上海世博集约交通的实践与启示

为应对大规模、长时间、高强度的世博客流,世博会交通运行方案以集约化模式为主导,在没有实施强制性交通管控的前提下,世博交通组织及全市日常交通平稳有序、运行效果良好.通过分析世博游客出行特征及世博会期间对外交通、道路交通、轨道交通的运行特征,从设施建设、交通管理、配套政策、交通服务等方面总结世博集约交通的实践经验.借鉴世博...     

交通信息对驾驶员逐日路径选择行为影响研究

在无信息、发布历史信息和发布预测信息3种信息条件下,分别建立了驾驶员的路径理解行程时间期望值的更新模型.通过建立一个含有2条平行路径的简单路网,对3种交通信息条件下驾驶员逐日路径选择进行了仿真,结果表明:交通信息对驾驶员的作用与驾驶员路径选择的随机程度和对信息依赖程度有关;在3种交通信息条件下,路网均不能达到用户均衡平衡状态;交通信息的预测方法不同,预测信息对驾驶员路径选择的影响有差异.     

基于ASP.NET的专业气象服务系统的权限控制实现

使用ASP.NET提供的HttpModule技术,对用户提交的Http请求进行解析.辅以合理的权限数据库结构设计,实现了专业气象服务网站的权限分配和管理.在实际开发过程中,通过权限数据库来动态生成导航菜单及其级联菜单,使得用户的权限分配和管理变得更加灵活、高效.     

Cost and User Profile of a Coastal Ocean Observing System

Fundamental to sustaining the financial support of a coastal ocean observing system is an intimate knowledge of users and their decision-making processes in order to maximize the worth of ocean observations to them. This article explores the evolving mission of GoMOOS (the Gulf of Maine Ocean Observing System), its costs of providing near real-time observations and observing products, possible methods to assess the benefits of an ocean observing system, and a method for indexing the importance—and thus, potentially, the economic value—that users attach to these observations and products.     

有限元示范库多媒体系统的设计与实现

在Ｗｉｎ９５／Ｗｉｎ９８平台上，采用ＨＴＭＬ语言设计实现了有限元示范库多媒体系统。从系统结构、用户界面设计、关键技术等方面，介绍了该系统的功能及特点。     

Using the revenues from congestion pricing

The economic theory behind congestion pricing relies on using the revenues to help compensate highway users. But can practical methods of using revenues come close to achieving this compensation, and still have salient appeal to important political groups? This paper investigates the possibilities for designing a package of revenue uses that can achieve these twin goals. The suggested approach returns two-thirds of the revenues to travelers through travel allowances and tax reductions, and uses the rest to improve transportation throughout the area, including affected business centers. By replacing regressive sales and fuel taxes, this approach offsets the tendency of the prices alone to have a regressive distributional impact. By lowering taxes, funding new highways, improving transit, and upgrading business centers, the package provides inducements for support from several key interest groups. The potential amounts of money involved are discussed using nationwide data, and in more detail using a case study of ubiquitous facility pricing throughout the Los Angeles region. Illustrative calculations of the effects on various individuals confirm that such a package can create net benefits for a wide spectrum of people and interest groups.     

A capacity restraint transit assignment with elastic line frequency

This paper proposes a new formulation for the capacity restraint transit assignment problem with elastic line frequency, in which the line frequency is related to the passenger flows on transit lines. A stochastic user equilibrium transit assignment model with congestion and elastic line frequency is proposed and the equivalent mathematical programming problem is also formulated. Since the passenger waiting time and the line capacity are dependent on the line frequency, a fixed point problem with respect to the line frequency is devised accordingly. The existence of the fixed point problem has been proved. A solution algorithm for the proposed model is presented. Finally, a numerical example is used to illustrate the application of the proposed model and solution algorithm.     

A link-node complementarity model and solution algorithm for dynamic user equilibria with exact flow propagations

In this paper, we propose a link-node complementarity model for the basic deterministic dynamic user equilibrium (DUE) problem with single-user-class and fixed demands. The model complements link-path formulations that have been widely studied for dynamic user equilibria. Under various dynamic network constraints, especially the exact flow propagation constraints, we show that the continuous-time dynamic user equilibrium problem can be formulated as an infinite dimensional mixed complementarity model. The continuous-time model can be further discretized as a finite dimensional non-linear complementarity problem (NCP). The proposed discrete-time model captures the exact flow propagation constraints that were usually approximated in previous studies. By associating link inflow at the beginning of a time interval to travel times at the end of the interval, the resulting discrete-time model is predictive rather than reactive. The solution existence and compactness condition for the proposed model is established under mild assumptions. The model is solved by an iterative algorithm with a relaxed NCP solved at each iteration. Numerical examples are provided to illustrate the proposed model and solution approach. We particularly show why predictive DUE is preferable to reactive DUE from an algorithmic perspective.     

交通信息服务系统建设和发展新模式

在新一代信息技术环境下,探讨交通信息服务系统建设和发展的新模式.针对现有交通信息服务系统发展的特点,分析了交通信息服务系统现有建设模式以及移动互联网、智能手机的发展现状,探讨了其中存在的问题.分析结果显示:数据资源整合难度大、后期运维资金不足等问题,严重影响了交通信息服务系统的服务水平以及可持续发展的能力.通过对新形势下的交通信息服务系统发展进行分析,指出当前人们对交通信息服务系统的需求发生了变化,移动互联网的发展也有了新的特点和趋势,原有的以政府为主导、以政府职能为核心的交通信息服务系统建设模式已经不能适应移动互联网技术环境下交通信息服务系统可持续发展的要求,并由此得出结论:面向新技术、新需求,交通信息服务系统必将转变为社会多方力量合作的、以用户需求为核心的建设模式.     

采用多模Turbo编解码器增加CDMA系统用户容量

随着移动用户数量的迅速增加,CDMA系统的容量面临巨大压力。以往Turbo编解码器在CDMA系统中仅用于信道编码,本文则提出采用多模Turbo编解码器增加CDMA系统用户容量。这一方案是基于码分多址与本文提出的Turbo编解码滤波技术。在一个CDMA小区中,基站用K个Turbo编解码器将用户分成K个不同的用户群,每一群的用户可使用小区的全部N个扩频码,采用匹配滤波器组检测同一群内的不同用户。因此,一个小区的用户数量可以增加为原来的K倍。仿真验证该方法是有效的。