Eldorado
The Eldorado digital repository system captures, stores, indexes, preserves, and distributes digital research material.
https://eldorado.tu-dortmund.de:443
2024-03-29T00:11:36Z
2024-03-29T00:11:36Z
Der Kongress der Dinge
http://hdl.handle.net/2003/42412
2024-03-28T23:15:25Z
2024-01-01T00:00:00Z
Title: Der Kongress der Dinge
Editors: Watzlawik, Jan C.
2024-01-01T00:00:00Z
A computer vision sensor for the parallelization of actively regulated capillary slug flow microreactors
Gladius, Anoj Winston
Mylenbusch, Jonas A.
Agar, David William
http://hdl.handle.net/2003/42411
2024-03-28T23:13:20Z
2023-09-11T00:00:00Z
Title: A computer vision sensor for the parallelization of actively regulated capillary slug flow microreactors
Authors: Gladius, Anoj Winston; Mylenbusch, Jonas A.; Agar, David William
Abstract: In this work, a computer vision sensor for the extraction of slug length, slug velocity and phase ratio from capillary liquid–liquid slug flows from video feeds in real-time, including the necessary post-processing algorithms, is developed. The developed sensor is shown to be capable of simultaneously monitoring multiple capillaries and provides reasonable accuracy at less than 3.5% mean relative error. Subsequently, the sensor is used for the control of a parallelized and actively regulated dual-channel slug flow capillary microreactor setup. As a model reaction, the solvent-free epoxidation of methyl oleate with hydrogen peroxide and a phase-transfer catalyst based on tungstophosphoric acid and a quaternary ammonium salt to yield the product 9,10-epoxystearic acid methyl ester is conducted. A space–time yield of 0.679 kg L−1 h−1 is achieved.
2023-09-11T00:00:00Z
Programmable mixed-signal circuits
Tappertzhofen, Stefan
http://hdl.handle.net/2003/42410
2024-03-28T23:13:58Z
2023-11-16T00:00:00Z
Title: Programmable mixed-signal circuits
Authors: Tappertzhofen, Stefan
Abstract: A novel concept for programmable mixed-signal circuits is presented based on programmable transmission gates. For implementation, memristively switching devices are suggested as the most promising candidates for realization of fast and small-footprint signal routing switches with small resistance and capacity. As a proof-of-concept, LT Spice simulations of digital and analogue example circuits implemented by the new concept are demonstrated. It is discussed how important design parameters can be tuned in the circuity. Compared to competing technologies such as Field Programmable Analogue Arrays or Application-Specific Integrated Circuits, the presented concept allows for development of ultra-flexible, reconfigurable, and cheap embedded mixed-signal circuits for applications where only limited space is available or high bandwidth is required.
2023-11-16T00:00:00Z
Spectroscopic analysis of structural and chemical properties of solid thin film lubricants
Thomann, Carl Arne
http://hdl.handle.net/2003/42409
2024-03-28T23:12:11Z
2023-01-01T00:00:00Z
Title: Spectroscopic analysis of structural and chemical properties of solid thin film lubricants
Authors: Thomann, Carl Arne
Abstract: Upon tribological loading, especially at elevated temperatures or in humidity, chemical transitions and structural processes are known to take place in solid thin film lubricants like amorphous carbons (a-C) and molybdenum disulphide (MoS2) and to critically limit their performance. To accommodate those restrictions, a selection of element-modifications is applied on a regular basis. General aim is to analyse structural and chemical properties in a-C and MoS2 thin films. The understanding of those is a prerequisite for the scientific conception around tribo-film formation, which is identified as critical part of the tribological system.
For this, Raman microscopy is augmented by a setup for optical temperature tuning via a pulsed laser. This work summarises the Raman-accessible film properties and the changes after element-modification and thermal impact. In a-C studies of optical temperature tuning, two ordering mechanisms are found, which are affected by element-modification. As initial reaction upon heating, graphitic clusters within an amorphous matrix increase in number and, subsequently, in size upon further heating. A Five Stage-model of structural relaxation in a-C is proposed. For MoS2, it is found that the formation of tribo-films is strongly dependent on the working environment, the tribo-film gains temperature resistance over untouched thin film material, and tribo-film formation is affected by element-modification. In studies of optical temperature tuning, an initial ordering process of amorphous MoS2 and subsequent chemical reaction to distinct oxides were found.
The results are useful for identification of defect mechanisms and possibly for gauging the status of wear in a-C and MoS2 thin films. Element-modification in a-C with previously unknown effects may now be interpreted within a found Five Stage-model; similarly, the behaviour of MoS2 spectra upon heating can now be evaluated.
2023-01-01T00:00:00Z
Precision measurements of 𝐬𝐢𝐧 (𝟐𝜷) with the LHCb experiment
Meier, Gerwin
http://hdl.handle.net/2003/42408
2024-03-28T23:12:17Z
2023-01-01T00:00:00Z
Title: Precision measurements of 𝐬𝐢𝐧 (𝟐𝜷) with the LHCb experiment
Authors: Meier, Gerwin
Abstract: High-precision measurements of observables of the Standard Model of particle physics, like the CKM matrix parameters, are key to answering the open questions of particle physics. The most precise CKM angle sin(2β) can be optimally determined by a decay-time dependent measurement of CP violation in B→ψKS0 decays. In this thesis data from B→J/ψ(→μμ)KS0, B→ψ(2S)(→μμ)KS0 and B→J/ψ(→ee)KS0 decays is analysed with KS0→π+π- collected at a centre-of-mass energy of √s = 13TeV with pp collisions by the LHCb experiment between 2015 and 2018. The data corresponds to an integrated luminosity of 6/fb and results in the combination of all three decays for the CP violation parameters in
S(ψKS0) = 0.717 +/- 0.013 (stat.) +/- 0.008 (syst.),
C(ψKS0) = 0.008 +/- 0.012 (stat.) +/- 0.003 (syst.),
where S corresponds to sin(2β). This is consistent with the Standard Model predictions and with previous measurements. Furthermore, this is the most precise single measurement and more precise than the current world average.; Hochpräzessionsmessungen von Observablen des Standardmodells der Teilchenphysik, wie die Parameter der CKM-Matrix, sind entscheidend, um offene Fragen der Teilchenphysik zu beantworten. Der am genauesten gemessene CKM Winkel sin(2β) kann optimal gemessen werden mit Zerfallszeit-abhängigen CP-verletzenden Messungen in B→ψKS0 Zerfällen. In dieser Arbeit wurden Daten von B→J/ψ(→μμ)KS0, B→ψ(2S)(→μμ)KS0 und B→J/ψ(→ee)KS0 Zerfällen mit KS0→π+π- analysiert. Diese wurden aufgenommen bei einer Schwerpunktsenergie von √s = 13TeV mit pp Kollisionen am LHCb-Experiment zwischen 2015 und 2018. Die Daten entsprechen einer integrierten Luminosität von 6/fb und resultieren in der Kombination von allen drei Zerfällen für die CP-verletzenden Parameter in
S(ψKS0) = 0.717 +/- 0.013 (stat.) +/- 0.008 (syst.),
C(ψKS0) = 0.008 +/- 0.012 (stat.) +/- 0.003 (syst.),
wobei S sin(2β) entspricht. Das ist konsistent mit den Vorhersagen des Standardmodells und vorherigen Messungen. Die Messung erreicht die größte Genauigkeit einer Einzelmessung und ist genauer als der Weltmittelwert.
2023-01-01T00:00:00Z
Organische Hybrid-Verbindungen auf Basis elektronenreicher Olefine
Antoni, Patrick Wolf
http://hdl.handle.net/2003/42407
2024-03-27T23:12:36Z
2023-01-01T00:00:00Z
Title: Organische Hybrid-Verbindungen auf Basis elektronenreicher Olefine
Authors: Antoni, Patrick Wolf
2023-01-01T00:00:00Z
A shifting regulatory landscape: the impact of corporate social responsibility disclosure and EU regulations on the judgments of investors and non-financial stakeholders
Chrzan, Sandra
http://hdl.handle.net/2003/42406
2024-03-27T08:10:09Z
2024-01-01T00:00:00Z
Title: A shifting regulatory landscape: the impact of corporate social responsibility disclosure and EU regulations on the judgments of investors and non-financial stakeholders
Authors: Chrzan, Sandra
Abstract: This dissertation presents a thorough investigation of Corporate Social Responsibility (CSR) disclosures across four essays, examining its development, present implementations, regulatory shifts, and impacts on diverse stakeholders. Prompted by the European Union's European Green Deal, the growing focus on sustainability and the incorporation of Environmental, Social, and Governance (ESG) factors into corporate strategies have led to an increased demand for transparent disclosure of companies' ESG performance. This analysis highlights a significant increase in sustainability reporting throughout Europe.
Nonetheless, a pronounced lack of consensus and standardization in CSR reporting is identified in this examination, particularly in Germany. The investigation progresses to analyze CSR disclosure's effects on both financial and non-financial stakeholders, addressing the challenges of information asymmetry and the evolving regulatory environment in the EU, which seeks to direct investments towards sustainable entities. The impact of CSR disclosures on corporate reputation among non-financial stakeholders is evaluated. Empirical results indicate no significant impact of CSR reporting on corporate reputation within this group, suggesting that CSR reports may not serve as an effective communication tool. In contrast, CSR disclosures via corporate websites are found to significantly influence corporate reputation among non-financial stakeholders. Further, we explore the EU taxonomy's effect on investors’ judgments, revealing that EU taxonomy indicators enhance transparency for professional investors. Notably, EU taxonomy indicators convey positive signals to private investors, even if the taxonomy indicators are below the presented industry average. Drawing upon these findings, the concluding essay discusses the legal implications for fostering green investments.
By merging empirical evidence with theoretical discourse, this dissertation aims to contribute to the understanding and development of CSR reporting. It highlights the critical need for precise, standardized reports taking into account the individual requirements of diverse stakeholder groups. This approach is intended to facilitate sustainable decisions and improve corporate reputation, in alignment with the EU's objectives towards a sustainable economy.
2024-01-01T00:00:00Z
The squeezed dark nuclear spin state in lead halide perovskites
Kirstein, E.
Smirnov, D. S.
Zhukov, E. A.
Yakovlev, D. R.
Kopteva, N. E.
Dirin, D. N.
Hordiichuk, O.
Kovalenko, M. V.
Bayer, M.
http://hdl.handle.net/2003/42405
2024-03-25T23:12:07Z
2023-10-21T00:00:00Z
Title: The squeezed dark nuclear spin state in lead halide perovskites
Authors: Kirstein, E.; Smirnov, D. S.; Zhukov, E. A.; Yakovlev, D. R.; Kopteva, N. E.; Dirin, D. N.; Hordiichuk, O.; Kovalenko, M. V.; Bayer, M.
Abstract: Coherent many-body states are highly promising for robust quantum information processing. While far-reaching theoretical predictions have been made for various implementations, direct experimental evidence of their appealing properties can be challenging. Here, we demonstrate optical manipulation of the nuclear spin ensemble in the lead halide perovskite semiconductor FAPbBr3 (FA = formamidinium), targeting a long-postulated collective dark state that is insensitive to optical pumping after its build-up. Via optical orientation of localized hole spins we drive the nuclear many-body system into this entangled state, requiring a weak magnetic field of only a few milli-Tesla strength at cryogenic temperatures. During its fast establishment, the nuclear polarization along the optical axis remains small, while the transverse nuclear spin fluctuations are strongly reduced, corresponding to spin squeezing as evidenced by a strong violation of the generalized nuclear squeezing-inequality with ξs < 0.5. The dark state corresponds to an ~35-body entanglement between the nuclei. Dark nuclear spin states can be exploited to store quantum information benefiting from their long-lived many-body coherence and to perform quantum measurements with a precision beyond the standard limit.
2023-10-21T00:00:00Z
Modification of 316L steel powders with bronze using high energy ball milling for use as a binder component in PBF-LB/M printing of diamond-metal matrix composites
Tillmann, Wolfgang
Ferreira, Manuel Pinho
http://hdl.handle.net/2003/42404
2024-03-25T23:13:40Z
2023-10-17T00:00:00Z
Title: Modification of 316L steel powders with bronze using high energy ball milling for use as a binder component in PBF-LB/M printing of diamond-metal matrix composites
Authors: Tillmann, Wolfgang; Ferreira, Manuel Pinho
Abstract: For the processing of diamond-metal matrix composites, the powder bed fusion using a laser for metals (PBF-LB/M), represents a new promising method for the additive manufacturing of diamond tools for concrete and rock machining, even with more complicated geometries. Previous research activities show a strong tendency for cracking and delamination during the construction process of the samples. This behavior is caused by thermal residual stresses associated with the embedded diamonds. To control these negative effects on the process side, the volume energy density is reduced accordingly, which, however, led to increased pore formation. This publication deals with an approach on the material side to modify a 316L stainless steel base powder with an addition of 20 wt% bronze via a high energy ball milling (HEBM) process in such a way that a homogeneous solid solution phase is created. A significantly increasing of the melting interval and a decreasing of both solidus and liquidus temperature was observed, which can reduce pore formation in the PBF-LB/M-process. In addition, XRD-diffractometry and SEM/EDS-analysis showed that the homogeneous solid solution phase of this alloyed powder segregates again into Fe- and Cu-rich phases when heated up to the melting point.
2023-10-17T00:00:00Z
Designs for the simultaneous inference of concentration–response curves
Schürmeyer, Leonie
Schorning, Kirsten
Rahnenführer, Jörg
http://hdl.handle.net/2003/42403
2024-03-22T23:13:06Z
2023-10-19T00:00:00Z
Title: Designs for the simultaneous inference of concentration–response curves
Authors: Schürmeyer, Leonie; Schorning, Kirsten; Rahnenführer, Jörg
Abstract: Background:
An important problem in toxicology in the context of gene expression data is the simultaneous inference of a large number of concentration–response relationships. The quality of the inference substantially depends on the choice of design of the experiments, in particular, on the set of different concentrations, at which observations are taken for the different genes under consideration. As this set has to be the same for all genes, the efficient planning of such experiments is very challenging. We address this problem by determining efficient designs for the simultaneous inference of a large number of concentration–response models. For that purpose, we both construct a D-optimality criterion for simultaneous inference and a K-means procedure which clusters the support points of the locally D-optimal designs of the individual models.
Results:
We show that a planning of experiments that addresses the simultaneous inference of a large number of concentration–response relationships yields a substantially more accurate statistical analysis. In particular, we compare the performance of the constructed designs to the ones of other commonly used designs in terms of D-efficiencies and in terms of the quality of the resulting model fits using a real data example dealing with valproic acid. For the quality comparison we perform an extensive simulation study.
Conclusions:
The design maximizing the D-optimality criterion for simultaneous inference improves the inference of the different concentration–response relationships substantially. The design based on the K-means procedure also performs well, whereas a log-equidistant design, which was also included in the analysis, performs poorly in terms of the quality of the simultaneous inference. Based on our findings, the D-optimal design for simultaneous inference should be used for upcoming analyses dealing with high-dimensional gene expression data.
2023-10-19T00:00:00Z
AAM: a dataset of Artificial Audio Multitracks for diverse music information retrieval tasks
Ostermann, Fabian
Vatolkin, Igor
Ebeling, Martin
http://hdl.handle.net/2003/42402
2024-03-22T23:12:57Z
2023-03-23T00:00:00Z
Title: AAM: a dataset of Artificial Audio Multitracks for diverse music information retrieval tasks
Authors: Ostermann, Fabian; Vatolkin, Igor; Ebeling, Martin
Abstract: We present a new dataset of 3000 artificial music tracks with rich annotations based on real instrument samples and generated by algorithmic composition with respect to music theory. Our collection provides ground truth onset information and has several advantages compared to many available datasets. It can be used to compare and optimize algorithms for various music information retrieval tasks like music segmentation, instrument recognition, source separation, onset detection, key and chord recognition, or tempo estimation. As the audio is perfectly aligned to original MIDIs, all annotations (onsets, pitches, instruments, keys, tempos, chords, beats, and segment boundaries) are absolutely precise. Because of that, specific scenarios can be addressed, for instance, detection of segment boundaries with instrument and key change only, or onset detection only in tracks with drums and slow tempo. This allows for the exhaustive evaluation and identification of individual weak points of algorithms. In contrast to datasets with commercial music, all audio tracks are freely available, allowing for extraction of own audio features. All music pieces are stored as single instrument audio tracks and a mix track, so that different augmentations and DSP effects can be applied to extend training sets and create individual mixes, e.g., for deep neural networks. In three case studies, we show how different algorithms and neural network models can be analyzed and compared for music segmentation, instrument recognition, and onset detection. In future, the dataset can be easily extended under consideration of specific demands to the composition process.
2023-03-23T00:00:00Z
Synthese, Charakterisierung und photophysikalische Untersuchungen von Kupfer(I)-Emittern im Zusammenhang mit Exzitonenkopplung und die Synthese heteronuklearer Systeme auf Basis von Kupfer(I)- und Gruppe(IV)-Metallen
Janiak, Lars Immanuel
http://hdl.handle.net/2003/42401
2024-03-22T23:12:34Z
2023-01-01T00:00:00Z
Title: Synthese, Charakterisierung und photophysikalische Untersuchungen von Kupfer(I)-Emittern im Zusammenhang mit Exzitonenkopplung und die Synthese heteronuklearer Systeme auf Basis von Kupfer(I)- und Gruppe(IV)-Metallen
Authors: Janiak, Lars Immanuel
Abstract: Das Design molekularer Emitter auf Basis von häufig vorkommenden Metallen, wie z.B. Kupfer(I), ist eine Herausforderung der gegenwärtigen Forschung und wird in dieser Arbeit thematisiert. Lumineszente Materialien in z.B. OLEDs enthalten häufig teure Edelmetalle mit örtlich begrenztem Vorkommen, wodurch aktuell eine geopolitische Abhängigkeit entsteht und in Zukunft der Bedarf für die Massenprodukte nicht abgedeckt werden kann. Ein weiteres Problem von OLEDs ist die Stabilität und Lichtsättigung, die aufgrund niedriger strahlender Ratenkonstanten die Lebenszeit des Bauteils begrenzen. Organometallkomplexe bieten den Vorteil einer hohen Spin-Bahn-Kopplung (SOC), wodurch Singulett- mit Triplettzuständen koppeln und eine effiziente Phosphoreszenz erreichen. Nachteilig ist jedoch, dass Phosphoreszenz sich durch verhältnismäßig lange Lebenszeiten auszeichnet. Diese Problematik kann mit dem alternativen und vielversprechenden Emissionsmechanismus der thermisch aktivierten verzögerten Fluoreszenz (TADF) umgangen werden, der Zugang zu deutlich kürzeren Lebenszeiten und hohen strahlenden Ratenkonstanten 𝑘𝑟 ermöglicht. Einen weiteren Lösungs-ansatz bietet die Verwendung des physikalischen Phänomens der intramolekularen Exzitonenkopplung, welches in dieser Arbeit anhand ausgewählter Kupfer(I)-Komplexe untersucht wurde. So wurde der Einfluss eines weiteren Metallzentrums in Organometallverbindungen analysiert, um das Übergangsdipolmoment μ zu erhöhen, das ein direktes Maß für die Erlaubtheit eines Übergangs darstellt. Hierzu wurden Pyrimidin- und Benzimidazol-basierte Brückenliganden verwendet, die durch zwei bidentate Koordinationsstellen eine hohe räumliche Nähe beider Metallzentren ermöglichen. Im Rahmen dieser Arbeit wurde zudem mit S-BINAP, POP und Xantphos der Einfluss verschiedener bidentater Phosphanliganden, aber auch des N-heterocyclischen 2,4-Di-isopropylphenyl-substituierten ARDUENGO-Carbens, auf die photophysikalischen Eigenschaften im Festkörper untersucht. Insbesondere bei bpm-basierten Kupfer(I)-Komplexen wurden kürzere Lebenszeiten mit gleichbleibend niedrigen Quantenaus-beuten detektiert, während für die strahlende Ratenkonstante 𝑘𝑟 bei pmbim- und bzim-basierten Systemen keine Zunahme zu beobachten war. Des Weiteren wurden einige phosphoreszierende Blaulichtemitter auf bzim-Basis mit Quantenausbeuten von bis zu 𝛷 = 0.61 charakterisiert. Zudem wurden bpm-basierte bimetallische Komplexe mit ungewöhnlichen reversiblen Reduktionspotentialen isoliert, welche sich als potenzielle Ein-Elektronen-Transferreagenzien ausweisen. Zusätzlich wurden photokatalytische Umwandlungen mittels DEXTER-Energietransfer von bzim-basierten Kupfer(I)-Komplexen erfolgreich durchgeführt.
Eine weitere Herausforderung stellt die Bildung des anti-MARKOVNIKOV-Produkts in der Hydroaminierung da. Aufgrund verschiedener thermodynamischer und kinetischer Barrieren ist das anti-MARKOVNIKOV-Produkt in der Hydroaminierung auf direktem Weg schlecht zugänglich. Gruppe(IV)-Metalle sind in der Lage diese Reaktion zu katalysieren. Aufgrund ihrer geringen Toleranz gegenüber funktionaler Gruppen und geringer Ausbeuten des anti-MAR-KOVNIKOV-Produkts jedoch limitiert. Im zweiten Teil der Arbeit wurden daher heteronukleare Systeme auf Basis von Kupfer(I)- und Gruppe(IV)-Metallen untersucht, welche in Zukunft als bimetallische Photokatalysatoren für die Hydroaminierung eingesetzt werden sollen. Priorität lag hierbei auf der Synthese und Isolation von derartigen Metallkomplexen. Während sich Gruppe(IV)-Amidokomplexe nicht für die Umsetzung mit Kupfer(I)-Komplexen eigneten, konnte durch den Wechsel auf Gruppe(IV)-Halogenidkomplexe eine erste heteronukleare Spezies auf Basis von Cu(I) und Zr(IV) nachgewiesen werden. Zudem konnten weitere neuartige Gruppe(IV)-pmbim-Verbindungen und ein trimetallischer Komplex auf Basis von einem Ti(IV)-Atom und zwei Cu(I)-Atomen isoliert werden. Letzterer zeichnet sich durch eine intensive Absorption über das gesamte sichtbare Spektrum aus.
