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Wyświetlanie 1-15 z 54
Tytuł:
The Abel summation of the Kontorovich-Lebedev integral representation
Autorzy:
Cojuhari, P.A.
Gomilko, A.M.
Powiązania:
https://bibliotekanauki.pl/articles/255109.pdf
Data publikacji:
2005
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
integral transforms
transforms of special functions
special functions
operational calculus
Kontorovich-Lebedev
Opis:
A new result on the summation of the Kontorovich-Lebedev integral representation in the sense of Abel mean is given.
Źródło:
Opuscula Mathematica; 2005, 25, 1; 101-107
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A two cones support theorem
Autorzy:
Estrada, R.
Powiązania:
https://bibliotekanauki.pl/articles/255211.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Radon transforms
support theorems
distributions
Opis:
We show that if the Radon transform of a distribution ƒ vanishes outside of an acute cone Co, the support of the distribution is contained in the union of Co and another acute cone C1, the cones are in a suitable position, and ƒ vanishes distributionally in the direction of the axis of C1, then actually supp ƒ C ⊂ Co. We show by examples that this result is sharp.
Źródło:
Opuscula Mathematica; 2016, 36, 2; 207-213
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convolution equations in the space of Laplace distributions
Autorzy:
Pliś, Maria
Powiązania:
https://bibliotekanauki.pl/articles/1294292.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Laplace distributions
Laplace transforms
convolution equations
Opis:
A formal solution of a nonlinear equation P(D)u = g(u) in 2 variables is constructed using the Laplace transformation and a convolution equation. We assume some conditions on the characteristic set Char P.
Źródło:
Annales Polonici Mathematici; 1998, 69, 3; 271-281
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poincaré theorem and nonlinear PDEs
Autorzy:
Pliś, Maria
Powiązania:
https://bibliotekanauki.pl/articles/1294309.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Laplace distributions
Laplace transforms
formal solutions
Opis:
A family of formal solutions of some type of nonlinear partial differential equations is found. Terms of such solutions are Laplace transforms of some Laplace distributions. The series of these distributions are locally finite.
Źródło:
Annales Polonici Mathematici; 1998, 69, 2; 99-105
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power system frequency estimation algorithm for electric energy metering of nonlinear loads
Autorzy:
Peng, Z.
Hong-Bin, L.
Powiązania:
https://bibliotekanauki.pl/articles/220639.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
frequency estimation
power systems
wavelet transforms
Opis:
In this paper, a discrete wavelet transform (DWT) based approach is proposed for power system frequency estimation. Unlike the existing frequency estimators mainly used for power system monitoring and control, the proposed approach is developed for fundamental frequency estimation in the field of energy metering of nonlinear loads. The characteristics of a nonlinear load is that the power signal is heavily distorted, composed of harmonics, inter-harmonics and corrupted by noise. The main idea is to predetermine a series of frequency points, and the mean value of two frequency points nearest to the power system frequency is accepted as the approximate solution. Firstly the input signal is modulated with a series of modulating signals, whose frequencies are those frequency points. Then the modulated signals are decomposed into individual frequency bands using DWT, and differences between the maximum and minimum wavelet coefficients in the lowest frequency band are calculated. Similarities among power system frequency and those frequency points are judged by the differences. Simulation results have proven high immunity to noise, harmonic and inter-harmonic interferences. The proposed method is applicable for real-time power system frequency estimation for electric energy measurement of nonlinear loads.
Źródło:
Metrology and Measurement Systems; 2012, 19, 2; 307-320
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The New Insight into the Theory of 2-D Complex and Quaternion Analytic Signals
Autorzy:
Snopek, K. M.
Powiązania:
https://bibliotekanauki.pl/articles/226235.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
2-D Fourier transform
quaternion Fourier transforms
2-D Hilbert transforms
2-D analytic signals
Opis:
The paper presents the overview of the theory of 2-D complex and quaternion analytic signals with the 1st-quadrant spectrum support. Both signals are expressed as complex/hypercomplex sums of partial and total 2-D Hilbert transforms. Moreover, starting with the definition of 2-D complex and quaternion Fourier transforms, the 2-D Hilbert transforms are derived in the form of sums of parts of different parity with respect to signal-domain variables. Some new relations for Hilbert quaternion spectra have been derived. The paper is illustrated with the example of the 2-D separable Cauchy signal.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 3; 285-291
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of information on sleep apnoea contained in two symmetric EEG recordings
Autorzy:
Prucnal, Monika A.
Polak, Adam G.
Powiązania:
https://bibliotekanauki.pl/articles/220736.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sleep apnoea detection
EEG signal
discrete wavelet transforms
Hilbert transforms
analysis of variance
multivariate regression analysis
Opis:
Electroencephalogram (EEG) is one of biomedical signals measured during all-night polysomnography to diagnose sleep disorders, including sleep apnoea. Usually two central EEG channels (C3-A2 and C4-A1) are recorded, but typically only one of them are used. The purpose of this work was to compare discriminative features characterizing normal breathing, as well as obstructive and central sleep apneas derived from these central EEG channels. The same methodology of feature extraction and selection was applied separately for the both synchronous signals. The features were extracted by combined discrete wavelet and Hilbert transforms. Afterwards, the statistical indexes were calculated and the features were selected using the analysis of variance and multivariate regression. According to the obtained results, there is a partial difference in information contained in the EEG signals carried by C3-A2 and C4-A1 EEG channels, so data from the both channels should be preferably used together for automatic sleep apnoea detection and differentiation.
