In certain mechanical heart valves, cavitation has been shown to develop during closure and rebound, leading to valve damage, blood damage, and strokes. Whereas it is uncertain what causes mechanical heart valve related strokes, some evidence suggests that stable bubbles may be the culprits. Previous work has indicated that vortex cavitation may contribute to stable bubble growth. Therefore, in...

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...

In this paper, validated simulations using Ricardo WAVE have been performed to investigate the effect of Miller cycle and low-carbon fuels on performance (power, torque, BTE BSFC) emissions a diesel engine. The results show that increased (larger deviation advanced or retarded intake valve closing from standard time) will decrease NOx, CO HC emissions, slightly improve brake thermal efficiency ...

Disc excursion and opening and closing velocities of prosthetic disc valves can be measured accurately by diagnostic echocardiography. The ultrasound beam is projected along the longitudinal axis of the valve and the echoes arising from the struts, disc, and suture ring are displayed on the oscilloscope. Twenty-four patients with normally functioning mitral Beall valves of various sizes and thr...

The in vivo operation of a speaking valve consists of two stages: 1) air passes through the razor-thin slit, the dome opens and the patient can speak; 2) the dome is closed and the patient cannot speak. The valve is thus subject to fatigue, as its service life is made up of a certain number of opening/closing cycles. Two types of valve were investigated: the Staffieri valve and a new valve prot...

A stainless steel, six-inch valve capable of closing in apprcximately 10 milliseconds has been developed at the Stanford Linear Accelerator Center. The valve will be automatically and zemotely operable, allowing it to be used in the S:dC be:nl switchyard area where high radi,tion levels wil:. prohi,it personnel pccess. The 7roblLdns of '.rigge-ing mechanical release, Lalve gute acceleratior and...

There is presently considerable ambiguity and confusion relating to ventilator terminology. This can be eliminated using a simple approach, visualising mechanical ventilation as an inspiratory pump, and defining trigger, limit, and cycling in this context. The trigger is the signal that starts a breath by opening the inspiratory valve, the limit is the factor which controls the way gas flows in...

This paper addresses modeling analysis and the soft seating control of an electromagnetic actuator used in electromechanical camless valvetrains. Our mathematical modeling analysis reveals the instability of the actuator dynamics linearized around the seating position and zero velocity. This implies that open loop pulse shaping alone cannot render repeatable valve closing and seating motion. Cl...

In this research, a method previously applied to improve a digital simulation of the avian syrinx is adapted to the geometry of the clarinet reed. The clarinet model is studied with particular attention to the case when the reed beats again the lay of the mouthpiece, closing off air flow to the bore once each period. In place of the standard reed table which gives steady-state volume flow as a ...