A finite element model of interaction between viscous free surface waves and submerged cylinders     

Gang Zhu  Alistair G. L. Borthwick  Rodney Eatock Taylor 《Ocean Engineering》2001,28(8)

This paper describes the simulation of the flow of a viscous incompressible Newtonian liquid with a free surface. The Navier–Stokes equations are formulated using a streamline upwind Petrov–Galerkin scheme, and solved on a Q-tree-based finite element mesh that adapts to the moving free surface of the liquid. Special attention is given to fitting the mesh correctly to the free surface and solid wall boundaries. Fully non-linear free surface boundary conditions are implemented. Test cases include sloshing free surface motions in a rectangular tank and progressive waves over submerged cylinders.  相似文献   

Species, tissue and gender-related organochlorine bioaccumulation in white-sided dolphins, pilot whales and their common prey in the northwest Atlantic   总被引：5，自引：0，他引：5  

Weisbrod AV  Shea D  Moore MJ  Stegeman JJ 《Marine environmental research》2001,51(1):29-50

Organochlorine concentrations were measured in white-sided dolphins, pilot whales, and their prey from the Gulf of Maine and used to identify species, tissue, and gender differences, and trophic transfer trends, in bioaccumulation. Polychlorinated biphenyl concentrations ([PCB]) in dolphin blubber (13 +/- 7.1 micrograms/g fresh wt.) were twice those in pilot whales, but pesticide concentrations (20 +/- 13 micrograms/g fresh) were similar between species. 4,4'-DDE, trans-non-achlor, Cl6(153) and Cl6(138) concentrations were highest. Skin tissues had more recalcitrant organochlorines than the internal organs. Male dolphins bioaccumulated higher concentrations of nonmetabolizable PCBs and hexachlorocyclohexane (HCH) isomers, whereas pilot whales had no gender-related differences in bioaccumulation. Pilot whales, mackerel, and herring had proportionately higher concentrations of DDTs, whereas [PCB] were higher in dolphins and squid. Although these odontocetes feed at the same trophic level and store a similar suite of contaminants, dolphins bioaccumulated higher and potentially hazardous 4,4'-DDE and PCB concentrations from food in their more geographically restricted range.  相似文献   

The mixing efficiency and the processes of restratification in a stably stratified medium     

V. S. Maderich  O. M. Konovalov  S. I. Konstantinov 《Physical Oceanography》1994,5(1):21-26

The mechanism of the effect of a collapsing turbulent eddy on diapycnal transport in a stably stratified fluid is considered. It is shown that at small Richardson turbulent numbersRi ₀ the mixing efficiency increases asRi ₀, and at large numbers it decreases in proportion toRi ₀ ^–1/2 .Translated by Mikhail M. Trufanov. UDK 551.465.15.  相似文献   

The structure,dynamics, and transformation of the estuary lenses in run-off seawater on the shelf of Guinea     

V. N. Eremeev  A. S. Samodurov 《Physical Oceanography》1994,5(3):159-176

Peculiarities of the dynamics and the structure formation in the estuary run-off lenses have been analysed based on field data obtained at the Guinean coast (the central eastern Atlantic Ocean). Attention was paid to the processes of restratification, internal mixing, and exchange in the areas of the frontal zone of the run-off lens and the tidal frontal zone. The stabilization of the front of the estuary run-off lens by means of the periodic washing out of its forepart by tidal upwelling is described. The mechanisms of the energy transformation in the leading part of the lens have been revealed. Effects of run-off and loczalization of transformed waters in the small-scale frontal zones are found. The energy estimations represented will be useful in considering analogous phenomena in other coastal regions.Translated by Mikhail M. Trufanov.  相似文献   

A B-spline based higher order panel method for analysis of steady flow around marine propellers     

G.-D. Kim  C.-S. Lee  J.E. Kerwin 《Ocean Engineering》2007,34(14-15):2045-2060

A higher order panel method based on B-spline representation for both the geometry and the solution is developed for the analysis of steady flow around marine propellers. The self-influence functions due to the normal dipole and the source are desingularized through the quadratic transformation, and then shown to be evaluated using conventional numerical quadrature. By selecting a proper order for numerical quadrature, the accuracy of the present method can be increased to the machine limit. The far- and near-field influences are shown to be evaluated based on the same far-field approximation, but the near-field solution requires subdividing the panels into smaller subpanels continuously, which can be effectively implemented due to the B-spline representation of the geometry. A null pressure jump Kutta condition at the trailing edge is found to be effective in stabilizing the solution process and in predicting the correct solution. Numerical experiments indicate that the present method is robust and predicts the pressure distribution on the blade surface, including very close to the tip and trailing edge regions, with far fewer panels than existing low-order panel methods.  相似文献   

