Light duty gasoline vehicle emission factors at high transient and constant speeds for short road segments

Vehicle emissions estimates are needed at high spatial and temporal resolution to estimate near-roadway air quality and human exposures. The MOBILE6 emission factor model is based on transient test cycles of less than 65 mph. Correction factors for high speed and constant speed are developed based on vehicle-specific power-based modal models for light duty gasoline vehicles, using data from portable emission measurement systems. At 80 mph versus 65 mph, the estimated average emission rates are greater by 30%, 20%, 80%, and 10% for NO_x, HC, CO, and CO₂. The ratio of constant to average of transient speed emission rates range from 0.49 to 0.94 for NO_x at speeds of 20 mph and 80 mph. The high speed and constant speed correction factors are applied to estimate vehicle emissions for a freeway segment that includes vehicle cruising speeds between 65 and 80 mph. The potential error for not accounting for constant speed operation on a short segment of highway could be 49% at moderate speed and 24% at high speed.     

盾构下穿越已运营隧道的地表变形实测分析

文章基于盾构理论依据,结合上海市轨道交通7号线沪南路-白杨路区间隧道监测实际,对双线盾构下穿越已运营隧道施工引起的地表变形规律进行了探讨,分析盾构隧道下穿越施工引起土体移动的影响因素,为今后同类工程的设计与施工提供参考。     

多工况机械的复合调速系统

以高位垃圾车后部进料机构为例,阐述了一种复合调速系统,此系统与多工况机械之间具有良好的匹配性和自动跟随性,机械在多种工况变化过程中可以自动实现"要快即快、要慢即慢"的作业效果.该系统体积小、集成度高、可靠性好,通过速度可变量调节,实现宽调速范围特性,系统拓展应用性好,为专用汽车多工况机械装置的设计提供了一种调速控制方法...     

GB 14023《车辆、船和由内燃机驱动的装置无线电骚扰特性限值和测量方法》2006版与2000版的差异

主要分析国家标准GB14023《车辆、船和由内燃机驱动的装置无线电骚扰特性限值和测量方法》2006版与2000版在技术内容上的差异。     

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.     

基于试验场道路的变速器台架载荷谱研究

通过实车采集试验样车在试验场道路上行驶时的CAN BUS数据,可直接获得发动机转速、扭矩和档位等信号;把传统的载荷-时间频次关系,转变为载荷-发动机飞轮旋转频次关系,同时记录各载荷等级对应的各个挡位的频次,这样可获得在各个档位下,不同载荷等级对应转速区间内的飞轮旋转频次,根据齿轮材料的S-N曲线和疲劳累积Miner理论,计算出各档位的疲劳强度,然后基本疲劳损伤等效原理选取各档位下产生较大疲劳强度的扭矩和转速,作为台架试验输入的载荷和转速,可有效避免载荷和转速选取的盲目性,为科学的制定台架试验载荷谱提供了依据。     

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.     

驾驶员前视行为特性的动态变化规律

为了准确描述驾驶员前视预瞄行为随车速及道路曲率动态变化的特性,文章开展了在不同道路曲率和车速下的驾驶员前视距离实车场地试验测试,建立了车速-道路曲率-驾驶员前视时间的关系曲线,并将其应用于人-车-路闭环仿真中,进一步提高了驾驶员方向控制模型与真实驾驶员操纵行为的一致性.     

纯电动汽车驱动系统设计理论与应用

以电动汽车为代表的代用燃料汽车是人类解决大气污染和能源短缺危机的主要途径。文章以汽车行驶动力学为理论依据,与企业生产实际相结合,在满足国家标准对纯电动汽车动力性能要求的前提下,对驱动电机、减速器及动力电池等重要零部件的参数进行选择匹配设计;同时也根据纯电动汽车驱动系统各主要零部件的技术参数,计算整车动力性能指标。为企业纯电动汽车驱动系统的研发提供了一种有效的方法和手段。     

大型油船航速估算方法

对现有的船舶航速估算方法分析比较，提出了大型油船的航速估算方法。其中有效功率估算是根据上海船研所肥大船系试验图谱和实船试验资料经分析、修正得出，与荷兰Ｈｏｌｔｒｏｐ法、大连造船厂法比较，本文方法均方差最小，估算值与试验值最接近；自航因子估算以ＳＳＰＡ大油轮系列自航试验资料为基础，用上海船研所大量肥大船模型自航试验数据修正得出。