Control valves are commonly found in modern process plants. The control valve reliability is critical to the control quality and safety of a plant. Whether a control valve meets the challenge of the control requirement depends on its response characteristics. To obtain the characteristics of the control valve, an experiment test system is developed to assess the performances of the control valv...

introduction: rheumatic heart disease still remains one of the leading causes of congestive heart failure and death owing to valvular pathologies, in developing countries. valve replacement still remains the treatment of choice in such patients.the aim of this study wasto analyze the postoperative outcome of  double valve replacement (mitral and aortic ) in patients of rheumatic heart disease. ...

Recently, power assisted nursing care systems have received much attention and active research. In such control system, an actuator and a control valve are mounted on the human body. In such designs, the size and weight of the valve become serious concerns. At the same time, the valve should be operated with lower energy consumption using limited electrical power. The purpose of our study is to...

The flexible control system for hydraulic pile hammer using main control valve is present to the requirement of rapidly reversing with high frequency. To ensure the working reliability of hydraulic pile hammer, the reversing performance of the main control valve should commutate robustness to various interfere factors. Through simulation model built in Simulink/Stateflow and experiment, the eff...

For the problem of low efficiency of conventional valve control systems, an economical PWM-based valve control system with no throttle loss is put forward and examined in this paper. There are four no-throttling-loss units used to control a single rod cylinder in this fixed displacement pump system, which breaks the mechanical linkage of meter-in and meter-out flow in the traditional four way d...

Valves are ubiquitous as final control elements in the chemical process industries. Motivated by heavy valve usage by the process industries and many industrial reports of valve nonlinearities undermining effective process control, this article summarizes our recent work that unifies concepts related to valve dynamics with frequently reported industrial concerns, and also investigates methods o...

To increase the efficiency of hydraulic systems by eliminating valve throttling losses, a direct displacement open circuit is proposed to control a single rod hydraulic actuator. The circuit provides three control inputs, including the displacement of a variable displacement pump, the opening area of a proportional valve, and the position of a directional valve. Pump control has a low bandwidth...