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Generation of Multi-Channel Co-axial Quasi-Perfect Vortex Electromagnetic Waves with Equal Divergence Radii Based on Aperture-Shared Metasurface

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IEEE Transactions on Antennas and Propagation 2025年

作者： Deng, Li Yang, Kaiqiao Yin, Kaiyue Chen, Jiawei Qu, Meijun Feng, Botao Beijing University of Posts and Telecommunications Beijing Laboratory of Advanced Information Networks Beijing Key Laboratory of Network System Architecture and Convergence Beijing100876 China Southeast University Institute of Electromagnetic Space State Key Laboratory of Millimeter Wave Nanjing211189 China Communication University of China School of Information and Communication Engineering Beijing Beijing100024 China Shenzhen University College of Electronics and Information Engineering Shenzhen518060 China

Vortex electromagnetic (EM) waves hold significant promise for next-generation wireless communication applications. However, their practical deployment is hindered by varying divergence characteristics across vortex modes with different mode numbers. To overcome this challenge and enable true spatial multiplexing of orbital angular momentum (OAM) waves, a dual-polarized shared-aperture metasurface is proposed. By leveraging both polarization and OAM multiplexing, quasi-perfect vortex (QPV) EM waves with co-axial beams and equal divergence radii are successfully generated at microwave frequencies. Initially, the properties of quasi-perfect vortex waves in the microwave band are analyzed, followed by the design of a dual-polarized metasurface unit. This unit integrates parasitic damping-coupled patches based on the traditional Jerusalem cross structure, providing polarization-independent control and approximately 360° phase-tuning capability. Furthermore, simulations validate the effectiveness of the dual-polarized single-mode metasurface design. Based on this, the concept is extended to a 4-channel multiplexing metasurface, operating at 15 GHz and capable of generating QPV waves. Finally, experimental results from the fabricated metasurface demonstrate the generation of QPV waves with OAM mode numbers 0, +2, +1, and -1, achieving simulated and measured OAM mode purities of 0.835 and 0.70, respectively. The experimental data closely aligns with simulations, confirming the effectiveness of the design. This study offers new insights into generating and applying perfect vortex EM waves, paving the way for high-capacity near-field wireless communication systems and advanced control of novel EM physical dimensions. © 1963-2012 IEEE.

关键词： Near field communication

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Modified Hough Transform Based Registration Method for Heavy-haul Railway Rail Profile with Intensive Environmental Noise

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IEEE Transactions on Instrumentation and Measurement 2025年

作者： An, Yuntong Cao, Yuan Sun, Yongkui Su, Shuai Wang, Feng Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation Control System School of Automation and Intelligent Beijing100044 China Beijing Jiaotong University Frontiers Science Center for Smart High-speed Railway System Beijing100044 China Beijing Jiaotong University State Key Laboratory of Advanced Rail Autonomous Operation Beijing100044 China

In heavy-haul railway inspections, accurate rail profile registration is essential for assessing wear and deformation of tracks. In this process, identifying the rail waist arc as key segments and determining the center of the arc as feature points are crucial steps for rough rail profile registration, often affected by noise from sensors, surface contaminants, and environmental factors. To address these challenges, a profile registration method is proposed, with the Modified Hough Transform (MHT) as a core component. The method first segments key profile sections using curvature thresholds to identify arc segments. For each point in these segments, MHT constructs circles with fixed radius and calculates their intersection points. A distance matrix based on Euclidean distances between intersection points is generated. By sorting and normalizing these distances, the method identifies local density variations and calculates density coefficients to find the circle center, without manual thresholding. Comparative experiments on simulated and field data show that the proposed method achieves high accuracy and robustness in noisy environments. The dual validation confirms its reliability, making this method effective for rail profile registration in heavy-haul railway inspections. © 1963-2012 IEEE.

关键词： Hough transforms

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Joining copper to thermosetting polymer via “Mortise and Tenon” interlocking and chemical-bonding both in-situ generated during friction stir spot welding

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Journal of Manufacturing Processes 2025年 149卷 318-330页

作者： Yidi Wu Jiaxun Li Zijie Huang Fangzheng Shi Licheng Sun Huihong Liu Gaoqiang Chen Peng Li Yongbing Li Zhongqin Lin Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures Shanghai Jiao Tong University Shanghai 200240 PR China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240 PR China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical Engineering Tsinghua University Beijing 100084 PR China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing 100084 PR China Shanghai Radio Equipments Research Institute 201109 Shanghai PR China School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 PR China

