随机化交通灯的二维元胞自动机交通模型

元胞自动机交通模型以简单的规则反映交通系统中的多种因素，可以分析各种交通现象，且可在计算机上方便、高效地运作·Ｂｉｈａｍ－Ｍｉｄｄｌｅｔｏｎ－Ｌｅｖｉｎｅ模型（ＢＭＬ模型）实现了二维交通问题的元胞自动机模型的模拟研究·本文对ＢＭＬ模型作了改进，解除了该模型中关于交通灯同步变化的限制·在新模型中，每个路口的交通灯可以自由选定起始工作时间和变化节奏，于是可以更全面、准确地反映交通灯对交通系统性能的影响·本文还对新模型中出现的若干新效应作了解释·     

城市交通路线选择问题的一种优化模型

市内交通的拥挤是广大市民关心的大问题。为了缓解交通的拥挤状况,我们对其原因进行了调查、分析和研究,建立了城市交通路线选择问题的优化模型,并且给出了相应的算法。假定某市的街道把城区分成了矩形方块,其路口为十字路口或丁字路口。某甲从家驱车上班,向东要经过m个方块,向北要经过n个方块。根据交通规则,在下面两种情况下无需等待绿灯信号,可直接通过:(1)在路口向右拐弯,(2)直接穿过左丁字路口(即向左可以     

粗糙集方法在路口交通模糊控制中的应用

交通灯的控制是城市交通系统中一个重要的问题.对交通过程采用模糊控制,模糊规则的获取以及模糊规则的客观性问题一直是众多学者努力研究的问题.粗糙集理论的提出主要是用来处理不完整和不确定信息,可以用来观察、测试数据并进行逻辑推理.本文采用粗糙集的方法对模糊规则的生成进行处理,生成相对客观的模糊规则.并结合路口交通的模糊控制问题,阐述该方法的实用性以及生成的模糊规则的客观性.     

基于问题驱动的泊松分布教学设计

本文采用问题驱动的教学模式,探讨了对泊松分布的教学设计.从交通路口拥堵程度的评估问题入手,建立基于二项分布的概率模型,利用连续问题离散化的思想,引出泊松分布及泊松定理,最后计算交通路口拥堵的概率.     

突发事件中对嫌疑犯有效封堵的模型与算法

基于CUMCM-2011 B题中关于嫌疑犯的封堵问题的研究.通过建立描述市区交通网络图的权矩阵,采用求最短路的Dijstra算法求出市区任意两节点的最短路径及路长,构作最佳路径阵和距离矩阵,以此为基点建立封堵路口的最优调度方案模型,再在此基础上建立封堵住嫌疑犯的最优模型,并设计了模型求解的算法.将算法应用于CUMCM-2011 B题中关于嫌疑犯的封堵问题,获得最优封堵方案.     

两级分解—协调方法在交通系统模糊控制中的应用

文章将大系统理论与模糊控制理论相结合，并应用于交通控制系统作了尝试。通过对单路口交通系统的分析，把大系统的分解—协调思想应用于单路口交通模糊控制中，提出了单路口交通系统的两级分解—协调模糊控制方法，并进行了计算机仿真研究。仿真结果表明，文中提出的方法比传统的交通控制方法（全感应控制方法）有效。     

考虑禁左条件的用户均衡交通配流模型与算法

交叉口处左转车流是对车流量影响较大的一个流向,也是造成城市交通拥挤和交通事故的关键因素之一,所以越来越多的城市路网选择在交叉口禁止左转来保障主干路车流通畅.在禁左的情况下,出行者究竟如何选择出行路径,究竟应该在哪些交叉口采取禁左管理可以使网络总旅行时间最小?针对以上两个问题,将根据用户均衡(UE)原理,建立考虑交叉口禁左条件的交通配流双层规划模型.利用Frank-Wolfe算法,对下层模型中的出行车辆进行配流,并返回到上层模型计算网络总旅行时间,通过遗传算法确定设置禁左交叉口位置,使得网络总旅行时间达到最小.根据数值算例,展现合理设置禁左交叉口的位置,可以使得交通网络总费用减小.     

