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A time-frequency application with the Stokes-Woodward technique ArchiMer
Elfouhaily, Tanos; Guignard, S; Branger, H; Thompson, D; Chapron, Bertrand; Vandemark, D.
In a recent paper, we have generalized Woodward's theorem and applied it to the case of random signals jointly modulated in amplitude and frequency. This generalization yields a new spectral technique to estimate the amount of energy due to mode coupling without calling for higher order statistics. Two power spectra are detected; the first is related to the independent modes, and the second contains extra energy caused by mode coupling. This detection is now extended from frequency to time-frequency domain. A comparison between a wavelet transform and our time-frequency technique shows good agreement along with new insight into the time occurrence of the nonlinearities or mode coupling. An application to water surface waves is given in this letter as an...
Tipo: Text Palavras-chave: Wind waves; Wave wave interaction; Vertical asymmetry; Time frequency distributions; Nonlinear hydrodynamic processes; Mode coupling; Instantaneous frequency; Instantaneous amplitude; Horizontal asymmetry; AM FM; Amplitude modulation frequency modulation.
Ano: 2003 URL: https://archimer.ifremer.fr/doc/2003/publication-744.pdf
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Analysis of random nonlinear water waves: the Stokes-Woodward technique ArchiMer
Elfouhaily, Tanos; Joelson, Maminirina; Guignard, Stéphan; Branger, Hubert; Thompson, Donald; Chapron, Bertrand; Vandemark, Douglas.
A generalization of the Woodward's theorem is applied to the case of random signals jointly modulated in amplitude and frequency. This yields the signal spectrum and a rather robust estimate of the bispectrum. Furthermore, higher order statistics that quantify the amount of energy in the signal due to nonlinearities, e.g., wave-wave interaction in the case of water waves, can be inferred. Considering laboratory wind generated water waves, comparisons between the presented generalization and more standard techniques allow to extract the spectral energy due to nonlinear wave-wave interactions. It is shown that our analysis extends the domain of standard spectral estimation techniques from narrow-band to broad-band processes.
Tipo: Text Palavras-chave: Frequency modulation; Amplitude modulation; Bispectrum; Vertical asymmetry; Horizontal asymmetry; Wave wave interaction; Mode coupling; Fluid mechanics; Modulation de fréquence; Modulation d'amplitude; Bispectre; Dissymétrie horisontale; Dissymétrie verticale; Interaction vague vague; Couplage de mode; Mécaniques des fluides.
Ano: 2003 URL: https://archimer.ifremer.fr/doc/2003/publication-741.pdf
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