大客车车身骨架结构强度分析及其改进设计

在Un igraph ics软件中建立车身骨架的线框模型后,用自行编制的接口程序生成命令流文件将模型导入到ANSYS环境中,建立了车身骨架有限元模型。用有限元理论分析了静态工况下客车车身骨架的强度特性,探讨了承载式车身骨架不同部位的受力特性。提出了通过对骨架结构进行局部改进来提高整体结构强度的方法,提出了对原结构进行改进设计的方案,并对改进前后的客车进行了强度试验,验证了改进后结构的合理性和可靠性。     

基于RMA方法的汽车车身CAN总线优化设计

针对汽车车身控制信息的高实时性和车身CAN系统扩充的高灵活性等特殊要求,介绍用于实时系统分析的速率单调分析(RMA)方法,在原总线利用率、信息最坏响应时间等实时性指标基础上引入总线扩展灵活性因子进行车身CAN总线方案的寻优设计,并以典型汽车车身控制系统为例,对单信号方案和信号组合方案进行实时性和扩展灵活性对比分析,在线试验结果验证了理论分析数据的正确性。     

城市公交站交通冲突分析及对策

公交站是城市公交系统的重要组成部分,客流通过在公交站点上下车的方式实现了公交系统的日常运营.但在公交站往往因其在有限空间内集聚大量人流与车流产生交通冲突,对城市交通的顺畅及通达产生消极影响.本文分析了城市公交站主要交通冲突影响因素及其冲突成因,并针对一般停靠和港湾式停靠方式产生的交通冲途性提出了解决问题的对策与方法.     

兼顾冷却、降噪要求的后置客车冷却系统研究

为保证发动机冷却效果良好,且具有低噪声特性,围绕冷却系几个关键部位进行了降噪试验研究。进行了风扇的选型设计,对进风格栅、进风通道、后舱门进行了吸声降噪设计。采取措施后,客车的车外加速噪声下降了2～3dB(A),表明,兼顾冷却、降噪要求的该后置客车冷却系统设计可行。     

On incentives and optimal effort to improve bus transit performance

ABSTRACT

This paper studies incentive-based subsidy to transit systems to improve performance. It derives a formula for optimal effort that equalizes marginal cost and marginal benefit and derives some principles from it among which is that the larger the value of a transit system’s performance criterion the larger the effort it will exert to improve it. Next, using a constrained cost minimization approach it derives a nonlinear cost function that includes optimal effort and estimates it using an unbalanced panel data of single mode U.S. bus transit systems. The results show that optimal effort is the equivalent of seven full-time employees (15,243 labor hours) per year and in real terms it results in 0.6% cost saving (US$198,331) and US$836,796 in incentive subsidy per observation. The implications of these findings are examined.     

Optimization of bus stop placement for routes on uneven topography

The improvement and expansion of public transport is an increasingly important solution to the high congestion costs and worsening environmental impacts of the car dominated transport systems seen in many cities today. The intelligent design of stop locations is one way to improve the quality of PT and thereby improve its ridership. Stop placement is a relatively complex task as it involves a trade-off between two competing goals; accessibility and operation; however this trade-off can be made explicit using an appropriate mathematical model. Many such models have been developed in the literature, however none consider the effects of uneven topography. Topography is an important but often neglected factor in the design of public transportation systems, with the potential to have a significant impact on the accessibility, operation and planning of a transit service. In this work a mathematical modelling approach to bus stop placement is developed which includes considerations of uneven topography in three ways; (1) Its effect on walking speed; (2) Its impact on the attractiveness of an access path to a transit service; and (3) Its effect on acceleration rates at stops. Because of the complexity of the model developed, a heuristic evolutionary algorithm’ is employed to approximate an optimal solution to the model. Finally, the model and solution method are applied to a case study in the Auckland CBD area in New Zealand.     

铁路信号系统中以太网转CAN网关设计

设计一种适用于铁路信号系统的以太网转CAN网关设备,将PowerPC405EP作为主控处理器芯片,采用Linux操作系统,利用其自带的协议栈实现以太网通信功能,外扩SJA1000实现CAN总线数据收发功能。为了便于工程施工和现场快速配置,相关通信配置文件及应用程序均存储在外扩的CF卡中。另外,系统还配备了专用的监测以太网接口通道,设备开通运营后可将其工作状态和上下行的通信原始数据上传至监测计算机用于故障分析。     

国产在用客车高速行驶时存在的主要问题及对策

在对我国高速公路客车运输行驶状况进行大量统计与调研的基础上,分析了国产在用客车高速行驶时所存在的主要问题,并提出了相应的对策。统计结果表明,目前我国全封闭式高速公路的运输能力还未能得到充分发挥,其主要原因是国产在用客车动力性、行驶稳定性、高速制动性等性能较差,建议高速公路用客车的设计,应充分考虑其使用特点及主动安全性要求。     

重庆主城区公交优先道系统设置技术及实施方案

实施公交优先道是落实公共交通优先发展策略的重要措施。公交优先道建设工作是一项系统工程,本文结合重庆主城区实际情况,总结了公交优先道系统设置技术和实施方案,即"四个系统、一个平台",包含交通标志标线系统、交通违法抓拍系统、公交优先道信息系统、信号优先控制系统和综合信息平台,有效改善了主城区地面公交运行环境,同时提升了交通纠违工作效率。     

公交停靠站停靠时间特征分析

公交停靠站停靠时间的研究有着重要的实用价值。在分析影响公交停靠时间的各个因素后,根据实地调查数据统计分析各个影响因素对停靠时间的影响特征,并在此基础上提出减少公交停靠时间延误的对策。