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The goal of this PhD thesis is to investigate possibilities of using symbol elimination for solving problems over complex theories and analyze the applicability of such uniform approaches in different areas of application, such as verification, knowledge representation and graph theory. In the thesis we propose an approach to symbol elimination in complex theories that follows the general idea of combining hierarchical reasoning with symbol elimination in standard theories. We analyze how this general approach can be specialized and used in different areas of application.
In the verification of parametric systems it is important to prove that certain safety properties hold. This can be done by showing that a property is an inductive invariant of the system, i.e. it holds in the initial state of the system and is invariant under updates of the system. Sometimes this is not the case for the condition itself, but for a stronger condition it is. In this thesis we propose a method for goal-directed invariant strengthening.
In knowledge representation we often have to deal with huge ontologies. Combining two ontologies usually leads to new consequences, some of which may be false or undesired. We are interested in finding explanations for such unwanted consequences. For this we propose a method for computing interpolants in the description logics EL and EL⁺, based on a translation to the theory of semilattices with monotone operators and a certain form of interpolation in this theory.
In wireless network theory one often deals with classes of geometric graphs in which the existence or non-existence of an edge between two vertices in a graph relies on properties on their distances to other nodes. One possibility to prove properties of those graphs or to analyze relations between the graph classes is to prove or disprove that one graph class is contained in the other. In this thesis we propose a method for checking inclusions between geometric graph classes.
The political targets for CO2 reduction in industrial processes are leading to a technological change in the area of pig iron production. In future, pig iron will be produced by using the direct reduction process instead of the blast furnace process. Direct reduction plants are currently operated with natural gas, this is to be replaced by hydrogen in the future in order to meet the climate targets. Within this work, the influence of hydrogen-containing atmospheres on currently used refractory materials from the Al2O3-SiO2 system was investigated. An experiment was developed to simulate the corrosion of refractory materials in the laboratory under realistic test conditions. Taking into account the atmosphere, the temperature and the sample material, a variety of practical corrosion tests were carried out. By applying a comprehensive analysis strategy, relevant corrosion effects on the materials were subsequently described as a result of the gas composition. The test temperature was in the range of 716 °C < T < 1150 °C. Physical and chemical-mineralogical tests were used to investigate the corrosion effects. In addition, the intensity of the corrosion effects was evaluated based on the gas compositions used. Pure hydrogen atmospheres in particular led to strong gas corrosion, while the presence of water vapor inhibited the chemical reactions. The mixture of methane and hydrogen can create an aggressive H2 / CO atmosphere, which also can lead to the formation of solid carbon. This phenomenon changes the possible causes of damage to refractory material; the crystallization pressure of carbon inside the structure of the refractory can also contribute to material failure. Furthermore, the corrosion reactions could be described by coupling imaging analysis methods and element determination. It was shown that, in contrast to the general opinion in the state of the art, there was not exclusively a decrease in SiO2-amount. Several reactions took place in the investigated, industrially used materials, which led to the local chemical attack of SiO2 (silicate glass phase) and caused a parallel crystallization of cristobalite. The chemical attack of hydrogen on the silicate glass phase can be defined as the primary corrosion reaction in the range of 716 °C < T < 1150 °C in a pure hydrogen atmosphere. In addition, the reaction kinetics as a function of temperature were experimentally investigated and described. Based on these analyses, material properties can be defined that are particularly suitable for the future use of defined refractory qualities within reduction processes.
Cross Cultural Adaptation of Design Thinking in Entrepreneurship Higher Education in Indonesia
(2024)
Entrepreneurship and entrepreneurship education have expanded together, and their conceptual and methodological challenges do not prevent the implementation of entrepreneurial education in educational contexts. The desire for a global workforce that can handle uncertainties and solve problems that cannot be solved by pure analytical inquiry drives the rapidly expanding number of educational programs and activities that are design-based. A growing number of educational programs for entrepreneurs increasingly incorporate design-based methods. However, design thinking-based theoretical assumptions may also be lacking. Despite growing academic interest in design thinking and entrepreneurship education, little is known about design thinking in higher entrepreneurship education, especially in Eastern nations. A Western teaching method, entrepreneurial design thinking may be adapted to many cultures. In this instance, the West has established entrepreneurship education as a respectable study subject and teaching practice in higher education over the past 40 years. The Eastern nations' occurrence varies, including Indonesia. Indonesia is an intriguing research subject since it has over 50% youth due to its abundant natural resources. However, it needs more opportunity-based entrepreneurs and requires assistance in implementing entrepreneurship education with a more innovative, design-based, and successful method. Entrepreneurial design thinking fulfills this demand. Indonesian students and teachers' norm-based attitudes and cultural mindsets towards a new western creative method may hinder entrepreneurial design thinking's acceptance. The literature review found that Indonesian university students are collaborative, compassionate, and practical, like design thinkers. However, they may also be risk-averse, self-restrained, and dependent on teachers as stereotypical Asians. Classroom space, educators' design thinking competence, and university or institution support are further barriers. Additional study into these challenges is needed to adapt design thinking to Indonesian entrepreneurial higher education culturally.
