JL-902型机车柴油机燃烧系统分析仪的研制及应用

讨论了JL-902型机车柴油机燃烧系统分析仪的系统组成、结构特点、现场测试数据,并对数据进行了分析和讨论。通过对测试的示功图和高压油管压力波的分析能够得出柴油机燃烧系统的基本性能参数,并为柴油机提供了一种新的测试设备。     

列车运行速度及走行距离测试的原理分析

推导了列车运行速度、走行距离与测速发电机输出电压频率的数学关系式，给出了利用ＣＭＯＳ数字集成电路和频率合成原理实现上述关系的电路框图，并对其速度接口电路、轮径输入方法及频率合成电路、分频电路和ＢＣＤ比例乘法器电路、显示电路、基准频率发生电路、电源电路等作了分析与说明。通过大量测量，获得了准确可靠的数据，表明电路设计是正确的。     

铁路列流图自动生成算法

针对铁路列流图目前由手工绘制存在的缺陷,研究铁路列流图自动生成算法。根据图论理论,从列流图中的列流路径由车流组织确定而无需考虑路径长度的特点出发,借鉴最短径路算法,提出站点连通路径标号算法,用来求出起点至终点经历的站点集合。采用点集合及边集合自动生成算法,自动生成路网内的车站、衔接方向、道岔及铁路线。分析不同情形下径点偏移的横纵坐标关系,按列流线等间距绘制的要求提出列流线自动生成算法。依据自动生成算法开发列流图编制软件,运用该软件自动生成具有65条列流线的某路网列流图,证明列流图自动生成算法能够很好地提高设计效率和质量,同时有助于实现列流图的规范化。     

Bifurcation analysis of an automobile model negotiating a curve

The paper deals with the bifurcation analysis of a rather simple model describing an automobile negotiating a curve. The mechanical model has two degrees of freedom and the related equations of motion contain the nonlinear tyre characteristics. Bifurcation analysis is adopted as the proper procedure for analysing steady-state cornering. Two independent parameters referring to running conditions, namely steering angle and speed, are varied. Ten different combinations of front and rear tyre characteristics (featuring understeer or oversteer automobiles) are considered for the bifurcation analysis. Many different dynamical behaviours of the model are obtained by slightly varying the parameters describing the tyre characteristics. Both simple and extremely complex bifurcations may occur. Homoclinic bifurcations, stable and unstable limit cycles (of considerable amplitude) are found, giving a sound and ultimate interpretation to some actual (rare but very dangerous) dynamic behaviours of automobiles, as reported by professional drivers. The presented results are cross-validated by exploiting handling diagram theory. The knowledge of the derived set of bifurcations is dramatically important to fully understand the actual vehicle yaw motions occurring while running on an even surface. Such a knowledge is a pre-requisite for robustly designing the chassis and for enhancing the active safety of vehicles.     

基于牵引仿真的列车运行图软冲突疏解方法研究

定义存在于高速铁路列车运行图运行线间的使列车无法在适当功率下运行的软冲突问题,该问题使用既有列车运行图规划方法难以有效解决。分析软冲突形成的机理及其影响,论证牵引供电与列车群一体化仿真计算方法能较好解决软冲突问题,即利用牵引供电计算实现列车运行图软冲突的检测,基于该检测结果进行列车仿真运行调整,从而实现对软冲突的剔除。一体化仿真方法不仅能实现高速列车运行图软冲突的疏解,同时也能得出列车运行过程的操纵策略,并解决了交流牵引供电仿真计算中的某些难点问题。选用我国某一高速铁路线路为例,验证基于牵引仿真的列车运行图软冲突疏解方法。     

Identification of the technical state of suspension elements in railway systems

The running safety and passenger comfort levels in a vehicle are tightly related to the technical state of the suspension elements. The technical state of the suspension depends of the service life time as its components become old and wear out. In this paper, a study on the dynamic behaviour of a railway vehicle is established in relation to the damping elements in one of its suspension stages. An experimental measurement model is developed, obtaining a set of useful signals for the identification of the dynamic parameters of the vehicle and developing a test through the application of the operational modal analysis technique, using least-squares complex exponential method as a basis to validate the numerical model of the multi-body system. Then, the study focuses on developing numerical simulations for the identification of the technical state of the dampers by the registration of dynamic variables under commercial service conditions and on estimating the state of the suspension elements.     

The handling surface: a new perspective in vehicle dynamics

The problem of describing the understeer–oversteer behaviour of a general vehicle, such as one with locked differential or tandem rear axle, is addressed taking a new perspective. The well-known handling diagram and the associated classical understeer gradient may be inadequate, mainly because they are no longer unique. The new concept of handling surface and a new definition of understeer gradient, which is indeed the gradient of the handling surface and hence a vector, are presented. It is also shown how the new concepts relate to and generalize the classical ones. Finally, a procedure for the experimental measure of the new understeer gradient is outlined.     

环放路网宏观基本图信号周期敏感性分析

为揭示路网宏观基本图(MFD)对信号周期的敏感性，首先，提出一种基于GMM的宏观基本图建模方法，并在此基础上提出路网运行效率和稳定性的表征方法；其次，提出MFD 对信号周期敏感性的仿真实验设计方法；再次，以环放路网为例，进行仿真实验，分析信号周期的变化对MFD的影响，进一步揭示信号周期对路网运行效率和稳定性的影响机理. 结果表明，合理的信号周期对MFD和路网的效率及稳定性影响不大，但周期过大或过小则对MFD 和路网的运行效率及稳定性造成较大影响. 该结论可以为路网交通控制和优化提供依据.     

铁道车辆疲劳可靠性设计Goodman-Smith图的绘制与应用

研究铁道车辆疲劳可靠性设计Goodman-Smith图的绘制及其应用方法.提出基于中短与长寿命概率疲劳S-N曲线,确定任意可靠性水平的疲劳强度,以及计算疲劳可靠性设计Goodman-Smith图中转折点坐标的全概率方法.研究表明：以车轮旋转一周、疲劳主应力交变一次为基本循环特征,疲劳寿命用行驶里程表示,以万km为基本单位来绘制铁道车辆的疲劳可靠性设计Goodman-Smith图较为合理.当结构的设计寿命和循环特征与Goodman-Smith图存在差异时,引入换算系数进行修正;当结构部件的疲劳载荷模式与绘制Goodman-Smith图试样的试验载荷模式存在差异时,引入折算系数进行修正;当结构部件的结构形状与尺寸、表面质量、环境条件等可能与绘制Goodman-Smith图的试样存在差异时,引入相应修正系数进行修正;分别给出了上述3种修正系数的表达式.并以LZ50钢疲劳可靠性设计Goodman-Smith图的绘制、修正及其在铁道车辆车轴设计中的应用为例,验证了方法的可行性.     

如何解决运行列车严重偏离时刻表问题

在城市轨道交通系统的运行过程中,由于各种可能原因造成列车在车站或区间被迫长时间停车,导致全线运行列车严重偏离在线运行时刻表,这种情形时有发生,不可避免。深圳地铁一期工程信号系统设计针对系统在发生这种情形所固有的特点和现象,结合本工程所选西门子信号系统特点,提出具体的应对措施和解决方法。