Bøker utgitt av Cuvillier

The separation of isotopes has always been a challenge because of their identical size, shape and thermodynamic properties. Nowadays, the extraction of deuterium is performed e.g. by the Girdler Sulfid process or cryogenic distillation, which lead to low separation factors (below 2.5) in combination with high energy costs. The standard way to produce helium-3 is to skim it as a byproduct of the radioactive tritium decay.In this thesis, two alternative approaches have been investigated for the separation of light isotopes, Quantum Sieving and Chemical Affinity Sieving . While Quantum Sieving is based on confinement in small pores, Chemical Affinity Sieving relies on strong adsorption sites. Both methods use the mass difference of the isotopes, which is related to their zero-point energy.The microporous metal-organic frameworks are excellent candidates for studying these quantum effects due to their well-defined pore structure and the possibility to introduce strong adsorption sites directly into the framework. The samples have been exposed to an isotope mixture and the adsorbed quantity of each isotope was detected by low-temperature thermal desorption spectroscopy (TDS). The ratio of the desorbed amount of the isotopes leads directly to the selectivity (separation factor). The selectivity is determined as a function of exposure time and temperature and exhibits the highest value of 25 observed for hydrogen isotopes at temperatures well above the boiling point of liquid nitrogen.

Variations in insulin regulation reflect either as tissue insulin resistance or insulin dysregulation result in moderate to severe hyperinsulinemia in horses and ponies suffering from the Equine Metabolic Syndrome (EMS). Several pathomechanisms provoking equine insulin resistance have been suggested, but insulin signaling in healthy horses has not been studied in detail so far. Thus the objective of this PhD project was to investigate equine insulin sensitivity, glucose homeostasis and lipid metabolism by combining examinations of insulin signaling on a protein level in different main metabolic tissues and analyses of dynamic hormone and metabolite changes during acute stimulations by either oral glucose application or IV insulin and glucose injection. Furthermore, systemic markers of insulin resistance were analyzed by an innovative targeted metabolomics approach to provide better understanding of potential pathomechanisms involved in impaired insulin regulation in horses. In conclusion, equine-specific insulin signaling, the marginal relationship of insulin sensitivity to obesity and strong associations of high plasma insulin concentration to cellular oxidative stress depicted not only a special physiological condition but also indicate novel pathophysiological conditions underlying EMS.

Magnetic nanostructures in thin films and their behavior have seen a drastic increase in scientific interest in the last decades. Similarly, X-ray microscopy has moved into the spotlight since the turn of the century. This thesis combines both topics with the investigation of magnetic vortex structures under pulsed field excitation using both micromagnetic simulations and time resolved magnetic X-ray microscopy. This allowed the observation of vortex core polarization switches with

This dissertation investigates the impact of the European regulatory measures MAD (Market Abuse Directive, introduced in 2003) and MiFID (Markets in Financial Instruments Directive, introduced in 2004) on the behaviour and information environment of sell-side financial analysts. The MAD and the MiFID are, amongst other objectives, geared up for the mitigation of conflicts of interest in the field of the financial analysts' investment research and the prohibition of selective disclosures. The impact of the regulatory measures is examined by using the common sell-side financial analysts' quantitative outputs target prices, earnings forecasts and stock recommendations. The main results of the empirical analysis imply that the regulatory measures induced conflicted sell-side analysts to avoid the intended impacts of the regulatory measures when issuing target prices. Moreover, the regulatory measures, which should prevent selective disclosures, can have unintended consequences, too.

