高速铁路ZPW-2000A轨道电路故障分析及监测优化

针对客专ZPW-2000A轨道电路故障处理时,仅靠监测手段不能准确区分室内外故障,需要人工测量,处理时间普遍较长的问题,通过分析信号集中监测系统及轨道电路原理,提出在既有监测系统基础上,增设接收电缆模拟网络监测点的优化措施;同时对轨道电路故障进行模拟试验,分析发生故障时各监测点的数据,总结不同种类故障发生时的规律;最后以2个实际案例验证了优化措施的效果。     

基于H桥逆变器的永磁容错电机变环宽恒频电流滞环的矢量控制

基于H桥逆变器的电流滞环脉宽调制(CHBPWM)在控制永磁容错电机的应用中,传统的CHBPWM有开关频率不固定和谐波分布复杂的缺点.针对这一问题,提出一种实时获取电流滞环控制所需的环宽,达到恒定开关频率的目的.首先,对三相永磁容错电机的结构进行分析,建立其数学模型.其次,对基于H桥型逆变器开关频率进行定性分析和理论推导,得到环宽和频率的数学关系.然后将实时采样、计算所获取的周期性变化的环宽代替传统的固定环宽.最后,仿真验证了这种控制方法的正确可行性.     

典型BIM技术在船闸工程平面提升闸门设计中的应用

平面提升闸门在船闸工程中是常用的一种门型，针对其采用传统的设计方法存在过程复杂、费时费力、更改繁琐、效率低下等问题。文章以曹娥江上浦船闸及航道工程中的平面提升闸门为例，采用典型BIM技术Autodesk Invertor三维设计的方法，特别对平面提升闸门采用该软件设计时的三维模型建立、生成机构传动动画，结构干涉检查、闸门重心位置显示、二维工程图等应用进行了研究和阐述。表明了将Autodesk Invertor软件应用在实际工程中，能够大大缩短设计周期，提高设计效率和准确率，对其他类型的闸门设计也有很好的借鉴意义。     

曲线梁桥的工程设计方法研究

现有的桥梁规范并不能很好地适用于曲线梁桥的全面设计,这在一定程度上使得设计曲线梁桥存在着一些困难。文中以实际设计的曲线梁桥为例,从跨径和截面选择、支座预留偏心、支承约束、总体布置等方面进行计算和分析,最终所得到的应力与曲线梁桥受力特性一致。     

A comparative analysis of US toll policy

In the US, there is a long tradition of toll roads, beginning with the Lancaster Turnpike that was built at the end of the 18th century connecting Philadelphia and Lancaster. There are currently more than 300 toll facilities in the US, which is probably the largest number of toll facilities in the world. These facilities represent a wide range of conditions, from hypercongested facilities in large metropolitan areas such as New York City to toll highways in rural areas. The toll structures are equally diverse, ranging from multi-tier price structures with frequent user, carpool, and time of day discounts; to simpler structures in which the only differentiation is made on the basis of the number of axles per vehicle. The toll rates are typically set by the agencies that operate or own the toll facilities. The rules or formulas by which these tolls are determined are not generally available to the public, though it is safe to say that toll decisions are made taking into account technical considerations, as well as the all important criterion of political acceptability. However, data on toll rates and how they change by vehicle types and by some other attributes are readily available.The overall objective of this paper is to analyze the toll data from various facilities across the US to gain insight into the overall factors affecting the tolls. A more specific objective is to assess—though in a rather approximate fashion—if the tolls by vehicle type, relative to each other, are appropriate and consistent with economic theory. This is achieved by comparing tolls to approximate indicators of road space consumption and pavement deterioration. The literature review confirmed that this is the first time such research has been conducted which is an important first step toward an analysis of the efficiency of current toll policies.The analyses in this paper are based on a random sample of all toll facilities across the US. The toll dataset, which include toll rates for passenger cars, busses, and three different truck types, is assembled mainly from the available information on the web sites of various toll agencies. After cleaning the data, the authors used econometric modeling to estimate a set of ordinary least squares (OLS) regression models that express tolls as functions of independent variables. Three families of models were estimated: linear models, models based on expansions of Taylor series, and models based on piece-wise linear approximations to non-linear effects. The resulting models were analyzed to identify the salient features of current toll policies towards different vehicle types.     

基于作战需求的数据链平台定位报告周期分析

文章以指控平台指挥战机打击敌机为例，在分析杀伤目标对平台定位报告周期要求的基础上，提出了一种基于作战需求的平台定位报告周期计算方法。所得结果与实际应用的数值基本吻合。     

铁路车辆承载鞍鞍面内弧半径测量系统的研究

阐述了用线激光三角法进行铁路车辆承载鞍内弧半径测量的方法,提出了一种可行的标定方案,通过计算得到测量系统的参数初值,并由此确定标定点的选取,通过三坐标机的探针在平台上移动来获取标定点的坐标,得到二维标定表,利用插值获得承载鞍内弧曲面的坐标,由此拟合出内弧轮廓的方程并来求得承载鞍的半径.     

利用MF/HF实现计算机船岸数据通信

传统的高频通信系统的工作是极不稳定可靠的.新一代高频通信系统一改旧貌,具有和卫星通信同样快捷、可靠的通信性能而且有较之卫星通信更便宜的特点,是实现船岸数据通信的有效方法之一.本文介绍了这一新系统的组成、工作原理及其特点.     

基于鲁棒接续时间的铁路空车调运优化

空车调运是铁路运输的关键环节，其方案具有一定的鲁棒性，可以避免车站技术作业时间以及站间旅行时间等不确定因素对调运方案实施的影响. 基于固定的车站技术作业时间和站间旅行时间，提出了空车供应站到达列车与发出列车、空车供应站发出列车与空车需求站发出列车间的空车接续时间关系判别方法. 以空车调运收益最大化为目标，建立了确定情形下考虑车种替代的空车调运模型，在此基础上，引入波动率描述车站技术作业时间和站间旅行时间的不确定性，并通过设置波动下限调整模型的鲁棒性，建立了不确定情形下的空车调运鲁棒优化模型；结合模型性质，以车流关系变化为依据，设计了鲁棒优化模型的快速求解算法，将非线性优化问题转化为易求解的鲁棒等价模型. 结果表明:求得的空车调运方案可以得出列车间的空车配流和车种替代情况，不确定因素的波动率和波动下限会影响空车调运方案的效益值，绝对鲁棒下站间旅行时间、供应站技术作业时间和需求站技术作业时间3个不确定因素导致方案效益值较确定模型分别下降了16.2%、12.1%和28.1%.