Źródło:
Metrology and Measurement Systems; 2019, 26, 2; 229-239
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Abel means of operator-valued processes
Autorzy:
Blower, G.
Powiązania:
https://bibliotekanauki.pl/articles/1288981.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Abel means
martingale transforms
subadditive ergodic theory
Opis:
Let $(X_j)$ be a sequence of independent identically distributed random operators on a Banach space. We obtain necessary and sufficient conditions for the Abel means of $X_n...X_2 X_1$ to belong to Hardy and Lipschitz spaces a.s. We also obtain necessary and sufficient conditions on the Fourier coefficients of random Taylor series with bounded martingale coefficients to belong to Lipschitz and Bergman spaces.
Źródło:
Studia Mathematica; 1995, 115, 3; 261-276
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detecting epileptogenesis in power variant domains
Autorzy:
Lewis, R. A.
Parks, B.
Shmueli, D.
Capinst, S.
Powiązania:
https://bibliotekanauki.pl/articles/206373.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
intracortical electroencephalograms automata
epilepsy
Fourier transforms
rough sets
Opis:
This paper presents the merging of two sets of experiments in the continuing endeavor to mine epileptiform activity from Electroencephalograms (EEG). The goal is to develop robust classification rules for identifying epileptiform activity in the human brain. We present advancements using the author's proprietary developed spectral analysis software to link power spectra of rat EEGs experiencing epilepsy seizures with the authors DFA algorithm and their MATLAB spectral analysis. Our system links 1) power spectra of seizures, in sleep, spike and seizure states, with 2) Deterministic Finite Automata (DFA). Combining power spectra with DFA to correctly predict and identify epileptiform activity (spikes) and epileptic seizures opens the door to creating classifiers for seizures. We also present a DFA that separates the states between seizure and nonseizure using robust testing and additional algorithms to increase the rigor when the methodology analyses noisy signals. Our results show optimal identification of seizures even when significant artifact and noise is present in the polyphonic domain. Herein we present a dual methodology that increases epileptoid identification in a noisy domain that links time and frequency domain components from MATLAB and proprietary software to clinical epileptiform activity.
Źródło:
Control and Cybernetics; 2011, 40, 2; 293-314
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Response due to mechanical source in second axisymmetric problem of micropolar elastic medium
Autorzy:
Singh, R.
Powiązania:
https://bibliotekanauki.pl/articles/955263.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
transformata Laplace'a
siła skupiona
sprężystość
eigenvalue
micropolar elastic medium
Laplace transforms
Hankel transforms
concentrated force
microrotation
Rhomberg’s integration
Opis:
The second axisymmetric problem in a micropolar elastic medium has been investigated by employing an eigen value approach after applying the Laplace and the Hankel transforms. An example of infinite space with concentrated force at the origin has been presented to illustrate the application of the approach. The integral transforms have been inversed by using a numerical technique to obtain the components of microrotation, displacement, force stress and couple stress in the physical domain. The results for these quantities are given and illustratred graphically.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 4; 1249-1261
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural frequency and critical velocities of heated inclined pinned PP-R pipe conveying fluid
Autorzy:
Mohmmed, J. H.
Tawfik, M. A.
Atiyah, Q. A.
