修船企业更应着力抓好内部治安检查

企业内部治安管理是企业管理的重要组成部分,而治安检查又是内部治安管理的重要手段。文章渐次阐述了修船企业治安问题的特殊性,治安检查的目的、方式、范围、内容和要求,可供同行借鉴。     

Development of a differential route share model for railroad freight traffic

This paper summarizes work undertaken towards development and calibration of a model to predict the distribution of rail freight traffic among competing routes. The model is designed for use in analyzing the traffic effects of changes in the level-of-service on selected rail lines. The model predicts route shares based on the overall network configuration of each railroad participating in a given market. The model selects feasible routes, discards those routes which appear to be too circuitous or costly, and then assigns traffic to the remaining routes in accordance with several network characteristics. It is designed to be sensitive to level-of-service changes, and to simulate the response of shippers and railroads to a competitive environment. A multiple route-finding algorithm was used to find possible routes based on the number of railroads operating at the originating and terminating end of a market. Multiple routes were determined and matched with observed traffic flows from the ICC One-Percent Waybill Sample. Physical network characteristics for each route, including distance, junction frequency, and “impedance,” were calculated from the network model and were correlated with the traffic share observed on each route in the market. A two-stage model was developed to find feasible routes from the set of possible routes and to allocate traffic to feasible routes based on levels-of-service. The model was calibrated on 9,793 routes from 1,199 markets with twenty or more carloads from the 1977 One-Percent Carload Waybill Sample. Model calibration supported the hypothesis that network route characteristics did indeed influence shipper choice of route, and that a normative model could be used to assess relative attractiveness of routes under various railroad corporate ownership restructuring scenarios.     

Safety culture in shipping

The emergence of a safety culture in shipping has been promoted, especially by the Secretary General of the International Maritime Organization. However, what is really meant by a safety culture? The adoption of the International Safety Management Code and of the amended International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, STCW 95, together with the introduction of Formal Safety Assessment in the IMO rule making process are considered as the major tools contributing to the emergence of such. This article examines the evolution of the concept of maritime safety concept during the last decades and discusses how the adoption of new international instruments has contributed to improve the maritime safety system. It provides possible definitions of maritime safety and safety culture and discusses how far the maritime safety system is from a culture of safety.     

Modelling the impact of rail fare increases

Rail fares in South-East England have been increasing in real terms for several years, and are expected to continue to do so. In this paper, the impact of such increases is examined in terms of the choices of mode of travel, home and job location, and residential migration. Forecasts are made using a model in which the population is partitioned into four sets according to whether they have changed home and/ or job over the forecast period. The model allocates population to homes and workers to jobs, and commuters to the three modes of travel considered. The impact of an increase of 25% in real fares over a five-year period is examined and a number of conclusions are drawn. The model shows that rail patronage will decline even if transport costs remain constant in real terms, because of decentralisation of jobs and rising car ownership. The overall long-term rail fare elasticity is found to be –0.7, but this is the mean of a wide range of values for different parts of the study area. People ceasing to commute by rail would divide almost equally between car and bus, the latter being used particularly to Central London. Those people who commute to London who are seeking new homes would tend to choose to live nearer London than they would have otherwise. The paper concludes with a discussion of the findings in terms of the assumptions implied in the model.     

柴油机气缸盖机械变形和应力的精确三维分析

本文在分析了国内外大量气缸盖结构分析算例特点的基础上,对16V240ZJ柴油机气缸盖的机械应力用三维有限元法在微机上进行了比较全面细致的计算,在计算模型中,对气缸盖各部分结构都不作替代简化;在边界条件的处理方面,计入了气缸套的弹性,并与刚性支承边界条件计算结果进行了比较,计算求得的位移和应力分布规律与实测完全一致,最大位移误差6.5％,最大压应力误差7.4％。     

Multimodal traveling and its impact on urban transit network design

Multimodal trip making, that is trips using a combination of several modes between origin and destination, is expected to be beneficial to society and might offer advantages to the traveler as well. This article looks at some of the implications of multi‐modality in trip making for the design of urban transit systems since these play an important role in multi‐modal transportation systems. In this respect, the article looks at the strategic design characteristics of urban transit networks, that is line density, stop density and service frequencies for the case of multimodal access to urban transit networks and for hierarchical network structures in urban transit systems. The analyses show that multimodal access does not require alternative network structures. For hierarchical network structures it is concluded that these are primarily determined by the hierarchy in demand densities and thus by hierarchy in urban structures.     

Telecommuting and travel: state of the practice,state of the art

This paper provides an overview of the status of telecommuting in the United States, especially as it relates to changes in travel behavior. Regarding the state of the practice, the paper discusses some refinements to the definition of telecommuting that have developed through increased operational experience. It reports several policy statements involving telecommuting, and explores the appeal of telecommuting as a public policy instrument. It highlights some trends in the implementation of home-based and work center-based telecommuting, and suggests that visible public-sector involvement has been crucial to the increased activity in this area.In sketching the state of the art, the paper outlines some frequently-stated hypotheses on telecommuting and travel behavior, and summarizes current empirical findings relating to those hypotheses. Finally, it suggests a variety of topics suitable for further research. These include studying factors influencing the ultimate adoption levels of telecommuting; impacts on energy/air quality, mode choice, and location/urban form; interactions with other transportation demand management strategies; relationships to the traditional urban travel demand forecasting process; cost/benefit tradeoffs; and telecommuting centers.     

新旧交替列车运行图客车车底周转图智能编制方法研究

编制新旧交替列车运行图客车车底周转图的实质是确定新运行图中所需客车车底的来源与旧运行图中所运用车底的去向,以实现新旧列车运行图的顺利交替。探讨交替期客车车底周转图的约束满足优化问题模型及其智能求解算法。模型以减少停运列车数量为目标,以车底技术作业时间、车底上下线地点为车底配属站等作为约束条件。利用启发式知识设计智能求解算法,得出新旧交替列车运行图客车车底周转图的满意解。     

接触轨断口设计分析

归纳了普遍存在的若干种接触轨断口。对道岔区断口设计存在的主要问题进行了重点分析,并结合各种情况提出了建议措施。阐述了各类接触轨系统断口设计的基本原则和关键技术。     

南京地铁二号线信号系统多级后备控制模式

后备控制模式是提高信号系统可靠性,保证其正常运营的重要手段之一。南京地铁二号线在西门子Trainguard MTA TC系统原有后备控制模式的基础上,又引入了中国电子科技集团公司第十四研究所研发的后备控制模式,使整个系统的可靠性得以提高。通过对多级后备控制模式的设计及原理进行分析,为今后进一步完善后备系统提供参考。