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991.
基于MTSP的机车周转图编制模型与算法   总被引:11,自引:0,他引:11  
为了提高机车的工作效率,探讨了机车周转图编制模型与算法.对于给定的列车运行图,综合考虑机车使用台数最少和图形均衡性,提出了一种编制机车周转图的新算法.将机车周转图编制问题转化为多旅行商问题(MTSP)并建立数学模型,从而求得问题的最优解.最后,用列车运行图实际数据进行了验证,证明了该算法的有效性.  相似文献   
992.
铁路货车运行品质考核指标研究   总被引:1,自引:1,他引:0  
陈雷  吕可维 《铁道学报》2006,28(3):111-115
简要回顾了我国铁道车辆运行平稳性标准的应用历史和现状,指出其中存在的主要问题,以图寻求改进我国评价铁路货车运行平稳性指标的可行途径。介绍了AAR和UIC中的相应标准的概况;阐述了铁路货车运行平稳性方面的主要矛盾;分析了采用运行平稳性指标评价铁路货车运行品质的一些具体问题。建议增加评价车辆纵向运行平稳性的指标,以更全面地反映和评价车辆的动态运行品质。提出了货车运行平稳性评价体系调整过程中应开展的主要工作和改进我国铁路货车运行平稳性标准的方向。建议以车体加速度峰值和均方根值作为考核铁路货车运行平稳性的主要指标,同时建议修建专用的试验线或扩展现有的试验线,以便更加客观地考核、比较和研究车辆的动态性能。  相似文献   
993.
建设项目跟踪审计中设计审计的探讨   总被引:4,自引:0,他引:4  
目前在建设项目的跟踪审计中,设计审计工作的开展多不到位。鉴于工程设计在项目建设中的重要性,跟踪审计人员应有意识地进行设计审计方面的有益探索和尝试。经济性是设计审计的重中之重,审计人员可通过设计方案优化,提出审计建议,将服务寓于监督之中,从而实现“绩效审计”的目标。  相似文献   
994.
    
Over the last decades, a dense population of the deep-sea/oceanic scyphozoan jellyfish Periphylla periphylla has established itself as top predator in the Trondheimsfjord in Norway, which has caused the traditional fisheries in this fjord to suffer. This was, however, not the first fjord this jellyfish invaded, and data suggest that it will not be the last one, either. With warmer temperatures, the jellyfish is moving northward in Norway, but not all fjords are created equal, and it is not thriving or taking up residence just anywhere. The current article explores three fjords in which Periphylla periphylla has become the top predator and outcompeted former ones. The main question of interest is why the jellyfish becomes dominant in one fjord and not another. The next question is which other Norwegian fjords further north exist with similar characteristics where we therefore would expect Periphylla periphylla to proliferate in the future. The latter is important from a policy and adaptation perspective for the local community of people, since the proliferation of the species unmistakably leads to fewer fish for commercial harvest and potentially less attractive waters for tourism purposes. Results show that three northern fjords, the Skjerstadfjorden the Holandsfjorden, and Stordjupna in the Vestfjord appear to be particularly vulnerable to a future Periphylla periphylla invasion.  相似文献   
995.
    
There has been an assumption that because many large marine protected areas (LMPAs) are designated in areas with relatively few direct uses, they therefore have few stakeholders and negligible social outcomes. This article challenges this assumption with diverse examples of social outcomes that are distinctive in LMPAs. We define social outcomes as inclusive of both social change processes and social impacts, where “social” includes all perceptual or material human dimensions. We draw on five in-depth case studies to report social outcomes resulting from proposed or designated LMPAs in Bermuda, Rapa Nui (Easter Island), Kiribati, Palau, and the Commonwealth of the Northern Mariana Islands & Guam. We conclude: (1) social outcomes arise even in remote LMPAs; (2) LMPA efforts generate social outcomes at all stages of development; (3) LMPAs have the potential to produce outcomes at a higher level of social organization, which can change the scope and type of affected populations and, in some cases, the nature and stakes of the outcomes themselves; (4) the potential for LMPAs to impart distinctive social outcomes results from their unique geographies and/or intersection with high-level politics and policy processes; and (5) social outcomes of LMPAs may emerge in the form of social change processes and/or social impacts.  相似文献   
996.
In 1976, Washington became the first state to implement the federal Coastal Zone Management Act (CZMA) primarily through the 1971 WA Shoreline Management Act (SMA). However, there has been little effort in Washington to evaluate outcomes of shoreline protection programs post SMA. In 2006–2008, we characterized shoreline conditions in San Juan County over three time periods spanning pre and post SMA and engaged community members to improve effectiveness of shoreline protection. We found modest improvements in forest retention on marine shorelines between pre and post 1977, but few other improvements through time. While we could not measure shoreline construction rates, construction practices for shore armor and overwater structures (docks) have changed very little, despite the increased regulatory standards. The vast majority of shore armor constructed post SMA occurred without mandatory county or state permits likely due to: widespread perception that permits were unnecessary and that permit standards were arbitrary and inconsistently applied; poor understanding of shoreline ecology by community members; lack of county or state enforcement authority and shoreline monitoring programs; and poor permit tracking systems.  相似文献   
997.
ABSTRACT

