Reducing car dependence in the heart of Europe: lessons from Germany,Austria, and Switzerland

Munich, Berlin, Hamburg, Vienna, and Zurich – the largest cities in Germany, Austria, and Switzerland – have significantly reduced the car share of trips over the past 25 years in spite of high motorisation rates. The key to their success has been a coordinated package of mutually reinforcing transport and land-use policies that have made car use slower, less convenient, and more costly, while increasing the safety, convenience, and feasibility of walking, cycling, and public transport. The mix of policies implemented in each city has been somewhat different. The German cities have done far more to promote cycling, while Zurich and Vienna offer more public transport service per capita at lower fares. All five of the cities have implemented roughly the same policies to promote walking, foster compact mixed-use development, and discourage car use. Of the car-restrictive policies, parking management has been by far the most important. The five case study cities demonstrate that it is possible to reduce car dependence even in affluent societies with high levels of car ownership and high expectations for quality of travel.     

Weather and road geometry impact on longitudinal driving behavior: Exploratory analysis using an empirically supported acceleration modeling framework

The objective of this paper is to quantify and characterize driver behavior under different roadway geometries and weather conditions. In order to explore how a driver perceives the rapidly changing driving surrounding (i.e. different weather conditions and road geometry configurations) and executes acceleration maneuvers accordingly, this paper extends a Prospect Theory based acceleration modeling framework. A driving simulator is utilized to conduct 76 driving experiments. Foggy weather, icy and wet roadway surfaces, horizontal and vertical curves, and different lane and shoulder widths are simulated while having participants driving behind a yellow cab at speeds/headways of their choice. After studying the driving trends observed in the different driving experiments, the extended Prospect Theory based acceleration model is calibrated using the produced trajectory data. The extended Prospect Theory based model parameters are able to reflect a change in risk-perception and acceleration maneuvering when receiving different parameterized exogenous information. The results indicate that drivers invest more attention and effort to deal with the roadway challenges compared to the effort to deal with the weather conditions. Moreover, the calibrated model is used to simulate a highway segment and observe the produced fundamental diagram. The preliminary results suggest that the model is capable of capturing driver behavior under different roadway and weather conditions leading to changes in capacity and traffic disruptions.     

基于ADAMS/Car弹性运动学对整车分析的影响

ADAMS软件提供了柔性体模块,可真实地模拟物体的运动,文章以某轿车为研究对象,利用ADAMS仿真软件建立了带有弹性下控制臂悬架的整车模型。选择开环转向事件里的转向阶跃输入进行仿真分析,在后处理中对横摆角速度、车速、侧向加速度和纵向加速度进行分析。结果表明,柔性体悬架模型比多刚体悬架模型对车身的横摆角速度、侧向加速度、纵向加速度以及速度等具有更好的抑制作用,有利于提高汽车操纵稳定性。     

27t轴重通用货车应用下调车场连挂区调速控制研究

27 t轴重通用货车的应用给调车场连挂区调速控制提出了新问题。分析27 t轴重通用货车单位基本阻力更小、溜放动能更大等特点,减速顶对27 t轴重通用货车制动功的减小、临界制动速度的上浮等特性,以及与既有货车混合应用后超速连挂风险的增加、调速控制复杂性的增大等问题。通过模型建立、参数标定及仿真计算,得到减速顶对27 t轴重通用货车制动功的减幅及临界制动速度的漂移量。为解决27 t轴重与既有货车混合应用下调车场连挂区调速控制问题,提出3种调速控制方案,仿真计算显示,在满足27 t轴重通用货车调速控制、难行车不利溜放、最短溜放距离等约束下,增加布顶与调整坡度相结合的方案最优。     

轿车发动机机械损失的降低

机械损失对现代车用发动机燃料经济性的影响很大，轿车发动机因为其经常在很小的负荷率下运行，故障低机构损失的对改善其油耗和排放将更大的效果，分析了轿车发动机基本参数，零部件设计等对摩擦损失的影响，提出了降低其机械损失的若干措施。     

轿车空调微机控制系统研究

本文介绍了一般轿车空调器针对舒适性要求所采用的控制方式和手段，并制作了以通用汽车公司某型轿车为实验对象的单片机控制系统，同时对控制策略作了深入研究，为轿车空调热舒适性控制提供一些方法。     

基于离散元-有限元耦合法的煤炭漏斗车装卸过程中隔板受力研究

在煤炭漏斗车标准和设计技术条件中均未规定隔板强度,漏斗车车体设计静强度计算中,未施加相应载荷进行设计验证。同时,某型号煤炭漏斗车在应用中出现隔板裂纹。为此,基于离散元-有限元(DEM-FEM)结合的方法,模拟煤炭漏斗车装卸煤炭过程,分析煤炭漏斗车车体隔板受力和强度仿真计算结果,并与煤炭漏斗车车体隔板现场测试强度结果进行对比。结果表明:装载煤炭过程中,隔板所受最大载荷大约为稳定时载荷的1.8倍;卸载煤炭过程受不同底门开启的影响,隔板所受载荷瞬间突增80%~112.6%。装卸过程中隔板所受作用力与高度之间呈非线性分布,仿真计算结果与现场测试数据基本吻合。这为设计煤炭漏斗车车体隔板时提供参考。     

轿车后副车架多轴疲劳分析

以某轿车五连杆独立后悬架的副车架为研究对象,根据台架试验方法建立了后悬架系统有限元模型,利用虚拟应变片技术和焊缝寿命预测技术,通过CAE分析与台架试验测试相结合,通过改进结构降低裂纹位置的疲劳损伤值,解决了该后副车架在台架试验中焊接位置出现裂纹的问题.改进结构一次性通过了8通道耐久性台架试验,表明有限元分析与台架试验相结合的方法可有效预测副车架焊缝疲劳寿命.     

宝来1.8T轿车独立点火线圈检测方法

一汽-大众宝来1.8T轿车点火系统采用独立式点火线圈,其故障是该款轿车点火系统常见的主要故障。详细介绍了独立点火线圈故障的诊断方法,即一般首先进行自诊断故障信息的检测以提取故障码,初步确定故障范围,然后检测点火系统主要的功能部件以最终确定故障。给出了应用所介绍的检测方法进行检测的具体实例。     

基于人-车-路虚拟试验的道路线形安全性评价

为了避免由于线形设计不良造成日后事故多发路段的产生,提出了基于人-车-路虚拟试验的道路线形设计安全性评价方法。首先基于对公路线形导致交通事故的分析,选取并构造了轨道跟踪误差、转向任务间隔、方向盘峰值转速、侧向加速度、垂直荷载和路段通行极限车速为道路线形安全性评价指标;采用EICAD和多体动力学软件ADAMS/Car实现了道路设计方案的三维建模,然后与车辆模型、驾驶员模型构成仿真环境完成了对安徽至浙江某高速公路线形设计方案的安全性评价;多数评价指标显示该设计路线安全性较好,但路段通行极限车速显示该路段前段(里程0~2.47 km)行车速度分布较分散,容易诱发超速行驶,为潜在的事故多发路段。