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SSRN 2022年

作者： Guo, Xiangru Mao, Ningdong Sun, Chaoyang Wang, Chunhui Cui, Yinan Xiong, Zhiping Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China School of Mechanical Engineering University of Science and Technology Beijing Beijing100083 China Applied Mechanics Lab School of Aerospace Engineering Tsinghua University Beijing100084 China National Key Laboratory of Science and Technology on Materials under Shock and Impact Beijing Institute of Technology Beijing100081 China

The tension-compression asymmetry and orientation effect of dislocation-twin boundary (TB) interactions in twinned TWIP steels were investigated using the discrete dislocation dynamics simulations and Schmid's law. The different types of dislocations dominate the TB migration in the twinned TWIP steel during tension and compression with the same loading orientation, and the asymmetric dislocation reactions at TB were attributed to the different leading partials produced after the dissociation of dislocation under different loading modes (tension or compression). Moreover, the complex dislocation-TB interactions, such as dislocations traversing TB, cross slip, dissociation, pile up and so on, were determined by considering the orientation effect of dislocation activation and the asymmetry of dislocation dissociation. The research advances the understanding of asymmetric behavior of twin and its influence on the macro hardening in plastic deformation of TWIP steels. © 2022, The Authors. All rights reserved.

关键词： Dissociation

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Small-Target Infrastructure Detection with Spatial Tracking and Multi-Level Feature Extraction of Railway Track Scenes

Small-Target Infrastructure Detection with Spatial Tracking ...

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Intelligent Communication, Sensing and Electromagnetics (ICSE), International Conference on

作者： Heng Du Huaiming Cang Yiwen Bai Xinyi Wang Beijing Elephant Technology Co. Ltd Beijing China School of Transportation Science and Engineering Beihang University Beijing China The State Key Lab of Intelligent Transportation System Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China

ISBN: (数字)9798350354935

ISBN: (纸本)9798350354942

In the field of railway transportation, with the continuous improvement of train running speed and the continuous increase of operating mileage, it becomes particularly important to ensure the safety and integrity of small-target infrastructure along the railway train. Although many small-target detection methods have been proposed, the research on small-target infrastructure detection along rail trains is very rare. To solve this problem, this paper proposes a small-target infrastructure detection network with spatial tracking and multi-level feature extraction based on Yolov8n. The experimental results show that ST-YOLO has a 3.6% mAP improvement on the OSDaR23 dataset compared to the baseline Yolov8n, and shows significant advantages over other state-of-the-art methods.

关键词： Rails Transportation Railway safety Switches Feature extraction Rail transportation Real-time systems Sensors Safety Monitoring

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A Fluid-Filled Tubular Dielectric Elastomer Variable Stiffness Structure Inspired by the Hydrostatic Skeleton Principle

A Fluid-Filled Tubular Dielectric Elastomer Variable Stiffne...

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IEEE International Conference on Robotics and Automation

作者： Tao Wang Yue Li Yuanjie Li Jinhua Zhang Jun Hong Michael Yu Wang Key Laboratory of Education Ministry for Modern Design & Rotor-Bearing System Xi'an Jiaotong University Xi'an Shaanxi China Department of Mechanical and Aerospace Engineering & Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Kowloon Hong Kong

This work presents a novel variable stiffness structure consisting of a fiber-constrained dielectric elastomer tube filled with insulating oil. The tensile stiffness of the structure can be adjusted by voltages and its initial value can be customized according to the initial pre-stretch of the material. The structure has a dimension of ～30 mm diameter ×50 mm length. A mathematical analysis is established to predict the initial tensile stiffness of the structure. The changes of the tensile stiffness of the structure under voltages are verified experimentally. The results show a decrease of the tensile stiffness of the device by 25% at 4 kV and the decrement is also related to the elongation of the structure. With different pre-stretches and dimensions of the dielectric elastomer, one can obtain devices with different variation ranges of tensile stiffness.