2023-01-01T00:00:00Z
Ultrafast coherent lattice dynamics coupled to spins in the van der Waals antiferromagnet FePS3
Mertens, Fabian
http://hdl.handle.net/2003/42400
2024-03-22T23:12:19Z
2023-01-01T00:00:00Z
Title: Ultrafast coherent lattice dynamics coupled to spins in the van der Waals antiferromagnet FePS3
Authors: Mertens, Fabian
Abstract: 2D materials, like the antiferromagnetic van der Waals semiconductors FePS3 studied
in this work, open up new possibilities for technological applications due to the
unique interaction of their magnetization with electronic, optical, and mechanical
properties. Furthermore, they provide the potential to study magnetism and
magnetization dynamics in reduced dimensions. Up do date, the coherent control of
the magnetization of these materials has barely been studied. Our research addresses
this gap by using ultrashort light pulses. In this context, time-resolved studies can
give an insight into the evolution of the light-induced dynamics, which essentially
require a dedicated experimental setup.
In this thesis, we present a comprehensive study on the development and application
of a table-top laser setup designed for magneto-optical pump-probe experiments and
adaptable for the investigation of microscopic samples. The system employs two
optical parametric amplifiers, with a tunable photon-energy range of 0.5 eV - 3.5 eV
for both the pump and the probe beam. Remarkable is the high pump amplitude
modulation rate at 50 % of the laser repetition rate, realized via the integration of
an electro-optical modulator, blocking every second pump pulse. Combined with a
high-frequency digitizer, performing single pulse detection, our system can achieve a
high sensitivity, down to 50 µdeg of the probe polarization rotation. The setup can
apply magnetic fields of up to ±9 T, and voltages in the kV regime while providing
a temperature control between 4 K-420 K.
The functionality of the setup’s systems is demonstrated by performing static Kerrrotation
and ultrafast demagnetization measurements in a cobalt single crystal as a
function of the most important experimental parameters.
The major part of this thesis is dedicated to our studies on a coherent optical
lattice mode of terahertz frequency triggered by femtosecond laser pulses in the
antiferromagnetic van der Waals semiconductor FePS3 . This specific 3.2 THz phonon
mode shows a close relation to the antiferromagnetic order, as it vanishes above the
Néel temperature and hybridizes with a magnon mode in the presence of a magnetic
field. We investigate it as a function of sample temperature, probe polarization,
excitation photon energy and externally applied magnetic fields. The resonant
excitation of a crystal-field split electronic ..-.. transition efÏciently pumps the
displacive excitation process of the mode, while the magnetic linear dichroism is
identified as the magneto-optical effect, which reflects the phonon mode in the probe
rotation. By applying magnetic fields of up to 9 T we can generate and observe
the coherent hybridized phonon-magnon mode, thus exploiting the hybridization to
excite coherent spin-dynamics. Furthermore, we investigate the coherent phonons
in the bulk form of FePS3 and in an exfoliated flake with a thickness of 380 nm.
2023-01-01T00:00:00Z
Ein strategischer erdbebenresilienter Wiederaufbau unter Verwendung von GIS basiertes weighted Overlay.
Derin, Enes
http://hdl.handle.net/2003/42399
2024-03-21T23:13:58Z
2023-10-16T00:00:00Z
Title: Ein strategischer erdbebenresilienter Wiederaufbau unter Verwendung von GIS basiertes weighted Overlay.
Authors: Derin, Enes
Abstract: Earthquakes are a natural phenomenon that can cause severe destruction within urban areas. In
particular, cascading effects resulting from the earthquake, such as liquefaction, fires, landslides
and tsunamis, can increase the resulting damage. In addition, current experience shows that strict
building regulations, such as specifications on statics and the design of the building structure, and
strategic planning by the city, are the best way so far to minimise damage from earthquakes.
On 06.February 2023, Turkey was hit by two strong earthquakes. The earthquakes caused enormous
destruction, killing many people. In particular, the city of Antakya, within the southeastern province
of Hatay, was hit very hard by the two earthquakes. The magnitude of the earthquakes within
the hit provinces varies according to the local topographical, geomorphological and hydrological
conditions.
As a basis for this work, the local conditions in the study area of Antakya are to be investigated and
evaluated so that the areas with high or very high risk can be identified. The identification of the risk
areas will result in a map that can be used as a basis for establishing new planning measures.
These planning measures result from the literature research, whereby three best practice examples
were taken into focus. The three case studies from Haiti, Chile and Japan have designed different
measures for earthquake-resilient urban planning. In addition, supplementary measures are to be
taken from other concepts and scientific work in order to be able to identify further suitable measures.
The identified measures are to be integrated into the basic map. The result should be a strategic
master plan, which should combine different measures at the urban level.
2023-10-16T00:00:00Z
Analyzing the associations between motivation and academic performance via the mediator variables of specific mathematic cognitive learning strategies in different subject domains of higher education
Wild, Steffen
Neef, Christoph
http://hdl.handle.net/2003/42398
2024-03-20T23:14:43Z
2023-05-12T00:00:00Z
Title: Analyzing the associations between motivation and academic performance via the mediator variables of specific mathematic cognitive learning strategies in different subject domains of higher education
Authors: Wild, Steffen; Neef, Christoph
Abstract: Background:
There are different teaching methods and learning content in the academic field of mathematics between school and university. Many students fail in their studies when the proportion of mathematics is high. Additionally, dropout rates, due to mathematical performance, are high. However, there are different strategies used to improve mathematical skills. Based on the process model of self-regulated learning, an analysis of the association between motivational aspects in the pre-action phase as well as seven special cognitive learning strategies for mathematics in the action phase was conducted. The variables were compared with student performance. The study drew on data from 548 retrospective interviews of cooperative students, using a cross-sectional research design.
Results:
The analysis via structural equation modeling shows a direct association between motivational aspects, such as academic self-concept and curiosity, and the seven learning strategies in mathematics. Furthermore, there is a direct effect of academic self-concept on performance. However, the learning strategy of practicing was the only variable with associations to performance. Additionally, the indirect effect of curiosity on performance via practicing is analyzed.
Conclusion:
It can be seen, that curiosity on its own is not enough to ensure a good level of performance in mathematics. The findings suggest student learning strategies focusing on harnessing their curiosity and on practicing. A high academic self-concept is also relevant to the performance level achieved. Lecturers should create a learning environment to support such student behavior.
2023-05-12T00:00:00Z
The gender dimensions of travel time use in Germany
Chidambaram, Bhuvanachithra
Scheiner, Joachim
http://hdl.handle.net/2003/42397
2024-03-20T23:13:50Z
2023-01-26T00:00:00Z
Title: The gender dimensions of travel time use in Germany
Authors: Chidambaram, Bhuvanachithra; Scheiner, Joachim
Abstract: Time use during travel has been the subject of considerable research in recent years thanks to its crucial role in determining the utility of travel time. While most of these studies have documented the effects of demographics and trip characteristics on travel time use, the effect of gender is still ambiguous. To understand the role of gender in travel time use, we explore the effect of gender interaction with non-travel time use behavior (daily habits, multitasking and preferences), joint travel (travel companion), and economic situation (income and working hours) on various time use activities (reading, ICT use and talking) during travel. Moreover, we address the mixed and scant evidence from prior studies regarding the effect of sociodemographic, residential and trip characteristics on travel time use. The study used the cross-sectional German Time Use Survey 2012/13 data and employed multi-level binary logistic regression for analysis. The results indicate four important findings: (1) women's socializing during travel is principally influenced by primary time spent on interaction with children and ICT usage, while men’s socializing during travel is positively influenced by traveling with their partners and socializing habits; (2) both women’s and men’s solitary activities during travel (e.g. reading/ICT use) are influenced by their economic situation (e.g. income, working hours) and daily non-travel time use habits (reading habits/ICT use habits); (3) individuals’ solitary time use during travel is positively influenced by other potential determinants such as living in semi-urban areas/East Germany, driving or traveling by public transport; and (4) socializing during travel is positively influenced by living with partners, having young children, evening/night/weekend trips, maintenance/leisure trips, traveling by public transport and walking.
2023-01-26T00:00:00Z
Transfer-free graphene passivation of sub 100 nm thin Pt and Pt–Cu electrodes for memristive devices
Tappertzhofen, Stefan
Braeuninger-Weimer, P.
Gumprich, Alexander
Chirca, I.
Potočnik, T.
Alexander-Webber, J. A.
Hofmann, S.
http://hdl.handle.net/2003/42396
2024-03-20T23:13:43Z
2023-02-24T00:00:00Z
Title: Transfer-free graphene passivation of sub 100 nm thin Pt and Pt–Cu electrodes for memristive devices
Authors: Tappertzhofen, Stefan; Braeuninger-Weimer, P.; Gumprich, Alexander; Chirca, I.; Potočnik, T.; Alexander-Webber, J. A.; Hofmann, S.
Abstract: Memristive switches are among the most promising building blocks for future neuromorphic computing. These devices are based on a complex interplay of redox reactions on the nanoscale. Nanoionic phenomena enable non-linear and low-power resistance transition in ultra-short programming times. However, when not controlled, the same electrochemical reactions can result in device degradation and instability over time. Two-dimensional barriers have been suggested to precisely manipulate the nanoionic processes. But fabrication-friendly integration of these materials in memristive devices is challenging.Here we report on a novel process for graphene passivation of thin platinum and platinum/copper electrodes. We also studied the level of defects of graphene after deposition of selected oxides that are relevant for memristive switching.
2023-02-24T00:00:00Z
Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 8/2024
http://hdl.handle.net/2003/42395
2024-03-18T23:16:26Z
2024-03-19T00:00:00Z
Title: Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 8/2024
2024-03-19T00:00:00Z
International trade in the European Union
Kaliske, Maren
http://hdl.handle.net/2003/42394
2024-03-21T14:55:53Z
2024-01-01T00:00:00Z
Title: International trade in the European Union
Authors: Kaliske, Maren
Abstract: The European Union stands as a remarkable example of regional economic and political integration,
fostering trade relationships among its member states through committing to joint laws
and policies. Despite all the EU’s successes, it faces constant challenges. This thesis combines
three chapters and reflects upon various dimensions of international trade within the EU. By
applying theory consistent structural gravity estimations this thesis sheds light on the influence
of converging and diverging political preferences, environmental policies, and infrastructure investments
on trade flows at both country and regional levels. The first chapter of this thesis
examines the interdependence of the political and economic integration process by raising the
question of how changes in the similarity in political preferences affect intra-EU trade integration.
The findings of this chapter suggest that member states converging to the EU’s political
mainstream experience a reduction in domestic trade and an increase in trade with other EU
member states. Building on the results of chapter one, the second chapter delves into the question
of whether differences in environmental policy preferences within the EU have given rise
to “pollution havens”. This chapter provides evidence for binding multilateral environmental
agreements successfully eliminating comparative advantages for emission-intensive industries.
The third chapter of this thesis shifts the focus of revealed policy preferences to the effect of
cohesion policy in the form of infrastructure investment. The results of this chapter reveal that
improved infrastructure helps facilitate trade and promotes economic linkages of NUTS-2 regions
thereby reducing persistent trade costs in the EU Single Market. The three chapters of this
thesis thereby deepen the understanding of factors determining and promoting trade integration
in the EU Single Market.
2024-01-01T00:00:00Z
Verfahren zur adaptiven Identifikation von Mittelspannungsteilnetzen durch den Einsatz des maschinellen Lernens
Puhe, Frederik
http://hdl.handle.net/2003/42393
2024-03-15T23:14:07Z
2023-01-01T00:00:00Z
Title: Verfahren zur adaptiven Identifikation von Mittelspannungsteilnetzen durch den Einsatz des maschinellen Lernens
Authors: Puhe, Frederik
Abstract: Im Rahmen dieser Dissertation wird ein Verfahren zur Identifikation von Teilnetzen in der Mittelspannungsebene entwickelt. Die Besonderheit liegt vor allem in der adaptiven Implementierung und Erweiterung in Ortsnetzstationen durch den Einsatz von Virtualisierungslösungen und Algorithmen des maschinellen Lernens.
Der Begriff Teilnetz beschreibt eine physikalisch vom Verbundsystem isolierte und von der Größe unbestimmte Versorgungsstruktur, welche aufgrund auftretender Störungen unbeabsichtigt weiter betrieben wird. Die Modellierung der Testumgebung und die darauf zugrunde liegende Bewertung der Funktionsweise des im Rahmen dieser Arbeit entwickelten Teilnetzidentifikationsverfahrens erfolgt anhand dynamischer Netzsimulationen in MATLAB Simulink© sowie durch eine Hardware-in-the-Loop Simulation unter Verwendung eines Echtzeitsimulators.; In this thesis, a subgrid identification procedure for medium voltage grids is developed. The main feature is the adaptive implementation and scaling in local substations by using virtualization solutions and machine learning algorithms. Subgrids describe supply structures that are physically isolated from the interconnected grid, unspecified in their size and continue to operate unintentionally due to disturbances. The modeling of the test environment and the evaluation of the functionality of the subgrid identification procedure is carried out by dynamic simulations in MATLAB Simulink© as well as by a Hardware-in-the-Loop simulation using a real-time simulator.
2023-01-01T00:00:00Z
Rettungsgassenbildung mit autonomen Fahrzeugen auf Hardware mit beschränkten Ressourcen
Kuzmic, Jurij
http://hdl.handle.net/2003/42392
2024-03-15T23:13:10Z
2024-01-01T00:00:00Z
Title: Rettungsgassenbildung mit autonomen Fahrzeugen auf Hardware mit beschränkten Ressourcen
Authors: Kuzmic, Jurij
Abstract: Der Schwerpunkt dieser Dissertation liegt auf der Entwicklung der Algorithmen und Software für stromsparende IoT-Geräte bezogen auf die Problematik der Rettungsgassenbildung auf Autobahnen mit autonomen Fahrzeugen. Auf den Autobahnen kommt es immer wieder zu unvorhersehbaren schwerwiegenden Unfällen. Dabei vergessen die Fahrer der Fahrzeuge teilweise eine Rettungsgasse für die Polizei- und Rettungsfahrzeuge zu bilden und behindern diese beim Erreichen des Unfallorts. Dabei ist für die Unfallbeteiligten jede Minute sehr wichtig. Die autonomen Fahrzeuge hingegen könnten die entwickelten Algorithmen zur Bildung der Rettungsgasse bei einem bestimmten Ereignis ausführen. Die Behebung dieser Problematik ist somit durch die autonomen Fahrzeuge möglich. Dementsprechend ist die Motivation dieser Forschungsarbeit dem Problem bei der Bildung der Rettungsgasse auf Autobahnen für die Polizei- und Rettungsfahrzeuge bei einem Unfall mit autonomen Fahrzeugen entgegenzuwirken. Dazu werden zwei Algorithmen erforscht und anschließend getestet. Die Evaluation der Algorithmen ist durch den in dieser Forschungsarbeit entwickelten Simulator möglich. Anschließend werden diese Algorithmen in der echten Umgebung und nicht nur in der Simulation überprüft. Um dem realen Problem entgegenzuwirken, werden echte autonome Modellfahrzeuge entwickelt und auf einer Teststrecke getestet. Außerdem ist die Motivation das Budget so gering wie möglich zu halten und dabei der Umwelt zur Liebe Strom und Geld zu sparen. Deswegen liegt der Fokus auf der Entwicklung der Software für stromsparende IoT-Geräte. Dabei entstehen die folgenden Fragestellungen: Welche der entwickelten Algorithmen und Methoden können überhaupt auf der stromsparenden IoT-Hardware ausgeführt werden? Welche Laufzeiten können auf diesen IoT-Geräten erreicht werden? Können ebenfalls Echtzeitanwendungen auf der verwendeten IoT-Hardware implementiert werden? Die aufgekommenen Fragestellungen können durch die verschiedenen Experimente dieser Forschungsarbeit beantwortet werden. Die Thematik der beschränkten Ressourcen ist nicht nur bei den Modellfahrzeugen interessant. Beschränkte Ressourcen findet man heutzutage ebenfalls in Drohnen, smarten Überwachungskameras, Wildkameras und weiteren IoT-Geräten.
2024-01-01T00:00:00Z
Memory-based deep reinforcement learning in endless imperfect information games
Pleines, Marco
http://hdl.handle.net/2003/42391
2024-03-15T23:13:13Z
2023-01-01T00:00:00Z
Title: Memory-based deep reinforcement learning in endless imperfect information games
Authors: Pleines, Marco
Abstract: Memory capabilities in Deep Reinforcement Learning (DRL) agents have become increasingly crucial, especially in tasks characterized by partial observability or imperfect information.
However, the field faces two significant challenges: the absence of a universally accepted benchmark and limited access to open-source baseline implementations.
We present "Memory Gym", a novel benchmark suite encompassing both finite and endless versions of the Mortar Mayhem, Mystery Path, and Searing Spotlights environments.
The finite tasks emphasize strong dependencies on memory and memory interactions, while the remarkable endless tasks, inspired by the game "I packed my bag", act as an automatic curriculum, progressively challenging an agent's retention and recall capabilities.
To complement this benchmark, we provide two comprehensible and open-source baselines anchored on the widely-adopted Proximal Policy Optimization algorithm.
The first employs a recurrent mechanism through a Gated Recurrent Unit (GRU) cell, while the second adopts an attention-based approach using Transformer-XL (TrXL) for episodic memory with a sliding window.
Given the dearth of readily available transformer-based DRL implementations, our TrXL baseline offers significant value.
Our results reveal an intriguing performance dynamic: TrXL is often superior in finite tasks, but in the endless environments, GRU unexpectedly marks a comeback.
This discrepancy prompts further investigation into TrXL's potential limitations, including whether its initial query misses temporal cues, the impact of stale hidden states, and the intricacies of positional encoding.
2023-01-01T00:00:00Z
Characterisation of silicon detectors using the two photon absorption – transient current technique
Pape, Sebastian
http://hdl.handle.net/2003/42390
2024-03-15T23:12:14Z
2023-01-01T00:00:00Z
Title: Characterisation of silicon detectors using the two photon absorption – transient current technique
Authors: Pape, Sebastian
Abstract: Modern high energy physics experiments have increasing demands on particle detectors in
terms of their spatial and temporal resolution, as well as their ability to withstand higher
radiation levels. To meet these demands, increasingly complex detectors with ever smaller
device segmentations are being developed that require precise device characterisation.
This work is dedicated to a newly developed characterisation technique: the two photon
absorption - transient current technique (TPA-TCT); a method to characterise particle
detectors with micrometer-scale three-dimensional spatial resolution. Femtosecond laser
light with a wavelength in the quadratic absorption regime is focused to generate excess
charge by two photon absorption in a volume of about 75 µm3 around the focal point. The
drift of the excess charge carriers is studied to obtain information about the device under
test. In this work, silicon detectors are used to explore and further develop the TPA-TCT.
The technique is applied to pad detectors in order to study the technique and to strip and
monolithic detectors to demonstrate the potential of TPA-TCT for the characterisation
of state-of-the-art detector technologies. The applicability of the TPA-TCT in neutron,
proton, and gamma irradiated devices is shown and radiation damage related effects on
the technique are systematically studied. The reduction of charge multiplication in a low
gain avalanche detector for increasing excess charge densities is observed and the role
of diffusion to partially recover the gain is investigated. New techniques to investigate
the electric field in complex segmented devices are developed and applied to strip and
monolithic detectors. This work paves the way for the TPA-TCT as a tool to characterise
detectors with three-dimensional micrometer-scale spatial resolution.; Heutige und zukünftige Experimente der Hochenergiephysik stellen immer höhere Anforde-
rungen an Teilchendetektoren in Bezug auf ihre räumliche und zeitliche Auflösung sowie
ihre Fähigkeit, steigenden Strahlungswerten standzuhalten. Um diese Anforderungen zu
erfüllen, werden immer komplexere Detektoren mit immer kleineren Segmentierungen ent-
wickelt, die eine präzise Charakterisierung erfordern. Diese Arbeit widmet sich einer neuen
Charakterisierungstechnik: der Two Photon Absorption - Transient Current Technique
(TPA-TCT); einer Methode zur Charakterisierung von Teilchendetektoren mit dreidimensio-
naler Auflösung im Mikrometerbereich. Femtosekunden-Laserlicht mit einer Wellenlänge im
quadratischen Absorptionsbereich wird fokussiert, um durch Zwei-Photonen-Absorption in
einem Volumen von etwa 75 µm3 um den Brennpunkt herum Überschussladung zu erzeugen.
Die Bewegung der Ladungsträger wird untersucht, um Informationen über den Detektor
zu erhalten. Im Rahmen dieser Arbeit werden Detektoren aus Silizium verwendet, um die
TPA-TCT zu untersuchen und weiterzuentwickeln. Pad-Detektoren werden untersucht, um
grundlegende Studien bezüglich der TPA-TCT durchzuführen. Das Potenzial der TPA-TCT
für die Charakterisierung moderner Detektortechnologien wird anhand von Streifen- und
monolithische Detektoren demonstriert. Die Anwendbarkeit der TPA-TCT in Neutronen,
Protonen und Gamma bestrahlten Detektoren wird gezeigt, und die Auswirkungen von
Strahlenschäden auf die Technik werden systematisch untersucht. Die Verringerung der
Ladungsvervielfachung in einem Low Gain Avalanche Detector bei zunehmender Ladungs-
trägerdichte wird beobachtet und die Rolle der Ladungsträgerdiffusion zur teilweisen
Wiederherstellung der Verstärkung wird untersucht. Neue Techniken zur Untersuchung
des elektrischen Feldes in komplexen, segmentierten Detektoren werden entwickelt und auf
Streifen- und monolithische Detektoren angewandt. Diese Arbeit ebnet den Weg für die
TPA-TCT als Methode für die Charakterisierung von Detektoren mit dreidimensionaler
räumlicher Auflösung im Mikrometerbereich.
