The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Christian Pedersen - One of the best experts on this subject based on the ideXlab platform.
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all semiconductor Laser Doppler Anemometer at 1 55 microm
Optics Express, 2008Co-Authors: Rene Skov Hansen, Christian PedersenAbstract:We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw Laser Doppler Anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the Laser source can be accomplished by an all semiconductor Laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.
N Paone - One of the best experts on this subject based on the ideXlab platform.
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estimating mechanical blood trauma in a centrifugal blood pump Laser Doppler Anemometer measurements of the mean velocity field
Artificial Organs, 1996Co-Authors: Marcos Pinotti, N PaoneAbstract:: A Laser Doppler Anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.
Rene Skov Hansen - One of the best experts on this subject based on the ideXlab platform.
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all semiconductor Laser Doppler Anemometer at 1 55 microm
Optics Express, 2008Co-Authors: Rene Skov Hansen, Christian PedersenAbstract:We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw Laser Doppler Anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the Laser source can be accomplished by an all semiconductor Laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.
V J Modi - One of the best experts on this subject based on the ideXlab platform.
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unsteady fluid dynamics of several mechanical prosthetic heart valves using a two component Laser Doppler Anemometer system
Artificial Organs, 2008Co-Authors: Toshinosuke Akutsu, V J ModiAbstract:: Five typical mechanical heart valves (Starr-Edwards, Bjork-Shiley convexo-concave (c-c), Bjork-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component Laser Doppler Anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level.
Marcos Pinotti - One of the best experts on this subject based on the ideXlab platform.
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critical flow regions in tissue artificial heart valve assessed by Laser Doppler Anemometer in continuous flow
Journal of The Brazilian Society of Mechanical Sciences and Engineering, 2006Co-Authors: Marcos Pinotti, Edna M De FariaAbstract:Flow diagnosis using non-invasive techniques such Laser Doppler Anemometer (LDA) is an important tool to improve the design of artificial heart valves. In the present study, an experimental protocol to obtain flow velocity field and colour coded maps of turbulent eddies dimensions using LDA measurements in a 25 mm bovine pericardium bio prosthesis valve is reported. A transparent Plexiglas chamber was specially designed to allow optical access to the flow passing through the valve. Experiments were conducted for non-pulsate flow (to study the valve performance in the peak flow) for the aorta Reynolds number ranging from 3300 to 6800. LDA interrogation volume visited five thousand and one hundred points along the flow (2500 points upstream and 2600 points downstream) for each Reynolds number. Post-processing methodology was employed to obtain haemolytic potential colour-coded maps, which were related to turbulent quantities. It was observed that haemolytic regions tend to move downstream the valve when the flow rate is increased.
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estimating mechanical blood trauma in a centrifugal blood pump Laser Doppler Anemometer measurements of the mean velocity field
Artificial Organs, 1996Co-Authors: Marcos Pinotti, N PaoneAbstract:: A Laser Doppler Anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.
