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1

Usefulness of the matching pursuit method in phonocardiographic signal analysis

Damps Natalia, Kłaczyński Maciej

Vibrations in Physical Systems

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2021

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Vol. 32, nr 1

art. no. 2021102

EN

This paper presents a phonocardiographic signal analysis with special emphasis on the Matching Pursuit method. To the knowledge of the authors, this method has not been used before to analyze PCG (phonocardiogram) signals. For this reason, its usefulness for this signal type was tested and a dictionary of Gabor atoms was created. Based on these findings, PCG signal analysis was performed as a Wigner-Ville distribution and compared with a spectrogram. Observing the obtained graphs, it was found that the Wigner-Ville map gives more detailed information about the frequencies which make up the given signal and the time of their occurrence. This method can be used to detect anomalies and pathologies of the heart.

2

Enhancing the resolution of time–frequency spectrum using directional multichannel matching pursuit

Xu Lu, Yin Xingyao, Li Kun

Acta Geophysica

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2020

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Vol. 68, no. 6

1643--1652

EN

Matching pursuit is able to decompose signals adaptively into a series of wavelets and has been widely applied in signal processing of the geophysical felds. Single-channel matching pursuit could not take into account the lateral continuity of seismic traces, and the recent multichannel matching pursuit exploits the lateral coherence as a constraint, which helps to improve the stability of decomposition results. However, atoms searched by multichannel matching pursuit currently are just shared by lateral seismic traces at the same time slicers. The lack of directionality in multichannel search strategies leads to irrationality in dealing with large dip angle seismic traces. Considering that the waveforms of refection events are relatively continuous and similar, an improved multichannel matching pursuit is proposed to realize the directional decomposition of adjacent signals. Based on the principle of seismic refection events tracking and identifcation, directional multichan nel decomposition of seismic traces is realized. The seismic channel to be decomposed is correlated with the time shift of the optimal atom determined by the previous seismic channel. The time position of the maximum correlation indicates the center time of the optimal atom. Optimal atoms identifed by one iteration of multichannel decomposition have the same frequency and phase parameters, diferent center time and amplitude parameters. The center time of the optimal atoms is consistent with seismic refection events. Tests illustrate that the algorithm can successfully reconstruct 2D seismic data without reducing accuracy. Besides, the application of feld data is of great signifcance for reservoir exploration and hydro-carbon interpretation.

3

Normalization effects in matching pursuit algorithm with gabor dictionaries

Różański P. T.

Journal of Applied Computer Science

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2018

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Vol. 26, nr 2

187--199

EN

The matching pursuit (MP) algorithm is a greedy method for signal decomposition used in video coding, data compression, and, particularly, analysis of EEG signals in various paradigms, including P300 and ER(D)S (motor imagery). An important issue for MP implementation is a correct treatment of normalization of atoms (functions) used in computations. Failing to account for normalization-related effects may affect both the numerical stability and the reliability of the algorithm. This paper describes these normalization effects, evaluates their impact on the algorithm’s performance, and describe the proper approach together with a ready-to-use implementation, available under a General Public Licence (GPL). Several performance optimizations used as a part of this implementation are also described.