Temat: spectral analysis - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Spectral analysis of multi-year GNSS code multipath time-series
Autorzy:: Kudrys, Jacek
Tematy:: GNSS
code multipath
spectral analysis
spectral index; Pokaż więcej
Data publikacji:: 2019
Powiązania:: https://bibliotekanauki.pl/articles/390405.pdf Link otwiera się w nowym oknie
Źródło:: Budownictwo i Architektura; 2019, 18, 4; 15-22
1899-0665
Pojawia się w:: Budownictwo i Architektura
Opis:: In the presented study multi-year time series of changes in the L1 pseudo-range multipath are analysed. Data from 8 stations of the EUREF Permanent Network (EPN) were used in the study. Periodic components present in the signal and their stability over time were analysed. Also, the type of background noise was determined, based on the spectral index. In some cases, the presence of weak components with a 1/2 and 1/3 of the Chandler period has also been found. Time-frequency analysis shows that periodic signals are not stationary in most of the examined cases, and particular signal components occur only temporarily. The analysed signals were char-acterised by pink noise in the lower frequency range and by white noise for higher frequencies, which is also characteristic for time series of coordinates obtained from GNSS measurements.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: A spectral theory for locally compact abelian groups of automorphisms of commutative Banach algebras
Autorzy:: Zhong Huang, Sen
Tematy:: automorphism
group representation
spectral analysis; Pokaż więcej
Data publikacji:: 1999
Powiązania:: https://bibliotekanauki.pl/articles/1217351.pdf Link otwiera się w nowym oknie
Źródło:: Studia Mathematica; 1999, 132, 1; 37-69
0039-3223
Pojawia się w:: Studia Mathematica
Opis:: Let A be a commutative Banach algebra with Gelfand space ∆ (A). Denote by Aut (A) the group of all continuous automorphisms of A. Consider a σ(A,∆(A))-continuous group representation α:G → Aut(A) of a locally compact abelian group G by automorphisms of A. For each a ∈ A and φ ∈ ∆(A), the function $φ_a(t):=φ(α_t a)$ t ∈ G is in the space C(G) of all continuous and bounded functions on G. The weak-star spectrum $σ_w*(φ_a)$ is defined as a closed subset of the dual group Ĝ of G. For φ ∈ ∆(A) we define $Ʌ_φ^a$ to be the union of all sets $σ_w*(φ_a)$ where a ∈ A, and $Λ_α$ to be the closure of the union of all sets $Ʌ_φ^a$ where φ ∈ ∆(A), and call $Λ_α$ the unitary spectrum of α. Starting by showing that the closure of $Ʌ_φ^a$ (for fixed φ ∈ ∆(A)) is a subsemigroup of Ĝ we characterize the structure properties of the group representation α such as norm continuity, growth and existence of non-trivial invariant subspaces through its unitary spectrum $Λ_α.$ For an automorphism T of a semisimple commutative Banach algebra A we consider the group representation T: ℤ → Aut (A) defined by $T_n:=T^n$ for all n ∈ ℤ. It is shown that $Λ_T=σ(T)∩$, where σ(T) is the spectrum of T and is the unit circle. From this fact we give an easy proof of the Kamowitz-Scheinberg theorem which asserts that the spectrum σ(T) either contains or is a finite union of finite subgroups of .
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Measurement and analysis of coastal waves along the north sea area of China
Autorzy:: Sun, S.
Li, H.
Sun, H.
