VNU-UET Repository: No conditions. Results ordered -Date Deposited. 2023-01-29T05:55:34ZEPrintshttp://eprints.uet.vnu.edu.vn/images/sitelogo.pnghttps://eprints.uet.vnu.edu.vn/eprints/2022-10-26T21:59:46Z2022-10-26T21:59:46Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4164This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41642022-10-26T21:59:46ZFormation and Study of Nanostructured M-Monolayers and LS-Films of TriphenylcorroleThao T. VuLarissa A. MaiorovaDmitrii B. BerezinOskar I. Koifman2022-09-20T15:38:19Z2022-09-20T15:38:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4772This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47722022-09-20T15:38:19ZModified Fluoroquinolones as Antimicrobial Compounds Targeting Chlamydia trachomatisThi Huyen VuErika AdhelKatarina VielfortNgûyet-Thanh Ha DuongGuillaume AnquetinKaty JeannotPhilippe VerbekeSofia HjalmarÅsa GylfeNawal Serradji2022-08-22T04:06:17Z2022-08-22T04:06:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4773This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47732022-08-22T04:06:17ZVortex particle method with iterative Brinkman penalization for simulation of flow past sharp-shape bodiesThis paper presents a Lagrangian vortex method combined with iterative Brinkman penalization for the simulation of incompressible flow past a complex geometry. In the proposed algorithm, particle and penalization domains are separately introduced. The particle domain is for the computation of particle convection and diffusion, while the penalization domain is the enforcement of the wall boundary conditions. In iterative Brinkman penalization, the no-slip boundary condition is enforced by applying penalization force in multiple times within each time step. This enables large time step size reducing computational cost and maintains the capability in handling complex geometries. The method is validated for benchmark problems such as an impulsively started flow past a circular cylinder, normal to a flat plate, and a symmetric airfoil at Reynolds numbers ranging from 550 to 1000. The vorticity and streamline contours, drag, and lift coefficients show a good agreement with those reported in literature.Dung Duong Vietduongdv@vnu.edu.vnZuhal Lavi Rizki2022-08-22T04:06:13Z2022-08-22T04:06:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4768This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47682022-08-22T04:06:13ZCarbon Fibers from Cellulosic Precursor for Thermal Insulation:
An Insight Into the Effect of Stabilization and Carbonization
Conditions on the SynthesisThere is an increasing demand for lightweight composites reinforced with carbon fibers (CFs) that
possess exceptional thermal characteristics, especially at high-temperature conditions. The focus of this study
is primarily on the sequence of structural changes at the micro-nano level during the carbonization of cellulosic fibers collected from Northern Vietnam. The impact of various operational parameters in the carbonization process such as the heating temperature and the stabilization process also discussed. The chemical
structure, morphology, and thermal conductivity of cellulose-based fiber were investigated. This investigation revealed that prepared CF-3 using cellulosic fibers collected from Northern Vietnam through the optimized parameters can be a potentials material for making outer ring insulation in high-temperature furnace
environments.Khanh.S.T Trantransikhanh.2012@gmail.comNang Dinh NguyenPhuong Hoai Nam Nguyennamnph@vnu.edu.vnVan Minh NguyenGovindan Suresh KumarHuynh Nguyen2022-08-22T04:06:08Z2022-08-22T04:06:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4765This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47652022-08-22T04:06:08ZAutomatic scan range for dose-reduced multiphase CT imaging of the liver utilizing CNNs and Gaussian modelsMultiphase CT scanning of the liver is performed for several clinical applications; however, radiation exposure from CT scanning poses a nontrivial cancer risk to the patients. The radiation dose may be reduced by determining the scan range of the subsequent scans by the location of the target of interest in the first scan phase. The purpose of this study is to present and assess an automatic method for determining the scan range for multiphase CT scans. Our strategy is to first apply a CNN-based method for detecting the liver in 2D slices, and to use a liver range search algorithm for detecting the liver range in the scout volume. The target liver scan range for subsequent scans can be obtained by adding safety margins achieved from Gaussian liver motion models to the scan range determined from the scout. Experiments were performed on 657 multiphase CT volumes obtained from multiple hospitals. The experiment shows that the proposed liver detection method can detect the liver in 223 out of a total of 224 3D volumes on average within one second, with mean intersection of union, wall distance and centroid distance of 85.5%, 5.7 mm and 9.7 mm, respectively. In addition, the performance of the proposed liver detection method is comparable to the best of the state-of-the-art 3D liver detectors in the liver detection accuracy while it requires less processing time. Furthermore, we apply the liver scan range generation method on the liver CT images acquired from radiofrequency ablation and Y-90 transarterial radioembolization (selective internal radiation therapy) interventions of 46 patients from two hospitals. The result shows that the automatic scan range generation can significantly reduce the effective radiation dose by an average of 14.5% (2.56 mSv) compared to manual performance by the radiographer from Y-90 transarterial radioembolization, while no statistically significant difference in performance was found with the CT images from intra RFA intervention ( = 0.81). Finally, three radiologists assess both the original and the range-reduced images for evaluating the effect of the range reduction method on their clinical decisions. We conclude that the automatic liver scan range generation method is able to reduce excess radiation compared to the manual performance with a high accuracy and without penalizing the clinical decision.Manh Ha Luuhalm@vnu.edu.vnTheo van WalsumHong Son MaiDaniel FranklinThi Thu Thao NguyenThi My LeAdraan MoelkerVan Khang LeDang Luu VuNgoc Ha LeQuoc Long Trantqlong@vnu.edu.vnDuc Trinh Chutrinhcd@vnu.edu.vnLinh Trung Nguyenlinhtrung@vnu.edu.vn2022-08-22T03:59:25Z2022-08-22T03:59:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4714This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47142022-08-22T03:59:25ZModified Savonius Wind Turbine for Wind Energy Harvesting in Urban EnvironmentsAnh Dinh Leanh.ld@vnu.edu.vnDuc Minh BanhHoang Van TamTran The Hung2022-08-22T03:57:57Z2022-08-22T03:57:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4750This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47502022-08-22T03:57:57ZMachine Learning and Remote Sensing Application for Extreme Climate Evaluation: Example of Flood Susceptibility in the Hue Province, Central Vietnam RegionFloods are the most frequent natural hazard globally and incidences have been increasing in recent years as a result of human activity and global warming, making significant impacts on people’s livelihoods and wider socio-economic activities. In terms of the management of the environment and water resources, precise identification is required of areas susceptible to flooding to support planners in implementing effective prevention strategies. The objective of this study is to develop a novel hybrid approach based on Bald Eagle Search (BES), Support Vector Machine (SVM), Random Forest (RF), Bagging (BA) and Multi-Layer Perceptron (MLP) to generate a flood susceptibility map in Thua Thien Hue province, Vietnam. In total, 1621 flood points and 14 predictor variables were used in this study. These data were divided into 60 for model training, 20 for model validation and 20 for testing. In addition, various statistical indices were used to evaluate the performance of the model, such as Root Mean Square Error (RMSE), Receiver Operation Characteristics (ROC), and Mean Absolute Error (MAE). The results show that BES, for the first time, successfully improved the performance of individual models in building a flood susceptibility map in Thua Thien Hue, Vietnam, namely SVM, RF, BA and MLP, with high accuracy (AUC > 0.9). Among the models proposed, BA-BES was most effective with AUC = 0.998, followed by RF-BES (AUC = 0.998), MLP-BES (AUC = 0.998), and SVM-BES (AUC = 0.99). The findings of this research can support the decisions of local and regional authorities in Vietnam and other countries regarding the construction of appropriate strategies to reduce damage to property and human life, particularly in the context of climate change.Minh Cuong HaPhuong Lan VuHuu Duy NguyenTich Phuc HoangDinh Duc DangThi Bao Hoa DinhGheorghe ŞerbanIoan RusPetre Brețcan2022-08-22T03:57:22Z2022-08-22T03:57:22Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4743This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47432022-08-22T03:57:22ZMulti-level just-enough elasticity for MQTT brokers of Internet of Things applicationsApplications for the Internet of Things (IoT) are rapidly having an impact on all areas of daily life. Every day, its embedded devices generate loads of data that requires efficient network infrastructure. The integration of lightweight communication protocols such as Message Queuing Telemetry Transport (MQTT) is to send millions of IoT messages back and forth with as few errors as possible. In practice, IoT big data analytic systems are often deployed with highly regarded MQTT solutions to handle huge amounts of dynamic data and achieve scalability. However, these solutions do not adapt well to fluctuations in workload, so they are not elastic yet. This article introduces a novel framework that provides just-enough elasticity for MQTT brokers with multiple levels of virtualization and its implementation using EMQX MQTT broker, Kubernetes container-orchestration system and OpenStack cloud environment. Various experiments based on a real life IoT application are conducted to validate our proposed framework and its elastic functionality.Manh Linh Phamlinhmp@vnu.edu.vnNguyen Tuan Thanh Lethanhlnt@tlu.edu.vnXuan Truong Nguyennguyenxuantruong@hpu2.edu.vn2022-08-22T03:57:06Z2022-08-22T03:57:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4737This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47372022-08-22T03:57:06ZGenome-Wide Identification and Analysis of Genes Encoding
Putative Heat Shock Protein 70 in Papaya (Carica papaya)Background and Objective: In high plants, the 70 kDa heat stress proteins (Hsp70-s) have been regarded as one of the vital components
of the cellular network of chaperones and folding catalysts that play important roles in numerous biological processes during growth and
development. The Hsp70 families have been reported in many plant species, unfortunately, no information on this important protein
family in papaya (Carica papaya). The objective of this study was to provide comprehensive information on the CpHsp70 family in papaya.
Materials and Methods: The CpHsp70 genes in the papaya genome were identified by a basic local alignment search tool against the
papaya genome database by using well-known Arabidopsis Hsp70-s. Sequences were then analyzed by various bioinformatics tools to
investigate the characteristics of the CpHsp70 family. Results: A total of 12 members of the CpHsp70 family has been identified and
characterized in papaya. By using various computational tools, these results revealed that all general characteristics of the CpHsp70 family,
like physic-chemical parameters, gene structure, phylogenetic tree and subcellular localization were provided. The transcriptome atlas
was applied to re-analyze the expression patterns of genes encoding the CpHsp70 family in major tissues/organs during the growth and
development of papaya plants. Conclusion: Results from this work exhibited the characteristics and expression analysis of the CpHsp70
genes of this important tropical fruit crop. Taken together, this study could provide a solid foundation of the CpHsp70 family, which will
be helpful in the construction of stress tolerance in papaya plantsThi Man LeThi Thanh Huyen TranXuan Quyen VuDuc Ha Chucd.ha@vnu.edu.vnChau Thuy PhamThi Ngoc Quynh LeViet Hong Lalaviethong.sp2@gmail.comPhi Bang Cao2022-08-19T05:36:10Z2022-08-19T05:36:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4733This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47332022-08-19T05:36:10ZLow-Reynolds-number wake of three tandem elliptic cylindersThe flow around three elliptic cylinders with equal spacing and aspect ratio in tandem arrangements was numerically investigated through direct numerical simulation. The spacing ratio (L/D, where D and L are the major axis and the center-to-center distance of two adjacent elliptic cylinders, respectively) ranging from 1.5 to 10 and the Reynolds numbers ofDuong Viet Dungduongdv@vnu.edu.vnNguyen Van DucNguyen Van TienNgo Ich Long2022-08-19T05:35:51Z2022-08-19T05:35:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4731This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47312022-08-19T05:35:51ZSWEET Gene Family in Sugar Beet (Beta vulgaris): Genome-Wide
Survey, Phylogeny and Expression AnalysisBackground and Objective: The SWEET (Sugars Will Eventually be Exported Transporter) proteins play important roles in modulating
the growth and development processes in plants. However, little information is available on the SWEET family in sugar beet
(Beta vulgaris). The objectives of this present study were to genome-wide identify and characterize the BvSWEET family in sugar beet.
Materials and Methods: Based on the available genome, proteome and transcriptome databases of sugar beet, various computational
tools have been used to analyze the nucleotide and full-length protein sequences of members of the BvSWEET family. Results: A total
of 16 members of the BvSWEET family has been identified in sugar beet at the genome-wide scale. Structural analysis indicated that the
BvSWEET family exhibited variable characteristics. Furthermore, the BvSWEET family in sugar beet could be categorized into four distinct
groups like in other plant species. Of our interest, we found that some BvSWEET genes exhibited strongly preferential expression in major
organs/tissues under adverse environmental stimuli. Conclusion: The results provided a comprehensive foundation for further functional
characterization of the BvSWEET gene family.Viet Hong Lalaviethong.sp2@gmail.comDuc Ha Chucd.ha@vnu.edu.vnThi Quyen Haquyenht@vnu.edu.vnThi Thanh Huyen TranVan Hai TongVan Tien TranThi Ngoc Quynh LeThi Thu Huong BuiPhi Bang Cao2022-08-19T05:35:42Z2022-08-19T05:35:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4729This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47292022-08-19T05:35:42ZDesign of a low-cost pressure measurement device: validation and testingTran The HungNguyen DungAnh Dinh Leanh.ld@vnu.edu.vn2022-03-21T00:46:35Z2022-03-21T00:46:35Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4711This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47112022-03-21T00:46:35ZMisspecified Cramer–Rao Bounds for Blind Channel Estimation Under Channel Order MisspecificationIn estimation, the misspecified Cramer–Rao bound (MCRB), which is an extension of the well-known Cramer–Rao bound (CRB) when the underlying system model is misspecified, has recently attracted much attention. In this paper, we introduce a new interpretation of the MCRB, called the generalized MCRB (GMCRB), via the Moore–Penrose inverse operator. This bound is useful for singular problems and particularly blind channel estimation problems in which the Hessian matrix is noninvertible. Two closed-form expressions of the GMCRB are derived for unbiased blind estimators when the channel order is misspecified. The first bound deals with deterministic models where both the channel and unknown symbols are deterministic. The second one is devoted to stochastic models where we assume that transmitted symbols are unknown random variables i.i.d. drawn from a Gaussian distribution. Two case studies of channel order misspecification are investigated to demonstrate the effectiveness of the proposed GMCRBs over the classical CRBs. When the channel order is known or accurately estimated, both generalized bounds reduce to the classical bounds. Besides, the stochastic GMCRB is lower than the deterministic one, especially at high SNR.Trung Thanh Leletrungthanhtbt@gmail.comAbed Meraim Karimkarim.abed-meraim@univ-orleans.frLinh Trung Nguyenlinhtrung@vnu.edu.vn2022-03-21T00:32:31Z2022-03-21T00:32:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4715This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47152022-03-21T00:32:31ZAssessment of Flow Fluctuation Pressure Models for Simulating the Cavitating FlowAnh Dinh Leanh.ld@vnu.edu.vnLinh Ngoc LeAnh Viet TruongHung The Tran2022-03-21T00:32:15Z2022-03-21T00:32:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4713This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/47132022-03-21T00:32:15ZInsights into the gene and protein structures of the CaSWEET family members in chickpea (Cicer arietinum), and their gene expression patterns in different organs under various stress and abscisic acid treatments‘Sugars Will Eventually be Exported Transporters’ (SWEETs) are a group of sugar transporters that play crucial roles in various biological processes, particularly plant stress responses. However, no information is available yet for the CaSWEET family in chickpea. Here, we identified all putative CaSWEET members in chickpea, and obtained their major characteristics, including physicochemical patterns, chromosomal distribution, subcellular localization, gene organization, conserved motifs and three-dimensional protein structures. Subsequently, we explored available transcriptome data to compare spatiotemporal transcript abundance of CaSWEET genes in various major organs. Finally, we studied the changes in their transcript levels in leaves and/or roots following dehydration and exogenous abscisic acid treatments using RT-qPCR to obtain valuable information underlying their potential roles in chickpea responses to water-stress conditions. Our results provide the first insights into the characteristics of the CaSWEET family members and a foundation for further functional characterizations of selected candidate genes for genetic engineering of chickpea.Viet Hong Lalaviethong.sp2@gmail.comDuc Ha Chucd.ha@vnu.edu.vnDuy Cuong TranHuu Nguyen KienThi Ngoc Quynh LeThi Hien Lelehien@vnu.edu.vnPhi Bang CaoDuc Bach NguyenQuoc Trung NguyenHuy Hàm Lêlhham@agi.ac.vnPhan Lam Son TranVan Loc Nguyennvloc@vnua.edu.vnCong Tuyen Anh PhamVan Chien HaMinh Chinh HoangDuc Thao Le2021-12-13T03:53:43Z2021-12-13T03:53:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4633This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46332021-12-13T03:53:43ZMagnetic and electrical properties of Ni‑doped Ba(Ti0.8Zr0.2)O3
materialsIn this work, Ni-doped lead-free ferroelectric Ba(Ti0.8Zr0.2)O3 materials were well synthesized by a simple chemical route. The complex magnetic behavior of the materials was explained by the random distribution of Ni cations into the Ba(Ti0.8Zr0.2)O3 host lattice. As increasing the Ni concentration to 9 mol%, nonlinear electric polarization behavior remained unchanged in the Ba(Ti0.8Zr0.2)O3 materials. The observations in nonlinear magnetization and electric polarization in Ni-doped Ba(Ti0.8Zr0.2)O3 materials suggested an extension of new material functions to the development of advanced materials for electronic devices.Dang Co Nguyencond@vnu.edu.vn2021-12-10T10:55:34Z2021-12-10T10:55:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4632This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46322021-12-10T10:55:34ZStudy of Thermodynamic Effect on the Mechanism of Flashing Flow under Pressurized Hot Water by a Homogeneous ModelAnh Dinh Leanh.ld@vnu.edu.vn2021-12-10T01:12:16Z2021-12-10T01:12:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4645This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46452021-12-10T01:12:16ZA Proactive Method of the Webshell Detection and Prevention based on Deep Traffic AnalysisThe popularity of today's web application has led to web servers are frequently objects to injecting webshell attacks. In this paper, we propose a new deep inspection method, namely DLWD, to detect in real-time and proactively prevent webshell attacks. DLWSD is composed of both signature-based and DNN deep learning-based detection. Moreover, to avoid bottlenecks, DLWSD built-in DeepInspector inspects in real-time the large-scale traffic flows with a strategy of periodic sampling at a defined frequency and interval for only flows that do not satisfy any signature. DeepInspector can create/update rules from webshell attacking alert results to prevent in future. We also proposed a mechanism using the cross-entropy loss function to regulate the training imbalanced dataset. Our experiments allow validating the performance of DLWSD using a popular dataset CSE-CIC-IDS2018 with the metrics (Accuracy, F1-score, FPR) of (99.99%, 99.98%, 0.01%) respectively. It is also better compared with other studies using the same dataset.Viet Ha Lelevietha@chinhphu.vnPhuong Hanh Duhanhdp@vnu.edu.vnNgoc Cuong Nguyencuongnn.hvan@gmail.comNgoc Hoa Nguyenhoa.nguyen@vnu.edu.vnViet Long Hoanglonghv08@gmail.com2021-11-27T02:35:03Z2021-11-27T02:35:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4631This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46312021-11-27T02:35:03ZImprovement of Mass Transfer Rate Modeling for Prediction of Cavitating FlowAnh Dinh Leanh.ld@vnu.edu.vnTran The Hung2021-11-27T02:34:37Z2021-11-27T02:34:37Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4630This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46302021-11-27T02:34:37ZExperimental study of the skin-friction topology around the Ahmed body in cross-wind conditionTran The HungAnyoji MasayukiNakashima TakujiShimizu KeigoAnh Dinh Leanh.ld@vnu.edu.vn2021-11-27T02:33:03Z2021-11-27T02:33:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4654This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46542021-11-27T02:33:03ZMigSpike: A Migration Based Algorithms and Architecture for Scalable Robust Neuromorphic SystemsWhile conventional hardware neuromorphic systems usually consist of multiple clusters of neurons that communicate via an interconnect infrastructure, scaling up them confronts the reliability issue when faults in the neuron circuits and synaptic weight memories can cause faulty outputs. This work presents a method named MigSpike that allows placing spare neurons for repairing with the support of enhanced migrating methods and the built-in hardware architecture for migrating neurons between nodes (clusters of neurons). MigSpike architecture supports migrating the unmapped neurons from their nodes to suitable ones within the system by
creating chains of migrations. Furthermore, a max-ﬂow min-cut adaptation and a genetic algorithm approach are presented to solve the aforementioned problem. The evaluation results show that the proposed methods support recovery up to 100% of spare neurons. While the max-ﬂow min-cut adaption can execute milliseconds, the genetic algorithm can help reduce the migration cost with a graceful degradation on communication cost. With a system of 256 neurons per node and a 20% fault rate, our approach minimizes the migration cost from remapping by 10.19× and 96.13× under Networks-on-Chip of 4×4 (smallest) and 16×16×16 (largest), respectively. The Mean-Time-to-Failure evaluation also shows an approximate 10× of lifetime expectancy by having a 20% spare rate.Nam Khanh Dangdnk0904@gmail.comNguyen Anh Vu DoanAbderazek Ben Abdallahbenab@u-aizu.ac.jp2021-11-27T02:28:54Z2021-11-27T02:28:54Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4636This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46362021-11-27T02:28:54ZThe effects of substrates on growth and green coverage of Blue daze (Evolvulus glomeratus) under rooftop conditionEstablishment of the green space in urban environment has been regarded as one of the major strategies for the development
of green cities. In this study, we provided experimental evidence for the uses of biochar-based substrates for the growth and
development of blue daze (Evolvulus glomeratus) plants under the rooftop condition. We frstly analyzed the physical features
of four common substrates, including 100% soil, soil+rice hull+coconut fber (2:1:1), soil+coconut fber+rice hull+coal
slag (1:1:1:1) and soil+coconut fber+rice hull+coal slag (1:2:2:1) to gain an advantages under the rooftop condition.
Subsequently, the evaluation of the growth and development of the blue daze (Evolvulus glomeratus) in four formulas under
the rooftop condition was investigated. Among them, the use of soil+coconut fber+rice hull+coal slag (1:1:1:1) exhibited
the highest values of growth dynamics and green coverage. Additionally, the efects of three thicknesses (5, 8, and 12 cm)
of a selected formula were tested under the rooftop condition. The results revealed that the surface area of green coverage
exhibited the highest value, by 1964.13 cm2
at 90 days after planting in a depth layer of 8 cm. Taken together, our study could
provide a solid foundation for further cultivation of blue daze plants under the rooftop condition.Anh Duc NguyenHa Duc ChuVan Loc Nguyen2021-11-16T04:37:59Z2021-11-16T04:37:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4647This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46472021-11-16T04:37:59ZCircall: fast and accurate methodology for discovery of circular RNAs from paired-end RNA-sequencing dataDat Thanh NguyenQuang Thinh TracThi-Hau Nguyenhaunt@vnu.edu.vnHa-Nam NguyenNir OhadYudi PawitanTrung Nghia Vu2021-11-16T04:36:51Z2021-11-16T04:36:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4644This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46442021-11-16T04:36:51ZAn Efficient Hybrid Webshell Detection Method for Webserver of Marine Transportation SystemsAn increase in the number of Maritime Intelligent Transport Systems (MITSs) also means an increase in the number of information security risks. Usually, the administration and operation of MITSs are done through web servers that are frequently targeted by hackers. In marine transportation industry, malicious code injection attacks (webshell) has been widely exploited by hackers to take full control of Web servers. Traditional webshell detection methods based on pattern matching that are no longer effective against new types of webshell. This motivates us to investigate the problem of detecting obfuscation or unknown webshells, termed OUW problem. In this work, we propose a pattern-matching-deep-learning hybrid ASP.NET webshell detection method (H-DLPMWD) to address the OUW problem. H-DLPMWD is based on Yara-based pattern matching to clean dataset; modeling ASP.NET code files as an operation code index (OCI) vectors; and applying CNN method to train and predict webshell in OCI vectors. To validate H-DLPMWD, our rigorous experimentation demonstrates that H-DLPMWD achieves an excellent accuracy of 98.49%, F1-score of 99.01%, and a low false positive rate of 1.75%.Viet Ha Lelevietha@chinhphu.vnNgoc Tu Nguyentu.nguyen@kennesaw.eduNgoc Hoa Nguyenhoa.nguyen@vnu.edu.vnLinh Lelle13@kennesaw.edu2021-10-31T00:45:47Z2021-10-31T00:45:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4559This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45592021-10-31T00:45:47ZStudy of Thermodynamic Effect on the Mechanism of Flashing Flow under Pressurized Hot Water by a Homogeneous ModelThe flashing flow in a Moby_Dick converging-diverging nozzle under pressurized hot water from 460.5 K to 483.5 K is simulated using a homogeneous compressible water-vapor two-phase flow model. The kinematic and thermodynamic mass transfer are accessed using the cavitation model based on the Hertz-Knudsen-Langmuir equation. Our simplified thermodynamic model is coupled with the governing equations to capture the phase-change heat transfer. This numerical method proved its reliability through a comparison with available experimental data of flow parameters inside the nozzle. Consequently, the present numerical method shows good potential for simulating the flashing flow under pressurized hot water conditions. The satisfying prediction of averaged flow parameters with a slight improvement compared to reference numerical data is reproduced. The results confirm a noticeable impact of the thermodynamic effect on the mechanism of flashing flow, resulting in a considerable decrease in the flow temperature and the saturated vapor pressure. The flashing non-equilibrium is significantly decreased, forcing the flashing flow to be classified as the usual cavitation behavior and better suited to homogeneous model. While the temperature drop is highly dependent on evaporation, the thermodynamic suppression is influenced by the condensation. The suppression effect, unobserved in water at a lower temperature in previous studies, is noticeable for the pressurized hot water flow characterized by the cavitation mechanism. The vapor void fraction decreased considerably in the radial and axial directions as the water temperature rose to 483.5 K in this study.Anh Dinh Leanh.ld@vnu.edu.vn2021-10-31T00:44:38Z2021-10-31T00:44:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4622This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46222021-10-31T00:44:38ZIterative Learning Sliding Mode Control for UAV Trajectory TrackingThis paper presents a novel iterative learning sliding mode controller (ILSMC) that can be applied to the trajectory tracking of quadrotor unmanned aerial vehicles (UAVs) subject to model uncertainties and external disturbances. Here, the proposed ILSMC is integrated in the outer loop of a controlled system. The control development, conducted in the discrete-time domain, does not require a priori information of the disturbance bound as with conventional SMC techniques. It only involves an equivalent control term for the desired dynamics in the closed loop and an iterative learning term to drive the system state toward the sliding surface to maintain robust performance. By learning from previous iterations, the ILSMC can yield very accurate tracking performance when a sliding mode is induced without control chattering. The design is then applied to the attitude control of a 3DR Solo UAV with a built-in PID controller. The simulation results and experimental validation with real-time data demonstrate the advantages of the proposed control scheme over existing techniques.Van Lanh NguyenManh Duong Phungduongpm@vnu.edu.vnHa Quangquang.ha@uts.edu.au2021-10-31T00:44:02Z2021-10-31T00:44:02Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4627This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46272021-10-31T00:44:02ZImprovement of Mass Transfer Rate Modeling for Prediction of Cavitating FlowAnh Dinh Leanh.ld@vnu.edu.vnHung The Tran2021-10-31T00:43:14Z2021-10-31T00:43:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4624This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46242021-10-31T00:43:14ZFuzzy-Based Distributed Behavioral Control With Wall-Following Strategy for Swarm Navigation in Arbitrary-Shaped EnvironmentsTruong NhuPham Duy HungVan Anh HoTrung Dung Ngo2021-10-31T00:42:10Z2021-10-31T00:42:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4611This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46112021-10-31T00:42:10ZCharacteristics of the flow around four cylinders of various shapesNguyen Van Lucnguyenvanluc@tdtu.edu.vnTrung Nguyen-ThoiDuong Viet Dungduongdv@vnu.edu.vn2021-10-31T00:41:45Z2021-10-31T00:41:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4599This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45992021-10-31T00:41:45ZExperimental study of the skin-friction topology around the Ahmed body in cross-wind conditionTran The HungAnyoji MasayukiNakashima TakujiShimizu KeigoAnh Dinh Leanh.ld@vnu.edu.vn2021-10-31T00:40:05Z2021-10-31T00:40:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3621This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36212021-10-31T00:40:05ZNumerical simulation study of cavitation in liquefied hydrogenAnh Dinh Leanh.ld@vnu.edu.vnJunnosuke OkajimaYuka Iga2021-10-15T02:48:25Z2021-10-15T02:48:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4619This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46192021-10-15T02:48:25ZA Variability Fault Localization Approach for Software Product LinesSoftware fault localization is one of the most expensive, tedious, and time-consuming activities in program debugging. This activity becomes even much more challenging in Software Product Line (SPL) systems due to variability of failures. These unexpected behaviors are induced by variability faults which can only be exposed under some combinations of system features. The interaction among these features causes the failures of the system. Although localizing bugs in single-system engineering has been studied in-depth, variability fault localization in SPL systems still remains mostly unexplored. In this article, we present VarCop, a novel and effective variability fault localization approach. For an SPL system failed by variability bugs, VarCop isolates suspicious code statements by analyzing the overall test results of the sampled products and their source code. The isolated suspicious statements are the statements related to the interaction among the features which are necessary for the visibility of the bugs in the system. In VarCop, the suspiciousness of each isolated statement is assessed based on both the overall test results of the products containing the statement as well as the detailed results of the test cases executed by the statement in these products. On a large public dataset of buggy SPL systems, our empirical evaluation shows that VarCop significantly improves two state-of-the-art fault localization techniques by 33% and 50% in ranking the incorrect statements in the systems containing a single bug each. In about two-thirds of the cases, VarCop correctly ranks the buggy statements at the top-3 positions in the resulting lists. Moreover, for the cases containing multiple bugs, VarCop outperforms the state-of-the-art approaches 2 times and 10 times in the proportion of bugs localized at the top-1 positions. Especially, in 22% and 65% of the buggy versions, VarCop correctly ranks at least one bug in a system at the top-1 and top-5 positions.Thu Trang Nguyentrang.nguyen@vnu.edu.vnKien Tuan NgoVan Son Nguyensonnguyen@vnu.edu.vnDinh Hieu Vohieuvd@vnu.edu.vn2021-10-15T02:47:39Z2021-10-15T02:47:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4617This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46172021-10-15T02:47:39ZTowards a Framework for High-Performance Simulation of Livestock Disease Outbreak: A Case Study of Spread of African Swine Fever in VietnamThe spread of disease in livestock is an important research topic of veterinary epidemiology because it provides warnings or advice to organizations responsible for the protection of animal health in particular and public health in general. Disease transmission simulation programs are often deployed with different species, disease types, or epidemiological models, and each research team manages its own set of parameters relevant to their target diseases and concerns, resulting in limited cooperation and reuse of research results. Furthermore, these simulation and decision support tools often require a large amount of computational power, especially for models involving tens of thousands of herds with millions of individuals spread over a large geographical area such as a region or a country. It is a matter of fact that epidemic simulation programs are often heterogeneous, but they often share some common workflows including processing of input data and execution of simulation, as well as storage, analysis, and visualization of results. In this article, we propose a novel architectural framework for simultaneously deploying any epidemic simulation program both on premises and on the cloud to improve performance and scalability. We also conduct some experiments to evaluate the proposed architectural framework on some aspects when applying it to simulate the spread of African swine fever in Vietnam.Manh Linh Phamlinhmp@vnu.edu.vnNikos Parlavantzasnikos.parlavantzas@irisa.frHuy Hàm Lêlhham@agi.ac.vnQuang Hung Buihungbq@vnu.edu.vn2021-09-15T02:50:14Z2021-09-15T02:50:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4605This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46052021-09-15T02:50:14ZTowards an Elastic Fog Computing Framework for IoT Big Data Analytics ApplicationsIoT applications have been being moved to the cloud during the last decade in order to reduce operating costs and provide more scalable services to users. However, IoT latency-sensitive big data streaming systems (e.g., smart home application) is not suitable with the cloud and needs another model to fit in. Fog computing, aiming at bringing computation, communication, and storage resources from “cloud to ground” closest to smart end-devices, seems to be a complementary appropriate proposal for such type of application. Although there are various research efforts and solutions for deploying and conducting elasticity of IoT big data analytics applications on the cloud, similar work on fog computing is not many. This article firstly introduces AutoFog, a fog-computing framework, which provides holistic deployment and an elasticity solution for fog-based IoT big data analytics applications including a novel mechanism for elasticity provision. Secondly, the article also points out requirements that a framework of IoT big data analytics application on fog environment should support. Finally, through a realistic smart home use case, extensive experiments were conducted to validate typical aspects of our proposed framework.Manh Linh Phamlinhmp@vnu.edu.vnTruong Thang Nguyenntthang@ioit.ac.vnTien Quang Hoanghoangtienquang@hpu2.edu.vn2021-08-11T01:44:07Z2021-08-11T01:44:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4598This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45982021-08-11T01:44:07ZTurbulent energy cascade associated with viscous reconnection of two vortex ringsCollision of two vortex rings (VR) initially arranged in axis-offset and orthogonal configurations at Reynolds numbers (ReΓ ) in a range 5000−200 000 was simulated to investigate turbulent energy cascade associated with their reconnection. Two elliptical VRs are generated by joining each part of the first VR with another part of the second VR for the axis-offset collision. While two VRs associate to form a double U-shaped vortex, and this vortex reconnects itself at two points to form three elliptical VRs linked by the vortex filaments for the orthogonal collision. Many vortex structures in various scales and shapes, including small-scale VRs and horseshoe vortices, are observed in connection regions for both cases. As ReΓ increasing, the energy of formed small vortices raises and their wavenumber (k) range enlarges. The flow energy spectrum approaches a k−5/3 slope of the Kolmogorov hypotheses at low wavenumbers. For the axis-offset collision, the energy spectrum at medium wavenumbers continuously changes from k−3.0 at ReΓ = 5000 to k−1.8 at ReΓ =200 000, and the exponent (α) of the wavenumber is determined by a function as α = 0.3304ln(ReΓ ) − 5.6538. Meanwhile, the energy spectrum at two medium-wavenumber subranges for the orthogonal collision with ReΓ ≥ 20 000 approaches slopes of k−3.0 and k−2.6. Turbulent mixing performance due to the axis-offset collision of two vortex rings is better than that with the orthogonal one.Nguyen Van LucPhan Toai TuynDuong Viet Dungduongdv@vnu.edu.vnLe Nam Tuan Phuong2021-08-11T01:40:59Z2021-08-11T01:43:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4589This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45892021-08-11T01:40:59ZFractional Frequency Reuse in Ultra Dense NetworksUltra Dense Network (UDN) in which Base Stations (BSs) are deployed at an ultra high density is a promising network model of the future wireless generation. Due to ultra densification, reuse of frequency bands with an ultra high density is compulsory for this network. Conventionally, the research on frequency reuse technique such as Fractional Frequency Reuse (FFR) classifies the active users into only two groups. However, this approach is not suitable for UDNs where the signal experiences a huge amount of power loss over distances. Thus, this paper proposes a generalized model of FFR for UDNs where the active users are classified into more than two groups The paper introduces a simple approach to obtain the coverage probability of a typical user in the case of a general path loss model. In the case of stretched path loss model for UDNs, the closed-form expression of user coverage probability is derived. From the analytical and simulation results, it is stated that the proposed model can improve user performance without increasing BS power consumption. Furthermore, two additional interesting conclusions are found in this paper: (i) the user coverage probability increases to a peak before passing a decline when the density of BSs increases; (ii) an increase in BS transmission power may decrease the user performance.Sinh Cong Lamcongls@vnu.edu.vnXuan Nam Tran2021-08-11T01:40:39Z2021-08-11T01:57:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4571This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45712021-08-11T01:40:39ZA course recommendation model for students based on learning outcomeHow to choose the most appropriate courses to study throughout the learning process remains a question interested in by many students. Students often choose suitable courses according to their interests, needs, and advice from supporting staff, etc. This paper presents the results in developing a course recommendation system that will select appropriate courses for each student studying a major in the following semesters based on his/her current academic performance. We have applied several techniques based on data mining and learning analytics to predict students’ learning outcomes in the next semester and developed a model to select the appropriate courses based on such a recommendation system. Besides, our study has focused on comparing the effectiveness of predictive learning methods based on collaborative filtering. Experiments analyzed the learning results of 510 students who enrolled in the courses from 2015 to 2019 and showed that the Matrix Factorization method is the most effective. Also, the paper has proposed procedures and constraints applicable to different training curricula.Viet Anh Nguyenvietanh@vnu.edu.vnHoa-Huy Nguyenhuynguyen@vnu.eduvnDuc-Loc Nguyen17020871@vnu.edu.vnMinh-Duc Leduclm@vnu.edu.vn2021-07-15T02:04:40Z2021-07-15T02:04:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4565This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45652021-07-15T02:04:40ZSimulation-based invariant verification technique for the OTS/CafeOBJ methodWe demonstrate the power of the simulation-based invariant verification technique through two case studies in which it is formally verified that two mutual exclusion protocols, MCS protocol and Anderson protocol, enjoy the mutual exclusion property by the simulation-based invariant verification technique. We initially attempted formally verifying that the two protocols enjoy the property by the induction-based invariant verification technique. We successfully completed the formal proof for MCS protocol by the simulation-based invariant verification technique earlier than the one by the induction- based invariant verification technique even though we started the latter earlier than the former. We did not successfully complete the formal proof for Anderson protocol by the induction-based invariant verification technique as of the time of this paper submission. We define a variant of simulation, "observably equivalent simulations," and prove some theorems on them to conduct the MCS case study. Given a state machine M, another state machine M' constructed by introducing auxiliary variables into M observably equivalently simulates M. In this sense, M' can be regarded as an abstract version of M.Duong Tran Dinhduongtd@vnu.edu.vnDang Bui Duybddang@jaist.ac.jpKazuhiro Ogataogata@jaist.ac.jp2021-07-12T10:19:10Z2021-07-12T10:19:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4567This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45672021-07-12T10:19:10ZThe min-cost parallel drone scheduling vehicle routing problemAdopting unmanned aerial vehicles (UAV), also known as drones, into the last-mile-delivery
sector and having them work alongside trucks with the aim of improving service quality and
reducing the transportation cost gives rise to a new class of Vehicle Routing Problems (VRPs).
In this paper, we introduce a new optimization problem called the min-cost Parallel Drone
Scheduling Vehicle Routing Problem (PDSVRP). This problem is a variant of the well-known
Parallel Drone Scheduling Traveling Salesman Problem (PDSTSP) recently introduced in the
literature in which we allow multiple trucks and consider the objective of minimizing the total
transportation costs. We formulate the problem as a Mixed Integer Linear Program and then
develop a Ruin and Recreate (R&R) algorithm. Exploiting PDSVRP solution characteristics
in an effective manner, our heuristic manages to introduce \sufficient" rooms to a solution via
new removal operators during the ruin phase. It is expected to enhance the possibilities for
improving solutions later in the recreate phase. Multiple experiments on a new set of randomly
generated instances confirm the performance of our approach. To explore the benefits of drone
delivery as well as the insight into the impact of related factors on the contribution of drones’ use
to operational cost, a sensitivity analysis is conducted. We also adapt the proposed algorithm
to solve the PDSTSP and validate it via benchmarks available in the literature. It is shown that
our algorithm outperforms state-of-the-art algorithms in terms of solution quality. Out of 90
considered instances, it finds 26 new best known solutions.Minh Anh NguyenGiang Thi-Huong DangMinh Hoàng HàMinh Trien Phamtrienpm@vnu.edu.vn2021-06-28T16:41:15Z2021-06-28T16:41:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4541This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45412021-06-28T16:41:15ZIn-air particle generation by on-chip electrohydrodynamicsElectrohydrodynamic atomization has been emerging as a powerful approach for respiratory treatment, including the generation and delivery of micro/nanoparticles as carriers for drugs and antigens. In this work, we present a new conceptual design in which two nozzles facilitate dual electrospray coexisting with ionic wind at chamfered tips by a direct current power source. Experimental results by a prototype have demonstrated the capability of simultaneously generating-and-delivering a stream of charged reduced particles. The concept can be beneficial to pulmonary nano-medicine delivery since the mist of nanoparticles is migrated without any restriction of either the collector or the assistance of external flow, but is pretty simple in designing and manufacturing devices.Thanh Van Dauv.dau@griffith.edu.auThanh Tung Buitungbt@vnu.edu.vnCanh-Dung TranCanh-Dung.Tran@usq.edu.auThanh Viet Nguyenthanh.nguyenviet@griffithuni.edu.auTuan-Khoa Nguyenkhoa.nguyentuan@griffithuni.edu.auToan Dinhtoan.dinh@griffithuni.edu.auHoang-Phuong Phanphuong.phanhoang@griffithuni.edu.auDavid WibowoDavid.Wibowo@griffithuni.edu.auBernd H. A. Rehmb.rehm@griffith.edu.auHang Thu Tah.ta@griffith.edu.auNam-Trung Nguyennam-trung.nguyen@griffith.edu.auViet Dzung Daod.dao@griffith.edu.au2021-06-28T16:41:01Z2021-06-28T16:41:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4540This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45402021-06-28T16:41:01ZDevelopment of a Compact Electrical Impedance Measurement Circuit for Protein Detection Two-electrode Impedance Micro-sensorDevelopment of compact and low-cost electronic circuits in the biosensor field is an essential demand. Especially, the design of noise reduction sections plays an important role in the measurement of small biosensing signals. This study develops an electrical impedance measurement circuit board to apply in the protein pre-concentration and detection microfluidic chips with integrated two-electrode impedance micro-sensor. A lock-in amplifier is applied in the circuit board to measure the impedance profile in the frequency range 10–200 kHz. An investigation on several ratios of signal to noise (SNRs) is conducted to indicate the ability of the proposed design in eliminating noise signals. Subsequently, a total impedance and series capacitance-based analysis approach from the recorded impedance data is demonstrated to be suitable for this protein chip in the frequencies range from 10 to 200 kHz. The obtained results enable a potential method in point-of-care diagnostic applications.Quoc Tuan Vuvqtuan0211@gmail.comNgoc Viet Nguyenvietnn.mt@gmail.comBao Anh Hoanganhbh@vnu.edu.vnChun-Ping JenChun-Ping@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vn2021-06-28T02:40:28Z2021-06-28T02:40:28Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4149This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41492021-06-28T02:40:28ZElectrodeposited nickel–graphene nanocomposite
coating: effect of graphene nanoplatelet size on its
microstructure and hardnessIn this study, the effect of graphene nanoplatelet (GNP) size on the microstructure and hardness of the
electrodeposited nickel–graphene nanocomposite coatings were investigated. GNPs with different sizes
were prepared by using a high energy ball milling technique. The experimental result revealed the high
energy ball milling technique could reduce the size, increase the surface area, and improve the
dispersion ability of GNPs. The microstructure, hardness, and components of the nanocomposite
coatings were greatly affected by GNP sizes. The highest microhardness was measured to be 273 HV for
the nanocomposite coatings containing 5 h-milled GNPs, which is increased up to �47% compared to
pristine Ni coating. The enhancement in the hardness is attributed to the uniform dispersion of the small
GNP sizes inside the Ni matrix and the Ni grain size reduction when using milled GNPs.Phuong Hoai Nam Nguyennamnph@vnu.edu.vn2021-06-28T02:34:32Z2021-06-28T02:34:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4548This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45482021-06-28T02:34:32ZElectrodeposited nickel–graphene nanocomposite coating: influence of graphene nanoplatelet size on wear and corrosion resistanceIn this paper, we broaden our previous work, which investigated the influence of graphene nanoplatelets (GNPs) size on
microstructure and hardness of composite coatings, to determine the effect of GNP size on wear-resistance and anti-corrosion
property of GNP-reinforced nickel coating (Ni/GNPs). The experimental results indicated that the small GNP material size
could enhance the wear resistance for nickel composite coating with the wear rate of 13.2 × 10–
4 mm3/
Nm, the wear depth
of 17.69 μm. Meanwhile, the anti-corrosion property is enhanced significantly, this is shown via the low corrosion current
density (Icorr value of 1.16 × 10–
7 A/cm2) and the high corrosion potential (Ecorr value of − 0.1661 V). In addition, the mass
lost in salt fog testing is low with the weight of 12.3 mg, which decreased down to ~ 55.27% compared to pristine Ni coating.