2023-01-01T00:00:00Z
Statistical inference for intensity-based load sharing models with damage accumulation
Jakubzik, Mirko Alexander
http://hdl.handle.net/2003/42389
2024-03-26T13:46:52Z
2023-01-01T00:00:00Z
Title: Statistical inference for intensity-based load sharing models with damage accumulation
Authors: Jakubzik, Mirko Alexander
Abstract: Consider a system in which a load exerted on it is equally shared between its components. Whenever one component fails, the total load is redistributed across the surviving components. This in turn increases the individual load applied to each of these components and therefore their risk of failure. Such a system is called a load sharing system.
In a load sharing system, the failure rate of a surviving component grows with the number of failed components. However, the risk of failure is likely to also depend on how long the surviving components were exposed to the shared load. This accumulation of damage within the system causes a continuous increase in the failure rate between consecutive component failures.
This thesis deals with the statistical inference for load sharing systems with damage accumulation that can be modelled in terms of its component failure rate. We identify the component failure rate as the stochastic intensity of a counting process, for which a parametric model can be specified - an intensity-based load sharing model with damage accumulation.
The first method of inference is the minimum distance estimator introduced by Kopperschmidt and Stute. They claim the strong consistency and asymptotic normality of this estimator, but we demonstrate that their proof of the asymptotic distribution is flawed. Our first important contribution is a corrected proof under slightly adjusted requirements.
The second method of inference is based on the K-sign depth test, a powerful and robust generalization of the classical sign test that was up to now mostly used with the residuals of a linear model. We present a procedure to obtain a "residual" counterpart in an intensity-based model via the hazard transformation of a point process. Moreover, we derive conditions on the model under which the 3-sign depth test is consistent.
The thesis closes by comparing these two methods with the established likelihood approach. To this end, we verify the applicability of the competing methods to the Basquin load sharing model with multiplicative damage accumulation recently proposed by Müller and Meyer. In a final simulation study, we assess the robustness of the methods in the presence of contaminated data. This study confirms that, in contrast to the other two approaches, the 3-sign depth test offers both a powerful and robust tool of statistical inference for intensity-based load sharing models with damage accumulation.
2023-01-01T00:00:00Z
Corporate disclosure and investor sentiment
Beer, Christian
http://hdl.handle.net/2003/42388
2024-03-15T23:14:51Z
2023-01-01T00:00:00Z
Title: Corporate disclosure and investor sentiment
Authors: Beer, Christian
Abstract: Investor decision-making relies on accurate, timely information, but market efficiency theories and information asymmetry challenge the ability to outperform the market. Disclosure practices, including the emerging importance of ESG information, play a key role in shaping investor sentiment and market dynamics. Digital platforms, especially social media, have transformed how information is disseminated, influencing corporate disclosure practices and investor reactions. Behavioral finance highlights how psychological factors can lead to deviations from fundamental valuations. The COVID-19 pandemic underscored the impact of external shocks on investor sentiment, with government interventions playing a critical role in market responses. Auditing, adapting to include non-financial information like ESG, remains essential in reducing information asymmetry, with modern data-analytic tools like Process Mining offering potential to enhance audit efficiency. This dissertation explores the interplay between financial reporting, news dissemination, auditing practices, and their collective impact on the capital market, highlighting the importance of active corporate communication, government response to crises, and the evolving role of auditing in maintaining market trust.
2023-01-01T00:00:00Z
Design principles for data quality tools
Altendeitering, Marcel
http://hdl.handle.net/2003/42387
2024-03-14T23:13:03Z
2023-01-01T00:00:00Z
Title: Design principles for data quality tools
Authors: Altendeitering, Marcel
Abstract: Data quality is an essential aspect of organizational data management and can facilitate accurate decision-making and building competitive advantages. Nu-merous data quality tools aim to support data quality work by offering automa-tion for different activities, such as data profiling or validation. However, de-spite a long history of tools and research, a lack of data quality remains an issue for many organizations. Data quality tools face changes in the organizational (e.g., evolving data architectures) and technical (e.g., big data) environment. Established tools cannot fully comprehend these changes, and limited prescrip-tive design knowledge on creating adequate tools is available. In this cumula-tive dissertation, we summarize the findings of nine individual studies on the objectives and design of data quality tools. Most importantly, we conducted four case studies on implementing data quality tools in real-world scenarios. In each case, we designed and implemented a separate data quality tool and abstracted the essential design elements. A subsequent cross-case analysis helped us accu-mulate the available design knowledge, resulting in the proposal of 13 general-ized design principles. With the proposal of empirically grounded design knowledge, the dissertation contributes to the managerial and scientific commu-nities. Managers can use our results to create customized data quality tools and assess offerings at the market. Scientifically, we address the lack of prescriptive design knowledge for data quality tools and offer many opportunities to extend our research in multiple directions. The continuous work on data quality tools will help them become more successful in ensuring data fulfills high-quality standards for the benefit of businesses and society.
2023-01-01T00:00:00Z
Development of a tool for Bayesian data analysis and its application in Monte Carlo tuning
La Cagnina, Salvatore
http://hdl.handle.net/2003/42386
2024-03-14T23:12:08Z
2023-01-01T00:00:00Z
Title: Development of a tool for Bayesian data analysis and its application in Monte Carlo tuning
Authors: La Cagnina, Salvatore
Abstract: In this thesis, a novel approach to Monte Carlo event generator tuning, grounded in Bayesian reasoning, is presented. The Bayesian Analysis Toolkit (BAT.jl) is introduced as a modern tool for performing Bayesian inference. A numerical test suite that verifies the validity and performance of the BAT.jl package is developed. The test suite is used to evaluate the performance of the Markov chain Monte Carlo (MCMC) sampling algorithms implemented in BAT.jl, utilizing a selection of test functions and different metrics to quantify the quality of the samples. The results show that the MCMC algorithms are able to sample the posterior distributions of the test functions accurately. Utilizing the BAT.jl toolkit, two hadronization models within the Herwig Monte Carlo event generator (MCEG) are successfully tuned to data from the LEP experiments. Several aspects of the tuning procedure are investigated, such as parameter and observable selection and parametrization quality. Samples generated using the tuned parameters, obtained from the global mode of the posterior, are compared to data through a χ2 test. The resulting p-values for the tuned simulations significantly outperform those from the nominal MCEG samples, indicating a successful tune and an improved description of the data. The posterior is also used to present a method for propagating the parameter uncertainties to the realm of the observables, providing a measure for the tuning uncertainty. Studies on the impact of assigning weights to the observables and the impact of correlations between measurements on the tuning are also presented. These show that weights can alter the tuning results, especially in cases with multiple modes in the posterior. However, their influence on the quality of the tune is minimal in this case. The correlation of measurements has less of an impact on the position of the global mode but substantially affects the associated parameter uncertainties estimates. Finally, a comparison of the two tuned hadronization models is presented, which indicates that the Lund string model describes the data slightly better than the cluster hadronization model for this set of observables.
2023-01-01T00:00:00Z
Lagrangian simulation of fiber orientation dynamics using random walk methods
Ahmadi, Omid
http://hdl.handle.net/2003/42385
2024-03-21T10:14:34Z
2023-01-01T00:00:00Z
Title: Lagrangian simulation of fiber orientation dynamics using random walk methods
Authors: Ahmadi, Omid
Abstract: This thesis focuses on developing a two-way coupled framework for the numerical simulation of fiber suspension flows. The influence of fibers on the flow is accounted for by evaluating a non-Newtonian stress term incorporated into the Navier-Stokes equations. The accuracy of the analysis depends on a second-order tensor field used to approximate the orientation distribution of fibers. In this context, the disperse phase can be treated in the Lagrangian or Eulerian manner. We conduct a comprehensive comparison of these frameworks for one-way coupled scenarios in both two- and three-dimensional homogeneous flows. With a special focus on the Lagrangian approach, the algorithm for solving the two-way coupled fiber suspension flow in a segregated manner is proposed by incorporating the fiber-induced stresses in the finite element formulation of the Navier-Stokes equations.
In non-dilute suspensions, fiber-fiber interactions may cause spontaneous changes in the orientation of fibers. Applying the theory of rotary Brownian motion, the effect can be studied using a rotary diffusion term with a Laplace-Beltrami operator. In this work, we develop random walk methodologies to emulate the action of the diffusion term without evolving or reconstructing the so-called orientation distribution function. After deriving simplified forms of Brownian motion generators for rotated reference frames, several practical approaches to generating random walks on the unit sphere are discussed. Among the proposed methods, this research effort presents the projection of Cartesian random walks, as well as polar random walks on the tangential plane. The standard random walks are then projected onto the unit sphere. Moreover, we propose an alternative based on a tabulated approximation of the cumulative distribution function obtained from the exact solution of the spherical heat equation.
In the last part of this work, the random walk approaches are compared through several numerical studies, including the study of the orientation distribution of fibers in a three-dimensional homogeneous flow. Then, the two-way coupled solver is validated in a simple geometry, followed by performing a few three-dimensional numerical simulations to study the rheological behavior of the fiber suspension flow through an axisymmetric contraction. The effect of fiber-fiber interactions is also incorporated using the random walk methodology.
2023-01-01T00:00:00Z
Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 7/2024
http://hdl.handle.net/2003/42384
2024-03-11T23:16:27Z
2024-03-11T00:00:00Z
Title: Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 7/2024
2024-03-11T00:00:00Z
Query evaluation revised: parallel, distributed, via rewritings
Spinrath, Christopher
http://hdl.handle.net/2003/42383
2024-03-08T23:12:47Z
2024-01-01T00:00:00Z
Title: Query evaluation revised: parallel, distributed, via rewritings
Authors: Spinrath, Christopher
Abstract: This is a thesis on query evaluation in parallel and distributed settings, and structurally simple rewritings.
It consists of three parts.
In the first part, we investigate the efficiency of constant-time parallel evaluation algorithms. That is, the number of required processors or, asymptotically equivalent, the work required to evaluate queries in constant time. It is known that relational algebra queries can be evaluated in constant time. However, work-efficiency has not been a focus, and indeed known evaluation algorithms yield huge (polynomial) work bounds. We establish work-efficient constant-time algorithms for several query classes: (free-connex) acyclic, semi-join algebra, and natural join queries; the latter in the worst-case framework.
The second part is about deciding parallel-correctness of distributed evaluation strategies: Given a query and policies specifying how data is distributed and communicated among multiple servers, does the distributed evaluation yield the same result as the classical evaluation, for every database? Ketsman et al. proved that parallel-correctness for Datalog is undecidable; by reduction from the undecidable containment problem for Datalog. We show that parallel-correctness is already undecidable for monadic and frontier-guarded Datalog queries, for which containment is decidable. However, deciding parallel-correctness for frontier-guarded Datalog and constraint-based communication policies satisfying a certain property is 2ExpTime-complete. Furthermore, we obtain the same bounds for the parallel-boundedness problem, which asks whether the number of required communication rounds is bounded, over all databases.
The third part is about structurally simple rewritings. The (classical) rewriting problem asks whether, for a given query and a set of views, there is a query, called rewriting, over the views that is equivalent to the given query. We study the variant of this problem for (subclasses of) conjunctive queries and views that asks for a structurally simple rewriting. We prove that, if the given query is acyclic, an acyclic rewriting exists if there is any rewriting at all. Analogous statements hold for free-connex acyclic, hierarchical, and q-hierarchical queries. Furthermore, we prove that the problem is NP-hard, even if the given query and the views are acyclic or hierarchical. It becomes tractable if the views are free-connex acyclic or q-hierarchical (and the arity of the database schema is bounded).
2024-01-01T00:00:00Z
Sustainable consumption for effective ecosystem-based adaptation in urban and peri-urban settlements in the lowlands of Nepal
Bista, Samjhana
http://hdl.handle.net/2003/42382
2024-03-07T23:13:52Z
2024-01-01T00:00:00Z
Title: Sustainable consumption for effective ecosystem-based adaptation in urban and peri-urban settlements in the lowlands of Nepal
Authors: Bista, Samjhana
Abstract: The concept of sustainability is not new to Nepal and was accepted as early as the Brundtland Commission published its report in 1987. However, very few studies have been conducted to see the linkage between sustainable consumption and nature conservation, such as ecosystem-based adaptation (EbA), and no research was reported from Nepal. A mixed research method was applied which included primary data collection from household surveys, focus group discussions, key informant interviews and experts’ consultation workshop, as well as secondary data from literature reviews and documents published by the Government of Nepal. The major factors influencing household/individual consumption were people’s lifestyle being more luxury-oriented, busy schedule of household members, availability of modern facilities, peer-pressure, increasing income, laziness, and modernisation. The people in the study area were found less aware on climate change and their impacts. Under conditions such as awareness on climate and health benefits, people were willing to pay the premium price for green food products and urban green parks. The individuals who are engaged in conservation initiatives were found to practise environment-friendly behaviours at the household level such as growing their own vegetables, using bicycles to work, using green parks instead of sophisticated gym centres, among others. The study, therefore, collected evidence to claim that sustainable consumption should be considered as one of the indicators of effective EbA. The findings will be very relevant to the policy makers, academia, private sector and development practitioners. Furthermore, it will pave the path for national as well as international discussions and commitments for climate financing efforts that are evidence-based, locally driven and local solutions-oriented.
2024-01-01T00:00:00Z
Delayed development of basic numerical skills in children with developmental dyscalculia
Lamb, Sarah
Krieger, Florian
Kuhn, Jörg-Tobias
http://hdl.handle.net/2003/42381
2024-03-06T23:14:53Z
2024-01-11T00:00:00Z
Title: Delayed development of basic numerical skills in children with developmental dyscalculia
Authors: Lamb, Sarah; Krieger, Florian; Kuhn, Jörg-Tobias
Abstract: Research suggests that children with developmental dyscalculia (DD) have deficits in basic numerical skills. However, there is conflicting evidence on whether basic numerical skills in children with DD are qualitatively different from those in typically developing children (TD) or whether basic numerical skills development in children with DD is simply delayed. In addition, there are also competing hypotheses about deficits in basic numerical skills, assuming (1) a general deficit in representing numerosities (Approximate Number System, ANS), (2) specific deficits in an object-based attentional system (Object Tracking System, OTS), or (3) deficits in accessing numerosities from symbols (Access Deficit, AD). Hence, the purpose of this study was to investigate whether deficits in basic numerical skills in children with DD are more indicative of a developmental delay or a dyscalculia-specific qualitative deviation and whether these deficits result from (selective) impairment of core cognitive systems involved in numerical processing. To address this, we tested 480 children (68 DD and 412 TD) in the 2nd, 3rd, and 4th grades with different paradigms for basic numerical skills (subitizing, counting, magnitude comparison tasks, number sets, and number line estimation tasks). The results revealed that DD children’s impairments did not indicate qualitatively different basic numerical skills but instead pointed to a specific developmental delay, with the exception of dot enumeration. This result was corroborated when comparing mathematical profiles of DD children in 4th grade and TD children in 2nd grade, suggesting that DD children were developmentally delayed and not qualitatively different. In addition, specific deficits in core markers of numeracy in children with DD supported the ANS deficit rather than the AD and OTS deficit hypothesis.
2024-01-11T00:00:00Z
Tuning the high-pressure phase behaviour of highly compressible zeolitic imidazolate frameworks: from discontinuous to continuous pore closure by linker substitution
Song, Jianbo
Pallach, Roman
Frentzel-Beyme, Louis
Kolodzeiski, Pascal
Kieslich, Gregor
Vervoorts, Pia
Hobday, Claire L.
Henke, Sebastian
http://hdl.handle.net/2003/42380
2024-03-06T23:12:24Z
2022-02-04T00:00:00Z
Title: Tuning the high-pressure phase behaviour of highly compressible zeolitic imidazolate frameworks: from discontinuous to continuous pore closure by linker substitution
Authors: Song, Jianbo; Pallach, Roman; Frentzel-Beyme, Louis; Kolodzeiski, Pascal; Kieslich, Gregor; Vervoorts, Pia; Hobday, Claire L.; Henke, Sebastian
Abstract: The high-pressure behaviour of flexible zeolitic imidazolate frameworks (ZIFs) of the ZIF-62 family with the chemical composition M(im)2−x(bim)x is presented (M2+=Zn2+, Co2+; im−=imidazolate; bim−=benzimidazolate, 0.02≤x≤0.37). High-pressure powder X-ray diffraction shows that the materials contract reversibly from an open pore (op) to a closed pore (cp) phase under a hydrostatic pressure of up to 4000 bar. Sequentially increasing the bim− fraction (x) reinforces the framework, leading to an increased threshold pressure for the op-to-cp phase transition, while the total volume contraction across the transition decreases. Most importantly, the typical discontinuous op-to-cp transition (first order) changes to an unusual continuous transition (second order) for x≥0.35. This allows finetuning of the void volume and the pore size of the material continuously by adjusting the pressure, thus opening new possibilities for MOFs in pressure-switchable devices, membranes, and actuators.
2022-02-04T00:00:00Z
Model selection characteristics when using MCP-Mod for dose–response gene expression data
Duda, Julia C.
Kappenberg, Franziska
Rahnenführer, Jörg
http://hdl.handle.net/2003/42379
2024-03-06T23:13:05Z
2022-02-20T00:00:00Z
Title: Model selection characteristics when using MCP-Mod for dose–response gene expression data
Authors: Duda, Julia C.; Kappenberg, Franziska; Rahnenführer, Jörg
Abstract: We extend the scope of application for MCP-Mod (Multiple Comparison Procedure and Modeling) to in vitro gene expression data and assess its characteristics regarding model selection for concentration gene expression curves. Precisely, we apply MCP-Mod on single genes of a high-dimensional gene expression data set, where human embryonic stem cells were exposed to eight concentration levels of the compound valproic acid (VPA). As candidate models we consider the sigmoid Emax (four-parameter log-logistic), linear, quadratic, Emax, exponential, and beta model. Through simulations we investigate the impact of omitting one or more models from the candidate model set to uncover possibly superfluous models and to evaluate the precision and recall rates of selected models. Each model is selected according to Akaike information criterion (AIC) for a considerable number of genes. For less noisy cases the popular sigmoid Emax model is frequently selected. For more noisy data, often simpler models like the linear model are selected, but mostly without relevant performance advantage compared to the second best model. Also, the commonly used standard Emax model has an unexpected low performance.
2022-02-20T00:00:00Z
Improving adaptive seamless designs through Bayesian optimization
Richter, Jakob
Friede, Tim
Rahnenführer, Jörg
http://hdl.handle.net/2003/42378
2024-03-06T23:13:14Z
2022-02-25T00:00:00Z
Title: Improving adaptive seamless designs through Bayesian optimization
Authors: Richter, Jakob; Friede, Tim; Rahnenführer, Jörg
Abstract: We propose to use Bayesian optimization (BO) to improve the efficiency of the design selection process in clinical trials. BO is a method to optimize expensive black-box functions, by using a regression as a surrogate to guide the search. In clinical trials, planning test procedures and sample sizes is a crucial task. A common goal is to maximize the test power, given a set of treatments, corresponding effect sizes, and a total number of samples. From a wide range of possible designs, we aim to select the best one in a short time to allow quick decisions. The standard approach to simulate the power for each single design can become too time consuming. When the number of possible designs becomes very large, either large computational resources are required or an exhaustive exploration of all possible designs takes too long. Here, we propose to use BO to quickly find a clinical trial design with high power from a large number of candidate designs. We demonstrate the effectiveness of our approach by optimizing the power of adaptive seamless designs for different sets of treatment effect sizes. Comparing BO with an exhaustive evaluation of all candidate designs shows that BO finds competitive designs in a fraction of the time.
2022-02-25T00:00:00Z
John Cook Wilson on the indefinability of knowledge
Longworth, Guy
Wimmer, Simon
http://hdl.handle.net/2003/42376
2024-03-05T23:15:02Z
2022-02-13T00:00:00Z
Title: John Cook Wilson on the indefinability of knowledge
Authors: Longworth, Guy; Wimmer, Simon
Abstract: Can knowledge be defined? We expound an argument of John Cook Wilson's that it cannot. Cook Wilson's argument connects knowing with having the power to inquire. We suggest that if he is right about that connection, then knowledge is, indeed, indefinable.
2022-02-13T00:00:00Z
Covalent allosteric inhibitors of Akt generated using a click fragment approach
Westhuizen, Leandi van der
Weisner, Jörn
Taher, Abu
Landel, Ina
Quambusch, Lena
Lindemann, Marius
Uhlenbrock, Niklas
Müller, Matthias P.
Green, Ivan R.
Pelly, Stephen C.
Rauh, Daniel
Otterlo, Willem A. L. van
http://hdl.handle.net/2003/42375
2024-03-04T23:12:26Z
2022-02-16T00:00:00Z
Title: Covalent allosteric inhibitors of Akt generated using a click fragment approach
Authors: Westhuizen, Leandi van der; Weisner, Jörn; Taher, Abu; Landel, Ina; Quambusch, Lena; Lindemann, Marius; Uhlenbrock, Niklas; Müller, Matthias P.; Green, Ivan R.; Pelly, Stephen C.; Rauh, Daniel; Otterlo, Willem A. L. van
Abstract: Akt is a protein kinase that has been implicated in the progression of cancerous tumours. A number of covalent allosteric Akt inhibitors are known, and based on these scaffolds, a small library of novel potential covalent allosteric imidazopyridine-based inhibitors was designed. The envisaged compounds were synthesised, with click chemistry enabling a modular approach to a number of the target compounds. The binding modes, potencies and antiproliferative activities of these synthesised compounds were explored, thereby furthering the structure activity relationship knowledge of this class of Akt inhibitors. Three novel covalent inhibitors were identified, exhibiting moderate activity against Akt1 and various cancer cell lines, potentially paving the way for future covalent allosteric inhibitors with improved properties.
