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A decoupled method for time-dependent reliability-based design optimization

Science China(Technological Sciences) 2025年第1期68卷 308-320页

作者： Dequan ZHANG Meide YANG Xu HAN State Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Mechanical EngineeringHebei University of TechnologyTianjin 300401China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

Time-dependent reliability-based design optimization(TRBDO)has received extensive attention because of its ability to achieve optimal solutions that help meet the requirement for whole lifecycle reliability by quantitatively considering dynamic ***,directly solving TRBDO problems is computationally expensive,if not prohibitive,owing to the need to repeatedly evaluate time-dependent probabilistic *** address this challenge,an efficient decoupled method called sequential optimization and time-dependent reliability assessment(SOTRA)is proposed in this *** method transforms the original TRBDO problem,initially formulated probabilistically,into a problem using percentile formulation after discretizing time-dependent performance *** adopting the equivalent minimum performance target point(EMPTP)concept,the TRBDO problem is further converted into an equivalent deterministic optimization problem,which is subsequently solved through a sequential iteration process involving deterministic optimization and time-dependent reliability *** efficiently and robustly search an EMPTP for reliability analysis,a time-dependent self-adaptive finite-step length method is *** verify the proposed SOTRA method against existing TRBDO methods,a numerical example,a benchmark structural design case of a simply supported beam,and an engineering application for flexible wheel design are exemplified in this *** results demonstrate that the proposed SOTRA method exhibits high efficiency and robustness in solving TRBDO problems.

关键词： reliability-based design optimization dynamic uncertainties time-dependent reliability analysis decoupled method sequential optimization and reliability analysis

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Spectrum analysis of interval process model and its application in uncertain vibration analysis

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Science China(Technological Sciences) 2024年第8期67卷 2549-2564页

作者： LI JinWu JIANG Chao NI BingYu State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

In recent years, the authors have extended the traditional interval method into the time dimension to develop a new mathematical tool called the “interval process model” for quantifying time-varying or dynamic uncertainties. This model employs upper and lower bounds instead of precise probability distributions to quantify uncertainty in a parameter at any given time point. It is anticipated to complement the conventional stochastic process model in the coming years owing to its relatively low dependence on experimental samples and ease of understanding for engineers. Building on our previous work, this paper proposes a spectrum analysis method to describe the frequency domain characteristics of an interval process, further strengthening the theoretical foundation of the interval process model and enhancing its applicability for complex engineering problems. In this approach, we first define the zero midpoint function interval process and its auto/cross-power spectral density(PSD) functions. We also deduce the relationship between the auto-PSD function and the auto-covariance function of the stationary zero midpoint function interval process. Next, the auto/cross-PSD function matrices of a general interval process are defined, followed by the introduction of the concepts of PSD function matrix and cross-PSD function matrix for interval process vectors. The spectrum analysis method is then applied to random vibration problems, leading to the creation of a spectrum-analysis-based interval vibration analysis method that determines the PSD function for the system displacement response under stationary interval process excitations. Finally, the effectiveness of the formulated spectrum-analysis-based interval vibration analysis approach is verified through two numerical examples.

关键词： interval process spectrum analysis power spectral density(PSD) time-varying uncertainty uncertain vibration analysis

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Automatic Generation of Intelligent vehicle Testing Scenarios at Intersections Based on Natural Driving Datasets

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent vehicles 2023年第9期9卷 1-11页

作者： Hu, Lin Lu, Tao Li, Gen Zhang, Xin Cai, Hai School of Automotive and Mechanical Engineering and Hunan Province Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle Changsha University of Science and Technology Changsha China

Turning right at a junction without the aid of traffic signals is a frequent cause of intersection accidents and a situation that intelligent automobiles will need to handle well in the future. This allows this study to choose the traffic circumstances of turning right at junctions and traveling straight through them. It then suggests an automatic approach for creating test scenarios for intelligent vehicles based on Monte Carlo simulation. Through the examination of scene feature parameters and a natural driving dataset, a Markov chain-based right-turn trajectory model was created. Then, test vehicle trajectories and right-turn trajectories were produced using Monte Carlo simulations. By figuring out the average DTW (Dynamic Time Warping) value between the created and actual right-turn trajectories in the four speed intervals with the highest occurrence probabilities, the authenticity of the generated right-turn trajectories was confirmed. The produced trajectories were simultaneously loaded into the software for cooperative simulation. The AEB (Automatic Emergency Braking) system's shortcomings were shown by extracting the relative positions of the two cars before to the incident. The two popular varieties of AEB algorithm models were then compared using safety and comfort parameters. Furthermore, the test scenario's risk level can be managed by changing the scenario feature settings. There are some potential uses for the suggested test scenario generation method in the testing and assessment of algorithms for intelligent vehicles. IEEE

关键词： Trajectories

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High-precision tip positioning composite feedforward control of linear colocated motion systems with Bi-Loop iterative feedforward tuning

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Science China(Technological Sciences) 2025年第2期68卷 153-166页

作者： Junyu HU Yourui TAO Shanhu LI Xu HAN College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjin 300130China

