Eldorado - Repositorium der TU Dortmund

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Bei diesem Service handelt es sich um das Institutionelle Repositorium der Technischen Universität Dortmund. Hier werden Ressourcen aus und für Lehre, Studium und Forschung gespeichert, erschlossen und der Öffentlichkeit zugänglich gemacht.

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Aktuellste Veröffentlichungen

Daphnicyclidin alkaloids 2001–2023
(Wiley, 2024-05-03) Gierok, Jan; Hiersemann, Martin
The Daphniphyllum alkaloids represent a particularly diverse class of complex diterpene alkaloids, which are characterized by their enormous structural diversity. The daphnicyclidins, a subgroup of these alkaloids, stand out due to their unique pentafulvene structural motif. This review article gives an overview of the compounds that have been isolated so far and can be assigned to this subgroup. Furthermore, all synthesis approaches and total syntheses published to date are presented.
Cycloadditionen von Diazoalkenen mit P4 und tBuCP
(Wiley, 2024-07-01) Hauer, Sebastian; Reitz, Justus; Koike, Taichi; Hansmann, Max M.; Wolf, Robert
Reaktionen von Diazoalkenen mit tert-Butylphosphaalkin (tBuCP) und weißem Phosphor (P4) führen zu neuen Phosphorheterocyclen, 3H-1,2,4-Diazamonophospholen und 1,2,3,4-Diazadiphospholen. Die erhaltenen Verbindungen sind seltene Beispiele für neutrale Heterophosphole. Der Bildungsmechanismus der formalen (3+2)-Cycloadditionsprodukte wurde quantenchemisch berechnet und die elektronischen Strukturen analysiert. Die neuen Phosphole bilden strukturell vielfältige Koordinationsverbindungen mit Übergangsmetallen und Hauptgruppenelementen. Angesichts der wachsenden Anzahl stabiler Diazoalkene bietet diese Arbeit einen unmittelbaren Zugang zu neutralen Aza(di-)phospholen als neue Ligandenklasse.
Detecting interactions in high‐dimensional data using cross leverage scores
(Wiley, 2024-11-29) Teschke, Sven; Ickstadt, Katja; Munteanu, Alexander
We develop a variable selection method for interactions in regression models on large data in the context of genetics. The method is intended for investigating the influence of single-nucleotide polymorphisms (SNPs) and their interactions on health outcomes, which is a p ≫ n problem. We introduce cross leverage scores (CLSs) to detect interactions of variables while maintaining interpretability. Using this method, it is not necessary to consider every possible interaction between variables individually, which would be very time-consuming even for moderate amounts of variables. Instead, we calculate the CLS for each variable and obtain a measure of importance for this variable. Calculating the scores remains time-consuming for large data sets. The key idea for scaling to large data is to divide the data into smaller random batches or consecutive windows of variables. This avoids complex and time-consuming computations on high-dimensional matrices by performing the computations only for small subsets of the data, which is less costly. We compare these methods to provable approximations of CLS based on sketching, which aims at summarizing data succinctly. In a simulation study, we show that the CLSs are directly linked to the importance of a variable in the sense of an interaction effect. We further show that the approximation approaches are appropriate for performing the calculations efficiently on arbitrarily large data while preserving the interaction detection effect of the CLS. This underlines their scalability to genome wide data. In addition, we evaluate the methods on real data from the HapMap project.
Data‐driven simulation of functional fatigue in shape memory alloy wires
(Wiley, 2024-09-10) Harnisch, Marius; Bartel, Thorsten; Weyergraf, Lukas; Menzel, Andreas; Schweizer, Ben
Data-driven mechanics offers great potential in engineering applications, where the efficient simulation of complex and, in particular, path-dependent material behavior is often challenging. Within this approach, conventional material models are replaced by data sets containing snapshots of stress, strain and the history of both assumed to be sufficiently accurate representations of the underlying material behavior. Based on these snapshots and on physical admissibility, a distance function is built which is minimized to yield the boundary value problems' solution. The aim of this paper is to apply this framework to accurately simulate the complex behavior of shape memory alloy wires under cyclic loading, under which these materials exhibit a degradation of their features, denoted functional fatigue. The constructed synthetic data sets are enriched by real experimental data, showcasing that the data-driven method is capable of combining both approaches of classic material modeling and modern methods which directly incorporate experimental data.
Fundamental characterization of lubrication effects through various cooling lubricants in the chip formation zone
(Springer Science and Business Media LLC, 2024-08-01) Biermann, Dirk; Saelzer, Jannis; Bergmann, Benjamin; Schenzel, Jan; Menze, Christian J.; Gerken, Julian Frederic; Wolf, Tobias; Denkena, Berend; Möhring, Hans-Christian; Zabel, Andreas
Using cooling lubricants in metalworking requires a high consumption of energy and resources. However, cooling lubricants serve to increase the productivity and quality of these processes. Accordingly, it is necessary to expand the efficiency of their application. This requires fundamental understanding of the working mechanisms. Driven by this motivation, this publication compares six cooling lubricants regarding their lubrication effect in orthogonal cutting. Three types of fluid supply, each conducted on a specific special machine tool for chip formation analysis, and two cutting speeds have been used in the tests. In order to analyze the lubricating effect of these different scenarios, force measurements were carried out and the chip formation was recorded with high-speed recordings. It was found that the process improvements due to lubrication is determined by the interaction of fluid properties, supply strategy and cutting speed. Moreover, clear limitations of water-based cooling lubricants (especially oil-water-emulsions) in the ability to lubricate the chip formation zone have been determined and quantified.