摘要：
The traffic situation at an urban intersection is complicated, due to the numerous internal conflicts and all kinds of traffic accidents. With the objective of improving road safety, the automotive industry is moving toward intelligent vehicles. The major challenges are accurately perceiving the road traffic environment, detecting the potential traffic conflicts, and proposing the alternative driving strategies. This paper summarizes the existing researches on traffic conflicts from the perspective of intelligent vehicles. The intelligent vehicles can perceive the surrounding environment, extract road condition information, and detect obstacles for avoiding collisions or mitigating accidents. It expounds that the perception technology of intelligent vehicles can be divided into three main categories, namely, the perception technology, the communication technology, and the fusion of perception-communication technology. At the same time, the existing technical problems are analyzed. Finally, future development trends in this field are discussed.
作者机构：
长沙理工大学汽车与机械工程学院, 长沙, 410114;长沙理工大学, 工程车辆安全性设计与可靠性技术湖南省重点实验室, 长沙, 410114;湖南大学, 汽车车身先进设计制造国家重点实验室, 长沙, 410082;中国汽车技术研究中心, 天津, 300162;[胡林; 陈凯] School of Automotive and Mechanical Engineering, Changsha University of Science and Technology, Changsha, 410114, China<&wdkj&>Hunan Province Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle, Changsha University of Science and Technology, Changsha, 410114, China
通讯机构：
[Hu, XS; Yang, YL] C;Chongqing Univ, Dept Automot Engn, State Key Lab Mech Transmiss, Chongqing 400044, Peoples R China.
关键词：
Mechanical power transmission;Gears;Mathematical model;Graph theory;Fuel economy;Hybrid electric vehicles;Topology;Hierarchical topological graph theory;hybrid electric vehicles;multi-mode;power split
摘要：
Power split hybrid electric vehicles (PS-HEVs) dominate the US and Japanese HEV market because of their superior fuel economy and drivability. In recent years, multi-mode PS-HEVs are offered by Toyota and GM. With multiple modes, it is possible for PS-HEVs to have both good launching/towing performance and fuel economy. Multiple modes are achieved by adding clutches or brakes. However, the corresponding design space can be quite large. To expedite the design process, a hierarchical topological graph theory approach is developed to systematically design a multi-mode PS-HEV with two planetary gear sets (PGSs). The process consists of three steps: 1) model the hybrid powertrain, 2) generate the multi-mode designs with specific modes, and 3) evaluate the performance of design candidates. In the performance screening process, designs are examined using the dynamic programming (DP) algorithm to evaluate their acceleration performance (0-100 km/h); and then a rapid dynamic programming (Rapid-DP) approach is used to compute their fuel economy under a specific driving cycle. Designs that pass the screening will then be retained as final vehicle designs. This design process ensures that the best designs are found and used.
关键词：
Batteries;Discharges (electric);Feature extraction;Estimation;Correlation;Aging;Lithium-ion batteries;Data-driven method;feature extraction method;health indicator (HI);lithium-ion battery;state of health (SOH)
摘要：
State of health (SOH) is essential for battery management, timely maintenance, and safety incident avoidance. For specific applications, a variety of SOH estimation methods have been proposed. However, it is often difficult to apply these methods to other applications. In this article, a novel feature extraction method is proposed to extract health indicators (HIs) from general discharging conditions. A voltage partition strategy is used to obtain the discharge capacity differences of two cycles [oQ(V)] from nonmonotonic or pulse discharge voltage curve, and a filtering strategy is employed to obtain smooth voltage curves under dynamic discharging conditions. The standard deviations of the discharge capacity curve and oQ(V) are selected as HIs and are verified to have strong correlations to battery capacity under different datasets for three types of batteries. By using these HIs as input features, typical data-driven methods, including linear regression, support vector machine, relevance vector machine, and Gaussian process regression (GPR), are constructed to predict battery SOH. The estimation results of these methods are compared under different operating conditions for the three types of batteries. Good estimation accuracy is achieved for all these methods. Among them, the GPR has the best performance, and its maximum absolute error and root-mean-square error are lower than 1% and 1.3%, respectively.
