Suche
Anzeige der Dokumente 1-10 von 200
Dissertation
Existence and Regularity Results of a Ferroelectric Phase-Field Model
(2019)
In this thesis, we investigate the existence and regularity results of a ferroelectric phase-field model, which is a state-of-the-art model arising in recent years from the engineering area for the ferroelectric study.
Dissertation
Gold Surface Nanostructuring with Ultrashort Laser Pulses - Study of Non-equilibrium Effects
(2019)
Laser material interaction and structure formation in metals under controlled ultrashort laser pulse conditions are discussed in this work. A novel approach is presented describing the exact amount of energy deposited by a laser pulse in a gold surface, applicable under a variety of structuring conditions. The presented model is validated by a new introduced broad-band pump-probe reflectivity measurement method. A technique also applicable to investigate other phenomenas where 20 fs resolution combined with an octave ...
Dissertation
Rethinking the genus Hyphodontia s.l. (Hymenochaetales, Basidiomycota) – investigations on a worldwide scope including new taxonomy, phylogeny, and identification keys
(2018-12)
The dissertation “Rethinking the genus Hyphodontia s.l. (Hymenochaetales, Basidiomycota) – investigations on a worldwide scope including new taxonomy, phylogeny, and identification keys” was elaborated by Janett Riebesehl in the Department of Ecology at the University of Kassel.
Changing the classification system of the fungal genus Hyphodontia s.l. to treat the species from the broad Hyphodontia s.l. concept by a division into other genera was continued. Hjortstam and Ryvarden (2002, 2009) began the concept, but ...
Dissertation
High-Speed 1.55 µm Quantum Dot Lasers with Electronically Coupled Quantum Well - Dot Active Regions
(2019-07-31)
The expansion of long-distance data communication at a wavelength of 1.55 µm calls for larger data transfer rates. Consequently, an improvement of emission and modulation properties of lasers emitting in this wavelength region is of high interest. The utilization of so-called tunnel-injection (TI) structures in InP-based quantum dot (QD) lasers is promising to fulfill this task. The aim of this thesis was the realization and analysis of TI structures in the lattice matched InP material system and incorporation into ...
Dissertation
Quantum optimal control theory of photoelectron spectroscopy
(2018)
The object of this doctoral thesis is two-fold and can be classified into two, but intrinsically related categories: (i) development of theoretical models for the simulation of electron dynamics and in parallel to this, (ii) method development of efficient numerical algorithms for ad hoc control of photoelectron and photoion-related observables. The first category primarily focuses on the development of a variety of theoretical models describing the interaction of light and matter for the extraction and control of ...
Dissertation
Berücksichtigung von Studierendenvorstellungen zum Thema Gehirn und Lernen in der Lehrkräfteausbildung Biologie
(2019-11)
Lehrer*innenbildung hat das Ziel, Studierende zu Fachleuten für das Lehren und Lernen auszubilden. Zahlreiche empirische Studien zeigen jedoch sowohl bei angehenden als auch praktizierenden Lehrkräften eine hohe Verbreitung von Fehlvorstellungen zum Thema Gehirn und Lernen – sogenannte Neuromythen. Für Biologielehrkräfte ist das Thema Gehirn und Lernen auch als Unterrichtsinhalt relevant. Sie unterrichten Themen wie Bau und Funktion des Gehirns oder Langzeitpotenzierung. Demnach ist es besonders wichtig, dass sie ...
Dissertation
1.55 μm Quantum Dot Lasers for Telecommunication
(2019)
The thesis at hand investigates the suitability of quantum dot (QD) material for use in long-distance coherent communication. The thesis was written in the frame of the SASER project MONOLOP that is aiming for a compact, monolithically integrated light source with a tunable wavelength covering the C+-band and narrow spectral linewidth below 500 kHz.
The thesis reviews the theoretical background of quantum dot material based on the InP material system and distributed feedback (DFB) lasers with lateral gratings as ...
Dissertation
The Navier-Stokes equations with time discretisation and Lagrangian approximation
(2018)
In the present thesis, we combine the Navier-Stokes equations - which correspond to the so-called Eulerian representation of fluid flow - with the Lagrangian description of fluid flow.
Dissertation
Investigation of diamond nanostructures with incorporated color centers
(2018)
Diamond is a material with excellent properties due to its structure and composition. Its crystal lattice is a perfect host of different defect centers, so-called color centers, whose properties, especially the capability of emitting single photons, can serve in quantum information technologies (QIT). As a high refractive index material only a small part of the photons emitted by these color centers in diamond can be collected. To enhance the photon collection efficiency photonic structures are necessary. They can ...