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Dissertation
Towards a Better Understanding of Entrepreneurial Teams: Investigating Temporal Dynamics on Multiple Levels
(2023)
This dissertation investigates entrepreneurial teams in the process of creating new ventures. The new venture creation process is complex. Different actors impact the new venture creation process in various ways, either facilitating or complicating it. The three studies at the heart of this thesis aim to cut through this complexity by examining the social context (i.e., entrepreneurial teams) and the temporal dynamics occurring in more detail. All studies address the conditions underpinning entrepreneurial teamwork ...
Dissertation
Learning through Self-Explanation
(2023)
In this dissertation, the effectiveness of learning through self-explanation was examined through a series of experiments. The primary focus was on the acquisition of factual knowledge. Learners' self-explanations were coded and categorized into correct inferences, correct paraphrases, and false utterances.
Dissertation
Process optimisation and non-destructive quality attributes monitoring during drying: A case study of celeriac slices and characterisation of its powder
(2023)
This study investigated strategies applied in drying technology to produce an optimised quality of plant-sourced food while considering environmental and sustainability aspects based on a case study of celeriac and powder, respectively. The I-optimal design of response surface methodology with 30 experiment runs was applied for process optimisation. Pre-drying treatments (blanching at 85 °C, 3 min; dipping in 1% citric acid solution, 3 min; no pre-drying treatment), drying temperatures (50, 60, and 70 °C), air ...
Aufsatz
A comparative study using water atomized and gas atomized powder in laser powder bed fusion process – Assessment of the fatigue performance
(2022)
Gas-atomized (GA, spherical) and water-atomized (WA, spattered) commercially pure iron (cp-Fe) powders were processed using laser-based powder bed fusion, resulting in a slightly higher porosity of the WA condition. In addition to characterization of quasi-static mechanical properties, fatigue tests, which are known to be detrimentally affected by porosity, were finally considered, revealing good properties even for the WA condition. In terms of microstructure stability, the GA and WA specimens significantly differ; ...
Aufsatz
Beam powder bed fusion for direct microstructure design – In-depth analysis of prospects and limitations of the multi spot scanning strategy
(2023)
The electron beam powder bed fusion process generally results in a strong 〈001〉 texture alongside the build direction for Inconel 718. This is a result of prevailing high thermal gradients between the melted surface and the solid material. However, based on specific beam movement patterns, the solidification behaviour can be altered towards an equiaxed, isotropic microstructure. The present study focuses on the “multi spot scanning” strategy directly provided by the machine manufacturer. The operation mode of the ...
Dissertation
The anatomy of velvet worms (Onychophora) as revealed by a multimethodological approach and three-dimensional reconstructions
(2024)
Onychophorans, or velvet worms, comprise a small group of worm-like, multi-legged terrestrial invertebrates. Since their discovery in 1826, these organisms have been investigated from different perspectives, particularly in the field of morphology—a discipline that provides the basis for functional and evolutionary inferences. Onychophorans are currently classified within Ecdysozoa (moulting animals) and form together with Tardigrada (water bears) and Arthropoda a clade named Panarthropoda. Therefore, onychophorans ...
Dissertation
City Development Regimes in-the-Making. Phronetic Analysis of Governance, Networks and Power in Cairo, 2011-2022
(2024)
Since the revolutionary uprising of January 2011, Cairo’s inner-city neighbourhoods have undergone rapid spatial transformations. Over the last decade, numerous old housing buildings have been replaced by modern ones, leading to the displacement of residents to the desert cities or newly-constructed neighbourhoods outside the city centre. The most remarkable transformations occurred since early 2018. Notably, these changes have been characterised by a fast implementation rate and a lack of community resistance to ...
Dissertation
Testing the Impact of Large-scale Digital Support on Students' Paths Toward College Education
(2024-02)
Increasing the share of college graduates can boost productivity, promote social mobility, and improve well-being. However, these benefits are often realized when the education system satisfies the demands of the industry. Otherwise, society may face skill shortages. This thesis aims to expand the understanding of how to attract students, particularly minorities, to pursue academic majors linked to the areas facing skill shortages (henceforth, high-rewarding majors). To accomplish this, it examines the impact of ...
Aufsatz
Parameter recommendation for injection molding based on similarity analysis of injection molded parts
(2023)
Injection molding is a widespread manufacturing process for producing complex plastic shapes. The process is controlled by a large number of parameters, which show interactions with each other. Thereby the determination of an optimal operating point during sampling is a resource-consuming and demanding task. The data, which is generated during sampling, is usually not used for subsequent sampling processes. In the context of Industry 4.0, manufacturing companies attempt to optimize production efficiency to save time ...
Aufsatz
Baumwolle als Faserverstärkung
(2023)
Jedes Jahr landen große Mengen Textilen auf Deponien oder in der thermischen Verwertung. Ein Teil dieser Abfälle könnte allerdings auch als Rohstoffe für Verbundwerkstoffe dienen. Baumwollfasern eignen sich etwa als Verstärkungsfasern, die die mechanischen Eigenschaften von biobasierten Kunststoffen steigern. Durch die Nutzung solcher Abfallströme können in Zukunft kostengünstig und biobasiert Materialien verstärkt werden.