The approach to access control migration used in this thesis is the creation of a graph-based access control model as an intermediate step in the migration process. The graph-model designed to be a common model of all involved mechanisms, enabling access control to be migrated from the graph to another mechanism, independent of which mechanism a graph was created from. This allows for the migration between any mechanisms represented by a given graph-model, but also for the comparison of the access granted by the different mechanisms.

A special ability of stimuli-responsive gels is the reversible solvent uptake in response to the influence of external stimuli, which has great potential for technical applications. However, this behaviour has not yet been researched. To achieve a better understanding of the chemo-responsive behaviour of gels, the swelling behaviour of poly-N-isopropylacrylamide (PNIPAAm) in different solvents and solvent compositions was investigated in this work. For this purpose, the swelling behaviour of PNIPAAm in various pure substances of the substance classes of carboxylic acids, alcohols and esters was first considered. It was found that hydrophilic and polar properties of the solvents cause positive swelling behaviour, while hydrophobic properties have a negative effect on the swelling behaviour. In addition, the swelling behaviour was investigated as a function of the reaction progress in various esterification reactions. High degrees of swelling were obtained up to high conversions, followed by a sharp decrease at complete conversion, indicating a dominant influence of the polar solvents. It was also recognised that with increasing length of the acid residue or alcohol residue, the influence of the other residue on the swelling behaviour decreased. Furthermore, it must be considered that the thermodynamic swelling equilibrium is superimposed by the swelling kinetics. This is noticeable from the molecular sizes. As the chain length of the residues increases, it can be assumed that the esters diffuse out of or into the gel matrix more slowly, which could lead to the reaction mixtures with short-chain esters showing an increase in the degree of swelling at high conversion rates.

This paper is about the question whether court rulings can be used as evidence for Social Engineering research. It goes into the methodology of acquiring and analysing the material and presents the results.

Constant-time implementations are a popular approach for defending against cache-timing attacks. It is necessary to verify the resulting executables of such implementations, because the compiler might introduce timing side-channels during code optimization, leaving the program vulnerable even though the source code has no indication of possible timing side-channels. This thesis proposes a novel approach for formally verifying executables to be constant-time, by developing a type system for scVerif's low-level, assembly-like intermediate language, which features explicit leak statements. The resulting type checker can detect timing side-channels for arbitrary leakage models, including data-dependent instruction timings. However, the implementation needs further work before it can be applied on real world cryptographic implementations. Once a better implementation of the approach exists, it can easily be used for automatic checks of executables for cache-timing side-channels. Users only have to specify the initial secrecy of every variable using easy to use source code comments.

This thesis describes and shows results of a method for comparing the computational resources required by different modelling tools to optimise energy system models. The method relies on a software called Tessif, a framework that unifies the data input and output of multiple Free and Open Source Software (FOSS) energy system modelling tools. Multiple energy system models are created in tessif through which they are then transformed to and optimised with each of the investigated modelling tools, which are Calliope, Fine, Oemof and Pypsa. The time elapsed while doing this and the memory usage are measured. Additionally the number of constraints that are used by the modelling tools to describe the models are recorded. The number of constraints can be used to assess the complexity of a model and is used in this thesis to allow the comparison of results of different energy system models. The measurements show that with the exception of Calliope the resource usage for the investigated modelling tools scales linearly and is on a relatively similar level. Both Calliope’s memory usage and the required time are significantly higher. The measurements further show that the difference in resource usage directly correlates with the difference in the number of constraints with the exception of Calliope’s memory usage which increases quadratically while the corresponding number of constraints only increases linearly.

The present scientific work was created in context of the project Tessif which provides a comparison of different "Free Open Source Energy System Modelling Software" (FOSESMS). The thesis develops a statistical method to differ the in Tessif implemented FOSESMS based on their results. This uses various statistical analysis methods such as Pearson correlation and cross-correlation in combination with model errors such as mean absolute error, mean bias error and root mean square error. Within two scenario an exemplary application of the method is then tested using the software tools oemof and PyPSA.

The present scientific work develops a method for comparing "Free Open Source Energy System Simulation Software" (FOSESSyS). A data sheet is generated on the basis of which the comparison takes place. With the help of a case study, an exemplary implementation of the method is then presented. Within this case study, a model of the electricity and heating network of the City of Hamburg created and examined using the software tools oemof and PyPSA. For this purpose, suitable scenarios are developed based on current emission targets. The data required to parameterize the model are obtained exclusively from open data sources. Any processing is done using "Free Open Source Software". The present work thus contributes to the "Open Science" movement.

