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Numerical Study on the Stress–Strain Cycle of Thermal Self-Compressing Bonding

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Chinese Journal of Mechanical Engineering 2018年第4期31卷 140-147页

作者： Yun-Hua Deng Qiao guan jun Tao Bing Wu Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Beijing Aeronautical Manufacturing Technology Research Institute School of Mechanical Engineering and Automation Beihang University Science and Technology on Power Beam Process Laboratory AVIC Beijing Aeronautical Manufacturing Technology Research Institute

Thermal self-compressing bonding(TSCB) is a new solid-state bonding method pioneered by the authors. With electron beam as the non-melted heat source, previous experimental study performed on titanium alloys has proved the feasibility of TSCB. However, the thermal stress–strain process during bonding, which is of very important significance in revealing the mechanism of TSCB, was not analysed. In this paper, finite element analysis method is adopted to numerically study the thermal elasto-plastic stress–strain cycle of thermal self-compressing bonding. It is found that due to the localized heating, a non-uniform temperature distribution is formed during bonding, with the highest temperature existed on the bond interface. The expansion of high temperature materials adjacent to the bond interface are restrained by surrounding cool materials and rigid restraints, and thus an internal elasto-plastic stress–strain field is developed by itself which makes the bond interface subjected to thermal compressive action. This thermal self-compressing action combined with the high temperature on the bond interface promotes the atom diffusion across the bond interface to produce solid-state joints. Due to the relatively large plastic deformation, rigid restraint TSCB obtains sound joints in relatively short time compared to diffusion bonding.

关键词： Thermal self-compressing bonding Locally non-melted heating Thermal elasto-plastic stress–strain Atom diffusion Solid-state bonding Finite element analysis

Targeting angiogenesis for fracture nonunion treatment in inflammatory disease

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Bone Research 2021年第3期9卷 336-348页

作者： Cuicui Wang jun Ying xiaolei Nie Tianhong Zhou Ding xiao Gaurav Swarnkar Yousef Abu-Amer Jianjun guan Jie Shen Department of Orthopaedic Surgery School of MedicineWashington UniversitySt.LouisMOUSA Department of Orthopaedic Surgery the First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina Institute of Orthopaedics and Traumatology the First Affiliated Hospital of Zhejiang Chinese Medical UniversityHangzhouChina Department of Mechanical Engineering&Materials Science School of EngineeringWashington UniversitySt.LouisMOUSA Shriners Hospital for Children St.LouisMOUSA

Atrophic fracture nonunion poses a significant clinical problem with limited therapeutic *** this study,we developed a unique nonunion model with high clinical relevance using serum transfer-induced rheumatoid arthritis(RA).Arthritic mice displayed fracture nonunion with the absence of fracture callus,diminished angiogenesis and fibrotic scar tissue formation leading to the failure of biomechanical properties,representing the major manifestations of atrophic nonunion in the ***,we demonstrated that the angiogenesis defect observed in RA mice was due to the downregulation of SPP1 and CXCL12 in chondrocytes,as evidenced by the restoration of angiogenesis upon SPP1 and CXCL12 treatment in *** this regard,we developed a biodegradable scaffold loaded with SPP1 and CXCL12,which displayed a beneficial effect on angiogenesis and fracture repair in mice despite the presence of ***,these findings strongly suggest that the sustained release of SPP1 and CXCL12 represents an effective therapeutic approach to treat impaired angiogenesis and fracture nonunion under inflammatory conditions.

关键词： CXCL12 angiogenesis impaired

Domain Reversal Characteristics of Near-Stoichiometric LiNbO3 Crystals

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Chinese Physics Letters 2000年第7期17卷 513-514页

作者： Yao Jiang-Hong XU Jing-jun ZHANG guang-Yin CHEN xiao-jun LI Bing LI guan-Gao Photonics Research Center College of Physics ScienceNankai UniversityTianjin 300071 Department of Physics College of Physics ScienceNankai UniversityTianjin 300071 National Laboratory for Infrared Physics Chinese Academy of SciencesShanghai 200083

The domain reversal characteristics of near-stoichiometric LiNbO3 ([Li]/[Li+Nb]=0.496) single crystals, which are grown by the Czochralski method with K2O tlux, are investigated. The switch tield for 180° ferroelectric domain reversal in the near-stoichiometric LiNbO3 crystal is 8.0±0.5kV/mm, which is only one third of the switching field required for the congruent LiNbO3 crystals. We have successfully achieved 180° domain reversal in near-stoichiometric LiNbO3 samples of 1.0mm thickness.

