TY - JOUR
AU - Alhaddad, Samer
AU - Förstner, Jens
AU - Grynko, Yevgen
ID - 43018
JF - Journal of Quantitative Spectroscopy and Radiative Transfer
KW - tet_topic_scattering
SN - 0022-4073
TI - Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength
VL - 302
ER -
TY - CONF
AU - Hoffmann, Max
AU - Biehler, Rolf
ED - Trigueros, Marı́a
ED - Barquero, Berta
ED - Hochmuth, Reinhard
ED - Peters, Jana
ID - 31849
KW - Teaching and learning of specific topics in university mathematics
KW - Transition to
KW - across and from university mathematics
KW - Student Teachers
KW - Geometry
KW - Congruence
KW - Double Discontinuity.
T2 - Proceedings of the Fourth Conference of the International Network for Didactic Research in University Mathematics (INDRUM 2022, 19-22 October 2022)
TI - Student Teachers ’ Knowledge of Congruence before a University Course on Geometry
ER -
TY - CONF
AU - Florensa, Ignasio
AU - Hoffmann, Max
AU - Romo Vázquez, Avenilde
AU - Zandieh, Michelle
AU - Martínez-Planell, Rafael
ED - Trigueros, Marı́a
ED - Barquero, Berta
ED - Hochmuth, Reinhard
ED - Peters, Jana
ID - 43097
T2 - Proceedings of the Fourth Conference of the International Network for Didactic Research in University Mathematics (INDRUM 2022, 19-22 October 2022)
TI - Innovations in university teaching based on mathematic education research
ER -
TY - GEN
AU - Süßmann, Johannes
ID - 43186
TI - Pantheon
ER -
TY - JOUR
AB - Lightweight design is a common approach to reduce energy demand in the use stage of vehicles. The production of lightweight materials is usually associated with an increase in energy demand, so the environmental impacts of lightweight structures need to be assessed holistically using a life cycle assessment. To estimate the life cycle environmental impacts of a product in its developmental stage, for example, by life cycle engineering, future changes in relevant influencing factors must be considered. Prospective life cycle assessment provides methods for integrating future scenarios into life cycle assessment studies. However, approaches for integrating prospective life cycle assessment into product development are limited. The objective of this work is to provide the methodological foundation for integrating future scenarios of relevant influencing factors in the development of lightweight structures. The applicability of the novel methodology is demonstrated by a case study of a structural component in a steel, aluminium, and hybrid design. The results show that appropriate decarbonisation measures can reduce the life cycle greenhouse gas emissions by up to 95 percent until 2050. We also found that shifts in the environmentally optimal design are possible in future scenarios. Therefore, the methodology and data provided contribute to improved decision-making in product development.
AU - Ostermann, Moritz
AU - Grenz, Julian
AU - Triebus, Marcel
AU - Cerdas, Felipe
AU - Marten, Thorsten
AU - Tröster, Thomas
AU - Herrmann, Christoph
ID - 43464
IS - 8
JF - Energies
KW - Life Cycle Engineering
KW - Life Cycle Assessment
KW - Lightweight Design
KW - Prospective LCA
KW - Future-oriented LCA
KW - Energy System
KW - Material production
KW - Sustainable production
SN - 1996-1073
TI - Integrating Prospective Scenarios in Life Cycle Engineering: Case Study of Lightweight Structures
VL - 16
ER -
TY - JOUR
AB - A relatively small body of research has been conducted on the near- and long-term effects of study abroad (SA) to date. This existing research suggests that SA effects on language skills tend to be volatile, while the impact on various aspects of learners’ personal, academic, and professional development may be longer-lasting. Yet, learner perspectives on the dynamics and durability of such effects, in particular in the context of short-term SA programs, remain largely unexplored. This study hence investigates the near-term impact of short-term SA programs as experienced by students within the first months and years following their sojourns. A qualitative case-study design is employed to examine the accounts of four American students of German, who studied abroad in Austria for four weeks and were interviewed repeatedly over a period of up to 40 months after their sojourns. The results suggest that, from the students’ perspective, many effects deteriorate in the near term, although the overall sojourn experience still appears influential.