2022-02-16T00:00:00Z
Synthesis and characterization of cationic hydrogels from thiolated copolymers for independent manipulation of mechanical and chemical properties of cell substrates
Pätzold, Florian
Stamm, Nils
Kamps, Dominic
Specht, Maria
Bolduan, Patrick
Dehmelt, Leif
Weberskirch, Ralf
http://hdl.handle.net/2003/42374
2024-03-04T23:12:36Z
2022-02-20T00:00:00Z
Title: Synthesis and characterization of cationic hydrogels from thiolated copolymers for independent manipulation of mechanical and chemical properties of cell substrates
Authors: Pätzold, Florian; Stamm, Nils; Kamps, Dominic; Specht, Maria; Bolduan, Patrick; Dehmelt, Leif; Weberskirch, Ralf
Abstract: Cells sense both mechanical and chemical properties in their environment and respond to these inputs with altered phenotypes. Precise and selective experimental manipulations of these environmental cues require biocompatible synthetic materials, for which multiple properties can be fine-tuned independently from each other. For example, cells typically show critical thresholds for cell adhesion as a function of substrate parameters such as stiffness and the degree of functionalization. However, the choice of tailor-made, defined materials to produce such cell adhesion substrates is still very limited. Here, a platform of synthetic hydrogels based on well-defined thiolated copolymers is presented. Therefore, four disulfide crosslinked hydrogels of different composition by free radical polymerization are prepared. After cleavage with dithiothreitol, four soluble copolymers P1–P4 with 0–96% cationic monomer content are obtained. P1 and P4 are then combined with PEGDA3500 as a crosslinker, to fabricate 12 hydrogels with variable elasticity, ranging from 8.1 to 26.3 kPa and cationic group concentrations of up to 350 µmol cm−3. Systematic analysis using COS7 cells shows that all of these hydrogels are nontoxic. However, successful cell adhesion requires both a minimal elasticity and a minimal cationic group concentration.
2022-02-20T00:00:00Z
Fast and accurate dose predictions for novel radiotherapy treatments in heterogeneous phantoms using conditional 3D‐UNet generative adversarial networks
Mentzel, Florian
Kröninger, Kevin
Lerch, Michael
Nackenhorst, Olaf
Paino, Jason
Rosenfeld, Anatoly
Saraswati, Ayu
Tsoi, Ah Chung
Weingarten, Jens
Hagenbuchner, Markus
Guatelli, Susanna
http://hdl.handle.net/2003/42373
2024-03-04T23:12:03Z
2022-02-19T00:00:00Z
Title: Fast and accurate dose predictions for novel radiotherapy treatments in heterogeneous phantoms using conditional 3D‐UNet generative adversarial networks
Authors: Mentzel, Florian; Kröninger, Kevin; Lerch, Michael; Nackenhorst, Olaf; Paino, Jason; Rosenfeld, Anatoly; Saraswati, Ayu; Tsoi, Ah Chung; Weingarten, Jens; Hagenbuchner, Markus; Guatelli, Susanna
Abstract: Purpose:
Novel radiotherapy techniques like synchrotron X-ray microbeam radiation therapy (MRT) require fast dose distribution predictions that are accurate at the sub-mm level, especially close to tissue/bone/air interfaces. Monte Carlo (MC) physics simulations are recognized to be one of the most accurate tools to predict the dose delivered in a target tissue but can be very time consuming and therefore prohibitive for treatment planning. Faster dose prediction algorithms are usually developed for clinically deployed treatments only. In this work, we explore a new approach for fast and accurate dose estimations suitable for novel treatments using digital phantoms used in preclinical development and modern machine learning techniques. We develop a generative adversarial network (GAN) model, which is able to emulate the equivalent Geant4 MC simulation with adequate accuracy and use it to predict the radiation dose delivered by a broad synchrotron beam to various phantoms.
Methods:
The energy depositions used for the training of the GAN are obtained using full Geant4 MC simulations of a synchrotron radiation broad beam passing through the phantoms. The energy deposition is scored and predicted in voxel matrices of size 140 × 18 × 18 with a voxel edge length of 1 mm. The GAN model consists of two competing 3D convolutional neural networks, which are conditioned on the photon beam and phantom properties. The generator network has a U-Net structure and is designed to predict the energy depositions of the photon beam inside three phantoms of variable geometry with increasing complexity. The critic network is a relatively simple convolutional network, which is trained to distinguish energy depositions predicted by the generator from the ones obtained with the full MC simulation.
Results:
The energy deposition predictions inside all phantom geometries under investigation show deviations of less than 3% of the maximum deposited energy from the simulation for roughly 99% of the voxels in the field of the beam. Inside the most realistic phantom, a simple pediatric head, the model predictions deviate by less than 1% of the maximal energy deposition from the simulations in more than 96% of the in-field voxels. For all three phantoms, the model generalizes the energy deposition predictions well to phantom geometries, which have not been used for training the model but are interpolations of the training data in multiple dimensions. The computing time for a single prediction is reduced from several hundred hours using Geant4 simulation to less than a second using the GAN model.
Conclusions:
The proposed GAN model predicts dose distributions inside unknown phantoms with only small deviations from the full MC simulation with computations times of less than a second. It demonstrates good interpolation ability to unseen but similar phantom geometries and is flexible enough to be trained on data with different radiation scenarios without the need for optimization of the model parameter. This proof-of-concept encourages to apply and further develop the model for the use in MRT treatment planning, which requires fast and accurate predictions with sub-mm resolutions.
2022-02-19T00:00:00Z
Mechanical in vitro fatigue testing of implant materials and components using advanced characterization techniques
Wegner, Nils
Klein, Martin
Scholz, Ronja
Kotzem, Daniel
Macias Barrientos, Marina
Walther, Frank
http://hdl.handle.net/2003/42372
2024-03-04T23:13:34Z
2021-11-30T00:00:00Z
Title: Mechanical in vitro fatigue testing of implant materials and components using advanced characterization techniques
Authors: Wegner, Nils; Klein, Martin; Scholz, Ronja; Kotzem, Daniel; Macias Barrientos, Marina; Walther, Frank
Abstract: Implants of different material classes have been used for the reconstruction of damaged hard and soft tissue for decades. The aim is to increase and subsequently maintain the patient's quality of life through implantation. In service, most implants are subjected to cyclic loading, which must be taken particularly into consideration, since the fatigue strength is far below the yield and tensile strength. Inaccurate estimation of the structural strength of implants due to the consideration of yield or tensile strength leads to a miscalculation of the implant's fatigue strength and lifetime, and therefore, to its unexpected early fatigue failure. Thus, fatigue failure of an implant based on overestimated performance capability represents acute danger to human health. The determination of fatigue strength by corresponding tests investigating various stress amplitudes is time-consuming and cost-intensive. This study summarizes four investigation series on the fatigue behavior of different implant materials and components, following a standard and an in vitro short-time testing procedure, which evaluates the material reaction in one enhanced test set-up. The test set-up and the applied characterization methods were adapted to the respective application of the implant with the aim to simulate the surrounding of the human body with laboratory in vitro tests only. It could be shown that by using the short-time testing method the number of tests required to determine the fatigue strength can be drastically reduced. In future, therefore it will be possible to exclude unsuitable implant materials or components before further clinical investigations by using a time-efficient and application-oriented testing method.
2021-11-30T00:00:00Z
Theoretical studies on a rotating film reactor for hydrogen production from methane
Becker, Tobias
Agar, David W.
http://hdl.handle.net/2003/42371
2024-03-04T23:13:13Z
2022-03-23T00:00:00Z
Title: Theoretical studies on a rotating film reactor for hydrogen production from methane
Authors: Becker, Tobias; Agar, David W.
Abstract: A film of liquid metal can protect the reactor wall from carbon deposits during methane pyrolysis, discharge carbon from the reactor and prevent blocking. The film can be generated by rotation in a rotating film reactor. Parameters such as liquid volume flow, operating mode or the diameter of the reactor can have an influence on the reaction behavior. A design of experiments was used to investigate the rotating film reactor in more detail and to characterize the influence of various parameters.
2022-03-23T00:00:00Z
Analysis and simplification of kinetic models for methane chlorination and pyrolysis
Keuchel, Florian
Heinlein, Moritz
Hohlmann, Jan
Agar, David W.
http://hdl.handle.net/2003/42370
2024-03-04T23:13:13Z
2022-03-10T00:00:00Z
Title: Analysis and simplification of kinetic models for methane chlorination and pyrolysis
Authors: Keuchel, Florian; Heinlein, Moritz; Hohlmann, Jan; Agar, David W.
Abstract: So far, no complete reaction mechanism has been proposed for high temperature chlorination and pyrolysis of methane. Various mechanisms for the description of this reaction pathway are combined and compared in this paper. This adaptation shows that the gas phase pyrolysis of methane and methyl chloride can be combined with surface reactions via nucleation from the gas phase or on the reactor wall to reproduce the product spectrum. In addition, kinetic parameters for a global simplified one-step mechanism focused on the formation of carbon are fitted to available experimental data.
2022-03-10T00:00:00Z
Reaction optimization of a Suzuki‐Miyaura cross‐coupling using design of experiments
Bobers, Jens
Hahn, Lisa Katharina
Averbeck, Tobias
Brunschweiger, Andreas
Kockmann, Norbert
http://hdl.handle.net/2003/42369
2024-03-01T23:13:14Z
2022-03-11T00:00:00Z
Title: Reaction optimization of a Suzuki‐Miyaura cross‐coupling using design of experiments
Authors: Bobers, Jens; Hahn, Lisa Katharina; Averbeck, Tobias; Brunschweiger, Andreas; Kockmann, Norbert
Abstract: The combination of lab automation and design of experiments for the execution of screening experiments increases productivity and reduces error-prone manual work. A self-developed software tool allows for creating fractional-factorial experimental design (FFED). Application of FFED on the screening of a Suzuki-Miyaura cross-coupling leads to a 93 % reduced design compared to full-factorial design. The resulting regression model qualitatively shows the positive effect of educt concentrations, time, and temperature and reveals the decrease in conversion at high base concentrations.
2022-03-11T00:00:00Z
Simulation of powder flow behavior in an artificial feed frame using an Euler‐Euler model
Zimmermann, Maren
Raffel, Carola
Bartsch, Jens
Thommes, Markus
http://hdl.handle.net/2003/42368
2024-03-01T23:13:18Z
2022-03-01T00:00:00Z
Title: Simulation of powder flow behavior in an artificial feed frame using an Euler‐Euler model
Authors: Zimmermann, Maren; Raffel, Carola; Bartsch, Jens; Thommes, Markus
Abstract: The Eulerian approach is an alternative numerical method to the traditionally used discreet particle techniques for modeling powder flow, avoiding limitations on particle number and diameter. The feasibility of an Euler-Euler simulation in a pharmaceutical application was investigated. In two- and three-dimensional flow simulations, computational fluid dynamics models and parameters were determined and verified based on comparison with experiments. Residence time distributions were calculated to show the applicability of the Eulerian model with two granular phases under the constraint of a continuous setup. Finally, this model was implemented to improve the process understanding of the powder flow in an artificial feed frame of a rotary tablet press.
2022-03-01T00:00:00Z
Klang- und Bewegungsvorstellungen
Herbst, Sebastian
http://hdl.handle.net/2003/42367
2024-02-29T23:15:27Z
2024-01-01T00:00:00Z
Title: Klang- und Bewegungsvorstellungen
Authors: Herbst, Sebastian
Abstract: Jedes Musizieren ist sinnvollerweise von Klang- und Bewegungsvorstellungen geleitet. Entsprechend ist die Bildung dieser Vorstellungen in unterschiedlichen Sinnesmodalitäten und deren assoziative Verbindung zu klangorientierten Musizierbewegungsvorstellungen Ziel des Musizierenlernens. Die Vermittlung von Klang- und Bewegungsvorstellungen gehört damit zu den zentralen Aufgaben für Lehrende im Unterricht.
Zur systematischen Beschreibung des Lehr-Lern-Prozesses wird ein Handlungsphasenmodell aus ideomotorischer Perspektive theoretisch entwickelt, in dem sich die zwei zentralen und im musizierpädagogischen Diskurs besonders beachteten Strategien zur Vermittlung von Klang- und Bewegungsvorstellungen – das Sprechen und Modelllehren – verorten und inhaltlich differenzieren lassen. Davon ausgehend wird im Rahmen eines qualitativen Experiments als Videostudie untersucht, welche Funktionen und Grenzen für verbalsprachliche und musizierende Modellierungen im Lehr-Lern-Prozess ausgemacht werden können und mit welchen Kompensationsstrategien Grenzen überwunden werden. Die Ergebnisse leisten einen Beitrag zur bewussten Gestaltung und Reflexion von stets individuellen und situationsgeprägten Prozessen des Musizierenlehrens und -lernens.
2024-01-01T00:00:00Z
Anpassen und Bewahren
Lehn, Katrin
http://hdl.handle.net/2003/42366
2024-02-29T23:14:12Z
2022-01-01T00:00:00Z
Title: Anpassen und Bewahren
Authors: Lehn, Katrin
Abstract: Die institutionelle Kindertagesbetreuung befindet sich im Wandel. Die Veränderungsprozesse im Feld der Kitas lassen sich zusammenfassen mit den Schlagworten Professionalisierung und Ökonomisierung. Diese nachhaltigen und strukturverändernden Prozesse, die auch Auswirkungen auf die Berufsrollen im Feld haben, schlagen sich in den Einrichtungen vor Ort nieder. So zeigt sich seit einigen Jahren, dass Kitas bildungsspezifische Schwerpunkte entwickeln und Zertifikate erwerben, mit denen die Einrichtungen besondere Förderbereiche hervorheben. Diese Arbeit leistet einen soziologischen und empirischen Beitrag zum Forschungsfeld Wandel und Ökonomisierung des Elementarbereichs, wobei ein Fokus auf Schwerpunktbildung und Zertifizierung mit dem Zertifikat „Anerkannte Kindertageseinrichtung des Kneipp Bund e.V.“ gesetzt wird. Im Zentrum der Forschungsarbeit stehen drei Kitas in einer Stadt in NRW, die seit Jahren kneippzertifiziert sind bzw. sich im Zertifizierungsprozess befinden. Aus soziologischer Perspektive wird untersucht, (1) welches Gesundheitsverständnis und welcher Gesundheitsdiskurs über das Kneipp-Konzept an die Kitas herangetragen wird, (2) wie Kitas Anschluss finden an das Kneipp-Konzept und welche Auswirkungen das Kneipp-Zertifikat auf die Organisation und die pädagogische Praxis hat. Ziel der Forschungsarbeit ist es, das Phänomen der Kneipp-Kita im Kontext des sich wandelnden Betreuungsumfeldes zu verstehen sowie einen empirischen Betrag zu Aushandlungen und Sinnaufladungen der pädagogischen Praxis zu leisten.
2022-01-01T00:00:00Z
Trajektorienfolgeregelung für automatisierte Fahrzeuge
Homann, Andreas
http://hdl.handle.net/2003/42365
2024-02-29T23:13:56Z
2024-01-01T00:00:00Z
Title: Trajektorienfolgeregelung für automatisierte Fahrzeuge
Authors: Homann, Andreas
Abstract: Bei der Betrachtung der Entwicklung von Assistenzsystemen, welche in Serienfahrzeuge integriert werden, zeichnet sich ein Trend hin zur vollständigen Automatisierung der Fahraufgabe ab. Neben der Entwicklung von alternativen Antriebskonzepten ist das automatisierte Fahren eines der wichtigsten Forschungs- und Innovationsthemen der Automobilbranche. Die erforderlichen Funktionen zur Automatisierung der Fahraufgabe lassen sich in verschiedene Teilaufgaben untergliedern. Ein bedeutendes Unterproblem ist die Trajektorienfolgeregelung, welche die eigentliche Fahrzeugführung vornimmt.
Die vorliegende Arbeit befasst sich mit der Entwicklung eines Ansatzes zur Trajektorienfolgeregelung für eine zyklisch neugeplante spline-basierte Referenztrajektorie. Als Grundlage zur vollständigen Beschreibung des Bewegungsverhaltens wird zunächst eine Modellierung der Fahrzeugdynamik und auch der untergeordneten Aktuatorregelkreise vorgenommen. Da die Modellierung des Fahrverhaltens von unterschiedlichen zeitvarianten Parametern abhängt, wird mit einer Sensitivitätsanalyse der Einfluss von Parameteränderungen auf das Übertragungsverhalten untersucht. Es zeigt sich, dass vorallem die Position des Schwerpunktes einen großen Einfluss auf das laterale Fahrverhalten nimmt. Weil die Referenztrajektorie die Eingangsgröße für die Regelung darstellt, besteht eine enge Kopplung zwischen beiden. Daher wird für die spline-basierte Referenztrajektorie untersucht, inwieweit der initiale Fahrzustand berücksichtigt werden kann und darüber hinaus, in welchem Maße eine Anpassung der Trajektorie an eine Gerade, eine Kurve mit konstantem Kurvenradius und an einen Übergangsbogen mit linearer Krümmungsänderung, welche die Grundsegmente im Straßenbau sind, möglich ist. Darüberhinaus wird die spline-basierte Trajektorie mittels des linearen Einspurmodells mit zusätzlichen Informationen erweitert, sodass eine näherungsweise Aufteilung des Kurswinkels in Gier- und Schwimmwinkel möglich ist. Es werden zwei Verfahren zur Trajektorienfolgeregelung entwickelt, die sich in der Prämisse für den Entwurf des Reglersystems unterscheiden. Die erste Methode zielt auf eine geringe Komplexität ab und beruht auf einer Vorsteuerung, welche die Gierratenübertragungsfunktion invertiert. Aufgrund der Besonderheit der Trajektorienfolgeregelung kann das resultierende nichtkausale System gelöst werden. Zusätzlich wird eine Regelung der Gierrate mit einem PI Regler vorgenommen. Der zweite Ansatz wurde unter dem Gesichtspunkt einer möglichst genauen Realisierung konzipiert, selbst in Situationen, in denen das Fahrzeug im nichtlinearen Bereich der Fahrdynamik geführt werden muss. Dieser beruht auf einer modellprädiktiven Regelung, welcher eine ableitungsfreie Optimierung zugrunde liegt. Dabei wird zur Rechenzeitoptimierung festgelegt, dass lediglich für den ersten Prädiktionsschritt die Stellgröße variiert wird, da sich die Trajektorienfolgeregelung auf die frühen Trajektorienpunkte fokussiert. Für die beiden Ansätze wird das Führungsverhalten in verschiedenen Verkehrssituationen evaluiert. Zusätzlich wird das Verhalten bei Störungen durch Seitenwind und einer geneigten Fahrbahn untersucht.
2024-01-01T00:00:00Z
Synthese und Studien photoaktiver Übergangsmetallkomplexe
Koop, Stefan
http://hdl.handle.net/2003/42364
2024-02-29T23:12:31Z
2023-01-01T00:00:00Z
Title: Synthese und Studien photoaktiver Übergangsmetallkomplexe
Authors: Koop, Stefan
Abstract: Der Fokus dieser Dissertation lag in der Synthese und Untersuchung photoaktiver Übergangsmetallkomplexe. Im ersten Projekt wurde die Darstellung neuartiger NHC-Übergangsmetallkomplexe auf Basis von Mangan und Vanadium und ihre Eignung als photoinduzierte, schaltbare Radikalspezies untersucht. Neben dieser wurde im zweiten Projekt die Synthese bimetallischer Photokatalysatoren auf Basis von Kupfer und Rhodium/Iridium und deren Eignung für Hydroaminierungsreaktionen untersucht. Es gelang der Einblick in die Synthese und Darstellung vier neuartiger bimetallischer Komplexe. Im letzten Projekt dieser Promotionsarbeit wurde die Synthese und Untersuchung von photolumineszenten Zn(II)-Komplexen in niedrigen Koordinationsmodi, welche Carbenliganden als π-Chromophore tragen. Neben der erfolgreichen Synthese trigonaler Zn(II)-Komplexe, konnte ein Einblick in deren photophysikalischen Verhaltensweisen gewonnen werden. Diese Ergebnisse liefern eine neue Klasse von seltenen phosphoreszierenden Zn(II)-Komplexen, die für photokatalytische Anwendungen interessant sein könnten.
2023-01-01T00:00:00Z
Structure and dynamics studies of the enzymes hCAII and GlpG via NMR spectroscopy
Kotschy, Julia
http://hdl.handle.net/2003/42363
2024-02-29T23:12:42Z
2024-01-01T00:00:00Z
Title: Structure and dynamics studies of the enzymes hCAII and GlpG via NMR spectroscopy
Authors: Kotschy, Julia
Abstract: Lösungs- und Festkörper-NMR-Spektroskopie eignen sich gut, um Moleküle wie Proteine mit atomarer Auflösung zu charakterisieren. Hier wurden insbesondere strukturelle und dynamische Änderungen durch die Interaktion mit Inhibitoren, Strategien zur NMR-Probenoptimierung und verschiedene Methoden zur Zuordnung von NMR-Peaks eruiert. Lösungs- und Festkörper-NMR-Experimente wurden entwickelt, um die Flexibilität von SBR in hCAII-gebundenem Zustand zu messen. Das Enzym hCAII reguliert osmotische Prozesse in humanen Zellen und ist deshalb ein Zielprotein für Arzneimittel. Die entwickelte Methode zeigte, dass sich der Ligand trotz hoher Affinität in der Bindungstasche bewegt. Dies könnte von Interesse für die Wirkstoffentwicklung sein. Des Weiteren wurden sogenannte „time-shared“ 3D Lösungs- und Festkörper-NMR-Experimente für die Zuordnung von Methyl-Gruppen durch die Korrelation von Amid- und Methyl-Protonen in räumlicher Nähe zueinander genutzt.
