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    Wyświetlanie 1-8 z 8
    Tytuł:
    A hybrid approach for fault diagnosis of spur gears using Hu invariant moments and artificial neural networks
    Autorzy:
    Rex, F. Michael Thomas
    Andrews, A.
    Krishnakumari, A.
    Hariharasakthisudhan, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/220768.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    gear fault
    Ahao-Atlas-Marks
    time-frequency domain features
    Hu invariant moments
    ANN
    Opis:
    Achieving a reliable fault diagnosis for gears under variable operating conditions is a pressing need of industries to ensure productivity by averting unwanted breakdowns. In the present work, a hybrid approach is proposed by integrating Hu invariant moments and an artificial neural network for explicit extraction and classification of gear faults using time-frequency transforms. The Zhao-Atlas-Marks transform is used to convert the raw vibrations signals from the gears into time-frequency distributions. The proposed method is applied to a single-stage spur gearbox with faults created using electric discharge machining in laboratory conditions. The results show the effectiveness of the proposed methodology in classifying the faults in gears with high accuracy.
    Źródło:
    Metrology and Measurement Systems; 2020, 27, 3; 451-464
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Applications and Comparison of Continuous Wavelet Transforms on Analysis of A-wave Impulse Noise
    Autorzy:
    Qin, J.
    Sun, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/177117.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    continuous wavelet transform (CWT)
    impulse noise signal processing
    time-frequency domain
    temporal and spectral resolutions
    noise-induced hearing loss
    A-wave impulse noise
    Opis:
    Noise induced hearing loss (NIHL) is a serious occupational related health problem worldwide. The A-wave impulse noise could cause severe hearing loss, and characteristics of such kind of impulse noise in the joint time-frequency (T-F) domain are critical for evaluation of auditory hazard level. This study focuses on the analysis of A-wave impulse noise in the T-F domain using continual wavelet transforms. Three different wavelets, referring to Morlet, Mexican hat, and Meyer wavelets, were investigated and compared based on theoretical analysis and applications to experimental generated A-wave impulse noise signals. The underlying theory of continuous wavelet transform was given and the temporal and spectral resolutions were theoretically analyzed. The main results showed that the Mexican hat wavelet demonstrated significant advantages over the Morlet and Meyer wavelets for the characterization and analysis of the A-wave impulse noise. The results of this study provide useful information for applying wavelet transform on signal processing of the A-wave impulse noise.
    Źródło:
    Archives of Acoustics; 2015, 40, 4; 503-512
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of ADC Resolution on Low-Frequency Electrical Time-Domain Impedance Spectroscopy
    Autorzy:
    Namin, R. L.
    Ashtiani, S. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/221144.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    electrical impedance spectroscopy
    analogue-to-digital converter
    Ramp signal
    fast Fourier transform
    Nyquist plot
    Opis:
    In this paper, the effect of the resolution of an analogue-to-digital converter (ADC) on the accuracy of timedomain low-frequency electrical impedance spectroscopy is examined. For the first time, we demonstrated that different wideband stimuli signals used for impedance spectroscopy have different sensitivities to the resolution of ADC used in impedance spectroscopy systems. We also proposed Ramp and Half-Gaussian signals as new wideband stimulating signals for EIS. The effect of ADC resolution was studied for Sinc, Gaussian, Half-Gaussian, and Ramp excitation signals using both simulation and experiments. We found that Ramp and Half-Gaussian signals have the best performance, especially at low frequencies. Based on the results, a wideband electrical impedance spectroscopy circuit was implemented with a high accuracy at frequencies bellow 10 Hz.
    Źródło:
    Metrology and Measurement Systems; 2017, 24, 2; 425-436
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Frequency and time domain characteristics of digital control of electric vehicle in-wheel drives
    Autorzy:
    Jarzebowicz, L.
    Opalinski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/141142.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    variable speed drives
    modeling
    digital control events
    anti-lock braking
    inwheel drives
    Opis:
    In-wheel electric drives are promising as actuators in active safety systems of electric and hybrid vehicles. This new function requires dedicated control algorithms, making it essential to deliver models that reflect better the wheel-torque control dynamics of electric drives. The timing of digital control events, whose importance is stressed in current research, still lacks an analytical description allowing for modeling its influence on control system dynamics. In this paper, authors investigate and compare approaches to the analog and discrete analytical modeling of torque control loop in digitally controlled electric drive. Five different analytical models of stator current torque component control are compared to judge their accuracy in representing drive control dynamics related to the timing of digital control events. The Bode characteristics and stepresponse characteristics of the analytical models are then compared with those of a reference model for three commonly used cases of motor discrete control schemes. Finally, the applicability of the presented models is discussed.
