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1.
基于海口站1976~1997年逐时潮位和逐日最大风速资料,利用阿基米德Copula函数构建海口年最大增水与相应日期最大风速的联合概率分布模型。结果表明:1)广义极值分布可作为海口站年最大增水和相应日期最大风速的边缘分布。两个序列之间存在强正相关关系,G-H Copula函数更适用于作为海口站年最大增水和相应日期的最大风速联合概率分布的连接函数。2)两变量联合作用的同频率增水高度设计值与增水的单变量边缘分布设计值之间的相对差值约为7.5%。3)条件概率1(P(Y≥y|X≥x))中同频率的年最大增水和相应风速的遭遇概率介于78.2%~80.9%,条件概率2(P(Y≥y|X≤x))中同频率的年最大增水和相应风速两者的遭遇概率小于4.8%。 相似文献
2.
基于copula函数论述了两变量的联合概率分布方法.此方法的主要优点是边缘分布可由不同的分布函数构成,变量间可具相关性.以粤东汕尾海域极值波高与相应风速为研究实例,经分析获得以下结果:(1)优选的极值波高和风速可分别由P-Ⅲ型和GEV 分布表示:(2)拟合优度检验指标表明二者的最优连接函数为Archimedean co... 相似文献
3.
选取渤海海域某导管架平台24年的年最大波高和相应风速,基于Gumbel分布对2个边缘分布的拟合优度检验,采用Archimedean Copula函数族中的4种函数构建两变量联合概率分布模型,并进行了拟合优度评价。利用优选出的Clayton Copula函数,计算风浪联合分布的联合重现值。以海洋平台响应作为约束条件,进行了二维Clayton Copula函数的风浪联合统计分析。研究结果表明:基于Copula函数构造的二维分布,考虑了风浪之间的相关性,在相同重现值设计参数下,可以降低导管架平台的结构响应,从而可以降低海洋平台的环境条件设计标准。 相似文献
4.
基于二元copula函数构建波高与相应波周期的长期联合分布。以粤东汕尾海域最大波高与相应平均周期为研究实例,经分析获得以下结果:(1)经拟合优度检验优选的年最大波高与相应周期的边缘分布分别为皮尔逊三型分布和广义极值分布,二者之间的较优连接函数为Archimedean类的Gumbel-Hougaard copula函数;(2)同频率条件下年最大波高和相应周期联合概率分布的设计要素值高于单变量的设计值,其中波高设计值的差异略大于周期设计值;(3)同现重现期和联合重现期的设计值可作为海岸海洋工程建设中的设计波高和相应周期的上限和下限;(4)条件概率1表明,同频率下的年最大波高和相应周期的遭遇概率很高,其组合概率可作为工程建筑物损毁风险率。 相似文献
5.
采用非对称Archimedean Copula函数与Kendall分布函数分析极端波况下的波高、周期和风速三变量联合概率分布与风险率及其设计分位数,为海岸海洋工程设计和风险评估提供参考依据。以粤东汕尾海域的实测风浪数据为例,使用非对称Gumbel-Hougaard Copula函数计算三变量风浪联合分布的"或"重现期、"且"重现期和二次重现期及其最可能的风浪设计值。主要结论如下:对比不同设计风浪重现期显示,"或"重现期的风险率偏高,"且"重现期的风险率偏低,二次重现期更准确地反映了特定设计频率情况下三变量风浪的风险率;按目前有关规范设计要求的单变量风浪要素设计值已经达到安全标准,按三变量"或"重现期和三变量同频率设计值推算的风浪设计值偏高,以最大可能概率推算的三变量风浪要素的二次重现期设计值可为相关工程安全与风险管理提供新的选择。 相似文献
6.
应用广义Pareto分布(GPD)分析超阈值波高序列的设计值。以位于美国北卡罗来纳州的FRF历时32年连续测量的逐日波高序列为例,检验了不同波高阈值样本的泊松分布,采用多种方法综合确定最佳阈值的拟合优度指标。对最优广义Pareto分布和GEV分布及P-Ⅲ分布推算的波高重现水平做了对比分析。得到以下结论:(1)波高的GPD属于短尾型分布;(2)拟合优度指标表明构建的波高GPD模型普遍优于GEV和P-Ⅲ型;(3)GPD的参数估计方法对设计波高的计算结果有较大影响。 相似文献
7.
