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High temperature lubrication performance of chlorophenyl silicone oil

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Friction 2024年第8期12卷 1716-1727页

作者： Yan MENG Xiangli WEN Jie CHENG Pengpeng BAI Yonggang MENG Yu TIAN School of mechanical and Electrical Engineering China University of Mining and Technology-BeijingBeijing 100083China Department of mechanical Engineering State Key Laboratory of Tribology in Advanced EquipmentTsinghua UniversityBeijing 100084China

Most studies of liquid lubricants were carried out at temperatures below 200°***,the service temperature of lubricants for aerospace and aeroengine has reached above 300°*** order to investigate the friction mechanism and provide data for high temperature lubrication,the friction and wear properties of chlorophenyl silicone oil(CPSO)-lubricated M50 steel and Si3N4 friction pairs were investigated ***-on-disk experimental results show that the lubrication performance of CPSO varies significantly with *** 150°C,coefficient of friction(COF)remains at 0.13–0.15 after the short running-in stage(600 s),while the COF in the running-in stage is 0.2–*** 200°C and above,the running-in time is much longer(1,200 s),and the initial instantaneous maximum COF can reach *** this condition,the COF gradually decreases and finally stabilizes at around 0.16–0.17 *** phenomenon is mainly due to the different thickness of boundary adsorption *** importantly,the wear rate of M50 steel increases significantly with the temperature,while the wear rate barely changes at temperatures above 200°*** anti-wear mechanism is explained as tribochemical reactions are more likely to occur between CPSO and steel surface with the increased temperature,generating the FeCl2 protective film on the metal ***,FeCl2 tribochemical film improves the lubrication and anti-wear capacity of the *** high temperatures(200–350°C),FeCl2 film becomes thicker,and the contact region pressure becomes lower due to the larger wear scar size,so the wear rate growth of M50 steel is much smaller compared with that of low temperatures(22–150°C).The main findings in this study demonstrate that CPSO lubricant has good anti-wear and lubrication capacity,which is capable of working under temperatures up to 350°C.

关键词： chlorophenyl silicone oil(CPSO) liquid lubricant anti-wear high temperature

Recent advances on monolithic perovskite-organic tandem solar cells

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Interdisciplinary Materials 2024年第1期3卷 113-132页

作者： Guanshui Xie Huan Li Longbin Qiu Shenzhen key laboratory of intelligent Robotics and Flexible manufacturing Systems Department of Mechanical and Energy EngineeringSUSTech Energy Institute for Carbon NeutralitySouthern University of Science and TechnologyShenzhenChina

Perovskite-organic tandem solar cells(TSCs)have emerged as a groundbreaking technology in the realm of photovoltaics,showcasing remarkable enhancements in efficiency and significant potential for practical ***-organic TSCs also exhibit facile fabrication surpassing that of all-perovskite or all-organic TSCs,attributing to the advantageous utilization of orthogonal solvents enabling sequential solution process for each *** perovskite-organic TSCs capitalize on the complementary light absorption characteristics of perovskite and organic *** is a promising prospect of achieving further enhanced power conversion efficiencies by covering a broad range of the solar spectrum with optimized perovskite absorber,organic semiconductors as well as the interconnecting layer's optical and electrical *** review comprehensively analyzes the recent advancements in perovskite-organic TSCs,highlighting the synergistic effects of combining perovskite with a low open-circuit voltage deficit,organic materials with broader light absorption,and interconnecting layers with reduced optical and electrical ***,the underlying device architecture design,regulation strategies,and key challenges facing the high performance of the perovskite-organic TSCs are also discussed.

关键词： interconnecting layer narrow‐bandgap organic solar cells recombination layer tandem solar cells wide‐bandgap perovskite solar cells

3D-printed self-healing,biodegradable materials and their applications

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Frontiers of mechanical Engineering 2024年第3期19卷 1-22页

作者： Yu LI Guangmeng MA Fawei GUO Chunyi LUO Han WU Xin LUO MingtaoZHANG Chenyun WANG Qingxin JIN Yu LONG School of mechanical Engineering Guangxi UniversityNanning 530004China State key laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi UniversityNanning 530004China Institute of Laser intelligent manufacturing and Precision Processing School of Mechanical EngineeringGuangxi UniversityNanning 530004China College of mechanical and Electrical Engineering Central South UniversityChangsha 410083China State key laboratory of Precision manufacturing for Extreme Service Performance Central South UniversityChangsha 410083China

3D printing is a versatile technology capable of rapidly fabricating intricate geometric structures and enhancing the performance of flexible devices in comparison to conventional fabrication ***,3D-printed devices are susceptible to failure as a result of minuscule structural impairments,thereby impacting their overall *** utilization of self-healing,biodegradable materials in 3D printing holds immense potential for increasing the longevity and safety of devices,thereby expanding the application prospects for such ***,enhancing the self-repairing capability of devices and refining the 3D printing performance of self-healing materials are still considerable challenges that need to be addressed to achieve optimal *** paper reviews recent developments in the field of advancements in 3D printing using self-healing and biodegradable ***,it investigates self-healing and biodegradable materials that are compatible with 3D printing techniques,discussing their printability,material properties,and factors that influence print ***,it explores practical applications of selfhealing and biodegradable 3D printing technology in ***,it critically offers practical perspectives on this topic.