作者机构：
[Wu, Xianhui; Hu, Lin] Changsha Univ Sci & Technol, Sch Automot & Mech Engn, Changsha, Peoples R China.;[Wu, Xianhui; Hu, Lin] Changsha Univ Sci & Technol, Hunan Prov Key Lab Safety Design & Reliabil Techn, Changsha, Peoples R China.;[Huang, Jing] Hunan Univ, State Key Lab Adv Design & Manufacture Vehicle Bo, Changsha, Peoples R China.;[Peng, Yong] Cent South Univ, Sch Traff & Transportat Engn, Changsha, Peoples R China.;[Liu, Weiguo] Geely Automobile Res Inst Co Ltd, Ningbo, Peoples R China.
通讯机构：
[Huang, Jing] H;Hunan Univ, State Key Lab Adv Design & Manufacture Vehicle Bo, Changsha, Peoples R China.
关键词：
Pedestrian crashes;Geographic information system (GIS);Logit analysis;Tree-based model;Injury severity;Clusters
摘要：
Improving the pedestrian traffic environment is important for the sustainable development of the city. This study goes beyond the traditional analysis of traditional traffic accident police reports by integrating them with rich geographic information system (GIS) resources to analyze a sample of 791 pedestrian crashes that occurred in the main urban area of Changsha city, China, from 2014 to 2016. The use of Baidu or Google Street View maps improves the accident reports and facilitates the detailed description of the characteristics that are related to pedestrian crashes. The focus of the analysis is to use GIS to visualize the distribution of pedestrian crashes in cities to explore the relationships between pedestrian crashes and the population, road network, land use and social services and activities and to analyze the impacts of the building environment and road characteristics on the severity of pedestrian crashes by combining the binary logistic regression and tree-based models. The results demonstrate that there are several clusters of pedestrian crashes in urban areas, which are related to the population, road network, regional functional zoning and social and economic characteristics. However, the severity of pedestrian casualties has strong relationships with darkness, lighting conditions, road isolation facilities and pedestrian age and behavior. Casualties are more severe at night than during the day, and school-age children and elderly pedestrians tend to suffer more. This study identifies the important influencing factors of urban pedestrian safety and of the risk awareness of pedestrians and other road users and proposes solutions from the perspectives of behavior and infrastructure.
关键词：
Batteries;energy management;fuel cell;hybrid electric vehicle (HEV);predictive control;sustainable transport
摘要：
Energy management is an enabling technology for increasing the economy of fuel cell/battery hybrid electric vehicles. Existing efforts mostly focus on optimization of a certain control objective (e.g., hydrogen consumption), without sufficiently considering the implications for on-board power sources degradation. To address this deficiency, this article proposes a cost-optimal, predictive energy management strategy, with an explicit consciousness of degradation of both fuel cell and battery systems. Specifically, we contribute two main points to the relevant literature, with the purpose of distinguishing our study from existing ones. First, a model predictive control framework, for the first time, is established to minimize the total running cost of a fuel cell/battery hybrid electric bus, inclusive of hydrogen cost and costs caused by fuel cell and battery degradation. The efficacy of this framework is evaluated, accounting for various sizes of prediction horizon and prediction uncertainties. Second, the effects of driving and pricing scenarios on the optimized vehicular economy are explored.
摘要：
<jats:p>In order to identify the abnormal road surface condition efficiently and at low cost, a road surface condition recognition method is proposed based on the vibration acceleration generated by a smartphone when the vehicle passes through the abnormal road surface. The improved Gaussian background model is used to extract the features of the abnormal pavement, and the k-nearest neighbor (kNN) algorithm is used to distinguish the abnormal pavement types, including pothole and bump. Comparing with the existing works, the influence of vehicles with different suspension characteristics on the detection threshold is studied in this paper, and an adaptive adjustment mechanism based on vehicle speed is proposed. After comparing the field investigation results with the algorithm recognition results, the accuracy of the proposed algorithm is rigorously evaluated. The test results show that the vehicle vibration acceleration contains the road surface condition information, which can be used to identify the abnormal road conditions. The test result shows that the accuracy of the recognition of the road surface pothole is 96.03%, and the accuracy of the road surface bump is 94.12%. The proposed road surface recognition method can be utilized to replace the special patrol vehicle for timely and low-cost road maintenance.</jats:p>
摘要：
In this work, the adiabatic shear band of TA1 titanium alloy subjected to electromagnetic impact loading was investigated. The formation of adiabatic shear band and microstructure evolution within it were revealed by microstructure characterizations. Deformation results showed an adiabatic shear band with the width of 10 μm located in shear deformation zone, and most deformations mainly concentrated in the narrow band. The compressive instability and the hardness difference contributed to the formation of adiabatic shear band. Severe shear deformations led to high location density within the adiabatic shear band. A large amount of dislocations distributed in the form of dislocation cells and random dislocations. The rotational dynamic recrystallization mechanism caused that many dynamic recrystallization grains with the size of 100–200 nm were found inside the adiabatic shear band. Adiabatic temperature rise and distortion energies stored by high dislocation densities provided sub-grain rotations with the driving forces.