Intramembranproteasen der Rhomboid-ähnlichen Familie sind an Prozessen beteiligt, die mit Krebs- und neurodegenerativen Erkrankungen[1] assoziiert sind. Die Intramembranprotease GlpG aus E. coli wurde als Vertreter dieser Familie betrachtet. Nachdem die Expression und Aufreinigung von GlpG optimiert worden waren, wurden die NMR-Peaks der Methyl-Gruppen durch Punktmutationen zugeordnet. Diese wurden dazu genutzt lokale Änderungen der chemischen Umgebung und der Flexibilität der Seitenketten im Mikro- bis Millisekunden-Bereich für GlpG ohne und im Komplex mit Inhibitoren mittels Lösungs-NMR-Spektroskopie zu verfolgen. Die Ergebnisse deuten darauf hin, dass die Interaktion mit dem Inhibitor STS1775 Konformationsänderungen bzw. Änderungen in der Dynamik von Methyl-Gruppen induziert, die bis zu 18 Å weit vom aktiven Zentrum entfernt sind.; Solution and solid-state NMR are valuable tools to characterize the chemical environments and dynamics of molecules like proteins with atomic resolution. Here, the effects of protein-ligand interactions on structural features and flexibility, strategies for NMR sample optimization, as well as different tools for peak assignments were elucidated.
For an unlabelled ligand in hCAII-bound state, dynamics were detected for a high-affinity complex via dedicated solution and solid-state NMR experiments. The enzyme hCAII is a well-studied drug target involved in, for example, pH regulation in human cells. The approach allowed to connect protein-ligand interactions with ligand flexibility, which might be of interest for medicinal chemistry. Furthermore, time-shared 3D NOESY/RFDR experiments were utilized both in solution and the solid state to assign methyl groups of hCAII.
Intra-membrane proteases of the rhomboid-like family are involved in processes associated with devastating conditions like cancer and neurodegeneration[1]. Here, GlpG from E. coli as a well-studied representative of the family was studied. After optimizing several expression and purification conditions, selected methyl groups were assigned via mutation to study chemical shift perturbations and microsecond to millisecond motion via solution NMR spectroscopy, comparing GlpG in apo and inhibitor-bound state. Our data indicate that upon binding of inhibitor STS1775, the conformational ensemble changes despite of up to 18 Å distance from the active site. Consequently, the occupancy of the active site modulates conformations close to but also far away from the substrate binding site.
2024-01-01T00:00:00Z
Experimental investigation of high-speed rotary bell atomization by laser-optical methods
Gödeke, Lutz
http://hdl.handle.net/2003/42362
2024-02-29T23:13:16Z
2023-01-01T00:00:00Z
Title: Experimental investigation of high-speed rotary bell atomization by laser-optical methods
Authors: Gödeke, Lutz
Abstract: The coating process in the modern automotive industry is usually implemented using high-speed rotary atomizers. The requirements for coating qualities are on the one hand of a technical nature, on the other hand they have to satisfy the subjective perception of the consumer. For the application, it is therefore of great interest to fathom and understand the physical dependencies between the applied coating layer, the selectable process parameters and material properties by means of fundamental research. This enables targeted product development that meets financial, environmental and quality requirements while economizing on material during application. Within the scope of the present work, the basic theoretical background for the three topics of coating properties, measurement technology, as well as data preparation and processing will be evaluated in detail. The focus lies on highlighting necessary adjustments in the methodology and particularities during measurement, application and data processing. For this purpose, the experimental procedure including the derived methods is presented in detail. The results are then displayed and discussed with the help of mathematical modeling approaches with respect to their
special characteristics. Finally, a comprehensive description of the relevant error sources and their individual influences is given.; Der Lackierprozess in der heutigen, modernen Automobilindustrie wird üblicherweise unter Verwendung von Hochrotationszerstäubern umgesetzt. Die Anforderungen an die Qualität des Lackes sind hierbei einerseits von technischer Natur, andererseits müssen sie dem subjektiven Empfinden des Endkunden genügen. Für die Applikation ist es somit von großem Interesse, die Zusammenhänge zwischen der aufgebrachten Lackschicht, den wählbaren Prozessparametern und Materialeigenschaften, durch Grundlagenforschung zu ergründen und zu verstehen. Hierdurch wird unter Einsparung von Material während der Applikation gezielte Produktentwicklung ermöglicht, die finanzielle, umwelttechnische und qualitative Vorgaben erfüllt. Im Rahmen der vorliegenden Arbeit werden die grundlegenden theoretischen Hintergründe für die drei Themenbereiche Lackeigenschaften, Messtechnik und Datenaufbereitung/-verarbeitung im Detail betrachtet. Der Schwerpunkt liegt hierbei darauf, notwendige Anpassungen in der Methodik und Besonderheiten während der Messung, Applikation und der Datenverarbeitung hervorzuheben. Hierzu wird das experimentelle Vorgehen inklusive der daraus abgeleiteten Methoden genau vorgestellt. Die Ergebnisse werden anschließend mit Hilfe von mathematischen Modellansätzen
in Bezug auf ihre Besonderheiten dargestellt und diskutiert. Abschließend erfolgt eine umfangreiche Beschreibung der relevanten Fehlerquellen und ihren individuellen Einflüssen.
2023-01-01T00:00:00Z
Statistische Methoden zur Validierung von Inhaltsanalysen
Koppers, Lars
http://hdl.handle.net/2003/42361
2024-02-29T23:13:12Z
2023-01-01T00:00:00Z
Title: Statistische Methoden zur Validierung von Inhaltsanalysen
Authors: Koppers, Lars
Abstract: Auch in den Geistes- und Sozialwissenschaften hat sich die Analyse von großen Textkorpora inzwischen durchgesetzt. Mit den Digital Humanity ist dort ein komplett neues Forschungsfeld entstanden. Damit wurde es zum ersten mal möglich große Textkorpora systematisch auszuwerten und nicht nur Stichproben daraus zu untersuchen. Am Dortmund Center für Datenbasierte Medienanalyse (DoCMA) wird Journalismusforschung anhand von Medienkorpora betrieben. Ein Hauptaugenmerk liegt dabei auf die Entwicklung Themen in Medienerzeugnissen. Als zentrale Methode wurde dabei mit der Latent Dirichlet Allocation (LDA; Blei, Ng u.a. 2003) gearbeitet, ein generatives Themenmodell, das aus Textkorpora Themen identifiziert, bei denen sowohl die Themenverteilung, als auch die Wortverteilung, die ein Thema definiert als latent hinter dem Text liegend angenommen werden. Die vorliegende Arbeit hat sich drei verschiedene Aspekte in diesem Themenbereich vorgenommen: Ein R-Paket für die Vorverarbeitung und Analyse der Textkorpora, mit einem Schwerpunkt auf Grafikvisualisierungen, die die zeitliche Komponente der Korpora in den Mittelpunkt stellt, ein effektiveres Sampling bei der Validierung von Subkorpora und eine Analyse der Topic Coherence für die Modellwahl.
Beim Textmining von Medienkorpora fallen immer wieder die gleichen Vorverarbeitungsschritte wie z.B. das Tokenisieren, das Entfernen von Stopwörtern und Umlauten an, bis eine LDA durchgeführt werden kann. Sowohl für die LDA. als auch für die Vorverarbeitung konnte dabei auf bestehende R-Pakete zurückgegriffen werden. Das R-Paket tosca liefert wrapper, die eine Vorverarbeitung übersichtlicher gestalten. Darüber hinaus bietet tosca einige auf die angebotene Analysepipeline abgestimmte Grafikfunktionen, die es ermöglichen ohne viel Aufwand zeitliche Verläufe von Themen und Wörtern zu erhalten. Im Bereich der Validierung wurden die von Blei vorgeschlagenen Intruder Words und Intruder Topics für R implementiert.
Für Inhaltsanalysen ist meistens nicht der ganze Korpus, sondern nur Teile davon relevant. Diese können über Wortfilter oder Themen der LDA identifiziert werden. Da die Qualität der Analyse von der Qualität des erzeugten Subkorpusses abhängt, muss dieser validiert werden, was über menschliche Kodierer*innen erfolgt. Oft braucht es mehrere Versuche, bis die Auswahlkriterien für den Subkorpus so optimiert wurden, dass seine Qualität ausreichend ist. In dieser Arbeit wird ein Verfahren vorgestellt, mit dem nicht zufällig aus dem gesamten Korpus Texte zur Validierung gezogen werden, sondern abhängig von dem bereits bestehenden Wissen aus frühreren Durchläufen aus den Schnittmengen der Subkorpora gezogen wird, die die Gesamtunsicherheit am stärksten reduzieren.
Die LDA hat das Problem, dass mathematisch optimierte Modelle für Anwender*innen oft nicht die inhaltlich besten Ergebnisse liefern. Gleichzeitig ist eine manuelle Modellwahl aus Kapazitätsgründen nur begrenzt möglich. In dieser Arbeit wird die Topic Coherence (Mimno u.a. 2011) als eine der vorgeschlagenen Maßzahlen zur Modellwahl untersucht. Während der Modellvergleich über Modelle mit verschiedenen Parametern nicht möglich ist, bietet diese Maßzahl die Möglichkeit unter wiederholten Läufen ein Modell auszusuchen. Darauf basierend wird ein Vorgehen vorgestellt, wie ein optimales Modell ausgesucht werden kann, wenn bereits von Anwender*innen für ihre Forschungsfrage optimale Themen aus anderen Läufen identifiziert wurden.
2023-01-01T00:00:00Z
Enzyme‐induced ferrification of hydrogels for toughening of functional inorganic compounds
Milovanovic, Marko
Rauner, Nicolas
Civelek, Emre
Holtermann, Tim
Jid, Oualid El
Meuris, Monika
Brandt, Volker
Tiller, Jörg C.
http://hdl.handle.net/2003/42360
2024-02-27T23:13:10Z
2022-04-01T00:00:00Z
Title: Enzyme‐induced ferrification of hydrogels for toughening of functional inorganic compounds
Authors: Milovanovic, Marko; Rauner, Nicolas; Civelek, Emre; Holtermann, Tim; Jid, Oualid El; Meuris, Monika; Brandt, Volker; Tiller, Jörg C.
Abstract: Enzyme-induced mineralization (EIM) has been shown to greatly enhance the mechanical properties of hydrogels by precipitation of calcium salts. Another feature of such hydrogels is their high toughness even when containing finely nanostructured mineral content of ≈75 wt%. This might be useful for bendable materials with high content of functional inorganic nanostructures. The present study demonstrates that EIM can form homogeneous nanostructures of water-insoluble iron salts within hydrogels. Crystalline iron(II) carbonate precipitates urease-induced within polyacrylate-based hydrogels and forms platelet structures that have the potential of forming self-organized nacre-like architectures. The platelet structure can be influenced by chemical composition of the hydrogel. Further, amorphous iron(II) phosphate precipitates within hydrogels with alkaline phosphatase, forming a nanostructured porous inorganic phase, homogeneously distributed within the double network hydrogel. The high amount of iron phosphate (more than 80 wt%) affords a stiffness of ≈100 MPa. The composite is still bendable with considerable toughness of 400 J m−2 and strength of 1 MPa. The high water content (>50%) may allow fast diffusion processes within the material. This makes the iron phosphate-based composite an interesting candidate for flexible electrodes and demonstrates that EIM can be used to deliberately soften ceramic materials, rendering them bendable.
2022-04-01T00:00:00Z
Systematic simulation strategy of plasma methane pyrolysis for CO2-free H2
Magazova, Aliya
Böddeker, Simon
Bibinov, Nikita
Agar, David W.
http://hdl.handle.net/2003/42359
2024-02-27T23:13:11Z
2022-03-24T00:00:00Z
Title: Systematic simulation strategy of plasma methane pyrolysis for CO2-free H2
Authors: Magazova, Aliya; Böddeker, Simon; Bibinov, Nikita; Agar, David W.
Abstract: Recently, the direct conversion of methane into hydrogen using cold plasma reactors has attracted increasing attention, since hydrogen has considerable potential as a future feedstock in the steel and chemical industries. However, the simulation of plasma pyrolysis reactors is extremely complex due to the vast temporal and spatial ranges of the variables involved and steep gradients. Previously, methane pyrolysis has been meticulously modeled by 0D simulations, and 3D plasma modeling has been largely confined to Argon systems. In this paper, a systematic methodology is presented, which provides an expedient and efficient hierarchy of 0D to 3D simulations, in order to approximate the methane pyrolysis simulation of a plasma reactor in its entirety. Various simulation tools are applied in a coordinated and pragmatic manner. The results show that the proposed synergy allows simplification of the reaction set and arc characteristics, significantly reducing the runtime required for the simulations.
2022-03-24T00:00:00Z
Tablet-Einsatz zur Vermittlung und Sicherung von Fachwissen
Greitemann, Lars
Melle, Insa
http://hdl.handle.net/2003/42358
2024-02-27T23:12:30Z
2022-06-15T00:00:00Z
Title: Tablet-Einsatz zur Vermittlung und Sicherung von Fachwissen
Authors: Greitemann, Lars; Melle, Insa
Abstract: Tablets kommt eine zunehmende Bedeutung im Unterricht zu. Sie ermöglichen die Erweiterung bewährter Unterrichtsformen (z. B. Bearbeitung von Aufgaben), aber auch neue Formate (z. B. Erstellung von Erklärvideos durch die Lernenden). Im Rahmen der hier vorgestellten Untersuchung wird die Wirkung des Tablet-Einsatzes in der Erarbeitungs- und Sicherungsphase analysiert. Dafür wird eine digitale Lernumgebung zur Einführung in das Basiskonzept Chemische Reaktion evaluiert, welche die Schüler:innen durch die beiden Unterrichtsphasen führt. Die Intervention wird im Rahmen eines Projekttags im Chemieanfangsunterricht durchgeführt, wobei sechs Unterrichtsstunden à 45 Minuten zur Verfügung stehen. Während der Erarbeitungsphase erfolgt ein interaktiver Informationsinput. Anschließend werden die Inhalte in Form von Experimenten angewendet und vertieft. Für die Sicherungsphase wird die Klasse in zwei Gruppen eingeteilt: Die eine Hälfte der Lernenden erstellt eigene Erklärvideos, wohingegen die andere Hälfte Aufgaben auf den iPads bearbeitet. Die Evaluation erfolgt unter anderem im Hinblick auf den Fachwissenszuwachs und die Einschätzung der Lernmaterialien durch die Schüler:innen. Der Vergleich beider Gruppen ermöglicht Aussagen über die Effektivität beider Sicherungsmaßnahmen.
2022-06-15T00:00:00Z
Gestaltung von Chemieunterricht für diverse Lerngruppen – ein Beispielunterricht zum Planungsmodell ChemDive
Holländer, Monika
Böhm, Katharina
Jasper, Leonie
Melle, Insa
http://hdl.handle.net/2003/42357
2024-02-27T23:12:31Z
2022-06-15T00:00:00Z
Title: Gestaltung von Chemieunterricht für diverse Lerngruppen – ein Beispielunterricht zum Planungsmodell ChemDive
Authors: Holländer, Monika; Böhm, Katharina; Jasper, Leonie; Melle, Insa
Abstract: Durch bildungspolitische und gesellschaftliche Veränderungen sind Lehrkräfte im deutschen Schulsystem mit einer zunehmend heterogenen Schülerschaft konfrontiert, nicht nur in inklusiven Lerngruppen. Dieser Diversität gilt es positiv zu begegnen, indem Unterricht von Beginn an für alle Lernenden zugänglich geplant und durchgeführt wird. Ein Konzept für die Gestaltung eines solchen Unterrichts ist das Universal Design for Learning, kurz UDL. Die Implementierung des nicht fachspezifischen UDL-Rahmenkonzepts in den Fachunterricht kann jedoch für (angehende) Lehrkräfte ein Hindernis darstellen. Vor diesem Hintergrund wurde auf Basis des UDL und anknüpfend an gängige Phasen- bzw. Verlaufsplankonzepte aus dem naturwissenschaftsdidaktischen Bereich das Planungsmodell ChemDive entwickelt, das Anregungen für konkrete Umsetzungsmöglichkeiten für einen universell zugänglichen Chemieunterricht bietet. ChemDive wird anhand eines Unterrichtsbeispiels erläutert und veranschaulicht.
2022-06-15T00:00:00Z
Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 6/2024
http://hdl.handle.net/2003/42356
2024-02-27T23:16:15Z
2024-02-28T00:00:00Z
Title: Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 6/2024
2024-02-28T00:00:00Z
Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 5/2024
http://hdl.handle.net/2003/42355
2024-02-26T23:16:13Z
2024-02-26T00:00:00Z
Title: Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 5/2024
2024-02-26T00:00:00Z
Organic four‐electron redox systems based on bipyridine and phenanthroline carbene architectures
Antoni, Patrick W.
Golz, Christopher
Hansmann, Max M.
http://hdl.handle.net/2003/42354
2024-02-23T23:12:34Z
2022-03-17T00:00:00Z
Title: Organic four‐electron redox systems based on bipyridine and phenanthroline carbene architectures
Authors: Antoni, Patrick W.; Golz, Christopher; Hansmann, Max M.
Abstract: Novel organic redox systems that display multistage redox behaviour are highly sought-after for a series of applications such as organic batteries or electrochromic materials. Here we describe a simple strategy to transfer well-known two-electron redox active bipyridine and phenanthroline architectures into novel strongly reducing four-electron redox systems featuring fully reversible redox events with up to five stable oxidation states. We give spectroscopic and structural insight into the changes involved in the redox-events and present characterization data on all isolated oxidation states. The redox-systems feature strong UV/Vis/NIR polyelectrochromic properties such as distinct strong NIR absorptions in the mixed valence states. Two-electron charge–discharge cycling studies indicate high electrochemical stability at strongly negative potentials, rendering the new redox architectures promising lead structures for multi-electron anolyte materials.
2022-03-17T00:00:00Z
From coiled flow inverter to stirred tank reactor – bioprocess development and ontology design
Grühn, Julia
Behr, Alexander S.
Eroglu, Talha H.
Trögel, Valentin
Rosenthal, Katrin
Kockmann, Norbert
http://hdl.handle.net/2003/42353
2024-02-23T23:13:10Z
2022-03-29T00:00:00Z
Title: From coiled flow inverter to stirred tank reactor – bioprocess development and ontology design
Authors: Grühn, Julia; Behr, Alexander S.; Eroglu, Talha H.; Trögel, Valentin; Rosenthal, Katrin; Kockmann, Norbert
Abstract: Miniaturized bioreactors, such as the coiled flow inverter (CFI), offer several benefits within process development such as lower time and cost factors. In this study, we demonstrate continuous flow experiments in a CFI and transferred them to experiments in a batch reactor by using the oxygen transfer coefficient kLa as a key parameter. In order to simplify the parameter transfer and at the same time develop a basis for future data handling according to the FAIR data principles, an equipment and process ontology was developed for these examples.
2022-03-29T00:00:00Z
Measuring and modeling of melt viscosity for drug polymer mixtures
Kimmel, Vincent
Ercolin, Enrico
Zimmer, Robin
Yörük, Muhammet
Winck, Judith
Thommes, Markus
http://hdl.handle.net/2003/42352
2024-02-23T23:13:14Z
2024-02-21T00:00:00Z
Title: Measuring and modeling of melt viscosity for drug polymer mixtures
Authors: Kimmel, Vincent; Ercolin, Enrico; Zimmer, Robin; Yörük, Muhammet; Winck, Judith; Thommes, Markus
Abstract: Melt viscosity is an essential property in pharmaceutical processes such as mixing, extrusion, fused deposition modeling, and melt coating. Measuring and modeling of the melt viscosity for drug/polymer mixtures is essential for optimization of the manufacturing process. In this work, the melt viscosity of nine formulations containing the drug substances acetaminophen, itraconazole, and griseofulvin, as well as the pharmaceutical polymers Eudragit EPO, Soluplus, and Plasdone S-630, were analyzed with a rotational and oscillatory rheometer. The shear rate, temperature, and drug fraction were varied systematically to investigate their influence on viscosity. The results for the pure polymers showed typical shear-thinning behavior and are fundamental for modeling with the Carreau and Arrhenius approaches. The investigations of the viscosity of the drug/polymer mixtures resulted in a plasticizing or a filler effect, depending on the type of drug and the phase behavior. A drug shift factor was proposed to model the change in viscosity as a function of the drug fraction. On this basis, a universal model to describe the melt viscosity of drug/polymer mixtures was developed, considering shear rate, temperature, and drug fraction.
