Nonstationary Wave Spectra Analysis
Mihail Petrakos and Roger Green (PhD students)
Nonstationary, nonlinear, time-space variation of directional wave statistics in wave tank and field statistics. Educational component on the Analysis of Ocean Wave Data.
The 8-day short course on ocean wave analysis methods (1994, 1995) helps transfer knowledge to students and industry. The nonstationary, non-linear wave studies impact wave-current modeling capability, model basin behavior, environmental forcing models, and others. During the 1996-1997 academic year, this material is being summarized for a book to be published by World Scientific Press.1993-Study methods available for nonstationary spectra, complex demodulation, wavlet analysis, and spline representation of FFT coefficient (evolutionary Fourier analysis). Selected the last as most appropriate to lead to directional spectra. Develop evolutionary FFT analysis in time. Validate with experimental data and extend the methods to space variation and directional polyspectra estimation. Continue to improve present 8-day short course on wave analysis methods. Summarize material for book "Analysis of Ocean Wave and Other Environmental Data." Authors: Borgman, Niedzwecki, Scheffner, Kern, and Petrakos
Wavelet theory work in general. Signal processing methods for nonstationary input.
The development here are aimed directly at the estimation of space-time variation of directional wave spectra and polyspectra. Most other studies are concerned only with time series in other (non-offshore) applications.
October 1994 to September 1997
An 8-day short course on wave analysis specifically for OTRC and Industry sponsors. Report on software for Dean Stream Function solution of nonlinear, undirectional waves of permanent form (prepared for 1995 short course). Analysis of Texas A&M tank data w/evolutionary FFT analysis. Participation in seminar planning on this subject. Scholarly publication and a Ph.D. thesis on theory and use of space-time nonstationary evolutionary FFT analysis by M. Petrakos (1995). Portion of Monogram, 1997;Book 1997; Ph.D. thesis by Roger Green 1997 or 1998.