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156. Entwurf von Beschaufelungen hydraulischer Maschinen mit Hilfe neuronaler Netze

Author

Baier, Horst (Prof. Dr.), Schilling, Rudolf (Prof. Dr. Dr. habil.), Krämer, Stefan, Baier, Horst (Prof. Dr.), Schilling, Rudolf (Prof. Dr. Dr. habil.), and Krämer, Stefan

Abstract

Im Rahmen dieser Arbeit wird ein neu entwickeltes Entwurfssystem auf der Basis künstlicher neuronaler Netze vorgestellt, mit dem in kurzer Zeit nahezu optimale Beschaufelungen hydraulischer Maschinen generiert werden können. Das System ermöglicht die Aufbereitung und Parametrisierung vorhandener Geometrien von Francis Turbinen und Kreiselpumpen, die in Abhängigkeit von einer beliebigen Anzahl an Betriebspunktparametern mit dem integrierten Backpropagation Lernverfahren trainiert werden können. Am Beispiel einer Baureihe von sechs Francis Turbinen sowie sechs Kreiselpumpen wird gezeigt, dass das entwickelte Verfahren in der Lage ist, einen funktionalen Zusammenhang zwischen Betriebspunkt und Geometrie zu erkennen, zu lernen und neue Geometrien mit vergleichbaren Strömungseigenschaften zu erzeugen. Als Ergebnis dieser Arbeit zeigt sich, dass der Einsatz künstlicher neuronaler Netze eine erhebliche Zeitersparnis im Entwurfs- und Optimierungsprozess von Strömungsmaschinen bedeutet., In this thesis a newly developed design system based on artificial neural networks is presented to generate nearly optimal hydraulic machinery bladings within a short time. The system allows the preprocessing and parametrization of existing geometries of Francis turbines and centrifugal pumps which can be trained with the integrated backpropagation algorithm depending on an arbitrary number of operating point parameters. Considering as example a series of six Francis turbines and six centrifugal pumps it will be demonstrated that the developed system is able to recognize and to learn a functional relationship between operating point and geometry and to generate new geometries with comparable flow characteristics. As result of this thesis it is shown that the use of artificial neural networks means considerable saving of time in the design and optimization process of fluid machinery.

Published
2007

157. Entwurf von Beschaufelungen hydraulischer Maschinen mit Hilfe neuronaler Netze

Author

Schilling, Rudolf (Prof. Dr. Dr. habil.), Schilling, Rudolf (Prof. Dr. Dr. habil.);Baier, Horst (Prof. Dr.), Krämer, Stefan, Schilling, Rudolf (Prof. Dr. Dr. habil.), Schilling, Rudolf (Prof. Dr. Dr. habil.);Baier, Horst (Prof. Dr.), and Krämer, Stefan

Abstract

Im Rahmen dieser Arbeit wird ein neu entwickeltes Entwurfssystem auf der Basis künstlicher neuronaler Netze vorgestellt, mit dem in kurzer Zeit nahezu optimale Beschaufelungen hydraulischer Maschinen generiert werden können. Das System ermöglicht die Aufbereitung und Parametrisierung vorhandener Geometrien von Francis Turbinen und Kreiselpumpen, die in Abhängigkeit von einer beliebigen Anzahl an Betriebspunktparametern mit dem integrierten Backpropagation Lernverfahren trainiert werden können. Am Beispiel einer Baureihe von sechs Francis Turbinen sowie sechs Kreiselpumpen wird gezeigt, dass das entwickelte Verfahren in der Lage ist, einen funktionalen Zusammenhang zwischen Betriebspunkt und Geometrie zu erkennen, zu lernen und neue Geometrien mit vergleichbaren Strömungseigenschaften zu erzeugen. Als Ergebnis dieser Arbeit zeigt sich, dass der Einsatz künstlicher neuronaler Netze eine erhebliche Zeitersparnis im Entwurfs- und Optimierungsprozess von Strömungsmaschinen bedeutet., In this thesis a newly developed design system based on artificial neural networks is presented to generate nearly optimal hydraulic machinery bladings within a short time. The system allows the preprocessing and parametrization of existing geometries of Francis turbines and centrifugal pumps which can be trained with the integrated backpropagation algorithm depending on an arbitrary number of operating point parameters. Considering as example a series of six Francis turbines and six centrifugal pumps it will be demonstrated that the developed system is able to recognize and to learn a functional relationship between operating point and geometry and to generate new geometries with comparable flow characteristics. As result of this thesis it is shown that the use of artificial neural networks means considerable saving of time in the design and optimization process of fluid machinery.