2024-02-21T00:00:00Z
Breathing porous liquids based on responsive metal-organic framework particles
Koutsianos, Athanasios
Pallach, Roman
Frentzel-Beyme, Louis
Das, Chinmoy
Paulus, Michael
Sternemann, Christian
Henke, Sebastian
http://hdl.handle.net/2003/42351
2024-02-23T23:12:27Z
2023-07-14T00:00:00Z
Title: Breathing porous liquids based on responsive metal-organic framework particles
Authors: Koutsianos, Athanasios; Pallach, Roman; Frentzel-Beyme, Louis; Das, Chinmoy; Paulus, Michael; Sternemann, Christian; Henke, Sebastian
Abstract: Responsive metal-organic frameworks (MOFs) that display sigmoidal gas sorption isotherms triggered by discrete gas pressure-induced structural transformations are highly promising materials for energy related applications. However, their lack of transportability via continuous flow hinders their application in systems and designs that rely on liquid agents. We herein present examples of responsive liquid systems which exhibit a breathing behaviour and show step-shaped gas sorption isotherms, akin to the distinct oxygen saturation curve of haemoglobin in blood. Dispersions of flexible MOF nanocrystals in a size-excluded silicone oil form stable porous liquids exhibiting gated uptake for CO2, propane and propylene, as characterized by sigmoidal gas sorption isotherms with distinct transition steps. In situ X-ray diffraction studies show that the sigmoidal gas sorption curve is caused by a narrow pore to large pore phase transformation of the flexible MOF nanocrystals, which respond to gas pressure despite being dispersed in silicone oil. Given the established flexible nature and tunability of a range of MOFs, these results herald the advent of breathing porous liquids whose sorption properties can be tuned rationally for a variety of technological applications.
2023-07-14T00:00:00Z
Associations between physical size and space are strongly asymmetrical
Richter, Melanie
Wühr, Peter
http://hdl.handle.net/2003/42350
2024-02-23T23:14:35Z
2023-09-27T00:00:00Z
Title: Associations between physical size and space are strongly asymmetrical
Authors: Richter, Melanie; Wühr, Peter
Abstract: The spatial–size association of response codes (SSARC) effect describes the phenomenon that left responses are faster and more accurate to small stimuli whereas right responses are faster and more accurate to large stimuli, as compared to the opposite mapping. The effect indicates associations between the mental representations of physical size and space. Importantly, the theoretical accounts of SSARC effects make different predictions about the reciprocity and/or symmetry of spatial–size associations. To investigate the reciprocity of SSARC effects, we compared compatibility effects in two verbal choice-response tasks: a size–location (typical SSARC) task and a location–size (reciprocal SSARC) task. In the size–location task, participants responded verbally to a small/large stimulus by saying “left”/“right”. In the location–size task, participants responded verbally to a left-/right-side stimulus by saying “small”/“large”. Participants completed both tasks with a compatible (small–left, large–right; left–small, right–large) and an incompatible (small–right, large–left; left–large, right–small) mapping. A regular SSARC effect emerged in the size–location task. However, no reciprocal SSARC effect emerged in the location–size task if outliers were excluded. If outliers were not excluded, small reciprocal SSARC effects occurred. Associations underlying the SSARC effect are thus strongly asymmetrical: Physical (stimulus) size can prime spatial responses much more strongly than spatial (stimulus) position can prime size-related responses. The finding of asymmetrical associations between size and space is in line with some theoretical accounts of the SSARC effect but at odds with others.
2023-09-27T00:00:00Z
„Das verbrannte Holz betreibt ja keine Fotosynthese mehr“ – Analyse der Lernhürden bei der Erstellung von Kohlenstoffkreisläufen anhand von Unterrichtsvideos
Krabbe, Christina
Thelen, Frederic
Simonds, Kathryn
Melle, Insa
http://hdl.handle.net/2003/42349
2024-02-23T23:12:31Z
2022-06-15T00:00:00Z
Title: „Das verbrannte Holz betreibt ja keine Fotosynthese mehr“ – Analyse der Lernhürden bei der Erstellung von Kohlenstoffkreisläufen anhand von Unterrichtsvideos
Authors: Krabbe, Christina; Thelen, Frederic; Simonds, Kathryn; Melle, Insa
Abstract: Die Nutzung von fossilen und regenerativen Rohstoffen zur Energiegewinnung und deren Beitrag zum Kohlenstoffkreislauf ist ein komplexes Thema, welches unterschiedliche (Schüler:innen-)Schwierigkeiten mit sich bringt. Darum ist es umso wichtiger, bei der Planung eines solchen Unterrichts diese Lernhürden zu berücksichtigen. Um Studierende dafür zu professionalisieren, bietet sich die Arbeit mit Videos von realem Unterricht an. Daher wurden Unterrichtsvideos erstellt und deren Einsatz in einer Lehrveranstaltung beforscht. Die Videos zeigen Schüler:innen bei der Erstellung von Kohlenstoffkreisläufen und offenbaren (Schüler:innen-)Schwierigkeiten im Prozess der Aufgabenbearbeitung. Der Beitrag führt literaturbekannte Lernhürden zum Thema auf und zeigt anhand der ausgewerteten Ergebnisse der Videoanalysen, welche (Schüler:innen-)Schwierigkeiten Studierende anhand der entwickelten Unterrichtsvideos identifizieren können.
2022-06-15T00:00:00Z
A flexible approach to modelling over‐, under‐ and equidispersed count data in IRT: the Two‐Parameter Conway–Maxwell–Poisson model
Beisemann, Marie
http://hdl.handle.net/2003/42348
2024-02-22T23:13:08Z
2022-06-09T00:00:00Z
Title: A flexible approach to modelling over‐, under‐ and equidispersed count data in IRT: the Two‐Parameter Conway–Maxwell–Poisson model
Authors: Beisemann, Marie
Abstract: Several psychometric tests and self-reports generate count data (e.g., divergent thinking tasks). The most prominent count data item response theory model, the Rasch Poisson Counts Model (RPCM), is limited in applicability by two restrictive assumptions: equal item discriminations and equidispersion (conditional mean equal to conditional variance). Violations of these assumptions lead to impaired reliability and standard error estimates. Previous work generalized the RPCM but maintained some limitations. The two-parameter Poisson counts model allows for varying discriminations but retains the equidispersion assumption. The Conway–Maxwell–Poisson Counts Model allows for modelling over- and underdispersion (conditional mean less than and greater than conditional variance, respectively) but still assumes constant discriminations. The present work introduces the Two-Parameter Conway–Maxwell–Poisson (2PCMP) model which generalizes these three models to allow for varying discriminations and dispersions within one model, helping to better accommodate data from count data tests and self-reports. A marginal maximum likelihood method based on the EM algorithm is derived. An implementation of the 2PCMP model in R and C++ is provided. Two simulation studies examine the model's statistical properties and compare the 2PCMP model to established models. Data from divergent thinking tasks are reanalysed with the 2PCMP model to illustrate the model's flexibility and ability to test assumptions of special cases.; Correction for this article: https://doi.org/10.1111/bmsp.12312
2022-06-09T00:00:00Z
The impact of speed-accuracy instructions on spatial congruency effects
Heuer, Herbert
Wühr, Peter
http://hdl.handle.net/2003/42347
2024-02-22T23:14:38Z
2023-08-23T00:00:00Z
Title: The impact of speed-accuracy instructions on spatial congruency effects
Authors: Heuer, Herbert; Wühr, Peter
Abstract: In many tasks humans can trade speed against accuracy. This variation of strategy has different consequences for congruency effects in different conflict tasks. Recently, Mittelstädt et al. (2022) suggested that these differences are related to the dynamics of congruency effects as assessed by delta plots. With increasing delta plots in the Eriksen flanker task congruency effects were larger under accuracy set, and with decreasing delta plots in the Simon task they were smaller. Here we tested the hypothesis for a single task, making use of the observation that for the Simon task delta plots decline when the irrelevant feature is presented first, but increase when the relevant feature leads. The differences between congruency effects under speed and accuracy instructions confirmed the hypothesized relation to the slope of delta plots. In fact, for similar delta plots in the compared speed-accuracy conditions, the relation should be a straightforward consequence of the shorter and longer reaction times with speed and accuracy set, respectively. However, when relevant and irrelevant features were presented simultaneously, congruency effects were stronger under speed set at all reaction times. For this condition, a supplementary model-based analysis with an extended leaky, competing accumulator model suggested a stronger and longer-lasting influence of the irrelevant stimulus feature. The congruency effects for reaction times were accompanied by congruency effects for error rates when delta plots were decreasing, but not when they were increasing.
2023-08-23T00:00:00Z
Hybrid coherent control of magnons in a ferromagnetic phononic resonator excited by laser pulses
Scherbakov, Alexey V.
Carr, Alex D.
Linnik, Tetiana L.
Kukhtaruk, Serhii M.
Armour, Andrew D.
Nadzeyka, Achim
Rushforth, Andrew W.
Akimov, Andrey V.
Bayer, Manfred
http://hdl.handle.net/2003/42346
2024-02-22T23:12:06Z
2024-01-23T00:00:00Z
Title: Hybrid coherent control of magnons in a ferromagnetic phononic resonator excited by laser pulses
Authors: Scherbakov, Alexey V.; Carr, Alex D.; Linnik, Tetiana L.; Kukhtaruk, Serhii M.; Armour, Andrew D.; Nadzeyka, Achim; Rushforth, Andrew W.; Akimov, Andrey V.; Bayer, Manfred
Abstract: We propose and demonstrate the concept of hybrid coherent control (CC) whereby a quantum or classical harmonic oscillator is excited by two excitations: one is quasiharmonic (i.e., harmonic with a finite lifetime) and the other is a pulsed broadband excitation. Depending on the phase relation between the two excitations, controlled by the detuning of the oscillator eigenfrequencies and the wave forms of the quasiharmonic and broadband excitations, it is possible to observe Fano-like spectra of the harmonic oscillator due to the interference of the two responses to the simultaneously acting excitations. Experimentally, as an example, the hybrid CC is implemented for magnons in a ferromagnetic grating where GHz coherent phonons act as the quasiharmonic excitation and the broadband impact arises from pulsed optical excitation followed by spin dynamics in the ferromagnetic nanostructure.
2024-01-23T00:00:00Z
Konsumbewusstsein als Ich-Bewusstsein
Platter, Heike
http://hdl.handle.net/2003/42345
2024-02-23T14:04:40Z
2024-01-01T00:00:00Z
Title: Konsumbewusstsein als Ich-Bewusstsein
Authors: Platter, Heike
Abstract: Soziologischer Ausgangspunkt für diese literatur- und kulturwissenschaftliche Analyse der 1980er-Jahre war Bret Easton Ellis’ Roman American Psycho (1991). Der US-amerikanische Autor zeichnet mit dem Monolog des Yuppie-Serienmörder-Protagonisten Patrick Bateman in New York von 1986–89 ein so radikal desillusioniertes Porträt einer Konsumgesellschaft, dass der als sexistisch, pornografisch, rassistisch und trivial gebrandmarkte Roman fast zensiert worden wäre. Es war diese symbolische Zusammenführung zweier kultureller Phänomene der 1980er-Jahre – eines Yuppies und eines Serienmörders – im Extrembeispiel eines „Konsumenten“, was mich zur Feldforschung der 1980er-Jahre veranlasst hat. Das Ergebnis ist diese Dissertation in vier unabhängig voneinander bestehenden Teilen. Bindeglied ist das Phänomen des Hyperkonsumismus; einem Zeitalter, in dem Wert und sozialer Status mit materiellem Reichtum gleichgesetzt und individuelle Freiheit ideologisch zur Freiheit der Konsumentinnen und Konsumenten – „Konsumbewusstsein als Ich-Bewusstsein“ – umfunktioniert ist. Reaganomics und die politische Kultur des Reaganism waren für diese Entwicklung ausschlaggebend, wie Teil I mit einer gesellschaftspolitischen Untersuchung des Konsums und dessen Ideologie zeigt. In Teil II stehen Bret Easton Ellis’ Biografie und Werk stellvertretend für eine neue Vermarktung von Autorinnen und Autoren nach vor allem marktwirtschaftlichen Prinzipien. Durch die Ideologie des Hyperkonsumismus hat auch eine Desensibilisierung stattgefunden, die von der amerikanischen Populärkultur tradiert und perpetuiert wird. Ellis hat mit American Psycho als Populärkulturtext seiner Zeit die 1980er-Jahre sprachlich „transkribiert“ und dabei subversiv Ideologiekritik geübt, wie Teil III über ein dekonstruktives close reading des Textes zeigt. Teil IV ist Ergebnis und Nachschlagewerk meines Populärkulturzitate-Vergleichs zugleich: ein enzyklopädisch zusammengeführtes Populärkulturlexikon mit über 1200 Einträgen. Diese Rekonstruktion der 1980er-Jahre über das „Amerikabild“ in American Psycho dokumentiert den tiefgreifenden Umbruch der USA von einem Produktionsland zu einer Dienstleistungsgesellschaft, von einer analogen zu einer digitalen Welt und ein sich veränderndes Selbstverständnis des Menschen hin zur Konsumentin bzw. zum Konsumenten. Donald Trumps Wahl 2016 zum 45. Präsidenten der USA – Trump war Vorbild für den Yuppie-Serienmörder-Protagonisten im Roman – belegt weiter die Aktualität dieser Dissertation und 2024 auch ihre gesellschaftspolitische Brisanz.; In this literary and cultural analysis of the 1980s, the sociological point of reference is Bret Easton Ellis’ novel American Psycho (1991). The monologue of the yuppie serial killer protagonist, Patrick Bateman, set in New York from 1986 to 1989, presents the US author’s radically disillusioned portrayal of a consumer society. The novel, which was denounced as sexist, pornographic, racist, and trivial, was almost censored before its publication. This symbolic fusion of two cultural phenomena from the 80s – a yuppie and a serial killer – to depict an extreme example of a “consumer”, prompted my research into the 1980s. The result is this dissertation, divided into four independent parts, linked by hyper-consumerism. This concept equates the value and social status of an individual with material wealth, transforming individual freedom ideologically into consumer freedom – “Consumer Consciousness as Consciousness of Identity.” Reaganomics and the political culture of Reaganism were decisive for this development, as Part I shows with a socio-political examination of consumption and its ideology. Part II demonstrates how Ellis, through his biography and literary work, represents the new way of promoting authors according to the principles of the market economy. The ideology of hyper-consumerism also led to a desensitization, perpetuated by American popular culture. In creating American Psycho as a popular cultural text, Ellis effectively “transcribed” the 80s and, in doing so, practiced a subversive ideological critique, which Part III shows through a deconstructive close reading of the work. Part IV comprises the result of my comparison of the popular culture quotations in the book with their original sources. As an encyclopedic popular culture lexicon of its time with over 1,200 entries, it illustrates the US’s transformation from a production-based to a service-oriented society, from an analog to a digital world, and the individual’s self-perception shift from citizen to consumer. This dissertation remains socio-politically poignant in 2024, as Donald Trump, elected the 45th president of the US in 2016, was the idol referenced by the protagonist in the novel.
2024-01-01T00:00:00Z
Investigating motion events
Marklová, Anna
http://hdl.handle.net/2003/42344
2024-02-26T08:02:23Z
2023-01-01T00:00:00Z
Title: Investigating motion events
Authors: Marklová, Anna
Abstract: This cumulative dissertation investigates the impact of language-specific patterns, specifically aspect
category, on speech and perception of goal-oriented motion events. The dissertation consists of three
articles that present the project’s outcomes and significant findings. Before presenting the articles, the
dissertation provides an extensive overview of the field of linguistic relativity and previous research
on conceptual perspectives. The methodology employed in the experiments is thoroughly described,
including the rationale behind the chosen methods and participant groups. In total, data from 367
individuals were analyzed to support the findings presented in this dissertation.
Five experiments in total were conducted. The first experiment, an input study with speech elicitation,
is presented in the Description of locomotion events: Language-specific patterns in child-directed
speech. The second experiment, an eye-tracking study with adults, is presented in the Perception
of Goal-oriented Locomotion Events in Monolingual and Bilingual Adults: Free-viewing eye-tracking
study. The three remaining experiments are presented in Expression and perception of endpoints during
language acquisition: Three studies on Czech. They include an elicitation experiment, an interactive
speech production, and an eye-tracking experiment with children.
The research conducted in this dissertation led to several conclusions. Firstly, conceptual preferences
were found to play a role during first language acquisition. The input provided by parents
already contains language-specific patterns, including the expression of endpoints.
Secondly, eye-tracking experiments did not uncover language-specific patterns. These experiments
aimed to determine if the influence of perspectives on visual perception persisted without additional
language tasks. However, no evidence supporting this hypothesis was found.
Thirdly, the research highlights the difficulties associated with experimental methods. Moving away
from single mono-logical utterances to dialogues introduces higher complexity, including turn-taking
forms, questions, answers, and repetitions.
Lastly, the dissertation emphasizes the importance of including bilingual participants in experiments
and not solely relying on monolinguals.
Overall, this dissertation sheds light on the influence of language-specific preferences on description
and visual perception of goal-oriented motion events. The research reveals the role of conceptual
preferences in first language acquisition, limitations in uncovering language-specific patterns in visual
perception, challenges in experimental methods, and the significance of including bilingual participants.
2023-01-01T00:00:00Z
Essays on platform work: freelancers on digital labor platforms
Gussek, Lisa
http://hdl.handle.net/2003/42343
2024-02-22T23:14:25Z
2023-01-01T00:00:00Z
Title: Essays on platform work: freelancers on digital labor platforms
Authors: Gussek, Lisa
Abstract: More and more people are working independently as online freelancers on digital labor platforms and the number of different projects mediated and coordinated on these online markets is increasing. We argue that the current understanding of platform work is incomplete. A mixed-method research strategy was used in this thesis. First, we collected and linked previous research findings to capture the status quo and derive avenues for future research. Based on this, we conducted four qualitative and quantitative empirical studies. First, we combined a latent-dirichlet allocation analysis of almost 3,000 forum posts from IT freelancers with an additional qualitative analysis. This was followed by two qualitative exploratory analyses using a total of 35 interviews with freelancers and clients on digital labor platforms and secondary data in the form of the personal online profiles and archival documents downloaded from the platforms. Finally, we analyzed a dataset of about 7,000 IT freelancer profiles using a negative binomial regression. Therefore, we develop a framework on digital labor platform research. By synthesizing findings from the literature, we develop a classification of forms of platform work and identify research gaps. Second, we synthesize and extend the challenges and identify discussion topics of online IT freelancers. We also illustrate specifics of IT freelancing. Third, we systematize the advancement, decline, and exit dynamics within a career model of online freelancing. We also define four underlying factors that alter freelancers' relationship with the platform. The probability of exit and the dependence and benefit of the platform change over time. Fourth, we illustrate the positive relationship between the use of signals and the success of IT freelancers. We develop a new signaling typology on digital labor platforms that includes three types of signals: activating, pointing, and supporting signals. Finally, we identify concrete IT-specific success factors. This work makes several contributions to theory and practice. We contribute to research on digital platforms by characterizing the forms of platform work, structuring and add-ing new aspects to the challenges of online freelancing, identifying success factors, and devel-oping a long-term and dynamic freelance career model. We also contribute to the platform literature that addresses specific platform mechanisms by explaining lock-in effects and switching costs related to platform power. We also contribute to the career literature by illustrating that the careers of online freelancers do not fit traditional career theories or perceptions of bounda-ryless or protean careers. We contribute to signaling theory by proposing a typology of signals and analyzing the signaling environment as an under-researched aspect. Moreover, we provide empirical evidence on the specifics of IT work on digital labor platforms. We also contribute to research dealing with skill obsolescence or IT teams. Finally, our results on the platform exit dynamics contribute to research on IT turnover. For practice, our results provide insights for online freelancers, organizations or individuals as clients and the platform owners.
2023-01-01T00:00:00Z
The rank of sparse random matrices
Coja-Oghlan, Amin
Ergür, Alperen A.
Gao, Pu
Hetterich, Samuel
Rolvien, Maurice
http://hdl.handle.net/2003/42342
2024-02-21T23:12:57Z
2022-04-23T00:00:00Z
Title: The rank of sparse random matrices
Authors: Coja-Oghlan, Amin; Ergür, Alperen A.; Gao, Pu; Hetterich, Samuel; Rolvien, Maurice
Abstract: We determine the asymptotic normalized rank of a random matrix A over an arbitrary field with prescribed numbers of nonzero entries in each row and column. As an application we obtain a formula for the rate of low-density parity check codes. This formula vindicates a conjecture of Lelarge (2013). The proofs are based on coupling arguments and a novel random perturbation, applicable to any matrix, that diminishes the number of short linear relations.
2022-04-23T00:00:00Z
Design and characterization of a melt electrostatic precipitator for advanced drug formulations
Justen, Anna
Weltersbach, Alina Faye
Schaldach, Gerhard
Thommes, Markus
http://hdl.handle.net/2003/42341
2024-02-20T23:13:07Z
2024-01-01T00:00:00Z
Title: Design and characterization of a melt electrostatic precipitator for advanced drug formulations
Authors: Justen, Anna; Weltersbach, Alina Faye; Schaldach, Gerhard; Thommes, Markus
Abstract: Electrostatic precipitators (ESP) are especially known for the efficient separation of micron and submicron particles from aerosols. Wet electrostatic precipitators are particularly suitable for highly resistive materials. Using these, particles can be directly transferred into a liquid for further processing or safer handling, which is advantageous for either hazardous or valuable materials. In this work, a wet ESP, which enables the separation of highly resistive particles into a heated liquid, was designed and investigated. To do this, spray-dried drug particles were embedded in a molten sugar alcohol to enhance the drug dissolution rate. After cooling, the solidified product showed advantageous properties such as a high drug dissolution rate and easy handling for further processing. For the design of the wet ESP, different discharge electrode configurations were tested. A wall film served as the collection electrode, which was generated by a specially designed distributer die. A laminar flow regime was achieved with a homogeneous film serving as the collection electrode, which is particularly important for a high separation efficiency. A prototype was designed and constructed in this respect. The particle separation into hot liquids or onto hot surfaces is challenging due to thermal effects in ESPs. The influence of thermophoresis and drag force on the particle transport was investigated, and optimum operation parameters were found for the present ESP. A broad field of applications can be covered with the presented device, where particles are embedded in even hot liquids to form liquid suspensions or, as it is presented here, solid dispersions. The dissolution of the drug-containing solid dispersion was studied in vitro. A remarkably faster drug dissolution was observed from the solid dispersion, as compared to a powder mixture of the drug and xylitol.
