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Numerical Simulation and Experimental Investigation on Friction and Lubrication Behaviors of Chevron Micro-Textured Valve Plate/Cylinder Block Interface With Various Area Densities

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Journal of Tribology 2025年第7期147卷 072201页

作者： Chen, Luanxia Liu, Zhanqiang Huang, Haihong Zhu, Yingying School of Mechanical Engineering Hefei University of Technology Hefei230009 China Key Laboratory of Green Design and Manufacturing of Mechanical Industry Hefei University of Technology Hefei230009 China School of Mechanical Engineering Shandong University Jinan250061 China State Key Laboratory for High-end Equipment and Advanced Technology of Metal Forming Shandong University Jinan250061 China

As the critical friction pairs of swashplate-type axial piston pumps, the cylinder block/valve plate lubricating interface is the primary source of friction, wear, and leakage in axial piston pumps. Surface micro-texturing has been widely employed in cylinder block/valve plate conjunctions to ameliorate tribological performance. However, little research has been conducted to investigate the influence of chevron micro-texture area density on the tribological behaviors and lubricating properties of cylinder block/valve plate interface both experimentally and numerically. In this article, the chevron micro-textures with various area densities were manufactured on H62 brass by micro-milling and subsequently characterized with a laser scanning confocal microscope (LSCM). The friction and wear performance of H62 brass/38CrMoAl conjunctions were obtained via disc-on-disc tribological tests to simulate the cylinder block/valve plate lubricating interface. Moreover, the load-carrying capacity of untextured and chevron micro-textured samples was numerically investigated under hydrodynamic lubrication. It was found that the chevron micro-textured surface with an area density of 30.1% displayed the lowest friction coefficient and the shallowest wear depth. Although the load-carrying capacity of chevron micro-textured samples with a high dimple area density was larger, the severe stress concentration induced by the reduced micro-texture spacing caused the increment and large fluctuations of friction coefficient. Copyright © 2024 by ASME.

关键词： Friction

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Reachable Sets-based Trajectory Planning Combining Reinforcement Learning and iLQR

arXiv

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arXiv 2025年

作者： Huang, Wenjie Li, Yang Yuan, Shijie Teng, Jingjia Qin, Hongmao Bian, Yougang The State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China

The driving risk field is applicable to more complex driving scenarios, providing new approaches for safety decision-making and active vehicle control in intricate environments. However, existing research often overlooks the driving risk field and fails to consider the impact of risk distribution within drivable areas on trajectory planning, which poses challenges for enhancing safety. This paper proposes a trajectory planning method for intelligent vehicles based on the risk reachable set to further improve the safety of trajectory planning. First, we construct the reachable set incorporating the driving risk field to more accurately assess and avoid potential risks in drivable areas. Then, the initial trajectory is generated based on safe reinforcement learning and projected onto the reachable set. Finally, we introduce a trajectory planning method based on a constrained iterative quadratic regulator to optimize the initial solution, ensuring that the planned trajectory achieves optimal comfort, safety, and efficiency. We conduct simulation tests of trajectory planning in high-speed lane-changing scenarios. The results indicate that the proposed method can guarantee trajectory comfort and driving efficiency, with the generated trajectory situated outside high-risk boundaries, thereby ensuring vehicle safety during operation. Copyright © 2025, The Authors. All rights reserved.

关键词： Risk assessment

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Investigation on tensile modulus of lumen-bast fiber reinforced composites using multiscale simulation method

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Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica 2025年第5期42卷 2528-2537页

作者： Xia, Fan He, Liping Chen, Dachuan State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicles Hunan University Changsha410082 China College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China College of Civil Engineering Hunan University Changsha410082 China

