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Wyświetlanie 1-15 z 44
Tytuł:
Koncepcja układu dla filtracji zakłóceń z jednoczesnym wiernym odtwarzaniem dużych skokowych zmian sygnału
The idea of system for filtering of disturbances with simultaneous possibility of execution of accurate follow up action in case of input signal step changes
Autorzy:
Żuchowski, A.
Grzywacz, B.
Powiązania:
https://bibliotekanauki.pl/articles/158017.pdf
Data publikacji:
2007
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
skalowane czasowo filtry dolnoprzepustowe
szybkie szacowanie amplitud skokowych zmian sygnału w obecności szumu
scaling of low-pass filters in time and frequency domain
Opis:
Przedstawiono koncepcję skalowanego czasowo (i zarazem częstotliwościowo) filtru dolnoprzepustowego, gdzie funkcję skalującą 1
The idea of scaling of low-pass filter in time and frequency domain has been presented in the paper. The scaling function 1
Źródło:
Pomiary Automatyka Kontrola; 2007, R. 53, nr 12, 12; 3-4
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reflektometria częstotliwościowa jako selektywna metoda pomiaru wilgotności gleby
Frequency domain reflectometry as a selective method for soil moisture measurement
Autorzy:
Wilczek, A.
Skierucha, W.
Powiązania:
https://bibliotekanauki.pl/articles/152769.pdf
Data publikacji:
2010
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
wilgotność gleby
zespolona przenikalność dielektryczna
reflektometria częstotliwościowa
soil moisture
complex dielectric permittivity
frequency domain reflectometry
Opis:
W niniejszej pracy zbadano wpływ zasolenia gleby na selektywność pomiaru jej wilgotności wykonanego metodą reflektometrii częstotliwościowej. W pracy podjęto próbę opracowania i oceny nowej sondy dwu-prętowej. W oparciu o zjawisko transformacji impedancji opracowano model sondy umożliwiający pomiar widma do częstotliwości 500 MHz. Metodą referencyjną pomiaru wilgotności był pomiar termograwimetryczny. Z pomiarów wynika, że dla pasma powyżej 300 MHz zastosowana metoda pozwala na selektywny pomiar wilgotności gleby.
The paper presents investigations of the influence of soil salinity on moisture measurements. The measurements were made by the (FDR) frequency domain reflectometry method. This method allows obtaining the frequency spectrum of complex dielectric permittivity when using the presented electrical model of the applied probe. Application of dielectric spectroscopy methods to analysis of results enables obtaining other information, besides moisture and salinity, about investigated soils. There is presented the use of a two-rod probe and its evaluation from the point of view of soil moisture selective measurements. An electrical model of the probe was formulated basing on the impedance transformation phenomenon in symmetrical waveguides. This model allows achieving 500 MHz frequency band unavailable till now for two-rod probes in commercial devices. Black earth soil type samples from Annopol were investigated. All measurements were taken with a vector network analyzer ZVCE produced by Rohde&Schwartz. The measured complex reflection coefficient S11 from the probe was used to obtain 10-500 MHz frequency spectrum of complex dielectric permittivity. The thermogravimetric measurement method of soil volumetric water content was used as the reference one. Five series of ten soil samples of different moisture and electrical conductivity values were analysed. The results show that the described FDR method allows measuring soil moisture selectively above 300 MHz.
Źródło:
Pomiary Automatyka Kontrola; 2010, R. 56, nr 8, 8; 867-870
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-efficiency carrier frequency estimation algorithm for real-time multi-domain communication signal analysis
Autorzy:
Wang, Q.
Yang, X.
Yan, X
Qin, K.
Powiązania:
https://bibliotekanauki.pl/articles/221239.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
carrier frequency estimation
multi-domain communication
signal analysis
Opis:
Based on real-time multi-domain communication signal analysis architecture, a high-efficiency blind carrier frequency estimation algorithm using the power spectrum symmetry of the measured modulated signal is presented. The proposed algorithm, which utilizes the moving averaged power spectrum achieved by the realtime spectrum analysis, iteratively identifies the carrier frequency in according to the power difference between the upper sideband and lower sideband, which is defined and revised by the estimated carrier frequency in each iteration. When the power difference of the two sidebands converges to the preset threshold, the carrier frequency can be obtained. For the modulation analysis, the measured signal can be coarsely compensated by the estimated result, and the residual carrier frequency error is eliminated by a following carrier synchronization loop. Compared with previous works, owing to the moving averaged power spectrum normalization and the smart iterative step variation mechanism for the two sidebands definition, the carrier frequency estimation accuracy and speed can be significantly improved without increasing the computational effort. Experimental results are included to demonstrate the outstanding performance of the proposed algorithm.
