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nonlinear dynamic analysis of functionally graded carbon nanotube-reinforced composite plates using MISQ20 element

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Frontiers of Structural and Civil Engineering 2023年第7期17卷 1072-1085页

作者： Quoc-Hoa PHAM Trung thanh TRAn Phu-Cuong nguyen Advanced Structural Engineering Laboratory Department of Structural EngineeringFaculty of Civil EngineeringHo Chi Minh City Open UniversityHo Chi Minh City 700000Vietnam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoi 100000Vietnam

The main objective of this study is to further extend the mixed integration smoothed quadrilateral element with 20 unknowns of displacement(MISQ20)to investigate the nonlinear dynamic responses of functionally graded carbon nanotube-reinforced composite(FG-CnTRC)plates with four types of carbon nanotube *** smooth finite element method is used to enhance the accuracy of the Q4 element and avoid shear locking without using any shear correction *** method yields accurate results even if the element exhibits a concave quadrilateral shape and reduces the error when the element meshing is ***,the element stiffness matrix is established by integrating the boundary of the smoothing *** motion equation of the FG-CnTRC plates is solved by adapting the newmark method combined with the newton–Raphson ***,the calculation program is coded in the MATLAB software and verified by comparing it with other published ***,the effects of the input parameters on the nonlinear vibration of the plates are investigated.

关键词： carbon nanotube MISQ20 FG-CnTRC plate nonlinear vibration nonlinear dynamic analysis SFEM

Static and free vibration analyses of functionally graded porous variable-thickness plates using an edge-based smoothed finite element method

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Defence Technology（防务技术） 2021年第3期17卷 971-986页

作者： Trung thanh Tran Quoc-Hoa Pham Trung nguyen-Thoi Department of Mechanics Le Quy Don Technical UniversityHanoiViet Nam Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityViet Nam

The main purpose of this paper is to present numerical results of static bending and free vibration of functionally graded porous(FGP) variable-thickness plates by using an edge-based smoothed finite element method(ES-FEM) associate with the mixed interpolation of tensorial components technique for the three-node triangular element(MITC3), so-called ES-MITC3. This ES-MITC3 element is performed to eliminate the shear locking problem and to enhance the accuracy of the existing MITC3 element. In the ES-MITC3 element, the stiffness matrices are obtained by using the strain smoothing technique over the smoothing domains formed by two adjacent MITC3 triangular elements sharing an edge. Materials of the plate are FGP with a power-law index(k) and maximum porosity distributions(U) in the forms of cosine functions. The influences of some geometric parameters, material properties on static bending, and natural frequency of the FGP variable-thickness plates are examined in detail.

关键词： Functionally graded porous(FGP)plates Edge-based smoothed finite element method(ES-FEM) Mixed interpolation of tensorial components(MITC) Static bending Free vibration

Structural and luminescent properties of (Eu,Tb) PO_4·H_2O nanorods/nanowires prepared by microwave technique

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Journal of Rare Earths 2011年第12期29卷 1170-1173页

作者： nguyen thanh Huong nguyen Duc Van Dinh Manh Tien Do Khanh Tung nguyen thanh Binh Tran Kim Anh Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology University of Engineering and Technology National University HanoiVietnam

nanowires/nanorods of europium/terbium orthophosphate monohydrate with Eu^3＋ concentration of 6, 11, and 20 at.% were prepared by microwave synthesis method. The effects of Eu^3＋ doping concentration on structure, morphology and optical properties of nanomaterials were also investigated. The results showed that, for all studied Eu^3＋ doping concentrations, a single-crystalline phase of rhabdophane-type （Eu,Tb）PO4·H2O nanowires/nanorods was obtained by using microwave heating of an aqueous solution of terbium（Ⅲ） nitrate, europium（Ⅲ） nitrate and nH4H2PO4 with pH=2. The length and width of these nanowires/nanorods ranged from 150 to 300 nm and from 10 to 50 nm, respectively. The evidence of energy transfer from Tb^3＋ to Eu^3＋ due to the energy overlap between the donor Tb^3＋ and the acceptor Eu^3＋was observed obviously via a significant enhancement in the luminescent intensity of Eu^3＋. Keywords：

关键词： microwave technique nanowires/nanorods energy transfer fluorescence spectroscopy rare earths

A Truck Scheduling Problem for Multi-Crossdocking System with Metaheuristics

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Computers, Materials & Continua 2022年第9期72卷 5165-5178页

作者： Phan nguyen Ky Phuc nguyen Van thanh Duong Bao Tram International University-Vietnam national University Vietnam National UniversityHoChiMinh City70000Vietnam Faculty of Commerce Van Lang UniversityHo Chi Minh City70000Vietnam

