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SSRN 2023年

作者： Liu, Shuo Che, Lu Fang, Guodong Liang, Jun Institute of Advanced Structure Technology Beijing Institute of Technology Beijing100081 China School of Civil Aviation Northwestern Polytechnical University Xi’an710072 China Yangtze River Delta Research Institute of NPU Taicang215400 China Science and Technology on Advanced Composites in Special Environments Key Laboratory Harbin Institute of Technology Harbin150001 China

The bond-based peridynamic (BB-PD) theory is inadequate in describing the four independent engineering material constants of composite lamina, which results in fixed values its Poisson’s ratios and shear moduli. This study presents a novel lamina conjugated BB-PD model encompasses not only the fiber bond and matrix bond, but also the transverse bond and conjugated bond pair. By defining these four basic PD bonds, the improved conjugated BB-PD model can overcome the restriction of material properties. The determination of the four basic PD micro-modulus parameters is achieved through the utilization of the equivalent relationship of strain energy density. In addition, the lamina conjugated BB-PD model is extended to deal with composite laminates with different stacking sequences. The present study validates the accuracy and applicability of the conjugated BB-PD model for composite materials by conducting simulations of the elastic deformation and progressive damage behavior of unidirectional laminae and laminates. Moreover, the proposed model provides an elucidation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading. © 2023, The Authors. All rights reserved.

关键词： Elastic moduli

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Effect of Overlap Pattern on the Residual Stress, Surface Morphology and Fatigue Properties of Ti-6al-4v Alloy by Multiple Laser Shock Peening

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SSRN 2024年

作者： Luo, Xuekun Tian, Kai Xu, Ziheng Wang, Yiming Wang, Xin Wang, Kun Yu, Yang Guo, Lulu Ye, Chang Dang, Ning Aviation Key Laboratory of Advanced Corrosion and Protection on Aviation Materials Beijing Institute of Aeronautical Material Beijing100095 China School of Mechanical Science and Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China Shenyang Engine Research Institute Shenyang110000 China State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials CNPC Tubular Goods Research Institute Shaanxi Xi’an710077 China

In this study, the effects of the laser shock peening (LSP) pattern on the fatigue properties of Ti-6Al-4V alloy were investigated. The residual stress distribution and surface morphology generated by LSP were analyzed using both experiments and numerical simulations. The results show that by optimizing the LSP patterns and overlap ratios, deep compressive residual stresses and beneficial surface morphology can be obtained, resulting in a significant improvement of the fatigue performance. Specifically, LSP without optimization improves the fatigue life by a factor of 1.68 when the stress level is 550 MPa and the stress ratio is 0.1, while LSP with optimized parameters improves the fatigue life by a factor of 29.67. It has been demonstrated that the optimization of LSP patterns and overlap ratios plays an important role in enhancing the surface integrity and, thus, the fatigue performance of the Ti-6Al-4V alloy. © 2024, The Authors. All rights reserved.

关键词： Surface morphology

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Optimal Trajectory Planning and Tracking for Autonomous Vehicles Considering Chassis Nonlinearities

Optimal Trajectory Planning and Tracking for Autonomous Vehi...

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2021 China Automation Congress, CAC 2021

作者： Zhang, Yuxiang Lyu, Jidong Wang, Jinkun Gao, Bingzhao Wang, Yuhai The State Key Laboratory of Automotive Simulation and Control Jilin University Changchun China The Advanced Technology Department of SAIC Motor Shanghai China Clean Energy Automotive Engineering Center Tongji University Shanghai China

ISBN: (纸本)9781665426473

This paper proposes a new type of local trajectory planning method for autonomous vehicles. In this frame, a lane-change or lane-keeping operation passed by the upper module is performed. Then, the trajectory planning algorithm can directly optimize the control sequences and obtain a feasible trajectory considering chassis nonlinearities and obstacles avoidance. A more accurate nonlinear model that considers the chassis' nonlinearity based on the traditional linear bicycle model is realized using a cubic polynomial of slip angle to fit the magic formula. Constraint conditions are designed based on the traffic environment to avoid obstacles. With a more precise model, the control sequences can be used as feedforward control and accompany with fine feedback control to receive a good motion control performance even in a high-speed situation. Furthermore, different time-steps of the control variables are used to reduce the number of solving variables to decrease calculation time. simulation results verify the effectiveness of the proposed method and the accuracy of the proposed nonlinear vehicle model. © 2021 IEEE

