Mathematical modelling of train–turnout interaction

The paper proposes a mathematical model of train–turnout interaction in the mid-frequency range (0–500 Hz). The model accounts for the effects of rail profile variation along the track and of local variation of track flexibility. The proposed approach is able to represent the condition of one wheel being simultaneously in contact with more than one rail, allowing the accurate prediction of the effect of wheels being transferred from one rail to another when passing over the switch toe and the crossing nose. Comprehensive results of train–turnout interaction during the negotiation of the main and the branch lines are presented, including the effect of wear of wheel/rail profiles and presence of track misalignment. In the final part of the paper, comparisons are performed between the results of numerical simulations and line measurements performed on two different turnouts for urban railway lines, showing a good agreement between experimental and numerical results.     

Application of time-variant predictive control to modelling driver steering skill

The paper addresses the need for improved mathematical models of human steering control. A multiple-model structure for a driver's internal model of a nonlinear vehicle is proposed. The multiple-model structure potentially offers a straightforward way to represent a range of driver expertise. The internal model is combined with a model predictive steering controller. The controller generates a steering command through the minimisation of a cost function involving vehicle path error. A study of the controller performance during an aggressive, nonlinear steering manoeuvre is provided. Analysis of the controller performance reveals a reduction in the closed-loop controller bandwidth with increasing tyre saturation and fixed controller gains. A parameter study demonstrates that increasing the multiple-model density, increasing the weights on the path error, and increasing the controller knowledge range all improved the path following accuracy of the controller.     

带缺陷隧道底板结构空气耦合冲击回波响应特性研究

针对隧道底板中空腔、含水、裂缝等结构内部损伤情况，为提高传统接触式冲击回波方法的检测效率，从气-固耦合的角度出发，以空气作为底板结构与检测系统之间应力波传播的耦合介质，开展隧道底板结构内部缺陷的空气耦合冲击回波响应特性研究。研究结果表明： 1）采用空气耦合冲击回波的方法确定的底板结构内部缺陷深度与缺陷理论深度值基本吻合； 2）检测系统的精度与缺陷尺寸及深度有关，随着缺陷尺寸的减小及深度增加，检测精度逐渐降低； 3）空气耦合冲击回波方法对空腔和含水缺陷的检测效果优于裂缝缺陷检测效果。     

半消声室长轴系动力装置的校中

文章主要介绍半消声室长轴系动力装置试验台的轴系校中。该动力装置采用了可伸缩十字轴式双万向联轴器以及辅助支撑，简化了轴系对中；通过对长轴系动力装置进行动力学分析，采用合理的轴系校中工艺方法，使轴系达到了对中精度。     

A closed-loop dynamic simulation-based design method for articulated heavy vehicles with active trailer steering systems

This paper presents a closed-loop dynamic simulation-based design method for articulated heavy vehicles (AHVs) with active trailer steering (ATS) systems. AHVs have poor manoeuvrability at low speeds and exhibit low lateral stability at high speeds. From the design point of view, there exists a trade-off relationship between AHVs’ manoeuvrability and stability. For example, fewer articulation points and longer wheelbases will improve high-speed lateral stability, but they will degrade low-speed manoeuvrability. To tackle this conflicting design problem, a systematic method is proposed for the design of AHVs with ATS systems. In order to evaluate vehicle performance measures under a well-defined testing manoeuvre, a driver model is introduced and it ‘drivers’ the vehicle model to follow a prescribed route at a given speed. Considering the interactions between the mechanical trailer and the ATS system, the proposed design method simultaneously optimises the active design variables of the controllers and passive design variables of the trailer in a single design loop (SDL). Through the design optimisation of an ATS system for an AHV with a truck and a drawbar trailer combination, this SDL method is compared against a published two design loop method. The benchmark investigation shows that the former can determine better trade-off design solutions than those derived by the latter. This SDL method provides an effective approach to automatically implement the design synthesis of AHVs with ATS systems.     

高等海事院校学生学习动机初探

近年来在国际航运市场高度竞争趋势下,高等海事教育便成为船员素质养成的重要关键,在现今教育学习多元化的感染下,以学生为主体的学习活动,可增进学生主动探索知识、发现与解决问题,随之激发学生的潜能.本文以学习者本身、教师、学校三大构面来探讨学生学习动机构成因素,并依据学习动机理论结合相关专家学者的实务性教学意见,提出六项激励学习动机的教学策略,以教与学并进的方式规划与培养具有国际竞争能力的高级航海技术人员.在此,学生学习动机将扮演其正向积极的意义与功能.     

电磁兼容在电力机车布线中的设计

电磁兼容性对于整个机车布线的设计已成为一个重要的问题，简单介绍了电磁兼容的基本原理，并就电力机车布线中的电磁兼容性原则进行了探讨和阐述。对国内外现有机车电磁兼容的设计进行了分析，比较得出如何在机车布线中消除电磁干扰的建议。     

Multimodal,multiclass stochastic dynamic traffic assignment for evaluating information provision strategies

A multimodal, multiclass stochastic dynamic traffic assignment model was developed to evaluate pre‐trip and enroute travel information provision strategies. Three different information strategies were examined: user optimum [UO], system optimum [SO] and mixed optimum [MO]. These information provision strategies were analyzed based on the levels of traffic congestion and market penetration rate for the information equipment. Only two modes, bus and car, were used for evaluating and calculating the modal split ratio. Several scenarios were analyzed using day‐to‐day and within day dynamic models. From the results analyzed, it was found that when a traffic manager provides information for drivers using the UO strategy and drivers follow the provided information absolutely, the total travel time may increases over the case with no information. Such worsening occurs when drivers switch their routes and face traffic congestion on the alternative route. This phenomenon is the 'Braess Paradox'.     

某软弱路基冲压与强夯处理对比试验研究

在某大型公路工程的软弱地基处理中，分别进行了冲击压实处理和强夯处理的试验。在2种施工方法的工后检测中，分别对于密度、压缩模量、面层强度等指标进行了对比研究，并对2种方法的工效进行了比较。研究表明：对于这种地下水位埋藏浅、压缩模量和标准贯人击数较低的软弱地基，冲压处理的效果和工艺效益均要优于强夯处理。     

基于动态模量试验的沥青混合料老化性能研究

为研究沥青混合料老化过程中的动态特性,对在不同温度条件下经受不同频率的动荷载的沥青混合料在不同老化期的动态模量进行试验,分析温度和荷载频率对动态模量及相位角的影响,采用车辙因子对沥青混合料的高温稳定性进行评价,并根据时间温度等效原理建立了不同老化程度的动态模量主曲线。研究结果表明：老化沥青混合料的动态模量和相位角具有明显的温度和频率依赖性,老化使沥青混合料动态模量增大,相位角减小。动态模量主曲线研究结果表明老化使沥青混合料的动态模量在整个温度（或频率）范围内变化幅度减小。