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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.
FinTech is deemed to be an underexplored phenomenon even in academic and real environments. Among (1) “Sustainable FinTech” – the application of information technology as innovation in established financial services providers’ business operation; and (2) “Disruptive FinTech” – the provision of financial products and services by non-incumbents which in most cases are information technology entrepreneurs, the former receives more attention. In order to contribute to Disruptive FinTech category, the thesis strive to examine Entrepreneurial Strategy framework applied for technology players taking part in Vietnam financial market.
Digital Transformation Maturity of Vietnam Aviation Industry: The Effect of Organizational Readiness
(2023)
The paper studies the digital transformation maturity in the context of the aviation industry in Vietnam. Digital transformation can mean enhancing existing processes, finding new opportunities within existing business domains, or finding new opportunities outside existing business domains. In the era of post Covid-19, digital transformation will play a vital role in the recovery with the support from digital technology to leverage the communication and implementation of new projects or changes.
Digital transformation and digital transformation maturity sometimes are used indistinguishing, but they are two different definitions. This paper will further explain the differences and will apply digital transformation maturity as a scale for the digital transformation in the report.
Due to the lack of experiment in the relationship between digital transformation maturity and the organizational readiness, the study will explore four components of organizational readiness, including digital leadership, digital culture, digital capabilities, and digital partnering.
The paper is a study focusing on exploring which factors and examining the impact of those factors influencing the entrepreneurial intention among students in the Construction industry, specifically among students of Hanoi Construction University and Hanoi Architecture University. The study also mentions some solution of this findings for entrepreneurship in the Construction field in Vietnam that the author might think of based on this research work for future study. The Theory of planned behavior is used as the theoritical framework for this study. Both qualitative and quantitative methods are employed. The questionaire will be conducted among students of the two universities mentioned above. Then, an exploratory factor analysis (EFA) will performed to test the validity of the constructs. The research findings provide factors and their impact factors influencing the entrepreneurial intention and propose some solutions to improve the entrepreneurship in the Construction field in Vietnam.
Digital transformation is a prevailing trend in the world, especially in dynamic Asia. Vietnam has recorded remarkable changes in the economy as domestic enterprises have made new strides in the digital transformation process. MB Bank, one of the prestigious financial groups in Vietnam, also takes advantage of digital transformation to have the opportunity to break through to become a large-scale technology enterprise with many factors such as improving customer experience, increasing customer base and increasing customer satisfaction. enhance competitiveness, build trust and loyalty for customers. However, in the process of converting MB, there are also many challenges that require banks to have appropriate policies to handle. It can be said that MB Bank is a typical case study of digital transformation in the banking sector in Vietnam.
Durch die zunehmende Wichtigkeit und Dringlichkeit des Klimawandels sind Unternehmen aufgefordert, einen Beitrag zu nachhaltiger Entwicklung zu leisten, insbesondere durch die jüngeren Generationen. Bisherige Beiträge von Unternehmen werden jedoch als unzureichend kritisiert, was insbesondere am mangelnden Engagement der Mitarbeiterinnen und Mitarbeiter für Nachhaltigkeit in Unternehmen liegen könnte. In diesem Zusammenhang wurde in den letzten Jahren Gamification als ein vielversprechendes, innovatives Tool um nachhaltige Verhaltensweisen der Mitarbeiterinnen und Mitarbeiter am Arbeitsplatz zu motivieren, vorgeschlagen und zunehmend erforscht. Es gibt jedoch nur wenige Studien und anwendbare Gamification-Lösungen, die mehr als ein spezifisches Nachhaltigkeitsthema behandeln und somit eine ganzheitliche Perspektive auf nachhaltige Verhaltensweisen am Arbeitsplatz einnehmen. Darüber hinaus mangelt es bisheriger Forschung an einem umfassenden Verständnis dafür, wie verschiedene Gamification-Elemente spezifische psychologische Effekte hervorrufen, wie sich diese in Verhaltensänderungen manifestieren und wie diese wiederum kumulativ in messbaren Unternehmensergebnissen resultieren. Der Weg von Gamification als ”Input” zu unternehmerischer Nachhaltigkeit als ”Output” ist also bislang unerforscht.