These results are attributed to the uniform distribution of the small GNP size inside Ni matrix as well as the grain refinement
effect of composite coating when using the small GNP size.Van Hau TranVan Trinh PhamVan Tu NguyenNguyen Duc Duoc PhanThi Phuong MaiXuan Toan NguyenDinh Phuong DoanPhuong Hoai Nam Nguyennamnph@vnu.edu.vnDinh Lam VuNgoc Minh PhanHung Thang Buithangbh@ims.vast.vn2021-06-28T02:34:13Z2021-06-28T02:34:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4536This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45362021-06-28T02:34:13ZAir pollution in Vietnam during the COVID-19 social isolation, evidence of reduction in human activitiesTruong X. NgoNgoc T.N. DoHieu D.T. PhanVinh T. TranTra T.M. MacAnh H. LeNguyet V. DoHung Q. BuiThanh T.N. Nguyen2021-06-28T02:33:18Z2021-06-28T02:33:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4533This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45332021-06-28T02:33:18ZQMaker: Fast and Accurate Method to Estimate Empirical Models of Protein EvolutionAmino acid substitution models play a crucial role in phylogenetic analyses. Maximum likelihood (ML) methods have been proposed to estimate amino acid substitution models; however, they are typically complicated and slow. In this article, we propose QMaker, a new ML method to estimate a general time-reversible Q matrix from a large protein data set consisting of multiple sequence alignments. QMaker combines an efficient ML tree search algorithm, a model selection for handling the model heterogeneity among alignments, and the consideration of rate mixture models among sites. We provide QMaker as a user-friendly function in the IQ-TREE software package (http://www.iqtree.org) supporting the use of multiple CPU cores so that biologists can easily estimate amino acid substitution models from their own protein alignments. We used QMaker to estimate new empirical general amino acid substitution models from the current Pfam database as well as five clade-specific models for mammals, birds, insects, yeasts, and plants. Our results show that the new models considerably improve the fit between model and data and in some cases influence the inference of phylogenetic tree topologies.[Amino acid replacement matrices; amino acid substitution models; maximum likelihood estimation; phylogenetic inferences.Bui Quang Minhm.bui@anu.edu.auCao Cuong Dangcuongdc@vnu.edu.vnLe Sy Vinhvinhls@vnu.edu.vnRobert Lanfearrob.lanfear@anu.edu.au2021-06-28T02:28:49Z2021-06-28T02:28:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4525This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45252021-06-28T02:28:49ZEfficiently compressing 3D medical images for teleinterventions via CNNs and anisotropic diffusionHa Manh LuuTheo WalsumDaniel FranklinPhuong Cam PhamLuu Dang VuAdriaan MoelkerMarius StaringXiem VanHoangWiro NiessenNguyen Linh Trung2021-06-28T02:06:35Z2021-06-28T02:06:35Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4518This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45182021-06-28T02:06:35ZGenome‐Wide Association Mapping of Salinity Tolerance at the Seedling Stage in a Panel of Vietnamese Landraces Reveals New Valuable QTLs for Salinity Stress Tolerance Breeding in RiceRice tolerance to salinity stress involves diverse and complementary mechanisms, such as the regulation of genome expression, activation of specific ion‐transport systems to manage excess sodium at the cell or plant level, and anatomical changes that avoid sodium penetration into the inner tissues of the plant. These complementary mechanisms can act synergistically to improve sa‐ linity tolerance in the plant, which is then interesting in breeding programs to pyramidize comple‐ mentary QTLs (quantitative trait loci), to improve salinity stress tolerance of the plant at different developmental stages and in different environments. This approach presupposes the identification of salinity tolerance QTLs associated with different mechanisms involved in salinity tolerance, which requires the greatest possible genetic diversity to be explored. To contribute to this goal, we screened an original panel of 179 Vietnamese rice landraces genotyped with 21,623 SNP markers for salinity stress tolerance under 100 mM NaCl treatment, at the seedling stage, with the aim of identifying new QTLs involved in the salinity stress tolerance via a genome‐wide association study (GWAS). Nine salinity tolerance‐related traits, including the salt injury score, chlorophyll and water content, and K+ and Na+ contents were measured in leaves. GWAS analysis allowed the identifica‐ tion of 26 QTLs. Interestingly, ten of them were associated with several different traits, which indi‐ cates that these QTLs act pleiotropically to control the different levels of plant responses to salinity stress. Twenty‐one identified QTLs colocalized with known QTLs. Several genes within these QTLs have functions related to salinity stress tolerance and are mainly involved in gene regulation, signal transduction or hormone signaling. Our study provides promising QTLs for breeding programs to enhance salinity tolerance and identifies candidate genes that should be further functionally studied to better understand salinity tolerance mechanisms in rice.T.D. LeF. GathignolH.T. VuK.L. Nguyennl.khanh@vnu.edu.vnL.H. TranH.T.T. VuT.X. DinhF. LazennecX.H. PhamA.-A. VeryP. GantetG.T. Hoang2021-06-28T02:04:40Z2021-06-28T02:04:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4550This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45502021-06-28T02:04:40ZExploiting Social Networks as a Live Mass Media Channel
During Disasters for ReactionsMinh Tien Nguyentiennm@jaist.ac.jpTri Thanh Nguyenntthanh@vnu.edu.vnKitamoto AsanobuVan-Hau Nguyen2021-06-28T00:17:18Z2021-06-28T00:17:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4507This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45072021-06-28T00:17:18ZProxy-based Federated Authentication: A Transparent Third-party Solution for Cloud-Edge FederationCloud and Edge computing paradigms provide storage and computing services to the traditional and Internet of Things devices. In the past few years, the number IoT devices has increased exponentially and different devices have different requirements due to heterogeneity. Hence, one computing platform is not suitable to fulfill the requirements of all IoT devices. In this case, federation of different computing paradigms comes into play where a user or a device having an account on one computing platform can access the services provided by the other computing platform, federated with the first computing platform, without having to create another account. There are multiple research problems which arise due to the federation among which authentication is the most important one. This work addresses the third-party authentication problem in federated cloud and 3GPP edge systems where a user (first party) having an account on the cloud or edge (second party) needs to access services in the edge or cloud (third party). Related studies in the literature solve these issues by proposing new protocols or by adding new components in the 3GPP system. In this study, we propose the standard-compliant third-party authentication approach, which is the combination of the existing authentication protocols in the cloud and the 3GPP network. we use a federated proxy between cloud and the 3GPP network to solve the problem of message mismatch in the authentication protocols of cloud and edge. The experimental results illustrate that, as compared with the combination of OpenID Connect and EPS-AKA, third-party authentication of edge-to-cloud and cloud-to-edge using federated proxy can reduce the authentication delay time by 27.7% and 37.9% respectively and it is also standard compliant.Ying-Dar Linydlin@cs.nctu.edu.twDuc Tai Truongtaitd95@gmail.comYuan-Cheng Lailaiyc@cs.nctu.edu.twChiYu Lilichiyu@gmail.comAsad Aliali.eed06g@nctu.edu.twThi Thai Mai Dinhdttmai@vnu.edu.vn2021-06-21T07:08:05Z2021-06-21T07:08:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4166This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41662021-06-21T07:08:05ZNanostructured Stable Floating М-Mono- and Bilayers and Langmuir-Schaefer Films of 5,10,15-TriphenylcorroleLarissa A. MaiorovaThao T. VuOlga A. GromovaKonstantin S. NikitinOskar I. Koifman2021-06-21T07:07:54Z2021-06-21T07:07:54Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4167This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41672021-06-21T07:07:54ZAn Influence of Copper Cation in the Complex on Structure of the Nanostructured Layers, Spectral and Electrocatalytic Characteristics of Langmuir-Schaeffer Films of TriphenylcorroleNadezhda M. BerezinaThao T. VuNadezhda V. KharitonovaLarisa A. MaiorovaOskar I. KoifmanSergei V. Zyablov2021-06-21T07:06:26Z2021-06-21T07:06:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4500This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/45002021-06-21T07:06:26ZStructural evolution and magnetic properties of Bi0.86Nd0.14Fe1-xTixO3 ceramicsCeramic Bi0.86Nd0.14Fe1-xTixO3 (0.02 ≤ x ≤ 0.1) compounds were prepared to study the structural evolution, microstructure, and magnetic properties. The structural analysis by X-ray diffraction and Rietveld refinement revealed a coexistence of the polar rhombohedral (R3c symmetry) and antipolar orthorhombic (Pbam symmetry)
structures over the entire composition range, while Raman scattering spectroscopy detected not only the phonon
vibrations of the R3c and Pbam but also the Pbnm symmetries. The microstructure investigation showed the small
and large grain size regions corresponding to the R3c and Pbam/Pbnm phases, respectively. The dependence of
magnetization on the Ti concentration suggested that the weak ferromagnetism observed in the compounds arised from the intrinsic collapse of cycloidal order rather than defect-induced magnetism. The magnetic aging observed at room temperature was explained on the basic of phase switching and spin frustration at the phase boundary. The influence of phase switching induced by an external electric field on the magnetic properties was also studied to reveal the contribution of phase boundary spins to the net magnetization.Thi Minh Hong Nguyenhongntm@vnu.edu.vnDang Co Nguyencond@vnu.edu.vnThi Anh Hoanhht@vnu.edu.vnDinh Tu Buibuidinhtu@vnu.edu.vn2021-06-21T07:06:12Z2021-06-21T07:06:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4499This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44992021-06-21T07:06:12ZElectronic structure and multiferroic properties of (Y, Mn)-doped barium hexaferrite compoundsWe have systematically studied the crystal and electronic structures and the magnetic and electrical polarization properties of polycrystalline Ba0.95Y0.05Fe12−xMnxO19 (denoted as BaYFe12−xMnxO19) compounds with x = 0–2. The analyzes of X-ray diffraction patterns and Raman scattering spectra indicated their single phase in the M-type hexaferrite structure. With increasing x, the lattice constant a slightly increased while c decreased, which related to the Jahn-Teller effect. Though an increase of x reduced gradually magnetization in a range of 23–32 emu/g, the coercive force increased from 3.3 kOe for x = 0 to about 4 kOe for x = 0.5–2. The study of the electrical polarization properties proved the dependence of the shape of electric hysteresis loops on x and applied electric field. The samples with x = 0 and 0.5 exhibit a weak ferroelectricity with the maximum polarization of ~0.11 μC/cm2 for x = 0, and of ~0.06 μC/cm2 for x = 0.5. Meanwhile, the other samples showed nearly circular hysteresis loops, which are characteristic of conductive materials. Detailed investigations indicated an increase in leakage current when x increased. All of such phenomena are tightly related to the chemical shift of Mn2+ → Mn3+ and the replacement of Mn2+,3+ for Fe3+ in BaYFe12−xMnxO19. These oxidation states and the chemical shift of Mn have been confirmed upon analyzing X-ray absorption spectraDuc Thang Phampdthang@vnu.edu.vnDang Co Nguyencond@vnu.edu.vnThi Minh Hong Nguyenhongntm@vnu.edu.vnThi Anh Hoanhht@vnu.edu.vn2021-06-20T05:10:41Z2021-06-20T05:10:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4490This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44902021-06-20T05:10:41ZA Trellis Based Temporal Rate Allocation and Virtual Reference Frames for High Efficiency Video CodingThe High Efficiency Video Coding (HEVC) standard has now become the most popular video coding solution for video conferencing, broadcasting, and streaming. However, its compression performance is still a critical issue for adopting a large number of emerging video applications with higher spatial and temporal resolutions. To advance the current HEVC performance, we propose an efficient temporal rate allocation solution. The proposed method adaptively allocates the compression bitrate for each coded picture in a group of pictures by using a trellis-based dynamic programming approach. To achieve this task, we trained the trellis-based quantization parameter for each frame in a group of pictures considering the temporal layer position. We further improved coding efficiency by incorporating our proposed framework with other inter prediction methods such as a virtual reference frame. Experiments showed around 2% and 5% bitrate savings with our trellis-based rate allocation method with and without a virtual reference frame compared to the conventional HEVC standard, respectively.HoangVan Xiemxiemhoang@vnu.edu.vnDao Thi Hue LeNguyen Canh Thuong2021-06-18T11:17:42Z2021-06-18T11:17:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4481This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44812021-06-18T11:17:42ZA framework for assume-guarantee regression verification of evolving softwareThis paper presents a framework for verifying evolving component-based software using assume-guarantee logic. The goal is to improve CDNF-based assumption generation method by having local weakest assumptions that can be used more effectively when verifying component-based software in the context of software evolution. For this purpose, we improve the technique for responding to membership queries when generating candidate assumptions. This technique is then integrated into a proposed backtracking algorithm to generate local weakest assumptions. These assumptions are effectively used in rechecking the evolving software by reducing time required for assumption regeneration within the proposed framework. The proposed framework can be applied to verify software that is continually evolving. An implemented tool and experimental results are presented to demonstrate the effectiveness and usefulness of the framework.Hoang Viet Tranvietth2004@gmail.comNgoc Hung Phamhungpn@vnu.edu.vnViet-Ha NguyenToshiaki Aoki2021-06-18T10:37:24Z2021-06-18T10:37:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4460This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44602021-06-18T10:37:24ZNear-isogenic lines of soybean confirm a QTL for seed
waterlogging tolerance at different temperaturesClimate change is predicted to increase the
probability of soil waterlogging due to severe rainfall,
causing significant damage to soybean at the germi�nation stage. Germination under waterlogging is also
greatly influenced by temperature. To clarify the
variation in germination responses of soybean geno�types to waterlogging at different temperatures, the
seeds of 15 soybean genotypes were treated by
soaking for 2 days at four temperatures: 21 �C,
23 �C, 25 �C, 27 �C and 29 �C. Differences in the
germination rate (GR) and normal seedling rate (NSR)were observed among soybean genotypes after soak�ing treatments regardless of the temperature. Among
the examined genotypes, Iyodaizu was classified as
waterlogging tolerant at the germination stage, and
Tachinagaha was classified as sensitive. Interestingly,
through the analyses of recombinant inbred lines
(RILs) developed from a cross between Tachinagaha
and Iyodaizu, quantitative trait loci (QTLs) for root
development under hypoxia at the seedling stage of
soybean were detected on chromosome 12
(Chr.12).We investigated whether the candidate QTL
region for root development is involved in seed
waterlogging tolerance by using a near-isogenic line
(NIL), NIL-9-4-5. Interestingly, under soaking treat�ment, the GR and NSR of NIL-9-4-5, carrying the
candidate QTL region, was nearly the same as that of
Iyodaizu and was significantly higher than that of
Tachinagaha. These results may indicate that the
candidate QTL region for root development under
hypoxia at the seedling stage located on Chr.12
contributes to the seed waterlogging tolerance of
soybean plants at the germination stage.Van Loc Nguyennvloc@vnua.edu.vnThi Thu Hien DangDuc ha Chucd.ha@vnu.edu.vnNakamura TetsuhiroTomomi AbikoMochizuki Toshihiro2021-06-18T10:35:26Z2021-06-18T10:35:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4459This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44592021-06-18T10:35:26ZTowards Robust Cognitive 3D Brain-inspired Cross-paradigm SystemSpiking Neuromorphic systems have been introduced as promising platforms for energy-efficient spiking neural network (SNNs) execution. SNNs incorporate neuronal and synaptic states in addition to the variant time scale into their computational model. Since each neuron in these networks is connected to many others, high bandwidth is required. Moreover, since the spike times are used to encode information in SNN, a precise communication latency is also needed, although SNN is tolerant to the spike delay variation in some limits when it is seen as a whole.
The two-dimensional packet-switched network-on-chip was proposed as a solution to provide a scalable interconnect fabric in large-scale spike-based neural networks. The 3D-ICs have also attracted a lot of attention as a potential solution to resolve the interconnect bottleneck. Combining these two emerging technologies provides a new horizon for IC design to satisfy the high requirements of low power and small footprint in emerging AI applications. Moreover, although fault-tolerance is a natural feature of biological systems, integrating many computation and memory units into neuromorphic chips confronts the reliability issue, where a defective part can affect the overall system's performance. This paper presents R-NASH - a reliable three-dimensional digital neuromorphic system geared explicitly toward the 3D-ICs biological brain's three-dimensional structure, where information in the network is represented by sparse patterns of spike timing and learning is based on the local spike-timing-dependent plasticity rule. Our platform enables high integration density and small spike delay of spiking networks and features a scalable design. R-NASH is a design based on the Through-Silicon-Via technology, facilitating spiking neural network implementation on clustered neurons based on Network-on-Chip. We provide a memory interface with the host CPU, allowing for online training and inference of spiking neural networks. Moreover, R-NASH supports fault recovery with graceful performance degradation.Abderazek Ben Abdallahbenab@u-aizu.ac.jpNam Khanh Dangdnk0904@gmail.com2021-06-18T10:34:53Z2021-06-18T10:34:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4456This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44562021-06-18T10:34:53ZTowards Robust Cognitive 3D Brain-inspired Cross-paradigm SystemSpiking Neuromorphic systems have been introduced as promising platforms for energy-efficient spiking neural network (SNNs) execution. SNNs incorporate neuronal and synaptic states in addition to the variant time scale into their computational model. Since each neuron in these networks is connected to many others, high bandwidth is required. Moreover, since the spike times are used to encode information in SNN, a precise communication latency is also needed, although SNN is tolerant to the spike delay variation in some limits when it is seen as a whole.
The two-dimensional packet-switched network-on-chip was proposed as a solution to provide a scalable interconnect fabric in large-scale spike-based neural networks. The 3D-ICs have also attracted a lot of attention as a potential solution to resolve the interconnect bottleneck. Combining these two emerging technologies provides a new horizon for IC design to satisfy the high requirements of low power and small footprint in emerging AI applications. Moreover, although fault-tolerance is a natural feature of biological systems, integrating many computation and memory units into neuromorphic chips confronts the reliability issue, where a defective part can affect the overall system's performance. This paper presents R-NASH - a reliable three-dimensional digital neuromorphic system geared explicitly toward the 3D-ICs biological brain's three-dimensional structure, where information in the network is represented by sparse patterns of spike timing and learning is based on the local spike-timing-dependent plasticity rule. Our platform enables high integration density and small spike delay of spiking networks and features a scalable design. R-NASH is a design based on the Through-Silicon-Via technology, facilitating spiking neural network implementation on clustered neurons based on Network-on-Chip. We provide a memory interface with the host CPU, allowing for online training and inference of spiking neural networks. Moreover, R-NASH supports fault recovery with graceful performance degradation.Abderazek Ben Abdallahbenab@u-aizu.ac.jpNam Khanh Dangdnk0904@gmail.com2021-05-31T11:03:51Z2021-05-31T11:03:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4444This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44442021-05-31T11:03:51ZAssessment of a Homogeneous Model for Simulating a Cavitating Flow in Water under a Wide Range of TemperaturesThe cavitating flow on a NACA0015 hydrofoil in water under a wide range of temperatures is simulated with or without non-condensation gas using a homogeneous model. Our simplified thermodynamic model is coupled with governing equations to capture the latent heat transfer in cavitation. A numerical evaluation proves its applicability through a comparison with experimental data. As a result, the numerical evaluation illustrates good agreement with measured data for both simulations with or without non-condensation gas. The expected prediction pressure coefficient is in better agreement with experimental data for high-temperature water compared to the existing numerical data. Although the temperature depression inside the cavity is confirmed numerically, the thermodynamic effect shows a weak impact on the cavitation behavior near the boiling temperature (100oC). The cavitating flow can therefore be simulated reasonably by an iso-thermal approach at a reasonable cost. The suppression of the void fraction as the water temperature increases is deduced by the flow behavior rather than the thermodynamic effect. Finally, the impact of a non-condensation gas is closely linked to the thermodynamic properties of the water and the flow behavior. The attached cavity position shifts closer to the hydrofoil leading edge significantly in high-temperature water, while an identical position is reproduced for room temperature conditions in comparison with the simulation without a non-condensation gas.Anh Dinh Leanh.ld@vnu.edu.vn2021-05-31T11:01:47Z2021-05-31T11:01:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4446This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44462021-05-31T11:01:47ZTurbulence cascade model for viscous vortex ring-tube reconnectionThe reconnection of a vortex ring and a vortex tube in a viscous fluid with the effects of two vortex core sizes (σ 0 = 0.12r 0 and 0.24r 0 , where r 0 are initial ring radius) and three initial flow configurations (left-offset, center and right-offset) at Reynolds number (Re Γ) of 10000 was investigated using a high-order Vortex-in-cell method combined with a Large-eddy simulation model. For the left-offset case, a large part of the ring, slipping over the tube, associates with a small part of the tube to establish a new vortex ring, whereas the rest of the tube is reconnected by another part of the ring. For the center case, half of the ring joins with a part of the tube to construct an elliptical vortex ring while the rest connects because of viscosity. The reconnected ring and tube become more stable and are like the initial ones in the ultimate stage. For the right-offset case, both the ring and tube's reconnection occurs, and the reconnected elliptical vortex ring is rapidly distorted. The proportion of reconnected ring increases, and then this ring section loses its integrity, decaying into a complex cluster of various-scales vortex structures in different shapes. At σ 0 = 0.12r 0 , the secondary vortex structures surrounding the tube and ring appear in three cases, while they are only observed for the center case at σ 0 = 0.24r 0. For three flow configurations and two vortex core sizes, after the reconnection, the energy cascade of the flow approaches a k −5/3 slope of Kolmogorov's similarity hypotheses and a k −3 slope in the ranges of wavenumbers (k) from 3 to 10 and from 10 to 40, respectively. The highest population of small-scale coherent vortex structures is observed for the right-offset, followed by the center and left-offset. In addition, a larger number of these structures were observed for a smaller core size. This validates that the mixing performance is the best at a small vortex core and in the right-offset configuration.Duong Viet Dungduongdv@vnu.edu.vnNguyen Van DucNguyen Van Lucnguyenvanluc@tdtu.edu.vn2021-05-31T10:58:32Z2021-05-31T10:58:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4437This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44372021-05-31T10:58:32ZHierarchical Convolutional Neural Network with Feature Preservation and Autotuned Thresholding for Crack DetectionDrone imagery is increasingly used in automated inspection for infrastructure surface defects, especially in hazardous or unreachable environments. In machine vision, the key to crack detection rests with robust and accurate algorithms for image processing. To this end, this paper proposes a deep learning approach using hierarchical convolutional neural networks with feature preservation (HCNNFP) and an intercontrast iterative thresholding algorithm for image binarization. First, a set of branch networks is proposed, wherein the output of previous convolutional blocks is half-sizedly concatenated to the current ones to reduce the obscuration in the down-sampling stage taking into account the overall information loss. Next, to extract the feature map generated from the enhanced HCNN, a binary contrast-based autotuned thresholding (CBAT) approach is developed at the post-processing step, where patterns of interest are clustered within the probability map of the identified features. The proposed technique is then applied to identify surface cracks on the surface of roads, bridges or pavements. An extensive comparison with existing techniques is conducted on various datasets and subject to a number of evaluation criteria including the average F-measure (AFβ) introduced here for dynamic quantification of the performance. Experiments on crack images, including those captured by unmanned aerial vehicles inspecting a monorail bridge. The proposed technique outperforms the existing methods on various tested datasets especially for GAPs dataset with an increase of about 1.4% in terms of AFβ while the mean percentage error drops by 2.2%. Such performance demonstrates the merits of the proposed HCNNFP architecture for surface defect inspection.Qiuchen ZhuQiuchen.Zhu@student.uts.edu.auTran Hiep Dinhtranhiep.dinh@vnu.edu.vnManh Duong Phungduongpm@vnu.edu.vnHa Quangquang.ha@uts.edu.au2021-05-31T10:58:19Z2021-05-31T10:58:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4436This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44362021-05-31T10:58:19ZSafety-enhanced UAV Path Planning with Spherical Vector-based Particle Swarm OptimizationThis paper presents a new algorithm named spherical vector-based particle swarm optimization (SPSO) to deal with the problem of path planning for unmanned aerial vehicles (UAVs) in complicated environments subjected to multiple threats. A cost function is first formulated to convert the path planning into an optimization problem that incorporates requirements and constraints for the feasible and safe operation of the UAV. SPSO is then used to find the optimal path that minimizes the cost function by efficiently searching the configuration space of the UAV via the correspondence between the particle position and the speed, turn angle and climb/dive angle of the UAV. To evaluate the performance of SPSO, eight benchmarking scenarios have been generated from real digital elevation model maps. The results show that the proposed SPSO outperforms not only other particle swarm optimization (PSO) variants including the classic PSO, phase angle-encoded PSO and quantum-behave PSO but also other state-of-the-art metaheuristic optimization algorithms including the genetic algorithm (GA), artificial bee colony (ABC), and differential evolution (DE) in most scenarios. In addition, experiments have been conducted to demonstrate the validity of the generated paths for real UAV operations. Source code of the algorithm can be found at https://github.com/duongpm/SPSO.Manh Duong Phungduongpm@vnu.edu.vnHa Quangquang.ha@uts.edu.au2021-05-31T10:58:07Z2021-05-31T10:58:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4435This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44352021-05-31T10:58:07ZRobust Subspace Tracking with Missing Data and Outliers: Novel Algorithm with Convergence GuaranteeIn this paper, we propose a novel algorithm, namely
PETRELS-ADMM, to deal with subspace tracking in the presence of outliers and missing data. The proposed approach consists of two main stages: outlier rejection and subspace estimation. In the first stage, alternating direction method of multipliers (ADMM) is effectively exploited to detect outliers affecting the observed data. In the second stage, we propose an improved version of the parallel estimation and tracking by recursive least squares (PETRELS) algorithm to update the underlying subspace in the missing data context. We then present a theoretical convergence analysis of PETRELS-ADMM which shows that it generates a sequence of subspace solutions converging to the optimum of its batch counterpart. The effectiveness of the proposed algorithm, as compared to state-of-the-art algorithms, is illustrated on both simulated and real data.Trung Thanh Leletrungthanhtbt@gmail.comViet Dung Nguyennvdung@vnu.edu.vnLinh Trung Nguyenlinhtrung@vnu.edu.vnKarim Abed-Meraimkarim.abed-meraim@univ-orleans.fr2021-05-31T10:54:29Z2021-05-31T10:54:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4431This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44312021-05-31T10:54:29ZOn the Design of a Fault-tolerant Scalable Three Dimensional NoC-based Digital Neuromorphic System with On-chip LearningMark OgbodoNam Khanh Dangdnk0904@gmail.comAbderazek Ben Abdallahbenab@u-aizu.ac.jp2021-05-31T10:52:11Z2021-05-31T10:52:11Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4430This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/44302021-05-31T10:52:11ZHotCluster: A thermal-aware defect recovery
method for Through-Silicon-Vias Towards Reliable
3-D ICs systemsThrough Silicon Via (TSV) is considered as the
near-future solution to realize low-power and high-performance
3D-Integrated Circuits (3D-ICs) and 3D-Network-on-Chips (3DNoCs). However, the lifetime reliability issue of TSV due to
its fault sensitivity and the high operating temperature of
3D-ICs, which also accelerates the fault-rate, is one of the
most critical challenges. Meanwhile, most current works focus
on detecting and correcting TSV defects after manufacturing
without considering high-temperature nodes’ impact on lifetime
reliability. Besides, the recovery for defective clusters is also
challenging because of costly redundancies. In this work, we
present HotCluster: a hotspot-aware self-correction platform for
clustering defects in 3D-NoCs to help understand and tackle
this problem. We first give a method to predict normalized fault
rates and place redundant TSV groups according to each region’s
fault rate. In our particular medium fault-rate (normalized to the
coolest area), HotCluster reduces about 60% of the redundancies
in comparison to the uniformly distributed redundancies while
having a higher ratio of router working in a normal state. Furthermore, HotCluster integrates both online (weight-based) and
offline (max-flow min-cut offline method) mapping algorithms to
help the system correct the faulty TSV clusters. The experimental
results show that both the max-flow min-cut offline method and
weight-based online mode with a redundancy of 0.25 exhibits less
than 1% of routers disabled under 50% defect-rates.Nam Khanh Dangdnk0904@gmail.comAkram Ben AhmedAbderazek Ben Abdallahbenab@u-aizu.ac.jpXuan Tu Trantutx@vnu.edu.vn2021-03-24T04:48:56Z2021-03-24T04:48:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4395This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43952021-03-24T04:48:56ZVortex ring-tube reconnection in a viscous fluidThe vortex ring-tube reconnection in a viscous fluid was investigated using a proposed vortex-in-cell method combined with a large eddy simulation model (LVIC). This method was verified using simulations of the Taylor–Green vortex flow at the Reynolds numbers (Re) 200 and 2000. The results show that the present method can capture the small-scale vortex structures in turbulent flows well. Besides, a Lagrangian method for passive scalar transport was successfully developed to track the vortex dynamics. The LVIC was then applied to three simulations of the interaction of a vortex ring at RerΓ(Γ/ν)=10000 and a vortex tube at RetΓ=1000, 5000, and 10 000. At RerΓ=10000 and RetΓ=1000, the effects of the tube on the ring are trivial while the ring breaks it into two parts and entrains them. The flow’s energy spectrum remains unchanged with time, the small-scale vortices are not generated, and the ring’s motion plays a key role in the flow. Moreover, the helicity distribution on the vortices is negligible. At RerΓ=10000 and RetΓ=5000, the tube breaks into two parts, and the leaving part of the tube interacts forcefully with the ring to form the small-scale vortices at the high wavenumbers. The population of small-scale vortex structures increases with time, and the large-scale vortices are twisted after the impingement. At RerΓ=10000 and RetΓ=10000, the impingement of the ring on the tube leads to their breakdown and reconnection. A part of the ring interacts with the leaving part of the tube to form a secondary ring, while the rest replaces the leaving part to reconnect the tube. The population of small-scale vortex structures and helicity distribution increase in this flow stage because of the interaction of the secondary ring wake and connection vortices. However, after the reconnection, the population and helicity distribution on the vortex structures significantly decrease. The smallest-scale vortex structure and the most effective mixing occur with RerΓ=10000 and RetΓ=5000.Nguyen Van Lucnguyenvanluc@tdtu.edu.vnDuong Viet Dungduongdv@vnu.edu.vn2021-01-06T02:44:08Z2021-01-06T02:44:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4364This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43642021-01-06T02:44:08ZImpact of blast and mechanical loads on the shear deformable stiffened sandwich plate with an auxetic core layer in thermal environmentNgoc Thinh PhamDinh Quang Vuquangvd2510@gmail.comThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2021-01-06T02:43:57Z2021-01-06T02:43:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4363This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43632021-01-06T02:43:57ZNonlinear dynamic response and vibration of imperfect eccentrically stiffened sandwich third-order shear deformable FGM cylindrical panels in thermal environmentshis study follows an analytical approach to investigate the nonlinear dynamic response and vibration of eccentrically stiffened sandwich functionally graded material (FGM) cylindrical panels with metal–ceramic layers on elastic foundations in thermal environments. It is assumed that the FGM cylindrical panel is reinforced by the eccentrically longitudinal and transversal stiffeners and subjected to mechanical and thermal loads. The material properties are assumed to be temperature dependent and graded in the thickness direction according to a simple power law distribution. Based on the Reddy’s third-order shear deformation shell theory, the motion and compatibility equations are derived taking into account geometrical nonlinearity and Pasternak-type elastic foundations. The outstanding feature of this study is that both FGM cylindrical panel and stiffeners are assumed to be deformed in the presence of temperature. Explicit relation of deflection–time curves and frequencies of FGM cylindrical panel are determined by applying stress function, Galerkin method and fourth-order Runge-Kutta method. The influences of material and geometrical parameters, elastic foundations and stiffeners on the nonlinear dynamic and vibration of the sandwich FGM panels are discussed in detail. The obtained results are validated by comparing with other results in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDuc Tuan NgoTran PhuongQuoc Quan TranVan Thanh Nguyen2021-01-06T02:43:47Z2021-01-06T02:43:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4361This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43612021-01-06T02:43:47ZNonlinear post-buckling and vibration of 2D penta-graphene composite platesThe newly developed penta-graphene is a two-dimensional (2D) carbon allotrope with promising mechanical properties. This paper investigates the nonlinear post-buckling and vibration of imperfect three-dimensional penta-graphene composite plates resting on elastic foundations and subjected to uniform external pressure and axial compressive load. The elastic constants of the single-layer penta-graphene are fully determined by the density functional theory by fitting the equation of strain energy to the density functional theory energy. Specifically, the elastic constant C66 which has not been considered by other authors is also determined. The motion and compatibility equations are derived based on the classical plate theory taking into account von Karman geometrical nonlinearity, initial geometrical imperfection and Pasternak type elastic foundations. For nonlinear post-buckling, the Bubnov–Galerkin method is applied to obtain the load–deflection amplitude curves while the Runge–Kutta method and harmonic balance method are used to obtain the deflection amplitude–time curves and the amplitude–frequency curves for nonlinear vibration. Numerical results show the effects of geometrical parameters, initial imperfection and elastic foundations on the nonlinear post-buckling and vibration of the imperfect 2D penta-graphene plates. The present results are also compared to others to validate the accuracy of the applied method and approach.Dinh Duc Nguyenducnd@vnu.edu.vnTien Lam PhamQuoc Quan TranMinh Quang PhamVan Quyen Nguyen2021-01-06T02:43:39Z2021-01-06T02:43:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4360This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43602021-01-06T02:43:39ZNonlinear vibration of FGM moderately thick toroidal shell segment within the framework of Reddy’s third order-shear deformation shell theoryNonlinear vibration and dynamic response of functionally graded moderately thick toroidal shell segments resting on Pasternak type elastic foundation are investigated in this paper. Functionally graded materials are made from ceramic and metal, and the volume fraction of constituents are assumed to vary through the thickness direction according to a power law function. Reddy’s third order shear deformation, von Karman nonlinearity, Airy stress function method and analytical solutions are used to derive the governing equations. Galerkin method is used to convert the governing equation into nonlinear differential equation, then the explicit expressions of natural frequencies and nonlinear frequency–amplitude relations are obtained. Using Runge–Kutta method, the nonlinear differential equation of motion is solved, and then nonlinear vibration and dynamic response of shells are analyzed. The effects of temperature, material and geometrical properties, and foundation parameters on nonlinear vibration and dynamic characteristics are investigated and discussed in detail.Minh Vuong PhamDinh Duc Nguyenducnd@vnu.edu.vn2021-01-06T02:43:28Z2021-01-06T02:43:28Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4359This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43592021-01-06T02:43:28ZEffect of eccentrically oblique stiffeners and temperature on the nonlinear static and dynamic response of S-FGM cylindrical panelsThis work aims to study the effect of obique stiffeners on the nonlinear static and dynamic buckling behaviors of S-FGM cylindrical panels based on the classical shell theory (CST) with the geometrical nonlinearity in von Kármán Donnell sense. The dynamic critical buckling load is obtainted by Budiansky-Roth criterion. The cylindrical panels are reinforced by oblique stiffeners on the top layer, and supported by elastic foundations on the bottom layer. Numerical results are given to evaluate effects of inhomogeneous, dimensional parameters, temperature increment, compressive pressure, oblique angles of stiffeners, the imperfection of original shape, and elastic foundations to the nonlinear static and dynamic response of S-FGM cylindrical panels in the thermal environment.Dinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimTuan Manh DuongDinh Nguyen Phamnguyenpd@vnu.edu.vn2021-01-06T02:43:14Z2021-01-06T02:43:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4358This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43582021-01-06T02:43:14ZFree vibration of cracked FGM plates with variable thickness resting on elastic foundationsMinh Phuc PhamTuan Manh DuongDinh Duc Nguyenducnd@vnu.edu.vn2021-01-06T02:43:02Z2021-01-06T02:43:02Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4354This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43542021-01-06T02:43:02ZEnhanced nodal gradient finite elements with new numerical integration schemes for 2D and 3D geometrically nonlinear analysisThe consecutive-interpolation procedure (CIP) has been recently proposed as an enhanced technique for traditional finite element method (FEM) with various desirable properties such as continuous nodal gradients and higher accuracy without increasing the total number of degrees of freedom (DOFs). It is common knowledge that linear finite elements, e.g., four-node quadrilateral (Q4) or eight-node hexahedral (HH8) elements, are not highly suitable for geometrically nonlinear analysis. The elements with quadratic interpolation functions have to be used instead. In this paper, the CIP-enhanced four-node quadrilateral element (CQ4), and the CIP-enhanced eight-node hexahedral element (CHH8), are for the first time extended to investigate geometrically nonlinear problems of two- (2D) and three-dimensional (3D) structures. To further enhance the efficiency of the present approaches, novel numerical integration schemes based on the concept of mid-point rules, namely element mid-points (EM) and element mid-edges (EE) are integrated into the present CQ4 element. For CHH8, the 3D-version of EM (namely 3D-EM) and the element mid-faces (EF) scheme are investigated. The accuracy and computational efficiency of the two novel quadrature schemes in both regular and irregular (distorted) meshes are analyzed. Numerical results indicate that the new integration approaches perform more efficiently than the well-known Gaussian quadrature while gaining equivalent accuracy. The performance of the CIP-enhanced elements, which is examined through numerical experiments, is found to be equivalent to that of quadratic Lagrangian finite element counterparts, while having the same discretization with that by the linear finite elements. In addition, we also apply the present CQ4 and CHH8 elements associated with different numerical integration techniques to nearly incompressible materials.Dinh Du NguyenMinh Ngoc NguyenDinh Duc Nguyenducnd@vnu.edu.vnRungamornrat JaroonQuoc Tinh Bui2020-12-26T09:29:35Z2020-12-26T09:29:35Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4330This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43302020-12-26T09:29:35ZThe new design of cows' behavior classifier based on acceleration data and proposed feature setMonitor and classify behavioral activities in cows is a helpful support solution for livestock based on the analysis of data from sensors attached to the animal. Accelerometers are particularly suited for monitoring cow behaviors due to small size, lightweight and high accuracy. Nevertheless, the interpretation of the data collected by such sensors when characterizing the type of behaviors still brings major challenges to developers, related to activity complexity (i.e., certain behaviors contain similar gestures). This paper presents a new design of cows' behavior classifier based on acceleration data and proposed feature set. Analysis of cow acceleration data is used to extract features for classification using machine learning algorithms. We found that with 5 features (mean, standard deviation, root mean square, median, range) and 16-second window of data (1 sample/second), classification of seven cow behaviors (including feeding, lying, standing, lying down, standing up, normal walking, active walking) achieved the overall highest performance. We validated the results with acceleration data from a public source. Performance of our proposed classifier was evaluated and compared to existing ones in terms of the sensitivity, the accuracy, the positive predictive value, and the negative predictive value.Phung Cong Phi KhanhDuc-Tan TranVan Tu DuongNguyen Hong ThinhDuc-Nghia Tran2020-12-25T11:15:15Z2020-12-25T11:15:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4335This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43352020-12-25T11:15:15ZOn the Gaussian Cramér-Rao Bound for Blind Single-Input
Multiple-Output System Identification: Fast and Asymptotic
ComputationsThe Cramér-Rao Bound (CRB) is a powerful tool to assess the performance limits of a parameter estimation problem for a given statistical model. In particular, the Gaussian CRB (i.e., the CRB obtained assuming the data are Gaussian) corresponds to the worst case; giving the largest CRB among a large class of data distributions. This makes it very useful in practice since optimizing under the Gaussian data assumption can be interpreted as a min-max optimization (i.e., minimizing the largest CRB). The Gaussian CRB is also the corresponding bound of Second-Order Statistics (SOS)-based estimation methods, which are frequently used in practice. Despite its practicality, computing this bound might be cumbersome in some cases, particularly in the case where the input is assumed deterministic and has a large number of samples. In this paper, we address this computational issue by proposing a fast computation for the deterministic Gaussian CRB of Single-Input Multiple Output (SIMO) blind system identification. More precisely, we exploit circulant matrix properties to reduce the cost from cubic to quadratic with respect to the sample size. Moreover, we derive a closed-form formula for the asymptotic (large sample size) Gaussian CRB and show how it can be computed using the residue theorem.Nait-Meziane MohamedAbed Meraim Karimkarim.abed-meraim@univ-orleans.frZhao ZhipengLinh Trung Nguyenlinhtrung@vnu.edu.vn2020-12-25T10:22:48Z2020-12-26T05:21:54Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4333This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43332020-12-25T10:22:48ZA Comprehensive Survey of Enabling and Emerging Technologies for Social Distancing——Part II: Emerging Technologies and Open IssuesThis two-part paper aims to provide a comprehensive survey on how emerging technologies, e.g., wireless and networking, artificial intelligence (AI) can enable, encourage, and even enforce social distancing practice. In Part I, an extensive background of social distancing is provided, and enabling wireless technologies are thoroughly surveyed. In this Part II, emerging technologies such as machine learning, computer vision, thermal, ultrasound, etc., are introduced. These technologies open many new solutions and directions to deal with problems in social distancing, e.g., symptom prediction, detection and monitoring quarantined people, and contact tracing. Finally, we discuss open issues and challenges (e.g., privacy-preserving, scheduling, and incentive mechanisms) in implementing social distancing in practice. As an example, instead of reacting with ad-hoc responses to COVID-19-like pandemics in the future, smart infrastructures (e.g., next-generation wireless systems like 6G, smart home/building, smart city, intelligent transportation systems) should incorporate a pandemic mode in their standard architectures/designs.Thanh Cong NguyenSaputra Yuris MulyaYurisMulya.Saputra@student.uts.edu.auVan Nguyen HuynhNgoc Tan Nguyennguyen.tan170@gmail.comViet Khoa Trankhoatv.uet@vnu.edu.vnTuan Bui Minhtuanbm.uet@vnu.edu.vnNguyen DiepDiep.Nguyen@uts.edu.auThai Hoang DinhHoang.Dinh@uts.edu.auXuan Thang Vuthang.vu85@gmail.comDutkiewicz Erykeryk.dutkiewicz@uts.edu.auChatzinotas SymeonOttersten Bjorn2020-12-25T10:12:57Z2020-12-25T10:12:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4332This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43322020-12-25T10:12:57ZA Comprehensive Survey of Enabling and Emerging Technologies for Social Distancing—Part I: Fundamentals and Enabling TechnologiesSocial distancing plays a pivotal role in preventing the spread of viral diseases illnesses such as COVID-19. By minimizing the close physical contact among people, we can reduce the chances of catching the virus and spreading it across the community. This two-part paper aims to provide a comprehensive survey on how emerging technologies, e.g., wireless and networking, artificial intelligence (AI) can enable, encourage, and even enforce social distancing practice. In this Part I, we provide a comprehensive background of social distancing including basic concepts, measurements, models, and propose various practical social distancing scenarios. We then discuss enabling wireless technologies which are especially effectin social distancing, e.g., symptom prediction, detection and monitoring quarantined people, and contact tracing. The companion paper Part II surveys other emerging and related technologies, such as machine learning, computer vision, thermal, ultrasound, etc., and discusses open issues and challenges (e.g., privacypreserving, scheduling, and incentive mechanisms) in implementing social distancing in practice.Thanh Cong NguyenSaputra Yuris MulyaYurisMulya.Saputra@student.uts.edu.auNgoc Tan Nguyennguyen.tan170@gmail.comViet Khoa Trankhoatv.uet@vnu.edu.vnMinh Tuan Buituanbm.uet@vnu.edu.vnNguyen DiepThai Hoang DinhXuan Thang Vuthang.vu85@gmail.comDutkiewicz Erykeryk.dutkiewicz@uts.edu.auChatzinotas SymeonOttersten Bjorn2020-12-23T03:41:50Z2020-12-23T03:52:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4314This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/43142020-12-23T03:41:50ZAnalysing outage probability of linear a
non-linear RF energy harvesting of
cooperative communication networksIn this study, a dual-hop cooperative communication system with radio frequency (RF) energy harvesting was
investigated in two cases of linear and non-linear energy harvesting models. In the proposed system, the signal is transmitted
directly from a source node to a destination node or sent with support of selected relay nodes. While both the source node and
the destination node are powered normally, the relay nodes are powered by harvesting technique. To choose the best relay
node, a selection combination method was applied at the destination node in both cases of amplify-and-forward and decodeand-forward protocols. To evaluate the system performance, the outage probability of the cooperative communications over
independent identically distributed Nakagami-m was derived and analysed with arbitrary m parameter whereas this parameter
was fixed to be integral value in previous research studies. Furthermore, the approximate and asymptotic operations are applied
to simplify the outage probability expressions. The simulation program was developed based on the Monte Carlo method and
MATLAB software with two aims of evaluating the system performance and verifying the theoretical results. The simulation
results demonstrate that the analysis and evaluation of the study are considerably accurate.Van Son Vusonvv@gmail.comTrieu Duong Dinhduongdt@vnu.edu.vnManh Hoang TranThanh Quan DoThanh Hiep Phamphamthanhhiep@gmail.com2020-12-18T09:07:40Z2020-12-18T09:07:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4288This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42882020-12-18T09:07:40ZA model for building probabilistic knowledge-based systems using divergence distancesThe knowledge-based systems (KBSs) in general and solving the knowledge merging problem in particular have seen a great surge of research activity in recent years. However, there still exist two main shortcomings that need to be addressed in the probabilistic framework. Firstly, the current methods only deal with the problems in which original probabilistic knowledge bases (PKBs) are required to be consistent and formed in the same structure. It is a very strong requirement and difficult to apply in practice. Secondly, only a few measures of distance between probability distributions have been studied to apply in existing models. To overcome these disadvantages, in this paper, we introduce a novel framework for merging PKBs. To this end, a theoretical model is introduced and several experiments are implemented. In theoretical model, some theorems are pointed out and proved to provide mathematical background to construct the merging model. Moreover, a deep survey on how to employ divergence distance functions (DDFs) between probability distributions to carry out the merging process are performed. In experimental aspect, a consistency recovery algorithm and some merging algorithms based on DDFs are proposed. Through the results of conducted experiments, issues about the time cost of merging process, the number of iterations, and CPU Time Elapsed parameter to solve the class of optimization problems in the merging process are analyzed, compared, and evaluated.Van Tham Nguyenthamnv.nute@gmail.comNgoc Thanh Nguyenngoc-thanh.nguyen@pwr.wroc.plTrong Hieu Tranhieutt@vnu.edu.vn2020-12-17T05:22:04Z2020-12-17T05:22:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4281This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42812020-12-17T05:22:04ZOn the proof of recursive Vogler algorithm for multiple knife-edge diffractionWe consider the problem of multiple knife-edge diffraction estimation which is a fundamental task in many wireless communication applications. So far, one of the most accurate methods for this problem is the Vogler one whose recursive implementation is efficient to reduce the high computational complexity of the direct one. However, in the original report, Vogler only presented the final result of the recursive algorithm without a rigorous mathematical proof, thus making the method difficult to understand and implement in practice. To tackle this shortcoming, we first analyze the mathematical structure of the problem and then present a formal proof of the result. To gain intuition of the proof and the key steps, we provide a simplified study case of four knife-edges. The insight from our proposed analysis and proof can be used to obtain a comprehensive interpretation, initiate a practical implementation and develop new efficient algorithms with similar structure.Viet Dung Nguyennvdung@vnu.edu.vnHuy PhanAli MansourArnaud CoatanhayThierry Marsault2020-12-13T15:49:19Z2022-10-26T21:59:50Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4163This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41632020-12-13T15:49:19ZThermal stability of meso-substituted metal corroles in inert and oxidative mediaVu Thi ThaoD. R. KarimovS. S. GuseinovE. V. BalantsevaD. B. Berezin2020-12-13T15:48:54Z2022-10-26T21:59:55Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4162This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41622020-12-13T15:48:54ZSynthesis, chemical stability, and electrocatalytic properties of zinc(II) and cobalt(II) complexes of N-methyltetraphenylporphineD. B. BerezinVu Thi TxaoA. A. AzorinaO. V. ShukhtoS. S. GuseinovN. M. Berezina2020-12-13T15:48:28Z2022-10-26T21:59:23Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4161This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41612020-12-13T15:48:28ZKinetic stability of corrole complexes with manganese, copper, and zinc in environments based on acetic and sulfuric acidsD. B. BerezinO. V. ShukhtoVu Thi ThaoD. R. KarimovB. D. Berezin2020-12-11T23:18:36Z2020-12-14T05:05:37Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4246This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42462020-12-11T23:18:36ZShort time cardio-vascular pulses estimation for dengue fever screening via continuous-wave Doppler radar using empirical mode decomposition and continuous wavelet transformDinh Chinh Nguyenchinhnd@vnu.edu.vnManh Ha Luuhalm@vnu.edu.vnSun Guanghaoguanghao.sun@uec.ac.jpQuoc Anh Lequocanh.uet@gmail.comThi Viet Huong Phamhuongpv@vnu.edu.vnAnh Vu Trananhvu77@gmail.comTrong Hieu Tranhieutt@vnu.edu.vnDuc Tan Trantan.tranduc@phenikaa-uni.edu.vnVu Trung Nguyennguyenvutrung@hmu.edu.vnIshibashi Koichiroishibashi@uec.ac.jpLinh Trung Nguyenlinhtrung@vnu.edu.vn2020-12-11T01:40:30Z2021-03-24T04:44:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4233This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42332020-12-11T01:40:30ZEarly SKIP mode decision for HEVC with Hierarchical coding structureTo meet real-time video communications, an investigation of early SKIP mode decisions is still important in many practical applications of High-Efficiency Video Coding (HEVC) encoders. On the other hand, in most current state-of-the-art early SKIP mode decision methods, the temporal layer index (TId), which is commonly used in the hierarchical coding structure, has not been fully exploited. In this regard, this paper proposes a novel early SKIP mode decision method for a HEVC encoder using TId-based rate-distortion (RD) modeling. In the proposed method, two new SKIP mode-checking conditions were introduced based on statistical analysis on TId and the RD-cost correlation. The experimental results showed that the proposed early SKIP mode decision method outperformed the relevant state-of-the-art HEVC complexity reduction methods significantly, with an encoding time saving of approximately 47% while having a BD-rate loss of only 0.45%.Hoang Van Xiemxiemhoang@vnu.edu.vnDinh Bao Minhminhdinh@vnu.edu.vnJeon Byeungwoobjeon@skku.edu2020-12-11T01:38:52Z2020-12-23T03:15:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4226This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42262020-12-11T01:38:52ZStructural, Optical, Ferroelectric and Ferromagnetic Properties of Bi1xGdxFeO3 MaterialsBi1xGdxFeO3 (BGFO) (x = 0.00 7 0.15) materials were prepared by a sol-gel method. The effect of Gd doping on the structural, ferromagnetic, and ferroelectric properties of BiFeO3 (BFO) were analyzed using x-ray diffraction, Raman scattering, energy-dispersive x-ray spectroscopy, ferroelectric hysteresis loop and magnetic hysteresis loop measurements. All samples showed
a rhombohedral structure of the perovskite type. The a and c lattice parameters decreased with Gd content, obeying Vegard’s law, from 5.583 A˚ to 5.511
A˚ , and from 13.869 A˚ to 13.741 A˚ , respectively. The optical band gap (Eg) also decreased with Gd content, from 2.02 eV to 1.60 eV at x = 0.00 to x = 0.15,
respectively. The ferroelectric and ferromagnetic properties of the BGFO materials were enhanced compared with those of the pure BFO material. Maximum saturation polarization (Ps) and saturation magnetization (Ms) values of 6.88 lC/cm2 and 0.386 emu/g were obtained. We found that the optimum Gd doping content to enhance multiferroic properties of BFO material is in range from x = 0.10 to x = 0.125. The origin of ferromagnetic
and ferroelectric properties of BGFO materials were also discussed.Dinh Tu Buibuidinhtu@vnu.edu.vn2020-12-11T01:37:56Z2020-12-11T01:37:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4209This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42092020-12-11T01:37:56ZFabrication and characteristics of Zn1–xSnxO nanorod/ITO composite photocatalytic filmsZn1−xSnxO NRs/ITO composite photocatalytic films were fabricated by the hydrothermal method. A
concentration of Sn dopant in Zn1−xSnxO nanorods(NRs)was varied from 0% to 7%. The structural
and surface morphology characteristics of Zn1−xSnxO NRs/ITO composite photocatalytic films were
investigated by X-Ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. In
addition, photocatalytic properties of synthesized materials were evaluated by degradation rates of
Rhodamine-B aqueous solutions under UV light irradiation. The SEM results indicated that, with an
increasing concentration of Sn dopant in Zn1−xSnxO NRs/ITO, the effective surface areas were
declined by an exponential decay function and the reduction was negligible as the Sn doping
concentration was higher than 3%. With the similarity in effective surface area, the contribution of Sn
in the enhancement of the photocatalytic activity of Zn0.93Sn0.07O NRs/ITO is clearly observed with