Lagrangian Sensor Particles are essential in gaining knowledge about process conditions inside of Single-Use Stirred Tank Bioreactors. To facilitate this, the particles should follow the flow of the fluids inside of the reactor. However, so far it has not been possible to validate their internal means of trajectory determination. To address this problem, in this thesis the positions of LED-equipped tracking particles, called LED Motes, in a 200 L Continuously Stirred Tank Reactor made of acrylic glass are measured visually and their velocities and accelerations calculated. To this end, LED Motes are designed and manufactured. A mote recognition script as well as a script for removal of distortions in the image through geometric calibration for MATLAB is developed to complement scripts for the calculation of velocity and acceleration values from positional data. Experiments are performed utilizing two different stirrer setups, one consisting of a Rushton turbine impeller and a pitched blade impeller and the other consisting of two pitched blade impellers. The experiments are performed without aeration and with an aeration rate of 15 l min^-1 and 20 l min^-1 using both a micro and a macro sparger. Thus, a total of 10 combinations of experimental parameters are achieved not accounting for variations in stirrer speed. Experiments utilizing every combination of experimental parameters are performed at four different stirrer speeds of 50, 70, 100 and 120 RPM for a total of 40 experiments. A high proportion of theoretically possible LED Mote positions are recognized. Only positions that can be assigned to a track of a length of more than 5 positions are evaluated for the calculation of velocity and acceleration values. Up to 94 % of the recognized positions are assigned to such a track. However, for the low-visibility, aerated, cases the percentage of positions assigned to tracks long enough to allow for evaluation is lower, reaching as low as 66 %. For the majority of experiments the percentage of positions used for calculations lies between 80 % and 90 %. The results show that the tracking of the 2D positions of LED Motes can lead to a good understanding of the dominant flow phenomena inside of a CSTR. The highest calculated mean velocity magnitudes for a single 62~mm by 60~mm interrogation window are approximately half of the stirrer tip speed. The expected flow patterns for the different stirrer types are observed. The Rushton turbine impeller causes high radial velocities while the pitched blade impellers cause high axial velocities. A good resolution of velocity and acceleration data can be achieved even with short experimental run times of only 120~s. However, for the aerated case, obscuration of the LED Motes reduces the quality of the results. A longer experimental run time and an increase in LED-brightness can increase the quality and resolution of the evaluation results even further. Usefulness and quality of data can be increased by the development of 3D tracking techniques using two cameras or a mirror setup to achieve two different viewpoints of the reactors instead of evaluating a single point of view. For this, the produced script lays a solid foundation.

Many chemical and biological liquid phase reactions require gaseous components provided by aeration via gassed stirred tanks. For fast chemical and biological reactions mass transfer from the gas to the liquid phase is often limited making a continuous process optimisation necessary. For this process optimisation, the mass transfer is usually quantified in the laboratory via the volumetric mass transfer coefficient kLa using the measurement method of gas stripping with nitrogen. The present work focuses on the characterisation of counter-diffusion effects and their influence on mass transport. The influence of different stripping gases on the determination of the kLa-value is particular important. The basis of this work is a 2 L stirred reactor and three gassing devices (opentube, L-sparger and sintered frit). These sparger can be differentiated primarily by their bubble size and shape. The analysis of mass transfer with different degassing methods is performed by the oxygen kLa-value for different gas volume flows and gassing devices. The reaction medium is stripped via nitrogen or argon. A physically degassed medium is used as well. In addition to mass transport measurements, endoscopic measurements are used to record the micro-bubbles generated by the sintered frit. As a key-result of the investigations, the physically degassed medium shows 56% higher mass transport rates than the medium desorbed with nitrogen. The main reason is the counter-diffusion and the resulting lower oxygen partial pressure in the bubbles, which has a negative influence on the mass transport. Moreover, the counter-diffusion effects increase with higher gas solubility of the stripping gas and mass transfer rate of oxygen decreases. In addition, the endoscopic measurement data and the kLa-values were used to calculate the respective mass transfer coefficients kL. These are characteristic for each degassing method. On the basis of the kLa-values a model for quantifying the counter-diffusion effects could be developed.

In the course of the ever-increasing growth of cities, the resulting heat, water and air pollution must be counteracted with innovative concepts, such as the greening of unused building surfaces. The aim of the present work is to examine building greening systems with regard to their performance and applicability as well as to analyze the extent of usable surfaces in Germany. For this purpose, the knowledge gained from literature research was considered in a practical context based on company correspondence. The results show that, by taking into account a few essential requirements, almost every roof and wall can be greened. In addition, the usable surface area of existing and new buildings in Germany indicates great potential for future greening. However, the demand for different greening systems varies greatly, which can be attributed to different cost-benefit ratios, among other things. In the future, topics such as fire protection for greening systems, the usage of synergy effects and the linking of plants and digitization must be addressed in order to make the application of building greening easier and more attractive.

Core of this paper is the concept and development of an online application to assess professional competencies for action oriented courses in technical vocational education and training (TVET). This paper is the result of an university exam for TVET.

As part of this work, the memory of the "Jura Impressa S9" coffee machine was reverse engineered. A structured procedure was developed for this. Setting by setting and function by function, the significance of ever new memory locations emerged. Newly bundled, these were disclosed to the outside via an easily accessible API and finally presented visually on a small website. In the process, the procedure and the significance of the results were critically scrutinized and placed in the context of reverse engineering.

Linux namespaces are used for container-based operating-system-level virtualization today; the user namespace in particular enables a relatively recent development of so-called rootless containers. A brief overview of the technology is given and the underlying permissions model is explained. Two different threat models for application deployment are created. Using a reproducible testing environment and a number of existing vulnerabilities, associated risks and benefits of employing the user namespace are analysed. It is shown that user namespaces can provide significant improvements to a system's security but also pose risks of their own.

This thesis shows that social engineering mainly relies on peripheral route persuasion and that consequently, Cialdini's principles of influence can be used to explain how social engineering attacks work. It is further shown by a comprehensive literature review that individual values of personality traits relate to social engineering susceptibility. Based on these arguments, a framework is proposed, which can help to guide future research. Suggestions to plausible relations between the personality traits of the Big 5 Theory and the principles of influence are made. These relations need to be evaluated by future research. Lastly, an integrated approach to prevention against social engineering attacks is proposed, which combines penetration tests using social engineering, security awareness trainings, and the development of a security-aware organizational culture. The methodology used in conducting this investigation is a theoretical, positive research approach. Extensive literature reviews have been conducted on social engineering, psychology of persuasion and the influence of personality traits on the success of social engineering attacks. Based on an analysis and discussion of these reviews, proposals for a new framework and a prevention approach have been developed.