In this paper we present a detailed simulation method to estimate the accuracy of Doppler power spectrum and mean blood velocity, using real CW Doppler transducers with twin-crystal arrangement. The method is based on dividing the sample volume into small cells using the statistics of the total power of Doppler spectrum with the same Doppler shift frequency, and from total power, which predicts...

BACKGROUND Diabetes affects the vascular ocular circulation. Colour Doppler imaging allows for simultaneous two dimensional anatomical imaging and Doppler evaluation of blood flow velocity; with this technique ocular blood flow velocity can be evaluated in normal and diabetic patients. METHODS A prospective study compared blood flow velocity in ocular vessels (ophthalmic artery, posterior cil...

BACKGROUND AND PURPOSE Many patient monitoring techniques have been used for detecting cerebral hypoperfusion during carotid endarterectomy. We compared middle cerebral artery blood flow velocities with carotid artery stump pressures to evaluate the indications for common carotid artery cross-clamp shunting and the probable hemodynamic causes of cerebrovascular complications. METHODS Blood fl...

This paper investigates the parametric excitation of a micro-pipe conveying fluid suspended between two symmetric electrodes. Electrostatically actuated micro-pipes may become unstable when the exciting voltage is greater than the pull-in value. It is demonstrated that the parametric excitation of a micro-pipe by periodic (ac) voltages may have a stabilizing effect and permit an increase of the...