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Modeling contribution to risk assessment of thermal production power for geothermal reservoirs
(2013)
Unsere unternehmerische Umwelt befindet sich in einem zunehmend dynamischen Wandel. Dies führt dazu, dass Herausforderungen, denen sich Unternehmen stellen müssen, immer komplexer werden. Hier gilt es zunehmend, eine Balance zwischen verschiedenen Spannungsfeldern zu erreichen. Sogenannte Megatrends stellen die Treiber dieses Wandels dar. Als Megatrend werden nach dem Zukunftsinstitut (2010a) richtungsweisende Veränderungstendenzen aufgefasst, die alle Bereiche des Lebens sowohl individuell als auch gesellschaftlich beeinflussen und langfristige Auswirkungen haben.
A methodology for assessment, seismic verification and strengthening of existing masonry buildings is presented in this paper. The verification is performed using a calculation model calibrated with the results from ambient vibration measurements. The calibrated model serves as an input for a deformation-based verification procedure based on the Capacity Spectrum Method (CSM). The bearing capacity of the building is calculated from experimental capacity curves of the individual walls idealized with bilinear elastic-perfectly plastic curves. The experimental capacity curves were obtained from in-plane cyclic loading tests on unreinforced and strengthened masonry walls with reinforced concrete jackets. The seismic action is compared with the load-bearing capacity of the building considering non-linear material behavior with its post-peak capacity. The application of the CSM to masonry buildings and the influence of a traditional strengthening method are demonstrated on the example of a public school building in Skopje, Macedonia.
Seismic excited liquid filled tanks are subjected to extreme loading due to hydrodynamic pressures, which can lead to nonlinear stability failure of the thinwalled cylindrical tanks, as it is known from past earthquakes. A significant reduction of the seismically induced loads can be obtained by the application of base isolation systems, which have to be designed carefully with respect to the modified hydrodynamic behaviour of the tank in interaction with the liquid. For this reason a highly sophisticated fluid-structure interaction model has to be applied for a realistic simulation of the overall dynamic system. In the following, such a model is presented and compared with the results of simplified mathematical models for rigidly supported tanks. Finally, it is examined to what extent a simple mechanical model can represent the behaviour of a base isolated tank in case of seismic excitation
Heat production in the windings of the stators of electric machines under stationary condition
(2014)
In electric machines due to high currents and resistive losses (joule heating) heat is produced. To avoid damages by overheating the design of effective cooling systems is required. Therefore the knowledge of heat sources and heat transfer processes is necessary. The purpose of this paper is to illustrate a good and effective calculation method for the temperature analysis based on homogenization techniques. These methods have been applied for the stator windings in a slot of an electric machine consisting of copper wires and resin. The key quantity here is an effective thermal conductivity, which characterizes the heterogeneous wire resin-arrangement inside the stator slot. To illustrate the applicability of the method, the analysis of a simplified, homogenized model is compared with the detailed analysis of temperature behavior inside a slot of an electric machine according to the heat generation. We considered here only the stationary situation. The achieved numerical results are accurate and show that the applied homogenization technique works in practice. Finally the results of simulations for the two cases, the original model of the slot and the homogenized model chosen for the slot (unit cell), are compared to experimental results.
Following earlier studies, we present forward and inverse simulations of heat and fluid transport of the upper crust using a local 3-D model of the Kola area. We provide best estimates for palaeotemperatures and permeabilities, their errors and their dependencies. Our results allow discriminating between the two mentioned processes to a certain extent, partly resolving the non-uniqueness of the problem. We find clear indications for a significant contribution of advective heat transport, which, in turn, imply only slightly lower ground surface temperatures during the last glacial maximum relative to the present value. These findings are consistent with the general background knowledge of (i) the fracture zones and the corresponding fluid movements in the bedrock and (ii) the glacial history of the Kola area.
This paper describes two courses on
simulation methods for graduate students:
“Simulation Methods” and “Simulation and
Optimization in Virtual Engineering” The
courses were planned to teach young engineers
how to work with simulation software as well as
to understand the necessary mathematical background.
As simulation software COMSOL is
used. The main philosophy was to combine
theory and praxis in a way that motivates the
students. In addition “soft skills” should be
improved. This was achieved by project work as
final examination. As underlying didactical principle
the ideas of Bloom’s revised taxonomy
were followed. The paper basically focusses on
educational aspects, e.g. how to structure the
course, plan the exercises, organize the project
work and include practical COMSOL examples.
