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Seok-Min Lim 《Maritime Policy and Management》1994,21(2):149-160
Based on recent operation performance data, the earnings and costs of container service have been investigated in the context of two inches developed by the japanese and used elsewhere in East Asian shipping: charater base. Although the average size of container ships on the world's main trade routes has increased over the past two decades it is dangerous to generalize about the ecnomies of scale derived from larger ship size. The effects of ship's on voyage results vary in accordance with such factors as ship's purchase price, level of running costs, level of freight rates, voyage length, achieved load factors and accounting methods used for allocating fixed costs. The question of optimum vessel, therfore, has no generally applicable answer. Shipowners must compromise. 相似文献
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从以往的对船舶的抗碰撞分析研究中,发现有两个因素在很多分析中被忽略,一个是船舶碰撞中最易破坏位置的选择,另一个是在某些船舶舷侧舱水存在时忽略了其对船舶抗碰撞性能的影响.通过对典型结构进行仿真分析,指出船舶最佳碰撞位置的选择并非一定位于通常所认为的强框架中心点处,而是取决于板与加强筋的相对刚度,以及撞击船撞头的形状,以及通过某FPSO双舷侧结构为例分析了在舷侧舱水存在的情况下,由于撞击的短时和水的惯性迟滞效应,使得提高了船舶的抗碰撞性能.对这两个因素的分析有助于今后更加完善的对船舶抗碰撞性能进行评估. 相似文献
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This paper is the second of two companion papers concerning the ultimate hull girder strength of container ships subjected to combined hogging moment and bottom local loads. The nonlinear finite element analysis in Part 1 has shown that local bending deformation of a double bottom due to bottom lateral loads significantly decreases the ultimate hogging strength of container ships. In this Part 2, extending Smith's method for pure bending collapse analysis of a ship's hull girder, a simplified method of progressive collapse analysis of ultimate hogging strength of container ships considering bottom local loads is developed. The double bottom is idealized as a plane grillage and the rest part of the cross section as a prismatic beam. An average stress-average strain relationship of plate/stiffened plate elements employed in Smith's method is transformed into an average stress-average plastic strain relationship, and implemented in the conventional beam finite element as a pseudo strain hardening/softening behaviors. The extended Smith's method is validated through a comparison with nonlinear finite element analysis. 相似文献
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The environment issue is one of the significant challenges that the liner shipping industry has to face. The International Maritime Organization (IMO) has set a goal to reduce greenhouse gas (GHG) emissions from existing vessels by 20–50% by 2050 and develop the Energy Efficiency Operational Indicator (EEOI) as a measure for energy efficiency. To achieve this goal, IMO has suggested three basic approaches: the enlargement of vessel size, the reduction of voyage speed, and the application of new technologies. In recent times, liners have adopted slow steaming and decelerated the voyage speed to 15–18 knots on major routes. This is because slow steaming is helpful in reducing operating costs and GHG emissions. However, it also creates negative effects that influence the operating costs and the amount of GHG emissions at the same time.This study started with the basic question: Is it true that as voyage speed reduces, the operating costs and CO2 emissions can be reduced at the same time? If this is true, liners will definitely decelerate their voyage speed themselves as much as possible so that they can increase their profits and improve the level of environmental performance. However, if this is not true, then liners will concentrate just on increasing their profits by not considering environmental factors. This led the authors to set out three objectives: (1) to analyze the relationship between voyage speed and the amount of CO2 emissions and to estimate the changes by slow steaming in liner shipping; (2) to analyze the relationship between voyage speed and the operating costs on a loop; and (3) to find the optimal voyage speed as a solution to maximize the reduction of CO2 emissions at the lowest operating cost, thus satisfying the reduction target of IMO. 相似文献
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Bart W. Wiegmans Anthony Van Der Hoest Theo E. Notteboom 《Maritime Policy and Management》2013,40(6):517-534
