Non-conventional modeling of extreme significant wave height through random sets
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摘要: 在结构设计当中,为了确保结构能到达安全运行的设计寿命,对环境危害的考虑是非常重要的。这在海洋工程领域尤为明显。在海事结构中,可靠的设计往往高度依赖于环境参数。这些参数会影响到设计当中的超越概率以及长期运行的可靠性。因此,一个可靠的环境参数将成为可靠性分析至关重要的一个条件。但是,在通常情况下收集到的海洋数据是相当有限的,并且伴有随时间环境变化的显然特性。因此,我们会提出了一个问题,目前的随机模型是否真正反映出这些实际环境影响的因素到足够的程度,以及如何实现其在具体结构分析中具体体现。在本文中,我们将以一个案例研究一个特定的海洋结构的可靠度对于环境影响的变化。利用泊松-GPD模型来模拟极端环境下的海洋参数变化。一个新型的基于对泊松-GPD模型稳定性考虑的的随机集合模型将被进行研究。在考虑这两个环境因素的同时和风暴的发生率,从而达到对一个实际海洋结构海洋参数的可靠性分析。最后,我们将讨论在此种模型下对于结构利用的可行性影响。Abstract: The analysis and design of offshore structures necessitates the consideration of wave loads. Realistic modeling of wave loads is particularly important to ensure reliable performance of these structures. Among the available methods for the modeling of the extreme significant wave height on a statistical basis, the peak over threshold method has attracted most attention. This method employs Poisson process to characterize time-varying properties in the parameters of an extreme value distribution. In this paper, the peak over threshold method is reviewed and extended to account for subjectivity in the modeling. The freedom in selecting the threshold and the time span to separate extremes from the original time series data is incorporated as imprecision in the model. This leads to an extension from random variables to random sets in the probabilistic model for the extreme significant wave height. The extended model is also applied to different periods of the sampled data to evaluate the significance of the climatic conditions on the uncertainties of the parameters.
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Key words:
- offshore engineering
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