An assessment of railway capacity

In this paper, we review the main concepts and methods to perform capacity analyses, and we present an automated tool that is able to perform several capacity analyses. Capacity is extremely dependent on infrastructure, traffic, and operating parameters. Therefore, an in-depth study of the main factors that influence railway capacity is performed on several Spanish railway infrastructures. The results show how the capacity varies according to factors such as train speed, commercial stops, train heterogeneity, distance between railway signals, and timetable robustness.     

Distributional effects of environmental taxes on transportation: evidence from Engel curves in the United States

Indirect taxes on transportation activities that pollute can correct externalities and close the gaps between private and social costs. However, policy makers often find such Pigou taxes difficult to implement because of political resistance due to possibly adverse affects on equity. For this reason it is important to assess the distributional aspects of environmental levies. This article estimates properties of the demand for transportation in parametric and non-parametric analyses of Consumer Expenditure Surveys for the United States and finds patterns in the resulting set of Engel curves. Private transportation using air flights and new cars has Engel elasticity above unity while public transportation via mass transit has Engel elasticity below unity. The findings can be interpreted in an important way since they show that a differentiated scheme of environmental taxes on transportation may function progressively. A Pigou scheme with larger taxes on modes of transportation that pollute more appears to coincide with larger levies on luxury modes preferred by richer households.     

Enhancing capacity planning through forecasting: An integrated tool for maintenance of complex product systems

Despite the extensive amount of data generated and stored during the maintenance capacity planning process, Maintenance, Repair, and Overhaul (MRO) organizations have yet to explore their full potential in forecasting the required capacity to face future and unprecedented maintenance interventions. This paper explores the integration of time series forecasting capabilities in a tool for maintenance capacity planning of complex product systems (CoPS), intended to value data that is routinely generated and stored, but often disregarded by MROs. State space formulations with multiplicative errors for the simple exponential smoothing (SES), Holt’s linear method (HLM), additive Holt-Winters (AHW), and multiplicative Holt-Winters (MHW) are assessed using real data, comprised of 171 maintenance projects collected from a major Portuguese aircraft MRO. A state space formulation of the MHW, selected using the bias-corrected Akaike information criterion (AICc), is integrated in a Decision Support System (DSS) for capacity planning with probabilistic inference capabilities and used to forecast the workload probability distribution of a future and unprecedent maintenance intervention. The developed tool is validated by comparing forecasted values with workloads of a particular maintenance intervention and with a model simulating current forecasting practices employed by MROs.     

政府绩效审计“阶梯型”评价模式的构建与应用——以BRT公共交通投资项目为例

构建一套政府公共交通投资项目绩效审计评价模式是提高政府公共交通投资项目绩效审计效率和审计质量的关键,然而目前业界尚未对此形成统一认识。论文基于平衡计分卡理论从资源配置、职能行使、潜力发挥和贡献效益四个维度,构建了“阶梯形”政府公共交通投资项目绩效审计评价模式,并通过模糊评价对某市BRT项目调研数据对该模式进行了验证。     

基于遥感影像的盘锦市土地资源承载力评价研究

本文以盘锦市作为研究区,通过对盘锦市2000年、2004年和2010年三个时间段的Landsat TM遥感影像处理,获取盘锦市2000年、2004年和2010年的土地利用数据,并综合考虑人口-资源-环境之间的协调发展,构建了盘锦市土地承载力评价体系,运用层次分析法及多因素加权求和法,对盘锦市土地资源承载力进行评价研究。     

质量的产能约束、信息不对称与大销量倾向:以食品安全为例

食品安全关系到每一个人的健康与生存,但以乳品为代表的食品类企业却往往忽视质量控制而热衷于销量扩张.本文从技术约束和信息不对称的角度对此给出了一种解释.分析表明:竞争压力未必是解释该现象的关键因素;只要产品的市场容量较大、并且在投资不足的前提下提供优质产品的产能相对较小,即使没有竞争的压力,厂商在质量控制上的投资也不充分,而且总是热衷于低价大销量的营销方式,后者被消费者视为投资充分的不完美信号.增强监管无法从根本上改变厂商投资不足且追逐大销量的现状,但能增加厂商高投资的可能性、提高产品的平均质量.我们的结论在一定程度上吻合乳品等国内食品企业高速扩张但忽视质量控制的现状.     

Uncertainty and entry deterrence

Summary. We study a model where capacity installation by an incumbent firm serves to deter others from entering the industry. We argue that uncertainty about demand or costs forces the incumbent to choose a higher capacity level than it would under certainty. This higher level diminishes the attractiveness of deterrence (Proposition 1) and, therefore, the range of parameter values for which deterrence occurs (Proposition 2). Received: July 10, 1997; revised version: November 21, 1997     

基于物流视角的北宋粮食纲运分析

基于物流系统要素理论,从一般要素、功能要素、支持要素和物质基础要素四个方面分析了北宋粮食纲运系统,从纲制编排与纲运限程、纲运管押与催检、行运秩序与安全保障三个方面描述了北宋粮食纲运的管理过程,纲运过程存在着诸如纲物丢失、损坏、延期运抵等问题,造成这些问题的主要原因是在押纲、催检和起卸三个环节上的官吏腐败。     

厦门经济特区扩容背景下的城市交通战略规划探讨

在国务院批准厦门经济特区扩大到全市的背景下,结合分析厦门城市近年来交通现状的基础上,紧紧围绕“全城厦门的理念统筹城乡交通战略规划,积极推进岛内岛外交通一体化建设,构筑以公共交通为主体的可持续城市交通发展模式.     

Regional Development Programmes

Broad-focusing development programmes at a regional level have been a major thrust by governments of developing countries over the last three decades. Most of the programmes addressed here have been entirely or partly financed by donor agencies. They have tended to concentrate on augmenting activities of government line agencies, and have mainly emphasized physical and social infrastructure, standardized support facilities to enterprises and individuals, and, sometimes, land use zoning and other measures to regulate the spatial distribution of facilities and activities. This article suggests that regional development programmes may become more effective if they are designed as more flexible instruments for peoplecentred development, exploiting potential comparative advantages of innovation, networking and institution building in a broad sense. Basic organizational and management requirements for this would be a decentralized set-up, substantial freedom from government administration. flexible organizational form, process planning with compatible systems of monitoring and co-ordination, active facilitation of initiatives from below and democratically minded leaders with broad management competence.