On the Application of Maximum Entropy Method to Wave Directional Spectrum Analysis

• Main Authors: Chien, Hwa, 錢樺
• Other Authors: C. C. Kao, Laurence, Z. H. Chuang
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/99543857121138041671

碩士 === 國立成功大學 === 水利及海洋工程學系 === 84 === Based on the theory developed by Hashimoto(1994) about the application of Maximum Entropy Method on Directional Wave Spectra Estimation, a new optimization strategy ARS(Adaptive Random Search) is chosen to simplify the complicated procedures and to avoid the divergence in the iteration computation. The validity and reliability of the method are examined through numerical simulation. The influence of the errors originated from the data acquisition and the computation procedures is discussed. Estimating the Directional Wave Spectra with insufficient field wave data could be regarded as an ill-posed problem. Maximum Entropy Principle,which was proved by Statistics and Information theory to be an effective solution to ill-posed problems, could be used to derive the probable expression of directional spreading function. Furthermore, the global optimization strategy ARS method is applied to estimate the parameters of the spreading function. Two multi-variable functions are chosen to examine the efficiency and the effectiveness of the ARS strategy. An AIC criterion is applied to determine the moderate order of the directional spreading function. This modified approach has been proved to have the ability to describe asymmetric and bimodal Directional spreading by the numerical simulation. It is suggested that the operation parameters of ARS f1 and f2, could be set to 4 and 10 in order to save the computation time with acceptable tolerance.