南海北部海面风速概率分布特征 总被引：1，自引：1，他引：0
利用南海北部的浮标、石油平台观测的海面风资料，分析了0~200 km范围内，不同离岸距离站点的风速的概率分布特征。观测结果指出，各站平均风速一般最大值出现在冬季，最小值出现在夏季，具有明显的季节变化特征，并且平均风速随着离岸距离的增大也逐渐增大。对于离岸距离较近的区域（100 km以内），海面风基本符合双参数的Weibull分布，但对于100 km以外的海面风速概率分布与Weibull分布存在明显差异，随着离岸距离的增大，平均风速和风速标准偏差也相应增大。风速平均值与风速标准偏差的比值较小时，Weibull分布的偏斜度基本为正值，当比值较大时偏斜度转为负值。随着离岸距离的增大，出现与Weibull分布不一致的情况越来越多，且与对应的Weibull分布相比，其偏斜度越小，风速概率分布越不能用Weibull分布进行较好拟合。 相似文献
8.
基于Copula函数的联合概率法在海洋工程中的应用 总被引：1，自引：0，他引：1
本文介绍了Copula函数的定义、属性和几种特殊的Copula函数.将Copula函数应用到近海工程中,用其建立了最大有效波高和最大风速的联合分布函数并检验,结果表明:Copula函数能够比较好的模拟实际的联合概率分布。通过Copula方法,可以由边缘分布和一个连接它们的Copula函数来得出联合分布函数,发挥其描述相关性尤其是尾部相关性的优势。该方法在近海工程的工程可靠度、设计标准和失效概率的计算中具有广泛的应用前景。 相似文献
9.
根据埕岛油田海冰厚度1947-1996年动态热力计算数据,推算冰厚的设计参数.利用Gumbel分布、Weibull分布、对数正态分布、皮尔逊Ⅲ型分布和最大熵分布分别拟合原始数据,寻找拟合最优的分布型式作为海冰厚度长期数据的分布,并根据所得分布估计冰厚的设计参数.在N年一遇重现期下,可推求对应的重现值;并利用极大似然法(MLM)求得该重现值的区间估计. 相似文献
10.
使用美国北卡罗来纳州的 FRF 1985—2016 年的极值波高及其持续时间数据，采用最优的 Gumbel-Hougaard copula函数和 Kendall 分布函数构建极值波高和相应历时不同组合的联合概率分布模式，分析各个组合的遭遇概率、“或”重现期、“且”重现期和 Kendall 重现期，以出现最大可能概率的方法推算各组合联合设计值。结果表明：Kendall 重现期所对应的累积频率更准确地代表了特定设计频率下的风险率；重现期分别为 5 年、10 年、20 年、50 年、100 年、200 年推算的 Kendall重现期设计值介于“或”重现期和“且”重现期设计值之间，小于相应的边缘分布设计值；基于 Kendall 重现期的极值波高及其持续时间不同重现期组合推算的结果可为海洋工程构筑物设计与风险管理提供新的选择与参考。 相似文献
11.
Distribution of wave heights and surface elevations of wind-driven waves are studied.Recordsof surface elevations obtained from both field observations and laboratory measurements are analyzed.Wave heights can be approximated by normal,two-parameter Weibull,and/or Rayleigh distribution.However,while the first two models may have almost equal probabilities to fit measured data quite satis-factorily,the Rayleigh distribution does not appear to be a good model for the majority of the cases stu-died.Surface elevations from field data are well described by the Gaussian model,but as with increasingwind speeds,water surface in a wind-wave flume deviates from normality,and the Edgeworth's form ofthe type A Gram-Charlier series is then applied. 相似文献
12.
