排序方式: 共有86条查询结果,搜索用时 31 毫秒
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文章针对大藤峡水利枢纽通航建筑物规模小、过坝货运量不断增大的现状,结合原设计通航建筑物规模,提出了调整大藤峡水利枢纽通航建筑物规模的6个方案,同时通过对6个调整方案的船闸通行能力进行计算分析,获得了满足远期运输需求的最优方案。 相似文献
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采用理论和实际相结合的方法,分析运输范围经济和规模经济的内涵,从理论和实证两个方面指出运输范围经济与规模经济的相互区别及内在联系,确定运输业存在范围经济和规模经济两种经济形式。最后,在此基础上提出推进我国道路运输范围经济与规模经济发展的有效政策措施。 相似文献
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陈应先 《铁道标准设计通讯》2014,(11):1-6
通过3种途径探索中国终期路网规模。其一是对比分析,选择了与我国略有相近的美、德、法、波、印度5国铁路相比较。其二是需求分析。其三是运量、运输密度与路网关系的研究。结果建议:以运量低方案,客80亿人、货100亿t、运输密度4 000万·t·km/km计算的终期路网规模为31.5万km。 相似文献
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介绍OIML R106(2005—1CD版)《自动轨道衡》国际建议与JJG 234—1990《动态称量轨道衡》,分析两者之间的差异.并提出采标建议。 相似文献
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“十五”期间,我国铁路以实施《中长期铁路网规划》为主要标志,展开了大规模、高标准的铁路建设,在扩大路网规模、提升工程标准、控制工程质量、规范建设市场、加强建设管理等方面取得了显著成绩。“十一五”是铁路跨越式发展的关键时期,也是大规模铁路建设最关键的阶段,要以确保建设规模和工程质量为重点,以扩大路网规模、优化布局结构,强攻客运专线、实现“一流的工程质量、一流的装备水平、一流的运营管理”为主要任务,充分利用和整合资源,结合技术引进和自主创新,加快构建一流技术标准体系,有序推进续转和新上项目,确保工程质量、安全、工期、投资。2006年是“十一五”开局之年,要加快前期工作,保证新项目如期开工,深化质量管理达标、工程分包专项治理和打击内业资料弄虚作假“三项治理活动”,加强安全专项整治,攻克征地拆迁、设计供图和技术问题,确保年度计划的完成。 相似文献
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This paper is about distance and time as factors of competitiveness of intermodal transport. It reviews the relevance of the factors, evaluates time models in practice, compares network distances and times in alternative bundling networks with geometrically varied layouts, and points out how these networks perform in terms of vehicle scale, frequency and door-to-door time. The analysis focuses on intermodal transport in Europe, especially intermodal rail transport, but is in search for generic conclusions. The paper does not incorporate the distance and time results in cost models, and draws conclusions for transport innovation, wherever this is possible without cost modelling. For instance, the feature vehicle scale, an important factor of transport costs, is analysed and discussed.Distance and time are important factors of competitiveness of intermodal transport. They generate (direct) vehicle costs and – via transport quality – indirect costs to the customers. Clearly direct costs/prices are the most important performance of the intermodal transport system. The relevance of quality performances is less clarified. Customers emphasise the importance of a good match between the transport and the logistic system. In this framework (time) reliability is valued high. Often transport time, arrival and departure times, and frequency have a lower priority. But such conclusions can hardy be generalised. The range of valuations reflects the heterogeneity of situations. Some lack of clarity is obviously due to overlapping definitions of different performance types.The following parts of the paper are about two central fields of network design, which have a large impact on transport costs and quality, namely the design of vehicle roundtrips (and acceleration of transport speed) and the choice of bundling type: do vehicles provide direct services or run in what we call complex bundling networks? An example is the hub-and-spoke network. The objective of complex bundling is to increase vehicle scale and/or transport frequency even if network volumes are restricted. Complex bundling requires intermediate nodes for the exchange of load units. Examples of complex bundling networks are the hub-and-spoke network or the line network.Roundtrip and bundling design are interrelated policy fields: an acceleration of the roundtrip speed, often desirable from the cost point of view, can often only be carried out customer friendly, if the transport frequency is increased. But often the flow size is not sufficient for a higher frequency. Then a change of bundling model can be an outcome.Complex bundling networks are known to have longer average distances and times, the latter also due to the presence of additional intermediate exchange nodes. However, this disadvantage is – inside the limits of maximal vehicle sizes – overruled by the advantage of a restricted number of network links. Therefore generally, complex bundling networks have shorter total vehicle distances and times. This expression of economies of scale implies lower vehicle costs per load unit.The last part of the paper presents door-to-door times of load units of complex bundling networks and compares them with unimodal road transport. The times of complex bundling networks are larger than that of networks with direct connections, but nevertheless competitive with unimodal road transport, except for short distances. 相似文献
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H. McGeehan 《运输规划与技术》2013,36(3-4):221-229
The primary aim of the paper is to determine a short‐run cost function for Dublin City Bus Services (DCS), using a translog approach. The results show that there are significant economies of density in the transit operation. The results also indicate that the structure of DCS is characterised by a homothetic production function and that partial elasticities of substitution are non‐unitary. 相似文献
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This paper analyzes energy intensities of ships, diesel–fuelled railways, trucks, and aircraft, using publicly available data. The analysis suggests that differences in operation, not technology, explain most of the variation in energy intensity within and across modes. Among the operational characteristics, most important is the amount of cargo weight transported per vehicle and therefore the scale of the respective transportation system. It is found that each mode has a characteristic envelope in an average energy intensity versus average cargo weight diagram, and estimates of the elasticities of energy intensity with respect to load size are made. 相似文献
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分别介绍单台面静态衡、双台面静态衡和双台面动态衡、三台面动态衡的结构、原理,以及计量不同换长铁路罐车液态质量的方法,简述静态衡、动态衡的检定方法。 相似文献