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Frontiers of Structural and Civil Engineering 2024年第9期18卷 1401-1423页

作者： Thu Huong NGUYEN THI Van Ke tran quoc Hoa PHAM School of Mechanical and Automotive Engineering Hanoi University of IndustryHanoi 100000Vietnam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoi 100000Vietnam Faculty of Engineering and Technology Nguyen Tat Thanh UniversityHo Chi Minh City 700000Vietnam

This work uses isogeometric analysis(IGA),which is based on nonlocal hypothesis and higher-order shear beam hypothesis,to investigate the static bending and free oscillation of a magneto-electro-elastic functionally graded(MEE-FG)nanobeam subject to elastic boundary constraints(BCs).The magneto-electric boundary condition and the Maxwell equation are used to calculate the variation of electric and magnetic potentials along the thickness direction of the *** study is innovative since it does not use the conventional boundary ***,an elastic system of straight and torsion springs with controllable stiffness is used to support nanobeams’beginning and end positions,creating customizable *** governing equations of motion of nanobeams are established by applying Hamilton’s principle and IGA is used to determine deflections and natural frequency *** studies were performed to evaluate the convergence and accuracy of the proposed *** from this,the impact of the input parameters on the static bending and free oscillation of the MEE-FG nanobeam is examined in *** findings could be valuable for analyzing and designing innovative structures constructed of functionally graded MEE materials.

关键词： elastic boundary conditions isogeometric analysis nanobeam via nonlocal theory grading of magneto-electro-elastic functions

Free vibration analysis of functionally graded porous curved nanobeams on elastic foundation in hygro-thermo-magnetic environment

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Frontiers of Structural and Civil Engineering 2023年第4期17卷 584-605页

作者： quoc-Hoa PHAM Parviz MALEKZADEH Van Ke tran Trung NGUYEN-THOI Faculty of Engineering and Technology Nguyen Tat Thanh UniversityHo Chi Minh City 700000Vietnam Department of Mechanical Engineering Persian Gulf UniversityBushehr ***Iran Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoi 100000Vietnam Laboratory for Applied and Industrial Mathematics Institute for Computational Science and Artificial IntelligenceVan Lang UniversityHo Chi Minh City 700000Vietnam Faculty of Mechanical-Electrical and Computer Engineering School of TechnologyVan Lang UniversityHo Chi Minh City 700000Vietnam Bualuang ASEAN Chair Professor Thammasat School of EngineeringThammasat UniversityPathumtani 12120Thailand

Herein,a two-node beam element enriched based on the Lagrange and Hermite interpolation function is proposed to solve the governing equation of a functionally graded porous(FGP)curved nanobeam on an elastic foundation in a hygro–thermo–magnetic *** material properties of curved nanobeams change continuously along the thickness via a power-law distribution,and the porosity distributions are described by an uneven porosity *** effects of magnetic fields,temperature,and moisture on the curved nanobeam are assumed to result in axial loads and not affect the mechanical properties of the *** equilibrium equations of the curved nanobeam are derived using Hamilton’s principle based on various beam theories,including the classical theory,first-order shear deformation theory,and higher-order shear deformation theory,and the nonlocal elasticity *** accuracy of the proposed method is verified by comparing the results obtained with those of previous reliable ***,the effects of different parameters on the free vibration behavior of the FGP curved nanobeams are investigated comprehensively.

关键词： functionally graded porous material curved nanobeam hygro-thermo-magnetic enriched finite element method

Combining Entropy Optimization and Sobel Operator for Medical Image Fusion

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Computer Systems Science & Engineering 2023年第1期44卷 535-544页

作者： Nguyen Tu Trung tran Thi Ngan tran Manh tuan To Huu Nguyen Faculty of Computer Science and Engineering Thuyloi University175 Tay SonDong DaHanoi010000Vietnam University of Information and Communication Technology Thai Nguyen UniversityThai Nguyen240000Vietnam

