Wyniki wyszukiwania - BazTech

1

Time reversal seismic source imaging using peak average power ratio (PAPR) parameter

Franczyk A., Leśniak A., Gwiżdż D.

Acta Geophysica

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2017

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Vol. 65, no. 2

299--308

EN

The time reversal method has become a standard technique for the location of seismic sources. It has been used both for acoustic and elastic numerical modelling and for 2D and 3D propagation models. Although there are many studies concerning its application to point sources, little so far has been done to generalise the time reversal method to the study of sequences of seismic events. The need to describe such processes better motivates the analysis presented in this paper. The synthetic time reversal imaging experiments presented in this work were conducted for sources with the same origin time as well as for the sources with a slight delay in origin time. For efficient visualisation of the seismic wave propagation and interference, a new coefficient—peak average power ratio—was introduced. The paper also presents a comparison of visualisation based on the proposed coefficient against a commonly used visualisation based on a maximum value.

2

Identyfikacja sejsmicznych zjawisk podobnych rejestrowanych w kopalniach podziemnych

Leśniak A.

Przegląd Górniczy

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2014

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T. 70, nr 3

34--40

PL

W opisanej pracy przedstawiono metodę służącą do automatycznego grupowania zjawisk sejsmicznych na podstawie sygnałów zarejestrowanych siecią czujników w kopalniach podziemnych. Algorytm wyznaczania klastrów złożonych z sygnałów podobnych bazuje na parametrach obliczanych z uproszczonej obwiedni zarejestrowanego sygnału. W pracy opisano implementację oraz przykładowe wyniki działania algorytmu dla sygnałów zarejestrowanych siecią sejsmiczną w kopalni miedzi „Rudna". Zauważono, że wyniki klasteryzacji są w dużym stopniu zależne od liczby kanałów rejestracyjnych aparatury sejsmicznej używanych do grupowania oraz wielkości progów wykorzystywanych do grupowania. Pogrupowane sygnały pozwalają na wzrost dokładności lokalizacji źródeł emisji i śledzenia wzrostu pojedynczych szczelin prowadzących do wystąpienia silnych wstrząsów.

EN

This paper presents the method of automated clustering of seismic events recorded by use of seismic network in underground mines. The proposed algorithm uses clusters of similar events (so called multiplets). The degree of similarity between signals is established by use of parameters evaluated from the simplified envelopes of the recorded events. The paper presents a detailed description of the algorithm as well as the example of clustering for signals recorded in "Rudna" copper mine. The analysis shows that the results largely depend on the number of channels of recording equipment used for cluster evaluation, as well as thresholds used during the single link algorithm. The evaluated multiplets allow to significantly increase the accuracy of source location of similar events and the rise in of effectiveness of seismic hazard evaluation.

3

A novel method to locate the voltage sag source: a case study in the Brazilian power network (Mato Grosso)

Moradi M. H., Mohammadi Y., Tayyebi M. H.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 3b

112-115

EN

This article presents a novel method to locate the voltage sag source based on directional overcurrent (DOC) relay information. In this method the source of voltage sag is located by using the variation of magnitude of measured current positive-sequence component during sag and presag conditions and the sign of its phase-angle jump. The performance of the proposed method is compared with distance relay (DR) and phase change in sequence current (PCSC) methods by using PSCAD/EMTDC on a simulated case study. The results show the good and unique performance of the novel method in cases where only currents are recorded.

PL

W artykule zaprezentowano nową metodę lokalizacji źródła zapadu napięcia bazującej na informacji o kierunkowym przeciążeniu prądowym. Źródło zapadu napięcia jest lokalizowane na podstawie pomiaru amplitudy i fazy prądu w czasie zapadu i przed zapadem. Porównano metodę z z dotychczas stosowanymi metodami DR i PCSC.

4

Voltage sag source location based on voltage measurements only

Leborgne R. Ch., Karlsson D.

Electrical Power Quality and Utilisation. Journal

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2008

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Vol. 14, iss. 1

25-30

EN

This paper introduces an alternative method for voltage sag source location based on voltage information only. The source is located considering the sag magnitude at the primary and secondary side of a transformer. A comprehensive review of previously proposed methods based on voltage and current measurements is presented. The performance of the proposed method is compared with the previous ones using PSCAD /EM TDC on a model of a regional network including transmission and sub-transmission levels. Moreover, the sag magnitude method is applied on a set of measurements taken from the regional network during a one year sag survey. The results show the good performance of the new method and its unique applicability in cases where only voltages are recorded, such as the sag survey presented.

5

Extraction of information from seismograms by neural networks

Niewiadomski J.

Acta Geophysica Polonica

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2004

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Vol. 52, nr 2

143-153

EN

In this study we concentrate on neural networks in the form of algorithms, and on their property to learn by examples. The possibility of learning by examples in-cludes also an enormous ability of information extraction. As the input data we have used the regional seismograms which record the ground particle velocities. Application of the networks for evaluation of the two seismic parameters has been demonstrated: first to calculate the magnitude (or seismic moment) of the seismic event directly from the velocity seismograms, without prior converting them to the displacement seismograms, and second, to locate seismic source by using only a single seismogram. Both applications are very convenient due to their speed of cal-culation and the lack of spectral methods - in the first case, and the good precision despite the unusual approach in the second case. To prepare the input data for the neural networks a preprocessing has been applied, which can be described as filter-ing of a seismogram by the filters bank.