Tematy:: coastal wave
measurement
buoy
spectral analysis; Pokaż więcej
Data publikacji:: 2016
Powiązania:: https://bibliotekanauki.pl/articles/259794.pdf Link otwiera się w nowym oknie
Źródło:: Polish Maritime Research; 2016, 3; 72-78
1233-2585
Pojawia się w:: Polish Maritime Research
Opis:: Taking advantage of coastal wave environment to carry out scaled ship model test is an effective testing technology for ship performance. In this paper, the method of spectral analysis is adopted to calculate the significant wave height, period, wave spectrum and some other parameters of some places along the North Sea area of China. The measured wave spectrum and the ocean spectrum are handled into non-dimensional form to evaluate their similarity. The influence of wind direction and tide on coastal waves was analyzed. And the results indicate that the coastal wave spectrum is similar to the ocean spectrum under some specific conditions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Spectral analysis of dynamic laser speckle patterns by using a full-field temporal modulation method
Autorzy:: Dake, W
Chasteen, E
Onyeuku, C
Tematy:: laser speckle
spectral analysis
light scattering; Pokaż więcej
Data publikacji:: 2013
Powiązania:: https://bibliotekanauki.pl/articles/174461.pdf Link otwiera się w nowym oknie
Źródło:: Optica Applicata; 2013, 43, 4; 871-882
0078-5466
1899-7015
Pojawia się w:: Optica Applicata
Opis:: We introduce an approach for analyzing the power spectrum of the time-varying intensity in the dynamic laser speckle patterns. The method is free from the limitation imposed by the Nyquist criterion on the minimum sampling rate. The temporal modulation shifts the intensity fluctuation spectrum by an amount that is equal to the modulation frequency. The subsequent integration of the intensity signal, performed at each detector pixel, acts effectively as a low-pass filter allowing the extraction of the spectral component at the modulation frequency. Within the speed range from 1 to 10 mm/s investigated in our experiment, the result demonstrates that the moving speed of the diffuse object can be determined with a good accuracy.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Diagnostics of commutator DC motor basing on spectral analysis of signals
Autorzy:: Głowacz, Z.
Zdrojewski, A.
Tematy:: commutator dc motor
rotor asymmetries
spectral analysis; Pokaż więcej
Data publikacji:: 2008
Powiązania:: https://bibliotekanauki.pl/articles/262623.pdf Link otwiera się w nowym oknie
Źródło:: Electrical Power Quality and Utilisation. Journal; 2008, 14, 1; 85-88
1896-4672
Pojawia się w:: Electrical Power Quality and Utilisation. Journal
Opis:: Measurement investigations have been carried out for commutator dc motor with internal asymmetries. Construction of considered motor enables to realize the breaking of one rotor coil and shorting of two groups of rotor coils. Each group contains three rotor coils. The basis of study were signals: current and voltage of field winding, current and voltage of armature winding and velocity of the rotor. The presented in this paper results of spectral analysis of signals create new possibilities for diagnostics of commutator dc motor.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Cyclical Properties of the Credit and Production in Selected European Countries - a Comparison of Deterministic and Stochastic Cycle Approach
Autorzy:: Lenart, Ł.
Pipień, M.
Tematy:: almost periodicity
spectral analysis
financial cycle
production cycle; Pokaż więcej
Data publikacji:: 2018-06
Powiązania:: https://bibliotekanauki.pl/articles/1029291.pdf Link otwiera się w nowym oknie
Źródło:: Acta Physica Polonica A; 2018, 133, 6; 1371-1387
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Opis:: We develop two nonparametric approaches to analyze the empirical properties of economic cycles. The first approach is based on almost periodically correlated time series commonly used in signal processing. Within this framework we depart from standard scheme of analysis that relies on stationarity assumption. The second approach is based on spectral analysis provided the stationarity assumption of cyclical fluctuations. We contribute to the existing literature in both, theoretical and empirical aspects. From theoretical viewpoint we develop methods of formal statistical inference about the main properties of elements of the economic cycle. In the first approach the testing procedure utilizing subsampling approach is proposed. In the second approach the method of analysis of concentration of the spectral mass is developed. Based on the monthly series of the credit aggregate and the industrial production, taken from selected European countries, we discuss the empirical properties of the credit cycle and we compare them with the production cycle. Our empirical findings show substantial diversity of the credit cycle across analysed countries. Also cyclical component in the credit series is identified much stronger than in case of the series of industrial production. Also the production cycles are much more synchronized across countries compared to the credit cycles.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Zastosowanie spektroskopii UV-VIS w analizie optycznej kremów fotoprotekcyjnych
Application of UV-VIS spectroscope in optical analysis of photoprotection creams
Autorzy:: Adamczyk, J.
Deda, A.
Wilczyński, S.
Zdybel, M.
