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Wyszukujesz frazę "Fourier transform" wg kryterium: Temat


Tytuł:
Filtering Property of Signal Sampling in General and Under-Sampling as a Specific Operation of Filtering Connected with Signal Shaping at the Same Time
Autorzy:
Borys, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/226441.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
signal sampling
filtering
discrete-time Fourier transform
Opis:
In this paper, we show that signal sampling operation can be considered as a kind of all-pass filtering in the time domain, when the Nyquist frequency is larger or equal to the maximal frequency in the spectrum of a signal sampled. We demonstrate that this seemingly obvious observation has wide-ranging implications. They are discussed here in detail. Furthermore, we discuss also signal shaping effects that occur in the case of signal under-sampling. That is, when the Nyquist frequency is smaller than the maximal frequency in the spectrum of a signal sampled. Further, we explain the mechanism of a specific signal distortion that arises under these circumstances. We call it the signal shaping, not the signal aliasing, because of many reasons discussed throughout this paper. Mainly however because of the fact that the operation behind it, called also the signal shaping here, is not a filtering in a usual sense. And, it is shown that this kind of shaping depends upon the sampling phase. Furthermore, formulated in other words, this operation can be viewed as a one which shapes the signal and performs the low-pass filtering of it at the same time. Also, an interesting relation connecting the Fourier transform of a signal filtered with the use of an ideal low-pass filter having the cut frequency lying in the region of under-sampling with the Fourier transforms of its two under-sampled versions is derived. This relation is presented in the time domain, too.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 3; 589-594
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of non-ideal signal sampling via averaging operation and spectrum of sampled signal predicted by this model
Autorzy:
Borys, A.
Powiązania:
https://bibliotekanauki.pl/articles/2172501.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
modelling of non-Ideal signal sampling
non-Ideal signal
spectrum of sampled signal
A/D converters
non-Ideal signal sampling
signal sampling
discrete time fourier transform
Opis:
In this paper, a novel model of a non-ideal signal sampling via a local, periodic averaging operation is present-ed. The spectrum of a sampled signal predicted by this model is also analysed as well as compared with a one following from another model.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2022, 16, 2; 274--278
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustical Analysis of Enclosure as Initial Approach to Vehicle Induced Noise Analysis Comparatevely Using STFT and Wavelets
Autorzy:
Błażejewski, A.
Kozioł, P.
Łuczak, M.
Powiązania:
https://bibliotekanauki.pl/articles/176551.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
modal analysis
short-time Fourier transform
wavelet transform
acoustic signal processing
Opis:
It is assumed in the paper that the signals in the enclosure in a transient period are similar to a noise induced by vehicles, tracks, cars, etc. passing by. The components of such signals usually points out specific dynamic processes running during the observation or measurements. In order to choose the best method of analysis of these phenomena, an acoustic field in a closed space with a sound source inside is created. Acoustic modes of this space influence the sound field. Analytically, the modal analyses describe the above mentioned phenomena. The experimental measurements were conducted in the room that might comprise the closed space with known boundary conditions and the sound source Br¨uel & Kjær Omni-directional type 4292 inside. To record sound signals before the field’s steady state was reached, the microphone type 4349 and the 4-channel frontend 3590 had been used. The obtained signals have been analysed by using two approaches, i.e. Fourier and the wavelet analysis, with the emphasis on their efficiency and the capability to recognise important details of the signal. The results obtained for the enclosure might lead to the formulation of a methodology for an extended investigation of a rail track or vehicles dynamics.
Źródło:
Archives of Acoustics; 2014, 39, 3; 385-394
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie algebr hiperzespolonych w przetwarzaniu sygnałów
Application of hypercomplex algebras in signal processing
Autorzy:
Błaszczyk, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/134792.pdf
Data publikacji:
2016
Wydawca:
ADVSEO
Tematy:
hypercomplex algebras
quaternion Fourier transform
octonion Fourier transform
system analysis
partial differential equations
Opis:
The subject of this paper is the application of hypercomplex algebras (in particular quaternions and octonions) in the analysis of time-invariant linear systems. We present the Cayley-Dickson construction of hypercomplex algebras and its important properties. Moreover, we formulate the concept of quaternion and octonion Fourier transform and their properties important from the signal processing point of view. We present an overview of known quaternion Fourier transform applications in the analysis of systems and partial differential equations of two variables. We also point out the direction of further work in the subject of application of the octonion Fourier transform in system analysis and analysis of partial differential equations of three variables. Such considerations are possible thanks to recently proved properties of octonion Fourier transform, which are also stated in this paper.
Źródło:
Technical Issues; 2016, 3; 13-18
2392-3954
Pojawia się w:
Technical Issues
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Boehmians of type S and their Fourier transforms
Autorzy:
Bhuvaneswari, R.
