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Dynamic analysis of asymmetric piecewise linear systems

Applied Mathematics and Mechanics(English Edition) 2025年第4期46卷 633-646页

作者： Ruiliang ZHANG Yongjun SHEN Xiaotong YANG School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang050043China School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuang050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang050043China

Piecewise linear systems are prevalent in engineering practice,and can be categorized into symmetric and asymmetric piecewise linear *** that symmetry is a special case of asymmetry,it is essential to investigate the broader model,namely the asymmetric piecewise linear *** traditional averaging method is frequently used for studying nonlinear systems,particularly symmetric piecewise linear systems,with the harmonic response of the oscillator serving as a key prerequisite for calculating steady-state ***,asymmetric systems inherently exhibit nonharmonic,asymmetric responses,rendering the traditional averaging method *** overcome this limitation,this paper introduces an improved averaging method tailored for an oscillator characterized by asymmetric gaps and *** the traditional method,which assumes a purely harmonic response,the improved averaging method redefines the system response as a superposition of a direct current(DC)term and a first harmonic ***,the DC term can be regarded as the offset induced by model ***,the DC term is treated as a slow variable function of time,with its time derivative assumed to be zero when calculating the steady-state solution,akin to the amplitude and phase in the traditional averaging *** validation demonstrates that the responses computed in both time and frequency domains with the improved averaging method exhibit greater accuracy compared with those derived from the traditional *** these improved results,the study also examines the parameter effect,stability,and bifurcation phenomena within the amplitude-frequency responses.

关键词： nonlinear vibration piecewise linear system asymmetry averaging method offset

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Research on the application of the parameter freezing precise exponential integrator in vehicle-road coupling vibration

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Applied Mathematics and Mechanics(English Edition) 2025年第2期46卷 373-390页

作者： Yu ZHANG Chao ZHANG Shaohua LI Shaopu YANG State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China Department of Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Research Center of the Basic Discipline Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuang 050043China

The vehicle-road coupling dynamics problem is a prominent issue in transportation,drawing significant attention in recent *** dynamic equations are characterized by high-dimensionality,coupling,and time-varying dynamics,making the exact solutions challenging to *** a result,numerical integration methods are typically ***,conventional methods often suffer from low computational *** address this,this paper explores the application of the parameter freezing precise exponential integrator to vehicle-road coupling *** model accounts for road roughness irregularities,incorporating all terms unrelated to the linear part into the algorithm's inhomogeneous *** general construction process of the algorithm is *** validity of numerical results is verified through approximate analytical solutions(AASs),and the advantages of this method over traditional numerical integration methods are *** parameter freezing precise exponential integrator schemes are constructed based on the Runge-Kutta framework,with the fourth-order four-stage scheme identified as the optimal *** study indicates that this method can quickly and accurately capture the dynamic system's vibration response,offering a new,efficient approach for numerical studies of high-dimensional vehicle-road coupling systems.

关键词： vehicle-road coupled dynamics dynamic response parameter freezing precise exponential integrator Newmark-βintegration

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IRT-diffusion: combined denoising diffusion probabilistic models with thermal signal processing methods for automated defect detection in composites using infrared thermography

IRT-diffusion: combined denoising diffusion probabilistic mo...

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2024 International Conference on Optical and Photonic engineering, icOPEN 2024

作者： Wei, Yanjie Zhang, Yuhang Xiao, Yao Gu, Xiaohui State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang050043 China

ISBN: (数字)9781510688117

ISBN: (纸本)9781510688100

Infrared thermography (IRT) is a reliable method for detecting defects in composites with advantages of full field, non-contact, easy operation and good visualization. Nevertheless, interpretation by experts is required to distinguish between defective and sound regions in the practical evaluation of defects, which limits the industrial applications of infrared thermography. In this study, a denoising diffusion probabilistic model (DDPM) framework named IRT-Diffusion is proposed to automatically segment defective regions in thermal images. IRT-Diffusion can reconstruct a defect segmentation image from a noisy image with standard Gaussian distribution by iteratively performing multiple denoising operations. Detection results from various traditional thermal signal processing methods are employed as input for the conditional noise predictor of IRT-Diffusion to generate more accurate defect segmentation results. The core innovation of this study is that the state-of-the-art generative model is first introduced and designed for defect identification in composites using infrared thermography. To assess the performance of IRT-Diffusion, experiments were conducted on several composites panels and compared with conditional variational autoencoder (CVAE) and conditional generative adversarial network (CGAN). The results demonstrate that the proposed method achieves superior quantitative metrics and effectively extracts defective regions. © 2025 SPIE.

关键词： Image segmentation

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Determination of defect size for composites using derivative images in pulse thermography

Determination of defect size for composites using derivative...

