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Wyszukujesz frazę "continuous wave" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Analysis for Improvement of Doppler Tomography Imaging of Objects Scattering Continuous Ultrasonic Waves
Autorzy:
Świetlik, Tomasz
Opieliński, Krzysztof J.
Powiązania:
https://bibliotekanauki.pl/articles/176449.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
continuous wave ultrasonic tomography
Doppler tomography
image reconstruction
Opis:
The paper describes an innovative ultrasound imaging method called Doppler Tomography (DT), otherwise known as Continuous Wave Ultrasonic Tomography (CWUT). Thanks to this method, it is possible to image the tissue cross-section in vivo using a simple two-transducer ultrasonic probe and using the Doppler effect. It should be noted that DT significantly differs from the conventional ultrasound Doppler method of measuring blood flow velocity. The main difference is that when measuring blood flow, we receive information with an image of the velocity distribution in a given blood vessel (Nowicki, 1995), while DT allows us to obtain a cross-sectional image of stationary tissue structure. In the conventional method, the probe remains stationary, while in the DT method, the probe moves and the examined tissue remains stationary. This paper presents a method of image reconstruction using the DT method. First, the basic principle of correlation of generated Doppler frequencies with the location of inclusions from which they originate is explained. Then the exact process and algorithm in this method are presented. Finally, the impact of several key parameters on imaging quality is examined. As a result, the conclusions of the research allow to improve the image reconstruction process using the DT method.
Źródło:
Archives of Acoustics; 2020, 45, 2; 329-339
0137-5075
Pojawia się w:
Archives of Acoustics
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
    Wyświetlanie 1-2 z 2

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