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Wyświetlanie 1-15 z 55
Tytuł:
An approach for electrical harmonic analysis based on interpolation DFT
Autorzy:
Jiao, Lina
Du, Yang
Powiązania:
https://bibliotekanauki.pl/articles/2086690.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electrical harmonic analysis
DFT
interpolation
Opis:
The discrete Fourier transform (DFT) is the main method of electrical harmonic analysis since it’s easily realized in an embedded system. But there were some difficulties in performing synchronized sampling. The spectral leakage caused by asynchronous sampling affects the accuracy of harmonics analysis. Using window functions and interpolation algorithms can improve the accuracy of harmonics analysis. An approach for electrical harmonic analysis based on the interpolation DFT was proposed. A window function reduces DFT leakage and the interpolation algorithm modifies the calculation results of frequency, amplitude and the initial phase angle. The simulation results indicate that, by using the interpolation DFT electrical harmonic analysis method based on the Hanning window or the Blackman window, the error of calculating amplitudes and frequencies is not greater than 0.5%.
Źródło:
Archives of Electrical Engineering; 2022, 71, 2; 445--454
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Invariant operators on function spaces on homogeneous trees
Autorzy:
Cowling, Michael
Meda, Stefano
Setti, Alberto
Powiązania:
https://bibliotekanauki.pl/articles/965849.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
spherical functions
harmonic analysis
homogeneous trees
Źródło:
Colloquium Mathematicum; 1999, 80, 1; 53-61
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the use of multi-harmonic least-squares fitting for THD estimation in power quality analysis
Autorzy:
Ramos, P. M.
Janeiro, F. M.
Radil, T.
Powiązania:
https://bibliotekanauki.pl/articles/220641.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
harmonic analysis
power quality
signal reconstruction
spectral analysis
harmonic distortion
Opis:
The quality of the supplied power by electricity utilities is regulated and of concern to the end user. Power quality disturbances include interruptions, sags, swells, transients and harmonic distortion. The instruments used to measure these disturbances have to satisfy minimum requirements set by international standards. In this paper, an analysis of multi-harmonic least-squares fitting algorithms applied to total harmonic distortion (THD) estimation is presented. The results from the different least-squares algorithms are compared with the results from the discrete Fourier transform (DFT) algorithm. The algorithms are assessed in the different testing states required by the standards.
Źródło:
Metrology and Measurement Systems; 2012, 19, 2; 295-306
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prony’s method with reduced sampling - numerical aspects
Autorzy:
Zygarlicki, J.
Mroczka, J.
Powiązania:
https://bibliotekanauki.pl/articles/220676.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
signal analysis
harmonic analysis
signal processing
power quality
Opis:
This paper presents a new modification of the least-squares Prony’s method with reduced sampling, which allows for a significant reduction in the number of the analysed signal samples collected per unit time. The specific combination of non-uniform sampling with Prony’s method enables sampling of the analysed signals at virtually any average frequency, regardless of the Nyquist frequency, maintaining high accuracy in parameter estimation of sinusoidal signal components. This property allows using the method in measuring devices, such as for electric power quality testing equipped with low power signal processors, which in turn contributes to reducing complexity of these devices. This paper presents research on a method for selecting a sampling frequency and an analysis window length for the presented method, which provide maximum estimation accuracy for Prony’s model component parameters. This paper presents simulation tests performed in terms of the proposed method application for analysis of harmonics and interharmonics in electric power signals. Furthermore, the paper provides sensitivity analysis of the method, in terms of common interferences occurring in the actual measurement systems.
Źródło:
Metrology and Measurement Systems; 2014, 21, 3; 521-534
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Two Model Coupling Methods for Joint Identication
Autorzy:
Susen, J.
Sulitka, M.
Sindler, J.
Janota, M.
