共查询到18条相似文献，搜索用时 93 毫秒
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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
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以青岛地区近30年历年日最大降水量(R_Y)与其在该年中的出现日期(L_Y),以及各月的日最大降水量(R_M)与其在该月中的出现日期(L_M)的13个样本序列为例,基于4种二维Copula函数(Clayton Copula、Frank Copula、Gumbel-Hougaard Copula和Gaussian Copula)建立二维联合分布模型;通过假设检验和拟合优度评价,选取拟合较优的二维Frank Copula函数所构建的日最大降水量及其出现日期的联合分布模型,对(R_Y,L_Y)和各月(R_M,L_M)进行了详细分析。通过历年各月日最大降水量及其出现日期的联合统计分析,在一定联合重现期时,当日最大降水量给定某一重现值时,可以估计该值在一年中(或某个月份中)最可能的出现日期,为合理港口装卸作业给建设意见。 相似文献
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将涠洲岛海洋站1961～1989年极值波高与风速的长期观测资料作为统计样本，基于二维皮尔逊Ⅲ型联合分布，估计了年极值有效波高与风速的联合出现概率。以导管架平台基底剪力计算为例，给出了相应的荷载设计组合，与单因素频率分析法相比，联合概率分布法所得百年一遇剪力值约降低18％，条件分布法所得百年一遇剪力值约降低12％。结果表明，考虑环境条件之间的相关性，可以合理降低荷载设计标准，从而减小海洋工程投资费用。 相似文献
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《中国海洋大学学报(自然科学版)》2015,(7)
防波堤一旦破坏,会严重影响港口的正常使用功能,准确计算防波堤的可靠度指标对港口工程意义重大。防波堤所受主要荷载为水平波浪力及波浪浮托力,计算可靠度应考虑两者的相关性。结合Gumbel-Houggard Copula函数与对数正态边缘分布构造二维的Copula分布可以很好地描述荷载间的相关性。本文以秦皇岛直立式防波堤为例,用二维Copula分布计算防波堤的可靠度,并与JC独立法、JC相关法进行了比较,结果显示:用Copula分布计算的结构可靠度指标远小于JC独立法计算结果,与JC相关法接近。 相似文献
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极值样本的选取和分布模型的确定是设计波高推算中的两个关键环节。使用阈值法选取波高过阈样本作为极值样本时,常用标准风暴长度法对超出量序列进行“去聚类”处理,以使样本符合独立性标准。然而标准风暴长度法中的标准风暴长度需要人为选择,增加了取样结果的不确定性。本文提出了一种自动的标准风暴长度估计方法,并基于该方法选取了粤西海域的波高过阈样本。波高过阈样本具有尖峰、厚尾的统计特征,为了更准确地拟合该样本,本文基于组合模型原理构建了一种新的分布模型——Gumbel-Pareto分布模型,并用该模型进行了粤西海域的设计波高推算,结果表明Gumbel-Pareto分布对波高过阈样本的拟合优度比Gumbel分布和广义Pareto分布更高,可以为大型海洋工程设计波高的确定提供参考。 相似文献
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简要论述了Copula理论与几种常用的二维Archimedean Copula函数的性质和适用性。以粤东汕头海域妈屿历年最高增水高度与相应风速的遭遇为研究实例,在分别采用3个三参数的概率分布模式:广义极值分布(GEV)、Weibull分布(WBL)和皮尔逊Ⅲ型(P-Ⅲ)分布对两个边缘分布(年最高增水高度与相应风速)拟合优度检验基础上构建了两变量联合概率分布模型。主要结果如下:(1) 年最大增水高度与相应风速的边缘分布分别服从Weibull分布和P-Ⅲ型分布;(2) 拟合优度检验指标表明二者的最优连接函数为Archimedean Copula类的Gumbel-Hougaard Copula;(3) 重现期介于2~200 a之间的边缘分布与同频率的联合分布的重现水平相对差值大约介于6.7%~22.2%之间;(4) 特定风速设计频率条件下,随年最大增水设计频率的减小,二者的遭遇概率也随之迅速减小;反之,特定增水设计频率随风速条件频率的减小,二者的遭遇概率随之明显增大。 相似文献
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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
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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
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为正确考虑和衡量核电厂选址风暴潮灾害分析中热带气旋登陆过程时出现的气压填塞量的取值,利用1949-2014年在我国东南沿海登陆的台风气压资料,建立了登陆前TC中心气压与登陆后气压填塞量二维Copula联合分布函数,通过同现重现期表征出两种样本筛选条件下两种边缘分布的相关关系。结果表明:Frank Copula函数可以适应样本联合分布;考虑在台湾登陆的TC样本与不考虑时相比,相同同现重现期水平在登陆前气压边缘分布方向上要增加10 h Pa左右;气压填塞量在25 h Pa以内时,填塞量越小,同现重现期越大。 相似文献
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The paper provides a bivariate distribution of wave power and wave height, as well as a bivariate distribution of wave power and wave period; both bivariate distributions are for individual waves within a sea state. This is relevant for e.g. making assessments of wave power devices and their potential for converting energy from waves. The results can be applied to compare systematically the wave power potential for individual waves in a given sea state at different locations. 相似文献
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Statistical analysis of the extreme values of the Baltic Sea level has been performed for a series of observations for 15–125 years at 13 tide gauge stations. It is shown that the empirical relation between value of extreme sea level rises or ebbs (caused by storm events) and its return period in the Baltic Sea can be well approximated by the Gumbel probability distribution. The maximum values of extreme floods/ebbs of the 100-year recurrence were observed in the Gulf of Finland and the Gulf of Riga. The two longest data series, observed in Stockholm and Vyborg over 125 years, have shown a significant deviation from the Gumbel distribution for the rarest events. Statistical analysis of the hourly sea level data series reveals some asymmetry in the variability of the Baltic Sea level. The probability of rises proved higher than that of ebbs. As for the magnitude of the 100-year recurrence surge, it considerably exceeded the magnitude of ebbs almost everywhere. This asymmetry effect can be attributed to the influence of low atmospheric pressure during storms. A statistical study of extreme values has also been applied to sea level series for Narva over the period of 1994–2000, which were simulated by the ROMS numerical model. Comparisons of the “simulated” and “observed” extreme sea level distributions show that the model reproduces quite satisfactorily extreme floods of “moderate” magnitude; however, it underestimates sea level changes for the most powerful storm surges. 相似文献