    Źródło:
    Archives of Electrical Engineering; 2017, 66, 4; 829-842
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    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:
    Analysis of the electromagnetic response of complex dispersive material with the single-step wideband finite element method
    Autorzy:
    Butryło, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/141234.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    propagation of electromagnetic pulse
    dielectric dispersion
    frequency selective materials
    broadband time-domain simulation
    finite element time-domain method
    Opis:
    The paper describes the formulation and implementation of the broadband finite element time domain algorithm. The presented formalism is valid to analysis of electromagnetic phenomena in linear, frequency selective materials. The complex profile of permittivity of materials is approximated using a set of the Lorentz resonance models. The solution of the integro-differential second order equation is obtained using a singlestep integration scheme and a recursive convolution algorithm. The discussed formulation enables to adopt the structure of the narrowband part as well as the phase of calculation of the convolution equations for the subsequent components. The properties of the algorithm are validated using a finite difference broadband algorithm.
    Źródło:
    Archives of Electrical Engineering; 2013, 62, 1; 111-122
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Methods of DC/DC converter transfer function measurements, based on data acquired in the time domain
    Autorzy:
    Walczak, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/220796.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    DC–DC converters
    frequency characteristics
    transfer function measurement
    Opis:
    The measurement of frequency characteristics, like magnitude and phase, related to a specific transfer function of DC–DC converters, can be a difficult task - especially when the measured signal approaches the boundary of a small-signal model validity (i.e. 1/3 of the switching frequency fS ). It is hard to find a paper where authors mention the measurement techniques they use to draw frequency characteristics. Meanwhile the presence of noise in the output signal does not enable to directly measure the gain and the phase shift between the input and output signals. In such situations additional analysis is required in order to achieve a reliable result. This paper contains a description of a few methods that can be used to analyse measured signals in order to determine the gain and the phase shift of a specific transfer function. They enable to verify mathematical models in a wide range of frequencies (up to 1/3 fS ). The methods use signals measured in the time domain and can be implemented in mathematical software such as Matlab or Scilab.
    Źródło:
    Metrology and Measurement Systems; 2019, 26, 4; 661-671
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Time-domain Windowing on Isolated Speech Recognition System Performance
    Autorzy:
    Ananthakrishna, Thalengala
    Anitha, H.
    Girisha, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2055228.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hidden Markov model
    HMM
    isolated speech recognition system
    ISR
    Kannada language
    mono-phone model
    Mel frequency cepstral coefficients
    MFCC
    Opis:
    Speech recognition system extract the textual data from the speech signal. The research in speech recognition domain is challenging due to the large variabilities involved with the speech signal. Variety of signal processing and machine learning techniques have been explored to achieve better recognition accuracy. Speech is highly non-stationary in nature and therefore analysis is carried out by considering short time-domain window or frame. In the speech recognition task, cepstral (Mel frequency cepstral coefficients (MFCC)) features are commonly used and are extracted for short time-frame. The effectiveness of features depend upon duration of the time-window chosen. The present study is aimed at investigation of optimal time-window duration for extraction of cepstral features in the context of speech recognition task. A speaker independent speech recognition system for the Kannada language has been considered for the analysis. In the current work, speech utterances of Kannada news corpus recorded from different speakers have been used to create speech database. The hidden Markov tool kit (HTK) has been used to implement the speech recognition system. The MFCC along with their first and second derivative coefficients are considered as feature vectors. Pronunciation dictionary required for the study has been built manually for mono-phone system. Experiments have been carried out and results have been analyzed for different time-window lengths. The overlapping Hamming window has been considered in this study. The best average word recognition accuracy of 61.58% has been obtained for a window length of 110 msec duration. This recognition accuracy is comparable with the similar work found in literature. The experiments have shown that best word recognition performance can be achieved by tuning the window length to its optimum value.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 1; 161--166
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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