Abstract in German
Nur wenige Forschungsvorhaben haben sich bislang den mittel- bis langfristigen Auswirkungen studentischer Auslandsaufenthalte gewidmet; die bisherige Datenlage deutet jedoch darauf hin, dass die Auswirkungen auf sprachliche Kompetenzen eher unbeständig sind, wohingegen die persönliche, studiums- und berufsbezogene Entwicklung der Lernenden länger von einem Auslandsaufenthalt beeinflusst wird. Die Dynamik und Beständigkeit derartiger Auswirkungen wurden jedoch kaum mit Blick auf kurze Auslandsaufenthalte (≤ acht Wochen) sowie aus der Perspektive der Studierenden erforscht, was die vorliegende Studie insbesondere hinsichtlich mittelfristiger Effekte fokussiert. Mittels eines qualitativen Fallstudiendesigns werden die Interviewdaten vier amerikanischer Deutschlernender untersucht, die sich vier Wochen in Österreich aufhielten und in einem Zeitraum von bis zu 40 Monaten nach ihrem Aufenthalt wiederholt befragt wurden. Die Ergebnisse zeigen, dass viele Auswirkungen eines solchen Aufenthalts aus studentischer Perspektive mittelfristig verblassen, auch wenn der Auslandsaufenthalt im Gesamten weiterhin als einflussreiche Erfahrung wahrgenommen wird.
AU - Müller, Mareike
ID - 44058
IS - 1
JF - Frontiers: The Interdisciplinary Journal of Study Abroad
SN - 2380-8144
TI - Near-Term Effects of Short-Term Study Abroad: A Longitudinal Examination of Learner Perceptions
VL - 35
ER -
TY - JOUR
AB - Die Wirtschaftlichkeit von Wärmemotoren wird maßgeblich durch die Rückführung von Wärme in Rekuperatoren beeinflusst. Beim isobaren Expansionsmotor vom Bush-Typ, einem Wärmemotor, welcher bereits mit Wärmequellen ab 60°C betrieben werden kann, steigt der thermische Wirkungsgrad durch den Einsatz von Rekuperatoren signifikant. Gleichzeitig wirken sich das Fluidvolumen des Wärmeübertragers sowie der beim Betrieb auftretende Druckverlust negativ auf den thermischen Wirkungsrad aus. In dieser Arbeit wird der Zusammenhang von Totvolumen, Druckverlust und Wärmerückgewinnung untersucht und Empfehlungen für den Betrieb von Rekuperatoren am isobaren Expansionsmotor gegeben.
AU - Mügge, Nils
AU - Kronberg, Alexander
AU - Glushenkov, Maxim
AU - Kenig, Eugeny Y.
ID - 42252
IS - 5
JF - Chemie Ingenieur Technik
KW - Isobarer Expansionsmotor
KW - Dynamische Wärmeübertragungsmodellierung
KW - Phasenwechsel
KW - dichte Arbeitsmedien
TI - Untersuchung überlagerter Effekte von Druckverlust und Totvolumen durch Rekuperation am isobaren Expansionsmotor
VL - 95
ER -
TY - JOUR
AB - AbstractThe use of structured measuring systems to prevent wall slip is a common approach to obtain absolute rheological values. Typically, only the minimum distance between the measuring surfaces is used for further calculation, implying that no flow occurs between the structural elements. But this assumption is misleading, and a gap correction is necessary. To determine the radius correction $$\Delta r$$
Δ
r
for specific geometries, we conducted investigations on three Newtonian fluids (two silicon oils and one suspension considered to be Newtonian in the relevant shear rate range). The results show that $$\Delta r$$
Δ
r
is not only shear- and material-independent, but geometry-dependent, providing a Newtonian flow behaviour in a similar viscosity range. Therefore, a correction value can be determined with only minute deviations in different Newtonian fluids. As the conducted laboratory measurements are very time-consuming and expensive, a CFD-approach with only very small deviations was additionally developed and compared for validation purposes. Therefore, simulation is an effective and resource-efficient alternative to the presented laboratory measurements to determine $$\Delta r$$
Δ
r
for the correction of structured coaxial geometries even for non-Newtonian fluids in the future.
AU - Josch, Sebastian
AU - Jesinghausen, Steffen
AU - Dechert, Christopher
AU - Schmid, Hans-Joachim
ID - 36983
JF - Rheologica Acta
KW - rheology
KW - rheometry
KW - suspension
KW - coaxial
KW - correction
SN - 0035-4511
TI - Experimental and simulative determination and correction of the effective gap extension in structured coaxial measuring systems
ER -
TY - CONF
AB - We present an approach for guaranteed constraint satisfaction by means of data-based optimal control, where the model is unknown and has to be obtained from measurement data. To this end, we utilize the Koopman framework and an eDMD-based bilinear surrogate modeling approach for control systems to show an error bound on predicted observables, i.e., functions of the state. This result is then applied to the constraints of the optimal control problem to show that satisfaction of tightened constraints in the purely data-based surrogate model implies constraint satisfaction for the original system.
