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SSRN 2023年

作者： Qiao, Junhao Liu, Jingping Jia, Dongdong Wang, Rumin Fu, Jianqin Duan, Xiongbo State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha410082 China Hunan Dazi Power Technology Co. Ltd Changsha410221 China School of Energy Science and Engineering Central South University Changsha410083 China

A novel design of the Miller cycle (MC) achieved by the asynchronous intake valve is adopted in the test spark ignition (SI) engine with different high compression ratios (CR12.5 and CR14.5). The influences of compression ratio (CR12.5 and CR14.5) and asynchronous intake valve Miller cycle (AIVMC) on the combustion cycle-to-cycle variations (CCV) of a GDI baseline engine are conducted and compared to the original Otto cycle (OC). Meanwhile, the influences of EGR strategy on the CCV, combustion phase and emissions of the modified engine with AIVMC are also discussed. Results show that using AIVMC can realize Miller cycle by adjusting the timing of variable valve. Moreover, the high geometric compression ratio SI engine equipped with AIVMC not only reduces the cyclic variation at low load compared with the OC cycle, but also optimizes combustion phase because of superior anti-knock ability, which improves operating stability and reduce fuel consumption. In addition, coupling application of AIVMC and EGR strategy in test SI engine enhances engine knock tolerance. Besides, using the EGR and AIVMC in the test SI engine can significantly reduce NOx emissions compared to only use the AIVMC. Meanwhile, the NOx emissions gain a reduction of 68.7% with using EGR. © 2023, The Authors. All rights reserved.

关键词： Intake valves

Human-Machine Shared Control Approach for the Takeover of Cooperative Adaptive Cruise Control

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arXiv

arXiv 2024年

作者： Wang, Haoran Li, Zhenning Eichberger, Arno Hu, Jia Key Laboratory of Road and Traffic Engineering The Ministry of Education Tongji University Shanghai201804 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha410082 China State Key Laboratory of Internet of Things for Smart City Departments of Civil and Environmental Engineering and Computer and Information Science University of Macau Avenida da Universidade Taipa China Institute of Automotive Engineering Graz University of Technology GrazA‐8010 Austria

Cooperative Adaptive Cruise Control (CACC) often requires human takeover for tasks such as exiting a freeway. Direct human takeover can pose significant risks, especially given the close-following strategy employed by CACC, which might cause drivers to feel unsafe and execute hard braking, potentially leading to collisions. This research aims to develop a CACC takeover controller that ensures a smooth transition from automated to human control. The proposed CACC takeover maneuver employs an indirect human-machine shared control approach, modeled as a Stackelberg competition where the machine acts as the leader and the human as the follower. The machine guides the human to respond in a manner that aligns with the machine’s expectations, aiding in maintaining following stability. Additionally, the human reaction function is integrated into the machine’s predictive control system, moving beyond a simple "prediction-planning" pipeline to enhance planning optimality. The controller has been verified to i) enable a smooth takeover maneuver of CACC;ii) ensure string stability within a specific Operational design Domain (ODD) when human control authority is below 32.7%;iii) enhance both perceived and actual safety through machine interventions;and iv) reduce the impact on upstream traffic by up to 60%. © 2024, CC BY.

关键词： Model predictive control

Investigating 3d Object Detection Using Stereo Camera and LiDAR Fusion with Bird'S-Eye View Representation

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SSRN 2024年

作者： Zhu, Lin Nie, Xin He, Zhicheng Cheng, Aiguo Li, Eric Zhong, ShengZheng State Key Laboratory of Advanced Design and Manufacture Technology for Vehicle Hunan University Changsha410082 China Wuling New Energy Automobile Co. Ltd. Liuzhou545007 China School of Computing Engineering & Digital Technologies Teesside University Middlesbrough United Kingdom

Multi-sensor fusion for 3D object detection is a crucial development in autonomous vehicle technology. Current research primarily explores the combination of monocular cameras with LiDARs. However, there is a notable gap in the integration of stereo cameras with LiDARs. A significant drawback of the fusion between monocular cameras and LiDARs is its vulnerability to sensor failures, which can completely disable the system. This paper presents a novel end-to-end framework called SLBEVFusion, which leverages the effective combination of stereo cameras and LiDARs for 3D object detection. The framework utilizes the rich semantic and depth data from stereo images along with spatial data from LiDAR point clouds to improve detection accuracy. Moreover, it addresses sensor failures by isolating the data streams of each sensor and implementing straightforward feature fusion in Bird's Eye View (BEV) space. Comprehensive testing on the challenging KITTI dataset demonstrates that our approach significantly enhances performance in 3D object detection by merging stereo cameras with LiDARs. © 2024, The Authors. All rights reserved.

