Using the method of Brownian dynamics, we investigate the dynamic properties of a 2d suspension of active disks at high Péclet numbers using active microrheology. In our simulations the tracer particle is driven either by a constant or an oscillatory external force. In the first case, we find that the mobility of the tracer initially appreciably de...
Emission measurements from unsteady combustion systems such as Pulse Detonation Combustion (PDC) are challenging due to the inherently large variations in pressure, temperature, composition, and flow velocity of the exhaust gas. Comparison of experimental data is additionally complicated by differences in operating conditions and gas sampling setup...
This work analyzes photovoltaic performance as a function of irradiance and temperature in order to improve the energy yield of Cu(In,Ga)(S,Se)2 (CIGS) modules under operating conditions. The analysis utilizes various methodologies, algorithms and models to evaluate the performance of photovoltaic devices. The one diode model (ODM) analytical appro...
Hybrid metal-halide perovskite solar cells have experienced a tremendous development within a short time period. In 2009 the first perovskite single-junction solar cell with a power conversion efficiency (PCE) of 3.8% was presented. Just eleven years later, in year 2020, a PCE of 25.5% was achieved, which approaches the value of silicon single-junc...
Solar cells made from thin layers of polycrystalline silicon (14−15 μm) are the core technology for the work in this thesis. They are made by the deposition of amorphous/nanocrystalline silicon on glass up to a desired thickness (5−40 μm), and crystallization with a line-shaped laser source (referred to as Liquid-phase-crystallized silicon or LPC-S...
Active thermography is a thermal imaging technique that is mainly used in nondestructive testing. Invisible defects in materials, such as cracks or voids, can be detected by actively heating the surface of the material and using a thermal imaging camera. The diffusive nature of heat propagation causes blurring in the acquired thermal images and thu...
The present study examines the possibilities of transferring drag measurement results on reduced-scale train models to the respective full-scale vehicle. A comprehensive experimental and numerical study of the boundary layer and skin friction along trains is performed, focusing on Reynolds number effects. The data are supplemented by an extensive l...
Crystalline-silicon (c-Si) based solar cells are the dominating technology supplying the market of photovoltaic modules presently and a sustainable method of electricity generation. One promising solar cell concept that can boost the efficiency of this technology and is gaining on industrial relevance is the silicon heterojunction (SHJ) solar cell....
Hybrid organic-inorganic perovskites are considered a promising material class for the application in single- and multi-junction solar cells. Prior to the commercialisation of such solar cells, further understanding of the device physics has to be gained. This dissertation addresses the optimisation of perovskite solar cell (PSC) single-junction de...
Um einen effizienten und schadstoffarmen Betrieb moderner Gasturbinen zu ermöglichen, werden diese mit mageren Brennstoff-Luft-Gemischen befeuert. Dabei sind gerade diese mageren Flammen anfällig für thermoakustische Instabilitäten. Bei dieser Kopplung von Druck- und Wärmeschwankungen können im Resonanzfall in der Brennkammer so hohe Schwankungsamp...
