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Study of Nanosecond Pulsed Hollow-Cathode Electron Beam Generation and Transportation Based on Pic-Mcc Simulation

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SSRN 2023年

作者： Huo, Weijie He, Weiguo Han, Luofeng Zhu, Kangwu Wang, Feng Shanghai Aerospace Electronic Technology Institute Shanghai201109 China School of Mechatronic Engineering and Automation Shanghai University Shanghai200444 China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Hangzhou310024 China Key Laboratory of Gravitational Wave Precision Measurement of Zhejiang Province Taiji Laboratory for Gravitational Wave Universe Hangzhou310024 China Shanghai Aerospace Control Technology Institute Shanghai201109 China

This work employs the PIC-MCC method to study the nanosecond pulsed hollow-cathode discharge and electron beam generation process. The electron beam’s energy and current distribution characteristics at the anode exit are investigated, and the simulation’s grid and step sizes are set as 0.04 μm and 5*10-13 s, respectively. Experimental parameters are used in the simulation, and experimental results are also used to verify the simulation accuracy. The simulations investigate the transportation characteristics of the electron beam under different energies and currents and obtain the effects of voltage, current, and ion density on the distribution characteristics of the electron beam. The electron beam current generated by the hollow-cathode discharge is gradually transformed from a random distribution in the central region to a Gaussian distribution. Due to the ion channel caused by the action of runaway electron pre-ionization, the high-energy electron beam achieves focused transport over a certain distance, and the high-energy electron beam has a smaller Gaussian radius than the source input. Besides, the ion-focusing channel formed by the high-energy electron transportation process can realize the transportation of the high-current electron beam in the conduction stage. © 2023, The Authors. All rights reserved.

关键词： Electron beams

Effects of strain paths on the fracture forming limit of high strength structural steel sheets

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Effects of strain paths on the fracture forming limit of hig...

2020 International Conference on Internet of Things, Artificial Intelligence and Mechanical Automation, IoTAIMA 2020

作者： Xu, Teng Xia, Qin-Xiang Qi, Zhen-Jie Wu, Xiao-Yu Ran, Jia-Qi Gong, Feng Guangdong Provincial Key Laboratory of Micro Nano Optomechatronics Engineering College of Mechatronics and Control Engineering Shenzhen University China Guangdong Provincial Key Laboratory of Precision Equipment and Manufacturing Technology School of Mechanical and Automotive Engineering South China University of Technology China Shenzhen Key Laboratory of Advanced Manufacturing Technology for MouldandDie College of Mechatronics and Control Engineering Shenzhen University China National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials China

The cruciform two-axial tensile specimen was designed and the two-axial tensile test scheme for different strain paths was developed. The effect of strain paths on the forming limit of high strength structural steel plates was obtained by the DIC method. The results show that for the unidirectional alternating loading test scheme, the equivalent strain of the ultimate strain is less than the sum of the equivalent strains from each step. When the main strain direction of the specimen pre-strain is perpendicular to the final strain path, the forming limit decreases with the increase of the pre-strain. © 2020 Published under licence by IOP Publishing Ltd.

关键词： Strain

Dynamic Gesture Recognition Algorithm Based on 3D Convolutional Neural Network

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Computational Intelligence and Neuroscience 2021年 2021卷 4828102页

作者： Liu, Yuting Jiang, Du Duan, Haojie Sun, Ying Li, Gongfa Tao, Bo Yun, Juntong Liu, Ying Chen, Baojia Key Laboratory of Metallurgical Equipment and Control Technology of Ministry of Education Wuhan University of Science and Technology Wuhan430081 China Research Center for Biomimetic Robot and Intelligent Measurement and Control Wuhan University of Science and Technology Wuhan430081 China Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering Wuhan University of Science and Technology Wuhan430081 China Hubei Key Laboratory of Hydroelectric Machinery Design and Maintenance China Three Gorges University Yichang443002 China

Gesture recognition is one of the important ways of human-computer interaction, which is mainly detected by visual technology. The temporal and spatial features are extracted by convolution of the video containing gesture. However, compared with the convolution calculation of a single image, multiframe image of dynamic gestures has more computation, more complex feature extraction, and more network parameters, which affects the recognition efficiency and real-time performance of the model. To solve above problems, a dynamic gesture recognition model based on CBAM-C3D is proposed. key frame extraction technology, multimodal joint training, and network optimization with BN layer are used for making the network performance better. The experiments show that the recognition accuracy of the proposed 3D convolutional neural network combined with attention mechanism reaches 72.4% on EgoGesture dataset, which is improved greatly compared with the current main dynamic gesture recognition methods, and the effectiveness of the proposed algorithm is verified. © 2021 Yuting Liu et al.

