Ph.D. Theses

The synthesis of polyacrylonitrile-based carbon nanofibers consists of the steps of electrospinning, thermal stabilization, carbonization and frequently an optional activation. This work focusses on the impacts of thermal stabilization and KOH activation on the pore structure and the CO2 adsorption properties of carbon nanofibers. [...]

The urgent need to address climate change has accelerated the global transition from fossil fuels to renewable energy sources, with photovoltaics (PV) emerging as the fastest-growing technology in this field. By 2023, PV systems accounted for three-quarters of newly installedrenewable energy systems, highlighting their central role in meeting global climate targets. [...]

The wave-driven Brewer-Dobson circulation plays a crucial role in transporting radiatively active trace gases and aerosols through the stratosphere, which, in turn, impact the Earth’s radiation budget. A detailed understanding of this transport, particularly within a changing climate, is therefore critical. [...]

Transitioning towards greenhouse-gas-neutral energy systems and economies relies critically on renewable energy technologies. Hydrogen is indispensable both as an energy carrier and as a chemical reactant, and water electrolysis powered by renewable sources is a key pathway. [...]

Hydrogenated amorphous silicon (a-Si:H) and silicon carbide (a-SiC:H) thin films are essential materials for optoelectronic and photovoltaic devices. High-quality layers of these materials are typically produced using vacuum-based deposition techniques, such as plasma enhanced chemical vapor deposition (PECVD). [...]

Der Individualverkehr mit PKW ist ein wichtiger Bestandteil der deutschen Wirtschaft. Als Treibstoffe werden Kohlenwasserstoffe auf Erdölbasis verwendet, die bei der Verbrennung in Motoren neben anderen Abgasen Kohlenstoffdioxid erzeugen. [...]

The rapid growth of information technology (IT), which will continue to increase in the future thanks to applications of artificial intelligence (AI), is generating an exponential rise in energy consumption by IT. Mitigating this increase requires significantly more energy-efficient information storage and processing than the classic von Neumann architectures based on complementary silicon semiconductor technology (CMOS). [...]

Land–atmosphere coupling, which represents the exchanges of water, energy and momentum between the land surface and atmosphere, plays a central role in shaping regional hydroclimate variability and climate extremes. These influences are transmitted through a chain of linked processes connecting soil moisture, evapotranspiration, boundary-layer development, cloud formation, and precipitation. [...]

In dieser Arbeit wird ein gemischt-ganzzahliges Optimierungsproblem zur Nominierungsvalidierung (NoVa) präsentiert und eingesetzt, um eine szenariobasierte Betrachtung möglicher Betriebszustände in Wasserstoff- und Erdgasinfrastrukturen durchzuführen. Zum einen wird das Modell eingesetzt, um mögliche Betriebszustände und Engpässe im von den Fernleitungsnetzbetreibern Gas im Rahmen des Netzentwicklungsplan Gas 2020 (NEP-Gas 2020) antizipierten initialen Wasserstoffnetz bis 2025 und bis 2030 zu analysieren. [...]