Tematy:: analiza spektralna
widmo
kremy
spectral analysis
spectrum
creams; Pokaż więcej
Data publikacji:: 2009
Powiązania:: https://bibliotekanauki.pl/articles/285268.pdf Link otwiera się w nowym oknie
Źródło:: Engineering of Biomaterials; 2009, 12, no. 89-91; 148-149
1429-7248
Pojawia się w:: Engineering of Biomaterials
Opis:: Analizie poddano kremy do opalania dostępne w Polsce. Badano widmo źródła światła po przejściu przez warstwę każdego kremu. Wykazano różnice w krzywych spektralnych dla różnych kremów.
The different sun cream available on polish cosmetic market were studied. The spectra of light source of every cream were investigated. The significant divergence for the different creams spectra curves were observed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Nontrivial solutions of linear functional equations: methods and examples
Autorzy:: Varga, A.
Vincze, C.
Tematy:: linear functional equations
spectral analysis
field homomorphisms; Pokaż więcej
Data publikacji:: 2015
Powiązania:: https://bibliotekanauki.pl/articles/255015.pdf Link otwiera się w nowym oknie
Źródło:: Opuscula Mathematica; 2015, 35, 6; 957-972
1232-9274
2300-6919
Pojawia się w:: Opuscula Mathematica
Opis:: For a wide class of linear functional equations the solutions are generalized polynomials. The existence of non-trivial monomial terms of the solution strongly depends on the algebraic properties of some related families of parameters. As a continuation of the previous work [A. Varga, Cs. Vincze, G. Kiss, Algebraic methods for the solution of linear functional equations, Acta Math. Hungar.] we are going to present constructive algebraic methods of the solution in some special cases. Explicit examples will be also given.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Aspekty techniczne rejestracji oraz analizy sygnałów elektroencefalograficznych
Technical aspects of EEG signal recording and analysis
Autorzy:: Szuflitowska, B.
Tematy:: elektroencefalograf
elektrody
analiza widmowa
electroencephalograph
electrodes
spectral analysis; Pokaż więcej
Data publikacji:: 2018
Powiązania:: https://bibliotekanauki.pl/articles/268564.pdf Link otwiera się w nowym oknie
Źródło:: Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2018, 59; 191-194
1425-5766
2353-1290
Pojawia się w:: Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Opis:: Elektroencefalografia jest techniką powszechnie stosowaną w diagnostyce medycznej oraz w badaniach. W artykule opisano zasadę pomiarów EEG i scharakteryzowano aparaturę pomiarową oraz metody rejestracji. Artykuł podzielony jest na dwie części. W pierwszej przedstawiono metody rejestracji sygnałów EEG oraz ich zastosowania kliniczne, a w drugiej narzędzia analizy widmowej. W pracy zostały użyte rzeczywiste sekwencje sygnałów EEG określone przez lekarza jako sygnały prawidłowe oraz wskazujące na chorobę (napadowe). Ich analiza została wykonana za pomocą szybkiej transformaty Fouriera oraz dyskretnej transformaty falkowej. Obliczano widmo mocy, a uzyskane średnie wartości mocy spektralnej stanowiły podstawę wskazania stanu patologicznego.
Electroencephalography, as an electrophysiological method to record electrical activity of the brain, is commonly used in medicine and research areas. This article presents theoretical basics of EEG measurement. This method is still being developed. The greatest emphasis is put on improvement of the measuring equipment and recording methods. The solutions to improve hardware and software are still sought. This article is divided into two main parts. The first part explains EEG recording and its clinical applications. Epilepsy is the most common neurological disorder. The future trends in the development of EEG are pointed out. In the second part spectral analysis tools are presented. The EEG signal has nonlinear and nonstationary properties In the paper, real EEG sequences described by a doctor as normal and epileptic (ictal) are used. The analysis is performed using fast Fourier transform and discrete wavelet transform. The power spectrum in each frequency band is calculated. The obtained average power spectral values allow to distinguish epileptic sequences. Spectral analysis is considered to be a potential tool that may aid in the diagnosis of neurological diseases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

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.
Tematy:: harmonic analysis
power quality
signal reconstruction
spectral analysis
harmonic distortion; Pokaż więcej
Data publikacji:: 2012
Powiązania:: https://bibliotekanauki.pl/articles/220641.pdf Link otwiera się w nowym oknie
Źródło:: Metrology and Measurement Systems; 2012, 19, 2; 295-306
0860-8229
Pojawia się w:: Metrology and Measurement Systems
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.
Dostawca treści:: Biblioteka Nauki

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