An experimental study of Taylor’s hypothesis in a quasi-two-dimensional turbulent soap film is presented. A two-probe laser Doppler velocimeter enables a nonintrusive simultaneous measurement of the velocity at spatially separated points. Using the cross correlation between a pair of points displaced in both space and time, the velocity coherence is measured to be better than 90% for scales les...

Copyright© 2001 by Gharib, Modarress, Fourguette, and Wilson. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Abstract This manuscript describes two MEMS based optical sensors for wall shear stress and velocity measurements in flow fields. Experimental results obtained with the wall shear stress sensor, the MicroS3, are compared with boundary layer ve...

The reliability of quantitative evaluation by doppler ultrasound with regard to the ophthalmic collateral blood flow in patients with carotid artery occlusion was estimated. The ultrasonic doppler flow signals of the ophthalmic collateral flow of 54 carotid occlusions were classified into four types and three degrees--high, moderate, and low reversed flow patterns--and were compared with the an...

This paper describes the design and construction of two ultrasonic Doppler transducers using Finite Element Analysis for blood flow measurement. These transducers were constructed using as sensing element, commercial 8 MHz PIC255 piezoceramic discs, EPO-TEK 301 and Rexolite 4422 as backing and matching layer materials respectively. The objective of this work was to design and construct two sing...

An experimental study of Taylor’s hypothesis in a quasi-two-dimensional turbulent soap film is presented. A two probe laser Doppler velocimeter enables a non-intrusive simultaneous measurement of the velocity at spatially separated points. The breakdown of Taylor’s hypothesis is quantified using the cross correlation between two points displaced in both space and time; correlation is better tha...

A physical model of gabion overflow dams was studied to determine the velocity profile and Reynolds shear stress. Physical tests were done under two different conditions of dam crest, overflow dams with impermeable and with permeable crests. Instantaneous velocity components over dam crest were measured by an ADV (Acoustic Doppler Velocimeter) instrument. This instrument is capable of measuring...

Synthetic pyrethroids are neurotoxic insecticides with a low mammalian toxicity. Prior investigations have found these agents to be neither cutaneous irritants nor sensitisers. Clinically demonstrable inflammation, as judged by erythema, oedema, or vesiculation, has not been apparent. Nevertheless, paraesthesia does result from cutaneous exposure. In this investigation technical grade flucythri...

An apparatus is described by means of which the power versus frequency spectrum of the photomultiplier current can be obtained for laser light scattered by streaming cytoplasm in the algal cell Chara corallina. A Doppler peak is noted in the spectrum which is abolished when cytoplasmic streaming is arrested by electrical stimulation. For 5 cells of Chara, this simple laser-Doppler velocimeter g...