Powiązania:
https://bibliotekanauki.pl/articles/1818780.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
finite Fourier sine transforms
Laplace transforms
natural frequency
inclined pipe conveying fluid
transformacja Fouriera
transformacja Laplace'a
częstotliwości drgań własnych
Opis:
Purpose: The flow velocity and pressure of fluid flowing through a pipeline can cause the vibration of pipes, and consequently result in the modification in natural frequency via fluid-structure interaction. The value of the natural frequency of a component when approaches the excitation force to a certain degree, a severe resonance failure may occur. Hence, avoiding the resonance failure of a pipe subjected to complex conditions is an essential issue that requires to be solved urgently in the engineering field. This work treats the transverse vibration for flexible inclined heated pipe, made of polypropylene randomcopolymer (PP-R), conveying fluid assuming pinned connections at the ends. The pipe was placed at different support angles and subjected to variant temperatures. Design/methodology/approach: The inclined pipe is modelled as Euler-Bernoulli beam taking into account its self-weight, temperature variation, inclination angle, aspect ratio, and internal fluid velocity. The integral transforms method, which includes the finite Fourier sine and the Laplace transforms, was used to develop an analytic solution to the modified equation of motion and the analytical expressions for dual natural frequencies of the pipefluid interaction system were computed. Findings: The proposed solution technique via finite Fourier sine and Laplace transforms offers a more convenient alternative to calculate the dynamic characteristic of pipes conveying fluid. The obtained results showed that the dynamical behaviour of pipe–fluid system is strongly affected by fluid flow velocity, degree of inclination, temperature variation, and aspect ratio of the pipe in transverse modes. Research limitations/implications: This work focuses on fundamental (first) mode in the most discussions. Practical implications: It was revealed that the thermal effects in the pipe are a very important factor and more significant in comparison with the internal fluid velocity and the inclination angle has a larger impact on vibration characteristics at a higher aspect ratio. The findings can be useful for the design of engineering components. Originality/value: Determining the combining effect of inclination angle, aspect ratio, and thermal loading on vibration characteristic of the pipes conveying fluid by using an improved analytic solution to the modified equation of motion via mixed of finite Fourier sine and Laplace transforms.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2021, 107, 1; 15--27
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Induction motor fault classification via entropy and column correlation features of 2D represented vibration data
Autorzy:
Basaran, Murat
Fidan, Mehmet
Powiązania:
https://bibliotekanauki.pl/articles/1841827.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
entropy
fault diagnosis
support vector machines
wavelet transforms
Opis:
Due to long-term use under challenging conditions, the sub-elements of induction motors may suffer certain defects over time. Such defects impair the vibration characteristics of the motors in different ways, depending on the type of defect. Therefore, the change in vibration characteristic provides indicators about the fault type and can be used in preventive maintenance strategies to ensure safe operation of the system. In this work, discrete-time vibration data were transformed into 2-dimensional grey-level images and decomposed into individual components by the Wavelet decomposition method. Features based on entropy and column correlation were extracted from these components and used to classify motor faults by using the Support Vector Machine method implemented by using the Sequential Minimal Optimisation algorithm. When the selected classifier is compared with other popular Machine Learning algorithms, it is observed that motor faults are more successfully classified, and these observations are presented in detail with comparative classification performance results.
Źródło:
Eksploatacja i Niezawodność; 2021, 23, 1; 132-142
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of fundamental solutions to fractional diffusion-wave equation in polar coordinates
Autorzy:
Povstenko, Y.
Powiązania:
https://bibliotekanauki.pl/articles/121886.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
Tematy:
równanie ułamkowe
problem Cauchy'ego
transformaty Laplace'a
transformata Hankela
fractional equations
Cauchy problem
Laplace transforms
Hankel and Laplace transforms
Opis:
The diffusion-wave equation is a mathematical model of a wide range of important physical phenomena. The first and second Cauchy problems and the source problem for the diffusion-wave equation are considered in cylindrical coordinates. The Caputo fractional derivative is used. The Laplace and Hankel transforms are employed. The results are illustrated graphically.
Źródło:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics; 2009, 14; 97-104
2450-9302
Pojawia się w:
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The elasticity problem for a stratified semi-infinite medium containing a penny-shaped crack filled with a gas
Zagadnienie półnieskończonego uwarstwionego ośrodka sprężystego zawierającego szczelinę kołową wypełnioną gazem
Autorzy:
Monastyrskyy, B.
Kaczyński, A.
Powiązania:
https://bibliotekanauki.pl/articles/386663.pdf
Data publikacji:
2007
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
sprężystość
naprężenie
transformacja Hankela
stress intensity
elasticity
Hankel transforms
Opis:
This paper deals with a periodic two-layered elastic half-space weakened by an interface penny-shaped crack tilled with a gas. The study is based on the approximate treatment by using the linear elasticity with microlocal parameters in the axisymmetric case. Applying the Hankel integral transforms, we obtain a system of dual integral equations. It is reduced to a set of two integral equations which are solved numerically. Some results concerning the variation of the internal gas pressure and the stress intensity factors of mode I and mode II are illustrated graphically.
Niniejsza praca poświęcona jest zagadnieniu periodycznej dwuwarstwowej półprzestrzeni sprężystej osłabionej międzywarstwową szczeliną kołową wypełnioną gazem. Zastosowano przybliżone podejście oparte na liniowej teorii sprężystości z parametrami mikrolokalnymi w osiowo-symetrycznym przypadku. Używając transformacji Hankela, otrzymano układ dualnych równań całkowych, który sprowadzono do numerycznego rozwiązania równań całkowych. Zależności dotyczące wewnętrznego ciśnienia gazu i współczynników intensywności naprężeń zilustrowano graficznie.
Źródło:
Acta Mechanica et Automatica; 2007, 1, 1; 63-66
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Derivation of Discrete Time Fourier Transform from Its Continuous Counterpart
Autorzy:
Borys, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/227150.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sampling of signals
discrete time
continuous time
Fourier transforms
Opis:
This paper is devoted to some problems that appear in derivations of the discrete time Fourier transform from a formula for its continuous time counterpart for transformation from the time into the frequency domain as well as to those regarding transformation in the inverse direction. In particular, the latter ones remained so far an unresolved problem. It is solved for the first time here. Many detailed explanations accompanying the solution found are presented. Finally, it is also worth noting that our derivations do not exploit any of such sophisticated mathematical tools as the so-called Dirac delta and Dirac comb.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 2; 355-360
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 54

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