To enhance the tip positioning accuracy and robustness against disturbances of linear colocated motion systems,a novel composite feedforward(COMFF)control with Bi-Loop iterative feedforward tuning(IFFT)is *** tip positioning error consists of the coupled tip residual vibration and linear motor tracking *** the influence of nonlinear friction and load flexibility,the topology of COMFF is designed as decoupled structures so that COMFF can suppress the tip residual vibration and compensate for the linear motor tracking error ***,Bi-Loop IFFT is built to improve the robustness of COMFF in high-precision motor tracking *** the state space of the linear motor tracking error based on the projection theorem,two loops are performed in parallel along the iteration *** is the P-type iteration loop that drives linear motor tracking errors to converge to the zero *** other is the observation loop constructed by the recursive least square with forgetting factors to accelerate the P-type iteration *** by the P-type iteration loop with the aid of the observation loop,the proposed COMFF is integrated with fast convergence and high robustness when confronted with model *** effectiveness of the proposed COMFF combined with Bi-Loop IFFT is validated by experiments.

关键词： composite feedforward(COMFF)control Bi-Loop iterative feedforward tuning(Bi-Loop IFFT) colocated motion systems nonlinear friction flexible load

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Microstructure evolution and precipitation behavior of Al-Mg-Si alloy during initial aging

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China Foundry 2023年第1期20卷 57-62页

作者： Ya-ya Zheng Bing-hui Luo Wei Xie Wang Li Department of Materials Engineering Hunan University of HumanitiesScience and TechnologyLoudi 417000HunanChina College of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle Changsha University of Science&TechnologyChangsha 410114China

The microstructure evolution and precipitation behavior of Al-Mg-Si alloy during initial aging were studied using hardness testing, conductivity testing, differential scanning calorimetry(DSC), and high resolution transmission electron microscopy(HRTEM). The results show that the precipitation sequence of the Al-Mg-Si alloy during initial aging can be represented as: supersaturated solid solution → spherical Mg/Si clusters → needle-like Guinier Preston(GP) zone → β″. Clusters are completely coherent with the Al matrix. The GP zone with relatively complete independent lattice parameters that differ slightly from the Al matrix parameters, is oriented along the direction of <111>Aland lying on {111}Alplane. The strength of the Al-Mg-Si alloy is greatly enhanced by the threedimensional strain field that exists between the β″ phase and the two {200}Alplanes. After aging at 170 ℃ for 6 h, the hardness reaches the peak of 127 HV and remains for a long time. At this stage, the electrical conductivity keeps relatively stable due to the formation of coherent precipitates(Mg/Si clusters/GP zones) and the reduction in solute atom concentration in the Al matrix. The severe coarsening and decreased number density of the β″ phase during the over-aging stage result in a significant decrease in the hardness.

关键词： Al-Mg-Si alloy precipitation behavior strengthening mechanism strain field β″

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Effects of the windshield inclination angle on head/brain injuries in car-to-pedestrian collisions using computational biomechanics models

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Transportation safety and Environment 2024年第2期6卷 1-12页

作者： Fang Wang Mingliang Wang Lin Hu Ke Peng Jiajie Yin Danqi Wang Liangliang Shi Zhou Zhou School of Automotive and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410114HunanChina Hunan Province Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle Changsha University of Science and TechnologyChangsha 410114HunanChina State Key Laboratory of Vehicle NVH and Safety Technology China Automotive Engineering Research Institute Co.Ltd.Chongqing 401122China Division of Neuronic Engineering KTH Ro y al Institute of TechnologyStockholm 14152Sweden

Car-to-pedestrian collision(CPC)accidents occur frequently,and pedestrians often suffer serious head/brain *** major cause is the primary impact with the ***,we use an umerical sim ulation method to study the influence of the windshield in-clination angle of a passenger car on pedestrian head/brain injury due to CPC *** range of the windshield inclination angle was set at 24°-50°,with an interval of 2°.The results show that the windshield angle significantly affects the pedestrian kine-matics and exerts different effects on the head injury when evaluating with various head injury *** the head peak linear/rotational acceleration and acceleration-based head injury criterion(HIC)/rotational injury criterion(RIC),the predictions at the secondary impact stage have no clear relationship with the windshield angle(R^(2)=0.04,0.07,0.03 and 0.26,respectively)and their distributions are *** the primary impact,the peak linear acceleration and HIC show a weak trend of first decreasing and then increasing with the increasing of the windshield angle,and the rotational acceleration and RIC tend to remain relatively *** the cum ulative strain dama ge measure(CSDM)criterion,the predictions at the primary impact are slightly lower than those at the secondary impact,and the trend of first decreasing and then increasing with the increase in the windshield angle is observed at both impact *** the windshield inclination angle is approximately 32°-40°,the head injury severity in both impact phases is generally lower than that predicted at other windshield angles.

