共查询到20条相似文献,搜索用时 174 毫秒
1.
2.
目前,机动车尾气污染已经逐渐取代燃煤污染而成为影响城市空气质量的主要因素。利用道路扩散模型研究机动车尾气扩散规律,可为城市道路大气污染的监测、评价与防治提供科学依据。介绍城市道路污染概况及影响污染物排放的因素,分别以排放因子模型和污染物扩散模型对道路模型进行综述,重点阐述该道路模型的特点及其在我国的应用现状,并展望道路大气污染防治发展方向。 相似文献
3.
4.
5.
随着城市汽车拥有量的急剧增加,现在国内城市大气污染的主要原因已转变为汽车尾气排放。据环保部数据测算,“十二五”期间我国还将新增机动车—亿辆左右,新增汽柴油消耗量1亿至1.5亿吨。随着车辆的增加,汽车与城市环境之间的矛盾越来越尖锐。有关环保专家认为,机动车尾气是城市空气的最大污染源,汽车尾气的排放污染是当前和今后一段时期控制空气质量最突出、最紧迫的问题。 相似文献
6.
7.
8.
随着我国汽车保有量的逐年增加.机动车尾气排放已成为中国大、中城市大气污染的主要污染源之一。据有关部门统计,目前北京、上海、天津、重庆等城市汽车排放污染已占市区大气污染的60%以上。为此,我国各大、中城市相继出台了控制汽车尾气排放的有关规定.这在一定程度上缓解了城市大气污染的进一步恶化。但是,就汽车对环境的污染而言,主要表现在汽车噪声和汽车尾气排放的两个方面.污染程度取决于汽车的技术状况和汽车的使用与维护。 相似文献
9.
随着社会经济和城市建设的迅速发展,机动车保有量急剧增加,造成交通拥堵问题日益严重,同时也导致了更为严重的交通污染问题。随着机动车尾气排放污染的日益加剧,对其研究也越来越广泛和深入。关于尾气排放的研究大致可以分为2个方面:(1)机动车尾气排放研究,从微观层面、中观层面、宏观层面对其进行研究,包括尾气排放获取数据的方法、机动车行驶周期及尾气排放模型的研究。(2)机动车尾气扩散研究,主要是其扩散模型的研究。此外排放控制策略研究也越来越受到重视,其研究趋势逐步由针对发动机改进等降低单个车辆的排放发展到整个路网的排放量改善的交通控制管理措施。 相似文献
10.
为了对新建城区交叉口行人-机动车分相位临界条件进行定量分析,运用行人-机动车阻滞机理和抢行博弈模型等相关理论,得到了完整的阻滞时间计算模型;结合右转车辆与行人等饱和度时平均延误最小的思想,对信号周期内机动车与行人的分相位设置临界状态建立数学模型,提出了新建城区交叉口行人-机动车分相位安全评价方法。结果表明:行人-右转机动车冲突是新建城区交叉口冲突的主要形式,根据分相位量化条件可将危险交叉口细分为分设临界交叉口和时时监控交叉口。 相似文献
11.
近十余年来,随着我国社会经济的飞速发展和城市化进程的加快,城市水污染不断加剧,城市水环境持续恶化,市郊结合部、尤其是城中村绝大部分河道受污染情况严重,地表水水质普遍劣于V类标准,一些水体甚至出现了黑臭现象.马漳河是该类河道的典型,通过对马漳河黑臭成因分析,找出存在的问题,提出消除黑臭河道的治理对策和措施,整治后面貌焕然... 相似文献
12.
路段上集群智能网联汽车的车队形成机制 总被引:1,自引:0,他引:1
智能网联汽车是解决城市交通问题的关键技术之一,对于未来城市智能交通体系建设有着关键作用。集群的智能网联汽车已经具备了涌现的基本条件,设计科学合理的交互规则,可以实现车辆的自组织,分布式涌现控制。以微观仿真软件VISSIM及C2X模块为研究平台,修改驾驶模型参数,在C2X模块中编程实现3条交互规则:速度一致、尽量靠近、避免碰撞,在仿真软件中构建单车道仿真模型,运行仿真实验,统计车辆在路段上不同距离形成车队情况,利用车头时距分布的熵值来衡量车流的有序性。仿真结果表明,车辆在运行至50s后初步形成车队,随着时间的增加,形成的车队越稳定,车流熵值在路段上随距离增加而减小,说明形成车队后更加有序,在路段上呈现出涌现现象。 相似文献
13.
14.
15.
16.
With the transfer of rural population to cities, the municipal engineering construction is becoming more and more rapid, in which the investment in the urban roads convenient for citizens to travel and transport is increasing year by year. With the increasing frequency of the use of municipal roads, the signings and markings playing the role of warning and indication expose some problems that need to be solved urgently, which seriously affect the function and comfort of municipal roads. Based on a detailed analysis of the existing problems and impacts of the signings and markings of municipal road engineering in China, the targeted improvement measures are proposed to ensure the perfection of the functions of signings and markings and improve the efficiency of vehicle traffic, which escort the safety, convenience and comfort of municipal road engineering. 相似文献
17.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(4):587-601
Dynamic instability, that is, resonance, may occur on an electromagnetic suspension-type Maglev that runs over the elevated guideway, particularly at very low speeds, due to the flexibility of the guideway. An analysis of the dynamic interaction between the vehicle and guideway is required at the design stage to investigate such instability, setting slender guideway in design direction for reducing construction costs. In addition, it is essential to design an effective control algorithm to solve the problem of instability. In this article, a more detailed model for the dynamic interaction of vehicle/guideway is proposed. The proposed model incorporates a 3D full vehicle model based on virtual prototyping, flexible guideway by a modal superposition method and levitation electromagnets including feedback controller into an integrated model. By applying the proposed model to an urban Maglev vehicle newly developed for commercial application, an analysis of the instability phenomenon and an investigation of air gap control performance are carried out through a simulation. 相似文献
18.
19.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(10):1287-1304
For electromagnetic suspension (EMS) type urban Maglev vehicles using a U-shaped electromagnet, the levitation and guidance forces are generated by only one electromagnet. Although the levitation force is actively controlled by changing the voltage of the electromagnet, the guidance force is passively determined by the levitation force. In addition, the curve negotiation performance of EMS-type urban Maglev vehicles using a U-shaped electromagnet must be considered, because an urban guideway may have some curves with shorter radii. It is, therefore, necessary to predict the curving performance with the greatest accuracy possible, in order to improve electromagnetic suspension and establish guideway design specifications. The objective is to establish a new dynamic modelling technique, so as to achieve more realistic curving simulation and thus to more accurately evaluate the curving performance of an EMS-type Maglev vehicle. The use of a full vehicle multibody dynamic model is proposed, and is applied to the evaluation of curving performance. Design changes are also investigated to obtain the bogie design directions for minimising variation in the lateral air gap, which is a criterion for curving performance. 相似文献
20.
车辆换道行为因其运行环境复杂,所涉及的交通因素众多,容易引起交通冲突,从而降低道路交通系统的安全性.对车辆换道行为的动态特性及其对车流运行的影响机理进行建模与研究,对提高交通系统的运行效率有重要意义.基于城市道路车辆换道行为的特征,改进了元胞自动机模型细化车辆换道过程;考虑驾驶员特性、车辆类型的影响,采用模糊推理理论描述驾驶员的换道决策,进而建立了城市道路驾驶员主观换道模型.通过将实测交通流数据与仿真输出数据进行对比,验证模型的有效性.结果表明,所建立的模型输出结果与实测数据的误差较小,说明模型具有一定的有效性. 相似文献