Out-Door Air Pollution Levels in Vehicular-Traffic Junctions in Nsukka Metropolis, Enugu Metropolis and Awgu Semi-Urban Area in Enugu State, Nigeria

Studies were carried out to investigate the outdoor air pollution levels in vehicular traffic junctions in the major cities of Nsukka, Enugu and semi-urban area of Awgu all in Enugu State, Nigeria using standard analytical procedures. PM2.5 was collected using Envirotech air sampler, APM 550 and analyzed gravimetrically. Other determined air pollutant gases such as SO2, NO2, O3 and CO were analyzed using colorimetric techniques. The mean hourly traffic density in the vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu were 2015, 2873 and 587 respectively. The mean range of values of PM2.5, NO2, SO2, O3 and CO in vehicular traffic junctions within the investigated environments were 1.67 - 12.16 μg/m3, 3.72 - 23.83 μg/m3, 2.96 - 30.09 μg/m3, 5.45 - 66.54 μg/m3 and 1.18 - 15.17 ppm respectively. The mean levels of the determined air pollutants in the air around vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu semi-urban area differed significantly. The mean levels of PM2.5, and CO in the air around vehicular traffic junctions in Enugu metropolis and CO in the air around traffic junctions in Nsukka metropolis were above the recommended permissible limits. Traffic density was therefore seen as the single most important factor contributing to the varying air pollution levels observed in the investigated environments.

Emission profiling of diesel and gasoline cars at a city traffic junction

In congested urban roads, cars must stop at intersections because of city traffic lights. As a result, pedestri- ans and traffic police personnel are exposed to pollutants emanating from the tailpipe of various vehicles at such city trafficjunctions. In this study, various gasoline- and diesel-fueled cars complying with differ- ent emission standards were tested for their emissions in simulated city traffic junction conditions. The engine exhaust from these cars was subjected to physicochemical characterization at different engine speeds under no-load conditions. These engine conditions were chosen because the cars idle at differ- ent engine speeds at a city traffic junction. Gravimetric and real-time measurements were performed for the tailpipe exhaust sampled from these vehicles. Exhaust particles were collected on 47 mm diameter quartz filter papers and subjected to gravimetric analysis for determining the total particulate mass （TPM） and trace metals while the engines were operated at two different engine idling speeds, 1500 rpm （representing low idling） and 2500 rpm （representing high idling）. At similar engine operating condi- tions, TPM and trace metals were lower for the exhaust from gasoline engines compared to the exhaust from diesel engines. Real-time measurements were performed for particle-bound poly-aromatic hydro- carbons （PAHs）, particle number and size distribution, regulated gaseous emissions and smoke opacity of the exhaust at four different engine speeds, 1500, 2000, 2500, and 3000 rpm. Particle-bound PAHs showed a decreasing trend for the vehicles that complied with stricter vehicular emission standards. Higher particle peak number concentrations were observed for diesel exhausts compared to the results for gasoline exhaust. Regulated gaseous emissions were also comoared.

Theoretical investigation of synchronous totally asymmetric simple exclusion process on lattices with two consecutive junctions in multiple-input-multiple-output traffic system

In this paper, we study the dynamics of the synchronous totally asymmetric simple exclusion process （TASEP） on lattices with two consecutive junctions in a multiple-input-multiple-output （MIMO） traffic system, which consists of m sub-chains for the input and the output, respectively. In the middle of the system, there are n （n 〈 m） sub-chains via two consecutive junctions linking m sub-chains of input and m sub-chains of output, respectively. This configuration is a type of complex geometry that is relevant to many biological processes as well as to vehicular traffic flow. We use a mean-field approach to calculate this typical geometry and obtain the theoretical results for stationary particle currents, density profiles, and a phase diagram. With the values of m and n synchronously increasing, the vertical phase boundary moves toward the right and the horizontal phase boundary moves toward the upside in the phase diagram. The boundary conditions of the system as well as the numbers of input and output determine the no-equilibrium stationary states, stationary-states phases, and phase boundaries. We use the results to compare with computer simulations and find that they are in very good agreement with each other.

Traffic Flow Merging and Bifurcating at Junction on Two-Lane Highway

In this paper we study the traffic states and jams in vehicular traffic merging and bifurcating at a junction on a two-lane highway. The two-lane traffic model for the vehicular motion at the junction is presented where a jam occurs frequently due to merging, lane changing, and bifurcating. The traffic flow is called the weaving. At the weaving section, vehicles slow down and then move aside on the other lane for changing their direction. We derive the fundamental diagrams (flow-density diagrams) for the weaving traffic flow. The traffic states vary with the density, slowdown speed, and the fraction of vehicles changing the lane. The dynamical phase transitions occur. It is shown that the fundamental diagrams depend highly on the traffic states.