Currently, the models for predicting the tensile modulus of bast fiber reinforced composites have not considered unique lumen microstructure of bast fibers. Therefore, in the present work, an equivalent model of lumen-bast fiber and its theoretical formula for calculating the elastic modulus were proposed in this study by combining the rule of mixture and Micro-CT technology. On this basis, a representative volume element (RVE) model of ramie fiber reinforced composite (RFPC) which considered lumen microstructures was established using multiscale simulation method, and its tensile modulus was computed. The validity of the RVE model was verified by experimental results. Additionally, the influence weights of four parameters (fiber content, fiber lumen ratio, fiber orientation, and aspect ratio) on the tensile elastic modulus of RFPC were investigated using orthogonal experimental design and variance analysis. It was found that fiber content and fiber orientation are the primary factors affecting the tensile modulus of RFPC. A polynomial fitting method was employed to obtain a predictive equation for estimating the tensile modulus of RFPC using these four parameters as independent variables. The main effects and synergistic effects of parameters on the tensile modulus of RFPC were systematically analyzed. This research provides a prediction method for estimating the tensile modulus of lumen-bast fiber reinforced composites and can be served as a theoretical basis for controlling their tensile performance. © 2025 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.

关键词： Jute fibers

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Manganese-based oxides cathodes for potassium-ion batteries: a review

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Journal of Energy Chemistry 2025年 108卷 1-18页

作者： Yue, Qinggang Xia, Maoting Zhou, Jiang Cheng, Juanjuan Lu, Bingan School of Physics and Electronics Hunan University Hunan Changsha410082 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Hunan Changsha410082 China School of Materials Science and Engineering and Key Laboratory of Nonferrous Metal Materials Science and Engineering Ministry of Education Central South University Hunan Changsha410083 China School of Materials Science and Engineering Hunan Provincial Key Lab of Advanced Materials for New Energy Storage and Conversion Hunan University of Science and Technology Hunan Xiangtan411201 China

Potassium-ion batteries (PIBs) were recognized for their natural abundance, high theoretical output voltage, and the availability of commercialized graphite anodes. However, the development of high-performance manganese-based layered oxide cathodes—a leading candidate for PIB systems—has been fundamentally constrained by irreversible phase transitions (PT) during the cycling process, manifesting as severe structural degradation and capacity fading. This review presents a transformative paradigm integrating machine learning (ML) with multiscale characterization to analyse the complex phase transition mechanisms in Mn-based cathodes. Through systematic ML-driven interrogation of structure–property relationships, we establish quantitative descriptors for phase stability and develop predictive models for transition dynamics. Furthermore, we highlight recent breakthroughs in cross-disciplinary approaches, enabling the rational design of PT-mitigated cathode architectures. By consolidating these insights into a unified knowledge framework, this work provides strategic guidelines for developing structurally robust Mn-based cathodes and outlines future research directions for next-generation PIB systems. © 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

关键词： Setting

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Massive GaN micro-LED array based underwater wireless optical communication

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Optics Express 2025年第9期33卷 19527-19534页

作者： Lv, Zhijian Liu, Xinyi Wu, Shuang Zhang, Wenwei Yue, C. Patrick Liu, Zhaojun Sino-German College of Intelligent Manufacturing Shenzhen Technology University Shenzhen China Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen China State Key Laboratory of Advanced Displays and Optoelectronics Technologies The Integrated Circuit Design Center Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Hong Kong

High-speed underwater wireless optical communication technology is a much-needed communication technology in current underwater applications, and micro-LED is a promising light source option. Considering the limitation of transmission distance due to the low optical power of a single micro-LED pixel, an underwater wireless optical communication system based on a novel massive GaN micro-LED array includes more than 5000 pixels fabricated via flip-chip technology is proposed, which can achieve 165-Mbps and 90-Mbps at 37.7 m and 73.5 m, respectively. Therefore, the feasibility of realizing a high data rate and long transmission distance in an underwater wireless optical communication system based on a novel massive micro-LED array is confirmed. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Fiber to the x

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Research on Real-Time Inspection Scheme of Tunnel Lining Surface Defects Based on YOLOv10

Research on Real-Time Inspection Scheme of Tunnel Lining Sur...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Fang, Enquan Li, Shijiao Liu, Zhen Wang, Yaodong Tao, Tao Guangzhou Metro Group Co. Ltd. Guangzhou510330 China State Key Laboratory of Advanced Rail Autonomous Operation Beijing Jiaotong University Beijing China Ministry of Education Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control Technology Beijing Jiaotong University Beijing100044 China

