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Wyświetlanie 1-15 z 194
Tytuł:
Experimental damage assessment of support condition for plate structures using wavelet transform
Autorzy:
Abdulkareem, Muyideen
Bakhary, Norhisham
Vafaei, Mohammadreza
Md Noor, Norhazilan
Abd Samat, Roslida
Powiązania:
https://bibliotekanauki.pl/articles/280431.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
damage
plate
continuous wavelet transform
discrete wavelet transform
Opis:
Wavelet transforms (WTs) have gained popularity due to their ability to identify singularities by decomposing mode shapes of structures. In VBDD, the support condition of a structure influences structural responses and modal properties. In fact, the structural responses and modal properties are a lot more sensitive to changing boundary conditions than to crack and fatigue damage, resulting in inaccurate damage detection results. Therefore, in this study, sensitivity tests to estimate a suitable distance range which allows damage detection by imposing single support damage are carried out. The estimated appropriate distance is then applied to detect damage at multiple supports. This involved the applicability of response acceleration of plate structures to support assessment by applying continuous wavelet transform (CWT) and discrete wavelet transform (DWT). The damage cases have been introduced by releasing bolts at specified fixed supports of the plate to simulate the damage. The response accelerations of the rectangular plate at points close to the supports were measured and decomposed using CWT and DWT to assess the structural integrity of each support. The results showed that an appropriate distance range was necessary for accurate damage detection, and both, CWT and DWT could provide reliable outputs. However, the first- and fourth-level detail coefficients of DWT failed to indicate damage in some cases. A more detailed investigation of the effect of different wavelet scale ranges on damage detection using CWT demonstrated that the accuracy of damage detection increased as the scale decreased.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 2; 501-518
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Wavelet Transform in Regression
Zastosowanie transformacji falkowej do budowy modeli regresyjnych
Autorzy:
Trzęsiok, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/905049.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
wavelets
wavelet transform
wavelet thresholding
nonparametric regression
Opis:
The wavelet transform was introduced in the 19S0's and it was developed as an alternative in tin short time Fourier transform. The wavelets theory is very popular in signal processing and pattern recognition and its applications are still growing. This paper presents the wavelet transform in nonparametric regression. The use of wavelets, in statistical applications was pioneered by D. Donoho and I. Johnstone. Here we discuss their methodology - wavelet shrinkage. The wavelet transform is compared with another nonparametric regression method - splines.
Transformacja falkowa została zaproponowana na początku lat osiemdziesiątych, jako alternatywa do transformacji Fouriera. Metoda ta szybko znalazła swoje zastosowanie w teorii sygnałów oraz w rozpoznawaniu obrazów, a zakres jej aplikacji nadal dynamicznie się rozwija. Autorami pionierskich prac z zakresu zastosowań teorii lalek w statystyce są David Donoho and Iain Johnstone. Zaproponowali oni w roku 1994 procedurę WaveShrink wykorzystywaną do estymacji funkcji gęstości oraz budowy nieparametrycznych modeli regresji oparła na transformacji falkowej. W artykule przedstawione zostało zastosowanie transformacji falkowej oraz procedury WaveShrink do budowy modelu regresyjnego. Omawianą metodę porównano z inną nieparametryczny metodą regresji - krzywymi sklejanymi.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2009, 225
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of deviations of cylindrical surfaces with the use of wavelet transform
Autorzy:
Stępień, K.
Makieła, W.
Powiązania:
https://bibliotekanauki.pl/articles/220818.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wavelet transform
cylindricity profile
decomposition
approximation
Opis:
Wavelet transform becomes a more and more common method of processing 3D signals. It is widely used to analyze data in various branches of science and technology (medicine, seismology, engineering, etc.). In the field of mechanical engineering wavelet transform is usually used to investigate surface micro- and nanotopography. Wavelet transform is commonly regarded as a very good tool to analyze non-stationary signals. However, to analyze periodical signals, most researchers prefer to use well-known methods such as Fourier analysis. In this paper authors make an attempt to prove that wavelet transform can be a useful method to analyze 3D signals that are approximately periodical. As an example of such signal, measurement data of cylindrical workpieces are investigated. The calculations were performed in the MATLAB environment using the Wavelet Toolbox.
