共查询到20条相似文献,搜索用时 125 毫秒
1.
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
2.
3.
4.
5.
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
6.
<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
7.
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
8.
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
9.
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
10.
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
11.
常微分方程具有一般数学的特点:抽象性、严密性,又具有本身的特点,即与工程技术紧密相连,实用性强.而常数变易法是解线性微分方程行之有效的一种方法。 相似文献
12.
This paper presents the uncertainty modelling of experimental results for a physical model of a tanker moored to a terminal inside a port. The physical model was built for an oil terminal at the port of Leixões in Portugal. The model incorporates the new modified port layout, as well as a future 300 m extension of the port outer north breakwater to enhance operational conditions. The physical model tests were performed on a scale of 1:80 in the Portuguese Civil Engineering Laboratory (LNEC). A generic mooring system of four mooring lines and two fenders is simulated using a nonlinear spring system. Decay tests are carried out to evaluate the natural periods of the moored model. Then, tests are carried out for the moored model in waves. The major aim of the experimental study is to obtain novel results for the wave elevation and direction at various locations inside the port, the ship motions at six degrees of freedom, and loads on mooring lines and fenders including the modified port layout. As the physical model measurements are subjected to different types of uncertainties, a systematic uncertainty analysis is carried out here, following ITTC guidelines and recommendations, to quantify all possible sources of uncertainties. The results are discussed, and several conclusions are reached. Based on the experimental results, the presented physical model study may replicate the results for waves and motions with uncertainties less than 9% of the significant amplitudes. The assessment of the applied nonlinear spring model reveals load predictions on the moorings, with uncertainties less than 4% of the maximum mooring loads. 相似文献
13.
14.
15.
16.
麦哲伦(Magellan,Ferdinand),葡萄牙著名航海家和探险家.先后为葡萄牙(1505~1512)和西班牙(1519—1521)作航海探险。5个多世纪以来,人们对麦哲伦崇拜得很,都把他看作是世界英雄,因为他是第一个完成环球航行的航海家。这一创举实际上以无可争辩的事实证明了地圆说。从这个意义上讲,麦哲伦的确是 相似文献
17.
为优化某船用柴油机的燃烧室的"油-气-室"匹配,降低有害物排放,运用AVL Fire对原型燃烧室改用不同燃烧室进行额定工况模拟.结果表明,高低型双涡流室双缩口燃烧室能在上涡流室形成"飞轮效应",相对于原型燃烧室,不仅能增加功率,而且能降低Nox和SOOT的排放.对高低型双涡流室双缩口燃烧室设置不同的高低涡流室的半径比r/R和喷油夹角进行计算.结果表明:随着r/R从0.3增加到1.3,Nox和SOOT的排放量均先减少后增多;当r/R为0.7时,Nox和SOOT的排放量均最少.当喷油夹角为140°~165°时,随着喷油夹角的增大,Nox的排放量先减少后增加,随后再减少,最后又升高;SOOT排放量先减小后增大,随后再减小. 相似文献
18.
19.
Characteristics of a bubble jet near a vertical wall 总被引:1,自引:0,他引:1
A numerical model of a coupled bubble jet and wall was built on the assumption of potential flow and calculated by the boundary integral method. A three-dimensional computing program was then developed. Starting with the basic phenomenon of the interaction between a bubble and a wall, the dynamics of bubbles near rigid walls were studied systematically with the program. Calculated results agreed well with experimental results. The relationship between the Bjerknes effect of a wall and characteristic parameters was then studied and the calculated results of various cases were compared and discussed with the Blake criterion based on the Kelvin-impulse theory. Our analyses show that the angle of the jet's direction and the pressure on the rigid wall have a close relationship with collapse force and the bubble's characteristic parameters. From this, the application range of Blake criterion can be determined. This paper aims to provide a basis for future research on the dynamics of bubbles near a wall. 相似文献
20.