北京通信段管内部分传输网络优化

北京铁路局管内京哈、津山、津秦沈等铁路,承担着大量客货运输任务。但该线路通信设备陈旧,处理能力不足。为此,分析北京铁路局重要干线的通信传输网络问题,利用新增传输设备,完成优化整改,提高网络安全性。     

计算机联锁软件仿真试验表格的运用

计算机联锁在现场模拟试验之前及软件修改后,电务段应进行全面的联锁仿真试验,并认真做好记录,仿真试验的内容按要求表格化,为此需要设计全面的试验表并应掌握试验方法。     

GSM-R分布式基站在多隧道区段的应用

从GSM-R分布式基站的特性入手,对组网结构、设备性能以及可维护性三方面进行了分析,并进行了大秦线多隧道区段应用GSM-R分布式基站前后质量对比,为GSM-R分布式基站在多隧道区段应用提供了可靠的理论和实践依据.     

A hybrid optimization-simulation approach for robust weekly aircraft routing and retiming

We address the robust weekly aircraft routing and retiming problem, which requires determining weekly schedules for a heterogeneous fleet that maximizes the aircraft on-time performance, minimizes the total delay, and minimizes the number of delayed passengers. The fleet is required to serve a set of flights having known departure time windows while satisfying maintenance constraints. All flights are subject to random delays that may propagate through the network. We propose to solve this problem using a hybrid optimization-simulation approach based on a novel mixed-integer nonlinear programming model for the robust weekly aircraft maintenance routing problem. For this model, we provide an equivalent mixed-integer linear programming formulation that can be solved using a commercial solver. Furthermore, we describe a Monte-Carlo-based procedure for sequentially adjusting the flight departure times. We perform an extensive computational study using instances obtained from a major international airline, having up to 3387 flights and 164 aircraft, which demonstrates the efficacy of the proposed approach. Using the simulation software SimAir to assess the robustness of the solutions produced by our approach in comparison with that for the original solutions implemented by the airline, we found that on-time performance was improved by 9.8–16.0%, cumulative delay was reduced by 25.4–33.1%, and the number of delayed passengers was reduced by 8.2–51.6%.     

Estimating economic and resilience consequences of potential navigation infrastructure failures: A case study of the Monongahela River

The paper examines the potential effects of failure of heavily used, outdated locks and dams on the Monongahela River in southwestern Pennsylvania. Catastrophic failure would result in lengthy outage of barge traffic. The displaced volume of coal shipments from mines to power plants is estimated using Energy Information Administration survey data. The resilience of the impacted facilities, the viability of their shipping alternatives, and their ability to re-organize into new markets is assessed. Lost revenues are estimated for facilities that close due to an inability to adapt, as well as the replacement cost of towboats and barges trapped by a catastrophic and sudden failure. The aggregate costs to these facilities as a result of a year-long closure are estimated at $0.56-1.7 billion.     

Evaluating the effects of bus design on passenger flow: Is agent-based simulation a feasible approach?

In this paper, we propose an agent-based simulation approach that is capable of simulating the flow of passengers on board buses and at bus stops. The intention is that it will be applied during vehicle development to analyze how vehicle design affects passenger flow, and thus also how it affects system performance such as dwell time. In turn, this could aid the developers in making design decisions early in the development process. Besides introducing the simulation tool itself, the paper explores the realism of the data generated by the tool. A number of passenger flow experiments featuring a full-scale bus mockup and 50 participants were carried out. The setup of these experiments mirrored a number of ‘bus journeys’ (regarding vehicle design, number of passengers boarding/alighting at each stop and so on) that had previously been simulated using the simulation tool. When the data from the simulations were compared with the data from the passenger flow experiments, it could be concluded that the tool is indeed able to generate realistic passenger flows, although with some errors when a large number of passengers board/alight. The simulated dwell times were rationally affected by the tested bus layout aspects. It was concluded that the tool makes it possible to evaluate how variations in bus layouts affect passenger flow, providing data of sufficiently high quality to be useful in early phases of vehicle design.     

基于模糊逻辑控制策略的混合动力汽车仿真研究

以燃油经济性和排放性能为主要控制目标,提出一种基于模糊逻辑的能量分配控制策略,应用ADVISOR仿真软件,对制定的控制策略在不同的道路循环工况下进行仿真。仿真结果表明,所设计的模糊逻辑控制策略能够合理分配发动机和电机的转矩,可使发动机工作在效率较高、排放较低的中等负荷区,整车的燃油经济性较好、排放较低。     

装有EPAS系统的汽车转向灵敏度仿真分析

描述了电动助力转向器的构造及其工作原理,对EPAS系统模型进行了简化,建立了EPAS机械动力学方程,推导出了电流比例控制策略下汽车转向灵敏度的传递函数方程,并在Matlab中进行了仿真计算,定性地阐述了电动机转动惯量等参数在汽车转向盘角阶跃输入下对系统响应特性的影响。     

ESP硬件在环试验平台的研究与开发

应用Matlab/xPC开发工具,为汽车稳定性控制系统的研究设计开发了硬件在环试验平台。该平台包括实时硬件和系统模型,并利用该平台进行了汽车稳定性控制系统的硬件在环仿真测试。测试结果表明,所开发的硬件在环平台符合测试的要求,所设计的控制算法提高了汽车的操纵稳定性。     

双横臂独立悬架ADAMS建模及运动特性分析

利用ADAMS建立了某轻型车完整的双横臂独立悬架运动学仿真模型,为反映车辆的真实行驶工况,对左、右车轮测试平台分别创建了随机激励。通过仿真分析,揭示了运动特性参数在悬架运动过程中的变化规律,并对原导向机构存在的问题进行了优化计算。结果表明,前轮定位参数在优化前、后的变化量较小,均在设计要求的范围内;轮距和前轮侧向滑移量的变化较大,优化后二者都在理想的范围内变动,达到了预期优化目标。