Improving fuel consumption and CO2 emissions calculations in urban areas by coupling a dynamic micro traffic model with an instantaneous emissions model

Τhis study demonstrates the combination of a microscopic traffic simulator (AIMSUN) with an instantaneous emissions model (AVL CRUISE) to investigate the impact of traffic congestion on fuel consumption on an urban arterial road. The micro traffic model was enhanced by an improved car-following law according to Morello et al. (2014) and was calibrated to replicate measured driving patterns over an urban corridor in Turin, Italy, operating under adaptive urban traffic control (UTC). The method was implemented to study the impact of congestion on fuel consumption for the category of Euro 5 diesel <1.4 l passenger cars. Free flow and congested conditions led to respective consumption differences of −25.8% and 20.9% over normal traffic. COPERT 5 rather well predicted the impact of congestion but resulted to a much lower relative reduction in free flow conditions. Start and stop system was estimated to reduce consumption by 6% and 11.9% under normal and congested conditions, respectively. Using the same modelling approach, UTC was found to have a positive impact on CO₂ emissions of 8.1% and 4.5% for normal and congested conditions, respectively, considering the Turin vehicle fleet mix for the year 2013. Overall, the study demonstrates that the combination of detailed and validated micro traffic and emissions models offers a powerful combination to study traffic and powertrain impacts on greenhouse gas and fuel consumption of on road vehicles over a city network.     

Electric vehicles: How much range is required for a day’s driving?

One full year of high-resolution driving data from 484 instrumented gasoline vehicles in the US is used to analyze daily driving patterns, and from those infer the range requirements of electric vehicles (EVs). We conservatively assume that EV drivers would not change their current gasoline-fueled driving patterns and that they would charge only once daily, typically at home overnight. Next, the market is segmented into those drivers for whom a limited-range vehicle would meet every day’s range need, and those who could meet their daily range need only if they make adaptations on some days. Adaptations, for example, could mean they have to either recharge during the day, borrow a liquid-fueled vehicle, or save some errands for the subsequent day. From this analysis, with the stated assumptions, we infer the potential market share for limited-range vehicles. For example, we find that 9% of the vehicles in the sample never exceeded 100 miles in one day, and 21% never exceeded 150 miles in one day. These drivers presumably could substitute a limited-range vehicle, like electric vehicles now on the market, for their current gasoline vehicle without any adaptation in their driving at all. For drivers who are willing to make adaptations on 2 days a year, the same 100 mile range EV would meet the needs of 17% of drivers, and if they are willing to adapt every other month (six times a year), it would work for 32% of drivers. Thus, it appears that even modest electric vehicles with today’s limited battery range, if marketed correctly to segments with appropriate driving behavior, comprise a large enough market for substantial vehicle sales. An additional analysis examines driving versus parking by time of day. On the average weekday at 5 pm, only 15% of the vehicles in the sample are on the road; at no time during the year are fewer than 75% of vehicles parked. Also, because the return trip home is widely spread in time, even if all cars plug in and begin charging immediately when they arrive home and park, the increased demand on the electric system is less problematic than prior analyses have suggested.     

车辆焊接结构疲劳寿命评估方法研究

为在设计阶段实现车辆焊接结构的抗疲劳设计,在研究AAR/BS/IIW标准的疲劳算法原理和焊接接头疲劳性能参数的基础上,给出基于AAR/BS/IIW标准进行车辆焊接结构疲劳寿命评估的方法和技术路线。依据AAR标准分析某公司出口的全钢焊接结构矿石车车体的疲劳寿命,结果表明:该出口矿石车车体焊接结构的最短疲劳寿命发生在中部横梁腹板与横梁下盖板角接焊接区,寿命年限为59.4年,满足25年设计寿命的要求;通过与IIW标准中提供的焊接接头结构的对比分析,提出对某提速客车转向架焊接构架的定位座根部焊接结构进行打磨的改进方案。数据表明:改进方案明显提高了定位座根部焊接接头的寿命。经对比分析可以看出,基于IIW标准的焊接构架疲劳寿命预测结果与疲劳试验结果比较接近。     

浅析桥头跳车的成因与防治

从分析桥头跳车的成因出发,对有代表性的几种防治方法进行粗浅的探讨。     

汽车驾驶人机系统目标评价树的建立及应用

以汽车安全行驶概率为评价目标,列举与之相关的驾驶员、汽车、环境3方面因素,分析因素间关系,确定重要因素并赋予权重,建立汽车驾驶人机系统目标评价树。介绍了该目标评价树的使用方法与适用范围。对哈尔滨市两个事故多发地段的驾驶环境进行评价和改进,取得预期效果。     

基于主动转向技术的汽车防侧翻控制的研究

以汽车2自由度模型作为参考模型，建立了一种汽车防侧翻的控制方法。该方法采用主动转向技术来改变转向轮的转向角度，有效地减少了汽车的侧向加速度，提高了汽车的防侧翻的能力。在8自山度汽车动力学模型的基础上，运用主动转向技术的控制策略进行了汽车的性能仿真分析。与末采用汽车防侧翻控制系统的汽车动力学分析结果相比，汽车的主动安全性得到了增强。     

汽车排气系统脉动强化传热机理研究

为探索高温尾气、受热零部件和外部环境及相应物理场间的耦合关系,建立汽车排气系统内外流固耦合传热模型,并对模型及数值方法进行验证。数值试验表明,内流速度与温度的脉动都会使对流传热系数增大,且随着速度和温度脉动振幅的增长,传热近似呈2次函数关系增长,温度的脉动对强化传热效果更好。同时,提出了一种稳态速度等效法来预测发动机尾气脉动的强化传热效果,该方法也可以应用于排气系统的热应力及其变形的计算上。     

车辆随机输入的动态仿真和试验研究

按汽车行驶平顺性评价方法，应用MATLAB工具箱编制了针对五自由度汽车模型的随机输入动态仿真程序，通过仿真可直接获得给定测点的加权加速度均方根值分量的最大值和总加权加速度均方根值，仿真结果与随机输入行驶试验结果基本吻合，证明仿真方法是正确的，该程序可用于汽车悬架系统参数的设计和平顺性的评估。