Published
2007

158. Mammakarzinom

Author

Wirtz, Marina, primary, Krämer, Stefan, additional, Puppe, Julian, additional, and Mallmann, Peter, additional

Published
2012
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181. Relapsing TIPIC Syndrome after Administration of an mRNA-Based COVID-19 Vaccine

Author

C. Sandu, Georgiana, Weisser, Gregor, Krämer, Stefan, and Reinhard, Matthias

Abstract

Reported vascular complications following mRNA-based COVID-19 vaccines are consisting of myocarditis, cerebral venous thrombosis, cerebral vascular thrombosis, and vaccine-induced thrombocytopenia. Here, we describe a case of a 49-year-old woman with left-sided pain above the middle common carotid artery (carotidynia) starting a few days after her second vaccination with an mRNA-based COVID-19 vaccine (Spikevax). Imaging was indicative of transient perivascular inflammation of the carotid artery (TIPIC) syndrome. The diagnostic workup for other immunologically mediated diseases was negative. The inflammation subsided after a course of prednisone and aspirin, and clinical symptoms vanished, but later mildly relapsed in the context of a viral upper respiratory tract infection other than SARS-CoV-2. Carotidynia because of TIPIC syndrome may present as an immunogenic side effect of the newly developed mRNA-based vaccinations against COVID-19. TIPIC syndrome should be considered in new-onset neck pain after vaccination.

Published
2023
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189. NCO-Tracking with Changing Set of Active Constraints using Multiple Solution Models

Author

Ebrahim, Taher, Hernandez, Reinaldo, Subramanian, Sankaranarayanan, Kalliski, Marc, Krämer, Stefan, and Engell, Sebastian

Abstract

Measurement-based optimization schemes can be used to counteract the effect of uncertainty and to drive the process to optimality. Necessary Conditions of Optimality Tracking (NCO-tracking) is a promising scheme which uses the process measurements to update the inputs directly. The limiting assumption for the application of the NCO-tracking scheme is that the set of active constraints does not change from its nominal value under the influence of the uncertainties. This paper presents a scheme that extends the NCO-tracking approach to handle parametric uncertainties that change the set of active constraints. Several solution structures are implemented to cover the whole range of the uncertain parameters. Based on the identification of the region of the uncertain parameters, the correct solution model is determined and applied to the process. The applicability of the methodology is shown for the benchmark Williams-Otto semi-batch reactor.

Published
2016
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190. Industrial Application of Multi-criterial Decision Support to improve the Resource Efficiency**The research leading to these results was done within the project MORE (Real-time Monitoring and Optimization of Resource Efficiency in Integrated Processing Plants). The project has received funding from the European Unions Seventh Framework Programme for research, technological development and demonstration under grant agreement No 604068.

Author

Ackerschott, Daniel, Beisheim, Benedikt, Krämer, Stefan, and Engell, Sebastian

Abstract

The high complexity of integrated processing plants makes it a hard problem for managers and operators to find the best operational strategy. And it becomes even more difficult when they have to deal with more than one criterion for optimality because trade-offs between conflicting goals have to be taken into account. Usually optimisation problems are set-up with a single objective function, where several criteria are compressed into one figure by weighting factors. Thus, the result is a single number without any leeway in decision making. In contrast, multi-criterial optimisation reveals the room for manoeuvre. Since the plant personnel have to balance several requirements in order to run the plant in an “optimal” fashion, we propose to use multi-criterial optimisation to assist them in their daily decisions.

Published
2016
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192. Relapsing TIPIC Syndrome after Administration of an mRNA-Based COVID-19 Vaccine.

