OBJECTIVE To assess the hydrodynamic properties of three new types of hydrocephalus valve. METHODS Three new constructions have been recently tested in the UK shunt Evaluation Laboratory: the magnetically adjustable Strata Valve (Medtronic PS Medical), the gravitational Miethke Dual-Switch Valve (Aesculap) and the ventriculo-sinus SinuShunt (CSF Dynamics). Pressure-flow performance curves wer...

Method of measurement of pressure drop in ports of hermetic compressor under discharge pressure is presented. ?,22 gas at 298 psig and 215QF condition pumped by hermetic compressor is directed into flow bench type pressure chamber where variety of orifices is installed and pressure drop is measured directly. Compressor and flow bench are installed in series on standard calorimeter which measure...

A silencer to attenuate engine exhaust noise using active control methods is developed. The device consists of an electrically driven valve, combined with a buffer volume, which is connected to the exhaust outlet. Using the mean flow through the valve and the pressure fluctuations in the volume, the valve regulates the flow in such a way that only the mean flow passes through the exhaust outlet...

Experimental investigations on the noise characteristics in spool valve with v-notches are conducted in this paper. Cavitation noise with frequency peak forms when the flow state changes form single phase turbulent to cavitating. The peak frequency decreases with the increase of the flowrate. On the other hand, jet flow develops intensely from the notches. Self-sustained flow oscillation produc...

The detailed unsteady turbulent flow inside a centrifugal fan and its downstream pipe was studied using detached eddy simulation (DES) at three flowrates, namely, the best efficiency point (BEP), 0.75BEP, 1.49BEP. Both mean fluctuating fields were analyzed on basis of root-mean-square value as indication intensity. Results showed that pressure fluctuation had minimum BEP, but velocity increased...

Purpose: To investigate the outcome of outlet-type ventricular septal defect (VSD) after surgery in pediatric patients. Methods: A total of 152 children who underwent surgical repairs for outlet-type VSD were enrolled. Clinical features associated with development of congestive heart failure (CHF), aortic valve prolapse (AVP), and aortic regurgitation (AR) were analyzed. Results: CHF was noted ...

Recently, with large-scale use of natural gas and massive constructions of gas pipelines, more and more public concern is focused on pipeline leakage. The leakage caused by holes on gas pipelines generates economic losses to gas companies and causes risks to the environment and sometimes accidents. In order to detect and locate pipeline rupture immediately, the leakage detection method plays a ...

The control valve operates at high operation frequency (up to 1,000 Hz) in the large pressure differences between the inlet and outlet of the valve. The flow and operation characteristics of a high-speed electromagnetic control valve are investigated using a commercial software, CFD-ACE+. It is found that maximum operation frequency of the control valve depends on the applied electromagnetic fo...

PURPOSE We assessed the effect of terazosin (Hytrin(R)) on functional bladder outlet obstruction in women. MATERIALS AND METHODS Functional bladder outlet obstruction was defined as a maximum flow rate of less than 12 ml per second combined with a detrusor pressure at maximum flow rate of more than 20 cm H2O in pressure flow studies in the absence of neurological disorders or mechanical cause...