共查询到20条相似文献，搜索用时 31 毫秒
1.
In this paper, the radar cross section of flat plates on ocean surfaces is statistically investigated. A combining method of physical optics and geometric optics is applied to establish an effective backscattering analysis procedure. This method is a high-frequency analysis method originally derived from a simplified Stratton-Chu integral equation, assuming that the radar is far away from the target so that Kirchhoff approximation is valid. A Monte-Carlo simulation method is adopted to statistically analyze the effects of undulated ocean surfaces. The ocean surfaces are randomly generated by Pierson-Moskowitz ocean wave spectrum and a directional distribution function. Numerical investigations are carried out for flat plates, with the same height and width but with different inclined angles, on ocean surfaces of various significant wave heights. 相似文献
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海洋背景磁场模拟计算及东中国海表层磁场分布 总被引：1，自引：0，他引：1
海洋中海水的运动会切割地球磁场,生成微弱的电场,进而在海洋内部和周围空间激发感生电磁场,即约为地球磁场一万至十万分之一的微弱海洋背景磁场.文中针对海洋背景磁场的生成机制及近几十年来对海洋背景磁场的理论研究,结合世界磁场模型WMM2005,模拟计算了三种典型的海洋运动--海浪、海流、内波所产生的感应磁场,建立了海洋背景磁场的数值计算模型,并在此基础上设计开发了海洋背景磁场的模拟计算软件.最后用卫星多传感器资料驱动普林斯顿海洋动力学模式,得到的东中国海2005年海洋表层环流数据,模拟计算了东中国海海表层磁场分布,对其磁场变化与分布规律作了简要分析. 相似文献
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海浪的视景仿真有重要的应用背景与军事意义。文中围绕如何解决海浪的实时视景仿真问题,讨论了基于海浪谱的不同浪级波面的仿真模型,并讨论了海浪的实时视景仿真实现技术。这些模型与技术对于提高海浪仿真实时性与真实性有一定的参考价值。 相似文献
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A commonly used method of simulating ocean waves from a specified frequency spectrum is shown to be incorrect. The method consists of adding numerous sine curves with random phases; and the error arises from assuming that the amplitudes of these component sine waves are deterministic, when they are in fact random variables. Methods of using random amplitudes are described and only one is found to be satisfactory. In this method the number of random values simulated — and then transformed with an inverse FFT — equals the required number of simulated data points. So simulation in the frequency domain can only give relatively short runs; it is necessary to work in the time domain if arbitrarily long runs are required.Errors in wave group statistics derived from the incorrect simulation method are discussed and related to discrepancies reported between groupiness in simulated data and ocean measurements. 相似文献
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波浪作用下刚性框架浮体及其锚绳运动数值模拟精度分析 总被引：2，自引：1，他引：1
由小尺度刚性杆件构成的复杂结构近年来多用于海洋平台建设和海洋监测浮标制作以及海洋增养殖人工浮鱼礁的设计。采用有限单元法和集中质量点法建立波浪作用下刚性框架浮体及其锚绳运动数值模型,探讨空间单元划分、时间离散步长、数据保存格式对刚性框架浮体和柔性锚绳运动模拟精度的影响,分别给出此三者之间的匹配关系。研究结果表明:框架浮体的单元划分可依据是否出水给定,单元的划分比建议取0.05;锚绳的单元划分与其上端连接的浮体浮力有关,当锚绳的拉力主要由上端浮体浮力产生时锚绳单元的划分影响较小,当锚绳的拉力主要由波浪力产生时锚绳单元的划分比建议取0.02;空间单元划分与时间离散步长存在匹配关系,通过减小时间步长来追求数值模拟精度时必须同时考虑保存运动物理量截断误差的影响。 相似文献
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福建沿海海域波浪能资源分析与评价 总被引：2，自引：0，他引：2
采用波浪模拟的方法,较准确计算得出福建沿海海域波浪能资源分布状况,并给出相应的分析和综合评价.主要结论如下:(1)福建沿海海域波浪能平均密度为2.6～7.3 kW/m,波浪能资源储量为2 210.45 MW,在我国沿海海域仅次于台湾和广东,是波浪能开发利用可以优先考虑的海区之一.(2)福建沿海海域波浪能资源储量的70%分布于平潭岛以北海域,其值达1 512.49 MW.其中,尤以北礵地区值最大,为378.80 MW.(3)以年平均波高为指标,福建沿海海域中东山区段为三类区,其他区段均为一类区和二类区,具有良好的开发前景.(4)福建沿海海域波浪能具有波功率密度低、资源分布广泛且不均匀、波功率密度随季节变化、能量具有多向性等分布特点.(5)基于福建波浪能的开发与利用现状,建议应优先着眼于解决边远海岛等特殊场所的用电问题. 相似文献
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Long term wave climate of both extreme wave and operational wave height is essential for planning and designing coastal structures.
