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Acta Mechanica Sinica 2023年第1期39卷 23-29页

作者：王林李二垒周宗彦张百成余艾冰 ARC Hub for Computational Particle Technology Department of Chemical & Biological Engineering Monash University Clayton VIC 3800 Australia Delft University of Technology Stevinweg 1 2628 CN Delft The Netherlands Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and Technology Nanchang 330013 China Beijing Advanced Innovation Center Materials Genome Engineering Advanced Material & Technology Institute University of Science and Technology Beijing Beijing 100083 China

粉末床熔融增材制造技术已应用于功能梯度材料的制造.文献中报道了一种材料成分沿垂直于粉末铺粉方向变化的新设计.基于此设计,本工作采用离散单元数值模拟研究了两种密度差异较大的金属粉末在铺粉过程中颗粒的偏析情况.结果发现,在铺... 详细信息

粉末床熔融增材制造技术已应用于功能梯度材料的制造.文献中报道了一种材料成分沿垂直于粉末铺粉方向变化的新设计.基于此设计,本工作采用离散单元数值模拟研究了两种密度差异较大的金属粉末在铺粉过程中颗粒的偏析情况.结果发现,在铺粉过程中,较大密度粉末(重颗粒)一侧的铺粉量小于较小密度粉末(轻颗粒)的一侧的铺粉量.这种现象表明重颗粒从粉末密度大的一侧向粉末密度较小的一侧扩散.这种扩散受铺粉速度影响较大,铺粉速度越快,扩散越明显.但粉末层厚度对扩散影响不大.结果还表明,重颗粒与轻颗粒间的粒径差异影响扩散较大,减小重颗粒的粒径可能是控制颗粒偏析的一种方案.

关键词：材料成分颗粒偏析功能梯度材料离散单元金属粉末密度差异增材制造技术扩散影响

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Long-time evolution of charged grains in plasma under harmonic external force and after being withdrawn

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Chinese Physics B 2022年第2期31卷 460-464页

作者： Miao Guan Zhi-Dong Chen Meng-Die Li Zhong-Mao Liu You-Mei Wang Ming-Yang Yu Department of Physics School of ScienceHangzhou Dianzi UniversityHangzhou 310016China College of Engineering Physics CAMDTShenzhen Key Laboratory of Ultraintense Laser and Advanced Material TechnologyShenzhen Technology UniversityShenzhen 518118China Institute for Fusion Theory and Simulation Zhejiang UniversityHangzhou 310007China Theoretical Physics I Ruhr UniversityBochum D-44780Germany

Evolution of the charged grains in a two-dimensional dusty plasma under a spatially harmonic external force,in particular,their long-time behaviors after the force has been withdrawn,is studied by using molecular dynamics *** an external force and a grain–grain interaction force,initially homogeneously distributed grains can reach a quasistationary state in the form of a disk *** the external force is withdrawn,the disk moves initially with its size and shape nearly unchanged until it rapidly stops moving,and eventually the disk grain rotates like a *** time needed to reach the final state increases with the strength of the initial external force increasing.

关键词： dusty plasma external force long-time behavior molecular dynamics(MD)simulation

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HMAFlow: Learning More Accurate Optical Flow via Hierarchical Motion Field Alignment

arXiv

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arXiv 2024年

作者： Ma, Dianbo Imamura, Kousuke Gao, Ziyan Wang, Xiangjie Yamane, Satoshi Graduate School of Natural Science & Technology Kanazawa University Japan Information Science Japan Advanced Institute of Science and Technology Japan State Key Laboratory of Automotive Simulation and Control Jilin University China

Optical flow estimation is a fundamental and longstanding visual task. In this work, we present a novel method, dubbed HMAFlow, to improve optical flow estimation in challenging scenes, particularly those involving small objects. The proposed model mainly consists of two core components: a Hierarchical Motion Field Alignment (HMA) module and a Correlation Self-Attention (CSA) module. In addition, we rebuild 4D cost volumes by employing a Multi-Scale Correlation Search (MCS) layer and replacing average pooling in common cost volumes with a search strategy utilizing multiple search ranges. Experimental results demonstrate that our model achieves the best generalization performance compared to other state-of-the-art methods. Specifically, compared with RAFT, our method achieves relative error reductions of 14.2% and 3.4% on the clean pass and final pass of the Sintel online benchmark, respectively. On the KITTI test benchmark, HMAFlow surpasses RAFT and GMA in the Fl-all metric by relative margins of 6.8% and 7.7%, respectively. To facilitate future research, our code will be made available at https://***/BooTurbo/HMAFlow. Copyright © 2024, The Authors. All rights reserved.

