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- Revstedt, Johan, et al.
(författare)
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Influence of impeller type on the flow and mixing in a stirred reactor
- 2000
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Ingår i: AIChE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 46:12, s. 2373-2382
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Tidskriftsartikel (refereegranskat)abstract
- Large eddy simulations (LES) of a stirred reactor with a liquid volume of 0.64 m3 were performed. The tank was stirred by either two standard Rushton impellers or two Scaba 6SRGT impellers. The LES can provide details of the flow field that cannot be obtained with so‐called Reynolds‐averaged equations and the corresponding models. The unsteady spatially filtered incompressible Navier‐Stokes equations were solved together with a transport equation for the concentration of an inert additive using a multigrid finite difference code with a staggered grid. The unresolved turbulent scales were modeled using a scale similarity model. The aim of this investigation has been to study the influence of impeller type on the flow structure and scalar transport. The results show that, compared at equal power input, the center plane velocities and the volume flow in the impeller stream do not differ much for the impeller types. Also, for the 6SRGT the periodic fluctuations associated with the blade passing is less pronounced
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- Sándor, János, et al.
(författare)
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A subduralis vérzés miatt kezelt betegek halálozását befolyásoló tényezók : [Predictors of lethal outcome in subdural haemorrhage]
- 2003
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Ingår i: Ideggyogyaszati Szemle. - : Literatura Medica Kiado. - 0019-1442 .- 2498-6208. ; 56:11-12, s. 386-395
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Tidskriftsartikel (refereegranskat)abstract
- Background: Subdural haemorrhage (SDH) is of high public health importance because of its frequency, high case fatality ratio (CFR) and the young age of affected population. Despite the fact that the effectivity of guideline based treatment has been improved in the last decade, the Hungarian praxis shows variable compliance for recommendations.Objectives: The study aimed to describe the heterogeneity of the treatment effectivity (by geographically identifying the populations provided with appropriate or non-optimal level care), to determine the relationship between the institutional proxies quality and the results of treatment for SDH by linking the proxies properties to the patients' records.Methods: The institutions' protocols were assessed by a self-completed questionnaire in 1997. The participating hospitals treated 79% of the Hungarian patients with SDH. The Hungarian hospital discharge data in 1997-1999 were the source of patient specific data. The risk factors of lethal outcome were investigated by logistic regression analysis.Results: High proportion of patients had been treated in hospital with low compliance for guidelines. The non-permanent access to neurosurgical service and CT facility, the lack of intracranial pressure monitoring and the respiration support provided out of intensive care units worsened the survival of subjects. It was quantified that the full compliance could have diminished the case fatality ratio by 15-20%. The ratio of extreme county level CFRs exceeded 2.36 and extrapolating the effectivity observed in the county with lowest lethality, the Hungarian CFR would have been reduced by 21% among patients with SDH main diagnosis. (The interpretation of findings is limited by the lack of differentiation between acute and chronic cases and of direct categorisation of severity for subdural haemorrhage in the official hospital discharge records).Discussion: The study results urge the increase of compliance for evidence based guidelines, since despite of some validity issues, it was demonstrated that the deviation from recommended practice is reflected in the disadvantageous outcome.
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