关键词： Semantics

Intelligent Prediction and Analysis of Mechanical Properties of Magnesium Alloys Using Interpretable Machine Learning

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SSRN 2023年

作者： Moses, Atwakyire Gui, Ying Michael, Marembo Chen, Buzhuo Chen, Ding State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Faculty of Engineering Technology Applied Design and Fine Art Department of Mechanical Engineering Kabale University P.O. Box 317 Kabale Uganda CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Hefei230027 China Department of Material Science and Engineering The Ohio State University ColumbusOH43210 United States

The Magnesium-rare earth alloy dataset was compiled by collecting data from the experiment and utilizing machine learning (ML) models to predict the mechanical properties of 348 sample tests. The proportion between the predicted and experimental results produced by different ML models demands more advanced regression methods to obtain better results. Utilizing magnesium chemical compositions at elevated temperatures as input variables and mechanical properties as output variables, four different machine learning (ML) models were employed namely (i.e.) Random Forest (RF), Extra Tree (ET), Gradient Boost (GB), and XG Boost (XGB) to resolve this difficult problem. Each single algorithm aimed to predict the mechanical properties of Mg-rare earth alloy i.e. ultimate tensile strength (UTS), yield strength (YS), and elongation (EL). Subsequently, the data-driven intelligent prediction modeling technique called Super learner (SL) was employed to integrate the single models into the stacked model approach to enhance prediction accuracy. The results obtained using SL models demonstrated enhanced prediction accuracy for UTS, YS, and EL. The findings further demonstrate enhanced prediction ability by outperforming other approaches as demonstrated by lower RMSE and higher R2 compared to previous studies. The reason to choose SL is because of its robustness, less prone to overfitting, and is also widely known for its better scalability, simplicity, and ability to handle noisy. The SL model is an optimal approach for predicting the properties of Mg-rare earth alloys. The proposed SL approach can serve as a tool for predicting the properties of Mg alloys. © 2023, The Authors. All rights reserved.

关键词： Magnesium alloys

Configuration design and control of hybrid tracked vehicle with three planetary gear sets

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Journal of Central South University 2021年第7期28卷 2105-2119页

作者： LI Rui FAN Jing-jing HAN Zheng-da GUAN Shuai QIN Zhao-bo School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China China North Vehicle Research Institute Beijing 100072China Intelligent Transportation Key Laboratory North China University of TechnologyBeijing 100144China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

The hybrid tracked vehicles(HTV)usually adopt series hybrid powertrain with extra steering mechanism,which has relatively low transmission efficiency and reduces the flexibility of structural *** overcome the disadvantages,a new kind of single-mode powertrain has been *** power-split hybrid powertrain is composed of three planetary gear(PG)sets connected to one engine,left and right track outputs,and three *** proposed powertrain can realize steering while going forward by controlling the output torque on each side without extra steering mechanism or steering *** to the diversity of the connection way between components and planetary gear sets,a rapid configuration design approach is proposed for the design selection of *** automated dynamic modelling method can show the one-to-one correspondence with the selected feasible groups by establishing two characteristic matrices,which is more simple than other *** analytically-based method is proposed to classify all possible connection designs into several groups to decrease the searching scope with improved design ***,the optimal control strategy is used to find the design with optimal fuel economy under typical condition of *** case study is implemented by the proposed design approach which demonstrates better design performances compared with the existing series-hybrid HTV.

