A parallel program for an urban-traffic analization and its evaluation

In this paper, we describe the traffic simulation system which analyzes a traffic flow in a road network. The system is constructed and operated on the parallel computer AP1000. A database of a road network is implemented with the object-oriented programming technique. Elements of a road network are regarded as objects, and vehicles which move on the lanes are regarded as attributive data. The database is divided into sub-databases and assigned to each processor. The system calculates the behavior of vehicles in parallel. Sending and receiving data among the objects are carried out with message passing on the communication network. Moreover, we show the results of the vehicles behavior, and evaluate the parallel efficiency.     

Cognition-Driven Traffic Simulation for Unstructured Road Networks

Dynamic changes of traffic features in unstructured road networks challenge the scene-cognitive abilities of drivers, which brings various heterogeneous traffic behaviors. Modeling traffic with these heterogeneous behaviors would have significant impact on realistic traffic simulation. Most existing traffic methods generate traffic behaviors by adjusting parameters and cannot describe those heterogeneous traffic flows in detail. In this paper, a cognition-driven trafficsimulation method inspired by the theory of cognitive psychology is introduced. We first present a visual-filtering model and a perceptual-information fusion model to describe drivers’ heterogeneous cognitive processes. Then, logistic regression is used to model drivers’ heuristic decision-making processes based on the above cognitive results. Lastly, we apply the high-level cognitive decision-making results to low-level traffic simulation. The experimental results show that our method can provide realistic simulations for the traffic with those heterogeneous behaviors in unstructured road networks and has nearly the same efficiency as that of existing methods.

     

面向对象方法在流化催化裂化动态系统仿真中的应用（Ⅱ） 面向对象程序设计和系统仿真

本文引入面向对象机制为流化催化裂化（ＦＣＣ）动态系统仿真问题求解建立了一个抽象通用的类层次，并应用ＴｕｒｂｏＣ＋＋面向对象程序设计语言开发了ＦＣＣ动态系统仿真程序。仿真模型采用９阶状态空间模型，仿真算法选择４阶Ｒｕｎｇｅ－Ｋｕｔｔａ方法，仿真曲线使用Ｂｏｒｌａｎｄ图形接口（ＢＧＩ）工具显示。仿真结果是令人满意的。作者认为，由于用面向对象程序设计语言编制的程序具有易阅读、易维修、易扩充和通用性强等优点，故用面向对象程序设计语言代替传统的过程式语言开发实际工业生产过程仿真软件，将使软件开发者和最终用户都受益非浅，它必将成为一种新的趋势。     

基于Agent的驾驶员-车辆建模研究与实现

微观交通仿真技术是解决城市交通网络拥塞问题的有效工具.在各种交通元素中,驾驶员-车辆单元是交通流的主体.该文通过对交通流中驾驶员、车辆特性的分析,将驾驶员和车辆视为一个整体,并基于Agent理论对之进行建模.文中详细分析了Agent的生成和路径搜索及选择算法,研究了Agent的跟驰、换道和挤占道等行为.该文最后介绍了基于Agent模型建立的一种微观交通仿真器,并在该仿真器上进行仿真实验.结果表明该系统能够较好的仿真实际交通流状况.     

高分辨率卫星影像车辆检测研究进展

高分辨率卫星遥感技术具有在更小的空间尺度上探测地表目标的能力,利用其影像数据进行车辆检测已成为新的研究热点。在概述遥感影像车辆检测研究现状的基础上,对车辆目标影像特征及车辆检测过程进行了探讨;将车辆检测方法分为利用光谱/几何结构特征的基本检测方法和综合运用多种特征的智能化检测方法,并详细叙述了多种车辆检测方法的原理与适用性以及车辆提取中的关键技术。通过分析发现：结合多特征的机器学习和面向对象的车辆检测方法更适合较复杂环境下的车辆检测。     

基于OD的微观交通发车仿真系统设计*

在分析了微观交通发车的一般流程和方法及微观交通仿真系统需求的基础上,设计了基于OD矩阵的微观发车仿真系统结构,分别应用GIS的思路、Floyd-Warshall算法和函数变换法实现了仿真系统中交通网络模块、道路路径模块和发车模块的功能,并介绍了OD矩阵模块和车辆模块的实现思路。最后采用面向对象的程序设计方法生成了符合仿真需求的运动车辆,为微观交通仿真系统的实现奠定了基础。     