关键词： LiNbO3 Crystal ferroelectric

Optimal Formation Reconfiguration Control of Multiple UCAVs Using Improved Particle Swarm Optimization

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Journal of Bionic Engineering 2008年第4期5卷 340-347页

作者： Hai-bin Duan guan-jun Ma De-lin Luo School of Automation Science and Electrical Engineering Beihang University Beijing 100191 P. R. China Provincial Key Laboratory for Information Processing Technology Suzhou University Suzhou 215006 P. R. China Center for Systems and Control Xiamen University Xiamen 361005 P. R. China

Optimal formation reconfiguration control of multiple Uninhabited Combat Air Vehicles （UCAVs） is a complicated global optimum problem. Particle Swarm Optimization （PSO） is a population based stochastic optimization technique inspired by social behaviour of bird flocking or fish schooling. PSO can achieve better results in a faster, cheaper way compared with other bio-inspired computational methods, and there are few parameters to adjust in PSO. In this paper, we propose an improved PSO model for solving the optimal formation reconfiguration control problem for multiple UCAVs. Firstly, the Control Parameterization and Time Diseretization （CPTD） method is designed in detail. Then, the mutation strategy and a special mutation-escape operator are adopted in the improved PSO model to make particles explore the search space more efficiently. The proposed strategy can produce a large speed value dynamically according to the variation of the speed, which makes the algorithm explore the local and global minima thoroughly at the same time. Series experimental results demonstrate the feasibility and effectiveness of the proposed method in solving the optimal formation reconfiguration control problem for multiple UCAVs.

关键词： uninhabited combat air vehicles particle swarm optimization control parameterization and time discretization optimal formation reeonfiguration

Therapeutic Efficacy of Shexiang Baoxin Pill Combined with Exercise in Patients with Heart Failure with Preserved Ejection Fraction: A Single-Center, Double-Blind, Randomized Controlled Trial

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Chinese Journal of Integrative Medicine 2023年第2期29卷 99-107页

作者： LIU Si-pei ZHOU Jian-guan JIN Yan GUO Yan ZHOU Shi-wei LIN Mei-lan ZHANG jun WANG xiao-nv guan Xia-fei WANG Lei Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese MedicineNanjing 210008China Department of Rehabilitation College of Acupuncture and Moxibustion and Massage Health Preservation and RehabilitationNanjing University of Chinese MedicineNanjing 210023China Division of Cardiovascular Rehabilitation Ruian Hospital of Traditional Chinese MedicineRuianZhejiang Province 325299China Xiyuan Hospital China Academy of Chinese Medical SciencesBeijing 100091China

Objective:To evaluate the therapeutic efficacy of Shexiang Baoxin Pill combined with exercise in heart failure patients with preserved ejection fraction(HFpEF).Methods:Sixty patients with HFpEF were randomly divided into group A(n=20),receiving Shexiang Baoxin Pill combined with home-based exercise training based on conventional drugs for 12 weeks;group B(n=20),receiving conventional drugs combined with home-based exercise training for 12 weeks;and group C(n=20),receiving conventional drug treatment *** oxygen uptake(peakVO2),anaerobic threshold(AT),6-min walking test(6MWT),Pittsburgh Sleep Quality Index(PSQI),and SF-36 questionnaire(SF-36)results before and after treatment were compared among ***:After the 12-week intervention,patients in group C showed significant declines in peakVO2,AT,6MWT,PSQI,and SF-36 compared with pre-treatment(P<0.01),while groups A and B both showed significant improvements in peakVO2,AT,6MWT,PSQI,and SF-36 results compared with pre-treatment(P<0.01).Compared with group C,patients in groups A and B showed significant improvements in peakVO2,AT,6MWT,PSQI,and SF-36(P<0.01).In addition,patients in group A showed more significant improvements in physical function,role-physical,vitality,and mental health scores on the SF-36 questionnaire,and PSQI scores than those in group B(P<0.01).Conclusions:Exercise training improved exercise tolerance,sleep quality and quality of life(QoL)in patients with ***,Shexiang Baoxin Pill played an active role in sleep quality and QoL of patients with HFpEF.

关键词： heart failure preserved ejection fraction exercise training Shexiang Baoxin Pill

Predicting buckling of carbon fiber composite cylindrical shells based on backpropagation neural network improved by sparrow search algorithm

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Journal of Iron and Steel Research International 2023年第12期30卷 2459-2470页

作者： Wei guan Yong-mei Zhu jun-jie Bao Jian Zhang School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang212003JiangsuChina

The buckling load of carbon fiber composite cylindrical shells(CF-CCSs)was predicted using a backpropagation neural network improved by the sparrow search algorithm(SSA-BPNN).Firstly,two CF-CCSs,each with an inner diameter of 100 mm,were manufactured and *** buckling behavior of CF-CCSs was analyzed by finite element and ***,the effects of ply angle and length–diameter ratio on buckling load of CF-CCSs were analyzed,and the dataset of the neural network was generated using the finite element *** this basis,the SSA-BPNN model for predicting buckling load of CF-CCS was *** results show that the maximum and average errors of the SSA-BPNN to the test data are 6.88%and 2.24%,*** buckling load prediction for CF-CCSs based on SSA-BPNN has satisfactory generalizability and can be used to analyze buckling loads on cylindrical shells of carbon fiber composites.

