排序方式: 共有43条查询结果,搜索用时 15 毫秒
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对美国<海岸防护手册>(SPM)中估计不规则波浪下越浪率的计算公式作了分析并对其不足进行了改进,提出利用规则波越浪率来计算不规则波作用下越浪率的一个新的公式.认为当建筑物堤顶高程(从静水面算起)为零时,越浪率不仅与波高有关,波速也是一个重要的影响因素,SPM 法的假定不符合实际的工况,导致 SPM 法不是低估就是高估了越浪率的大小.通过数值模拟,将新改进的公式与 SPM 法、实验数据、以及经验公式作了对比,表明新公式是比较合理的,其计算结果可以作为工程设计的参考依据. 相似文献
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基于局部条纹频率估计的二维高斯滤波方法 总被引:1,自引:0,他引:1
提出一种基于局部条纹频率估计的干涉相位图二维高斯滤波方法。该方法采用最大似然法估计局部条纹频率,并用相位噪声的局部标准差评价噪声强度,从而控制滤波器参数实现自适应滤波,并采用仿真数据和SIR-C/XSAR在意大利Etna火山的干涉数据进行试验,将本算法与均值滤波方法和中值滤波方法以及Goldstein滤波方法进行了比较。试验结果表明,该方法不仅能够有效抑制干涉相位噪声,还能够很好地保持干涉条纹的细节信息。 相似文献
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Zheng Chongwei Liang Bingchen Chen Xuan Wu Guoxiang Sun Xiaofang Yao Jinglong 《中国海洋大学学报(英文版)》2020,19(3):479-488
Research on the diffusion characteristics of swells contributes positively to wave energy forecasting, swell monitoring, and early warning. In this work, the South Indian Ocean westerly index(SIWI) and Indian Ocean swell diffusion effect index(IOSDEI) are defined on the basis of the 45-year(September 1957–August 2002) ERA-40 wave reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) to analyze the impact of the South Indian Ocean westerlies on the propagation of swell acreage. The following results were obtained: 1) The South Indian Ocean swell mainly propagates from southwest to northeast. The swell also spreads to the Arabian Sea upon reaching low-latitude waters. The 2.0-meter contour of the swell can reach northward to Sri Lankan waters. 2) The size of the IOSDEI is determined by the SIWI strength. The IOSDEI requires approximately 2–3.5 days to fully respond to the SIWI. The correlations between SIWI and IOSDEI show obvious seasonal differences, with the highest correlations found in December–January–February(DJF) and the lowest correlations observed in June–July–August(JJA). 3) The SIWI and IOSDEI have a common period of approximately 1 week in JJA and DJF. The SIWI leads by approximately 2–3 days in this common period. 相似文献
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ZHENG Xilai WANG Bingchen LI Yuying XIA Wenxiang Institute of Environmental Science Engineering Ocean University of Chin Qingdao Shandong Comprehensive Institute of Geotechnical Survey Beijing 《《地质学报》英文版》2004,78(3)
On the basis of site investigation and sample collection of petroleum contaminants in the soil-water-crop system in the Shenyang-Fushun sewage irrigation area, the physical-chemical-biological compositions of the unsaturated zone is analyzed systematically in this paper. At the same time, the degradation kinetics of residual and aqueous oils is determined through biodegradation tests. The studies show that dominant microorganisms have been formed in the soils after long-term sewage irrigation. The microorganisms mainly include bacteria, and a few of fungus and actinomycetes. After a 110-days' biodegradation test, the degradation rate of residual oil is 9.74%-10.63%, while the degradation rate of aqueous oil reaches 62.43%. This indicates that the degradation rate of low-carbon aqueous oil 相似文献
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The perforated breakwater is an environmentally friendly coastal structure,and dissolved oxygen concentration levels are an important index to denote water quality.In this paper,oxygen transport experiments with regular waves through a vertical perforated breakwater were conducted.The oxygen scavenger method was used to reduce the dissolved oxygen concentration of inner water body with the chemicals Na_2SO_3 and Co Cl_2.The dissolved oxygen concentration and wave parameters of 36 experimental scenarios were measured with different perforated arrangements and wave conditions.It was found that the oxygen transfer coefficient through wave surface,K_1a_1,is much lower than the oxygen transport coefficient through the perforated breakwater,K_2a_2.If the effect of K_1a_1 is not considered,the dissolved oxygen concentration computation for inner water body will not be greatly affected.Considering the effect of a permeable area ratio α,relative location parameter of perforations δ and wave period T,the aforementioned data of 30 experimental scenarios,the dimensional analysis and the least squares method were used to derive an equation of K_2a_2(K_2a_2=0.0042α~(0.5)δ~(0.2)T~(-1)).It was validated with 6 other experimental scenarios data,which indicates an approximate agreement.Therefore,this equation can be used to compute the DO concentration caused by the water transport through perforated breakwater. 相似文献
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Modeling of suspended sediment transport with waveinduced longshore current in Huanghe (Yellow) River Delta 总被引:3,自引:2,他引:1
A three-dimensional suspended sediment model(SED)developed by the present authors is coupled with the combinatorial model of COHERENS(Luyten et al.,1999) (the three-dimensional coupled hydrodynamical-ecological model for Regional and Shelf Seas) and SWAN(Holthuijsen et al.,2004) (the third generation wave model).SWAN is regarded as a subroutine of COHERENS and gets time-and space-varying current velocity and surface elevation from COHERENS.COHERENS gets time-and space-varying wave relevant parameters provided by SWAN.Effects of wave on current are applied in bottom shear stress,wave-induced depth-dependent radiation stress and surface drag coefficient calculation.At the same time,the damping function of suspended sediment on turbulence is introduced into COHERENS.So the sediment model SED has feed back on circulation model COHERENS.The SED obtains current as sociated parameters from COHERENS.Then a couple dhydrodynamic-sediment model COHERENS-SED being able to account for interaction between wave and current is obtained.COHERENS-SED is adopted to simulate three-dimensional suspended sediment transport in the Huanghe River delta.In terms of simulation results,there is obvious diffierence between top and bottom layer of wave-induced longshore current.The values of time series of sediment concentration gotten by COHERENS-SED have,generally,an accepted agreement extent with measurement.Significant wave heights and wave periods obtained by COHERENS-SED show that wave simulation case with current’s effect can give better agreement extent with measurement than case without current’s effect.In the meantime,suspended sediment concentration distributing rule obtained by COHERENS-SED is similar to former researches and measurement. 相似文献