This paper deals with the importance of port choice and container terminal selection for deep-sea container carriers. The paper focuses on the research question: on what basis do deep-sea container operators select container ports (strategy) and container terminals (financial reasons) in the Hamburg–Le Havre range over others? In answering this research question, three dimensions are addressed in detail: the buying decision characteristics; port choice strategy; and terminal selection. The results show that strategic considerations at company level are important. For port choice the most important criteria from a carrier's perspective are: availability of hinterland connections; reasonable tariffs; and immediacy of consumers (large hinterland). In addition to these criteria, shipping lines attach great value to often neglected factors, such as feeder connectivity, environmental issues and the total portfolio of the port. The study reveals that port selection and terminal selection are not the same with terminal selection criteria mainly depending on: handling speed; handling costs; reliability; and hinterland connections. The analysis also brought forward that the decision making is different per container carrier, per trade and per port type, implying that a one size fits all approach is not relevant. 相似文献
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船舶在波浪中航行时的纵向运动性能是衡量船舶综合航行性能的重要指标.为了改善船舶在波浪中的纵向运动性能,本文基于首部减摇组合附体技术对某型船首部构型进行改造并通过水池模型试验对其静水阻力和耐波性进行了分析研究.在分析该船作业及航区特点的基础上,通过船首部线型改造及减纵摇组合附体构型优化,给出适用于该船的首部构型方案.应用CFD软件和修正切片法进行水动力性能分析,并对船首构型方案进行优选.将优选出的性能较优复合船型方案和原船型开展水池模型静水阻力与耐波性对比试验分析,验证减摇复合船型的静水阻力性能与耐波性能.试验结果表明,改造后的复合船型减纵摇效果明显,对应实船四级海况18节航速下纵摇与首部加速度有义值较原船型降低15%以上;复合船型静水阻力有所增加,实船18节航速下静水阻力增加13.5%. 相似文献
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S. Gilman 《Maritime Policy and Management》2013,40(2):95-102
The introduction of unit load methods, particularly the cellular container system, has been associated with a large increase in ship size on some of the world's major general cargo routes. In this sector, ship size is determined by a set of interactions between handling performance, route length, traffic flow, itinerary, requirements for frequent and regular service, port costs and general system organization. This paper explores these relationships to identify major influences and to consider the prospects for further growth. 相似文献
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针对船体变形测量技术大多处于理论仿真的局限性,提出了基于实船试验的船体变形测量技术,考虑到测量速度的需要及静态变形角缓慢变化的特征,推导了基于角速率匹配法"准静态"模型。采用Kalman滤波技术对Mochalov模型和"准静态"模型下的变形角进行了估计,从实船试验的角度验证了船体变形的产生原因,拓展了"准静态"模型适用范围,进一步分析了舵操作对船体变形角的影响。试验结果表明,"准静态"变形角对缓变静态变形角跟踪效果良好,提高了静态变形角的测量精度,为光纤陀螺船体变形测量技术的实际应用奠定了坚实的基础。 相似文献
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Simme Veldman Lorena Garcia-Alonso José Ángel Vallejo-Pinto 《Maritime Policy and Management》2013,40(5):509-522
For the economic and financial evaluation of port investment projects, it is important to know the demand function of a port's services. The objective of this study is to establish such a demand choice function for the Spanish container port services. The function is derived from the coefficients of a port choice model, for which a multinomial logit model is used and of which the coefficients are estimated with regression analysis. The variables tested concern inland transport cost, ocean transport costs and broad proxy variables for quality of service. Information on container import and export flows for 2007 is obtained from the Spanish Treasury Department. The linear regression analysis is based on differences of utilities of alternative routings of containerised cargoes compared to those routed via the port of Valencia. The obtained results are satisfactory in terms of model fit. The estimated coefficients can be used to assess the impact of changes in costs of container flows routed via a port on a port's market share. A demand choice function for the port can be derived by systematically doing so. An example is presented for the port of Valencia. 相似文献
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在船速较低的肥大型船舶上,安装球鼻艏会在很大程度上降低船舶受到的阻力,球艏对艏部型线有缓和的作用,使船舶艏部水流发生改变,减少艏底漩涡,从而降低形状阻力,进而改善船舶的水动力性能。根据设计的10万吨级半潜船船型的船模静水阻力试验情况,该船舶船首由直立型改为球鼻艏型式,通过对原型和改进后的船型的阻力试验结果进行对比,检验了新船型的减阻性能,同时对船尾伴流场进行了研究,发现船首形状改变对尾部半流场影响不大 相似文献