AU - Schaller, Manuel
AU - Worthmann, Karl
AU - Philipp, Friedrich
AU - Peitz, Sebastian
AU - Nüske, Feliks
ID - 30125
IS - 1
T2 - IFAC-PapersOnLine
TI - Towards reliable data-based optimal and predictive control using extended DMD
VL - 56
ER -
TY - JOUR
AB -
AU - Heck, Tamara
AU - Steinhardt, Isabel
AU - Rahal, Rima-Maria
AU - Schubotz, Moritz
AU - Scholl, Dominik
AU - Behrens, Sarah
ID - 43094
JF - Research Ideas and Outcomes
KW - Open Science
SN - 2367-7163
TI - Bootstrapping the Open Science culture: The fellowship approach
VL - 9
ER -
TY - GEN
ED - Meine, Sabine
ED - Otto, Arnold
ED - Süßmann, Johannes
ID - 35062
SN - 978-3-8260-7218-5
TI - Musiklandschaften zwischen Rhein und Weser. Pluralisierung und Verflechtung entlang des Hellwegs in der Frühen Neuzeit. Unter Mitarbeit v. Markus Lauert
VL - 13
ER -
TY - JOUR
AB - High-contrast slab waveguide Bragg gratings with 1D periodicity are investigated. For specific oblique excitation by semi-guided waves at sufficiently high angles of incidence, the idealized structures do not exhibit any radiative losses, such that reflectance and transmittance for the single port mode add strictly up to one. We consider a series of symmetric, fully and partly etched finite gratings, for parameters found in integrated silicon photonics. These can act as spectral filters with a reasonably flattop response. Apodization can lead to more box shaped reflectance and transmittance spectra. Together with a narrowband Fabry–Perot filter, these configurations are characterized by reflection bands, or transmittance peaks, with widths that span three orders of magnitude.
AU - Hammer, Manfred
AU - Farheen, Henna
AU - Förstner, Jens
ID - 43245
IS - 4
JF - Journal of the Optical Society of America B
KW - tet_topic_waveguide
SN - 0740-3224
TI - How to suppress radiative losses in high-contrast integrated Bragg gratings
VL - 40
ER -
TY - GEN
AU - Meier, Torsten
AU - Grisard, S.
AU - Trifonov, A.V.
AU - Rose, Hendrik
AU - Reichhardt, R.
AU - Reichelt, Matthias
AU - Schneider, C.
AU - Kamp, M.
AU - Höfling, S.
AU - Bayer, M.
AU - Akimov, I.A
ID - 43132
T2 - arxiv:2302.02480
TI - Temporal sorting of optical multi-wave-mixing processes in semiconductor quantum dots
ER -
TY - JOUR
AB - We present strong enhancement of third harmonic generation in an amorphous silicon metasurface consisting of elliptical nano resonators. We show that this enhancement originates from a new type of multi-mode Fano mechanism. These ‘Super-Fano’ resonances are investigated numerically in great detail using full-wave simulations. The theoretically predicted behavior of the metasurface is experimentally verified by linear and nonlinear transmission spectroscopy. Moreover, quantitative nonlinear measurements are performed, in which an absolute conversion efficiency as high as ηmax ≈ 2.8 × 10−7 a peak power intensity of 1.2 GW cm−2 is found. Compared to an unpatterned silicon film of the same thickness amplification factors of up to ~900 are demonstrated. Our results pave the way to exploiting a strong Fano-type multi-mode coupling in metasurfaces for high THG in potential applications.
