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Dissertation

Extremal Fixpoints for Higher-Order Modal Logic
(2018-10)
In this dissertation, we investigate the interplay between extremal fixpoints and higher-order constructs. The main Focus here is Higher-Order Modal Fixpoint Logic (HFL), an extension of the modal mu-calculus by a simply typed lambda calculus. The resulting logic is very expressive, yet the interplay of its components has not been systematically investigated so far. Goal of this thesis is to characterize the interplay of the components of HFL.
A first characterization is given by converting the denotational semantics ...
Dissertation

Entwicklung eines Nanoimprint-Prozesses zur Herstellung von dreidimensional strukturierten Nanopartikeln mit erhöhter mechanischer Stabilität
(2019)
The nanoimprint technology realizes already the production of two-dimensional (2D) shaped nanoparticles of different shapes and materials. These nanoparticles can be applied in advanced applications in material engineering, as well as in biology and particularly in drug-delivery systems. This work presents three-dimensional (3D) shaped nanoparticles with T-, L- and step-like cross-sections, implemented by substrate conformal imprint lithography (SCIL) and a manual soft-imprint technique. Further, 2D shaped nanoparticles ...
Dissertation

Analyzing Given Names
(2020)
Computer science has evolved so much that it influences almost every part of human live. A particularly personal part of human live is the selection of a given name for a newborn baby. The name discovery service Nameling is our way to help expectant parents with this decision. It is a web service that helps parents to find a given name for their newborn baby. We want to further improve the user experience of Nameling by personalizing its name results for the current user. We deem this important, because the selection ...
Dissertation

Social Network Mining for Analysis of Social Phenomena
(2019)
In den letzten zehn Jahren wurde eine große Menge an Daten über menschliche Interaktionen verfügbar, die entweder aus sozialen Online-Netzwerken stammen oder von tragbaren Geräten erfasst wurden. Die klassischen Sozialwissenschaften bieten keine Instrumente für die Durchführung datengetriebener Forschung mit solchen Daten. Die computerorientierte Sozialwissenschaft (Computational Social Science) versucht, diese Lücke zu schließen, indem sie Methoden für Data-Mining und maschinelles Lernen zur Nutzung der Daten aus ...
Dissertation

Power System Inertia
(2019)
System inertia is the instantaneous power reserve that stabilizes power systems after large-scale disturbances. It declines with increasing renewable generation, causing an increased risk of black-out unless action is taken.
Providing additional inertia will be necessary to maintain security of supply at a reasonable level. To solve the problem of reduced inertia in a reliable and cost-efficient way, this thesis first systematically describes requirements on system level, as basis for the following evaluation of ...
Dissertation

Safety Approach of Detecting Abnormal Events (Spinning and Sliding) in Vehicular Systems
(2021)
The primary theme in the vehicles industry is the increase in automating and integrating more robust intelligent electronic systems to enhance the safe functioning, flexibility, and to extend the virtual productive age of the vehicular systems. Further, significant efforts focus on developing monitoring systems for the abnormal driving conditions such as wheel spinning and sliding that can increase the hazardous in the operating environment and speed up the wearing off process. Thus, these events play a primary role ...
Dissertation

Gast-Partikel in mikroskaligen, dreidimensionalen Wirts-Partikeln: Herstellung durch Nanoimprintlithographie und ihre Charakterisierung
(2020)
Die Verwendung von Partikeln spielt in vielen alltäglichen Bereichen eine essenzielle Rolle und ist daher im Laufe dieses Jahrhunderts immer mehr in den Fokus der Forschung gerückt. Aktuelle Forschungsarbeiten belegen, dass die Größe und Form der Partikel Einfluss auf verschiedene Anwendungen haben. Ein Beispiel ist die Verwendung als Medikamententräger. Forschungen zeigen, dass ellipsoide Partikel langsamer als sphärische Partikel von Makrophagen internalisiert werden und den Transport von Medikamenten innerhalb des ...
Dissertation

Discovering Knowledge in Bipartite Graphs with Formal Concept Analysis
(2019)
Since the 1970s knowledge based approaches are a crucial part of artificial intelligence (AI) research. In this work we investigate data sets in the form of bipartite graphs, i.e., graphs where a bipartition of the vertex set respecting the edge set can be found, for knowledge. To this end we first relate those bipartite graphs to the structure formal context, as used in formal concept analysis (FCA). This link enables us to employ the whole tool-set of FCA to bipartite graphs and therefore, notably, to bipartite ...
Dissertation

Fehlertoleranz und Elastizität für ein Framework zur globalen Lastenbalancierung
(2018-09-10)
Die Anzahl an Rechenknoten in Hochleistungsrechnern wächst stetig. In solchen Systemen nimmt die Bedeutung von Fehlertoleranz zu, da die Wahrscheinlichkeit eines permanenten Knotenausfalls ebenfalls stetig wächst.
Fehlertoleranz gegenüber permanenten Knotenausfällen wird typischerweise durch Checkpointing auf Systemebene realisiert. Findet das Checkpointing jedoch auf Anwendungsebene statt, können Laufzeitvorteile erzielt werden. Diese Implementierungen sind allerdings zeitintensiv und fehleranfällig. Anwendungen, ...
Dissertation
Multilayer Thin-film Structures with Distributed Cavity for Optical Filter and Laser Applications
(2018-12)
This work is aimed at the development of a fabrication process for realization of a chirped filter based laser device (called as coreSEL). Conventional vertical cavity surface emitting lasers (VCSELs) are based on Fabry-Pérot arrangement where the electric field of the resonant mode is mainly located in the cavity region (center) and often causes undesired effects such as mode-jumps. However, coreSEL is based on chirped optical filter which offers a resonant mode with wider spatial distribution of the electric field ...