地下直线电机牵引地面车辆分析研究

提出了一种地下直线电机牵引地面车辆的创新交通方式,对其基本原理进行了简单的介绍,并建立了相应的动力学仿真模型。在此基础上分析了传统直线电机悬挂结构对车辆性能的影响,并对比分析了地下直线电机车辆与传统直线电机车辆的动力学能行与能耗情况,结果表明地下直线电机的动力学性能及能耗情况均优于传统直线电机车辆。     

独立旋转车轮直线电机地铁车辆动力学分析

为了减小直线电机和感应板的间隙以提高直线电机工作效率,便于直线电机安装和减小直线电机对转向架结构设计要求,提出一种采用独立旋转车轮的直线电机地铁车辆转向架．利用多体动力学软件SIMPACK,对采用独立旋转车轮的直线电机车辆系统进行动力学计算．动力学仿真分析结果表明,采用独立旋转车轮的直线电机车辆具有良好的运行平稳性和曲线通过性能,满足城市轨道交通车辆的要求．     

直线电机地铁车辆悬挂的振动研究

由于直线电机地铁车辆电机悬挂具有特殊的结构形式,因此其振动特性也具有不同于传统电机悬挂车辆的特点。为了研究直线电机地铁车辆的振动特性,从结构上分析直线电机的定位方式,并对其振动特性进行分析,然后分别研究在未计直线电机法向力的情况下直线电机悬挂结构对转向架振动特性、轮轨相互作用及轮轨激励传递特性的影响。研究结果表明：直线电机的垂向振动和横向振动存在一定程度的耦合,且直线电机定位结构对转向架的振动和轮轨关系都具有极大的影响。     

直线电机地铁车轨系统动力响应分析

直线电机地铁系统是一种新型的城市轨道交通模式,它采用直线感应电机牵引,轮轨支撑导向。根据系统特点,建立直线电机地铁系统垂向车辆-轨道耦合模型。在此基础上编制计算机仿真程序,分析确定性不平顺对车辆和轨道动力响应特性及直线电机气隙变化的影响规律。     

直线电机车辆机电动力学模型的构建与分析

基于直线电机车辆的基本结构及工作原理,利用拉格朗日-麦克斯韦方程,从机械与电磁能量层面进行了直线电机车辆系统机电动力学模型的构建。分析了车辆系统机械部件及电磁部分的相互作用规律,并推导了相关微分方程。根据Clark变换,将所得的三相坐标系模型简化为两相坐标系模型。应用Matlab求解及仿真,得到相关参数的变化规律。以此方法建立直线电机车辆的机电动力学模型,简单有效地解决了相关的机电动力学问题。     

某电动汽车馈能悬架设计及其发电效率仿真

传统被动悬架无法根据车辆运行状况自动调节,并且传统被动悬架减少振动的过程中浪费掉了很大一部分的能量,该文设计了一款建立在某电动汽车参数基础上的直线电机式馈能悬架。对直线电机式馈能悬架的弹性元件、导向机构、减振器、直线电机进行设计计算,并使用三维建模软件CATIA进行悬架各部件的建模。最后利用COMSOL软件进行仿真分析,计算直线电机式馈能悬架的效率。     

采用直线电机的馈能悬架控制系统设计与馈能分析

为了实现悬架的主动减振及能量回收,将直线电机作为汽车主动悬架的作动器。设计了基于整车的主动悬架控制系统,控制直线电机根据路面激励输出相应主动力,同时根据直线电机的不同模式对其能量进行管理控制。采用七自由度整车模型进行仿真,结果表明所设计的控制系统能有效的改善车辆的舒适性,并且当阻尼系数选择恰当的情况下能够进行能量回馈。     

直线感应电机牵引模式的车辆设备

针对目前城轨交通发展的趋势,结合城轨交通的要求,在对比了目前已用于轨道交通的直线感应和同步电机的一些特点后,提出了目前城轨交通中应采用技术成熟的感应电机牵引的观点。最后对采用直线感应电机的线性地铁和低速磁悬浮进行了比较,为城市轨道交通设计过程中的车辆设备的选型提供了参考。     

副构架直线电机转向架车辆动力学及振动研究

为了改善直线电机车辆动力学性能,提出了在轴箱上增加副构架,建立了其整车动力学模型,并对有无副构架的两种车辆在一定速度下进行频域和时域仿真,计算了车辆主要振型和曲线通过的主要性能.结果表明存在副构架转向架的车辆其直线稳定性高,通过小半径曲线时与车辆轮轨磨耗相关的指数较小,当通过较大半径曲线时,性能比无副构架的车辆稍差,但绝对值保持在一个相对较低的水平.     

直线电机振动特性对车轮多边形问题的影响研究

针对国内某地铁车辆因车轮多边形造成舒适性差的问题展开动力学仿真和线路测试研究。理论上简要分析了车轮多边形产生的原因并建立地铁车辆动力学模型,计算得到转向架各部件的振动固有频率,并发现车辆平稳性在40 km/h速度下异常恶劣。建立以轨道不平顺为输入、电机位移为输出传递函数,分析了40 km/h速度下车轮多边形产生的外部激励43.6 Hz与直线电机垂向固有频率接近从而导致电机发生共振,进一步加剧了车轮多边形恶化。线路跟踪实验表明,车体上的平稳性指标同样在40 km/h时异常恶化,恶化程度随车轮多边形波深增大而加剧。归纳提出以异常振动速度为切入点,对车轮多边形问题分析的仿真和线路实验方法。最后对直线电机悬挂参数进行优化,消除剧烈振动,提高了乘坐舒适性。     