The cross-docking is a very important subject in logistics and supply chain *** to the definition,cross-docking is a process dealing with transhipping inventory,in which goods and products are unloaded from an inbound truck and process through a flow-center to be directly loaded onto an outbound ***-docking is favored due to its advantages in reducing the material handing cost,the needs to store the product in warehouse,as well decreasing the labor cost by eliminating packaging,storing,pick-location and order *** cross-docking,products can be consolidated and transported as a full load,reducing overall distribution *** this paper,we focus on a truck scheduling at the multidoor,multi-crossdocking network with inventory constraints and process capability *** this model,a truck can visit severals docks for loading or unloading many types *** situation is very common in *** study also developed an exact mathematical model using mixedinteger linear programming(MILP)with the objective of minimizing the makespan to obtaint the benchmark in small scale *** scale problems are solved through Simulated Annealing(SA)algorithm and Tabu Search(TS)*** of these algorithms will be compared to benchmarks obtained from solver as well as to each other.

关键词： Truck scheduling multi-door multi-crossdocking network simulated annealing tabu search

Designing Software to Analyze Sewing Process of Industrial Knitted Products

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Computer Systems Science & Engineering 2023年第2期44卷 1837-1852页

作者： Phan thanh Thao nguyen thanh Hung Pham Thi Le My nguyen Xuan Hiep Duy-nam Phan Hanoi University of Science and Technology Hanoi10000Vietnam

In the textile industry,garment manufacturing contains four major pro-cesses containing cutting,sewing,ﬁnishing,and *** is the most crucial and intricate section,dealing with a large number of varied operations.A successful sewing process needs to be optimized regarding different factors,including time,sewing equipment,and skilled *** lineﬂow is combined by a set of operations with a particular *** utmost impor-tance of all garment industry is to arrange the workstations to minimize the num-ber of employees in order to produce at the best productive rate with the most reasonable cost,shortest time,and satisfying *** most garment factories,the production lines are balanced using the empirical judgment of the line *** the whole process the data of production time at each step,labor pro-ductivity,proper choices of equipment were always needed to calculate line efﬁ*** far as the issue is concerned,there has not been an academically sewing process analyzing software providing adequate data of sewing motions and sewing time as the credible input for the line balancing *** this goal,this paper presents the results of research on optimizing academically self-built software to analyze the sewing process of knitted products applied to industrial production using Java programming language on Google *** results achieved by the software are not only to analyze sewing products and the technological sewing process,calculate the sewing time on the machine but also analyze the sewing activities of workers into manipulations,movements,and motions to calculate the preparation time for two typical knitted products,namely,Polo-Shirt and T-Shirt with the case studies at General Textile Garment Joint Stock Company Hanoi and Star Fashion Company Limited.

关键词： Sewing motion sewing time GSD MTM polo-shirt T-shirt sewing process sewing operation analyzing software

Beach Profiles Characteristics Along Giao Thuy and Hai Hau Coasts,Vietnam:A Field Study

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China Ocean Engineering 2012年第4期26卷 699-712页

作者： nguyen Viet thanh 郑金海张弛 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Harbor Coastal and Offshore Engineering Hohai University Faculty of Civil Engineering University of Transport and Communications

Giao Thuy and Hai Hau coasts are located in nam Dinh province, Vietnam, with a total coastline of 54.42 km in length. The sea-dike system has been seriously damaged and there have been many dike breaches which caused floods and losses. This situation is considered of a general representative for coastal area in the northern part of Vietnam. A variety of studies have shown that the gradient in the longshore sediment transport rate and the offshore fine sediment lost are the main mechanisms causing the beach erosion. This study presents a field investigation of the beach profiles at Giao Thuy and Hai Hau beaches. Three types of empirical functions for the equilibrium beach profile are applied and compared with the observations. Results show that all observed beach profiles can be described by a single function. However, one specific equilibrium profile equation is not sufficient to assess all beach profiles. In Section 1 of Giao Thuy and Section 3 of Hai Thinh beaches, beach profiles are consistent with the logarithmic function, while the exponential function fits well in Section 2. This difference is explained with respect to coastal morphology, sediment characteristics and hydrodynamic conditions which vary in site. An analysis of the validity of the beach profile functions is recommended for the numerical modeling and engineering designs in this area.