ISBN: (纸本)9789819639687

To address the issue of increasing tunnel surface defects due to prolonged service periods. This paper proposes an online recognition method using the YOLOv10 object detection algorithm for identifying tunnel surface conditions and intrinsic textures. Initially, tunnel inspection equipment was designed and deployed on a field operation inspection vehicle to facilitate the rapid acquisition of high-definition images of the tunnel surfaces. The collected images were meticulously annotated to highlight intrinsic textures such as cracks, water leaks, pipelines, bolt holes, and distribution boxes, resulting in 5,813 authentic tunnel defect images serving as the datasets for this study. Utilizing the YOLOv10 object detection model, the developed model achieved an accuracy of 80.6%, a recall rate of 77.8%, and an mAP0.5 of 81.3% on the experimental datasets. The model size is just 5.46 MB, and it achieves an FPS of 64.32, which is sufficient to meet the requirements for online detection and recognition tasks of tunnel surface defects. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Inspection equipment

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An efficient discrete physics-informed neural networks for geometrically nonlinear topology optimization

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Computer Methods in Applied Mechanics and Engineering 2025年 442卷

作者： Yin, Jichao Li, Shuhao Zhang, Yaya Wang, Hu State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Beijing Institute of Technology Shenzhen Automotive Research Institute Shenzhen518000 China

The application of geometrically nonlinear topology optimization (GNTO) poses a substantial challenge due to the extensive memory requirements and prohibitive computational demands involved. To tackle this challenge, a discrete physics-informed neural network (dPINN) is suggested as a promising approach to alleviate computational demands and enhance the applicability to large-scale problems. In comparison to collocation point-based PINNs, the most distinctive characteristic of dPINN is its mesh-based local interpolation for the evaluation of the system energy. This approach not only circumvents the issue of material mapping between elements and collocation points, but also provides improved robustness. Moreover, the partial differential equation (PDE) that corresponds to the adjoint equations lacks explicit expressions. The dPINN is capable of naturally evaluating equivalent energy through discrete expressions, a capability that collocation point-based PINNs lack. Furthermore, the activation state of sub-networks in series is determined in accordance with the density variation, thereby saving computational costs by dynamically incorporating each sub-network to reduce the trainable parameters in certain optimization steps, while conserving computational resources. The dPINN demonstrates exceptional accuracy and efficiency, along with enhanced resilience against mesh distortion compared to the finite element method (FEM), thereby enabling the application of larger loads. The dPINN-based GNTO is validated to be robust with regard to different geometries, loads, and volume fractions through several examples, and the outcomes are largely consistent with those of the FEM-based approach. Of greater significance is the fact that dPINN is capable of solving a million-DOFs 3D GNTO problem, which represents a notable advantage. © 2025 Elsevier B.V.

关键词： Mesh generation

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Unraveling the reaction mechanism of high reversible capacity CuP_(2)/C anode with native oxidation PO_(x) component for sodium-ion batteries

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Chinese Chemical Letters 2025年第1期36卷 574-578页

作者： Huixin Chen Chen Zhao Hongjun Yue Guiming Zhong Xiang Han Liang Yin Ding Chen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China CAS key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China College of Materials Science and Engineering Co-Innovation Center of Efficient Processing and Utilization of Forest ResourcesNanjing Forestry UniversityNanjing 210037China Laboratory of Advanced Spectro-electrochemistry and Li-ion Batteries Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Institute of Physics Chinese Academy of SciencesBeijing 100190China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi institutesChinese Academy of SciencesXiamen 361021China

Phosphorus-based anode is a promising anode for sodium-ion batteries(SIBs)due to its high specific capacity,however,suffers from poor electronic conductivity and unfavorable electrochemical *** metals such as copper(Cu)into phosphorus has been demonstrated to not only improve the electronic conductivity but also accommodate the volume change during cycling,yet the underline sodiation mechanism is not ***,take a copper phosphide and reduced graphene oxide(CuP_(2)/C)composite as an example,which delivers a high reversible capacity of>900 mAh/***,it is revealed that the native oxidation PO_(x)components of the CuP_(2)/C composite show higher electrochemical reversibility than the bulk Cu P_(2),based on a quantitative analysis of high-resolution solid-state^(31)P NMR,ex-situ XPS and synchrotron X-ray diffraction characterization *** sodiation products Na_(3)PO_(4) and Na_(4)P_(2)O_(7) derived from PO_(x) could react with Na-P alloys and regenerate to PO_(x) during charge process,which probably accounts for the high reversible capacity of the Cu P_(2)/C *** findings also illustrate that the phosphorus transforms into nanocrystalline Na_(3)P and Na_(x)P alloys,which laterally shows crystallization-amorphization evolution process during cycling.

