Refine
Year of publication
- 2023 (264) (remove)
Institute
- Fachbereich Gestaltung (95)
- Fachbereich Medizintechnik und Technomathematik (40)
- Fachbereich Elektrotechnik und Informationstechnik (31)
- ECSM European Center for Sustainable Mobility (25)
- Fachbereich Luft- und Raumfahrttechnik (25)
- Fachbereich Wirtschaftswissenschaften (21)
- Fachbereich Chemie und Biotechnologie (18)
- Fachbereich Energietechnik (14)
- Fachbereich Maschinenbau und Mechatronik (12)
- INB - Institut für Nano- und Biotechnologien (12)
Document Type
- Bachelor Thesis (93)
- Article (80)
- Conference Proceeding (38)
- Part of a Book (24)
- Book (12)
- Patent (3)
- Habilitation (2)
- Master's Thesis (2)
- Preprint (2)
- Talk (2)
Keywords
- Corporate Design (6)
- Editorial (6)
- Illustration (6)
- Typografie (6)
- Nachhaltigkeit (5)
- Produktdesign (5)
- Fotografie (4)
- Publikation (4)
- Design (3)
- Erscheinungsbild (3)
Zugriffsart
- weltweit (102)
- campus (49)
- bezahl (32)
- fachbereichsweit (FB4) (12)
Dynamic loads significantly impact the structural design of propeller blades due to fatigue and static strength. Since propellers are elastic structures, deformations and aerodynamic loads are coupled. In the past, propeller manufacturers established procedures to determine unsteady aerodynamic loads and the structural response with analytical steady-state calculations. According to the approach, aeroelastic coupling primarily consists of torsional deformations. They neglect bending deformations, deformation velocities, and inertia terms. This paper validates the assumptions above for a General Aviation propeller and a lift propeller for urban air mobility or large cargo drones. Fully coupled reduced-order simulations determine the dynamic loads in the time domain. A quasi-steady blade element momentum approach transfers loads to one-dimensional finite beam elements. The simulation results are in relatively good agreement with the analytical method for the General Aviation propeller but show increasing errors for the slender lift propeller. The analytical approach is modified to consider the induced velocities. Still, inertia and velocity proportional terms play a significant role for the lift propeller due to increased elasticity. The assumption that only torsional deformations significantly impact the dynamic loads of propellers is not valid. Adequate determination of dynamic loads of such designs requires coupled aeroelastic simulations or advanced analytical procedures.
On the applicability of several tests to models with not identically distributed random effects
(2023)
We consider Kolmogorov–Smirnov and Cramér–von-Mises type tests for testing central symmetry, exchangeability, and independence. In the standard case, the tests are intended for the application to independent and identically distributed data with unknown distribution. The tests are available for multivariate data and bootstrap procedures are suitable to obtain critical values. We discuss the applicability of the tests to random effects models, where the random effects are independent but not necessarily identically distributed and with possibly unknown distributions. Theoretical results show the adequacy of the tests in this situation. The quality of the tests in models with random effects is investigated by simulations. Empirical results obtained confirm the theoretical findings. A real data example illustrates the application.
Selected problems in the field of multivariate statistical analysis are treated. Thereby, one focus is on the paired sample case. Among other things, statistical testing problems of marginal homogeneity are under consideration. In detail, properties of Hotelling‘s T² test in a special parametric situation are obtained. Moreover, the nonparametric problem of marginal homogeneity is discussed on the basis of possibly incomplete data. In the bivariate data case, properties of the Hoeffding-Blum-Kiefer-Rosenblatt independence test statistic on the basis of partly not identically distributed data are investigated. Similar testing problems are treated within the scope of the application of a result for the empirical process of the concomitants for partly categorial data. Furthermore, testing changes in the modeled solvency capital requirement of an insurance company by means of a paired sample from an internal risk model is discussed. Beyond the paired sample case, a new asymptotic relative efficiency concept based on the expected volumes of multidimensional confidence regions is introduced. Besides, a new approach for the treatment of the multi-sample goodness-of-fit problem is presented. Finally, a consistent test for the treatment of the goodness-of-fit problem is developed for the background of huge or infinite dimensional data.
