Optimal development of alternative fuel station networks considering node capacity restrictions

A potential solution to reduce greenhouse gas (GHG) emissions in the transport sector is the use of alternative fuel vehicles (AFV). As global GHG emission standards have been in place for passenger cars for several years, infrastructure modelling for new AFV is an established topic. However, as the regulatory focus shifts towards heavy-duty vehicles (HDV), the market diffusion of AFV-HDV will increase as will planning the relevant AFV infrastructure for HDV. Existing modelling approaches need to be adapted, because the energy demand per individual refill increases significantly for HDV and there are regulatory as well as technical limitations for alternative fuel station (AFS) capacities at the same time. While the current research takes capacity restrictions for single stations into account, capacity limits for locations (i.e. nodes) – the places where refuelling stations are built such as highway entries, exits or intersections – are not yet considered. We extend existing models in this respect and introduce an optimal development for AFS considering (station) location capacity restrictions. The proposed method is applied to a case study of a potential fuel cell heavy-duty vehicle AFS network. We find that the location capacity limit has a major impact on the number of stations required, station utilization and station portfolio variety.     

基于滚动时域优化的共享自动驾驶汽车动态调度方法

共享自动驾驶汽车被视为未来城市交通系统的重要组成部分。本文考虑随机订单需求研究共享自动驾驶汽车的动态调度优化方法。通过建立车辆调度时空网络，分别针对订单分配与空车移位生成车辆运行时间弧，提出车辆调度问题的刻画方法。基于马尔科夫决策框架，以时空节点流量为状态，以时空弧流量为决策变量，建立最大化系统净收益的车辆动态调度优化模型。 采取滚动时域优化思想，建立含前视时间窗的随机规划模型，并利用CPLEX优化引擎，滚动求解车辆动态调度决策结果。Sioux Falls网络算例结果表明，滚动时域优化方法可保证车辆动态调度决策效果，提升系统运营效率。在计算时间限制下，滚动时域方法应优先采用长时间窗中等规模 样本。在最大化系统净收益的同时进一步最小化乘客等待时间，可有效提升车辆动态调度决策效果。     

Joint deployment of charging stations and photovoltaic power plants for electric vehicles

The focus of this study is to jointly design charging stations and photovoltaic (PV) power plants with time-dependent charging fee, to improve the management of the coupled transportation and power systems. We first propose an efficient and extended label-setting algorithm to solve the EV joint routing and charging problem that considers recharging amount choices at different stations and loop movement cases. Then, a variational inequality problem is formulated to model the equilibrium of EV traffic on transportation networks, and an optimal power flow model is proposed to model the power network flow with PV power plants and optimally serve the EV charging requirements. Based on the above models for describing system states, we then formulate a model to simultaneously design charging stations, PV plants, and time-dependent charging fee. A surrogate-based optimization (SBO) algorithm is adopted to solve the model. Numerical examples demonstrate that the proposed SBO algorithm performs well. Additionally, important insights concerning the infrastructure design and price management of the coupled transportation and power networks are derived accordingly.     

Fully autonomous vehicles: analyzing transportation network performance and operating scenarios in the Greater Toronto Area,Canada

Fully autonomous vehicles (AVs) have the potential to considerably change urban mobility in the future. This study simulates potential AV operating scenarios in the Greater Toronto Area (GTA), Canada, and assesses transportation system performance on a regional level. For each scenario, the base capacities of certain types of road links are modified to simulate the theoretical increase in throughput enabled by AV driving behavior. Another scenario examines driverless parking operations in downtown Toronto. Simulation results indicate that the increased attractiveness of freeways relative to other routes leads to slightly increased average travel distance as vehicles divert to access higher capacity road links. Average travel time is found to decrease by up to one-fifth at the 90% AV market penetration level. Concurrently, localized increases in congestion suggest that proactive transportation planning will be needed to mitigate negative consequences of AV adoption, especially in relation to induced demand for personal automobile travel.     

军用运输车辆机动伪装探讨

分析了军用运输车在行车状态中的暴露征候,主要包括光学波段、雷达和热红外暴露征候等。从加强组织指挥、充分利用各种器材和方法、车辆重点部位伪装、音响伪装等方面提出了相应对策,旨在提高战时车辆机动的伪装效能。     

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首先运用建立在突变理论上的汽车购买热潮分析模型，分析了私人汽车购买量与人均国民收入及交通政策之间的关系，以及在何种条件下才会出现汽车的购买高潮，并以北京市的实际数据为实例做了具体分析.然后用分形方法建立了北京私人汽车拥有量的预测模型，并预测了北京市未来三年的私人汽车拥有量，将最近一年的预测数据与实际数据做了比较，得出可行性.     

轻轨车辆斩波控制的节能途径

本文根据斩波调压控制的基本原理,以及北京地铁DK_6,DK_9斩波型动车试验和运营的研究结果,提出了城市轻轨车辆采用斩波控制的节能途径与具体措施.     

脊骨梁桥面板结构的车桥耦合分析

采用ANSYS对脊骨梁的＂肋梁-桥面板体系＂进行了车桥耦合分析,考虑了车辆行驶速度和肋梁间距2个主要因素,运用限元瞬态动力时程分析的手段对其进行了动力学分析研究,得到了局部构件的冲击系数,提出了在对于此类桥梁进行设计时,应进行专门的动力学冲击效应分析,以确保其安全性。     

桥面平整度对连续梁桥动力响应的影响分析

不同等级桥面平整度对连续粱桥各特征截面的动力响应有一定的影响。相关研究表明，桥面平整度是车辆对桥梁产生冲击的一个重要因素，现行桥梁规范中的冲击系数公式仅适用于桥面状况比较良好的情况。     

轻轨车辆节能途径的探讨

本文从减少列车阻力、选用牵引变流器和牵引电动机以及列车运行方式等方面探讨了城市轻轨车辆节能的可能途径和应采取的对策.