Powiązania:
https://bibliotekanauki.pl/articles/99775.pdf
Data publikacji:
2015
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
machine tool
mutlibody model
component coupling
harmonic analysis
Opis:
An experimental identification of joint dynamic properties requires accurate models of the joined bodies and an appropriate model coupling method. The bodies to be coupled can be described by their mass, stiffness and damping matrices (M, K, C) or by receptance matrices. Each approach has its advantages and disadvantages. The receptance matrix method requires a high number of measurements. However the measured data can be used directly and no model identification is needed. The experimental identification of the M, K, C matrices feasible for creating precise coupled models is difficult. Therefore, an approach based on a verified FE model can be employed. The two methods of model identification and coupling are discussed using a case study of two bolted beams. Several ways of the receptance matrices measurement simplification and their influence on the accuracy of the results are studied. The effect of noise, measured FRF peak accuracy and data filtering on the resulting coupled receptance matrix is studied as well. The results obtained by the receptance matrix method are compared to the results obtained by the method of coupling the verified FE models. It has been found that the method based on coupling the verified M, K, C matrices proves to be a more reliable approach, which will allow a more precise joint dynamic model identification in the next step.
Źródło:
Journal of Machine Engineering; 2015, 15, 1; 58-70
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Harmonic domain modelling of transformer core nonlinearities using the DIgSILENT powerfactory software
Autorzy:
Wiechowski, W.
Bak-Jensen, B.
Bak, C. L.
Lykkegaard, J.
Powiązania:
https://bibliotekanauki.pl/articles/262821.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
Tematy:
autotransformers
harmonic analysis
nonlinearities
simulation software
transformer cores
Opis:
This paper demonstrates the results of implementation and verification of an already existing algorithm that allows for calculating saturation characteristics of singlephase power transformers. The algorithm was described for the first time in 1993. Now this algorithm has been implemented using the DIgSILENT Programming Language (DPL) as an external script in the harmonic domain calculations of a power system analysis tool PowerFactory [10]. The algorithm is verified by harmonic measurements on a single-phase power transformer. A theoretical analysis of the core nonlinearities phenomena in single and three-phase transformers is also presented. This analysis leads to the conclusion that the method can be applied for modelling nonlinearities of three-phase autotransformers.
Źródło:
Electrical Power Quality and Utilisation. Journal; 2008, 14, 1; 3-11
1896-4672
Pojawia się w:
Electrical Power Quality and Utilisation. Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coupled modelling for machine tool structural optimization
Autorzy:
Sulitka, M.
Sindler, J.
Susen, J.
Powiązania:
https://bibliotekanauki.pl/articles/99670.pdf
Data publikacji:
2014
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
mutlibody model
component coupling
finite element
harmonic analysis
Opis:
Effective machine tool design needs to take into account various kinematic configurations and possible combinations of structural parts, which meet the requirements of both the structural properties on one hand and technology and cost limitation on the other hand. Prior to a detailed developing a certain machine tool structure, an expert based decision on the machine tool conception needs to be performed. A high number of design variants should be explored in a short time. Fulfilling those demands leads to developing a machine tool modular models, enabling easy changing the kinematic configuration or various structural parts. In the paper the techniques for effective component coupling and model order reduction using mode truncation or Krylov subspace based technique for creating the machine tool coupled models are introduced. Case studies considering real machine tool structures are given. High quality of Krylov subspace reduction technique in connection with multipoint constraint surface coupling is shown both in terms of dynamic properties of the reduced multibody model and a very low time demands at the same time.
Źródło:
Journal of Machine Engineering; 2014, 14, 3; 21-34
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Presentation of a Wavelet-Based Harmonic Model for Tidal Level Forecasting at Sabah and Sarawak
Autorzy:
Abubakar, Auwal Garba
Mahmud, Mohd Razali
Tang, Kelvin Kang Wee
Husaaini, Alhaji
Powiązania:
https://bibliotekanauki.pl/articles/1837991.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
harmonic analysis
harmonic constituents
sea water level
tidal prediction
wavelet-based harmonic
Opis:
The world’s tides are a result of the combined forces of celestial forces and centrifugal force exerted by the Earth Moon and the Sun acting on the water body, earth tides and the atmospheric tides. Harmonic analysis is the most popular and widely accepted method used for the processing and expression of tidal behaviour as well as its characteristics. Despite its strengths, harmonic analysis has a few drawbacks when short data are involved for long term prediction. However, to enhance the accuracy of the popular methodology of harmonic analysis (HA), this study presents a wavelet based harmonic model for tidal analysis and prediction. Six months of water level heights at four tide gauge stations in Sabah and Sarawak of Malaysia were employed. The results obtained agrees with the original data when a comparison was made. The root mean square error (RMSE) and Pearson correlation coefficient (r) are the statistical index tools applied to test the functioning of the model. The residual error is the deviation between the original data and the predicted data which was also computed in this study. The new wavelet based harmonic model improves the accuracy of prediction. Moreover, the model is efficient and feasible for tidal analysis and prediction.