关键词： Convolution

Microstructure and Properties of Graphene Reinforced Co-Based Composite Coating by Laser Cladding

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SSRN 2022年

作者： Chang, Wei Xiao, Guangchun Zhang, Hui Chen, Hui Yi, Mingdong Zhang, Jingjie Chen, Zhaoqiang Xu, Chonghai School of Mechanical and Automotive Engineering Qilu University of Technology Shandong Academy of Sciences Jinan250353 China Key Laboratory of Equipments Manufacturing and Intelligent Measurement and Control China National Light Industry Qilu University of Technology Shandong Academy of Sciences Jinan250353 China Shandong Institute of Mechanical Design and Research Jinan250031 China

Graphene (Gr)-reinforced Co-based (Co50) composite coatings were prepared on 40Cr steel substrates by laser cladding technology. The effects of different amounts of Gr addition on the microstructure and mechanical properties of the coating were studied. The addition of a proper amount of Gr can improve the comprehensive properties of the coating, and most Gr forms carbides, such as Cr23C6 and Cr7C3, under the action of laser irradiation. The addition of Gr can significantly refine the grains and evenly distribute them. When the addition of Gr is 3 ωt%, the average grain size is the smallest in the coating, which is 5.7 μm, and the highest microhardness reaches 777.5 HV0.2, which is an increase of 270.2% compared with the substrate. The unmelted Gr remains dispersed in the coating, which can improve lubrication and reduce friction. The average friction coefficient and wear volume are decreased to 0.335 and 4.26×107 μm3, which are approximately 54.2% and 28.0% of the substrate, respectively. © 2022, The Authors. All rights reserved.

关键词： Microstructure

Biomechanical Finite Element Methods Study of a Novel Internal Fixation System for Lumbar Spondylolysis

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SSRN 2025年

作者： Li, Jingyuan Du, Chengfei Wang, Yulei Du, Di Liang, Jinlong Shao, Nengqi Feng, Fanzhe Xu, Wenhao Xu, Yongqing Cui, Yi Center for Joint Surgery Intelligent Manufacturing and Rehabilitation Engineering Center The First Affiliated Hospital of Army Medical University Chongqing400038 China Chongqing Municipal Science and Technology Bureau Key Laboratory of Precision Medicine in Joint Surgery Chongqing400038 China Chongqing Municipal Education Commission Key Laboratory of Joint Biology Chongqing400038 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of mechanical engineering Tianjin University of Technology Tianjin300384 China Department of Orthopaedic Surgery 920th Hospital of Joint Logistics Support Force Kunming650032 China Department of Orthopaedic Surgery 920th Hospital of Joint Logistics Support Force No. 212 of Da-Guan Road Xishan District Kunming650032 China

ObjectiveThis study aimed to verify the biomechanical efficacy of a novel internal fixation system for repairing lumbar spondylolysis (LS). Additionally, the changes in the mechanical performance of the novel internal fixation device during compression were *** healthy 25-year-old male volunteer was recruited for lumbar spine CT data acquisition to construct and validate a nonlinear finite element model of the L4-S1 spinal segment (A). Based on this, models were established for L5 spondylolysis (B), traditional internal fixation (C), and the pressurization process of the novel LS repair device fixation (D→E→F). For these six models, we constrained the lower surface of the S1 vertebral body while applying an axial compression force of 500 N and a moment load of 7.5 N·m on the upper surface of the L4 vertebral body to simulate six motions of the lumbar spine. The performance of each finite element model was evaluated by comparing the range of motion (ROM), maximum displacement, and maximum pressure experienced by the lumbar spine under different motion *** with Model C, Models D, E, and F exhibited a reduced ROM and maximum displacement (1%-38.5%, 12.8%-63.6%, and 32.8%-80.2%) compared with Model C during six different motions. Notably, compared with Model C, the novel internal fixation models consistently demonstrated a decreasing trend in the maximum stress on the intervertebral discs (IVD) and an increasing trend in the maximum stress on the articular cartilage and maximum stress and displacement of the bone graft. Moreover, the novel internal fixation model displayed larger ranges of evenly distributed stresses on the isthmus and reduced maximum stress on the internal fixation device across all six motions, with improved stiffness effects during the pressurization process of the novel internal fixation system (D→E→F).ConclusionsAccording to several mechanical comparisons, the novel internal fixation system had better biomechan