基于PLC的多路口交通灯控制系统的设计

PLC可编程序控制器是以微处理器为基础,结合计算机、自动控制及通信等先进的工业控制设备,凭借构造简洁、程序编制简便、工作稳定可靠等特点,被广泛应用于生产生活中。PLC、机器人、CAD/CAM是现代工业自动化的三大支柱,PLC对作业环境的适应能力较高,在红绿灯控制中运用广泛,可有效减少排队等待时间,达到科学管理的目的。采用EDA技术对交叉口信号灯闪烁和车流进行仿真,展示可编程逻辑控制器在信号灯控制中的应用。通过编写组态程序使人们对PLC和MCGS的使用有更深层次的了解。通过PLC开发令管理人员更好地利用PLC对现场信息进行采集及控制,从系统设计、梯形图设计到组态设计,再到现场测试,全面掌握PLC的设计流程,为工程项目产品开发及设计提供参考。

天津站交通枢纽轨道换乘中心工程岩土工程勘察

研究目的:天津站交通枢纽轨道换乘中心工程为一深大基坑工程,工程结构、地质条件、环境条件都极为复杂,采用适宜的勘察方法、提供合理的设计参数、提出科学的岩土工程评价和措施是工程建设的重要环节。研究结果:通过采用地质钻探、原位测试和室内外试验等综合勘察方法,查明了场地的工程地质和水文地质条件,提出了各项水土参数,并对场地的稳定性和适宜性、基坑围护结构型式、基坑坑底隆起和管涌、结构抗浮、降水控制等岩土工程问题进行了分析评价,提出了有针对性的工程措施意见,为设计和施工提供了科学依据。

一种基于分布式网络多智能体的匝道协同控制方法

针对高速公路与城市快速路交汇区域(路网结合部)拥堵日益严重的现状,综合考虑异构交通网络的通行能力与转换需求,基于多智能体和局部感应控制思想,对路网结合部匝道控制模式进行分析,建立单点CPSO-RBF-PID匝道控制模型、关联主线多匝道一致性协同方法和不同主线间匝道竞争性协同方法.在此基础上,将路网结合部进行网络拓扑,建立基于分布式网络多智能体的匝道协同控制方法.并选取相应路网结合部对所建模型进行验证,结果证明,该模型具有良好的控制效果,能够起到有效地稳定路网结合部交通流密度,缓解结合部区域交通拥堵的作用.

城市交通时间最短路径计算模型及应用仿真

研究道路状态信息和路口固定延迟模型优化问题,城市交通时间最短路径(T'DSP)是统计意义上的最优路径,对个体车辆而言并非最优,主要原因在于没有考虑车辆通行与交通信号的时空相位关系。通过对上述关系的研究,提出了基于交通信号的路口延迟和时间最短路径(TLBSP)的计算模型及改进Dijkstra算法,适用于现有主要交通网络和交通规则,能实现交通信号控制下各车最短时间路径的计算。实验结果表明,TLBSP算法的时间最短路径优于距离最短路径算法和固定延时的TDSP算法,改进算法可应用于城市交通导航,能促使车辆在空间上合理分布,有利于缓解城市交通拥堵。

MAS协商在交通运输企业中的应用

结合计算机协同与集成技术发展 ,研究计算机协同中的 MAS多个智能体技术在交通运输组织管理中的应用 ,探索性地给出一种解决综合交通枢纽内多个运输企业利益关系的

城市交通枢纽的规划要点

随着城市化进程的加快,我国的各大城市开始大规模建设城市交通枢纽,急需相对应的规划理论和方法的支持。在此背景下,重点研究了城市交通枢纽的基本概念、功能和发展现状,结合西直门枢纽的实际情况,分析了城市交通枢纽规划的影响因素、基本原则,总结了城市交通枢纽的基本规划方法,并提出了在城市交通枢纽规划中应注意的关键问题。

关于轨道交通需求预测与城市客运交通枢纽关系的研究

城市交通由多种交通方式构成 .城市居民的出行 ,往往是多种交通方式的组合过程 .因此 ,各种交通方式之间换乘的组织 ,决定了 1个城市客运交通体系的水平 .结合我国城市交通发展的实际 。

