Counting the different efficient paths for transportation networks and its applications

This paper deals with an interesting problem about how to efficiently compute the number of different efficient paths between an origin‐destination pair for a transportation network because these efficient paths are the possible paths used by drivers to some extent. Based on a novel triangle operation derived, it first presents a polynomial‐time combinatorial algorithm that can obtain the number of different simple paths between any two nodes for an acyclic network as well as the total travel cost of these paths. This paper proceeds to develop a combinatorial algorithm with polynomial‐time complexity for both counting the different efficient paths between an origin‐destination pair and calculating the total travel cost of these paths. As for applications, this paper shows that the preceding two algorithms can yield the lower and upper bounds for the number of different simple paths between an origin‐destination pair, while it has already be recognized that a polynomial‐time algorithm getting such a number does not exist for a general network. Furthermore, the latter algorithm can be applied for developing a heuristic method for the traffic counting location problem arising from the origin‐destination matrix estimation problems.     

基于高速收费数据的路径速度还原与流量推断

基于收费数据的高速公路研究逐渐增多。本文利用收费数据对高速公路车流量进行推断。使用广度优先搜索算法对车辆进行路径还原,然后对车辆的运行状态进行了细化,对车辆平均速度的计算方法进行了优化。依据车辆行驶状态计算时间与速度,推算出车辆在不同时间段内的位置信息,进而推断出不同时段各路段的流量。与优化前的结果进行对比,发现了误差的不确定性。     

一种基于GPS的热轴跟踪方案的设计与实现

针对现有二代红外线轴温探测系统在探测到机车车辆发生强热或激热等热轴故障后,热轴跟踪和轴报信息的传递需要较长时间的问题,提出一种新的基于GPS的热轴跟踪方案,给出了热轴跟踪系统的设计方法,并在实际运行过程中证明了方案的正确性。     

容量限制的交通分配优化方法研究

容量限制一直是交通分配研究的重要内容，是造成路段和路网拥挤的根本原因。目前大多数的研究都是基于拥挤模型进行理论分析和实际计算，而实际中的拥挤路网大多不是一个平衡分配问题。以Fisk提出的Losit分配优化思想及Wardrop的系统最优为基础，建立了容量限制下的路网分配优化模型，并给出了相应的启发式优化算法。     

基于现场取样整体动稳定度的沥青面层结构组合优选

在某高速公路选取了不同车辙深度的多个横断面,在路肩处进行了全厚式沥青面层的取样,在三层式取样试件内部形成了沿厚度方向的温度梯度;开展轮辙试验测得了其整体动稳定度,分析了设计年限末路面车辙预估深度与实测整体动稳定度之间的关系;以15 mm车辙深度对应的整体动稳定度作为调研路段的结构抗车辙性能控制标准,开展了不同材料组合和厚度组合结构的轮辙试验,并以该整体动稳定度控制标准为依据进行了结构组合的优选。研究结果表明,通过分析现场车辙深度与对应沥青面层整体动稳定度之间的关系,确定沥青面层结构整体动稳定度的控制标准,此方法可以运用于类似道路的结构组合优选。     

基于SPN-PF模型的行人跟踪算法改进

结合粒子滤波和神经网络方法提出了一种新的自适应的行人跟踪改进算法.根据行人跟踪经常出现的遮挡,失跟,误跟等问题,提出了一个SPN-PF模型,通过Sigma-Pi网络将行人的多个特征联系在一起,经过学习和计算,进一步讲结果运用到粒子滤波方法中,从而达到可靠准确的跟踪行人目标的目的.实验结果表示该文提出的方法能够更准确的对行人进行跟踪.     

客运专线无碴轨道精密定轨测量技术研究

以客运专线无碴轨道CPⅢ"后方交会"控制网为基础,对精密定轨测量技术进行分析研究。首先对全站仪自由重叠设站的测设方案进行理论研究、误差分析和优化设计,然后以模拟实测实验进行验证。这对目前客运专线和城际铁路无碴轨道的精密定轨测量具有一定的指导意义。     

基手Dijstra算法群布型立交匝道优化

针对多目标最短路径的问题采用线性加权Dijstra算法。在立体交通规划布局阶段，考虑其相互作用关系，提出群布型立体交叉的概念及用最短路径法优化匝道设计的实用方法。以重庆绕城高速公路与射线之间的界石、一品、南彭立交为例，检验该方法的实用性。     

Rear-heavy car control by adaptive linear optimal preview

Adaptive linear optimal preview control theory is applied to a simple but non-linear car model, with parameters chosen to make the rear axle saturate first in any quasi-steady manoeuvre. The tendency of such a car to spin above a critical speed, which is a function of its running state, causes control to be especially difficult when operating near to the limit of the rear-axle force system. As in previous work, trim states and optimal gains are computed off-line for a given speed and a full range of lateral accelerations. Gain-scheduling with interpolation over trims and gain sets is used to keep the control appropriate to the running conditions, as they change. Simulations of manoeuvres are used to test and demonstrate the system capability. It is shown that utilising the rear-axle lateral-slip ratio as the scheduling variable, in the case of this rear-heavy car, gives excellent tracking, even when the tyres are run close to full saturation. It is implied by this and previous work that the general case can be treated effectively by monitoring both front- and rear-axle slips and scheduling on a worst-case basis.     

用改进的遗传算法解决多约束QoS单播路由问题

在Internet网络中由于多媒体通信的需要,QoS路由技术已经成为研究的热点。本文通过对多约束QoS单播路由问题的研究,在已有遗传算法解决方案的基础上,提出一种改进的遗传算法。改进后的遗传算法综合考虑QoS单播路由中延时、延时抖动、带宽、丢失率等因素,并根据网络连接特性和带宽限制,在种群的初始化、染色体的交叉和变异等操作中,对个体中基因的选择进行指导,并加入去除循环、削减路由开销等操作,使得多条件约束下的路由选择效率更高。最后给出实验举例,并通过与现有算法性能比较,表明改进的遗传算法能快速、有效地解决多约束QoS单播路由选择问题,并适用于大规模的网络系统。