This study successfully joined the hard-to-weld combination of Cu and thermosetting polyimide (PI) for the first time using a novel strategy combining chemical plating and friction stir spot welding (FSSW). A thin Cu layer was first chemical-plated on a surface-roughened PI sheet, then a thick Cu sheet was friction stir spot welded onto the chemical-plated PI. Under the appropriate thermo-mechanical conditions, Cu sheet beneath the stir zone was bonded atomically with the chemical-plated Cu layer, transferring both vertically downward force and horizontally shearing torque to the Cu materials approaching to the Cu/PI interface. A strong “mortise and tenon” interlocking was thus generated at the Cu/PI interface owing to the plastic deformation of Cu and the constraint from PI. Simultaneously, the released CO and NO₂ gases from PI, along with the thermal environment, oxidized the Cu surface at the Cu/PI interface, forming a nanoscale Cu₂O layer. This enabled chemical bonding between the functional group (-C=O) on the PI's surface and the Cu₂O oxide on the Cu surface. Both “mortise and tenon” interlocking and chemical bonding were finally generated in-situ during the welding process, thereby playing a remarkable effect on improving the mechanical performance of Cu/PI joints.

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Novel Mobility Formula for Parallel Mechanisms Expressed with Mobility of General Link Group

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1082-1090页

作者： ZHANG Yitong LU Wenjuan MU Dejun YANG Yandong ZHANG Lijie ZENG Daxing Key Laboratory of Parallel Robot and Mechatronic System Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University

The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new formulae have been presented, however these formulae can hardly intuitively reflect general link group＇s restrictions on output member and its influences on independence of output parameters, which is premise to the judgment of the properties of mobility. Towards the problem to reveal the intrinsic relationship between the degree of freedom（DOF） of a mechanism, the link group, and the dimension of output parameters, also to avoid determination of virtual constraint, based on the new concepts of the ＂DOF of general link group＂ and ＂node parameters＂, a new formula in the calculation of the mobility of mechanisms is presented that is expressed with DOFs of the general link groups and rank of motion parameters of base point of the output link. It is named GOM（mobility of groups and output parameter） formula. On the basis of new concepts of＂effective parameters＂ and ＂invalid parameters＂, a rule is put forward for solving the DOF of mechanisms with invalid parameters by GOM formula, that is, the base point parameters are the subset of effective parameters of link group. Thereafter, several examples are enumerated and the results coincide with the prototype data, which proves the validity of the proposed formula. Meanwhile, it is obtained that the necessary and sufficient condition for the judgment of output parameters independence is that each of the DOF of the link group is not less than zero. The proposed formula which is simple in calculation provides theoretical basis for the judgment of independence of output parameters and provides references for type synthesis of novel parallel mechanisms with independence requirements of their output parameters.

关键词： parallel mechanism degree of freedom general link group output parameters

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Bauschinger effect in nano-grinding of 3C-SiC: A molecular dynamics study

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Wear 2025年

作者： Zhao, Xiangyang Tang, Yunqing Chen, keyang Cai, Yukui Liang, Xiaoliang Liu, Zhanqiang Li, Dongyang School of Mechanical Engineering Shandong University Jinan250061 China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Jinan250061 China Key National Demonstration Center for Experimental Mechanical Engineering Education Jinan250061 China Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology Guilin University of Electronic Technology Guilin541004 China Department of Chemical and Materials Engineering University of Alberta EdmontonABT6G 2H5 Canada

The Bauschinger effect typically occurs in ductile materials and influences their tribological behaviors. However, this phenomenon is rarely reported in brittle materials. The nano-scale plastic deformation observed in brittle materials implies that the Bauschinger effect may also occur during their nano-tribological processes. In this study, molecular dynamics simulations were employed to evaluate the Bauschinger effect in cubic silicon carbide (3C-SiC) and its effect on nano-grinding of 3C-SiC. The results show that defects generated in 3C-SiC during shear deformation recover upon reversal of the shear direction, and defects near the surface of 3C-SiC workpiece generated during nano-grinding also recover upon reversal of the grinding direction, which validates the hypothesis that the Bauschinger effect may occur in 3C-SiC and could benefit its machinability. The Bauschinger effect during bi-directional grinding could help significantly reduce the damage and roughness to the surface of 3C-SiC and also help lower the machining resistance. Such benefits from the Bauschinger effect are found to be more pronounced at relatively lower temperatures, which makes the machinability of 3C-SiC during the bi-directional grinding at relatively lower temperatures comparable to that during the unidirectional grinding at higher temperatures. Therefore, taking advantage of the Bauschinger effect could help lower the operation temperature for high-quality and high-efficiency grinding of 3C-SiC with reduced defects, roughness, and resistance. This study provides an insight into the nano-tribological behaviors of brittle materials and demonstrates an effective approach for their ultra-precision machining. © 2025 Elsevier B.V.