关键词： Chassis

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Zeeman spin splittings with persistent spin textures in antiferromagnetic semiconductors

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Physical Review B 2023年第12期108卷 125108-125108页

作者： Xinran Liu Hong Jian Zhao Laurent Bellaiche Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun 130012 China

Realizing sizable Zeeman spin splittings (ZSSs) with persistent spin textures (PSTs) in semiconductors is promising for the design of high-performance spintronic devices. The ZSSs of this kind have long been known in ferromagnetic semiconductors, while whether antiferromagnetic semiconductors—much more plenteous than ferromagnetic semiconductors—can host an analogous effect remains elusive. Here, we show that such ZSSs can occur in antiferromagnetic semiconductors. By symmetry analysis, we find 12 magnetic point groups that can host ZSSs and PSTs, providing theoretical guidelines for screening the corresponding antiferromagnets. Our first-principles calculations further confirm CaTcO3 as an antiferromagnetic semiconductor showcasing ZSSs that are sizable (tens of meV), possibly controllable by a magnetic field, and accompanied with PSTs. Our work thus may open a route towards the application of antiferromagnetic semiconductors in spintronics.

关键词： Dresselhaus coupling Magnetoelectric effect Rashba coupling Zeeman effect Antiferromagnets Multiferroics Perovskites First-principles calculations

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Susceptibility of patients with chronic obstructive pulmonary disease to heart rate difference associated with the short-term exposure to metals in ambient fine particles:A panel study in Beijing,China

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Science China(Life Sciences) 2022年第2期65卷 387-397页

作者： Ke Gao Xi Chen Xiaoying Li Hanxiyue Zhang Mengxiao Luan Yuan Yao Yifan Xu Teng Wang Yiqun Han Tao Xue Junxia Wang Mei Zheng Xinghua Qiu Tong Zhu State Key Joint Laboratory for Environmental Simulation and Pollution Control and Beijing Innovation Center for Engineering Science and Advanced Technology College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Green Research Inspection and Certification Co. Ltd.Institute of Building Research Co.Ltd.in ShenzhenShenzhen 518071China Medical Research Council Centre for Environment and HealthImperial College LondonDepartment of Epidemiology and BiostatisticsLondon W21PGUK Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health and Department of Epidemiology and Biostatistics School of Public HealthPeking UniversityBeijing 100191China

Susceptibility of patients with chronic obstructive pulmonary disease(COPD)to cardiovascular autonomic dysfunction asso-ciated with exposure to metals in ambient fine particles(PM2.5,particulate matter with aerodynamic diameter≤2.5µm)remains poorly *** on the COPDB(COPD in Beijing)panel study,we aimed to compare the associations of heart rate(HR,an indicator of cardiovascular autonomic function)and exposure to metals in PM2.5 between 53 patients with COPD and 82 healthy controls by using linear mixed-effects *** all participants,the HR levels were significantly associated with interquartile range increases in the average concentrations of Cr,Zn,and Pb,but the strength of the associations differed by exposure time(from 1.4%for an average 9 days(d)Cr exposure to 3.5%for an average 9 d Zn exposure).HR was positively associated with the average concentrations of PM2.5 and certain metals only in patients with *** between HR and exposure to PM2.5,K,Cr,Mn,Ni,Cu,Zn,As,and Se in patients with COPD significantly differed from those in health ***,association between HR and Cr exposure was robust in COPD *** conclusion,our findings indicate that COPD could exacerbate difference in HR following exposure to metals in PM2.5.

