检索结果-南通市图书馆

Wall shear-stress extraction by an optical flow algorithm with a sub-grid formulation

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2021年第1期37卷 65-79,I0003页

作者： The hung tran Lin Chen Faculty of Aerospace Engineering Le Quy Don Technical UniversityHanoi10000Vietnam Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100049China

In this study,we developed a novel optical-flow algorithm for determining the wall shear-stress on the surface of *** algorithm solves the thin-oil-film equation using a numerical scheme that recovers local features neglected by smoothing filters.A variational formulation with a smoothness constraint was applied to extract the global shear-stress *** algorithm was then applied to scalar images generated using direct numerical simulation(DNS)method,which revealed that the errors were smaller than those of conventional *** application of the proposed algorithm to recover the wall shear-stress on a low-aspect-ratio wing and on an axisymmetric boattail model taken as examples in this study showed a strong potential for analysing shear-stress *** to the methods used in previous studies,proposed method reveals more local features of separation line and singular points on object surface.

关键词： Wall shear-stress Optical flow Thin-oil-film equation Sub-grid model

Enhanced Intrusion Detection System for an EH IoT Architecture Using a Cooperative UAV Relay and Friendly UAV Jammer

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2021年第11期8卷 1786-1799页

作者： Van Nhan Vo hung tran Chakchai So-In Institute of Research and Development Duy Tan UniversityDa Nang 550000Vietnam Faculty of Information Technology Duy Tan UniversityDa Nang 550000Vietnam Applied Network Technology Laboratory Department of Computer ScienceFaculty of ScienceKhon Kaen UniversityKhon Kaen 40002Thailand Faculty of Computer Science Phenikaa UniversityHanoi 100000Vietnam

In this paper,the detection capabilities and system performance of an energy harvesting(EH)Internet of Things(Io T)architecture in the presence of an unmanned aerial vehicle(UAV)eavesdropper(UE)are *** communication protocol is divided into two *** the first phase,a UAV relay(UR)cooperates with a friendly UAV jammer(UJ)to detect the UE,and the UR and UJ harvest energy from a power beacon(PB).In the second phase,a ground base station(GBS)sends a confidential signal to the UR using non-orthogonal multiple access(NOMA);the UR then uses its harvested energy to forward this confidential signal to IoT destinations(IDs)using the decode-and-forward(DF)***,the UJ uses its harvested energy to emit an artificial signal to combat the detected UE.A closed-form expression for the probability of detecting the UE(the detection probability,DP)is derived to analyze the detection ***,the intercept probability(IP)and throughput of the considered IoT architecture are ***,we identify the optimal altitudes for the UR and UJ to enhance the system and secrecy *** Carlo simulations are employed to verify our approach.

关键词： Detection probability(DP) energy harvesting(EH) friendly UAV jammer Internet of Things(IoT) system performance UAV detection

Synthesis and characterization of core/shell structured nanophosphors CePO_4:Tb@LaPO_4 by solvothermal method

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2011年第12期29卷 1147-1151页

作者： Dinh Xuan loc tran Thi Kim Chi tran Thu Huong Nguyen Vu tran Kim Anh Wieslaw Strek Le Quoc Minh Institute of Materials Science Vietnam Academy of Science and Technology Institute of Low Temperature and Structure Research Polish Academy of Sciences(PAN) University of Engineering and Technology

Core/shell structured CePO4：Tb（Ⅲ）@LaPO4 and CePOa：Tb（Ⅲ） were successfully synthesized in tris（2-ethylhexyl） phosphate （TEHP） and diethylene glycol （DEG） solvents for comparison of the two techniques in open air and closed reaction vessel. Morphology and crystal structure of the core/shell nanophosphors were determined by using X-ray diffraction （XRD） and transmission electron microscopy （TEM）, which showed that nanophosphors had diameter of about 5-10 nm with the monoclinic monazite phase. The nanophosphors obtained by close vessel procedure showed smaller size, more homogeneity and pure crystallite. The luminescent measurements were done upon the different excitation wavelengths in ultraviolet region and at room temperatm＇e to elucidate the influences of the used solvents and the reaction temperatures. It was found that CePO4：Tb@LaPO4 preparedby the close vessel synthesis showed the intensity of green band of the transfer from 5D4 to 7F5 energy level, which was strongly increased, and the luminescent decay time was 3.2 ms, which was longer than that of naked CePO4：Tb phosphor.

