遗传算法在城市单交叉路口信号动态控制中的研究及应用

提出一种实时遗传算法优化配时控制方法,对单交叉路口多相位交通流建立一种实时动态模型,根据不同时刻的不同车流量,选择最优相位配时和相位顺序,通过对本周期及前一周期的车流量进行实时测量,采用线性预估方法,对下一周期的车流量进行预估,以最大通行能力为路口模型控制性能指标,从而确定下一周期的相位配时方案。最后在原模型的基础上作为改进模型的例子融入了延误时间,得到了新的目标函数。采用C语言编程进行实时仿真试验,结果表明,算法实时性好,运行稳定。     

Violent water-structure interaction: Overtopping features and vertical loads on a fixed structure due to broken incident flows

This paper presents an alternative experimental study of the interaction of broken flows with a fixed structure, concerning the overtopping features and vertical loads over its deck. Wet dam-break tests were carried out to generate incoming flows. Synchronized measurements provided by high-speed cameras, water elevation and force sensors, were used to investigate the influence of tank length in overtopping behaviour and the patterns and loads formed by wet dam-break flows generated by different conditions. During some of the overtopping events analysed, large scale plunging waves were observed, hitting the deck directly and forming large air cavities. These events generated violent interactions with the structure, causing significant loads and chaotic behaviour over the deck, due to the combination of air cavity collapse, reactive splash and run-down. The present approach could be employed as an alternative to study interactions of broken incident flows with different types of fixed structures, allowing the acquisition of detailed data to compare analytical or numerical models.     

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提出一种适用于在城市中构建高速关键线路的信号配时方案.与以往只注重根据车流量适时调整信号灯的方案相比,该方案强调将关键道路上某一方向上的所有车辆分段,把每一个有效车流段看作一个整体,让其按规定速度行驶,当这些有效车流段到达叉路口时,让信号灯为其调整绿灯,而当其全部通过叉路口,在路上行驶时,让信号灯转为红灯,利用下一段车流到来前的时间间隙供另一方向的车辆通过,由于这些车辆在行驶过程中避开了所有红灯,中途无需停车,因此平均速度提高一倍以上.本文将详细阐述车流分段、行车规则和信号配时等的具体构想,并用实验验证该方案的可行性和高效性.     

Managing evacuation networks

This paper proposes a non-anticipative, adaptive, decentralized strategy for managing evacuation networks. The strategy is non-anticipative because it does not rely on demand forecasts, adaptive because it uses real-time traffic information, and decentralized because all the information is available locally. It can be used with a failed communication network.The strategy pertains to networks in which no links backtrack in the direction of increased risk. For these types of networks, no other strategy exists that can evacuate more people in any given time, or finish the evacuation in less time. The strategy is also shown to be socially fair, in the sense that the time needed to evacuate all the people exceeding any risk level is, both, the least possible, and the same as if less-at-risk individuals did not participate in the evacuation. The strategy can be proven optimal even when backflows happen due to driver gaming.     

基于二流理论的宏观交通评价模型的建立

为研究宏观道路网络交通特性,以二流理论为基础,建立道路网络宏观交通特性的评价模型。该模型引入图论的分析方法,考虑可达性的评价指标和街道的实际交通情况,全面而抽象地描述城市道路网络路段与交叉口之间的关系,并给出道路网络宏观交通特性的评价指标,最后以一简单实例说明利用该模型评价城市道路网络宏观交通特性的过程。     

基于离散单元法的道砟循环加载双轴试验研究

为从微观上分析列车循环荷载作用下道砟强度和刚度变化以及塑性变形的发展,用离散单元法模拟其在一次及二次加载条件下的双轴试验,分析2种情况在不同围压下道砟的力学特性并进行比较。结果表明:(1)第一次加载完成后,偏应力-轴向应变曲线表现为弱应变软化型或应变硬化型,其形态主要取决于围压高低;体应变-轴向应变曲线包括剪缩和剪胀2个阶段,剪缩阶段比较短。(2)第二次加载完成后,不同围压的偏应力-轴向应变曲线均为硬化型,道砟整体强度和刚度减小,塑性变形发展迅速;试验过程中,道砟颗粒一直处于剪胀状态。     

高速列车湍流绕流三维数值模拟研究

本文在般曲线坐标系下，采用Ｋ－ε双方程模型及壁面控制函数，借助于代数变换建立起以协变速度分量为独立变量的三维复杂钝体湍流绕流数值计算方法，建立了一套适合于近地大长细比复杂几何体的三维网格生成与控制方法，同时采用交错网格，成功地解决了压力－速度耦合关系。首次对高速列车三维湍流绕流场压力分布、速度分布以及气动阻力进行研究。本文的研究工作对进一步解决近地大长细比复杂几何体湍流绕流数值模拟是一个良好的开端     

基于遗传算法的城市单交叉路口信号动态控制

针对单交叉路口多相位交通流建立一种实时动态模型,并根据不同时刻的不同车流量, 选择最优相位配时和相位顺序.提出一种实时遗传算法优化配时控制方法,通过对本周期及前 一周期的车流量进行实时测量,采用线性预估方法,对下一周期的车流量进行预估,以最大通行能力为路口模型控制性能指标,从而确定下一周期的相位配时方案.采用MATLAB语言编程 进行实时仿真试验,结果表明,算法实时性好,运行稳定.     

Interaction of two-dimensional impulsively started airfoils

Continuous vortieity panels were used to model general unsteady inviscid, incompressible, two-dimensional flows. The geometry of the airfoil was approximated by series of short straight segments having endpoints that lie on the actual surface. A piecewise linear, continuous distribution of vorticity over the airfoil surface was used to generate disturbance flow. The no-penetration condition was imposed at the midpoint of each segment and at discrete times. The wake was simulated by a system of point vortices, which moved at local fluid velocity. At each time step, a new wake panel with uniform vortieity distribution was attached to the trailing edge, and the condition of constant circulation around the airfoil and wake was imposed. A new expression for Kutta condition was developed to study the interference effect between two impulsively started NACA0012 airfoils. The tandem arrangement was found to he the most effective to enhance the lift of the rear airfoil. The interference effect between tidal turbine blades was shown clearly.     

径向电场对等离子体约束的影响

讨论了由径向电场产生的剪切极向流对托卡马克中等离子体的约束的影响。采用考虑了剪切极向转动效应的新经典离子热输运系数模型,这种模型导致的热通量函数在相同的密度和温度下是多值的,将它用于电子与离子之间有碰撞的ＭＨＤ方程,数值结果显示了Ｈ模情形等离子体上边缘陡峭的离子温度梯度。