| 摘要: |
| 通过对国内外常用的4种极值波高分布模式的拟合与比较，得到了以下结论：（1）由于地区差异，港口工程技术规范给出的单一模式并非具有普遍性。对同一工程应该采用多种理论分布进行计算比较，从中选择最佳模式。（2）应用麦奎尔特法拟合Weibull分布实现了对未知多数的一举寻优，解的收敛速度快，结果稳定且精度高。同时对其它几种分布实现了资料的微机化处理。（3）本文算例用4种极值分布对不同重现值波高进行了比较，所得到的小概率波高各不相同：Gumbel分布得到的重现值最大；Log-normal和P-III型分布得到的值次之；Weibull分布得到的值最小。 |
| 关键词: 极值分布拟合 麦奎尔特法 重现值 |
| DOI： |
| 分类号: |
| 基金项目:国家科委九五攻关项目，96－922－03－03号 |
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| STATISTICAL DISTRIBUTIONS OF LONG-TERM EXTREME WAVE HEIGHT |
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WANG Yun-hong,DONG Sheng
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1.Tianjin Water Conservancy Bureau,Tianjin,300074;2.Collage of Engineering, Ocean University of Qingdao, Qihgdao, 266003
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| Abstract: |
| Calculation of the predicted wave height against various return periods plays an important role in planning, design of coastal construction and ocean engineering. The determination of the design values will greatly influence the level of protection standard and the scale of investment. Comparison of several extreme distribution models used in China and abroad shows that because of the difference of the areas there is no popular trend to use only one distribution as a recommended model. The optimum model for every engineering design can be obtained only when much more distributions are fitted and compared. So far, 3-parameter Weibull distribution is widely used. The initially unknown values of the parameters are determined by probability paper or linear least square curve fitting at present, the former method is simple but the results may not be the same. The latter method requires estimation of an initial location parameter. The speed of solution depends to a large extent on the interval between original value and actual value of location parameter. In this paper a new approach is proposed based on the Marquardt method. Three unknown parameters can be calculated simultaneously. The speed of the iterative loop is high and the accuracy is good. Fitting was carried out by computer. Example shows that different distributions gave very different estimation of long return period wave heights. The value provided by Gumbel distribution is largest, those obtained by Log-normal and P-III distributions are less, and that by Weibull distribution is smallest. |
| Key words: Extreme distribution fitting, Marquardt method, return period |
