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A novel tool for Non Destructive Testing using frequency analysis of IR image sequences

Więcek P., Strąkowska M.

Measurement Automation Monitoring

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2015

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Vol. 61, No. 6

219--222

EN

In this paper, a novel methodology and a software tool for advanced image processing of thermal image sequences are presented. The software implements 1-D Fourier, short-time Fourier and wavelet transforms. The tool uses temperature variation in time for each pixel in the sequence of IR images. It is dedicated to Non Destructive Testing (NDT) testing and the functional time-dependent thermal imaging, e.g. for screening in medical diagnosis. The overall methodology is based on 2-stage analysis. The first, preliminary one is to estimate the right scale/frequency and the moment in time for the final frequency analysis. It can simplify characterization of materials and detection of cracks and defects.

2

Induction motor signatures analysis under influence of mechanical and electrical fault

Gomez A. F., Sułowicz M., Sobczyk T. J.

Maszyny Elektryczne : zeszyty problemowe

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2014

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Nr 4(104)

293--299

EN

The study of the potential impact under the typically measured signals in electrical machines due to faults is a crucial step for the development of effective systems for fault detection. The relationship between the electrical and mechanical components has been extensively studied in the past, but despite the progres made, the introduction of new control systems or the nonlinearities presented in the electrical machine, still makes hard the diagnosis of faults. The present study attempts to show the evolution of the induction motor signatures when electrical and mechanical faults occurs simultaneously. The analysis of the stator phase currents may lead to an accurate diagnosis of the fault due to the fact that the non-linearity interactions between the electrical and mechanical components are difficult to predict with precision. Fourier analysis has been chosen. Results shown in the present paper indicate that the consequences of the above mentioned faults in the typical analysis carried out to diagnoses the state of the electrical machine, may be interpreted as indicator of a different type of fault.

3

Aproksymacja konturów z wykorzystaniem metod transformacyjnych

Stąpor M.

Elektronika : konstrukcje, technologie, zastosowania

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2003

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Vol. 44, nr 5-6

27-28

PL

W artykule przedstawiono transformacyjne metody aproksymacji konturów. Zastosowano przekształcenia Fouriera, Walsha, oraz falkowe Daubechies. Wykorzystano opis konturu w układzie współrzędnych kartezjańskich. Dla konturów testowych obliczono współczynniki widmowe powyższych transformat. W celu kompresji posłużono się kryterium progowym, a następnie obliczono transformatę odwrotną. Dla porównania poszczególnych rodzajów aproksymacji przedstawiono kształty aproksymowanych konturów testowych. Zamieszczono także wykresy błędu średniokwadratowego (MSE) w funkcji stopnia kompresji.

EN

In this paper transform methods of contour approximation are presented. Fourier, Walsh and wavelet Daubechies transforms have been used. Contours have been represented by two one-dimensional vectors in cartesian co-ordinates. The spectrum coefficients of tested contours have been calculated by applying the different transforms. To compress contour data, the threshold criterion has been applied. In the next step the inverse transform has been calculated. Shapes of approximated test contours are included. Plots of the mean square error (MSE) versus compression ratio are included for comparision of approximation efficiency.