Transport in Romania—a British perspective

Abstract

Railways restructuring takes place under very different circumstances and with very different goals in Western Europe, Central and Eastern Europe, and Russia. There are some improvements in productivity associated with the reforms in the European Union (among others access to infrastructure and vertical separation). But they are not certain to be replicated following similar restructuring in transition economies, especially if one takes account of the much higher shadow price on government subsidies in the latter. The current and proposed reforms in the railways of Central and Eastern Europe and Russia are described in detail; the likely outcomes of reforms in the special economic, regulatory and legal environments of these countries are analysed; and an alternative proposal for restructuring in Russia is presented.     

喷油器套压装过程分析

本文主要介绍了喷油器套压装过程,对整个气缸盖铜套装配机进行了详细的分析,分析了整个压装过程的每一个关键环节,对气缸盖铜套装配机的说明书进行了深入的解读,并描述了现在压装机的发展现状和以后压装机行业的发展趋势,最后对论文进行总结。本论文对以后气缸盖铜套装配机的改进和应用都起到了积极的作用。     

Passengers’ activities during short trips on the London Underground

The present study considers underground passengers and investigates the ways in which they spend their time during a trip of average length or shorter. Using a structured procedure that had been refined after a preliminary study, more than 1,700 passengers were observed in London. The results showed that even when the length of travel is very short (2–6 stops), underground passengers engage in several occupations, especially those involving the use of mobile Information and Communication Technologies. These occupations depend on the specific spatial and temporal conditions of the travel, as well as on gender and age. These results should be useful in designing travel services that enhance passengers’ experiences; they also suggest a criterion for comparing trips using different transportation modes (i.e., looking at the time point during the trip at which the ratio of active versus passive occupations changes).     

Traffic forecasts under uncertainty and capacity constraints

Traffic forecasts provide essential input for the appraisal of transport investment projects. However, according to recent empirical evidence, long-term predictions are subject to high levels of uncertainty. This article quantifies uncertainty in traffic forecasts for the tolled motorway network in Spain. Uncertainty is quantified in the form of a confidence interval for the traffic forecast that includes both model uncertainty and input uncertainty. We apply a stochastic simulation process based on bootstrapping techniques. Furthermore, the article proposes a new methodology to account for capacity constraints in long-term traffic forecasts. Specifically, we suggest a dynamic model in which the speed of adjustment is related to the ratio between the actual traffic flow and the maximum capacity of the motorway. As an illustrative example, this methodology is applied to a specific public policy that consists of suppressing the toll on a certain motorway section before the concession expires.     

Brake Valve Timing and Fuel Injection: a Unified Engine Torque Actuator for Heavy-Duty Vehicles

A unified engine torque actuator for heavy-duty vehicles is developed in this paper. Based on averaging and identification of the instantaneous torque response for changes in brake valve timing and fuel flow, we derive a control oriented engine model of a six cylinder, 350 Hp turbocharged diesel engine, equipped with a compression brake. This work bridges the gap between the detailed compression crank angle based models developed in the engine design community, and the first order lag representation of diesel engine torque response used in the vehicle dynamics community. Moreover, we integrate the compression brake actuator with the service brakes and design a PI-controller that emulates the driver's actions during long descends on grades. The controller simply uses the engine speed measurement to activate the service brakes only when needed.     

Technical characteristics and efficiency of urban bus companies: The case of Spain

The aim of the present study is twofold. First, to provide new information concerning the technical characteristics of urban bus companies on the basis of a sample of medium and large-size cities in Spain. Second, to analyze the degree of efficiency of those companies and to quantify the reasons for this efficiency. The results should be useful in evaluating possible changes in public policies relating to urban transport, specifically changes in the way the market is organized and in pricing.The analysis is carried out by estimating a cost function. The sample is made up of a panel data set consisting of observations of nine Spanish companies that operated during the period 1983–1995. The specified functional form is translogarithmic. The output unit of measure adopted is bus*kms run. The cost function includes the network length for each company, thus permitting evidence concerning economies of density and economies of scale.The use of panel data allows us to estimate the cost function, taking into account that each company is affected by the specific characteristics of each individual city, the different features of the network in question and by different levels of efficiency. The economies of scale have been calculated, taking into account that the features of the network and of the city – represented by their specific individual effect – will vary with the company's level of output.Finally, an analysis is made of the relative productive efficiency of the companies, as well as of the variables likely to influence that efficiency.