Źródło:
Metrology and Measurement Systems; 2014, 21, 2; 281-292
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Improved Method of Permutation Correction in Convolutive Blind Source Separation
Autorzy:
Wang, L.
Ding, H.
Yin, F.
Powiązania:
https://bibliotekanauki.pl/articles/177954.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
blind source separation
cocktail party
convolutive mixing
frequency domain
permutation problem
Opis:
This paper proposes an improved method of solving the permutation problem inherent in frequency-domain of convolutive blind source separation (BSS). It combines a novel inter-frequency dependence measure: the power ratio of separated signals, and a simple but effective bin-wise permutation alignment scheme. The proposed method is easy to implement and surpasses the conventional ones. Simulations have shown that it can provide an almost ideal solution of the permutation problem for a case where two or three sources were mixed in a room with a reverberation time of 130 ms.
Źródło:
Archives of Acoustics; 2010, 35, 4; 493-504
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of upper extremity position on EMG signal measures calculated in time, frequency and time-frequency domains
Autorzy:
Wang, J.
Bartuzi, P.
Roman-Liu, D.
Powiązania:
https://bibliotekanauki.pl/articles/306619.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
upper extremity
EMG
position
time-frequency domain
postawa ciała
biomechanika
Opis:
The aim of this study was to investigate the relationship between time-frequency, time and frequency measures when considering various upper extremity positions below the level of the shoulder and in trapezius as well as deltoideus muscles. During the experiment, 15 subjects performed a task that involved screwing and unscrewing a screw cap on a board in six different locations, i.e., there were six upper extremity positions. Variables were calculated in the time, frequency and time-frequency domains on a recorded EMG signal. The results showed that parameters analyzed in the time-frequency domain were more sensitive to changes in position than parameters analyzed in the frequency domain.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 4; 83-91
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gain scheduled controller design for thermo-optical plant
Autorzy:
Veselý, V
Osuský, J
Sekaj, I.
Powiązania:
https://bibliotekanauki.pl/articles/229643.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gain scheduled control
small gain theorem
frequency domain
genetic algorithm
control performance
Opis:
This paper presents a gain scheduled controller design for MIMO and SISO systems in the frequency domain using the genetic algorithms approach. The proposed method is derived from the M-delta structure of closed loop MIMO (SISO) systems and the small gain theory is exploited to obtain the stability condition. An example of real system illustrates the effectiveness of the proposed output feedback gain scheduled controller design method and also the possibility to improve its performance using the genetic algorithm.
Źródło:
Archives of Control Sciences; 2014, 24, 3; 333-349
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Binaural speech segregation system on single board computer
Autorzy:
Usagawa, Tsuyoshi
Irwansyah, Irwansyah
Powiązania:
https://bibliotekanauki.pl/articles/950427.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
frequency domain binaural model
single-board computer
hearing assistance
open-source software
komputer jednopłytkowy
wsparcie słuchu
oprogramowanie otwarte
Opis:
A pocket-size binaural speech segregation system has been developed and assembled with available consumer hardware. It can enhance a target speech in a certain direction while attenuating interfering sounds from other directions. This system is based on the frequency domain binaural model (FDBM) and it segregates multiple speeches based on the directivity. This real-time system is implemented on a low-cost single board computer which might be used as a hearing assistance device. Performance of the system is evaluated in a normal laboratory room as well as anechoic chamber. Even in a room with reverberation, the system works well and show the almost same performance obtained in anechoic chamber.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-9
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of sensor-based condition monitoring methods as in-process tool wear and breakage indices - case study: drilling
Autorzy:
Tsanakas, J. A.
Botsaris, P. N.
Amirids, I. G.
Galeridis, G. G.
