Water hammers seriously endanger the stability and safety of pipeline transportation systems, its protection mechanism has been a hotspot for research. In order to study change water hammer pressure caused by ball valve under different closing laws, computational fluid dynamics method was used perform transient numerical simulation times laws. The results show that faster speed in early stage, ...

A 44-year–old woman underwent mitral valve and tricuspid valve (TV) replacement 6 years earlier using an ATS bileaflet tilting disc prostheses (ATS Medical Inc., Minneapolis, MN) for combined valvular stenosis and regurgitation because of rheumatic heart disease. On a routine clinic visit, the patient reported progressive fatigue and pedal edema over the previous few weeks. On physical examinat...

A high-resolution method of spectral analysis, of the class generally called "maximum entropy method," was used in a study of aortic porcine valve closing sounds in 37 patients (ages 19 to 76). Spectra from 27 normal xenografts, implanted from 2 weeks to 61 months previously, were characterized by a dominant frequency peak, F1, at 89 +/- 15 Hz (mean +/- SD), with a lower amplitude peak, F2, at ...

Abstract The high speed, transient cavitating flow distribution inside diesel injector nozzles with consideration of the opening and closing needle valve is calculated using a generalized equation of state (EOS) to describe the fluid density, a homogeneous equilibrium model (HEM) for phase change, and an arbitrary moving mesh to account for needle motion. The KIVA-3V code was modified for the g...

The effects of the valve opening and opening height are very crucial in internal combustion engine. The optimum setup for the opening cam high and timing of camshafts in engines will improve fuel economy and exhaust gas emission. This improvement can be obtained from intake (inlet) valve timing and also from exhaust (outlet) valve timing. The challenging technique is to set up the engine to the...

Background We aim to investigate the effect of utilizing aortic valve timing in the measurement of cardiac magnetic resonance (CMR)-derived ejection fraction (EF). Although CMR-derived left ventricular (LV) EF is the gold-standard for volumetric evaluation of the heart, it always reports higher values when compared to other modalities such as echocardiography and radionuclide ventriculography. ...

Echocardiographically recorded mitral valve motion was compared with phasic transmitral flow in 17 open chest dogs. The normal mitral valve opening started with the onset of mitral flow and reached its full excursion while flow was still accelerating. Complete valve opening occurred .044 sec (plus or minus .002 sem) before peak flow, during which time an average of 17.6 percent of total mitral ...

OBJECTIVE Recently, various modifications have been made to aortic root replacement procedures to include the pseudosinus in the synthetic graft, but its effect on valve function still remains to be elucidated. The purpose of this study was to compare the flow dynamics and its influence on the stress/strain in the valve leaflet in two types of aortic root, either with or without the pseudosinus...