Modeling and simulation of overtaking behavior involving environment

Overtaking is a complex driving behavior for intelligent vehicles. Current research on modeling overtaking behavior pays little attention on the effect of environment. This paper focuses on the modeling and simulation of the overtaking behavior in virtual reality traffic simulation system involving environment information, such as road geometry and wind. First, an intelligent vehicle model is proposed to better understand environment information and traffic situation. Then, overtaking behavior model is introduced in detail, the lane changing feasibility is analyzed and the fuzzy vehicle controllers considering the road and wind effect are researched. Virtual reality traffic simulation system is designed to realize the simulation of overtaking behavior, with realistic road geometry features. Finally, simulation results show the correctness and the effectiveness of our approach.     

An object-oriented approach for mechanical components design and visualization

In this paper, development of shape modeling tools for engineering design, analysis, simulation, and visualization is presented. The approach based on the idea of function-based shape modeling is combined with the power and versatility of the object-oriented programming (OOP). An OOP code, initially developed as a teaching and learning tool for educational use in an undergraduate Modeling and Simulation course, to generate mechanism components is presented. Different parametric, explicit, and implicit functions or their combination are used to generate mechanical components shapes. Using a blending process, sophisticated shapes have been generated on the graphical interface. However, the ideas and concept of the OOP mechanical components design presented in this paper can be applied to other application areas.     

A context-based object-oriented application framework for discrete event simulation

Applying object-oriented programming (OOP) to construct simulation programs has gained momentum in the research community. Major research efforts involved with object-oriented paradigm adopted in discrete-event simulation are reviewed in this paper, along with a simulation application framework proposed which provides special reusability mechanisms. This object-oriented simulation framework consists of three object elements, that is, model, service and scheduler. The relations and interactions among these elements are also demonstrated. In addition, the abstraction of a model under such a framework is reached by a special concept and implementation, referred to as the simulation context. Each simulation context is used to model a component sub-system, e.g. the control or physical flows of a manufacturing system. A practical system, CSIMT+ +, is also developed to validate the feasibility of such a simulation application framework. Furthermore, various forms of application models based on this framework are also illustrated.     

面向事实程序研究

本文针对面向对象程序的不足,根据奥地利语言哲学家路德维格·维特根斯坦（Ludwig Wittgenstein）关于世界和语言逻辑结构的哲学论述,并结合现实世界中对象能自动适应环境变化的特性,提出了一种以面向对象程序设计为基础并包含面向对象程序设计所有功能的新型程序设计语言--面向事实程序设计,并说明了该语言的特点、优点、结构和功能.     

A general framework for modeling shared autonomous vehicles with dynamic network-loading and dynamic ride-sharing application

Shared autonomous vehicles (SAVs) could provide low-cost service to travelers and possibly replace the need for personal vehicles. Previous studies found that each SAV could service multiple travelers, but many used unrealistic congestion models, networks, and/or travel demands. The purpose of this paper is to provide a method for future research to use realistic flow models to obtain more accurate predictions about SAV benefits. This paper presents an event-based framework for implementing SAV behavior in existing traffic simulation models. We demonstrate this framework in a cell transmission model-based dynamic network loading simulator. We also study a heuristic approach for dynamic ride-sharing. We compared personal vehicles and SAV scenarios on the downtown Austin city network. Without dynamic ride-sharing, the additional empty repositioning trips made by SAVs increased congestion and travel times. However, dynamic ride-sharing resulted in travel times comparable to those of personal vehicles because ride-sharing reduced vehicular demand. Overall, the results show that using realistic traffic flow models greatly affects the predictions of how SAVs will affect traffic congestion and travel patterns. Future work should use a framework such as the one in this paper to integrate SAVs with established traffic flow simulators.     

基于Python语言环境的轻量AOP工具的设计实现

作为众多成功开源软件产品之一的Python程序设计语言,其自身最具鲜明性的是“动态语言”特性与独特的“面向对象模型”系统。而AOP(面向方面编程)技术,作为OOP(面向对象编程)中解决代码耦合度问题的新技术思路,经历了若干年的研究探索后,已经在C 以及Java语言环境中被实现为实用工具。本文将尝试基于Python语言环境,利用其“动态语言”特性与的“面向对象模型”,设计实现一个轻量工具。     