关键词： Machinability

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Laser cladding WC/Fe composite coating on nose rail of turnout: Microstructure characteristics and wear behaviors

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Wear 2025年

作者： Ding, Haohao Cui, Tong Wang, Wenjian Lin, Qiang Wang, Liang Yang, Yi Yang, Wenbin Zhang, Qunli Xiao, Qian Qi, Huan Tribology Research Institute State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China Mechanical Industry Key Laboratory of Damage Mechanism and Protection Technology for High-speed Friction Pairs Southwest Jiaotong University Chengdu610031 China Institute of Laser Advanced Manufacturing Zhejiang University of Technology Hangzhou310023 China Chengdu Qingshi Laser Technology Co. Ltd Chengdu610213 China State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastucture East China Jiaotong University Nanchang330013 China

The nose rail of turnout is suffering from severe impact and sliding wear due to its irregular structure. As a surface repairing technology, laser cladding has an application possibility to improve the wear resistance. Furthermore, WC particles possess high hardness and good wettability with Fe-base alloys. Therefore, the laser cladding process of WC/Fe composite coating on nose rail is optimized and the wear behavior is explored. WC/Fe composite coatings with different WC contents (0-40 wt%) are produced on the nose rail material (high manganese steel) using a MMRO-2 fiber laser. It is found that with the increase in WC content, the microstructure size is reduced, the proportion of equiaxed dendrites is increased and the hardness is improved. When the WC content is increased to 40 wt%, cracks are formed during cladding. To solve this problem, three optimization methods are explored: adjustment of laser energy density, laser remelting and ultrasonic vibration assistance. The results show that the increase in the energy density, remelting power, vibration amplitude could reduce the number of cracks. Finally, impact and sliding tests are performed to study the wear behavior of WC/Fe composite coating. It is found that with the increase in WC content to 30 wt%, both the impact and sliding wear resistances of coating are enhanced. With the continuing increase to 40 wt%, the impact wear resistance is reduced but the sliding wear resistance is slightly increased. The impact damage form is predominated by spalling, and the sliding damage form is dominated by ploughing. Comparing the three optimization methods, laser remelting could reduce the wear resistant due to the decline of coating hardness. However, improving the vibration amplitude could increase the wear resistance due to the increased hardness and decreased microstructure size. © 2025 Elsevier B.V.

关键词： Manganese steel

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An Image Semantic Communication system Based on GAN and Relative Position-Encoding

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IEEE Communications Letters 2025年

作者： Zhang, Ziqi Tan, Weijie Li, Chunguo Guizhou University College of Big Data and Information Engineering Guiyang550025 China Guizhou University State Key Laboratory of Public Big Data College of Computer Science and Technology Guiyang550025 China Advanced Cryptography and System Security Key Laboratory of Sichuan Province Chengdu610025 China Ministry of Industry and Information Technology Laboratory of Cryptography Application Technology Innovation and Testing Verification Beijing100015 China Southeast University School of Information Science and Engineering Nanjing210096 China

In image semantic communication, the complex wireless channel environment leads to the loss of image details and performance degradation during transmission. To address this issue, we propose an image semantic communication system based on Generative Adversarial Networks (GAN) and Relative Position-Encoding (RPE), named GAN-RpeSC. Specifically, in the system design, we introduce the GAN network at the output of the semantic communication framework to enhance the image restoration. We integrate the RPE module into the Visual Transformer (ViT) module, adding the RPE module to its Multihead Self Attention (MHSA), so that the model can better capture the spatial location information of the image. Experimental results show that the proposed GAN-RpeSC has significant advantages in improving image transmission quality, with a 0.3 dB improvement in peak signal-to-noise ratio (PSNR) compared to the ViT module alone. © 1997-2012 IEEE.

