Train boarding and alighting rates at high passenger loads

Line capacity in metro and high‐frequency suburban railways is as much determined by station stop times as by factors such as line speed or train acceleration. This paper applies the method developed by London Underground to estimate the time that trains spend at stations, as a function of the physical characteristics of the situation (e.g. train door width) and the numbers of passengers involved. Analysis was carried out on a number of alternative designs for refurbishment of South West Trains' Class 455 inner‐suburban rolling stock. Whilst there is indeed an interaction between boarding and alighting passengers, this paper demonstrates that the LUL relationship breaks down at the highest passenger loads. Moreover, results indicate that passenger flow is not equal between different parts of the same group of boarders or alighters.     

基于奇异强度理论的疲劳特性评估方法

疲劳是海洋结构物破坏的重要因素,为简化舰船结构疲劳评估方法,基于线弹性断裂力学和切口应力强度理论,针对典型薄板结构研究拐角节点处的应力强度,分析结构形式,利用ANSYS有限元模拟和MathCAD函数拟合,分别给出计算应力强度因子的＂奇异权函数法＂和＂奇异等效裂纹法＂的研究方法,同时给出简便算法和经验公式。进而应用Paris裂纹扩展法则进行结构奇异强度疲劳特性评估,并结合S-N曲线分析拐角节点处的应力集中,得到与结构尺寸相关的＂奇异应力集中系数＂函数。最后,针对切口应力,提出有限元分析所需要的＂奇异应力等效取值点＂的参考位置。希望能将奇异强度理论纳入船舶结构疲劳强度校核规范中做参考。     

摩托车发动机凸轮测量测头替换方法

采用平面测头有利于凸轮型面的加工和凸轮升程的测量,但这就涉及到测量时的测头替换问题,也就是说,在加工和测量工艺条件有限、或某种特殊场合无法采用符合设计要求型式和形状的测头时,允许用测头替换方法采用不符合设计要求的测头进行凸轮测量。     

Optimization and Performance Enhancement of Active Suspensions for Automobiles under Preview of the Road

The problem of deriving control laws which minimize specified performance indices for a vehicle moving on a rough surface with preview of the surface elevation is considered. The approach is based on linear optimal tracking theory and consequently the system elements are taken to be linear and the performance index is constrained to be of quadratic form.

The ideas of overtaking optimality are applied to the problem in order to achieve a closed form solution for the control. Then, using the control laws derived, computer simulations of performance are conducted and time histories are shown. In the absence of limitations on either processing or actuator speeds, and for cases in which the preview is sufficient to give good control laws, the value of the preview in enhancing vehicle suspension performance is assessed. Comparisons are made with results in the literature.     

Two-Vehicle Collision Reconstruction : A Rational, Computer-Aided Approach

Methods are presented for predicting either initial speeds or impact locations for two inelastic vehicles on a collision course. Forty system parameters are distinguished, of which up to 35 can be deduced with varying degrees of accuracy from post-collision data. The remaining parameters are calculated using the conservation laws of linear momentum, angular momentum, and energy. Essential ingredients of this analysis are the plastic impact deformation energies and the friction work along the post impact trajectories. Examples of central impact and computer-aided studies for oblique impact illustrate how vehicle speed predictions vary within the bounds of uncertain accident data.     

摩托车发动机凸轮的影像测量方法(2)

一般以1°间隔测量整个凸轮（0～360°）的升程（基圆部分可以取大一点的角度间隔）,获得凸轮的升程误差值△h_i。△h_i可由图4关系导出:△h_i=h_is-h_i=y_is-y_i,最后画出如图5所示的凸轮升程误差曲线。     

Book reviews

EAST EUROPEAN TRANSPORT: REGIONS AND MODES, edited by B. Mieczkowski. The Hague, Martinus Nijhoff. (F85.00)

CONFLICT IN TRANSPORTATION, by H. M. Steiner, Lexington Mass: D. C. Heath and Lexington Books, 1978. 124 pp.     

A study of rail demand in a two‐tier fares environment

A method based on logit analysis is suggested for predicting the effects on patronage and revenue of relative changes in peak and offpeak fares. The method also permits the ready estimation of consequent changes in service profitability. Data was collected specifically for this study from British Rail's Teesside corridor to achieve model calibration. Results show the extent to which demand in peak and offpeak fare‐periods is complementary when fare restrictions are applied only to the morning peak.     

The use of recovery time in timetables: rail passengers’ preferences and valuation relative to travel time and delays

Transportation - Recovery time in the rail industry is the additional time that is included in train timetables over and above the minimum journey time necessary often with the explicit aim of...