关键词： car-to-pedestrian collision(CPC) head/brain injury head injury criterion(HIC) windshield inclination angle computa-tional biomechanics model(CPCBM)

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High-precision numerical modeling of the pro jectile launch and failure mechanism analysis of pro jectile-borne components

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Applied Mathematics and Mechanics(English Edition) 2025年第5期46卷 885-906页

作者： Xindan GUO Qiming LIU Xu HAN Tao LI Bin’an JIANG Canwei CAI State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Mechanical EngineeringHebei University of TechnologyTianjin 300401China Artillery Ammunition Technology Laboratory PLA Army Academy of Artillery and Air DefenseHefei 230031China

As core components of precision-guided projectiles,projectile-borne components are highly susceptible to failure or even damage in complex high-overload environments,thereby significantly compromising launch reliability and ***,accurately characterizing the mechanical behavior of propellants remains challenging due to the limitations in the current internal ballistic theory and the constraints of large-scale artillery firing *** complicates the high-precision numerical modeling of projectile launch,and obstructs investigations into the failure mechanisms of projectile-borne ***,this paper identifies propellant parameters using the computational inverse method under uncertainty,further establishes high-precision numerical models of projectile launch,and explores the failure mechanisms of projectile-borne components in complex high-overload ***,a projectile launching experiment is meticulously designed and executed to obtain the breech pressure and muzzle ***,a general simulation model is built,and the powder burn model is used to simulate the ignition and ***,the propellant parameters are effectively identified with the computational inverse method by the combination of the experiments and simulations.A high-precision numerical model of projectile launch is modified with the parameters validated by another experiment,and the high-overload characteristics during projectile launch are thoroughly analyzed based on this ***,the high-overload characteristics of projectile-borne components are analyzed to elucidate the stress variation laws and to reveal the failure mechanisms influenced by time and spatial *** research provides an effective method for perfectly identifying propellant parameters and building high-precision numerical models of projectile ***,it provides significant guidance for the anti-high overload design and analysis of projectile-bo

关键词： projectile-borne component high-overload environment propellant parameter identification computational inverse technique failure mechanism

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Path Tracking Controller design of Automated Parking Systems via NMPC with an Instructible Solution

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Chinese Journal of Mechanical engineering 2024年第3期37卷 353-367页

作者： Liang Chen Zhaobo Qin Manjiang Hu Yougang Bian Xiaoyan Peng State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China Wuxi Intelligent Control Research Institute of Hunan University Wuxi 214115China

Parking difficulties have become a social issue that people have to *** parking system is practicable for quick par operations without a driver which can also greatly reduces the probability of parking *** paper proposes a Lyapunov-based nonlinear model predictive controller embedding an instructable solution which is generated by the modified rear-wheel feedback method(RF-LNMPC)in order to improve the overall path tracking accuracy in parking ***,A discrete-time RF-LNMPC considering the position and attitude of the parking vehicle is proposed to increase the success rate of automated parking ***,the RF-LNMPC problem with a multi-objective cost function is solved by the Interior-Point Optimization,of which the iterative initial values are described as the instructable solutions calculated by combining modified rear-wheel feedback to improve the performance of local optimal ***,the details on the computation of the terminal constraint and terminal cost for the linear time-varying case is *** closed-loop stability is verified via Lyapunov techniques by considering the terminal constraint and terminal cost ***,the proposed RF-LNMPC is implemented on a selfdriving Lincoln MKZ platform and the experiment results have shown improved performance in parallel and vertical parking *** Monte Carlo analysis also demonstrates good stability and repeatability of the proposed method which can be applied in practical use in the near future.

关键词： Automated parking Path tracking controller Nonlinear model predictive control Monte Carlo analysis

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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

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A study of boundary conditions for pedestrian thorax impact test

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International Journal of vehicle Systems Modelling and Testing 2024年第2期18卷 120-133页

作者： Long, Yongcheng Liu, Yu Xiao, Yu Ruan, Zhisheng Xiao, Zhi Zhang, Guanjun Huang, Jing State Key Laboratory of Intelligent Vehicle Safety Technology Chongqing401122 China China Automotive Engineering Research Institute Co. Ltd. Chongqing401122 China Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Changsha410082 China

Thorax injury is one of the main injuries during pedestrian impacts, and it is important to determine the boundary conditions for pedestrian thorax impactor tests. A series of virtual cases were built up to simulate the vehicle-pedestrian impact accidents. Then, the kinematic process was analysed during the vehicle-pedestrian impacts, and thorax impact parameters were extracted. Finally, the statistical characteristics of these impact parameters were obtained for thorax impactor tests. The results show that vehicle type affects the pedestrian impact kinematics and thorax impact parameters significantly. The range of thorax wrap-around distance is 928~1915 mm and 1018~1762 mm during sedan-pedestrian impact and SUV-pedestrian impact respectively. The average thorax impact speeds are about 5.8 m/s and 4.8 m/s in sedan-pedestrian impact and in SUV-pedestrian impact respectively. The average thorax impact velocity angles are 26.8° and 19.5° respectively. These results can provide the effective reference data for pedestrian thorax impactor tests. Copyright © 2024 Inderscience Enterprises Ltd.

关键词： Kinematics

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