Although a superconductor has zero resistivity when carrying a direct current, losses do occur when it is exposed to an alternating magnetic field and/or is carrying an alternating current. The magnitude of these so-called AC losses depends on the operating temperature, the amplitude and the direction of the magnetic field, the transport current, and the frequency. Therefore, the use of high-temperature superconductors, HTSs, in electric power components such as cables, transformers or reactors, requires knowledge of the AC losses. This thesis deals with the development of AC loss models for HTSs, mainly for Bi-2223 tapes. In particular, the orientation of the applied magnetic field is taken into account in the modelling. The basis for the models is the results of experimental investigations. The basic concepts of HTSs with special emphasis on the modelling of AC losses are presented. These can be broken down into several components. Their sources and natures are described. One of the components is the hysteretic loss and it is the dominating loss in AC applications at power frequencies. Therefore, the other loss components are neglected in the modelling. Models are presented and the associated parameters are investigated with respect to their dependence of the magnetic field as well as the temperature. The AC losses for parallel and perpendicular magnetic field with respect to the wide side of the tape are calculated numerically. Moreover, a semi-empirical model for intermediate angels of the applied magnetic field is proposed. The comparisons show good agreement with experimental results. Keywords: High-temperature superconductors, AC loss modelling, hysteresis, E-J characteristic. / <p>QCR 20161026</p>

<p>Although a superconductor has zero resistivity when carrying a direct current, losses do occur when it is exposed to an alternating magnetic field and/or is carrying an alternating current. The magnitude of these so-called AC losses depends on the operating temperature, the amplitude and the direction of the magnetic field, the transport current, and the frequency. Therefore, the use of high-temperature superconductors, HTSs, in electric power components such as cables, transformers or reactors, requires knowledge of the AC losses.</p><p>This thesis deals with the development of AC loss models for HTSs, mainly for Bi-2223 tapes. In particular, the orientation of the applied magnetic field is taken into account in the modelling. The basis for the models is the results of experimental investigations.</p><p>The basic concepts of HTSs with special emphasis on the modelling of AC losses are presented. These can be broken down into several components. Their sources and natures are described. One of the components is the hysteretic loss and it is the dominating loss in AC applications at power frequencies. Therefore, the other loss components are neglected in the modelling.</p><p>Models are presented and the associated parameters are investigated with respect to their dependence of the magnetic field as well as the temperature. The AC losses for parallel and perpendicular magnetic field with respect to the wide side of the tape are calculated numerically. Moreover, a semi-empirical model for intermediate angels of the applied magnetic field is proposed. The comparisons show good agreement with experimental results.</p><p><b>Keywords:</b> High-temperature superconductors, AC loss modelling, hysteresis, E-J characteristic.</p>

The invention of closed circuit television (CCTV) has initiated a new trend in high security by video surveillance. More recently, CCTV cameras have been incorporating wireless LAN technology for data transfer purposes by using on chip memory storage until the time of update. In this thesis, short range communication such as Bluetooth low energy (Bluetooth smart) is used in order to perform simple I/O applications. The two important components of the project are the camera and the Bluetooth module box. An external antenna is designed for the connectivity box and the operating range of the box is deduced by using link budget. The blue cool connectivity box is assessed by defining the capabilities of the box, i.e., simple I/O operations. Field test measurements for the designed antenna provide optimum communication range. The thesis also reviews software simulation tools that are essential for antenna design and path loss modelling. The efficiency of simulated measurements versus real-time measurements are also assessed. The primary target of the thesis is to detail the design of a cost-effective antenna based on link budget calculations and perform basic I/O tasks wirelessly between the blue cool connectivity box and the camera. It is concluded that in future works, advanced operations can be added on to the existing model. It is also suggested that a model for multi floor communication can be designed.