基于编程对象与事件的车辆系统的仿真研究

该文采用对象的概念与方法编制了车辆动力学仿真程序,利用VB集成开发环境的丰富功能,编制了以事件触发为特征的车辆操纵仿真。将车辆及驾驶员模型用类模块封装的对象概念,用于实现人机交互性和描述多车辆复杂系统的仿真,给出了仿真实例,说明这种编程方法在智能型车辆控制仿真中具有很大的潜力与应用前景。     

车联网中RFID模型

RFID模型是车联网仿真的基础和核心模型之一. 目前交通仿真模型不能满足车联网无线通信及协同交互等方面的需求、且缺少RFID模型. 为此, 建立了RFID系统的读写器和电子标签模型. 给出了读写器Agent和电子标签Agent结构及实现. 根据自动机理论, 建立了读写器、电子标签和主机之间通信时异构通信协议数据帧格式的有限状态机模型, 解决了异构数据帧统一处理问题. 作为模型应用和验证实例, 基于VC++ 2010平台, 开发了RFID交通数据采集读写器优化布设仿真软件. 结果表明, RFID模型较好地逼     

一种基于分类回归树的无人车汇流决策方法

决策规划是无人驾驶技术中的重要环节.由于道路结构变化或障碍物引起的车辆被动换道多采用基于逻辑规则或优化算法的决策方式.本文以通行量为优化目标,提出一种基于分类回归树（Classification and regression tree,CART）的汇流决策方法.依据交通流参数,选择大量具有代表性的车辆汇流场景.对场景中车辆的汇流决策序列进行编码,采用遗传算法搜索使得通行量最大的决策方案.将寻优获得的大量汇流决策序列作为样本,训练分类回归树.选取车辆自身信息及与周围车辆的关系等以描述环境特征,运用分类回归树描述环境特征与决策结果的映射关系,获得一种通行量最优的汇流决策方法.在软件中进行仿真实验,对比既有方法,基于分类回归树的汇流方法能够有效减少汇流行为对车流的扰动,在大流量情形下依旧能保持较高的通行效率.此外,该方法对实际实施中可能存在的环境感知误差,如定位误差,有一定的鲁棒性.     

基于微处理器的车流量数据的检测与分析

本文提出了矩阵式红外线车流量识别这个全新的技术，利用微处理器，设计出了经济、高效、准确的车流量检测装置，能实现对被监测路段的车辆行驶方向、车型、多车并行、车流量统计等复杂情形的识别。这有利于获取道路交通情况，促进交通管理。     

城市交通系统的微观仿真研究

基于微观交通模型,将面向对象方法与可视化技术运用到城市交通系统的微观仿真研究中,开发了一套具有一定实用价值的交通仿真软件。仿真结果表明,车辆运行动画与人的直观交通经验一致。该方法可用于对一般的规模庞大的道路交通网络的研究。     

快速路网宏观交通流仿真系统的开发与仿直

为了给快速路网运行状况分析和控制策略评价提供高效辅助决策工具,提出快速路网宏观交通流仿真系统整体框架,分输入模块、仿真模块和输出模块三部分,并给出采用Microsoft Visual Basic面向对象语言开发的实现流程图和关键技术.仿真案例采用该系统对包含两个起点、两个终点的快速路网进行仿真,刻画交通拥挤的形成、传播...     

道路网元胞自动机交通流仿真研究

对于交通流移动对象的模拟,论述了现有模型的不足,并提出基于道路网的元胞自动机模型（RN-CA）。该模型不仅模拟移动对象在交通流中的行为,还引入不同类型道路和车辆情况下的发车、跟车、超车和矫正模型,使模拟更精确、可靠。采用Dijkastra算法,综合考虑道路长度、车道数、流量、平均速度等因素动态计算最优行驶路径。对于行车时间预估,采用模拟加预估的方式,综合考虑当前和历史路况。为了改进系统的性能,系统采用可调节线程数目的模拟方式。     

Foresee,a fully distributed self-organized approach for improving traffic flows

Based on traffic data acquisition by the vehicles and inter-vehicle wireless communications, road traffic self-organization has been studied for several years. In this paper we propose a generic model of cooperation among vehicles, which is designed not to saturate the communication medium and to be insensitive to information loss among vehicles. We also propose an original software simulator, which helps us to show how this model can be used in realistic traffic situations. In the simulation, we evaluate one instance of our model, which features an algorithm for limiting the risks of information storms. This feature is particularly interesting in urban settings, where radio communication must fit within the traditional IEEE-802.11 traffic. We show that this algorithm can considerably reduce the amount of communication, without affecting the quality of traffic self-organization.