Since the field wave data for the waters around Korean peninsula is not enough to provide reliable wave statistics, the wave
climate information has been generated by means of long-term wave hindcasting using available meteorological data. Basic data
base of hindcasted wave parameters such as significant wave height, peak period and direction has been established continuously
for the period of 25 years starting from 1979 and for major 106 typhoons for the past 53 years since 1951 for each grid point
of the North East Asia Regional Seas with grid size of 18 km. Wind field reanalyzed by European Center for Midrange Weather
Forecasts (ECMWF) was used for the simulation of waves for the extratropical storms, while wind field calculated by typhoon
wind model with typhoon parameters carefully analyzed using most of the available data was used for the simulation of typhoon
waves. Design wave heights for the return period of 10, 20, 30, 50 and 100 years for 16 directions at each grid point have
been estimated by means of extreme wave analysis using the wave simulation data. As in conventional methodsi of design criteria
estimation, it is assumed that the climate is stationary and the statistics and extreme analysis using the long-term hindcasting
data are used in the statistical prediction for the future. The method of extreme statistical analysis in handling the extreme
events like typhoon Maemi in 2003 was evaluated for more stable results of design wave height estimation for the return periods
of 30–50 years for the cost effective construction of coastal structures. 相似文献
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An information system for ocean wave resources and its application to wave power utilizationare indtroduced.It can manage,analyze and process the data in the monthly report of ocean wave observa-tion records of the State Ocean Administration,and can provide various kinds of curves and numericalcharacters of statistics.This system has been put into utility in Guangzhou Institute of Energy Conversion(GIEC),the Chinese Academy of Sciences since 1996.An application example is given of theinverstigation and analysis on ocean wave resource of the Nan Ao Island,Guangdong Province,where a100 kW onshore OWC(oscillating water column)wave power station will be built.The wave power distri-bution is obtained in different wave directions for different wave periods.It is found that 70 percent of thewave power comes from the direction of ENE,and more than 95 percent of the wave power is related withdirection E.The average wave power density is about 3 kW/m,and more than 80 percent of the wavepower is distributed in the 相似文献
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The paper discusses short- and long-term probability models of ocean waves. The Gaussian theory is reviewed, and nonlinear short-term probability distributions are derived from a narrow band second-order model. The nonlinearity has different impact on different measurement techniques, and this is further demonstrated for wave data from the WAVEMOD Crete measurement campaign and laser data from the North Sea. Finally, we give some examples on how the short-term statistics may be used to estimate the probability distributions for the maximum waves during individual storms as well as in a wave climate described by long-term distributions. 相似文献
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基于星载波谱仪海浪方向谱探测原理,仿真了不同海况、风速下的海浪波谱仪接收信号,并采用周期图法、Welch法、AR模型法以及最小方差法共4种不同的调制谱估计方法反演出海浪谱,比较各种调制谱估计方法的海浪方向谱反演性能。仿真结果表明:对于一定方位向下的一维海浪谱反演,不同调制谱估计方法反演海浪谱性能优劣没有绝对的顺序。对于二维海浪谱反演,在成长中海浪条件下周期图法反演性能最差,其他3种方法的反演性能没有绝对优劣顺序;对于成熟风浪,最小方差法在积分能量误差、有效波高误差两个指标上的反演性能最好,在主波波向、主波波长误差上,周期图法反演性能最差,其他3种方法没有绝对优劣顺序。在涌浪条件下,AR模型法反演性能优于其他3种方法。在不同海况下,随着波谱仪中心入射角的下降,反演性能会下降。基于这些仿真结果,本文推荐最小方差法作为充分成长海浪的海浪方向谱反演的调制谱估计方法,AR模型法作为涌浪海浪方向谱反演的调制谱估计方法。 相似文献
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所谓海浪过程的数值模拟,就是根据预先给定的海浪过程的谱密度模拟出与之对应的海浪过程,然后利用它去研究各种有关的问题.例如,当研究多桩柱石油平台的结构物经受波浪影响时,可以把波浪对结构物的作用问题看作一个随机过程系,用几个点的联合海浪过程模拟来处理.文献[1]中,已给出单过程海浪模拟实现的方法步骤.但是,由于伪随机数的产生及富氏变换的正、余弦函数的运算在电子计英机土所需要的时间,随着离散序列和迭加子波数的增加而急剧增加,从而使模拟波面需要的时间较长.为此我们寻求快速模拟海浪波面过程的方法.本文提出运用FFT算法的快速模拟联合海浪过程的模式,并以单过程为例说明FFT在海浪数值模拟中的应用. 相似文献
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Qiao Fangli 《海洋学报(英文版)》1996,15(2):145-158
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In conventional marine seismic exploration data processing, the sea surface is usually treated as a horizontal free boundary. However, the sea surface is affected by wind and waves and there often exists dynamic small-range fluctuations. These dynamic fluctuations will change the energy propagation path and affect the final imaging results. In theoretical research, different sea surface conditions need to be described, so it is necessary to study the modeling method of dynamic undulating sea surface. Starting from the commonly used sea surface mathematical simulation methods, this paper mainly studies the realization process of simple harmonic wave and Gerstner wave sea surface simulation methods based on ocean wave spectrum, and compares their advantages and disadvantages. Aiming at the shortcomings of the simple harmonic method and Gerstner method in calculational speed and sea surface simulation effect, a method based on wave equation and using dynamic boundary conditions for sea surface simulation is proposed. The calculational speed of this method is much faster than the commonly used simple harmonic method and Gerstner wave method. In addition, this paper also compares the new method with the more commonly used higher-order spectral methods to show the characteristics of the improved wave equation method. 相似文献
