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Non-stationary Analysis Applied to Tribocorrosion Signals; Análise não Estacionária Aplicada a Sinais de Tribocorrosão

Marco André A. Kappel; Universidade do Estado do Rio de Janeiro; Danillo Pedro Silva; Universidade do Estado do Rio de Janeiro; José María Sánchez-Amaya; Universidad de Cádiz; Roberto P. Domingos; Universidade do Estado do Rio de Janeiro; Ivan Napole
Fonte: Revista Virtual de Química Publicador: Revista Virtual de Química
Tipo: ; Formato: binary/octet-stream
Publicado em 18/09/2015 PT
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Significant part of electrochemical and mechanical tribocorrosion signals can be non-stationary. These signals include electrochemical potential and current, and friction force. Thus, in this case, traditional analysis techniques in the frequency domain, such as the Fourier transform technique, are not suitable for the efficient signal interpretation. Techniques such as the Short-Time Fourier Transform (STFT) are typically applied in time-frequency domain to make a detailed signal analysis. However, since the method is based on choosing a fixed length window, it is not possible to simultaneously obtain the highest resolution in both time and frequency. The current paper adopted a technique to find a dynamically variable size for the window in order to efficiently analyze non-stationary signals. This procedure was applied to tribocorrosion signals of commercially pure titanium rubbed against an alumina sphere of 4.0 mm in 0.9% m/v NaCl medium. The method directly analyzes the signal in the time domain by computing the kurtosis of small centered intervals of the signal. In practice, kurtosis can detect abrupt changes in data distribution by adapting the time-frequency resolution when it is necessary. The variable STFT results are adequate for the investigation of tribocorrosion friction force and electrochemical potential/current because they present a plot in time-frequency domain without the need of a preconditioning stage...