Powiązania:
https://bibliotekanauki.pl/articles/329544.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
tool condition monitoring
vibration signals
thermal signatures
spindle motor current
tool wear
statistical analysis
frequency domain analysis
Opis:
Today, effective unmanned machining operations and automated manufacturing are unthinkable without tool condition monitoring (TCM). Undoubtedly, the implementation of an adaptable, reliable TCM and its successful employment in industry, emerge as major instigations over the recent years. In this work, a sensor-based approach was deployed for the in-process monitoring and detection of tool wear and breakage in drilling. In particular, four widely reported indirect methods for tool wear monitoring, i.e. vibration signals together with thermal signatures, spindle motor and feed motor current measurements were obtained during numerous drillings, under fixed conditions. The acquired raw data was, then, processed both statistically and in the frequency domain, in order to distinguish the meaningful information. The study of the latter is influential in identifying the trend of specific signals toward tool wear mechanism. The efficiency of this information as a tool wear and/or breakage index is the feature that determines the effectiveness and reliability of a potential indirect TCM approach based on a multisensor integration. The paper concludes with a discussion of both advantages and limitations of this effort, stressing the necessity to develop simple, fast condition monitoring methods which are, generally, less likely to fail.
Źródło:
Diagnostyka; 2012, 2(62); 3-13
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonparametric identification of added masses in frequency domain: a numerical study
Autorzy:
Suwała, G.
Biczyk, J.
Jankowski, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/31343109.pdf
Data publikacji:
2013
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
structural health monitoring
mass identification
frequency domain
virtual distortion method
czujniki pomiarowe
inteligentne czujniki pomiarowe
domena częstotliwości
Opis:
This paper presents a theoretical derivation and reports on a numerical verification of a model-free method for identification of added masses in truss structures. No parametric numerical model of the monitored structure is required, so there is no need for initial model updating and fine tuning. This is a continuation and an improvement of a previous research that resulted in a time-domain identification method, which was tested to be accurate but very time-consuming. A general methodology is briefly introduced, including the inverse problem, and a numerical verification is reported. The aim of the numerical study is to test the accuracy of the proposed method and its sensitivity to various parameters (such as simulated measurement noise and decay rate of the exponential FFT window) in a numerically controlled environment. The verification uses a finite element model of the same real structure that was tested with the time-domain version of the approach. A natural further step is a lab verification based on experimental data.
Źródło:
IPPT Reports on Fundamental Technological Research; 2013, 4; 37-41
2299-3657
Pojawia się w:
IPPT Reports on Fundamental Technological Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial-frequency domain analysis of defect signals in rail magnetic-dynamic non-destructive testing
Analiza sygnałów w obszarze przestrzenno-częstotliwościowym w nieniszczącej magnetycznej-dynamicznej defektoskopii szyn
Autorzy:
Storozh, I.
Nichoga, V.
Dub, P.
Grudzinski, Е.
Powiązania:
https://bibliotekanauki.pl/articles/251558.pdf
Data publikacji:
2012
Wydawca:
Instytut Naukowo-Wydawniczy TTS
Tematy:
signals analysis
defects in rails
spatial-frequency domain
magnetic defectoscope
analiza sygnałów
wady w szynach
obszar przestrzenno-częstotliwościowy
defektoskop magnetyczny
Opis:
The aim of the investigation is search of possible methods of automatic processing of defect signals from a magnetic testing carriage that realizes magnetic-dynamic non-destructive testing. The wavelet-like transform with a fragment of the recorded signal as a mother function was used to analyze the transversal crack signal. The signal pattern was resampled (rescaled) in such way that a file of signals, that were stretched or compressed relatively to the original length, was created. The described methods can be used for detection of dangerous defects in rails. The programme realization does not require large amount of calculation that enables to carry out real-time signal processing.
Wciąż prowadzone są poszukiwania metod automatyzacji procesu obróbki dynamicznych sygnałów pochodzących z defektoskopu magnetycznego umieszczonego w wagonie pomiarowym. Dla analіzy sygnałów od poprzecznego pęknięcia zostały wprowadzone przekształcenia, w których w rolі funkcji macierzystej występuje fragment zapisanego sygnału. Wycinek sygnału poddano dyskretyzacji i przeskalowaniu tak, że otrzymano przebiegi sygnałów, które są rozciągnięte lub ściśnięte w odniesieniu do pierwotnej długości. Opisane metody mogą być używane dla wykrywania niebezpiecznych wad w szynach. Realizacja nie wymaga dużych mocy obliczeniowych i umożliwia prowadzenie i przetwarzanie sygnałów w czasie rzeczywistym.
Źródło:
TTS Technika Transportu Szynowego; 2012, 9; 479-483, CD
1232-3829
2543-5728
Pojawia się w:
TTS Technika Transportu Szynowego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
TDR and low-frequency measurements for continuous monitoring of moisture and density in a snow pack
Autorzy:
Stacheder, M.