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2024 International Conference on Optical and Photonic engineering, icOPEN 2024

作者： Wei, Yanjie Lu, Jiashuo Xiao, Yao Gu, Xiaohui State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang050043 China

ISBN: (数字)9781510688117

ISBN: (纸本)9781510688100

Pulse thermography is a reliable method for detecting defects in composites with advantages of full field, non-contact and easy operation. However, the size determination of subsurface defects with low width-to-depth ratios using pulsed thermography is a challenging task due to the blurred defect edges in infrared thermal images caused by lateral heat diffusion. The present study explores the ability of time derivative images of infrared thermography to predict defect size. 2D thermal conduction of pulse thermography based on the virtual heat source method was analyzed to compare the temperature profile and derivative profile of defects along the diameter direction, and a size prediction method based on the derivative profile is proposed. The feasibility of the proposed method was evaluated by measuring the dimensions of the flat-bottomed holes in the composite panels. The experimental results demonstrated that the size inversion method based on derivative images brings an improvement in measuring accuracy for defects. Additionally, the influences of cooling time, defect depth, defect size and thermal properties of the material on the measurement of defect dimension are also discussed. © 2025 SPIE.

关键词： Thermography (imaging)

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Study on the Mechanism of Polygonal Wear in Wheels Based on Wheel-Rail Contact Normal Force

Study on the Mechanism of Polygonal Wear in Wheels Based on ...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Zhou, Zichao Liu, Yongqiang Guo, Tao Wang, Tiecheng Huo, Wenbiao State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China CRRC TANGSHAN CO. LTD. Tangshan063000 China

ISBN: (纸本)9789819639687

To address the issue of high-order polygonal wear in high-speed trains operating at 300 km/h, this paper investigates the influence of bogie modal vibration on the initiation and progression of such wear phenomena. The model simulation incorporates the modal vibrations of both the frame and the wheelset, while also accounting for non-Hertzian contact and track irregularity within a long-term iterative wear model, thereby enhancing its alignment with real-world operational conditions. The main conclusions are: The vibration frequency of the wheel-rail contact normal force, influenced by running speed and sleeper spacing, plays a key role in the initiation of polygonal wear. The fourth-order bending resonance of the wheelset is the primary cause of the 20th-order polygon wear and its rapid development. Suspension parameters have a significant impact on the wear index, and proper adjustment of these parameters can effectively slow the progression of polygonal wear. The findings of this paper hold theoretical value and practical significance in understanding the formation and progression mechanisms of polygonal wear, as well as in developing effective measures for its mitigation. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Railroads

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Multi-Objective Parallel Human-machine Steering Coordination Control Strategy of Intelligent Vehicles Path Tracking Based on Deep Reinforcement Learning

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Chinese Journal of mechanical engineering 2025年第1期38卷 1-19页

作者： Wang, Hongbo Feng, Lizhao Li, Shaohua Chen, Wuwei Zhou, Juntao School of Automotive and Transportation Engineering Hefei University of Technology Hefei China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

In the parallel steering coordination control strategy for path tracking, it is difficult to match the current driver steering model using the fixed parameters with the actual driver, and the designed steering coordination control strategy under a single objective and simple conditions is difficult to adapt to the multi-dimensional state variables’ input. In this paper, we propose a deep reinforcement learning algorithm-based multi-objective parallel human-machine steering coordination strategy for path tracking considering driver misoperation and external disturbance. Firstly, the driver steering mathematical model is constructed based on the driver preview characteristics and steering delay response, and the driver characteristic parameters are fitted after collecting the actual driver driving data. Secondly, considering that the vehicle is susceptible to the influence of external disturbances during the driving process, the Tube MPC (Tube Model Predictive Control) based path tracking steering controller is designed based on the vehicle system dynamics error model. After verifying that the driver steering model meets the driver steering operation characteristics, DQN (Deep Q-network), DDPG (Deep Deterministic Policy Gradient) and TD3 (Twin Delayed Deep Deterministic Policy Gradient) deep reinforcement learning algorithms are utilized to design a multi-objective parallel steering coordination strategy which satisfies the multi-dimensional state variables’ input of the vehicle. Finally, the tracking accuracy, lateral safety, human-machine conflict and driver steering load evaluation index are designed in different driver operation states and different road environments, and the performance of the parallel steering coordination control strategies with different deep reinforcement learning algorithms and fuzzy algorithms are compared by simulations and hardware in the loop experiments. The results show that the parallel steering collaborative strategy based on a deep

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Research on methods for data acquisition and visualization of subway network passenger flow big data 4

Research on methods for data acquisition and visualization o...

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2024 4th International Conference on Intelligent traffic systems and Smart City, ITSSC 2024

作者： Song, Xue Lv, Xikui Liu, Xinhua School of Civil Engnieering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Shijiazhuang050043 China Qingdao Metro Group Co. Ltd. Qingdao266000 China

ISBN: (纸本)9781510686304

To explore the acquisition, analysis, and visualization applications of subway passenger flow data in the context of big data, and to uncover the patterns behind passenger travel data, this paper utilizes subway IC card swiping data as the data source to achieve the acquisition of subway network data, extraction of inbound and outbound passenger flows, modeling of subway rail network, and visualization of passenger flow big data. Through the analysis of subway passenger flow data, this paper reveals the urban transportation travel demand and residents' travel characteristics, analyzes the impact mechanism of land use types and land development intensity on passenger flows, and holds significant importance in improving the quality of urban public transportation services and optimizing subway operation strategies. © 2025 SPIE.