41% improvement in comparison to ZnO NRs/ITO.Thi Dung NguyenTran Chien DangDuc Thien TrinhAnh Tuan DuongDuc Thang PhamNang Dinh NguyenDinh Lam Nguyen2020-12-11T01:37:43Z2020-12-26T14:26:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4208This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42082020-12-11T01:37:43ZExperimental and numerical study on photocatalytic activity of the ZnO nanorods/CuO composite filmThe photocatalytic activity of the ZnO NRs/CuO composite film was investigated by using both experimental and numerical methods. The ZnO NRs/CuO composite film exhibits significantly enlarge absorption range to visible-light and suppress the recombination rate of the photogenerated electron-hole pairs, which can be well utilized as a photocatalyst. The ZnO NRs/CuO composite film also presents good stability, and reusability, and durability for photo-decomposition purpose. The optimal ZnO NRs/CuO composite film contains 1μ-thick of CuO film and 10 nm-thick of ZnO NRs film. The donor concentration in ZnO NRs film should be lower than 1016 cm−3. The short circuit current density of the optimal composite film is 25.8 mA/cm2 resulting in the calculated pseudo-order rate constant of 1.85 s−1. The enhancement in degradation efficiency of this composite film is attributed to the inner electric field and large effective surface area of ZnO NRs film.Thi Dung Nguyendungtnguyen@vnu.eduMinh Duc Tranminhductran911@gmail.comVan Thanh Hoanghoangvanthanh12b4ksa2015@gmail.comDuc Thien TrinhDuc Thang Phamthangducpham@yahoo.comDinh Lam NguyenLamnd2005@gmail.com2020-12-10T03:45:32Z2020-12-10T05:17:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4221This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42212020-12-10T03:45:32ZmPartition: A Model‐Based Method for Partitioning AlignmentsThu LeSy Vinh Levinhls@vnu.edu.vn2020-12-10T03:40:44Z2020-12-10T03:40:44Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4219This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42192020-12-10T03:40:44ZFLAVI: An Amino Acid Substitution Model for FlavivirusesThu NguyenLe Sy Vinhvinhls@vnu.edu.vn2020-12-08T15:31:12Z2020-12-08T15:31:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4197This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41972020-12-08T15:31:12ZEnd-to-end Image Patch Quality Assessment for Image/Video with Compression ArtifactsIn this paper, we present an experimental image quality assessment (IQA) method for image/ video patches with compression artifacts. Using the High Efficiency Video Coding (HEVC) standard, we create a new database of image patches with compression artifacts. Then, we conduct a completed subjective testing process to obtain the ‘ground truth’ quality scores for the mentioned database. Finally, we employ an end-to-end learning method to estimate the IQA model for the patches with HEVC compression artifacts. In such proposed method, a modified convolutional neural network (CNN) architecture is exploited for feature extraction while an adaptive moment estimation optimizer solution is used to perform the training process. Experimental results show that the proposed end-to-end IQA method significantly outperforms the relevant IQA benchmarks, especially when the compression artifacts are strongly realized.Pham Thanh Tungtung@vinafire.com.vnVan Hoang Xiemxiemhoang@vnu.edu.vnNguyen Trung NghiaDinh Trieu DuongLe Thanh Ha2020-12-08T15:31:06Z2020-12-08T15:31:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4201This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42012020-12-08T15:31:06ZAdaptive Content Frame skipping for Wyner-Ziv based Light Field Image CompressionLight field (LF) imaging introduces attractive possibilities for digital imaging, such as digital focusing, post-capture changing of the focal plane or view point, and scene depth estimation, by capturing both spatial and angular information of incident light rays. However, LF image compression is still a great challenge, not only due to light field imagery requiring a large amount of storage space and a large transmission bandwidth, but also due to the complexity requirements of various applications. In this paper, we propose a novel LF adaptive content frame skipping compression solution by following a Wyner–Ziv (WZ) coding approach. In the proposed coding approach, the LF image is firstly converted into a four-dimensional LF (4D-LF) data format. To achieve good compression performance, we select an efficient scanning mechanism to generate a 4D-LF pseudo-sequence by analyzing the content of the LF image with different scanning methods. In addition, to further explore the high frame correlation of the 4D-LF pseudo-sequence, we introduce an adaptive frame skipping algorithm followed by decision tree techniques based on the LF characteristics, e.g., the depth of field and angular information. The experimental results show that the proposed WZ-LF coding solution achieves outstanding rate distortion (RD) performance while having less computational complexity. Notably, a bit rate saving of 53% is achieved compared to the standard high-efficiency video coding (HEVC) Intra codec.Phi Cong HuyPerry StuartHoangVan Xiemxiemhoang@vnu.edu.vn2020-12-08T15:31:03Z2020-12-08T15:31:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4200This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/42002020-12-08T15:31:03ZVersatile Video Coding based Quality Scalability with Joint Layer ReferenceScalability is an essential coding feature for adaptive video streaming applications, notably considering the growing heterogeneity of the transmission, display and consumption environments. Versatile video coding (VVC) is the emerging video coding standard, targeting offering higher compression efficiency regarding previous standards to further facilitate already available and novel video applications, notably at higher spatial resolutions. In this context, this paper proposes the first VVC-based quality scalability extension, targeting to offer higher compression efficiency than the native VVC quality scalability solution. The proposed Quality Scalable Versatile Video Coding (QS-VVC) solution is designed based on a layered coding approach with one base layer (BL) and one or more enhancement layers (EL). To achieve higher compression performance, a novel joint layer referencing approach is proposed where the base and enhancement layers decoded information are jointly exploited to create a new EL coding reference. Experimental results shown that the proposed QS-VVC codec outperforms the most relevant benchmarks, notably VVC-based simulcasting, native VVC quality scalability, and the previous ScalableHoangVan Xiemxiemhoang@vnu.edu.vnNguyen Quang SangJeon Byeungwoo2020-12-08T09:33:08Z2021-06-28T02:41:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4148This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41482020-12-08T09:33:08ZNanomaterials for Organic Optoelectronic Devices: Organic Light-Emitting Diodes,
Organics Solar Cells and Organic Gas SensorsThis paper presents a unified view on applied nanomaterials that have been developed for a group of organic optoelectronic devices such as
Organic Light-Emitting Diodes (OLEDs), Solar Cells (OSCs) and Gas Sensors (OGSs). From recent references, included our unpublished one, it
has been demonstrated that nanostructured particles of metals, semiconductors, and oxides in conducting polymers embedded in conducting
polymers have significantly contributed to improving both the performance parameters and working time of devices. The presence of inorganic
nanoparticles in polymeric matrices has strongly influenced all physical properties of the polymers. However, herein the most interesting
properties of OLEDs, OSCs, and OGSs are of electro-luminescence, photo-electrical conversion, and gas sensing, respectively. A publication has
been seen regarding the nanostructured materials used for the fabrication of nanocomposite devices which aim at different practical purposes.Phuong Hoai Nam Nguyennamnph@vnu.edu.vn2020-12-08T09:29:38Z2020-12-08T09:29:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4141This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41412020-12-08T09:29:38ZDevelopment of a microfluidic flow-focusing droplet generating device utilising rapid prototyping techniqueIn the recent decades, droplet-based microfluidics has emerged as a promising research area which covers various applications in a broad spectrum of fields such as chemical reactions, drug discovery, molecule synthesis and cell biology. This study proposes the implementation of a microfluidic droplet generating prototype using the popular flow-focusing geometry. The proposed system is fabricated based on a rapid prototyping technique, which significantly simplifies the fabrication process, reduces the production cost and shortens the time-to-market as compared with traditional techniques. The functionalities and characteristics of the prototype were carefully verified by simulations and practical experiments. The obtained results showed that the generation of droplets could be precisely controlled by adjusting the flow rate ratio between the dispersed phase and the continuous phase.Xuan Loc Phamxuanloc97ars@vnu.edu.vnQuang Loc Dolocdq@gmail.comQuoc Tuan Vutvu.tuan@gmail.comNhu Cuong Nguyencuongnn241@gmail.comThu Hang Nguyenhang021197@gmail.comThanh Hang Tranhangtt.uet@vnu.edu.vnNgoc An Nguyenngocan@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vnDuc Trinh Chutrinhcd@vnu.edu.vn2020-12-08T09:29:25Z2020-12-08T09:29:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4138This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41382020-12-08T09:29:25ZElectrostatic modulation of a photonic crystal resonant filterWe demonstrate continuous and reversible spectral modulation of a photonic crystal cavity resonant mode using electrostatic force. The design and simulation of an H0 cavity were done using finite-element analysis methods. Fabrication of the sample device was done in a cleanroom using state-of-the-art nanotechnologies that are compatible with fabrication techniques for complementary metal-oxide semiconductors and microelectromechanical systems. Upon the change of the applied bias voltage, the resonant tuning effect is quantitatively demonstrated. Furthermore, the dynamic response of the transmission output intensity with respect to the oscillating applied voltage is demonstrated.Minh Hoang Nguyenhoang.photonics@gmail.comThanh Tung Buitungbt@vnu.edu.vn2020-12-08T09:28:41Z2020-12-08T09:28:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4136This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41362020-12-08T09:28:41ZAn electrohydrodynamic gyroscopeA novel configuration of gyroscope using an electro-hydrodynamics flow circulating in a confined space
is developed. The configuration includes three corona discharge based actuators to generate ionic flows inside three separated sub-channels which are connected to the main chamber. Ionic flows are merged together while they move through a nozzle installed at the main chamber entrance. After the merging phase, the conflated flow is diverged to move back to sub-channels where each accelerates at the discharge actuator. A master ring is installed at the end of the nozzle to remove any residual charge of the conflated ion flow. The ion flow velocity is measured using several hotwires installed in the main chamber. Since the configuration does not require any vibrating components, the present device is robust,
cost-effective and consumes low power, hence, very potential in application of inertial sensing.Van Ngoc Tranvanngoc@gmail.comThanh Van Dauv.dau@griffith.edu.auCanh-Dung TranCanh-Dung.Tran@usq.edu.auXuan Thien Dinhthien@cfd.ritsumei.ac.jpThanh Hoa Phanp.hoa@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vn2020-12-08T09:28:32Z2020-12-08T09:28:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4134This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41342020-12-08T09:28:32ZA new structure of Tesla coupled nozzle in synthetic jet micro-pumpSynthetic jet pump is a potential technique to improve the pumping performance by introducing a smart structure which can enhance counter-rotating vortexes. Aligning with this approach, a new structure of valveless micro-pump is developed in this work. The mechanism of the present micro-pump is based on the combination of the nozzle and a tesla element to rectify the synthetic jet. The new structure of “ace of spades” nozzle, named Tesla coupled nozzle, creates series of vortexes at the orifice of the pump chamber that allows to attenuate the reversed flows while fluid is drawn through the pump. The present
micro-pump is simple but robust and can perform at rather low voltages.Canh-Dung TranCanh-Dung.Tran@usq.edu.auHong Phuc Phamphucph-fme@mail.hut.edu.vnTuan-Khoa Nguyenkhoa.nguyentuan@griffithuni.edu.auHoang-Phuong Phanphuong.phanhoang@griffithuni.edu.auToan Dinhtoan.dinh@griffithuni.edu.auThanh Viet Nguyenthanh.nguyenviet@griffithuni.edu.auThanh Tung Buitungbt@vnu.edu.vnDuc Trinh Chutrinhcd@vnu.edu.vnNam-Trung Nguyennam-trung.nguyenEmailgriffith.edu.auDzung Viet Daod.dao@griffith.edu.auThanh Van Dauv.dau@griffith.edu.au2020-12-08T09:28:16Z2020-12-08T09:28:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4132This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41322020-12-08T09:28:16ZSimulation and Experimental Study of a Synthetic Jet Valveless PumpA valveless microfluidic pump using a Lead Zirconate Titanate (PZT) diaphragm-actuated synthetic jet is developed and fabricated. For this present design, a valveless pump structure is developed in which the pump chamber is sealed one side and connected to an emitting nozzle at another side. The design is simulated using the multi-physics approach and then successfully investigated with a prototype produced by a low-cost additive fabrication technique. The device’s parameters including
the liquid pumping characteristics and the size of PZT membrane are optimized based on its desired performance. The developed device can be applied over a wide range of applications from micro-mixing to fluidic controlling.Luan Le Vanluanlv@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vnNhu Cuong Nguyencuongnn241@gmail.comNgoc An Nguyenngocan@vnu.edu.vnThien Xuan Dinhthien@cfd.ritsumei.ac.jpBao Lam Danglam.dangbao@hust.edu.vnCanh-Dung TranCanh-Dung.Tran@usq.edu.auDuc Trinh Chutrinhcd@vnu.edu.vnThanh Van Dauv.dau@griffith.edu.au2020-12-08T09:28:03Z2020-12-08T09:28:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4133This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41332020-12-08T09:28:03ZStudy on Design Optimization of a Symmetry Two-Axis Tilt Angle Capacitive SensorThis paper presents the design, optimization, fabrication and characterization of a symmetrical twoaxis tilt angle sensor. The sensor consists of a globe-calotte-shaped excitation electrode and two pairs of sensing electrodes of the same dimensions, positioned symmetrically on a 3D printed hollow sphere. The sphere is filled with oil and air, and then mounted on the surface of a printed circuit board (PCB) for mechanical packaging and measurement. Experimental results show that the sensor can measure the tilt angle in both the x- and y-axes with sensitivity of 124 mV/° and resolution of ±0.15° in the range from −35° to 35°. The characteristics of the sensor on the x- and y-axes are similar. The proposed sensor can be used in several applications.Dac Hai Nguyenhaind75@gmail.comThi Thuy Ha Trantttha@gmail.comQuoc Tuan Vuvqtuan0211@gmail.comVan Thai Lethailv@haui.edu.vnDuc Trinh Chutrinhcd@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vnNgoc An Nguyenngocan@vnu.edu.vn2020-12-08T09:17:50Z2020-12-08T09:17:50Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4176This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41762020-12-08T09:17:50ZA Deep Wavelet Sparse Autoencoder Method for Online and Automatic Electrooculographical Artifact RemovalThe Hoang Anh NguyenThe Duy Buiduybt@vnu.edu.vnThanh Ha Leltha@vnu.edu.vn2020-12-07T14:07:31Z2020-12-21T09:33:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4155This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41552020-12-07T14:07:31ZPCA-Based Robust Motion Data RecoveryHuman motion tracking is a prevalent technique in many fields. A common difficulty encountered in motion tracking is the corrupted data is caused by detachment of markers in 3D motion data or occlusion in 2D tracking data. Most methods for missing markers problem may quickly become ineffective when gaps exist in the trajectories of multiple markers for an extended duration. In this paper, we propose the principal component eigenspace based gap filling methods that leverage a training sample set for estimation. The proposed method is especially beneficial in the scenario of motion data with less predictable or repeated movement patterns, and that of even missing entire frames within an interval of a sequence. To highlight algorithm robustness, we perform algorithms on twenty test samples for comparison. The experimental results show that our methods are numerical stable and fast to work.Zhuorong LiHongchuan YuHai Dang KieuTung Long VuongJian Jun Zhang2020-12-07T04:19:27Z2020-12-07T04:19:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4146This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41462020-12-07T04:19:27ZGenerative Software Module Development for Domain-Driven Design with Annotation-Based Domain Specific LanguageMinh Duc LeDuc Hanh Danghanhdd@vnu.edu.vnViet Ha Nguyenhanv@vnu.edu.vn2020-12-04T08:25:59Z2020-12-04T08:25:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4118This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41182020-12-04T08:25:59ZThe effect of cracks and thermal environment on free vibration of FGM platesThe free vibration parameters of cracked functionally graded material (FGM) plates with nonlinear varying thickness according to the symmetric parabola function under temperature is studied in this paper. The temperature transfers through the thickness of the FGM plate and material properties of the plate are distributed power law in the thickness direction and depend on the temperature. The formulas were developed based on Shi's third-order shear deformation theory and the phase field theory in destructive mechanics. The results of the present approach are compared with the existing literature for the validation. The free vibration frequencies of the plate are calculated depending on various parameters such as crack length, crack angle, plate length ratio, temperature, volume fraction index and boundary conditions. In addition, the effect of plate edges and symmetrical parabolic thickness shapes on the natural frequencies of FGM plates are also studied.Minh Phuc PhamDinh Duc Nguyenducnd@vnu.edu.vn2020-12-04T08:25:31Z2020-12-04T08:25:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4116This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41162020-12-04T08:25:31ZVibration and nonlinear dynamic analysis of sandwich FG-CNTRC plate with porous core layerThis paper focuses on the influence of CNTs, porosity, mechanical and thermal loading on the vibration and dynamic response of the sandwich functionally graded carbon nanotube-reinforced composite (FG-CNTRC) composite plate. The plate is made by three layers in which the core layer is porous FGM materials, bottom and top surfaces are FG-CNTRC. The motion equations are given based on Hamilton’s principle, TSDT, Galerkin method and the fourth-order Runge–Kutta method. The numerical illustration is shown to examine the influence of various parameters such as porosity distribution, CNTs volume fraction, geometrical parameters, elastic foundations, temperature, mechanical loads on the dynamic behaviors of the plate.Dinh Dat NgoVan Thanh NguyenMinh Anh VuDinh Duc Nguyenducnd@vnu.edu.vn2020-12-04T08:25:20Z2020-12-04T08:25:20Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4114This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41142020-12-04T08:25:20ZAn analytical approach for nonlinear thermo-electro-elastic forced vibration of piezoelectric penta – Graphene platesThis paper deals with the nonlinear forced vibration of imperfect penta – graphene plates integrated with piezoelectric actuator layers. The plate is subjected to combination of mechanical, thermal, and electrical loadings. Based on the first order shear deformation plate theory, the governing equations are established taken into account the effect of the von Kármán type of geometrical nonlinearity, the Pasternak type elastic foundations, the damping and the piezoelectric – thermal eﬀects. Four edges of the hybrid plate are assumed to be simply supported and immovable in the in-plane directions. The solution forms that satisfy the boundary conditions are assumed to be trigonometric. The closed form expressions of natural frequency, the frequency ratio – amplitude and the deflection amplitude – time curves are obtained by using the Galerkin and Runge – Kutta methods. The numerical results show positive effects of elastic foundations, negative effect of temperature increment and initial imperfection, considerable effect of geometrical parameters as well as small effect of applied voltage on the nonlinear forced vibration of piezoelectric penta – graphene plate.Quoc Quan TranVan Quyen NguyenDinh Duc Nguyenducnd@vnu.edu.vn2020-12-04T08:24:31Z2020-12-04T08:24:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4113This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41132020-12-04T08:24:31ZNonlinear buckling and post-buckling behavior of shear deformable sandwich toroidal shell segments with functionally graded core subjected to axial compression and thermal loadsThis paper presents an analytical investigation on buckling and post-buckling of shear deformable sandwich toroidal shell segments with functionally graded core and homogeneous face sheets. The effective material properties of core layer are graded in the thickness direction according to a simple power law distribution in terms of volume fraction index. The shells are surrounded by an elastic foundation and subjected to axial compressive or thermal loads. Reddy's third-order shear deformation shell theory (TSDT) is used to established formulations. A new solution using Galerkin method for solving a governing system of four-partial differential equations is carried out to obtain closed-form expressions of buckling stresses and post-buckling curves. Two cases of bowed-out and bowed-in sandwich toroidal shells are considered. Effects of material, geometric parameters and elastic foundation on stability behavior of the shells is analyzed in detail. The difference between bucking stresses basing on TSDT and those basing on classical shell theory (CST) is also clearly shown in this study.Minh Vuong PhamDinh Duc Nguyenducnd@vnu.edu.vn2020-12-04T08:24:16Z2020-12-04T08:24:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4112This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41122020-12-04T08:24:16ZBending and free vibration analyses of functionally graded material nanoplates via a novel nonlocal single variable shear deformation plate theoryA novel nonlocal shear deformation theory is established to investigate functionally graded nanoplates. The significant benefit of this theory is that it consists of only one unknown variable in its displacement formula and governing differential equation, but it can take into account both the quadratic distribution of the shear strains and stresses through the plate thickness as well as the small-scale effects on nanostructures. The numerical solutions of simply supported rectangular functionally graded material nanoplates are carried out by applying the Navier procedure. To indicate the accuracy and convergence of this theory, the present solutions have been compared with other published results. Furthermore, a deep parameter study is also carried out to exhibit the influence of some parameters on the response of the functionally graded material nanoplates.Kha Hoa LeVan Vinh Phamvinhpv@gmail.comDinh Duc Nguyenducnd@vnu.edu.vnThoi Trung NguyenTruong Son LeVan Thom Do2020-12-04T08:24:02Z2020-12-04T08:24:02Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4111This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41112020-12-04T08:24:02ZA first-principle study of nonlinear large amplitude vibration and global optimization of 3D penta-graphene plates based on the Bees AlgorithmPenta-graphene, a new monolayer of carbon atoms, has been synthesized with ideal strength and temperature resistance. However, the mechanical behavior of penta-graphene has not been fully investigated yet. This paper presents an analytical investigation on the nonlinear large amplitude vibration of imperfect three-dimensional (3D) penta-graphene plates subjected to uniformly distributed external pressure with simply supported and immovable edges in thermal environments. The elastic constants and the thermal expansion coefficients of the 3D penta-graphene plate are determined using the density functional theory. The motion and compatibility equations are established based on the Reddy’s higher-order shear deformation plate theory in which the effect of von Karman nonlinear terms, the initial imperfection and the Pasternak elastic foundation are taken into consideration. The Galerkin method is applied to determine the closed-form expressions of linear frequency and nonlinear to linear frequency ratio while the dynamic response of the plate is obtained by using the fourth-order Runge–Kutta method. The Bees Algorithm is used to determine the optimum value of the natural frequency which depends on five variables including the thickness, the length and the width of penta-graphene plates and two stiffness coefficients of elastic foundations. The numerical results show the effects of width-to-thickness ratio, elastic foundations coefficients, initial imperfection parameter and temperature increment on the nonlinear vibration of the 3D penta-graphene plates.Dinh Dat NgoQuoc Quan TranPhuong TranDinh Duc Nguyenducnd@vnu.edu.vnTien Lam Pham2020-12-04T08:23:43Z2020-12-04T08:23:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4110This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41102020-12-04T08:23:43ZNonlinear static and dynamic stability of functionally graded toroidal shell segments under axial compressionThis work presents an analytical approach to investigate nonlinear static and dynamic stability of toroidal shell segments resting on elastic foundation subjected to axial compression. The shells are made of functionally graded material (FGM) which created from metal and ceramic, and the volume fraction of constituents is supposed to gradually vary from one surface to another according to a power law function. Basic formulations are established based on Reddy's third-order shear deformation shell theory (TSDT) considering geometrical nonlinearity in von Kármán sense. Governing system of four-partial differential equations are converted into nonlinear differential equation using Galerkin method. Runge-Kutta method is used to solve nonlinear differential equation of motion and then nonlinear dynamic response of shell are examined. Budiansky-Roth criterion are used to obtain critical dynamic buckling load and then nonlinear dynamic stability of shells under axial compressive load linearly varying on time is analyzed. The influences of material and geometrical parameters, and elastic foundations on the static and dynamic stability of FGM toroidal sell segments are discussed in detail. The obtained results are validated by comparing with other results in the literature.Minh Vuong PhamDinh Duc Nguyenducnd@vnu.edu.vn2020-12-04T08:21:16Z2020-12-04T08:21:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4117This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41172020-12-04T08:21:16ZNonlinear forced vibrations analysis of imperfect stiffened FG doubly curved shallow shell in thermal environment using multiple scales methodThis study investigates the non-linear vibrations of stiffened imperfect functionally graded double-curved shallow shells, as rested on nonlinear elastic foundations. The shells are exposed to external harmonic excitation and are placed in the thermal situations. The modeling of shells is derived according to the classical shell theory and the non-linear geometric von Kármán relationships. It is considered that the distribution of material properties changes along the thickness direction based on a power law index. The smeared stiffener technique is considered to model the stiffened shells. An approximation, according to Galerkin’s approach, is utilized to reduction of the shell governing equations into the non-linear coupled ordinary differential relations. The ODE equations are analytically solved and analyzed through the perturbation methodology for investigating the resonance behavior of shells. Simulation results are reported to examine the influences of stiffeners, initial imperfection, foundation coefficients, thermal environment, and geometrical characteristics on the non-linear primary resonance response of doubly curved shallow shells. Also, the nonlinear dynamic behaviors are analyzed by numerical methods through the bifurcation diagrams, and the nonlinear dynamical behaviors of the shell for different value of parameters are examined.Ahmadi HabibBayat AliakbarDinh Duc Nguyenducnd@vnu.edu.vn2020-11-30T14:57:05Z2020-11-30T14:57:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4095This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40952020-11-30T14:57:05ZVeRA: Verifying RBAC and authorization constraints models of web applicationsThe software security issue is being paid great attention from the software development community as security violations have emerged variously. Developers
often use access control techniques to restrict some security breaches to software
systems’ resources. The addition of authorization constraints to the role-based
access control model increases the ability to express access rules in real-world
problems. In this paper, we introduce an approach to reviewing the implementation of these models in web applications written by JavaEE according to the MVC
architecture under the support of the Spring Security framework. The proposed
method helps developers detect flaws in the assignment implementation process
of the models. Firstly, the approach focuses on extracting the information about
users and roles from the database of the web application. We then analyze policy
configuration files to establish the access analysis tree of the system. Next, algorithms are introduced to validate the correctness of implemented user - role and
role - permission assignments in the application system against the role-based access control and authorization constraint specification by the SecureUML model.
Lastly, we developed a tool called VeRA, to automatically support the verification process. The tool has also experimented with a number of access violation
scenarios in the medical record management system.Thanh Nhan LuongNinh Thuan Truongthuantn@vnu.edu.vn2020-11-30T07:03:47Z2020-11-30T07:03:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4089This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40892020-11-30T07:03:47ZGiant magnetoelectric effects in serial-parallel connected Metglas/PZT arrays with magnetostrictively homogeneous laminatesTo ensure the magnetostrictive softness, the homogeneity, the decrease of the shear-lag effect and the
space-saving construction of narrowed longitudinal-transverse L-T magnetoelectric (ME) composites, a
novel parallel-connected-multi-bars (PCMB) geometry of PZT/Metglas is proposed and investigated by
simulation and experiment. In this case, Metglas layers are structured in different geometries from the
conventional single bar (c-SB) to conventional separated multiple bars (c-SMB), elongated separate
multi-bar (e-SMB) and n-magnetic-bar based PCMB (n-PCMB). This n-PCMB geometry divides the conventional
ME configuration into n parallel-connected ME units (n-PCMEU) according to the magnetic
geometries. The optimal ME performance with the largest ME voltage coefficient aE of 630 V/cm.Oe is
achieved in PCMEU with two Metglas bars (n = 2). The ME voltage coefficient can be further enhanced by
integrating m of these optimal PCMEUs in series to form a serial-parallel ME unit array m-S (n-PMEU)A.
The aE value increases by a factor of 3.6 and reaches 2.238 kV/cm.Oe for 4-S (2-PMEU)A, a factor that is
almost equal to m. The resulting 4-S (2-PMEU)A sensor possesses an extremely high sensitivity of
18.1 mV/nT, with a resolution of 10�1 nT.Dinh Cuong TrinhViet Hung Nguyenviethung1996vn@gmail.comLe Ha VuAnh Tuan PhungDinh Duong DoAnh Tam Hohoanhtam@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vnThi Huong Giang Dogiangdth@vnu.edu.vn2020-11-30T07:03:26Z2020-11-30T07:03:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4088This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40882020-11-30T07:03:26ZMagnetoelectric Vortex Magnetic Field Sensors Based
on the Metglas/PZT LaminatesThis paper describes the route, from simulations toward experiments, for optimizing the
magnetoelectric (ME) geometries for vortex magnetic field sensors. The research is performed on the
base of the Metglas/Piezoelectric (PZT) laminates in both open and closed magnetic circuit (OMC and
CMC) geometries with di�erent widths (W), lengths (L), and diameters (D). Among these geometries,
the CMC laminates demonstrate advantages not only in their magnetic flux distribution, but also in
their sensitivity and in their independence of the position of the vortex center. In addition, the ME
voltage signal is found to be enhanced by increasing the magnetostrictive volume fraction. Optimal
issues are incorporated to realize a CMC-based ME double sandwich current sensor in the ring shape
with D � W = 6 mm � 1.5 mm and four layers of Metglas. At the resonant frequency of 174.4 kHz,
this sensor exhibits the record sensitivity of 5.426 V/A as compared to variety of devices such as the
CMC ME sensor family, fluxgate, magnetoresistive, and Hall-e�ect-based devices. It opens a potential
to commercialize a new generation of ME-based current and (or) vortex magnetic sensors.Thi Huong Giang Dogiangdth@vnu.edu.vnAnh Tam Hohoanhtam@vnu.edu.vnThi Ngoc Khanh VuTrong Vinh NguyenAnh Tuan PhungVan Tuan NguyenThi Ngoc NguyenHuu Duc Nguyenducnh@vnu.edu.vn2020-11-26T04:47:14Z2020-11-26T04:47:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4087This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40872020-11-26T04:47:14ZFPGA-Based Lightweight Hardware Architecture of the PHOTON Hash Function for IoT Edge DevicesThe design of cryptographic engines for the Internet of Things (IoT) edge devices and other ultralightweight devices is a crucial challenge. The emergence of such resource-constrained devices raises significant challenges to current cryptographic algorithms. PHOTON is an ultra-lightweight cryptographic hash function targeting low-resource devices. The currently implemented hardware architectures of PHOTON hash function utilize a large amount of resources and have low operating frequencies with a low rate of throughputs. Maximum operating frequency and throughput of PHOTON architecture can be improved but at the cost of larger area utilization. Therefore, to improve the area-performance trade-offs of PHOTON hash function, an iterative architecture is implemented in this work. The concern is with the most lightweight version of PHOTON hash function with the hash size of 80 bits. It is implemented and verified on several Xilinx and Altera Field Programmable Gate Array (FPGA) devices using their synthesis and simulation tools. Low-cost and high-processing FPGA devices were both considered. The design is optimized for performance, whereas the area utilization is also taken into consideration. The overall performance and logic utilization are benchmarked with the existing implementations. The results show an improvement rate of 10.26% to 51.04% in the speed performance and a reduction rate of 7.55% to 60.64% in area utilization compared to existing implementations of PHOTON hash functions.Mohammed Omar Awadh Al-Shatarim.alshatari@gmail.comFawnizu Azmadi Hussinfawnizu@utp.edu.myAzrina Abd Azizazrina_aaziz@utp.edu.myGunawan Witjaksonogwitjaksono@binus.eduXuan Tu Trantutx@vnu.edu.vn2020-10-13T08:45:45Z2020-10-13T08:45:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4081This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40812020-10-13T08:45:45ZLow-power High-performance 32-bit RISC-V Microcontroller on 65-nm Silicon-On-Thin-BOX (SOTB)In this paper, a 32-bit RISC-V microcontroller in a 65-nm Silicon-On-Thin-BOX (SOTB) chip is presented. The system is developed based on the VexRiscv Central Processing Unit (CPU) with the Instruction Set Architecture (ISA) extensions of RV32IM. Besides the core processor, the System-on-Chip (SoC) contains 8KB of boot ROM, 64KB of on-chip memory, UART controller, SPI controller, timer, and GPIOs for LEDs and switches. The 8KB of boot ROM has 7KB of hard-code in combinational logics and 1KB of a stack in SRAM. The proposed SoC performs the Dhrystone and Coremark benchmarks with the results of 1.27 DMIPS/MHz and 2.4 Coremark/MHz, respectively. The layout occupies 1.32-mm2 of die area, which equivalents to 349,061 of NAND2 gate-counts. The 65-nm SOTB process is chosen not only because of its low-power feature but also because of the back-gate biasing technique that allows us to control the microcontroller to favor the low-power or the high-performance operations. The measurement results show that the highest operating frequency of 156-MHz is achieved at 1.2-V supply voltage (VDD) with +1.6-V back-gate bias voltage (VBB). The best power density of 33.4-µW/MHz is reached at 0.5-V VDD with +0.8-V VBB. The least current leakage of 3-nA is retrieved at 0.5-V VDD with -2.0-V VBB.Trong Thuc HoangCkristian DuranKhai Duy NguyenTuan Kiet DangQuang Nhu Quynh NguyenPhuc Hong ThanXuan Tu Trantutx@vnu.edu.vnDuc Hung LeAkira TsukamotoKuniyasu SuzakiCong Kha Phampham@ee.uec.ac.jp2020-10-13T08:21:31Z2020-10-13T08:21:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4075This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40752020-10-13T08:21:31ZMotion-Encoded Particle Swarm Optimization for Moving Target Search Using UAVsThis paper presents a novel algorithm named the motion-encoded particle swarm optimization (MPSO) for finding a moving target with unmanned aerial vehicles (UAVs). From the Bayesian theory, the search problem can be converted to the optimization of a cost function that represents the probability of detecting the target. Here, the proposed MPSO is developed to solve that problem by encoding the search trajectory as a series of UAV motion paths evolving over the generation of particles in a PSO algorithm. This motion-encoded approach allows for preserving important properties of the swarm including the cognitive and social coherence, and thus resulting in better solutions. Results from extensive simulations with existing methods show that the proposed MPSO improves the detection performance by 24\% and time performance by 4.71 times compared to the original PSO, and moreover, also outperforms other state-of-the-art metaheuristic optimization algorithms including the artificial bee colony (ABC), ant colony optimization (ACO), genetic algorithm (GA), differential evolution (DE), and tree-seed algorithm (TSA) in most search scenarios. Experiments have been conducted with real UAVs in searching for a dynamic target in different scenarios to demonstrate MPSO merits in a practical application.Manh Duong Phungduongpm@vnu.edu.vnQuang Haquang.ha@uts.edu.au2020-10-09T07:10:25Z2020-10-09T07:10:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4071This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40712020-10-09T07:10:25ZApplication of WRF-Chem to simulate air quality over Northern VietnamThe WRF-Chem (Weather Research and Forecasting with Chemistry) model is implemented and validated against ground-based observations for meteorological and atmospheric variables for the first time in Northern Vietnam. The WRF-Chem model was based on HTAPv2 emission inventory with MOZCART chemical-aerosol mechanism to simulate atmospheric variables for winter (January) and summer (July) of 2014. The model satisfactorily reproduces meteorological fields, such as temperature 2 m above the ground and relative humidity 2 m above the ground at 45 NCHMF meteorological stations in January, but lower agreement was found in those simulations of July. PM10 and PM2.5 concentrations in January showed good temporal and spatial agreements to observations recorded at three CEM air monitoring stations in Phutho, Quangninh, and Hanoi, with correlation coefficients of 0.36 and 0.59. However, WRF-Chem model was underestimated with MFBs from − 27.9 to − 118.7% for PM10 levels and from − 34.2 to − 115.1% for PM2.5 levels. It has difficulty in capturing day-by-day variation of PM10 and PM2.5 concentrations at each station in July, but MFBs were in the range from − 27.1 to − 40.2% which is slightly lower than those in January. It suggested that further improvements of the model and local emission data are needed to reduce uncertainties in modeling the distribution of atmospheric pollutants. Assessment of biomass burning emission on air quality in summer was analyzed to highlight the application aspect of the WRF-Chem model. The study may serve as a reference for future air quality modeling using WRF-Chem in Vietnam.Thi Nhu Ngoc Dongocdtn@fimo.edu.vnXuan Truong Ngotruongnx@fimo.edu.vnVan Ha Phamhapv@fimo.edu.vnNhu Luan Vuongluannv@cem.gov.vnHoang Anh LeChau Thuy PhamQuang Hung Buihungbq@vnu.edu.vnThi Nhat Thanh Nguyenthanhntn@vnu.edu.vn2020-09-14T02:55:49Z2020-09-14T02:55:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4061This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40612020-09-14T02:55:49ZA new constraint programming model and a linear programming-based adaptive large neighborhood search for the vehicle routing problem with synchronization constraintsWe consider a vehicle routing problem which seeks to minimize cost subject to time window and synchronization constraints. In this problem, the fleet of vehicles is categorized into regular and special vehicles. Some customers require both vehicles’ services, whose service start times at the customer are synchronized. Despite its important real-world application, this problem has rarely been studied in the literature. To solve the problem, we propose a Constraint Programming (CP) model and an Adaptive Large Neighborhood Search (ALNS) in which the design of insertion operators is based on solving linear programming (LP) models to check the insertion feasibility. A number of acceleration techniques is also proposed to significantly reduce the computational time. The computational experiments show that our new CP model finds better solutions than an existing CP-based ALNS, when used on small instances with 25 customers and with a much shorter running time. Our LP-based ALNS dominates the CP-based ALNS, in terms of solution quality, when it provides solutions with better objective values, on average, for all instance classes. This demonstrates the advantage of using linear programming instead of constraint programming when dealing with a variant of vehicle routing problems with relatively tight constraints, which is often considered to be more favorable for CP-based methods. We also adapt our algorithm to solve a well-studied variant of the problem, and the obtained results show that the algorithm provides good solutions as state-of-the-art approaches and improves four best known solutions.Minh Hoang Haminhhoang.ha@vnu.edu.vnTat Dat NguyenDuy Thinh NguyenHoang Giang PhamThuy DoLouis-Martin Rousseau2020-09-14T02:55:14Z2020-09-14T02:55:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4064This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40642020-09-14T02:55:14ZImprovements on the performance of SCM/WDM-based RoF systemRadio over Fiber (RoF) techniques are good candidates to create the backbone of the next generation of wireless networks. Many parameters affect RoF communications such as amplified spontaneous emission noise (ASE), four-wave mixing nonlinearity (FWM), the modulation, channel spacing, switching voltage, and phase shifter. In this paper, we propose an improved model of RoF communication systems using subcarrier multiplexing/wavelength division multiplexing (SCM/WDM) technique with unequal channel spacing and 1-km Erbium-doped fiber amplifier (EDFA). Simulation results confirmed that we could obtain the lowest bit error rate and noises when the EDFA is placed at 1 km from the transmitter by using optical single-sideband (OSSB) modulation at frequencies 193.1, 193.2, 193.35, and 193.6 THz.Duc Tan Trantantd@vnu.edu.vnTrung Ninh Buininhbt@vnu.edu.vn2020-09-14T02:52:10Z2020-09-14T02:52:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4060This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40602020-09-14T02:52:10ZSolving the k-dominating set problem on very large-scale networksThe well-known minimum dominating set problem (MDSP) aims to construct the minimum-size subset of vertices in a graph such that every other vertex has at least one neighbor in the subset. In this article, we study a general version of the problem that extends the neighborhood relationship: two vertices are called neighbors of each other if there exists a path through no more than k edges between them. The problem called “minimum k-dominating set problem” (MkDSP) becomes the classical dominating set problem if k is 1 and has important applications in monitoring large-scale social networks. We propose an efficient heuristic algorithm that can handle real-world instances with up to 17 million vertices and 33 million edges. This is the first time such large graphs are solved for the minimum k-dominating set problemMinh Hai NguyenMinh Hoang Haminhhoang.ha@vnu.edu.vnDiep Nguyen NDiep.Nguyen@uts.edu.auThe Trung Trantrung@fpt.edu.vn2020-09-14T02:51:25Z2020-09-14T02:51:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4056This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40562020-09-14T02:51:25ZOpposite Partial Response Filter for Shingled Magnetic Recording SystemsShingled magnetic recording (SMR) is regarded as the most influential technology for the next-generation magnetic recording systems. The SMR tracks are partly overlapped by each other, and the SMR systems can obtain higher area densities by increasing track per inch density. As a result, this brings more interference from the adjacent sidetracks, i.e., intertrack interference (ITI) while reading the home track. In this letter, we are interested in applying the filtering process to the squeezed tracks before recording to improve the quality of retrieved data. The preprocessing is to reduce the effect of unwanted signals from the sidetracks on the home track. The results show that the SMR system's performance is vastly improved even under the extremely severe effects of the ITI.Dinh Chi NguyenThu Phuong NguyenSinh Cong Lamcongls@vnu.edu.vn2020-09-07T08:16:54Z2020-11-29T02:17:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4049This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40492020-09-07T08:16:54ZA thermal-aware on-line fault tolerance method for TSV lifetime reliability in 3D-NoC systemsThrough-Silicon-Via (TSV) based 3D Integrated Circuits (3D-IC) are one of the most advanced architectures by providing low power consumption, shorter wire length and smaller footprint. However, 3D-ICs confront lifetime reliability due to high operating temperature and interconnect reliability, especially the Through-Silicon-Via (TSV), which can significantly affect the accuracy of the applications. In this paper, we present an online method that supports the detection and correction of lifetime TSV failures, named IaSiG. By reusing the conventional recovery method and analyzing the output syndromes, IaSiG can determine and correct the defective TSVs. Results show that within a group, $R$ redundant TSVs can fully localize and correct $R$ defects and support the detection of $R+1$ defects. Moreover, by using $G$ groups, it can localize up to GxR and detect up to Gx(R+1) defects. An implementation of IaSiG for 32-bit data in eight groups and two redundancies has a worst-case execution time (WCET) of 5,152 cycles while supporting at most 16 defective TSVs (50\% localization).
By integrating IaSiG onto a 3D Network-on-Chip, we also perform a grid-search based empirical method to insert suitable numbers of redundancies into TSV groups. The empirical method takes the operating temperature as the factor of accelerated fault due to the fact that temperature is one of the major issues of 3D-ICs. The results show that the proposed method can reduce the number of redundancies from the uniform method while still maintaining the required Mean Time to Failure.Nam Khanh Dangdnk0904@gmail.comAkram Ben AhmedAbderazek Ben Abdallahbenab@u-aizu.ac.jpXuan Tu Trantutx@vnu.edu.vn2020-07-29T08:16:59Z2020-07-29T08:16:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4035This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40352020-07-29T08:16:59ZNanomaterials for Organic Optoelectronic Devices: Organic Light-Emitting Diodes, Organics Solar Cells and Organic Gas SensorsNang Dinh Nguyendinhnn@vnu.edu.vnSi Trong Khanh TranMinh Long LamDuc Cuong Nguyencuongnd@vnu.edu.vnPhuong Hoai Nam Nguyennamnph@vnu.edu.vn2020-07-29T08:14:18Z2020-07-29T08:14:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4029This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40292020-07-29T08:14:18ZSmartphone-based Indoor Positioning Using BLE iBeacon and Reliable Lightweight Fingerprint MapThe introduction of Bluetooth Low Energy (BLE)
technology provides new opportunities that the Global Positioning System (GPS) could not provide for indoor localization. In this article, we propose a real-time indoor tracking and positioning system using BLE beacon and smartphone sensors. Up to now, most of the system is using Pedestrian Dead Reckoning (PDR). The initial position is considered to have a high impact on the accuracy of PDR, so, based on the analysis of received signal strength (RSS), we present a method to estimate the approximate distance, then, estimate the initial position through Trilateration technique. Next,
we propose a lightweight and reliable fingerprintmethod. This
method addresses two problems: (1) to correct errors due to
the initial position error and orbital drift of PDR, (2) to reduce theamount of data, number of reference points and collecting
data time. The proposed system is implemented on hesmartphone as an application.To verify the accuracy of the system, we performed some experiments. The results show that the system not only achieves high accuracy but also the high
performance with average complexity and low cost.Thi Thai Mai Dinhdttmai@vnu.edu.vnNgoc Son Duongduongson.vnu@gmail.comSandrasegaran KumbesanKumbesan.Sandrasegaran@uts.edu.au2020-07-18T02:01:54Z2020-07-18T02:01:54Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4018This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40182020-07-18T02:01:54ZAnalytical solutions for nonlinear magneto-electro-elastic vibration of smart sandwich plate with carbon nanotube reinforced nanocomposite core in hygrothermal environmentThis paper presents an analytical approach on the nonlinear magneto-electro-elastic vibration of smart sandwich plate. The sandwich plate consists of a carbon nanotube reinforced nanocomposite (CNTRC) core integrated with two magneto-electro-elastic face sheets. For core layer, three types of carbon nanotube (CNT) distribution such as FG-O, FG-V, FG-X are considered while the volume fraction of BaTiO3 − CoFe2O4 in each face sheet is chosen to be 0.5. It is assumed that the smart sandwich plate is rested on Pasternak-type elastic foundations and subjected to the combination of external pressure, thermal, electric and magnetic loads. The coupled constitutive relations are derived based on the Hamilton's principle in which the kinematic nonlinearity is defined using Reddy's higher order shear deformation theory. The analytical solutions which satisfy the boundary conditions are assumed to have the trigonometric form. The Galerkin method is used to obtain the closed form expressions of natural frequency, the relation between the frequency ratio and dimensionless amplitude and the dynamic response of the sandwich plate. The numerical results are conducted to illustrate the effect of geometrical parameters, CNT volume fraction, temperature and moisture increment, electric and magnetic potentials on the nonlinear vibration of smart sandwich plate. The reliability of present results is evaluated by comparing with the previous results based on different approach.Dinh Dat NgoQuoc Quan Tranquantq1505@gmail.comMahesh VinyasDinh Duc Nguyenducnd@vnu.edu.vn2020-07-18T02:01:39Z2020-07-18T02:01:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4017This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40172020-07-18T02:01:39ZNonlinear dynamic analysis of piezoelectric functionally graded porous truncated conical panel in thermal environmentsIn this article, the nonlinear dynamic response and free vibration of functionally graded porous (FGP) truncated conical panel with piezoelectric actuators in thermal environments are investigated by an analytical method. The panel resting on an elastic foundation which is modeled according to the Winkler–Pasternak theory. The material properties including Young's modulus, shear modulus, and density are assumed to smoothly through the shell thickness. Three types of porosity distribution across the thickness, namely, symmetric porosity distribution, non-symmetric porosity, and uniform porosity distribution, are considered. Theoretical formulations are presented based on the first-order shear deformation shell theory with a von Karman-Donnell type of kinematic nonlinearity. The non-linear motion equations and resulting equations are derived by using Hamilton's principle, Galerkin's method, and Runge-Kutta method. Lastly, some numerical results are presented to study the effects of shell characteristics, porosity distribution, porosity coefficient, applied actuator voltage, temperature increment and elastic foundations on the nonlinear dynamic response and the natural frequencies of the piezoelectric FGP truncated conical panel.Quang Chan DoVan Thanh NguyenDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2020-07-18T02:01:15Z2020-07-18T02:01:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4015This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40152020-07-18T02:01:15ZNonlinear buckling and post-buckling analysis of shear deformable stiffened truncated conical sandwich shells with functionally graded face sheets and a functionally graded porous coreIn this study, the nonlinear buckling and post-buckling analysis of stiffened truncated conical sandwich shells with functionally graded face sheets and a functionally graded porous core resting on the Winkler–Pasternak elastic foundation subject to a uniform axial compressive load has been investigated. Shells are reinforced by functionally graded material stringers and rings, in which the change of spacing between stringers in the meridional direction also is taken into account. The stability equations of the shell are derived based on the first-order shear deformation theory with a von Karman–Donnell type of kinematic nonlinearity and the smeared stiffener technique. Those equations are solved by the Galerkin method to determine the effects of stiffeners, shell characteristics, material properties, porosity coefficient, and elastic foundation on the critical buckling load and for analyzing the post-buckling load–deﬂection curves. The approaches are verified with the known results in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimDinh Khoa NguyenQuang Chan Do2020-07-18T02:00:52Z2020-07-18T02:00:52Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4010This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40102020-07-18T02:00:52ZNonlinear stability and optimization of thin nanocomposite multilayer organic solar cell using Bees AlgorithmThis paper carries out the nonlinear stability of nanocomposite multilayer organic solar cell (NMOSC) subjected to axial compressive loads. The model of organic solar cell is assumed to consist five layers: Al, P3HT:PCBM, PEDOT:PSS, IOT and Glass. Based on the classical plate theory, the basic equations are established taking into account the effect of elastic foundations and initial imperfection. The approximation solutions are selected based on the boundary conditions of the four edges of NMOSC. The equation which indicates the relationship between axial compressive loads and deflection amplitude of NMOSC is obtained by using the Galerkin method. Bees Algorithm is applied to maximize the value of critical buckling load with nine variables including the thickness of five layers, the length and the width of NMOSC and two stiffness coefficients of elastic foundations. The numerical results show the effect of geometrical and material parameters, initial imperfection and elastic foundations on the nonlinear static stability and the critical buckling load of NMOSC. Optimal values of nine geometrical parameters of NMOSC are also determined.Dinh Dat NgoMinh Anh Vuvuminhanhhp@gmail.comQuoc Quan Tranquantq1505@gmail.comTruong Duc PhamDinh Duc Nguyenducnd@vnu.edu.vn2020-07-18T02:00:39Z2020-07-18T02:00:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4009This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40092020-07-18T02:00:39ZNonlinear Postbuckling of Eccentrically Oblique-Stiffened Functionally Graded Doubly Curved Shallow Shells Based on Improved Donnell EquationsThe nonlinear buckling and postbuckling of eccentrically oblique-stiffened doubly curved shallow functionally graded shells is investigated based on improved Donnell equations. The improved Lekhnitskii smeared stiffeners technique is employed to found the stiffness matrix of the stiffened shells. The shells are reinforced by eccentrically oblique stiffeners with an arbitrary inclination angle. Using the Galerkin method, an analytical approximate solution for the deflection of reinforced FGM doubly curved shallow shells is obtained. The influence of geometrical parameters, oblique stiffeners, and temperature on the postbuckling behavior of the shells is analyzed.Dinh Duc Nguyenducnd@vnu.edu.vnHoai Nam VuHuy Cuong Nguyen2020-07-18T02:00:24Z2020-07-18T02:00:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4008This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40082020-07-18T02:00:24ZNonlinear Post-Buckling of CNTs Reinforced Sandwich-Structured Composite Annular Spherical ShellsThis work presents the nonlinear post-buckling behavior of carbon nanotubes (CNTs) reinforced sandwich composite annular spherical (AS) shells supported by elastic foundations in the thermal environment. This paper takes advantage of the sandwich-structured configuration with three layers: two nanocomposite face sheets and an isotropic core to analyze the static problem. Due to the precious properties, CNTs are applied to reinforce nanocomposite face sheets of AS shells. The governing equations of the nonlinear mechanical response of CNTs reinforced sandwich-structured composite (SSC) AS shells are achieved by using the classical shell theory (CST) and taking von Kármán’s geometrical nonlinearity into account. Applying Airy’s stress function and an approximate solution, we propose a form of stress function for CNTs reinforced SSC AS shells. The detailed effects of different types of CNTs’ reinforcement and volume fractions, geometrical parameters, core to face sheet thickness ratio, Winkler and Pasternak elastic foundations on the nonlinear mechanical post-buckling analysis are examined.Tuan Manh DuongThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Nguyen Phamnguyenpd@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2020-07-18T01:52:45Z2020-07-18T01:52:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4011This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40112020-07-18T01:52:45ZVibration and nonlinear dynamic analysis of variable thickness sandwich laminated composite panel in thermal environmentBased on the first-order shear deformation theory taking into account geometrical nonlinearity, initial geometrical imperfection, vibration and nonlinear dynamic analysis of the sandwich laminated composite panel characterized by a continuous thickness variation in thermal environment and resting on an elastic foundation are considered in this paper. Variable thickness could affect the design of composite panel since it allows to tailor the stiffness features in the most stressed areas within the domain, keeping the weight constant. As a consequence, an improved dynamic behavior of the structure may be exhibited. The motion equations of dynamic analysis are determined due to Galerkin method and the obtained equation is numerically solved by using Runge–Kutta method. In numerical results, the effects of initial geometrical imperfections and geometrical parameters, material properties, coefficients of foundation, mechanical loads, temperature and the variable thickness on the nonlinear dynamic response and vibration of the laminated composite panel are investigatedDinh Duc Nguyenducnd@vnu.edu.vnEock Kim SeungThi Thuy Anh Vuanhvutt@vnu.edu.vnMinh Anh Vuvuminhanhhp@gmail.com2020-07-10T15:05:06Z2020-12-21T09:36:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3995This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39952020-07-10T15:05:06ZSecrecy Performance of Cooperative Cognitive
Radio Networks Under Joint Secrecy Outage and
Primary User Interference ConstraintsIn this paper, we investigate the secrecy performance of a Cooperative Cognitive Radio
Network (CCRN) in the presence of an eavesdropper (EAV). The secondary users (SUs) are subject to three
constraints which include peak transmit power level and interference limitation with respect to the primary
user (PU) as well as secrecy outage constraints due to the EAV. Secrecy outage is achieved when the EAV
cannot decode the targeted signal, but communications in the secondary network is still possible (non-zero
capacity exists). Approximation expressions of the secrecy outage probability and the probability of non-zero
secrecy capacity are derived to evaluate the secrecy performance. Monte Carlo simulations are provided to
examine the accuracy of the derived approximation expressions. Based on this, power allocation policies
for the SUs are derived, satisfying all the constraints while maximizing the secrecy performance as well as
the quality of service performance of the secondary network. It can be concluded that with knowledge of
the channel state information (CSI) of the EAV it is possible to calculate the optimal value for the secrecy
outage threshold of the secondary user (SU) which in turn allows maximizing the secrecy performance. Most
interestingly, our numerical results illustrate that the secrecy performance of the system is much improved
when the parameters obtained using the CSI of the EAV are calculated optimally. Thence, the system can
adjust the power allocation so that no eavesdropping occurs even without reducing quality of service (QoS)
performance compared to a network without any EAV.Xuan Truong Quachqxtruong@ictu.edu.vnHung Trantran.hung@mdh.seElisabeth Uhlemannelisabeth.uhlemann@mdh.seTruc Mai Tranmai.tran@vnu.edu.vn2020-07-10T14:57:17Z2020-07-29T08:39:33Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3968This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39682020-07-10T14:57:17ZTSV-OCT: A Scalable Online Multiple-TSV Defects Localization for Real-Time 3-D-IC SystemsIn order to detect and localize TSV failures in
both manufacturing and operating phases, most of the existing methods use a dedicated testing mechanism with long response time and prerequisite interruptions for on-line testing. This paper presents an ECC-based method named “Through-Silicon-Via On Communication Test” (TSV-OCT) to detect and localize faults without halting the operation of TSV-based 3D-IC systems. We ﬁrst propose Statistical Detector, a method to detect open and short defects in TSVs that work in parallel with data transactions.