关键词：
epidemiology;health and safety;hearing;occupational health practice;statistics
摘要：
OBJECTIVE: Hearing loss caused by high levels of noise is a potential occupational health disorder among train drivers around the world. This study aims to investigate the relationship between tunnel driving occupational environment and hearing loss in train drivers, to provide some insights into helping reduce hearing loss among train drivers. METHODS: This study analysed cross-sectional data for 1214 train drivers who work at China Railway Guangzhou Group. Health examination was taken by physicians with professional licences, and audiometric testing was performed by health technicians in a sound-isolated room. T/R is defined as the ratio of the length of the tunnels to the length of the railway along drivers' work routes. Different multivariate models and stratified models were established for sensitivity analysis. A multivariable logistic regression model was used to estimate the ORs of hearing loss associated with tunnel driving occupational environment. RESULTS: The adjusted OR for high-frequency hearing loss in association with the highest T/R levels (30%-45%) versus the lowest T/R levels (<15%) was 3.72 (95% CI 1.43 to 9.69). The corresponding OR for speech-hearing loss was 1.75 (95% CI 0.38 to 8.06). The sensitivity analysis shows our results are suitable for various alternative models. CONCLUSIONS: This study found that there was a significant association between tunnel driving occupational environment and hearing loss. Train drivers who work in a higher T/R environment have worse hearing loss.
摘要：
Traction batteries constitute a core technology for electric vehicles. The cells used in such batteries are usually connected in a series-parallel structure. Significant degradation in energy density, cycle life, and safety occurs with battery usage, thanks to discrepancies among cell parameters, such as resistance, capacity, and State of Charge. Hence, it is imperative to explore propagation mechanisms of parameter inconsistency and develop methods to diagnose them. The state of the art in the two aspects are elaborated from three perspectives of internal, external, and coupling effects. Modeling approaches for parameter inconsistency available in the existing literature are comprehensively surveyed, with the purpose of spurring innovative ideas for establishing new models. Methods of data processing and feature extraction are systematically summarized in order to promote diagnostic efficiency and credibility. Moreover, methods of battery inconsistency evaluation and diagnosis are reviewed with the aim of catalyzing the development of new diagnostic algorithms. Finally, existing problems and future trends in the field of battery pack inconsistency research are elucidated.
摘要：
As an advanced interference-fit joining technology, electromagnetic riveting (EMR) has wide engineering application prospects in manufacturing and assembly fields. In this paper, a theoretical model on interference fit for EMR process is derived based on the stress wave theory and thick wall cylinder theory. EMR experiments are conducted to verify the analytical model. The compared results show that the analytical solutions agree well with experimental values. The interference-fit model synthetically considers many process parameters factors, not only the material properties and size of rivet, sheets and punch, but also the riveting force. The residual stress distribution, which is an important factor on fatigue life, can be predicted by this model. In addition, this can provide scientific guidance for the process parameter design and riveting setup optimization in engineering application.
摘要：
In order to obtain a more accurate interval of an accident reconstruction result, two modified experiment design methods were proposed. The first is based on the orthogonal design (OD) and it is named as the orthogonal-based design (OBD), while the other is based on the uniform design (UD) and it is named as the multi-response surface-uniform design (MUD). Furthermore, some conclusions are given according to seven numerical cases: results obtained from the Latin hypercube sampling design (LHS) are the worst, while those obtained from the UD are the last but one, and all are worse than the results obtained from the OBD and the MUD. Furthermore, some conclusions about the number of simulation runs of each design of experiment (DOE) can be given: if the second order response surface model is selected, the number of simulation runs of the LHS is the same as the UD, and all are lesser than the number of simulation runs of the OBD and the MUD in most cases. As for the OBD and the MUD, the number of simulation runs of the OBD is lesser than the number of simulation runs of the MUD, but the MUD can be applied more widely than the OBD. Finally, a true vehicle-pedestrian accident case is given, Pc-Crash was used to reconstruct the accident based on all traces provided by the police, and the interval of the impact velocity of the vehicle was calculated using the OBD, results showed that the research is meaningful in practice.