Motile cilia are hair-like cell extensions that beat periodically to generate fluid flow along various epithelial tissues within the body. In dense multiciliated carpets, cilia were shown to exhibit a remarkable coordination of their beat in the form of traveling metachronal waves, a phenomenon which supposedly enhances fluid transport. Yet, how cilia coordinate their regular beat in multiciliated epithelia to move fluids remains insufficiently understood, particularly due to lack of rigorous quantification. We combine experiments, novel analysis tools, and theory to address this knowledge gap. To investigate collective dynamics of cilia, we studied zebrafish multiciliated epithelia in the nose and the brain. We focused mainly on the zebrafish nose, due to its conserved properties with other ciliated tissues and its superior accessibility for non-invasive imaging. We revealed that cilia are synchronized only locally and that the size of local synchronization domains increases with the viscosity of the surrounding medium. Even though synchronization is local only, we observed global patterns of traveling metachronal waves across the zebrafish multiciliated epithelium. Intriguingly, these global wave direction patterns are conserved across individual fish, but different for left and right noses, unveiling a chiral asymmetry of metachronal coordination. To understand the implications of synchronization for fluid pumping, we used a computational model of a regular array of cilia. We found that local metachronal synchronization prevents steric collisions, i.e., cilia colliding with each other, and improves fluid pumping in dense cilia carpets, but hardly affects the direction of fluid flow. In conclusion, we show that local synchronization together with tissue-scale cilia alignment coincide and generate metachronal wave patterns in multiciliated epithelia, which enhance their physiological function of fluid pumping.
Amino acid-based surfactants are valuable compounds for cosmetic formulations. The chemical synthesis of acyl-amino acids is conventionally performed by the Schotten-Baumann reaction using fatty acyl chlorides, but aminoacylases have also been investigated for use in biocatalytic synthesis with free fatty acids. Aminoacylases and their properties are diverse; they belong to different peptidase families and show differences in substrate specificity and biocatalytic potential. Bacterial aminoacylases capable of synthesis have been isolated from Burkholderia, Mycolicibacterium, and Streptomyces. Although several proteases and peptidases from S. griseus have been described, no aminoacylases from this species have been identified yet. In this study, we investigated two novel enzymes produced by S. griseus DSM 40236ᵀ . We identified and cloned the respective genes and recombinantly expressed an α-aminoacylase (EC 3.5.1.14), designated SgAA, and an ε-lysine acylase (EC 3.5.1.17), designated SgELA, in S. lividans TK23. The purified aminoacylase SgAA was biochemically characterized, focusing on its hydrolytic activity to determine temperature- and pH optima and stabilities. The aminoacylase could hydrolyze various acetyl-amino acids at the Nα -position with a broad specificity regarding the sidechain. Substrates with longer acyl chains, like lauroyl-amino acids, were hydrolyzed to a lesser extent. Purified aminoacylase SgELA specific for the hydrolysis of Nε -acetyl-L-lysine was unstable and lost its enzymatic activity upon storage for a longer period but could initially be characterized. The pH optimum of SgELA was pH 8.0. While synthesis of acyl-amino acids was not observed with SgELA, SgAA catalyzed the synthesis of lauroyl-methionine.