Second, we propose an Isolation and Check algorithm to enhance the localization ability of the method. Moreover, the Monte-Carlo simulations show that the proposed Statistical Detector increases ×2 the number of detected faults when compared to conventional ECC-based techniques. With the help of Isolation and Check, TSV-OCT localizes the number of defects up to ×4 and ×5 higher. In addition, the response time is kept below 65,000 cycles which could be easily integrated into real-time applications. On
the other hand, an implementation of TSV-OCT on a 3D Network-on-Chip router shows no performance degradation for testing while having a reasonable area overhead.Nam Khanh Dangdnk0904@gmail.comAkram Ben AhmedAbderazek Ben Abdallahbenab@u-aizu.ac.jpXuan Tu Trantutx@vnu.edu.vn2020-07-10T05:51:47Z2020-07-10T05:51:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3998This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39982020-07-10T05:51:47ZAn Efficient Algorithm to Extract Control Flow-based Features for IoT Malware DetectionControl flow-based feature extraction method has the ability to detect malicious code with higher accuracy than traditional text-based methods. Unfortunately, this method has been encountering with the NP-hard problem, which is infeasible for the large-sized and high-complexity programs. To tackle this, we propose a control flow-based features extraction dynamic programming algorithm (CFD) for fast extraction of control flow-based features with polynomial time O(N^2), where N is the number of basic blocks in decompiled executable codes. From the experimental results, it is demonstrated that the proposed algorithm is more efficient and effective in detecting malware than the existing ones. Applying our algorithm to an IoT dataset gives better results on 3 measures: Accuracy (AC) = 99.05%, False Positive Rate (FPR) = 1.31% and False Negative Rate (FNR) = 0.66%.Nghi Phu Trantnphvan@gmail.comDai Tho Nguyennguyendaitho@vnu.edu.vnHuy Hoang Lehoangle.hvan@gmail.comNgoc Toan Nguyenngoctoan.hvan@gmail.comNgoc Binh Nguyennn_binh@kcg.edu2020-07-10T05:36:01Z2020-07-10T05:41:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4004This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/40042020-07-10T05:36:01ZMulti-channel EEG epileptic spike detection by a new method of
tensor decompositionObjective. Epilepsy is one of the most common brain disorders. For epilepsy diagnosis or treatment, the neurologist needs to observe epileptic spikes from electroencephalography (EEG) data. Since multi-channel EEG records can be naturally represented by multi-way tensors, it is of interest to see whether tensor decomposition is able to analyze EEG epileptic spikes. Approach. In this paper, we first proposed the problem of simultaneous multilinear low-rank approximation of tensors (SMLRAT) and proved that SMLRAT can obtain local optimum solutions by using two well-known tensor decomposition algorithms (HOSVD and Tucker-ALS). Second, we presented a new system for automatic epileptic spike detection based on SMLRAT. Main results. We propose to formulate the problem of feature extraction from a set of EEG segments, represented by tensors, as the SMLRAT problem. Efficient EEG features were obtained, based on estimating the ‘eigenspikes’ derived from nonnegative GSMLRAT. We compared the proposed tensor analysis method with other common tensor methods in analyzing EEG signal and compared the proposed feature extraction method with the state-of-the-art methods. Experimental results indicated that our proposed method is able to detect epileptic spikes with high accuracy. Significance. Our method, for the first time, makes a step forward for automatic detection EEG epileptic spikes based on tensor decomposition. The method can provide a practical solution to distinguish epileptic spikes from artifacts in real-life EEG datasets.Trung Thanh Leletrungthanhtbt@gmail.comDao Nguyen Thi Anhdaonta81@gmail.comViet Dung Nguyennvdung@vnu.edu.vnLinh Trung Nguyenlinhtrung@vnu.edu.vnAbed-Meraim Karimkarim.abed-meraim@univ-orleans.fr2020-06-05T02:04:31Z2020-06-05T02:04:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3959This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39592020-06-05T02:04:31ZModelling and calculation of characteristic parameters of the active and buffer layers in organic solar cellMinh Duc TranDinh Lam Nguyenlamnd2005@vnu.edu.vn2020-05-29T08:22:38Z2020-05-29T08:22:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3958This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39582020-05-29T08:22:38ZFabrication and characteristics of Zn1–xSnxO nanorod/ITO composite photocatalytic filmsZn1−xSnxO NRs/ITO composite photocatalytic films were fabricated by the hydrothermal method. A concentration of Sn dopant in Zn1−xSnxO nanorods (NRs) was varied from 0% to 7%. The structural and surface morphology characteristics of Zn1−xSnxO NRs/ITO composite photocatalytic films were investigated by X-Ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. In addition, photocatalytic properties of synthesized materials were evaluated by degradation rates of Rhodamine-B aqueous solutions under UV light irradiation. The SEM results indicated that, with an increasing concentration of Sn dopant in Zn1−xSnxO NRs/ITO, the effective surface areas were declined by an exponential decay function and the reduction was negligible as the Sn doping concentration was higher than 3%. With the similarity in effective surface area, the contribution of Sn in the enhancement of the photocatalytic activity of Zn0.93Sn0.07O NRs/ITO is clearly observed with 41% improvement in comparison to ZnO NRs/ITO.T. Dung NguyenTran Chien DangDuc Thien TrinhAnh Tuan DuongDuc Thang Phampdthang@vnu.edu.vnNang Dinh Nguyendinhnn@vnu.edu.vnDinh Lam Nguyenlamnd2005@vnu.edu.vn2020-05-29T08:21:35Z2020-05-29T08:21:35Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3957This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39572020-05-29T08:21:35ZExperimental and numerical study on photocatalytic activity of the ZnO nanorods/CuO composite filmThe photocatalytic activity of the ZnO NRs/CuO composite film was investigated by using both experimental and numerical methods. The ZnO NRs/CuO composite film exhibits significantly enlarge absorption range to visible-light and suppress the recombination rate of the photogenerated electron-hole pairs, which can be well utilized as a photocatalyst. The ZnO NRs/CuO composite film also presents good stability, and reusability, and durability for photo-decomposition purpose. The optimal ZnO NRs/CuO composite film contains 1μ-thick of CuO film and 10 nm-thick of ZnO NRs film. The donor concentration in ZnO NRs film should be lower than 1016 cm−3. The short circuit current density of the optimal composite film is 25.8 mA/cm2 resulting in the calculated pseudo-order rate constant of 1.85 s−1. The enhancement in degradation efficiency of this composite film is attributed to the inner electric field and large effective surface area of ZnO NRs film.T. Dung NguyenMinh Duc TranVan Thanh HoangDuc Thien TrinhDuc Thang Phampdthang@vnu.edu.vnDinh Lam Nguyenlamnd2005@vnu.edu.vn2020-04-24T04:18:38Z2020-04-24T04:18:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3951This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39512020-04-24T04:18:38ZAn Efficient Hardware Implementation of Residual Data Binarization in HEVC CABAC EncoderHEVC-standardized encoders employ the CABAC (context-based adaptive binary arithmetic coding) to achieve high compression ratios and video quality that supports modern real-time high-quality video services. Binarizer is one of three main blocks in a CABAC architecture, where binary symbols (bins) are generated to feed the binary arithmetic encoder (BAE). The residual video data occupied an average of 75% of the CABAC’s work-load, thus its performance will significantly contribute to the overall performance of whole CABAC design. This paper proposes an efficient hardware implementation of a binarizer for CABAC that focuses on low area cost, low power consumption while still providing enough bins for high-throughput CABAC. On the average, the proposed design can process upto 3.5 residual syntax elements (SEs) per clock cycle at the maximum frequency of 500 MHz with an area cost of 9.45 Kgates (6.41 Kgates for the binarizer core) and power consumption of 0.239 mW (0.184 mW for the binarizer core) with NanGate 45 nm technology. It shows that our proposal achieved a high overhead-efficiency of 1.293 Mbins/Kgate/mW, much better than the other related high performance designs. In addition, our design also achieved a high power-efficiency of 8288 Mbins/mW; this is important factor for handheld applications.Dinh Lam Tranlamtdvdt@gmail.comXuan Tu TranDuy Hieu Buihieubd@vnu.edu.vnCong Kha Phampham@ee.uec.ac.jp2020-03-28T11:49:03Z2020-04-24T04:14:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3942This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39422020-03-28T11:49:03ZA non-blocking non-degrading multiple defects link testing method for 3D-Networks-on-ChipAs one of the most promising technologies to realize 3D Integrated Circuits (3D-ICs), Through-Silicon-Via (TSV) acts as the inter-layer link inside 3D Networks-on-Chip. However, the reliability issues due to the low yield rates and the sensitivity to thermal hotspots and stress issues are preventing TSV-based 3D-ICs from being widely and efficiently used. To ensure the correctness of TSV connections at run-time, detecting multiple (clustering) defects is an important feature. While Error Correction Codes are limited by a certain number of detectable faults, using Built-In-Self-Test (BIST) prevents the system from operating normally during the test time. This paper first presents a Parity Product Code (PPC) with the ability to correct one fault and detect, at least, two faults. Second, we present extended PPC (EPPC) to detect multiple defects within the links of Networks-on-Chip by using two or more additional matrices. Furthermore, we present the distance-aware version of EPPC to detect multiple defects by using only one extra matrix.
The results show that the distance-aware EPPC can detect 100% of clustering defects and multiple random defects within two and three cycles, respectively.
The performance evaluation for Network-on-Chip testing also shows no degradation while providing an extremely short response time (2-3 cycles).Nam Khanh Dangdnk0904@gmail.comMichael MeyerAkram Ben AhmedAbderazek Ben Abdallahbenab@u-aizu.ac.jpXuan Tu Trantutx@vnu.edu.vn2020-03-28T11:47:12Z2020-03-28T11:47:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3940This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39402020-03-28T11:47:12ZScalable design methodology and online algorithm for TSV-cluster defects recovery in highly reliable 3D-NoC systems3D-Network-on-Chips exploit the benefits of Network-on-Chips and 3D-Integrated Circuits allowing them to be considered as one of the most advanced and auspicious communication methodologies. On the other hand, the reliability of 3D-NoCs, due to the vulnerability of Through Silicon Vias, still remains as a major problem. Most of the existing techniques rely on correcting the TSV defects by using redundancies or employing routing algorithms. Nevertheless, they are not suitable for TSV-cluster defects as they can either lead to costly area and power consumption overheads or they may result in non-minimal routing paths; thus, posing serious threats to the system reliability and overall performance. In this work, we present a scalable and low-overhead TSV usage and design method for 3D-NoC systems where the TSVs of a router can be utilized by its neighbors to deal with the cluster open defects. An adaptive online algorithm is also introduced to assist the proposed system to immediately work around the newly detected defects without using redundancies. The experimental results show the proposal ensure less than 2% of the routers being disabled, even with 50% of the TSV clusters defects. The performance evaluations also demonstrate unchanged performances for real applications under 5% of cluster defects.Nam Khanh Dangdnk0904@gmail.comAkram Ben AhmedYuichi OkuyamaAbderazek Ben Abdallahbenab@u-aizu.ac.jp2020-02-11T08:44:30Z2020-02-11T08:44:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3928This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39282020-02-11T08:44:30ZDynamic Basic Activity Sequence Matching Method in Abnormal Driving Pattern Detection Using Smartphone SensorsIn this work, we present a novel method, namely dynamic basic activity sequence matching (DAS), a combination of machine learning methods and flexible threshold based methods for distinguishing normal and abnormal driving patterns. Indeed, DAS relies on the activity detection module (ADM) presented in our previous work to analyze each driving pattern as a sequence of basic activities—stopping (S), going straight (G), turning left (L), and turning right (R). In fact, the threshold value and other parameters like the duration of long and short activities are iteratively induced from the collected dataset. Hence, DAS is flexible and independent of driving contexts such as vehicle modes and road conditions. Experimental results, on the dataset collected from numerous motorcyclists, show the outperformance of our proposed method against dynamic time warping and the two popular machine learning methods—random forest and neural network—in distinguishing the normal and abnormal driving patterns. Moreover, we propose an efficient framework composing of two phases: in the first phase, the normal and abnormal driving patterns are distinguished by relying on DAS. In the second phase, the detected abnormal patterns are further classified into various specific abnormal driving patterns—weaving, sudden braking, etc. This fusion framework again achieves the highest overall accuracy of 97.94%.Thi Hau Nguyennguyenhau@vnu.edu.vnDang Nhac LuDuc Nhan NguyenHa Nam Nguyennamnh@vnu.edu.vn2020-02-11T08:44:18Z2020-02-11T08:44:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3934This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39342020-02-11T08:44:18ZA Service-based Framework for Building and Executing Epidemic Simulation Applications in the CloudThe cloud has emerged as an attractive platform for resource-intensive scientific applications, such as epidemic simulators. However, building and executing such applications in the cloud presents multiple challenges, including exploiting elasticity, handling failures, and simplifying multi-cloud deployment. To address these challenges, this paper proposes a novel service-based framework called DiFFuSE that enables simulation applications with a bag-of-tasks structure to fully exploit cloud platforms. This paper describes how the framework is applied to restructure two legacy applications, simulating the spread of bovine viral diarrhea virus and Mycobacterium avium subspecies paratuberculosis, into elastic cloud-native applications. Experimental results show that the framework enhances application performance and allows exploring different cost-performance trade-offs while supporting automatic failure handling and elastic resource acquisition from multiple clouds.Nikos Parlavantzasnikos.parlavantzas@irisa.frManh Linh Phamlinhmp@vnu.edu.vnChristine MorinChristine.Morin@inria.frSandie Arnouxsandie.arnoux@inra.frGaël Beaunéegael.beaunee@inra.frLuyuan Qiqiluyuan@gmail.comPhilippe Gontierphilippe.gontier@oniris-nantes.frPauline Ezannopauline.ezanno@oniris-nantes.fr2020-01-31T08:01:34Z2020-01-31T08:01:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3923This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39232020-01-31T08:01:34ZCollaborative Smartphone-Based User Positioning in a Multiple-User Context Using Wireless TechnologiesFor the localization of multiple users, Bluetooth data from the smartphone is able to
complement Wi‐Fi‐based methods with additional information, by providing an approximation of
the relative distances between users. In practice, both positions provided by Wi‐Fi data and relative
distance provided by Bluetooth data are subject to a certain degree of noise due to the uncertainty
of radio propagation in complex indoor environments. In this study, we propose and evaluate two
approaches, namely Non‐temporal and Temporal ones, of collaborative positioning to combine
these two cohabiting technologies to improve the tracking performance. In the Non‐temporal
approach, our model establishes an error observation function in a specific interval of the Bluetooth
and Wi‐Fi output. It is then able to reduce the positioning error by looking for ways to minimize the
error function. The Temporal approach employs an extended error model that takes into account
the time component between users’ movements. For performance evaluation, several multi‐user
scenarios in an indoor environment are set up. Results show that for certain scenarios, the proposed
approaches attain over 40% of improvement in terms of average accuracyViet Cuong Tacuongtv@vnu.edu.vnTrung Kien DaoDominique VaufreydazEric Castelli2020-01-08T01:06:40Z2020-01-08T01:07:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3918This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39182020-01-08T01:06:40ZSensing Data Fusion for Enhanced Indoor Air Quality MonitoringMultisensor fusion of air pollutant data in smart buildings remains an important input to address the well-being and comfort perceived by their inhabitants. An integrated sensing system is part of a smart building where real-time indoor air quality data are monitored round the clock using sensors and operating in the Internet-of-Things (IoT) environment. In this work, we propose an air quality management system merging indoor air quality index (IAQI) and humidex into an enhanced indoor air quality index (EIAQI) by using sensor data on a real-time basis. Here, indoor air pollutant levels are measured by a network of waspmote sensors while IAQI and humidex data are fused together using an extended fractional-order Kalman filter (EFKF). According to the obtained EIAQI, overall air quality alerts are provided in a timely fashion for accurate prediction with enhanced performance against measurement noise and nonlinearity. The estimation scheme is implemented by using the fractional-order modeling and control (FOMCON) toolbox. A case study is analysed to prove the effectiveness and validity of the proposed approach.Quang Haquang.ha@uts.edu.auSantanu MetiaSantanu.Metia@uts.edu.auManh Duong Phungduongpm@vnu.edu.vn2020-01-04T05:42:24Z2020-01-04T05:43:37Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3802This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38022020-01-04T05:42:24ZExposure to air pollution and risk of hospitalization for cardiovascular diseases amongst Vietnamese adults: Case-crossover studyThi Trang Nhung NguyenChristian SchindlerQuy Chau NgoThi Hanh PhanTu Hoang LeMinh Dien TranThi Nhat Thanh Nguyenthanhntn@vnu.edu.vnNino Künzli2019-12-30T03:19:49Z2019-12-30T03:19:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3915This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/39152019-12-30T03:19:49ZLight Intensity-dependent Variation in Defect Contributions to Charge Transport and Recombination in a Planar MAPbI3 Perovskite Solar CellWe investigated operation of a planar MAPbI3 solar cell with respect to intensity variation ranging from 0.01 to 1 sun. Measured J-V curves consisted of space-charge-limited currents (SCLC) in a drift-dominant range and diode-like currents in a diffusion-dominant range. The variation of power-law exponent of SCLC showed that charge trapping by defects diminished as intensity increased, and that drift currents became eventually almost ohmic. Diode-like currents were analysed using a modified Shockley-equation model, the validity of which was confirmed by comparing measured and estimated open-circuit voltages. Intensity dependence of ideality factor led us to the conclusion that there were two other types of defects that contributed mostly as recombination centers. At low intensities, monomolecular recombination occurred due to one of these defects in addition to bimolecular recombination to result in the ideality factor of ~1.7. However, at high intensities, another type of defect not only took over monomolecular recombination, but also dominated bimolecular recombination to result in the ideality factor of ~2.0. These ideality-factor values were consistent with those representing the intensity dependence of loss-current ratio estimated by using a constant internal-quantum-efficiency approximation. The presence of multiple types of defects was corroborated by findings from equivalent-circuit analysis of impedance spectra.Shinyoung RyuDuc Cuong Nguyencuongnd@vnu.edu.vnNa Young HaHui Joon Parkhuijoon@ajou.ac.krY. H. AhnJi-Yong Parkjiyong@ajou.ac.krSoonil Leesoonil@ajou.ac.kr2019-12-26T11:04:19Z2019-12-26T11:04:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3899This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38992019-12-26T11:04:19ZAnthropogenic influence on surface water quality of the Nhue and Day sub-river systems in VietnamThi Minh Hanh PhamThe Ba Dangbadt@vnu.edu.vn2019-12-26T11:04:02Z2019-12-26T11:04:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3897This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38972019-12-26T11:04:02ZDevelopment of Water Quality Indices to Identify Pollutants in Vietnam's Surface WaterThi Minh Hanh PhamThe Ba Dangbadt@vnu.edu.vn2019-12-26T11:02:05Z2019-12-26T11:02:22Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3898This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38982019-12-26T11:02:05ZAnalysis of Variation and Relation of Climate, Hydrology and Water Quality in the Lower Mekong RiverThi Minh Hanh PhamThe Ba Dangbadt@vnu.edu.vn2019-12-19T03:16:47Z2019-12-20T04:56:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3847This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38472019-12-19T03:16:47ZHigh-Frequency Interdigitated Array Electrode-Based Capacitive Biosensor for Protein DetectionThis paper reports a study on developing of a protein detection biochip based on interdigitated array electrodes (IDAEs) capacitive immunosensor. The protein after being preconcentrated in a detection region will be selectively captured and detected by the capacitive immunosensor. Using electrical impedance spectroscopy operated at high-frequency in the range of 100 kHz–1 MHz, the capacitance of the gold electrode is determined and the antibody surface modification steps can be also monitored. The experiment results show the capacitance changes in accordance with the adding biochemical layer on gold electrodes for each step of the antibody surface modification. In particular, the total impedance operated at 1 MHz frequency has been seen to change from 2.1 kΩ of bare chip (before antibody surface modification) to 8 kΩ after antibody surface modification process while the serial capacitance is recorded to reduce steadily from 450 pF to 55 pF. Also, the efficiency of protein chip was investigated by implementing the measurement of 10 µM BSA with and without preconcentration process. The measurement results have shown the sensitivity increasing significantly after the protein is preconcentrated in this chip. The results demonstrate high efficiency of protein detection can be achieved by operating high frequency capacitive measurement on IDAEs capacitive immunosensor.Quoc Tuan Vuvqtuan0211@gmail.comNgoc Viet Nguyenvietnn@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vnChun-Ping JenChun-Ping@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vn2019-12-19T03:16:14Z2019-12-20T04:44:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3846This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38462019-12-19T03:16:14ZSimulation and Experimental Study of a Synthetic Jet Valveless PumpA valveless microfluidic pump using a Lead Zirconate Titanate (PZT) diaphragm-actuated synthetic jet is developed and fabricated. For this present design, a valveless pump structure is developed in which the pump chamber is sealed one side and connected to an emitting nozzle at another side. The design is simulated using the multi-physics approach and then successfully investigated with a prototype produced by a low-cost additive fabrication technique. The device’s parameters including the liquid pumping characteristics and the size of PZT membrane are optimized based on its desired performance. The developed device can be applied over a wide range of applications from micro-mixing to fluidic controlling.Van Luan Leetek.luan@gmail.comThanh Tung Buitungbt@vnu.edu.vnNhu Cuong Nguyencuongnn241@gmail.comNgoc An Nguyenngocan@vnu.edu.vnThien Xuan Dinhthien@cfd.ritsumei.ac.jpLam Bao Danglambao@gmail.comCanh Dung TranCanh-Dung.Tran@usq.edu.auDuc Trinh Chutrinhcd@vnu.edu.vnThanh Van Dauv.dau@griffith.edu.au2019-12-19T03:15:51Z2019-12-19T03:15:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3843This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/38432019-12-19T03:15:51ZStudy on Design Optimization of a Capacitive Tilt Angle SensorThis paper presents a design optimization and validation of a two-axis cylindrical capacitive tilt angle sensor. The proposed sensor includes of five electrodes symmetrically arranged surrounding an air–liquid two phases cylindrical tube, forming two pairs of electrodes for roll and pith angle measurement. Cylindrical plastic tube filled partly with dielectric fluid with dielectric constant of 2. The proposed sensor can detect tilt angles in x-axis and y-axis, i.e. roll and pith angles. When the cylindrical plastic tube is rotated, the dielectric fluid covers a portion of the induction electrodes, thereby changing the differential capacitance value of the capacitor corresponding to the tilt angle. By measuring the capacitance change, the tilt angle can be estimated. Performance of the sensor was investigated by Finite element method using Comsol Multiphysics simulation software. Simulation results show the variation in capacitance with respect to the variation of tilt angle. Based on this simulation model, the structure of the electrodes was manipulated for maximizing the sensitivity for roll and pith sensing in an appropriate working range. Experiments were also conducted for validation. The experiment results are well matched with simulated results. The optimized sensor has working range from −70° to +70° with sensitivity of 3 mV/° in the roll angle and from −30° to +30° with sensitivity of 17 mV/° in the pitch angle.Thi Thuy Ha Trantttha@gmail.comDac Hai Nguyenhaind75@gmail.comQuoc Tuan Vutvu.tuan@gmail.comQuoc Thinh Phamthinhpq@tnu.edu.vncNgoc An Nguyenngocan@vnu.edu.vnDuc Trinh Chutrinhcd@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vn2019-12-12T09:35:24Z2019-12-12T09:35:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3631This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36312019-12-12T09:35:24ZStructural transition, electrical and magnetic properties of Cr doped Bi0.9Sm0.1FeO3 multiferroicsThe structural, vibrational, electrical and magnetic properties of Bi0.9Sm0.1Fe1-xCrxO3 (0.02 x 0.1) ceramics have been investigated in the vicinity of the morphotropic phase boundary (MPB) between the rhombohedral and orthorhombic structures. X-ray diffraction (XRD) patterns reveal a gradual formation of the orthorhombic phase and Bi14CrO24 impurity with increasing chromium concentration. The Riet- veld refinement and Raman scattering analysis confirm the structural transformation from the polar R3c to the anti-polar Pnam phases. The Cole-Cole plots show two relaxation regimes which are attributed to gain and grain boundary responses above room temperature. The slim magnetic hysteresis loops are observed in samples with x 1⁄4 0.02e0.08, while a robust loop with the coercivity field of Hc z 1200 Oe is observed for x 1⁄4 0.1 sample where the canted antiferromagnetic phase is significantly contributed to the total magnetization. This result approves that the cycloidal spin structure cannot be suppressed by Cr doping.Thi Anh Hoanhht@vnu.edu.vnPhong P.T.Thoan N.H.Thi Minh Hong Nguyenhongntm@vnu.edu.vnHao N.V.Ha L.T.Bach T.N.Thanh T.D.Xuan C.T.A.Quang N.V.Dang N.V.Tho P.T.2019-12-12T09:35:00Z2019-12-12T09:35:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3517This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35172019-12-12T09:35:00ZShort and long range ordering in La1−xSrxCoO3 cobaltitesWe have carefully studied the relation between the critical and electrical behavior of rhombohedral
La1 -xSrxCoO3 (x = 0.2-0.5) compounds prepared by solid-state reactions. The results obtained from
analyzing M(T, H) data indicate that and all compounds undergo a second-order phase transition
and the ferromagnetic-paramagnetic (FM-PM) transition temperature increase from approximate
182 K for x = 0.2 to 253 K for x = 0.5. Basing on the modified Arrott and Kouvel-Fisher techniques,
scaling hypothesis, and critical isotherm analysis, we have determined the critical exponent values
characteristic of magnetic order of La1 -xSrxCoO3, with = 0.361~0.489, = 1.021~1.346, and =
2.99~4.72. Interestingly, though all compounds are metallic ferromagnets, we have found the phase
segregation in magnetic order as x > 0.3, where magnetic interactions tend to change from long-toshort-range FM order together with the absence of the insulating-like behavior at temperatures
below 100 K. These phenomena are related to the spatial coexistence of multiple electronic and
magnetic phases due to the changes in concentration of cobalt ions, spin-state transitions, and the
existence of poor-hole anti-FM and hole-rich FM regions.Thi Anh Hoanhht@vnu.edu.vnThe Long PhanV. Quang N.L. Cho S.C. Yu S.2019-12-10T15:56:44Z2020-01-08T01:10:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3798This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37982019-12-10T15:56:44ZSpatiotemporal analysis of ground and satellite-based aerosol for air quality assessment in the Southeast Asia regionSatellite observations for regional air quality assessment rely on comprehensive spatial coverage, and daily monitoring with reliable, cloud-free data quality. We investigated spatiotemporal variation and data quality of two global satellite Aerosol Optical Depth (AOD) products derived from MODIS and VIIRS imagery. AOD is considered an essential atmospheric parameter strongly related to ground Particulate Matter (PM) in Southeast Asia (SEA). We analyze seasonal variation, urban/rural area influence, and biomass burning effects on atmospheric pollution. Validation indicated a strong relationship between AERONET ground AOD and both MODIS AOD (R2 = 0.81) and VIIRS AOD (R2 = 0.68). The monthly variation of satellite AOD and AERONET AOD reflects two seasonal trends of air quality separately for mainland countries including Myanmar, Laos, Cambodia, Thailand, Vietnam, and Taiwan, Hong Kong, and for maritime countries consisting of Indonesia, Philippines, Malaysia, Brunei, Singapore, and Timor Leste. The mainland SEA has a pattern of monthly AOD variation in which AODs peak in March/April, decreasing during wet season from May–September, and increasing to the second peak in October. However, in maritime SEA, AOD concentration peaks in October. The three countries with the highest annual satellite AODs are Singapore, Hong Kong, and Vietnam. High urban population proportions in Singapore (40.7%) and Hong Kong (21.6%) were associated with high AOD concentrations as expected. AOD values in SEA urban areas were a factor of 1.4 higher than in rural areas, with respective averages of 0.477 and 0.336. The AOD values varied proportionately to the frequency of biomass burning in which both active fires and AOD peak in March/April and September/October. Peak AOD in September/October in some countries could be related to pollutant transport of Indonesia forest fires. This study analyzed satellite aerosol product quality in relation to AERONET in SEA countries and highlighted framework of air quality assessment over a large, complicated region.Thi Nhat Thanh Nguyenthanhntn@vnu.edu.vnHa V. PhamKristofer LaskoMai T. BuiDominique LafflyAstrid JourdanQuang Hung Buihungbq@vnu.edu.vn2019-12-09T09:27:34Z2019-12-09T09:27:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3758This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37582019-12-09T09:27:34ZInGaP Nano-pattern Structure Realized by Thermally Dewetted Au Nanoparticles and Anisotropic Dry EtchingAbstract: Background: Optical reflection loss can be reduced more than 30% when multilayers ARC are deposited on the optoelectronic devices surface. Besides that, sub-wavelength structures, which have a period sufficiently smaller than the wavelength of light, have been introduced as an antireflection layer to offer a new possibility to suppress the Fresnel reflection. Normally, e-bean and nano-imprint lithography techniques are used to create nano-scale etch mask patterns. Metallic nanoparticles, which can be formed by a thermal dewetting process of metal thin film without any nanolithography techniques, can be utilized as an etch mask for the nano structure fabrications. The nano-patterned structures were fabricated on a silicon nitride passivation layer of a GaInP/GaAs/Ge triple-junction solar cell and showed an enhancement of its performance due to improved optical transmission and current matching.
Objective: Investigate the influences of InGaP nano-pattern structures on the optical characteristics and applied for compound solar cells. Methods: In this report, disordered InGaP nano-pattern structures were formed by thermally dewetted Au nanoparticles and anisotropic dry etching processes. The effects of the InGaP nano-patterned
structure on the optical reflection characteristics were investigated.
Results: The result indicated that the InGaP nano-patterned structure can reduce the optical reflection
in a wide range of wavelengths and, thus, can work as an antireflection layer. The InGaP nanostructure can improve up to 14.8% in the short circuit current density compared to that of the planar cell.
Conclusion: The InGaP nano structures have been successfully fabricated by thermal dewetted Au nanoparticles and anisotropic dry etching methods. The fabricated Au nanoparticles pattern was found to be the best when annealing temperature is 400°C for 30 minutes with the 5nm thick of Au film. By controlling dry etching time, the height of InGaP nanostructures can be varied from 95 nm to 150 nm. With the increasing of the height, the optical reflectance can be down to 22%. The InGaP nanostructure with the height of 150 nm was also introduced to the window layer of a single junction GaAs soar cell. The result indicated that the InGaP nanostructure only affects on the short circuit current density.Dinh Lam Nguyenlamnd2005@vnu.edu.vn2019-12-09T09:15:34Z2019-12-09T09:15:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3757This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37572019-12-09T09:15:34ZA Novel Framework to Classify Malware in MIPS Architecture-based IoT DevicesMalware on devices connected to the Internet via the Internet of Things (IoT) ) is evolving and is a core component of the fourth industrial revolution. IoT devices use the MIPS architecture with a large proportion running on embedded Linux operating systems, but the automatic analysis of IoT malware has not resolved. We proposed a framework to classify malware in IoT devices by using MIPS-based system behavior (system call - syscall) got from our F-Sandbox passive process and machine learning techniques. The F-Sandbox is a new type for IoT sandbox, automatically created from the real firmware of the specialized IoT devices, inheriting the specialized environment in the real firmware, therefore creating a diverse environment for sandboxing as an important characteristic of IoT sandbox. This framework classifies five families of IoT malware with F1-Weight = 97.44%.Nghi Phu Trantnphvan@gmail.comDang Kien Hoang15021363@vnu.edu.vnQuoc Dung Ngoquocdung.ngo@gmail.comDai Tho Nguyennguyendaitho@vnu.edu.vnNgoc Binh Nguyennnbinh@vnu.edu.vn2019-12-09T07:07:22Z2019-12-09T07:07:22Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3738This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37382019-12-09T07:07:22ZDielectrophoresis can control the density of CNT membranes as confirmed by experiment and dissipative particle simulationIn forests and membranes, Carbon nano tubes (CNT) are not individual, instead they tend to be agglomerated into bundles because of the strong van der Waals interaction. CNTs usually form into bundles containing up to hundreds or thousands of parallel CNTs named as fibres which create networks within a CNT membrane. Recently, CNT based macrostructures (yarn and membrane) have increasingly been used in various applications in electronics, medical and bioengineering. Meanwhile the volume density of CNTs impacts on mechanical and physical properties of macrostructures, the controlling of the density of membranes is very complex. Thus, in this paper, an electric processing to dilate CNT membrane is sufficiently studied and investigated by both the experiment and particle based numerical simulation. Several initially potential applications of the method are also represented not only to control the density of CNTs but also to improve the CNTs’ alignment in macro-structures.Canh-Dung TranCanh-Dung.Tran@usq.edu.auCao Khoa Lecao-khoa.le@usq.edu.auThanh Tung Buitungbt@vnu.edu.vnThanh Van Dauv.dau@griffith.edu.au2019-12-09T07:06:35Z2019-12-09T07:06:35Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3736This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37362019-12-09T07:06:35ZA Circulatory Ionic Wind for Inertial Sensing ApplicationA novel gyroscope using circulatory electro-hydrodynamics flow in a confined space is presented for the first time. The configuration of the new gyroscope includes three point-ring corona discharge actuators which generate ion flows in three separated sub-channels. The three ion flows then merge together when going through a nozzle of the main chamber entrance and create a jet flow. In the new configuration, the residual charge of ion wind flow is removed by a master-ring electrode located at one end of the main chamber. Under the effect of the angular speed of gyroscope, the jet flow is deflected and this deflection is sensed using hotwires. Results, which are consistently acquired by both numerical simulation and experiment on our prototypes, demonstrate the repeatability and stability of the new approach. Since the ion wind can be generated by a minimum power, the present configuration-based device does not require any vibrating component. Thus, the device is robust, cost and energy-effective.Van Ngoc Tranvanngoc@gmail.comThanh Tung Buitungbt@vnu.edu.vnThien Xuan Dinhthien@cfd.ritsumei.ac.jpCanh-Dung TranCanh-Dung.Tran@usq.edu.auThanh Hoa Phanp.hoa@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vnVan Thanh Dauv.dau@griffith.edu.au2019-12-09T07:06:17Z2019-12-09T07:06:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3735This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37352019-12-09T07:06:17ZDevelopment of a Passive Capacitively Coupled Contactless Conductivity Detection (PC4D) Sensor System for Fluidic Channel Analysis Toward Point-of-Care ApplicationsA sensor system based on a modified capacitively coupled contactless conductivity detection sensor is proposed and developed. The proposed system provides a passive and wireless readout technique, through which the conductivity of fluidic flow can be analyzed and foreign objects occurring in the fluidic flow can be detected. The proposed sensor system takes advantage of the series resonance principle and detects shifts in the resonance frequency and reflection coefficient to estimate the conductivity of the fluidic flow. In this study, the working principle of the device is proposed and analyzed using a multiphysics simulation, and its performance is validated experimentally. The sensing performance is confirmed by measuring the conductivity of the fluidic media and the detection of foreign objects, such as air bubbles or water droplets, occurring in the flow. The influence of the distance between the inductors on the resonance frequency for different solution conductivities is also investigated and reported. The proposed sensor system shows its potential for use in various applications in biomedicine and chemistry, particularly in point-of-care applications, where the sensing chip can be easily set up for measurement and disposed of after use.Loc Quang Dolocdq@hus.edu.vnThanh Tung Buitungbt@vnu.edu.vnBao Anh Hoangbaoanh0408@gmail.comThanh Pham Vanphamvanthanh@hus.edu.vnChun-Ping JenChun-Ping@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vn2019-12-09T07:03:42Z2019-12-09T07:03:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3212This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32122019-12-09T07:03:42ZA Robust Two-axis Tilt Angle Sensor Based on Air/Liquid Two-phase Dielectric Capacitive Sensing StructureThi Thuy Ha Trantttha@gmail.comDinh Tiep Dangdangtiep.2011@gmail.comQuoc Tuan Vutvu.tuan@gmail.comQuoc Thinh Phamthinhpq@tnu.edu.vncMasahiro Aoyagim.aoyagi@aist.go.jpNgoc My Buibuingocmy_vn@mail.ruThanh Van Dauv.dau@griffith.edu.auThanh Tung Buitungbt@vnu.edu.vn2019-12-09T03:35:08Z2019-12-09T03:35:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3593This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35932019-12-09T03:35:08ZFull-Duplex Enabled Mobile Edge Caching: From Distributed to Cooperative CachingMobile edge caching (MEC) has received much attention as a promising technique to overcome the stringent latency and data hungry requirements in the future generation wireless networks. Meanwhile, full-duplex (FD) transmission can
potentially double the spectral efficiency by allowing a node to receive and transmit simultaneously. In this paper, we investigate the delivery time performance of full-duplex enabled MEC (FDMEC) systems, in which the users are served by distributed edge nodes (ENs), which operate in FD mode and are equipped with a limited storage memory. Firstly, we analyse the FD-MEC with different levels of cooperation among the ENs and take into account the realistic model of self-interference cancellation. Secondly, we propose a framework to minimize the system delivery time of FD-MEC under both linear and optimal precoding designs. Thirdly, to deal with the non-convexity of the formulated problems, two iterative optimization algorithms are proposed based on the inner approximation method, whose convergence is analytically guaranteed. Finally, the effectiveness of the proposed designs are demonstrated via extensive numerical results. It is shown that the cooperative scheme mitigates inter-user and self interference significantly better than the distributed scheme at the expense of inter-EN cooperation. In addition, we show that minimum mean square error (MMSE)-based precoding design achieves the best performance-complexity trade-off, compared with the zero-forcing and optimal designs.Xuan Thang Vuthang.vu85@gmail.comSymeon ChatzinotasChatzinotas@gmail.comBj¨orn Otterstenbjorn.ottersten@uni.luAnh Vu Trinhvuta@vnu.edu.vn2019-12-09T03:31:02Z2019-12-09T03:31:02Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3307This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33072019-12-09T03:31:02ZDielectrophoresis Microfluidic Enrichment Platform with Built-In Capacitive Sensor for Rare Tumor Cell DetectionThe manipulation and detection of rare cells are important for many applications in early disease diagnosis and medicine. This study presents a dielectrophoresis (DEP) microfluidic enrichment platform combined with a built-in capacitive sensor for circulating tumor cell detection. The microchip is composed of a lollipop-shaped gold microelectrode structure under a polydimethylsiloxane chamber. A prototype of the device was fabricated using standard micromachining technology. With the proposed device, target cells (in this study, A549 non-small human lung carcinoma and S-180 sarcoma cell lines) are firstly guided toward the center of the working chamber via DEP forces. Then, the target cells are captured by an electrode immobilized by anti-EGFR, which has high affinity toward the target cells. After the cell concentration process, the differential capacitance is read to detect the presence of the target cells. Numerical simulations and measurement experiments were performed to demonstrate the high sensitivity of differential capacitive sensing. The obtained results show high sensitivity for S-180 cell detection (3 mV/cell). The proposed platform is suitable for rapid cancer diagnoses and other metabolic disease applications.Loc Quang Dolocdq@hus.edu.vnThi Thuy Ha Trantttha@gmail.comThanh Tung Buitungbt@vnu.edu.vnVan Thanh Daudauv@sc.sumitomo-chem.co.jpNgoc Viet Nguyenvietnn.mt@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vnChun-Ping JenChun-Ping@gmail.com2019-12-09T03:30:20Z2019-12-09T03:30:20Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3306This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33062019-12-09T03:30:20ZEstimating the effect of asymmetric electrodes in bipolar discharge ion wind generatorWe present the study of a simple and efficient air-flow generator under the effect of ion winds which are created by corona discharge. Based on our recent research of ion wind with bipolar corona using parallel pins, this work reports an investigation and evaluation of the corona system in asymmetrical configurations, where the two electrodes have different tip shapes. The system of new configuration is investigated both experimentally and numerically. The numerical and experimental results are the base to establish a regime of stable operation by the measured I-V characteristics. The optimized set-up can generate an air flow up to 2.24 m/s at the atmospheric pressure. With the asymmetrical configuration of different pin tip shapes, the system can be used in many mixing applications such as mixing solvent and die where the generated vortices are also presented.Van Thanh Daudauv@sc.sumitomo-chem.co.jpCanh-Dung TranCanh-Dung.Tran@usq.edu.auThien Xuan Dinhthien@cfd.ritsumei.ac.jpLam Bao Danglambao@gmail.comTibor Terebessytibor.terebessy@clearviewtraffic.comThanh Tung Buitungbt@vnu.edu.vn2019-12-09T03:29:45Z2019-12-09T03:29:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3305This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33052019-12-09T03:29:45ZParticle precipitation by bipolar corona discharge ion windsThe paper reports the development of a particle precipitation based aerosol sampler using bipolar corona discharge ion winds with collected particles of minimized net charge. For the new approach, neutralized particles move towards a sampler under the effect of electric field and dual ion winds. Since there is no electrode or sampling chip installed inside the air-flow channel, impediments to airborne particle flow or ion winds are removed along the flow direction. In addition, the isolation of ion winds, which generate circuit, allows using various materials for the sampling chip including non-conductors and also protecting collected particles from any discharge ignition on the chip. The device mechanism is numerically simulated in OpenFOAM to study the electrofluidodynamic interaction of charged particles and bipolar ion winds. The efficiency of the new approach has been investigated by experiment with a maximum efficiency of 94%. The effects of flow rate, discharge voltage and electrode distances on the method are also evaluated.Van Thanh Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpCanh-Dung TranCanh-Dung.Tran@usq.edu.auTibor Terebessytibor.terebessy@clearviewtraffic.comDuc Trinh Chutrinhcd@vnu.edu.vnThanh Tung Buitungbt@vnu.edu.vn2019-12-04T07:37:40Z2020-12-25T11:04:55Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3704This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/37042019-12-04T07:37:40ZSimulation study of two-dimensional viscoelastic imaging of soft tissues using the extended Kalman filter for tumor detectionThe mechanical properties of tissues in terms of elasticity and viscosity provide useful information for tumor detection. Recently, shear wave imaging has been developed to quantify tissue elasticity by estimating the parameters of the complex shear modulus (CSM). The current challenges of CSM estimation are estimation accuracy, computational complexity, and dealing with heterogeneous media. In this paper, we propose a two-dimensional CSM imaging method based on the extended Kalman filter (EKF). Firstly, particle velocities at spatial locations are acquired by using a Doppler ultrasound system. Then, the EKF is used to estimate the CSM at each spatial point, and hence for an area of interest using ray scanning. Finally, the CSM images are also enhanced using several image processing algorithms. Simulated experiment and performance studies are carried out to confirm the quality of the proposed method.Quang Ha Luongluonghai@mta.edu.vnDuc Tan Trantan.tranduc@phenikaa-uni.edu.vnLinh Trung Nguyenlinhtrung@vnu.edu.vnHuu Tue HuynhNgoc Minh Do2019-11-29T03:37:53Z2019-11-29T03:37:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3671This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36712019-11-29T03:37:53ZA hybrid genetic algorithm for the traveling salesman problem with droneThis paper addresses the traveling salesman problem with drone (TSP-D), in which a truck and drone are used to deliver parcels to customers. The objective of this problem is to either minimize the total operational cost (min-cost TSP-D) or minimize the completion time for the truck and drone (min-time TSP-D). This problem has gained a lot of attention in the last few years reflecting the recent trends in a new delivery method among logistics companies. To solve the TSP-D, we propose a hybrid genetic search with dynamic population management and adaptive diversity control based on a split algorithm, problem-tailored crossover and local search operators, a new restore method to advance the convergence and an adaptive penalization mechanism to dynamically balance the search between feasible/infeasible solutions. The computational results show that the proposed algorithm outperforms two existing methods in terms of solution quality and improves many best known solutions found in the literature. Moreover, various analyses on the impacts of crossover choice and heuristic components have been conducted to investigate their sensitivity to the performance of our method.Quang Minh HaYves DevilleQuang Dung PhamMinh Hoang Haminhhoang.ha@vnu.edu.vn2019-11-29T03:37:09Z2019-11-29T03:37:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3670This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36702019-11-29T03:37:09ZA distance-based approach for merging probabilistic knowledge basesIn the stages of development of probabilistic expert systems, knowledge merging is a major concern. To deal with knowledge merging problems, several approaches have been put forward. However, in the proposed models, each original probabilistic knowledge base (PKB) is represented by a set of probabilistic functions fulfilling such knowledge base. The drawbacks of the solutions are that the output of model is also a set of probabilistic functions satisfying the resulting PKB and there is no algorithm for implementing the merging process of PKBs in which each of them consists of probabilistic constraints. In this paper, distance-based approach is utilized to propose a new method of merging PKBs to ensure that both the input and output of methods are represented by sets of probabilistic constraints. To this aim, the relationship between the probability rules and the probabilistic constraints, and the several transformation methods for the representation of the original PKB are presented, a set of merging operators (MOs) is proposed, and several desirable logical properties are investigated and discussed. Several algorithms for merging PKBs are presented and the computational complexities of these algorithms are also analyzed and evaluated.Van Tham Nguyenthamnv.nute@gmail.comNgoc Thanh Nguyenngoc-thanh.nguyen@pwr.wroc.plTrong Hieu Tranhieutt@vnu.edu.vn2019-11-28T09:01:47Z2019-11-29T05:48:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3587This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35872019-11-28T09:01:47ZHigh thermoelectric power factor in SnSe2 thin film grown on Al2O3 substrateThermoelectric figure of merit (ZT) is highly sensitive to the carrier concentration and maximizes within the narrow region of 1019–1020 cm−3. The SnSe2 single crystal is predicted to have a high ZT value with carrier concentration in the range of 1019–1020 cm−3. Here, we grew SnSe2 thin film on Al2O3 substrate by pulsed laser deposition (PLD) with post-annealing at 400 °C in Argon for 60 min. The annealed thin film shows a high thermoelectric power factor up to 8 μW cm−1 K−2 at 220 K with a carrier concentration of 5.2 × 1019 cm−3. A hexagonal crystal structure of the SnSe2 thin film was confirmed by X-ray diffraction and Raman spectra measurements. The thin film showed an n-type semiconductor behavior. Maximum electrical conductivity and Seebeck coefficient were obtained at 220 K with the values of 210 Scm−1 and −192 μVK−1, respectively.Anh Tuan DuongDinh Lam Nguyenlamnd2005@vnu.edu.vnManh Nghia NguyenThi Minh Hai NguenAnh Duc NguyenAnh Tuan PhamParman UllahTahir ZeeshanYong Soo KimQuang Trung DoTu NguyenVan Hao BuiDas RajaThanh Huy PhamSunglae Cho2019-11-28T01:49:17Z2019-11-28T01:49:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3636This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36362019-11-28T01:49:17ZNonlinear buckling of eccentrically stiffened nanocomposite cylindrical panels in thermal environmentsBased on Reddy's third order shear deformation shell theory and Galerkin method, this paper introduces analytical solutions to study nonlinear buckling behaviors of imperfect carbon nanotube reinforced composite cylindrical panels on elastic foundations in thermal environments. The panels are reinforced by single-walled carbon nanotubes and the eccentrically longitudinal and transversal stiffeners. The effects of geometrical parameters, eccentrically stiffeners, elastic foundations, initial imperfection, temperature increment and nanotube volume fraction on the mechanical behaviors of the nanocomposite cylindrical panels are also examined in numerical results. Some comparisons with results of other authors show the accuracy of the present theory and approach.Dinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimQuoc Quan TranTuan Manh DuongHuy Cuong Nguyen2019-11-28T01:46:38Z2019-11-28T01:46:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3644This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36442019-11-28T01:46:38ZThe effect of cracks on the stability of the functionally graded plates with variable-thickness using HSDT and phase-field theoryIn this paper, the stability in a rectangular functionally grade material (FGM) plate with central crack is studied. The plate thickness is changed exponentially following the length of the plate. The properties of the FGM plate are assumed to vary along the thickness direction according to a simple power law distribution. Based on the phase-field theory, the new third order shear deformation plate theory (TSDT) and the finite element method (FEM), the stability of cracked FGM plate is determined. The obtained numerical results are compared with the published articles to ensure credibility. The work also considered effects of changing of the plate thickness ratio, length, crack angle and volume fraction exponent of the functionally graded material on the stability of the plate. Lastly, some visual images of the mechanical instability forms of cracked FGM plates will be introduced.Minh Phuc PhamDinh Duc Nguyenducnd@vnu.edu.vn2019-11-28T01:46:19Z2019-11-29T05:52:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3645This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36452019-11-28T01:46:19ZNonlinear Vibration of Carbon Nanotube Reinforced Composite Truncated Conical Shells in Thermal EnvironmentThis paper is concerned with the nonlinear vibration and dynamic response of carbon nanotube (CNT) reinforced composite truncated conical shells resting on elastic foundations in a thermal environment. The material properties of shells are assumed to be temperature-dependent and graded in the thickness direction according to various linear functions. The nonlinear equations of motion are expressed in the form of two-component deflection function and solved by the analytical method. Detailed studies for the influences of various types of distribution and volume fractions of CNTs, geometrical parameters, Winkler and Pasternak elastic foundations on the dynamic response and nonlinear vibration of CNT polymer composite truncated conical shells are examined and the comparison study is carried out to verify the accuracy and efficiency of the proposed method.Dinh Nguyen Phamnguyenpd@vnu.edu.vnDinh Quang Vuquangvd2510@gmail.comThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2019-11-28T01:45:58Z2019-11-28T01:45:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3646This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36462019-11-28T01:45:58ZAn analytical solution for nonlinear dynamic response and vibration of FG‐CNT reinforced nanocomposite elliptical cylindrical shells resting on elastic foundationsThe present study deals with the nonlinear dynamic response and vibration of functionally graded carbon nanotubes (FG‐CNT) reinforced composite elliptical cylindrical shells resting on elastic foundations in thermal environments using an analytical solution. The nanocomposite elliptical cylindrical shells are reinforced by single‐walled carbon nanotubes. Based on the classical shell theory with the geometrical nonlinearity in von Kármán and the nonlinear dynamic response and vibration results are obtained by using the Airy stress function, Galerkin method, and Runge‐Kutta method. In numerical results, the effect of geometrical parameters, initial geometric imperfection, Winkler and Pasternak elastic foundations and volume fractions and types of distribution of CNTs on the nonlinear dynamic response and vibration of FG‐CNT reinforced composite elliptical cylindrical shells are investigated.Dinh Dat NgoDinh Khoa NguyenDinh Nguyen Phamnguyenpd@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2019-11-28T01:45:21Z2019-11-28T01:45:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3634This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36342019-11-28T01:45:21ZNonlinear post-buckling of CNTs reinforced sandwich-structured composite annular spherical shellsTuan Manh Duongiam.mr.manh@gmail.comThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vnDinh Nguyen Phamnguyenpd@vnu.edu.vn2019-11-28T01:43:35Z2019-11-28T01:43:35Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3649This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36492019-11-28T01:43:35ZA finite element–based assessment of free vibration behaviour of circular and annular magneto-electro-elastic plates using higher order shear deformation theoryIn this article, the free vibration behaviour of circular and annular magneto-electro-elastic plates has been investigated under the framework of higher order shear deformation theory. The three-dimensional finite element formulation has been derived with the aid of Hamilton’s principle by taking into account the coupling between elastic, electric and magnetic properties. The equations of motion are solved using condensation technique. Furthermore, the credibility of proposed finite element formulation has been validated using COMSOL software and also by comparing the results with previously published articles. Special attention has also been paid to assess the influence of parameters such as coupling effect, stacking sequences and inner-to-outer diameter ratio. The numerical results reveal that the coupled natural frequencies of the annular magneto-electro-elastic plates vary significantly with the circular hole dimensions incorporated. The circular and annular plates are considered as one of the prominent structural components in various engineering and industrial application. Therefore, the proposed finite element formulation and the results presented in this article can serve as benchmark solutions for the design and analysis of smart sensors and actuators.Vinyas M.Sundar S.Thoi Trung NguyenDinh Duc Nguyenducnd@vnu.edu.vn2019-11-28T01:42:41Z2019-11-28T01:43:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3648This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36482019-11-28T01:42:41ZNonlinear dynamic response and vibration of shear deformable piezoelectric functionally graded truncated conical panel in thermal environmentsThe novelty of this study is using the analytical approach to investigate the nonlinear dynamic response and vibration of shear deformable functionally graded truncated conical panel with piezoelectric actuators, resting on Pasternak type elastic foundations in thermal environments. Material properties are graded in the thickness direction according to a simple power law distribution in terms of the fractions of constituents. The governing equations are derived based on the first order shear deformation shell theory with a von Karman – Donnell type of kinematic nonlinearity in which the Hamilton's principle is used to derive the equations of motion of piezoelectric functionally graded truncated conical panel. The those equations are solved by the Galerkin method and Runge – Kutta method to determine the nonlinear deflection amplitude – time curves and natural frequency of the functionally graded panel. In numerical results, the effects of applied actuator voltage, temperature increment, dimensional parameters, semi – vertex angle, material properties and elastic foundations on the nonlinear dynamic response and vibration of the piezoelectric functionally graded truncated conical panel are discussed in details. The approach are verified with the known results in the literature.Quang Chan DoQuoc Quan Tranquantq1505@gmail.comSeung-Eock KimDinh Duc Nguyenducnd@vnu.edu.vn2019-11-27T07:06:06Z2019-11-27T07:06:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3406This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34062019-11-27T07:06:06ZEnhanced magneto-transport and thermoelectric properties of MnP nanorod thin flms grown on Si (1 0 0)The MnP thin flms were grown on Si (1 0 0) substrates at 300 and 400 °C using molecular beam epitaxy (MBE). The flms crystallize in an orthorhombic structure. FESEM images indicated that both flms are composed of vertically aligned MnP nanorods. However, the density of the nanorods in the flm grown at 400 °C is higher