Źródło:
Geomatics and Environmental Engineering; 2020, 14, 4; 5-23
1898-1135
Pojawia się w:
Geomatics and Environmental Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applying Harmonic Analysis in the Measurements of Geometrical Deviations of the Crankshafts – Selecting Support Conditions
Autorzy:
Nozdrzykowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/2064978.pdf
Data publikacji:
2018
Wydawca:
STE GROUP
Tematy:
harmonic analysis
geometrical deviations
elastic deflections
crankshafts
support conditions
Opis:
The article presents principles of the most suitable support conditions which enable elimination of deflections and elastic deformations of crankshafts under their self-weight. On the basis of the formulated principles sample calculations of force values of support reactions were performed. This guarantees zero value of deflections on main journals depending on the angle of rotation of the shaft, applying available programme of strength calculations Nastran FX 2010. The obtained results have been approximated with a mathematical equation applying the calculating method based on the harmonic analysis theory. Then a comparative assessment of the force diagram (the forces were obtained via strength calculations and mathematical model including so called mutual inter-correlation coefficient) was made. The obtained results of comparative analysis showed high correspondence between the compared diagrams. Presented procedures of determining the required forces ensuring elimination of deflections and elastic deformations can be applied to measurements of crankshaft geometrical deviations realized on the basis of a measuring system with, so called, flexible support of a measured object.
Źródło:
Multidisciplinary Aspects of Production Engineering; 2018, 1, 1; 191--195
2545-2827
Pojawia się w:
Multidisciplinary Aspects of Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ANALYSIS OF ECONOMIC ACTIVITY MOVEMENTS IN THE CZECH REPUBLIC – FREQUENCY APPROACH
Autorzy:
Poměnková, Jitka
Powiązania:
https://bibliotekanauki.pl/articles/453003.pdf
Data publikacji:
2009
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Katedra Ekonometrii i Statystyki
Tematy:
harmonic analysis
deterministic trends
stochastic cycles
economic activity
business cycle
Opis:
The primary purpose of this work is to identify the business cycle types in the Czech Republic. In the light of business cycles problematic, and viewed from the frequency analysis perspective, harmonic analysis will be used. From the range of de-trending techniques, the first order difference, linear filtering, unobserved component model and Hodrick-Prescott filter are used. In the case of Hodrick-Prescott filter, a cyclical fluctuation estimate with the derivation of smoothing parameter designed specially for the Czech Republic case is investigated. The aim is to distinguish types of cyclical fluctuations in the Czech Republic. A consequent analysis of potential sources of cyclical movement is done.
Źródło:
Metody Ilościowe w Badaniach Ekonomicznych; 2009, 10, 1; 207-220
2082-792X
Pojawia się w:
Metody Ilościowe w Badaniach Ekonomicznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Masso-stoimostnye zavisimosti prostranstvennykh indukcionnykh preobrazovatelejj s aksialnym shtampopressovannym i vitym magnitoprovodami
Mass value on the spatial induction converter with axially stamp-pressed and twisted magnetic circuits
Autorzy:
Sadovoy, A.
