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Multi-Material Topology Optimization of 2D Structures Using Convolutional Neural Networks

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Computer Modeling in engineering & Sciences 2024年第8期140卷 1919-1947页

作者： Jiaxiang Luo Weien Zhou Bingxiao Du Daokui Li Wen Yao College of Aerospace Science and engineering National University of Defense TechnologyChangsha410073China defense Innovation institute Chinese Academy of Military ScienceBeijing100071China Intelligent Game and Decision Laboratory Chinese Academy of Military ScienceBeijing100071China

In recent years,there has been significant research on the application of deep learning(DL)in topology optimization(TO)to accelerate structural ***,these methods have primarily focused on solving binary TO problems,and effective solutions for multi-material topology optimization(MMTO)which requires a lot of computing resources are still ***,this paper proposes the framework of multiphase topology optimization using deep learning to accelerate MMTO *** framework employs convolutional neural network(CNN)to construct a surrogate model for solving MMTO,and the obtained surrogate model can rapidly generate multi-material structure topologies in negligible time without any *** performance evaluation results show that the proposed method not only outputs multi-material topologies with clear material boundary but also reduces the calculation cost with high prediction ***,in order to find a more reasonable modeling method for MMTO,this paper studies the characteristics of surrogate modeling as regression task and classification *** the training of 297 models,our findings show that the regression task yields slightly better results than the classification task in most ***,The results indicate that the prediction accuracy is primarily influenced by factors such as the TO problem,material category,and data ***,factors such as the domain size and the material property have minimal impact on the accuracy.

关键词： Multi-material topology optimization convolutional neural networks deep learning finite element analysis

Room and cryogenic deformation behavior of AZ61 and AZ61-xCaO(x=0.5,1 wt.%)alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1996-2009页

作者： Umer Masood Chaudry Hafiz Muhammad Rehan Tariq Nooruddin Ansari Soo Yeol Lee Tea-Sung Jun Department of Mechanical engineering Incheon National UniversityIncheon 22012Republic of Korea research institute for engineering and Technology Incheon National UniversityIncheon 22012Republic of Korea Department of Materials Science&engineering Chungnam National UniversityDaejeon 34134Republic of Korea

This study investigates the influence of CaO(0.5,1(wt.%))alloying on the microstructural evolution,texture development and deformation behavior of AZ61 magnesium *** uniaxial tension tests at room(RT)and cryogenic(CT,-150℃)temperature were performed to investigate the twinability and dislocation behavior and its consequent effect on flow stress,ductility and strain hardening *** results showed that the AZ61-1CaO exhibited superior strength/ductility synergy at RT with a yield strength(YS)of 223 MPa and a ductility of 23% as compared to AZ61(178 MPa,18.5%)and AZ61-0.5CaO(198 MPa,21%).Similar trend was witnessed for all the samples during CT deformation,where increase in the YS and decrease in ductility were *** Mtex tools based in-grain misorientation axis(IGMA)analysis of RT deformed samples revealed the higher activities of prismatic slip in AZ61-CaO,which led to superior ***,subsequent EBSD analysis of CT deformed samples showed the increased fraction of fine{10-12}tension twins and nucleation of multiple{10-12}twin variants caused by higher local stress concentration at the grain boundaries,which imposed the strengthening by twin-twin ***,the detailed investigations on strengthening contributors showed that the dislocation strengthening has the highest contribution towards strength in all samples.

关键词： Magnesium Twinning Twinning variant EBSD Cryogenic deformation

Experimental study on shock interaction control of double wedge in high-enthalpy hypersonic flow subject to plasma synthetic jet

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Chinese Journal of Aeronautics 2024年第4期37卷 151-165页

作者： Xuzhen XIE Qiang LIU Yan ZHOU Zhenbing LUO Wei XIE Guanghui BAI Kai LUO Qiu WANG Jianjun WU College of Aerospace Science and engineering National University of Defense TechnologyChangsha 410073China China Academy of Launch Vehicle Technology Beijing 100076China institute of Mechanics Chinese Academy of SciencesBeijing 100190China

