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Applied Additively Manufactured Ceramics for the Built Environment
Get PDFThis dissertation focuses on the application of additive manufacturing technologies for ceramic materials and their use in building construction. After putting the topic of ceramics in architecture into its technical and historic context, a variety of preceding projects from this field are presented.
From evaluating these preliminary findings, a research-occasion has been derived, featuring a set of hypothesises on how an industrialized production of such components may be realized. By investigating two of these hypotheses in more detail, methodologies to exceed the geometric freedom, as well as to harmonize the printed component’s appearance with commercial ceramic building products have been developed.
In order to assess the usability of the developed methodologies in an industrial context, a case study was carried out. A commercially-available product, the nesting bricks, which are yet being produced in a manual process, were used as an object of study. First, their geometries were printed directly, before optimizations have been made in a second iteration. Through this, time-savings, as well as a more favourable appearance were achieved.
Ultimately, conclusions drawn from the multiple stages of this research have been summarized and an outlook was presented on how a further utilization of this technology may look like
Dislocation-mediated and twinning-induced plasticity of CoCrFeMnNi in varying tribological loading scenarios
Get PDFCoarse-grained, metallic materials undergo microstructure refinement during tribological loading. This in turn results in changing tribological properties, so the microstructural evolution is a parameter which should not be underestimated while designing tribological systems. Single-trace experiments were conducted to understand the initiation of deformation mechanisms acting in various tribological systems. The main scope of this work was to investigate the influence of normal and friction forces as well as crystal orientations on the dominating deformation mechanism in a face-centred cubic concentrated solid solution. While varying the normal force is easily realised, varying friction forces were achieved by using several counter body materials paired against CoCrFeMnNi. The subsurface deformation layer was either mediated through dislocation slip or twinning, depending on the grain orientation and on the tribological system. A layer dominated by dislocation-based deformation is characterised by lattice rotation, the formation of a dislocation trace line or subgrain formation. Such behaviour is observed for tribological systems with a low friction coefficient. For systems dominated by deformation twinning, three types of twin appearance were observed: small twins interacting with the surface, large twins and grains with two active twin systems. Two different twinning mechanisms are discussed as responsible for these characteristics
A best practice for gamification in large companies: An extensive study focusing inter-generational acceptance
No full textGamification is increasingly successful in the field of education and health. However, beyond call-centers and applications in human resources, its utilization within companies remains limited. In this paper, we examine the acceptance of gamification in a large company (with over 17,000 employees) across three generations, namely X, Y, and Z. Furthermore, we investigate which gamification elements are suited for business contexts, such as the dissemination of company principles and facts, or the organization of work tasks. To this end, we conducted focus group discussions, developed the prototype of a gamified company app, and performed a large-scale evaluation with 367 company employees. The results reveal statistically significant intergenerational disparities in the acceptance of gamification: younger employees, especially those belonging to Generation Z, enjoy gamification more than older employees and are most likely to engage with a gamified app in the workplace. The results further show a nuanced range of preferences regarding gamification elements: avatars are popular among all generations, badges are predominantly appreciated by Generations Z and Y, while leaderboards are solely liked by Generation Z. Drawing upon these insights, we provide recommendations for future gamification projects within business contexts. We hope that the results of our study regarding the preferences of the gamification elements and understanding generational differences in acceptance and usage of gamification will help to create more engaging and effective apps, especially within the corporate landscape
Claeys, Gregory: Utopianism for a Dying Planet. Life After Consumerism, 608 S., Princeton UP, Princeton, NJ/Oxford 2022.
No full textNach den durch Extremwetter gekennzeichneten Sommern der vergangenen Jahre dürfte es auch in den westlichen Demokratien nur noch wenige Menschen geben, denen das Ausmaß des Klimawandels keine existenziellen Sorgen bereitet. Zu heiß und trocken waren die letzten Sommer, zu heftig die Regenfälle, und wer nur einigermaßen regelmäßig die Nachrichten verfolgt, wird noch mit ganz anderen Schreckensmeldungen konfrontiert: vom Abschmelzen der Gletscher, der Versteppung immer größerer Flächen bis hin zu dem Wassernotstand, der sich mittlerweile auch in Südeuropa ausbreitet. Fest steht, die Menschheit steht vor einem Scheideweg. Insbesondere der konsumorientierte Lebensstil im globalen Norden, zunehmend auch in den bevölkerungsreichen Schwellenländern, der immer mehr Ressourcen verbraucht, muss enden. Wie schwierig, ja geradezu unmöglich indes der Ausstieg aus liebgewonnenen Verhaltensmustern und Konsumbedürfnissen – die Fernreise, der SUV, die Flugmango, das Steak, das neue Kleid, das im kommenden Jahr entsorgt wird – ist, erleben zumindest die Ober- und Mittelklassen der Industrienationen in ihrer alltäglichen Praxis. Moderne Gesellschaften sind kapitalistische Gesellschaften, in denen die soziale Integration wesentlich über den Konsum erfolgt
Resilience beyond insurance: coordination in crisis governance
No full textThe latest report by the Intergovernmental Panel on Climate Change (IPCC) warns of an increase in heavy rainfall events due to global warming and climate change, which can result in significant economic costs for insurance companies and businesses. To address this challenge, insurance companies are focusing on developing new risk management strategies and offering new products such as flood insurance. However, the article argues that effective and feasible coordination shortens recovery time and can therefore drastically reduce the financial costs of a crisis—that is, the insurance costs. The paper analyses the deficit in crisis management during heavy rain events in Germany, based on the 2021 Ahr valley flood. The analysis is conducted based on document analysis and interviews and focuses on three areas of deficit: coordination between crisis staffs and (1) civil society, (2) emergency responders, and (3) political leaders. The paper highlights the importance of coordination during a crisis, which can help to address the crisis more efficiently and effectively, minimise damage and get communities back on their feet faster. The paper recommends policy changes to improve interface management and disaster management coordination
Surface tension behavior of superspreading and non-superspreading trisiloxane surfactants
No full textOne parameter frequently considered to be relevant for superspreading of trisiloxane surfactants is surface tension kinetics. In the scientific literature, some experimental results reported for trisiloxane surfactants are in contradiction with fundamental concepts of surfactant monomer diffusion. Therefore, maximum bubble pressure tensiometry has been used to determine dynamic surface tension (DST) of two types of trisiloxane surfactants: superspreader and non-superspreader. Results show that both surfactants behave similarly at concentrations below critical micelle concentration (CMC), as expected. The CMC curves, as determined by drop shape analysis, confirmed that the more hydrophilic non-superspreader has a higher CMC as compared to the more hydrophobic superspreader. Accordingly, the lower surfactant monomer concentration of the superspreader results in a higher DST than the non-superspreader at the same surface age. So, in contrary to claims in the literature, there is nothing mysterious or unexpected concerning the surface tension behavior of trisiloxane surfactants
Temporally consistent sequence-to-sequence translation of cataract surgeries
No full textPurpose: Image-to-image translation methods can address the lack of diversity in publicly available cataract surgery data. However, applying image-to-image translation to videos—which are frequently used in medical downstream applications—induces artifacts. Additional spatio-temporal constraints are needed to produce realistic translations and improve the temporal consistency of translated image sequences.