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本文基于第3代海浪模式WAVEWATCH Ⅲ (WW3）模拟的1996–2015年海浪后报数据,分析了南海北部有效波高及其极值的时空变化特征,并采用Pearson-Ⅲ和Gumbel两种极值分布方法对该区极值波高重现期进行了估算。结果表明,南海北部有效波高的季节变化和空间分布与季风风场基本一致,呈现秋冬高春夏低,并自吕宋海峡西侧向西南降低的特征,与ERA5再分析数据结果高度相似。有效波高极值（简称极值波高）的时空分布特征受时间分辨率强烈影响,采用极值数据的分辨率越高（如逐小时）,所展现的台风型波浪特征越显著。扣除季节变化信号后的有效波高和年极值波高均体现出较强的线性增高趋势,近20年升高的比例分别为7.7%和31.6%,值得警惕和关注。该区多年一遇极值波高存在若干个大值区,且与台风的路径、强度有直接联系,表明台风是引发该区域极端大浪的最主要机制。对比Pearson-Ⅲ和Gumbel极值分布估算结果发现：若极值波高较低,频率随极值波高升高缓慢降低,此时两种极值分布的估算都比较准确,差异极小,可忽略不计;但当研究时间范围内,某年极值波高远超其他年份时,Pearson-Ⅲ极值分布估算结果明显高... 相似文献
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In this study, a 91-year data set at the Wusong Station near Shanghai City in Yangtze Estuary has been used to estimate the 100-year Annual Maximum Water Level (AMWL). The performances of four common distribution models have been evaluated. The GEV model provides the best estimates of an AMWL. It results in the minimum difference (0.04 m) compared to the observed 92-year AMWL, with the high correlation coefficient (0.99) and minimum root-mean-square-error (0.045 m) value. Predictions from other distribution models cause non-negligible deviations, underestimating the 92-year AMWL by 0.57, 0.38, and 0.15 m for Weibell, Lognormal, and Gumbel distribution models, respectively. In order to examine the effects of a shorter data set, a 59-year data set was investigated. Model predictions using 59-year data set underestimates the observed 60-year AMWLs. By comparing to the 100-year AMWL estimated by the GEV distribution, using the 91-year data set, results using the shorter 59-year data set lead to underestimates of the 100-year AMWL by 0.78 m for Weibull, 0.58 m for Lognormal, 0.38 m for Gumbel, and 0.39 m for GEV distributions. Therefore, one should be cautious when estimating the 100-year AMWL if the data set covers a period much shorter than 100 years. Selecting an appropriate distribution model can improve prediction accuracy. 相似文献
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Marine environmental design parameter extrapolation has important applications in marine engineering and coastal disaster prevention.The distribution models used for environmental design parameter usually pass the hypothesis tests in statistical analysis,but the calculation results of different distribution models often vary largely.In this paper,based on the information entropy,the overall uncertainty test criteria were studied for commonly used distributions including Gumbel,Weibull,and Pearson-III distribution.An improved method for parameter estimation of the maximum entropy distribution model is proposed on the basis of moment estimation.The study in this paper shows that the number of sample data and the degree of dispersion are proportional to the information entropy,and the overall uncertainty of the maximum entropy distribution model is minimal compared with other models. 相似文献
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根据1965—2009年间影响北海市沿岸的热带气旋资料和风暴增水资料,进行统计分析北海市沿岸的风暴潮特征。结果表明:北海市沿岸平均每年发生风暴增水2—3次,其中较大以上强度的风暴增水每年0.87次,严重以上强度的风暴增水每3年有一次;北海市沿岸每年4—11月均有可能发生风暴增水,且集中在7—10月,尤以9月最多。影响北海市沿岸的热带气旋主要以西北行路径为主,且多是穿过雷州半岛或海南岛后在越南沿海登陆,此种情况下,风暴增水曲线表现为周期性波动。另外,本文还采用Pearson-Ⅲ分布和Gumbel分布来估算风暴增水频度,得出北海市沿岸不同重现期的高潮位值。 相似文献
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In this study, we considered the problem of estimating long-term predictions of design wave height based on the observation data collected over 10–15 years along the eastern-coast of the Korean peninsula. We adopted a method that combines Bayesian method and extreme value theory. The conventional frequency analysis methods must be reconsidered in two ways. First, the conventional probability distributions used in the frequency analysis should be evaluated to determine whether they can accurately model the variation in extreme values. Second, the uncertainty in the frequency analysis should also be quantified. Therefore, we performed a comparative study of the Gumbel distribution and GEV distribution to show the higher efficiency of the latter. Further, we compared the Bayesian MCMC (Markov Chain Monte Carlo) scheme and the MLE (Maximum Likelihood Estimation) with asymptotic normal approximation for parameter estimation to confirm the advantage of the Bayesian MCMC with respect to uncertainty analysis. 相似文献