有容量限制的广义网络均衡比较

近些年来,Wardrop原理在有容量限制的交通网络中沿着两个方向被学者推广,形成了几种不同的广义网络均衡定义.在路径、路段上两种类型的容量限制下,通过对四种广义网络均衡进行比较,得到这些均衡解之间的相互关系;用反例说明广义均衡解集包含关系不成立的情况;得到这些广义均衡解的效率损失.     

有向循环图强连通度的下界

为简便计,本文采用文[1]中的定义和符号,而未说明的概念或符号引自[3].本文仅讨论有限、简单有向图. 有向图D=(V,A)称为强连通的,如果对D的任两顶点u与v,在D中同时存在(u,v)—有向路和(v,u)—有向路,C(?)V称为D的点割集,如果D—C非强连通或是单点.D的所含点数最少的点割集称为最小点割集,其阶数定义为D的强连通度,记为k(D)或k. 循环有向图D(n,S)定义如下:     

稳健交通均衡模型的SDP松弛

交通均衡问题在城市交通管理中具有重要意义.研究均衡交通的目的是通过对稳定交通流进行量化分析、,为决策者提供交通规划及管理的依据.Wardrop交通均衡原理是描述交通均衡问题的基石,本文在其扩展之一的稳健Wardrop(Robust Wardrop,简记为RW)互补均衡模型的基础上,将不确定因素的盒子约束改进为球约束,以改善原有模型的保守度.其次给出带有不确定因素的稳健Wardrop极小化形式及其确定性稳健对应模型(Robust Counterpart,简记为RC).最后通过SDP松弛手段将稳健对应模型(RC)松弛为容易的线性半定规划问题进行求解,并给出实例说明,为不确定因素影响下的交通均衡问题提供了一种新的有效模型及解法.     

常微分方程解的普遍唯一性定理和整体存在性定理(續)

(四) 整体存在性的一般定理现在我们讨论方程组(E)解的整体存在性问题。在这一节总假设方程(E)的右端函数f(t,x)在(n+1)-维实空间上定义且连续,并用记号f(t,x)∈C(E~(n+1))表示。今后规定模‖x‖表示。按照文[6]中微分方程组(E)的解整体存在的定义,这时我们说方程(E)的解整体存在,意思是指方程(E)的一切饱和解的定义区间都是(-∞,+∞)。定义2.我们称在实空间E~(n+1)中定义的连续可微的实函数v(t,x)是正的无限大函数,假如v(t,x)在空间E~(n+1)中恒取正值或者v(t,0)=0而v(t,x)> 定理3.设f(t,x)∈C(E~(n+1)),且对任意(t,x)∈E~(n+1)时满足不等式     

概率小议--兼谈广东省2004年高考第13题

1概率的统计定义:记某个随机事件为A,若在ǖ次彼此无关的试验(或观察)中出现了v次,则称Fǖ(A)=v/ǖ为随机事件A在ǖ次独立试验中出现的频率.     

超单严格循环设计的一些结果

主要研究基于(v,k,2)光正交码的最优超单严格循环填充,即(v,k,λ)-OSCP的存在性问题,解决了λ=2,3,4的(v,3,λ)-OSCP的存在性,得到了一些k≥4的(v,k,λ)-OSCP的无穷类.     

(3,2,1)-共轭r-正交拉丁方的存在性

如果两个v阶拉丁方L和M的重叠产生恰好r个不同的有序对,则称L和M是r-正交的.如果L还是M的(i,j,k)-共轭,则称L是(i,j,k)-共轭r-正交的,简记为(i,j,k)-r-COLS(v)((i,j,k)-r-conjugate orthogonal Latin square of order v),其中{i,j,k}={1,2,3}.本文研究(3,2,1)-r-COLS(v)的存在性问题.对于v 23,除去少数几个可能的例外值,本文给出关于(3,2,1)-r-COLS(v)的几乎完整的解.对于v23,如果r∈[v,v2]\{v+1,v+2,v+3,v+5,v+7,v2 1},除去可能的例外r=v2 3,都存在(3,2,1)-r-COLS(v).由于(3,2,1)-r-COLS(v)的存在性与(1,3,2)-r-COLS(v)的存在性是等价的,本文得到关于(1,3,2)-r-COLS(v)的同样结论.     

