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161.
分析简单混联式混合动力客车动力系统的结构;基于混合动态系统理论制定能量管理策略,并且通过仿真将该方案与原车进行比较.仿真结果表明,采用该方案的车辆动力性有所改善,燃油经济性有显著提高. 相似文献
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Xinkai WuHenry X. Liu 《Transportation Research Part B: Methodological》2011,45(10):1768-1786
In this paper a new traffic flow model for congested arterial networks, named shockwave profile model (SPM), is presented. Taking advantage of the fact that traffic states within a congested link can be simplified as free-flow, saturated, and jammed conditions, SPM simulates traffic dynamics by analytically deriving the trajectories of four major shockwaves: queuing, discharge, departure, and compression waves. Unlike conventional macroscopic models, in which space is often discretized into small cells for numerical solutions, SPM treats each homogeneous road segment with constant capacity as a section; and the queuing dynamics within each section are described by tracing the shockwave fronts. SPM is particularly suitable for simulating traffic flow on congested signalized arterials especially with queue spillover problems, where the steady-state periodic pattern of queue build-up and dissipation process may break down. Depending on when and where spillover occurs along a signalized arterial, a large number of queuing patterns may be possible. Therefore it becomes difficult to apply the conventional approach directly to track shockwave fronts. To overcome this difficulty, a novel approach is proposed as part of the SPM, in which queue spillover is treated as either extending a red phase or creating new smaller cycles, so that the analytical solutions for tracing the shockwave fronts can be easily applied. Since only the essential features of arterial traffic flow, i.e., queue build-up and dissipation, are considered, SPM significantly reduces the computational load and improves the numerical efficiency. We further validated SPM using real-world traffic signal data collected from a major arterial in the Twin Cities. The results clearly demonstrate the effectiveness and accuracy of the model. We expect that in the future this model can be applied in a number of real-time applications such as arterial performance prediction and signal optimization. 相似文献
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Xuegang Ban Peng Hao Zhanbo Sun 《Transportation Research Part C: Emerging Technologies》2011,19(6):1133-1156
We study how to estimate real time queue lengths at signalized intersections using intersection travel times collected from mobile traffic sensors. The estimation is based on the observation that critical pattern changes of intersection travel times or delays, such as the discontinuities (i.e., sudden and dramatic increases in travel times) and non-smoothness (i.e., changes of slopes of travel times), indicate signal timing or queue length changes. By detecting these critical points in intersection travel times or delays, the real time queue length can be re-constructed. We first introduce the concept of Queue Rear No-delay Arrival Time which is related to the non-smoothness of queuing delay patterns and queue length changes. We then show how measured intersection travel times from mobile sensors can be processed to generate sample vehicle queuing delays. Under the uniform arrival assumption, the queuing delays reduce linearly within a cycle. The delay pattern can be estimated by a linear fitting method using sample queuing delays. Queue Rear No-delay Arrival Time can then be obtained from the delay pattern, and be used to estimate the maximum and minimum queue lengths of a cycle, based on which the real-time queue length curve can also be constructed. The model and algorithm are tested in a field experiment and in simulation. 相似文献
167.
隧道路面类型选择及调查研究 总被引:1,自引:0,他引:1
采用理论分析和实际调查相结合的方法分析了隧道内温度、湿度、噪声、基础强度、交通条件等对隧道路面类型选择影响.为了选择舒适、安全、耐久的隧道路面类型,基于灰靶分析理论从路面整体强度、耐久性、平整度、抗滑性能、耐磨性能及修复难易程度六个方面对沥青和水泥两种路面进行综合评价.结果表明沥青路面在隧道中具有更好的适用性.经对近百座隧道路面实地调查,验证了理论分析的正确性.随着施工、阻燃等技术进步,沥青路面将逐渐取代水泥路面在隧道内得到广泛应用. 相似文献
168.
应用应变梯度塑性理论构建了微切削第一变形区的力学模型,在此力学模型的基础上提出了第一变形区几何尺寸的分析预测方法和影响因素,得出当材料的内禀长度l越小,即材料相对均匀时,第一变形区厚度赿小.当切削厚度增大时,第一变形区的长度增大.设计了正交切削实验来验证模型的有效性,实验结果表明随着进给量的增大,第一变形区厚度减小而第一变形区的长度反而增大. 相似文献
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城市公共交通是城市可持续发展的必由之路,对城市交通具有重大意义.本文从公交车的运行特点入手,用数学方法描述公交车从发车到到站的运行过程,建立公交车到站模型,并利用简化模型分析公交站台车辆到站规律,计算车辆到站频次.最后,利用排队理论建立公交站台服务水平的计算模型.运用排队论模型对北京市某公交站台进行评价,证明对站点设置位置和停靠模式以及站台的线路数和线路发车频率的合理设置,可以有效地控制站台内公交车的排队情况,提高公交站台的运行效率,缓解交通拥堵. 相似文献
170.
曾小玲 《广州航海高等专科学校学报》2011,19(1):60-62
在教育模式从以教师为中心转化到以学生为中心的过程中,人们似乎忽略师生间的互动的重要性.以大学英语课堂为例,论述了良好的师生关系不仅有益于教师与学生,还有益于整个英语教学教育的效果和质量的提高.本文还探讨了在大学英语课堂中建立良好的师生互动关系的途径. 相似文献