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    Wyświetlanie 1-8 z 8
    Tytuł:
    The 8AE-PD computer measurement system for registration and analysis of acoustic emission signals generated by partial discharges in oil power transformers
    Autorzy:
    Witos, Franciszek
    Opilski, Zbigniew
    Szerszeń, Grzegorz
    Setkiewicz, Maciej
    Powiązania:
    https://bibliotekanauki.pl/articles/220623.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    acoustic emission
    partial discharge
    multichannel system
    acoustic signal detection
    acoustic signal processing
    signal analysis
    voltage preamplifier
    Opis:
    A computer measurement system, designed and built by authors, dedicated to location and description of partial discharges (PD) in oil power transformers examined by means of the acoustic emission (AE) method is presented. The measurement system is equipped with 8 measurement channels and ensures: monitoring of signals, registration of data in real time within a band of 25-1000 kHz in laboratory and real conditions, basic and advanced analysis of recorded signals. The basic analysis carried out in the time, frequency and time-frequency domains deals with general properties of the AE signals coming from PDs. The advanced analysis, performed in the discrimination threshold domain, results in identification of signals coming from different acoustic sources as well as location of these sources in the examined transformers in terms of defined by authors descriptors and maps of these descriptors on the side walls of the tested transformer tank. Examples of typical results of laboratory tests carried out with the use of the built-in measurement system are presented.
    Źródło:
    Metrology and Measurement Systems; 2019, 26, 2; 403-418
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distant Measurement of Plethysmographic Signal in Various Lighting Conditions Using Configurable Frame-Rate Camera
    Autorzy:
    Przybyło, J.
    Kańtoch, E.
    Jabłoński, M.
    Augustyniak, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/221113.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    photoplethysmography
    remote patient monitoring
    heart rate detection
    video signal processing
    Opis:
    Videoplethysmography is currently recognized as a promising noninvasive heart rate measurement method advantageous for ubiquitous monitoring of humans in natural living conditions. Although the method is considered for application in several areas including telemedicine, sports and assisted living, its dependence on lighting conditions and camera performance is still not investigated enough. In this paper we report on research of various image acquisition aspects including the lighting spectrum, frame rate and compression. In the experimental part, we recorded five video sequences in various lighting conditions (fluorescent artificial light, dim daylight, infrared light, incandescent light bulb) using a programmable frame rate camera and a pulse oximeter as the reference. For a video sequence-based heart rate measurement we implemented a pulse detection algorithm based on the power spectral density, estimated using Welch’s technique. The results showed that lighting conditions and selected video camera settings including compression and the sampling frequency influence the heart rate detection accuracy. The average heart rate error also varies from 0.35 beats per minute (bpm) for fluorescent light to 6.6 bpm for dim daylight.
    Źródło:
    Metrology and Measurement Systems; 2016, 23, 4; 579-592
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-contact harmonic detection of ferromagnetic material defects based on SQGSR and OPLTF
    Autorzy:
    Zhao, Yizhen
    Wang, Xinhua
    Chen, Yingchun
    Ju, Haiyang
    Shuai, Yi
    Powiązania:
    https://bibliotekanauki.pl/articles/1848986.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    harmonic detection
    ferromagnetic materials defects
    focusing vector array
    signal extraction algorithm
    Opis:
    In order to find the defects in ferromagnetic materials, a non-contact harmonic detection method is proposed. According to the principle of frequency modulated carrier wave, a tunnel magneto resistance harmonic focusing vector array detector was designed which radiates lower and higher frequency electromagnetic waves through the coil array to the detection targets. We use bistable stochastic resonance to enhance the energy of collected weak target signal and apply quantum computation and a Sobol low deviation sequence to improve genetic algorithm performance. Then we use the orthogonal phase-locked loop to eliminate the intrinsic background excitation field and tensor calculations to fuse the vector array signal. The finite element model of array detector and the magnetic dipole harmonic numerical model were also established. The simulation results show that the target signal can be identified effectively, its focusing performance is improved by 2 times, and the average signal-to-noise ratio is improved by 9.6 times after the algorithm processing. For the experiments, we take Q235 steel pipeline as the object to realize the recognition of three defects. Compared with the traditional methods, the proposed method is more effective for ferromagnetic materials defects detection.