than that grown at 300 °C, leading to a considerable decrease of resistivity in this sample. Both flms showed a ferromagnetic behavior, but the Curie temperature
increased from 275 K for the flm grown at 300 °C to 325 K for the flm grown at 400 °C. Anomalous Hall eﬀect (AHE) and negative magneto-resistance (MR) were
observed in the flms. While both flms exhibited a metallic behavior, a higher thermoelectric power factor (PF) was achieved for the flm grown at 400 °CAnh Tuan DuongThi Minh Hai NguyenDinh Lam Nguyenlamnd2005@vnu.edu.vnDas RajaHuu Tuan NguyenBach Thang PhanSunglae Cho2019-11-26T07:43:11Z2019-11-26T07:43:11Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3586This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35862019-11-26T07:43:11ZIoT-enabled dependable control for solar energy harvesting in smart buildingsEfficiency and reliability have been essential requirements for energy generation in smart cities. This paper presents the design and development of dependable control schemes for microgrid management, which can be seamlessly integrated into the management system of smart buildings. Here, to recover from failures in the solar energy system of a building microgrid, dependable controllers are proposed along with its hardware implementation. The system features the use of Internet of Things (IoT) as its core to coordinate the operation of multiple subsystems in a scalable manner. The control scheme uses a number of controllers cooperatively functioning via a token-based mechanism within the network to provide redundancy and thus reliability in solar tracking. The system exploits data from not only local in-situ sensors but also online sources via IoT networks for fault-tolerant control. Experiments conducted in a twelve-storey building indicate the harvested solar energy meeting the design requirement while the control reliability is maintained in face of communication or hardware disruptions. The results confirmed the validity of the proposed approach and its applicability to energy management in smart buildings.Manh Duong Phungduongpm@vnu.edu.vnHa Quangquang.ha@uts.edu.au2019-11-08T03:20:07Z2019-11-08T03:20:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3585This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35852019-11-08T03:20:07ZA novel reconfigurable router for QoS guarantees in real-time NoC-based MPSoCsThis paper presents a proposal and implementation of a multi-mode full-reconfigurable router for Network-on-Chip (NoC). First, the router supports a hybrid packet-switching architecture that is dynamically reconfigurable to exchange between wormhole and virtual cut-through switching schemes at run-time. Therefore, it reaches a higher average performance than wormhole switching, while decreasing the implementation cost in comparison with the virtual cut-through switching. Second, the router is equipped a Quality-of-Services (QoS)-driven arbiter. Therefore, the proposed solution not only guarantees the guaranteed-throughput service without reserving resources but also enhances the average performance for the best-effort service by using network resources efficiently based on the priority inheritance arbitration mechanism. Third, the router is enhanced with the dynamically deadline-aware rerouting mechanism. In contention situation, the router can configure the routing computation unit to reroute the packet to another path so as to reduce the waiting interval of the blocked packets. The router was designed at the Register Transfer Level and modeled using VHDL language and then synthesized with Xilinx Virtex-7 FPGA technology. The experimental results prove that the proposed router is reliable and can improve the average performance of different QoS loads significantly compared with the generic routers while the area and power overhead are acceptable.Kiem Hung Nguyenkiemhung@vnu.edu.vnXuan Tu Trantutx@vnu.edu.vn2019-11-01T16:40:19Z2019-11-01T16:40:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3580This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35802019-11-01T16:40:19ZUSLTG: Test Case Automatic Generation by Transforming Use CasesThis paper proposes a transformation-based method to automatically generate functional test cases from use cases named USLTG (USL-based Test Generation). We first focus on developing a modeling language named Test Case Specification Language (TCSL) in order to express test cases. Test cases in TCSL can contain detailed information including test steps, test objects within steps, actions of test objects, and test data. Such information is often ignored in currently available test case specifications. We then aim to generate test cases in a TCSL model by a transformation from use cases that are represented by a Use case Specification Language (USL). The USLTG transformation includes three main steps, in generating: (1) scenarios, (2) test data, and (3) a TCSL model. Within our transformation, the OCL solver is employed in order to build system snapshots as the part of test cases and to identify other test data. We applied our method to two case studies and evaluated our method by comparing with other recent works.Minh Hue ChuDuc Hanh Danghanhdd@vnu.edu.vnNgoc Binh Nguyennnbinh@vnu.edu.vnAnh Hoang Truonghoangta@vnu.edu.vn2019-10-14T03:02:09Z2019-10-14T03:02:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3571This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35712019-10-14T03:02:09ZMatched Field Processing For Source Localization Based on
An Approach of Riemannian GeometryThe matched field processing (MFP) for source localization has long history, and remains a viable area of research as well as application of SONAR. Some methods such as empirical mode decomposition, adaptive MFP, compressive MFP and MFP using Riemannian geometry have been introduced recently in order to increase the performance of conventional MFP. In case of ocean environment variability, there are many modeled field replicas thus the number of degree of freedom is increased, consequently the true source selection becomes more complexity. In this paper, we presents a MFP using an approach of Riemannian geometry in which Riemannian distance is obtained in close-form from a new isometric mapping and 20 modeled field replicas that are received in simulation from variable sound speeds. On the basis of the proposed MFP and simulation results, the source localization could be found in a more realistic manner.Quyen Tran Caoquyentc@vnu.edu.vn2019-08-21T03:37:07Z2019-08-21T03:37:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3543This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35432019-08-21T03:37:07ZEffect of Crystallization Temperature on Energy-Storage Density and Efficiency of Lead-Free Bi0.5(Na0.8K0.2)0.5TiO3 Thin Films Prepared by Sol-Gel MethodDang Co Nguyennguyendangco.95@gmail.comViet Cuong Lecuonglv@vnu.edu.vnDinh Tu Buibuidinhtu@vnu.edu.vnDuc Thang Phampdthang@vnu.edu.vnXuan Dien LuongNgoc Hung VuDuc Quan Ngo2019-08-21T03:35:43Z2019-08-21T03:35:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3552This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35522019-08-21T03:35:43ZSummit Navigator: A Novel Approach for Local Maxima ExtractionThis paper presents a novel method, called the Summit Navigator, to effectively extract local maxima of an image histogram for multi-object segmentation of images. After smoothing with a moving average filter, the obtained histogram is analyzed, based on the data density and distribution to find the best observing location. An observability index for each initial peak is proposed to evaluate if it can be considered as dominant by using the calculated observing location. Recursive algorithms are then developed for peak searching and merging to remove any false detection of peaks that are located on one side of each mode. Experimental results demonstrated the advantages of the proposed approach in terms of accuracy and consistency in different reputable datasets.Tran Hiep Dinhtranhiep.dinh@vnu.edu.vnManh Duong Phungduongpm@vnu.edu.vnQuang Haquang.ha@uts.edu.au2019-08-21T03:35:11Z2019-08-21T03:35:11Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3551This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35512019-08-21T03:35:11ZBisimulation and bisimilarity for fuzzy description logics under the Gödel semanticsDescription logics (DLs) are a suitable formalism for representing knowledge about domains in which objects are described not only by attributes but also by binary relations between objects. Fuzzy extensions of DLs can be used for such domains when data and knowledge about them are vague and imprecise. One of the possible ways to specify classes of objects in such domains is to use concepts in fuzzy DLs. As DLs are variants of modal logics, indiscernibility in DLs is characterized by bisimilarity. The bisimilarity relation of an interpretation is the largest auto-bisimulation of that interpretation. In DLs and their fuzzy extensions, such equivalence relations can be used for concept learning. In this paper, we define and study fuzzy bisimulation and bisimilarity for fuzzy DLs under the Gödel semantics, as well as crisp bisimulation and strong bisimilarity for such logics extended with involutive negation. The considered logics are fuzzy extensions of the DL (a variant of PDL) with additional features among inverse roles, nominals, (qualified or unqualified) number restrictions, the universal role, local reflexivity of a role and involutive negation. We formulate and prove results on invariance of concepts under fuzzy (resp. crisp) bisimulation, conditional invariance of fuzzy TBoxes/ABoxes under bisimilarity (resp. strong bisimilarity), and the Hennessy-Milner property of fuzzy (resp. crisp) bisimulation for fuzzy DLs without (resp. with) involutive negation under the Gödel semantics. Apart from these fundamental results, we also provide results on using fuzzy bisimulation to separate the expressive powers of fuzzy DLs, as well as results on using strong bisimilarity to minimize fuzzy interpretations.Linh Anh NguyenQuang Thuy Hathuyhq@vnu.edu.vnNgoc Thanh NguyenThi Hong Khanh NguyenThanh Luong Tran2019-08-08T02:38:21Z2019-08-08T02:38:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3546This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35462019-08-08T02:38:21ZMultiple UAV Coordination based on the Internet of Things for Real-time Surface InspectionThis paper presents a real-time control system for surface inspection using multiple unmanned aerial vehicles (UAVs). The UAVs are coordinated in a specific formation to collect data of the inspecting objects. The communication platform for data transmission is based on the Internet of Things (IoT). In the proposed architecture, the UAV formation is established via using the angle-encoded particle swarm optimisation to generate an inspecting path and redistribute it to each UAV where communication links are embedded with an IoT board for network and data processing capabilities. Data collected are transmitted in real time through the network to remote computational units. To detect potential damage or defects, an online image processing technique is proposed and implemented based on histograms. Extensive simulation, experiments and comparisons have been conducted to verify the validity and performance of the proposed system.Van Truong HoangManh Duong Phungduongpm@vnu.edu.vnTran Hiep Dinhtranhiep.dinh@vnu.edu.vnQuang Ha2019-07-05T03:10:53Z2019-07-05T03:10:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3538This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35382019-07-05T03:10:53ZEffect of Crystallization Temperature on Energy-Storage Density and Efficiency of Lead-Free Bi0.5(Na0.8K0.2)0.5TiO3 Thin Films Prepared by Sol-Gel MethodLead-free Bi0.5(Na0.80K0.20)0.5TiO3 (BNKT) ferroelectric films were synthesized on Pt/Ti/SiO2/Si substrates via the chemical solution deposition. The influence of the crystallization temperature on the microstructures, the ferroelectric and energy-storage properties of the films was investigated in detail. The results showed that the BNKT films have reached the well crystallized state in the single-phase perovskite structure at 700oC. Ferroelectric and energystorage properties of the films were significantly enhanced by increasing the crystallization
temperature. The remnant polarization (2Pr) and maximum polarization (2Pm) reached the highest values of 18.4 µC/cm2 and 61.2 µC/cm2, respectively, under the electric field of 300 kV/cm. Thanks to the strong enhancement in 2Pm and the large Pmax - Pr value, the highest energy-storage density (Jreco) and efficiency of 2.3 J/cm3 and 58.2%, respectively, were obtained. These results indicate that the BNKT films have application potentials in advanced
capacitors.Dinh Tu Buibuidinhtu@vnu.edu.vnDang Co Nguyennguyendangco.95@gmail.comViet Cuong Lecuonglv@vnu.edu.vnDuc Thang Phampdthang@vnu.edu.vn2019-07-05T03:06:17Z2019-07-05T03:06:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3493This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34932019-07-05T03:06:17ZNumerical analysis of the vibration response of skew magneto-electro-elastic plates based on the higher-order shear deformation theoryThis work addresses the problem of the three-dimensional free vibration behavior of skew magneto-electro-elastic plates under the framework of a higher order shear deformation theory. To this end, the finite element method was adopted considering the Hamilton’s principle. The results obtained from the present finite element model are verified with the simulation results of COMSOL software. Further, a parametric study is carried out to evaluate the influence of boundary conditions, stacking sequence, aspect ratio, and the length-to-width ratio. A special emphasis has been given to the natural frequency characteristics of multiphase skew magneto-electro-elastic plates as well. The results from the present analyses allow concluding on the significant influence that the geometrical skewness has on the free vibration behavior of these plates.Vinyas M.Nischith G.Loja M.A.R.Ebrahimi F.Dinh Duc Nguyenducnd@vnu.edu.vn2019-07-05T03:05:29Z2019-07-05T03:05:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3492This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34922019-07-05T03:05:29ZEffects of porosity and thermomechanical loading on free vibration and nonlinear dynamic response of functionally graded sandwich shells with double curvatureThe fundamental frequencies and nonlinear dynamic responses of functionally graded sandwich shells with double curvature under the influence of thermomechanical loadings and porosities are investigated in this study. Two material models are considered. The continuity requirement of material properties throughout layers are fulfilled by newly introducing refined effects of two porosity types regarding the average of constituent properties weighted by the porosity volume fraction. The first-order shear deformation theory taking the out-of-plane shear deformation into account is employed to obtain the Lagrange equation of motions. The number of primary variables reduces from five to three after introducing the Airy stress function. The system of dynamic governing equations is obtained by utilizing the Bubnov–Galerkin procedure. The natural frequencies are analytically computed by solving eigenvalue problems, and the fundamental frequencies are acquired by further assumptions about the inertial force caused by the shell rotation variables. The nonlinear dynamic responses of the functionally graded spherical, cylindrical, and hyperbolic paraboloid shells under the influence of different geometry configurations, loading conditions, and porosity types and degrees are obtained by applying the fourth-order Runge–Kutta method. The numerical results are presented and verified with available studies in the literature. Although porosities are usually considered material defects weakening the structure performance, this study has proved clearly that porosities stiffen the shell structures to some extent.Minh Chien TrinhDinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock Kim2019-07-05T01:54:10Z2019-07-05T01:54:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3491This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34912019-07-05T01:54:10ZFree vibration and nonlinear dynamic response of imperfect nanocomposite FG-CNTRC double curved shallow shells in thermal environmentAnalytical solutions for the nonlinear vibration of imperfect functionally graded nanocomposite (FG-CNTRC) double curved shallow shells on elastic foundations subjected to mechanical load in thermal environments are introduced in this paper. The double curved shallow shells are reinforced by single-walled carbon nanotubes (SWCNTs) which are assumed to be graded through the thickness direction according to the different types of linear functions. Motion and compatibility equations are derived using Reddy's higher order shear deformation shell theory and taking into account the effects of initial geometrical imperfection and temperature – dependent properties. The deflection – time curve and the natural frequency are determined by using Galerkin method and fourth – order Runge – Kutta method. The effects geometrical parameters, elastic foundations, initial imperfection, temperature increment, mechanical loads and nanotube volume fraction on the nonlinear thermal vibration of the nanocomposite double curved shallow shells are discussed in numerical results. The accuracy of present approach and theoretical results is verified by some comparisons with the known data in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnHadavinia HomayounQuoc Quan Tranquantq1505@gmail.comDinh Khoa Nguyen2019-07-05T01:53:21Z2019-07-05T01:53:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3490This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34902019-07-05T01:53:21ZNonlinear thermal vibration of carbon nanotube polymer composite elliptical cylindrical shellsThis paper investigated the nonlinear
vibration and dynamic response of the carbon nanotube polymer composite elliptical cylindrical shells
on elastic foundations in thermal environment. The
material properties of the nanocomposite elliptical
cylindrical shells are assumed to depend on temperature and graded in the thickness direction according
to various linear functions. The shell is subjected to the
combination of the uniformly distributed transverse
load in harmonic form and the uniform temperature
rise. The motion and geometrical compatibility equations are derived based on the Reddy’s higher order
shear deformation shell theory. The natural frequencies and the deflection amplitude–time curves of the
shell are determined by using the Galerkin method and
fourth-order Runge–Kutta method. The numerical
results show not only the positive influences of carbonDinh Dat NgoQuoc Quan Tranquantq1505@gmail.comDinh Duc Nguyenducnd@vnu.edu.vn2019-07-05T01:52:29Z2019-07-05T01:52:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3489This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34892019-07-05T01:52:29ZUsability and challenges of offshore wind energy in Vietnam revealed by the regional climate model simulationThis study revealed great potential and shortcoming of offshore wind energy in Vietnam by numerical simulations with Weather Research and Forecasting (WRF) model at 10 km resolution for 10 years (2006-2015). The greatest energy potential was found in the offshore area of Phu Quy island (Binh Thuan province). The area, alone, can provide the 38.2 GW power generation capacity corresponding to the increasing renewable-energy demand by 2030 planned by the country. There is also a drawback of the wind resource, which is associated with strong multiple-scale temporal variabilities. The seasonal variability associated with monsoon onsets and daily variability associated with the wind diurnal cycles were found ranging 30-50%. Meanwhile, the inter-annual variability could reach up to 10%. These variabilities must be considered when designing wind farms and grids over the region. Additionally, due to the fact that the WRF model performed climatological features of the winds well against the observations, this results indicate that it can be useful tools for wind-power assessment as compared to other reanalysis or QuikSCAT data with courser spatio-temporal resolutions.Van Q.DoanDinh Van-NguyenKusaka HiroyukiThanh CongToan Du VanDinh Duc Nguyenducnd@vnu.edu.vn2019-07-05T01:51:19Z2019-07-05T01:51:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3488This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34882019-07-05T01:51:19ZNonlinear vibration and dynamic buckling of eccentrically oblique stiffened FGM plates resting on elastic foundations in thermal environmentThis paper presents a semi-analytical approach to investigate the nonlinear dynamic response and vibration of eccentrically oblique stiffened functionally graded plate resting on elastic foundation. The Lekhnitskii's smeared stiffener technique is improved by using a transformation technique for oblique stiffeners. Governing equations are solved by classical shell theory, Galerkin method, stress function with temperature-dependent material effects. The results show the influences of geometrical parameters, material properties, imperfection, the elastic foundations, eccentrically oblique stiffeners, mechanical loads and temperature on the nonlinear dynamic response and nonlinear vibration of plates. The numerical results in this paper are compared with the results reported in other reports.Seung-Eock KimDinh Duc Nguyenducnd@vnu.edu.vnHoai Nam VuVan Sy Nguyen2019-06-25T15:42:55Z2019-06-25T15:42:55Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3509This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35092019-06-25T15:42:55ZOn three soft rectangle packing problems with guillotine constraintsWe investigate how to partition a rectangular region of length L1 and height L2 into n rectangles of given areas (a1,…,an) using two-stage guillotine cuts, so as to minimize either (i) the sum of the perimeters, (ii) the largest perimeter, or (iii) the maximum aspect ratio of the rectangles. These problems play an important role in the ongoing Vietnamese land-allocation reform, as well as in the optimization of matrix multiplication algorithms. We show that the first problem can be solved to optimality in O(nlogn) , while the two others are NP-hard. We propose mixed integer linear programming formulations and a binary search-based approach for solving the NP-hard problems. Experimental analyses are conducted to compare the solution approaches in terms of computational efficiency and solution quality, for different objectives.Quoc Trung BuiThibaut VidalMinh Hoang Haminhhoang.ha@vnu.edu.vn2019-06-20T22:35:30Z2019-06-20T22:35:30Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3506This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35062019-06-20T22:35:30ZDesign Optimization of an Anisotropic Magnetoresistance
Sensor for Detection of Magnetic NanoparticlesRecent studies have shown that the magnetic field sensitivity of an anisotropic magnetoresistance (AMR) sensor using a single-layer Ni80Fe20 thin film can be considerably improved by increasing the shape anisotropy of the film. In this work, an effective approach for improving the sensitivity and reducing the magnetic coercive field as well as the thermal noise contribution in an AMR Wheatstone bridge sensor is proposed by combining multiple resistors in the series–parallel combination circuits. Four different AMR sensor designs, consisting of a single resistor, three and five resistors in series and six resistors in series–parallel connection, were fabricated by using Ta (10 nm)/Ni80Fe20 (5 nm)/Ta (10 nm) films grown on thermally oxidized Si substratesunder the presence and the absence of a biasing magnetic field (900 Oe). Theresults showed that the sensors based on series–parallel combination gain a magnetic sensitivity (SH) 1.72 times higher than that of the sensor based on the series connection. This optimized sensor has improved the capacity of detecting various concentrations of magnetic nanoparticles with a detection limit of magnetic moments estimated to be about 0.56 uemuKhac Quynh LeDinh Tu BuiViet Anh CaoHuu Duc Nguyenducnh@vnu.edu.vnAnh Tuan PhungTien Dung TranThi Huong Giang Dogiangdth@vnu.edu.vn2019-06-20T22:34:01Z2019-06-20T22:34:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3503This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35032019-06-20T22:34:01ZON LOCALLY MINIMUM AND STRONGEST ASSUMPTION GENERATION METHOD FOR COMPONENT-BASED SOFTWARE VERIFICATIONSince software becomes more complex during its life cycle, the veriﬁcation cost becomes higher, especially for such methods which are using model checking in general and assume-guarantee reasoning in speciﬁc. To address the problem of reducing the assume-guarantee veriﬁcation cost, this paper presents a method to generate locally minimum and strongest assumptions for veriﬁcation of component-based software. For this purpose, we integrate a variant of membership queries answering technique to an algorithm which considers candidate assumptions that are smaller and stronger ﬁrst, larger and weaker later. Because the algorithm stops as soon as it reaches a conclusive result, the generated assumptions are the locally minimum and strongest ones. The correctness proof of the proposed algorithm is also included in the paper. An implemented tool, test data, and experimental results are presented and discussed.Hoang Viet Tranvietth2004@gmail.comNgoc Hung Phamhungpn@vnu.edu.vnViet Ha Nguyenhanv@vnu.edu.vn2019-06-20T22:33:53Z2019-06-20T22:33:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3502This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35022019-06-20T22:33:53ZON IMPROVEMENTS OF DIRECTED AUTOMATED RANDOM TESTING IN TEST DATA GENERATION FOR C++ PROJECTSThis paper improves the breadth-ﬁrst search strategy in directed automated random testing (DART) to generate a fewer number of test data while gaining higher branch coverage, namely Static DART or SDART for short. In addition, the paper extends the test data compilation mechanism in DART, which currently only supports the projects written in C, to generate test data for C++ projects. The main idea of SDART is when it is less likely to increase code coverage with the current path selection strategies, the static test data generation will be applied with the expectation that more branches are covered earlier. Furthermore, in order to extend the test data compilation of DART for C++ context, the paper suggests a general test driver technique for C++ which supports various types of parameters including basic types, arrays, pointers, and derived types. Currently, an experimental tool has been implemented based on the proposal in order to demonstrate its eﬃcacy in practice. The results have shown that SDART achieves higher branch coverage with a fewer number of test data in comparison with that of DART in practice.Duc Anh Nguyennguyenducanh@vnu.edu.vnNguyen Huong Tran17028005@vnu.edu.vnDinh Hieu Vohieuvd@vnu.edu.vnNgoc Hung Phamhungpn@vnu.edu.vn2019-06-19T12:28:55Z2019-06-19T12:28:55Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3531This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35312019-06-19T12:28:55ZA Model Based Poisson Point Process for Downlink Cellular Networks Using Joint SchedulingThis paper proposes a model based on a random cellular network to analyse performance of Joint Scheduling in which a typical user measures signal-to-interference-plus-noise ratio (SINR) on different resource blocks from K nearest BSs in order to find out the BS with the highest SINR to establish communication. The paper derives the general form of average coverage probability of a typical user in the case of $$K>2$$K>2and its close-form expression in the case of $$K=2$$K=2. The analytical results which are verified by Monte Carlo simulation indicates that (1) using the Joint Scheduling can improve the user's performance up to $$34.88 \backslash%$$34.88%in the case of the path loss exponent $$\backslashalpha = 3$$α=3; (2) the effect of the density of BSs on the user association probability is infinitesimal.Sinh Cong Lamcongls@vnu.edu.vnKumbesan Sandrasegarankumbesan.sandrasegaran@uts.edu.au2019-06-16T10:16:50Z2019-06-16T10:16:50Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3482This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34822019-06-16T10:16:50ZOn The Successful Delivery Probability of
Full-Duplex Enabled Mobile Edge CachingCache hit ratio (CHR) is a common metric to evaluate the performance of an edge caching system. While CHR is efficient to measure throughput reduction gain, it fails to
guarantee user quality of experience since CHR does not capture the last-mile channel uncertainty. In this letter, we investigate a novel successful delivery probability (SDP) metric of full-duplex enabled mobile edge caching (FD-MEC) systems, defined as a probability that the user receives the requested file before a tolerable delay. Firstly, the average SDP is derived in a closed-form expression for arbitrary caching policy and network topology, taking into account the wireless fading distribution. Secondly, based on the derived SDP, a sub-optimal cache placement is proposed to maximize the average SDP, which is analytically shown to surpass both the most popular and uniform caching policies. Finally numerical results are presented to verify the accuracy of our analysis and demonstrate the effectiveness of our proposed cache placement design.Thang Vu Xuanthang.vu@uni.luLei LeiLeiLei@gmail.comSymeon ChatzinotasChatzinotas@gmail.comBj¨orn Otterstenbjorn.ottersten@uni.luVu Trinh Anhvuta@vnu.edu.vn2019-06-03T04:23:07Z2019-06-03T04:23:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3461This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34612019-06-03T04:23:07ZNonlinear dynamic response and vibration of functionally graded nanocomposite cylindrical panel reinforced by carbon nanotubes in thermal environmentThis paper investigated the nonlinear dynamic response and vibration of functionally graded carbon nanotubes-reinforced composite cylindrical panels with the support elastic foundations subjected to mechanical, thermal, and damping loads based on Reddy’s higher order shear deformation shell theory. The cylindrical panel is reinforced by single-walled carbon nanotubes which are graded through the panel thickness according to the different linear functions. The effective material properties of the panel are assumed to depend on temperature and estimated through the rule of mixture. The nonlinear dynamic response and natural frequency for functionally graded carbon nanotubes-reinforced composite cylindrical panel are determined by applying the Galerkin method and fourth-order Runge–Kutta method. In numerical results, the effects of geometrical parameters, temperature increment, nanotube volume fraction, elastic foundations, and types of carbon nanotubes distributions on the nonlinear vibration of functionally graded carbon nanotubes-reinforced composite cylindrical panel are studied and discussed in detail. The present theory and approach are validated by comparing with those in the literature.Dinh Khoa NguyenMinh Anh Vuvuminhanhhp@gmail.comDinh Duc Nguyenducnd@vnu.edu.vn2019-06-03T04:21:27Z2019-06-03T04:21:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3460This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34602019-06-03T04:21:27ZNonlinear buckling and post-buckling of eccentrically oblique stiffened sandwich functionally graded double curved shallow shellsThis paper aims to investigate the nonlinear buckling and post-buckling of eccentrically oblique stiffened sandwich functionally graded double curved shallow shells resting on elastic foundations in thermal environment. The shells are reinforced by functionally graded eccentrically oblique stiffeners with deviation angles. Two types of sandwich functionally graded double curved shallow shells with the differences of distribution of functionally graded face sheets and homogeneous core are considered. Material properties of the sandwich shells and stiffeners are assumed to vary continuously and smoothly in the thickness direction according to Sigmoid power law. The formula of force and moment resultants and the nonlinear equilibrium equations are established based on the improved Donnell theory and Lekhnitskii's smeared stiffeners technique. The analytical displacement solutions are chosen based on the trigonometric forms satisfying the boundary conditions. The value of critical buckling loads and the load – deflection curves of the shells are obtained by using the Bubnov – Galerkin method. In numerical results; effect of geometrical parameters, elastic foundations, temperature increment, compressive load and oblique stiffeners on the critical buckling loads and post-buckling load – deflection curves of the shells are studied specifically. The obtained results are also compared with others from literature to validate the accuracy of the present method and approach.Quoc Quan TranHuy Cuong NguyenDinh Duc Nguyenducnd@vnu.edu.vn2019-06-03T04:19:45Z2019-06-03T04:19:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3451This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34512019-06-03T04:19:45ZCharacterization of performance parameters of organic solar cells with a buffer ZnO layerBy embedding a thin ZnO layer sandwiched between the hole transport and photoactive layers, organic solar cells (OSC) based on poly(3-hexylthiophene) (P3HT) were prepared by spincoating. UV-Vis spectra of the composite films showed that ZnO exhibited a suitable buffer layer that could block holes movement throughout the heterojunction of ITO/ZnO. The enhancement in the fill factor (FF) of the buffer-OSC (BOSC) is attributed to the presence of nanoheterojunctions of ZnO/PCBM and ZnO/ITO. For the normal temperature, the increase of the open-circuit potential and short-circuit current resulted in an overall increase of the energy conversion efficiency. Comparing to OSCs without buffer layer (WOSC), the laminar structure of ITO/ZnO/P3HT/PCBM/Li/Al cells possess a much larger photovoltaic energy conversion efficiency, namely 2.12% (for BOSC) compared to 1.75% (for WOSC).Nang Dinh Nguyendinhnn@vnu.edu.vnHyung-Kook KimDinh Lam Nguyenlamnd2005@vnu.edu.vnDuc Cuong Nguyencuongnd@vnu.edu.vnPhuong Hoai Nam Nguyennamnph@vnu.edu.vn2019-06-03T04:15:37Z2019-06-03T04:15:37Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3442This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34422019-06-03T04:15:37ZFlexible deployment of component-based distributed applications on the Cloud and beyondIn an effort to minimize operational expenses and supply users with more scalable services, distributed applications are actually going towards the Cloud. These applications, sent out over multiple environments and machines, are composed by inter-connecting independently developed services and components. The implementation of such programs on the Cloud is difficult and generally carried out either by hand or perhaps by composing personalized scripts. This is extremely error prone plus it has been found that misconfiguration may be the root of huge mistakes. We introduce AutoBot, a flexible platform for modeling, installing and (re)configuring complex distributed cloud-based applications which evolve dynamically in time. AutoBot includes three modules: A simple and new model describing the configuration properties and interdependencies of components; a dynamic protocol for the deployment and configuration ensuring appropriate resolution of these interdependencies; a runtime system that guarantee the proper configuration of the program on many virtual machines and, if necessary, the reconfiguration of the deployed system. This reduces the manual application deployment process that is monotonous and prone to errors. Some validation experiments were conducted on AutoBot in order to ensure that the proposed system works as expected. We also discuss the opportunity of reusing the platform in the transition of applications from Cloud to Fog computing.Manh Linh Phamlinhmp@vnu.edu.vnTruong Thang Nguyenntthang@ioit.ac.vn2019-06-03T04:14:06Z2019-06-03T04:14:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3437This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34372019-06-03T04:14:06ZUFBoot2: Improving the Ultrafast Bootstrap ApproximationAbstract
The standard bootstrap (SBS), despite being computationally intensive, is widely used in maximum likelihood phylogenetic analyses. We recently proposed the ultrafast bootstrap approximation (UFBoot) to reduce computing time while achieving more unbiased branch supports than SBS under mild model violations. UFBoot has been steadily adopted as an efficient alternative to SBS and other bootstrap approaches. Here, we present UFBoot2, which substantially accelerates UFBoot and reduces the risk of overestimating branch supports due to polytomies or severe model violations. Additionally, UFBoot2 provides suitable bootstrap resampling strategies for phylogenomic data. UFBoot2 is 778 times (median) faster than SBS and 8.4 times (median) faster than RAxML rapid bootstrap on tested data sets. UFBoot2 is implemented in the IQ-TREE software package version 1.6 and freely available at http://www.iqtree.org.Thi Diep Hoangdiepht@vnu.edu.vnOlga Chernomorvon Haeseler ArndtQuang Minh BuiSy Vinh Levinhls@vnu.edu.vn2019-06-03T04:09:45Z2019-06-03T04:09:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3462This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34622019-06-03T04:09:45ZNonlinear buckling and post-buckling of functionally graded CNTs reinforced composite truncated conical shells subjected to axial loadThis study deals with the nonlinear static analysis of functionally graded carbon nanotubes reinforced composite
(FG-CNTRC) truncated conical shells subjected to axial load based on the classical shell theory. Detailed studies for both
nonlinear buckling and post-buckling behavior of truncated conical shells. The truncated conical shells are reinforced by singlewalled carbon nanotubes which alter according to linear functions of the shell thickness. The nonlinear equations are solved by
both the Airy stress function and Galerkin method based on the classical shell theory. In numerical results, the influences of
various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the
nonlinear buckling and post-buckling behavior of FG-CNTRC truncated conical shells are presented. The proposed results are
validated by comparing with other authors.Quang Chan DoDinh Nguyen Phamnguyenpd@vnu.edu.vnDinh Quang Vuquangvd2510@gmail.comThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2019-06-03T04:07:26Z2019-06-03T04:07:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3449This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34492019-06-03T04:07:26ZImproving the Bag-of-Words model with Spatial Pyramid matching using data augmentation for fine-grained arbitrary-oriented ship classificationIn this letter, we investigate fine-grained classification of arbitrary-oriented ships in very high resolution optical imagery using Bag of Word model with Spatial Pyramid (SP-BoW). Given that based on ‘spatial pyramid’ of the histogram of local features, the final feature vectors not only count the multiplicity of ‘words’ but also represent their spatial topology. We attempt to improve the performance of this model by introducing augmented data for training phase. Our aim is to make the dataset big enough to be able to capture holistic variation of ship orientation. Three data augmentation operations are used including random rotate by an angle of modulo 90°, random flip-left-right, and random flip-top-bottom. Through this procedure, our trained SP-BoW model is able to get better generalization. The proposed approach is validated on the High-Resolution Ship Collections 2016 (HRSC2016) ship dataset. The results indicate that training on augmented data can significantly improve the performance of SP-BoW. Beside, compared to other state-of-the-art convolutional neural network-based approaches, the approach proposed in this research has yielded competitive results and could make it a good baseline for evaluating more sophisticated CNN architecture in the future.Viet Hung Luuhunglv@fimo.edu.vnVan Kiet DinhNguyen Hoang Hoa LuongQuang Hung Buihungbq@vnu.edu.vnThi Nhat Thanh Nguyenthanhntn@vnu.edu.vn2019-06-03T03:58:45Z2020-01-06T07:40:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3467This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34672019-06-03T03:58:45ZHierarchical Distributed Control for Global Network Integrity Preservation in Multirobot SystemsIn this paper, we address a novel hierarchical distributed control (HDC) strategy for networked multirobot systems (MRSs). This strategy is developed on a geometric approach without requiring estimation of algebraic connectivity. It is originally based upon behavioral control, but upgraded by distributed node control with a mobility constraint for global network integrity preservation and distributed connectivity control with a local connectivity minimization strategy for network coverage expansion. Thanks to properties of HDC, a networked MRS is capable of achieving high performance with cooperative tasks. We have examined and evaluated our proposed method in both simulations with up to 100 simulated robots and real-world experiments with up to 14 real robots.Duy Hung Phamhungpd@vnu.edu.vnQuang Vinh Tranvinhtq@vnu.edu.vnTrung Dung Ngodungnt@ieee.org2019-06-03T03:55:48Z2019-06-03T03:55:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3447This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34472019-06-03T03:55:48ZA Dynamic-Clustering Backup Scheme for High-Availability Distributed File Sharing SystemsDHT routing algorithms can provide efficient mechanisms for resource placement and lookup for distributed file sharing systems. However, we must still deal with irregular and frequent join/leave of nodes and the problem of load unbalancing between nodes in DHT-based file sharing systems. This paper presents an efficient file backup scheme based on dynamic DHT key space clustering in order to guarantee data availability and support load balancing. The main idea of our method is to dynamically divide the DHT network into a number of clusters, each of which locally stores and maintains data chunks of data files to guarantee the data availability of user data files even when node churn occurs. Further, high-capacity nodes in clusters are selected as backup nodes to achieve adequate load balancing. Simulation results demonstrate the superior effectiveness of the proposed scheme over other file replication schemes.Hoai Son Nguyensonnh@vnu.edu.vnDinh Nghia Nguyennghiahvan@gmail.comShinji Sugawara2019-06-03T03:50:39Z2019-06-03T03:50:39Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3422This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34222019-06-03T03:50:39ZGeometrically nonlinear dynamic response of eccentrically stiffened circular cylindrical shells with negative Poisson’s ratio in auxetic honeycombs core layerHong Cong PhamThanh Long PhamVan Nhat NguyenDinh Duc Nguyenducnd@vnu.edu.vn2019-06-03T03:48:27Z2019-06-03T03:48:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3421This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34212019-06-03T03:48:27ZBending and thermal buckling of unsymmetric functionally graded sandwich beams in high temperature environment based on a new third order shear deformation theoryThanh Trung TranHoang Nam NguyenVan Thom DoVan Minh PhungDinh Duc Nguyenducnd@vnu.edu.vn2019-06-03T03:47:07Z2019-06-03T03:47:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3420This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34202019-06-03T03:47:07ZNonlinear buckling and post-buckling of FGM toroidal shell segment under torsional load in thermal environment within Reddy’s third-order shear deformation shell theoryMinh Vuong PhamDinh Duc Nguyenducnd@vnu.edu.vn2019-02-18T03:42:27Z2019-02-18T03:42:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3435This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34352019-02-18T03:42:27ZMaximizing misinformation restriction within time and budget constraintsOnline social networks have become popular media worldwide. However,they also allow rapid dissemination of misinformation causing negative impacts tousers. With a source of misinformation, the longer the misinformation spreads, thegreater the number of affected users will be. Therefore, it is necessary to preventthe spread of misinformation in a specific time period. In this paper, we proposemaximizing misinformation restriction (MMR) problem with the purpose of finding aset of nodes whose removal from a social network maximizes the influence reductionfrom the source of misinformation within time and budget constraints. We demonstratethat theMMRproblem is NP-hard even in the case where the network is a rooted treeCanh V. Phammaicanhki@gmail.comMy T. ThaiHieu V. DuongBao Q. BuiXuan Huan Hoanghuanhx@vnu.edu.vn2019-01-07T03:14:44Z2019-01-07T03:14:44Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3399This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33992019-01-07T03:14:44ZNanometer-scale local probing of X-ray absorption spectra of Co/Pt multilayer filmWe report our local X-ray absorption spectra (XAS) measurement mapping for a Co/Pt multilayer using
scanning transmission microscopy with 25-nm spatial resolution and 0.1-eV spectral resolution. We have
systematically analyzed the two-dimensional XAS intensity variation over the corresponding magnetic domain
patterns, revealing a XAS profile across the magnetic domain wall as well as the simultaneous high-throughput
measurement of local XAS spectra.Duy Truong QuachDuc Thang Phampdthang@vnu.edu.vnDjati HankodoJe-Ho ShimDong Eon KimKyung-Min LeeJong-Ryul JeongNamdong KimHyun-Joon ShinDong-Hyun Kim2019-01-07T03:12:06Z2019-01-07T03:12:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3400This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34002019-01-07T03:12:06ZAlternative approaches used to assess structural changes of natural zircon caused by heat treatmentThi Thu Huong LEltthuongvnu@yahoo.comThi Minh Thuyet NguyenThe Long PhanNgo TranNgoc Toan DangDuc Thang Phampdthang@vnu.edu.vnThe Huy Bui2019-01-07T02:43:25Z2019-01-07T02:43:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3401This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34012019-01-07T02:43:25ZCrystal Structure and Magnetic Properties of La0.8R0.2(Fe0.88Si0.12)13 (R = Sm and Tb) CompoundsVan Hiep VuongKhac Thuan NguyenThi Kim Anh DoNam Nhat Hoangnhathn@vnu.edu.vn2019-01-07T02:40:13Z2019-01-07T02:40:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3402This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34022019-01-07T02:40:13ZLow Field Magnetocaloric Effect in Bulk and Ribbon Alloy La(Fe0.88Si0.12)13Van Hiep VuongThi Kim Anh DoDuy Thien NguyenQuang Hoa NguyenNam Nhat Hoangnhathn@vnu.edu.vn2019-01-07T02:00:01Z2019-01-07T02:00:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3398This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33982019-01-07T02:00:01ZMinor hysteresis patterns with a rounded/sharpened reversing behavior in ferromagnetic multilayerHysteresis of ferromagnetic system exhibits a fundamental stimulus-response behavior, thereby
casting all the important macromagnetic system parameters such as coercivity, nucleation feld,
saturation magnetization, and hysteresis loss. Recently, increasing attention has been paid to
exploration of relatively less understood minor loop behavior, since faster operation of magnetic
devices is inevitably accompanied by minor hysteresis behavior from cycling among unsaturated
ferromagnetic states. Here, we report our microscopic investigation of unusual minor hysteresis loop
behavior, represented by rounded or sharpened response of minor hysteresis loop of (CoFeB/Pd)4
multilayer flm. It is observed that rounded and sharpened response in the minor hysteresis response
could be manifested under proper conditions. The minor loop behavior has been systematically
investigated by direct microscopic magnetic domain observation using magneto-optical Kerr
microscopy. The rounded response of magnetization at the reversing external feld along the minor
hysteresis curve, so far neglected or considered as one of ‘unusual’ behaviors, has been found to be
elaborately controllable by tuning the reversing feld strength and the feld sweep rate for multilayers
with low repeat numbers. Variable roundedness of the minor hysteresis loop is understandable based on
the analysis of magnetic domain dynamics such as domain nucleation and the domain wall velocity.Duy Truong QuachDuc Thang Phampdthang@vnu.edu.vnDuc The NgoThe Long PhanSeung-Young ParkSang-Hyuk LeeDong-Hyun Kim2018-12-25T11:03:22Z2018-12-25T11:03:22Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3375This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33752018-12-25T11:03:22ZGuruWS: A Hybrid Platform for Detecting Malicious Web Shells and Web Application VulnerabilitiesWeb application/service is now omnipresent but its security risks, such as malware and vulnerabilities, are indeed underestimated. In this paper, we propose a protective, extensible and hybrid platform, named GuruWS, for automatically detecting both web application vulnerabilities and malicious web shells. Based on the original PHP vulnerability scanner THAPS, we propose E-THAPS which implements a novel detection mechanism, an improved SQL injection, Cross-site Scripting and vulnerability detection capabilities. For malicious web shell detection, taint analysis and pattern matching methods are chosen to be implemented in GuruWS. A number of extensive experiments are carried out to prove the outstanding performance of our proposed platform in comparison with several existing solutions in detecting either web application vulnerabilities or malicious web shells.Van Giap Legiaplvk57@gmail.comHuu Tung Nguyenhtung.nht@gmail.comDuy Phuc Phamduyphuc@vnu.edu.vnNgoc Hoa Nguyenhoa.nguyen@vnu.edu.vn2018-12-20T06:04:47Z2018-12-20T06:04:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3289This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32892018-12-20T06:04:47ZView Synthesis Method for 3D Video Coding Based on Temporal and Inter ViewTung Long VuongDinh Minh Leminhld_57@vnu.edu.vnVan Xiem Hoangxiemhoang@vnu.edu.vnTrieu Duong Dinhduongdt@vnu.edu.vnHuu Tien VuThanh Ha Leltha@vnu.edu.vn2018-12-19T05:07:30Z2018-12-19T09:21:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3324This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33242018-12-19T05:07:30ZInfluences of Morphology of Window Layer on the Characteristics of PbS Quantum Dot Solar CellsBackground: In QDs-based solar cell devices, the PbS QDs layer was mainly focused
to optimize. The ZnO electron acceptor layer attracts less attention whereas it shows the key
roles in extracting and transporting charge carriers in heterojunction. The utilization of 1-D ZnO
structures has been demonstrated to be large interface areas and good carrier pathways for efficient carrier collection. However, the influences of the morphology of metal oxide nanostructures on the photovoltaic performance of QD-based solar cells have been few in-depth reports.
Objective: In this work, ZnO NRs/PbS QD based solar cells were fabricated. The influences of
the ZnO NRs array structures on characteristics of ZnO NRs/PbS QD based solar cells were investigated.
Method: ZnO NRs/PbS QD based solar cells were fabricated via spin coating method. XRD,
SEM, UV-VIS-NIR spectrophotometer, I-V and EQE measurement systems were utilized to investigate the fabricated samples.
Results: We have found optimum combinations of the linked parameters of ZnO NRs, their
length of (230 ± 5) nm and density of (1.50 ± 5)x1010 # of rods.cm-2, that exhibit maximum efficiency of ∼2.5% for the ZnO NR/PbS QDs based solar cell.
Conclusion: The influences the ZnO NRs structures on the solar cell characteristics, including
the absorption, external quantum efficiency, and current density-voltage curves, were investigated. There seems to be an optimum between NR length and their density for resulting in maximum efficiency. This could be due the interplay of solar flux absorption and junction area controlled by these two parameters of ZnO NR morphology.Thu Ha NguyenDinh Lam Nguyenlamnd2005@vnu.edu.vn2018-12-17T09:42:49Z2018-12-17T09:42:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3322This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33222018-12-17T09:42:49ZMechanism of the photocatalytic activity of p-Si(100)/n-ZnO nanorods heterojunctionA heterojunction of p-Si(100)/n-ZnO nanorods was fabricated by a simple hydrothermal method. The
photocatalytic activity of this heterojunction was examined by degradation of Rhodamine B (RhB) under
UV light irradiation. The results indicated that the p-Si(100)/n-ZnO nanorods heterojunction exhibits
higher photocatalytic activity compared to that of a glass/n-ZnO nanorods. The inner electric field created
by the space charge region of heterojunction will oppose the recombination of photogenerated electrons
and holes. Furthermore, this heterojunction serves as a convenient recyclable and effective photocatalyst.
