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Oxidation-induced superelasticity in metallic glass nanotubes

Nature Materials 2024年第1期23卷 52-57页

作者： Li, Fucheng Zhang, Zhibo Liu, Huanrong Zhu, Wenqing Wang, Tianyu Park, Minhyuk Zhang, Jingyang Bönninghoff, Niklas Feng, Xiaobin Zhang, Hongti Luan, Junhua Wang, Jianguo Liu, Xiaodi Chang, Tinghao Chu, Jinn P. Lu, Yang Liu, Yanhui Guan, Pengfei Yang, Yong Department of Mechanical Engineering College of Engineering City University of Hong Kong Kowloon Tong Hong Kong Institute of Physics Chinese Academy of Sciences Beijing China Songshan Lake Materials Laboratory Dongguan China Beijing Computational Science Research Center Beijing China Department of Material Science and Engineering National Taiwan University of Science and Technology Taipei Taiwan Department of Materials Science and Engineering College of Engineering City University of Hong Kong Kowloon Tong Hong Kong College of Mechatronics and Control Engineering Shenzhen University Shenzhen China Department of Mechanical Engineering The University of Hong Kong Pok Fu Lam Hong Kong Department of System Engineering College of Engineering City University of Hong Kong Kowloon Tong Hong Kong

Although metallic nanostructures have been attracting tremendous research interest in nanoscience and nanotechnologies, it is known that environmental attacks, such as surface oxidation, can easily initiate cracking on the surface of metals, thus deteriorating their overall functional/structural properties 1–3. In sharp contrast, here we report that severely oxidized metallic glass nanotubes can attain an ultrahigh recoverable elastic strain of up to ~14% at room temperature, which outperform bulk metallic glasses, metallic glass nanowires and many other superelastic metals hitherto reported. Through in situ experiments and atomistic simulations, we reveal that the physical mechanisms underpinning the observed superelasticity can be attributed to the formation of a percolating oxide network in metallic glass nanotubes, which not only restricts atomic-scale plastic events during loading but also leads to the recovery of elastic rigidity on unloading. Our discovery implies that oxidation in low-dimensional metallic glasses can result in unique properties for applications in nanodevices. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

关键词： Metallic glass

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Train Safety control Based on Deep Deterministic Policy Gradient with control Barrier Function 21

Train Safety Control Based on Deep Deterministic Policy Grad...

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21st International Conference on Networking, Sensing and control, ICNSC 2024

作者： Wang, Guoteng Lv, Jidong Liu, Hongjie Chai, Ming Tang, Tao Zhang, Wentao School of Automation and Intelligence Beijing Jiaotong University Beijing China Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing China Beijing Jiaotong University State Key Laboratory of Advanced Rail Autonomous Operation Beijing China Beijing Zhengshi Environmental Engneering Company Beijing China

ISBN: (纸本)9798350365221

Train Relative Distance Braking Mode (RDBM) has great potential to increase line capacity by enabling shorter following distances based on train-to-train communication in-formation. However, it is difficult for traditional train control methods to ensure avoidance of potential collision risks in RDBM while dealing with the nonlinearity and uncertainty of train dynamics. In this paper, a novel train safety control method combining Deep Deterministic Policy Gradient (DDPG) and control Barrier Function(Cbf)is proposed. Firstly, the safety constraint set for adjacent trains, considering their braking capabilities, is analyzed, and the uncertainty of train dynamics is modeled using a Gaussian process. Secondly, DDPG is used to explore the optimal control strategy under the action of uncertain train dynamics, and CBF provides compensation control input to ensure safety during the learning process. Then, a DDPG-CBF algorithm is presented to achieve efficient safety controller design and implementation. Finally, sufficient numerical simulations demonstrate that, compared with DDPG algorithm alone, the DDPG-CBF algorithm can not only ensure the safe and stable operation of trains, but also learn train control strategies expe-ditiously and accurately under different operating environments, with an average efficiency increase of 38.94 %. © 2024 IEEE.

关键词： Braking

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Distributed optimization for discrete-time multiagent systems with nonconvex control input constraints and switching topologies

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Chinese Physics B 2021年第12期30卷 283-290页

作者： Xiao-Yu Shen Shuai Su Hai-Liang Hou School of Automation Central South UniversityChangsha 410083China National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong UniversityBeijing 100044China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing 100044China

This paper addresses the distributed optimization problem of discrete-time multiagent systems with nonconvex control input constraints and switching *** introduce a novel distributed optimization algorithm with a switching mechanism to guarantee that all agents eventually converge to an optimal solution point,while their control inputs are constrained in their own nonconvex *** is worth noting that the mechanism is performed to tackle the coexistence of the nonconvex constraint operator and the optimization gradient *** on the dynamic transformation technique,the original nonlinear dynamic system is transformed into an equivalent one with a nonlinear error *** utilizing the nonnegative matrix theory,it is shown that the optimization problem can be solved when the union of switching communication graphs is jointly strongly ***,a numerical simulation example is used to demonstrate the acquired theoretical results.

