Results 261 to 270 of about 488,726 (317)

Decorrelation-based blood flow velocity estimation: effect of spread of flow velocity, linear flow velocity gradients, and parabolic flow

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2002
In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been developed. In this paper, we investigated the influence of nonuniform flow on the velocity estimation. The decorrelation characteristics of transverse blood flow using an intravascular ultrasound (IVUS) array catheter ...
Lupotti, F.A., Steen, A.F.W. van der, Mastik, F., Korte, C.L. de   +3 more
openaire   +4 more sources

A flow-sensing velocity microphone

2019 IEEE SENSORS, 2019
A microphone is described having a sensing element driven by viscous forces due to the fluctuating velocity of the air in a sound field. Unlike typical microphones having pressure-sensing diaphragm, thin microfabricated beams or thin porous plates are used to detect acoustic flow.
Ronald N. Miles, Mahdi Farahikia, Stephane Leahy, Ahmed Abdel Aziz   +3 more
openaire   +1 more source

Velocity distribution in aortic flow

Cardiovascular Research, 1973
Velocity measurements in the dog aorta using a thin film anemometer are described. The instantaneous velocity profiles for the ascending and descending aorta indicate a large inertial core region with relatively thin boundary layers; pronounced non-uniformities are present in the ascending aorta.
C, Clark, D L, Schultz
openaire   +2 more sources

``Brillouin Flow'' with Thermal Velocities

Journal of Applied Physics, 1953
A type of electron flow in a constant magnetic field is described. The beam of electrons is supposed to be everywhere in thermal equilibrium and the usual Brillouin flow is found when the equilibrium temperature tends to zero. Some considerations are put forward bearing on the choice of a suitable beam temperature in specific problems.
Pierce, J. R., Walker, L. R.
openaire   +2 more sources

Correlation-based blood-flow velocity estimation: effect of transverse spread of flow velocity and flow velocity gradients

2000 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.00CH37121), 2002
In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been introduced. We investigated the decorrelation characteristics of transverse blood flow using an intravascular ultrasound (IVUS) array catheter by means of computer modeling.
F.A. Lupotti, A.F.W. van der Steen
openaire   +1 more source

Computing the velocity of a rotating flow

Parallel Computing, 1998
Abstract To compute the time-dependent flow of a rotating incompressible fluid we consider the velocity–vorticity formulation of the Navier–Stokes equations in cylindrical coordinates. In the numerical method employed the velocity field at each time-step is found as the least squares solution of an overdetermined system of linear equations, Ax=b.
openaire   +1 more source

Slip velocity and velocity inversion in a cylindrical Couette flow

Physical Review E, 2009
Velocity inversion in a nanoscale cylindrical Couette flow is investigated with the Navier-Stokes (NS) equation and molecular-dynamics (MD) simulation. With general slip boundary conditions in the NS equation, the flow can be classified into five distinct profiles. The condition of velocity inversion is explored in the whole space of four dimensionless
openaire   +2 more sources

Flow Velocities in Pipelines

Journal of Hydraulic Engineering, 1983
Most of the equations that have been developed for relating velocity of a stream in a partly filled pipe to the slope and size of the stream use hydraulic radius (R) as the parameter for size. The equations using this parameter are poor representations of flow behavior when comparing different relative depths of flow, as Camp pointed out for the case ...
openaire   +1 more source

Selection of velocity profile and flow depth in granular flows

Physical Review E, 2001
The dynamics of a two-dimensional pile constituted by spherical grains organized in parallel layers is investigated theoretically. Only three effects are taken into account in the model: driving by gravity, nonlocal dissipation due to shocks, and trapping of grains by the bumps of the underneath layer. This is sufficient to recover the basic properties
B, Andreotti, S, Douady
openaire   +2 more sources

Flow Velocity

Abstract This chapter reviews basic concepts in fluid dynamics that are useful to the practice of anesthesiology. Laminar flow occurs when fluids flow in an orderly fashion without mixing. Turbulent flow involves mixing within the fluid and creates additional resistance to flow. The Reynolds number equation describes factors that promote
openaire   +1 more source