关键词： beach profile field study power function exponential function logarithmic function

OPT-BAG Model for Predicting Student Employability

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Computers, Materials & Continua 2023年第8期76卷 1555-1568页

作者： Minh-thanh Vo Trang nguyen Tuong Le Faculty of Information Technology HUTECH UniversityHo Chi Minh CityVietnam Faculty of Information Technology Ho Chi Minh City Open UniversityHo Chi Minh CityVietnam Laboratory for Artificial Intelligence Institute for Computational Science and Artificial IntelligenceVan Lang UniversityHo Chi Minh CityVietnam Faculty of Information Technology School of TechnologyVan Lang UniversityHo Chi Minh CityVietnam

The use of machine learning to predict student employability is important in order to analyse a student’s capability to get a *** on the results of this type of analysis,university managers can improve the employability of their students,which can help in attracting students in the *** addition,learners can focus on the essential skills identified through this analysis during their studies,to increase their *** effectivemethod calledOPT-BAG(OPTimisation of BAGging classifiers)was therefore developed to model the problem of predicting the employability of *** model can help predict the employability of students based on their competencies and can reveal weaknesses that need to be ***,we analyse the relationships between several variables and the outcome variable using a correlation heatmap for a student employability ***,a standard scaler function is applied in the preprocessing module to normalise the variables in the student employability *** training set is then input to our model to identify the optimal parameters for the bagging classifier using a grid search cross-validation ***,the OPT-BAG model,based on a bagging classifier with optimal parameters found in the previous step,is trained on the training dataset to predict student *** empirical outcomes in terms of accuracy,precision,recall,and F1 indicate that the OPT-BAG approach outperforms other cutting-edge machine learning models in terms of predicting student *** this study,we also analyse the factors affecting the recruitment process of employers,and find that general appearance,mental alertness,and communication skills are the most *** indicates that educational institutions should focus on these factors during the learning process to improve student employability.

关键词： Ensemble classifier grid search cross-validation OPT-BAG student employability

On A nOnLInEAR VOLTERRA-HAMMERSTEIn InTEGRAL EQUATIOn In TWO VARIABLES

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Acta Mathematica Scientia 2013年第2期33卷 484-494页

作者： Le Thi Phuong ngoc nguyen thanh Long nhatrang Educational College 01 Nguyen Chanh Str.Nhatrang CityVietnam Department of Mathematics and Computer Science University of Natural ScienceVietnam National University Ho Chi Minh City227 Nguyen Van Cu Str.Dist. 5Ho Chi Minh CityVietnam

Using a fixed point theorem of Krasnosel＇skii type, this article proves the exis- tence of asymptotically stable solutions for a Volterra-Hammerstein integral equation in two variables.

关键词： Volterra-Hamnmrstein integral equation in two variables the fixed point theo-rem of Krasnosel'skii type contraction mapping completely continuous asymp-totically stable solution

Spatiotemporal Trend Analysis of Precipitation Extremes in Ho Chi Minh City, Vietnam During 1980–2017

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International Journal of Disaster Risk Science 2021年第1期12卷 131-146页

作者： nguyen Trong Quan Dao nguyen Khoi nguyen Xuan Hoan nguyen Ky Phung thanh Duc Dang Faculty of Environmental and Food Engineering Nguyen Tat Thanh UniversityHo Chi Minh City 700000Vietnam Faculty of Environment University of ScienceHo Chi Minh City 700000Vietnam Vietnam national University Ho Chi Minh City 700000Vietnam Ho Chi Minh City University of Food Industry Ho Chi Minh City 700000Vietnam Institute for Computational Science and Technology Ho Chi Minh City 700000Vietnam Engineering Systems and Design Pillar Singapore University of Technology and DesignTampines 487372Singapore

In this study,the spatiotemporal variability of trends in extreme precipitation events in Ho Chi Minh City during the period 1980–2017 was analyzed based on several core extreme precipitation indices(Rx1 day,Rx5 day,CDD,CWD,R20 mm,R25 mm,R95 p,and SDII).The nonparametric Mann–Kendall and Sen’s slope methods were used to compute the statistical strength,stability,and magnitude of trends in annual rainfall,as well as the extreme precipitation *** found that 64%of the stations had statistically significant upward trends in yearly rainfall,with high magnitudes frequently observed in the northern and southern regions of the *** the extreme precipitation indices,only SDII and R25 mm showed dominantly significant ***,there were increasing trends in the frequency and duration at the southern and central regions of the city during the study ***,El ni?o-Southern Oscillation and Pacific Decadal Oscillation positively correlated with the duration and negatively correlated with the intensity and frequency of extreme ***,water management plans should be adjusted appropriately to reduce the severe impacts of precipitation extremes on communities and ecosystems.

关键词： Spatiotemporal trend Extreme precipitation Extreme precipitation indices Ho Chi Minh City