Methods: We introduce a motion-translation module that translates optical flows between domains to impose such constraints. We combine it with a shared latent space translation model to improve image quality. Evaluations are conducted regarding translated sequences’ image quality and temporal consistency, where we propose novel quantitative metrics for the latter. Finally, the downstream task of surgical phase classification is evaluated when retraining it with additional synthetic translated data.
Results: Our proposed method produces more consistent translations than state-of-the-art baselines. Moreover, it stays competitive in terms of the per-image translation quality. We further show the benefit of consistently translated cataract surgery sequences for improving the downstream task of surgical phase prediction.
Conclusion: The proposed module increases the temporal consistency of translated sequences. Furthermore, imposed temporal constraints increase the usability of translated data in downstream tasks. This allows overcoming some of the hurdles of surgical data acquisition and annotation and enables improving models’ performance by translating between existing datasets of sequential frames
On Modified Halpern and Tikhonov–Mann Iterations
No full textWe show that the asymptotic regularity and the strong convergence of the modified Halpern iteration due to T.-H. Kim and H.-K. Xu and studied further by A. Cuntavenapit and B. Panyanak and the Tikhonov–Mann iteration introduced by H. Cheval and L. Leuştean as a generalization of an iteration due to Y. Yao et al. that has recently been studied by Boţ et al. can be reduced to each other in general geodesic settings. This, in particular, gives a new proof of the convergence result in Boţ et al. together with a generalization from Hilbert to CAT(0) spaces. Moreover, quantitative rates of asymptotic regularity and metastability due to K. Schade and U. Kohlenbach can be adapted and transformed into rates for the Tikhonov–Mann iteration corresponding to recent quantitative results on the latter of H. Cheval, L. Leuştean and B. Dinis, P. Pinto, respectively. A transformation in the converse direction is also possible. We also obtain rates of asymptotic regularity of order O(1/n) for both the modified Halpern (and so in particular for the Halpern iteration) and the Tikhonov–Mann iteration in a general geodesic setting for a special choice of scalars
Application of nickel-doped graphene nanotubes to modified GCE as a sensitive electrochemical sensor for the antipsychotic drug clozapine in spiked human blood serum samples
No full textClozapine (CLZ) is one of the most vital medications for managing schizophrenia, and the timely measurement of CLZ levels has been recognized as an obstacle to the wider use of CLZ. Herein, for the first time, nickel-doped graphene nanotubes (Ni@GRNT) were used to construct an electrochemical CLZ sensor by drop coating Ni@GRNT suspension on a glassy carbon electrode. The Ni@GRNT was synthesized and characterized using X‐ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrochemical behavior and influence of different physicochemical factors of sensing electrodes were investigated by using cyclic voltammetry, EIS technique, and differential pulse voltammetry techniques. Also, the catalytic rate constant (kcat) and the transfer coefficient (α) were calculated. The modified electrode illustrated satisfactory linear range, detection limit (LOD), reusability, and reproducibility results. At optimal experimental conditions, measurements can be performed at a broad linear dynamic range of 0.3 nmol L⁻¹–60.0 μmol L⁻¹ CLZ and with a LOD of 0.1 nmol L⁻¹. The sensitivity value was estimated to be 3.06 μA µmol L⁻¹ cm⁻². Ultimately, this platform was successfully used for CLZ sensing in spiked human blood serum and tablet samples with an accuracy of > 93%
Stabilization of spline bases by extension
No full textWe present a method to stabilize bases with local supports by means of extension. It generalizes the known approach for tensor product B-splines to a much broader class of functions, which includes hierarchical and weighted variants of polynomial, trigonometric, and exponential splines, but also box splines, T-splines, and other function spaces of interest with a local basis. Extension removes elements that cause instabilities from a given basis by linking them with the remaining ones by means of a specific linear combination. The two guiding principles for this process are locality and persistence. Locality aims at coupling basis functions whose supports are close together, while persistence guarantees that a given set of globally supported functions, like certain monomials in the case of polynomial splines, remain in the span of the basis after extension. Furthermore, we study how extension influences the approximation power and the condition of Gramian matrices associated with the basis, and present a series of examples illustrating the potential of the method