Application of Wavelet Transform to Problems in Ocean Engineering

Abstract

This study presents the results of series of studies, which are mainly devoted to the application of wavelet transforms to various problems in ocean engineering. Both continuous and discrete wavelet transforms were used. These studies attempted to solve detection of wave directionality, detection of wave profile, and decoupling of the rolling component from free roll decay tests. The results of these analysis, using wavelet transform,demonstrated that the wavelet transform can be a useful tool in analyzing many problems in the filed of ocean engineering.1. IntroductionThe wavelet transform is a powerful tool for solving a variety of physical problems. The advantage of wavelet transform, over traditional Fourier transform, lies in the fact that it provides information about time evolution, as well as frequency content of the signals, while the Fourier transform yields only frequency information. The Fourier transform is a well-known frequency domain approach (Newland, 1993), which has been used, extensively, for frequency domain analysis, but it is not an appropriate tool for analyzing transient signals.We discuss the concept of wavelet transform. Then the properties of Morlet and Mexican hat wavelet are described. To detect directionality, directional wavelet is adopted. The three examples of applications illustrated in this paper include detection of wave directionality by Morlet wavelet, detection of wave profile by Mexican wavelet, and decoupling of rolling component from free roll decay test data by discrete wavelet transform. The results of these analysis show that the wavelet transform has a potential to be utilized in signal analysis in fields of ocean engineering.