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41.
通过对涂层性能新标准(PSPC)的分析和研究,在船舶建造的前期策划过程中,从船舶设计、工法设计、生产管理等各方面,分解涂层性能新标准(PSPC)各项要求到各个工序,再通过现场施工检验,进一步优化整个实施体系。 相似文献
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针对公路建设中发生的生态环境问题,以烟台公路生态路网建设为模板,构建区域生态公路建设的指标体系,对生态公路建设提出了系统性的解决方案。 相似文献
44.
Behdad Masih-Tehrani Susan H. Xu Soundar Kumara Haijun Li 《Transportation Research Part B: Methodological》2011,45(8):1128-1151
Disruptions and random supplies have been important sources of uncertainty that should be considered in the design and control of supply chains. There have been many real world examples in which a single catastrophic event has simultaneously degraded the capabilities of several suppliers leading to considerable erosion of profits and goodwill for a company. However, the literature on analytical models that account for the dependence nature of disruptions and its impact on supply chain performance is sparse.In this paper, we consider an m-manufacturer, 1-retailer, newsvendor inventory system with stochastically dependent manufacturing capacities, caused by random disruptions that may simultaneously inflict damages to the capacities of the manufacturers. We develop the structural/analytical properties of key performance measures and optimal inventory policies for the multi-source and assembly inventory systems. We show that stochastic dependence in disruptions can have opposite effects on system performance in the multi-source and assembly systems. While risk diversification is preferred in the multi-source system, risk concentration is preferred in the assembly system. Our results also suggest that, if the retailer ignores the effect of dependent disruptions, then in the multi-source structure, it would underestimate the cost, overestimate the fill rate, and order more units than the optimum; however, in the assembly structure, the opposite would happen. We perform a comprehensive numerical study to validate our analytical results and generate useful managerial and operational insights for effective risk management of supply chains in the presence of dependent supply uncertainty. 相似文献
45.
针对我国公路运输量调查的历史沿革、调查工作现状、目前存在的问题和不足进行分析论述,并提出改进意见和建议。 相似文献
46.
依据2项国家标准,分别采用氙弧灯和荧光紫外灯对不同颜色面漆漆膜的破坏性开展试验研究.试验结果显示,2种光源对面漆漆膜破坏性的区别主要表现在失光、色差和粉化方面.从成膜物质和试验条件方面分析试验结果的形成原因,比较2种光源对漆膜破坏的等效性. 相似文献
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Intermodal rail/road freight transport has always been considered as a competitive alternative to its road freight counterpart in the European medium- to long-distance corridors (markets). Such consideration has been based on the increasing competitiveness of some innovative rail services and the existing and prospective performance of both modes in terms of the full social – internal or operational and external – costs. The most recent innovation of rail technologies and related services launched by some European railway companies, still at the conceptual level, is the Long Intermodal Freight Train (LIFT). This is supposed to be a block train operating in long-distance corridors (markets) with a substantial and regular freight demand.This paper develops analytical models for assessing the performance of the LIFTs, the already-operating Conventional Intermodal Freight Trains (CIFTs), and their road counterpart as well. The performance consists of the full – internal (private) and external – costs of the door-to-door delivery of loading units – containers, swap-bodies, and semi-trailers. The internal costs embrace the operational costs of the transport (rail and road) and intermodal terminal operators. The external costs include the costs of the impacts of door-to-door delivery of loading units on society and the environment. These negative externalities include noise, air pollution, traffic accidents, and congestion.The models are applied to a simplified version of intermodal and road transport system using inputs from the European freight transport sector. The aims are to compare the full costs of particular modalities in order to investigate the potential of the LIFTs as compared with the CIFTs in improving the internal efficiency of the rail freight sector and its competitiveness with respect to its road counterpart. In addition, the paper attempts to assess some effects on the potential modal shift of EU (European Union) transport policies on internalizing transport externalities. 相似文献
49.
The number of variables involved in the monitoring of an ecosystem can be high and often one of the first stages in the analysis is to reduce the number of variables. We describe a method developed for geological purposes, using the information theory, that enables selection of the most relevant variables. This technique also allows the examination of the asymmetrical relationships between variables. Applied to a set of physical and biological variables (plankton assemblages in four areas of the North Sea), the method shows that biological variables are more informative than physical variables although the controlling factors are mainly physical (sea surface temperature in winter and spring). Among biological variables, diversity measures and warm-water species assemblages are informative for the state of the North Sea pelagic ecosystems while among physical variables sea surface temperature in late winter and early spring are highly informative. Although often used in bioclimatology, the utilisation of the North Atlantic Oscillation (NAO) index does not seem to provide a lot of information. The method reveals that only the extreme states of this index has an influence on North Sea pelagic ecosystems. The substantial and persistent changes that were detected in the dynamic regime of the North Sea ecosystems and called regime shift are detected by the method and corresponds to the timing of other shifts described in the literature for some European Systems such as the Baltic and the Mediterranean Sea when both physical and biological variables are considered. 相似文献
50.
为保证高速列车的行车安全,必须建立防止异物入侵的安全防范体系。在铁路客运专线与公路并行区段采用柔性防护时,必须预留一定的变形空间,以保证受到异物冲击后的柔性防护网不侵入铁路建筑限界。通过有限元仿真计算和现场性能试验,准确把握柔性防护网在规定的冲击能量作用下的最大变形数据。仿真和试验结果表明:柔性防护网的最大变形量随着冲击能量的增大而增大,最大变形距离达1.8 m以上。建议设置在铁路客运专线与公路并行区段之间的柔性防护网,其垂直冲击能量设计标准取为:一般区段9.3×104J,加强区段1.7×105J;且柔性防护网预留变形空间的宽度以不小于2.0 m为宜。 相似文献