Die vorliegende Habilitation beschäftigt sich mit verschiedenen Aspekten des Hochwasserrisikos in Deutschland. In zwölf Artikeln werden neue wissenschaftliche Erkenntnisse über Hochwassergefahren, über Faktoren, die Hochwasserschäden beeinflussen, sowie über effektive private Vorsorgemaßnahmen präsentiert. So wird die jahreszeitliche Verteilung von Hochwasser in ganz Deutschland gezeigt. Weiterhin werden mögliche Auswirkungen des Klimawandels auf Abflussverhältnisse und Häufigkeiten von Hochwasserereignissen am Beispiel des Rhein-Einzugsgebietes abgeschätzt. Ferner wird am Niederrhein simuliert, welche Auswirkungen Deichbrüche haben können. Hochwasserschäden stehen im zweiten Teil der Arbeit im Fokus: Nach dem August-Hochwasser 2002 wurden ca. 1700 Privathaushalte telefonisch befragt. Damit konnten die Einflüsse verschiedener Faktoren, wie der Überflutungsdauer oder der Verunreinigung des Hochwassers mit Öl, auf die Höhe von finanziellen Schäden quantifiziert werden. Daraus ist zum einen ein neues Modell entstanden, mit dem Hochwasserschäden großräumig berechnet werden können. Zum anderen konnten Hinweise für die Verbesserung der privaten Vorsorge abgeleitet werden. Beispielsweise zeigte sich, dass versicherte Haushalte schneller und besser entschädigt werden als Nicht-Versicherte. Ebenfalls wurde deutlich, dass verschiedene Bevölkerungsgruppen, wie Mieter und Hauseigentümer, unterschiedliche Möglichkeiten haben, Vorsorge zu betreiben. Dies ist zukünftig in der Risikokommunikation zu berücksichtigen. In den Jahren 2005 und 2006 waren Elbe und Donau wiederum von Hochwasser betroffen. Eine erneute Befragung von Privathaushalten und Behörden ermöglichte, die Verbesserung des Hochwasserrisikomanagement und der Vorsorge am Beispiel der Stadt Dresden zu untersuchen. Viele Methoden und Erkenntnisse dieser Arbeit sind in der wasserwirtschaftlichen Praxis anwendbar und tragen somit zur Verbesserung der Hochwasserrisikoanalyse und des Risikomanagements in Deutschland bei. / This thesis deals with different aspects of flood risk in Germany. In twelve papers new scientific findings about flood hazards, factors that influence flood losses as well as effective private precautionary measures are presented. The seasonal distribution of flooding is shown for the whole of Germany. Furthermore, possible impacts of climate change on discharge and flood frequencies are estimated for the catchment of the river Rhine. Moreover, it is simulated at reaches of the Lower Rhine, which effects may result from levee breaches. Flood losses are the focus of the second part of the thesis: After the flood in August 2002 approximately 1700 households were interviewed by telephone. By this, it was possible to quantify the influence of different factors such as flood duration or the contamination of the flood water with oil on the extent of financial flood damage. On this basis, a new model was derived, by which flood losses can be calculated on a large scale. On the other hand, it was possible to derive recommendations for the improvement of private precaution. For example, the analysis revealed that insured households were compensated more quickly and to a better degree than uninsured. It became also clear that different groups like tenants and homeowners have different capabilities of performing precaution. This is to be considered in future risk communication. In 2005 and 2006, the rivers Elbe and Danube were again affected by flooding. A renewed pool among households and public authorities enabled us to investigate the improvement of flood risk management and the precaution in the City of Dresden. Several methods and finding of this thesis are applicable for water resources management issues and contribute to an improvement of flood risk analysis and management in Germany.

Modeling of extreme events is a challenging statistical task. Firstly, there is always a limit number of observations and secondly therefore no experience to back test the result. One way of estimating higher quantiles is to fit one of theoretical distributions to the data and extrapolate to the tail. The shortcoming of this approach is that the estimate of the tail is based on the observations in the center of distribution. Alternative approach to this problem is based on idea to split the data into two sub-populations and model body of the distribution separately from the tail. This methodology is applied to non-life insurance losses, where extremes are particularly important for risk management. Never the less, even this approach is not a conclusive solution of heavy tail modeling. In either case, estimated 99.5% percentiles have such high standard errors, that the their reliability is very low. On the other hand this approach is theoretically valid and deserves to be considered as one of the possible methods of extreme value analysis.