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381.
382.
383.
A polar method for obtaining wave resonating quadruplets {K1, K2, K3, K4} in the computation of nonlinear wave–wave interaction source term of the wave model is presented with results for both deep and finite water depths. The method first determines the end radial points of the locus equation for K2, for each set of input wave vectors (K1, K3) on the symmetry. The locus of K2 (and hence K4) is then traced in the anti-clockwise direction starting with the maximum radial point on the line of symmetry. It is shown that when k3>k1, the number of points on the locus varies when the orientations of the input wave vectors are changed and reduces when the difference in the magnitude of the input wave vectors is increased. A significant advantage in this method is that the angular increment on the locus for K2 can be kept constant. 相似文献
384.
Shallow-Water Gasohydrothermal Vents of Ushishir Volcano and the Ecosystem of Kraternaya Bight (The Kurile Islands) 总被引:2,自引:0,他引:2
V. G. Tarasov M. V. Propp L. N. Propp A. V. Zhirmunsky B. B. Namsakakv V. M. Gorlenko D. A. Starynin 《Marine Ecology》1990,11(1):1-23
Abstract. A marine ecosystem in the crater of the Ushishir Volcano (Kraternaya Bight, Yankich Island, the Kuriles) showing gasothcrmal activity was studied for hydrographical, hydrochemical, and biological characteristics. Maximal changes in chemical and biological characteristics were observed in the surface water layer of 0–5 m. This layer had higher water temperature, was saturated with volcanogcnic carbon dioxide (up to 2000 10-6 torr), ovcrsaturatcd with oxygen (up to 200 %), and contained high concentrations of chlorophyll a. Hydrogen sulfide was found in the surface water layer and at a depth of 15 m in the area of maximal effect of volcanic effluents.
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr2 -d-l , chcmolithotrophy predominating. Bottom settlements had high population density and great animal biomass, which reached 10 kg m-2 in gasohydrothermal fields. They obtain sufficient energy from primary production of microphy-tobenthos, algobacterial, and bacterial mats. Bcnthic species dominant in the bight were not found off the Ushishir Islands.
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight. 相似文献
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight. 相似文献
385.
M. Arockiasamy H. El-Tahan A.S.J. Swamidas W.E. Russell D.V. Reddy 《Ocean Engineering》1984,11(5):463-490
The paper presents an analytical and experimental study on the transient response of semisubmersibles to bergybit impact and the strength of bergybit ice to high strain-rate loadings. Two approaches have been proposed for the solution of the semisubmersible-bergybit interaction problem, one using the energy approach and the other using the conventional structural dynamics approach with initial velocity conditions. In addition the local behaviour of the impacted regions have been analysed for deformation and failure. Numerical results have been given for local behaviour of an impacted column and global behaviour of semisubmersible-bergybit system. Experimental study has been reported on the impact strength of iceberg ice at strain rates of 10−3, 10−2 and 10−1; the indentation impact strength of ice is found to be 3–4 times the unaixial compressive strength, at the same strain rate. 相似文献
386.
Highly sensitive microstructural probes subjected to noise disturbances are free of these in laboratory tests. This leads necessarily to the working out of methods for complex testsin situ. The paper reports on the successful use for this purpose of a grate (net) suspended from a free-falling probe. The grate sets up turbulence with reproducible structure in the area of sensor location.UDK 551.46.085 相似文献
387.
388.
One of the most efficient tools of studying meteorological and climatic time series is wavelet analysis, which allows local properties of a nonstationary time series to be examined. New sets of continuous and discrete wavelet-forming functions are proposed. All proposed wavelets are finite (have a bounded carrier), even, and well localized in the spectral space. 相似文献
389.
Hotspots in ambient noise caused by ice-edge eddies in the Greenland and Barents Seas 总被引:1,自引:0,他引:1
Johannessen O.M. Sagen H. Sandven S. Stark K.V. 《Oceanic Engineering, IEEE Journal of》2003,28(2):212-228
Mesoscale eddies are frequently observed in the Greenland and Barents Seas' marginal ice zone (MIZ). The objective of this study was to investigate the hypothesis that acoustic hotspots along the ice-edge region are due to mesoscale eddy currents interacting with the broken-up ice floes in the MIZ. To test this hypothesis, ambient-noise case studies were carried out during the MIZEX 85-87 and SIZEX 89 field experiments. In each experiment, ice-edge eddies were localized visually from aircraft and by use of satellite remote-sensing data obtained in near real time. Sonobuoys were, thereafter, deployed by fix-wing aircraft and helicopters in selected eddy areas. Ambient-noise data, recorded over several hours by aircraft, were analyzed estimating averaged ambient-noise levels at four selected frequencies: 40, 100, 315, and 1000 Hz. The analysis showed high mean levels and large gradients in ambient noise near ice-edge eddies and during strong wind and wave forcing against the ice edge. The conclusion of this study is that mapping of the ice edge and localization of mesoscale ocean processes using remote sensing from space will provide important input to ambient-noise prediction in the MIZ. 相似文献
390.
V.Hachemi Safai 《Applied Ocean Research》1983,5(4):215-225
The paper presents a theoretical and numerical approach to the dynamical behaviour of risers in deep water which takes into account two types of nonlinearity; that due to viscous drag forces and that due to the large displacements of the riser when submitted to strong axial loads. As the second nonlinearity may have a significant influence upon the behaviour of risers in deep water, a method for automatically updating the structural geometry during the dynamic analysis is given. A computer programme has been written for this purpose. 相似文献