关键词： Motion estimation

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Temperature Field Analysis and Optimal Design of Axial Flux Permanent Magnet Motor Based on Fluid-Solid Coupling

Temperature Field Analysis and Optimal Design of Axial Flux ...

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IEEE International Conference on Power and Power and Renewable Energy (ICPRE)

作者： Haoyu Kang Yiming Song Jin Wang Libing Zhou State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China AECC Hunan Aviation Powerplant Research Institute Zhuzhou China

ISBN: (数字)9798350377460

ISBN: (纸本)9798350377477

With its compact spatial structure and high power density, the axial flux permanent magnet motor is suitable for specialized applications but also imposes higher cooling requirements. It necessitates a well-designed rotor cooling structure to ensure reliable motor operation. This paper uses a 7kW dual-stator single-rotor axial flux permanent magnet motor as an example. Based on the principle of fluid-solid coupling, the motor's three-dimensional fluid field and temperature field models are established to study the impact of different rotor structures on the motor's heat dissipation capability. The research results indicate that the permanent magnets exhibit the highest temperature rise in a dual-stator single-rotor axial flux permanent magnet motor. By more effectively agitating the air around the permanent magnets and increasing the heat dissipation area of the permanent magnets, the motor's cooling capacity can be improved. Specifically, thinning the rotor support structure can effectively suppress the temperature rise of the permanent magnets.

关键词： Heating systems Couplings Solid modeling Temperature distribution Fluids Cooling Rotors Permanent magnet motors Permanent magnets Stress

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Knowledge-driven material design platform based on the whole-process simulation and modeling

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International Journal of Modeling, simulation, and Scientific Computing 2022年第2期13卷 1-15页

作者： Gongzhuang Peng Tie Li Xiang Zhai Wenzheng Liu Heming Zhang National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing Beijing 100083 P.R.China Shanghai Electro-Mechanical Engineering Institute Shanghai 201109 P.R.China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System Engineering Beijing 100854 P.R.China Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing Simulation Center Beijing 100854P.R.China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center Beijing 100854P.R.China National CIMS Engineering Research Center Tsinghua University Beijing 100084P.R.China

In order to realize the agility,collaboration and visualization of alloy material devel-opment process,a product development platform based on simulation and modeling technologies is established in this *** this platform,the whole-process simulation module builds multi-level simulation models based on metallurgical mechanisms from the production line level,the thermo-mechanical coupling field level and the microstructure evolution *** design knowledge management module represents the multi-source heterogeneous material design knowledge through ontology model,including customers’requirement knowledge,material component knowledge,process design knowledge and quality inspection knowledge,and utilizes the case-based reasoning approach to reuse the *** data-driven modeling module applies machine learning algorithms to mine the relationships between product mechanical properties,material components,and process parameters from historical samples,and utilizes multi-objective optimiza-tion algorithms to find the optimal combination of process *** of the developed platform in actual steel mills shows that the proposed method helps to improve the efficiency of product design process.

关键词： Product development knowledge-based engineering multi-scale simulation performance prediction model

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Impacts of synoptic circulation on surface ozone pollution in a coastal eco-city in Southeastern China during 2014-2019

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Journal of Environmental sciences 2023年第5期127卷 143-157页

作者： Yu Yan Xuesong Wang Zhengchao Huang Kun Qu Wenbin Shi Zimu Peng Limin Zeng Shaodong Xie Yuanhang Zhang State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China International Joint Laboratory for Regional Pollution Control Ministry of EducationBeijing 100816China Center for Environmental Education and Communications of Ministry of Ecology and Environment Beijing 100020China Beijing Innovation Center for Engineering Science and Advanced Technology Peking UniversityBeijing 100871China CAS Center for Excellence in Regional Atmospheric Environment Chinese Academy of SciencesXiamen 361021China