关键词： solvothermal synthesis luminescence CePOn:Tb CePOa:Tb@LaPO4 rare earths

Single-Layer Wideband Circularly Polarized Antenna Using Non-Uniform Metasurface for C-band Applications

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第8期68卷 2487-2498页

作者： Huy hung tran Khoa Nguyen-Dang Niamat Hussain Faculty of Electrical and Electronic Engineering PHENIKAA UniversityHanoi12116Vietnam PHENIKAA Research and Technology Institute(PRATI) A&A Green Phoenix Group JSCCau Giay11313HanoiVietnam Department of Computer and Communication Engineering Chungbuk National UniversityCheongju 28644Korea

A single-layer design of non-uniform metasurface(MS)based circularly polarized(CP)antenna with wideband operation characteristic is proposed and investigated in this *** antenna is excited by a truncated corner squared patch as a primary radiating CP ***,a non-uniform MS is placed in the same layer with the driven *** increasing the impedance bandwidth,the non-uniform MS also generates two additional CP bands in the high frequency band,leading to significantly increase the antenna’s overall *** use of non-uniform MS distinguishes our design from the other CP MS based antennas in literature,in which the MS is formed by multiple uniform unit cells and placed in different layer with the radiating *** validation,an antenna prototype,whose overall dimensions of 0.94λ_(o)×0.94λ_(o)×0.06λ_(o) at the center operating frequency,is fabricated and experimentally *** measured operating bandwidth with|S11|≤−10 dB and AR≤3 dB is 27.1%(5.1–6.7 GHz)and the broadside gain within this band is from 5.7 to 7.2 *** to the other related works,the proposed antenna has advantage of very wideband operation with single-layer design.

关键词： Circular polarization metasurface non-uniform patch antenna wideband

High-performance carbon fiber/gold/copper composite wires for lightweight electrical cables

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第7期42卷 46-53页

作者： Thang Q.tran Jeremy Kong Yoong Lee Amutha Chinnappan Nguyen Huu loc Long T.tran Dongxiao Ji W.A.D.M.Jayathilaka Vishnu Vijay Kumar Seeram Ramakrishna Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1EA-07-05Singapore 117575Singapore Faculty of Mechanical Engineering Ho Chi Minh City University of TechnologyVNUHCM268 Ly Thuong KietDistrict 10Ho Chi Minh City 740400Viet Nam

In this study,we synthesized high-performance Carbon Fiber/Gold/Copper(CF/Au/Cu)composite wires by using a 2-step deposition method via sputtering and *** Au was sputtered on PANbased CFs as a pre-treatment,the wettability and surface reactivity of the CFs were improved,resulting in a homogeneous deposition of Cu on their *** different Cu electrodeposition time,the resulting CF/Au/Cu composite wires could possess a high strength of up to 3.27 GPa(~10 times stronger than copper wires)while their electrical conductivity could be as high as 4.4×10^5 S/cm(~75%of that for copper).More importantly,since the composite wires were lightweight(up to 70%lower than Cu mass density),they are a promising candidate to substitute conventional heavy metal wires in the future electrical applications.

关键词： Carbon fiber Copper composite wires Strength Electrical properties

Study of vertically ascending flight of a hawkmoth model

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2020年第5期36卷 1031-1045,I0002页

作者： Anh Tuan Nguyen Vu Dan Thanh Le The hung tran V.N.Due Van Binh Phung Faculty of Aerospace Engineering Le Quy Don Technical UniversityHanoiVietnam Institute of Theoretical and Applied Research.Duy Tan University HanoiVietnam Division of Construction Computation Institute for Computational ScienceTon Due Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Due Thang UniversityHo Chi Minh CityVietnam

This paper provides insight into the wing kinematics,the power requirement and the dynamic stability characteristics of a hawkmoth model in vertically ascending *** wing kinematics of the hawkmoth model is obtained based on the minimum required power *** optimization process is conducted using genetic and simplex algorithms that are coupled with an artificial neural network to rapidly predict the aerodynamic force and required *** training data for the neural network are generated from an unsteady vortex-lattice *** to hover,the results in this study show the larger flapping frequency and the smaller rotation amplitude of the hawkmoth wing kinematics in ascending ***,more power is required when the ascending speed *** conducting a dynamic modal analysis based on a cycle-average approach,the certain effect of the ascending speed on the modal structures of the hawkmoth model was observed.

