Two infants underwent supra-annular placement of prosthetic mitral valves. The objective of this strategy was to insert a larger valve and delay replacement. This approach was initially successful but by two and three years later the patients developed impairment of cardiac function. The prosthesis decreased the volume and compliance of the left atrium causing high left atrial and pulmonary ven...

An emerging method to increase the recovery from oil reservoirs is the application of measurement and control techniques to better control subsurface flow over the life of the reservoir. In particular the use of sensors and remotely controllable valves in wells and at surface, in combination with large-scale subsurface flow models is promising. Various elements from process control may play a r...

An emerging method to increase the recovery of oil from subsurface reservoirs is the application of measurement and control techniques to better control the multiphase flow in the reservoir over the entire production period. In particular the use of sensors and remotely controllable valves in wells and at surface, in combination with large-scale reservoir flow models is promising. Various eleme...

The motivation for this work is to formulate a control design method for a pneumatic system with discrete input values (resulting from the use of binary or three-position solenoid valves) that addresses the time-delay that is often associated with the flow state of solenoid on/off valves. This method is shown to be applicable to a general class of nonlinear, nonautonomous systems subject to pos...

A highly transient flow regime called riser slugging can develop in pipelines from wellheads to separation tanks which introduces severe oscillations of pressure and flow rates in off-shore processes. Mitigation of the intensity of riser slugging may be achieved via anticipative control actions on valves positioned at the entrance and at gas/oil exits of the separators. In Phase 1, this work is...

BACKGROUND Calcification and dysfunction of aortic and mitral valves are frequently found in chronic dialysis patients, but their influence on the development of left ventricular hypertrophy (LVH) is not well defined. METHODS Conventional echocardiography and Doppler measurement of trans-aortic flow velocity were performed in 135 chronic haemodialysis patients, and left ventricular mass index...

Hysteresis and nonlinearity exist in most valves that are utilized in building HVAC systems, such as in cooling or heating coil valves. The hysteresis mainly comes from the manufacturing clearance in an actuator gearbox and nonlinearity in the variation of the regulated flow with respect to control signal originates from valve design. The combination of valve hysteresis and nonlinearity poses s...

Aortic valve resistance has been proposed to represent the severity of aortic stenosis because some studies observed that it was less affected by change in flow than the valve-effective orifice area, but this issue remains controversial. The objective of this study was to systematically analyze the theoretical and practical determinants of these parameters in relation to changes in flow. Valve ...

The article considers the problem of determining characteristics working media that flow in flowing channels control ball valves. A mathematical model gas medium a valve for different angular positions regulating body (stem) was developed typical widespread design this type computational study carried out to determine pressure and velocity fields, dependence resistance rate on angle turn stem. ...