The coastal eco-city of Fuzhou in Southeastern China has experienced severe ozone(O_(3))episodes at times in recent *** this study,three typical synoptic circulations types(CTs)that influenced more than 80%of O_(3) polluted days in Fuzhou during 2014-2019 were identified using a subjective *** characteristics of meteorological conditions linked to photochemical formation and transport of O_(3) under the three CTs were *** Air Quality Model with extensions was applied to simulate O_(3) episodes and to quantify O_(3) sources from different regions in *** Fuzhou was located to the west of a high-pressure system(classified as“East-ridge”),more warm southwesterly currents flowed to Fuzhou,and the effects of cross-regional transport from Guangdong province and high local production promoted the occurrence of O_(3) *** a uniform pressure field with a low-pressure system occurring to the east of Fuzhou(defined as“East-low”),stagnant weather conditions caused the strongest local production of O_(3) in the atmospheric boundary *** by high-pressure systems over the mainland(categorized as“Inland-high”),northerly airflows enhanced the contribution of cross-regional transport to O_(3) in *** abnormal increases of the“East-ridge”and“Inland-high”were closely related to O_(3) pollution in Fuzhou in April and May 2018,resulting in the annual maximum number of O_(3) polluted days during recent ***,the rising number of autumn O_(3) episodes in 2017-2019 was mainly related to the“Inland-high”,indicating the aggravation of cross-regional transport and highlighting the necessity of enhanced regional collaboration and efforts in combating O_(3) pollution.

关键词： Ozone pollution Synoptic circulation Regional transport Chemical production

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Plating Al Coating on High-Strength Steel in Chloroaluminate Ionic Liquid Under Pulse Current Modes

SSRN

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SSRN 2024年

作者： Nan, Yang Li, Wen Li, Shaojie Wei, Qi Li, Weiping Aviation Key Laboratory of Science and Technology on Advanced Surface Engineering AVIC Manufacturing Technology Institute Beijing100024 China School of Materials Science and Engineering Beihang University Beijing100191 China

Aluminum coating is a potential candidate for cadmium coating replacement due to its excellent corrosion resistance and nontoxicity. Among the fabrication methods of Al coating, plating Al via ionic liquids has drawn major attention of researchers because of the superiority of controllability, stability and low energy consumption. However, the evolution rules of plating aluminum on high-strength steel via pulse current modes at room temperature requires deeper investigation. In this work, pulse current density and pulse duty factor are regulated to reveal the plating patterns of Al on 300M high-strength steel in AlCl3-EMIC (2:1 in mole) ionic liquid. It is found that higher current density can significantly facilitate the nucleation of Al grains and the compactness of morphology, while an enlarged pulse duty factor tends to result in more regular Al crystals. When the current density and the pulse duty factor are fixed at 20 mA cm−2 and 80%, the densest and most uniform aluminum coating is obtained. The component of Al coating is verified to be pure Al crystals with good adhesion and the plating process achieves a high current efficiency of 97.27%. Under the protection of Al coating, the impedance and galvanic corrosion current density of 300M steel substrate are optimized by two orders of magnitude, while the corrosion current density is markedly decreased from 5.58 μA cm−2 to 0.77 μA cm−2. © 2024, The Authors. All rights reserved.

关键词： Morphology

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Evolution of N=20,28,50 shell closures in the 20≤Z≤30 region in deformed relativistic Hartree-Bogoliubov theory in continuum

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Chinese Physics C 2024年第1期48卷 144-153页

作者：郑茹尤孙向向申国防耿立升 School of Physics Beihang UniversityBeijing102206China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Institut für Kernphysik Institute for Advanced Simulation and Jülich Center for Hadron PhysicsForschungszentrum JülichD-52425 JülichGermany CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang UniversityBeijing 102206China Southern Center for Nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

Magicity,or shell closure,plays an important role in our understanding of complex nuclear *** this work,we employ one of the state-of-the-art density functional theories,the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc)with the density functional PC-PK1,to investigate the evolution of the N=20,28,50 shell closures in the 20≤Z≤30 *** show how these three conventional shell closures evolve from the proton drip line to the neutron drip line by studying the charge radii,two-neutron separation energies,two-neutron gaps,quadrupole deformations,and single-particle *** particular,we find that in the 21≤Z≤27 region,the N=50 shell closure disappears or becomes quenched,mainly due to the deformation ***,both experimental data and theoretical predictions indicate that the N=28 shell closure disappears in the Mn isotopic chain,mainly due to the deformation *** DRHBc theory predicts the existence of the N=20 shell closure in the Ca,Sc,and Ti isotopic chains,but the existing data for the Ti isotopes suggest the contrary,and therefore further research is needed.