This work proposes methods for modeling the acoustic behavior of induction machines as well as optimization approaches for the control of the acoustic behavior. The aim of this work is to simplify and improve the quality of the acoustic modeling of induction machines and to show possible optimization measures in order to make the application and its understanding accessible to a broader group of users. In this work, approaches for the efficient modeling of harmonic phenomena in the electromagnetics of induction machines are shown and analyzed. This work focuses on the development of efficient geometric models for the calculation of electromagnetics of induction machines, which are substantially based on analytical equations and are used in an extended simulation via numerical methods. Subsequently, a method for the acoustic calculation of the vibrations resulting from the electromagnetic force excitation on the surface of the housing of the electrical machine is presented. The approach for the calculation of the surface vibrations is based on the system simulation and the vibration synthesis approach. The presented method offers the possibility to present extensive and realistic models and can therefore contribute to the optimized design of induction machines and many other types of electric drive systems. The procedure consists of a two-stage process, whereby a distinction is made between an offline calculation, as a prediction for model parametrization and for the calculation of the electromagnetic behavior as well as an online calculation, which includes the actual acoustic calculation. Based on this efficient calculation method, control and sensor influences as well as spatial harmonics and inverter switching frequency orders can be analyzed and optimized. In addition, two methods are presented, which refer exclusively to the changes of the software and their parametrization of the electric drive system. On the one hand, this work presents a procedure which improves the acoustic behavior by changing the operating point at constant torque and speed of the electric drive. Another method describes the injection of voltage pulses to generate harmonic current oscillations, which counteract with the excitation of occurring vibrations and thus contribute to the reduction and optimization of the acoustic behavior of the induction machine and thus of the electric drive train. Underlining the results of the presented methods, the results of the simulation models are proposed and compared to measurements.

Die Festschrift ¿Kartvelology, Kartosphere, Kartophony¿ (Language, Culture, Identity) stellt einen Sammelband dar, der die wissenschaftlichen Beiträge aus den thematisch miteinander flankierenden Bereichen wie Linguistik der Kartvelsprachen (Georgisch, Megrelisch, Lazisch, Tchanisch), georgische Literatur, georgische Geschichte und Bizantinistik beinhaltet. Die Artikel haben überwiegend empirische Natur und sind auf die Analyse von Sprachdaten bzw. Archivmaterialien basiert. Methodisch decken die Abhandlungen klassische Desktiptivistik, Komparatistik sowie Korpuslinguistik und Feldforschung ab. Die Festschrift ist der georgischen Kartvelologin Emeritus Prof. Jujuna Peikrishvili gewidmet. Auch aus diesem Grund stehen nach allen Beiträgen die einseitigen georgischsprachigen Resümees sowie die akademische Biografie von Prof. Peikrishvili am Ende des Bandes.

Companies across a wide range of industries are affected by the increasing relevance of digital innovation and their related organizing challenges. Against this background, it is unclear how this influences the role of the established IT function in incumbent firms. Although digital innovations require IT-related knowledge and capabilities, the corporate IT function seems unprepared with regards to their organizational structure and capabilities.Therefore, this cumulative dissertation comprises four individual studies at the intersection of digital innovation and the IT function. These studies mainly address the following research goals: (1) to understand how the increasing prevalence of digital innovation is changing the IT function¿s organizing logics, and (2) to understand how the IT function can contribute to the effective and efficient development of digital innovations.On the one hand, the thesis shows that digital innovation projects can trigger new value commitments of IT functions regarding their organizing logic. On the other hand, the results implicate that IT functions require sufficient organizational support and decision rights, as well as organizational agility and ambidexterity, to successfully contribute to their firms¿ digital innovation activities.

After the occurrence of a disaster (e. g. an earthquake or tsunami) one of the main needs for the rescue teams and volunteer helpers is a functional communication infrastructure even during the first hours. The disaster recovery system (DRS) which is proposed in this work is based on an IEEE 802.11s wireless mesh network which is set up by non-damaged, legacy, mesh capable and battery powered devices still available in the disaster region. Key considerations concerning the performance of a DRS are the required node density, the coverage that can be achieved by a given node density, scalability as well as the lifetime of the system. For lifetime of the system. For lifetime enhancement, which is a key challenge for the proposed DRS on battery powered devices, a distributed algorithm is proposed which enhances the lifetime of such a system by an approach which allows to shut down non-necessary nodes and to keep them for a later usage while still keeping network connectivity.