天津城市轨道交通网络的区域救援模式

介绍了天津城市轨道交通线路布局及实际运营情况,结合单线救援模式的不足,分析了天津城市轨道交通采用区域救援模式的可行性。从设置救援抢修点、划分救援区域、组建联合救援队、设备配备等方面对区域救援模式和区域救援模式的优势进行了详细阐述。     

提高公路物流运输中空车利用率的研究

对传统道路交通运输模式易导致空车利用率低、降低运输效率、引起资源浪费的问题进行研究分析,提出相应的对策,对提高公路物流运输中的空车利用率具有重要意义.     

规费征管之我见

在社会主义市场经济的新形势下,只有认真贯彻依法征费的方针,不断完善征费管理机制,才能多征费、征好费,从而更好地为国家的经济建设服务。     

汽车焊接结构冲击拉伸强度分析

利用改进的霍普金森棒法对汽车用钢板的圆弧焊接接头试验片进行了静强度和冲击强度的拉伸试验,得到了三种不同材料试验片的应变率、应力波、冲击破坏变形和破坏速度并对试验结果进行了分析.试验结果为车体材料的选择提供了依据.     

城市轨道车辆的粘着利用与节能

轮轨间的最佳粘着利用对城市轨道车辆节能起着重要作用.本文分析了城市轨道车辆的粘着特点,提出了改善其粘着利用的途径,并指出了装设粘控装置能实现最佳粘着利用,收到良好的节能效果.     

城市轻轨车辆转向架方案的选择

本文根据城市轻轨车辆用转向架的运用条件和技术要求,结合我国的技术水平和传统特点,对城市轻轨车辆转向架结构设计中应考虑的问题进行了分析,认为在进行轻轨车辆转向架设计时,应采用空气弹簧、盘形制动,弹性车轮、磨耗形踏面、焊接构架等先进技术.     

国内外汽车—油品—排放项目研究概述

为了减少汽车排放,满足日益严格的排放标准,20世纪后期以来国内外对燃油成分、性能影响排放的规律进行了大量研究,对美国AQIRP、欧洲EPEFE、日本JCAP和国内相关研究项目进行了总结,提出在日益严格的排放法规的基础上根据国内的炼油结构、燃油水平和当代及未来汽车先进技术进行燃油指标对排放的影响研究的必要性。     

Deriving macroscopic fundamental diagrams from probe data: Issues and proposed solutions

Well-defined relationships between flow and density averaged spatially across urban traffic networks, more commonly known as Macroscopic Fundamental Diagrams (MFDs), have been recently verified to exist in reality. Researchers have proposed using MFDs to monitor the status of urban traffic networks and to inform the design of network-wide traffic control strategies. However, it is also well known that empirical MFDs are not easy to estimate in practice due to difficulties in obtaining the requisite data needed to construct them. Recent works have devised ways to estimate a network’s MFD using limited trajectory data that can be obtained from GPS-equipped mobile probe vehicles. These methods assume that the market penetration level of mobile probe vehicles is uniform across the entire set of OD pairs in the network; however, in reality the probe vehicle market penetration rate varies regionally within a network. When this variation is combined with the imbalance of probe trip lengths and travel times, the compound effects will further complicate the estimation of the MFD.To overcome this deficit, we propose a method to estimate a network’s MFD using mobile probe data when the market penetration rates are not necessarily the same across an entire network. This method relies on the determination of appropriate average probe penetration rates, which are weighted harmonic means using individual probe vehicle travel times and distances as the weights. The accuracy of this method is tested using synthetic data generated in the INTEGRATION micro-simulation environment by comparing the estimated MFDs to the ground truth MFD obtained using a 100% market penetration of probe vehicles. The results show that the weighted harmonic mean probe penetration rates outperform simple (arithmetic) average probe penetration rates, as expected. This especially holds true as the imbalance of demand and penetration level increases. Furthermore, as the probe penetration rates are generally not known, an algorithm to estimate the probe penetration rates of regional OD pairs is proposed. This algorithm links count data from sporadic fixed detectors in the network to information from probe vehicles that pass the detectors. The simulation results indicate that the proposed algorithm is very effective. Since the data needed to apply this algorithm are readily available and easy to collect, the proposed algorithm is practically feasible and offers a better approach for the estimation of the MFD using mobile probe data, which are becoming increasingly available in urban environments.     

传统燃油车的电动化改制方案研究

文章以前置后驱的传统燃油车改制为前置前驱的纯电动汽车案例,展开整车设计分析,在维持原型车的外形、长宽高、轴距和轮距等基本参数的基础上,提出了整车布置结构变化的改制设计方案,设定了电动车整车主要性能指标。在电动化设计中取消了传统燃油动力总成及其附属的燃油、进排气等系统,依据整车性能目标要求,结合车辆空间及整车结构原理,对驱动电机动力总成、电池PACK、VCU、PDC三合一等高压系统零部件进行选型及布置设计。     

Autonomous vehicles: scientometric and bibliometric review*

ABSTRACT

This paper presents a scientometric and bibliometric review of the research on autonomous vehicles (AVs) to identify its main characteristics, evolution, and potential trends for future studies. Relevant articles were searched on WoS, yielding a research corpus of 10,580 papers, and the software CiteSpace was subsequently used for analysis. The results showed that AV research is heterogeneous and registered a growing demand over time. Multidisciplinarity is present, with 96 science fields being identified. As in any other sector, it is necessary to understand broader aspects of this industry such as the market factors surrounding it, as well as other economic and managerial issues. In this sense, we observed a migration of the research field from multidisciplinarity to pluridisciplinarity with a greater number of studies focusing on the latter. We understand that terminology standardisation contributes to achieving pluridisciplinarity. As such, it is important to highlight that sustainability, public policies, liability, and safety, as well as business issues such as performance and business models are some of the tendencies in the field of AVs. For future studies, we suggest a more in-depth analysis of publications in terms of individual search terms, as well as the sub-areas identified as trends in this paper.