Źródło:
Metrology and Measurement Systems; 2013, 20, 1; 139-150
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected aspects in the analysis of the combustion process using wavelet transform
Wybrane aspekty w analizie procesu spalania z wykorzystaniem przekształceń falkowych
Autorzy:
Grądz, Żaklin
Powiązania:
https://bibliotekanauki.pl/articles/1841303.pdf
Data publikacji:
2020
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
scalogram
continuous wavelet transform
discrete wavelet transform
diagnostics
skalogram
przekształcenie Falkowe dyskretne
przekształcenie Falkowe ciągłe
diagnostyka
Opis:
The complexity of changes occurring in the flame during the combustion process has a direct influence on the quantity and qualityof the combustion products. The presented measurement data pertaining to the changes in flame luminosity were recorded using a specialized monitoring system. These signals from the combustion ofsuch fuels as pulverized coal and mazoutwere recorded with high sampling rate. The paper presented the analysis of changes in flame luminosity for different fuels using continuous and discrete wavelet transform. The main aim of the studies was to determine the scale values, which enable differentiating between the type of combusted fuel. The results of studies were presented in the form of scalograms.
Złożoność zmian zachodzących w płomieniu w trakcie procesu spalania różnych paliw ma bezpośredni wpływ na ilość i jakość powstałych produktów spalania. Przedstawione w pracy dane pomiarowe zmian intensywności świecenia płomienia zostały zarejestrowaneprzy użyciu specjalistycznego systemu monitorującego. Sygnały te,dla procesu spalania,zostały zarejestrowane z wysoką częstotliwością próbkowania. W artykule przedstawiono analizę zmian intensywności świecenia płomienia dla różnych paliw przy zastosowaniu ciągłego i dyskretnego przekształcenia falkowego. Podstawowym celem badań było określenie wartości skali, na podstawie których możliwe będzie rozróżnienie rodzaju spalanego paliwa. Wyniki badań zostały zaprezentowane w postaci skalogramów.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2020, 10, 3; 52-55
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implementation of the Wavelet Transform with SSE Extensions
Autorzy:
Łyszkowski, T.
Wiechno, T.
Yatsymirskyy, M.
Powiązania:
https://bibliotekanauki.pl/articles/108711.pdf
Data publikacji:
2013
Wydawca:
Społeczna Akademia Nauk w Łodzi
Tematy:
Orthogonal Filters
discrete wavelet transform
SSE extensions
Opis:
It has been shown that application of assembly implementation of Streaming SIMD Extensions (SSE) shortens the time needed to apply filtration in twochannel filter bank by tenfold, comparing to non-optimized version, written in Microsoft Visual C++ 2010 Express, without assembler extensions. The implementation described in this paper can be applied to computation of Discrete Wavelet Transform on general-purpose processors.
Źródło:
Journal of Applied Computer Science Methods; 2013, 5 No. 2; 123-135
1689-9636
Pojawia się w:
Journal of Applied Computer Science Methods
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Image fusion for travel time tomography inversion
Autorzy:
Yin, X.
Liu, L.
Zhao, X.
Ashraf, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/259784.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
tomography
inversion algorithm
wavelet transform
image fusion
Opis:
The travel time tomography technology had achieved wide application, the hinge of tomography was inversion algorithm, the ray path tracing technology had a great impact on the inversion results. In order to improve the SNR of inversion image, comprehensive utilization of inversion results with different ray tracing can be used. We presented an imaging fusion method based on improved Wilkinson iteration method. Firstly, the shortest path method and the linear travel time interpolation were used for forward calculation; then combined the improved Wilkinson iteration method with super relaxation precondition method to reduce the condition number of matrix and accelerate iterative speed, the precise integration method was used to solve the inverse matrix more precisely in tomography inversion process; finally, use wavelet transform for image fusion, obtain the final image. Therefore, the ill- conditioned linear equations were changed into iterative normal system through two times of treatment and using images with different forward algorithms for image fusion, it reduced the influence effect of measurement error on imaging. Simulation results showed that, this method can eliminate the artifacts in images effectively, it had extensive practical significance.
Źródło:
Polish Maritime Research; 2015, S 1; 149-156
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wavelet-based Entropy Measure for Rate-Distortion Optimization in Image Coding
Autorzy:
Garcia-Alvarez, J.
Führ, H.
Castellanos-Dominguez, G.
Powiązania:
https://bibliotekanauki.pl/articles/226142.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
entropy
wavelet transform
information measure
rate distortion
Opis:
A novel method for calculation of the entropy measure in wavelet space is proposed. This perceived-based entropy measure uses a Second Order Model entropy estimator, in which the occurrence of neighbors is considered in formulation. It has the intention to allow the implementation of a more suitable measure in coding processes and a relationship between the metric and the description of perceptual features. This method is used for the Rate-Distortion optimization in order to improve the bit-allocation coding algorithm, demonstrating that the wavelet-based entropy estimates a truncation step close to the target rate. The hypothesis is founded in the effect of distortion on the coefficient allocation. Because entropy measure is a close approximation of the conditional probability of image in multiresolution space, it provides an adequate representation for the information of a Detail feature. A definition of Detail-based homogeneity variance criteria is used for the information quantity - wavelet representation space, in order to find the image that fits a given Quality Level criteria. Experimental results are obtained for artificial and natural databases.