关键词： 3D printing self-healing biodegradable soft materials covalent bonds non-covalent bonds

Position-aware pushing and grasping synergy with deep reinforcement learning in clutter

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CAAI Transactions on Intelligence Technology 2024年第3期9卷 738-755页

作者： Min Zhao Guoyu Zuo Shuangyue Yu Daoxiong Gong Zihao Wang Ouattara Sie intelligent Robotics laboratory Faculty of Information TechnologyBeijing University of TechnologyBeijingChina Beijing key laboratory of Computational Intelligence and intelligent Systems BeijingChina laboratory of Biomechatronics and intelligent Robotics(BIRO) Department of Mechanical and Aerospace EngineeringNorth Carolina State UniversityRaleighNorth CarolinaUSA

The positional information of objects is crucial to enable robots to perform grasping and pushing manipulations in *** effectively perform grasping and pushing manipu-lations,robots need to perceive the position information of objects,including the co-ordinates and spatial relationship between objects(e.g.,proximity,adjacency).The authors propose an end-to-end position-aware deep Q-learning framework to achieve efficient collaborative pushing and grasping in ***,a pair of conjugate pushing and grasping attention modules are proposed to capture the position information of objects and generate high-quality affordance maps of operating positions with features of pushing and grasping *** addition,the authors propose an object isolation metric and clutter metric based on instance segmentation to measure the spatial re-lationships between objects in cluttered *** further enhance the perception capacity of position information of the objects,the authors associate the change in the object isolation metric and clutter metric in cluttered environment before and after performing the action with reward function.A series of experiments are carried out in simulation and real-world which indicate that the method improves sample efficiency,task completion rate,grasping success rate and action efficiency compared to state-of-the-art end-to-end *** that the authors’system can be robustly applied to real-world use and extended to novel *** material is available at https://***/NhG\_k5v3NnM}{https://***/NhG\_k5v3NnM.

关键词： deep learning deep neural networks intelligent robots

Safe Efficient Policy Optimization Algorithm for Unsignalized Intersection Navigation

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 2011-2026页

作者： Xiaolong Chen Biao Xu Manjiang Hu Yougang Bian Yang Li Xin Xu State key laboratory of Advanced Design and manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State key laboratory of Advanced Design and manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082 Wuxi intelligent Control Research Institute(WICRI)of Hunan University Wuxi 214115China College of Intelligence Science and Technology Institute of Unmanned SystemsNational University of Defense TechnologyChangsha 410073China

Unsignalized intersections pose a challenge for autonomous vehicles that must decide how to navigate them safely and *** paper proposes a reinforcement learning(RL)method for autonomous vehicles to navigate unsignalized intersections safely and *** method uses a semantic scene representation to handle variable numbers of vehicles and a universal reward function to facilitate stable learning.A collision risk function is designed to penalize unsafe actions and guide the agent to avoid them.A scalable policy optimization algorithm is introduced to improve data efficiency and safety for vehicle learning at *** algorithm employs experience replay to overcome the on-policy limitation of proximal policy optimization and incorporates the collision risk constraint into the policy optimization *** proposed safe RL algorithm can balance the trade-off between vehicle traffic safety and policy learning *** intersection scenarios with different traffic situations are used to test the algorithm and demonstrate its high success rates and low collision rates under different traffic *** algorithm shows the potential of RL for enhancing the safety and reliability of autonomous driving systems at unsignalized intersections.

关键词： Autonomous driving decision-making reinforcement learning(RL) unsignalized intersection

Mechanism and application of mechanical property improvements in engineering materials by pulsed magnetic treatment:A review

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Friction 2024年第10期12卷 2139-2166页

作者： Zhipeng CAI Chengkai QIAN Xu ZHANG Ning DAI Yao WU Wen JI State key laboratory of Tribology in Advanced equipment Tsinghua UniversityBeijing 100084China Department of mechanical Engineering Tsinghua UniversityBeijing 100084China Tianjin Research Institute for Advanced equipment Tsinghua UniversityTianjin 300304China

Pulsed magnetic treatment(PMT)has been adopted as an effective strengthening method for engineering materials and components in recent years,and the development of its application depends on the comprehensive understanding of the nature of *** deep mechanism was thought initially to be the magnetostrictive effect,while further investigation found that the magnetic field could lead to the change of the defect states in the crystal,which is called the magnetoplastic *** to the complexity of the engineering materials,manifestations of the magnetoplastic effect become more diverse,and they were reviewed in the form of microstructure homogenization and interfacial ***,the mechanism of the magnetoplastic effect was discussed,focusing on the changes in the spin states under the external magnetic *** modifications could also alter material performances,especially the residual stress,plasticity,and fatigue ***,PMT with specific parameters can be utilized to obtain an ideal combination of microstructure,residual stress,and mechanical properties for better service performance of different mechanical parts,and its applications on machining tools and bearings are perfect *** work reviews the effect of PMT on the microstructure and properties of different materials and the mechanism,and it also summarizes the fundamental applications of PMT on essential mechanical parts.