关键词： Electron tubes Strain Oils Muscles Hydraulic systems Force Soft robotics

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Recrystallization Mechanism and Texture Evolution of Pre-Twinned Zr702 During Annealing

SSRN

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SSRN 2022年

作者： Zeng, Qinghui Qiu, Risheng Bi, Fengxian Wang, Lixia Song, Shiyong Zeng, Qihang College of Intelligent Manufacturing Engineering Chongqing University of Arts and Sciences Chongqing402160 China College of Materials Science and Engineering Chongqing University Chongqing400044 China Chongqing Jianshe Vehicle System Co. LTD. Chongqing400054 China Science and Technology on Reactor Fuel and Materials Laboratory Sichuan Chengdu610041 China

With the aim of tailoring the texture of Zr alloys by twin recrystallization, the recrystallization mechanism and texture evolution of a tensile-twin-containing Zr702 were investigated in this work. Two types of rolling modes, simple rolling along former normal direction (ND) and cross rolling along former ND and rolling direction (RD) at cryogenic temperature, were conducted in a Zr702 sheet with a basal texture to activate high density tensile twins, and subsequent annealing was applied to induce twin recrystallization. During cryogenic rolling, [[EQUATION]] and [[EQUATION]] tensile twins were activated, which resulted in a texture change of c-axis keeping away from ND and tilting close to transverse direction (TD) along the ND-TD plane. And a [[EQUATION]] twin band- [[EQUATION]] twin band- [[EQUATION]] twin band lamellar structure formed inside the twinned grains at high thickness reductions due to the growth of [[EQUATION]] twins between parallel [[EQUATION]] twins. When rolling direction is RD for cross rolling, the grain orientations were more beneficial to the activation of prismatic slip than tensile twinning, leading to lower area fractions of tensile twins and sluggish texture change in cross-rolled samples. However, the final textures of the two types of rolled samples at 30% thickness reduction were similar. During annealing, twin recrystallization in tensile twins featured by bulging of twin boundaries and conventional discontinuous recrystallization at original grain boundaries occurred in twinned grains. Recrystallized grains formed in tensile twins had orientations closed to the un-recrystallized twins and contributed to the generation of a uniform texture of c-axis tilted close to TD along ND-TD plane in rolled and annealed samples, regardless of the different area fractions of twins and the various rolled textures at different thickness reductions. Few recrystallized grains nucleating in [[EQUATION]] twins gave rise to the disappearance of c-axis p

关键词： Textures

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One-dimensional non-linear consolidation of soft foundation with upper crust with depth-dependent additional stress

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Materials Research Innovations 2015年 19卷 S9198-S9204页

作者： Zhang, J.H. Wang, Y.L. Cen, G.M. Jiang, W.W. Zheng, J.L. Wu, H.X. National Engineering Laboratory of Highway Maintenance Technology Changsha University of Science and Technology Changsha410114 China Texas Transportation Institute Texas A and M University System College StationTX77843 United States Guangdong Highway Design Institute Co. Ltd. Guangzhou510030 China Jiangxi Ganyue Expressway Co. Ltd. Nanchang330029 China

A model for one-dimensional non-linear consolidation of a soft foundation with an upper crust with depth-dependent additional stress was presented in this paper. The semi-analytical solution of this model with the boundary condition of the pervious top was derived, which was proved by comparing with the classical solution of a one-layered foundation under an instantaneous loading. Then, the effects of the depth-dependent additional stress on the consolidation of the double-layered foundation were revealed. The results show that the depth-dependent additional stress inside foundation has a great influence on the consolidation rate at the former stage and final settlement of the double-layered foundation. If the change of the additional stress along the depth is neglected, an underestimated consolidation rate and overestimated final settlement will be obtained. © W. S. Maney & Son Ltd 2015.