煤车装卸系统的优化操作

本文对一煤炭装卸系统建立优化模型,目标函数是每年总费用的期望值。我们将问题归结为寻求一定的操作规则,以使总费用期望值近似达到最优。此外,我们为了达到最少总费用安排了一个日调度表,最后,讨论了模型的优缺点。     

立方非线性微结构固体中的对称孤立波及存在条件

考虑固体材料的宏观尺度立方非线性效应、微尺度立方非线性效应以及微尺度频散效应并根据修正的Mindlin理论,建立了一维微结构固体中纵波传播的一种新模型.用动力系统的定性分析方法,证明了适当条件下立方非线性微结构固体中可存在对称钟型孤立波和反钟型孤立波,并给出了两种孤立波的存在条件.用数值方法分析了微尺度立方非线性效应对钟型与反钟型孤立波的影响,结果显示随着微尺度非线性效应的增强(或负增强),两种孤立波的宽度变窄(或变宽)而幅度保持不变.     

一类描述大气中重力孤立波的新模型

从两层流体浅水波方程出发,运用尺度分析与扰动方法,建立了一类新的模型(mKdV-BO模型)来描述大气中的重力孤立波。前人建立的KdV模型和BO模型适合描述经向和纬向扰动较弱时重力孤立波的生成和演化,而该模型的非线性更强,适合描述经向、纬向扰动较强时重力孤立波的生成与演化。通过运用试探函数法获得了模型的代数孤波解,并分析了孤立波的生成条件与传播速度。新模型的建立对于进一步解释大气中列队雷雨阵的形成机制,探讨大气中的强对流天气如飑线的形成等具有重要意义。 关键词：重力孤立波;试探函数法;列队雷雨阵     

Self‐organizing traffic lights at multiple‐street intersections

The elementary cellular automaton following rule 184 can mimic particles flowing in one direction at a constant speed. Therefore, this automaton can model highway traffic qualitatively. In a recent paper, we have incorporated intersections regulated by traffic lights to this model using exclusively elementary cellular automata. In such a paper, however, we only explored a rectangular grid. We now extend our model to more complex scenarios using an hexagonal grid. This extension shows first that our model can readily incorporate multiple‐way intersections and hence simulate complex scenarios. In addition, the current extension allows us to study and evaluate the behavior of two different kinds of traffic‐light controller for a grid of six‐way streets allowing for either two‐ or three‐street intersections: a traffic light that tries to adapt to the amount of traffic (which results in self‐organizing traffic lights) and a system of synchronized traffic lights with coordinated rigid periods (sometimes called the “green‐wave” method). We observe a tradeoff between system capacity and topological complexity. The green‐wave method is unable to cope with the complexity of a higher‐capacity scenario, while the self‐organizing method is scalable, adapting to the complexity of a scenario and exploiting its maximum capacity. Additionally, in this article, we propose a benchmark, independent of methods and models, to measure the performance of a traffic‐light controller comparing it against a theoretical optimum. © 2011 Wiley Periodicals, Inc. Complexity, 2012     

城市主干道交通信号灯模糊线控制的探讨

本文首先提出城市交通系统线控制的两级递阶结构：第一级，用模糊逻辑控制器确定单路口交通信号灯的周期和绿信比；第二级，用模糊相位控制器确定相邻两路口的相位差；两级间用模糊转换开关协调；然后，提出具体的实现方法。     

Heavy and light traffic in fluid models with burst arrivals

We consider the problem of finding a heavy and light traffic limits for the steady-state workload in a fluid model having a continuous burst arrival process. Such a model is useful for describing (among other things) the packetwise transmission of data in telecommunications, where each packet is approximated to be a continuous flow. Whereas in a queueing model, each arrival epoch,t _n , corresponds to a customer with a service timeS _n , the burst model is different: each arrival epoch,t _n , corresponds to a burst of work, that is, a continuous flow of work (fluid, information) to the system at rate 1 during the time interval [t _n ,t _n +S _n ]. In the present paper we show that the burst and queueing models share the same heavy-traffic limit for work, but that their behavior in light traffic is quite different.Research supported by the Japan Society for the Promotion of Science, during the author's fellowship in Tokyo.Research funded by C & C Information Technology Research Laboratories, NEC, and the International Science Foundation.     

