Background The proximal flow convergence method, a quantitative color Doppler flow technique, has been validated recently for calculating regurgitant flow and orifice area. We investigated the potential of the method as a tool to study different pathophysiological mechanisms of mitral valve incompetence by assessing the time course of regurgitant flow and orifice area and analyzed the implicati...

The main objective of this work is to examine the impac.1 of jet interactions in arrays of micropropulsion devices on thrust performance. Rarefied flow of nitrogen and helium from a single orifice and orifice arrays into vacuum was studied experimentally and numerically. The chamber pressure was changed in the range from 10 milli-torr to 40 torr, the orifice diameter was 1 mm, and the center-to...

Measurement of permeability of cigarette envelope papers used in Low Ignition Propensity (LIP) cigarettes presents a number of practical problems:  Measurements must be made on both the conventional and low permeability band regions.  The low permeability band must be measured using a small orifice (15 x 2 mm compared to the normal 20 x 10 mm) with a flow as low as 1 ml/minute.  Leakage from...

Objectives. In this study we Investigated the centerline velocity profile method for low computation applied to noncircular, as well as circular, orifices using digital color Row data . Ractlgroaud. Recently it been fed that low volume thrmo an orifice can be estimated more accurately by computing the axial "centerline" low velocityldistance profile proximal to the orifice. etha'. A total of se...

UNLABELLED This work applied a propagation of uncertainty method to typical total suspended particulate (TSP) sampling apparatus in order to estimate the overall measurement uncertainty. The objectives of this study were to estimate the uncertainty for three TSP samplers, develop an uncertainty budget, and determine the sensitivity of the total uncertainty to environmental parameters. The sampl...

BACKGROUND The anatomic opening area (AOA) is usually reported as the primary index of mechanical heart valve function. Because flow contracts immediately distal to an orifice as a result of the vena contracta effect, AOA may not be a good measure of true effective flow area. METHODS AND RESULTS Laser flow imaging was used to visualize the contraction in the jet flow stream as it passed throu...