动态平衡运量配流问题及其稳态伴随解算法

动态平衡运量配流问题的建模和求解是发展智能车辆导驶系统的理论基础.本文对多起点单讫点交通网络建立了连续时间最优控制模型,该模型的最优解对应于动态用户平衡解.文中提出的稳态伴随解算法避免了解复杂的两点边界值问题,可以获得原问题的近似解.该算法利用了交通网络和计算机网络的结构特性,计算速度较高,可用于城市交通流的实时控制.     

基于路段元胞传输模型的动态用户最优配流问题

利用基于路段的元胞传输模型进行模拟, 给出了一种计算实际路段出行阻抗的方法, 并在此基础上构造了基于路段变量的动态用户最优变分不等式模型. 模型采用针对迄节点的路段变量, 在每一个小时段都能给出路段流入率、流出率、路段流量和实际路段阻抗, 为用户提供较为全面的诱导信息打下了较好的理论基础. 采用了修正投影算法来进行求解. 数值算例表明模型具有的实用性和优越性, 使道路交通流宏观模型与动态网络交通配流问题得到较好的结合.     

交叉口有交通信号控制时用户最优动态配流模型

针对智能交通系统（ＴＴＳ）基础上中主要基础理论之一的动态交通分配问题,在现有研究成果的基础上,提出了更接近真实路网的多起点多旋点交叉口设置有交通信号控制（Ｔｒａｆｆｉｃ Ｓｉｇｎａｌ Ｃｏｎｔｒｏｌ）时的动态配流模型,给出了对现有的通过Ｆｒａｎｋ Ｗｏｉｆｅ算法所得的ＤＵＯ配流解进行修正的原则,最后的算例表明由修正后的模型和算法所得到的ＤＵＯ配流解满足ＴＳＣ约束。     

基于神经网络的酵母流加发酵过程最优重复控制新方法

本文提出了基于神经网络的酵母流加发酵过程最优重复控制的两种新方法,方法1 采用状态反馈控制律,用误差反传法学习过程和控制器神经网络参数。方法2 采用直接最优控制律,用误差反传法学习过程神经网络参数和控制作用,两种方法都具有很强的自适应能力,在控制方案实施时,采用了动态重复控制方式,使得本文控制方法具有类似于预测控制的优点,鲁棒性好,将其用于醇母流加发酵过程的优化控制,仿真结果令人满意,实验证明按最优流加轨线操作,可使产率提高26％,糖蜜消耗减少4％,本文方法为那些用传统方法难以建模的生化过程的优化控制提供了一条新途径。     

配煤优化模型及其专家系统的设计

近几年,国内外对焦炭的需求量不断增长,焦炭成了紧俏商品。如何充分利用当地的煤炭资源,以经济的方式进行配煤炼焦,成为炼焦企业急需解决的问题。本文围绕炼焦配煤领域的研究前沿,采用混合型0～1整数规划技术,建立了以炼焦成本最低为目标的配煤比优化模型。在此基础上设计并建立了一套能够准确、快速地预测焦炭质量、计算低成本配煤方案的配煤优化专家系统,较好地解决了炼焦配煤周期长和炼焦煤市场供应变化快之间的矛盾。     

基于抽象匹配流的彩色图像配准模型

在抽象匹配流框架下,构造能够克服大色差问题的彩色图像配准模型.该模型中,数据项采用互相关函数作为2幅图像间的相似性度量,以解决大色差问题;正则项采用各向异性扩散滤波器约束图像演化,从而实现在演化过程中对图像特征的有效保持.扩散滤波器中的扩散系数定义为关于彩色结构张量的函数,以使图像演化能够综合各通道信息,解决了各通道所得位移场不一致而引起的色彩混迭问题.实验结果表明,文中模型对具有大色差的彩色图像能够实现有效配准.     

基于流演算理论的动态访问控制模型研究

访问控制模型为系统的信息安全提供了一个理论框架,其目的是保护系统资源不被非法用户盗用,防止合法用户对受保护信息进行非法使用。然而,现有的访问控制模型大部分属于静态授权模型,不能方便地描述大规模、异构的分布式网络系统中授权过程的动态变化。为了解决上述不足,在充分研究流演算理论的基础上,提出了一个基于流演算理论的访问控制模型(FCDAC)。FCDAC将动态世界中的所有授权过程都看作是动作的结果,通过动作来实现状态的变化,并且在系统中只需描述动作的前提条件公理和状态更新公理就可容易地实现权限的变化。最后,通过一个教务管理实例验证上述理论,结果表明FCDAC是可行的。     

基于多级流模型的流过程故障诊断算法

通过一个简单的流过程介绍了采用多级流模型技术进行系统建模和利用其模型进行故障定位诊断的原理.提出了通过矩阵运算实现故障搜索的方法,并提出了传播路径状态矩阵状态向量、节点影子状态矩阵等新定义,将有利于发挥多级流模型在快速故障诊断中的高效率.     