Author

Sandu, Georgiana C., Weisser, Gregor, Krämer, Stefan, and Reinhard, Matthias

Subjects
*MESSENGER RNA, *COVID-19 vaccines, *NECK pain, *RESPIRATORY infections, *CEREBRAL embolism & thrombosis, *CAROTID artery
Abstract

Reported vascular complications following mRNA-based COVID-19 vaccines are consisting of myocarditis, cerebral venous thrombosis, cerebral vascular thrombosis, and vaccine-induced thrombocytopenia. Here, we describe a case of a 49-year-old woman with left-sided pain above the middle common carotid artery (carotidynia) starting a few days after her second vaccination with an mRNA-based COVID-19 vaccine (Spikevax). Imaging was indicative of transient perivascular inflammation of the carotid artery (TIPIC) syndrome. The diagnostic workup for other immunologically mediated diseases was negative. The inflammation subsided after a course of prednisone and aspirin, and clinical symptoms vanished, but later mildly relapsed in the context of a viral upper respiratory tract infection other than SARS-CoV-2. Carotidynia because of TIPIC syndrome may present as an immunogenic side effect of the newly developed mRNA-based vaccinations against COVID-19. TIPIC syndrome should be considered in new-onset neck pain after vaccination. [ABSTRACT FROM AUTHOR]

Published
2023
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194. Treatment of Leaks after Endovascular Repair of Aortic Aneurysms

Author

Görich, Johannes, primary, Rilinger, Norbert, additional, Sokiranski, Roman, additional, Krämer, Stefan C., additional, Ermis, Cengiz, additional, Schütz, Ansgar, additional, Brambs, Hans-Jürgen, additional, Söldner, Joachim, additional, Kaiser, Werner, additional, Sunder-Plassmann, Ludger, additional, and Pamler, Reinhard, additional

Published
2000
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198. Long-term effects of ACE inhibitor on vascular remodelling.

Author

Tuleta, Izabela, Bauriedel, Gerhard, Krämer, Stefan, Nickenig, Georg, and Skowasch, Dirk

Subjects
ACE inhibitors, TRANSLUMINAL angioplasty, PERIPHERAL vascular disease treatment, IMMUNOHISTOCHEMISTRY, ANGIOTENSIN receptors, DENDRITIC cells, LABORATORY rats
Abstract

The long-term pathomorphological changes of the injured vessels under angiotensin-converting-enzyme (ACE) inhibitor are still not known. Therefore, we assessed the alternations of vascular architecture after three-month therapy with ACE inhibitor and identified new target cells for this medication. Carotid arteries of spontaneously hypertensive rats underwent balloon angioplasty. 14 days prior intervention, half of the animals was treated with ACE inhibitor. After three months of vascular trauma, the injured vessels were explored by histomorphology and immunohistochemistry for angiotensin-II receptor (AT1R), dendritic and HSP47+ cells. The neointimal growth decreased significantly only up to 28 days under ACE inhibitor. In contrast, the reductive effect of ACE inhibitor on media area persisted up to three months after intervention. A significant fraction of early neointimal cells was of a dendritic cell type. The relevant portion of these cells showed an expression of AT1R and HSP47. AT1R was present in 70% and HSP47 in 18% of all early neointimal cells in both groups. ACE inhibitor may at least temporarily diminish remodelling processes in injured vessels. The detection of AT1R on dendritic cells identifies these cells as important targets for therapeutic strategies involving modulation of the renin-angiotensin system. [ABSTRACT FROM AUTHOR]

Published
2014
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199. ISOMORPHISM BETWEEN LINEAR CODES AND ARITHMETIC CODES FOR SAFE DATA PROCESSING IN EMBEDDED SOFTWARE SYSTEMS.

Author

RAAB, Peter, KRÄMER, Stefan, MOTTOK, Jürgen, and VAVŘIČKA, Vlastimil

Subjects
ISOMORPHISM (Mathematics), MATHEMATICAL transformations, LINEAR codes, ALGEBRAIC codes, EMBEDDED computer systems
Abstract

We present a transformation rule to convert linear codes into arithmetic codes. Linear codes are usually used for error detection and correction in broadcast and storage systems. In contrast, arithmetic codes are very suitable for protection of software processing in computer systems. This paper shows how to transform linear codes protecting the data stored in a computer system into arithmetic codes safeguarding the operations built on this data. Combination of the advantages of both coding mechanisms will increase the error detection capability in safety critical applications for embedded systems by detection and correction of arbitrary hardware faults. [ABSTRACT FROM AUTHOR]

Published
2014

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