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Metody ilościowej analizy szumu napięciowego Barkhausena

Fryczowski K., Roskosz M.

Przegląd Spawalnictwa

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2016

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R. 88, nr 10

133--138

PL

Przeprowadzone badania doświadczalne z wykorzystaniem magnetycznego szumu Barkhausena (MBN) wykazały jego silne powiązanie z mikrostrukturą i stanem naprężenia w materiałach o właściwościach ferromagnetycznych. Materiały te są szeroko stosowanych w przemyśle, co jest argumentem uzasadniającym prowadzenie prac badawczo-rozwojowych związanych z tym zjawiskiem. W artykule uwaga skupia się na metodach analizy ilościowej MBN, czyli sposobach otrzymywania informacji diagnostycznej. Wymienione i opisane zostały zarówno popularne metody punktowe jak i te wykorzystujące właściwości czasowo-częstotliwosciowe sygnałów niestacjonarnych.

EN

The results of experimental studies of application of magnetic Barkhausen noise (MBN) showed his strong relationship with the microstructure and stress state of the ferromagnetic material. These materials are widely used in the industry, what is the argument to conduct more detailed research assosiated with this phenomenon. In paper attention is paid to quantitative MBN analysis method, that means the way for obtaining diagnostic information. Popular scalar method and as well joint time-frequency method was mentioned and described.

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Time-Frequency Characteristics of Chemical Oscillations. Experimental and Model Studies

Darowicki K., Felisiak W.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 9

1269-1278

EN

Chemical oscillations exhibit nonlinear, and nonstationary features and their complete characterization cannot be accomplished via classical Fourier transform. That is why there is a need for another analysis framework in joint time-frequency domain. In this paper the authors propose a proper methodology of spectral analysis of Belousov-Zhabotinsky (BZ) reaction. The short time Fourier transformation (STFT) has been applied to the analysis of potential registers of BZ reaction in a batch reactor. The method allowed finding the frequency and energy distribution of chemical oscillations in the function of time. The similarities and the differences between the spectrograms generated for the experimental data and simulated time series, based on the modified Oregonator model, are briefly discussed.

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Reduction of Cross Terms in Wigner-Ville Distribution of Transiently Evoked Otoacoustic Emission

Grzanka A., Hatzopoulos S., Śliwa L., Muliński W.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2001

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vol. 49, nr 3

493-503

EN

The objective of the paper is to present a new method of time-frequency representation, applicable on signals of short duration, based on regional smoothing of Wigner-Ville distribution (WYD). The proposed algorithm reduces the amplitude of the cross-terms and preserves high resolution of the WYD, because the smoothing routine is applied only in the regions where cross-terms appear. The criterion for cross-terms localisation is the negativity of energy in the time-frequency plane. The method is energy balanced and does not affect the positive values of the spectrogram. The method has been specially fitted for Transiently Evoked Otoacoustic Emission (TEOAE) signals, whose spectral properties are still under investigation. The presented results show (i) that the TEOAE signals are very complex and (ii) that the application of the proposed method of analysis may decompose the TEOAE signals into components which may contribute more to our understanding of the TEOAE underlying cochlear mechanies.