青藏铁路客车沿程需氧量仿真研究

为研究和改进青藏铁路旅客列车供氧系统,以格尔木一拉萨段青藏铁路旅客列车为例,采用集总参数法建立列车内部含氧量变化的动态数学模型,运用MATLAB软件的SimuLink工具对车内含氧量进行仿真,分别得到不供氧和以13.7 kPa氧分压持续供氧情况下的列车内外氧含量变化曲线,以及沿程最低需氧量和累计的最低需氧量总和.将这些结果与基于稳态的供氧量工程实用表达式的计算结果进行比较,经分析得知,只需将工程实用式稍加修正,两者结果就会非常吻合.这说明用修正后的工程实用式代替动态法计算客车需氧量简便可行.     

盘形制动是城市轨道车辆基础制动装置的发展趋势

基础制动装置是确保城市轨道交通车辆行车安全的措施之一。在分析城市轨道车辆运输特点基础上,结合城市轨道车辆基础制动装置具体类型,分析了城市轨道车辆踏面制动与盘形制动的优缺点,用有限元模拟城轨车辆车轮踏面温度场及热应力,表明速度100 km/h及以上的城轨列车基础制动不适宜采用踏面制动,指出盘形制动是城市轨道交通车辆基础制动的发展的必然趋势。     

斜拉桥在考虑风效应时的车-桥耦合振动

以芜湖长江大桥为算例,考虑风荷载作用于列车和桥梁上,对ICE高速列车以200km/h的速度通过桥梁时,计算了与列车运行安全性及旅客乘座舒适度相关的指标.风荷载考虑为脉动的,按Simiu谱用MonteCarlo法模拟脉动风速,结合由风洞试验测定的空气动力参数,计算了作用于列车和桥梁上的自然风荷载.根据结构动力学理论,建立了机车(车辆)的动力学方程;建立了桥梁的有限元振动方程;桥上轨道不平顺按6级线路(最好的线路)模拟.计算结果表明,对芜湖长江大桥,桥上允许行车的桥面处横桥向最大风速应小于30m/s.     

DC01型电动列车辅助逆变器控制器及应急起动功能的改善

上海轨道交通1号线DC01型直流传动车辆在运行中因蓄电池应急供电后电压跌落,造成辅助逆变器起动失效,从而导致车辆丧失运营能力。在分析DC01型电动列车辅助逆变器控制器构成和功能的基础上,讨论了产生该故障的原因。通过提高动作保护电流的限界值、实施智能式分级起动控制方案等措施可改善控制器的性能。     

中国汽车出口东盟市场面对的挑战及对策分析

随着时代的发展,汽车贸易出口也在逐步的增加,中国汽车的国际市场实力不容小觑.为了使中国的汽车走出国门,积极地参与竞争,就必须顺应时代的发展,拓展市场宽度.     

邻里合乘——社区拼车常态化的探索

为了促进邻里合乘社区拼车模式不断完善以及有效推广实践、实现社区拼车常态化发展,在分析我国拼车发展现状与困境的基础上,探讨了邻里合乘社区拼车的创新理念,包括社区组织、法律支持、签订协议、社会参与四个方面。针对存在的拼车协议缺陷、拼车对象受限难推广的局限,提出邻里合乘的发展建议：扩大活动影响,寻求政策支持,从根本上突破法律等制度的困境;建立由政府支持的社区拼车试点计划,逐步将社区拼车模式推广,最终实现社区全民拼车的常态化。     

编组站货车信息管理系统的应用与思考

针对编组站货车管理系统的需求特点和存在的问题,结合当前计算机发展趋势,探讨了编组站货车管理信息系统中各子系统之间的信息共享和系统整合方案,论文以YIS在襄樊北编组站的实际应用为背景,详细研究了提高信息利用效率、优化统计分析、规范故障处理的途径和技术措施,提出了充分发挥各子系统潜能、更好地为编组站运输生产服务的方案.     

Impact of heavy vehicles on surrounding traffic characteristics

This work examines the impact of heavy vehicle movements on measured traffic characteristics in detail. Although the number of heavy vehicles within the traffic stream is only a small percentage, their impact is prominent. Heavy vehicles impose physical and psychological effects on surrounding traffic flow because of their length and size (physical) and acceleration/deceleration (operational) characteristics. The objective of this work is to investigate the differences in traffic characteristics in the vicinity of heavy vehicles and passenger cars. The analysis focuses on heavy traffic conditions (level of service E) using a trajectory data of highway I‐80 in California. The results show that larger front and rear space gaps exist for heavy vehicles compared with passenger cars. This may be because of the limitations in manoeuvrability of heavy vehicles and the safety concerns of the rear vehicle drivers, respectively. In addition, heavy vehicle drivers mainly keep a constant speed and do not change their speed frequently. This work also examines the impact of heavy vehicles on their surrounding traffic in terms of average travel time and number of lane changing manoeuvres using Advanced Interactive Microscopic Simulator for Urban and Non‐Urban Networks (AIMSUN) microscopic traffic simulation package. According to the results, the average travel time increases when proportion of heavy vehicles rises in each lane. To reflect the impact of heavy vehicles on average travel time, a term related to heavy vehicle percentage is introduced into two different travel time equations, Bureau of Public Roads and Akçelik's travel time equations. The results show that using an exclusive term for heavy vehicles can better estimate the travel times for more than 10%. Finally, number of passenger car lane changing manoeuvres per lane will be more frequent when more heavy vehicles exist in that lane. The influence of heavy vehicles on the number of passenger car lane changing is intensified in higher traffic densities and higher percentage of heavy vehicles. Large numbers of lane changing manoeuvres can increase the number of traffic accidents and potentially reduce traffic safety. The results show an increase of 5% in the likelihood of accidents, when percentage of heavy vehicles increases to 30% of total traffic. Copyright © 2014 John Wiley & Sons, Ltd.     

The impact of fuel availability on demand for alternative-fuel vehicles

We study the impact of fuel availability on demand for alternative-fuel vehicles, using data from a survey of potential car buyers in Germany. The survey was conducted as a computer-assisted personal interview and included a choice experiment involving cars with various fuel types. Applying a standard logit model, we show that alternative fuel availability influences choices positively, but its marginal utility diminishes with supply. Furthermore, we derive consumers’ marginal willingness-to-pay for an expanded service station network. The results suggest that a failure to expand the availability of alternative fuel stations represents a significant barrier to the widespread adoption of alternative-fuel vehicles.     

基于尾号空间分布的小汽车限行方案优化研究

提出根据各尾号小汽车空间分布特征计算尾号出行OD矩阵的方法,基于公平性原则,构建尾号限行方案优化模型.上层模型以工作日(周一~周五)车辆总走行时间最小为目标,以各工作日每辆小汽车早高峰平均走行时间基本相同且每周各尾号限行次数不大于1为约束,给出限号方案;下层模型基于用户均衡原则分配OD交通量.限号方案与分配结果相互作用,达到均衡状态时可得最优限号组合方案.为验证模型,以D市为例进行实证研究,结果表明,与基于经验的限号方案相比,优化方案下路网通行效率可提高5.35%,工作日车辆总走行时间降低0.894×105h,日均单车走行时间减少4.5 min.