关键词： metal in fine particles chronic obstructive pulmonary disease(COPD) susceptibility heart rate cardiovascular auto-nomic function

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Crack-based and Hair-like Sensors Inspired from Arthropods:A Review

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Journal of Bionic Engineering 2020年第5期17卷 867-898页

作者： Changchao Zhang Junqiu Zhang Daobing Chen Xiancun Meng Linpeng Liu Kejun Wang Zhibin Jiao Tao Sun Dakai Wang Shichao Niu Zhiwu Han Luquan Ren Key Laboratory of Bionic Engineering(Ministry of Education China)Jilin UniversityChangchun 130022China State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130022China State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China School of Mechanical and Electric Engineering Jiangsu Provincial Key Laboratory of Advanced RoboticsSoochow UniversitySuzhou 215123China

Over a long period of time,arthropods evolve to have two excellent mechanical sensilla of slit sensilla and trichobothria sensilla,which construct a perfect perception *** former mainly perceives the change of the in-the-plane force while the latter perceives that of the out-of-plane *** recent years,these two sensilla have attracted researchers as the models for developing artificial mechanical *** review mainly includes the biomechanics and biomimetic manufacturing techniques as well as their future application *** order to better understand the advantages of biological strategies,this review describes the morphology,mechanical analysis,and information recognition of slit sensilla and trichobothria *** this review highlights the recent development of Crack-based Sensors(CBSs)and Hair-like Sensors(HLSs)based on the analysis of biological *** manufacturing method and substrate of crack in CBS and those of hair rods in HLS are discussed ***,the practical applications and potential value of two sensilla,such as flexible wearable electronic devices,robot sensing system,autopilot sensing and wind tunnel speed detection,are briefly discussed.

关键词： crack-based sensors hair-like sensors slit sensilla trichobothria sensilla bioinspiration

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Tracking Strategy of Multiple Moving Targets Using Multiple UAVs

Tracking Strategy of Multiple Moving Targets Using Multiple ...

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International Conference on Guidance, Navigation and Control, ICGNC 2020

作者： Lin, Chuanjian Shi, Jingping Huang, Degang Zhang, Weiguo Li, Wei School of Automation Northwestern Polytechnical University Xi’an710129 China Shaanxi Province Key Laboratory of Flight Control and Simulation Technology Xi’an710129 China Department of Automation Tsinghua University Beijing100084 China China North Industries Group Aviation Ammunition Institute Corporation Limited Harbin150036 China China Electronics Technology Group Corporation no.10 Research Institute Chengdu610036 China

ISBN: (纸本)9789811581540

The research of target tracking mainly focuses on one-to-one and many-to-one tracking, and occasionally on many-to-many tasks. Compared with single target tracking, multiple target tracking has broader application prospects and important research significance. The core problem of multiple targets tracking is the target assignment. This paper first introduces the improved L1 algorithm, which can realize the target tracking with a single UAV. The global asymptotic stability of the algorithm is also illustrated. Secondly, the time-optimal strategy based on the virtual structure is utilized to solve the target assignment. Finally, the numerical simulations are carried out for the tracking problems of moving targets, and the results verify the effectiveness of the proposed tracking algorithm. © 2022, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Unmanned aerial vehicles (UAV)

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Adversarial Learning Network for Recovering Rppg Signals from Low-Resolution Images for Remote Heart Rate Measurement

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SSRN 2024年

作者： Zhai, Dezhao Chen, Wei Li, Qinwei Yu, Ming Wu, Hang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China Systems Engineering Institute Academy of Military Sciences People's Liberation Army Tianjin300161 China Tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of China Tianjin300300 China School of Artificial Intelligence Nankai University Tianjin300381 China

Remote Photoplethysmography (rPPG) is a non-contact method for measuring heart rate (HR) through facial video, which has significant research value and application potential. However, in long-distance vital sign measurement tasks, the low resolution of facial images and insufficient pixels in the facial region severely degrade the quality of the rPPG signals, leading to a sharp decline in HR accuracy. To address this issue, this paper proposes an adversarial learning network for recovering rPPG signals from low-resolution images (ALRSL-HR). First, arbitrary resolution face images are fed into multi-channel network to extract rPPG signal features capturing rich rPPG information, generating rPPG feature blocks, and temporally aggregating for richer feature representation. These features are then inputted into the backbone network to generate adversarial examples of rPPG signals of varying qualities. Finally, a two-stage adversarial loss function is employed to enable the low-quality rPPG signals to learn the periodic characteristics of high-quality rPPG signals, recover the low-quality signals, and narrow the quality gap between rPPG signals from low-resolution images. Extensive experiments were conducted in this paper to validate the effectiveness of our model on the public COHFACE, UBFC-Phys and UBFC-rPPG datasets. The results of the experiments demonstrate that the proposed ALRSL-HR model can effectively recover degraded rPPG signals from low-resolution images. © 2024, The Authors. All rights reserved.

