北美铁路时间标准化的考察

北美铁路时间标准化是19世纪全球标准时间改革中最为重要的环节,它开创了公共记时的新纪元,为国际子午线会议的召开奠定了基础。铁路网络和通讯手段的快速发展为铁路标准时间在北美的诞生提供了契机,同时,纷繁芜杂的地方时增加了铁路时间标准化的必要性和紧迫性。北美铁路标准时间的实施,体现的是社会各个层面共同发展所形成的社会合力的作用。     

Gender structures in car availability in car deficient households

This paper studies the intra-household allocation of cars in car deficient households from a gender perspective. An individual’s car access is measured in terms of duration of car use over a week. Car deficient households are defined as households with fewer cars than drivers. We develop a set of hypotheses that serve to explain gender differences in car availability, and empirically test some of these hypotheses by using multiple regression analysis. The data we use is the German Mobility Panel 1994–2008. Our findings provide evidence for the importance of social roles and economic power in intra-household negotiations about the limited resource of the household car. We cannot clearly decipher whether patriarchal structures and/or gender preferences are relevant as well, but our data suggest that both may play a role.     

Impacts of Information and Communication Technologies (ICT) on time use and travel behavior: a structural equations analysis

The objective of this paper is to contribute an empirical study to the literature on transportation impacts of Information and Communications Technologies (ICT). The structural equation model (SEM) is employed to analyze the impacts of ICT usage on time use and travel behavior. The sample is derived from the travel characteristic survey conducted in Hong Kong in 2002. The usage of ICT is defined as the experience of using e-mail, Internet service, video conferencing and videophone for either business or personal purposes. The results show that the use of ICT generates additional time use for out-of-home recreation activities and travel and increases trip-making propensity. Individuals at younger age or with higher household income are found to be more likely ICT users. The findings of this study provide further evidence on the complementarity effects of ICT on travel, suggesting that the wide application of ICT probably leads to more, not less, travel. The study also demonstrates the importance of considering the interactions between activity and travel for better understanding of the nature and magnitude of the impacts of ICT on time use and trip making behavior.     

Prediction of ambient carbon monoxide concentration using nonlinear time series analysis technique

This study evaluates the potential of nonlinear time series analysis based methods in predicting the carbon monoxide concentration in an urban area. To establish the functional relationship between current and future observations, two models based on local approximations and neural network approximations are used. To compare the performance of the models, an autoregressive integrated moving average model is also applied. The multi-step forecasting capabilities of the models are evaluated.     

水泥混凝土路面板下脱空的路面雷达电磁波模拟

建立了路面雷达电磁波在水泥混凝土路面结构中传播的二维时域有限差分(2D-FDTD)方程,并针对空气耦合式天线雷达进行了水泥混凝土路面板下存在脱空病害的路面雷达电磁波模拟。进一步分析了水泥混凝土板下脱空出现水充空洞及气充空洞两种情况的路面雷达回波特性,本文的研究对路面雷达技术应用于水泥混凝土路面脱空病害检测实施具有重要的理论参考意义。     

城市交通管理的国民经济效益评价方法研究

在对比分析现有国民经济效益评价方法的基础上,本文从时间节省、燃油节约和交通事故减少3个方面提出了适合我国国情的国民经济效益评价的模型与方法,探讨了模型中主要参数的计算方法和取值。以178个城市3年来的统计数据为基础进行了应用研究,结果表明,模型能够较为合理的对交通管理产生的国民经济效益进行评价。     

基于需求划分的带软时间窗的路径优化方法

针对带有时间窗约束的车辆路径问题(Vehicle Routing Problem With Time Windows,VRPTW)的NP特征,以非完全连通配送网络为研究对象,用带有软时间窗约束的整体配送费用最小为目标,提出了一种基于需求的城市动态划分方法,有效的减少了路径的组合规模,并且用遗传算法将其实现,通过改进的Dijkstra算法求取其基于动态划分的最优配送路径集,最后计算示例验证了本文方法的有效性。     

大秦线2亿吨运输能力若干问题的探讨

大秦线实现2亿吨、储备3亿吨的运输能力,应走大重量、低密度的道路。在最终列车重量全部实现20000t的前提下,提出过渡期的列车重量方案和相应的行车密度;检算追踪列车间隔时间和天窗占用运行图时间;分析线路在开设垂直型天窗时天窗占用运行图时间较大的原因;确定需要的通过能力;提出车站封闭的数量和保留车站的改扩建方案;提出煤炭装车站(点)、卸车地和相关线路的配套改造方案。     

高速铁路对道岔侧向最高允许通过速度的要求

从满足高速铁路运营的角度,研究道岔侧向最高允许通过速度。分析认为影响因素有列车最小运行间隔时间、最高运行速度、列车制动性能和加速性能、沿线车站到发线长度。以列车最高运行速度300km·h-1和350km·h-1等条件为前提,对4种运行工况下道岔侧向最高允许通过速度要求进行计算。结果表明,高速铁路的区间道岔侧向最高允许通过速度选择应不低于160km·h-1,车站道岔和咽喉区渡线侧向最高允许通过速度选择应不低于100km·h-1。