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11.
Raimund K. Herz 《运输规划与技术》2013,36(4):311-328
The rediscovery of the bicycle by the public, by politicians and by professional urban transportation planners as a mode of transport which is perfectly in harmony with the goals of environmental protection, energy saving and personal fitness has stimulated this empirical study on the actual use of the bicycle by various population groups for obligatory and discretionary trip purposes. The influence on bicycle usage of such factors as age, education, car availability, residential density and town size, topography and time of year is analysed in this paper for selected population groups. For housewives from motorized households logit‐models were designed and calibrated to model their modal choice for shopping trips with special references to the bicycle. From the empirical results, the groups with the largest potentials for cycling are identified and the extent to which the potentials could be activated by specific policies is discussed. The research is based on a large sample held to be representative for the Federal Republic of Germany in 1976 and is supplemented by more recent surveys in selected German cities conducted by SOCIALDATA Munich. 相似文献
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以新疆乌鲁木齐“世纪花苑”三期工程人防地道为例,运用快速拉格朗日差分分析程序,通过逐渐调整上部荷载大小,使其达到临界状态下的数值模拟方法,系统分析不同影响因素(如洞跨、顶拱高跨比、顶板厚度、荷载范围等)对人防地道顶板最大安全荷载的影响及相关变化规律。结果表明,顶板最大安全荷载与洞跨及荷载范围成反比,而与顶拱高跨比、顶板厚度和荷载偏心率成正比。在此基础上,用数理统计方法得出能综合考虑各影响因素下顶板最大安全荷载的预测方程。 相似文献
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The CAMCAT oil spill forecasting system is presented in this paper, and an evaluation of the impact of errors in the forcing fields over its forecasts is carried out. The system is formed by several independent modules which provide forecasts of winds, currents and waves to an oil spill module which predicts the evolution of the spill.The typical twin-experiments experience is used paying special attention to a realistic characterization of the errors when perturbing the forcing fields. The results suggest that errors in the wind and current fields are the main limiting factor for the quality of the oil spill forecasts. The pollutant identification is also crucial to determine the final vertical position and characteristics of the product. 相似文献
14.
付杰 《辽宁省交通高等专科学校学报》2012,14(1):27-29
本文介绍了高速公路建设中水土流失的成因及重点区域,并利用《辽宁省土壤侵蚀的定量分析》建立的数学模型,对我省即将建设的"盘锦辽滨疏港高速公路"项目可能产生的水土流失量进行预测,在工程实例中探讨了我省高速公路建设水土流失预测的方法,为我省高速公路建设中的水土保持工作提供了借鉴和参考。 相似文献
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受造船管理模式、生产场地资源等条件制约,造船企业生产计划安排不均衡的现象时有发生,由此引发的劳动力需求不均衡的现象在各个造船生产部门不同程度的存在,如何根据造船生产计划,有效地预测各生产阶段的劳动力需求,进行劳动力资源余缺调剂,一直是造船企业在努力探索的热门话题。本文试图运用数理统计的原理,借助计算机辅助工具(专业的软件),通过研究历史统计资料一实动工时的累积曲线,结合造船生产计划安排并考虑未来情况的变动,估计预测期内的累积曲线,以比例趋势法预测未来劳动力的需求量。 相似文献
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This article assesses the most likely technological developments in transport, not only by investigating current innovations but also by observing different approaches to confronting future developments. The article discusses technology forecasting and the meaning of environmentally sound technologies; some insights into technology development and the relevance of technological forecasting; the factors that influence technology development in transport; and, in this context, differentiation between exploration, expectation and forecasting. It goes on to identify, from four different perspectives, major developments of strategic relevance for the transport sector that might arise in the longer term. An assessment is made of the consequences of these observations for the implementation of innovations in transport. 相似文献
17.
Robert Bain 《Transportation》2009,36(5):469-482
Traffic forecasts are employed in the toll road sector, inter alia, by private sector investors to gauge the bankability of
candidate investment projects. Although much is written in the literature about the theory and practice of traffic forecasting,
surprisingly little attention has been paid to the predictive accuracy of traffic forecasting models. This paper addresses
that shortcoming by reporting the results from the largest study of toll road forecasting performance ever conducted. The
author had access to commercial-in-confidence documentation released to project financiers and, over a 4-year period, compiled
a database of predicted and actual traffic usage for over 100 international, privately financed toll road projects. The findings
suggest that toll road traffic forecasts are characterised by large errors and considerable optimism bias. As a result, financial
engineers need to ensure that transaction structuring remains flexible and retains liquidity such that material departures
from traffic expectations can be accommodated.
Robert Bain spent the first 15 years of his career as a traffic and transportation consultant before joining the infrastructure team at Standard & Poor’s in 2002. He is currently retained by the rating agency on a freelance basis and, separately, provides transport-related technical support services to infrastructure funds, insurance companies and institutional investors. Robert recently completed a PhD at the Institute for Transport Studies—hence his affiliation with the University of Leeds. 相似文献
Robert BainEmail: |
Robert Bain spent the first 15 years of his career as a traffic and transportation consultant before joining the infrastructure team at Standard & Poor’s in 2002. He is currently retained by the rating agency on a freelance basis and, separately, provides transport-related technical support services to infrastructure funds, insurance companies and institutional investors. Robert recently completed a PhD at the Institute for Transport Studies—hence his affiliation with the University of Leeds. 相似文献
18.
作者通过对铁路建设项目经济评价业务特点的分析,提出了利用计算机辅助经济评价的设计思想,并对运量预测、运营成本计算的算法作了详细讨论。 相似文献
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为研究华东地区夏季无砟轨道温度梯度的分布规律同时对高温时期的温度梯度进行预警管理,运用统计学方法研究轨道板温度梯度的分布规律并得到其预警限值,同时构建贝叶斯网络预测模型,对华东地区夏季无砟轨道温度梯度质量进行预测与评价。研究结果表明:华东地区夏季正温度梯度预警限值为66. 5℃/m,负温度梯度预警限值为-31. 5℃/m;贝叶斯网络预测模型具有88. 6%的准确率,可良好预测无砟轨道温度梯度的质量等级,同时由贝叶斯的诊断推理功能得出环境温度和太阳辐射是造成无砟轨道温度梯度异常的主要原因。 相似文献