关键词： Photoplethysmography

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Modulation of the Octahedral Structure and Potential Superconductivity of La3Ni2O7 through Strain Engineering

arXiv

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arXiv 2024年

作者： Huo, Zihao Luo, Zhihui Zhang, Peng Yang, Aiqin Liu, Zhengtao Tao, Xiangru Zhang, Zihan Guo, Shumin Jiang, Qiwen Chen, Wenxuan Yao, Dao-Xin Duan, Defang Cui, Tian Key Laboratory of Material Simulation Methods & Software of Ministry of Education State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics School of Physics Xi’an Jiaotong University Xi’an710049 China Center for Neutron Science and Technology Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices State Key Laboratory of Optoelectronic Materials and Technologies School of Physics Sun Yat-Sen University Guangzhou510275 China Institute of High Pressure Physics School of Physical Science and Technology Ningbo University Ningbo315211 China

The recent transport measurement of La3Ni2O7 uncover a "right-triangle" shape of the superconducting dome in the pressure-temperature (P-T) phase diagram. Motivated by this, we perform theoretical first-principles studies of La3Ni2O7 with the pressure ranging from 0 to 100 GPa. Notably, we reveal a pressure dependence of the Ni-dz2 electron density at the Fermi energy (nzEF) that highly coincides with such shape. On this basis, we further explore the electronic structure under uniaxial stress. By tracking the stress response of nzEF , we propose that superconductivity can be achieved by applying only ~ 2 GPa of compression along the c axis. The idea is further exemplified from the perspectives of lattice distortion, band structure, Fermi surface and superconducting phase coherence. We also discuss the possible charge modulation under the stress and provide an insight to the relation between nzEF and the superconducting Tc in La3Ni2O7 system. Our study provides a helpful guide to the future experiment. © 2024, CC BY.

关键词： Band structure

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Numerical Fracture Analysis of a Reactor Pressure Vessel based on Abaqus-FRANC3D Co-simulation Method

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Procedia Structural Integrity 2022年 37卷 225-232页

作者： M. Annor-Nyarko Hong Xia Key Laboratory of Nuclear Safety and Advanced Nuclear Energy Technology Ministry of Industry and Information Technology Harbin Engineering University Harbin 150001 China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin 150001 China Nuclear Installations Directorate Nuclear Regulatory Authority Ghana

The reactor pressure vessel (RPV) is subjected to many cyclic loadings critical of which is the integrity risk posed by pressurized thermal shock (PTS) loadings induced by one of the most frequent anticipated operational occurrences - inadvertent operation of the safety injection system (SIS). In this paper, the fracture mechanics analysis for an ageing pressurized water reactor subjected to PTS induced by inadvertent actuation of the SIS is performed using a proposed simplified Abaqus-FRANC3D co-simulation method. A three-dimensional (3-D) finite element half-symmetric model of a typical pressured water reactor RPV is used to perform thermal-mechanical stress coupling analysis. 3-D fracture mechanic submodel with an assumed surface crack is created for the computation of the transient integrity parameter-stress intensity factor (SIF), using M-integral approach coupled in the proposed co-simulation method. Subsequently ASME method is used to evaluate the vessel’s material fracture toughness. Finally, the SIFs obtained with the simplified co-simulation method is compared with the conventional virtual crack-closure technique (VCCT), and the result show good agreement. This work serves as a useful reference for fast crack propagation and life prediction analysis of ageing PWR RPVs.

关键词： Pressurized thermal shock Fracture mechanics Reactor pressure vessel Safety injection system Stress intensity factor FRANC3D

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