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    Wyświetlanie 1-5 z 5
    Tytuł:
    Tissue Attenuation Estimation from Backscattered Ultrasound Using Spatial Compounding Technique - Preliminary Results
    Autorzy:
    Klimonda, Z.
    Litniewski, J.
    Nowicki, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/177842.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ultrasound attenuation estimation
    spatial compounding
    parametric imaging
    Opis:
    The pathological states of biological tissue are often resulted in attenuation changes. Thus, information about attenuating properties of tissue is valuable for the physician and could be useful in ultrasonic diagnosis. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion, is presented. The Doppler IQ technique was adopted to estimate the mean frequency directly from the raw RF data. The Singular Spectrum Analysis technique was used for the extraction of mean frequency trends. These trends were converted into attenuation distribution and finally the parametric images were computed. In order to reduce variation of attenuation estimates the spatial compounding method was applied. Operation and accuracy of attenuation extracting procedure was verified by calculating the attenuation coefficient distribution using the data from the tissue phantom (DFS, Denmark) with uniform echogenicity while attenuation coefficient underwent variation.
    Źródło:
    Archives of Acoustics; 2010, 35, 4; 643-651
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Circular Radon Transform Inversion Technique in Synthetic Aperture Ultrasound Imaging : an Ultrasound Phantom Evaluation
    Autorzy:
    Tasinkevych, J.
    Trots, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/176632.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    synthetic aperture focusing method
    circular Radon Transform
    delay and sum beamforming
    range migration algorithm
    Opis:
    The paper presents an overview of theoretical aspects of ultrasound image reconstruction techniques based on the circular Radon transform inversion. Their potential application in ultrasonography in a similar way as it was successfully done in the x-ray computer tomography is demonstrated. The meth- ods employing Radon transform were previously extensively explored in the synthetic aperture radars, geophysics, and medical imaging using x-ray computer tomography. In this paper the main attention is paid to the ultrasound imaging employing monostatic transmit-receive configuration. Specifically, a single transmit and receive omnidirectional source placed at the same spatial location is used for generation of a wide-band ultrasound pulse and detection of back-scattered waves. The paper presents derivation of the closed-form solution of the CRT inversion algorithms by two different approaches: the range-migration algorithm (RMA) and the deconvolution algorithm (DA). Experimentally determined data of ultrasound phantom obtained using a 32-element 5 MHz linear transducer array with 0.48 mm element pitch and 0.36 mm element width and 5 mm height, excited by a 2 sine cycles burst pulse are used for comparison of images reconstructed by the RMA, DA, and conventional synthetic aperture focusing technique (SAFT). It is demonstrated that both the RMA and SAFT allow better lateral resolution and visualization depth to be achieved as compared to the DA approach. Comparison of the results obtained by the RMA method and the SAFT indicates slight improvement of the lateral resolution for the SAFT of approximately 1.5 and 1.6% at the depth of 12 and 32 mm, respectively. Concurrently, however, the visualization depth increase for the RMA is shown in comparison with the SAFT. Specifically, the scattered echo amplitude increase by the factor of 1.36 and 1.12 at the depth of 22 and 32 mm is demonstrated. It is also shown that the RMA runs about 30% faster than the SAFT and about 12% faster than the DA method.
    Źródło:
    Archives of Acoustics; 2014, 39, 4; 569-582
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Technique for Measuring Spatial Distribution of the Surface Acoustic Wave Velocity in Metals
    Autorzy:
    Mokryy, O.
    Tsyrulnyk, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/177231.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ultrasound
    surface acoustic waves
    acoustic wave velocity
    spatial resolution
    Opis:
    In this paper a possibility of determining a local velocity of the surface acoustic Rayleigh waves using a transducer, with the rigidly connected emitting and receiving parts, is considered. A problem on spatial resolution of such a transducer for investigation of inhomogeneous specimens is also examined. A high spatial resolution can be obtained due to the transducer displacement by a value less than the distance between the emitting and receiving parts. It is shown that in this case it is not necessary to measure the transducer displacement with a high accuracy for precise determination of the velocity. Such an effect is obtained through measuring the velocity of surface waves in one local region of the specimen with respect to the other. The criterion for optimal spatial resolution selection during spatially inhomogeneous specimens study is also proposed. The proposed criterion use is illustrated on the example of the determination of spatial distribution of the surface acoustic velocity in a steel specimen subjected to inhomogeneous plastic deformation.
    Źródło:
    Archives of Acoustics; 2016, 41, 4; 741-746
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Tinnitus Therapy Based on High-Frequency Linearization Principles - Preliminary Results
    Autorzy:
    Poremski, T.
    Kostek, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/177726.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    tinnitus
    sensorineural hearing loss
    tinnitus masking
    Tinnitus Retraining Therapy (TRT)
    signal quantization
    dithering technique
    high-frequency linearization
    ultrasound dither noise
    Opis:
    The aim of this work is to present problems related to tinnitus symptoms, its pathogenesis, hypothe- ses on tinnitus causes, and therapy treatment to reduce or mask the phantom noise. In addition, the hypothesis on the existence of parasitic quantization that accompanies hearing loss has been recalled. Moreover, the paper describes a study carried out by the Authors with the application of high-frequency dither having specially formed spectral characteristics. Discussion on preliminary results obtained and conclusions are also contained.
    Źródło:
    Archives of Acoustics; 2012, 37, 2; 161-170
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Variation of Precipitated Phase Investigated with the Usage of Nonlinear Ultrasonic Technique
    Autorzy:
    You, Jun
    Wu, Yunxin
    Gong, Hai
    Powiązania:
    https://bibliotekanauki.pl/articles/2097705.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    nonlinear ultrasound
    Al-Cu precipitation
    2219-T6 aluminum alloy
    precipitates phase
    Opis:
    It is well known that nonlinear ultrasound is sensitive to some microstructural characteristics in material. This paper investigates the dependence of the nonlinear ultrasonic characteristic on Al-Cu precipitation in heat-treated 2219-T6 aluminum alloy specimens. The specimens were heat-treated at a constant temperature 155℃ for different exposure times up to 1800 min. The nonlinearity parameter and the changes of precipitates phase were measured for each of the artificially aged specimens. The experimental results show fluctuations in the fractional change in nonlinear parameter (Δβ/β0) and the changes of precipitated phase over the aging time, but with an interesting correlation between the fractional change in nonlinear parameter (Δβ/β0) and the change of precipitate phase over the aging time. Through the experimental data results, the fractional change in nonlinear parameter (Δβ/β0) and the change of precipitate phase over the aging time were fitted curve. Microstructural observations confirmed that those fluctuations are due to the formation and evolution of precipitates that occur in a unique precipitation sequence in this alloy. These results suggest that the nonlinear ultrasonic measurement can be useful for monitoring second phase precipitation in the 2219-T6 aluminum alloy.
    Źródło:
    Archives of Acoustics; 2021, 46, 4; 605-610
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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