joule-thomson cooling systems are used in refrigeration processes such as cryogenic gas liquefaction. although extensive studies have been carried out by researchers, most of them include cryogenic heat exchangers and their associated fields. in the current study, an attempt was made to indicate the effect of using inappropriate operational conditions in a cryogenic joule-thomson cooling system...

BACKGROUND Low-gradient severe aortic stenosis with preserved ejection fraction is an increasingly recognized entity, and symptomatic patients may benefit from aortic valve replacement. However, systemic hypertension frequently coexists with low-gradient severe aortic stenosis, which itself may cause elevated left ventricular (LV) filling pressures with resultant symptoms of dyspnea. METHODS ...

A piston piezoelectric (PZT) pump has many advantages for the use of light actuators. How to deal with contradiction between amount and oil delivery quality is an essence when designing pump. In order depress pressure pulsation flow in a single-piston PZT pump, two-stage attenuator proposed. It involves elastic cavity group unloading valve. Unsteady inside numerically calculated analyzed reveal...

s spring In some nuclear reactor containment isolation applica­ Greek tions, butterfly valves with pneumatic actuators are used to close pipelines in the event of containment p density pressure transients resulting from postulated acci­ e angular position dents. A model is developed which predicts the closure time history of such valve/actuator systems INTRODUCTION under prescribed transients. ...

We have investigated the prevalence of hypertension and the response of blood pressure to operation in 87 patients with lone aortic valve disease who underwent aortic valve replacement. In patients with aortic stenosis alone 26% were hypertensive pre-operatively (age and sex adjusted blood pressure greater than 160 systolic and or greater than 95 mmHg diastolic) and 24% were hypertensive post-o...

BACKGROUND Pressure recovery is the variable increase in lateral pressure downstream from a stenotic orifice. The magnitude and clinical significance of pressure recovery in aortic valve stenosis are poorly defined. METHODS AND RESULTS We obtained high-fidelity pressure and velocity recordings in 11 patients with isolated significant aortic valve stenosis at the time of diagnostic cardiac cat...

Normally closed (NC) micro check-valve is used to stop liquid flow when liquid pressure difference across the membrane is lower than the designed cracking pressure. As shown in Figure 2-1, when the applied pressure P is lower than the designed cracking pressure, P c , the NC check-valve is closed, and vice versa. Generally the cracking pressure can be introduced electrically such as electromagn...

heat exchangers are the critical components of refrigeration and liquefaction processes. selection of appropriate operational conditions for cryogenic recuperative heat exchanger and expansion valve operating in joule-thomson cooling system results in improving the performance and efficiency. in the current study, a straightforward procedure is introduced to design an efficient joule-thomson co...

Pressure relief valve is one of the most important devices used on the security of pipelines, since it is responsible to guarantee the integrity of the installations. Generally, the response and behavior of a relief valve during its transient is unknown by users, who employ simplified and static analysis to design the pipeline, further, the information provided by manufactures is limited. The f...

Nasal foreign body in children is not an uncommon presentation to the Emergency Department. Removal is essential. Many methods of removal exist. Nasal wash technique is advocated mainly in friable foreign bodies. We report the successful use of the oral bag-valve-mask insufflation technique to remove friable facial tissue in the left nose of a 2 year-old girl. We used a pediatric bag-valve-mask...