Application of the Conway-Maxwell-Poisson generalized linear model for analyzing motor vehicle crashes

This paper documents the application of the Conway–Maxwell–Poisson (COM-Poisson) generalized linear model (GLM) for modeling motor vehicle crashes. The COM-Poisson distribution, originally developed in 1962, has recently been re-introduced by statisticians for analyzing count data subjected to over- and under-dispersion. This innovative distribution is an extension of the Poisson distribution. The objectives of this study were to evaluate the application of the COM-Poisson GLM for analyzing motor vehicle crashes and compare the results with the traditional negative binomial (NB) model. The comparison analysis was carried out using the most common functional forms employed by transportation safety analysts, which link crashes to the entering flows at intersections or on segments. To accomplish the objectives of the study, several NB and COM-Poisson GLMs were developed and compared using two datasets. The first dataset contained crash data collected at signalized four-legged intersections in Toronto, Ont. The second dataset included data collected for rural four-lane divided and undivided highways in Texas. Several methods were used to assess the statistical fit and predictive performance of the models. The results of this study show that COM-Poisson GLMs perform as well as NB models in terms of GOF statistics and predictive performance. Given the fact the COM-Poisson distribution can also handle under-dispersed data (while the NB distribution cannot or has difficulties converging), which have sometimes been observed in crash databases, the COM-Poisson GLM offers a better alternative over the NB model for modeling motor vehicle crashes, especially given the important limitations recently documented in the safety literature about the latter type of model.     

Levitation forces in single-sided linear induction motors for high-speed ground transport

The levitation force and thrust in a current-controlled single-sided linear induction motor which propels electrodynamically-levitated vehicles are discussed. It has been shown theoretically that the single-sided linear induction motor (SLIM) can operate satisfactorily over suitably large clearance gap compared with the effective height of electrodynamic suspension. The levitation force in SLIM can be used practically as an alternative levitation force in the low-speed region by supplying a primary current several times the rated current within the very short acceleration times. In high-speed Maglev vehicle system with electrodynamic suspension and SLIM propulsion, the aluminum plate for levitation can be saved for the distance to accelerate the vehicle to speeds sufficient for electrodynamic levitation by the cryogenic magnets.     

The Fatality Analysis Reporting System as a tool for investigating racial and ethnic determinants of motor vehicle crash fatalities

The Fatality Analysis Reporting System (FARS) is a Department of Transportation database in the public domain that contains detailed information about fatalities resulting from motor vehicle crashes on public roadways in the United States since 1975. However, data on race and Hispanic ethnicity were not collected by FARS until 1999. Since then, completeness of reported racial and ethnic information has varied from State to State. To assess utility of FARS for investigating race- and ethnicity-specific risk factors associated with motor vehicle crash mortality, we examined yearly national and State-specific reporting rates of race and Hispanic ethnicity for 168,863 motor vehicle crash fatalities from 1999 to 2002. In 1999, national reporting was 85% for race and 78% for Hispanic ethnicity. Over the 4-year study period, a significant linear increase in annual reporting for both race and Hispanic ethnicity was evident at the national level, as reporting by individual States improved over time. In 2002, national reporting rates reached 90% for race and 88% for Hispanic ethnicity. Our findings indicate that FARS has become a valuable resource for population-based studies of motor vehicle crash mortality disparities that exist among racial and ethnic subpopulations in the United States.     

车用电机噪声振动分析系统开发及应用

以车用电机为对象,从硬件组成和软件设计两方面实现噪声振动测试分析系统的开发。该系统以时域分析、频谱分析以及阶比分析等为信号处理核心,可有效地对车用电机在运行过程中的稳态、升/降速非稳态的噪声振动进行分析。以某型发电机升速过程噪声振动测试为例,简要介绍了系统的应用。并通过近两年对多种车用电机的噪声振动测试,验证了系统的准确性和可靠性,具有工程实用价值。     

Self-regulating permanent magnet linear motor

A new type of self-regulating permanent magnet linear motor (PMLM) is proposed. This PMLM utilizes chiefly permanent magnets and a ferromagnetic yoke for producing a force to propel a flying vehicle. A detailed structure and the theory of the proposed PMLM are given     

Modeling crash outcome probabilities at rural intersections: application of hierarchical binomial logistic models

It is important to examine the nature of the relationships between roadway, environmental, and traffic factors and motor vehicle crashes, with the aim to improve the collective understanding of causal mechanisms involved in crashes and to better predict their occurrence. Statistical models of motor vehicle crashes are one path of inquiry often used to gain these initial insights. Recent efforts have focused on the estimation of negative binomial and Poisson regression models (and related deviants) due to their relatively good fit to crash data. Of course analysts constantly seek methods that offer greater consistency with the data generating mechanism (motor vehicle crashes in this case), provide better statistical fit, and provide insight into data structure that was previously unavailable. One such opportunity exists with some types of crash data, in particular crash-level data that are collected across roadway segments, intersections, etc. It is argued in this paper that some crash data possess hierarchical structure that has not routinely been exploited. This paper describes the application of binomial multilevel models of crash types using 548 motor vehicle crashes collected from 91 two-lane rural intersections in the state of Georgia. Crash prediction models are estimated for angle, rear-end, and sideswipe (both same direction and opposite direction) crashes. The contributions of the paper are the realization of hierarchical data structure and the application of a theoretically appealing and suitable analysis approach for multilevel data, yielding insights into intersection-related crashes by crash type.