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101.
江苏岸外辐射沙脊群东沙稳定性研究 总被引:8,自引:0,他引:8
东沙是江苏岸外辐射沙脊群中的第二大沙洲,具有独特的地形地貌和水动力条件,对它进行稳定性研究为揭示整个辐射沙洲及其邻近岸滩的动态演变都非常有益。通过利用多年遥感卫片资料、1998年取得的现场水文泥沙观测资料和东沙滩面表层沉积物资料等,对东沙的地形地貌特征、沉积特征和东沙两侧潮汐通道的水流泥沙特征等进行了详细分析。研究结果表明,东沙的沙脊偏于西侧,西侧滩面较窄、高程较高且岸线较为顺直,东侧滩面较宽、高程较低且岸线较为破碎;西洋和陈家坞槽均处于冲刷状态,净输沙的主要方向为输向槽外或输向条子泥;东沙近三十年来面积有所缩小且有外围向中央收缩的趋势,尤其以向东、向南方向的迁移最为明显。 相似文献
102.
A moving particle image velocimetry (PIV) system was successfully developed and used in a large towing tank for ship model tests to observe velocity fields near ship models. The experimental method involved adjustable optical devices for various test conditions and a special particle-seeding device. The streamwise and cross-streamwise flow fields of a yacht model and a tanker model were measured. Ship type, bottom shape, and towing speed were found to be the causes of problems affecting optical access and image quality. Possible solutions, deeper optical ducts, dark painting color, and pre-processed analysis method, were proposed and discussed. 相似文献
103.
104.
Ulla Botelho Machado 《Applied Ocean Research》2002,24(6):321-330
In this article a method to estimate the mean upcrossing intensity, μ(u), of a stochastic process is proposed. It is assumed that the stochastic process is a sum of a Gaussian process and a second-order correction term. The method is based on the two-dimensional Saddlepoint approximation. The accuracy of the method is tested on processes having analytical solutions for μ(u). Numerical examples are given where the stochastic process represents (i) the horizontal response of a floating offshore structure in a Gaussian sea, and (ii) the response of a structure subjected to a Gaussian wind velocity process. In addition, the estimates are compared to empirical upcrossing intensities of simulated responses. For case (ii), the obtained μ(u) estimates are compared to estimates obtained by numerical integration. 相似文献
105.
对冲绳海槽1984-1990年的实测热流值,利用数字滤波方法计算,得到反映该区深部地壳热状态的区域热流值为80-160mW/m^2,用B样条函数法对其作数值模拟,计算出海槽地温场模式,并以此研究冲绳海槽海底高热流的形成机制,得出冲绳海槽热流值的区域性变化与綦中地质构造格局呈正相关,高热流是该区现代构造活动所致,其明显特征是地壳减薄,地幔上拱等结论。 相似文献
106.
107.
Lawrence W. Harding Jr Blanche W. Meeson Thomas R. Fisher Jr 《Estuarine, Coastal and Shelf Science》1986,23(6)
Chesapeake Bay is a large and productive estuary that has received close scrutiny in recent years because of indications that its water quality and biota have been damaged by man's activities. Data on primary production for the estuary as a whole, however, are surprisingly sparse. We describe here the distribution of photosynthetic carbon assimilation by phytoplankton in Chesapeake Bay, and relate productivity patterns to hydrographic characteristics of the estuary. Between March 1982 and April 1983, a series of four cruises was conducted on Chesapeake Bay, and two cruises on the urbanized Delaware Bay for comparison. The upper Chesapeake and Delaware were highly turbid with high concentrations of suspended particulate matter and dissolved inorganic nutrients. Low chlorophyll concentrations were usually found in these areas of high turbidity, despite the abundance of nutrients, suggesting light limitation. Application of Wofsy's (1983) model of phytoplanton growth confirmed this suggestion. Chlorophyll and productivity maxima usually occurred seaward of the turbidity maxima where light penetration increased and suffient nutrients were present to support active phytoplankton growth. Further seaward of the chlorophyll maxima in the Chesapeake, the photic zone depth increased, concentrations of nutrients decreased, and phytoplankton biomass decreased, suggesting that nutrient availability, rather than light, controlled phytoplankton growth in the lower portion of the estuary. In contrast to the Chesapeake, Delaware Bay was more turbid, had generally higher nutrient concentrations, and was lower in phytoplankton productivity. The chlorophyll maxima and region of rapid phytoplankton growth occurred further toward the lower estuary and shelf regions in Delaware Bay because the high turbidity extended further seaward. Nutrients were never depleted at the shelf end of the estuary sufficiently to retard phytoplankton growth. Photosynthesis-irradiance (P-I) curves from simulated in situ and constant intensity incubations showed a strong correlation of the light-limited slope (aB) with the light-saturated rate (
) on each cruise. Spatial variations in
corresponded to patterns of phytoplankton abundance, as did integral production (PP) and carbon-based growth rates (μC, μm), and photosynthetic parameters varied significantly with temperature. 相似文献
108.
计算域的选取对风暴潮数值模拟的影响 总被引:3,自引:1,他引:3
作者以 72 0 3号台风过程中引起的黄海沿岸水文测站的风暴潮过程为例 ,选取不同计算域 ,模拟计算的同一测站的风暴潮增水值有很大差异。只有选取整个黄渤海海域 ,才能得到较精确的风暴潮增水结果。从而揭示在封闭或半封闭海域中由风暴过程激发的区域自由振荡 ,是风暴潮增水中不容忽视的量。说明该海域中的风暴潮过程是海域整体效应的响应 ,因此认为数值模拟中计算域应选取整个封闭或半封闭海域 相似文献
109.
礁膜配子放散条件的研究 总被引:2,自引:0,他引:2
本文报道了礁膜配子的放散与温度、光照、比重的关系。结果表明,自然海区的礁膜在白天大量放散配子。配子放散的适宜温度为19-21℃;光照为2000-5000lx时能促进配子大量放散出来;配子放散的适宜比重为1.05-1.025;这些研究结果将为礁膜人工育苗提供一些科学依据。 相似文献
110.
提出用B样条函数求解曲线、曲面上重磁位场的向上延拓,水平、垂向导数计算,磁异常分量互换的方法。该方法的特点是:原理简明,程序通用性强,计算精度高。 相似文献