关键词： Foundations

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Emergent grain boundary phases in stressed polycrystalline thin films

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Physical Review Materials 2023年第8期7卷 083602-083602页

作者： Mengyuan Wang Ruilin Yan Xiao Han Hailong Wang Moneesh Upmanyu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei Anhui 230027 China Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP) Department of Mechanical and Industrial Engineering Northeastern University Boston Massachusetts 02115 USA

The grain boundary (GB) microstructure influences and is influenced by the development of residual stresses during synthesis of polycrystalline thin films. Recent studies have shown that the frustration between the preferred growth direction and rotations of abutting crystals to local cusps in GB energies leads to internal stresses localized within nanoscopic surface layers around the valleys and ridges that form at emergent boundaries (eGBs). Using a combination of continuum frameworks, numerical analyses, and all-atom simulations of bicrystal 〈111〉 copper films, we show that eGBs tune their surface morphology and rotation extent in response to external strains. Compression favors rotation to and growth of low-energy GB phases (complexions) at eGB valleys while tension favors the transitions at eGB ridges, a reflection of the stress-induced mass efflux/influx that changes the energetic balance between interfacial and deformation energies. Molecular dynamics simulations of strained and growing bicrystal films reveal that the eGB phase transition is coupled to island formation at the surface triple junctions, providing a direct link between eGB phases and surface step flow. The interplay between eGB structure, morphology, and mechanics emerges as a crucial ingredient for predictive understanding of stress and morphological evolution during film growth, with broad implications for multifunctional response of polycrystalline surfaces in a diverse range of surface phenomena such as surface-mediated deformation, interfacial embrittlement, thermal grooving, stress corrosion, surface catalysis, and topological conduction.

关键词： Grain boundaries Interface & surface thermodynamics Surface & interfacial phenomena Surface reconstruction Solid-solid interfaces Thin films Molecular dynamics

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Mixture of Experts for Network Optimization: A Large Language Model-enabled Approach

arXiv

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arXiv 2024年

作者： Du, Hongyang Liu, Guangyuan Lin, Yijing Niyato, Dusit Kang, Jiawen Xiong, Zehui Kim, Dong In The School of Computer Science and Engineering Nanyang Technological University Singapore639798 Singapore The State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing100876 China The School of Automation Guangdong University of Technology Key Laboratory of Intelligent Information Processing and System Integration of IoT Ministry of Education Guangzhou510006 China Guangdong-HongKong-Macao Joint Laboratory for Smart Discrete Manufacturing Guangzhou510006 China The Pillar of Information Systems Technology and Design Singapore University of Technology and Design Singapore487372 Singapore The Department of Electrical and Computer Engineering Sungkyunkwan University Suwon16419 Korea Republic of

Optimizing various wireless user tasks poses a significant challenge for networking systems because of the expanding range of user requirements. Despite advancements in Deep Reinforcement Learning (DRL), the need for customized optimization tasks for individual users complicates developing and applying numerous DRL models, leading to substantial computation resource and energy consumption and can lead to inconsistent outcomes. To address this issue, we propose a novel approach utilizing a Mixture of Experts (MoE) framework, augmented with Large Language Models (LLMs), to analyze user objectives and constraints effectively, select specialized DRL experts, and weigh each decision from the participating experts. Specifically, we develop a gate network to oversee the expert models, allowing a collective of experts to tackle a wide array of new tasks. Furthermore, we innovatively substitute the traditional gate network with an LLM, leveraging its advanced reasoning capabilities to manage expert model selection for joint decisions. Our proposed method reduces the need to train new DRL models for each unique optimization problem, decreasing energy consumption and AI model implementation costs. The LLM-enabled MoE approach is validated through a general maze navigation task and a specific network service provider utility maximization task, demonstrating its effectiveness and practical applicability in optimizing complex networking systems. © 2024, CC BY.