Karunakaran, V.
Powiązania:
https://bibliotekanauki.pl/articles/747250.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
Boehmians
spaces of type S
Fourier transform
Opis:
Function spaces of type S are introduced and investigated in the literature. They are also applied to study the Cauchy problem. In this paper we shall extend the concept of these spaces to the context of Boehmian spaces and study the Fourier transform theory on these spaces. These spaces enable us to combine the theory of Fourier transform on these function spaces as well as their dual spaces.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica; 2010, 54, 1
0365-1029
2083-7402
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio A – Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Automatic Genre Classification Using Fractional Fourier Transform Based Mel Frequency Cepstral Coefficient and Timbral Features
Autorzy:
Bhalke, D. G.
Rajesh, B.
Bormane, D. S.
Powiązania:
https://bibliotekanauki.pl/articles/177599.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
feature extraction
Timbral features
MFCC
Mel Frequency Cepstral Coefficient
FrFT
fractional Fourier transform
Fractional MFCC
Tamil Carnatic music
Opis:
This paper presents the Automatic Genre Classification of Indian Tamil Music and Western Music using Timbral and Fractional Fourier Transform (FrFT) based Mel Frequency Cepstral Coefficient (MFCC) features. The classifier model for the proposed system has been built using K-NN (K-Nearest Neighbours) and Support Vector Machine (SVM). In this work, the performance of various features extracted from music excerpts has been analysed, to identify the appropriate feature descriptors for the two major genres of Indian Tamil music, namely Classical music (Carnatic based devotional hymn compositions) & Folk music and for western genres of Rock and Classical music from the GTZAN dataset. The results for Tamil music have shown that the feature combination of Spectral Roll off, Spectral Flux, Spectral Skewness and Spectral Kurtosis, combined with Fractional MFCC features, outperforms all other feature combinations, to yield a higher classification accuracy of 96.05%, as compared to the accuracy of 84.21% with conventional MFCC. It has also been observed that the FrFT based MFCC effieciently classifies the two western genres of Rock and Classical music from the GTZAN dataset with a higher classification accuracy of 96.25% as compared to the classification accuracy of 80% with MFCC.
Źródło:
Archives of Acoustics; 2017, 42, 2; 213-222
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxidative Aging Characterization of Pyro-Oil Modified Binders Using Fourier Transform Infrared Spectroscopy
Autorzy:
Bhagat, Nikita Taran
Hadole, Hemantkumar Prakash
Ranadive, Mahadeo Sambhaji
Powiązania:
https://bibliotekanauki.pl/articles/2201866.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
pyro-oil
aging
asphalt binder
FTIR
Fourier Transform Infrared
carbonyls
sulfoxides
HDPE processing
plastic waste
pyrolysis of plastics
Opis:
The numerous uses for plastics in various industries have led to an increase in its manufacturing on a global scale over time. The accumulation of plastic waste is a direct result of the daily rise in plastic demand. One of the effective and trending ways of reducing the impact of plastic waste on the environment is to pyrolyze it and use the oil obtained from it as fuel for power generation, heating, extraction of chemicals, or as an asphalt binder modifier. In this study, an attempt was made for the modification of asphalt binder with the oil obtained from plastic waste pyrolysis known as pyro-oil, and to analyse aging properties of the modified binder. This paper deals with the modification of VG30 binder with pyro-oil obtained from High Density Polyethylene (HDPE) plastic waste and the analysing the effect of aging on the modified binders. Pyro-oil is yielded from the pyrolysis process of HDPE at about 750°C. The modified binders were prepared by adding 1%, 2%, and 3% pyro-oil by total weight of VG30. The effect of aging for the unmodified and modified binders was analyzed using fourier transform infrared (FTIR) spectroscopy. The binders were short term aged and the changes in their chemical functionalities before and after aging were analyzed. Results of the FTIR test were used to calculate functional group indices for evaluating the aging characteristics of the modified binders. It was observed that binder chemistry is influenced by aging.
Źródło:
Advances in Science and Technology. Research Journal; 2023, 17, 1; 140--149
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Validity of the Noise Model of Quantization for the Frequency-Domain Amplitude Estimation of Low-Level Sine Waves
Autorzy:
Bellan, D.
