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The scattering problem involving water waves by small undulation on the porous ocean-bed in a two-layer fluid,is investigated within the framework of the two-dimensional linear water wave theory where the upper layer is covered by a thin uniform sheet of ice modeled as a thin elastic plate.In such a two-layer fluid there exist waves with two different modes,one with a lower wave number propagate along the ice-cover whilst those with a higher wave number propagate along the interface.An incident wave of a particular wave number gets reflected and transmitted over the bottom undulation into waves of both modes.Perturbation analysis in conjunction with the Fourier transform technique is used to derive the first-order corrections of reflection and transmission coefficients for both the modes due to incident waves of two different modes.One special type of bottom topography is considered as an example to evaluate the related coefficients in detail.These coefficients are depicted in graphical forms to demonstrate the transformation of wave energy between the two modes and also to illustrate the effects of the ice sheet and the porosity of the undulating bed. 相似文献
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学习贯彻十七大精神,对于动员拿党全国各族人民,存以胡锦涛同忠为总书记的党中央坚强领导下,高举中国特色社会主义伟大旗帜,奋力夺取全面建没小埭社会新胜利、圩创中国特色礼会主义事业新局而,具有重大现实意义和深远历史意义。长汀航道各级党组织要把组织学习和贯彻落实十七大精神作为当前和今后一个时期的首要政治任务,迅速把干部职工的思想和行动统一到全会精神上来, 相似文献
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<正>众所周知,三一重工股份有限公司是一家享有盛誉的上市公司,曾连续4年上榜中国最具价值品牌,是工程机械行业内的标志性企业之一。作为中国最具科研实力的工程机械制造商,三一重工拥有国家级技术中心、博士后工作站,并承接有国家863课题,取得专利400多项。三一重 相似文献
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0引言近年来全球集装箱运量的年增长率基本维持在10%以上,据初步统计2007年全球集装箱运量达1.3亿TEU,港口吞吐量达4.7亿TEU。随着集装箱制造、装卸工艺的改进,适箱货物的范围也在不断扩大。20世纪90年代,美国就开始采用集装箱运 相似文献
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美国海岸警备队港口长官(COTP)或口岸当局(OCMI)对存在缺陷的船舶,根据缺陷的严重性,决定对这些船舶采取控制行动来保证船舶、港口和环境的安全,至于控制的程度、范围以及当局的执行力则和这些缺陷的本性一致. 相似文献
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Global strength is a significant item for floatingproduction storage and offloading (FPSO) design, and steel weightplays an important role in the building costs of FPSO. It is the maintask to consider and combine these two aspects by optimizing hulldimensions. There are many optional methods for the globalstrength analysis. A common method is to use the ABS FPSOEagle software to analyze the global strength including the rulecheck and direct strength analysis. And the same method can beadopted for the FPSO hull optimization by changing the depth.After calculation and optimization, the results are compared andanalyzed. The results can be used as a reference for the futuredesign or quotation purpose. 相似文献
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由丹丹;孙丽萍;曲治国;王涛 《船舶与海洋工程学报》2013,12(4):459-462
For a large floating vessel in waves,radiation damping is not an accurate prediction of the degree of roll unlike other degrees of freedom motion.Therefore,to get the knowledge of roll motion performance of deepwater pipelay crane vessels and to keep the vessel working safety,the paper presents the relationship between a series of dimensionless roll damping coefficients and the roll response amplitude operator(RAO).By using two kinds of empirical data,the roll damping is estimated in the calculation flow.After getting the roll damping coefficient from the model test,a prediction of roll motion in regular waves is evaluated.According to the wave condition in the working region,short term statistics of roll motion are presented under different wave parameters.Moreover,the relationship between the maximal roll response level to peak spectral wave period and the roll damping coefficient is investigated.Results may provide some reference to design and improve this kind of vessel. 相似文献
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D.E. Pitfield 《Research in Transportation Economics》2008,24(1):5-14
The phenomenon of the wide world growth in low-cost airlines has resulted in a focus on their pricing strategies, on issues of cost recovery and on their impact on the traffic and market shares of legacy carriers or other low-cost carriers when they are in competition, either directly or at adjacent airports.This paper provides a brief overview of the characteristics of these low-cost carriers as well as their history and geography. It goes on to outline ways in which these carriers compete and manage demand, ranging from price competition to advertising; some of these methods directly reflect their special characteristics. Some empirical evidence is presented which indicates a correlation in fare setting behaviour between competitors and insights are offered on cost recovery.The impact of the start-up of low-cost carriers is also analysed, focusing on their impacts on other low-cost carriers. The case of Ryanair competing with easyJet on London-Venice is examined along with Southwest and Frontier on Denver-Las Vegas. 相似文献
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依托中科炼化离岸式码头工程,通过波浪物理模型试验,对码头桩基墩台底面压强和上托力进行研究。首先,在不同墩台底面相对超高条件下,分析了墩台底面波浪压强作用过程以及分布,对作用的两种压强类型(冲击压强和缓变压强)进行探讨,给出了墩台底面同步平均相对压强与墩台底面相对超高的变化关系。然后,在不同墩台底面相对超高条件下,分析了墩台上托力变化过程,并将最大相对上托力与最大相对同步压强进行比较分析。最后,将上托力试验结果与几种典型方法的计算结果进行比较。相关研究提供了深水离岸式码头的桩基墩台上托力计算依据,可供类似工程借鉴。 相似文献
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为使船舶达到绿色、环保的要求,并解决能源紧缺问题,在船上广泛应用太阳能是一种有效途径。介绍太阳能在船上应用的现状和相关规范对太阳能在船上应用的规定。分析在800PCC滚装船上应用太阳能的优势,给出该船的基本参数和航线,结合这些基本信息分析该船太阳能光伏电力系统的结构和运行模式。通过研究总结出该船应用太阳能可带来能效指数提高的积极效应。 相似文献
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文中通过分析国外LNG船舶船员培训的现状和当前内河LNG动力船舶常用知识和技能,结合笔者跟船的的实际操作体会,对内河LNG动力船舶船员培训相关内容进行初步探讨。 相似文献