Diese Dissertation schließt diese Lücke, indem eine ganzheitliche gamifizierte Intervention konzipiert, gestaltet und evaluiert wird, die Mitarbeiterinnen und Mitarbeiter bei verschiedenen nachhaltigen Verhaltensweisen in ihren täglichen Aktivitäten unterstützt. Das Projekt verwendet einen designwissenschaftlichen Forschungsansatz, der die Mitarbeiterinnen und Mitarbeiter eng in die schrittweise Entwicklung der Lösung einbezieht. Als Teil des iterativen Designprozesses werden in dieser Dissertation sechs Studien vorgestellt, um das theoretische Verständnis von Gamification für nachhaltige Verhaltensweisen von Mitarbeiterinnen und Mitarbeitern zu erweitern. Zunächst wird ein umfassender Überblick über die bestehende Forschung zu Gamification für nachhaltiges Mitarbeiterverhalten gegeben, wobei Gamification-Designs und Ergebnisse früherer Studien analysiert und eine Agenda für die weitere Forschung aufgezeigt werden (Studie 1). Danach werden theoretische Grundlagen der Forschung zu Gamification, Serious Games und Game-based Learning (Studie 2) und empirische Gestaltungsprinzipien
für Gamification und persuasive Systeme (Studie 3) als Basis für die erfolgreiche Gestaltung gamifizierter Anwendungen systematisch untersucht. Anschließend werden in empirischen Studien Motivationen der Mitarbeiterinnen und Mitarbeiter für nachhaltiges Verhalten erforscht und ihre Erwartungen an Gestaltungsmerkmale beleuchtet (Studie 4) sowie kontextuelle Herausforderungen und Gestaltungsdilemmata bei der Implementierung von Gamification in einem organisatorischen Kontext aufgezeigt (Studie 5). Schließlich wird in einer quantitativen Feldstudie (Studie 6) untersucht, wie verschiedene Gamification-Designs nachhaltiges Mitarbeiterverhalten und unternehmerische Nachhaltigkeitskennzahlen in Organisationen beeinflussen. Basierend auf den Ergebnissen wird in dieser Dissertation ein umfassendes Framework für Gamification für nachhaltiges Mitarbeiterverhalten präsentiert, welches Design-, individuelle Verhaltens- und Unternehmensperspektiven einbezieht. Schließlich werden darauf aufbauend praktische Empfehlungen für die Gestaltung von Gamification zur Förderung nachhaltigen Mitarbeiterverhaltens am Arbeitsplatz präsentiert.
Counts of SARS-CoV-2-related deaths have been key numbers for justifying severe political, social and economical measures imposed by authorities world-wide. A particular focus thereby was the concomitant excess mortality (EM), i.e. fatalities above the expected all-cause mortality (AM). Recent studies, inter alia by the WHO, estimated the SARS-CoV-2-related EM in Germany between 2020 and 2021 as high as 200 000. In this study, we attempt to scrutinize these numbers by putting them into the context of German AM since the year 2000. We propose two straightforward, age-cohort-dependent models to estimate German AM for the ‘Corona pandemic’ years, as well as the corresponding flu seasons, out of historic data. For Germany, we find overall negative EM of about −18 500 persons for the year 2020, and a minor positive EM of about 7000 for 2021, unveiling that officially reported EM counts are an exaggeration. In 2022, the EM count is about 41 200. Further, based on NAA-test-positive related death counts, we are able to estimate how many Germans have died due to rather than with CoViD-19; an analysis not provided by the appropriate authority, the RKI. Through 2020 and 2021 combined, our due estimate is at no more than 59 500. Varying NAA test strategies heavily obscured SARS-CoV-2-related EM, particularly within the second year of the proclaimed pandemic. We compensated changes in test strategies by assuming that age-cohort-specific NAA-conditional mortality rates during the first pandemic year reflected SARS-CoV-2-characteristic constants.
X-ray computer tomography (XRT) is a three-dimensional, nondestructive, and thus reproducible examination method that allows for the investigation of internal and external structures of objects. Due to its characteristics, the XRT technique has increasingly established itself as an alternative examination method and is also applied in the field of mineral processing. Within this work, XRT is used to investigate the influence of hydrochloric acid leaching of iron-rich bauxites on grain composition. Acid leaching is a promising method for the beneficiation of iron-rich bauxites for refractories. Many studies have already established that leaching with hydrochloric acid can reduce the Fe₂O₃ content in bauxites. However, apart from the influence of the leaching process on the composition of the bauxites, aspects such as the influence of the acid on the exact grain constitution or the porosity behavior have rarely been considered so far. To address these open questions, XRT analysis was used to examine and characterize various bauxites. By comparing identical grains before and after leaching, it was observed that in gibbsite bauxites the acid penetration is deeper, and the volume decreases significantly. In diasporic and boehmitic bauxites, clear leaching edges can be seen in which the iron content has been reduced.