关键词： Encoding (symbols)

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Fabrication of a high-power pump and signal combiner with an asymmetric tapered fiber bundle utilizing un-pretreated pump fibers

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Optics Express 2025年第6期33卷 12349-12360页

作者： Ji, Mengyuan Liu, Kai Chen, Wenqi Yi, Xuezhuan Wang, Meng Tian, Lei Meng, Junqing Wangzhijiang Innovation Center for Laser Aerospace Laser Technology and System Department Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China Advanced Laser and Optoelectronic Functional Materials Department Special Glasses and Fibers Research Center Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Beijing Institute of Tracking and Telecommunication Technology Beijing100049 China

We report a fabrication method for addressing the non-uniform arrangement issues associated with the asymmetric tapered fiber bundles (TFBs) in high-power pump and signal combiners (PSCs), which do not require pre-treatment of the pump fibers. It employs a homemade thin-walled glass tube with the coating layer, and six pump fibers surround it evenly to collectively form the TFB, while the signal fiber remains unaffected during the tapering process of the fiber bundle. The 3D simulation model of the backward (6 + 1)×1 PSC was established by the refractive index distribution method to calculate the transmission efficiency of the pump light and signal light, and then identify the optimal preparation parameters for achieving the best efficiency. In this model, a simulated quasi-uniform energy distribution light field was used as the input of the pump fiber, which can optimize the previous calculation method. Experimental results exhibited that the backward (6 + 1)×1 PSC achieved signal light and pump light transmission efficiencies of over 96% and 98%, respectively, the beam quality degradation is ∆M2 = 0.09, and the total output pump power was 4.102 kW. The experimental results are in good agreement with the simulation results. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Refractive index

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Continual Reinforcement Learning for Digital Twin Synchronization Optimization

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IEEE Transactions on Mobile Computing 2025年

作者： Tong, Haonan Chen, Mingzhe Zhao, Jun Hu, Ye Yang, Zhaohui Liu, Yuchen Yin, Changchuan Beijing University of Posts and Telecommunications Beijing Key Laboratory of Network System Architecture and Convergence Beijing Advanced Information Network Laboratory Beijing China College of Computing and Data Science Singapore University of Miami Department of Electrical and Computer Engineering Frost Institute for Data Science and Computing Coral Gables33146 United States University of Miami Department of Industrial and Systems Engineering Coral Gables33146 United States Zhejiang University College of Information Science and Electronic Engineering Hangzhou310027 China North Carolina State University Department of Computer Science RaleighNC27695 United States Beijing Key Laboratory of Network System Architecture and Convergence China Beijing University of Posts and Telecommunications Beijing Advanced Information Network Laboratory Beijing100876 China

This article investigates the adaptive resource allocation scheme for digital twin (DT) synchronization optimization over dynamic wireless networks. In our considered model, a base station (BS) continuously collects factory physical object state data from wireless devices to build a real-time virtual DT system for factory event analysis. Due to continuous data transmission, maintaining DT synchronization must use extensive wireless resources. To address this issue, a subset of devices is selected to transmit their sensing data, and resource block (RB) allocation is optimized. This problem is formulated as a constrained Markov process (CMDP) problem that minimizes the long-term mismatch between the physical and virtual systems. To solve this CMDP, we first transform the problem into a dual problem that refines RB constraint impacts on device scheduling strategies. We then propose a continual reinforcement learning (CRL) algorithm to solve the dual problem. The CRL algorithm learns a stable policy across historical experiences for quick adaptation to dynamics in physical states and network capacity. Simulation results show that the CRL can adapt quickly to network capacity changes and reduce normalized root mean square error (NRMSE) between physical and virtual states by up to 55.2%, using the same RB number as traditional methods. © 2025 IEEE. All rights reserved.

关键词： Markov processes

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Synthesis of core–shell SiO2/polymer composite microspheres by miniemulsion polymerization and damping performance characteristics of formed thin film

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Discover Polymers 2025年第1期2卷 1-13页

作者： Cheng, Guanzhi Xing, An Xu, Tailin Guan, Wenxun Wang, Xi Xie, Yongjiang State Key Laboratory of High-Speed Railway Track System Beijing China Railway Engineering Research Institute China Academy of Railway Sciences Co. Ltd. Beijing China Research Center for Bioengineering and Sensing Technology University of Science and Technology Beijing Beijing China Institute for Advanced Study Shenzhen University Guangdong China

This study focuses on the synthesis of SiO2/polymer composite microspheres with core–shell structure via miniemulsion polymerization using styrene (St) and butyl acrylate (BA) as monomers, and encapsulating SiO2 nanoparticles during the processes. The resulting composite emulsion and its formed latex thin film were characterized by FT-IR, DLS, DSC, and DMA techniques to investigate the effects of emulsifier concentration, nanoparticle content, and monomer ratio on microsphere morphology and properties. TEM results showed a clear core–shell structure for SiO2/polymer composite microspheres under optimal conditions with an emulsifier (SDS) concentration of 30 mM, a SiO2 content of 5wt%, and a St:BA monomer ratio of 1:1. The maximum loss factor and damping peak area were found to be at their highest levels under these conditions, indicating potential for the composite material as a high-performance damping material due to its excellent mechanical properties and thermal stability.

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