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941.
-In previous and this studies it appears that the linear and nonlinear wave theory can notaccurately and easily predict the water particle velocities.Therefore,different from the theoretical consider-ations,in this study we have attempted to determine the transfer function empirically.Laboratory experi-ments were performed under various wave conditions.The empirical formulas of the transfer function ofthe wave height,angular frequency and water particle velocity were obtained on the basis of these test databy dimensional analysis and regression analysis.In intermediate and deep water depth conditions,thetransfer function was only a function of a nondimensional parameter which is composed of the angular fre-quency,the depth of the velocity gauge under the still water level,water depth and the acceleration of grav-ity.Finally,the empirical formulas were compared with experimental data and observational data formpresent and Cavaleri's(1978)studies.The empirical formulas were found to be in sufficient correl 相似文献
942.
943.
分别于1986年12月和1985年3月1日—1987年3月1日在海州湾进行了波浪和含沙量观测,运用所获资料以及本区长期水文、地形资料,采用流体力学、沉积学和泥沙运动力学相结合的研究方法,建立了海州湾淤泥质海滩剖面堆积过程的二维计算模式。结果表明,在堆积型淤泥质海滩,由于浮泥的经常性存在,使波浪急剧衰减,其对岸滩的作用甚为微弱,潮流成为塑造淤泥质海滩的主要动力,岸滩在淤涨过程中,在平均高潮位厂沿和平均低潮位附近出现两个凸点,上一个凸点外推速率大于下一个凸点,潮下带变化缓慢。 相似文献
944.
G. H. Sutton F. K. Duennebier B. Iwatake J. D. Tuthill B. T. R. Lewis J. Ewing 《Marine Geophysical Researches》1981,5(1):3-34
The purpose of the experiment was to determine the effects of coupling and bottom currents on ocean bottom seismometers. Twelve operational OBSs, three specially designed three-component systems, and a hydrophone were compared with each other. Unlike seismometers placed on hard rock at land stations, ocean bottom seismometers can be affected by soft sediments (which act as lossy mechanical springs) and by buoyancy. Coupling through soft sediments can modify the response to ground motion much as a low pass filter does, and high buoyancy tends to counteract this effect. These effects are observed in the Lopez data, which consist of signals from mechanical transient tests, cap shots, airgun pulses, and general background noise. The modification of response is pronounced for some instruments and barely noticeable in others. Instruments that stand high in the water relative to their base width tend to be susceptible to rocking motion that shows up as a mechanical cross coupling between horizontal and vertical motion. Correlation of Lopez results with coupling theory suggests that it is possible to design ocean bottom seismometers that will couple well to any sediment. Current levels at the Lopez site (<5 cm s-1) were too small to produce noticeable effect on any of the instruments; however, the same design criteria that will minimize coupling problems will also lessen problems caused by ocean currents.Hawaii Institute of Geophysics Contribution No. 1171. 相似文献
945.
Francis G. Wyatt Jr. 《Ocean Engineering》1973,2(5):219-221
The design and use of a lightweight, retrievable, bottom-mounted current meter for taking current measurements to ocean depths of 1800 m are described. 相似文献
946.
G.P. Glasby 《Marine Chemistry》1973,1(2):105-125
The rare-earth distribution has been determined in five manganese nodules from a range of marine environments. Manganese nodules from Loch Fyne, Scotland, and the Gulf of Aden are characterized by a low absolute abundance of the rare-earth elements and a low Ce/La ratio compared with deep-sea nodules. This difference is interpreted in terms of the diagenetic remobilization of manganese in the high sedimentation regimes leading to the effective fractionation of manganese from the rare-earth elements and the resultant depletion of the rare earths in nodules from these environments. The mechanism of incorporation of the rare-earth elements into manganese nodules is thought to be either the direct adsorption of these elements from seawater or the scavenging of the elements by colloidal iron oxide prior to their incorporation into the authigenic phase of nodules. There appears to be no evidence for the surface transfer of these elements from inorganic detritus into the authigenic phase of nodules as suggested by previous authors. The distribution of U and Th in the nodules is controlled by factors similar to those controlling the rare-earth abundance in nodules. The higher U/Th ratios in nodules from Loch Fyne and the Gulf of Aden is considered to be due to the preferential reduction of UO2(CO3)34? to some lower-valency uranium species such as U3O8 in nodules from less oxidizing environments. 相似文献
947.
利用颗粒态放射性核素携带的颗粒物历经过程信息,我们提出用泥沙扩散方程和颗粒态放射性核素扩散方程联解底部边界层颗粒态物质迁移参数的方法。分析实例的样品取自荷兰Waden Sea南部Balgzand潮滩(砂坪)和Mok湾潮滩(泥坪)的两个站位(BG1和Mok2)。示踪核素为~(234)Th,~(210)Pb和~(137)Cs,其放射性比度由r能谱测出。 相似文献
948.
Sand ridges on the inner Atlantic shelf of North America: Morphometric comparisons with Huthnance stability model 总被引:1,自引:0,他引:1
A. G. Figueiredo Jr. D. J. P. Swift Stubblefield T. L. Clarke 《Geo-Marine Letters》1981,1(3-4):187-191
Sand ridge fields on the inner shelf of the Middle Atlantic Bight are generally thought to have formed in response to northeasterly
storm flows as the shoreface underwent erosional retreat with postglacial sea-level rise. However, the hydrodynamic mechanism
is poorly unerstood. Coastal boundary models see the ridges as responses of the seafloor to distortions in the flow induced
by the coastal boundary. Stability models propose that an irregular initial topography will evolve toward an ordered array
of bedforms in response to repeated flow events. The two classes of models are not mutually exclusive, nor are members within
each class mutually exclusive. Results of measurements of ridge spacing on the inner Atlantic shelf of North America agree
with the predictions of stability models. 相似文献
949.
G.F. Humphrey 《Marine Policy》1981,5(3):270-271
The deliberations at UNCLOS have been watched with great interest by individual marine scientists and by those who have attended as observers on behalf of scientific groups. Most of all these scientists have been apprehensive that their ability (freedom) to carry out research would be significantly limited by many of the provisions of the ICNT. In fact, one author goes as far as to state that progress has been made, largely at the expense of the marine research scientist1. 相似文献
950.
It is suggested that Bouvet Island is the surface manifestation of a mantle plume which has resulted in the creation of a chain of seamounts in the South Atlantic and a general shoaling of the region.The strike of two newly defined large fracture zones borth and south of the Bouvet Island pedestal have been utilized to determine a pole of rotation at 12.5°S, 12.5°W for the Africa-Antarctica motion. A pole at 75°S, 13°E has been calculated for the South America-Antarctica motion. At the triple junction the South America-Africa relative motion is 3.3 cm yr-1 (whole rate) at 075°. The Africa-Antarctica motion is 1.7 cm yr-1 at 065° and the South America-Antarctica motion is 1.6 cm yr-1 at 085. 相似文献