The aortic valve operates in a complex haemodynamic environment, opening and closing over 100,000 times a day. When complications arise, such as aortic stenosis, prognosis can be very poor, leading to death within the first few years. Surgical valve replacement is currently the standard treatment for aortic stenosis. A thorough understanding of the anatomy and function of the native valve is im...

Variable valve timing allows improvements of internal combustion engines and can be achieved by camless actuation technology. In this paper we consider an electromechanical valve (EMV) actuator. One of the main problems in the EMV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator parts can be ...

Particle Image Velocimetry (PIV) is an important technique in studying blood flow in heart valves. Previous PIV studies of flow around prosthetic heart valves had different research concentrations, and thus never provided the physical flow field pictures in a complete heart cycle, which compromised their pertinence for a better understanding of the valvular mechanism. In this study, a digital P...

Water-hammer is a transient condition which may occur in a network as a result of rapid or slow valve closures, pump failures, changes in turbine loading, etc. It creates high and low pressure waves which travel along the system and decay as a result of wall shear stress. Comparison o experimental and theoretical results revealed the failure of steady or quasi-steady models in correctly predict...

This paper investigates multiple-valve closures in a simple reservoir-valve-pipeline-valve system. Multiple closing (or opening) of valves may induce large positive or low negative pressure waves due to wave interference (superposition the waves). The effect closure can be either beneficial detrimental, with outcome being entirely dependent on position and sequence delay closures. Valves are in...

In order to improve the reliability of tripping solenoid valve and switching steam turbine in nuclear power plant reduce abnormal closing. According working principle valves plant, this paper designs a kind electromagnetic sealing test system, including base, measurement control system hydraulic system. The detection is an offline By simulating real load condition tightness tested valve. actual...

The purpose of a prosthetic cardiac valve is to restore the function of a diseased aortic or mitral valve, and its role in haemodynamics is a passive one: the opening and closing of such a valve is strictly regulated by the pressure differences in the cardiac chambers which communicate through this valve. Therefore we consider that a prosthetic valve should be tested under conditions simulating...

BACKGROUND AND OBJECTIVES The aim of this study was to assess mechanical valve function using 64-slice multidetector computed tomography (MDCT). SUBJECTS AND METHODS In 20 patients (mean age, 50+/-12 years; male-to-female ratio, 10:10), 30 St. Jude bileaflet mechanical valves (15 aortic and 15 mitral valves) were evaluated using MDCT. We selected images vertical and parallel to the mechanical...