Powiązania:
https://bibliotekanauki.pl/articles/77944.pdf
Data publikacji:
2015
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
target function
electromagnetic processe
material consumption
harmonic analysis
calculation model
Źródło:
Motrol. Motoryzacja i Energetyka Rolnictwa; 2015, 17, 2
1730-8658
Pojawia się w:
Motrol. Motoryzacja i Energetyka Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Circuit for Balancing Harmonic-Polluted Three-Phase Networks
Autorzy:
Saied, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/262835.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
Tematy:
harmonic analysis
power quality
load balancing
frequency scan
Steinmetz circuit
Opis:
This paper presents a new circuit capable of balancing harmonics-polluted three-phase power networks supplying single-phase loads. It takes into account the negative and positive sequences exhibited by the fifth and seventh harmonics, respectively. The concept extends the relations of the Steinmetz circuit, which are based exclusively on fundamental frequency considerations. The Steinmetz circuit does not, therefore, guarantee the balancing of the different harmonics in the line currents. Furthermore, it can lead to resonances between the capacitive and inductive elements in the two added balancing branches. A procedure for identifying the topology and the circuit parameters of the proposed connection is given. The results of a detailed case study are presented in order to demonstrate the superiority of the proposed circuit over the conventional Steinmetz connection.
Źródło:
Electrical Power Quality and Utilisation. Journal; 2013, 16, 1; 19-24
1896-4672
Pojawia się w:
Electrical Power Quality and Utilisation. Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radiation of mining grounds - case study forecasting the hazard level of ionizing
Prognozowanie poziomu zagrożenia promieniowaniem jonizującym na terenach górniczych - studium przypadku
Autorzy:
Korban, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1206269.pdf
Data publikacji:
2015
Wydawca:
STE GROUP
Tematy:
hazard of ionizing radiation
harmonic analysis
szkodliwości promieniowania jonizującego
analiza harmoniczna
Opis:
When analyzing time series we can often observe that they have periodic oscillations (cyclic, seasonal). One of the methods which can be applied to investigate such a phenomenon and which belongs to the group of periodic components models is the method of harmonic analysis. The method consists in analyzing the oscillations around the medium level a0 and building a model as the sum of so called harmonics. The paper presents the applicability potential of harmonic analysis in the forecasting process of radiation hazard on post-mining grounds (mine waters with raised content of radium Ra226 and Ra-228 drained off to the surface), using for that purpose the measurement results of radium concentration from the area of mine water catchment from the years 2004-2013.
Analizując szeregi czasowe często dostrzegamy w nich wahania okresowe (cykliczne, sezonowe). Jedną z metod pozwalającą na badanie tego typu zjawisk jest należąca do grupy modeli składowej periodycznej analiza harmoniczna. Metoda ta opiera się na badaniu wahań wokół poziomu średniego a0 i na budowie modelu w postaci sumy tzw. harmonik. W artykule przedstawiono możliwości wykorzystania analizy harmonicznej w procesie prognozowania występowania zagrożenia radiacyjnego na terenach pogórniczych (wody kopalniane o podwyższonej zawartości radu Ra-226 i Ra-228 odprowadzane na powierzchnię) wykorzystując w tym celu wyniki pomiarów stężenia radu w jednym z rejonów zlewni wód dołowych z lat 2004-2013.
Źródło:
Management Systems in Production Engineering; 2015, 2 (18); 51-57
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Harmonic analysis of torsional vibration force excitation
Autorzy:
Urbanský, M.
Powiązania:
https://bibliotekanauki.pl/articles/196998.pdf
Data publikacji:
2017
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
torsional vibration
force excitation
harmonic analysis
drgania skrętne
wymuszenie siły
analiza harmoniczna
Opis:
In our department, we deal with various methods for the continuous tuning of torsional oscillating mechanical systems during their operation, mainly in terms of torsional vibration magnitude. Therefore, in order to carry out necessary experimental research, we need torsional oscillation exciters, which operate on various principles. The objective of this paper is to conduct a harmonic analysis of a torsional oscillation force excitation mechanism, in order to identify the possibilities of its application.
Źródło:
Zeszyty Naukowe. Transport / Politechnika Śląska; 2017, 97; 181-187
0209-3324
2450-1549
Pojawia się w:
Zeszyty Naukowe. Transport / Politechnika Śląska
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 55

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