关键词： Reinforcement learning

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Effects of Geometric Parameters on Performance of Rectangular Submerged Inlet for Aircraft

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Transactions of Nanjing University of Aeronautics and Astronautics 2021年第6期38卷 984-992页

作者： LIU Chao PEI Houju CHEN Changdong XU Wenbing YANG Kaijie Environment Control and Oxygen System Department Shanghai Aircraft Design and Research InstituteShanghai 201210P.R.China AVIC Nanjing Servo Control System Corporation Nanjing 210016P.R.China College of Energy&Power Engineering Jiangsu University of Science and TechnologyZhenjiang 212003P.R.China Key Laboratory of Aircraft Environment Control and Life Support MIITNanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

To improve the comfortability and safety of aircraft,the demand of rectangular submerged inlets(RSIs)with low resistance is proposed to increase the inlet flow rate of ram air. A theoretical model is built to numerically analyze the effects of geometric parameters on the inlet mass flow rate of RSIs. The geometric parameters in question here encompass the aspect ratio of 2—4,the ramp angle of 6°—7°,the characteristic parameter of the throat of 0.20 —0.30,the ramp length of 939—1 337 mm,and the cone angle of 0° —3°. Simulation results demonstrate that the mass flow rate(MFR)is positively correlated with the aspect ratio,ramp angle,ramp length,and cone angle,and negatively correlated with characteristic parameter of the throat. Within the range of the geometric parameters considered,the RSI with the aspect ratio of 3,the ramp angle of 6°,the characteristic parameter of the throat of 0.20,the ramp length of 1 337 mm,and the cone angle of 3° obtains the largest MFR value of about 2.251 kg/s.

关键词： ram air system rectangular submerged inlet geometric parameter mass flow rate(MFR)

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TICNet: Three-Branch Real-Time Semantic Segmentation Network with Intensive Compensation of Railway Track Scenes

TICNet: Three-Branch Real-Time Semantic Segmentation Network...

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Machine Learning and Computer Application (ICMLCA), International Conference on

作者： Yiwen Bai Lu Yang Lei Zhang Yajing Song School of Transportation Science and Engineering Beihang University Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China Traffic Control Technology Co. Ltd Beijing China

ISBN: (数字)9798331530334

ISBN: (纸本)9798331530341

With the rapid development of railway traffic system, real-time semantic segmentation plays a crucial role in railway track scene monitoring. However, most of the existing methods use lightweight convolution to reduce the computational complexity, which results in reduced accuracy. To solve this problem, this paper proposes a real-time semantic segmentation network called TICNet, which is specifically used for accurate segmentation of railway track scenes. TICNet uses a novel three-branch structure designed for efficient feature extraction and accurate segmentation. Results on the RailSem19 dataset show that TICNet has a segmentation accuracy of 62.36% mIoU with an inference speed of 81.2 FPS, which is significantly better than many existing methods.

关键词： Accuracy Convolution Semantic segmentation Semantics Focusing Machine learning Feature extraction Real-time systems Computational complexity Monitoring

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Hierarchical Micro/Nano Structures with Anti-Reflection and Superhydrophobicity on the Silicon Surface Fabricated by Femtosecond Laser

SSRN

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SSRN 2024年

作者： Duan, Junyu Long, Gui Xu, Xu Liu, Weiming Li, Chuankun Zhang, Jianguo Xu, Jianfeng Xiao, Junfeng State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Hubei Jiuzhiyang Infrared System Co. Ltd. Wuhan430223 China Huazhong Institute of Electro-Optics Wuhan National Laboratory for Optoelectronics Wuhan430223 China China Ship Development and Design Center Wuhan43006 China Hunan University China

In this paper, hierarchical micro/nano structures composed of periodic microstructures, LIPSS, and nanoparticles were fabricated by femtosecond laser processing. A layer of hydrophobic species was formed on the micro/nano structures through perfluorosilane modification. The reflectivity and hydrophobicity’s influence mechanisms of structural height, duty cycle, and size are experimentally elucidated. The average reflectivity of the silicon surface in the visible light band is reduced to 3.0% under the optimal parameters, and the surface exhibits a large contact angle of 172.3 ± 0.8 ° and a low sliding angle of 4.2 ± 1.4 °. Finally, the durability of anti-reflection and superhydrophobicity is also confirmed. This study deepens the understanding of the principles of anti-reflection and superhydrophobicity and expands the design and preparation methods for self-cleaning and anti-reflective surfaces. © 2024, The Authors. All rights reserved.

关键词： Femtosecond lasers

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