关键词： hybrid tracked vehicles planetary gear optimal design control

Space Domain based Ecological Cooperative and Adaptive Cruise Control on Rolling Terrain

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arXiv

arXiv 2024年

作者： Lei, Mingyue Wang, Haoran Xiong, Lu So, Jaehyun Dhamaniya, Ashish Hu, Jia Key Laboratory of Road and Traffic Engineering The Ministry of Education Tongji University Shanghai China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha China School of Automotive Studies Tongji University Shanghai China Department of Transportation Systems Engineering Ajou University Gyeonggi-do Korea Republic of Department of Civil Engineering SV National Institute of Technology Gujarat India

Cooperative and Adaptive Cruise Control (CACC) is widely focused to enhance driving fuel-efficiency by maintaining a close following gap. The ecology of CACC could be further enhanced by adapting to the rolling terrain. However, current studies cannot ensure both planning optimality and computational efficiency. Firstly, current studies are mostly formulated on the conventional time domain. These time domain based methods cannot ensure planning optimality for space-varying road slopes. Secondly, fuel consumption models are non-linear and hard to solve efficiently. Hence, this paper proposes a space domain based Ecological-CACC (Eco-CACC) controller. It is formulated into a nonlinear optimal control problem with the objective of optimizing global fuel consumptions. Furthermore, a differential dynamic programming-based solving method is developed to ensure real-time computational efficiency. Simulation results have shown that the proposed Eco-CACC controller can improve average fuel saving by 37.67% at collector road and about 17.30% at major arterial. String stability of the proposed method has been theoretically proven and experimentally validated. © 2024, CC BY.

关键词： Adaptive cruise control

Observation of fractal higher-order topological states in acoustic metamaterials

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Science Bulletin 2022年第20期67卷 2069-2075,M0004页

作者： Shengjie Zheng Xianfeng Man Ze-Lin Kong Zhi-Kang Lin Guiju Duan Ning Chen Dejie Yu Jian-Hua Jiang Baizhan Xia State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China College of Mechanical and Electrical Engineering Changsha UniversityChangsha 410022China Institute of Theoretical and Applied Physics School of Physical Science and Technology&Collaborative Innovation Center of Suzhou Nano Science and TechnologySoochow UniversitySuzhou 215006China

Topological phases of matter have been extensively investigated in solid-state materials and classical wave systems with integer dimensions. However, topological states in non-integer dimensions remain almost unexplored. Fractals, being self-similar on different scales, are one of the intriguing complex geometries with non-integer dimensions. Here, we demonstrate fractal higher-order topological states with unprecedented emergent phenomena in a Sierpin? ski acoustic metamaterial. We uncover abundant topological edge and corner states in the acoustic metamaterial due to the fractal geometry. Interestingly,the numbers of the edge and corner states depend exponentially on the system size, and the leading exponent is the Hausdorff fractal dimension of the Sierpin? ski carpet. Furthermore, the results reveal the unconventional spectrum and rich wave patterns of the corner states with consistent simulations and experiments. This study thus unveils unconventional topological states in fractal geometry and may inspire future studies of topological phenomena in non-Euclidean geometries.

关键词： Higher-order topological states Topological fractals Sierpinski carpet Fractal dimensions Acoustic metamaterials

Superfolded configuration induced low thermal conductivity in two-dimensional carbon allotropes revealed via machine learning force constant potential

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arXiv

arXiv 2023年

作者： Yu, Linfeng Dong, Kexin Yang, Qi Zhang, Yi Zheng, Xiong Wang, Huimin Qin, Zhenzhen Qin, Guangzhao National Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Hunan Key Laboratory for Micro-Nano Energy Materials & Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China School of Physics and Microelectronics Zhengzhou University Zhengzhou450001 China Research Institute of Hunan University in Chongqing Chongqing401133 China Greater Bay Area Institute for Innovation Hunan University Guangdong Province Guangzhou511300 China

Understanding the fundamental link between structure and functionalization is crucial for the design and optimization of functional materials, since different structural configurations could trigger materials to demonstrate diverse physical, chemical, and electronic properties. However, the correlation between crystal structure and thermal conductivity (κ) remains enigmatic. In this study, taking two-dimensional (2D) carbon allotropes as study cases, we utilize phonon Boltzmann transport equation (BTE) along with machine learning force constant potential to thoroughly explore the complex folding structure of pure sp2 hybridized carbon materials from the perspective of crystal structure, mode-level phonon resolved thermal transport, and atomic interactions, with the goal of identifying the underlying relationship between 2D geometry and κ. We propose two potential structure evolution mechanisms for targeted thermal transport properties: in-plane and out-of-plane folding evolutions, which are generally applicable to 2D carbon allotropes. It is revealed that the folded structure produces strong symmetry breaking, and simultaneously produces exceptionally strongly suppressed phonon group velocities, strong phonon-phonon scattering, and weak phonon hydrodynamics, which ultimately lead to low κ. The insight into the folded effect of atomic structures on thermal transport deepens our understanding of the relationship between structure and functionalization, which offers straightforward guidance for designing novel nanomaterials with targeted κ, as well as propel developments in materials science and engineering. Copyright © 2023, The Authors. All rights reserved.