Fusing medical images is a topic of interest in processing medical *** is achieved to through fusing information from multimodality images for the purpose of increasing the clinical diagnosis *** fusion aims to improve the image quality and preserve the specific *** methods of medical image fusion generally use knowledge in many differentfields such as clinical medicine,computer vision,digital imaging,machine learning,pattern recognition to fuse different medical *** are two main approaches in fusing image,including spatial domain approach and transform domain *** paper proposes a new algorithm to fusion multimodal *** algorithm is based on Entropy optimization and the Sobel *** transform is used to split the input images into components over the low and high frequency ***,two fusion rules are used for obtaining the fusing *** rule,based on the Sobel operator,is used for high frequency *** second rule,based on Entropy optimization by using Particle Swarm Optimization(PSO)algorithm,is used for low frequency *** algorithm is implemented on the images related to central nervous system *** experimental results of the paper show that the proposed algorithm is better than some recent methods in term of brightness level,the contrast,the entropy,the gradient and visual informationfidelity for fusion(VIFF),Feature Mutual Information(FMI)indices.

关键词： Medical image fusion wavelet entropy optimization PSO Sobel operator

A novel finite element formulation for static bending analysis of functionally graded porous sandwich plates

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Frontiers of Structural and Civil Engineering 2022年第12期16卷 1599-1620页

作者： Van Chinh NGUYEN Trung Thanh tran Trung NGUYEN-THOI quoc-Hoa PHAM Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoiVietnam Laboratory for Applied and Industrial Mathematics Institute for Computational Science and Artificial IntelligenceVan Lang UniversityHo Chi Minh CityVietnam Faculty of Mechanical-Electrical and Computer Engineering Van Lang UniversityHo Chi Minh CityVietnam Faculty of Engineering and Technology Nguyen Tat Thanh UniversityHo Chi Minh CityVietnam

This article aims to propose a finite element formulation based on Quasi-3D theory for the static bending analysis of functionally graded porous(FGP)sandwich *** FGP sandwich plates consist of three layers including the bottom skin of homogeneous metal,the top skin of fully ceramic and the FGP core layer with uneven porosity distribution.A quadrilateral(Q4)element with nine degrees of freedom(DOFs)per node is derived and employed in analyzing the static bending response of the plate under uniform and/or sinusoidally distributed *** accuracy of the present finite element formulation is verified by comparing the obtained numerical results with the published results in the ***,some numerical examples are performed to examine the effects of the parameters including power-law index k and porosity coefficient on the static bending response of rectangular FGP sandwich *** addition,a problem with a complicated L-shape model is conducted to illustrate the superiority of the proposed finite element method.

关键词： sandwich plates functionally graded porous static bending Quasi-3D theory Q4 element

Fabrication and characterization of YVO_4:Eu^(3+) nanomaterials by the microwave technique

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Journal of Rare Earths 2011年第12期29卷 1137-1141页

作者： tran Thu Huong Vu Duc Tu tran Kim Anh Le Thi Vinh Le quoc Minh Institute of Materials Science Vietnamese Academy of Science and Technology University of Engineering and Technology National University Hanoi Departments of Chemistry Hanoi University of Mining and Geology

Fabrication and characterization of YVO4：Eu^3＋ nanophosphors prepared by microwave （MW） irradiation assisted soft template synthesis were reported. The effects of synthesis conditions such as different powers of MW irradiation, pH values and concentration of reac- tion materials on properties of nanophosphor were also investigated to obtain the controllable size, morphology and high luminescence efficiency. Morphology, crystalline structure, and optical properties were characterized by field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD） and fluorescence spectroscopy, respectively. The results showed that YVOa：Eu^3＋ nanophosphors were obtained by using diethyleneglycol （DEG） as soft template, with pH values in the range of 4 to 12, upon microwave irradiation from 300 to 900 W, at temperature of 80 ℃. The high fluorescent YVOa：Eu^3＋ nanocrystals obtained with size from 15 nm down to 8 nm are more effective to develop an ultrahigh sensitive fluorescent label for biomolecule, cell and tissue.