Based on the Vine copula theory, a trivariate statistical model of significant wave height, characterized wave period and mean wave direction was constructed. To maintain the properties of the different types of variables, a special copula function was derived from the model developed by Johnson and Wehrly based on the maximum entropy principle. It was then combined with the Archimedean copulas to construct the proposed model. An effective algorithm for generating corresponding joint pseudo-random numbers was also developed. Statistical analysis of hindcast data for the significant wave height, mean wave period, and direction, which were collected from an observation point in the North Atlantic every three hours from 1997 to 2001, was performed. The marginal distributions of the significant wave height and mean wave period were fitted by a modified maximum entropy distribution, and the mean wave direction was fitted by a mixture of von Mises distributions. It was shown that the proposed model is a good fit for the data. The seasonal wave energy resources in the target area were assessed using the model estimates. Histograms of the directional wave energy, wave energy roses, and scatter and energy diagrams were presented. 相似文献
13.
《Applied Ocean Research》2004,26(3-4):114-136
Two successive wave heights are modeled by a Gaussian copula, which is referred to as the Nataf model. Results with two initial distributions for the transformation are presented, the Næss model [Næss A. On the distribution of crest to trough wave heights. Ocean Engineering (1985);12(3):221–34] and a two-parameter Weibull distribution, where the latter is in best agreement with data. The results are compared with existing models. The Nataf model has also been used for modeling three successive wave heights.Results show that the Nataf transformation of three successive wave heights can be approximated by a first order autoregressive model. This means that the distribution of the wave height given the previous wave height is independent of the wave heights prior to the previous wave height. Thus, the joint distribution of three successive wave heights can be obtained by combining conditional bivariate distributions. The simulation of successive wave heights can be done directly without simulating the time series of the complete surface elevation.Successive wave periods with corresponding wave heights exceeding a certain threshold have also been studied. Results show that the distribution for successive wave periods when the corresponding wave heights exceed the root-mean-square value of the wave heights, can be approximated by a multivariate Gaussian distribution.The theoretical distributions are compared with observed wave data obtained from field measurements in the central North Sea and in the Japan Sea, with laboratory data and numerical simulations. 相似文献
14.
广东阳西近岸海域波浪的分布特征 总被引：2，自引：0，他引：2
通过对广东阳西近岸测站1a实测波浪资料及岸边同期风资料的整理与分析,探讨了该海域的波浪特性,得出研究海域不分方向H1/10年平均值为1.00 m,常浪向为SE向,出现的频率为38.35%,强浪向为SE向,观测期间的最大波高出现在0814号"黑格比"台风期间,Hmax值为8.31 m.用已有的理论分布函数对实测统计数据进行拟合,筛选出研究海域的波高分布、周期分布及波高与周期联合分布的特征,结果表明双参数威布尔理论波高分布、杨正己威布尔周期分布、朗格-赫金斯83模式或者孙孚模式较为适用于本海区的波高分布、周期分布、波高周期联合分布;结合相应的风速风向资料,运用回归分析方法,建立了该地区的波高与风速之间、波高与波周期之间的关系. 相似文献
15.
Akira Masuda Tadao Kusaba Kenji Marubayashi Michiyoshi Ishibashi 《Journal of Oceanography》1999,55(2):289-305
The variability of the sea surface wind and wind waves in the coastal area of the Eastern Tsushima Strait was investigated
based on the hourly data from 1990 to 1997 obtained at a station 2 km off Tsuyazaki, Fukuoka. The annual mean wind speed was
4.84 m s−1, with strong northwesterly monsoon in winter and weak southwesterly wind in summer. Significant wave heights and wave periods
showed similar sinusoidal seasonal cycles around their annual means of 0.608 m and 4.77 s, respectively. The seasonal variability
relative to the annual mean is maximum for wave heights, medium for wind speeds, and minimum for wave periods. Significant
wave heights off Tsuyazaki turned out to be bounded by a criterion, which is proportional to the square of the significant
wave period corresponding to a constant steepness, irrespective of the season or the wind speed. For terms shorter than a
month, the significant wave height and the wave period were found to have the same spectral form as the inshore wind velocity:
white for frequencies less than 0.2 day−1 and proportional to the frequency to the −5/3 power for higher frequencies, where the latter corresponds to the inertial
subrange of turbulence. The spectral levels of wave heights and wave periods in that inertial range were also correlated with those of the inshore wind velocity, though the scatter was large.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
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