Based on the above research needs, the purpose of this research endeavor is to look into the cultural nuances of the design thinking technique for entrepreneurial higher education and postulate how it could be adapted to other cultures, especially in Indonesia. This thesis uses deductive and qualitative case-study research methods. In particular, the latter used thematic analysis (Braun & Clarke, 2006; Terry & Hayfield, 2021) as the data analysis technique to provide a means and tools for understanding from interviews, class observation, and literature studies. Since this thesis follows the constructivist-relativist research paradigm, it explores contextual and cultural differences in Indonesian entrepreneurship education and its potential and obstacles to adapt the Western teaching methodology of entrepreneurial design thinking in higher education. In summary, this study searches for elements that might aid or hinder the cross-cultural adaption of entrepreneurial design thinking. This research wants to understand how cross-cultural adaptability fits into entrepreneurial design thinking research, especially for Indonesia. This thesis aims to provide new theoretical insights and practical advice on adapting entrepreneurial design thinking from Western to Eastern cultures.
From the findings, this thesis concluded at least seven educational value differentials before adaptation from the exhaustive literature and case study evaluations. For Indonesian entrepreneurship higher education institutions to use entrepreneurial design thinking, they must consider educational culture, technological infrastructure, language, primary audience, learning and teaching style, reasoning patterns, and social-cultural environment. This study provides four practical adaptation recommendations: socialization, externalization, combination, and internalization. Finally, this research demonstrated that cross-cultural adaption of entrepreneurial design thinking in Indonesia might be difficult but worthwhile. This thesis' case study, "School of Business Management – Bandung Institute of Technology (SBM ITB)", showed that Indonesian entrepreneurial higher education might use design thinking as a teaching approach. All stakeholders must improve internally and publicly. Thus, this study recommended integrating most Indonesian higher education institutions' entrepreneurship teaching approaches with a "student-centered" approach that stresses business mentorship, uses design thinking tools and processes, and links them to students' entrepreneurial initiatives.
To summarize, this research contributes to the field since it draws on and combines the findings of several other fields of study, including entrepreneurial education, design thinking, and cross-cultural adaptation. This study stepped out of the "usual and proper" pedagogical ruts to investigate "non-human" cross-cultural adaptability. It has attempted to apply these ideas to a real-world, unique case study in a developing nation (in this case, Indonesia).
During the development phase of plastic components, simulations are being used to an increasing extent. Against the background of product requirements and the inevitable necessity of conserving resources, the expanded use of simulation tools is an essential part of the solution. Among available methods, but so far underutilized with respect to real-life processes, is the molecular dynamics simulation. By the use of this method it is possible to visualize the physical processes occurring on the microscopic level, as e.g. those that arise during plastics processing. This thesis examines how boundary conditions, which mimic the extrusion blow molding process, affect the behavior of polyethylene on the microscopic level. A mesoscopic model (coarse-graining) is applied to describe the polymer. Initially, this model is verified by determining material properties. The uniaxial tensile test is modeled on the micro-scale to identify parameters such as the elastic modulus, yield stress, and Poisson’s ratio. Additionally, thermal properties, particularly those characterizing the crystallization behavior, are identified. The objective of these investigations is the microscopic observation and quantification of effects that occur during dynamic stretching and crystallization processes. The calculated properties show good agreement with the experimental data, especially regarding the thermal parameters. Qualitatively, the stress-strain behavior is reproduced in alignment with experimentally observed results. However, the short time scale of the simulation models leads to micromechanical behavior that is more extreme than what is monitored on a macroscopic level. By extending the simulation models, biaxial stretching processes are simulated. These stretching processes resemble the situation during the inflation of the parison in the extrusion blow molding process. The examination of various cooling conditions, particularly by the use of mold constraints, is another focus of the investigations. The analysis of the biaxially stretched simulations reveals that disentanglement processes during stretching dominate the further development of polymer systems. It is possible to quantify the dynamics of crystallization processes depending on the degree of stretching and cooling conditions through various parameters (distribution of entanglement points, local orientations). The results indicate that coarse-grained molecular dynamics simulations are able to significantly enhance the micromechanical understanding of local events occurring during plastic processing.
The digital transformation of the public sector and the development of suitable implementation mechanisms are currently major challenges in the area of E-Government. While Germany is one of the leading countries in the private sector in terms of digital offerings, the digital transformation processes in the public sector are progressing only slowly. In particular, compared to other European countries, German administrations offer few digital and interoperable services, which prevents them from catching up with a government-wide dig-ital transformation.
The aim of this dissertation is to investigate the reasons for the slow progress of digital transformation in the public sector and to understand why Germany is not making significant progress in the digitization of administrative services compared to other European member states. Furthermore, it aims to gradually build a comprehensive understanding of why digital transformation is not being driven, supported or applied in the public sector and what positive or negative factors ultimately prevent cross-organizational exchange.
The focus of this dissertation is on organizational and interdisciplinary collaboration in socio-technical systems and its influence on the digital transformation of public administrations. The investigation of science and practice is based on the principles of qualitative social research and qualitative content analysis according to Mayring. Deductive categories are systematically derived and supplemented by further inductive categories along the empirical investigation in the five case studies.