多参数指数族的逆Bhattacharyyà信息阵并应用于正态分布

本文进一步讨论多参数指数族中给定可估函数的 UMVUE 的方差计算问题.设定义于(X,B_X)上的 r.v.X 的分布为 P_θ,θ∈Θ.P_θ受某σ-有限测度μ(x)所控,称{P_θ,θ∈Θ)为自然指数族,是指     

问题与征解

问题 问题 13(供题者:北京大学 冯荣权,北京国际数学中心 许地生)定义n阶实矩阵A 范数为 (‖A‖= sup‖v‖=1‖Av‖),其中 ‖v‖ 表示n维向量v的范数.若A的元素都是整数,则称A为整矩阵.     

一类P-强制变分不等方程及其应用

:建立了变分不等方程〈Au,u - v〉 + j(u) - j(v)≤〈f ,u - v〉,　　 v∈ K的解的存在性定理 ,其中凸泛函 j(v)不必是半可加的 ,A是 j- P -强制算子 .并应用于Von Karman方程的障碍问题 .     

EXISTENCE OF STRONGLY VALID TOLLS FOR MULTICLASS NETWORK EQUILIBRIUM PROBLEMS＊

In this article,we consider the multiclass network equilibrium problems.A so called strongly valid toll can support any multiclass user equilibrium flow pattern as a system minimum when the system obje...     

Multiclass multicriteria mixed equilibrium on networks and uniform link tolls for system optimum

In this paper, we consider a unified framework of multiclass multicriteria mixed equilibrium, and the existence of uniform link tolls supporting such a mixed equilibrium as a system optimum. The network users are divided into different classes, and each class of traveler perceives his/her disutility associated with a route as a combination of two criteria given, respectively, by the travel time disutility and the time-irrelevant travel disutility. And users in a common class follow either user equilibrium (UE) principle or Cournot–Nash (CN) principle. A variational inequality model characterizing the multiclass multicriteria UE–CN mixed equilibrium behavior is developed. By utilizing the dual theory, we establish the existence of uniform link tolls supporting such mixed equilibrium as a system optimum.     

Solution approach to infinite linear programming problem with capacity constraints

The purpose of this article is to investigate a kind of infinite linear programming problem (ILPP) arising from infinite multiclass network equilibrium problems. In several cases, we construct special feasible solutions to the ILPP. By virtue of the nature of network, we prove that the solutions are optimal. Marcotte and Zhu (Oper Res Lett 37:211?C214, 2009) proved the existence of the valid tolls for the infinite multiclass network equilibrium problems. Based on this, we analyze the property of the tolls vector, i.e., the relationship between breakpoints and the tolls. We also consider the solutions in the network where origin-destination pairs may differ in their probability density functions.     

Existence and computation of optimal tolls in multiclass network equilibrium problems

In this work we provide a simple proof of the existence of optimal tolls for multiclass network equilibrium problems where the value-of-time parameter varies continuously throughout the population. The main argument, based on a finite-dimensional reformulation of the problem, also allows us to determine in a simple fashion revenue minimizing link toll vectors.     