Źródło:
International Journal of Electronics and Telecommunications; 2010, 56, 1; 25-31
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phoneme Segmentation Based on Wavelet Spectra Analysis
Autorzy:
Ziółko, B.
Manandhar, S.
Wilson, R. C.
Ziółko, M.
Powiązania:
https://bibliotekanauki.pl/articles/177480.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
speech recognition
speech segmentation
discrete wavelet transform
Opis:
A phoneme segmentation method based on the analysis of discrete wavelet transform spectra is described. The localization of phoneme boundaries is particularly useful in speech recognition. It enables one to use more accurate acoustic models since the length of phonemes provide more information for parametrization. Our method relies on the values of power envelopes and their first derivatives for six frequency subbands. Specific scenarios that are typical for phoneme boundaries are searched for. Discrete times with such events are noted and graded using a distribution-like event function, which represent the change of the energy distribution in the frequency domain. The exact definition of this method is described in the paper. The final decision on localization of boundaries is taken by analysis of the event function. Boundaries are, therefore, extracted using information from all subbands. The method was developed on a small set of Polish hand segmented words and tested on another large corpus containing 16 425 utterances. A recall and precision measure specifically designed to measure the quality of speech segmentation was adapted by using fuzzy sets. From this, results with F-score equal to 72.49% were obtained.
Źródło:
Archives of Acoustics; 2011, 36, 1; 29-47
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Illumination for chatter mark detection using machine vision
Autorzy:
Szydłowski, M.
Powałka, B.
Berczyński, S.
Powiązania:
https://bibliotekanauki.pl/articles/100021.pdf
Data publikacji:
2014
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
inspection
chatter detection
image processing
wavelet transform
Opis:
Authors of this research present a new method for image acquisition using special illumination for milled surfaces. The presented method uses special light and camera setup to reveal chatter marks on processed surfaces. After the acquisition the images are digitally processed using a method based on Continuous Wavelet Transform. A milling experiment has been preformed for validation of the methods. The biggest advantage of this method is that it doesn't have to be manually set like other image processing methods used in chatter detection.
Źródło:
Journal of Machine Engineering; 2014, 14, 2; 38-46
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transformata falkowa wybranych sygnałów symulacyjnych
The discrete wavelet transform of the selected simulation signals
Autorzy:
Józefczyk, I.
Małecki, R.
Powiązania:
https://bibliotekanauki.pl/articles/257140.pdf
Data publikacji:
2013
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Eksploatacji - Państwowy Instytut Badawczy
Tematy:
sygnał
dyskretna transformacja falkowa
falka
signal
discrete wavelet transform
wavelet
Opis:
W artykule przedstawiono dyskretną transformcję falkową (DWT) dwóch sygnałów symulacyjnych z zastosowaniem falki dmey (dyskretny Meyer), której użyteczność potwierdziły wcześniejsze badania [5]. Przedmiotem badań były sygnały - wzorce oraz sygnały powstałe z wzorca poprzez dodanie tła losowego - zakłóceń. W celu wyeliminowania czynnika losowego sygnały zakłócone poddawano transformacji falkowej. Celem badań było poszukiwanie narzędzi statystycznych do określenia jakości transformacji falką dmey na różnych poziomach dekompozycji.
In the article, there was a Discrete Wavelet Transform (DWT) of two simulation signals shown with the usage of waves which had been proven to be effective in previous research. The subjects of the article are signals-modules and the signals created from the modules by adding a randomised background-interference. In order to eliminate the random factor, DWT was used against disrupted signals. The aim of the research was the search for statistical tools to assess the quality of dmey wave transformation.
