Doppler devices

Flowmeters These are used to measure flocculant addition, underflow, and feed flow rates. For automatic control, the more commonly used devices are magnetic flowmeters and Doppler effect flowmeters. 

Mossbauer resonance of Zn to study the influence of the gravitational field on electromagnetic radiation. A Ga ZnO source (4.2 K) was used at a distance of 1 m from an enriched ZnO absorber (4.2 K). A red shift of the photons by about 5% of the width of the resonance line was observed. The corresponding shift with Fe as Mossbauer isotope would be only 0.01%. The result is in accordance with Einstein s equivalence principle. Further gravitational red shift experiments using the 93.3 keV Mossbauer resonance of Zn were performed later employing a superconducting quantum interference device-based displacement sensor to detect the tiny Doppler motion of the source [66, 67]. 

By recording the raw Doppler signal on an oscillograph, drum camera, or similar device, it is possible to obtain projectile displacementtime information Photographic Methods... 

So far, a modulator device has been described, not a filter. This can be used on a monochromatic (for example laser) input beam to vary the Doppler-shifted frequency or direction or intensity of an output beam as a function of input RF frequency and power. In order to understand how an AOTF device goes further than this, it is necessary to look at the effect of Bragg regime diffraction and the impact of the anisotropy of the AOTF crystal medium. 

Devices such as ultrasonic flow equipment use the Doppler frequency shift of ultrasonic signals reflected from discontinuities in the fluid stream to obtain flow measurements. These discontinuities can be suspended solids, bubbles, or interfaces generated by turbulent eddies in the flow stream. The sensor is mounted on the outside of the pipe, and an ultrasonic beam from a piezoelectric crystal is transmitted through the pipe wall into the fluid at an angle to the flow stream. Signals reflected off flow disturbances are detected by a second piezoelectric crystal located in the same sensor. Transmitted and reflected signals are compared in an electrical circuit, and the corresponding frequency shift is proportional to the flow velocity. 

Vos JA, van den BergJC, Ernst SM, et al. Carotid angioplasty and stent placement comparison of transcranial Doppler US data and clinical outcome with and without filtering cerebral protection devices in 509 patients. Radiology 2005 234 493 -99,... 

There is a need to distinguish at this point how the shear rate in the impeller zone differs from the shear rate in the tank zone. To do this, however, one must carefully define shear rate and the corresponding concepts of macroscale shear rate and microscale shear rate. When one studies the localized fluid velocity through utilization of a small dimension probe, or as is currently used, a laser Doppler velocity meter device, one sees that at any point in the... 

The methods of wind velocity measurement include (a) Pitot, (b) vane, (c) cup, (d) propeller or turbine, (e) thermal, (f) Doppler, (g) acoustic, and (h) laser-type designs. These devices can detect velocities in nautical miles per hour units (1.85 km/h = 101 fpm) or in knots up to 600 knots (60,000 fpm) at the following elevations designs a, b, and c—tower height f—60-600 m thickness at up to 1,500 m. 

It is worth noting that, due to the rather high viscosity and low permittivity of the suspending fluids used in electrorheology, the electrophoretic mobility is much smaller than in an aqueous medium (typical values in aqueous media are I //m/s for I V/cm, and we have almost three orders of magnitude less). In this case our tracking system is more efficient and far less expensive than conventional devices based on Doppler velocimetry. 

Many industries regularly conduct repeat insult patch tests on human volunteers to evaluate topical irritancy. Groups of human volunteers are patched with test substance. One to five concentrations can be tested simultaneously, a wide enough range to yield results relevant to the usage. Cumulative skin irritancy is measured by applying patch applications each day for 3 weeks. Skin irritation is usually assessed visually, but blood flow and skin temperature can be measured objectively by laser Doppler flowmetry, ultrasound Doppler, heat flow disk measurement, sensitive thermocouple devices, or noncontact infrared radiative techniques. In these tests, dose-response curves can be obtained. Skin thickness can be measured with calipers as a measure of edema formation. 

For particle sizing, many varieties of cascade imp-actors perform well, although care must be taken to avoid errors introduced by sampling (such as collection in sampling lines). The laser/Doppler-type particle-size device can be used to measure aerodynamic size and low concentrations with a rapid readout. In a system described by Cook, a powerful pulsed laser using temporal analysis of back-scattered light can be used to measure the spatial distribution of particles. 

The Malvern API Aerosizer (Malvern Instruments Ltd., Southborough, MA) operates on the principle of supersonic flow in a jet, followed by laser Doppler velocimetry to measure the aerodynamic diameter of particles in the size range from 0.5 to 200 pm using 50 channels. The operating flowrate is 6 L/min. The Atcor Net-2000 is a similar device for determining aerodynamic diameter, except that it is capable of sizing particles up to only 5.0 pm in diameter at a flowrate of 0.1 ft3/min (2.83 L/min). 

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