Bus travel time modelling using GPS probe and smart card data: A probabilistic approach considering link travel time and station dwell time

Abstract

Path travel time estimation for buses is critical to public transit operation and passenger information system. State-of-the-art methods for estimating path travel time are usually focused on single vehicle with a limited number of road segments, thereby neglecting the interaction among multiple buses, boarding behavior, and traffic flow. This study models path travel time for buses considering link travel time and station dwell time. First, we fit link travel time to shifted lognormal distributions as in previous studies. Then, we propose a probabilistic model to capture interactions among buses in the bus bay as a first-in-first-out queue, with every bus sharing the same set of behaviors: queuing to enter the bus bay, loading/unloading passengers, and merging into traffic flow on the main road. Finally, path travel time distribution is estimated by statistically summarizing link travel time distributions and station dwell time distributions. The path travel time of a bus line in Hangzhou is analyzed to validate the effectiveness of the proposed model. Results show that the model-based estimated path travel time distribution resembles the observed distribution well. Based on the calculation of path travel time, link travel time reliability is identified as the main factor affecting path travel time reliability.     

基于电化学热耦合模型的电动汽车电池模组热特性研究

为研究电池组的排列与布置方式对电池热特性的影响,本文中以18650锂离子电池为研究对象,建立了单体电池的电化学热力学耦合模型。利用模型仿真和实验测量获得了不同放电倍率时的电池表面温度随放电容量的变化关系,实验数据与仿真数据基本吻合,模型准确。基于单体耦合模型,分析了6×5动力电池模组的不同排列与布置方式下的热特性。结果表明:间距太小或太大均会使平均温度增加,本案例电池间距24 mm时平均温度最低;间距越大,温差越小,温度分布均匀性越好;间距一定,交叉排列散热效果优于对齐排列,且空间利用率更高。电池的排列和间距对电池散热有重要影响,锂离子动力电池组设计过程中应充分考虑。     

无车日与城市轨道交通

本文通过对无车日产生的背景介绍及其引发的思考，议论城市未来交通的发展，比较轨道交通的优势和发展潜力，得出大城市必须大力发展轨道交通的结论。     

整孔双线简支箱梁运输控制因素及工程措施和工期计算

结合京沪高速铁路制梁场设计以及京津、武广客运专线等先后开工建设的实践经验，较为系统地阐述了整孔双线简支箱梁在运输通道上的控制因素和解决的工程措施，并且提出了运梁工期的计算方法。此文论述的内容可对高速铁路及客运专线施工组织设计提供经验和指导。     

平稳性指标W和加权加速度Aw不能相互换算的分析

对TB/T2360—93《铁道机车动力学性能试验鉴定方法及评定标准》附录C3中平稳性指标W和加权加速度Aw的换算公式进行了分析，从平稳性指标W和加权加速度有效值Aw定义分析了二者的关系，结果表明平稳性指标W和加权加速度Aw不能相互换算，W和Aw没有相关性，需分别通过计算获得。     

基于LES方法圆柱绕流三维数值模拟(英文)

采用计算流体软件CFX5中large.eddy simulation(LES)模型计算了均匀流场中三维圆柱绕流的水动力特性.使用有限体积法对三维N-S方程进行求解.数值模拟着重研究了高雷诺数时展向各截面的压力、阻力、升力及涡管特性.数值计算结果表明:展向各截面柱体受力关于中截面对称且小于二维情况,柱体周围流场呈现明显的三维特性.     

四室井筒式地下连续墙水平承载试验研究(英文)

井筒式地下连续墙基础因为存在土芯、墙体和外部土体的相互作用,其水平承载机理复杂。进行了3组不同尺寸的四室模型墙试验。基于模型墙内力和位移测试结果,研究了其水平承载特性。结果表明:不同截面尺寸和埋深的井筒式墙基础在不同水平荷载下的弯矩、剪力、转角、土抗力以及摩阻力分布形状相似;随着墙体截面尺寸和深度的增加,弯矩增大,墙体呈现刚体破坏特征;前墙外侧土抗力随荷载线性增加,成为土抗力的主要贡献部分。     

冲淤管道装置冲刷能力的研究

冲淤管道装置系统是修建于港池池底,主要适用于顺岸式码头泥沙处理的清淤系统。该装置的结构主要包括管道上顺次排布的喷嘴,冲淤管道,管路系统和动力设施。根据实验研究结果,着重探讨了该系统的基本组成部分即喷嘴的结构设计,管道最优参数选择,并着重对冲淤管道冲淤的可行性和冲淤能力进行分析,也对该冲淤管道装置的实际应用和布局进行介绍。池底冲淤管道装置系统的主要特点是充分利用河道本身运移能力进行清淤工作。该清淤技术可作为解决顺岸式码头港池和其它特定区域泥沙淤积问题的技术措施。     

城市快速路建设先决条件分析

如何把握城市快速路的建设时机是众多发展中的大城市在构建面向未来的交通系统过程中正在面对或即将面对的问题.在中国城市交通发展模式转型和创新的背景下,探讨如何针对特定的时间、特定的城市正确决策快速路的建设.首先梳理国内外城市快速路的发展历程,分析快速路区别于一般城市道路的特征.提出将城镇化、机动化和区域化水平作为判定城市快...     

Dry sliding wear behavior of silver containing Ni-based composite-steel tribo-pair

Ni-based self lubricating composites containing four different amounts of silver were prepared by powder metallurgy (PM) route. The room temperature friction and wear behavior was investigated by carrying out dry sliding experiments against bearing steel using a ring-on-disk configuration. Tests were conducted at a constant load of 100N and different sliding speeds of 0.5, 1.0 and 1.5 m/s to analyze the effect of both the speed and the silver content on the wear behavior of the tribo-pair. The friction coefficient and the wear rate of the composites were found to decrease with increasing both the sliding speed and the silver content. The wear rate of the counterface was observed to be a little higher when it was siding against the composite having silver in comparison to that without any silver. However, the overall wear rate of the tribo-pair was found to decrease with increasing sliding speed and silver content.