Search results for "shunt"

Investigation of the Temperature Sensitivity of 20-Years Old Field-Aged Photovoltaic Panels Affected by Potential Induced Degradation

2022

One effect of moisture ingress on solar panels is potential induced degradation (PID). Solar panels affected by PID experience large leakage currents between the solar cells and the module’s frame, which leads to substantial power degradation. In the present work, the temperature coefficients of 3 old PV panels affected by PID were investigated. In the electroluminescence images, solar cells nearer to the edge of the modules appear darker due to ohmic shunting. IR thermal images acquired under clear sky outdoor conditions show that the majority of the warmer cells (hotspots) were located closer to the edge of the modules. The difference in cell temperature (∆T) due to PID effect…

25-kW/50-kHz generator for induction heating

1991

The authors present the features, technology, and construction of a transistorized generator for induction heating operating over the 4-50 kHz frequency range. This type of 25 kW output-power generator allows replacement of the electronic tube generators for most of their applications. The advantages of this new generator are more energy efficiency, extended life, reduced size, separated heating station of the generator, and connection by flexible cable. In addition, the generator has incorporated a frequency automatic tracking system that allows operating without any adjustments over a wide frequency range. >

Modeling the Sequential Switching Shunt Series Regulator

2005

This letter characterizes, in terms of the bandwidth and limit cycle frequency of its constituent subsystems, the sequential switching shunt series regulator -S/sup 4/R, a high-efficiency, low-mass and volume power cell devised to power the next generation of regulated power buses in telecommunication spacecrafts. Transconductance power source modeling is used to obtain linear and nonlinear models. These are used to establish a design control strategy which involves the dynamic response in large load requirements or at the end of the satellite life. Simulations and experimental results are also given to demonstrate the validity of the model.

Frame-based and frameless endoscopic procedures in the third ventricle.

1997

Stereotactic guidance is useful for planning an accurate trajectory to the third ventricle. A guiding block with a ball joint was developed for frame-based endoscopy and adaptors for arm-based and armless navigation systems. Between 1992 and 1996, 52 patients were operated on endoscopically in the third ventricle under stereotactic guidance. Thirty-eight ventriculostomies, 13 biopsies and 10 cystic lesions were performed. The coordinates of two points were calculated; one in the foramen of Monro and the second in the third ventricle. The ventriculostomy was performed under endoscopic control bluntly with a Fogarty catheter in front of the basilar artery. Twenty-seven (71%) of the patients h…

Cerebrospinal Fluid Dynamics Following Ventriculoperitoneal Shunt in Hydrocephalus: Do Technological Advancements Avoid Complications?

2022

Zur therapie der �sophagusvarizenblutung in der Bundesrepublik Deutschland (West) ? Ergebnisse einer Urnfrage

1991

An 1076 chirurgischen und internistischen Abteilung in der BRD (West) wurde eine Umfrage zur Behandlung der Osophagusvarizenblutung durchgefuhrt. Es uberwiegt die Akutsklerosierung bzw. die Ballonsondenbehandlung mit nachfolgender Sklerosierung bei der aktiven Blutung. Die abdominelle Sperroperation wird bei der konservativ nicht stillbaren Blutung noch vor dem portokavalen Notshunt bevorzugt. Betablocker werden vor allem in internistischen Abteilungen zur Rezidivprophylaxe eingesetzt. Erst nach mehrfacher Rezidivblutung trotz Sklerosierung sehen etwa die Halfte der Abteilungen eine Indikation zum elektiven Shunt. Der distale splenorenale Shunt nach Warren and die portokavale Anastomose dom…

Adjustable tourniquet to manipulate pulmonary blood flow after Norwood operations

2000

Abstract Background . Survival after first-stage palliative Norwood operations for single ventricle with systemic outflow obstruction is mainly dependent on a balanced ratio of pulmonary blood flow to systemic blood flow. Here we report the clinical results using a modified technique that allows a controlled systemic-to-pulmonary shunt flow to prevent pulmonary overcirculation. Methods . From 1995 to 1998, of 26 infants undergoing first-stage palliative Norwood operations, 7 had placement of an adjustable tourniquet around a modified right Blalock-Taussig shunt. Results . Hospital survival was 20 of 26 patients (77%). All 7 patients in whom snaring of the shunt was indicated survived. Two p…

Imaging-guided interventions modulating portal venous flow: Evidence and controversies

2021

Portal hypertension is defined by an increase in the portosystemic venous gradient. In most cases, increased resistance to portal blood flow is the initial cause of elevated portal pressure. More than 90% of cases of portal hypertension are estimated to be due to advanced chronic liver disease or cirrhosis. Transjugular intrahepatic portosystemic shunts, a non-pharmacological treatment for portal hypertension, involve the placement of a stent between the portal vein and the hepatic vein or inferior vena cava which helps bypass hepatic resistance. Portal hypertension may also be a result of extrahepatic portal vein thrombosis or compression. In these cases, percutaneous portal vein recanalis…

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Arterial O2-Partial Pressure at Positve Endexpiratory Pressure in Hyperoxia for Verification of Patent Foramen Ovale?

1990

As a rule, during anaesthesia a time dependent increase in pulmonary shunting occurs even in states of normal lung function. Therefore positive end-expiratory pressure ventilation (PEEP) is often used to decrease intrapulmonary right/left shunting (RL shunt) and thus to increase arterial O2 partial pressure (paO2) without increasing the inspiratory oxygen fraction.