关键词： microwave synthesis method DEG soft template YVO4:Eu^3+ nanophosphor luminescence rare earths

Isogeometric analysis for free vibration of bidirectional functionally graded plates in the fluid medium

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Defence Technology（防务技术） 2022年第8期18卷 1311-1329页

作者： quoc-Hoa Pham Phu-Cuong Nguyen Van Ke tran Trung Nguyen-Thoi Faculty of Civil Engineering Ho Chi Minh City Open UniversityHo Chi Minh CityViet Nam Faculty of Mechanical Engineering 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

This paper for first time proposes an isogeometric analysis (IGA) for free vibration response of bi-directional functionally graded (BDFG) rectangular plates in the fluid medium. Material properties of the BDFG plate change in both the thickness and length directions via power-law distributions and Mori-Tanaka model. The governing equation of motion of BDFG plate in the fluid-plate system is formulated basing on Hamilton's principle and the refined quasi three-dimensional (3D) plate theory with improved function f(z). The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to determine the added mass. The discrete system of equations is derived from the Galerkin weak form and numerically analyzed by IGA. The accuracy and reliability of the proposed solutions are verified by comparing the obtained results with those published in the literature. Moreover, the effects of the various parameters such as the interaction boundary condition, geometric parameter, submerged depth of plate, fluid density, fluid level, and the material volume control coefficients on the free vibration behavior of BDFG plate in the fluid medium are investigated in detail. Some major findings regarding the numerical results are withdrawn in conclusions.

关键词： Contact plate-fluid Refined quasi 3D plate theory Mori-Tanaka model Isogeometric analysis Bidirectional functionally graded plate

Graphical method based on modified maximum force criterion to indicate forming limit curves of 22MnB5 boron steel sheets at elevated temperatures

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Journal of Iron and Steel Research International 2021年第8期28卷 1009-1018页

作者： Thanh Luyen quoc-tuan Pham Thi-Bich Mac Tien-Long Banh Duc-Toan Nguyen Faculty of Mechanical Engineering Hungyen University of Technology and EducationHungyen 160000Vietnam Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 70000Vietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh City 70000Vietnam School of Mechanical Engineering Hanoi University of Science and TechnologyHanoi City 100000Vietnam

A new approach for predicting forming limit curves(FLCs)at elevated temperatures was proposed *** are often used to predict failure and determine the optimal forming parameters of automotive ***,a graphical method based on a modified maximum force criterion was applied to estimate the FLCs of 22MnB5 boron steel sheets at room temperature using various hardening ***,the predicted FLC data at room temperature were compared with corresponding data obtained from Nakazima's tests to obtain the best *** estimate the FLC at elevated temperatures,tensile tests were conducted at various temperatures to determine the ratios of equivalent fracture strains between the corresponding elevated temperatures and room *** at elevated temperatures could be established based on obtained ***,the predicted FLCs at elevated temperatures did not agree well with the corresponding FLC experimental data of Zhou et al.A new method was proposed herein to improve the prediction of FLCs at elevated *** FLC calculated at room tem-perature was utilized to predict the failure of Nakazima's samples via finite element *** on the simulation results at room temperature,the mathematical relationships between the equivalent ductile fracture strain versus stress triaxiality and strain ratio were established and then combined with ratios between elevated and room temperatures to calculate the FLCs at different *** predicted FLCs at elevated temperatures agree well with the corresponding experimental FLC data.

关键词： Forming limit curve Modified maximum force criterion Graphical method Hardening law Finite element method Boron steel sheet Elevated temperature

The Continuous Knapsack Problem with Capacities

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Journal of the Operations Research Society of China 2021年第3期9卷 713-721页

作者： Huynh Duc quoc Nguyen Chi Tam tran Hoai Ngoc Nhan Department of Mathematics College of Natural ScienceCan Tho UniversityCan Tho City 900900Vietnam Faculty of Basic Sciences Vinh Long University of Technology EducationVinh Long 940000Vietnam

We address a variant of the continuous knapsack problem,where capacities regarding costs of items are given into *** prove that the problem is NP-complete although the classical continuous knapsack problem is solvable in linear *** the case that there exists exactly one capacity for all items,we solve the corresponding problem in O(n log n)time,where n is the number of items.

