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Dissertation
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Optimal Control of Quantum Information Tasks in Open Quantum Systems
(2020-07-30)
Every quantum system inevitably interacts with its environment. This is a fundamental requirement that allows us to control, measure and, in general, interact with quantum systems. In that respect, a quantum system's openness can be interpreted as prerequisite that enables quantum technologies in the first place. The latter are built to harness the intrinsic quantum mechanical behavior of quantum devices in order to build new, powerful technologies. However, a quantum system's openness also causes it to interact ...
Dissertation
High temperature-stable InGaAs QDs for the monolithic integration in external-cavity surface-emitting lasers
(2021)
Optically pumped vertical external-cavity surface-emitting lasers (VECSELs), also called semiconductor disk lasers (SDLs), benefit from the flexibility and versatility of the semiconductor material. With a simple cavity layout, fundamental transverse mode operation with a circular output beam and high beam quality is possible. They have excellent heat-sink properties and only require inexpensive multimode diode lasers for pumping. The complete VECSEL structure is only a few micrometers thick which leads to a strong ...
Dissertation
Designing Breeding Programs For Improving Milk Yield Performance Of Indigenous Genous Dairy Cattle In Sudan
(2022)
The overall aim of the present study was to design appropriate breeding programs for the sustainable improvement of Butana cattle in Sudan. Four studies were conducted, beginning with a comprehensive review of literature on indigenous dairy cattle breeding strategies in sub-Saharan Africa with a focus on the factors that contribute to their success or failure. It showed that crossbreeding of indigenous breeds with exotic breeds has been widely used for genetic improvement, but it largely failed under low-input ...
Dissertation
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Taking a Closer Look at the Desirability of Desirable Difficulties - Additionally Focusing on Required Prerequisites, Negative Side-Effects, and Negative Consequences
(2022)
As the title of my dissertation already indicates, the main purpose of the following work was to take a closer, more thorough, and encompassing look at the desirability of desirable difficulties. The term desirable difficulties thereby subsumes varying types of difficult, demanding, and challenging learning strategies—like the application of (learning/practice) tests and generation tasks: Working on and successfully solving those difficult tasks requires more (cognitive) effort compared to working on easier learning ...
Dissertation
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Validation of a generalized model for the description of polycrystalline exchange-biased magnetic thin films
(2022)
Applications based on nano- and microscaled systems have become indispensable in many aspects in everyday life, industry, research and medicine. In this regard, thin film technology plays a crucial role with the physical properties of solids changing significantly when they are reduced to thin layers with thicknesses in the nanometer range. In this regime, a solid’s microstructure as well as boundary and surface effects start to dominate. A prominent example is the exchange bias effect, which results due to the ...
Dissertation
Entwicklung einer vereinfachten europaweit anwendbaren Methodik zur Festlegung von Effizienzanforderungen an Wärmerückgewinnungssysteme in der Raumlufttechnik für Nicht-Wohngebäude auf der Grundlage mehrdimensionaler Optimierungsberechnungen
(2022)
Die vorliegende Dissertation beschäftigt sich mit der Anpassung der EU-Verordnung 1253/2014, welche die Effizienzkriterien an die WRG von RLT-Geräten in NWG festlegt. Die Verordnung definiert die Anforderungen als starre Grenzwerte, die vom Süden bis zum Norden Europas gelten ohne den jeweiligen Standort oder die Gebäudenutzung zu berücksichtigen. Gemäß den Referenzwerten der aktuellen Verordnung wurde eine Verschärfung des Anforderungsniveaus diskutiert, wobei auch hier zunächst starre Grenzwerte geplant waren. Der ...
Dissertation
Zusammenhang der Nutzungshäufigkeit mit der Wirksamkeit eines angeleiteten Online-Selbsthilfeprogramms bei depressiven Patienten
(2022)
Zusammenhang der Nutzungshäufigkeit mit der Wirksamkeit eines angeleiteten Online-Selbsthilfeprogramms bei depressiven Patienten:
Die Deprexis-Studie, die Basis meiner Arbeit ist, hat gezeigt, dass eine webbasierte Selbsthilfe als Ergänzung zur multimodalen stationären psychotherapeutischen Behandlung den Verlauf der depressiven Symptome verringern kann und so die Wirkung der stationären Psychotherapie durch die Integration einer zusätzlichen Online-Intervention verbessert. Eine Stichprobe von 115 Patient*Innen, ...
Dissertation
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Praktische Anwendung von aktiver Vormagnetisierung in transformatorlosen DC/DC-Konvertern
(2022)
Magnetic devices are used in almost every power electronic system. Therefore, their purpose and with that their requirements can vary in a wide range. The consequence is a large number of options regarding the priority of optimisation. In this work, the focus is on reducing the volume or weight of inductors in transformerless DC-DC converters. Active prmeagnetization is choosed as an optimisation approach. The technique enables an operation of the DC-DC-converter in the Triangular Current Mode (TCM), whereby ...
Dissertation
A Multi-Perspective Investigation of the Innovation Process: Dynamics, Regulation, and Integration of Concepts
(2021)
This dissertation provides insight into how individuals and teams address the complex and dynamic nature of innovation processes. Focusing on affect and self-regulation, the dissertation investigates how and why regulation efforts of individuals and teams may be beneficial for both innovative activities (i.e., idea generation and implementation) and innovative strategies (i.e., exploration and exploitation). Further, it addresses the issue of conceptual variety in innovation research and examines to what extent ...
Dissertation
Neo-institutionalism and business sustainability in emerging economies
(2022)
This dissertation deals with the institutional environment surrounding the private sector in the various emerging markets and developing economies (EMDEs) worldwide where most of the global population lives. Its primary purpose is to identify and combine theoretical aspects of new (sociological) institutionalism/neo-institutionalism to better understand the role of institutional environments in shaping business impacts on sustainable development. Institutions shape the behaviour of individuals as well as entire groups ...