Narzissmus ist ein vielgenutzter Begriff. Häufig wird er im Kontext toxischer Beziehungen verwendet. Nur selten wird das Leben von Frauen thematisiert, deren Mutter narzisstisch ist. Die Graphic Novel „Niemals gut genug“ leistet einen Beitrag zu diesem wenig beachteten Thema. „Niemals gut genug“ schildert anhand von illustrierten Kurzgeschichten alltägliche Situationen von Töchtern narzisstischer Mütter. Die Kurzgeschichten berücksichtigen die Vielfalt narzisstischer Persönlichkeitsstörungen und werfen ein Schlaglicht auf die Vergangenheit narzisstischer Mütter. Dadurch rückt auch die transgenerationale Weitergabe von Narzissmus in den Fokus. „Niemals gut genug“ stellt einen einfühlsamen Zugang zu diesem sensiblen Thema dar und hilft dadurch Betroffenen beim Verstehen und Genesen.
"News Flow" Nachrichten- und Informationsprozesse im digitalen Wandel. In der digitalen Welt sind wir von Informationen aus unterschiedlichen Medien umgeben. Die ständige Verfügbarkeit führt zu Überforderung und Orientierungslosigkeit. Junge Menschen bevorzugen Streaming und Social Media gegenüber traditionellen Nachrichten. Angesichts globaler Krisen und Desinformation sind innovative Lösungen wichtig, um den Informationsfluss zu verbessern. "News Flow" ist eine digitale Anwendung für Alternativen des Nachrichtenkonsums. Sie berücksichtigt individuelle Bedürfnisse und nutzt moderne Technologien. Durch die visuelle Vermittlung wird das Interesse an Nachrichten gesteigert und junge Zielgruppen angesprochen. Diese Arbeit stellt sich den Herausforderungen des digitalen Wandels im Nachrichtenbereich und eröffnet eine neue Perspektive auf den Nachrichtenkonsum.
The aim of the present study was the characterisation of three true subtilisins and one phylogenetically intermediate subtilisin from halotolerant and halophilic microorganisms. Considering the currently growing enzyme market for efficient and novel biocatalysts, data mining is a promising source for novel, as yet uncharacterised enzymes, especially from halophilic or halotolerant Bacillaceae, which offer great potential to meet industrial needs. Both halophilic bacteria Pontibacillus marinus DSM 16465ᵀ and Alkalibacillus haloalkaliphilus DSM 5271ᵀ and both halotolerant bacteria Metabacillus indicus DSM 16189 and Litchfieldia alkalitelluris DSM 16976ᵀ served as a source for the four new subtilisins SPPM, SPAH, SPMI and SPLA. The protease genes were cloned and expressed in Bacillus subtilis DB104. Purification to apparent homogeneity was achieved by ethanol precipitation, desalting and ion-exchange chromatography. Enzyme activity could be observed between pH 5.0–12.0 with an optimum for SPPM, SPMI and SPLA around pH 9.0 and for SPAH at pH 10.0. The optimal temperature for SPMI and SPLA was 70 °C and for SPPM and SPAH 55 °C and 50 °C, respectively. All proteases showed high stability towards 5% (w/v) SDS and were active even at NaCl concentrations of 5 M. The four proteases demonstrate potential for future biotechnological applications.
RƎURB (Reurbanization & Renewable Energy) ist ein Konzept zur Integration von erneuerbaren Energien in einen urbanen Begegnungsraum. Es beinhaltet das Design eines skulpturalen Kleinwindkraftwerks und eines Solar-Pavillons mit einer Sitzlandschaft für einen energieautarken, öffentlichen Platz. Durch die Integration eines W-LAN Hotspots und Lademöglichkeiten in der Sitzlandschaft bringt RƎURB nicht nur grünen Strom in die Stadt, sondern gewährleistet der Bevölkerung auch Zugang zur Digitalisierung und einen kostenlosen Arbeitsraum. Windturbine: Herkömmliche Windräder können in der Stadt nicht genutzt werden. Die RƎURB-Windsäule ist darauf spezialisiert, die urbanen Winde aus allen Richtungen aufzunehmen und funktioniert schon bei einem leichten Windstoß. Durch das elegante Design lassen sich die Technologien als ästhetischen Blickfang in das moderne Stadtbild integrieren.