Effects of the 80 km/h and variable speed limits on air pollution in the metropolitan area of barcelona

In 2008 the regional government of Catalonia (Spain) reduced the maximum speed limit on several stretches of congested urban motorway in the Barcelona metropolitan area to 80 km/h, while in 2009 it introduced a variable speed system on other stretches of its metropolitan motorways. We use the differences-in-differences method, which enables a policy impact to be measured under specific conditions, to assess the impact of these policies on emissions of NO_x and PM₁₀. Empirical estimation indicate that reducing the speed limit to 80 km/h causes a 1.7–3.2% increase in NO_x and 5.3–5.9% in PM₁₀. By contrast, the variable speed policy reduced NO_x and PM₁₀ pollution by 7.7–17.1% and 14.5–17.3%. As such, a variable speed policy appears to be a more effective environmental policy than reducing the speed limit to a maximum of 80 km/h.     

主动悬架用直线电机模型预测推力控制

针对主动悬架用直线电机高精度与高效率的控制需求，充分研究直线电机以及主动悬架动力学特性，建立直线电机驱动模型与主动悬架二自由度参考模型。为了改善传统直线电机直接推力控制的动态性能，提出一种改进的模型预测推力控制方法。该方法将逆变器产生的7个非零电压矢量作为备选矢量，并融合预测模型来计算出控制周期内的电机运行状态参数，基于成本函数最小值原理挑选出最优电压矢量，并将其作用于逆变器产生驱动电机所需的电压。为了解决数字控制系统的固有问题，提出延时补偿技术，保证对电机能够进行实时控制；对于逆变器开关频率不固定而引起的开关损耗等问题，通过在成本函数中加入开关频率项，在选择最优电压矢量的同时还降低了逆变器的整流频率与开关损耗；另外为了提高电机推力的效率以及减小推力与磁链波动，提出最大推力电流比与占空比优化控制技术，提高直线电机的动态控制性能。基于MATLAB/Simulink与dSPACE联合仿真，并搭建直线电机与主动悬架硬件测试平台，对所提出的控制方法进行验证，同时对主动悬架系统的动力学性能也进行了仿真与试验测试。试验结果表明：相较于传统的直接推力控制，所提出的控制策略使电机能够拥有更快的稳态速度、更小的电磁力与磁链波动以及更低的开关频率；各工况下，轮胎动载荷试验与仿真结果均方根值的相对误差分别为12.3%、4.47%、6.3%；悬架动行程试验与仿真结果均方根值的相对误差分别为10.3%、8.86%、10.6%；车身加速度试验与仿真结果均方根值的相对误差分别为6.23%、9.12%、7.2%。由计算结果可知，各评价指标的相对误差均在13%以内，验证了仿真结果的正确性，证明了模型预测推力控制对于提升电机与悬架动力学性能的有效性，能够实现对车辆悬架系统全局工况性能最优，协调控制悬架系统的动力学性能。     

国外光电有源干扰装备的发展

国外光电有源干扰装备在现代战争中发挥着越来越重要的作用。文章介绍了光电有源干扰技术的发展历程以及装备的研制、改进情况，指出了在现代战争中发展光电有源干扰技术的优势和重要性，重点探讨了几种光电有源干扰装备的性能及其特点，最后论述了光电有源干扰装备的发展动向与分析。     

物料搬运与设备选用

在整个物流过程,装卸搬运是不断出现和反复进行的活动。它的出现频率高于其他各种物流活动,同时每次装卸搬运都要占用很多的时间和消耗很多的劳动,装卸搬运管理的高低不仅成为决定物流速度的关键,而且是影响物流费用高低的重要因素。     