关键词： Axial compression

Broadband Chaos Generation from Relaxation Oscillation-Free Polarization Mode of Vertical-Cavity Surface-Emitting Laser

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Guangxue Xuebao/Acta Optica Sinica 2025年第10期45卷

作者： Di, Chengzhen Liu, Qi Wang, Longsheng Zhao, Qingchun Guo, Yuanyuan Chang, Pengfa Jia, Zhiwei Wang, Anbang Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education Taiyuan University of Technology Shanxi Taiyuan030024 China College of Electronic Information and Optical Engineering Taiyuan University of Technology Shanxi Jinzhong030600 China Key Laboratory of Precision Measurement Physics Ministry of Shanxi Province Taiyuan University of Technology Shanxi Taiyuan030024 China School of Computer and Communication Engineering Northeastern University at Qinhuangdao Hebei Qinhuangdao066004 China Key Laboratory of Photonic Technology for Integrated Sensing and Communication Ministry of Education Guangdong University of Technology Guangdong Guangzhou510006 China

Objective Secure communication based on chaotic lasers has gained significant attention in recent years due to its high speed and compatibility with existing fiber-optic networks. Vertical-cavity surface-emitting lasers (VCSELs) are promising candidates, offering a compact structure and low power consumption. However, VCSELs are constrained by chaotic bandwidth limitations induced by relaxation oscillations, which reduce the secure transmission rate. Existing methods for broadening the chaos bandwidth often rely on complex external perturbations, which may hinder system synchronization. We propose a simplified method for generating broadband chaos by utilizing the relaxation-oscillation-free polarization mode of VCSELs. Methods We present a novel approach for generating broadband chaos by utilizing the relaxation-oscillation-free polarization mode of VCSELs. The experimental setup (Fig. 1) employs a custom single-mode VCSEL with a wavelength of 1550 nm and no internal isolator. The laser is powered by a low-noise current source and is equipped with precise temperature control to ensure stable operation. Optical feedback is provided via a fiber mirror, with its intensity regulated by a variable optical attenuator. Polarization controllers are used to align the feedback polarization, directing X mode feedback to the X mode and Y mode feedback to the Y mode. The output signals are separated into X+Y, X, and Y modes using polarization beam splitters. The spectral, temporal, and dynamic properties of the VCSEL are analyzed using an optical spectrum analyzer, a high-speed oscilloscope, and an electrical spectrum analyzer. key parameters, including bias current and feedback strength, are systematically varied and optimized to investigate their effects on chaos generation, with the aim of identifying the optimal conditions for achieving broadband chaos with the desired characteristics. Results and Discussions We begin with an in-depth analysis of the free-running VCSEL to e

关键词： Optical feedback

Optimization and Development of Wc-Co Cemented Carbide Slurry for Stereolithography-Based Additive manufacturing

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SSRN 2023年

作者： Tan, Jinlin Chen, Yongan Ling, Xile Guo, Hongshan Sun, Jinxing Zhao, Saijin Bai, Jiaming Zhou, Peng Zhang, Dongyang Gong, Feng Shenzhen Key Laboratory of High Performance Nontraditional Manufacturing College of Mechatronics and Control Engineering Shenzhen University Shenzhen518060 China Institute of Intelligent Manufacturing Technology Shenzhen Polytechnic University Shenzhen518055 China Shenzhen Blueswin Industrial Co. Ltd Shenzhen518117 China Institute of Critical Materials for Integrated Circuits Shenzhen Polytechnic University Shenzhen518000 China Hoffmann Institute of Advanced Materials Shenzhen Polytechnic University 7098 Liuxian Blvd Nanshan District Shenzhen518055 China Hubei Key Laboratory of Plasma Chemistry and Advanced Materials School of Materials Science and Engineering Wuhan Institute of Technology Wuhan430205 China College of Engineering Southern University of Science and Technology Nanshan District Shenzhen518055 China

Tungsten carbide-cobalt (WC-Co) cemented carbide has a wide rage of application prospects in a wide range of industries because of its high strength, high hardness, excellent wear resistance, high-temperature resistance, and corrosion resistance, etc. Additive manufacturing (AM) makes it possible to fabricate geometrically complex tools compared to traditional manufacturing techniques. However, the preparation of high solid loading, superior stability, and optimal curing thickness of WC-Co cemented carbide slurry remains challenging for creating dense cemented carbide parts via stereolithography-based additive manufacturing. In this work, the dispensability, stability, and curing thickness of WC-Co cemented carbide slurry were investigated. The WC-Co (94-6wt.%) cemented carbide slurry with high solid loading, low viscosity, and good stability, as well as sufficient curing thickness, was successfully achieved. This work provides a reference for additive manufacturing of near-net-shape WC-Co cemented carbide parts by stereolithography, viz. digital light processing (DLP). © 2023, The Authors. All rights reserved.