The identified phenomena are analyzed in a scientific explanatory model and described with the help of the holistic approach and the actor-network theory. On this basis, solutions are developed that can either prevent or at least reduce the influencing factors. An interdiscipli-nary approach that combines theoretical foundations from business informatics, administrative informatics/e-government and organizational science not only creates a comprehensive understanding of the problem, but also develops approaches for the scientific description of informatics phenomena with the help of social constructivist approaches.
In the last decade, policy-makers around the world have turned their attention toward the creative industry as the economic engine and significant driver of employments. Yet, the literature suggests that creative workers are one of the most vulnerable work-forces of today’s economy. Because of the highly deregulated and highly individuated environment, failure or success are believed to be the byproduct of individual ability and commitment, rather than a structural or collective issue. This thesis taps into the temporal, spatial, and social resolution of digital behavioural data to show that there are indeed structural and historical issues that impact individuals’ and
groups’ careers. To this end, this thesis offers a computational social science research framework that brings together the decades-long theoretical and empirical knowledge of inequality studies, and computational methods that deal with the complexity and scale of digital data. By taking music industry and science as use cases, this thesis starts off by proposing a novel gender detection method that exploits image search and face-detection methods.
By analysing the collaboration patterns and citation networks of male and female computer scientists, it sheds lights on some of the historical biases and disadvantages that women face in their scientific career. In particular, the relation of scientific success and gender-specific collaboration patterns is assessed. To elaborate further on the temporal aspect of inequalities in scientific careers, this thesis compares the degree of vertical and horizontal inequalities among the cohorts of scientists that started their career at different point in time. Furthermore, the structural inequality in music industry is assessed by analyzing the social and cultural relations that breed from live performances and musics releases. The findings hint toward the importance of community belonging at different stages of artists’ careers. This thesis also quantifies some of the underlying mechanisms and processes of inequality, such as the Matthew Effect and the Hipster Paradox, in creative careers. Finally, this thesis argues that online platforms such as Wikipedia could reflect and amplify the existing biases.
The diversity within amphibian communities in cultivated areas in Rwanda and within two selected, taxonomically challenging groups, the genera Ptychadena and Hyperolius, were investigated in this thesis. The amphibian community of an agricultural wetland near Butare in southern Rwanda comprised 15 anuran species. Rarefaction and jackknife analyses corroborated that the complete current species richness of the assemblage had been recorded, and the results of acoustic niche analysis suggested species saturation of the community. Surveys at many other Rwandan localities showed that the species recorded in Butare are widespread in cultivated and pristine wetlands. The species were readily distinguishable using morphological, bioacoustic, and molecular (DNA barcoding) features, but only eight of the 15 species could be assigned unambiguously to nominal species. The remaining represented undescribed or currently unrecognized taxa, including three species of Hyperolius, two Phrynobatrachus species, one Ptychadena species, and one species of Amietia. The diversity of the Ridged Frogs in Rwanda was investigated in two studies (Chapters III and IV). Three species of Ptychadena were recorded in wetlands in the catchment of the Nile. They can be distinguished by morphological characters (morphometrics and qualitative features) as well as by their advertisement calls and genetics. The Rwandan species of the P. mascareniensis group was shown to differ from the topotypic population as well as from other genetic lineages in sub-Saharan Africa and an old available name, P. nilotica, was resurrected from synonymy for this lineage. Two further Ptychadena species were identified among voucher specimens from Rwanda deposited in the collection of the RMCA, P. chrysogaster and P. uzungwensis. Morphologically they can be unambiguously distinguished from each other and the three other Rwandan species. A key based on qualitative morphological characters was developed, which allows unequivocal identification of specimens of all species that have been recorded from Rwanda. DNA was isolated from a Rwandan voucher specimen of P. chrysogaster, and the genetic analysis corroborated the species" distinct status.
A species of Hyperolius collected in the Nyungwe National Park was compared to all other Rwandan species of the genus and to morphologically or genetically similar species from neighbouring countries. Its distinct taxonomic status was justified by morphological, bioacoustic, and molecular evidence and it was described as a new species, H. jackie. A species of the H. nasutus group collected at agricultural sites in Rwanda was described as a new species in the course of a revision of the species of the Hyperolius nasutus group. The group was shown to consist of 15 distinct species which can be distinguished from each other genetically, bioacoustically, and morphologically.
The aerial performance, i.e. parachuting, of the Disc-fingered Reed Frog, Hyperolius discodactylus, was described. It represents a novel observation of a behaviour that has been known from a number of Southeast Asian and Neotropical frog species. Parachuting frogs, including H. discodactylus, exhibit certain morphological characteristics and, while airborne, assume a distinct posture which is best-suited for maneuvering in the air. Another study on the species addressed the validity of the taxon H. alticola which had been considered either a synonym of H. discodactylus or a distinct species. Type material of both taxa was re-examined and the status of H. alticola reassessed using morphological data from historic and new collections, call recordings, and molecular data from animals collected on recent expeditions. A northern and a southern genetic clade were identified, a divide that is weakly supported by diverging morphology of the vouchers from the respective localities. No distinction in advertisement call features could be recovered to support this split and both genetic and morphological differences between the two geographic clades are marginal and not always congruent and more likely reflect population-level variation. Therefore it was concluded that H. alticola is not a valid taxon and should be treated as a synonym of H. discodactylus.