关键词： Phonons

Exploring traffic safety climate with driving condition and driving behaviour:a random parameter structural equation model approach

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Transportation safety and Environment 2021年第3期3卷 304-315页

作者： Daiquan Xiao Xiaofei Jin Xuecai Xu Changxi Ma Quan Yuan Huazhong University of Science and Technology School of Civil and Hydraulic EngineeringWuhan 430074China Shanghai Municipal Engineering Design Institute(Wuhan Branch) Wuhan 430000China Lanzhou Jiaotong University School of Traffic and Transportation EngineeringLanzhou 730070China State Key Laboratory of Automotive Safety and Energy School of Vehicle and MobilityTsinghua UniversityBeijing 100084China

This study aimed to explore traffic safety climate by quantifying driving conditions and driving *** achieve the objective,the random parameter structural equation model was proposed so that driver action and driving condition can address the safety climate by integrating crash features,vehicle profiles,roadway conditions and environment *** geo-localized crash open data of Las Vegas metropolitan area were collected from 2014 to 2016,including 27 arterials with 16827 injury *** quantifying the driving conditions and driving actions,the random parameter structural equation model was built up with measurement variables and latent *** revealed that the random parameter structural equation model can address traffic safety climate quantitatively,while driving conditions and driving actions were quantified and reflected by vehicles,road environment and crash features *** findings provide potential insights for practitioners and policy makers to improve the driving environment and traffic safety culture.

关键词： traffic safety culture traffic safety climate random parameter structural equation model driving condition driving behaviour

Development of Test Scenarios for vehicle and Two-Wheeler at Intersection Based on China In-Depth Accident Study

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SSRN 2022年

作者： Hu, Lin Li, Gen Wu, Ning Lin, Miao Bo, Ying Wang, Fang School of Automotive and Mechanical Engineering Changsha University of Science and Technology Changsha China Hunan Province Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle Changsha University of Science and Technology Changsha China Traffic Engineering and Management Ruhr-University Bochum Germany China Automobile Technology Research Center Co. Ltd Tianjin China China Society of Automotive Engineers Beijing China

Autonomous vehicles (AVs) after fully tested can effectively reduce the accident rate of two-wheelers (TWs), for which the development of test scenarios is one of basic prerequisites. The existing TW test scenarios are difficult to deploy in the simulation software because the details like accident location are ignored. In this study, the typical TW test scenarios at intersections (crossroads or T-junctions) were developed using accident data from China In-Depth Accident Study (CIDAS). First, 1239 TWs accidents involving intersection were selected from CIDAS, and the correlation analysis was carried out for road type, TW type, weather, accident time, traffic light, and other thirteen variables. Second, the bi-level clustering structure based on k-medoids algorithm was used in this study, in which the first level was used to merge variables with high correlation and the second for mining typical accident scenarios. Third, the scenario injury index based on weight coefficient was proposed, and scenarios with high-frequency and high injury index were extracted. The four main conclusions are as follows: (1) Many scenarios not found in previous studies have been developed, which involving retrograde ETWs, ETWs crossing the road through the sidewalk, and crossroad equipped with traffic lights;(2) Two high frequency scenarios and four scenarios with high injury index were obtained. Motorcycle scenarios have lower frequency than electric two-wheeler (ETW), but with higher injury index due to high velocity;(3) The vehicles are mainly turning at T-junction scenarios, while traveling straight at the crossroad;(4) Future research on test scenarios should focus on some special situations, such as: Failure to give way, Retrograde TWs, Traffic light conflict including jumping the red light and traffic light switching gap, and visual obstruction. The research methods and conclusions can be used as guidelines or references for AVs test based on scenario. © 2022, The Authors. All rig

关键词： Autonomous vehicles