关键词： Composite cylindrical shell:Carbon fiber Backpropagation neural network Sparrow search algorithm Buckling

Dynamic Couplingand Cooperative Control for Multi-paralleled Doubly Fed Induction Generator Wind Farms during Symmetrical Low Voltage Ride-through in a Weak Grid

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Protection and Control of Modern Power Systems 2024年第3期9卷 112-125页

作者： Lei guan jun Yao the College of Electrical Engineering at Chongqing University ChongqingChina the State Key Laboratory of Power Transmission Equipment Technology School of Electrical EngineeringChongqing UniversityChongqing 400044China

In multi-fed grid-connected systems,there are complex dynamic interactions between different pieces of *** in situations of weak-grid faults,the dynamic coupling between equipment becomes more *** may cause the system to experience small-signal instability during the fault *** this paper,multi-paralleled doubly fed induction generator(DFIG)-based wind farms(WFs)are taken as an example to study the dynamic coupling within a multi-fed system during fault steady-state of symmetrical low voltage ride-through(LVRT)in a weak *** analysis reveals that the dynamic coupling between WFs will introduce a damping shift to each *** inevitably affects the system’s dynamic stability and brings the risk of small-signal instability during fault steady-state in LVRT *** the distance to fault location and fault severity will exacerbate the dynamic coupling between *** of the dynamic coupling,adjusting the control state of one WF will affect the stability of the remaining WFs in the ***,a cooperative control strategy for multi-paralleled DFIG WFs is proposed to improve dynamic stability during *** analysis and the effectiveness of the proposed control strategy are verified by modal analysis and simu-lation.

关键词： Doubly fed induction generator(DFIG) wind farms(WFs) dynamic stability low voltage ride through(LVRT) weak grid dynamic coupling

Progress of hidden spin polarization in inversion-symmetric crystals

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Science China(Physics,Mechanics & Astronomy) 2022年第3期65卷 1-18页

作者： Shan guan Jia-Xin Xiong Zhi Wang jun-Wei Luo State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Academy of Quantum Information Sciences Beijing 100193China

Hidden spin polarization refers to that doubly degenerate bands protected by combined inversion and time-reversal symmetry in nonmagnetic inversion-symmetric crystals could have opposite non-zero local spin polarizations, which are spatially separated in two real-space sectors paired by the inversion symmetry. Since its first prediction from ab initio calculation, hidden spin polarization has inspired tremendous interest and has been observed experimentally due to its intriguing fundamental properties as well as the great potential for applications. Moving forward, the search for moment-dependent spin splitting has also been extended to antiferromagnets even without considering spin-orbit coupling. This paper systematically reviews recent works in this field with a focus on basic concepts and material realization. It also details several remaining bottlenecks and suggests possible avenues for future research.

关键词： spin-orbit coupling hidden spin polarization tight-binding model ab initio calculation

A Formation Reconfiguration Algorithm for Multi-UAVs Based on Distributed Cooperative Coevolutionary with an Adaptive Grouping Strategy

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Chinese Journal of Electronics 2020年第5期29卷 841-851页

作者： LIU Huaxian LIU Feng ZHANG Xuejun guan Xiangmin CHEN jun School of Electronic and Information Engineering Beihang University General Aviation Institute of Zhejiang JianDe Department of General Aviation Civil Aviation Management Institute of China School of Engineering and Materials Science Queen Mary University of London

The Formation reconfiguration problem plays a crucial role in the implementation of complex tasks for multiple unmanned aerial vehicles, which attracted increasing attention in the past decade. Taking into consideration the control parameters and time discretization of the multi-UAVs in the 3 Dimensional(3-D) space, the formation reconfiguration problem can be formulated as a large-scale combinatorial optimization problem with complex constraints and tight couplings between variables. The problem results in the reduction in efficiency and effectiveness using classic bio-inspired algorithms. In this paper, a formation reconfiguration method based on cooperative coevolutionary algorithm is proposed along with a new decomposition strategy to improve the optimization capability and prevent premature convergence. In the proposed approach, variables of multi-UAV are divided into several sub-groups based on an adaptive grouping strategy. The proposed strategy groups the variables in order to better deal with the tight coupling among them, taking into account the variables’ variance and multi-UAVs characteristics of the formation reconfiguration problem. Therefore, each subgroup can adopt the Self-adaptive differential evolution strategy with neighborhood search(SaNSDE) with the aim to optimize the UAV’s control inputs using multithreaded programming. SaNSDE contributes to calculating the results in a fully distributed and paralleled *** solution is then obtained through cooperation and coordination with all subcomponents. Simulation results based on extreme scenarios adopted by previous researches demonstrate that the proposed algorithm outperformed the existing approaches including Particle swarm optimization(PSO), Differential evolution(DE),and the cooperative coevolution algorithms with different well-known grouping strategies.

关键词： Formation reconfiguration Multi-UAV Grouping strategy Cooperative coevolutionary Distributed