On the recognition of human activities and the evaluation of its imitation by robotic systems
(2023)
This thesis addresses the problem of action recognition through the analysis of human motion and the benchmarking of its imitation by robotic systems.
For our action recognition related approaches, we focus on presenting approaches that generalize well across different sensor modalities. We transform multivariate signal streams from various sensors to a common image representation. The action recognition problem on sequential multivariate signal streams can then be reduced to an image classification task for which we utilize recent advances in machine learning. We demonstrate the broad applicability of our approaches formulated as a supervised classification task for action recognition, a semi-supervised classification task for one-shot action recognition, modality fusion and temporal action segmentation.
For action classification, we use an EfficientNet Convolutional Neural Network (CNN) model to classify the image representations of various data modalities. Further, we present approaches for filtering and the fusion of various modalities on a representation level. We extend the approach to be applicable for semi-supervised classification and train a metric-learning model that encodes action similarity. During training, the encoder optimizes the distances in embedding space for self-, positive- and negative-pair similarities. The resulting encoder allows estimating action similarity by calculating distances in embedding space. At training time, no action classes from the test set are used.
Graph Convolutional Network (GCN) generalized the concept of CNNs to non-Euclidean data structures and showed great success for action recognition directly operating on spatio-temporal sequences like skeleton sequences. GCNs have recently shown state-of-the-art performance for skeleton-based action recognition but are currently widely neglected as the foundation for the fusion of various sensor modalities. We propose incorporating additional modalities, like inertial measurements or RGB features, into a skeleton-graph, by proposing fusion on two different dimensionality levels. On a channel dimension, modalities are fused by introducing additional node attributes. On a spatial dimension, additional nodes are incorporated into the skeleton-graph.
Transformer models showed excellent performance in the analysis of sequential data. We formulate the temporal action segmentation task as an object detection task and use a detection transformer model on our proposed motion image representations. Experiments for our action recognition related approaches are executed on large-scale publicly available datasets. Our approaches for action recognition for various modalities, action recognition by fusion of various modalities, and one-shot action recognition demonstrate state-of-the-art results on some datasets.
Finally, we present a hybrid imitation learning benchmark. The benchmark consists of a dataset, metrics, and a simulator integration. The dataset contains RGB-D image sequences of humans performing movements and executing manipulation tasks, as well as the corresponding ground truth. The RGB-D camera is calibrated against a motion-capturing system, and the resulting sequences serve as input for imitation learning approaches. The resulting policy is then executed in the simulated environment on different robots. We propose two metrics to assess the quality of the imitation. The trajectory metric gives insights into how close the execution was to the demonstration. The effect metric describes how close the final state was reached according to the demonstration. The Simitate benchmark can improve the comparability of imitation learning approaches.
Antonio Lotti und seine liturgische Kirchenmusik – Vorstudien zu Biographie und Überlieferung
(2023)
Antonio Lotti (1667-1740) gehört zu den venezianischen Komponisten, die in der älteren wie der neueren Fachliteratur ein hohes Ansehen genießen, obwohl seine Werke bis heute nur wenig bekannt sind. Eine unklare Überlieferungslage, aber auch sachfremde ästhetische Postulate verzögerten jedoch die Auseinandersetzung mit Lottis Kompositionen. Erst in neuerer Zeit gab es ein verstärktes Interesse sowohl an seinen Opern und vokaler Kammermusik als auch an seiner Kirchenmusik.
In der vorliegenden Studie wird zunächst Lottis Biographie unter Einbeziehung neuer Quellenfunde auf dem aktuellen Stand des Wissens zusammenfassend dargestellt. Der zweite Teil bietet erstmals eine Identifikation von Lottis Buchstaben- und Notenschrift nach streng philologischen Kriterien. Angesichts des nicht mehr erhaltenen Nachlasses ist dieser Teil von besonderer Bedeutung, bietet er doch die unverzichtbare Basis zur weiteren Erforschung von Lottis Kirchenmusik, ihrer Überlieferung und Faktur.