Applications of sensitivity analysis for probit stochastic network equilibrium

Network equilibrium models are widely used by traffic practitioners to aid them in making decisions concerning the operation and management of traffic networks. The common practice is to test a prescribed range of hypothetical changes or policy measures through adjustments to the input data, namely the trip demands, the arc performance (travel time) functions, and policy variables such as tolls or signal timings. Relatively little use is made, however, of the full implicit relationship between model inputs and outputs inherent in these models. By exploiting the representation of such models as an equivalent optimisation problem, classical results on the sensitivity analysis of non-linear programs may be applied, to produce linear relationships between input data perturbations and model outputs. We specifically focus on recent results relating to the probit Stochastic User Equilibrium (PSUE) model, which has the advantage of greater behavioural realism and flexibility relative to the conventional Wardrop user equilibrium and logit SUE models. The paper goes on to explore four applications of these sensitivity expressions in gaining insight into the operation of road traffic networks. These applications are namely: identification of sensitive, ‘critical’ parameters; computation of approximate, re-equilibrated solutions following a change (post-optimisation); robustness analysis of model forecasts to input data errors, in the form of confidence interval estimation; and the solution of problems of the bi-level, optimal network design variety. Finally, numerical experiments applying these methods are reported.     

无限多类别网络均衡问题中的收费计算

对于一个多类别的网络均衡问题,可以通过计算某个辅助问题的容量限制约束相应的乘子向量得到有效收费.本文通过计算拉格朗日函数的鞍点来计算乘子向量.借助于广义拉格朗日函数的稳定性和Uzawa算法非精确解的收敛性,得到鞍点序列的收敛性.其中离散化方法用于最小化广义拉格朗日函数的计算.     

ATIS和道路收费下的混合随机用户均衡的效率损失

在ATIS作用下的交通网络中,用户在交通信息的接受程度上是异质的;考虑到装有ATIS的用户并不总是遵循ATIS的建议,因此,引入信息遵从率这一参数,将所有用户分为三类:安装并遵从信息、安装但不遵从信息和不安装的用户;均按照随机用户均衡的方式进行择路,但对出行时间有不同的感知。同时考虑存在道路收费的情形下,用户在时间价值上是异质的。综合考虑交通信息与道路收费的影响,基于用户两方面的异质性,对其进行合理分类,构建了多用户多准则的混合随机均衡模型及其等价的变分不等式;当收费不作为系统总成本的一部分时,建立了时间准则与费用准则下的系统最优模型;在此基础之上,分别研究了两种准则下混合均衡相对于系统最优的效率损失,给出了效率损失上界,并进一步分析了效率损失上界与各参数间的关系;交通管理者可以从道路收费策略的实施、信息诱导系统的完善等角度进行路网的改造和优化设计。     

Day-to-day evolution of the traffic network with Advanced Traveler Information System

Since the notion of user equilibrium (UE) was proposed by Wardrop [13], it has become a cornerstone for traffic assignment analysis. But, it is not sufficient to only ask whether equilibrium exists or not; it is equally important to ask whether and how the system can achieve equilibrium. Meanwhile, stability is an important performance in the sense that if equilibrium is unsustainable, both the equilibrium and the trajectory are sensitive to disturbances, even a small perturbation will result in the system evolution away from the equilibrium point. These incentive a growing interest in day-to-day dynamics. In this paper, we develop a dynamical system with Advanced Traveler Information System (ATIS) and study the stability of the network with ATIS. A simple network is used to simulate the model, and the results show that there exist periodic attractors in the traffic network in some cases (for example, the market penetration level of ATIS is 0.25 and traffic demand is 2 unit). It is found that the logit parameter of the dynamical model and the traffic demand can also affect the stability of the traffic network. More periodic attractors appear in the system when the traffic demand is large and the low logit parameter can delay the appearance of periodic attractors. By simulation, it can be concluded that if the range of the periodic attractors’ domain of the simple network is known, the road pricing based on the range of the attraction domain is effective to alleviate the instability of the system.     

Simultaneously optimizing link tolls and signal settings in a road network

The problem of determining link tolls to reduce traffic congestion is often referred as a toll design problem. In this paper, optimal tolls are determined for signal-controlled junctions in urban traffic road networks where the rerouting traffic is properly taken into account. This problem can be formulated as a mathematical program with equilibrium constraints (MPEC) where the user equilibrium is expressed as a variational inequality problem. Due to the non-differentiability of the equilibrium problem, an efficient convergent solution scheme is established. Numerical calculations are conducted on a variety of example road networks and comparisons are made with earlier methods.