关键词： pulsed magnetic treatment wear resistance microstructure modifications mechanical properties magnetoplastic effect

Research on embedded locally resonant metamaterials used for vibration attenuation of thin-walled workpieces in mirror milling

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Acta Mechanica Sinica 2024年第8期40卷 1-16页

作者： Bei Ding Wei Wang Juliang Xiao Zhiqiang Wu Cheng Liu School of mechanical Engineering Tianjin UniversityTianjin300350China Tianjin key laboratory of Nonlinear Dynamics and Control Tianjin300350China key laboratory of Modern Mechanisms and equipment Design of the State Ministry of Education Tianjin UniversityTianjin300350China

The shell composed of large-scale parts is the essential component of mechanical structures in the aerospace,shipping,and railway *** workpieces are characterized by thin walls and weak rigidity,thus requiring an effective technology for high-performance ***,an embedded locally resonant metamaterial with double resonators is proposed and combined with the magnetic follow-up support technology to attenuate the vibration of thin-walled parts for the first *** band structures and parametric adjustment laws are systematically investigated and validated by analytical calculation and finite element method,which proves the proposed model is broadband,lightweight,and flexible in low *** characteristics,as well as the relatively simple structure,are unique advantages for thin-walled structure ***,mirror milling experiments have been performed to assess the slave module with the proposed *** the results,the root mean square amplitude of the thin-walled workpiece with the combined device decreases by nearly 9%,which means that the performance has been improved by the combined ***,this work provides an integrated and efficient solution for vibration suppression in thin-walled parts milling,which extends locally resonant metamaterials to practical engineering fields and helps to improve the status quo of mirror milling from the perspective of metamaterials.

关键词： Local resonance Band gap Thin-walled workpieces Vibration suppression

Interface strengthening for thermal sprayed WC-10Co4Cr coating subjected to pulsed magnetic treatment

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Rare Metals 2024年第2期43卷 780-795页

作者： Cheng-Kai Qian Qu Liu Heng Wang Ke-Jian Li Zhi-Peng Cai Department of mechanical Engineering Tsinghua UniversityBeijing100084China Tianjin Research Institute for Advanced equipment Tsinghua UniversityTianjin300304China State key laboratory of Tribology in Advanced equipment Tsinghua UniversityBeijing100084China

The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the *** this study,pulsed magnetic treatment(PMT)was applied to the thermal sprayed WC-10Co4Cr coating,and the fatigue lifetime of the coated bolt increased by 219.82%under an imitation of the operating mode *** tests further proved that both the adhesion and cohesion strength were improved after PMT,and they benefit from the interface strengthening *** formation of coherent WC/Co interfaces was characterized by in-situ transmission electron microscopy(TEM),and the molecular dynamic simulations indicate that the work of separation of these interfaces is much higher than the original disordered *** stress was relaxed and distributed more homogeneously after PMT,and it mainly contributes to the coating/substrate *** work provides a new post-treatment method focusing on the interfaces in the WC-based coating and gives insight into its mechanism so that it is hopeful to be applied to other kinds of coatings.

关键词： Cemented carbide coating Pulsed magnetic treatment Interface strengthening Fatigue properties Adhesion strength

Comprehensive modeling strategy for thermomechanical tribological behavior analysis of railway vehicle disc brake system

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Friction 2024年第1期12卷 74-94页

作者： Jiabao YIN Chun LU Jiliang MO School of mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China Technology and equipment of Rail Transit Operation and Maintenance key laboratory of Sichuan Province Chengdu 610031China

A comprehensive modeling strategy for studying the thermomechanical tribological behaviors is proposed in this *** wear degradation considering the influence of temperature(T)is predicted by Archard wear model with the help of the UMESHMOTION subroutine and arbitrary Lagrangian–Eulerian(ALE)remeshing *** the proposed method,the thermomechanical tribological behaviors of railway vehicle disc brake system composed of forged steel brake disc and Cu-based powder metallurgy(PM)friction block are studied *** effectiveness of the proposed methodology is validated by experimental test on a self-designed scaled brake test bench from the perspectives of interface temperature,wear degradation,friction noise and vibration,and contact status *** work can provide an effective way for the investigation of thermomechanical tribological behaviors in the engineering field.

关键词： tribological behaviors thermomechanical field wear prediction finite element simulation disc brake system railway vehicle