    Źródło:
    Metrology and Measurement Systems; 2021, 28, 1; 55-72
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Direct Comparison of Analogue and Digital FGPA-Based Approaches to Synchronous Detection
    Autorzy:
    Teren, O.
    Tomlain, J.
    Sedlacek, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/221544.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    synchronous detection
    lock-in amplifier
    digital signal processing
    FPGA
    measurement of impedance
    Opis:
    This paper deals with a comparison between digital and analogue implementation of a synchronous detection algorithm. The commonly used implementation methods of synchronous detection are presented in the paper. The paper describes FPGA-based digital and analogue hardware approaches, focusing on the digital design. The characteristics of used analogue-to-digital converters are measured. Both proposed approaches are directly compared in terms of sensitivity and long-term stability. The achieved results, along with identified limitations and proposed improvements are widely discussed.
    Źródło:
    Metrology and Measurement Systems; 2018, 25, 1; 57-69
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A novelty detection approach to monitoring of epicyclic gearbox health
    Autorzy:
    Dworakowski, Z.
    Dziedziech, K.
    Jabłoński, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/221834.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    epicyclic gearbox
    soft computing
    auto-associative neural network
    novelty detection
    vibration signal
    Opis:
    Reliable monitoring for detection of damage in epicyclic gearboxes is a serious concern for all industries in which these gearboxes operate in a harsh environment and in variable operational conditions. In this paper, autonomous multidimensional novelty detection algorithms are used to estimate the gearbox’ health state based on vectors of features calculated from the vibration signal. The authors examine various feature vectors, various sources of data and many different damage scenarios in order to compare novel detection algorithms based on three different principles of operation: a distance in the feature space, a probability distribution, and an ANN (artificial neural network)-based model reconstruction approach. In order to compensate for non-deterministic results of training of neural networks, which may lead to different network performance, the ensemble technique is used to combine responses from several networks. The methods are tested in a series of practical experiments involving implanting a damage in industrial epicyclic gearboxes, and acquisition of data at variable speed conditions.
    Źródło:
    Metrology and Measurement Systems; 2018, 25, 3; 459-473
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Single-channel EEG processing for sleep apnea detection and differentiation
    Autorzy:
    Prucnal, Monika A.
    Polak, Adam G.
    Powiązania:
    https://bibliotekanauki.pl/articles/27311744.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    single-channel EEG
    sleep apnea detection
    optimization of signal processing
    medical decision support
    Opis:
    Sleep apnea syndrome is a common sleep disorder. Detection of apnea and differentiation of its type: obstructive (OSA), central (CSA) or mixed is important in the context of treatment methods, however, it typically requires a great deal of technical and human resources. The aim of this research was to propose a quasi-optimal procedure for processing single-channel electroencephalograms (EEG) from overnight recordings, maximizing the accuracy of automatic apnea or hypopnea detection, as well as distinguishing between the OSA and CSA types. The proposed methodology consisted in processing the EEG signals divided into epochs, with the selection of the best methods at the stages of preprocessing, extraction and selection of features, and classification. Normal breathing was unmistakably distinguished from apnea by the k-nearest neighbors (kNN) and an artificial neural network (ANN), and with 99.98% accuracy by the support vector machine (SVM). The average accuracy of multinomial classification was: 82.29%, 83.26%, and 82.25% for the kNN, SVM and ANN, respectively. The sensitivity and precision of OSA and CSA detection ranged from 55 to 66%, and the misclassification cases concerned only the apnea type.
    Źródło:
    Metrology and Measurement Systems; 2023, 30, 2; 323--336
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Metal detector excited by frequency-swept signal
    Autorzy:
    Svatoš, J.
    Vedral, J.
    Fexa, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/221024.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    metal detection
    polyharmonic signals
    Frequency Sweep
    modelling of electromagnetic induction
    analog signal processing
    Opis:
    This paper describes the theoretical background of electromagnetic induction from metal objects modelling. The response function of a specific case of object shape - a homogenous sphere from ferromagnetic and nonferromagnetic material is introduced. Experimental data measured by a metal detector excited with a linearly frequency-swept signal are presented. As a testing target various spheres from different materials and sizes were used. These results should lead to better identification of the buried object.
    Źródło:
    Metrology and Measurement Systems; 2011, 18, 1; 57-67
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    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
      Wyświetlanie 1-8 z 8

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