关键词： multiagent systems nonconvex input constraints switching topologies distributed optimization

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Adaptive Artificial Potential Field Ship Motion Planning Based on DDPG

Adaptive Artificial Potential Field Ship Motion Planning Bas...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Chen, Huimin Liu, Chenguang He, Zhibo Zhang, Guoqing Han, Bing State Key Laboratory of Maritime Technology and Safety Wuhan University of Technology Wuhan430063 China Intelligent Transportation Systems Research Center Wuhan University of Technology Wuhan430063 China School of Transportation and Logistics Engineering Wuhan University of Technology Wuhan430063 China Navigation College Dalian Maritime University Dalian116026 China State Key Laboratory of Maritime Technology and Safety Dalian116026 China National Engineering Research Center of Ship & Shipping Control System Shanghai200134 China

ISBN: (纸本)9789819639601

The paper presents a ship motion planning method that adjusts the attractive and repulsive gain parameters of the artificial potential field (APF) algorithm using the deep deterministic policy gradient (DDPG) algorithm, to address the challenges of parameter design and limited adaptability of traditional APF algorithms. This approach leverages the speed advantage of the APF planning algorithm and the exploration capability of the DDPG reinforcement learning algorithm. By optimizing the parameters of APF with DDPG, the local optima problem can be alleviated in complex obstacle environments. Simulation results demonstrate that the proposed motion planning algorithm can generate reasonable trajectories and exhibit strong adaptability in complex obstacle scenarios. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Motion planning

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Design and Analysis of Double One Out of Two with a Hot Standby Safety Redundant Structure

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Chinese Journal of Electronics 2020年第3期29卷 586-594页

作者： WEN Jiakun CAO Yuan MA Lianchuan DU Siqi School of Electronic and Information Engineering Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University

In the rail transit system, the running foundation of the computer control system is required to be highly reliable, available and safe. A redundant system structure of double one out of two with a hot standby applied to the safety computer platform of the train control system is proposed in this paper. Considering the common cause failure, fault diagnosis rate, repair rate and switching success rate, the Markovian approach is adopted for modeling four safety redundant structures,including two out of three, double one out of two, one out of two with a hot standby and double one out of two with a hot standby. The calculation of the failure rate and PFH values is carried out with MATLAB to evaluate the reliability, safety and influencing factors of each structure. The final conclusion is that double one out of two with a hot standby structure can be best in the aspect of both reliability and safety with appropriate DC and β parameters.

关键词： Markov model Safety redundant structure Reliability Safety Double one out of two with a hot standby

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research on High Precision Tracking Method of Guided Transport Vehicle Based on Autonomous Combination Positioning

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Chinese Journal of Electronics 2020年第4期29卷 779-785页

作者： CAO Yuan ZHANG Shuangshuang YANG Guizhi WEN Tao National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University School of Electronic and Information Engineering Beijing Jiaotong University

Guided transport vehicle(GTV) uses satellite positioning technology, lidar, and highperformance video sensors to achieve real-time positioning and tracing, these devices cost a *** addition, GTV shifts left and right during operation due to there is no fixed orbits *** is very important to detect the lateral offset in real time to ensure the accurate tracing of the vehicle along the dotted *** at the above issues, this paper proposes a low-cost high precision tracing method for GTV based on integrated positioning,high resolution estimation of the vehicles positioning information is implemented by Cubature Kalman filters(CKF) with a loosely coupled mode based on GPS/SINS in this method; Considering that GTV has a fixed driving route, a two-stage map matching algorithm based on Hidden Markov model(HMM) is proposed, which further improves the accuracy; The lateral offset distance is detected based on the positioning information, which provides theoretical support for the subsequent control of the precise operation of the *** algorithm’s feasibility has been verified by real vehicle experiments,the results show that the proposed algorithm achieves a centimeter-level positioning accuracy, and when the lateral offset distance is not less than 65 cm, the detection accuracy of the lateral offset distance is more than 92%.

关键词： Positioning and tracing CKF Map matching Lateral offset detection

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A Hybrid Meta-Heuristic Algorithm of Load Balancing for Cloud-based Railway Interlocking system

A Hybrid Meta-Heuristic Algorithm of Load Balancing for Clou...

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International Conference on Intelligent Transportation

作者： Huan Zheng Qihe Zhang Zhiguo Liang Jiacheng Kong Dongdong Wei Yong Yang Ming Chai Haifeng Wang National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University Beijing China Center of National Railway Intelligent Transportation System Engineering and Technology China Academy of Railway Sciences Corporation Limited Beijing China

Cloud-based railway interlocking system is a novel solution for interlocking systems with the development of cloud computing. The load balancing problem caused by imbalanced resources in computing platforms is an essential problem in realizing cloud-based railway interlocking system. Conventional load balancing algorithms focus on makespan, throughput and costs. However, a load balancing algorithm for a cloud-based railway interlocking system should focus on optimizing resource utilization and execution time. To this end, we propose a hybrid meta-heurisite algorithm called Improved Genetic Annealing Algorithm (IGAA). The proposed algorithm can guarantee global optimization ability by using the Metropolis criterion and can converge rapidly due to the parallel searching characteristic of the Genetic Algorithm. Finally, the feasibility and effectiveness of the proposed algorithm are verified by experiments.