The photodecomposition rate of RhB after 5 cycles is negligible change in an experiment using this
heterojunction.Thi Hoa NguyenVan Cuong VuongDinh Lam Nguyenlamnd2005@vnu.edu.vn2018-12-17T04:09:18Z2018-12-17T19:19:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3317This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33172018-12-17T04:09:18ZLow-complexity adaptive algorithms for robust subspace trackingThis paper introduces new, low-complexity, adaptive
algorithms for robust subspace tracking in certain adverse scenarios of noisy data. First, an adequate weighted least-squares criterion is considered for the design of a robust subspace tracker that is most efficient in the burst noise case. Second, by using data pre-processing and robust statistics estimate, we introduce a second method that is shown to be the most efficient for subspace tracking in the case of impulsive noise (e.g. α-stable noise). Finally, a ‘detect-and-skip’ approach is adopted where the corrupted measurements are detected and treated as ‘missing’ data. The resulting algorithm is particularly effective in the case where the data is affected by sparse ‘outliers’. All these approaches were analyzed and their convergence properties
were investigated. Moreover, the proposed subspace tracking algorithms were compared by simulated experiments to some state-of-the-art methods, in different noise/outliers contexts.Linh Trung Nguyenlinhtrung@vnu.edu.vnViet Dung Nguyennvdung@vnu.edu.vnMessaoud Thamerim_thameri@hotmail.comMinh Chinh Truongtmchinh@gmail.comKarim Abed-Meraimkarim.abed-meraim@univ-orleans.fr2018-12-17T03:07:14Z2018-12-17T03:07:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3310This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33102018-12-17T03:07:14ZFast phylogenetic maximum parsimony tree inference and bootstrap approximationBackground: The nonparametric bootstrap is widely used to measure the branch support of phylogenetic trees. However, bootstrapping is computationally expensive and remains a bottleneck in phylogenetic analyses. Recently, an ultrafast bootstrap approximation (UFBoot) approach was proposed for maximum likelihood analyses. However, such an approach is still missing for maximum parsimony.
Results: To close this gap we present MPBoot, an adaptation and extension of UFBoot to compute branch supports under the maximum parsimony principle. MPBoot works for both uniform and non-uniform cost matrices. Our analyses on biological DNA and protein showed that under uniform cost matrices, MPBoot runs on average 4.7 (DNA) to 7 times (protein data) (range: 1.2–20.7) faster than the standard parsimony bootstrap implemented in PAUP*; but 1.6 (DNA) to 4.1 times (protein data) slower than the standard bootstrap with a fast search routine in TNT (fast-TNT). However, for non-uniform cost matrices MPBoot is 5 (DNA) to 13 times (protein data) (range:0.3–63. 9) faster than fast-TNT. We note that MPBoot achieves better scores more frequently than PAUP* and fast-TNT. However, this effect is less pronounced if an intensive but slower search in TNT is invoked. Moreover, experiments on large-scale simulated data show that while both PAUP* and TNT bootstrap estimates are too conservative, MPBoot bootstrap estimates appear more unbiased.
Conclusions: MPBoot provides an efficient alternative to the standard maximum parsimony bootstrap procedure. It shows favorable performance in terms of run time, the capability of finding a maximum parsimony tree, and high bootstrap accuracy on simulated as well as empirical data sets. MPBoot is easy-to-use, open-source and available at http://www.cibiv.at/software/mpboot.Thi Diep Hoangdiepht@vnu.edu.vnSy Vinh Levinhls@vnu.edu.vnFlouri TomasStamatakis Alexandrosvon Haeseler ArndtBui Minh2018-12-17T02:48:33Z2018-12-17T02:48:33Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3275This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32752018-12-17T02:48:33ZAccurate prediction of optimal cancer drug therapies from molecular profiles by a machine-learning algorithm.John F McDonaldRoman MezencevQuoc Long Trantqlong@vnu.edu.vnBenedict BenignoIoana BontaGiuseppe Del Priore2018-12-17T02:47:55Z2018-12-17T02:47:55Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3273This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32732018-12-17T02:47:55ZAn empirical comparison of nine pattern classifiersQuoc Long Trantqlong@vnu.edu.vnK-A TohDipti SrinivasanK-L WongShaun Qiu-Cen Low2018-12-17T02:47:00Z2018-12-17T02:47:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3271This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32712018-12-17T02:47:00ZFeasibility of detecting prostate cancer by ultraperformance liquid chromatography--mass spectrometry serum metabolomicsXiaoling ZangChristina M JonesQuoc Long Trantqlong@vnu.edu.vnMaria Eugenia MongeManshui ZhouL DeEtte WalkerRoman MezencevAlexander GrayJohn F McDonaldFacundo M Fernandez2018-12-14T02:38:08Z2018-12-14T02:38:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3267This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32672018-12-14T02:38:08ZBenchmarking a reduced multivariate polynomial pattern classifierKar-Ann TohQuoc Long Trantqlong@vnu.edu.vnDipti Srinivasan2018-11-26T06:01:00Z2018-11-26T06:01:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3136This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31362018-11-26T06:01:00ZVibration and nonlinear dynamic response of eccentrically stiffened functionally graded composite truncated conical shells surrounded by an elastic medium in thermal environmentsA semi-analytical approach eccentrically stiffened functionally graded (ES-FGM) truncated conical shells surrounded by an elastic medium in thermal environments is presented. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman Donnell sense, the smeared stiffeners technique and Galerkin method, this paper deals with vibration and nonlinear dynamic problem. The truncated conical shells are reinforced by ring stiffeners made of full metal or full ceramic depending on situation of stiffeners at the metal-rich or ceramic-rich side of the shell respectively. In addition, the study is not only assumed that the material properties depend on environment temperature variation, but also considered the thermal stresses in the stiffeners. Numerical results are given to evaluate effects of inhomogeneous, dimensional parameters, outside stiffeners, temperatures and elastic foundations to vibration and nonlinear dynamic response of structures.Quang Chan DoThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2018-11-20T09:05:19Z2018-11-20T09:05:19Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3164This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31642018-11-20T09:05:19ZSi-doping effect on solution-processed In-O thin-film transistorsIn this work, silicon-doped indium oxide thin-film transistors (TFTs) have been fabricated for the first
time by a solution processing method. By varying the Si concentration in the In2O3–SiO2 binary oxide
structure up to 15 at%, the thicknesses, densities, and crystallinity of the resulting In–Si–O(ISO) thin
films were investigated by x-ray reflectivity (XRR) and x-ray diffraction techniques, while the
produced TFTs were characterized by a conventional three-probe method. The results of XRR analysis
revealed that the increase in the content of Si dopant increased the thickness of the produced film and
reduced its density, and that all the Si-doped ISO thin films contained only a single amorphous phase
even after annealing at temperatures as high as 800 °C. The manufactured ISO TFTs exhibited a
reduction in the absolute value of threshold voltage VT close to 0 Vand low current in the off-state, as
compared to those of the non-doped indium oxide films, due to the reduced number of oxygen
defects, which was consistent with the behavior of ISO TFTs fabricated by a sputtering method. The
ISO TFT with a Si content of 3 at% annealed at 400 °Cdemonstrated the smallest subthreshold swing
of 0.5 V/dec, VT of−5 V, mobility of 0.21 cm2 V−1s−1, and on/off current ratio of about 2×107.Ha HoangTatsuki HoriTo-oru YasudaTakio KizuKazuhito TsukagoshiToshihide NabatameNguyen Quoc Trinh BuiAkihiko Fujiwara2018-11-15T09:20:28Z2018-11-15T09:20:28Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3148This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31482018-11-15T09:20:28ZNano ZrO2 Synthesis by Extraction of Zr(IV) from ZrO(NO3)2 by PC88A, and Determination of Extraction Impurities by ICP-MSHigh purity Zirconium (Zr) materials are essential in many components of nuclear reactors, especially fuel cladding tubes. Due to the matrix influence, determination of impurities in the Zr materials requires separation from the Zr matrix. Among extraction methods, solvent extraction is common and suitable for large-scale production. In this study, extraction capability of Zr(IV) by 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (PC88A) was examined by FT-IR and UV of ZrO(NO3)2 salt, PC88A-toluene solvent, and Zr-PC88A-toluene complex. ZrO2 (obtained from Institute for Technology of Radioactive and Rare Elements—ITRRE), after being separated from the Zr matrix, was determined for impurities using internal standard (indium, In) by 50% of PC88A dissolved in toluene. Separation of impurities from the Zr matrix underwent two stages. First, one cycle of extraction of the Zr matrix and impurities in 3 M HNO3 using 50% PC88A/toluene was conducted. Second, impurities were scrubbed by 4 M HNO3 in two cycles. Results revealed that approximately 74% of Zr(IV) was separated to the organic phase and 26% remained in the aqueous phase. Determination of impurities after separation from the Zr matrix by ICP-MS using internal standard in revealed that the recovery of impurities achieved 95–100%. With the mentioned amount of Zr, the effect of the Zr matrix on the determination of elements by ICP-MS is negligible. Levels of impurities have relative standard deviations (RSD) of less than 6.9% and recovery of 88.6–98.8%. Therefore, the determination of impurities has high reliability and accuracy. The back-extraction of Zr(IV) in organic phase by 1 M H2SO4 has stripped about 99.5% of the Zr matrix back to the aqueous phase. Following this, NH3 was added to the solution containing Zr after back-extraction to form Zr(OH)4 which was then desiccated to produce ZrO2. X-ray Diffraction (XRD), Scanning and Transmission Electron Microscopy (SEM and TEM) images showed that the new ZrO2 product has spherical nanostructure with diameters of less than 25 nm, which is suitable for applications for the treatment of colorants, metal ions in wastewater sources and manufacture of anti-corrosion steel. In addition, the energy dispersive X-ray (EDX) of the new ZrO2 product showed that it has high purity.Manh Nhuong Chuchumanhnhuong@dhsptn.edu.vnT. H. Lan Nguyennguyenhienlan@dhsptn.edu.vnXuan Truong Maimaixuantruong@dhsptn.edu.vnVan Thuan Doandoanthuanms@gmail.comLong Giang Bachblgiang@ntt.edu.vnDuy Chinh Nguyenndchinh@ntt.edu.vnDuc Cuong Nguyencuongnd@vnu.edu.vn2018-11-15T09:20:18Z2018-11-15T09:20:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3146This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31462018-11-15T09:20:18ZContributions of poly(3-hexylthiophene) nanowires to alteration of vertical inhomogeneity of bulk-heterojunction active layers and improvements of light-harvesting and power-conversion efficiency of organic solar cellsWe report a 47.1% efficiency improvement resulting from the combination of device-architecture modification and inclusion of poly(3-hexylthiophene-2,5-diyl) nanowires (P3HT NWs) in bulk heterojunction (BHJ) active layers (ALs). Modelling of ellipsometry spectra shows substantial changes in inhomogeneity and optical constants of BHJ ALs with P3HT-NW inclusion. Furthermore, finite-difference time-domain simulation results based on actual device structures with inhomogeneous AL models indicate that enhanced light harvesting is a main contributing factor to efficiency improvement. On the contrary, P3HT-NW inclusion has no significant effect on charge carrier collection, other than suppressing occurrence of cul-de-sac in hole-transport pathways and unfavourable indene-C60 bisadduct domains near top anodes.Sung-yoon JoeShinyoung RyuDuc Cuong Nguyencuongnd@vnu.edu.vnJong Hyuk YimHuiseong JeongNa Young HaY.H. AhnJi-Yong ParkSoonil Leesoonil@ajou.ac.kr2018-11-15T09:20:10Z2018-11-15T09:20:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3145This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31452018-11-15T09:20:10ZTrue nature of active layers in organic solar cells fabricated by sequential casting of donor and acceptor layersThe operation characteristics of nominal bilayer (BL) organic solar cells (OSCs), the active layers (ALs) of which consisted of sequentially casted bottom P3HT donor and top ICBA acceptor layers, resembled those of OSCs with bulk heterojunction (BHJ) ALs. Optical analysis and device simulations showed that such resemblance can be attributed to a similarity in the micromorphology of ALs; as‐deposited BL‐type ALs transformed spontaneously into BHJ‐type ALs. The inclusion of P3HT nanowires (NWs) in the donor layers resulted in different AL micromorphology and consequently a larger power conversion efficiency. Separate assessment of the exciton generation and charge–carrier transport and/or extraction showed that the contribution of P3HT NWs was more prominent in optical effects.Jong Hyuk YimSung‐yoon JoeDuc Cuong Nguyencuongnd@vnu.edu.vnShin Young RyuNa Young HaY. H. AhnJi‐Yong ParkSoonil Leesoonil@ajou.ac.kr2018-11-15T09:20:01Z2018-11-15T09:20:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3144This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31442018-11-15T09:20:01ZHole‐extraction layer dependence of defect formation and operation of planar CH3NH3PbI3 perovskite solar cellsThree planar CH3NH3PbI3 (MAPbI3) solar cells having the same structure except a hole‐extraction layer (HEL) showed distinctive difference in operation characteristics. Analysis of frequency‐dependent capacitance and dielectric‐loss spectra of the three MAPbI3 devices showed two types of recombination‐loss channels with different time constants that we attributed respectively to interface and bulk defects. Discrepancy in defect formation among the three devices with a HEL of PEDOT:PSS, NiOx, or Cu‐doped NiOx was not surprising because grain‐size distribution and crystalline quality of MAPbI3 can be affected by surface energy and morphology of underlying HELs. We were able to quantify interface and bulk defects in these MAPbI3solar cells based on systematic and simultaneous simulations of capacitance and dielectric‐loss spectra, and current–voltage characteristics by using the device simulator SCAPS.Duc Cuong Nguyencuongnd@vnu.edu.vnSung‐yoon JoeNa Young HaHui Joon ParkJi‐Yong ParkY. H. AhnSoonil Leesoonil@ajou.ac.kr2018-11-15T09:19:47Z2018-11-15T09:19:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3019This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30192018-11-15T09:19:47ZSolution-Processible Crystalline NiO Nanoparticles for High-Performance Planar Perovskite Photovoltaic CellsIn this work, we report on solution-based p-i-n-type planar-structured CH3NH3PbI3 perovskite
photovoltaic (PV) cells, in which pre-crystallized NiO nanoparticles (NPs) without post-treatment are
used to form a hole transport layer (HTL). X-ray diffraction and high-resolution transmission electron
microscopy showed the crystallinity of the NPs, and atomic force microscopy and scanning electron
microscopy confirmed the uniform surfaces of the resultant NiO thin film and the subsequent perovskite
photoactive layer. Compared to the conventional poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, the NiO HTL had excellent energy-level alignment with that of CH3NH3PbI3
and improved electron-blocking capability, as analyzed by photoelectron spectroscopy and diode
modeling, resulting in Voc ~0.13 V higher than conventional PEDOT:PSS-based devices. Consequently, a
power conversion efficiency (PCE) of 15.4% with a high fill factor (FF, 0.74), short-circuit current density
(Jsc, 20.2 mA·cm−2), and open circuit voltage (Voc, 1.04 V) having negligible hysteresis and superior air
stability has been achieved.Uisik KwonBong-Gi KimDuc Cuong Nguyencuongnd@vnu.edu.vnJong-Hyeon ParkNa Young HaSeung-Joo KimSeung Hwan KoSoonil Leesoonil@ajou.ac.krDaeho Leedhl@gachon.ac.krHui Joon Parkhuijoon@ajou.ac.kr2018-11-15T09:19:37Z2018-11-15T09:19:37Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3147This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31472018-11-15T09:19:37ZElectrical properties of ion gels based on PVDF-HFP applicable as gate stacks for flexible devicesElectrical characteristics of ion gels prepared by loading different amounts of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) in Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) are investigated and compared with those of ion liquid, [EMIM][TFSI] for possible application as a gate stack for flexible electronic devices. Capacitance and impedance as a function of frequency are measured, which can be well accounted for by a simple circuit model identifying the local device components. The operation of a flexible field effect transistor based on graphene and the ion gel as a top gate stack is also demonstrated.Kwanbyung ChaeDuc Cuong Nguyencuongnd@vnu.edu.vnShinyoung RyuDong-Il YeomSoonil LeeJi-Yong Parkjiyong@ajou.ac.kr2018-11-08T06:55:42Z2018-11-08T06:55:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3140This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31402018-11-08T06:55:42ZOn Domain Driven Design Using Annotation-Based Domain Specific LanguageThe aim of object-oriented domain-driven design (DDD) is to iteratively develop software around a realistic domain model. Recent work in DDD use an annotation-based extension of object-oriented programming language to build the domain model. This model becomes the basis for a ubiquitous language and is used as input to generate software. However, the annotation-based extensions of these work do not adequately address the primitive and essential structural and behavioural modelling requirements of practical software. Further, they do not precisely characterise the software that is generated from the domain model. In this paper, we propose a DSL-based DDD method to address these limitations. We make four contributions: (1) An annotation-based domain-specific language (DSL) named DCSL, whose annotation extension expresses a set of essential structural constraints and the essential behaviour of a domain class. (2) A structural mapping between the state and behaviour spaces of a domain class. This mapping enables a technique for generating the behavioural specification. (3) A technique that uses DCSL to support behavioural modelling with UML activity diagram. (4) A 4-property characterisation of the software generated from the domain model. We demonstrate our method with a Java software tool and evaluate DCSL in the context of DDD.Minh Duc LeDuc Hanh Danghanhdd@vnu.edu.vnViet Ha Nguyenhanv@vnu.edu.vn2018-11-04T09:29:21Z2018-11-04T09:29:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3085This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30852018-11-04T09:29:21ZView synthesis method for 3D video coding based on temporal and inter view correlationRecently, in three-dimensional (3D) television, the temporal correlation between consecutive frames of the
intermediate view is used together with the inter-view correlation to improve the quality of the synthesised view. However, most temporal methods are based on the motion vector fields (MVFs) calculated by the optical flow or block-based motion estimation which has very high computational complexity. To alleviate this issue, the authors propose a temporal-disparity-based view
synthesis (TDVS) method, which uses the MVFs extracted from the bitstreams of side views and motion warping technique to create the temporal correlation between views in the intermediate position. Then a motion compensation technique is used to create a temporal-based view. Finally, the temporal-based view is fused with a disparity-based view which is generated by a traditional depth image-based rendering technique to create the final synthesised view. The fusion of these views is performed based on the side information which is determined and encoded at the sender-side of the 3D video system using a dynamic programming algorithm and rate-distortion optimisation scheme. Experimental results show that the proposed method can
achieve the synthesised view with appreciable improvements in comparison with the view synthesis reference software 1D fast (VSRS-1D Fast) for several test sequences.Long Vuong Tunglongvt94@gmail.comMinh Le Dinhminhle2994@gmail.comXiem Hoang Vanxiemhoang@vnu.edu.vnTrieu Duong Dinhduongdt@vnu.edu.vnTien Vu Huulthavnu@gmail.comHa Le thanhlthavnu@gmail.com2018-10-29T04:29:21Z2018-10-29T04:29:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3128This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31282018-10-29T04:29:21ZAnalysis of air pollution over Hanoi, Vietnam using multi-satellite and MERRA reanalysis datasetsAir pollution is one of the major environmental concerns in Vietnam. In this study, we assess the current status of air pollution over Hanoi, Vietnam using multiple different satellite datasets and weather information, and assess the potential to capture rice residue burning emissions with satellite data in a cloud-covered region. We used a timeseries of Ozone Monitoring Instrument (OMI) Ultraviolet Aerosol Index (UVAI) satellite data to characterize absorbing aerosols related to biomass burning. We also tested a timeseries of 3-hourly MERRA-2 reanalysis Black Carbon (BC) concentration data for 5 years from 2012–2016 and explored pollution trends over time. We then used MODIS active fires, and synoptic wind patterns to attribute variability in Hanoi pollution to different sources. Because Hanoi is within the Red River Delta where rice residue burning is prominent, we explored trends to see if the residue burning signal is evident in the UVAI or BC data. Further, as the region experiences monsoon-influenced rainfall patterns, we adjusted the BC data based on daily rainfall amounts. Results indicated forest biomass burning from Northwest Vietnam and Laos impacts Hanoi air quality during the peak UVAI months of March and April. Whereas, during local rice residue burning months of June and October, no increase in UVAI is observed, with slight BC increase in October only. During the peak BC months of December and January, wind patterns indicated pollutant transport from southern China megacity areas. Results also indicated severe pollution episodes during December 2013 and January 2014. We observed significantly higher BC concentrations during nighttime than daytime with peaks generally between 2130 and 0030 local time. Our results highlight the need for better air pollution monitoring systems to capture episodic pollution events and their surface-level impacts, such as rice residue burning in cloud-prone regions in general and Hanoi, Vietnam in particular.Kristofer LaskoKrishna Prasad VadrevuThi Nhat Thanh Nguyenthanhntn@vnu.edu.vn2018-10-09T09:52:28Z2018-10-09T09:52:28Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3077This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30772018-10-09T09:52:28ZNew approach to investigate nonlinear dynamic response of sandwich auxetic double curves shallow shells using TSDTNonlinear dynamic behavior of double curved shallow shells with negative Poisson’s ratios in auxetic honeycombs on elastic foundations subjected blast, mechanical and damping loads is investigated in the present article. This study considers double curved shallow shells with auxetic core which have three layers in which the top and the bottom outer skins are isotropic aluminum materials; the central layer has honeycomb structure using the same aluminum material. Based on the analytical solution, Reddy’s third order shear deformation theory (TSDT) with the geometrical nonlinear in von Karman and Airy stress functions method, Galerkin method and the fourth-order Runge-Kutta method, the resulting equations are solved to obtain expressions for nonlinear motion equations. The effects of geometrical parameters, material properties, elastic foundations, imperfections, blast loads, mechanical and damping loads on the nonlinear dynamic analysis of double curved shallow shells with negative Poisson’s ratios in auxetic honeycombs are studied.Hong Cong PhamDuy Khanh NguyenDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T09:49:56Z2018-10-09T09:49:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3080This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30802018-10-09T09:49:56ZAn approach to modeling and estimating power consumption of mobile applicationsHong Anh Lelehonganh@humg.edu.vnAnh Tu BuiNinh Thuan Truongthuantn@vnu.edu.vn2018-10-09T09:49:07Z2018-10-09T09:49:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3081This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30812018-10-09T09:49:07ZPreservation of Class invariants in refactoring UML modelsThi Huong Daohuongdt.di12@vnu.edu.vnXuan Truong Nguyennguyenxuantruong@vov.org.vnNinh Thuan Truongthuantn@vnu.edu.vn2018-10-09T09:45:32Z2018-10-09T09:45:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3082This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30822018-10-09T09:45:32ZAn analytical approach on nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by carbon nanotubesThis work presents the nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by single-walled carbon nanotubes resting on elastic foundations based on the higher order shear deformation theory with geometrical nonlinearity in von Karman–Donnell sense. The composite shells are made of various amorphous polymer matrices: poly(methyl methacrylate) (PMMA) and poly{(m-phenylenevinylene)-co-[(2,5-dioctoxy-p-phenylene) vinylene]} (PmPV). The governing equations are solved by the Galerkin method and Airy's stress function to achieve mechanical and thermal post-buckling behaviors of nanocomposite double-curved shallow shells. Various types of distributions of carbon nanotubes, both uniform distributions, and functionally graded distributions are examined. The material properties of nanocomposite double-curved shallow shells are assumed to be temperature dependent. Detailed parametric studies are carried out on the effect of various types of distribution and volume fractions of carbon nanotubes, temperature increments, elastic foundations, edge to radius and edge to thickness ratios on the nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by CNTs.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Nguyen Phamnguyenpd@vnu.edu.vnHuy Cuong NguyenVan Sy NguyenDinh Khoa Nguyen2018-10-09T08:59:16Z2018-10-09T08:59:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3075This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30752018-10-09T08:59:16ZValidation simulation for free vibration and buckling of cracked Mindlin plates using phase-field methodThis article focus on validation phase-field method for simulation of free vibration and buckling of crack plates. The formula is derived from using Reissner-Mindlin plate theory. Validation simulation is carried out by numerically investigating free vibration and buckling of cracked plate with taking the configuration, material property, crack location, and other relevant assumptions as the same with the comparing references. The article shows that phase-field approach can be used to estimate the critical buckling load and frequencies of vibration mode. The article also demonstrates the significant advanced of phase-field method for plates with complex crack geometries.Hong Duc Doandoan.hd.amsl.eng@vnu.edu.vnVan Thom DoMinh Phuc PhanDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:57:38Z2018-10-09T08:57:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3074This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30742018-10-09T08:57:38ZNonlinear buckling and post-buckling of FGM shear deformable truncated conical shells reinforced by FGM stiffenersQuang Chan DoDo Long VuDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:56:42Z2018-10-09T08:56:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3073This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30732018-10-09T08:56:42ZNonlinear thermo-mechanical buckling and post-buckling response of porous FGM plates using Reddy’s HSDTThis work presents an analytical approach to investigate buckling and post-buckling behavior of FGM plate with porosities resting on elastic foundations and subjected to mechanical, thermal and thermomechanical loads. The formulations are based on Reddy's higher-order shear deformation plate theory taking into consideration Von Karman nonlinearity, initial geometrical imperfections, and Pasternak type of elastic foundations. By applying Galerkin method, closed-form relations of buckling loads and post-buckling equilibrium paths for simply supported plates are determined. Numerical results are carried out to show the effects of porosity distribution characteristics (Porosity-I and Porosity-II), geometrical parameters, material properties and elastic foundations on the mechanical, thermal and thermomechanical buckling loads and post-buckling resistance capacity of the porous FGM plates.Hong Cong PhamMinh Chien TrinhDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:54:17Z2018-10-09T08:54:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3070This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30702018-10-09T08:54:17ZNonlinear dynamic analysis and vibration of eccentrically stiffened S-FGM elliptical cylindrical shells surrounded on elastic foundations in thermal environmentsElliptical cylindrical shell is one of shells with special shape. Up to date, there is no publication on vibration and dynamic of functionally graded elliptical cylindrical shells. Therefore, the purpose of the present study is to investigate the nonlinear dynamic response and vibration of imperfect eccentrically stiffness functionally graded elliptical cylindrical shells on elastic foundations using both the classical shell theory (CST) and Airy stress functions method with motion equations using Volmir's assumption. The material properties are assumed to be temperature - dependent and graded in the thickness direction according to a Sigmoid power law distribution (S-FGM). The S-FGM elliptical cylindrical shell with metal-ceramic-metal layers are reinforced by outside metal stiffeners. Both the S-FGM elliptical shell and metal stiffeners are assumed to be in thermal environment and both of them are deformed under temperature simultaneously. Two cases of thermal loading (uniform temperature rise and temperature variation through thickness) are considered. The nonlinear motion equations are solved by Galerkin method and Runge-Kutta method (nonlinear dynamic response, natural frequencies). The effects of geometrical parameters, material properties, elastic foundations Winkler and Pasternak, the nonlinear dynamic analysis and nonlinear vibration of the elliptical cylindrical shells are studied. The some obtained results are validated by comparing with those in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Nguyen Phamnguyenpd@vnu.edu.vnDinh Khoa Nguyen2018-10-09T08:52:59Z2018-10-09T08:52:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3061This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30612018-10-09T08:52:59ZA static buckling investigation of multi-cracked FGM plate based phase-field method coupling the new TSDTDinh Duc Nguyenducnd@vnu.edu.vnHong Duc DoanVan Thom DoDuc Truong Trinh2018-10-09T08:49:41Z2018-10-09T08:49:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3059This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30592018-10-09T08:49:41ZVibration and nonlinear dynamic response of eccentrically stiffened functionally graded composite truncated conical shells in thermal environmentsQuang Chan DoThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:46:04Z2018-10-09T08:46:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3065This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30652018-10-09T08:46:04ZGeometrically nonlinear dynamic response and vibration of shear deformable eccentrically stiffened FGM cylindrical panels subjected to thermal, mechanical and blast loadsBased on the first order shear deformation shell theory, this paper presents an analysis of the nonlinear dynamic response and vibration of imperfect eccentrically stiffened functionally graded material (ES-FGM) cylindrical panels subjected to mechanical, thermal, and blast loads resting on elastic foundations. The material properties are assumed to be temperature-dependent and graded in the thickness direction according to simple power-law distribution in terms of the volume fractions of the constituents. Both functionally graded material cylindrical panels and stiffeners having temperature-dependent properties are deformed under temperature, simultaneously. Numerical results for the dynamic response of the imperfect ES-FGM cylindrical panels with two cases of boundary conditions are obtained by the Galerkin method and fourth-order Runge–Kutta method. The results show the effects of geometrical parameters, material properties, imperfections, mechanical and blast loads, temperature, elastic foundations and boundary conditions on the nonlinear dynamic response of the imperfect ES-FGM cylindrical panels. The obtained numerical results are validated by comparing with other results reported in the open literature.Dinh Duc Nguyenducnd@vnu.edu.vnDuc Tuan NgoHong Cong PhamDinh Dat NgoDinh Khoa Nguyen2018-10-09T08:45:54Z2018-10-09T08:45:54Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3063This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30632018-10-09T08:45:54ZNonlinear response and buckling analysis of eccentrically stiffened FGM toroidal shell segments in thermal environmentThis paper presents an analytical approach to study nonlinear response and buckling analysis of FGM toroidal shell segments reinforced by FGM stiffeners surrounded by elastic foundations in thermal environment and under external pressure. The formulations are based on Reddy's third-order shear deformation shell theory (TSDT) with von Karman nonlinearity, Pasternak type elastic foundations and smeared stiffener technique. By applying Galerkin's method and using stress function, closed-form expressions for determining the static critical external pressure load and postbuckling load–deflection curves are determined. Finally, the influences of geometrical parameters, volume fraction index, elastic foundations, and the effectiveness of stiffeners on the stability of shells are considered.Vuong Pham MinhDuc Nguyen Dinh2018-10-01T04:19:03Z2018-10-01T04:19:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3066This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30662018-10-01T04:19:03ZThe stability of cracked rectangular plate with variable thickness using phase field methodThis study focuses on the investigation of the stability in a rectangular FGM plate with central crack. The plate thickness is changed linearly following the length of the plate. Using the Reissner-Mindlin first order shear deformation theory (FSDT), phase field theory and finite element method (FEM), the stability of fracture of the plate is determined. In order to ensure the reliability of the study, the obtained numerical results in this paper are compared with results reported in other publications. The work also presents the analysis of critical buckling computation for plate that have variation in thickness, the length of the crack on plate as well as the inclined angle of the crack. The numerical results show that the crack length impacts significantly to the critical buckling values of the plate, whereas the impact of inclined angle is less.Minh Phuc PhamVan Thom DoHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2018-10-01T03:59:43Z2018-10-01T03:59:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3064This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30642018-10-01T03:59:43ZNew approach to investigate the nonlinear dynamic response and vibration of a functionally graded multilayer graphene nanocomposite plate on a viscoelastic Pasternak medium in a thermal environmentThis paper presents an analytical approach to investigate the nonlinear dynamic response and vibration of functionally graded multilayer nanocomposite plates reinforced with a low content of graphene platelets (GPLs) using first-order shear deformation theory and a stress function with full motion equations (not using Volmir’s assumptions). The weight fraction of GPL nanofillers is assumed to be constant in each individual GPL-reinforced composite (GPLRC). The modified Halpin–Tsai micromechanics model that takes into account the GPL geometry effect is adopted to estimate the effective Young’s modulus of the GPLRC layers. The plate is assumed to rest on a viscoelastic Pasternak medium and to be subjected to dynamic mechanical load in a thermal environment. Numerical results for the nonlinear dynamic response and vibration of functionally graded (FG) multilayer GPLRC plates are obtained by the Runge–Kutta method. The results show the influences of the GPL distribution pattern, weight fraction, geometry, foundation models, mechanical and temperature loads on the nonlinear dynamic response and vibration, natural frequencies and frequency–amplitude curves of FG multilayer GPLRC plates.Hong Cong PhamDinh Duc Nguyenducnd@vnu.edu.vn2018-09-21T04:20:50Z2018-09-21T04:20:50Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3054This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30542018-09-21T04:20:50ZHighly Accurate Step Counting at Various Walking States Using Low-Cost Inertial Measurement Unit Support Indoor Positioning SystemAccurate step counting is essential for indoor positioning, health monitoring systems, and other indoor positioning services. There are several publications and commercial applications in step counting. Nevertheless, over-counting, under-counting, and false walking problems are still encountered in these methods. In this paper, we propose to develop a highly accurate step counting method to solve these limitations by proposing four features: Minimal peak distance, minimal peak prominence, dynamic thresholding, and vibration elimination, and these features are adaptive with the user’s states. Our proposed features are combined with periodicity and similarity features to solve false walking problem. The proposed method shows a significant improvement of 99.42% and 96.47% of the average of accuracy in free walking and false walking problems, respectively, on our datasets. Furthermore, our proposed method also achieves the average accuracy of 97.04% on public datasets and better accuracy in comparison with three commercial step counting applications: Pedometer and Weight Loss Coach installed on Lenovo P780, Health apps in iPhone 5s (iOS 10.3.3), and S-health in Samsung Galaxy S5 (Android 6.01).Thanh Pham Vanphamvanthanh1209@gmail.comAnh Nguyen Ducanhnd@gmail.comDinh Dang Nhudangnhu@gmail.comHai Pham Honghonghaipham.bk@gmail.comAn Tran Vanantv79@gmail.comKumbesan Sandrasegarankumbesan.sandrasegaran@uts.edu.auTan Tran Ductantd@vnu.edu.vn2018-09-08T09:51:30Z2018-09-08T09:51:30Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3046This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30462018-09-08T09:51:30ZQuantification of non-rigid liver deformation in radiofrequency ablation interventions using image registrationMulti-modal image fusion for image guidance in minimally invasive liver interventions generally requires a registration of pre-operatively acquired images to interventional images of the patient. Whereas rigid registration approaches are fast and can be used in an interventional setting, the actual liver deformation may be non-rigid. The purpose of this paper is to assess the magnitude of non-rigid deformation of the liver between pre-operative and interventional CT images in case of tumor ablations, over the full liver and over parts of the liver that match the volumes typically imaged by a 3D ultrasound transducer. We acquired 3D abdominal CT scans of 38 patients that underwent radiofrequency ablation of liver tumors, pre-operative CT images as well as intra-operative CT images. To determine the magnitude of liver deformation due to pose changes and respiration, we non-rigidly registered the pre-operative CT scan to the intra-operative CT scan. By fitting this deformation to a rigid transformation in a region of interest and computing the residual displacements, the non-rigid deformation part can be quantified. We performed quantifications over the complete liver, as well as for two volumes of interest representative for sub-xiphoidal and inter-costal 3D ultrasound acquisitions. The results showed that a substantial amount of non-rigid deformation was found, and rotation of patient's pose and deep inhalation caused significant liver deformation. Hence we concluded that non-rigid motion correction in the interventions should be taken into account.Ha Luu Manhhalm@vnu.edu.vnAdriaan Moelkera.moelker@erasmusmc.nlStefan Kleins.klein@erasmusmc.nlWiro Niessenw.niessen@erasmusmc.nlTheo van Walsumt.vanwalsum@erasmusmc.nl2018-09-07T05:19:47Z2018-09-07T05:19:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3050This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30502018-09-07T05:19:47ZComplex Shear Modulus Estimation using Integration of LMS/AHI AlgorithmElasticity and viscosity of tissues are two important
parameters that can be used to investigate the structure of tissues,especially detecting tumors. By using a force excitation, the shear wave speed is acquired to extract its amplitude and phase. This information is then used directly or indirectly to compute the Complex Shear Modulus (CSM consists of elasticity and viscosity). Among these methods, Algebraic Helmholtz Inversion (AHI) algorithm can be combined with the Finite Difference Time
Domain (FDTD) model to estimate CSM effectively. However, this algorithm is strongly affected by measured noise while acquiring the particle velocity. Thus, we proposed a LMS/AHI algorithm which can estimate correctly CSM. A simulation scenario is built to confirm the performance of the proposed LMS/AHI algorithm with average error of 3:14%.Hai Luong Quangluonghai@gmail.comCuong Nguyen Manhcuongnm@gmail.comLong Ton Thatttlong@hcmiu.edu.vnTan Tran Ductantd@vnu.edu.vn2018-08-28T08:35:14Z2018-08-28T08:35:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3048This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30482018-08-28T08:35:14ZDevelopment of a Real-Time, Simple and High-Accuracy Fall Detection System for Elderly Using 3-DOF AccelerometersFalls represent a major problem for the elderly people aged 60 or above. There are many monitoring systems which are currently available to detect the fall. However, there is a great need to propose a system which is of optimal effectiveness. In this paper, we propose to develop a low-cost fall detection system to precisely detect an event when an elderly person accidentally falls. The fall detection algorithm compares the acceleration with lower fall threshold and upper fall threshold values to accurately detect a fall event. The post-fall recognition module is the combination of posture recognition and vertical velocity estimation that has been added to our proposed method to enhance the performance and accuracy. In case of a fall, our device will transmit the location information to the contacts instantly via SMS and voice call. A smartphone application will ensure that the notifications are delivered to the elderly person's relatives so that medical attention can be provided with minimal delay. The system was tested by volunteers and achieved 100% sensitivity and accuracy. This was confirmed by testing with public datasets and it also achieved the same percentage in sensitivity and accuracy as in our recorded datasets.Van Thanh Phamphamvanthanh1209@gmail.comDuc Tan Trantantd@vnu.edu.vnDinh Chinh Nguyenchinhnd@vnu.edu.vnDuc Anh Nguyenanhnd@gmail.comNhu Dinh Dangdangnhu@gmail.comEl-Rabaie El-Sayed Mahmoudsrabie1@yahoo.comKumbesan Sandrasegarankumbesan.sandrasegaran@uts.edu.au2018-06-18T07:54:20Z2018-06-18T07:54:20Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2998This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29982018-06-18T07:54:20ZSolution-processed CuO thin films with various Cu2+ ion concentrationsPresented herein is a report on cupric oxide (CuO) thin films prepared on glass substrates by using a solution process with varying nominal concentrations of Cu2+ ions at 0.15 M, 0.20 M, and 0.25 M. X-ray diffraction patterns and scanning electron microscopy (SEM) micrographs were analyzed to evaluate the crystalline structure and surface morphology of the CuO thin films. The fabricated CuO thin films exhibited a single-phased monoclinic structure with (200) and (111) orientations. The grain size of the CuO thin films was observed to increase with higher concentration, by SEM observation. The electrical and optical properties of the CuO thin films were investigated using a four-probe measurement system and UV/VIS spectrometer, respectively. The thin films showed a minimum resistivity of 0.085 Ωcm corresponding to the 0.25 M concentration, and a bandgap energy ranging from 2.10 eV to 2.15 eV. In addition, the light-harvesting ability of CuO thin films was considered by the absorption figure of merit (a-FOM), in correlation with the global solar spectrum. A maximum a-FOM value of 12.79 Ω-1cm-1 was attained for the sample with a Cu2+ ion concentration of 0.25 M.Quang Hoa NguyenVan Dung NguyenAkihiko FujiwaraNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vn2018-06-13T09:38:51Z2018-06-13T09:38:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3013This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30132018-06-13T09:38:51ZVortex flow generator utilizing synthetic jets by diaphragm vibrationThis paper develops a millimeter scale fully packaged device in which a vortex flow of high velocity is generated inside a chamber. Under the actuation by a lead zirconate titanate (PZT) diaphragm, a flow circulates with increasing velocity after each actuating circle to form a vortex in a cavity named as the vortex chamber. At each cycle, the vibration of the PZT diaphragm creates a small net air flow through a rectifying nozzle, generates a synthetic jet which propagates by a gradual circulation toward the vortex chamber and then backward the feedback chamber. The design of such device is firstly conducted by a numerical analysis whose results are considered as the base of our experimental set-up. A vortex flow generated in the votex chamber was observed by a high-speed camera. The present approach which was illustrated by both the simulation and experiment is potential in various applications related to the inertial sensing, fluidic amplifier and micro/nano particle trapping and mixing.Van Thanh Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpThanh Tung Buitungbt@vnu.edu.vnCanh-Dung TranCanh-Dung.Tran@usq.edu.au2018-06-13T09:38:32Z2018-06-13T09:38:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3012This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30122018-06-13T09:38:32ZTri-axis convective accelerometer with closed-loop heat sourceIn this paper, we report the details and findings of a study on tri-axis convective accelerometer, which is designed with the closed-loop type heat source and thermal sensing hotwire elements. The closed-loop heat source enhances the convective flow to the central part where a hotwire is placed to measure the vertical component of acceleration. The simulation was conducted using numerical analysis, and the device was prototyped by additive manufacturing. The device, functioning as a tilt sensor and an accelerometer, was tested up to acceleration of 20 g. The experiments were successfully conducted and the experimental results agreed reasonably with those obtained by numerical analysis. The results demonstrated that the closed-loop heat source could reduce the cross effect between the acceleration components. The scale factor and cross-sensitivity had the values of 0.26 uV/g and 1.2%, respectively. The cross-sensitivity and the effects of heating power were also investigated in this study.Van Thanh Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpLam Bao Danglambao@gmail.comCanh-Dung TranCanh-Dung.Tran@usq.edu.auThanh Tung Buitungbt@vnu.edu.vnHoa Thanh Phanhoathanh@gmail.com2018-06-13T09:38:14Z2018-06-13T09:38:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3011This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30112018-06-13T09:38:14ZA study of angular rate sensing by corona discharge ion windWe report an application of ion wind in angular rate sensing. A new design of a jet flow gyroscope using ion wind corona discharge is developed by conducting a numerical simulation and then an experimental analysis with regard to the advantages of a corona-discharge-based jet flow. Ion wind is generated by applying a high-voltage between a pin, as the discharge electrode, and a ring, as the reference electrode. The current-voltage characteristics of the discharge process by experimental works is set up as the boundary condition to describe the ion wind flow in the numerical simulation. A jet flow of ion wind is observed through an experiment and a simulation. When the gyroscope is subjected to an angular rate, the induced Coriolis force deflects the ion wind. This deflection is detected using four hotwires installed downstream of the working chamber behind the reference electrode. The experimental result show that the angular rate can be detected with a sensitivity of 4.7 uV/o/s. Because ion wind can be generated with minimum power and does not require any vibrating components, the device is robust, consumes low power, and is cost-effective.Van Thanh Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpCanh-Dung TranCanh-Dung.Tran@usq.edu.auThanh Tung Buitungbt@vnu.edu.vnHoa Thanh Phanhoathanh@gmail.com2018-06-13T09:37:58Z2018-06-13T09:37:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3009This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30092018-06-13T09:37:58ZDual-pin electrohydrodynamic generator driven by alternating currentWe report a unique alternating current (AC) driven corona based air-flow generator using symmetrically arranged electrodes. Unlike the conventional configuration where one electrode generates charged ions moving towards the reference electrode, this configuration allows both negative and positive charges to simultaneously move away from the device and generate ion wind in parallel with the electrodes. In comparison with the direct current (DC) driven corona generator, the time oscillating AC field allows the device a better stabilization owing to the independence of ion wind strength from the inter-electrode spacing. Our results by both simulation and experiment showed that when the AC frequency exceeds a threshold value of 1100 Hz, the electric field at the electrode tips is determined dominantly by the charge cloud created in the previous half-cycle, resulting in stronger net electric field and thus stronger ion wind. In addition, the electrode separation in the AC driven corona based generator is less critical above the frequency threshold, yielding a more robust design with minimized susceptibility to manufacturing tolerances and impurities on the electrodes. Moreover, lower voltage levels of the AC driven system allow simpler and more economical design in the high voltage circuit of the AC generator.Van Thanh Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpCanh-Dung TranCanh-Dung.Tran@usq.edu.auTibor Terebessytibor.terebessy@clearviewtraffic.comThanh Tung Buitungbt@vnu.edu.vn2018-06-08T08:52:34Z2018-06-08T08:52:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2970This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29702018-06-08T08:52:34ZD3NER: Biomedical named entity recognition using CRF-biLSTM improved with fine-tuned embeddings of various linguistic informationThanh Hai Danghai.dang@vnu.edu.vnHoang Quynh Lelhquynh@gmail.comMinh Trang NguyenTien Sinh Vu2018-06-08T08:51:26Z2018-06-08T08:51:26Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2979This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29792018-06-08T08:51:26ZExploiting User Posts for Web Document SummarizationRelevant user posts such as comments or tweets of a Web document provide additional valuable information to enrich the content of this document. When creating user posts, readers tend to borrow salient words or phrases in sentences. This can be considered as word variation. This paper proposes a framework which models the word variation aspect to enhance the quality of Web document summarization. Technically, the framework consists of two steps: scoring and selection. In the first step, the social information of a Web document such as user posts is exploited to model intra-relations and inter-relations in lexical and semantic levels. These relations are denoted by a mutual reinforcement similarity graph used to score each sentence and user post. After scoring, summaries are extracted by using a ranking approach or concept-based method formulated in the form of Integer Linear Programming. To confirm the efficiency of our framework, sentence and story highlight extraction tasks were taken as a case study on three datasets in two languages, English and Vietnamese. Experimental results show that: (i) the framework can improve ROUGE-scores compared to state-of-the-art baselines of social context summarization and (ii) the combination of the two relations benefits the sentence extraction of single Web documents.Minh Tien Nguyentiennm@jaist.ac.jpDuc Vu Tranvu.tran@jaist.ac.jpLe Minh Nguyennguyenml@jaist.ac.jpXuan Hieu Phanhieupx@vnu.edu.vn2018-06-08T08:40:05Z2018-06-08T08:40:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2972This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29722018-06-08T08:40:05ZA compact microfluidic chip with integrated impedance biosensor for protein preconcentration and detectionIn this study, a low-cost, compact biochip is designed and fabricated for protein detection. Nanofractures formed by self-assembled gold nanoparticles at junction gaps are applied for ion enrichment and depletion to create a trapping zone when electroosmotic flow occurs in microchannels. An impedance measurement module is implemented based on the lock-in amplifier technique to measure the impedance change during antibody growth on the gold electrodes which is caused by trapped proteins in the detection region. The impedance measurement results confirm the presence of trapped proteins. Distinguishable impedance profiles, measured at frequencies in the range of 10–100 kHz, for the detection area taken before and after the presence of proteins validate the performance of the proposed system.Tuan Vu Quocvqtuan0211@gmail.comMeng-Syuan WuMeng-Syuan@gmail.comTung Thanh Buitungbt@vnu.edu.vnDuc Trinh Chutrinhcd@vnu.edu.vnChun-Ping JenChun-Ping@gmail.com2018-06-08T08:39:14Z2018-06-08T08:39:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2971This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29712018-06-08T08:39:14ZFluidic Platform with Embedded Differential Capacitively Coupled Contactless Conductivity Detector for Micro-Object SensingIn this paper, we present a microfluidic platform with differential capacitively coupled contactless conductivity detection (DC4D) technique for microparticle detection. The microfluidic platform is formed by bonding PDMS channel to glass substrate. The proposed microfluidic sensor embedded in the microchannel consists of three adjacent electrodes. These electrodes are arranged to form differential coplanar capacitor structures to provide high sensitivity. The differential capacitance is changed when a microsized object crosses the sensing area in the microfluidic channel. This microfluidic system with the novel sensing design based on DC4D technique provides a platform for detection the presence of an object as well as its electrical property.Loc Quang Dolocdq@hus.edu.vnTung Thanh Buitungbt@vnu.edu.vnHa Thi Thuy Tranthuyhadt@gmail.comKikuchi Katsuyak.kikuchi@aist.go.jpAasahiro Aoyagim-aoyagi@aist.go.jpDuc Trinh Chutrinhcd@vnu.edu.vn2018-06-07T07:02:07Z2018-06-07T07:02:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2959This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29592018-06-07T07:02:07ZAn Efficient Parallel Method for Optimizing Concurrent Operations on Social NetworksThis paper presents our approach to optimize the performance of both reading and writing concurrent operations on large-scale social network. Here, we focus on the directed, unweighted relationships among members in a social network. It can then be illustrated as a directed, unweighted graph. And determining the relationship between any two members is similar to finding the shortest path between two vertices. With such a large-scale dynamic social network, we face the problem of having concurrent operations from adding or removing edges dynamically while one may ask to determine the relationship between two members. To solve this issue, we propose an efficient parallel method based on (i) utilizing an appropriate data structure, (ii) parallelizing the updating actions and (iii) improving the performance of query processing by both reducing the searching space and computing in multi-threaded parallel. Our method was validated by the datasets from SigMod Contest 2016 and SNAP DataSet Collections with good experimental results compared to other solutionsPhuong Hanh Duhanhdp@vnu.edu.vnHai Dang Phamdangph@vnu.edu.vnNgoc Hoa Nguyenhoa.nguyen@vnu.edu.vn2018-06-07T07:01:43Z2018-06-07T07:01:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2958This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29582018-06-07T07:01:43ZUnearthing new genomic markers of drug response by improved measurement of discriminative powerOncology drugs are only effective in a small proportion of cancer patients. Our current ability to identify these responsive patients before treatment is still poor in most cases. Thus, there is a pressing need to discover response markers for marketed and research oncology drugs. Screening these drugs against a large panel of cancer cell lines has led to the discovery of new genomic markers of in vitro drug response. However, while the identification of such markers among thousands of candidate drug-gene associations in the data is error-prone, an appraisal of the effectiveness of such detection task is currently lacking.Cao Cuong Dangcuongdc@vnu.edu.vnAntonio PeónPedro Ballester2018-06-01T03:49:04Z2018-06-01T03:49:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2955This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29552018-06-01T03:49:04ZMPBoot: fast phylogenetic maximum parsimony tree inference and bootstrap approximationBACKGROUND:
The nonparametric bootstrap is widely used to measure the branch support of phylogenetic trees. However, bootstrapping is computationally expensive and remains a bottleneck in phylogenetic analyses. Recently, an ultrafast bootstrap approximation (UFBoot) approach was proposed for maximum likelihood analyses. However, such an approach is still missing for maximum parsimony.