动态Leontief投入产出模型的LQ最优控制

本文首先探讨了动态Leontief投入产出模型的最小实现问题,提出了以投资为控制向量的状态方程,然后在此基础上导出了具有明确经济意义的最优反馈控制策略。     

鱼雷柱塞变量泵配流阀参数设计与仿真

在鱼雷动力系统设计中,燃料柱塞泵安全可靠性对鱼雷发挥最大战斗效率具有很大的意义。在鱼雷HAP三组元能供系统中,由于柱塞变量燃料泵采用端面配流方式,缸体和配流盘存存摩擦运动,长时间工作下,缸体的温度会上升,容易造成燃料泵爆炸,基于鱼雷能供系统的安全性考虑,使用阀式配流代替端面配流来消除安全隐患。通过分析柱塞变量泵的配流阀的结构形式,主要部件的参数计算和建立配流阀模型,在Matlab软件中,用ODE45算法仿真了柱塞泵在阀式配流下,柱塞腔的压力变化情况,并计算了阀式柱塞泵在高低两种转速下的容积效率。经仿真分析,柱塞变量泵在阀式配流下完全满足设计要求,从而验证了方法的可行性。     

Continuous and Discrete Trajectory Models for Dynamic Traffic Assignment

A continuous trajectory model is presented in which transportation networks are represented as topological constructs. The general formulation enhances existing analytic dynamic traffic assignment models by incorporating continuous single-link traffic flow models in a general, coherent, and relatively intuitive manner. Specific exact formulation based on a simplified kinematic wave traffic flow model with physical queues is presented as well.A discrete trajectory model is proposed as an approximation of the continuous model. The discrete model provides wide flexibility in choosing the level of aggregation with respect to time intervals, ranging from several hours, as typical in current practice of long-term travel forecasting models, to one second or less, as in microscopic simulations. An algorithm to find discrete approximate solutions is presented as well as accuracy measures to evaluate them. The effect of time resolution on model performance is examined by a numerical example.     

Analytical Models of the Dynamic Traffic Assignment Problem

A review of analytical formulations of the dynamic traffic assignment problem is presented, focusing on the authors' experience with variational inequality approaches. Solution algorithms and computational issues requiring additional study are discussed.     

Some Consistency Conditions for Dynamic Traffic Assignment Problems

This paper explores some critical issues in modeling network traffic flow for predictive user optimal dynamic traffic assignment. They include the role of FIFO (first-in-first-out) in link, path and network traffic dynamics, minimal set representation of link traffic evolution, and consistency conditions for link models. It is found that (1) link FIFO plays a central role in modeling link, path and network traffic flow evolution, and (2) the dimension of a minimal state set that adequately describes link traffic flow under FIFO is two. Moreover, two sufficient FIFO conditions are provided, and pitfalls in using these conditions to enforce FIFO are pointed out. Finally, ramifications of these findings to DTA modeling are also discussed.     

A Decomposition Scheme for System Optimal Dynamic Traffic Assignment Models

In this paper, a Dantzig-Wolfe decomposition based solution algorithm is developed for the linear programming formulation introduced by Ziliaskopoulos (2000) for System Optimal Dynamic Traffic Assignment problem. The algorithm takes advantage of the network structure in the constraint set of the formulation: the sub-problem is formulated as a minimum-cost-flow problem and the master as a simpler linear programming problem, which allows DTA to be solved more efficiently on meaningful networks. The algorithm is tested on an example network and its performance is analyzed.     

The CONTRAM Dynamic Traffic Assignment Model

CONTRAM is a computer model of time-varying traffic in road networks, which takes as input the network definition and time-varying demand for travel between a set of origin and destination zones, and outputs the resulting network flows, routes and travel times. It combines a macroscopic time-sliced traffic model with disaggregate dynamic assignment of traffic, so is intermediate between macroscopic equilibrium and microscopic models. The paper details the methods used, including time-dependent queuing which plays a central role, and the treatment of network definition, user classes, road capacities, signals and coordination, vehicle emissions, Intelligent Transport Systems and research lines.