Im Rahmen des vorliegenden Promotionsprojekts wird untersucht, welche Körperideologien in den drei unterschiedlichen Sportfeldern Hochleistungs-, Gesundheits- sowie Erlebnis- bzw. Funsport gegeben sind und welchen gesellschaftswirksamen Einfluss diese Ideologien aufweisen. Im Rahmen der zentralen Forschungsfrage wird des Weiteren erforscht, welche diskursiven Mittel bei Körperideologien im Sportbereich eingesetzt werden, welche Formationen in Bezug auf den Gegenstand, welche Äußerungsmodalitäten, Begrifflichkeiten und Strategien dem Diskurs zugrundeliegen und wer als TrägerIn oder AdressatIn des Diskurses identifiziert werden kann. Außerdem steht die Fragestellung im Fokus, welche Bezüge zu anderen Diskursen bestehen und um welche Diskurse es sich dabei handelt. Körperideologien des Sports werden in diesem Zusammenhang als Vorstellungen von einem (idealen) Körper betrachtet, welche durch den Sport übertragen und in der Gesellschaft verbreitet werden. Dabei wird zunächst der Begriff der Ideologie theoretisch hergeleitet und definiert sowie im Hinblick auf die vorliegende Arbeit als Weltdeutung mit einem Anspruch auf Alleinvertretung aufgefasst. Des Weiteren wird die Gouvernementalitätstheorie von Foucault aufgegriffen und für die Identifizierung der Macht- und Herrschaftsstrukturen in Bezug auf die untersuchten Körperideologien herangezogen. Dabei geht es darum, inwieweit die durch den Sport übermittelten Körperideologien dazu geeignet sind, in einem gouvernementalitätstheoretischen Sinne Führung zur Selbstführung zu ermöglichen. In einer sportsoziologischen Hinsicht beinhaltet der Sport leistungsbezogene Eigenschaften, welche in auf Effektivität abzielenden wirtschaftlichen Prozessen eine grundlegende Voraussetzung darstellen. Im Rahmen der Studie werden für jeden der drei genannten Sportbereiche jeweils zwei Individualsportarten ausgewählt, bei welchen die fokussierten Körperideologien untersucht werden. Während im Bereich des Hochleistungssports Schwimmen und Biathlon und im Bereich des Gesundheitssports Nordic Walking sowie Pilates betrachtet werden, stellen Stand Up Paddling und Parkour die fokussierten Sportarten im Bereich des Fun- bzw. Erlebnissports dar. Für die vorliegende Untersuchung kommt das Verfahren der kritischen Diskursanalyse (KDA) von Jäger zur Anwendung, da dieses für die Rekonstruktion von ideologischen Diskursen geeignet erscheint. Hierfür werden aus den drei Sportbereichen sowohl Print- als auch Onlinepublikationen sondiert und anhand von Strukturanalysen hinsichtlich verschiedener formaler und inhaltlicher Charakteristika untersucht. Des Weiteren wird mit Hilfe der tiefergehenden Feinanalyse jeweils ein Artikel pro Sportart explorativ analysiert, um verschiedene Muster zu vorhandenen Körperideologien in den fokussierten Sportarten und Sportbereichen identifizieren und anhand ausgewählter Textstellen belegen zu können. Bei den Ergebnissen zeigt sich, dass der Körper in den Hochleistungssportarten Schwimmen und Biathlon als formbares Material bzw. als Instrument zur Erbringung sportlicher Höchstleistungen betrachtet und dargestellt wird. Auch im Gesundheitssport wird der Körper als form- bzw. trainierbar hervorgehoben, wobei hierbei die Gesundheit im Fokus steht und mit Schlankheit gleichgesetzt wird. Im Bereich des Fun- bzw. Erlebnissports zeigt sich bei der Sportart Stand Up Paddling der Körper ebenfalls als zu bearbeitendes Objekt. Dagegen wird bei der Sportart Parkour der angenommene Normalismus von Jugendlichkeit anhand der Ergebnisse widerlegt. Deutlich wird, dass als diskursives Mittel vor allem der Körper als formbares Material erscheint. Dabei stehen in Bezug auf die Äußerungsmodalitäten und Begrifflichkeiten der Diskurse vor allem das Leistungsmaximum, aber auch Schlankheit und Fitness im Fokus. Die identifizierten Diskurse sind an die gesamte Gesellschaft adressiert und werden zudem durch sich selbst getragen, wodurch sie nicht nur die Realität abbilden, sondern auch ein Eigenleben in der Form entwickeln, dass sie als Träger von Wissen fungieren.
Praktika als gängige Lehr-Lernformate in hochschulischen Kontexten setzen stets die Zusammenarbeit verschiedener Institutionen und Personen voraus, da Studierende mit einem Praktikum den Lernort der Universität verlassen und in einen beruflichen Handlungszusammenhang mit den zugehörigen organisationalen Strukturen versetzt werden. Praktika werden unter anderem als Elemente der Berufsorientierung gesellschaftliche Implikationen zugeschrieben. Als Format innerhalb eines hochschulischen Bildungsgangs sind sie darüber hinaus mit didaktischen Begründungen verbunden und durch die Beteiligung verschiedener Personen auch mit individuellen Interessen. Studierende sind während eines Praktikums in der Rolle als Praktikant*in in besonderer Weise individuell gefordert. Ergänzt werden diese Perspektiven durch die Betrachtung disziplinärer und professioneller Implikationen, die sich für Praktika erziehungswissenschaftlicher Studiengänge ergeben. Zusammenarbeit findet in Praktika zwischen Organisationen, in Organisationen und zwischen Personen statt. Der geringe Forschungsstand zu Perspektiven auf Fragen der Zusammenarbeit für in erziehungswissenschaftliche Studiengänge integrierte Praktika bietet den Anlass der Studie. Um die verschiedenen Perspektiven auf Praktika als Zusammenarbeit zu erheben, werden qualitative episodische Interviews sowohl mit den Studierenden und Lehrenden einer Universität, als auch mit für Praktika verantwortlichen Tätigen aus dem beruflichen Bereich durchgeführt, die nach der qualitativen inhaltlich strukturierenden Inhaltsanalyse ausgewertet werden. Aus der Auswertung der geführten Interviews mit den drei Akteur*innen-Gruppen ergibt sich ein Einblick darin, wie sich Zusammenarbeit zwischen pädagogisch tätigen Institutionen, Universitäten und Studierenden in und durch Praktika konkretisiert. Es werden beispielsweise Aspekte der Interaktionsbezogenen Dimensionen beschrieben, wie auftauchende Dilemmata, Resonanzen, Kulturen des Umgangs, Interessenslagen und Konstellationen von Akteur*innen. Diese werden ergänzt um Aspekte der Dimensionen mit Bezug zu Institutionen, Umwelt, Aufgaben und Personen. Die Interviewaussagen von drei interviewten Akteur*innen-Gruppen Studierende, Praxisanleiter*innen, universitäre Lehrende werden vergleichend anhand dieser Dimensionen betrachtet und als Ergebnisse dieser Studie dargestellt. Die Ergebnisse liefern Aussagen dazu, wie Zusammenarbeit in Praktika erziehungswissenschaftlicher Studiengänge von den beteiligten Akteur*innen-Gruppen wahrgenommen wird. Dies kann dazu beitragen die differierenden Perspektiven anschlussfähig zu machen für die didaktische und organisatorische Gestaltung von Praktika durch Institutionen wie Universitäten und Praktikumseinrichtungen, aber auch durch Initiative von Studierenden in der Rolle als Praktikant*innen während eines erziehungswissenschaftlichen Studiums. Auch für weitere Forschungsprojekte zum Zusammenwirken der Beteiligten in Praktika kann die Studie Anstöße bieten.