主路m条车道的车流服从M3分布下支路混合车流的通行能力

本文以可接受间隙理论为基础,利用概率论方法,对以大车和小车两种代表车型组成的混合车流进行分析,建立了无信号交叉口支路混合车流穿越主路m条车道,每一车道的交通流车头时距服从不同强度的M3分布的通行能力模型,发了无信号交叉口单一车型、单一车道车流理想条件的通行能力理论。     

主路多车道无信号交叉口混合交通流的通行能力

Highway capacity is defined as maximum volume of traffic flow through the particular highway section under given traffic conditions,road conditions and so on.Highway construction and management is judged by capacity standard.The reasonable scale and time of highway construction,rational network structure and optimal management mode of highway network can be determined by analyzing the fitness between capacity and traffic volume.All over the world,highway capacity is studied to different extent in different country. Based on the gap acceptance theory,the mixed traffic flow composed of two representative vehicle types heavy and light vehicles is analyzed with probability theory.Capacity model of the minor mixed traffic flows crossing m major lanes,on which the traffic flows fix in with M3 distributed headway,on the unsignalized intersection is set up,and it is an extension of minor lane capacity theory for one vehicle-type and one major-lane traffic flow.     

Optimal control in light traffic Markov decision processes

We consider Markov Decision Processes under light traffic conditions. We develop an algorithm to obtain asymptotically optimal policies for both the total discounted and the average cost criterion. This gives a general framework for several light traffic results in the literature. We illustrate the method by deriving the asymptotically optimal control of a simple ATM network.     

Light traffic for workload in queues

General exact light traffic limit theorems are given for the distribution of steadystate workloadV, in open queueing networks having as input a general stationary ergodic marked point process {(t _n ,K _n )n0 (where t_n denotes the arrival time and K_n the routing and service times of the nth customer). No independence assumptions of any kind are required of the input. As the light traffic regime, it is only required that the Palm distribution for the exogenous interarrival time converges weakly to infinity (while the service mechanism is not allowed to change much). As is already known in the context of a single-server queue, work is much easier to deal with mathematically in light traffic than is customer delayD, and consequently, our results are far more general than existing results forD. We obtain analogous results for multi-channel and infinite-channel queues. In the context of open queueing networks, we handle both the total workload in the network as well as the workload at isolated nodes.Research supported in part by the Japan Society for the Promotion of Science during the author's fellowship in Tokyo, and by NSF Grant DDM 895 7825.     

短时交通流混沌预测模型的比较研究

短时交通流预测是实现交通流诱导的关键技术之一.针对目前短时交通混沌预测模型预测结果差异较大的问题,归纳了4种基于混沌理论的短时交通流预测模型:RBF神经网络模型、最大Lyapunov指数模型、局域线性模型和Volterra滤波器自适应预测模型,并对这4种预测模型进行了比较研究.应用4种预测模型对几个典型的非线性系统进行预测,验证了算法的准确性.然后用这4种预测模型对微观实测交通流的时间序列进行实证分析.仿真结果表明,4种预测模型对典型混沌时间序列具有很好的预测效果;而对实测交通流预测,其预测精度和稳定性较差,但可以满足实时交通流预测的需要.     

Light traffic heuristic for anM/G/1 queue with limited inventory

Motivated by solving a stylized location problem, we develop a light traffic heuristic for anM/G/1 queue with limited inventory that gives rise to a closed form expression for average delay in terms of basic system parameters. Simulation experiments show that the heuristic works well. The inventory operates as follows: the inventory level drops by one unit after each service completion and whenever it drops to a pre-specified levelu, an order is placed with replenishment time exp(). Upon replenishment the inventory is restocked to a pre-specified levels and any arrivals when there is no inventory are placed in queue. Suggestions are given to cover the more general case of a New Better than Used (NBU) replenishment time distribution. Applications to inventory management problems are also discussed.The research was supported in part by ONR Contract N00014-90-J-1649, NSF Contract DDM-8922712 and the Center for Telecommunications Research under NSF grant CDR 84-21402.