2024-01-01T00:00:00Z
Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 4/2024
http://hdl.handle.net/2003/42340
2024-02-20T23:16:16Z
2024-02-20T00:00:00Z
Title: Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 4/2024
2024-02-20T00:00:00Z
Retrofitted building skins – Energetische Optimierung der Gebäudehülle im Bestand
Albus, Jutta
Rehnig, Lena
http://hdl.handle.net/2003/42339
2024-02-19T23:14:05Z
2022-07-19T00:00:00Z
Title: Retrofitted building skins – Energetische Optimierung der Gebäudehülle im Bestand
Authors: Albus, Jutta; Rehnig, Lena
Abstract: Um das Klimaziel der Bundesregierung zu erreichen, gilt die energetische Optimierung im Gebäudesektor als eine übergeordnete Aufgabe, die nicht nur die Erstellung neuer Gebäude, sondern auch die Ertüchtigung des Gebäudebestands betrifft. Gegenstand der Forschungs- und Lehrtätigkeiten des Lehrgebiets bilden Entwurfsentwicklungen, die durch innovative Gebäudehüllen und Fassadentechnologien einen nachhaltigen und ressourcenschonenden Beitrag auch für den hohen Anteil von Bestandsgebäuden leisten. Sanierungs- und Instandhaltungsmaßnahmen werden vor dem Hintergrund energetischer Optimierungsstrategien, nachhaltiger Gebäudekonzeption und ressourcenschonendem Materialeinsatz entwickelt und fokussieren dabei aktive und passive Maßnahmen. Dabei soll insbesondere der Anteil von bestehenden Büro- und Verwaltungsbauten betrachtet werden, der neben dem Wohngebäudebestand ein erhebliches Potential zur Reduzierung von CO2-Emissionen aufzeigt.; In order to adapt to the Federal Government's Climate Action Programme, energy optimization in the building sector is considered an important task that not only affects the construction of new buildings, but also the renovation of existing building stock. The research and teaching activities of the junior professorship focus on architectural design developments that follow sustainable and resource-saving parameters by implementing innovative building skins and facade technologies to improve the energetic building performance. Renovation and maintenance methods are developed against the background of energy optimization strategies, sustainable building design and resource-efficient use of materials, focusing on the implementation of active and passive measures. This paper emphasizes the proportion of existing office and administrative buildings, which, in addition to the residential building stock, have considerable potential to reduce CO2 emissions.
2022-07-19T00:00:00Z
Experimental splitting of hydrogen sulfide by halogens for application in reaction cycles
Wiesehahn, Maximilian
Zimmermann, Elodia Morales
Agar, David W.
http://hdl.handle.net/2003/42338
2024-02-19T23:13:10Z
2022-04-21T00:00:00Z
Title: Experimental splitting of hydrogen sulfide by halogens for application in reaction cycles
Authors: Wiesehahn, Maximilian; Zimmermann, Elodia Morales; Agar, David W.
Abstract: Hydrogen sulfide is a toxic gas that is almost always present in the processing of crude oil or natural gas and must be removed. In addition, hydrogen can be used as an energy carrier if it can be separated from H2S. In this work, as the first step of a reaction cycle that could achieve just that, the bromination and chlorination of hydrogen sulfide are experimentally studied. It can be shown that both halogens are capable of completely converting hydrogen sulfide in a gas phase reaction. While the chlorination can produce byproducts, the bromination is free of such.
2022-04-21T00:00:00Z
Development of an automated adsorbent selection strategy for liquid–phase adsorption
Schreiber, Mareike
Schembecker, Gerhard
http://hdl.handle.net/2003/42337
2024-02-19T23:13:08Z
2022-04-06T00:00:00Z
Title: Development of an automated adsorbent selection strategy for liquid–phase adsorption
Authors: Schreiber, Mareike; Schembecker, Gerhard
Abstract: A systematic and automatic approach for adsorbent selection for liquid–phase adsorption is proposed. Based on physical properties like polarity, pore size, and specific surface, a screening strategy is developed and automated on a robotic platform. Key performance indicators are applied ensuring economically based decisions. The approach developed is verified by adsorption of caffeine out of an aqueous solution with vanillin, uracil, and α–ionon as impurities. The adsorbent selection strategy leads to the polymeric adsorbent SP207 and a specific surface of 15 m2mL−1 ending in a separation cost indicator of 16 € gCaffeine−1. This work proposes an opportunity for accelerated process design strengthened by the usage of robotic devices.
2022-04-06T00:00:00Z
Catalytic synthesis of methyl 9,10‐dihydroxystearate from technical feedstocks in continuous flow via epoxidation and hydrolysis
Vondran, Johanna
Benninghoff, Tobias
Emminghaus, Anahita Irene
Seidensticker, Thomas
http://hdl.handle.net/2003/42336
2024-02-16T23:13:10Z
2022-04-30T00:00:00Z
Title: Catalytic synthesis of methyl 9,10‐dihydroxystearate from technical feedstocks in continuous flow via epoxidation and hydrolysis
Authors: Vondran, Johanna; Benninghoff, Tobias; Emminghaus, Anahita Irene; Seidensticker, Thomas
Abstract: The sequence of the homogeneously Ru-catalyzed epoxidation of methyl oleate and acid-catalyzed hydrolysis of the corresponding epoxide methyl 9,10-epoxy stearate is successfully transferred from batch into flow mode, allowing for the continuous production of methyl 9,10-dihydroxystearate. Thereby, methyl oleate is first converted up to 97% within 14 min at excellent selectivity in the epoxidation using aqueous hydrogen peroxide as the sole oxidant. In the subsequent hydrolysis, a residence time of 10 min is sufficient for quantitative conversion of the epoxide. The desired, pure vicinal diol is isolated upon crystallization from the crude reaction mixture in an integrated process starting from technical grade (91.5%) substrate. The isolated yield is increased upon the addition of water as a green antisolvent from 75% up to 97%. Finally, the concept is transferred to methyl oleate of even lower purity (76%), still obtaining an isolated yield of 66% of the vicinal diol. Thus, the integration of sequential epoxidation and hydrolysis into continuous flow and subsequent crystallization allows for high conversion and selectivities within a total residence time of 27 min, corresponding to a space–time yield of 190 g h−1 L−1 in the epoxidation and 164 g h−1 L−1 in the hydrolysis, respectively.
Practical applications: The modular flow setup enables the targeted functionalization toward the epoxide intermediate or the vicinal diol. Both offer versatile applications for the production of polymers, surfactants, or toward further conversion as in oxidative cleavage starting from methyl oleate. The application of flow chemistry offers advantages for the safe handling of hydrogen peroxide even at high temperatures. With fats and oils being natural substances, oleochemicals such as fatty acid methyl esters are typically available in technical purity so that efficient strategies for the isolation of pure products are of need. Crystallization of the product is promising, as additional organic solvents are not required. Thus, using the difference in melting point and solubility behavior of the desired product compared to other compounds is a promising method for the applicability of renewable resource-based substrate mixtures.
2022-04-30T00:00:00Z
On the determination of thermal boundary conditions for parameter identifications of thermo-mechanically coupled material models
Rose, Lars
Menzel, Andreas
http://hdl.handle.net/2003/42335
2024-02-16T23:13:34Z
2022-05-24T00:00:00Z
Title: On the determination of thermal boundary conditions for parameter identifications of thermo-mechanically coupled material models
Authors: Rose, Lars; Menzel, Andreas
Abstract: Identifiability and sensitivity of thermal boundary coefficients identified alongside thermal material parameters by means of full field measurements during a simple tension test are shown empirically using a simple tension test with self heating as a proof of concept. The identification is started for 10 different initial guesses, all of which converge toward the same optimum. The solution appears to be locally unique and parameters therefore independent, but a comparison against a reference solution indicates high correlation between three model parameters and the prescribed external temperatures required to model heat exchange with either air or clamping jaws. This sensitivity is further analyzed by rerunning the identification with different prescribed external temperatures and by comparing the obtained optimal parameter values. Although the model parameters are independent, optimal values for heat conduction and the heat transfer coefficients are highly correlated as well as sensitive with respect to a change, respectively, measurement error of the external temperatures. A precise fit on the basis of a simple tension test therefore requires precise measurements and a suitable material model which is able to accurately predict dissipated energy.
2022-05-24T00:00:00Z
Gezielte Eigenspannungseinstellung in der inkrementellen Blechumformung
Maaß, Fabian
http://hdl.handle.net/2003/42334
2024-02-16T23:13:28Z
2024-01-01T00:00:00Z
Title: Gezielte Eigenspannungseinstellung in der inkrementellen Blechumformung
Authors: Maaß, Fabian
Abstract: Infolge einer inhomogenen Umformung zur Herstellung von Bauteilen verbleiben Spannungen im Material. Diese Eigenspannungen sind mechanische Spannungen, die zu einer inneren Belastung des
Bauteils führen. Das Vorhandensein von Eigenspannungen kann die Leistungsfähigkeit eines Bauteils
je nach Ausprägung signifikant steigern oder zu einem früheren Versagen im Belastungsfall führen.
Daher ist die Kenntnis des resultierenden Eigenspannungszustands infolge des Fertigungsschritts
durch geeignete Prognosemodelle unerlässlich. Eigenspannungen werden für gewöhnlich durch
nachgelagerte mechanische Bearbeitungsschritte gezielt in Bauteile eingebracht oder durch thermische Nachbehandlungsprozesse eliminiert. Diese nachgelagerten Prozessschritte zur
Eigenspannungseinstellung benötigen zusätzliche Ressourcen.
Das flexible Umformverfahren der inkrementellen Blechumformung zeichnet sich im Vergleich zu
konventionellen Umformverfahren durch geringe Werkzeugkosten und Prozesskräfte bei gleichzeitig
erhöhter Umformbarkeit aus. Durch die unterhalb des Werkzeugs lokalisierte Umformzone bietet die
inkrementelle Blechumformung die Möglichkeit, Eigenspannungen lokal definiert in Bauteile
einzubringen. Die Flexibilität der inkrementellen Blechumformung ermöglicht die Herstellung
geometrisch identischer Bauteile mit unterschiedlichen Prozessparametern, welche die wirkenden
Umformmechanismen beeinflussen. Der Zusammenhang von Prozessparametern, Umformmechanismen und
den daraus resultierenden Eigenspannungen ist bislang nicht bekannt. Ziel dieser Arbeit ist es
daher, ein grundlegendes Verständnis über die Eigenspannungsausbildung bei der inkrementellen
Blechumformung zu erarbeiten, um Eigenspannungen durch diesen Umformprozess stabil und definiert
in Bauteile einzubringen sowie die Verbesserung des Bauteileinsatzverhaltens durch gezielt
induzierte Eigenspannungszustände zu quantifizieren.
Unter Zuhilfenahme eines numerischen Prozessmodells wird der Einfluss von Zustellinkrement und
Werkzeugradius auf die Umformmechanismen und die Eigenspannungsausbildung im Bauteil
identifiziert. Basierend auf diesen Ergebnissen werden Konzepte der Spannungsüberlagerung
analysiert und experimentell erprobt, um die Möglichkeiten der Eigenspannungseinstellung während
des Umformprozesses zu vergrößern.
Eine gezielte Einstellung des Eigenspannungszustands kann genutzt werden, um die Leistungsfähigkeit
von Bauteilen unter statischer und zyklischer Last zu steigern. Dies eröffnet Möglichkeiten der
Materialeinsparung durch niedrigere Sicherfaktoren bei der Bauteilauslegung, um dem
Leichtbaugedanken zur Steigerung der Ressourceneffizienz gerecht zu werden.
2024-01-01T00:00:00Z
The machines take over: a comparison of various supervised learning approaches for automated scoring of divergent thinking tasks
Buczak, Philip
Huang, He
Forthmann, Boris
Doebler, Philipp
http://hdl.handle.net/2003/42333
2024-02-15T23:13:06Z
2022-08-08T00:00:00Z
Title: The machines take over: a comparison of various supervised learning approaches for automated scoring of divergent thinking tasks
Authors: Buczak, Philip; Huang, He; Forthmann, Boris; Doebler, Philipp
Abstract: Traditionally, researchers employ human raters for scoring responses to creative thinking tasks. Apart from the associated costs this approach entails two potential risks. First, human raters can be subjective in their scoring behavior (inter-rater-variance). Second, individual raters are prone to inconsistent scoring patterns (intra-rater-variance). In light of these issues, we present an approach for automated scoring of Divergent Thinking (DT) Tasks. We implemented a pipeline aiming to generate accurate rating predictions for DT responses using text mining and machine learning methods. Based on two existing data sets from two different laboratories, we constructed several prediction models incorporating features representing meta information of the response or features engineered from the response’s word embeddings that were obtained using pre-trained GloVe and Word2Vec word vector spaces. Out of these features, word embeddings and features derived from them proved to be particularly effective. Overall, longer responses tended to achieve higher ratings as well as responses that were semantically distant from the stimulus object. In our comparison of three state-of-the-art machine learning algorithms, Random Forest and XGBoost tended to slightly outperform the Support Vector Regression.; Correction for this article: https://doi.org/10.1002/jocb.627
2022-08-08T00:00:00Z
Heterogenität der Effekte von Ausdauertraining zur Steigerung der kardiorespiratorischen Fitness bei Personen mit Multipler Sklerose
Schlagheck, Marit Lea
http://hdl.handle.net/2003/42332
2024-02-15T23:15:26Z
2023-01-01T00:00:00Z
Title: Heterogenität der Effekte von Ausdauertraining zur Steigerung der kardiorespiratorischen Fitness bei Personen mit Multipler Sklerose
Authors: Schlagheck, Marit Lea
Abstract: Körperliches Training gewinnt als nicht-medikamentöse Therapiemaßnahme bei Multipler Sklerose (MS) zunehmend an Bedeutung. Die aktuelle Studienlage zeigt jedoch uneinheitliche Effekte von Ausdauertraining hinsichtlich verschiedener physiologischer, biologischer und patientenzentrierter Endpunkte. Die vorliegende Dissertation untersucht potenzielle Einflussfaktoren auf die Heterogenität der Ergebnisse: (i) die Qualität der Interventionsinhalte und deren Dokumentation, (ii) die Aussagekraft der Ergebnismessung, und (iii) Faktoren der individuellen Trainingsresponse.
Die Ergebnisse zeigen, dass fundamentale Trainingsprinzipien in bisherigen Interventionsstudien unzureichend berücksichtigt wurden. Fehlende signifikante Ergebnisse können auf Unzulänglichkeiten in der Trainingsgestaltung zurückzuführen sein, was zu einer Unterschätzung der Effekte von körperlichem Training führt. Nur knapp 50% der untersuchten Studien berichten adäquat über Trainingsinhalte und nur 3% über die Trainingsadhärenz, was die Interpretation und die Reproduzierbarkeit einschränken. Publikation 2 zeigt, dass über 40% der Personen mit MS in stationärer Rehabilitation die allgemeinen Kriterien einer maximalen kardiorespiratorischen Belastung während eines Ausbelastungstests nicht erfüllen. Dies schränkt die Beurteilung des Fitnesszustandes, der Effektivität von Trainingsprogrammen und die Trainingssteuerung ein. Schließlich bestätigen die Ergebnisse der Interventionsstudie in Publikation 3 signifikante Verbesserungen der kardiorespiratorischen Fitness auf Gruppenebene sowohl nach hochintensivem Intervalltraining (HIIT) als auch nach moderat-intensivem kontinuierlichem Training. Auf individueller Ebene profitierten jüngere, weniger fitte Personen, die HIIT durchführten, am meisten von der dreiwöchigen Trainingsintervention.
Zusammenfassend zeigen die Ergebnisse der Arbeit, dass die heterogenen Studienergebnisse zu den Effekten von Ausdauertraining bei MS durch Mängel in der Interventionsgestaltung, eine unzureichende Aussagekraft der Ergebnismessung und interindividuelle Unterschiede in der Trainingsresponse beeinflusst werden. Um die Evidenz für körperliches Training mit der Evidenz für medikamentöse Behandlungen vergleichbar zu machen, ist es unerlässlich, dass die Gestaltung und Dokumentation den entsprechenden Standards gleichkommen. Zukünftige Studien sollten optimierte Möglichkeiten zur Beurteilung der kardiorespiratorischen Fitness und zur Trainingssteuerung bei Personen mit MS untersuchen. Darüber hinaus ist es wichtig, Faktoren der individuellen Trainingsresponse zu berücksichtigen, um personalisierte Trainingsansätze zu entwickeln, die den Bedürfnissen der Betroffenen gerecht werden. Die Berücksichtigung dieser Aspekte kann das Verständnis und die Anwendung von Ausdauertraining als therapeutische Maßnahme bei MS verbessern.
2023-01-01T00:00:00Z
Parameter identification approaches with application to different classes of materials
Schulte, Robin
http://hdl.handle.net/2003/42331
2024-02-15T23:13:44Z
2023-01-01T00:00:00Z
Title: Parameter identification approaches with application to different classes of materials
Authors: Schulte, Robin
Abstract: Die vorliegende Arbeit befasst sich mit verschiedenen Strategien der Parameteridentifikation bezüglich der multi-objektiven Optimierung unter Berücksichtigung von integralen Größen und Feldgrößen, um effizient Parameter von komplexen Materialmodellen zu identifizieren, wie beispielsweise Gradienten-erweiterte Schädigungsmodelle. Außerdem wird eine hybride Strategie entwickelt, um die Problematik der Bestimmung von adequaten Startwerten zu überwinden. Zu diesem Zweck wird ein künstliches neuronales Netz mit den simulierten Materialverhalten von diversen Parameterkombinationen trainiert. Anschließend wird die experimentell gemessene Materialantwort in das Netz eingegeben um eine Vorhersage der Parameter zu erhalten, die im Anschluss als qualitativ hochwertiger Startwert für eine multi-objektive Parameteridentifikation verwendet wird. In dieser Arbeit werden die hybride und die weiteren Strategien untersucht unter der Verwendung von verschiedener komplexer Materialmodelle und diverser Gruppen von Materialien. Zusätzlich wird ein Gradienten-erweitertes, mit Viskoelastizität unter finiter Dehnung gekoppeltes Schädigungsmodel entwickelt um effizient Schädigungseffekte in ratenabhängigen Materialien abzudecken. Des Weiteren wird im Kontext eines Laminat-basierenden Modells für ferroelektrische Materialien eine numerische Untersuchung bezüglich numerisch effizienter Fischer-Burmeister Ansätze durchgeführt, um die häufig auftretenden Karush-Kuhn-Tucker Konditionen zu lösen.; This thesis deals with different parameter identification strategies regarding multi-objective optimisations including integral and field data in order to efficiently identify parameters of complex material models, e.g.~gradient-enhanced damage models. In addition, to overcome the difficulty of finding appropriate starting values, a hybrid strategy is developed. For this purpose, an artificial neural network is trained with simulated material behaviours of various parameter combinations. Subsequently, the experimentally measured response is fed into the network to obtain a parameter prediction which is afterwards employed as qualitative starting value for a subsequent multi-objective parameter identification. In this work, the hybrid and the other strategies are investigated by employing different complex material models and various material groups. Moreover, a gradient-enhanced damage model coupled to finite strain viscoelasticity is developed to efficiently cover damage effects in rate-dependent material responses. Furthermore, in the context of a laminate-based model for ferroelectric materials, a numerical investigation is performed regarding numerically efficient Fischer-Burmeister approaches, to solve the frequently occurring Karush-Kuhn-Tucker conditions.
2023-01-01T00:00:00Z
Filmreaktorkonzepte und Strategien zur Vermeidung und Entfernung von Kohlenstoffablagerungen bei der Methanpyrolyse
Becker, Tobias
http://hdl.handle.net/2003/42330
2024-02-15T23:13:16Z
2023-01-01T00:00:00Z
Title: Filmreaktorkonzepte und Strategien zur Vermeidung und Entfernung von Kohlenstoffablagerungen bei der Methanpyrolyse
Authors: Becker, Tobias
Abstract: Der Weg zu einer klimafreundlicheren Zukunft führt unweigerlich über die Dekarbonisierung der wichtigsten Wirtschaftssektoren Energie, Bausektor, Verkehr, Industrie und Landwirtschaft. Wasserstoff leistet einen großen Beitrag auf diesem Weg, als alternativer Energiespeicher, Energieträger oder Treibstoff.
Emissionsfreier Wasserstoff kann unter Nutzung regenerativer Energien via Methanpyrolyse produziert werden. Das Nebenprodukt Kohlenstoff erhöht durch Verkauf die Wirtschaftlichkeit des Prozesses, erzeugt aber auch verfahrenstechnische Herausforderungen. Akkumulation von Kohlenstoff endet unumgänglich mit einer Verblockung des Reaktors.
Zur Vermeidung und Entfernung von Kohlenstoffablagerungen wurden verschiedene Reaktorkonzepte studiert. Im Fallfilmreaktor und im rotierenden Filmreaktor wird die Wand durch einen Film flüssigen Metalls vor Ablagerungen geschützt. Beide Reaktoren wurden experimentell, mit Schwerpunkten hinsichtlich der Ausbildung des Films, der Filmdicke und des Verweilzeitverhaltens, untersucht. Mit CFD-Modellen wurden die Pyrolysereaktion in den Reaktoren und die Abtrennung von Kohlenstoffpartikeln beleuchtet. In einem Fallfilmreaktor (L = 3 m, ⌀ = 26 mm) konnten bei 1600 K hohe Umsätze von > 90 % erzielt werden. Der Gleichstrombetrieb wurde als vorteilhaft identifiziert und mehr als 75 % des produzierten Kohlenstoffs konnten über den flüssigen Film abgetrennt werden. Der rotierende Filmreaktor wurde etwas kürzer (1,7 m) und breiter (. = 44 mm) ausgeführt. Umsätze > 83 % wurden bei gleichem formalen Reaktionsvolumen erreicht. Die Abtrennung des Kohlenstoffs wurde durch die Rotation des Reaktors verbessert. Ab Partikelgrößen von 5 µm konnte der Kohlenstoff nahezu vollständig über den Film abgetrennt werden.