AU - Hähnel, David
AU - Golla, Christian
AU - Albert, Maximilian
AU - Zentgraf, Thomas
AU - Myroshnychenko, Viktor
AU - Förstner, Jens
AU - Meier, Cedrik
ID - 44097
IS - 1
JF - Light: Science & Applications
KW - tet_topic_meta
SN - 2047-7538
TI - A multi-mode super-fano mechanism for enhanced third harmonic generation in silicon metasurfaces
VL - 12
ER -
TY - BOOK
AU - Bauer, Anna Brigitte
ID - 44083
SN - 978-3-8325-5625-9
TI - Experimentelle Kompetenz Physikstudierender. Entwicklung und erste Erprobung eines performanzorientierten Kompetenzstrukturmodells unter Nutzung qualitativer Methoden
VL - 352
ER -
TY - GEN
AU - Schürmann, Patrick
ID - 43374
TI - A Formal Comparison of Advanced Digital Signature Primitives
ER -
TY - JOUR
AB - Microcellular wood fiber reinforced polymers offer the possibility to reduce the use of fossil raw materials. In particular, thick-walled structures with thicknesses greater than 6 mm offer a high potential for weight savings. This study investigates the cell structures and mechanical properties of injection-molded test specimens. The influence of different thicknesses (6–10 mm) along with different chemical blowing agents (endothermic, exothermic) with varying dosages (0–2 wt%) is analyzed. The investigations reveal that exothermic chemical blowing agents form finer cells consistently to thin-walled structures than endothermic ones. Higher foaming agent content leads to higher pore fractions, with many small cells coalescing into a large open-pore cell network. The mechanical properties depend mainly on the pore content of the sample. The specific tensile properties deteriorate with the use of chemical blowing agents (CFA), whereas the sandwich structure produced with compact edge layers has a positive influence on the specific flexural properties.
AU - Moritzer, Elmar
AU - Flachmann, Felix
ID - 42515
IS - 3
JF - Journal of Cellular Plastics
KW - Materials Chemistry
KW - Polymers and Plastics
KW - General Chemistry
SN - 0021-955X
TI - Morphological and mechanical properties of foamed thick-walled Wood-Plastic-Composite structures
VL - 59
ER -
TY - JOUR
AU - Burmeister, Sascha Christian
AU - Schryen, Guido
ID - 42179
JF - Energy Systems
TI - Distribution Network Optimization: Predicting computation times to design scenario analysis for network operators
ER -
TY - JOUR
AB - Abstract
The accessibility to rheological parameters for concrete is becoming more and more relevant. This is mainly related to the constantly emerging challenges, such as not only the development of high-strength concretes is progressing very fast but also the simulation of the flow behaviour is of high importance. The main problem, however, is that the rheological characterisation of fresh concrete is not possible via commercial rheometers. The so-called concrete rheometers provide valuable relative values for comparing different concretes, but they cannot measure absolute values. Therefore, we developed an adaptive coaxial concrete rheometer (ACCR) that allows the measurement of fresh concrete with particles up to
d
max
=
5.5
mm
{d}_{{\rm{\max }}}=5.5\hspace{.5em}{\rm{mm}}
. The comparison of the ACCR with a commercial rheometer showed very good agreement for selected test materials (Newtonian fluid, shear thinning fluid, suspension, and yield stress fluid), so that self-compacting concrete was subsequently measured. Since these measurements showed a very high reproducibility, the rheological properties of the fresh concrete could be determined with high accuracy. The common flow models (Bingham (B), Herschel–Bulkley, modified Bingham (MB) models) were also tested for their applicability, with the Bingham and the modified Bingham model proving to be the best suitable ones.
AU - Josch, Sebastian
AU - Jesinghausen, Steffen
AU - Schmid, Hans-Joachim
ID - 43034
IS - 1
JF - Applied Rheology
KW - Condensed Matter Physics
KW - General Materials Science
SN - 1617-8106
TI - Development of an adaptive coaxial concrete rheometer and rheological characterisation of fresh concrete
VL - 33
ER -
TY - CHAP
AB - State education in honest tax payment can be understood as a facet of training in citizenship, i.e. as an attempt by the modern state to standardize the behavior of its citizens and to prevent deviations. Based on this Foucauldian understanding, this exploratory article examines tax education in the United States, Spain, and West Germany from the mid-1940s to the late 1980s. During this period, the USA asserted itself as the champion of tax education and Spain consistently tried to emulate this example, albeit with more modest means and different semantic strategies from as early as the 1960s, when it was still under a autoritarian regime. The FRG, however, completely discontinued its few early attempts at tax education from the mid-1950s onwards. Even during the economic crises and tax scandals of the 1970s, there was no relaunch of the programs. The article locates the reasons for this highly uneven development in the different ideal images of the citizen in the three states.
AU - Schönhärl, Korinna
AU - Düll, Nasrin
AU - Ramírez Lugo , Nadya Melina
ED - Sébastien, Guex
ED - Hadrien, Buclin
ID - 44249
T2 - Tax Evasion and Tax Havens since the Nineteenth Century
TI - Tax Education After WWII: How Spain, the USA, and West Germany Tried to Make Their Citizens Pay Honestly
ER -