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A Distributed Convergent Clock Synchronization Algorithm Based on Exponential Smoothing for Cloud-Based Railway Interlocking system

A Distributed Convergent Clock Synchronization Algorithm Bas...

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International Conference on Intelligent Transportation

作者： Qihe Zhang Shunli Li Zhiguo Liang Jiacheng Kong Dongdong Wei Yong Yang Ming Chai Haifeng Wang National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University Beijing China Center of National Railway Intelligent Transportation System Engineering and Technology China Academy of Railway Sciences Corporation Limited Beijing China

Clock synchronization is one of the essential problems for the cloud-based railway interlocking system, which is related to task processing and information synchronization. To improve the convergence rate and performance of a classical distributed clock synchronization algorithm, this paper proposes an exponential smoothing predictor-based distributed clock synchronization algorithm for the cloud-based railway interlocking system. Firstly, a classical distributed clock synchronization algorithm is conducted to get a convergent clock for distributed computing nodes. Then, to improve the convergence rate and performance, we introduce an exponential smoothing predictor to the classical method. Moreover, the convergence condition and convergence rate of our proposed method were analyzed theoretically. Finally, the simulation results show that the proposed algorithm has a better convergence performance than a classical method and can meet the requirements of a cloud-based railway interlocking system.

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Dynamic Passenger Demands Oriented Optimization of Virtually Coupled Train Formation Scheduling

Dynamic Passenger Demands Oriented Optimization of Virtually...

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2022 Chinese Automation Congress, CAC 2022

作者： Zhang, Haobei Tang, Tao Liu, Hongjie Lang, Yinghui Beijing Jiaotong University School of Electronics and Information Engineering Beijing China Beijing Jiaotong University State Key Laboratory of Rail Traffic Control and Safety Beijing China Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing China

ISBN: (纸本)9781665465335

The research on virtual coupling technology in metros is a hot topic recently. Intelligent automatic train units can flexibly form virtually coupled train formations (VCTFs) when needed, so that the train capacity would be able to adapt to passenger demands, which are changing dynamically with time and space. However, matching the capacity of trains with passenger demands is a difficult decision-making optimization problem. In this work, we propose a collaborative control problem to decide when and how to create a VCTF to meet the dynamic passenger demands in a metro system. A mathematical model is formulated which can simultaneously optimize the number of related train units in a VCTF, the train dwelling time at a station and the running time in a section. Performance indicators such as train load factor and number of stranded passengers are adopted to measure the satisfaction of the operators and passengers. Then, a multi-objective genetic algorithm is adopted to obtain the Pareto optimum solutions. Finally, simulation experiments are conducted, and the relationship between line efficiency and passenger demand in different discrete time periods is analyzed to verify the correctness and feasibility of the model. Compared with the traditional timetabling method, adopting the virtual coupling technology can better adapt the train capacity to meet the time changing passenger demands, which is welcomed by both metro operators and passengers in reality. © 2022 IEEE.

关键词： Genetic algorithms

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An Improved Safe Braking Model of Virtually Coupled Trains for Closer Tracking 21

An Improved Safe Braking Model of Virtually Coupled Trains f...

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21st International Conference on Networking, Sensing and control, ICNSC 2024

作者： Yan, Wenxiao Wang, Jiayu Fan, Liqun Liu, Qiusheng Jia, Qingdong Wang, Yihan Liu, Hongjie Shenzhen Metro Group Co. Ltd. Shenzhen518026 China Shenzhen Municipal Design and Research Institute Co. Ltd. Shenzhen518029 China Traffic control Technology Co. Ltd. Beijing100070 China School of Automation and Intelligence Beijing Jiaotong University Beijing100044 China Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing100044 China

ISBN: (纸本)9798350365221

With the rapid growth of transportation passenger flow in recent years, the research direction of Virtual Coupling (V C) in railways has become hot. V C increases capacity by tracking shorter distances. The traditional train emergency braking (EB) model can no longer meet the high operating efficiency requirements of VC. VC urgently needs a more efficient safety EB model. Therefore, to improve efficiency, a measurement of the EB model's rationality is defined considering safety and efficiency. Based on the defined model measurement, an EB model optimization method and a new EB model are proposed. The new model is closer to the actual braking process of the train and ensures safety from the distance level. That is, the braking trajectory of the train calculated by the new model is closer to the actual braking trajectory of the train, and the two braking trajectories satisfy the specific safety constraints. Finally, the safety and efficiency of the new model were verified through simulation experiments. The new model can avoid train collisions during the entire EB process. Experimental results show that compared with the traditional old EB model of VC based on space-time interval [1], the new model's minimum safe distance (MSD) between two VC train units can be reduced by 39%. © 2024 IEEE.

关键词： Railroad accidents

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