Water vapor in the atmosphere over the northern Tien Shan     

V. N. Aref’ev  F. V. Kashin  V. K. Semenov  R. M. Akimenko  N. E. Kamenogradskii  N. I. Sizov  V. P. Sinyakov  L. B. Upenek  V. P. Ustinov 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):739-751

Refined data of systematic measurements of total water vapor in the atmosphere from May 1980 to April 2005 are presented. The data were obtained at the Issyk Kul atmospheric-monitoring station by the method of solar molecular-absorption spectroscopy. Over 25 years, the annual mean water-vapor content in the atmosphere increased by 4.5% at a mean rate of increase of 0.18% per year. However, the water-vapor content decreased in the last five years. The results of statistical processing of experimental data (general statistical characteristics, correlation coefficients, composite oscillations) are described. A refined model is proposed for forecasts of temporal variations in the monthly mean and annual mean water-vapor contents for the coming years. The model includes a linear trend and the sum of oscillations with periods close to the periods of a number of well-known geophysical phenomena. Regression equations are proposed to relate the water-vapor content in the atmospheric column to the surface temperature and absolute humidity.  相似文献   

Bacterial killing by Mytilus hemocyte monolayers as a model for investigating the signaling pathways involved in mussel immune defence     

Canesi L  Scarpato A  Betti M  Ciacci C  Pruzzo C  Gallo G 《Marine environmental research》2002,54(3-5):547-551

The signaling pathways involved in mussel immune defence were investigated utilizing a model of killing of Escherichia coli by Mytilus galloprovincialis hemocytes in a co-culture setting. In particular, the role played by different mitogen activated protein kinases (MAPKs) and by the production of eicosanoids were investigated utilising specific cell permeant, pharmacological enzyme inhibitors. Hemocyte pretreatment with the p38 MAPK inhibitor SB203580 significantly reduced bacterial killing, whereas PD98059 (an inhibitor of ERK--extracellularly regulated kinase--MAPK activation) had no significant effect. Wortmannin also inhibited bacterial killing, indicating a crucial role for PI3-kinase activation in the immune response. Killing of E. coli was also reduced by inhibitors of both PLA2 and cyclooxygenase activities, indicating that eicosanoid production is involved in mediating the response to bacterial challenge. The results demonstrate that bacterial killing by mussel hemocytes is particularly sensitive to inhibitors of the key steps involved in the transduction of bacterial signals into the host cell. Moreover, these data indicate that the hemocyte bactericidal activity can be suitably utilized not only for identifying the signaling pathways involved in the response to bacterial infection, but also as a potential investigative-toxicology model to test drugs and contaminants for their effect on the overall mussel immune defence.  相似文献   

印度东南部海岸拉梅斯沃勒姆滨外保克湾底层水特征对底栖有孔虫的影响     

Kumar V  高莉玲 《海洋地质前沿》2001,17(12):13-15

有孔虫生活在海洋和半咸水环境。底栖有孔虫的存在很大程度上受物理因素（深度、温度、光量、水体扰动）、化学因素（盐度、溶解氧和可用元素）和生物因素（食物供给量和底层沉积物特征）的制约。研究人员对印度东、西岸现代底栖有孔虫生态学和分布状态进行了研究。Ｎａｉｄｕ等在对Ｖｉｓａｋｈａｐａｔｎａｍ港复合体有孔虫进行分析后提出 ,可以将有孔虫作为海洋污染的指示物。ＳｒｅｅｎｉｖａｓａＲａｏ等采用Ｑ模式系数分析对尼赞伯德讷姆湾有孔虫的分布进行了研究 ,确认此区域存在４种组合 ,受不同环境条件的影响。Ｋｈａｒｅ等对门格…  相似文献   

Methods of fitting the Fisher-Tippett type 1 extreme value distribution     

D.J.T. Carter  P.G. Challenor 《Ocean Engineering》1983,10(3):191-199

Methods are described for estimating the parameters of the Fisher-Tippet Type 1 extreme value distribution and associated return values from measured extremes, such as maximum wave height. A comparison of these methods, with simulated data, shows that those using Gumbel's plotting position are least satifactory. Maximum likelihood methods give the smallest mean square errors, but the very much simpler method of moments is nearly as good.  相似文献   

Validation of the stochastic distorted-wave Born approximation model with broad bandwidth total target strength measurements of Antarctic krill   总被引：2，自引：0，他引：2  

Demer  David A; Conti  Stephane G 《ICES Journal of Marine Science》2004,61(1):155-156

In the computations of SDWBA_TTS(f) in Figure 4, the scatteredvector was integrated over all orientations in the XY plane,where X is the main axis of the krill, but a factor of 2 was  相似文献