气缸压力及其与空燃比、转速的关系研究

对 4缸汽油机的各缸压力、曲轴转速、空燃比进行了同时测量 ,由测量得到的压力分析了 4缸汽油机气缸间平均指示压力的差异以及平均指示压力、最高燃烧压力、最高燃烧压力所在曲轴转角三者的关系。采用统计分析方法研究了平均指示压力与测量得到的循环平均曲轴转速、循环平均空燃比之间的关系。试验结果表明汽油机不同气缸的平均指示压力存在偏差 ,其偏差率可达± 5 % ;气缸最高压力与最高压力所在曲轴转角之间有较强的相关 ,但平均指示压力与循环平均空燃比和循环平均转速是不相关的     

基于分类管理的汽车制造业供应商评价与选择方法

针对汽车制造业零部件数量大、种类多及差别大的特点,结合零部件在整车中的地位和作用,提出将零部件按重要程度分类的思想,并给出具体的分类指标,在此基础上建立汽车制造业供应商评价与选择程序模型。重点阐述了一级零部件的评选策略,并对现有的各种评价方法的优缺点进行了比较,为汽车制造业对零部件供应商的评价与选择提供了依据。     

基于双波比较的汽车AMT电机测速方法

针对霍尔元件测速方法在测量汽车AMT电机转速时转速波形存在较大周期偏差的问题,在分析影响周期偏差主要因素的基础上,提出了采用线性霍尔元件结合双波比较的新方法。该测速方法有效地减小了转速正弦波的中轴波动对比较器输出矩形波周期的影响,从而有效减少了输出转速矩形波的周期偏差,提高了转速测量精度。试验证明,该方法具有测量精度高、实现成本低和可用于大范围电机转速测量的特点。     

行驶质量评价指标的回顾和展望

道路作为满足公众行驶需要的一种特殊产品,其好坏的根本量度之一就是行驶质量评价指标。由于这个指标取决于道路的破损情况,因此将其与道路表面的粗糙度特征建立回归关系才方便应用。自从20世纪60年代以来,确定行驶质量指标的主要参数就不断演变。先是人工实测车辙,破损及修补面积,再是各种仪器实测的路面平整度,比如国际平整度指数,IRI。本文在大量的研究基础上,指出了现行主要参数的不足,并提出了一个确定行驶质量指标的新参数,既乘客所直接感受到的竖直方向上的加速度的变化率,JERK。     

车轮速度传感器的构造与维护

车轮速度传感器的作用是将车轮的转变为电压信号，输送给电子控制系统（ＥＣＵ），并发出相应的指令。介绍了车轮速度传感器的构造、工作原理、维护与检测。     

浅谈摊铺机的恒速摊铺

路面平整度是评价路面质量的重要指标之一,摊铺机的摊铺速度对平整度有很大影响.文章分析了摊铺机速度与平整度的关系以及影响摊铺机速度变化的因素.并给出了控制影响因素的办法.     

非接触车速仪车速误差的分析及采样时间的自适应调节

通过对车速仪测量速度的数学模型的建立，分析了动态情况下速度采样时间、距离脉冲当量与速度误差的关系，给出了速度误差的计算公式，提出了用采样时间的自适应调节，提高动态测量精度及具体应用的方法。还对各工况下的速度采样时间及误差进行了计算和比对。     

Measuring Truck Travel Time Reliability Using Truck Probe GPS Data

Truck probe data collected by global positioning system (GPS) devices has gained increased attention as a source of truck mobility data, including measuring truck travel time reliability. Most reliability studies that apply GPS data are based on travel time observations retrieved from GPS data. The major challenges to using GPS data are small, nonrandom observation sets and low reading frequency. In contrast, using GPS spot speed (instantaneous speed recorded by GPS devices) directly can address these concerns. However, a recently introduced GPS spot-speed-based reliability metric that uses speed distribution does not provide a numerical value that would allow for a quantitative evaluation. In light of this, the research described in this article improves the current GPS spot speed distribution-based reliability approach by calculating the speed distribution coefficient of variation. An empirical investigation of truck travel time reliability on Interstate 5 in Seattle, WA, is performed. In addition, correlations are provided between the improved approach and a number of commonly used reliability measures. The reliability measures are not highly correlated, demonstrating that different measures provide different conclusions for the same underlying data and traffic conditions. The advantages and disadvantages of each measure are discussed and recommendations of the appropriate measures for different applications are presented.     

Performance Evaluation of Handoff-Based Cellular Traffic Monitoring Systems Using Combined Wireless and Traffic Simulation Platform

Handoff-based cellular probe technologies have been proven to be a cost-effective solution for traffic surveillance due to their low cost, large sample size, and intensive spatial coverage. At the same time, the development of reliable simulation tools that can be used to conduct a feasibility study, performance evaluation, and estimation model testing for cellular probe technologies, especially in the arterial environment, is still limited. In this study, by simulating the real-world signal delaying and wireless signal communication protocols, we establish a simulation platform for evaluating cellular probe system. The simulation platform eliminates unrealistic assumption on static and regular cell boundaries in the existing simulation tools and can provide simulation results similar to field observations. Based on the platform, we compared the performance of cellular probe system under both freeway and arterial environment. We analyzed the impact of traffic conditions, the duration of cellphone calls, and penetration rate on the handoff efficiency, handoff link speed error, and information-disseminating link speed estimation error. In addition, we also provide a detailed evaluation of the accuracy of the intersection delay estimation and the potential error sources and mechanism. The results show that the handoff-based cellular probe technologies attain good performance in traffic monitoring and the proposed simulation platform can reflect the real-world condition on an acceptable level.