The hypersonic shock-shock interaction flow field at double-wedge geometries controlled by plasma synthetic jet actuator is experimentally studied in a Ma = 8 high-enthalpy shock tunnel with the purpose of exploring a novel technique for reducing surface heat flux in a real flight environment. The results demonstrate that increasing the discharge energy is advantageous in eliminating the shock wave, shifting the shock wave interaction point, and shortening the control response time. The oblique shock wave can be completely removed when the actuator's discharge energy grows from 0.4 J to 11.5 J, and the displacement of the shock wave interaction point increases by 124.56%, while the controlled response time is shortened by 30 μs. Besides, the reduction in diameter of the jet exit is firstly proved to have a negative impact on energy deposition in a working environment with incoming flow, which reduces the discharge energy and hence decreases the control effect. The shock wave control response time lengthens when the jet exits away from the second wedge. Along with comparing the change in wall heat flux at the second wedge over time, the control effect of plasma synthetic jet actuator with and without inflation is also analyzed. When plasma synthetic jet works in inflatable mode, both the ability to eliminate shock waves and the shifting effect of the shock wave interaction point are increased significantly, and the wall heat flux is also reduced.

关键词： Hypersonic flow High-enthalpy flow Plasma synthetic jet Shock wave Flow control

ContextAug:model-domain failing test augmentation with contextual information

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Frontiers of Computer Science 2024年第2期18卷 43-60页

作者： Zhuo ZHANG Jianxin XUE Deheng YANG Xiaoguang MAO School of Information Technology and engineering Guangzhou College of CommerceGuangzhou 511363China School of Computer and Information engineering Institute for Artificial IntelligenceShanghai Polytechnic UniversityShanghai 201209China College of Computer National University of Defense TechnologyChangsha 410073China

In the process of software development,the ability to localize faults is crucial for improving the efficiency of *** speaking,detecting and repairing errant behavior at an early stage of the development cycle considerably reduces costs and development *** have tried to utilize various methods to locate the faulty ***,failing test cases usually account for a small portion of the test suite,which inevitably leads to the class-imbalance phenomenon and hampers the effectiveness of fault ***,in this work,we propose a new fault localization approach named *** obtaining dynamic execution through test cases,ContextAug traces these executions to build an information model;subsequently,it constructs a failure context with propagation dependencies to intersect with new model-domain failing test samples synthesized by the minimum variability of the minority feature *** contrast to traditional test generation directly from the input domain,ContextAug seeks a new perspective to synthesize failing test samples from the model domain,which is much easier to augment test *** conducting empirical research on real large-sized programs with 13 state-of-the-art fault localization approaches,ContextAug could significantly improve fault localization effectiveness with up to 54.53%.Thus,ContextAug is verified as able to improve fault localization effectiveness.

关键词： context fault localization test cases

Twistronics and moiréexcitonic physics in van der Waals heterostructures

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Frontiers of physics 2024年第4期19卷 147-185页

作者：李思维韦可刘祺瑞唐宇翔江天 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China institute for Quantum Science and Technology National University of Defense TechnologyChangsha 410073China

Heterostructures composed of two-dimensional van der Waals(vdW)materials allow highly controllable stacking,where interlayer twist angles introduce a continuous degree of freedom to alter the electronic band structures and excitonic *** by the discovery of Mott insulating states and superconductivity in magic-angle bilayer graphene,the emerging research fields of“twistronics”and moiréphysics have aroused great academic interests in the engineering of optoelectronic properties and the exploration of new quantum phenomena,in which moirésuperlattice provides a pathway for the realization of artificial excitonic *** we systematically summarize the current achievements in twistronics and moiréexcitonic physics,with emphasis on the roles of lattice rotational mismatches and atomic ***,we review the effects of the interlayer twist on electronic and photonic physics,particularly on exciton properties such as dipole moment and spin-valley polarization,through interlayer interactions and electronic band *** also discuss the exciton dynamics in vdW heterostructures with different twist angles,like formation,transport and relaxation processes,whose mechanisms are complicated and still need further ***,we review the theoretical analysis and experimental observations of moirésuperlattice and moirémodulated *** exotic moiréeffects are also shown,including periodic potential,moiréminiband,and varying wave function symmetry,which result in exciton localization,emergent exciton peaks and spatially alternating optical selection *** further introduce the expanded properties of moirésystems with external modulation factors such as electric field,doping and strain,showing that moirélattice is a promising platform with high tunability for optoelectronic applications and in-depth study on frontier ***,we focus on the rapidly developing field of correlated electron physics based on the moiré

关键词： moirésuperlattice twistronics van der Waals heterostructure moiréexciton correlated electronic state

Microstructural evolution and deformation behavior of friction stir welded twin-induced plasticity steel

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Journal of Materials Science & Technology 2024年第2期169卷 68-81页

作者： Ke Qiao Kuaishe Wang Jia Wang Zhengyang Hao Yating Xiang Peng Han Jun Cai Qi Yang Wen Wang School of Metallurgical engineering National and Local Joint Engineering Research Center for Functional Materials ProcessingXi’an University of Architecture and TechnologyXi’an 710055China Shanghai research institute of Materials Shanghai 200437China

The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first *** results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in *** with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,*** elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile *** engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the ***,the tensile fracture occurred in the *** order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈*** order of yield strength was as follows:HAZ>BM>SZ.

