نتایج جستجو برای: spectral doppler
تعداد نتایج: 208190 فیلتر نتایج به سال:
This paper presents a new implementation of an formance, relative to the FM Doppler system reported echo-ranging FM Doppler system with improved perpreviously. The use of long sweeps provides a significant reduction in peak to average power ratio compared to pulsed wave (PW) emission. A PW Doppler system exploits the direct relationship between arrival time of the received signal and range from...
Spotlight SAR interferometry is an attractive option for high resolution mapping and monitoring. In this paper, the signal spectral characteristics and the interfeometric properties of spaceborne spotlight SAR are analyzed completely, and the effect of the azimuthvariant Doppler to spotlight SAR interferometry is studied. Moreover, a new coregistration algorithm, which contains coarse coregistr...
An abnormal level of red blood cell (RBC) aggregation is a clinical condition associated with many pathologies. Our purpose is to investigate the feasibility of spectral domain phase-resolved optical Doppler tomography incorporated with Doppler variance imaging to characterize RBC aggregation in flowing blood. Variance/standard deviation (SD) of the Doppler frequency spectrum of porcine blood f...
The duplex ultrasonic scanner combines real-time B-mode imaging with a single-gate, variable-range pulsed Doppler. The detection and categorization of the severity of carotid artery atherosclerosis is achieved by performing spectral analysis of the pulsed Doppler velocity signal obtained from vessels of interest. Using this technique, 750 patients with suspected extracranial carotid artery dise...
We have recently obtained the first simultaneous 2-d plasma Doppler spectroscopic images of plasma brightness, temperature and flow fields. Using compact polarization optical methods, quadrature images of the optical coherence of an isolated spectral line are multiplexed to four quadrants of a fast CCD camera. The simultaneously captured, but distinct images can be simply processed to unfold th...
BACKGROUND The aim of this study was to assess differences in intrarenal artery Doppler parameters measured without and with Doppler angle correction. METHODS We retrospectively reviewed color duplex sonography in 30 normally functioning kidneys (20 native kidneys in 10 subjects and 10 transplanted kidneys in 10 subjects) performed between January 26, 2010 and July 26, 2010. There were 10 age...
Skin vasomotion is the rhythmic variation of the skin microvessel diameter, responsible for the skin microcirculatory blood flow oscillation, the so called skin blood flowmotion. Experimental and clinical findings suggest that vasomotion depends on several mechanisms, such as the endothelial activity, the spontaneous myogenic activity of the microvascular wall and the sympathetic activity. Skin...
Image formation from squinted sliding spotlight synthetic aperture radar (SAR) is limited by azimuth spectral folding and severe two dimension coupling. This paper presents an Extended Wavenumber Domain Algorithm (WDA) for highly squinted sliding spotlight SAR data processing. This algorithm adopts azimuth deramping approach to overcome the azimuth spectral folding phenomenon. The chirp rate fo...
In many countries wind turbines are rapidly growing in numbers as the demand for energy from renewable sources increases. The continued deployment of wind turbines can, however, be problematic for many radar systems, which are easily disturbed by turbines located in the radar line of sight. Wind turbines situated in the vicinity of Doppler weather radars can lead to erroneous precipitation esti...
Ultrasound analysis plays an important role in the assessment of morphology of different forms of cancerous lesions. However, owing to the large number of false positive results, the accuracy of the technique has been largely restrictive in nature. Pulsed Doppler spectral analysis and color Doppler imaging enable the evaluation of blood vessel distribution, tumor blood flow, and quantitative me...
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