Fuel economy of hybrid-electric versus conventional gasoline vehicles in real-world conditions: A case study of cold cities in Quebec,Canada

This paper investigates the fuel efficiency of commercial hybrid electric vehicles (HEVs) and compares their performance with respect to standard gasoline vehicles in the context of cold Canadian urban environments. The effect of different factors on fuel efficiency is studied including road driving conditions (link type, city size), temperature, speed, cold-starts and eco-driving training. For this study, fuel consumption data at the link level in real-world conditions was used from a sample of 74 instrumented vehicles. From the study fleet, 21 vehicles were HEVs. Among other results, the beneficial fuel efficiency merits of hybrid vehicles were demonstrated with respect to gasoline cars, in particular at low speeds and in urban (city) environments. After controlling for other factors, sedan HEVs were 28% more efficient than sedan gasoline vehicles. However, the low temperatures (below 0 °C) observed regularly during winter season in the study cities were identified as a detrimental factor to fuel economy. In winter, the fuel efficiency of HEVs decrease about 20% with respect to summer. Other factors such as eco-driving training, city size, cold start and vehicle type were also found to be statistically significant.     

地铁车辆配置中的新技术运用

介绍重庆地铁车辆的配置以及不同于一般地铁车辆的技术特点,包括车地配合的再生制动能量吸收系统、轻快型无摇枕空气弹簧转向架、轴盘加踏面的基础制动配置、全列车交叉混合制动、第四代乘客信息显示系统等。实践表明,经过一段时间的运行考验,这些新技术收到明显的效果。     

Exact and meta-heuristic approach for a general heterogeneous dial-a-ride problem with multiple depots

Dial-a-ride problems are concerned with the design of efficient vehicle routes for transporting individual persons from specific origin to specific destination locations. In real-life this operational planning problem is often complicated by several factors. Users may have special requirements (e.g. to be transported in a wheelchair) while service providers operate a heterogeneous fleet of vehicles from multiple depots in their service area. In this paper, a general dial-a-ride problem in which these three real-life aspects may simultaneously be taken into account is introduced: the Multi-Depot Heterogeneous Dial-A-Ride Problem (MD-H-DARP). Both a three- and two-index formulation are discussed. A branch-and-cut algorithm for the standard dial-a-ride problem is adapted to exactly solve small problem instances of the MD-H-DARP. To be able to solve larger problem instances, a new deterministic annealing meta-heuristic is proposed. Extensive numerical experiments are presented on different sets of benchmark instances for the homogeneous and the heterogeneous single depot dial-a-ride problem. Instances for the MD-H-DARP are introduced as well. The branch-and-cut algorithm provides considerably better results than an existing algorithm which uses a less compact formulation. All seven previously unsolved benchmark instances for the heterogeneous dial-a-ride problem could be solved to optimality within a matter of seconds. While computation times of the exact algorithm increase drastically with problem size, the proposed meta-heuristic algorithm provides near-optimal solutions within limited computation time for all instances. Several best known solutions for unsolved instances are improved and the algorithm clearly outperforms current state-of-the-art heuristics for the homogeneous and heterogeneous dial-a-ride problem, both in terms of solution quality and computation time.     

重载交通条件下预应力混凝土预制箱梁的设计研究

榆林至佳县高速公路是陕西省重要的能源运输大通道,交通量构成中的大货车、特大货车及拖挂车占相当大的比例.通过实地调研,建立两种车辆荷载模型,并在新的荷载模型下进行计算分析,与公路Ⅰ级荷载对比后,对预应力混凝土预制箱梁进行重新设计研究.     

有轨电车的发展历程与思考

首先回顾有轨电车的起源、发展和衰落历程,总结世界各国对有轨电车进行现代化改造的两种做法:针对路权和车辆、仅改造车辆。在此基础上,明确有轨电车的概念,从线路、车站、车辆、信号、运营五个方面详细阐述其技术特征,指出在有轨电车规划建设过程中,应充分认识其运营特点,不能过高估计其客运能力。最后指出,要冷静而理性地思考中国当前有轨电车规划建设热潮,并在有轨电车名称的规范、适用范围、建设标准、对道路交通的影响等方面进行了深度的思考。     

电动汽车充电与换电模式定价及投资策略

考虑消费者对电动汽车充电与换电模式的不同价值偏好,以电动汽车制造商和换电站投 资商为视角,构建三方博弈决策分析模型,揭示充电、换电模式下电价与投资均衡的机理。通过 引入投资商的投资建设水平,构建由充电汽车制造商、换电汽车制造商和换电站投资商三方组成 的3级斯坦科尔伯格模型,得到电动汽车充电与换电模式的最优定价及投资策略。对影响电动汽 车市场需求、充换电模式的最优定价及最优投资水平的主要因素进行敏感性分析,探究换电汽车 制造商与投资商合作与否对换电站的投资建设水平及充电与换电模式定价的影响。研究发现, 换电汽车制造商和换电站投资商的合作能降低竞争对手(充电汽车制造商)的利润。不合作时的 投资建设水平会受到换电模式的利润分成比例影响,出现投资过低或投资过高的现象。     

电动汽车电池供电模式探讨

电动汽车电池供电模式是电动汽车推广应用的基础和前提。分析国外电动汽车电池供电模式,阐述国内电动汽车电池供电设施建设现状,提出我国应当建立以电池租赁为主、自助充电为辅的电动汽车电池供电模式。     

Optimization and integration of ground vehicle systems

This article deals with the optimal design of ground vehicles and their subsystems, with particular reference to 'active' safety and comfort. A review of state-of-the-art optimization methods for solving vehicle system design problems, including the integration of electronic controls, is given, thus further encouraging the use of such methods as standard tools for automotive engineers. Particular attention is devoted to the class of methods pertaining to complex system design optimization, as well as approaches for the optimal design of complex systems under uncertainty. Some examples of design optimizations are given in the fields of vehicle system dynamics, powertrain/internal combustion engine design, active safety and ride comfort, vehicle system design and lightweight structures, advanced automotive electronics, and smart vehicles.     

多水下机器人编队通信研究

针对多水下机器人编队控制中的水下无线通信问题,提出了一种基于调度的水下无线环状媒介访问控制协议,克服了由于多跳带来的隐藏终端和暴露终端的问题,保证了系统通信的公平接入和周期性控制,同时通过采用数据包捎带技术,在数据包中携带令牌信息,减少额外发送令牌控制包等方法来提高系统吞吐量。N S仿真软件上的仿真实验分析了新协议的性能,通过与类似ALOHA的基于竞争协议的对比实验确定新协议的使用范围,验证了上述媒介访问控制协议的有效性和可行性。     

纯电动汽车动力锂电池SOC估计策略综述

电池管理系统(BMS)采用了防止电池过放电和过充,提供电池均衡控制,能够实现新能源汽车动力锂电池的最佳利用和保护。电池管理系统实时精准估算电池电荷状态(SOC)是提高电动汽车续航里程和延长寿命的关键。然而,SOC不能直接测量,动力电池的充、放电又是一个复杂过程,导致目前现有的SOC估算策略很难精确地估算出实时在线SOC值。因此,如何提高SOC估算精度是当下BMS领域的研究热点。本文通过对各种SOC估算方法进行文献综述,分析和总结各个SOC估算方法的原理及优缺点,提出SOC估计策略未来发展趋势。