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The effect of the wave-induced mixing on the upper ocean temperature in a climate model 总被引：3，自引：1，他引：2
The significant underestimation of sea surface temperature （SST） and the temperature in the upper ocean is one of common problems in present climate models. The influence of the wave-induced mixing on SST and the temperature in the upper ocean was examined based on a global climate model. The results from the model coupled with wave-induced mixing showed a significant improvement in the simulation of SST and the temperature in the upper ocean compared with those of the original model without wave effects. Although there has still a cold bias, the new simulation is much closer to the climatology, especially in the northern ocean and tropical ocean. This study indicates that some important physical processes in the accurate simulation of the ocean may be ignored in present climate models, and the wave-induced mixing is one of those factors. Thus, the wave-induced mixing （ or the effect of surface waves） should be incorporated properly into climate models in order to simulate or forecast the ocean, then climate system, more accurately. 相似文献
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有界赤道大洋波包解及其年际年代际变率 总被引：1，自引：0，他引：1
Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results are as follows. The wave packet is a superposition of eastward travelling Kelvin waves and westward travelling Rossby waves with the slowest speed, and satisfies the boundary conditions of eastern and western coasts, respectively.The decay coefficient of this solution to the north and south sides of the equator is inversely proportional only to the phase velocity of Kelvin waves in the upper water. The oscillation frequency of the wave packet, which is also the natural frequency of the ocean, is proportional to its mode number and the phase velocity of Kelvin waves and is inversely proportional to the length of the equatorial ocean in the east-west direction. The flow anomalies of the wave packet of Mode 1 most of the time appear as zonal flows with the same direction. They reach the maximum at the center of the equatorial ocean and decay rapidly away from the equator, manifested as equatorially trapped waves. The flow anomalies of the wave packet of Mode 2 appear as the zonal flows with the same direction most of the time in half of the ocean, and are always 0 at the center of the entire ocean which indicates stagnation, while decaying away from the equator with the same speed as that of Mode 1. The spatial structure and oscillation period of the wave packet solution of Mode 1 and Mode 2 are consistent with the changing periods of the surface spatial field and time coefficient of the first and second modes of complex empirical orthogonal function(EOF)analysis of flow anomalies in the actual equatorial ocean. This indicates that the solution does exist in the real ocean, and that El Ni?o-Southern Oscillation(ENSO) and Indian Ocean dipole(IOD) are both related to Mode 2.After considering the Indonesian throughflow, we can obtain the length of bounded equatorial ocean by taking the sum of that of the tropical Indian Ocean and the tropical Pacific Ocean, thus this wave packet can also explain the decadal variability(about 20 a) of the equatorial Pacific and Indian Oceans. 相似文献
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山东省周边海域波浪能资源评估 总被引：2，自引：0，他引：2
采用第三代海浪模式SWAN对2001-2010年期间山东省周边海域的波浪状况进行了数值模拟。波浪能数值模拟值与台站观测值的比对结果表明模拟值可靠、实用。分析发现山东省周边海域平均波能流密度以2 000W/m以下为主,低于中国南部海域及欧美沿岸波能流密度。选取12个典型代表点,从波能流密度大小、变化特征、稳定性等角度分析了不同代表点的波浪能情况,发现山东周边波能流密度受气候变化影响近10年来呈上升趋势。综合不同区域波浪能大小及需求情况,建议选取山东半岛东部海域、蓬莱外围岛屿近渤海中部海域和渤海中部海域作为波浪能开发利用的首选区域。其中成山头东部海域波能流密度在冬季高达5 000 W/m,在该季节大部分区域可归为一类资源丰富区。基于此,建议开发利用中小规模的波浪能供电设备或供电设施。 相似文献
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Calibration coefficients incorporated in the modified Weibull distribution are more effective for maximum wave height simulation. The parametric relations are derived there from to estimate various wave height statistics including extreme wave heights. The characteristic function of the Weibull distribution is derived. The Weibull distribution is suggested for the newly defined significant wave height simulation by the method of characteristic function. The statistical tools suggested and developed here for predicting the required wave height statistics are validated against the wave data (both deep and shallow) of eastern Arabian Sea comprising rough monsoon conditions also, giving reasonable accuracy. 相似文献