Eltern spielen eine entscheidende Rolle bei der Inanspruchnahme von kultureller Bildung durch Kinder und Jugendliche. Häufig sind sie in die Organisation und Finanzierung der kulturellen Bildungsangebote involviert. Insbesondere in ländlichen Räumen kommt die Besonderheit hinzu, dass Eltern aufgrund größerer räumlicher Distanzen und einer unzureichenden Ausstattung des ÖPNV Begleitfahrten mit dem eigenen PKW durchführen müssen. Häufig werden ländliche Räume anhand objektivierbarer Daten als strukturschwach oder kulturarm beschrieben. Darüber, ob oder inwiefern das von ländlich lebenden Eltern ebenso gesehen wird, ist jedoch wenig bekannt.
Die vorliegende Dissertationsschrift gibt einen Einblick in die elterlichen Perspektiven auf kulturelle Bildung in ländlichen Räumen. Sie basiert auf offenen, qualitativen Leitfadeninterviews mit Eltern aus vier ländlichen Regionen Deutschlands, die diskursanalytisch und unter Zuhilfenahme von Kodierungspraktiken aus dem Kontext der Grounded Theory ausgewertet wurden.
In den Interviews zeigt sich eine Vielzahl an elterlichen Verständnissen und Positionierungsweisen zur kulturellen Bildung in ländlichen Regionen. Es stellt sich heraus, dass der elterliche Diskurs auf einem komplexen Zusammenspiel sozioökonomischer bzw. -kultureller Bedingungen, raumstruktureller Gegebenheiten und individueller Präferenzen hinsichtlich kultureller Bildung auf dem Land basiert.
With the increasing importance and urgency of climate change, companies are challenged to contribute to sustainable development, especially by younger generations. However, existing corporate contributions have been criticized as insufficient, which could be particularly caused by a lack of employee engagement in corporate sustainability. In this context, gamification has been proposed and increasingly investigated in recent years as a promising, innovative tool to motivate sustainable employee behaviors in the workplace. However, there are few studies and applicable gamification solutions that address more than one specific sustainability issue and thus take a holistic perspective on sustainable behaviors in the workplace. Moreover, previous research lacks a comprehensive understanding of how different gamification elements elicit specific psychological effects, how these manifest in behavioral changes, and how these, in turn, cumulatively result in measurable corporate outcomes. The path from gamification as ”input” to corporate sustainability as ”output” thus remains unexplored.
This dissertation fills this gap by conceptualizing, designing, and evaluating a holistic gamified intervention that supports employees in various sustainable behaviors in their daily activities. The project uses a design science research approach that closely involves employees in the incremental development of the solution. As part of the iterative design process, this dissertation presents six studies to extend the theoretical understanding of gamification for sustainable employee behaviors. First, a comprehensive review of existing research on gamification for sustainable employee behavior is provided, analyzing gamification designs and results of previous studies and outlining an agenda for further research (Study 1). Theoretical foundations of research on gamification, serious games, and game-based learning (Study 2) and empirical design principles for gamification and persuasive systems (Study 3) are then systematically reviewed as a basis for the successful design of gamified applications. Subsequently, empirical studies explore employees’ motivations for sustainable behavior and illuminate their expectations for design features (Study 4), and identify contextual challenges and design dilemmas when implementing gamification in an organizational context (Study 5). Finally, a quantitative field study (Study 6) explores how different gamification designs influence sustainable employee behavior and corporate sustainability in organizations. Based on the findings, this dissertation presents a comprehensive framework of gamification for sustainable employee behavior that incorporates design, individual behavior, and organizational perspectives. Finally, building on these insights, it provides practical recommendations for designing gamification to encourage sustainable employee behavior at work.