关键词： Urban transportation

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Effects of Day-Night Temperature Fluctuations on Top-Down Cracking Development in Road structures

SSRN

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SSRN 2025年

作者： Li, Ting Qiao, Haoyu Xu, Peng Yang, Guangqing Faculty of Engineering University of Porto Porto4200 465 Portugal State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

Top-down cracking has become a significant issue in road structures. Temperature is a key factor in the occurrence of top-down cracking. However, there is a lack of research on how day-night temperature fluctuations impact the propagation of top-down cracking in road structures, leading to an incomplete understanding of its development. This study employs the extended finite element method, which is an innovative approach for crack analysis, to create a simulation model of road structure with top-down cracking, integrating thermal boundary theory. The model's accuracy is confirmed through comparison with previous studies. The research then examines the temperature distribution and various influential factors, including ambient temperature, material properties, and cracking characteristics, using the stress intensity factor as the main indicator. Grey relational analysis is used to further investigate the effects of different parameters on the stress intensity factor. Additionally, the study explores the propagation path of top-down cracking in road structure under cyclic temperature loading. The findings provide new insights into the thermally-induced mechanisms behind top-down cracking development in road structures. © 2025, The Authors. All rights reserved.

关键词： Road construction

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Research on the power generation efficiency of bladeless wind turbines under different degrees of freedom based on bidirectional fluid-solid coupling

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Zhendong yu Chongji/Journal of Vibration and Shock 2025年第12期44卷 150-161页

作者： Wei, Hongwei Liu, Kan Wei, Keqin Jia, Yaya Liu, Qingkuan School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China

A simplified model of the bladeless wind turbine was established and the formula for its power generation efficiency was derived. Numerical simulations were conducted using computational fluid dynamics software Fluent and user-defined functions (UDF), studying the vortex-induced vibration characteristics and power generation efficiency of single and dual degree-of-freedom bladeless wind turbines under different reduced wind speeds. The study shows that the difference in the degrees of freedom of the wind turbine significantly affects its vibration response, aerodynamic characteristics and power generation efficiency. The vibration amplitude initially increases and then decreases as the reduced wind speed increases, remaining stable in certain wind speed ranges. The vibration trajectory of the dual degree-of-freedom wind turbine at reduced wind speeds primarily forms a figure-eight pattern, exhibiting multi-frequency vibrations when the wind speed approaches the natural frequency, with the trajectory becoming chaotic. The power generation efficiency follows a trend of increasing first and then decreasing with the changing reduced wind speed, with the efficiency of the dual degree-of-freedom wind turbine being higher than that of the single degree-of-freedom wind turbine. At a reduced wind speed of Ur = 2. 4, the maximum power generation efficiency of the single degree-of-freedom wind turbine is 25. 19%;at Ur = 3.4, the maximum power generation efficiency of the dual degree-of-freedom wind turbine is 57. 14%. Power generation efficiency is influenced by the combined effects of incoming wind speed, vibration velocity, and lift-drag coefficients. With changes in degrees of freedom and reduced wind speeds, the wake vortex shedding patterns of the wind turbine also vary. The vortex shedding patterns of the three-dimensional bladeless wind turbine at different heights in the span direction are similar to those of the two-dimensional wind turbine, but due to smaller vortice

关键词： Energy dissipation

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The Influence of Parameter Optimization of Rubber Nodes in High-Speed Train Turning Arms on Suppressing Hunting Motion

The Influence of Parameter Optimization of Rubber Nodes in H...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Guo, Tao Li, Ya Liu, Yongqiang Zhan Tianyou College Dalian Jiaotong University Dalian116028 China CRRC Tangshan Co. Ltd. Tangshan063000 China Shijiazhuang Enric Gas Equipment Co. Ltd. Shijiazhuang051000 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China

ISBN: (纸本)9789819639724

To solve the problems of frequent occurrence of lateral instability and abnormal wear of the tread surface during the service of high-speed trains, the stiffness characteristics and its parameters optimization of the rotating arm rubber node were analyzed in this paper. A high-speed train dynamic model was established using the dynamic analysis software Universal Mechanism with a type of 350 km/h high-speed train in China as the research object. Based on the mechanism of primary and secondary vehicle instability, the phenomena of abnormal hunting of the vehicle body and abnormal vibration of the bogie was reproduced through simulation, and the vehicle response and hunting characteristics were analyzed. The Poynting Thomson model, which can represent the stiffness frequency variation characteristic of rotating arm rubber node, was optimized by the genetic optimization algorithm. The research results indicate that the optimized arm node has a significant inhibitory effect on the instability of primary and secondary hunting movements. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Railroad transportation

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