关键词： Curing

Advancing energy absorption in additively manufactured meta-plates through machine learning-driven inverse design

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Thin-Walled Structures 2025年 215卷

作者： Qingyuan Liu Liang Mou Lan Zhang Shuai Yuan Haiyang Peng Jinguo Ge Yunze Yang Yuhong Long Hualin Fan Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology School of Mechanical and Electrical Engineering Guilin University of Electronic Technology Jinji road Guilin Guangxi 541004 China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Transportation safety systems (e.g., automotive crash boxes, train front-end energy absorption structures) require energy absorbers to simultaneously control energy absorption ( EA ), peak crushing force or stress ( PCF , PCS ), mean crushing force or stress ( MCF , MCS ), and undulation of load carrying ( ULC ). This study proposed meta-plates, characterized by stacking layers, twisting angles, and wall thicknesses. An additive manufacturing constrained machine learning and genetic algorithm (ML-GA) co-design framework was designed to optimize the crashworthiness performances. Finite element (FE) simulations incorporating nonlinear material models and contact algorithms, combined with Latin hypercube sampling, efficiently explored 10.7% of the design space, capturing nonlinear large deformations under quasi-static compression up to 50% strain. 600 independent samples were calculated to evaluate the performance of the ML model, which achieved 96.0% prediction accuracy ( R 2 score). At a given target relative density ( ρ ∗ ) ranging from 4% to 14%, the optimized meta-plates demonstrated 80%–200% higher MCS compared to benchmark shell/plate lattices at equivalent ρ ∗ . The meta-plates also exhibited directional crushing behavior with crushing force efficiency ( CFE ) around 1.0. Experimental validations show < 6% deviation from predictions also witnessed the high MCS , low PCS , and nearly free from stress fluctuation for meta-plates with 8%, 10%, and 14% ρ ∗ values. This methodology enables rapid design of lightweight energy absorbers with tunable deformation modes and extremely high material efficiency, providing a paradigm shift from trial-and-error approaches to intelligent crashworthy structure development.

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Branch-and-cut-and-price for agile earth observation satellite scheduling

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European Journal of Operational Research 2025年

作者： Peng, Guansheng Wang, Jianjiang Song, Guopeng Gunawan, Aldy Xing, Lining Vansteenwegen, Pieter School of Advanced Engineering and Great Bay Institute for Advanced Study Great Bay University Dongguan523000 China Defense Innovation Institute Chinese Academy of Military Science Beijing100071 China College of Systems Engineering National University of Defense Technology Changsha410073 China National Key Laboratory of Information Systems Engineering National University of Defense Technology Changsha410073 China School of Computing and Information Systems Singapore Management University Singapore178902 Singapore Research Institute of Intelligent Control and Manufacturing System Jiangsu University of Technology Changzhou213001 China KU Leuven Institute for Mobility - CIB Leuven3001 Belgium

The Agile Earth Observation Satellite scheduling selects and sequences satellite observations of possible targets on the Earth's surface, each with a specific profit and multiple time windows. The objective is to maximize the collected profit of all observations completed under some operational constraints. The problem can be modeled as a variant of the Team Orienteering Problem with Time Windows (TOPTW). The key differences with the regular TOPTW are twofold: first, a time-dependent transition time is required for each pair of consecutive observations to adjust the camera's look angles. Second, the time windows of each target vary during different observation cycles, called "orbits". Some targets are invisible during certain orbits. We call this variant the Time-dependent Team Orienteering Problem with Variable Time Windows. In this paper, we present an efficient branch-and-cut-and-price (BCP) algorithm that exploits the problem's characteristics to solve it to optimality. Some algorithmic enhancements have been implemented, such as a Lagrangian bound, an ng-path relaxation, a primal heuristic, and subset-row inequalities. Extensive experiments on different configurations of benchmark instances demonstrate the superior performance of the proposed BCP algorithm and its algorithmic enhancements. Moreover, the primal heuristic yields a high-quality lower bound and outperforms state-of-the-art heuristics. Finally, we adopt our framework to solve the well-known TOPTW, and our algorithm is much faster than state-of-the-art exact algorithms. © 2025 Elsevier B.V.

关键词： Branch and bound method