Organic binder mixtures and process additives have been used in refractory materials for a long time due to their property-improving effect. Coal tar pitches in particular can contain thousands of chemical compounds, of which especially polycyclic aromatic hydrocarbons (PAHs) are known to be carcinogenic and mutagenic and thus pose a risk to both the environment and human health. However, despite intensive research, the exact structure of these carbon mixtures is still not fully clarified. This is becoming an increasing problem, especially with regard to more stringent legal requirements arising from REACH, the European Chemicals Regulation for the Registration, Evaluation, Authorization and Restriction of Chemicals. Furthermore, the knowledge of the structural and chemical composition is also of great importance for optimal processing of the carbon mixtures to high-quality technical products. In the present work, an analytical strategy for the investigation of complex carbon mixtures containing PAHs is developed. Due to their complexity, a combination of different methods is used, including elemental analysis, solvent extraction, thermogravimetry, differential thermal analysis, raman and infrared spectroscopy as well as high-resolution mass spectrometry. In addition, a procedure for the evaluation of mass spectrometric data based on multivariate statistical methods such as hierarchical cluster analysis and principal component analysis is developed. The application of the developed analytical strategy to various industrially used carbon-based binder mixtures allowed the elucidation of characteristic properties, including aromaticity, molecular mass distribution, degree of alkylation and elemental composition. It was also shown that combining high-resolution time-of-flight mass spectrometry with multivariate statistical data analysis is a fast and effective tool for the classification of complex binder mixtures and the identification of characteristic molecular structures. In addition, the analytical strategy was applied to manufactured refractory products. Despite the small amount of the contained organic phase, characteristic structural features of each sample could be identified and extracted, which enabled an unambiguous classification of the refractory products.
Die Geometrie unseres Anschauungsraumes – die euklidische Geometrie – ist für einen allgemeinbildenden Mathematikunterricht elementar. Seitens der Mathematiklehrkraft stellt grundsätzlich ihr Fachwissen das Fundament des Unterrichtens dar. Als Teil ihres Professionswissens sollten Mathematiklehrkräfte prinzipiell über ein Fachwissen verfügen, das in Bezug zur akademischen Mathematik den unterrichtlichen Anforderungen der schulischen Mathematik gerecht wird.
Die im Rahmen der Dissertation entwickelte Theorie des metrisch-normalen euklidischen Raumes charakterisiert sich in ihrer perspektivischen Dualität, der mathematischen Stringenz eines axiomatisch-deduktiven Vorgehens auf der einen und der Berücksichtigung der fachdidaktischen Anforderungen an Mathematiklehrkräfte auf der anderen Seite; sie hebt sich darin von bestehenden Theorien ab.
Leichte Sprache (LS, easy-to-read German) is a simplified variety of German. It is used to provide barrier-free texts for a broad spectrum of people, including lowliterate individuals with learning difficulties, intellectual or developmental disabilities (IDD) and/or complex communication needs (CCN). In general, LS authors are proficient in standard German and do not belong to the aforementioned group of people. Our goal is to empower the latter to participate in written discourse themselves. This requires a special writing system whose linguistic support and ergonomic software design meet the target group’s specific needs. We present EasyTalk a system profoundly based on natural language processing (NLP) for assistive writing in an extended variant of LS (ELS). EasyTalk provides users with a personal vocabulary underpinned with customizable communication symbols and supports in writing at their individual level of proficiency through interactive user guidance. The system minimizes the grammatical knowledge needed to produce correct and coherent complex contents by intuitively formulating linguistic decisions. It provides easy dialogs for selecting options from a natural-language paraphrase generator, which provides context-sensitive suggestions for sentence components and correctly inflected word forms. In addition, EasyTalk reminds users to add text elements that enhance text comprehensibility in terms of audience design (e.g., time and place of an event) and improve text coherence (e.g., explicit connectors to express discourse-relations). To tailor the system to the needs of the target group, the development of EasyTalk followed the principles of human-centered design (HCD). Accordingly, we matured the system in iterative development cycles, combined with purposeful evaluations of specific aspects conducted with expert groups from the fields of CCN, LS, and IT, as well as L2 learners of the German language. In a final case study, members of the target audience tested the system in free writing sessions. The study confirmed that adults with IDD and/or CCN who have low reading, writing, and computer skills can write their own personal texts in ELS using EasyTalk. The positive feedback from all tests inspires future long-term studies with EasyTalk and further development of this prototypical system, such as the implementation of a so-called Schreibwerkstatt (writing workshop)
In the last years, the public interest in epidemiology and mathematical modeling of disease spread has increased - mainly caused by the COVID-19 pandemic, which has emphasized the urgent need for accurate and timely modelling of disease transmission. However, even prior to that, mathematical modelling has been used for describing the dynamics and spread of infectious diseases, which is vital for developing effective interventions and controls, e.g., for vaccination campaigns and social restrictions like lockdowns. The forecasts and evaluations provided by these models influence political actions and shape the measures implemented to contain the virus.
This research contributes to the understanding and control of disease spread, specifically for Dengue fever and COVID-19, making use of mathematical models and various data analysis techniques. The mathematical foundations of epidemiological modelling, as well as several concepts for spatio-temporal diffusion like ordinary differential equation (ODE) models, are presented, as well as an originally human-vector model for Dengue fever, and the standard (SEIR)-model (with the potential inclusion of an equation for deceased persons), which are suited for the description of COVID-19. Additionally, multi-compartment models, fractional diffusion models, partial differential equations (PDE) models, and integro-differential models are used to describe spatial propagation of the diseases.