关键词： Hawkmoth Ascending flapping flight-Genetic algorithm Artificial neural network Flight dynamic stability

Low-temperature synthesis of Fe_(2)(MoO_(4))_(3) nanosheets: A cathode for sodium ion batteries with kinetics enhancement

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2021年第11期14卷 3977-3987页

作者： Ha tran Huu N.S.M.Viswanath Ngoc hung Vu Jong-Won Lee Won Bin Im Division of Materials Science and Engineering Hanyang University222Wangsimni-roSeongdong-guSeoul04763Republic of Korea School of Materials Science and Engineering Chonnam National University77 Yongbong-roBuk-guGwangju61186Republic of Korea Falcuty of Biotechnology Chemistry and Environmental EngineeringPhenikaa UniversityHanoi10000Vietnam A&A Green Phoenix Group Phenikaa Research and Technology Institute(PRATI)167 Hoang NganHanoi10000Vietnam Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)333 Techno Jungang-daeroHyeonpung-eupDalseonggunDaegu42988Republic of Korea

Sodium ion batteries (SIBs) are alternatives to lithium ion batteries (LIBs), and offer some significant benefits such as cost reduction and a lower environmental impact;however, to compete with LIBs, further research is required to improve the performance of SIBs. In this study, an orthorhombic Na super ionic conductor structural Fe_(2)(MoO_(4))_(3) nanosheet with amorphous-crystalline core-shell alignment was synthesized using a facile low-temperature water-vapor-assisted solid-state reaction and applied as a cathode material for SIBs. The obtained material has a well-defined three-dimensional stacking structure, and exhibits a high specific capacity of 87.8 mAh·g^(−1) at a current density of 1 C = 91 mA·g^(−1) after 1,000 cycles, which is due to the considerable contribution of extra surface-related reaction such as the pseudo-capacitive process. This material shows significantly improved cycling and rated behavior as well as enhanced performance under high- and low-temperature conditions, as compared to the same materials prepared by the conventional high-temperature solid-state reaction. This enhancement is explained by the unique morphology in combination with the improved kinetics of the electrochemical reaction due to its lower charge transfer resistance and higher sodium ion conductivity.

关键词： low-temperature synthesis cathode sodium ion batteries kinetics Na+super ionic conductor(NASICON)

Intermediary RRT*-PSO:A Multi-Directional Hybrid Fast Convergence Sampling-Based Path Planning Algorithm

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第8期76卷 2281-2300页

作者： loc Q.Huynh Ly V.tran Phuc N.K.Phan Zhiqiu Yu Son V.T.Dao School of Industrial Engineering and Management International UniversityVietnam National University HCMCHo Chi Minh City700000Vietnam Department of Industrial Management National Taiwan University of Science and TechnologyTaipei City106335Taiwan

Path planning is a prevalent process that helps mobile robots find the most efficient pathway from the starting position to the goal position to avoid collisions with *** this paper,we propose a novel path planning algorithm-Intermediary RRT*-PSO-by utilizing the exploring speed advantages of Rapidly exploring Random Trees and using its solution to feed to a metaheuristic-based optimizer,Particle swarm optimization(PSO),for fine-tuning and *** Phase 1,the start and goal trees are initialized at the starting and goal positions,respectively,and the intermediary tree is initialized at a random unexplored region of the search *** trees were grown until one met the other and then merged and re-initialized in other unexplored *** the start and goal trees merge,the first solution is found and passed through a minimization process to reduce unnecessary *** 2 begins by feeding the minimized solution from Phase 1 as the global best particle of PSO to optimize the *** simulating two special benchmark configurations and six practice configurations with special cases,the results of the study concluded that the proposed method is capable of handling small to large,simple to complex continuous environments,whereas it was very tedious for the previous method to achieve.

关键词： Motion planning global path planning rapidly exploring random trees particle swarm optimization

A Neural-network-based Approach to Study the Energy-optimal Hovering Wing Kinematics of a Bionic Hawkmoth Model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2019年第5期16卷 904-915页

作者： Anh Tuan Nguyen Ngoc Doan tran Thanh Trung Vu Thanh Dong Pham Quoc Tru Vu Jae-hung Han Faculty of Aerospace Engineering Le Quy Don Technical University236 Hoang Quoc VietVietnam Office of International Cooperation Le Quy Don Technical University236 Hoang Quoc VietVietnam Department ofAerospace Engineerings Korea Advanced Institute of Science and Technology Daejeon 34141Republic ofKorea

This paper presents the application of an artificial neural network to develop an approach to determine and study the energy-optimal wing kinematics of a hovering bionic hawkmoth model.A three-layered artificial neural network is used for the rapid prediction of the unsteady aerodynamic force acting on the wings and the required *** this artificial network is integrated into genetic and simplex algorithms,the running time of the optimization process is reduced *** validity of this new approach is confirmed in a comparison with a conventional method using an aerodynamic model based on an extended unsteady vortex-lattice method for a sinu soidal wing kinematics *** studying the obtained results,it is found that actual hawkmoths do not hover under an energy-optimal ***,by tilting the stroke plane and lowering the wing positions,they can compromise and expend some energy to enhance their maneuverability and the stability of their flight.

关键词： optimal hovering wing kinematics artificial neural network insect flight genetic algorithm unsteady vortex-lattice method bionics