The variability of peak flow measurements was studied in 24 patients with airway obstruction, using 12 Assess peak flow meters and a Fleisch pneumotachograph type 4 as a standard. The Assess peak flow meter gave systematic under-readings of 19-34% (low accuracy). The value scale of the Assess peak flow meter should be adjusted. As systematic under-readings do not influence the variability in pe...

A constant-temperature heated-film anemometer system has been adapted for the detailed study of in-vivo aortic velocity fields. Two types of sensing probes were developed: a velocity probe and a velocity-gradient or fluid shear stress probe. These probes were evaluated for steady and pulsatile flow in rigid circular tubes using both a glycerin-water mixture and blood. Measurements using both de...

BACKGROUND Noninvasive assessment of functionally stenotic small-diameter aortic mechanical prostheses is complicated by theoretical constraints relating to the hemodynamic relevance of Doppler-derived transprosthetic gradients. To establish the utility of Doppler echocardiography for evaluation of these valves, 20-mm Medtronic Hall and 19-mm St Jude prostheses were studied in vitro and in vivo...

BLOOD flow in single vessels can be measured by direct methods such as rotameter, drop-flow meter, Rein-thermostromuhr, Venturi principle, electromagnetic flow meter and bubble-floAV meter. Such methods are usually characterized by great accuracy, but their applicability is considerably limited in man by the fact that the appropriate vessel must be made accessible. Blood flow in some regions wa...

BACKGROUND Although Doppler color flow mapping is widely used to assess the severity of mitral regurgitation (MR), a simple, accurate, and quantitative marker of MR by color flow mapping remains elusive. We hypothesized that vena contracta width by color flow mapping would accurately predict the severity of MR. METHODS AND RESULTS We studied 80 patients with MR. Vena contracta width was measu...

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study e...

Objectives : The objectives of this study are to assess the degree uniformity flow rate flowing into four grit chamber for actual waste water treatment and improve hydraulic structure existing distribution channel.Methods Mobile ultrasonic meter was used measure each chambers, CFD technique suggest several improvements enhancing evenness.Results Discussion From results measurement using flowmet...

The noninvasive Doppler assessment of regurgitant volume from jet size is limited by the fundamental inequality of jet volume and regurgitant volume and by the dependence of jet dimensions on driving pressure and instrument settings for a given flow volume. Therefore, this study addresses the hypothesis that an equation could be derived from basic physical principles to quantify regurgitant vol...

Grazing flow passing over the quiescent fluid inside the cavity of a Helmholtz resonator can excite the resonator. When the frequency of the instabilities within the shear layer is near the natural frequency of the resonator then flow-excited resonance will occur. This process causes self-sustained periodic oscillations of the flow over the orifice of the resonator. Quantitative numerical predi...

Electromagnetic flow meters based on the principles of Faraday’s laws of induction have been used successfully in many industries. The conventional electromagnetic flow meter can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel Imaging Electromagnetic ...