区分障碍物特性的客车乘客疏散模型与分析

近年来,疏散性能评估已成为客车车厢设施布局及设计流程中的必要环节.考虑狭长通道下障碍物特性对人员疏散影响显著,引入感知域概念,刻画疏散人员翻越座椅等行为决策特性;进一步引入一类多值函数扩充元胞状态集合,量化障碍物的可翻越特性,建立障碍物模型,模拟紧急状态下人员无序疏散行为;为对模型结果验证分析,建立基本模型,构建其与AnyLogic®均可模拟的基本场景,在此场景下对二者模拟结果交叉验证.模拟分析结果及结论是,移动规则合理有效,结合障碍物模型并考虑可翻越障碍物影响的模拟结果是可信的;发现N k O -tk evac 曲线与此情形下的疏散动画具有一定的时空关联性,可为车体设计提供进一步参考;此外,随疏散人员感知域的增大,疏散时间逐渐减小.     

基于双重启发式动态规划算法的列车运行调整研究

通过对列车行车组织特点及运行调整策略的研究,采用自适应动态规划体系中的双重启发式动态规划算法,建立了列车运行调整模型.双重启发式动态规划算法适合处理具有实时性、约束性、非线性、随机性等特点的列车运行调整复杂动态系统的优化控制问题,通过仿真验证,该算法求解速度快、精度高,对列车晚点的调整起到了良好的控制作用.为列车运行调整的深入研究提供了一定的参考价值.     

船舶永磁电动机推进系统建模与仿真概述

本文简要介绍永磁电动机推进系统,以及用于永磁电动机推进系统的建模和仿真的工具,并给出永磁电动机船舶电力推进系统的Matlab/Simulink仿真实例.     

基于UML工作流模型的应用研究

分析了工作流模型的组成,根据统一建模语言的特点,形式化定义了为工作流过程建模的UML活动图结构以及建模规则,给出一个应用实例来描述建模过程并对模型作了详细分析。     

Spatial variation of roadside C2–C6 hydrocarbon concentrations during low wind speeds: Validation of CALINE4 and COPERT III modelling

The CALINE4 model is widely used to predict the effect of vehicle emissions on ambient concentrations close to roadways. It requires an evaluation of the rate at which different air pollutants are emitted by vehicles, taking into account things such as vehicle flow, velocity, type and age. For Europe the databases of the COmputer Program to calculate Emissions from Road Transport (COPERT) are combined with local vehicle details to obtain site-specific emission factors for dispersion modelling. The ability of CALINE4 to predict the spatial variation of hydrocarbon concentrations downwind of a motorway is assessed, as is the accuracy of COPERT III composite emission factors for several hydrocarbon compounds. The concentrations of seven traffic-associated compounds is found at three locations downwind and upwind of a motorway. Modelled and measured background-corrected downwind concentrations are compared on three bases: daily peak hour concentrations, mean concentrations, and a set of model evaluation parameters.     

基于Excel的红绿灯仿真控制决策

电子表格Excel具有强大的计算功能,它是一种可描述问题、建立模型、处理数据与求解的有效工具.汽车行驶到十字路口,受红绿灯控制,产生等待时间.利用Excel对此进行计算机仿真模拟,比较不同控制参数对控制目标的影响,可以找到相对较佳的方案.     

Validating the Passenger Traffic Model for Copenhagen

The paper presents a comprehensive validation procedure for the passenger traffic model for Copenhagen based on external data from the Danish national travel survey and traffic counts. The model was validated for the years 2000–2004, with 2004 being of particular interest because the Copenhagen Metro became operational in autumn 2002. We observed that forecasts from the demand sub-models agree well with the data from the 2000 national travel survey, with the mode choice forecasts in particular being a good match with the observed modal split. The results of the 2000 car assignment model matched the observed traffic better than those of the transit assignment model. With respect to the metro forecasts, the model over-predicts metro passenger flows by 10–50%. The wide range of findings from the project resulted in two actions. First, a project was started in January 2005 to upgrade the model’s base trip matrices. Second, a dialog between researchers and the Ministry of Transport has been initiated to discuss the need to upgrade the Copenhagen model, e.g. a switching to an activity-based paradigm and improving assignment procedures.     

Farm tractor models for research and development purposes

The modelling problems related to the simulation of the dynamics of farm tractors are dealt with. The aim is to develop reliable mathematical models to speed-up the research and development activities in which farm tractors and their sub-systems (driveline, steering and suspension system, etc.) are to be conceived and designed. Two models of farm tractors have been developed. The first model is based on a proprietary software, able to quickly simulate the motion of a vehicle on smooth or rough soil. The second model has been developed by the commercial software ADAMS/Car^®, which allows to model complicated transmission and suspension systems. In both of the two models, the tyres, the transmission system, the suspension system, the steering system, the engine and the body inertia are carefully described mathematically. Both of the two models are defined in a parametric way. Particular attention has been devoted to the measurements of the tyre characteristic and of the inertia parameters of the farm tractor body. For the measurement of tyre characteristics, a new instrumented wheel hub has been used. The accurate measurement of both the tyre characteristic and body inertia tensor has allowed a good agreement between measured and computed time histories referring to a number of validation manoeuvres performed either on-road or off-road. The derived farm tractor models could simulate the working conditions of a generic farm tractor while hauling a plough or while running at a relatively high speed on a rough soil or while steering on a sloped, soft surface.     

特大型桥梁群桩基础承载特性离心模型试验研究

苏通大桥超大型主桥索塔群桩基础置于第四系土层中,其承载变形特性是设计急待解决的技术问题。通过离心模型试验,研究了5种工况下主桥索塔群桩基础的竖向承载变形特性,分析了承台竣工、裸塔竣工、成桥阶段群桩基础的沉降及桩顶荷载分布规律。结果表明,5种工况下主桥索塔群桩基础的极限承载力大于5 000 MN,成桥阶段的总沉降为148~186 mm,基础整体稳定,桩顶荷载成W形分布,桩底注浆和冲刷形态对群桩基础的承载变形特性有一定影响。     

Simulating Demand-responsive Transportation: A Review of Agent-based Approaches

Abstract

In light of the need to make better use of existing transport infrastructure, demand-responsive transportation (DRT) systems are gaining traction internationally. However, many systems fail due to poor implementation, planning, and marketing. Being able to realistically simulate a system to evaluate its viability before implementation is important. This review investigates the application of agent-based simulation for studying DRT. We identify that existing simulations are strongly focused on the optimisation of trips, usually in favour of the operator, and rarely consider individual preferences and needs. Agent-based simulations, however, permit incorporation of the latter, as well as capture the interactions between operators and customers. Several areas of future research are identified in order to unify future research efforts.