Application of fuzzy control to a road tunnel ventilation system

This paper deals with the serious problems of ventilation system in a large road tunnel. Higher visibility and lower concentration of carbon monoxide are the key issues concerning the ventilation system. Prior to designing the fuzzy control model, a configuration layout of the ventilation system including sensing, control and traffic prediction as well is conceptually constructed. Based on the layout that offers assignments of sensors and control elements, a fuzzy logic control model is developed. Membership functions of sensor errors and control increments are physically submitted in order to set up the fuzzy logic rules. Timing and spacing filtering in terms of weighting approaches is employed in the fuzzy logic rules. A dynamic equation describing the concentration of air pollution is also given so as to cooperate with the fuzzy logic rules and to play roles in the computer simulation. The result of computer simulation involving five cases indicates that a multi-level scheme is able to solve the engineering problems.     

Approximation of the steepest descent direction for the O-D matrix adjustment problem

In this paper, a method to approximate the directions of Clarke's generalized gradient of the upper level function for the demand adjustment problem on traffic networks is presented. Its consistency is analyzed in detail. The theoretical background on which this method relies is the known property of proximal subgradients of approximating subgradients of proximal bounded and lower semicountinuous functions using the Moreau envelopes. A double penalty approach is employed to approximate the proximal subgradients provided by these envelopes. An algorithm based on partial linearization is used to solve the resulting nonconvex problem that approximates the Moreau envelopes, and a method to verify the accuracy of the approximation to the steepest descent direction at points of differentiability is developed, so it may be used as a suitable stopping criterion. Finally, a set of experiments with test problems are presented, illustrating the approximation of the solutions to a steepest descent direction evaluated numerically. Research supported under Spanish CICYT project TRA99-1156-C02-02.     

Application of a simulation-based dynamic traffic assignment model

The evaluation of on-line intelligent transportation system (ITS) measures, such as adaptive route-guidance and traffic management systems, depends heavily on the use of faster than real time traffic simulation models. Off-line applications, such as the testing of ITS strategies and planning studies, are also best served by fast-running traffic models due to the repetitive or iterative nature of such investigations. This paper describes a simulation-based, iterative dynamic equilibrium traffic assignment model. The determination of time-dependent path flows is modeled as a master problem that is solved using the method of successive averages (MSA). The determination of path travel times for a given set of path flows is the network-loading sub-problem, which is solved using the space-time queuing approach of Mahut. This loading method has been shown to provide reasonably accurate results with very little computational effort. The model was applied to the Stockholm road network, which consists of 2100 links, 1191 nodes, 228 zones, representing and 4964 turns. The results show that this model is applicable to medium-size networks with a very reasonable computation time.     

基于交通仿真的交叉口渠化设计

以北京劲松交叉口为例，分别对该交叉口改善前后的运行效率进行了模拟对比，分析了的渠化设计对交通的影响。     

交通灯模糊控制器设计

运用两输入单输出的模糊控制模型，对被控对象的输入量及输出量进行了具体的模糊化，并根据模糊集合理论的计算结果得出了精确的模糊控制表，在此基础上提出了以单片机实现模糊控制器的硬件结构和程序流程。     

洛阳智慧交通系统的数据库应用研究

从研究城市路口节点和路段的状态出发,介绍交通流量调查的方法,交通流量数据库结构,数据库追加和更新技术;利用相关分析和时间序列分析方法,解决无传感器路口数据的更新机制,保障数据发布的实时性.     

Stability analysis of a multi-phase car-following model

This paper presents a numerical stability analysis of a multi-phase car-following model under mild to severe disturbances. The results show that local stability was always conformed. An asymptotically unstable region was found for traffic in congested states. One of the previously calibrated boundary conditions for close-following situations was found to be in conflict with the stable condition required by the car-following model, which had attributed to speed oscillations during transition of the traffic from a non-congested to a congested state. Suggestions were made to the choice of model parameter values to meet the stability conditions and ways to improve the model.     

The information transmission in community networks

The community structure has been empirically found in many real networks. This paper proposes an efficient Double Shortest Path routing strategy trying to avoid the modules of traffic congestion, which means that we adopt the shortest routing strategy both in the inter-modules and in the intra-module. Simulations show that this routing algorithm is superior to the traditional shortest path routing protocol with appropriate selection of the tunable parameters. In addition, this algorithm can also be improved by integrating it with several alternative routing strategies.     

Driver choice compared to controlled diversion for a freeway double on-ramp in the framework of three-phase traffic theory

Two diversion schemes that apportion demand between two on-ramps to reduce congestion and improve throughput on a freeway are analyzed. In the first scheme, drivers choose to merge or to divert to a downstream on-ramp based on information about average travel times for the two routes: (1) merge and travel on the freeway or (2) divert and travel on a surface street with merging downstream. The flow, rate of merging at the ramps, and the travel times oscillate strongly, but irregularly, due to delayed feedback. In the second scheme, diversion is controlled by the average mainline velocities just upstream of the on-ramps. Driver choice is not involved. If the average upstream velocity on the mainline drops below a predetermined value (20 m/s) vehicles are diverted to the downstream ramp. When the average mainline velocity downstream becomes too low, diversion is no longer permitted. The resultant oscillations in this scheme are nearly periodic. The period is dominated by the response time of the mainline to interruption of merging rather than delayed feedback, which contributes only a minor component linear in the distance separating the on-ramps. In general the second scheme produces more effective congestion reduction and greater throughput. Also the travel times for on-ramp drivers are less than that obtained by drivers who attempt to minimize their own travel times (first scheme). The simulations are done using the Kerner-Klenov stochastic three-phase theory of traffic [B.S. Kerner, S.L. Klenov, Phys. Rev. E 68 (2003) 036130].     

基于结构方程模型的公交驾驶员负性情绪驾驶下工作状态的影响因素分析

为减少公交驾驶员负性情绪下消极驾驶造成的交通事故,基于结构方程理论,选取了工作环境、个人属性、心理特性、综合压力以及感知水平5个指标,构建了影响公交驾驶员负性情绪驾驶下工作状态的结构方程模型,并定量分析了各影响因素之间的关系以及对驾驶员工作状态的作用大小.结果表明:工作环境、个人属性、心理特性以及感知水平对驾驶员负性情绪驾驶下的工作状态具有正向影响,综合压力具有反向影响,其中工作环境的总影响效应最大(0.97).