Powiązania:
https://bibliotekanauki.pl/articles/25546.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
moisture
low-frequency measurement
monitoring
time domain reflectometry
density
snow density
Źródło:
International Agrophysics; 2005, 19, 1
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-linear modelling of elastic hysteretic damping in the time domain
Autorzy:
Spitas, C.
Dwaikat, M. M. S.
Spitas, V.
Powiązania:
https://bibliotekanauki.pl/articles/38606055.pdf
Data publikacji:
2020
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
hysteresis
damping
modified viscous model
dynamics time-domain
mechanical vibration
frequency
non-linear modeling
Opis:
Elastic hysteretic damping is defined as the dissipation of energy at a rate that is weakly dependent on frequency of vibration. In this article, we propose that the elastic hysteretic damping can be achieved by a simple modification to the viscous damping model. The proposed modification is based on computing an instantaneous correction factor that recursively depends on the state variables of the system. This correction factor is related to the rate by which the velocity changes with respect to the displacement. The new model compares quite favourably with the other existing solutions in the time-domain and differences between the solutions become evident for higher damping ratios. It is found that the new model predicts consistently the weak variation in the loss factor as a function of frequency. In addition to its simple mathematical formulation, the proposed model is superior to the existing solutions in that it does not require knowledge of the past history of motion neither the knowledge of the excitation frequency and is extensible to any type of loading. Various aspects pertaining to the linearity of the proposed approach are finally discussed.
Źródło:
Archives of Mechanics; 2020, 72, 4; 323-353
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Open-Ended Coax and TDR sensors for the measurement of soil dielectric permittivity in microwave frequencies
Autorzy:
Skierucha, W.
Walczak, R.
Wilczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/24912.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
microwave frequency
soil permittivity
measurement
soil
dielectrical permittivity
time domain reflectometry
Źródło:
International Agrophysics; 2004, 18, 4
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Software-Defined Radio for Rayleigh and Raman Scattering Measurement in Optical Fibers
Autorzy:
Shatarah, I. S. M.
Więcek, B.
Powiązania:
https://bibliotekanauki.pl/articles/114286.pdf
Data publikacji:
2018
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
Rayleigh and Raman scattering
synchronous detection
silica optical fiber
optical frequency domain reflectometry
Opis:
A laboratory system for measuring the Raman scattering light in optical fiber is presented. The system is equipped with the developed driver for 5 mW/1550 nm laser diode, optical circulator, WDM filters to separate Rayleigh and Raman scattered light and InGaAs cooled photodiode to detect the weak scattered radiation. Instead of using expensive network analyzer we propose to use Software-Defined Radio, which ensures the necessary sensitivity and selectivity of detected signals. The preliminary results are presented for about 3 km – length single mode silica optical fiber.
Źródło:
Measurement Automation Monitoring; 2018, 64, 4; 112-115
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An identification procedure of electromagnetic parameters for an induction motor equivalent circuit including rotor deep bar effect
Autorzy:
Rolek, J.
Utrata, G.
Powiązania:
https://bibliotekanauki.pl/articles/141612.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
induction motors
equivalent circuits
parameter identification
frequency-domain analysis
genetic algorithms
Opis:
The paper presents an identification procedure of electromagnetic parameters for an induction motor equivalent circuit including rotor deep bar effect. The presented procedure employs information obtained from measurement realised under the load curve test, described in the standard PN-EN 60034-28: 2013. In the article, the selected impedance frequency characteristics of the tested induction machines derived from measurement have been compared with the corresponding characteristics calculated with the use of the adopted equivalent circuit with electromagnetic parameters determined according to the presented procedure. Furthermore, the characteristics computed on the basis of the classical machine T-type equivalent circuit, whose electromagnetic parameters had been identified in line with the chosen methodologies reported in the standards PN-EN 60034-28: 2013 and IEEE Std 112TM-2004, have been included in the comparative analysis as well. Additional verification of correctness of identified electromagnetic parameters has been realised through comparison of the steady-state power factor-slip and torque-slip characteristics determined experimentally and through the machine operation simulations carried out with the use of the considered equivalent circuits. The studies concerning induction motors with two types of rotor construction – a conventional single cage rotor and a solid rotor manufactured from magnetic material – have been presented in the paper.
Źródło:
Archives of Electrical Engineering; 2018, 67, 2; 279--291
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 44

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