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排序方式: 共有216条查询结果,搜索用时 31 毫秒
51.
This paper focuses on the response of port authorities to the changing market environment in which they operate. It documents the changes taking place in the relationships between port authorities and terminal management companies and considers the strategic issues faced by these groups and other port interests. In particular, it investigates the potential conflicts of interest for a port authority in matters related to the level of competition amongst terminals within a port and the amount of competition amongst ports. 相似文献
52.
管德 《交通运输工程学报》2001,1(2):8-9
简略地讨论了发展支线航空的两个关键因素,地区人均经济水平的提高和交通运输系统的综合优化,支线航空的发展,是必然的,但是一个渐过的过程,取决于上述两个因素所决定的市场需求,同时,还对飞机的可靠性和寿命对运营成本的影响,做了简略的分析。 相似文献
53.
设计一种适用于桥梁静载荷试验中极不完备数据条件下的优化GM(1,1)模型。使用3个前置神经网络模块替换传统模型中的微分拟合过程,利用神经网络的回归能力对其进行优化,使用1个后置神经网络模块结合1个数据解模糊模块替换传统模型的数据还原过程,其他数据处理方式沿用传统模型的数据处理方式。经过仿真计算,发现不同桥梁设计规模下,优化模型的标准差显著低于传统模型,证实优化模型具有较显著的算力提升。 相似文献
54.
Stef Proost Fay DunkerleyBruno De Borger Astrid GühnemanPia Koskenoja Peter MackieSaskia Van der Loo 《Transportation Research Part A: Policy and Practice》2011,45(3):161-170
The trans-European transport network (TEN-T) encompasses the major planned transport infrastructure in Europe, ranging from high speed rail to port infrastructure. Projects in this category are considered priority projects and receive European subsidies; but these have been insufficient to get these projects off the ground. This paper addresses two research questions. First, it sketches the basic economics of cross-boundary infrastructure projects: what pricing and investment policies can we expect, what is the role of through traffic and high fixed costs of infrastructure? Second, it examines briefly what lessons the EU could draw from the experience of other existing federal funding institutions like the US and Germany. These ideas are used to propose a new subsidy scheme for the TEN-T projects. 相似文献
55.
基于AQWA的旁靠油轮水动力相互作用研究 总被引:3,自引:0,他引:3
船舶旁靠系统的水动力响应是一个非常复杂的工程问题,系统中每一个结构的动力响应会受到其他结构的耦合影响。针对两旁靠FPSO和LNG运输船组成的旁靠系泊系统,基于三维势流理论,应用多体水动力学软件AQWA,在考虑两船间水动力相互作用的情况下,计算两旁靠船舶所受到的波浪载荷,并与不考虑两船水动力相互作用的计算结果进行对比分析。结果表明,旁靠系泊系统水动力相互作用是不可忽略的。同时也分析了不同旁靠间距对水动力性能的影响,结果发现旁靠间距只在中高频段时对水动力性能的影响较大。研究结果可为旁靠系统系泊方案的设计和研究提供一定的参考。 相似文献
56.
Carlo Scaffidi Salvatore De Caro Salvatore Foti Tommaso Scimone Antonio Testa 《International Journal of Automotive Technology》2018,19(6):1091-1101
An electrically assisted internal combustion engine is obtained by combining a conventional engine and one or more electrical motors of considerably smaller size. A key feature of such an innovative vehicle hybridization approach is that the torque generated by electric machines is not transmitted to the wheels. The electric motors are, in fact, intended only to assist the internal combustion engine in low efficiency, low performance, or high polluting working conditions. They however, draw extra power and energy from the battery. This paper presents a tool to evaluate different possible solutions in terms of energy balance, efficiency, battery stress and battery ageing. The method, which is based on suitable mathematical models and specific analysis criteria is also exploited to compare eight different configurations of a C-segment vehicle, pointing out limits and capabilities of traditional 12?14 V systems. 相似文献
57.
Kris De Baere Helen Verstraelen Lucien Lemmens Silvia Lenaerts Raf Dewil Yves Van Ingelgem Geert Potters 《Journal of Marine Science and Technology》2014,19(1):116-123
Sacrificial anodes have become a standard practice for the protection of ballast tanks of merchant vessels against corrosive damage. A well protected tank should extend the life span of a ship and consequently enhances its economic value. An in situ survey comprising more than 100 merchant vessels provided the opportunity to measure the impact of these anodes on the life expectancy of these vessels. Contrary to the general belief of these anodes’ beneficial effect, no significant difference was found in our observations in terms of corrosion occurrence between ship populations with and without sacrificial anodes, across all ship ages. This may be explained by the highly variable conditions and the complex geometry in a ballast tank severely impede optimal and straightforward installation of these anodes in these tanks. Also, poorly placed anodes in it may harm the integrity of the coating of the tank. We therefore plead for uniform and clear rules on anode installation and inspection. 相似文献
58.
Lisa-Ann Gershwin Monica De Nardi Kenneth D. Winkel Peter J. Fenner 《Coastal management》2013,41(1):22-41
Dangerous marine stingers (jellyfish) are an emotive issue in tropical Australia, where they are widely regarded as the number one marine health threat. However, numerous severe and fatal stings have been reported throughout the tropical and temperate seas of the world, indicating that marine stingers are a global health problem. Further, life-threatening jellyfish stings are more frequently reported globally now compared to earlier decades, possibly as a result of improved recognition and reporting, or increased spatial and/or temporal distribution or densities. As stinging incidents may also have significant financial implications (lost tourism revenues and liability settlements), and the treatment of envenomed patients comes at high cost to the taxpayer, this issue is also a management challenge. This article outlines suggested approaches, based largely on Australian experience, for dealing with this under-recognized global coastal management issue. 相似文献
59.
基于遗传算法自动舵模糊控制研究 总被引:3,自引:0,他引:3
本文采用遗传算法对模糊控制规则进行优化,并将之应用于船舶自动舵控制系统中。经过仿真证明,该方法和普通模糊控制相比具有较好的控制性能 相似文献
60.