基于GIS的城市交通网络要素可视化表达方法研究

城市交通网络要素的可视化表达是GIS—T研究和应用领域中的一个难题,本文在对目前流行的交通网络数据模型进行系统研究的基础上,选择了动态分段技术下的结点-弧段模型,对交通网络复杂要素进行可视化表达,并对城市交通网络要素的可视化表达方法和形式进行了分析,最后结合交通网络复杂要素的可视化表达,设计和创建了具体的数据结构表和数据结构图。

城市轨道交通与其它交通方式衔接的研究

从线路和车站相互关系的角度 ,分析和论述了城市轨道交通规划中 ,该系统与其它交通衔接的方式及技术问题 ,并给出了国外在这方面比较好的做法 ,为我国城市轨道交通的规划提出了具有积极借鉴意义的方向 .

天津港北航道与主航道交汇水域通航风险评估

以连续72 h观测的天津港北航道与主航道交汇水域交通流量统计数据为样本,对交汇水域船舶到达规律进行研究.研究结果表明交汇水域船长大于180 m的船舶到达规律服从负二项分布.并在此基础上对船长大于180 m的船舶同时到达交汇水域的可能性进行研究,预计到2010年,2条船同时进入交汇水域的概率最大为6.2%,5条船同时进入交汇水域的概率最小为1.6%.

道路平面交叉口通行能力的延误分析法

提出了道路交叉口通行能力延误分析法的基本原理，并详细阐述了道路交叉口延误曲线的确定方法（现场观测法、数学模型法及计算机模拟法），讨论了道路交叉口服务水平的划分标准；提出了道路交叉口各级服务通行能力的确定方法。最后，文章建立了基于延误曲线的道路交叉口通行能力修正模型，包括道路条件修正及交通条件修正。

铁路枢纽车流组织的非线性0-1规划模型及算法

分析铁路枢纽车流组织问题的背景、特点及优化目标 ,给出铁路枢纽车流组织所需的构模参数 ,梳理与路网联系的车流类型及结构 ,综合考虑直通、改编、地方车流的作业过程 ,建立基于铁路枢纽资源约束的非线性0 - 1规划模型 ,并将遗传算法应用于该问题的寻优过程。

信号交叉口通行能力计算方法适用性研究

介绍我国常用的两种计算信控交叉口通行能力的方法,以两个典型十字交叉口为例,计算交叉口的通行能力,以交叉口饱和度为评价指标,对两种计算方法结果进行对比分析,适用于不同交通条件和交通流量的通行能力计算方法,旨在探讨各种方法的优缺点及适用范围。

行人过街信号控制路口交通噪声预测模型

分析了行人过街信号控制路口交通流的运行特性,根据能量叠加原理建立了行人过街信号控制路口交通噪声预测模型(以下简称信号控制路口模型)。将实测交通噪声数据分别与信号控制路口模型的预测值及只考虑车辆匀速行驶的长直道路交通噪声预测模型的预测值进行对比,结果表明,信号控制路口模型更能正确反映路口实际交通噪声的空间分布。最后利用该模型对行人过街信号控制路口附近的交通噪声分布进行计算,得到了噪声空间分布的若干规律。

结合部区域入口匝道协调控制模型

针对进出城市的高速公路与关联城市快速路(简称结合部区域)交通拥堵日益恶化的现象,以结合部区域为研究对象,从结合部区域的匝道控制影响因素分析入手,建立了一种适用于结合部区域的单点入口控制模型和多入口匝道协调控制模型,以京津塘高速公路与北京市三环、四环的结合部区域为例,以实地调研及交通流检测数据为基础,通过仿真验证其有效性,为匝道协调控制实际应用提供理论方法.

水上交通冲突技术在船舶定线制警戒区中的应用

针对以分道通航制为主的船舶定线制没能很好地解决各主要交通流汇集区域的船舶会遇问题,结合船舶定线制航道交叉口与道路平交路口的相似性,引入交通冲突相关研究方法,并将其与水上交通已有的概念结合,进行船舶定线制警戒区的安全研究。通过船舶定线制航道交叉口交通流冲突的研究,对局部水域的安全状况进行评价,寻找改善措施,减少警戒区交通冲突的发生,降低事故率,减轻事故严重程度,从而改善船舶定线制交通流复杂水域交通安全状况,并为优化船舶定线制的设计方案提供参考。