Acoustic Doppler velocimetry ( ADV ) is designed to record instantaneous velocity components at a single point with a relatively high frequency.

* Acoustic Doppler velocimetry

* Acoustic Particle-Image Velocimetry — Development and Applications

The Fletcher – Munson curves are one of many sets of equal-loudness contours for the human ear, determined experimentally by Harvey Fletcher and Wilden A. Munson, and reported in a 1933 paper entitled " Loudness, its definition, measurement and calculation " in the Journal of the Acoustic Society of America.

Laser Doppler Velocimetry predates PIV as a laser-digital analysis system to become widespread for research and industrial use.

The instrument was soon called the Laser Doppler Velocimeter ( LDV ) and the technique Laser Doppler Velocimetry, also abbreviated LDV.

The Doppler effect, using ultrasonic signals, can be employed to measure the flow of blood without cutting into the blood vessel.

Doppler effect of water flow around a swan

Ultrasonography and Doppler sonography provide useful means to detect appendicitis, especially in children, and shows free fluid collection in the right iliac fossa, along with a visible appendix without blood flow in color Doppler.

This may reveal the size and shape of the abdominal organs, and Doppler studies may show the direction of flow in the portal vein, as well as detecting Budd-Chiari syndrome and portal vein thrombosis.

The cross-sectional area of the flow is calculated from a depth measurement and the average velocity of the flow is measured directly ( Doppler and propeller methods are common ).

For the Doppler principle to work in a flowmeter it is mandatory that the flow stream contains sonically reflective materials, such as solid particles or entrained air bubbles.

Voxels can contain multiple scalar values-essentially vector data ; in the case of ultrasound scans with B-mode and Doppler data, density, and volumetric flow rate are captured as separate channels of data relating to the same voxel positions.

* Transcranial Doppler, a test that measures the velocity of blood flow through the brain's blood vessels

Doppler capabilities on modern scanners allow the blood flow in arteries and veins to be assessed.

But due to the unavailability of Doppler ultrasound imaging technology ( the diagnostic tool detecting abnormal blood flow in the veins, " Venous Reflux ", the pathological basis for varicose veins ) at that time, Ekbom may have underestimated the role of venous disease.

This Doppler shift can then be used to calculate flow velocity and volume and effectively Q using the following equations:

2D measurement of the diameter ( d ) of the aortic annulus allows calculation of the flow CSA ( cross-sectional area ) which is then multiplied by the vti of the Doppler flow profile across the aortic valve to determine the flow volume or SV.

The Ultrasonic Cardiac Output Monitor ( USCOM ) ( Uscom Ltd, Sydney, Australia ) uses Continuous Wave Doppler ( CW ) to measure the Doppler flow profile vti, as in echocardiography, but uses anthropometry to calculate aortic and pulmonary valve diameters and CSA's allowing both right and left sided Q measurements.

Real time Automatic tracing of the Doppler flow profile allows for beat to beat right and left sided Q measurements significantly simplifying operation and reducing the time of acquisition compared with the conventional echocardiographic method.

A non-invasive Doppler can also be used to measure blood flow at any point in the circulation, including within the heart, the CO, and can be converted to a pressure difference using the modified Bernoulli equation, ΔP = 4V2.

* Tracing the Doppler pulse of the blood flow of the supraorbital artery as far as possible, its delineation is continued as a vertical line, until it intersects with the hairline of the patient.

Duodenography and colonography are performed like a standard abdominal examination using B-mode and color flow Doppler ultrasonography using a low frequency transducer — for example a 2. 5 MHz — and a high frequency transducer, for example a 7. 5 MHz probe.

Color flow Doppler sonography is used to examine the localization of lesions in relation to vessels.

* In planar Doppler velocimetry ( optical flow meter measurement ), TOF measurements are made perpendicular to the flow by timing when individual particles cross two or more locations along the flow ( collinear measurements would require generally high flow velocities and extremely narrow-band optical filters ).

The present day measurement of knots and log are determined using a mechanical tow, electronic tow, hull-mounted units ( which may or may not be retractable ), Doppler ( either ultrasonic or radar ), or GPS.

Doppler measurement is reliable only if the sampling rate exceeds the Nyquist frequency for the frequency shift produced by radial motion.

For velocity measurement, Professor Wolman of Dresden created an alternative of his Doppler tracking system in 1940 – 41, which used a ground signal transponded by the A-4 to measure the velocity of the missile.

While direct measurement of the most violent tornado wind speeds is nearly impossible, since conventional anemometers would be destroyed by the intense winds, some tornadoes have been scanned by mobile Doppler radar units, which can provide a good estimate of the tornado's winds.

* The old record was a 257-268 mph wind measurement from a Doppler weather radar near Red Rock, Oklahoma, as reported in a formal publication by Bluestein et al.

The common characteristic to these is that a measurement of angular motion is combined with a measurement of the absolute velocity ( usually obtained via the Doppler effect ).

These include laser catheters, stent catheters, IVUS catheters, Doppler catheter, pressure or temperature measurement catheter and various clot and grinding or removal devices.

Doppler radar measurement results for a lathe-turned monolithic solid. 50 BMG very-low-drag bullet ( Lost River J40. 510-773 grain monolithic solid bullet / twist rate 1: 15 in ) look like this:

The most common test used for the evaluation of the severity of aortic insufficiency is transthoracic echocardiography, which can provide two-dimensional views of the regurgitant jet, allow measurement of velocity using Doppler, and estimate jet volume.

TRIUMF's Doppler Shift Lifetimes facility, which is an experimental setup for the measurement of the lifetimes of excited states of nuclei.

It was soon shown fluid flow measurement could be made from the Doppler effect on a He-Ne beam scattered by very small polystyrene spheres entrained in the fluid.

Particles passing through this volume will scatter light from the measurement beam with a Doppler shift ; a portion of this light is collected by the receiving optics and transferred to the photodetector.

Laser Doppler velocimetry is often chosen over other forms of flow measurement because the equipment can be outside of the flow being measured and therefore has no effect on the flow.

The laser Doppler vibrometer is being used in clinical otology for the measurement of tympanic membrane ( eardrum ), malleus ( hammer ), and prosthesis head displacement in response to sound inputs of 80-to 100-dB sound-pressure level.

This combined with the fact that it is coherent means that Fourier interrogated can be used rather than azimuth integrated providing superior signal to noise and a Doppler measurement.

For point measurements like laser Doppler velocimetry, particles in the nanometre diameter range, such as those in cigarette smoke, are sufficient to perform a measurement.

Today, the most accurate means of maritime speed measurement comes from Doppler measurement, either derived acoustically by use of Doppler Sonar or radio interferometrically by Doppler measurement of satellite signals such as those from Global Positioning System ( GPS ).