关键词： CuP_(2)/C composite POx component Reaction mechanism Solid-state NMR Sodium-ion batteries

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RGB-Based Category-Level Object Pose Estimation via Depth Recovery and Adaptive Refinement

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IEEE Robotics and Automation Letters 2025年第6期10卷 5377-5384页

作者： Yang, Hui Sun, Wei Liu, Jian Zheng, Jin Zeng, Zhiwen Mian, Ajmal Hunan University National Engineering Research Center for Robot Visual Perception and Control Technology College of Electrical and Information Engineering Changsha410082 China Hunan University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Changsha410082 China Central South University School of Architecture and Art Changsha410082 China University of Western Australia Department of Computer Science and Software Engineering CrawleyWA6009 Australia

Category-level pose estimation methods have received widespread attention as they can be generalized to intra-class unseen objects. Although RGB-D-based category-level methods have made significant progress, reliance on depth image limits practical application. RGB-based methods offer a more practical and cost-effective solution. However, current RGB-based methods struggle with object geometry perception, leading to inaccurate pose estimation. We propose depth recovery and adaptive refinement for category-level object pose estimation from a single RGB image. We leverage DINOv2 to reconstruct the coarse scene-level depth from the input RGB image and propose an adaptive refinement network based on an encoder-decoder architecture to dynamically improve the predicted coarse depth and reduce its gap from the ground truth. We introduce a 2D–3D consistency loss to ensure correspondence between the point cloud obtained from depth projection and the objects in the 2D image. This consistency supervision enables the model to maintain alignment between the depth image and the point cloud. Finally, we extract features from the refined point cloud and feed them into two confidence-aware rotation regression branches and a translation and size prediction residual branch for end-to-end training. Decoupling the rotation matrix provides a more direct representation, which facilitates parameter optimization and gradient propagation. Extensive experiments on the REAL275 and CAMERA25 datasets demonstrate the superior performance of our method. Real-world estimation and robotic grasping experiments demonstrate our model robustness to occlusion, clutter environments, and low-textured objects. Our code and robotic grasping video are available at DA-Pose. © 2016 IEEE.

关键词： Depth perception

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A Stable RTK/MEMS-IMU Tightly-Coupled Algorithm under Differential Corrections Outage

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IEEE Transactions on Vehicular technology 2025年

作者： Bian, Yougang Cao, Shipeng Wang, Guangcai Qin, Xiaohui Hu, Manjiang Qin, Hongmao Hunan University State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Changsha410082 China Hunan University Wuxi Intelligent Control Research Institute Wuxi214115 China

The GNSS-RTK and MEMS-IMU integrated navigation system is a commonly used high-precision, low-cost solution for outdoor positioning. However, the significant measurement error of MEMS-IMU can rapidly lead to divergence in navigation state predictions based on inertial error propagation models. To overcome this limitation and enhance accuracy, maintaining the continuity of RTK measurement information is crucial. Nevertheless, due to the instability of wireless transmission links and communication equipment, or disruptions in base station observations, differential corrections often experience outages, resulting in a decline in measurement information quality and affecting the accuracy of integrated navigation. Therefore, this paper proposes a stable RTK/MEMS-IMU tightly coupled algorithm. During outages of differential corrections, the proposed algorithm utilizes historical differential corrections from the base station along with real-time rover station information to construct a stable double-difference carrier phase vector. This approach ensures the stability of measurement information and enhances positioning accuracy. Simulation results have verified the effectiveness of this method, and land tests have demonstrated that, compared to the traditional RTK/MEMS-IMU tightly coupled algorithm, the position and velocity accuracy of this algorithm during outages of differential corrections have been improved by 29.5% and 18.4%, respectively. © 1967-2012 IEEE.

关键词： Base stations

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