RESULTS:
To close this gap we present MPBoot, an adaptation and extension of UFBoot to compute branch supports under the maximum parsimony principle. MPBoot works for both uniform and non-uniform cost matrices. Our analyses on biological DNA and protein showed that under uniform cost matrices, MPBoot runs on average 4.7 (DNA) to 7 times (protein data) (range: 1.2-20.7) faster than the standard parsimony bootstrap implemented in PAUP*; but 1.6 (DNA) to 4.1 times (protein data) slower than the standard bootstrap with a fast search routine in TNT (fast-TNT). However, for non-uniform cost matrices MPBoot is 5 (DNA) to 13 times (protein data) (range:0.3-63.9) faster than fast-TNT. We note that MPBoot achieves better scores more frequently than PAUP* and fast-TNT. However, this effect is less pronounced if an intensive but slower search in TNT is invoked. Moreover, experiments on large-scale simulated data show that while both PAUP* and TNT bootstrap estimates are too conservative, MPBoot bootstrap estimates appear more unbiased.
CONCLUSIONS:
MPBoot provides an efficient alternative to the standard maximum parsimony bootstrap procedure. It shows favorable performance in terms of run time, the capability of finding a maximum parsimony tree, and high bootstrap accuracy on simulated as well as empirical data sets. MPBoot is easy-to-use, open-source and available at http://www.cibiv.at/software/mpboot .Thi Diep Hoangdiepht@vnu.edu.vnSy Vinh Levinhls@vnu.edu.vnTomas FlouriAlexandros StamatakisArndt von HaeselerQuang Minh Bui2018-04-10T06:34:01Z2018-04-10T06:34:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2926This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29262018-04-10T06:34:01Z300-GHz Balanced Varactor Doubler in Silicon CMOS for Ultrahigh-Speed Wireless CommunicationsThis letter presents a 300 GHz transmitter front-end suitable for ultrahigh-speed wireless communications. The transmitter front-end realized in TSMC 40 nm CMOS consists of a varactor based doubler driven by a three-stage D-band power amplifier (PA). Measurement results show that the D-band PA obtains a saturated power of 6.1 dBm and a power added efficiency (PAE) of 4.3%. The balanced varactor doubler results in an output power of -12 dBm at 300 GHz. The transmitter front-end consumes a total DC power of 72.9 mW from a 0.9 V supply voltage while it occupies an area of 0.72 mm2.Tuan Anh Vutanhvu@vnu.edu.vnKyoya Takanokyoya@hiroshima-u.ac.jpMinoru Fujishimafuji@hiroshima-u.ac.jp2018-04-02T03:29:53Z2018-04-02T03:29:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2929This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29292018-04-02T03:29:53ZVehicle Mode and Driving Activity Detection Based on Analyzing Sensor Data of SmartphonesIn this paper, we present a flexible combined system, namely the Vehicle mode-driving Activity Detection System (VADS), that is capable of detecting either the current vehicle mode or the current driving activity of travelers. Our proposed system is designed to be lightweight in computation and very fast in response to the changes of travelers’ vehicle modes or driving events. The vehicle mode detection module is responsible for recognizing both motorized vehicles, such as cars, buses, and motorbikes, and non-motorized ones, for instance, walking, and bikes. It relies only on accelerometer data in order to minimize the energy consumption of smartphones. By contrast, the driving activity detection module uses the data collected from the accelerometer, gyroscope, and magnetometer of a smartphone to detect various driving activities, i.e., stopping, going straight, turning left, and turning right. Furthermore, we propose a method to compute the optimized data window size and the optimized overlapping ratio for each vehicle mode and each driving event from the training datasets. The experimental results show that this strategy significantly increases the overall prediction accuracy. Additionally, numerous experiments are carried out to compare the impact of different feature sets (time domain features, frequency domain features, Hjorth features) as well as the impact of various classification algorithms (Random Forest, Naïve Bayes, Decision tree J48, K Nearest Neighbor, Support Vector Machine) contributing to the prediction accuracy. Our system achieves an average accuracy of 98.33% in detecting the vehicle modes and an average accuracy of 98.95% in recognizing the driving events of motorcyclists when using the Random Forest classifier and a feature set containing time domain features, frequency domain features, and Hjorth features. Moreover, on a public dataset of HTC company in New Taipei, Taiwan, our framework obtains the overall accuracy of 97.33% that is considerably higher than that of the state-of the art.Dang Nhac LuDuc Nhan NguyenThi Hau Nguyennguyenhau@vnu.edu.vnHa Nam Nguyennamnh@vnu.edu.vn2018-02-06T06:47:21Z2018-02-06T06:47:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2920This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29202018-02-06T06:47:21ZQuantitative analysis of COOH-terminated alkanethiol SAMs on gold nanoparticle surfacesSurface-functionalization of a self-assembled monolayer (SAM) can be achieved byintroducing functional molecules
at the terminal. To immobilize biomolecules on a gold
substrate, COOH-terminated alkanethiol SAMs are preferably employed. Thiol molecules adsorption on gold surface was performed using thioglycolic acid (TGA, HS-CH2-COOH) monomers and a self-assembled technique.
Characterization by Fourier transform infrared (FTIR) spectroscopy revealed gold–sulfur (Au–S) bonding through confirming the presence and disappearance of thiol molecules on the Au surface before and after the sample’s immersion in the TGA solution. Moreover, FTIR spectra also proved the presence of carboxyl molecules (C=O; OH) at the free end on the gold nanoparticle (AuNP) surface. Quantitative analysis of the carboxyl molecules interacted with methylene blue (MB) ones, and then identification by UV-Vis absorption spectroscopy showed
that the average density of the carboxyl molecules on the free end of the alkanethiol SAM was about 3.9 × 1014 molecules per cm2
Keywords: Au–S bond, self-assembled monolayer (SAM), thioglycolic acid (TGA), carboxyl molecular densityCường / Kiên Nguyễncuongnk@vnu.edu.vn2018-02-06T06:43:34Z2018-02-06T06:43:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2919This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29192018-02-06T06:43:34ZEffects of nitrogen incorporation on structure of a-C:H films deposited on polycarbonate by plasma CVDNitrogen-incorporated-hydrogenated amorphous carbon (a-C:H:N) films were deposited on polycarbonate (PC) substrates by r.f. plasmaenhanced chemical vapor deposition (PECVD). Effects of nitrogen incorporation on microstructure, bonding states, chemical composition,
internal stresses, and friction coefficients of deposited films were investigated. The films were characterized by X-ray photoelectron microscopy, infrared microscopy (IR), Raman spectroscopy and friction tests. Results from the measurement indicate that incorporated nitrogen content has considerable effects on film properties. Raman spectra of the a-C:H:N films are broad, asymmetric and centered at around wavenumber of 1500 cm-1. Shifting of the G-peak toward the higher wavenumber, narrower bandwidth of the G-peak and an increase of the ID/IG ratio demonstrate the graphitic character of the a-C:H:N films with the further increase of the atomic fraction of nitrogen (N/C). IR spectra demonstrate nitrogen bonded to carbon and hydrogen as CZN, CMN, N–H and C–H bonding configurations in the aC:H:N films. The internal stress considerably decreased as well as the friction coefficient is low when the N/C fraction increased. The surface roughness of the a-C:H:N films estimated by atomic force microscopy (AFM) seems to be less smooth with the increase in the N/C fraction.
Keywords: Nitrogen incorporation; a-C:H:N films; Plasma-enhanced chemical vapor deposition (PECVD); PolycarbonateCường/ Kiên Nguyễncuongnk@vnu.edu.vnM. TaharaN. Yamauchi,T. Sone2018-01-09T03:16:07Z2018-01-09T03:16:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2885This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28852018-01-09T03:16:07ZModelling the helium plasma jet delivery of
reactive species into a 3D cancer tumourCold atmospheric plasmas have attracted significant worldwide attention for their potential beneficial effects in cancer therapy. In order to further improve the effectiveness of plasma in cancer therapy, it is important to understand the generation and transport of plasma reactive species into tissue fluids, tissues and cells, and moreover the rates and depths of delivery,
particularly across physical barriers such as skin. In this study, helium (He) plasma jet treatmentof a 3D cancer tumour, grown on the back of a live mouse, induced apoptosis within the tumour to a depth of 2.8 mm. The He plasma jet was shown to deliver reactive oxygen species through the unbroken skin barrier before penetrating through the entire depth of the tumour. The depth
and rate of transport of He plasma jet generated H2O2, NO3− and NO2−, as well as aqueous oxygen [O2(aq)], was then tracked in an agarose tissue model. This provided an approximation of the H2O2, NO3−, NO2− and O2(aq) concentrations that might have been generated during the
He plasma jet treatment of the 3D tumour. It is proposed that the He plasma jet can induce apoptosis within a tumour by the ‘deep’ delivery of H2O2, NO3− and NO2− coupled with O2(aq); the latter raising oxygen tension in hypoxic tissue.
Keywords: tissue oxygenation, tissue model, plasma jet, hypoxia, hyperbaric medicine, reactive
oxygen species (ROS) and reactive nitrogen species (RNS), cancer therapyJ Szili EndreEndre.Szili@unisa.edu.auOh Jun-SeokHideo FukuharaBhatia RishabGaur NishthaKien Cuong Nguyencuongnk@vnu.edu.vnHong Sung-HaSatsuki ItoKotaro OgawaChiaki KawadaShuin TaroTsuda MasayukiMatsuo FurihataAtsushi KurabayashiFuruta HiroshiMasafumi ItoInoue KeijiHatta AkimitsuShort Robert D2018-01-05T10:01:12Z2018-01-05T10:01:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2598This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25982018-01-05T10:01:12ZThe Impact of Online Learning Activities on Student Learning Outcome in Blended Learning CourseThe aim of the study was to determine the impact of online learning activities to the learning outcomes of students who participated in the blended learning course. Interactive activities are considered, in this study, include teacher - student interaction, student - student interaction, student - content interaction, and student - technology interaction. The undergraduate student participated in the blended learning course which using formative assessment to evaluate student learning outcomes by the combination of different learning activities through a learning management system. The quantitative results obtained when implementing learning analytics data from the system through using regression analysis showed that the students interact effectively with learning activities in the course have better results. Quantitative analytical results indicate that student – student interaction has a greater impact on student learning outcomes. These learning activities used for interactive activities as suggestions for teachers to design and implement learning activities for blended learning coursesViet Anh Nguyenvietanh@vnu.edu.vn2018-01-05T04:08:34Z2018-01-05T04:08:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2903This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/29032018-01-05T04:08:34ZLearning from Multiple Classifier Systems: Perspectives for Improving Decision Making of QSAR Models in Medicinal ChemistryQuantitative Structure - Activity Relationship (QSAR) modeling has been widely used in medicinal chemistry and computational toxicology for many years. Today, as the amount of data on chemicals is increasing dramatically, QSAR methods have become pivotal for the purpose of handling the data, identifying a decision, and gathering useful information from data processing. The advances in this field have paved a way for numerous alternative approaches that require deep mathematics in order to enhance the learning capability of QSAR models. One of these directions is the use of Multiple Classifier Systems (MCSs) that potentially provide a means to exploit the advantages of manifold learning through decomposition frameworks, while improving generalization and predictive performance. In the present paper, we present MCS as a next generation of QSAR modeling techniques and discuss the chance to mining the vast number of models already published in the literature. We systematically revisited the theoretical frameworks of MCS as well as current advances in MCS application for QSAR practice. Furthermore, we illustrate our idea by describing ensemble approaches on modeling histone deacetylase (HDACs) inhibitors. We expect that our analysis would contribute to a better understanding about MCS application and its future perspectives for improving the decision making of QSAR models.The Hai/V PhamHai Nam NguyenViet Nga DoanThanh Hai Danghai.dang@vnu.edu.vnKarel Dieguez-SantanaYovani Marrero-PonceeJuan/A Castillo-GaritGerardo/M Casanola-MartinThi Thu Huong Le2017-12-25T04:17:52Z2017-12-25T04:17:52Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2842This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28422017-12-25T04:17:52ZNew approach to investigate nonlinear dynamic response of
sandwich auxetic double curves shallow shells using TSDTNonlinear dynamic behavior of double curved shallow shells with negative Poisson’s ratios in auxetic honeycombs on elastic foundations subjected blast, mechanical and damping loads is investigated in the present article. This study considers double curved shallow shells with auxetic core which have three layers in which the
top and the bottom outer skins are isotropic aluminum materials; the central layer has honeycomb structure
using the same aluminum material. Based on the analytical solution, Reddy’s third order shear deformation
theory (TSDT) with the geometrical nonlinear in von Karman and Airy stress functions method, Galerkin method
and the fourth-order Runge-Kutta method, the resulting equations are solved to obtain expressions for nonlinear
motion equations. The effects of geometrical parameters, material properties, elastic foundations, imperfections,
blast loads, mechanical and damping loads on the nonlinear dynamic analysis of double curved shallow shells
with negative Poisson’s ratios in auxetic honeycombs are studied.Hong Cong PhamDuy Khanh NguyenDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2017-12-25T04:01:08Z2017-12-25T04:01:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2833This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28332017-12-25T04:01:08ZNonlinear dynamic response and vibration of imperfect shear deformable functionally graded plates subjected to blast and thermal loadsBased on Reddy's higher-order shear deformation plate theory, this article presents an analysis of the nonlinear dynamic response and vibration of imperfect functionally graded material (FGM) thick plates subjected to blast and thermal loads resting on elastic foundations. The material properties are assumed to be temperature-dependent and graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. Numerical results for the dynamic response and vibration of the FGM plates with two cases of boundary conditions are obtained by the Galerkin method and fourth-order Runge–Kutta method. The results show the effects of geometrical parameters, material properties, imperfections, temperature increment, elastic foundations, and boundary conditions on the nonlinear dynamic response and vibration of FGM plates.Dinh Duc Nguyenducnd@vnu.edu.vnDuc Tuan NgoTran PhuongQuoc Quan Tran2017-12-25T04:00:17Z2017-12-25T04:00:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2832This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28322017-12-25T04:00:17ZNonlinear thermal stability of eccentrically stiffened FGM double curved shallow shellsThis article presents analytical solutions for the nonlinear static and dynamic stability of imperfect eccentrically stiffened functionally graded material (FGM) higher order shear deformable double curved shallow shell on elastic foundations in thermal environments. It is assumed that the shell’s properties depend on temperature and change according to the power functions of the shell thickness. The shell is reinforced by the eccentrically longitudinal and transversal stiffeners made of full metal. Equilibrium, motion, and compatibility equations are derived using Reddy’s higher order shear deformation shell theory and taking into account the effects of initial geometric imperfection and the thermal stress in both the shells and stiffeners. The Galerkin method is applied to determine load–deflection and deflection–time curves. For the dynamical response, motion equations are numerically solved using Runge–Kutta method. The nonlinear dynamic critical buckling loads are found according to the criterion suggested by Budiansky–Roth. The influences of inhomogeneous parameters, dimensional parameters, stiffeners, elastic foundations, initial imperfection, and temperature increment on the nonlinear static and dynamic stability of thick FGM double curved shallow shells are discussed in detail. Results for various problems are included to verify the accuracy and eﬃciency of the approach.Quoc Quan TranDinh Duc Nguyenducnd@vnu.edu.vn2017-12-25T03:50:06Z2017-12-25T03:50:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2829This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28292017-12-25T03:50:06ZThermal and mechanical stability of functionally graded carbon nanotubes
(FG CNT)-reinforced composite truncated conical shells surrounded by the
elastic foundationsThe thermal and mechanical stability of a functionally graded composite truncated conical shell reinforced by
carbon nanotube fibers and surrounded by the elastic foundations are studied in this paper. Distribution of
reinforcements across the shell thickness is assumed to be uniform or functionally graded. The equilibrium and
linearized stability equations for the shells are derived based on the classical shell theory. Using Galerkin
method, the closed – form expression for determining the linear thermal and mechanical buckling load is
obtained. The paper also analyzed and discussed the effects of semi-vertex angle, shell length, volume fraction of
fibers, distribution pattern of fibers, temperature, elastic foundations on the linear thermal and mechanical
buckling loads of the functionally graded carbon nanotube fibers-reinforced composite (FG CNTRC) truncated
conical shell in thermal environment.Dinh Duc Nguyenducnd@vnu.edu.vnHong Cong PhamDuc Tuan NgoTran PhuongVan Thanh Nguyen2017-12-25T03:49:20Z2017-12-25T03:49:20Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2828This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28282017-12-25T03:49:20ZConstitutive modeling of cyclic plasticity deformation and low–high-cycle fatigue of stainless steel 304 in uniaxial stress stateFor constructing a theory that adequately describes the effects of cycling loading, we initially analyze an experimental plastic hysteresis loop of the stainless steel SS304 and allocate on it three backstress types responsible for yield surface center displacement. Evolutionary equations per each backstresses type are formulated based on the equation of plasticity flow theory at combined (isotropic-kinematic) hardening. Material functions (parameters) closing the theory are defined, and basic experiment and identification methods of material function are formulated. Comparison of design results and experiments testifies their reliable compatibility.Valentin S. BondarVladimir V. DansinLong D.VuDinh Duc Nguyenducnd@vnu.edu.vn2017-12-25T03:48:53Z2017-12-25T03:48:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2827This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28272017-12-25T03:48:53ZNonlinear buckling and postbuckling of imperfect piezoelectric S-FGM circular cylindrical shells with metal–ceramic–metal layers in thermal environment using Reddy's third-order shear deformation shell theoryBased on Reddy's third-order shear deformation shell theory, this paper studied the nonlinear buckling and postbuckling response of imperfect Sigmoid functionally graded circular cylindrical shells in a thermal environment with an outer surface-bonded piezoelectric actuator. Material properties are temperature dependent and graded in the thickness direction with two shell's outer surfaces rich of metal and ceramic in the middle (S-FGM). The shell is subjected to uniform external pressure, axial compressive, electrical loads and resting on elastic foundations. The obtained numerical results are validated by comparing with other results reported in the open literature.Dinh Khoa NguyenThi Thiem HoangDinh Duc Nguyenducnd@vnu.edu.vn2017-12-25T03:48:24Z2017-12-25T07:21:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2826This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28262017-12-25T03:48:24ZNonlinear thermo-mechanical response of eccentrically stiffened Sigmoid FGM circular cylindrical shells subjected to compressive and uniform radial loads using the Reddy's third-order shear deformation shell theoryBased on Reddy's third-order shear deformation shell theory, this paper presents an analytical approach to investigate the nonlinear thermo-mechanical response of imperfect Sigmoid FGM circular cylindrical shells surrounded on elastic foundations and reinforced by outside metal stiffeners. The eccentrically stiffened S-FGM shells are subjected to axial compressive load and uniform radial load in thermal environment. Using the stress function, Bubnov–Galerkin method, the paper proposes the formula for forces and moments taking into account the thermal stress in both the shells and stiffeners. The obtained results are validated by comparing with other results reported in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Khoa NguyenThi Thiem Hoang2017-12-25T03:48:08Z2017-12-25T03:48:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2825This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28252017-12-25T03:48:08ZThermomechanical buckling and post-buckling of cylindrical shell with functionally graded coatings and reinforced by stringersThe cylindrical shells reinforced by stringers have been widely used in modern engineering structures such as storage tanks, missile, submarine hull, oil-transmitting pipeline, etc. In this present article, the thermomechanical buckling and post-buckling behaviors of a cylindrical shell with functionally graded (FG) coatings are investigated by an analytical approach. The cylindrical shell is reinforced by outside stringers under torsional load in the thermal environment. The layers of FG coatings are assumed to be made by functionally graded materials (FGMS) combining of ceramic and metal phases and the core of the shell is made from homogeneous material. The classical shell theory based on the von-Karman assumptions is used to model the thin cylindrical shell. Using Galerkin's procedure and Airy stress function, the governing equations can be solved to obtain the closed-form solution for the critical buckling load and postbuckling load-deflection curves of simply supported shells. Moreover, many important parametric studies of stringers, temperature field, material volume fraction index, the thickness of metal layer, etc. are taken into investigation. According to numerical examples, it is revealed that the outside strings have considerably impact on thermomechanical buckling and postbuckling behaviors of the shells.Toan Thang PhamDinh Duc Nguyenducnd@vnu.edu.vnThoi Trung Nguyen2017-12-25T03:47:31Z2017-12-25T03:47:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2824This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28242017-12-25T03:47:31ZNonlinear dynamic response and vibration of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) shear deformable plates with temperature dependence material properties and surrounded on elastic foundationsBased on Reddy’s third-order shear deformation plate theory, the nonlinear dynamic response and vibration of imperfect functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plates on elastic foundations subjected to dynamic loads and temperature are presented. The plates are reinforced by single-walled carbon nanotubes which vary according to the linear functions of the plate thickness. The plate’s effective material properties are assumed to depend on temperature and estimated through the rule of mixture. By applying the Airy stress function, Galerkin method and fourth-order Runge–Kutta method, nonlinear dynamic response and natural frequency for imperfect FG-CNTRC plates are determined. In numerical results, the influences of geometrical parameters, elastic foundations, initial imperfection, dynamic loads, temperature increment, and nanotube volume fraction on the nonlinear vibration of FG-CNTRC plates are investigated. The obtained results are validated by comparing with those of other authors.Van Thanh NguyenDinh Khoa NguyenDuc Tuan NgoPhuong TranDinh Duc Nguyenducnd@vnu.edu.vn2017-12-20T04:55:33Z2017-12-20T04:55:33Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2822This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28222017-12-20T04:55:33ZAnalysis of bi-directional functionally graded plates by FEM and a new third-order shear deformation plate theoryonly in one specified direction, but also different other directions. In particular, the bi-directional functionally
graded materials (2D-FGMs) introduced are expected to have more effective properties, consequently eliminating
commonly awkward problems such as local stress concentrations and delamination. In this paper,
buckling and bending behaviors of 2D-FGM plates, which are of great importance in the design and development
of engineering applications, are numerically analyzed by a finite element model. The plate kinematics are described
using a new third-order shear deformation plate theory (TSDT), without the need for special treatment of
shear-locking effect and shear correction factors. The present TSDT theory based on rigorous kinematic of displacements,
which is shown to be dominated over other preceding theories, is derived from an elasticity formulation,
rather by the hypothesis of displacements. The materials are assumed to be graded in two directions
and their effective properties are computed through the rule of mixture. The accuracy of the proposed approach
assessed on numerical results is confirmed by comparing the obtained results with respect to reference published
solutions. The effects of some numerical aspect ratios such as volume fraction, boundary conditions, thickness to
length ratio, etc. on static deflections and critical buckling are numerically studied. The investigation of results
confirms that such aforementioned aspect ratios have significant effects on the mechanical behaviors of plates.Van Thom DoDinh Kien NguyenDinh Duc Nguyenducnd@vnu.edu.vnHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnQuoc Tinh Bui2017-12-20T04:55:12Z2017-12-20T04:55:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2823This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28232017-12-20T04:55:12ZStatic response and free vibration of functionally graded carbon nanotube-reinforced composite rectangular plates resting on Winkler–Pasternak elastic foundationsIn the present article, static response and free vibration of functionally graded carbon nanotube
reinforced composite (FG-CNTRC) rectangular plate resting on Winkler–Pasternak elastic foundations
using an analytical approach are studied. The rectangular plates are reinforced by single-walled carbon
nanotubes (SWCNTs) which are assumed to be graded through the thickness direction with four types
of distributions. The mathematical model of the FG-CNTRC plate is developed based on the first-order
shear deformation plate theory (FSDT) and Hamilton principle. By using Navier solution, the governing
equations are solved to obtain the central deflection and the natural frequency parameters. Several
examples are verified to have higher accuracy than those from the previous method in the literature.
Also, the effects of different parameters on static response and natural frequency of FG-CNTRC plate are
highlighted by solving numerous examples. Finally, these new results may serve as benchmarks for future
investigations.Dinh Duc Nguyenducnd@vnu.edu.vnJaehong LeeThoi Trung NguyenToan Thang Pham2017-12-20T04:25:14Z2017-12-20T04:25:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2820This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28202017-12-20T04:25:14ZNew approach to study nonlinear dynamic response and vibration of sandwich composite cylindrical panels with auxetic honeycomb core layerThe main goal of this study is using analytical solution to investigate the nonlinear dynamic response and
vibration of sandwich auxetic composite cylindrical panels. The sandwich composite panels have three
layers in which the top and bottom outer skins are isotropic aluminum materials, the central auxetic
core layer – honeycomb structures with negative Poisson’s ratio using the same aluminum material. The
panels are resting on elastic foundations and subjected to mechanical, blast and damping loads. Based
on Reddy’s first order shear deformation theory (FSDT) with the geometrical nonlinear in von Karman
and using the Airy stress functions method, Galerkin method and fourth-order Runge–Kutta method,
the resulting equations are solved to obtain expressions for nonlinear motion equations. The effects
of geometrical parameters, material properties, elastic Winkler and Pasternak foundations, mechanical,
blast and damping loads on the nonlinear dynamic response and the natural frequencies of sandwich
composite cylindrical panels are studied.Dinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimDuc Tuan NgoPhuong Tran2017-12-20T04:24:20Z2017-12-20T04:24:20Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2819This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28192017-12-20T04:24:20ZA rate-dependent hybrid phase field model for dynamic crack propagationSeveral models of variational phase field for fracture have been introduced and analyzed to different degrees of applications, and the rate-independent phase field approach has been shown to be a versatile one, but it is not able to accurately capture crack velocity and dissipated energy in dynamic crack propagation. In this paper, we introduce a novel rate-dependent regularized phase field approach to study dynamic fracture behaviors of polymethylmethacrylate materials, in which the rate coefficient is estimated through energy balance, i.e., dynamics release energy, cohesive energy and dissipated energy. The mode-I dynamics crack problem is considered, and its accuracy is validated with respect to experimental data [F. Zhou, Ph.D. dissertation (The University of Tokyo, Japan, 1996)] and other numerical methods, taking the same configuration, material property, crack location, and other relevant assumptions. The results shed light on the requirement and need for taking the rate-dependent coefficient in dynamic fracture analysis.Hong Duc DoanQuoc Tinh BuiVan Thom DoDinh Duc Nguyenducnd@vnu.edu.vn2017-12-20T02:58:34Z2017-12-20T02:58:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2818This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28182017-12-20T02:58:34ZDynamic response and vibration of composite double curved shallow shells with negative Poisson’s ratio in auxetic honeycombs core layer on elastic foundations subjected to blast and damping loadsThe purpose of the present study is to investigate dynamic response and vibration of composite double curved
shallow shells with negative Poisson’s ratios in auxetic honeycombs core layer on elastic foundations subjected
to blast and damping loads using analytical solution. This study considers composite double curved shallow
shells with auxetic core which have three layers in which the top and bottom outer skins are isotropic aluminum
materials; the central layer has honeycomb structure using the same aluminum material. Based on the first order
shear deformation theory (FSDT) with the geometrical nonlinear in von Karman and using Airy stress functions
method, Galerkin method and the fourth-order Runge–Kutta method, the resulting equations are solved to obtain
expressions for nonlinear motion equations. The effects of geometrical parameters, material properties, elastic
foundations Winkler and Pasternak, the nonlinear dynamic analysis and vibration of double curved shallow shells
with negative Poisson’s ratios in auxetic honeycombs core layer are studiedDinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimHong Cong PhamTuan Anh NguyenDinh Khoa Nguyen2017-12-20T02:57:12Z2017-12-20T02:57:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2812This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28122017-12-20T02:57:12ZNew approach to investigate nonlinear dynamic response and vibration of imperfect functionally graded carbon nanotube reinforced composite double curved shallow shells subjected to blast load and temperatureThis paper presents a new approach – using analytical solution to investigate nonlinear dynamic response and vibration of imperfect functionally graded carbon nanotube reinforced composite (FG-CNTRC) double curved shallow shells. The double curved shallow shells are reinforced by single-walled carbon nanotubes (SWCNTs) which vary according to the linear functions of the shell thickness. The shells are resting on elastic foundations and subjected to blast load and temperature. The shell's effective material properties are assumed to depend on temperature and estimated through the rule of mixture. By applying higher order shear theory, Galerkin method and fourth-order Runge–Kutta method and the Airy stress function, nonlinear dynamic response and natural frequency for thick imperfect FG-CNTRC double curved shallow shells are determined. In numerical results, the influences of geometrical parameters, elastic foundations, initial imperfection, temperature increment and nanotube volume fraction on the nonlinear vibration of the FG-CNTRC double curved shallow shells are investigated. The proposed results are validated by comparing with those of other authors.Dinh Duc Nguyenducnd@vnu.edu.vnQuoc Quan TranDinh Khoa Nguyen2017-12-20T02:56:00Z2017-12-20T02:56:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2810This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28102017-12-20T02:56:00ZThe effects of strength models in numerical study of metal plate destruction by contact xeplosive chargeTuan Anh TruongVan Thom DoTien Dat PhamDinh Duc Nguyenducnd@vnu.edu.vn2017-12-20T02:54:24Z2017-12-20T02:54:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2809This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28092017-12-20T02:54:24ZThermal buckling analysis of FGM sandwich truncated conical shells reinforced by FGM stiffeners resting on elastic foundations using FSDTThis work presents an analytical approach to investigate the mechanical and thermal buckling of functionally graded materials sandwich truncated conical shells resting on Pasternak elastic foundations, subjected to thermal load and axial compressive load. Shells are reinforced by closely spaced stringers and rings, in which the material properties of shells and stieners are graded in the
thickness direction following a general sigmoid law distribution and a general power law distribution. Four models of coated shell-stiener arrangements are investigated. The change of spacing between stringers in the meridional direction also is taken into account. Two cases on uniform temperature rise and linear temperature distribution through the thickness of shell are considered. Using the rst-order shear deformation theory, Lekhnitskii smeared stiener technique and the adjacent equilibrium criterion, the linearization stability
equations have been established. Approximate solution satises simply supported boundary conditions and Galerkin method is applied to obtain closed-form expression for determining the critical compression buckling
load and thermal buckling load in cases uniform temperature rise and linear temperature distribution across the shell thickness. The eects of temperature,
foundation, core layer, coating layer, stieners,
material properties, dimensional parameters and semi-vertex angle on buckling behaviors of shell are shown.Dinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimQuang Chan Do2017-12-20T02:51:47Z2017-12-20T02:51:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2808This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28082017-12-20T02:51:47ZPhase-field thermal buckling analysis for cracked functionally graded composite plates considering neutral surfaceIn this paper, the variational phase field model is adopted to analyze thermal buckling behavior of cracked
functionally graded material (FGM) plates. Unlike existing works, the difference between neutral surface and
mid-surface of FGM plates is taken into account in the present study. The kinematics of plate is based on first
order shear deformation theory, while the crack is simulated by variational phase-field theory. The critical
buckling temperature rises of cracked FGM plate is calculated, and the obtained results are then compared with
those derived from extended isogeometric analysis by the authors and other numerical methods. We analyze the
thermal buckling of cracked FGM plates for both cases: (a) the mid-surface coincides neutral surface, and (b)
they are different between each other, and then showing their influence. We also investigate the effects of
boundary condition and material properties on thermal buckling of cracked FGM plate. Through these results, it
reveals the necessity to consider the difference between neutral surface and mid-surface in thermal buckling
analysis.Van Thom DoHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vnQuoc Tinh Bui2017-12-20T02:51:01Z2017-12-20T02:51:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2813This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28132017-12-20T02:51:01ZNonlinear dynamic analysis and vibration of eccentrically stiffened S-FGM elliptical cylindrical shells surrounded on elastic foundations in thermal
environmentsElliptical cylindrical shell is one of shells with special shape. Up to date, there is no publication on vibration and dynamic of functionally graded elliptical cylindrical shells. Therefore, the purpose of the present study is to
investigate the nonlinear dynamic response and vibration of imperfect eccentrically stiffness functionally graded
elliptical cylindrical shells on elastic foundations using both the classical shell theory (CST) and Airy stress
functions method with motion equations using Volmir's assumption. The material properties are assumed to be
temperature - dependent and graded in the thickness direction according to a Sigmoid power law distribution (S
FGM). The S-FGM elliptical cylindrical shell with metal-ceramic-metal layers are reinforced by outside metal
stiffeners. Both the S-FGM elliptical shell and metal stiffeners are assumed to be in thermal environment and
both of them are deformed under temperature simultaneously. Two cases of thermal loading (uniform
temperature rise and temperature variation through thickness) are considered. The nonlinear motion equations
are solved by Galerkin method and Runge-Kutta method (nonlinear dynamic response, natural frequencies). The
effects of geometrical parameters, material properties, elastic foundations Winkler and Pasternak, the nonlinear
dynamic analysis and nonlinear vibration of the elliptical cylindrical shells are studied. The some obtained
results are validated by comparing with those in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Nguyen PhamDinh Khoa Nguyen2017-12-20T02:47:51Z2017-12-20T02:47:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2805This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28052017-12-20T02:47:51ZThe dynamic response and vibration of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) truncated conical shells resting on elastic foundationBased on the classical shell theory, the linear dynamic response of functionally graded
carbon nanotube-reinforced composite (FG-CNTRC) truncated conical shells resting on elastic
foundations subjected to dynamic loads is presented. The truncated conical shells are reinforced by
single-walled carbon nanotubes (SWCNTs) that vary according to the linear functions of the shell
thickness. The motion equations are solved by the Galerkin method and the fourth-order Runge–Kutta
method. In numerical results, the influences of geometrical parameters, elastic foundations, natural
frequency parameters, and nanotube volume fraction of FG-CNTRC truncated conical shells are
investigated. The proposed results are validated by comparing them with those of other authors.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Nguyen Phamnguyenpd_58@vnu.edu.vn2017-12-20T02:45:16Z2017-12-20T02:45:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2804This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28042017-12-20T02:45:16ZNonlinear dynamic response and vibration of nanocomposite multilayer organic solar cellIn the recent years, organic solar cell (OSC) has attracted much interest of the research community due to its great promise as renewable sources. This paper presents the first analytical approach to investigate the nonlinear dynamic response and vibration of imperfect rectangular nanocompsite multilayer organic solar cell subjected to mechanical loads using the classical plate theory. Nanocompsite organic solar cell consists of five layers of Al, P3HT:PCBM, PEDOT:PSS, IOT and glass. Motion and compatibility equations are derived using the classical plate theory and taking into account the effects of initial geometrical imperfection and geometrical nonlinearity in
Von Karman – Donnell sense. The Galerkin method and fourth – order Runge – Kutta method are used to give
explicit expressions of natural frequencies, nonlinear frequency – amplitude relation and nonlinear dynamic
responses of nanocompsite organic solar cell. The numerical results show the influences of geometrical parameters,
the thickness of layers, imperfections, and mechanical loads on the nonlinear dynamic response and
nonlinear vibration of nanocompsite organic solar cell.Dinh Duc Nguyenducnd@vnu.edu.vnSeung-Eock KimQuoc Quan TranDinh Long Dangddlong@vnu.edu.vnMinh Anh Vuvuminhanhhp@gmail.com2017-12-20T02:40:31Z2017-12-20T02:40:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2797This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27972017-12-20T02:40:31ZTransitivity Demolition and the Fall of Social NetworksIn this paper, we study crucial elements of a complex network, namely its nodes and connections, which play a key role in maintaining the network’s structure and function under unexpected structural perturbations of nodes and edges removal. Speciﬁcally, we want to identify vital nodes and edges whose failure (either random or intentional) will break the most number of connected triples(or triangles)in the network. This problem is extremely important, because connected triples form the foundation of strong connections in many real-world systems, such as mutual relationships in social networks, reliable data transmission in communication networks, and stable routing strategies in mobile networks. Disconnected triples, analog to broken mutual connections, can greatly affect the network’s structure and disrupt its normal function, which can further lead to the corruption of the entire system. The analysis of such crucial elements will shed light on key factors behind the resilience and robustness of many complex systems in practice. We formulate the analysis under multiple optimization problems and show their intractability. We next propose efﬁcient approximation algorithms, namely, DAK-n and DAK-e, which guarantee an (1 − 1/e)-approximate ratio (compared with the overall optimal solutions) while having the same time complexity as the best triangle counting and listing algorithm on power-lawnetworks.Thisadvantagemakes ouralgorithmsscaleextremelywellevenforverylargenetworks.Inanapplicationperspective,we perform comprehensive experiments on real social traces with millions of nodes and billions of edges. Empirical results indicate that our approaches achieve comparably better solution quality while are up to 100×faster than the current state-of-the-art methods.The Hung Nguyenthehung912000@gmail.comXuan Huan Hoanghuanhx@vnu.edu.vnP. Nam NguyenVu Tam NguyenNgoc Thang Dinh2017-12-12T07:45:06Z2017-12-12T07:45:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2766This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27662017-12-12T07:45:06ZSatellites may underestimate rice residue and associated burning emissions in VietnamIn this study, we estimate rice residue, associated burning emissions, and compare results with existing emissions inventories employing a bottom-up approach. We first estimated field-level post-harvest rice residues, including separate fuel-loading factors for rice straw and rice stubble. Results suggested fuel-loading factors of 0.27 kg m−2 (±0.033), 0.61 kg m−2 (±0.076), and 0.88 kg m−2 (±0.083) for rice straw, stubble, and total post-harvest biomass, respectively. Using these factors, we quantified potential emissions from rice residue burning and compared our estimates with other studies. Our results suggest total rice residue burning emissions as 2.24 Gg PM2.5, 36.54 Gg CO and 567.79 Gg CO2 for Hanoi Province, which are significantly higher than earlier studies. We attribute our higher emission estimates to improved fuel-loading factors; moreover, we infer that some earlier studies relying on residue-to-product ratios could be underestimating rice residue emissions by more than a factor of 2.3 for Hanoi, Vietnam. Using the rice planted area data from the Vietnamese government, and combining our fuel-loading factors, we also estimated rice residue PM2.5 emissions for the entirety of Vietnam and compared these estimates with an existing all-sources emissions inventory, and the Global Fire Emissions Database (GFED). Results suggest 75.98 Gg of PM2.5 released from rice residue burning accounting for 12.8% of total emissions for Vietnam. The GFED database suggests 42.56 Gg PM2.5 from biomass burning with 5.62 Gg attributed to agricultural waste burning indicating satellite-based methods may be significantly underestimating emissions. Our results not only provide improved residue and emission estimates, but also highlight the need for emissions mitigation from rice residue burning.Kristofer LaskoKrishna Prasad VadrevuTuan Vinh TranEvan EllicottThi Nhat Thanh Nguyenthanhntn@vnu.edu.vnQuang Hung Buihungbq@vnu.edu.vnChristopher Justice2017-12-12T07:44:09Z2017-12-12T07:44:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2765This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27652017-12-12T07:44:09ZImprovement of land-cover classification over frequently cloud-covered areas using Landsat 8 time-series composites and an ensemble of supervised classifiersRecent abundance of moderate-to-high spatial resolution satellite imagery has facilitated land-cover map production. However, in cloud-prone areas, building high-resolution land-cover maps is still challenging due to infrequent satellite revisits and lack of cloud-free data. We propose a classification method for cloud-persistent areas with high temporal dynamics of land-cover types. First, compositing techniques are employed to create dense time-series composite images from all available Landsat 8 images. Then, spectral–temporal features are extracted to train an ensemble of five supervised classifiers. The resulting composite images are clear with at least 99.78% cloud-free pixels and are 20.47% better than their original images on average. We classify seven land classes, including paddy rice, cropland, grass/shrub, trees, bare land, impervious area, and waterbody over Hanoi, Vietnam, in 2016. Using a time series of composites significantly improves the classification performance with 10.03% higher overall accuracy (OA) compared to single composite classifications. Additionally, using time series of composites and the ensemble technique, which combines the best of five experimented classifiers (eXtreme Gradient Boosting, logistic regression, Support Vector Machine (SVM) with Radial Basis Function (RBF) kernel – SVM–RBF and Linear kernel – SVM–Linear, multilayer perceptron), performed best with 84% OA and 0.79 kappa coefficient.Duc Chuc Manchucmd@fimo.edu.vnThanh Thuy Nguyennguyenthanhthuy@vnu.edu.vnQuang Hung Buihungbq@fimo.edu.vnKristofer LaskoThi Nhat Thanh Nguyenthanhntn@vnu.edu.vn2017-12-11T09:38:43Z2019-02-18T04:14:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2748This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27482017-12-11T09:38:43ZOn the min-cost traveling salesman problem with droneOver the past few years, unmanned aerial vehicles (UAV), also known as drones, have been adopted as part of a new logistic method in the commercial sector called "last-mile delivery". In this novel approach, they are deployed
alongside trucks to deliver goods to customers to improve the quality of service and reduce the transportation cost. This approach gives rise to a new variant of the traveling salesman problem (TSP), called TSP with drone (TSP-D). A variant of this problem that aims to minimize the time at which truck and drone finish the service (or, in other words, to maximize the quality of service) was studied in the work of Murray and Chu (2015). In contrast, this paper considers a new variant of TSP-D in which the objective is to minimize operational costs including total transportation cost and one created by
waste time a vehicle has to wait for the other. The problem is first formulated mathematically. Then, two algorithms are proposed for the solution. The first
algorithm (TSP-LS) was adapted from the approach proposed by Murray and Chu (2015), in which an optimal TSP solution is converted to a feasible TSP-D solution by local searches. The second algorithm, a Greedy Randomized Adaptive Search Procedure (GRASP), is based on a new split procedure that optimally splits any TSP tour into a TSP-D solution. After a TSP-D solution has been generated, it is then improved through local search operators. Numerical results obtained on various instances of both objective functions with different sizes and characteristics are presented. The results show that GRASP outperforms TSP-LS in terms of solution quality under an acceptable running time.Quang Minh HaYves DevilleQuang Dung PhamMinh Hoang Haminhhoang.ha@vnu.edu.vn2017-12-04T02:57:53Z2017-12-04T02:57:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2735This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27352017-12-04T02:57:53ZCorona anemometry using dual pin probeIn this paper, we present an experimental study on the anemometry characteristics of a bipolar corona discharge probe with symmetrically arranged parallel electrodes. The possibility of measuring a wide range of air flow rate/flow velocity has been demonstrated. The parallel pin probe simultaneously creates positive and negative corona discharge, decomposes air media at both electrodes while keeping them with charge balance ensured by the use of a single isolated power source. This feature is fundamentally different from other reported unipolar discharge configurations, where the decomposed gas and charge is created from single electrode. Under the existence of the air flow, the decomposed gas is redistributed towards the downstream electrode, and changes the current–voltage characteristics of the system. When the probe is in open space, the discharge current is reduced with increasing flow velocity. In constrained space the discharge current behaviour is similar at high flow rates above 25 l min−1, while at low flow rates this relation is reversed. In addition, the sensitivity of discharge current to change in air flow is much higher when the negative pin is placed downstream. Both open space and constrained space characteristics are explained in terms of the influence of external flow on the ozone distribution and its effect on the discharge current. This explanation is supported by ozone measurements, with the data showing good correlation between the discharge current and ozone concentration with respect to the external flow. The role of the electrode separation and discharge voltage is also investigated.Van Thanh Dauvandt@gmail.comThien Xuan Dinhthien@cfd.ritsumei.ac.jpThanh Tung Buitungbt@vnu.edu.vnTibor Terebessytibor.terebessy@clearviewtraffic.com2017-12-04T02:57:07Z2017-12-04T02:57:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2729This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27292017-12-04T02:57:07Z30-GHz High-Frequency Application of Screen Printed Interconnects on an Organic SubstratePrinted conductive traces on flexible substrates offer many potential applications in the area of wearable electronics, ranging from search and rescue operations to health and physiological monitoring. The literature abounds on the effect of sintering conditions on the dc electrical resistivity of printed traces, due to the applications considered which fall in the lower frequency domain (megahertz range). There is a growing interest to investigate wireless body area networks for wearable electronics operating in the higher frequencies, due to the advantages involved. At present, there is a little information available on the radio frequency performance of printed interconnects, and this work seeks to investigate the effect of the paste property on the dc conductivity and high-frequency performance ( $\textbackslashle 30$ GHz) of interconnects. The results obtained suggest that paste leveling has a significant influence on the dc electrical performance. In addition, the dc conductivity values are possibly affected by the adhesion of the paste onto the particular substrate during the printing process, which was observed to have a significant effect on the quality and thicknesses of the traces printed. Last, the influence of the dc conductivity on the high-frequency performance of interconnects is investigated, where the measured results are validated with simulation results.Ying Ying Limyingying.lim@aist.go.jpYee Mey GohManabu YoshidaThanh Tung Buitungbt@vnu.edu.vnMasahiro AoyagiChangqing Liu2017-12-03T11:55:09Z2017-12-03T11:55:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2728This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27282017-12-03T11:55:09ZAnalytical modeling of a silicon-polymer electrothermal microactuatorThis paper illustrates both thermal and mechanical analysis methods for displacement and contact force calculating of a novel sensing silicon-polymer microgripper when heat sources are applied by an electric current via its actuators. Thermal analysis is used to obtain temperature profile by figuring out a heat conductions and convections model. Temperature profile is then applied into the mechanical structure of the gripper's actuators to form the final equation of displacement and contact force of the jaws. Finally, the comparison among the calculation, simulation and actual measurement concludes that materialization methods are appropriate. Achieving the final equation of gripper's jaws displacement and contact force is a major step to optimize or reform this novel structure for different sizes to meet specific applications.Huu Phu Phanphanhuuphu82@gmail.comMinh Ngoc Nguyenminhngoc@gmail.comNgoc Viet Nguyenvietnn.mt@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vn2017-12-03T11:17:15Z2017-12-05T06:29:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2718This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27182017-12-03T11:17:15ZLiquid identification by using a micro-electro-mechanical interdigital transducerA surface-acoustic-mode aluminum nitride (AlN) transducer is utilized to determine the type of liquid dropped on the propagation path. It is based on tracking the shrinking droplet radius and observing stagnant liquid molecules during and after the liquid evaporation process. The device configuration is suitable to test small amounts of liquids, in the microliter range. According to both mass loading and physical property mechanisms, eight samples of liquids, isopropanol (IPA), ethanol (ETH), deionized-water (DW), tap water (TW), heptane (HEP), propylene glycol monomethyl ether acetate (PGMEA), hexamethyldisilazane (HMDS) and acetone (ACE), which have different equilibrium vapor pressures, molecular weights and boiling points, are accurately detected. The experimental results show that the rate of the change in the energy loss including a slow and fast attenuation region depends on the change of physical properties, such as density, sound speed in liquids and evaporation rate, during the evaporation process. As the evaporation rate of the DW is rather slow, the slow attenuation region occurs for a longer time than the fast one. Consequently, the whole oscillation duration of the attenuation occurs for a longer time, whereas that of the other liquids studied, like ACE, ETH, and IPA, having a faster evaporation rate is shorter. Sensitivities of the surface-acoustic-mode transducer to the evaporation process of liquids such as DW, TW, PGMEA, HMDS, HEP, IPA, ETH and ACE are -29.39, -29.53, -31.79, -34.12, -33.62, -32.87, -32.67, and -32.82 dB small mu m-2{,} respectively. The concentration of stagnant liquid molecules causes a change in the surface mass of the micro-electro-mechanical transducer{,} which causes a frequency shift and increases the signal noise at the receiver after the liquid evaporation process. The average frequency shifts of ACE{,} HEP{,} HMDS{,} ETH{,} IPA{,} PGMEA{,} TW and DW are 241{,} 206{,} 172{,} 117{,} 76{,} 27.3{,} 11.6 and 0 kHz{,} respectively{,} coherent with the type of formed liquid pattern on the device surface{,} thus allowing to detect liquid samples effectively.Thu Hang BuiT.H.Bui@tudelft.nlBruno Moranamorana@gmail.comAtef Akhnoukhakhnoukh@gmail.comDuc Chutrinhcd@vnu.edu.vnPasqualina M. Sarrosarro@gmail.com2017-11-21T22:11:58Z2018-01-10T07:58:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2664This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26642017-11-21T22:11:58ZDesign and implementation of site-specific rainfall-induced landslide early warning and monitoring system: a case study at Nam Dan landslide (Vietnam)ABSTRACTThis paper proposes and implements an early warning and monitoring system for rainfall-induced landslide (named as EWMRIL) with a case study at the Nam Dan landslide (northern Vietnam). The proposed system consists of six sensor nodes and one rainfall station that are used to sense large amounts of data in real-time such as soil moisture, pore-water pressure (PWP), movement status, and rainfall. In addition, a new flexible configuration for the wireless communication system is proposed that is capable not only to save the energy consuming but also to ensure the reliability of the system. Using wireless communication system, the sensed data were sent to the computer station for analyzing and predicting the instability of the landslide in terms of factor of safety (FoS) using the finite element seepage analysis and the limit equilibrium slope stability analysis methods. These methods are available in the SEEP/W and SLOPE/W modules of the GeoStudio software. Based on the analyzing results, the system proposed three warning levels for the landslide Early, Intermediate, and Imminent. Experiment result in the rainy season from August to September 2016 has proven the validity of the EWMRIL system. The result of this study is useful for landslide risk prevention and management in landslide prone-areas.Quoc Anh Giangianquocanh@gmail.comDuc Tan Trantantd@vnu.edu.vnDinh Chinh Nguyenchinhnd@vnu.edu.vnViet Ha Nhuvietha.nhu@gmail.comTien Dieu BuiBuiTienDieu@gmail.com2017-11-08T07:18:14Z2017-11-08T07:18:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2621This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26212017-11-08T07:18:14ZInterface Charge Trap Density of Solution Processed Ferroelectric Gate Thin Film Transistor Using ITO/PZT/Pt StructureThe conductance method was applied to investigate the interface charge trap density
(Dit) of solution processed ferroelectric gate thin film transistor (FGT) using indium-tin
oxide (ITO)/ Pb(Zr,Ti)O3 (PZT)/Pt structure. As a result, a large value of Dit of MFS
capacitor, i.e., Pt/PZT/ITO, was estimated to be 1.2 × 1014 eV−1 cm−2. This large Dit
means that an interface between the ITO layer and the PZT layer is imperfect and it is
one of themain reasons for the poor memory property of this FGT. By using transmission
electron microscopy (TEM), this imperfect interface was clearly observed. Thus, it is
concluded that improvement of this interface is critical for better memory performance.Van Thanh PhamNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vnMiyasako TakaakiTrong Tue PhanTokumitsu EisukeShimoda Tatsuya2017-11-08T07:15:36Z2017-11-08T07:15:36Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2620This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26202017-11-08T07:15:36ZSwitchable Voltage Control of the Magnetic Anisotropy in Heterostructured Nanocomposites of CoFe/NiFe/PZTIn this work, we study the magnetic properties of a CoFe/NiFe/PZT heterostructured nanocomposite
that is affected by the strain in the PZT substrate when a voltage in the range from –250
to 250 V is applied. An interesting electric-voltage-controlled magnetic anisotropy, with a relative
increase in magnetization up to above 100%, is observed. This brings a new challenge to operate a
low-power-consuming spin electronic device. We also utilize a theoretical model based on interfacecharge-
mediated and strain-mediated magnetic-electric coupling to understand the change in the
magnetic properties of the investigated material.Thi Minh Hong Nguyenhongntm@vnu.edu.vnBa Doan NguyenHuy Tiep NguyenViet Cuong Lecuonglv@vnu.edu.vnNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vnDuc Thang PhamDong-Hyun Kim2017-11-08T07:13:14Z2017-11-08T07:13:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2619This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26192017-11-08T07:13:14ZElectric Properties and Interface Charge Trap Density of Ferroelectric Gate Thin Film Transistor Using (Bi,La)4Ti3O12/Pb(Zr,Ti)O3 Stacked Gate InsulatorWe successfully fabricated ferroelectric gate thin film transistors (FGTs) using solution-processed (Bi,La)4Ti3O12 (BLT)/Pb(Zr,Ti)O3 (PZT)
stacked films and an indium–tin oxide (ITO) film as ferroelectric gate insulators and an oxide channel, respectively. The typical n-type channel
transistors were obtained with the counterclockwise hysteresis loop due to the ferroelectric property of the BLT/PZT stacked gate insulators.
