铌磷半钢在中磷铸铁闸瓦中应用的研究

本文通过对用铌磷半钢配制的中磷闸瓦的金相组织、力学性能、物理性能和摩擦-磨损特性的研究及其实际运行,证明:其质量指标和使用性能完全满足 TB1159-76标准,并超过普通中磷闸瓦的技术水平;可使中磷铸铁闸瓦的原材料成本降低10%左右.     

Towards a dynamic discrete-choice model of household automobile fleet size and composition

The emphasis on energy consumption in studies of traveller behaviour has led to increased interest in the development of policy sensitive models of automobile demand. In recognition of the fuller dimensions of automobile demand, a number of studies have considered choice amongst types of automobiles as well as number of automobiles. With rare exception, existing studies have concentrated on either type choice or number choice. In all instances the approach has been static. This paper develops a series of linked discrete-choice models to explain household automobile holdings (type and number) and adjustments in the holdings over time. The empirical study is part of an initial data effort leading up to the development of a full scale longitudinal panel of Sydney households. A model system based on a retrospective panel of 354 households, interviewed in 1980, is reported herein. The model is dynamic in the sense that it allows for prior decisions, brand loyalty and the costs of transacting.     

一种船用发动机扭振测量方法及其硬件实现研究

本文提出了一种新的能实时预报船用发动机主轴系统扭转振动的精确测量方法.首先,根据脉冲填充法的原理,在主轴作匀速转动的条件下,推导了一个用于精确计算齿脉冲发生时刻主轴系统扭振振幅的理论公式.然后,由该式建立了实时求取主轴系统扭振数据的递推算法,并给出了测量主轴平均转速的公式.文中也对扭振算法的基本误差和主轴转速变化的影响进行了讨论.最后给出了一个基于FPGA实现本算法的硬件电路,并使用动态系统仿真工具SystemView对其工作性能进行了模拟和评价.结果表明:理论计算与实验数据有良好的吻合.     

A conflict model and interactive simulator (FASTCARS) for predicting enroute driver behavior in response to real-time traffic condition information

This paper proposes a theoretical methodology and practical data collection approach for modeling enroute driver behavioral choice under Advanced Traveler Information Systems (ATIS). The theoretical framework is based on conflict assessment and resolution theories popularized in psychology and applied to models of individual consumer behavior. It is posed that enroute assessment and adjustment is a reactionary process influenced by increased conflict arousal and motivation to change. When conflict rises to a level at which conflict exceeds a personal threshold of tolerance, drivers are likely to alter enroute behavior to alleviate conflict through either route diversion of goal revision. Assessment and response to conflict arousal directly relate to the driver's abilities to perceive and predict network conditions in conjunction with familiarity of network configurations and accessible alternate routes.Data collection is accomplished through FASTCARS (Freeway andArterialStreetTrafficConflictArousal andResolutionSimulator), in interactive microcomputer-based driving simulator. Limited real-world implementation of ATIS has made it difficult to study or predict individual driver reaction to these technologies. It is contended here that in-laboratory experimentation with interactive route choice simulators can substitute for the lack of real-world applications and provide an alternate approach to data collection and driver behavior analysis. This paper will explain how FASTCARS is useful for collecting data and testing theories of driver behavior.     

Wave Propagation in a Finite Cascade of Masses and Springs Representing a Train

The response of a train, modelled with a cascade of bodies and springs, due to a step force at the locomotive is investigated. In this model the mass of the locomotive and the last wagon may differ from that of the other wagons. An analytic solution is given for a finite and for a semi-infinite cascade and a comparison to the solution of a continuous model is made.     

Passing sight distance on two-lane highways: Review and revision

Several models have been developed to determine the minimum passing sight distance required for safe and efficient operation on two-lane highways. The American Association of State Highway and Transportation Officials has developed a model assuming that once the driver begins a pass, he/she has no opportunity but to complete it. This assumption is believed to result in exaggerated passing sight distance requirements. Considerably shorter passing sight distance values are presented in the Manual of Uniform Traffic Control Devices and are used as the marking standards in Canada and the U.S.A. More appropriate models have been developed considering the driver's opportunity to abort the pass, and are based on a critical sight distance which produces the same factor of safety whether the pass is completed or aborted. However, these models need to be revised to determine the passing sight distance requirements more accurately and to closely match field observations. In this paper, a revised model for determining the minimum required passing sight distance was developed, based on the concept of critical sight distance and considering the kinematic interaction between the passing, passed, and opposing vehicles. The results of the revised model were compared with field data and showed that the revised model simulates the passing manoeuvre better than the currently-available models which are either too conservative or too liberal. The results showed that the passing sight distance requirements recommended in the Manual of Uniform Traffic Control Devices are sufficient at low design speeds (50–60 k.p.h.) and for manoeuvres involving passenger cars only. For higher design speeds, the Manual of Uniform Traffic Control Devices standards are less than the passing sight distance required for safe and comfortable passes. The deficiency was found to increase with the increase in design speed, and reaches about 36% at a 120-k.p.h. design speed. Based on these results, major revisions to the current Manual of Uniform Traffic Control Devices marking standards are recommended.     

Development of vessel traffic services: Legal considerations

Legislative measures, rather than further technological advances, are needed if there is to be any extensive development of Vessel Traffic Services. Reasons are given why this conclusion differs from that of the COST 301 Study with respect to legal liability of Vessel Traffic Services.