The 2nd edition of the lightning risk management
standard (IEC 62305-2) considers structures, which may
endanger environment. In these cases, the loss is not limited to
the structure itself, which is valid for usual structures. In the past
(Edition 1) this danger was simply taken into account by a special
hazard factor, multiplying the existing risk for the structure with
a number. Now, in the edition 2, we add to the risk for the
structure itself a “second risk” due to the losses outside the
structure. The losses outside can be treated independently from
what occurs inside. This is a major advantage to analyze the risk
for sensitive structures, like chemical plants, nuclear plants, or
structures containing explosives, etc. In this paper, the existing
procedure given by the European version EN 62305-2 Ed.2 is
further developed and applied to a few structures.
Risk management for structures with a risk of explosion should be considered very carefully when performing a risk analysis according to IEC 62305-2. In contrast to the 2006 edition of the standard, the 2010 edition describes the topic “Structures with a risk of explosion” in more detail. Moreover, in Germany separate procedures and parameters are defined for the risk analysis of structures with a risk of explosion (Supplement 3 of the German DIN EN 62305-2 standard). This paper describes the contents and the relevant calculations of this Supplement 3, together with a numerical example.
Am 1. Oktober 2013 ist das auf drei Jahre angelegte EU-Forschungsprojekt INSYSME – Innovative Systeme für erdbebentaugliche Ausfachungswände aus Ziegelmauerwerk in Stahlbetonrahmentragwerken – gestartet. Unter der Koordination der Universität Padua beteiligen sich 16 Partner aus sechs europäischen Ländern (Deutschland, Griechenland, Italien, Portugal, Rumänien, Türkei). Als deutsche Partner nehmen die Arbeitsgemeinschaft Mauerziegel aus Bonn, die Universität Kassel sowie das Ingenieurbüro SDA-engineering GmbH aus Herzogenrath, teil. Ziel der deutschen Partner ist die Entwicklung von innovativen Ausfachungssystemen aus monolithischem wärmedämmenden Ziegelmauerwerk, mit denen nicht nur eine erhöhte Erdbebensicherheit, sondern auch die sichere Erfüllung der steigenden Anforderungen aus Windbeanspruchungen gewährleistet werden können. Die Forschungsergebnisse sollen vom Partner SDA-engineering GmbH in die bereits seit einigen Jahren verfügbare Softwarelösung MINEA [1] integriert werden. Weitere Informationen stehen auf den Websites des Projektes [2] zur Verfügung. Im vorliegenden Beitrag werden nach einer kurzen thematischen Einführung die Ergebnisse von Tastversuchen an senkrecht zur Ebene belasteten Ausfachungswänden aus Planziegelmauerwerk vorgestellt. Im Anschluss wird das geplante Arbeitsprogramm der deutschen Partner im Projekt INSYSME beschrieben.
Die Erdbeben in Albstadt 1978 (Magnitude 5,7), Roermond 1992 (Magnitude 5,9) oder in Waldkirch 2004 (Magnitude 5,1) haben verdeutlicht, dass die erdbebensichere Auslegung von Mauerwerksbauten auch in Deutschland von großer Bedeutung ist. Bereits im Jahr 1981 wurde die DIN 4149 (1981) “Bauten in deutschen Erdbebengebieten – Lastannahmen, Bemessung und Ausführung üblicher Hochbauten“ eingeführt, in der aber für Mauerwerksbauten nur wenige Anforderungen gestellt wurden. Diese Norm wurde durch den NABau-Arbeitsausschuss “Erdbeben; Sonderfragen“ des Deutschen Instituts für Normung e.V. (DIN) auf Grundlage des Eurocode 8 (2004) vollständig überarbeitet und durch die DIN 4149 (2005) abgelöst, die umfangreiche Regelungen für die seismische Auslegung von Mauerwerksbauten enthält. Mittlerweile liegen die DIN EN 1998-1 (2010) und der Nationale Anhang DIN EN 1998-1/NA (2011) vor, die nach Einarbeitung der Ergebnisse der durchgeführten Anwendungserprobung bauaufsichtlich eingeführt und die DIN 4149 (2005) ersetzen werden. Der folgende Beitrag gibt einen Überblick über die seismische Berechnung und Bemessung von Mauerwerksbauten nach dem europäischen Regelwerk und illustriert deren Anwendung an einem baupraktischen Beispiel.