نتایج جستجو برای: spectral doppler
تعداد نتایج: 208190 فیلتر نتایج به سال:
The concept of cepstrum thresholding (CT) is applied to estimate smoothed nonparametric spectrum. The CT method is applied to Mesosphere, Stratosphere and Troposphere (MST) radar data for spectral cleaning. This method is not superior as compared with the conventional Periodogram method. So, to enhance the spectral visibility in Doppler Profile (DP), the CT technique is modified. The modified c...
We present an application of the Joint Spectral and Time domain OCT (STdOCT) method for detection of wide range of flows in the retinal vessels. We utilized spectral/Fourier domain OCT (SOCT) technique for development of scan protocols for Doppler signal analysis. We performed retinal imaging in normal eyes using ultrahigh speed (200 000 axial scans/s) SOCT instrument with a CMOS camera. Variou...
Doppler color flow imaging is a method for noninvasively imaging blood flow through the heart by displaying flow data on the two-dimensional echocardiographic image. This capability has generated great excitement about the use of the technique for identifying valvular, congenital, and other forms of heart disease, as the color flow image imparts spatial information to the Doppler data. To inexp...
In recent years, the use of Doppler ultrasound sonography for the diagnosis of atherosclerosis has increased. However, parameters provided by the commercially available Doppler ultrasound units are inadequate to compete with the gold standard method, catheter angiography. Therefore, developing a new method based on Doppler ultrasound sonography remains a hot topic among researchers. In this stu...
The radar Doppler spectrum contains a wealth of information on cloud microphysical properties. Typically, radar-based cloud retrievals use only the zeroth or first moments of the Doppler spectrum – reflectivity and mean Doppler velocity – to derive quantities such as cloud water content and particle characteristic size (e.g., Liou and Sassen 1994; Matrosov et al. 2002). When using only the mome...
OBJECTIVES Our purpose was to investigate cervical lymphadenopathies by using color Doppler spectral analysis and power Doppler ultrasonography methods as well as B-mode ultrasound and to classify them as malignant or benign lesions and to compare the results with the histopathological findings. PATIENTS AND METHODS Sixty-nine lymph nodes of 69 patients were evaluated with color and power Dop...
In this study, short-time Fourier transform (STFT) and wavelet transform (WT) were used for spectral analysis of ophthalmic arterial Doppler signals. Using these spectral analysis methods, the variations in the shape of the Doppler spectra as a function of time were presented in the form of sonograms in order to obtain medical information. These sonograms were then used to compare the applied m...
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