关键词： Twin-induced plasticity steel Friction stir welding Microstructure Mechanical property Deformation behavior

Model of self-generated magnetic field generation from relativistic laser interaction with solid targets

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Chinese Physics B 2024年第5期33卷 511-517页

作者：严睿邹德滨赵娜杨晓虎蒋祥瑞胡理想徐新荣周泓宇余同普卓红斌邵福球银燕 Northwest institute of Nuclear Technology Xi'an 710024China Department of Physics National University of Defense TechnologyChangsha 410073China School of Microelectronics and Physics Hunan University of Technology and BusinessChangsha 410205China Department of Nuclear Science and Technology National University of Defense TechnologyChangsha 410073China College of engineering Physics Shenzhen Technology UniversityShenzhen 518118China

Generation of self-generated annular magnetic fields at the rear side of a solid target driven by relativistic laser pulse is investigated by using theoretical analysis and particle-in-cell *** spatial strength distribution of magnetic fields can be accurately predicted by calculating the net flow caused by the superposition of source flow and return flow of hot *** theoretical model established shows good agreement with the simulation results,indicating that the magnetic-field strength scales positively to the temperature of hot *** provides us a way to improve the magnetic-field generation by using a micro-structured plasma grating in front of the solid *** with that for a common flat target,hot electrons can be effectively heated with the well-designed grating size,leading to a stronger magnetic *** spatial distribution of magnetic fields can be modulated by optimizing the grating period and height as well as the incident angle of the laser pulse.

关键词： self-generated magnetic field laser solid-target interaction micro-structured plasma grating

Overview of radar detection methods for low altitude targets in marine environments

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Journal of Systems engineering and Electronics 2024年第1期35卷 1-13页

作者： YANG Yong YANG Boyu School of Electronic Science National University of Defense TechnologyChangsha 410073China

In this paper,a comprehensive overview of radar detection methods for low-altitude targets in maritime environments is presented,focusing on the challenges posed by sea clutter and multipath *** performance of the radar detection methods under sea clutter,multipath,and combined conditions is categorized and summarized,and future research directions are outlined to enhance radar detection performance for low-altitude targets in maritime environments.

关键词： radar sea clutter multipath scattering detection low altitude target

Resource-saving scheduling scheme for centralized target tracking in multiple radar system under automatic blanket jamming

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Chinese Journal of Aeronautics 2024年第5期37卷 349-362页

作者： Zhengjie LI Yujie WEI Junwei XIE Haowei ZHANG Yu TIAN Air and Missile defense College Air Force Engineering UniversityXi’an 710051China Air Force Xi’an Flying College Xi’an 710300China Air and Missile defense institute Air Force Research InstituteBeijing 100085China School of Economics and Management Beihang UniversityBeijing 100191China

This paper investigates the problem of Joint Radar Node Selection and Power Allocation(JRNSPA)in the Multiple Radar System(MRS)in the blanket jamming *** radar node independently tracks moving target and subsequently transmits the raw observation data to the fusion center,which formulates a centralized tracking network *** order to establish a practical blanket jamming environment,we suppose that each target carries the self-defense jammer which automatically implements blanket jamming to the radar nodes that exceed the preset interception ***,the Predicted Conditional Cramer-Rao Lower Bound(PC-CRLB)is derived and utilized as the tracking accuracy *** at ensuring both the tracking performance and the Low Probability of Intercept(LPI)performance,the resource-saving scheduling model is formulated to minimize the transmit power consumption while meeting the requirements of tracking ***,the Modified Zoutendijk Method Of Feasible Directions(MZMFD)-based two-stage solution technique is adopted to solve the formulated non-convex optimization *** results show the effectiveness of the proposed JRNSPA scheme.

关键词： Multiple Radar System(MRS) Centralized target tracking Resource scheduling Blanket jamming Low Probability of Intercept(LPI)