Źródło:
Problemy Eksploatacji; 2013, 1; 27-34
1232-9312
Pojawia się w:
Problemy Eksploatacji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fault diagnosis of analog circuit based on wavelet transform and neural network
Autorzy:
Wang, Hui
Powiązania:
https://bibliotekanauki.pl/articles/141368.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
analog circuit
fault diagnosis
neural network
wavelet transform
Opis:
Analog circuits need more effective fault diagnosis methods. In this study, the fault diagnosis method of analog circuits was studied. The fault feature vectors were extracted by a wavelet transform and then classified by a generalized regression neural network (GRNN). In order to improve the classification performance, a wolf pack algorithm (WPA) was used to optimize the GRNN, and a WPA-GRNN diagnosis algorithm was obtained. Then a simulation experiment was carried out taking a Sallen–Key bandpass filter as an example. It was found from the experimental results that the WPA could achieve the preset accuracy in the eighth iteration and had a good optimization effect. In the comparison between the GRNN, genetic algorithm (GA)-GRNN and WPA-GRNN, the WPA-GRNN had the highest diagnostic accuracy, and moreover it had high accuracy in diagnosing a single fault than multiple faults, short training time, smaller error, and an average accuracy rate of 91%. The experimental results prove the effectiveness of the WPA-GRNN in fault diagnosis of analog circuits, which can make some contributions to the further development of the fault diagnosis of analog circuits.
Źródło:
Archives of Electrical Engineering; 2020, 69, 1; 175-185
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The progressive transmission method based on the 2-D wavelet transform for a digital video signal
Autorzy:
Murawski, K.
Powiązania:
https://bibliotekanauki.pl/articles/273329.pdf
Data publikacji:
2001
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
wavelet transform
digital transmission
video stream
multiresolution analysis
Opis:
This paper presents a method of progressive digital transmission of a video stream, based on picture frame multi-resolution analysis.
Źródło:
Biuletyn Instytutu Automatyki i Robotyki; 2001, R. 7, nr 15, 15; 15-25
1427-3578
Pojawia się w:
Biuletyn Instytutu Automatyki i Robotyki
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Autocorrelation Bark Wavelet Transform (PACWT) Features for Robust Speech Recognition
Autorzy:
Majeed, S. A.
Husain, H.
Samad, S. A.
Powiązania:
https://bibliotekanauki.pl/articles/177326.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
speech recognition
feature extraction
phase autocorrelation
wavelet transform
Opis:
In this paper, a new feature-extraction method is proposed to achieve robustness of speech recognition systems. This method combines the benefits of phase autocorrelation (PAC) with bark wavelet transform. PAC uses the angle to measure correlation instead of the traditional autocorrelation measure, whereas the bark wavelet transform is a special type of wavelet transform that is particularly designed for speech signals. The extracted features from this combined method are called phase autocorrelation bark wavelet transform (PACWT) features. The speech recognition performance of the PACWT features is evaluated and compared to the conventional feature extraction method mel frequency cepstrum coefficients (MFCC) using TI-Digits database under different types of noise and noise levels. This database has been divided into male and female data. The result shows that the word recognition rate using the PACWT features for noisy male data (white noise at 0 dB SNR) is 60%, whereas it is 41.35% for the MFCC features under identical conditions.
Źródło:
Archives of Acoustics; 2015, 40, 1; 25-31
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-dimensional octonion wavelet transform
Autorzy:
Katunin, A.
Powiązania:
https://bibliotekanauki.pl/articles/122330.pdf
Data publikacji:
2014
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
octonion wavelet transform
spatial data processing
octonionic wavelets
Opis:
The necessities of processing of spatial data require developing new feature-sensitive tools such as extensions of the wavelet transform. Considering the advantages of the application of complex wavelets and their extension to quaternionic wavelets for twodimensional data structures, the new octonion discrete wavelet transform for the analysis of three-dimensional data structures was introduced in this paper. The construction of the wavelet pyramid as well as octonionic wavelets were presented.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2014, 13, 1; 33-38
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected problems of damage detection in internally supported plates using one-dimensional Discrete Wavelet Transform
Autorzy:
Guminiak, M.
Knitter-Piątkowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/281731.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Kirchhoff plates
Boundary Element Method
Discrete Wavelet Transform
Opis:
The paper is concerned with damage detection in plates while using the Discrete Wavelet Transform (DWT). Rectangular plate structures resting on a Winkler or elastic half-space type foundation, with free boundaries are examined. Plate bending is described and solved by the Boundary Element Method in a direct approach. Defects are introduced by additional edges forming slots in relation to the basic plate domain. Numerical investigation is conducted basing on signal analysis of the structural static response and by taking advantage of multi-resolution analysis (MRA) of the signal function which can be represented in a multi-scale manner. The obtained signal is decomposed with the use of Daubechies or Coiflet wavelet families. The white noise generator is used to model measurement inaccuracy which is an inevitable element of a real experiment. The efficiency of DWT of the contaminated signal in damage detection is studied.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 3; 631-644
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 194

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