Powiązania:
https://bibliotekanauki.pl/articles/221016.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
quantization
amplitude estimation
sine wave
discrete Fourier transform
additive noise
Opis:
This paper deals with the amplitude estimation in the frequency domain of low-level sine waves, i.e. sine waves spanning a small number of quantization steps of an analog-to-digital converter. This is a quite common condition for high-speed low-resolution converters. A digitized sine wave is transformed into the frequency domain through the discrete Fourier transform. The error in the amplitude estimate is treated as a random variable since the offset and the phase of the sine wave are usually unknown. Therefore, the estimate is characterized by its standard deviation. The proposed model evaluates properly such a standard deviation by treating the quantization with a Fourier series approach. On the other hand, it is shown that the conventional noise model of quantization would lead to a large underestimation of the error standard deviation. The effects of measurement parameters, such as the number of samples and a kind of the time window, are also investigated. Finally, a threshold for the additive noise is provided as the boundary for validity of the two quantization models.
Źródło:
Metrology and Measurement Systems; 2015, 22, 1; 89-100
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of wavelet-Fourier analysis into drawing-shaft reinforcement diagnostics
Zastosowanie analizy falkowej-Fouriera w diagnostyce zbrojenia szybowego
Autorzy:
Batko, W.
Krzyworzeka, P.
Mikulski, A.
Powiązania:
https://bibliotekanauki.pl/articles/328824.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
diagnostyka
transformata falkowa-Fouriera
analiza niestacjonarna
diagnostic
wavelet-Fourier transform
non-stationary analysis
Opis:
Impulse tests are commonly encountered in the research of dynamic properties of frame constructions in their operation time. One of the most significant problem issue associated with the application of these tests is description problems and unambiguous interpretation of non-stationary measurements results. New approach introduced by the authors involves system response-signal filtration by means of wavelet analysis and taking advantage of the information contained within the signal's energy. The article describes the application of wavelet-Fourier transformation for determining frequency spectrum from recovered impulse response. Practical usage is illustrated by the example shaft reinforcement in an underground mine.
W badaniach własności dynamicznych konstrukcji kratowych w trakcie eksploatacji wykorzystuje się zazwyczaj testy impulsowe. Jednym z istotnych utrudnień ich stosowania są problemy opisu oraz jednoznacznej interpretacji niestacjonarnych wyników pomiaru. Nowością zaproponowaną przez autorów jest filtracja sygnału odpowiedzi układu za pomocą analizy falkowej oraz wykorzystanie informacji zawartej w energii sygnału. Opisano sposób wykorzystania transformacji falkowej-Fouriera dla wyznaczenia widma częstotliwościowego ze zrekonstruowanej odpowiedzi impulsowej. Możliwości praktyczne ilustruje przykład zbrojenia szybowego kopalni podziemnej.
Źródło:
Diagnostyka; 2006, 1(37); 127-133
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
P-wave interaction with a pair of rigid strips embedded in an orthotropic strip
Autorzy:
Basu, S.
Mandal, S. C.
Powiązania:
https://bibliotekanauki.pl/articles/281710.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
P-wave
Fourier transform
Hilbert transform
Fredholm integral equation
stress intensity factor
Opis:
The present paper is concerned with the problem of scattering of the P-wave by two co- -planer finite rigid strips placed symmetrically in an infinitely long orthotropic strip. Using the Hilbert transform technique, the mixed boundary value problem has been reduced to the solution of dual integral equations which has finally been reduced to the solution of a Fredholm integral equation of the second kind. Solving this integral equation numerically, stress intensity factors have been calculated at the inner and outer edges of the rigid strips, and the vertical displacement outside the strips has been calculated and plotted graphically to show the effect of material orthotropy.
Źródło:
Journal of Theoretical and Applied Mechanics; 2016, 54, 2; 579-592
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Classification of Seizure Types Using Random Forest Classifier
Autorzy:
Basri, Ashjan
Arif, Muhammad
Powiązania:
https://bibliotekanauki.pl/articles/2123290.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
EEG
fast fourier transform
seizure
random forest
Opis:
Epilepsy is one of the most common mental disorders in the world, affecting 65 million people. The prevalence in Arab countries of Epilepsy is estimated at 174 per 100,000 individuals, and in Saudi Arabia is 6.54 per 1,000 individuals. Epilepsy seizures have different types, and each patient needs to have a treatment plan according to the seizure type. Hence, accurate classification of seizure type is an essential part of diagnosing and treating epileptic patients. In this paper, features based on fast Fourier transform from EEG montages are used to classify different types of seizures. Since the distribution of classes is not uniform and the dataset suffers from severe imbalance. Various algorithms are used to under-sample the majority class and over-sample the minority classes. Random forest classifier produced classification accuracy of 96% to differentiate three types of seizures from the healthy EEG reading.
Źródło:
Advances in Science and Technology. Research Journal; 2021, 15, 3; 167--178
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vibrations detection in industrial plumps based on spectral analysis to increase their efficiency
Zwiększenie efektywności pomp przemysłowych w wyniku detekcji wibracji bazującej na analizie widma
Autorzy:
Balhadef, R.
Hafajfa, A.
