A route guidance system considering travel time unreliability

Under a stochastic roadway, drivers need a route guidance system incorporating travel time variability. To recommend a customized path depending on the trip purpose and the driver’s risk-taking behavior, various path ranking methods have been developed. Unlike those methods, our proposed disutility method can easily incorporate a target arrival time in the ranking process by measuring how late the travel is and by penalizing it depending on the severity of lateness. In addition, the disutility-based route guidance system can properly address travel time unreliability that causes unacceptable disruptions to the driver’s schedule (i.e., unexpected long delay). We compare the disutility-based path ranking method with other ranking methods, the percentile travel time, the mean excess travel time, and the on-time arrival probability. We show that the disutility has stronger discriminating power and requires less solution space to find an optimal path. The most important advantage is that it can estimate a driver’s risk-taking behavior for each trip purpose by using the discrete choice analysis. We construct a simulation framework to acquire the travel time data on a hypothetical roadway. We analyze the data and show how various ranking methods recommend a customized path. Using the data, we show the advantage of the disutiltiy method over the other methods, which is generating a customized path with respect to the target arrival time by properly penalizing the travel time lateness.     

导弹中末段制导导引律转换研究

文章研究了导弹由中间段制导律向末段制导律转换的问题,提出了一种可变导引系数的组合制导律,即可变系数组合比例导引律（ACNG）。仿真结果表明,该导引律总体优于纯比例导引和固定系数组合比例导引律,中末段弹道过渡平滑,衔接良好,有利于中末段的交班,同时降低了导弹的需用过载。     

基于贝叶斯网络的末制导雷达可靠性分析

复杂系统的可靠性数据分散、混杂,传统方法难以得出有效的分析结论。贝叶斯网络模型能够描述部件间相互关系与系统影响程度的变化趋势,较适于建立可靠性分析模型。为此,以某型导弹末制导雷达为实例,通过不同条件下两种贝叶斯网络模型（静态与动态）的比较分析,较为详细地给出故障诊断与致因影响等结论,并验证了模型的有效性。     

基于交通限制的路网最优路径算法

为了解决车辆诱导系统中复杂道路结构表达及因为城市道路交通信号管理而产生的最优路径选择求解的复杂性,依据图论中最短路径算法的基本原理,提出了含有禁行路线路网的最优路径求解算法。以行程时间最少为目标,按照网络转化法把含有禁行路线的路网转化为不含有禁行路线的路网,采用邻接节点矩阵和邻接节点权矩阵实现了道路节点关系的表达,改善了传统的Dijkstra算法,将全局节点路径的求解转化为与求解节点紧密联系的局部区域求解,将所研究的网络转化方法和改进的路径寻优算法应用于车辆诱导系统。结果表明应用该算法能够在含有禁行路线的路网中求解最优路径,减少了问题求解的路网节点数,提高了计算效率。     

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目前，停车困难已经成为城市商业中心区的突出问题，本文以工作实践为基础，对北京市商业中心区停车问题进行了初步的研究分析，在充分吸取国内外先进技术和经验的基础上，给出了停车诱导系统的总体结构，LED 可变信息情报板的规划设置以及系统信息提供注意事项，提出了停车诱导管理的设计与控制方法，并结合北京市王府井和西单地区停车诱导管理系统实际建设应用，表明应用效果明显.     

双目标路径诱导下的交通信息定价策略

为了提高交通信息定价精度,在假定出行者权衡出行时间和出行费用双目标路径诱导的基础上,建立混合均衡定价模型,通过实例对模型进行了标定和验证,对比评价了单目标和双目标路径诱导下的交通信息定价策略,并给出双目标路径诱导下的交通信息定价结果。研究结果表明,与双目标路径诱导相比,单目标路径诱导改变了交通信息定价的可行区域,当具有信息的出行者、交通信息提供者、交通管理者三方各自的利益为决策主体时,交通信息的最终价格分别为1.3、2.6和1.8元,说明了混合均衡定价模型是有效的。     

交通拥挤漂移的形成机理与预防技术

为了研究交通诱导信息对驾驶员驾驶行为的影响,从诱导比例、替代路径数量、替代路径合理性和路网交通负荷分布的角度,分析了在动态交通诱导条件下拥挤漂移现象的产生机理,提出了逐步增加诱导比例,在路阻数据中加入干扰因子与K最短路方法等3种预防交通拥挤漂移的技术,并采用Vissim交通仿真软件对其进行了模拟评价。模拟结果表明:在局部拥挤的道路网络中,所提出的3种方法都能够减轻或消除拥挤漂移现象,其中K最短路方法的效果最好,其次是逐步诱导方法,尽管在路阻数据中加入干扰因子的方法效果最不理想,但仍优于对车辆进行100%诱导和不采取任何诱导措施的情况。     

基于元胞自动机的VMS诱导信息系统研究

VMS诱导信息系统的特点是系统的性能高度依赖驾驶员对信息的反应，诱导信息类型一直是研究的重点。已有的研究多侧重于将行程时间作为诱导信息，如当前行程时间、预测行程时间。有学者基于两条等长路径尝试将速度信息作为诱导信息，并对最近驶出车辆的行程时间信息和平均速度信息的诱导效果进行对比，结果表明速度诱导信息效果更好。考虑实际路网中．替换路径长度通常不等，文中以元胞自动机为工具，对发布平均行程时间诱导信息和平均速度诱导信息的效果进行模拟，并对结果进行分析。     

The influence of route guidance advice on route choice in urban networks

The paper begins by reviewing what is known about route choice processes and notes the mismatch between this knowledge and the route choice assumptions embedded in the most widely used assignment models. Empirical evidence on the influence of route guidance advice on route choice is reviewed and, despite its limited nature, is seen to suggest that users are reluctant to follow advice unless they find it convincing and that, the more familiar they are with the network, the less likely they are to accept advice. Typically only a small minority of journeys are made in total compliance with advice.Results from an interactive route choice simulator (IGOR) are summarised and are seen to reveal that compliance depends on the extent to which the advice is corroborated by other factors, on the drivers' familiarity with the network and on the quality of advice previously received. It is noted that the IGOR results are in a form which would enable response models to be calibrated.Recent approaches to the modelling of route choice in the context of guidance are discussed. Some are seen to make simplifying assumptions which must limit the relevance of their results; most make no allowance for the fact that drivers are unlikely to comply with all advice and several are not able to represent the benefits which guidance might bring in the context of sporadic congestion or incidents.As an alternative, a two phase model comprising a medium term strategic equilibrium and a day-specific simulation with explicit representation of driver response is proposed.Updated and extended from an earlier version published in theProceedings of the Japan Society of Civil Engineers (JSCE No 425/IV-4, 1991-1).     

完善上海轨道交通网络导乘系统管理的探讨

在上海轨道交通形成网络后,乘客对导乘信息的需求更为迫切和多元化。目前上海轨道交通网络中已有多种形式的导乘系统为乘客提供多方位的导乘信息服务。介绍了运营服务标识系统、广播系统、乘客信息服务系统、客服中心技术支持系统、智能查询系统、网络运营智能化信息服务系统等,以及上海地铁服务监督热线、运营便民信息(印刷品)、上海地铁网等,并指出了存在的问题。对如何完善上海轨道交通网络运营导乘系统提出了相关建议。