These FGTs exhibited good device performance characteristics, such as a high ON/OFF ratio of 106, a large memory window of 1.7–3.1 V, and a
large ON current of 0.5–2.5 mA. In order to investigate interface charge trapping for these devices, we applied the conductance method to MFS
capacitors, i.e., Pt/ITO/BLT/PZT/Pt capacitors. As a result, the interface charge trap density (Dit) between the ITO and BLT/PZT stacked films
was estimated to be in the range of 10�11–10�12 eV�1 cm�2. The small Dit value suggested that good interfaces were achieved.Van Thanh PhamNguyen Quoc Trinh Buitrinhbnq@vnu.edu.vnMiyasako TakaakiTrong Tue PhanTokumitsu EisukeShimoda Tatsuya2017-11-07T16:27:28Z2017-12-05T06:28:11Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2629This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26292017-11-07T16:27:28ZInterference Suppression of ULA Antennas by Phase-only Control Using BAT AlgorithmThis paper proposes an adaptive BAT algorithm (BA) based beamformer for pattern nulling of half-wave Dipole Uniformly Spaced Linear Array (DULA), of which the imposed nulls have been placed at directions of interferences. This pattern nulling is obtained by controlling only the phase of each array element. In order to verify the proposal, several scenarios of DULA pattern with the pre-set nulls have been performed and compared with those of genetic algorithm (GA) and accelerated particle swarm optimization (APSO) considering mutual coupling. The proposed beamformer has shown the ability to suppress side lobes, to maintain predefined beamwidth, to place precisely single, multiple, and broad nulls at an arbitrary direction of interferences. Furthermore, the beamformer is much faster and more effective in terms of null steering and side lobe suppression in pattern synthesis than GA and APSO based ones.Van Luyen Tongtvluyen@gmail.comVu Bang Giang Truonggiangtvb@vnu.edu.vn2017-11-02T22:28:00Z2018-01-10T07:51:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2605This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/26052017-11-02T22:28:00ZEffect of droplet shrinking on surface acoustic wave response in microfluidic applicationsThe effect of the contact angle and radius of a microsize droplet on the surface acoustic wave (SAW) response for microfluidic applications is reported. It is studied through the dynamic change of the droplet shape during the evaporation process. An aluminium nitride SAW device, operating at 125.7 MHz, is utilized to investigate the deformation of the droplet shape (contact angle and contact radius) caused by shrinking. The large cavity placed on the propagation path distorts the in-band SAW response one time at the centre frequency. The fractional coefficient of the SAW insertion loss, before and after dropping the liquid on the propagation path, is continuously recorded. The change in the fractional coefficient shows that the radiated acoustic kinetic energy depends on the contact area between the sessile micro-size droplet and the SAW device more than the contact angle of the droplet. Three droplet volumes have been considered, namely 0.05, 0.1 and 0.13 μl, and the electrical results show a better agreement with the theoretical data than the optical image data. The average duration of the fractional coefficient change for these cases is 420, 573 and 760 s, respectively. The effect of the hydrophobicity versus hydrophilicity of the contact surface on the duration of the fractional coefficient change is studied by coating the SAW with a silicon oxide or hexamethyldisilazane (HMDS) thin layer. For the same 0.05 μl sessile droplet on the hydrophobic surface, this duration is on average 110 s longer than that on the hydrophilic surface.ThuHang Buihangbt@vnu.edu.vnVan Nguyennguyenvan@gmail.comSten VollebregtVollebregt@gmail.comBruno Moranamorana@gmail.comHenk van Zeijlhenkvz@gmail.comDuc Trinh Chutrinhcd@vnu.edu.vnPasqualina M Sarrosarrop@gmail.com2017-11-01T14:00:13Z2017-11-01T14:00:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2599This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25992017-11-01T14:00:13ZSemiautomated registration of pre- and intraoperative CT for image-guided percutaneous liver tumor ablation interventionsGokhan GunayManh Ha LuuAdriaan MoelkerTheo van WalsumStefan Klein2017-10-31T01:53:07Z2017-10-31T01:53:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2582This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25822017-10-31T01:53:07ZPrecision and recall oncology: combining multiple gene mutations for improved identification of drug-sensitive tumoursCancer drug therapies are only effective in a small proportion of patients. To make things worse, our ability to identify these responsive patients before administering a treatment is generally very limited. The recent arrival of large-scale pharmacogenomic data sets, which measure the sensitivity of molecularly profiled cancer cell lines to a panel of drugs, has boosted research on the discovery of drug sensitivity markers. However, no systematic comparison of widely-used single-gene markers with multi-gene machine-learning markers exploiting genomic data has been so far conducted. We therefore assessed the performance offered by these two types of models in discriminating between sensitive and resistant cell lines to a given drug. This was carried out for each of 127 considered drugs using genomic data characterising the cell lines. We found that the proportion of cell lines predicted to be sensitive that are actually sensitive (precision) varies strongly with the drug and type of model used. Furthermore, the proportion of sensitive cell lines that are correctly predicted as sensitive (recall) of the best single-gene marker was lower than that of the multi-gene marker in 118 of the 127 tested drugs. We conclude that single-gene markers are only able to identify those drug-sensitive cell lines with the considered actionable mutation, unlike multi-gene markers that can in principle combine multiple gene mutations to identify additional sensitive cell lines. We also found that cell line sensitivities to some drugs (e.g. Temsirolimus, 17-AAG or Methotrexate) are better predicted by these machine-learning models.Stefan NaulaertsCao Cuong Dangcuongdc@vnu.edu.vnPedro Ballester2017-10-31T01:52:06Z2017-10-31T01:52:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2578This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25782017-10-31T01:52:06ZFLU, an Amino Acid Substitution Model for Influenza ProteinsThe amino acid substitution model is the core component of many protein analysis systems such as sequence similarity search, sequence alignment, and phylogenetic inference. Although several general amino acid substitution models have been estimated from large and diverse protein databases, they remain inappropriate for analyzing specific species, e.g., viruses. Emerging epidemics of influenza viruses raise the need for comprehensive studies of these dangerous viruses. We propose an influenza-specific amino acid substitution model to enhance the understanding of the evolution of influenza viruses.Cao Cuong DangSi Quang LeOlivier GascuelSy Vinh Levinhls@vnu.edu.vn2017-10-23T08:45:53Z2017-10-23T08:45:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2577This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25772017-10-23T08:45:53ZHow Reliable Are Ligand-Centric Methods for Target Fishing?Computational methods for Target Fishing (TF), also known as Target Prediction or Polypharmacology Prediction, can be used to discover new targets for small-molecule drugs. This may result in repositioning the drug in a new indication or improving our current understanding of its efficacy and side effects. While there is a substantial body of research on TF methods, there is still a need to improve their validation, which is often limited to a small part of the available targets and not easily interpretable by the user. Here we discuss how target-centric TF methods are inherently limited by the number of targets that can possibly predict (this number is by construction much larger in ligand-centric techniques). We also propose a new benchmark to validate TF methods, which is particularly suited to analyse how predictive performance varies with the query molecule. On average over approved drugs, we estimate that only five predicted targets will have to be tested to find two true targets with submicromolar potency (a strong variability in performance is however observed). In addition, we find that an approved drug has currently an average of eight known targets, which reinforces the notion that polypharmacology is a common and strong event. Furthermore, with the assistance of a control group of randomly-selected molecules, we show that the targets of approved drugs are generally harder to predict.Antonio PeonCao Cuong DangPedro Ballester2017-10-16T08:14:57Z2017-10-16T08:14:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2574This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25742017-10-16T08:14:57ZThe vehicle routing problem with service level constraintsWe consider a vehicle routing problem which seeks to minimize cost subject to service level constraints on several groups of deliveries. This problem captures some essential challenges faced by a logistics provider which operates transportation services for a limited number of partners and should respect contractual obligations on service levels. The problem also generalizes several important classes of vehicle routing problems with profits. To solve it, we propose a compact mathematical formulation, a branch-and-price algorithm, and a hybrid genetic algorithm with population management, which relies on problem-tailored solution representation, crossover and local search operators, as well as an adaptive penalization mechanism establishing a good balance between service levels and costs. Our computational experiments show that the proposed heuristic returns very high-quality solutions for this difficult problem, matches all optimal solutions found for small and medium-scale benchmark instances, and improves upon existing algorithms for two important special cases: the vehicle routing problem with private fleet and common carrier, and the capacitated profitable tour problem. The branch-and-price algorithm also produces new optimal solutions for all three problems.Teobaldo BulhõesMinh Hoang Haminhhoang.ha@vnu.edu.vnRafael MartinelliThibaut Vidal2017-10-16T08:13:57Z2017-10-16T08:13:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2573This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25732017-10-16T08:13:57ZSolving the multi-vehicle multi-covering tour problemThe well-known multi-vehicle covering tour problem (m-CTP) involves finding a minimum-length set of vehicle routes passing through a subset of vertices, subject to constraints on the length of each route and the number of vertices that it contains, such that each vertex not included in any route is covered. Here, a vertex is considered as covered if it lies within a given distance of at least a vertex of a route. This article introduces a generalized variant of the m-CTP that we called the multi-vehicle multi-covering Tour Problem (mm-CTP). In the mm-CTP, a vertex must be covered at least not only once but several times. Three variants of the problem are considered. The binary mm-CTP where a vertex is visited at most once, the mm-CTP without overnight where revisiting a vertex is allowed only after passing through another vertex and the mm-CTP with overnight where revisiting a vertex is permitted without any restrictions. We first propose graph transformations to convert the last two variants into the binary one and focus mostly on solving this variant. A special case of the problem is then formulated as an integer linear program and a branch-and-cut algorithm is developed. We also develop a Genetic Algorithm (GA) that provides high-quality solutions for the problem. Extensive computational results on the new problem mm-CTP as well as its other special cases show the performance of our methods. In particular, our GA outperforms the current best metaheuristics proposed for a wide class of CTP problems.Tuan Anh PhamMinh Hoang Haminhhoang.ha@vnu.edu.vnXuan Hoai Nguyen2017-08-31T10:17:16Z2017-08-31T10:17:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2567This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25672017-08-31T10:17:16ZPerformance Analysis of Frequency Reuse for PPP Networks in Composite Rayleigh-Lognormal Fading ChannelSinh Cong Lamcongls@vnu.edu.vnKumbesan SandrasegaranPantha Ghosal2017-07-31T03:09:51Z2017-12-07T06:49:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2562This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25622017-07-31T03:09:51ZA Comprehensive Reliability Assessment of Fault-Resilient Network-on-Chip Using Analytical ModelNam Khanh Dangdnk0904@gmail.comAkram Ben AhmedXuan Tu Trantutx@vnu.edu.vnYuichi OkuyamaAbderazek Ben Abdallahbenab@u-aizu.ac.jp2017-07-06T10:55:08Z2018-01-10T07:55:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2552This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25522017-07-06T10:55:08ZDevelopment of a Real Time Supported Program for Motorbike Drivers Using Smartphone Built-in SensorsUsing mobile phones during traffic progress is one of the main causes traffic accidents because drivers do not focus on driving, they try to listen phone calls or to text some messages... Most of research work has focused to car driving. However, using motorbike is very popular in some developing countries such as Vietnam, India, etc. Up to now, there are just a few works, which focus to motorbike driving with obvious limitations. Thus, in this research, we proposed a complete solution for bikers who own a smartphone. Our work exploits the information from built-in sensors in Android smartphone. A complete scheme for motorbike driving is proposed. In this scheme, the user state is detected by improving the current Google activity recognition API. If the state is “On vehicle”, the phone automatically switches to silent mode and send to the caller an SMS. Our work provides a mechanism to receive the calls from VIP contacts and urgent calls. The phone would switch back to the normal mode if the state is not "On vehicle". Furthermore, it sends the accident location to the relatives when an accident occurs to save their lives automatically. The application was tested carefully and it can be used to protect the lives of motorbike drivers.Van Thanh Phamphamvanthanh1209@gmail.comTien Anh Nguyenanhnt007@gmail.comDuc Nghia Trannghiatranduc1986@yahoo.comDuc Anh Nguyenndanh@gmail.comDuc Tan Trantantd@vnu.edu.vn2017-07-04T02:52:33Z2017-07-04T02:52:33Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2543This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25432017-07-04T02:52:33ZraSAT: an SMT solver for polynomial constraintsThis paper presents raSAT SMT solver, which is aimed to handle polynomial constraints over both reals and integers with simple unified methodologies. Its three main features are (1) a raSAT loop for inequalities, which adds testing to interval constraint propagation to accelerate SAT detection, (2) a non-constructive reasoning for equations over reals based on the generalized intermediate value theorem, and (3) soundness of floating-point arithmetic that is guaranteed by (a) rounding up/down over-approximations of intervals, and (b) confirmation of a satisfying instance detected by testing using the iRRAM package, which guarantees error bounds.Vu Xuan TungVan Khanh Tokhanhtv@vnu.edu.vnMizuhito Ogawa2017-07-03T07:57:40Z2017-07-03T07:59:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2519This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25192017-07-03T07:57:40ZImproved mitochondrial amino acid substitution models for metazoan
evolutionary studiesBackground: Amino acid substitution models play an essential role in inferring phylogenies from mitochondrial
protein data. However, only few empirical models have been estimated from restricted mitochondrial protein data
of a hundred species. The existing models are unlikely to represent appropriately the amino acid substitutions from
hundred thousands metazoan mitochondrial protein sequences.
Results: We selected 125,935 mitochondrial protein sequences from 34,448 species in the metazoan kingdom to
estimate new amino acid substitution models targeting metazoa, vertebrates and invertebrate groups. The new models
help to find significantly better likelihood phylogenies in comparison with the existing models. We noted remarkable
distances from phylogenies with the existing models to the maximum likelihood phylogenies that indicate a considerable
number of incorrect bipartitions in phylogenies with the existing models. Finally, we used the new models and
mitochondrial protein data to certify that Testudines, Aves, and Crocodylia form one separated clade within amniotes.
Conclusions: We introduced new mitochondrial amino acid substitution models for metazoan mitochondrial proteins.
The new models outperform the existing models in inferring phylogenies from metazoan mitochondrial protein data.
We strongly recommend researchers to use the new models in analysing metazoan mitochondrial protein data.Sy Vinh Levinhls@vnu.edu.vnCuong Dangcuongdc@vnu.edu.vnQuang Lelsquang@gmail.com2017-07-03T07:57:23Z2017-07-03T07:57:23Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2518This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25182017-07-03T07:57:23ZA mutation in GABRB3 associated with Dravet syndromeDravet syndrome is a rare and severe type of epilepsy in infants. Approximately, 70–80% of
patients with Dravet syndrome have mutations in SCN1A, the gene encoding the alpha-1
subunit of the sodium channel, while some simplex patients have variants in one of several other
genes, including but not limited to GABRA1, SCN2A, STXBP1, GABRG2, and SCN1B. In this study,
we performed exome sequencing in six patients with SCN1A-negative Dravet syndrome to
identify other genes related to this disorder. In one affected individual, we detected a novel de
novo heterozygous missense variant, c.695G>A, p.(Arg232Gln), in GABRB3, the gene encoding
the β3-subunit of the gamma-aminobutyric acid type A (GABAA) receptor, which mediates
inhibitory signaling within the central nervous system. In summary, the data in this study identify
GABRB3 as a candidate gene for Dravet syndrome.Sy Vinh Levinhls@vnu.edu.vnTruc LeVan Khanh LeHuynh KieuHang Dohangdo009@gmail.com2017-07-02T14:43:13Z2017-07-02T14:43:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2545This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25452017-07-02T14:43:13ZPerformance Prediction for Students: A Multi-Strategy ApproachThis paper presents a study on Predicting Student Performance (PSP) in academic systems. In order to solve the task, we have proposed and investigated different strategies. Specifically, we consider this task as a regression problem and a rating prediction problem in recommender systems. To improve the performance of the former, we proposed the use of additional features based on course-related skills. Moreover, to effectively utilize the outputs of these two strategies, we also proposed a combination of the two methods to enhance the prediction performance. We evaluated the proposed methods on a dataset which was built using the mark data of students in information technology at Vietnam National University, Hanoi (VNU). The experimental results have demonstrated that unlike the PSP in e-Learning systems, the regression-based approach should give better performance than the recommender system-based approach. The integration of the proposed features also helps to enhance the performance of the regression-based systems. Overall, the proposed hybrid method achieved the best RMSE score of 1.668. These promising results are expected to provide students early feedbacks about their (predicted) performance on their future courses, and therefore saving times of students and their tutors in determining which courses are appropriate for students’ ability.Thi Oanh TranHai Trieu DangViet Thuong DinhThi Minh Ngoc TruongThi Phuong Thao VuongXuan Hieu Phanhieupx@vnu.edu.vn2017-06-29T15:14:04Z2017-06-29T15:14:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2542This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25422017-06-29T15:14:04ZNa-doped La 0.7 Ca 0.3 MnO 3 compounds exhibiting a large magnetocaloric effect near room temperatureDinh Chi LinhNguyen Thi HaHuu Duc Nguyenducnh@vnu.edu.vnLe Viet BauNguyen Manh AnSeong-Cho YuTran Dang Thanh2017-06-28T14:51:27Z2017-06-28T14:51:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2525This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25252017-06-28T14:51:27ZSystematic assessment of multi-gene predictors of pan-cancer cell line sensitivity to drugs exploiting gene expression dataBackground: Selected gene mutations are routinely used to guide the selection of cancer drugs for a given patient tumour. Large pharmacogenomic data sets, such as those by Genomics of Drug Sensitivity in Cancer (GDSC) consortium, were introduced to discover more of these single-gene markers of drug sensitivity. Very recently, machine learning regression has been used to investigate how well cancer cell line sensitivity to drugs is predicted depending on the type of molecular profile. The latter has revealed that gene expression data is the most predictive profile in the pan-cancer setting. However, no study to date has exploited GDSC data to systematically compare the performance of machine learning models based on multi-gene expression data against that of widely-used single-gene markers based on genomics data. Methods: Here we present this systematic comparison using Random Forest (RF) classifiers exploiting the expression levels of 13,321 genes and an average of 501 tested cell lines per drug. To account for time-dependent batch effects in IC50 measurements, we employ independent test sets generated with more recent GDSC data than that used to train the predictors and show that this is a more realistic validation than standard k-fold cross-validation. Results and Discussion: Across 127 GDSC drugs, our results show that the single-gene markers unveiled by the MANOVA analysis tend to achieve higher precision than these RF-based multi-gene models, at the cost of generally having a poor recall (i.e. correctly detecting only a small part of the cell lines sensitive to the drug). Regarding overall classification performance, about two thirds of the drugs are better predicted by the multi-gene RF classifiers. Among the drugs with the most predictive of these models, we found pyrimethamine, sunitinib and 17-AAG. Conclusions: Thanks to this unbiased validation, we now know that this type of models can predict in vitro tumour response to some of these drugs. These models can thus be further investigated on in vivo tumour models. R code to facilitate the construction of alternative machine learning models and their validation in the presented benchmark is available at http://ballester.marseille.inserm.fr/gdsc.transcriptomicDatav2.tar.gz.Linh NguyenCao Cuong DangPedro J. Ballester2017-06-14T09:49:48Z2017-06-14T09:49:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2391This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23912017-06-14T09:49:48ZBehavior-based Navigation of Mobile Robot in Unknown Environments Using Fuzzy Logic and Multi-Objective OptimizationThis study proposes behavior-based navigation architecture, named BBFM, to deal with the problem of navigating the mobile robot in unknown environments in the presence of obstacles and local minimum regions. In the architecture, the complex navigation task is split into principal sub-tasks or behaviors. Each behavior is implemented by a fuzzy controller and executed independently to deal with a specific problem of navigation. The fuzzy controller is modified to contain only the fuzzification and inference procedures so that its output is a membership function representing the behavior’s objective. The membership functions of all controllers are then used as the objective functions for a multi-objective optimization process to coordinate all behaviors. The result of this process is an overall control signal, which is Pareto-optimal, used to control the robot. A number of simulations, comparisons, and experiments were conducted. The results show that the proposed architecture outperforms some popular behaviorbased architectures in term of accuracy, smoothness, traveled distance, and time response.Thi Thanh Van Nguyenvanntt@vnu.edu.vnManh Duong Phungduongpm@vnu.edu.vnQuang Vinh Tranvinhtq@vnu.edu.vn2017-06-14T09:49:05Z2017-06-14T09:49:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2512This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25122017-06-14T09:49:05ZEnhanced discrete particle swarm optimization path planning for UAV vision-based surface inspectionIn built infrastructure monitoring, an efficient path planning algorithm is essential for robotic inspection of large surfaces using computer vision. In this work, we first formulate the inspection path planning problem as an extended travelling salesman problem (TSP) in which both the coverage and obstacle avoidance were taken into account. An enhanced discrete particle swarm optimization (DPSO) algorithm is then proposed to solve the TSP, with performance improvement by using deterministic initialization, random mutation, and edge exchange. Finally, we take advantage of parallel computing to implement the DPSO in a GPU-based framework so that the computation time can be significantly reduced while keeping the hardware requirement unchanged. To show the effectiveness of the proposed algorithm, experimental results are included for datasets obtained from UAV inspection of an office building and a bridge.Manh Duong Phungduongpm@vnu.edu.vnCong Hoang QuachTran Hiep Dinhtranhiep.dinh@vnu.edu.vnHa Quangquang.ha@uts.edu.au2017-06-12T04:06:16Z2017-06-12T04:06:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2494This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24942017-06-12T04:06:16ZRobust Global Optimization of Electromagnetic Devices With Uncertain Design Parameters: Comparison of the Worst Case Optimization Methods and Multiobjective Optimization Approach Using Gradient IndexThe uncertainties in design variables are unavoidable in the optimal design of electromagnetic devices, and there is an imperative demand to find a robust design, which is insensitive to the uncertainties and remains within the feasible region of constraints even perturbed by the uncertainties. In this paper, a gradient-based worst case optimization (G-WCO) algorithm is proposed in a limited uncertainty set to increase the numerical efficiency based on the worst case optimization (WCO) algorithm. Through applications to the robust optimal design of TEAM 22, the performances of the proposed G-WCO, conventional WCO, and multiobjective optimization approach using gradient index (GI) are compared.Z. RenMinh Trien Phamtrienpm@vnu.edu.vnChang Seop Koh2017-06-12T04:05:36Z2017-06-12T04:05:36Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2493This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24932017-06-12T04:05:36ZMultiguiders and Nondominate Ranking Differential Evolution Algorithm for Multiobjective Global Optimization of Electromagnetic ProblemsThe differential evolution (DE) algorithm was initially developed for single-objective problems and was shown to be a fast, simple algorithm. In order to utilize these advantages in real-world problems it was adapted for multiobjective global optimization (MOGO) recently. In general multiobjective differential evolutionary algorithm, only use conventional DE strategies, and, in order to optimize performance constrains problems, the feasibility of the solutions was considered only at selection step. This paper presents a new multiobjective evolutionary algorithm based on differential evolution. In the mutation step, the proposed method which applied multiguiders instead of conventional base vector selection method is used. Therefore, feasibility of multiguiders, involving constraint optimization problems, is also considered. Furthermore, the approach also incorporates nondominated sorting method and secondary population for the nondominated solutions. The propose algorithm is compared with resent approaches of multiobjective optimizers in solving multiobjective version of Testing Electromagnetic Analysis Methods (TEAM) problem 22.N. BaatarMinh Trien Phamtrienpm@vnu.edu.vnChang Seop Koh2017-06-12T04:03:31Z2017-06-12T04:04:31Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2491This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24912017-06-12T04:03:31ZA Global Optimization Algorithm for Electromagnetic Devices by Combining Adaptive Taylor Kriging and Particle Swarm OptimizationAbstract:
This paper presents an efficient optimization strategy which employs adaptive Taylor Kriging and Particle Swarm Optimization (PSO). In this method, the objective function of electromagnetic problem is interpolated by using adaptive Taylor Kriging, in which the covariance parameter is obtained by Maximum Likelihood Estimation (MLE). And then, PSO is used to search for optimal solutions of electromagnetic problem. The proposed algorithm is verified its validity by analytic functions and TEAM (Testing of Electromagnetic Analysis Method) problem 22.Bin XiaMinh Trien Phamtrienpm@vnu.edu.vnY. ZhangChang Seop Koh2017-06-10T11:54:35Z2017-12-07T06:51:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2490This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24902017-06-10T11:54:35ZAES datapath optimization strategies for low-power low-energy multi-security-level Internet-of-Thing applicationsConnected devices are getting attention because of the lack of security mechanisms in current Internet-of-Thing (IoT) products. The security can be enhanced by using standardized and proven-secure block ciphers as Advanced Encryption Standard (AES) for data encryption and authentication. However, these security functions take a large amount of processing power and power/energy consumption. In this paper, we present our hardware optimization strategies for Advanced Encryption Standard (AES) for high speed, ultra-low power, ultra-low energy IoT applications with multiple levels of security. Our design supports multiple security levels through different key sizes, power and energy optimization for both datapath and
key expansion. The estimated power results show that our
implementation may achieve an energy per bit comparable with
the lightweight standardized algorithm PRESENT of less than
1pJ/bit at 10MHz at 0.6V with throughput of 28Mbps in ST
FDSOI 28nm technology. In terms of security evaluation, our
proposed datapath, 32-bit key out of 128 bits cannot be revealed by Correlation Power Analysis (CPA) attack using less than 20 thousand traces.Duy Hieu Buihieubd@vnu.edu.vnDiego Puschinidiego.puschini@cea.frSimone Bacles-MinSimone.BACLES-MIN@cea.frEdith Beigneedith.beigne@cea.frXuan Tu Trantutx@vnu.edu.vn2017-06-10T11:42:34Z2017-06-10T11:42:34Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2473This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24732017-06-10T11:42:34ZBisimilarity for paraconsistent description logicsWe introduce comparisons w.r.t. information between interpretations in paraconsistent description logics and use them to define bisimilarity for such logics. This notion is useful for concept learning in description logics when inconsistencies occur. We give preservation results and the Hennessy-Milner property for comparisons w.r.t. information in paraconsistent description logics. As consequences, we obtain also invariance results and the Hennessy-Milner property for bisimilarity in paraconsistent description logics.Linh Anh NguyenThi Hong Khanh NguyenNgoc Thanh NguyenQuang Thuy Hathuyhq@vnu.edu.vnNgoc Thanh NguyenManuel NúñezBogdan Trawiński2017-06-10T11:39:14Z2017-06-10T11:39:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2481This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24812017-06-10T11:39:14ZA formal approach to checking consistency in software refactoringIn software development, refactoring is a process that improves the system internal structure without altering its external behavior. Applying design patterns, which are common reusable solutions of several kinds of problems is widely adopted. This technique, however, raises a challenging issue that after applying design patterns the software system may not preserve some certain behavioral properties. This paper proposes a new approach to checking consistency between original software system and its evolution at both design and implementation phases. First, we formalize elements of software designs and programs. Methods, based on these formalizations, are proposed for verifying the design and implementation of the system. Finally, the paper presents a case study of Adaptive Road Traffic Control system to illustrate the proposed approach in detail.Hong Anh Leanhfit@gmail.comThi Huong DaoNinh Thuan Truongthuantn@vnu.edu.vn2017-06-10T11:32:27Z2017-06-10T11:32:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2472This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24722017-06-10T11:32:27ZSieve-based coreference resolution enhances semi-supervised learning model for chemical-induced disease relation extractionThe BioCreative V chemical-disease relation (CDR) track was proposed to accelerate progress of text mining in facilitating integrative understanding ofchemical substances, diseases and their relations. In this article, we describe an extension of the UET-CAM system for mining chemical-disease relations from text data, of which performance was ranked 4th among 18 participating corresponding systems by the BioCreative CDR track committee. In Disease Named Entity Recognition and Normalization (DNER) phase, our system employs joint learning with a perceptron-based named entity recognizer (NER) and a back-off model with Semantic Supervised Indexing (SSI) and Skip-gram for named entity normalization (NEN). Crucially, for solving the chemical-induced disease (CID) sub-task, we propose a pipeline that includes a coreference resolution module and a SVM intra-sentence relations extraction model. The former module utilizes a multi-pass sieve to identify inter-sentence references for entities while the latter is trained on both the CDR data and our silverCID corpus with a rich feature set. SilverCID is the silver standard corpus contains more than 50 thousands sentences which are automatically built based on the CTD database in order to provide evidence for the CID relation extraction. We critically evaluated our method on the CDR test set in order to clarify the contribution of our system components. Results show an F1 of 82.44 for the DNER task, and a best performance of F1 58.90 on the CID task. The comparisons also demonstrate the significant contribution of the multi-pass sieve coreference resolution method and the silverCID corpus.Hoang Quynh Lelhquynh@gmail.comMai Vu Tranvutm@vnu.edu.vnThanh Hai Danghai.dang@vnu.edu.vnQuang Thuy Hathuyhq@vnu.edu.vnNigel Collier2017-06-09T11:37:33Z2017-06-09T11:37:33Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2485This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24852017-06-09T11:37:33ZSecond-order optimization based adaptive PARAFAC decomposition of three-way tensorsA fast adaptive parallel factor (PARAFAC) decomposition algorithm is proposed for a class of third-order tensors that have one dimension growing linearly with time. It is based on an alternating least squares approach in conjunction with a Newton-type optimization technique. By preserving the Khatri-Rao product and exploiting the the reduced-rank update structure of the estimated subspace at each time instant, the algorithm achieves linear complexity and superior convergence performance. A modified version of the algorithm is also proposed to deal with the non-negative constraint. In addition, parallel implementation issues are investigated. Finally, the performance of the algorithm is numerically studied and compared to several state-of-the-art algorithms.Viet Dung Nguyennvdung@vnu.edu.vnKarim Abed-Meraimkarim.abed-meraim@univ-orleans.frLinh Trung Nguyenlinhtrung@vnu.edu.vn2017-06-09T11:34:48Z2017-06-09T11:34:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2484This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24842017-06-09T11:34:48ZGeneralized minimum noise subspace for array processingBased on the minimum noise subspace (MNS) method previously introduced in the context of blind channel identification, generalized minimum noise subspace (GMNS) is proposed in this paper for array processing that generalizes MNS with respect to the availability of only a fixed number of parallel computing units. Different batch and adaptive algorithms are then introduced for fast and parallel computation of signal (principal) and noise (minor) subspaces. The computational complexity of GMNS and its related estimation accuracy are investigated by simulated experiments and a real-life experiment in radio astronomy. It is shown that GMNS represents an excellent tradeoff between the computational gain and the subspace estimation accuracy, as compared to several standard subspace methods.Viet Dung Nguyennvdung@vnu.edu.vnKarim Abed-Meraimkarim.abed-meraim@univ-orleans.frLinh Trung Nguyenlinhtrung@vnu.edu.vnRodolphe Weberweberrod@gmail.com2017-06-09T11:26:58Z2017-06-09T11:26:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2480This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24802017-06-09T11:26:58ZDevelopment of a Real Time Supported Program for Motorbike Drivers Using Smartphone Built-in SensorsUsing mobile phones during traffic progress is one of the main causes traffic accidents because drivers do not focus on driving, they try to listen phone calls or to text some messages... Most of research work has focused to car driving. However, using motorbike is very popular in some developing countries such as Vietnam, India, etc. Up to now, there are just a few works, which focus to motorbike driving with obvious limitations. Thus, in this research, we proposed a complete solution for bikers who own a smartphone. Our work exploits the information from built-in sensors in Android smartphone. A complete scheme for motorbike driving is proposed. In this scheme, the user state is detected by improving the current Google activity recognition API. If the state is “On vehicle”, the phone automatically switches to silent mode and send to the caller an SMS. Our work provides a mechanism to receive the calls from VIP contacts and urgent calls. The phone would switch back to the normal mode if the state is not "On vehicle". Furthermore, it sends the accident location to the relatives when an accident occurs to save their lives automatically. The application was tested carefully and it can be used to protect the lives of motorbike drivers.Pham Van Thanhphamvanthanh1209@gmail.comTien-Anh Nguyenanhnt007@gmail.comNghia Tran Ducnghiatranduc1986@yahoo.comNguyen Duc Anhanhnd@gmail.comTran Duc-Tantantd@vnu.edu.vn2017-06-09T11:26:45Z2018-01-10T08:00:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2479This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24792017-06-09T11:26:45ZDeterministic compressive sampling for high-quality image reconstruction of ultrasound tomographyBackground
A well-known diagnostic imaging modality, termed ultrasound tomography, was quickly developed for the detection of very small tumors whose sizes are smaller than the wavelength of the incident pressure wave without ionizing radiation, compared to the current gold-standard X-ray mammography. Based on inverse scattering technique, ultrasound tomography uses some material properties such as sound contrast or attenuation to detect small targets. The Distorted Born Iterative Method (DBIM) based on first-order Born approximation is an efficient diffraction tomography approach. One of the challenges for a high quality reconstruction is to obtain many measurements from the number of transmitters and receivers. Given the fact that biomedical images are often sparse, the compressed sensing (CS) technique could be therefore effectively applied to ultrasound tomography by reducing the number of transmitters and receivers, while maintaining a high quality of image reconstruction.
Methods
There are currently several work on CS that dispose randomly distributed locations for the measurement system. However, this random configuration is relatively difficult to implement in practice. Instead of it, we should adopt a methodology that helps determine the locations of measurement devices in a deterministic way. For this, we develop the novel DCS-DBIM algorithm that is highly applicable in practice. Inspired of the exploitation of the deterministic compressed sensing technique (DCS) introduced by the authors few years ago with the image reconstruction process implemented using l 1 regularization.
Results
Simulation results of the proposed approach have demonstrated its high performance, with the normalized error approximately 90% reduced, compared to the conventional approach, this new approach can save half of number of measurements and only uses two iterations. Universal image quality index is also evaluated in order to prove the efficiency of the proposed approach.
Conclusions
Numerical simulation results indicate that CS and DCS techniques offer equivalent image reconstruction quality with simpler practical implementation. It would be a very promising approach in practical applications of modern biomedical imaging technology.Huy Tran Quangtranquanghuysp2@gmail.comTue Huynh Huuhhtue@hcmiu.edu.vnLong Ton Thatttlong@hcmiu.edu.vnDuc Tan Trantantd@vnu.edu.vn2017-06-03T10:07:05Z2017-08-08T14:50:22Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2468This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24682017-06-03T10:07:05ZAXI-NoC: High-Performance Adaptation Unit for ARM Processors in Network-on-Chip ArchitecturesThe increasing demand on scalability and reusability of system-on-chip design as well as the decoupling between computation and communication has motivated the growth of the Network-on-Chip (NoC) paradigm in the last decade. In NoC-based systems, the computational resources (i.e. IPs) communicate with each other using a network infrastructure. Many works have focused on the development of NoC architectures and routing mechanisms, while the interfacing between network and associated IPs also needs to be considered. In this paper, we present a novel efficient AXI (AMBA eXtensible Interface) compliant network adapter for NoC architectures, which is named an AXI-NoC adapter. The proposed network adapter achieves high communication throughput of 20.8Gbits/s and consumes 4.14mW at the operating frequency of 650MHz. It has a low area footprint (952 gates, approximate to 2,793um2 with CMOS 45nm technology) thanks to its effective hybrid micro-architectures and with zero latency thanks to the proposed mux-selection method.Xuan Tu Trantutx@vnu.edu.vnTung NguyenHai Phong Phanhaiphongphan@gmail.comDuy Hieu Buihieubd@vnu.edu.vn2017-03-06T04:23:11Z2019-01-14T02:54:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2417This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24172017-03-06T04:23:11ZNonlinear dynamic response and vibration of sandwich composite plates with negative Poisson’s ratio in auxetic honeycombsAuxetic cellular solids in the forms of honeycombs under blast load have great potential in a diverse range of applications, including core material in sandwich plates composite components. Based on Reddy’s first-order shear deformation plate theory, this paper presents an analysis of the nonlinear dynamic response and vibration of sandwich plates with negative Poisson’s ratio in auxetic honeycombes on elastic foundations subjected to blast and mechanical loads. A three-layer sandwich plate is considered discretized in the thickness direction by using analytical methods (stress function method, approximate solution), Galerkin method, and fourth-order Runge-Kutta method. The results show the effects of geometrical parameters, material properties, mechanical and elastic foundations on the nonlinear dynamic response, and vibration of sandwich plates.Dinh Duc Nguyenducnd@vnu.edu.vnHong Cong Pham2017-02-06T15:50:58Z2017-02-06T15:50:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2409This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24092017-02-06T15:50:58ZThe nonlinear dynamic and vibration of the S-FGM shallow spherical shells resting on an elastic foundations including temperature effectsThis study investigated the nonlinear dynamic and vibration of the S-FGM shallow spherical shells with ceramic-metal-ceramic layers (in two cases: non-axisymmetric and axisymmetric shells) on an elastic foundations (EF) with different types of boundary conditions in thermal environment. Material compositions of the shell are graded in the thickness direction according to a sigmoid law distribution in terms of the volume fractions of the constituents. The governing equations are derived by using the classical shell theory and Pasternak's two parameters EF. The motion equations of dynamic analysis are determined due to Galerkin method and the obtained equation is numerically solved by using Runge–Kutta method. The approximate solutions are assumed to satisfy the different types of boundary conditions. The criterion suggested by Budiansky–Roth is applied to determine the dynamic critical buckling load and the nonlinear dynamic response is found by numerical form. In numerical results, the effects of geometrical parameters, material properties, the EF, boundary conditions, mechanical loads and temperature on the nonlinear dynamic and vibration stability of the shells are investigated.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Quang Vuquangvd2510@gmail.comThi Thuy Anh Vuanhvutt@vnu.edu.vn2017-01-10T03:51:49Z2017-01-10T03:51:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2396This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23962017-01-10T03:51:49ZTowards the implenmentation of an assessment-centered blended learning framework at the course level: a case study in a Vietnamese national universityViet Anh Nguyenvietanh@vnu.edu.vn2017-01-08T08:08:24Z2017-01-08T08:08:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2398This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23982017-01-08T08:08:24ZIon Wind Generator Utilizing Bipolar Discharge in Parallel Pin GeometryThanh Van Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpTerebessy Tibortibor.terebessy@clearviewtraffic.comThanh Tung Buitungbt@vnu.edu.vn2017-01-08T08:07:48Z2017-01-08T08:07:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2397This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23972017-01-08T08:07:48ZBipolar corona assisted jet flow for fluidic applicationVan Thanh Daudauv@sc.sumitomo-chem.co.jpThien Xuan Dinhthien@cfd.ritsumei.ac.jpThanh Tung Buitungbt@vnu.edu.vnTibor Terebessytibor.terebessy@clearviewtraffic.com2017-01-06T07:07:58Z2017-01-06T07:07:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2395This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23952017-01-06T07:07:58ZA peer assessment approach to project based blended learning course in a Vietnamese higher educationThis article presents a model using peer assessment to evaluate students taking part in blended - learning courses (BL). In these courses, teaching activities are carried out in the form of traditional face-to-face (F2F) and learning activities are performed online via the learning management system Moodle. In the model, the topics of courses are built as a set of projects and case studies for the attending students divided into groups. The result of the implementation of projects is evaluated and ranked by all course participants and is one of the course evaluation criteria for lecturers. To assess learners more precisely, we propose a multi-phase assessment model in evaluating all groups and the group members. The result of each student in the group based on himself evaluation, evaluations of the team members, the tearcher and all students in the course. There are 107 students, who participated in the course entitled ``web application development'', are divided into 20 groups conducting the course in the field of information technology is deployed in the form of blended learning through peer assessment. The results of student's feedback suggested that the usage of various peer assessment created positive learning effectiveness and more interesting learning attitude for students. The survey was conducted with the students through the questionnaire, each question with scale 5-point Likert scale that ranged from 1 (very unsatisfied) to 5 (very statisfied) to investigate the factors: Collaboration, Assessment, Technology showed that students were satisfied with our approach.Viet Anh Nguyenvietanh@vnu.edu.vn2017-01-05T02:33:16Z2017-01-05T02:33:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2285This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22852017-01-05T02:33:16ZOn the nonlinear stability of eccentrically stiffened functionally graded annular spherical segment shellsDinh Duc Nguyenducnd@vnu.edu.vnHuy Bich DaoThi Thuy Anh Vuanhvutt@vnu.edu.vn2017-01-05T02:31:33Z2017-01-05T02:31:33Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2282This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22822017-01-05T02:31:33ZOn the linear stability of eccentrically stiffened functionally graded annular spherical shell on elastic foundationsThi Thuy Anh Vuanhvutt@vnu.edu.vnHong Cong PhamHuy Bich DaoDinh Duc Nguyenducnd@vnu.edu.vn2017-01-04T13:42:09Z2017-01-04T13:42:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2389This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/23892017-01-04T13:42:09ZA Comprehensive Lighting Configuration for Efficient Indoor
Visible Light Communication NetworksDesign of an efcient indoor visible light communication (VLC) system requires careful considerations on both illumination and
communication aspects. Besides fundamental factors such as received power and signal-to-noise ratio (SNR) level, studies on
mobility scenarios and link switching process must be done in order to achieve good communication link quality in such systems.
In this paper, a comprehensive lighting confguration for efcient indoor VLC systems for supporting mobility and link switching
with constraint on illumination, received power, and SNR is proposed. Full connectivity in mobility scenarios is required to make
the system more practical. However, diﬀerent from other literatures, our work highlights the signifcance of recognizing the main
inﬂuences of feld of view angle on the connectivity performance in the practical indoor scenarios. A ﬂexible link switching initiation
algorithm based on the consideration of relative received power with adaptive hysteresis margin is demonstrated. In this regard, we
investigate the eﬀect of the overlap area between two light sources with respect to the point view of the receiver on the link switching
performance. Te simulation results show that an indoor VLC system with sufcient illumination level and high communication
link quality as well as full mobility and support link switching can be achieved using our approach.Thai-Chien Buiuetchien@gmail.comSuwit Kiravittayasuwitki@gmail.comKeattisak Sripimanwatkeattisak.sripimanwat@gmail.comNam Hoang Nguyenhoangnn@vnu.edu.vn2017-01-04T07:21:16Z2017-01-04T07:21:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2246This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22462017-01-04T07:21:16ZFluidic lens by using thermal lens effectHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnYoshihiko AkamineKazuyoshi Fushinobu2017-01-04T07:20:40Z2017-01-04T07:20:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2245This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22452017-01-04T07:20:40ZFinite-Difference Time Domain Analysis of Ultrashort Pulse Laser Light Propagation under Nonlinear CouplingYoshihiko AKAMINEHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnKazuyoshi FUSHINOBU2017-01-04T07:20:02Z2017-01-04T07:20:02Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2244This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22442017-01-04T07:20:02ZGeneration of Bessel Beam by Using Thermal LensHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnYoshihiko AKAMINENaoki IWATANIMasamichi KOHNOKazuyoshi FUSHINOBU2017-01-04T07:19:27Z2017-01-04T07:19:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2243This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22432017-01-04T07:19:27ZFundamental investigation of fluidic optical devices: Transmission characteristics of laser beam in 1D temperature field of liquid mediumHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnKazuyoshi FushinobuKen Okazaki2017-01-04T07:18:57Z2017-01-04T07:18:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2239This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22392017-01-04T07:18:57ZOptimization of near-infrared laser drilling of silicon carbide under waterNaoki IwataniHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnKazuyoshi Fushinobu2017-01-04T07:18:24Z2017-01-04T07:18:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2222This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22222017-01-04T07:18:24ZInfluence of natural convection on beam propagation in fluidic optical deviceByunggi KimHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnKazuyoshi Fushinobu2017-01-04T03:26:58Z2017-01-04T03:26:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2221This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22212017-01-04T03:26:58ZOn the thermal buckling analysis of functionally graded plates with internal defects using extended isogeometric analysisTiantang YuQuoc Tinh BuiShuohui YinHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnC.T. WuVan Thom DoSatoyuki Tanaka2017-01-04T03:25:53Z2017-01-04T03:25:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2220This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22202017-01-04T03:25:53ZBessel beam laser-scribing of thin film silicon solar cells by ns pulsed laserHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnRyoichi IIDAByunggi KIMIsao SATOHKazuyoshi FUSHINOBU2016-12-31T14:13:53Z2016-12-31T14:13:53Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2219This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22192016-12-31T14:13:53ZOn the high temperature mechanical behaviors analysis of heated functionally graded plates using FEM and a new third-order shear deformation plate theoryQuoc Tinh BuiVan Thom DoLan Hoang That TonHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnSatoyuki TanakaDat Tien PhamThien-An Nguyen-VanTiantang YuSohichi Hirose2016-12-31T14:12:06Z2016-12-31T14:12:06Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2218This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22182016-12-31T14:12:06ZHybrid phase field simulation of dynamic crack propagation in functionally graded glass-filled epoxyHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnQuoc Tinh BuiDinh Duc Nguyenducnd@vnu.edu.vnKazuyoshi Fushinobu2016-12-31T14:09:17Z2016-12-31T14:09:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2216This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22162016-12-31T14:09:17ZMechanism of TCO thin film removal process using near-infrared ns pulse laser: Plasma shielding effect on irradiation directionByunggi KimRyoichi IidaHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnKazuyoshi Fushinobu2016-12-31T14:08:09Z2016-12-31T14:08:09Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2215This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22152016-12-31T14:08:09ZEnhanced nodal gradient 3D consecutive-interpolation tetrahedral element (CTH4) for heat transfer analysisMinh Ngoc NguyenQuoc Tinh BuiThien Tich TruongNgoc Anh TrinhIndra Vir SinghTiantang YuHong Duc Doandoan.hd.amsl.eng@vnu.edu.vn2016-12-31T14:06:47Z2016-12-31T14:06:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2214This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22142016-12-31T14:06:47ZNumerical modeling of 3-D inclusions and voids by a novel adaptive XFEMZhen WangTiantang YuQuoc Tinh BuiNgoc Anh TrinhThi Hien Luong NguyenDinh Duc Nguyenducnd@vnu.edu.vnHong Duc Doandoan.hd.amsl.eng@vnu.edu.vn2016-12-31T14:05:15Z2016-12-31T14:05:15Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2213This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22132016-12-31T14:05:15ZNanosecond pulse laser scribing using Bessel beam for single shot removal of transparent conductive oxide thin filmByunggi KimRyoichi IidaHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnKazuyoshi Fushinobu2016-12-31T10:21:25Z2016-12-31T10:21:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2211This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22112016-12-31T10:21:25ZDetection of magnetic nanoparticles using simple AMR sensors in Wheatstone bridgeWheatstone bridges incorporating a serially connected ensemble of simple AMR elements of Ni80Fe20 film were produced, targeting an application of a pinned magnetic field along the sensing magnetoresistor length. For the optimal dimension, the magnetoresistive element with length l 4 µm, width 150 µm and thickness 5 nm still shows a rather modest AMR ratio (of about 0.85% only). However, the resulting bridge exhibits a sensitivity as large as 2.15 mV/Oe. This is according to a standard sensitivity of 1.80 mV/V/Oe and a detection limit better than 10_6 emu, which is almost doubled with respect to that in the typical commercial AMR devices and is comparable with Permalloy based PHE sensor. This is suitable to detect the superparamagnetic fluid of 50 nm-Fe3O4-chitosan.Khac Quynh LeDinh Tu Buibuidinhtu@vnu.edu.vnXuan Dang DangQuoc Viet DongThi Hien Lelehien@vnu.edu.vnThi Huong Giang Dogiangdth@vnu.edu.vnHuu Duc Nguyenducnh@vnu.edu.vn2016-12-31T10:19:45Z2016-12-31T10:19:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2207This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/22072016-12-31T10:19:45ZNonlinear response of a shear deformable SFGM shallow spherical shell with ceramic-metalceramic layers resting on an elastic foundation in a thermal environmentThis article presents an analytical approach to investigate the nonlinear stability of thick, functionally graded material (FGM) shallow spherical shells resting on elastic foundations, subjected to uniform external pressure and exposed to thermal environments. Material properties are assumed to be temperature dependent and graded in the thickness direction according to a Sigmoid power law distribution (S-FGM) in terms of the volume fractions of constituents. Using the first-order shear deformation theory and the Galerkin method, the effects of materials, geometry, elastic foundation parameters, and temperature on the nonlinear response of the thick S-FGM shells are analyzed and discuss