关键词： Knapsack problem Complexity Capacity Polynomially solvabl

A new species Lobophora tsengii ***.(Dictyotales;Phaeophyceae)from Bach Long Vy(Bailongwei)Island,Vietnam

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Journal of Oceanology and Limnology 2021年第6期39卷 2363-2369页

作者： Zhongmin SUN Minh Dong DAO quoc Toan tran Duc Tien DAM Department of Marine Organism Taxonomy and Phylogeny Institute of OceanologyChinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Graduate University of Science and Technology Vietnam Academy of Science and Technology(VAST)Hanoi 100000Vietnam Institute of Natural Products Chemistry Vietnam Academy of Science and Technology(VAST)Cau GiayHanoi 100000Vietnam Institute of Marine Environment and Resources(IMER) Vietnam Academy of Science and Technology(VAST)Haiphong 180000Vietnam Haiphong University of Medicine and Pharmacy Haiphong 180000Vietnam

A new species Lobophora tsengii is described from Bach Long Vy(Bailongwei)Island,Haiphong Province,*** plants inhabit the subtidal zone and have predominantly erect fan-shaped thalli that attach to the substrate by a basal *** thallus is commonly composed of a single layer of large medullary cells with four layers of cortical cells on either side of the *** newly collected specimens from the island are morphologically similar to those from Hainan Island,China,but differ from the New Caledonian ones in having thicker *** molecular phylogenetic analyses based on concatenated rbcL and cox3 s equences,the specimens from the island were 100%identical to those from Hainan Island,China,and they formed a clade separating from other Lobophora ***,based on analyses of numerous cox3 s equences,our specimens were also distinguished from the closely related taxa occurring in New Caledonia,Kenya,and West *** the morphological and molecular analyses,we conclude that our specimens represent a new species of Lobophora,which is apparently endemic to the Beibu Gulf(Gulf of Tonkin)and adjacent waters.

关键词： Bach Long Vy(Bailongwei)Island cox3 Lobophora molecular phylogeny morphology rbcL

Three-Dimensional Multiferroic Structures under Time-Harmonic Loading

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Computer Modeling in Engineering & Sciences 2024年第11期141卷 1165-1191页

作者： Sonal Nirwal Ernian Pan Chih-Ping Lin quoc Kinh tran Department of Civil Engineering National Yang Ming Chiao Tung UniversityHsinchu300TaiwanChina Disaster Prevention and Water Environment Research Center National Yang Ming Chiao Tung UniversityHsinchu300TaiwanChina Department of Applied Science Krishna Institute of Engineering and TechnologyGhaziabad201206India

Magneto-electro-elastic(MEE)materials are a specific class of advanced smart materials that simultaneouslymanifest the coupling behavior under electric,magnetic,and mechanical *** unique combination ofproperties allows MEE materials to respond to mechanical,electric,and magnetic stimuli,making them versatile forvarious *** paper investigates the static and time-harmonic field solutions induced by the surface loadin a three-dimensional(3D)multilayered transversally isotropic(TI)linear MEE layered ***’s functionscorresponding to the applied uniform load(in both horizontal and vertical directions)are derived using the Fourier-Bessel series(FBS)system of vector *** virtue of this FBS method,two sets of first-order ordinarydifferential equations(i.e.,N-type and LM-type)are obtained,with the expansion coefficients being Love *** is noted that the LM-type system corresponds to the MEE-coupled P-,SV-,and Rayleigh waves,while the N-typecorresponds to the purely elastic SH-and Love *** applying the continuity conditions across interfaces,the solutions for each layer of the structure(from the bottom to the top)are derived using the dual-variable andposition(DVP)*** method(i.e.,DVP)is unconditionally stable when propagating solutions throughdifferent *** examples illustrate the impact of load types,layering,and frequency on the response ofthe structure,as well as the accuracy and convergence of the proposed *** numerical results are usefulin designing smart devices made of MEE solids,which are applicable to engineering fields like renewable energy.

关键词： Multiferroics multilayers Love numbers Fourier-Bessel series dual-variable and position method time-harmonic