To establish an Association of Southeast Asian Nations (ASEAN) Single Shipping Market (ASSM) is an important part of ASEAN governments’ overall plan to achieve an ASEAN Economic Community by 2015. It is expected that a single shipping market will improve the region’s logistics performance and international competitiveness. To achieve this vision, however, the ASEAN countries need to remove any remaining barriers to logistics performance. In this light, the objective of this paper is to identify these barriers and assess their effects on the logistics performance of shipping and logistics firms based in ASEAN countries. Using a questionnaire-based survey, the study revealed several barriers affecting their logistics performance with varying significance among these countries. Unless these barriers from the perspective of the industry are removed, the ability of the shipping and logistics industry to benefit from a liberalized market would be limited. These perceived barriers are examined in detail and strategies to address them are proposed. The ASEAN experience is applicable to similar countries in the process of integrating their international shipping sector as well as contributes to the understanding of the different barriers and how these barriers can affect the logistics performance of shipping and logistics companies.  相似文献   
998.
制备一种玄武岩纤维/铝合金层合板复合结构,通过试验和仿真,探讨该复合结构的拉伸、压缩、剪切、弯曲和抗冲击特性。采用连续壳单元模拟纤维层,建立低速冲击仿真模型,从能量吸收、接触力和层合板损伤程度3个方面,研究铺层结构和冲击载荷角度对纤维金属层合板抗冲击性能的影响。最后,将纤维金属层合板应用于发动机罩外板,进行发动机罩静态刚度和行人头部碰撞仿真分析。结果表明,与原发动机罩相比,纤维金属层合板发动机罩的弯曲刚度和扭转刚度均有不同程度提高,行人头部保护性能得到改善。  相似文献   
999.
肘形橡胶软管平衡性能研究   总被引:1,自引:0,他引:1  
推导了肘形橡胶软管帘线缠绕的平衡角和实际缠绕角,利用非线性有限元软件MSC.MARC,分析了不同缠绕角的肘形软管在内压作用下的平衡性.结果表明,缠绕角大于平衡角时肘形管会外张,缠绕角小于平衡角时肘形管会内收;实际缠绕时,最佳平衡性点并不是在ψ=90°时缠绕角为54.7°,而是要比这个角度稍小一些.  相似文献   
1000.
Abstract

Traditional transport infrastructure assessment methodologies rarely include the full range of strategic benefits for the transportation system. One of these benefits is the contribution to cross‐border integration, critical for the European integration process. However, this is a key issue in strategic planning and decision‐making processes, as its inclusion may increase the probability of large‐scale transport infrastructure projects being funded. This paper presents a methodology for the measurement of the contribution of transport infrastructure plans to European integration. The methodology is based on the measurement of the improvement in network efficiency in cross‐border regions of neighbouring countries, via accessibility calculations in a Geographical Information System support. The methodology was tested by applying it to the ambitious road and rail network extensions included in the Spanish Strategic Transport and Infrastructure Plan (PEIT) 2005–2020. The results show significant and important network efficiency improvements of the PEIT outside the Spanish border. For the road mode, while the Spanish average accessibility improvement accounts for 2.6%, average improvements in cross‐border regions of France and Portugal are of 1.8%. And for the rail mode, the corresponding Spanish value is 34.5%, whereas in neighbouring regions it accounts for 20.2%. These results stress the significant importance of this strategic benefit and the consequent need for its inclusion in strategic planning processes. Finally, the paper identifies the potential of the methodology when applied at different administrative levels, such as the local or state levels.  相似文献   
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