关键词： shell evolution covariant density functional theories magic numbers

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Study on Microstructure and Corrosion Behavior of Welded Joints of 2a12 and 2a97 Aluminum Alloys by Fsw

SSRN

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SSRN 2024年

作者： Li, Wen Li, Shaojie Nan, Yang Bai, Xuepiao Li, Weiping School of Materials Science and Engineering Beihang University Beijing100191 China Aviation Key Laboratory of Science and Technology on Advanced Surface Engineering AVIC Manufacturing Technology Institute Beijing100024 China

T-shaped joints of high-strength aluminum alloy welded by friction stir welding (FSW) are expected to replace the traditional riveting structures. However, the corrosion of T-joint still hinder the popularization of FSW in aerospace industry. Herein, T-joints of 2A12 and 2A97 aluminum alloys are prepared and studied via structural characterization and corrosion tests. The microstructures and constituents of different micro zones in T-joints before and after corrosion tests are characterized and analyzed particularly. The internal relationship between different micro zones in T-joints and their corrosion behaviors are clarified, which provides theoretical basis for improving welding process and surface protection after welding. © 2024, The Authors. All rights reserved.

关键词： Friction stir welding

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基于晶体塑性的辐照金属材料局部化颈缩和吕德斯带的模拟研究

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Acta Mechanica Sinica 2023年第4期39卷 132-146页

作者：付家琪刘文斌隋昊男程杨洋段慧玲 State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering ScienceThe Beijing Innovation Center for Engineering Science and Advanced TechnologyCollege of EngineeringPeking UniversityBeijing100871China Key Laboratory of High Energy Density Physics Simulation Center for Applied Physics and Technologyand Inertial Fusion Sciences and ApplicationsCollaborative Innovation Center of Ministry of EducationPeking UniversityBeijing100871China

金属材料中,颈缩失稳通常由表面缺陷或材料不均匀性等潜在扰动引起并随着微结构的演化进一步发展.本文将构型扰动法与考虑辐照效应的晶体塑性本构关系相结合,模拟了辐照前后局部化颈缩和吕德斯带等现象.通过考虑模拟局部化变形中扰动的... 详细信息

金属材料中,颈缩失稳通常由表面缺陷或材料不均匀性等潜在扰动引起并随着微结构的演化进一步发展.本文将构型扰动法与考虑辐照效应的晶体塑性本构关系相结合,模拟了辐照前后局部化颈缩和吕德斯带等现象.通过考虑模拟局部化变形中扰动的必要性,发现了外在的几何缺陷和内禀的微结构演化在颈缩过程中的竞争关系.此外,以纯金属铜和奥氏体不锈钢为例研究了辐照硬化效应对颈缩失稳的影响.结果表明,流动应力的增加和功硬化能力的降低是均匀延伸率下降的原因,辐照效应导致的织构软化作用可以忽略.为了解释辐照后低碳钢下屈服点和吕德斯应变同时增加的现象,一种位错脱钉扎和位错与辐照缺陷的交互作用相耦合的塑性变形机制被提出并结合修正的流动方程,很好地模拟出包含屈服下降、应力平台、应变扩展和应变硬化等特征的吕德斯带现象.其中,位错与辐照缺陷的相互作用也可以解释辐照后纯金属材料中发现的扩散颈缩现象.我们的模拟结果既阐明了几何缺陷在颈缩失稳中的重要作用,也为辐照金属中常见的宏观塑性失稳现象提供了清晰的物理图像.

关键词：吕德斯带金属材料奥氏体不锈钢晶体塑性下屈服点流动应力几何缺陷均匀延伸率

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