Boumehraz, M.
Powiązania:
https://bibliotekanauki.pl/articles/410075.pdf
Data publikacji:
2016
Wydawca:
STE GROUP
Tematy:
Spectral analysis
vibration signal
vibration analysis
rotating machinery
centrifugal pump
signal estimation
Fourier transform
Prony approach
analiza widma
sygnał wibracji
analiza wibracji
maszyna wirująca
pompa odśrodkowa
estymacja sygnału
transformata Fouriera
model Prony’ego
Opis:
Spectral analysis is the key tool for the study of vibration signals in rotating machinery. In this work, the vibration analysis applied for conditional preventive maintenance of such machines is proposed, as part of resolved problems related to vibration detection on the organs of these machines. The vibration signal of a centrifugal pump was treated to mount the benefits of the approach proposed. The obtained results present the signal estimation of a pump vibration using Fourier transform technique compared by the spectral analysis methods based on Prony approach.
Analiza widma jest kluczowym narzędziem badania sygnałów dotyczących wibracji w maszynach wirujących. W niniejszej pracy proponuje się analizę wibracji dla oceny stanu technicznego tych maszyn w ramach utrzymania prewencyjnego, bazującą na detekcji wibracji ich poszczególnych elementów. Przydatność i korzyści zaproponowanego podejścia zostały ocenione podczas badania pompy odśrodkowej. Uzyskane wyniki przedstawiają estymację sygnałów wibracji pompy z wykorzystaniem transformaty Fouriera w porównaniu z przeprowadzoną analizą widma z zastosowaniem modelu Prony’ego.
Źródło:
Management Systems in Production Engineering; 2016, 1 (21); 55-61
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inversion of the Riemann-Liouville operator and its dual using wavelets
Autorzy:
Baccar, C.
Hamadi, N. B.
Herch, H.
Meherzi, F.
Powiązania:
https://bibliotekanauki.pl/articles/952838.pdf
Data publikacji:
2015
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
inverse problem
Riemann-Liouville operator
Fourier transform
wavelets
Opis:
We define and study the generalized continuous wavelet transform associated with the Riemann-Liouville operator that we use to express the new inversion formulas of the Riemann-Liouville operator and its dual.
Źródło:
Opuscula Mathematica; 2015, 35, 6; 867-887
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparison of methods for obtaining nanocellulose using acid and ionic liquid hydrolysis reactions
Autorzy:
Babicka, Marta
Ratajczak, Izabela
Dwiecki, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/24072146.pdf
Data publikacji:
2019
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
1-butyl-3-methylimidazolium chloride
sulphuric acid(VI)
acid hydrolysis
ionic liquid hydrolysis
dynamic light scattering
fourier transform infrared spectroscopy
Opis:
A comparison of methods for obtaining nanocellulose using acid and ionic liquid hydrolysis reactions. In this study, two methods were compared, i.e. acid hydrolysis using sulphuric acid (VI) and ionic liquid hydrolysis using 1-methyl-3-butylimidazolium chloride to obtain nanocellulose from Sigmacell Cellulose Type 20. The efficiency of both processes was tested for weight loss of the material during the reaction. The study showed that much more material can be obtained using ionic liquid hydrolysis than using acid hydrolysis. A dynamic light scattering study was performed to determine material particle size before and after these processes. Particles of nanometric size were recorded only for cellulose after the reaction with an ionic liquid. In addition, Fourier transform infrared spectroscopy was performed to determine the chemical structure of the materials tested.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology; 2019, 107; 19--23
1898-5912
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement accuracy verification of phasor measurement unit with dynamic phasor estimation
Autorzy:
Arendarski, B.
Rabe, S.
Heineken, W.
Komarnicki, P.
Powiązania:
https://bibliotekanauki.pl/articles/140719.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
discrete Fourier transform (DFT)
dynamic phasor
measurement accuracy
phasor measurement unit (PMU)
power system
Opis:
Power systems that are highly loaded, especially by a stochastic supply of renew- ables and the presence of storages, require dynamic measurements for their optimal control. Phasor measurement units (PMUs) can be used to capture electrical parameters of a power system. Standards on the PMU dynamic performance have been modified to incorporate their new dynamic mode of operation. This paper examines the PMU dynamic performance and proposes essential algorithms for measurement accuracy verification. Measurements of dynamic input signals, which vary in amplitude or frequency, were taken during au- tomated tests of two PMUs. The test results are presented and expounded with further recommendation for the performance requirements. This paper also presents and examines applied testing procedures with relevance to the specifications of the IEEE Standard for Synchrophasor C37.118.1™-2011 and its amendment C37.118.1a™-2014.
Źródło:
Archives of Electrical Engineering; 2018, 67, 3; 529--543
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

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