Active control strategy on a catenary–pantograph validated model

Dynamic simulation methods have become essential in the design process and control of the catenary–pantograph system, overall since high-speed trains and interoperability criteria are getting very trendy. This paper presents an original hardware-in-the-loop (HIL) strategy aimed at integrating a multicriteria active control within the catenary–pantograph dynamic interaction. The relevance of HIL control systems applied in the frame of the pantograph is undoubtedly increasing due to the recent and more demanding requirements for high-speed railway systems. Since the loss of contact between the catenary and the pantograph leads to arcing and electrical wear, and too high contact forces cause mechanical wear of both the catenary wires and the strips of the pantograph, not only prescribed but also economic and performance criteria ratify such a relevance. Different configurations of the proportional-integral-derivative (PID) controller are proposed and applied to two different plant systems. Since this paper is mainly focused on the control strategy, both plant systems are simulation models though the methodology is suitable for a laboratory bench. The strategy of control involves a multicriteria optimisation of the contact force and the consumption of the energy supplied by the control force, a genetic algorithm has been applied for this purpose. Thus, the PID controller is fitted according to these conflicting objectives and tested within a nonlinear lumped model and a nonlinear finite element model, being the last one validated against the European Standard EN 50318. Finally, certain tests have been accomplished in order to analyse the robustness of the control strategy. Particularly, the relevance or the plant simulation, the running speed and the instrumentation time delay are studied in this paper.     

三/单相平衡变换的铁路新型牵引供电系统的研究

提出了一种以有源功率补偿器核心的新型铁路牵引电系统，以解决现有牵引供电系统对电力系统造成的三相负载不平衡，功率因数低及谐波污染等问题，通过对三／单相负载的平衡变换分析，构造了系统模型，提出了ＰＷＭ控制方案，最后给出了仿真结果。     

汽车驾驶员主动安全性因素的辨识与分析

机动车驾驶为运输业中特殊工作,所以对该行业从业人员要求较高。安全驾驶旨为预防交通事故,确保行车安全。汽车驾驶安全性,不仅与汽车自身安全性能相关,而且与驾驶者行车中安全操控密不可分,通过一系列的措施增强驾驶者主动安全意识,可降低行车风险。基于此,有必要掌握汽车驾驶员素质对行车安全影响,了解事故发生的客观规律,提出针对性的预防措施,将各类不安全隐患遏制于萌芽时期,为行车安全做以保障。     

Effectiveness of using variable message signs to disseminate dynamic traffic information: Evidence from field trails in European cities

Variable message signs (VMS) can provide up‐to‐date traffic information and guidance to drivers through electronic signs at the roadside. The paper draws together the results from VMS field trials conducted in nine cities as part of European Union‐sponsored research projects carried out between 1994 and 1999. The projects followed common guidelines in carrying out field trial evaluations, which has enabled generalized findings to be made on the impacts of the different VMS applications. The main emphasis in the paper is on drivers' reactions to VMS and the impacts of VMS on road network efficiency. Results are reported for four different types of traffic information. For incident messages, it is not only the severity of the problem reported that influences the level of diversions, but also other factors such as the specific location mentioned and the availability of viable alternative routes to avoid the problem location. For route guidance information, it is demonstrated that substantial diversions occur when the route advice differs from that given normally. For continuous information describing the traffic state on a major route, information increases the use of the major route and reduces use of alternative routes if there are no traffic problems reported on the major route. Travel time information was well regarded by drivers and found to be effective in inducing route changes. In general, the deployments of VMS to inform drivers of traffic conditions have proved successful in terms of improving network travel times and reducing environmental impacts. Whilst such changes have been relatively small, driver perception of the benefits is much higher. This is potentially very significant in terms of the role that VMS can play in the development of integrated transport strategies, as the provision of information may encourage greater acceptance of a range of demand management measures.     

智能车辆主动避撞与稳定性联合控制仿真

为改善车辆在主动避撞过程中的车辆动力学特性,在MATLAB/Simulink环境下结合驾驶员模型分别设计了基于模糊控制理论的主动避撞控制处理器、制动稳定性控制器和转向稳定性控制器,从而能够在车辆主动避撞过程中综合考虑避撞和稳定性两个目标.并在ADAMS中建立了整车模型,联合MATLAB进行了仿真研究,仿真结果证明,在相...     

基于SPEA2的城市快速路速度引导多目标优化

基于速度引导控制作用下的城市快速路交通流扩展模型,建立了车辆总耗费时间与速度引导值变化幅度的多目标优化模型.采用强度Pareto进化算法(SPEA2)对比分析3种速度引导值确定方案,同时基于集合理论从Pareto 前沿中选择出最优解并确定最佳方案.在此方案下,应用Matlab进行了速度引导控制仿真分析,结果表明,速度引...