We will make use of different optimization techniques to adapt the models to medical data and estimate the relevant parameters or finding optimal control techniques for containing diseases using both Metropolis and Lagrangian methods. Reasonable estimates for the unknown parameters are found, especially in initial stages of pandemics, when little to no information is available and the majority of the population has not got in contact with the disease. The longer a disease is present, the more complex the modelling gets and more things (vaccination, different types, etc.) appear and reduce the estimation and prediction quality of the mathematical models.
While it is possible to create highly complex models with numerous equations and parameters, such an approach presents several challenges, including difficulties in comparing and evaluating data, increased risk of overfitting, and reduced generalizability. Therefore, we will also consider criteria for model selection based on fit and complexity as well as the sensitivity of the model with respect to specific parameters. This also gives valuable information on which political interventions should be more emphasized for possible variations of parameter values.
Furthermore, the presented models, particularly the optimization using the Metropolis algorithm for parameter estimation, are compared with other established methods. The quality of model calculation, as well as computational effort and applicability, play a role in this comparison. Additionally, the spatial integro-differential model is compared with an established agent-based model. Since the macroscopic results align very well, the computationally faster integro-differential model can now be used as a proxy for the slower and non-traditionally optimizable agent-based model, e.g., in order to find an apt control strategy.
In a world where language defines the boundaries of one's understanding, the words of Austrian philosopher Ludwig Wittgenstein resonate profoundly. Wittgenstein's assertion that "Die Grenzen meine Sprache bedeuten die Grenzen meiner Welt" (Wittgenstein 2016: v. 5.6) underscores the vital role of language in shaping our perceptions. Today, in a globalized and interconnected society, fluency in foreign languages is indispensable for individual success. Education must break down these linguistic barriers, and one promising approach is the integration of foreign languages into content subjects.
Teaching content subjects in a foreign language, a practice known as Content Language Integrated Learning (CLIL), not only enhances language skills but also cultivates cognitive abilities and intercultural competence. This approach expands horizons and aligns with the core principles of European education (Leaton Gray, Scott & Mehisto 2018: 50). The Kultusministerkonferenz (KMK) recognizes the benefits of CLIL and encourages its implementation in German schools (cf. KMK 2013a).
With the rising popularity of CLIL, textbooks in foreign languages have become widely available, simplifying teaching. However, the appropriateness of the language used in these materials remains an unanswered question. If textbooks impose excessive linguistic demands, they may inadvertently limit students' development and contradict the goal of CLIL.
This thesis focuses on addressing this issue by systematically analyzing language requirements in CLIL teaching materials, emphasizing receptive and productive skills in various subjects based on the Common European Framework of Reference. The aim is to identify a sequence of subjects that facilitates students' language skill development throughout their school years. Such a sequence would enable teachers to harness the full potential of CLIL, fostering a bidirectional approach where content subjects facilitate language learning.
While research on CLIL is extensive, studies on language requirements for bilingual students are limited. This thesis seeks to bridge this gap by presenting findings for History, Geography, Biology, and Mathematics, allowing for a comprehensive understanding of language demands. This research endeavors to enrich the field of bilingual education and CLIL, ultimately benefiting the academic success of students in an interconnected world.
Bauxite is, among other raw materials, an important material for the production of refractories. However, the availability of refractory raw material grades is limited worldwide. As high iron contents have a negative influence on the temperature resistance of the refractory material produced, a maximum iron oxide content of 2 wt.-% in the bauxite is acceptable. This means that only native raw materials from a few deposits can be used. In order to counteract the problem of too high iron oxide contents in natural bauxites, the possibility of processing bauxite for the refractory industry by using an acid leaching process was to be investigated within the scope of this work. In previous studies on this topic, some investigations on iron leaching have already been carried out on individual bauxites. However, the resulting bauxite composition was mostly neglected in its entirety and only the influences of individual leaching parameters on the leaching result were investigated independently. Moreover, the results and procedures generated are not generally valid and cannot be transferred to bauxites of other chemical or mineralogical compositions.
In order to clarify the open questions in the processing of natural bauxites, leaching tests with hydrochloric acid were carried out on five different bauxites within this work. By using computerized statistical design of experiments, an individual model was generated for each bauxite to predict the optimal factor settings. The factors investigated were acid concentration, solid-acid ratio, leaching temperature, leaching time and grain fraction. The general planning method for bauxite processing developed in this context contains all necessary factors, useful factor settings and the effects to be considered during planning and evaluation. It could be shown that, based on this planning method, a significant, individual model can be created for each of the bauxites investigated, which predicts the optimal leaching settings for the corresponding bauxite. Furthermore, it was found that the transfer of an already created model to another bauxite of similar composition is possible. Based on the results obtained from the leaching tests and model fittings, in combination with further results on the structural analysis of the bauxites, insights into the leachability of various aluminium and iron minerals from bauxite could be gained.
To develop a sustainable acid leaching process, the possibility of regenerating the contaminated acid produced was also tested as an example. It was shown that liquid-liquid extraction can extract more than 99 % of the iron present in the solution and that the regenerated acid can then be reused for the leaching process.