Neben den Filmreaktorkonzepten, wurden Bildung, Einfluss auf die Reaktion und Entfernung von Kohlenstoff in Rohrreaktoren untersucht. In kinetischen Untersuchungen wurde gezeigt, dass im Reaktor akkumulierender Kohlenstoff die Reaktion beschleunigt. Mit einem Modell aus Gasphasen- und Oberflächenreaktion konnten die Effekte gut beschrieben werden. Zuletzt wurden die Kohlenstoffverblockungen mit einer Pressvorrichtung mechanisch entfernt. Die zur Entfernung notwendige Kraft steigt mit der Kohlenstoffmenge im Reaktor und ist abhängig vom Reaktormaterial.; The path to a more carbon-neutral future inevitably involves decarbonizing the key economic sectors of energy, construction, transport, industry and agriculture. Hydrogen plays a major role on this path, as energy storage, energy carrier or fuel.
Zero-emission hydrogen can be produced using renewable energies via methane pyrolysis. The by-product carbon contributes to the economic efficiency of the process, but also creates challenges in process engineering. Accumulation of carbon inevitably ends with clogging of the reactor.
Various reactor concepts were studied to prevent and remove carbon deposits. A liquid metal film protects the wall from deposits within the falling film reactor and the rotating film reactor. Both reactors were studied experimentally, focusing on the film formation, film thickness and residence time distribution. CFD models were used to investigate the pyrolysis reaction and the separation of carbon. In a falling film reactor (L = 3 m, ⌀ = 26 mm), high conversions of > 90 % were obtained at 1600 K. Co-current operation was identified as advantageous and more than 75 % of the carbon could be separated via the liquid film. The rotating film reactor was shorter (1.7 m) and wider (. = 44 mm). Conversions > 83 % were achieved in the same formal reaction volume. Carbon separation was improved by rotating the reactor. From particle sizes of 5 µm, almost all the carbon was separated via the film.
In addition to the film reactors, formation and removal of carbon in tubular reactors were studied. Kinetic studies showed that carbon accumulating in the reactor accelerates the reaction. Using a model of gas-phase and surface reaction, the effects could be well described. Finally, the carbon aggregates were removed mechanically with a pressing device. The force required for removal increases with the amount of carbon in the reactor and depends on the reactor material.
2023-01-01T00:00:00Z
Covering Cohesion Policy in Europe
Alfter, Brigitte
Almodt, Remi
Beuran, Paul
Brandt, Richard
Bursens, Peters
Chlebowski, Michał
Fengler, Susanne
Frangonikolopoulos, Christos
Frateur, Wouter
Frias, Paulo
Glinka, Kamil
Homolová, Adriana
Kostarella, Ioanna
Kreutler, Marcus
Kurkowski, Isabella
Kuś, Michał
Lemke, Julia
Lima, Helena
Mack, Johanna
Müller, Henrik
Niepert, Juliane
Nistor, Cristina
Panagiotou, Nikos
Petho, Andras
Schuck, Christoph
Sheffield, Hazel
Stavar, Ancuta
Szilagyi, Alexandra
Szynol, Adam
Touwen, Carien
Veglis, Andreas
Walewijns, David
Zappe, Anna-Carin
http://hdl.handle.net/2003/42329
2024-02-14T17:10:08Z
2024-01-01T00:00:00Z
Title: Covering Cohesion Policy in Europe
Authors: Alfter, Brigitte; Almodt, Remi; Beuran, Paul; Brandt, Richard; Bursens, Peters; Chlebowski, Michał; Fengler, Susanne; Frangonikolopoulos, Christos; Frateur, Wouter; Frias, Paulo; Glinka, Kamil; Homolová, Adriana; Kostarella, Ioanna; Kreutler, Marcus; Kurkowski, Isabella; Kuś, Michał; Lemke, Julia; Lima, Helena; Mack, Johanna; Müller, Henrik; Niepert, Juliane; Nistor, Cristina; Panagiotou, Nikos; Petho, Andras; Schuck, Christoph; Sheffield, Hazel; Stavar, Ancuta; Szilagyi, Alexandra; Szynol, Adam; Touwen, Carien; Veglis, Andreas; Walewijns, David; Zappe, Anna-Carin
2024-01-01T00:00:00Z
X‐ray‐based tomographic imaging for the investigation of laminar mixing in capillaries
Schuler, Julia
Herath, Jakob
Kockmann, Norbert
http://hdl.handle.net/2003/42328
2024-02-14T23:13:13Z
2022-05-06T00:00:00Z
Title: X‐ray‐based tomographic imaging for the investigation of laminar mixing in capillaries
Authors: Schuler, Julia; Herath, Jakob; Kockmann, Norbert
Abstract: Micro-computed tomography is a promising non-invasive imaging technology that offers high spatial resolution without requiring optical access. This opens the opportunity to analyze concentration fields in mixing equipment in 3D. To demonstrate the potential of the methodology, laminar mixing in helically coiled capillaries is investigated by tracking the radial distribution of potassium iodide along the main flow direction. Dean flow can be observed in the helically coiled capillaries, which intensifies with Reynolds number and decreasing effect of gravity.
2022-05-06T00:00:00Z
Ultra‐long lived luminescent triplet excited states in cyclic (alkyl)(amino)carbene complexes of Zn(II) halides
Mrózek, Ondřej
Gernert, Markus
Belyaev, Andrey
Mitra, Mousree
Janiak, Lars
Marian, Christel M.
Steffen, Andreas
http://hdl.handle.net/2003/42327
2024-02-14T23:12:32Z
2022-05-18T00:00:00Z
Title: Ultra‐long lived luminescent triplet excited states in cyclic (alkyl)(amino)carbene complexes of Zn(II) halides
Authors: Mrózek, Ondřej; Gernert, Markus; Belyaev, Andrey; Mitra, Mousree; Janiak, Lars; Marian, Christel M.; Steffen, Andreas
Abstract: The high element abundance and d10 electron configuration make ZnII-based compounds attractive candidates for the development of novel photoactive molecules. Although a large library of purely fluorescent compounds exists, emission involving triplet excited states is a rare phenomenon for zinc complexes. We have investigated the photophysical and -chemical properties of a series of dimeric and monomeric ZnII halide complexes bearing a cyclic (alkyl)(amino)carbene (cAAC) as chromophore unit. Specifically, [(cAAC)XZn(μ-X)2ZnX(cAAC)] (X=Cl (1), Br (2), I (3)) and [ZnX2(cAAC)(NCMe)] (X=Br (4), I (5)) were isolated and fully characterized, showing intense visible light photoluminescence under UV irradiation at 297 K and fast photo-induced transformation. At 77 K, the compounds exhibit improved stability allowing to record ultra-long lifetimes in the millisecond regime. DFT/MRCI calculations confirm that the emission stems from 3XCT/LEcAAC states and indicate the phototransformation to be related to asymmetric distortion of the complexes by cAAC ligand rotation. This study enhances our understanding of the excited state properties for future development and application of new classes of ZnII phosphorescent complexes.
2022-05-18T00:00:00Z
Von der Erreichbarkeitsexplosion zur Mobilitätsarmut
Scheiner, Joachim
Hölzel, David
Hülz, Martina
Mattioli, Giulio
http://hdl.handle.net/2003/42326
2024-02-14T23:14:06Z
2024-02-01T00:00:00Z
Title: Von der Erreichbarkeitsexplosion zur Mobilitätsarmut
Authors: Scheiner, Joachim; Hölzel, David; Hülz, Martina; Mattioli, Giulio
Abstract: Die wissenschaftliche und politische Diskussion um die Auswirkungen von eingeschränkter
Erreichbarkeit und Mobilität auf soziale Teilhabe ist im Kontext von sozialen und sozialräumlichen Ungleichheit in Mobilität und Erreichbarkeit entstanden. Der Beitrag führt in die entsprechende (wissenschaftliche) Diskussion ein. Zunächst wird das Phänomen der Mobilitätsarmut in den Kontext der extremen Zunahme an Mobilität und Erreichbarkeit im 20. Jahrhundert gestellt. Wir argumentieren, dass in der Diskussion um Grunddaseinsfunktionen
die Mobilität in den Rang eines Grundbedürfnisses "erhoben" wurde und damit das Daseinsvorsorgeprinzip der
Erreichbarkeit durch räumliche Nähe in den Hintergrund gerückt ist. Um Ungleichheiten zu reduzieren und für alle eine angemessene Teilhabe zu ermöglichen, sollten sich Raum- und Verkehrsplanung an den Prinzipien der Gerechtigkeit und Suffizienz orientieren, nicht an der Nutzenmaximierung. Dies bedeutet, dass bei planerischen Entscheidungen zunächst stets der Nutzen für die am wenigsten Privilegierten im Mittelpunkt stehen sollte, etwa für diejenigen, die unter Erreichbarkeits- oder/und Mobilitätsarmut leiden. Suffizienz in der Mobilität bedeutet, dass die staatliche Vorsorge sich auf die Gewährleistung der Befriedigung von Grundbedürfnissen beschränken soll. Nach dieser normativen Diskussion werden Grundkonzepte (Dimensionen, Indikatoren, Risikofaktoren) zur Untersuchung erreichbarkeits- und mobilitätsbezogener Exklusion sowie beispielhafte empirische Studien vorgestellt. Aus der Diskussion werden Schlussfolgerungen vor dem Hintergrund gegenwärtiger Verkehrspolitik gezogen.
2024-02-01T00:00:00Z
Cell‐free protein synthesis for the screening of novel azoreductases and their preferred electron donor
Rolf, Jascha
Ngo, Anna Christina Reyes
Lütz, Stephan
Tischler, Dirk
Rosenthal, Katrin
http://hdl.handle.net/2003/42325
2024-02-12T23:13:16Z
2022-05-20T00:00:00Z
Title: Cell‐free protein synthesis for the screening of novel azoreductases and their preferred electron donor
Authors: Rolf, Jascha; Ngo, Anna Christina Reyes; Lütz, Stephan; Tischler, Dirk; Rosenthal, Katrin
Abstract: Azoreductases are potent biocatalysts for the cleavage of azo bonds. Various gene sequences coding for potential azoreductases are available in databases, but many of their gene products are still uncharacterized. To avoid the laborious heterologous expression in a host organism, we developed a screening approach involving cell-free protein synthesis (CFPS) combined with a colorimetric activity assay, which allows the parallel screening of putative azoreductases in a short time. First, we evaluated different CFPS systems and optimized the synthesis conditions of a model azoreductase. With the findings obtained, 10 azoreductases, half of them undescribed so far, were screened for their ability to degrade the azo dye methyl red. All novel enzymes catalyzed the degradation of methyl red and can therefore be referred to as azoreductases. In addition, all enzymes degraded the more complex and bulkier azo dye Brilliant Black and four of them also showed the ability to reduce p-benzoquinone. NADH was the preferred electron donor for the most enzymes, although the synthetic nicotinamide co-substrate analogue 1-benzyl-1,4-dihydronicotinamide (BNAH) was also accepted by all active azoreductases. This screening approach allows accelerated identification of potential biocatalysts for various applications.
2022-05-20T00:00:00Z
On the complexity of the bilevel minimum spanning tree problem
Buchheim, Christoph
Henke, Dorothee
Hommelsheim, Felix
http://hdl.handle.net/2003/42324
2024-02-12T23:12:01Z
2022-06-08T00:00:00Z
Title: On the complexity of the bilevel minimum spanning tree problem
Authors: Buchheim, Christoph; Henke, Dorothee; Hommelsheim, Felix
Abstract: We consider the bilevel minimum spanning tree (BMST) problem where the leader and the follower choose a spanning tree together, according to different objective functions. We show that this problem is NP-hard, even in the special case where the follower only controls a matching. Moreover, we give some evidence that BMST might even remain hard in case the follower controls only few edges. On the positive side, we present a (|V|-1)-approximation algorithm for BMST, where |V| is the number of vertices. Moreover, we show that 2-approximating BMST is fixed-parameter tractable and that, in case of uniform costs on leader's edges, even solving BMST exactly is fixed-parameter tractable. We finally consider bottleneck variants of BMST and settle the complexity landscape of all combinations of sum or bottleneck objective functions for the leader and follower, for the optimistic as well as the pessimistic setting.
2022-06-08T00:00:00Z
Chelating phosphorus–an O, C, O-coordinating pincer-type ligand coordinating PIII and PV centres
Gock, Michael
Lutter, Michael
Pintus, Anna
Schollmeier, Dieter
Arca, Massimiliano
Lippolis, Vito
Jurkschat, Klaus
http://hdl.handle.net/2003/42323
2024-02-12T23:12:33Z
2022-07-12T00:00:00Z
Title: Chelating phosphorus–an O, C, O-coordinating pincer-type ligand coordinating PIII and PV centres
Authors: Gock, Michael; Lutter, Michael; Pintus, Anna; Schollmeier, Dieter; Arca, Massimiliano; Lippolis, Vito; Jurkschat, Klaus
Abstract: The sequence of reactions of the phosphorus-containing aryllithium compound 5-t-Bu-1,3-[(P(O)(O-i-Pr)2]2C6H2Li (ArLi) with Ph2PCl, KMnO4, elemental sulfur and elemental selenium, respectively, gave the aryldiphenylphosphane chalcogenides 5-t-Bu-1,3-[(P(O)(O-i-Pr)2]2C6H2P(E)Ph2 (1, E=O; 2, E=S; 3, E=Se). Compound 1 partially hydrolysed giving [5-t-Bu-1-{(P(O)(O-i-Pr)2}-3-{(P(O)(OH)2}C6H2]P(O)Ph2 (4). The reaction of ArLi with PhPCl2 provided the benzoxaphosphaphosphole [1(P), 3(P)-P(O)(O-i-Pr)OPPh-6-t-Bu-4-P(O)(O-i-Pr)2]C6H2P (5i) as a mixture of the two diastereomers. The oxidation of 5i with elemental sulfur gave the benzoxaphosphaphosphole sulfide [1(P), 3(P)-P(O)(O-i-Pr)OP(S)Ph-6-t-Bu-4-P(O)(O-i-Pr)2]C6H2 (5) as pair of enantiomers P1(R), P3(S)/P1(S), P3(R) of the diastereomer (RS/SR)-5 (5b). The aryldiphenylphosphane 5-t-Bu-1,3-[(P(O)(O-i-Pr)2]2C6H2PPh2 (6) was obtained from the reaction of the corresponding aryldiphenylphosphane sulfide 2 with either sodium hydride, NaH, or disodium iron tetracarbonyl, Na2Fe(CO)4. The oxidation of the aryldiphenylphosphane 6 with elemental iodine and subsequent hydrolysis yielded the aryldiphenyldioxaphosphorane 9-t-Bu-2,6-(OH)-4,4-Ph2-3,5-O2-2,6-P2-4λ5-P-[5.3.1.0]-undeca-1(10),7(11),8-triene (7). Both of its diastereomers, (RR/SS)-7 (7a) and (RS/SR)-7 (7b), were separated as their chloroform and i-propanol solvates, 7a⋅2CHCl3 and 7b⋅i-PrOH, respectively. DFT calculations accompanied the experimental work.
2022-07-12T00:00:00Z
Suppression of liquid-liquid phase separation and aggregation of antibodies by modest pressure application
Fetahaj, Zamira
Jaworek, Michel W.
Oliva, Rosario
Winter, Roland
http://hdl.handle.net/2003/42322
2024-02-12T23:12:45Z
2022-06-27T00:00:00Z
Title: Suppression of liquid-liquid phase separation and aggregation of antibodies by modest pressure application
Authors: Fetahaj, Zamira; Jaworek, Michel W.; Oliva, Rosario; Winter, Roland
Abstract: The high colloidal stability of antibody (immunoglobulin) solutions is important for pharmaceutical applications. Inert cosolutes, excipients, are generally used in therapeutic protein formulations to minimize physical instabilities, such as liquid–liquid phase separation (LLPS), aggregation and precipitation, which are often encountered during manufacturing and storage. Despite their widespread use, a detailed understanding of how excipients modulate the specific protein-protein interactions responsible for these instabilities is still lacking. In this work, we demonstrate the high sensitivity to pressure of globulin condensates as a suitable means to suppress LLPS and subsequent aggregation of concentrated antibody solutions. The addition of excipients has only a minor effect. The high pressure sensitivity observed is due to the fact that these flexible Y-shaped molecules create a considerable amount of void volume in the condensed phase, leading to an overall decrease in the volume of the system upon dissociation of the droplet phase by pressure already at a few tens of to hundred bar. Moreover, we show that immunoglobulin molecules themselves are highly resistant to unfolding under pressure, and can even sustain pressures up to about 6 kbar without conformational changes. This implies that immunoglobulins are resistant to the pressure treatment of foods, such as milk, in high-pressure food-processing technologies, thereby preserving their immunological activity.
2022-06-27T00:00:00Z
Gold(I) NHC catalysts immobilized to amphiphilic block copolymers: a versatile approach to micellar gold catalysis in water
Petersen, Hanne
Ballmann, Monika
Krause, Norbert
Weberskirch, Ralf
http://hdl.handle.net/2003/42321
2024-02-12T23:12:39Z
2022-06-23T00:00:00Z
Title: Gold(I) NHC catalysts immobilized to amphiphilic block copolymers: a versatile approach to micellar gold catalysis in water
Authors: Petersen, Hanne; Ballmann, Monika; Krause, Norbert; Weberskirch, Ralf
Abstract: Fifteen gold(I)-NHC-functionalized amphiphilic block copolymers that differ in the type of linker (ethyl, pentyl, octyl and benzyl) that attaches the gold(I) NHC catalyst to the block copolymer backbone, as well as, the substitution pattern of the NHC ligand (i. e. mesityl, methyl, 2,6-diisopropylphenyl and n-hexyl) were synthesized by a reversible addition and fragmentation transfer (RAFT) polymerization process. Micelle formation of the gold(I) NHC polymers was analyzed by electron microscopy and dynamic light scattering and revealed spherical and rod-like particles from 12 to 96 nm. In the micellar, gold(I) catalyzed cycloisomerization of an allene to the corresponding dihydrofuran, linker flexibility and substitution pattern of the NHC-ligand showed a strong effect on the catalytic activity. Best results were obtained were obtained for gold(I) NHC catalysts bound to the polymer backbone by pentyl linker whereas the rather stiff benzyl linker gave lowest catalyst conversion. Moreover, the polymer catalyst could be recycled in four consecutive runs and gave activities from 35 to 84 % in the fourth run and underscores the importance of fine tuning structural parameters to achieve high conversion under micellar reaction conditions.
2022-06-23T00:00:00Z
The harmonic Maxwell's equations in periodic waveguides
Kirsch, Andreas
Schweizer, Ben
http://hdl.handle.net/2003/42320
2024-02-12T05:10:08Z
2024-01-01T00:00:00Z
Title: The harmonic Maxwell's equations in periodic waveguides
Authors: Kirsch, Andreas; Schweizer, Ben
Abstract: We study Maxwell’s equations with periodic coefficients in a
closed waveguide. A functional analytic approach is used to formulate
and to solve the radiation problem. We furthermore characterize the set
of all bounded solutions to the homogeneous problem. The case of a
compact perturbation of the medium is included, the scattering problem
and the limiting absorption principle are discussed.
2024-01-01T00:00:00Z
Tackling the Challenge of Aging Populations: The Impact of Increasing Life Expectancy and Low Fertility on the Old-Age Dependency Ratio
Pflaumer, Peter
http://hdl.handle.net/2003/42319
2024-02-11T23:12:58Z
2023-09-01T00:00:00Z
Title: Tackling the Challenge of Aging Populations: The Impact of Increasing Life Expectancy and Low Fertility on the Old-Age Dependency Ratio
Authors: Pflaumer, Peter
Abstract: The old-age dependency ratios are indicators of the number of elderly people who are generally economically inactive compared to the number of people of working age. They significantly affect the financial burden of social public pension schemes, making it essential to analyze the influence of mortality on this ratio. In this paper, the Gompertz model is used to investigate the effect of mortality and fertility on the old-age dependency ratio, with a focus on the impact of changes in life expectancy. Elasticity formulas are derived to analyze this effect, and the results indicate that an increase in life expectancy leads to a considerable rise in the old-age dependency ratio.
2023-09-01T00:00:00Z
Refining Mortality Projections at Advanced Ages: Evaluating the Significance of Wittstein's Mortality Law
Pflaumer, Peter
http://hdl.handle.net/2003/42318
2024-02-11T23:12:57Z
2023-11-01T00:00:00Z
Title: Refining Mortality Projections at Advanced Ages: Evaluating the Significance of Wittstein's Mortality Law
Authors: Pflaumer, Peter
Abstract: Age-specific mortality rates for semi-supercentenarians and supercentenarians play a pivotal role in comprehending longevity and population dynamics at advanced ages. In this study, we introduce a modified Wittstein Model, offering an alternative to the conventional S-shaped curve models used in mortality forecasting. The Wittstein Model, originally formulated by Theodor Wittstein, has been adapted to suit contemporary contexts. Utilizing life table data for German women from 2019/2021, we project age-specific mortality rates, construct life tables commencing from age 100, and conduct a sensitivity analysis to assess the impact of model parameters on mortality patterns.
The sensitivity analysis unveils the influence of parameter values on the shape of age-specific mortality rates. This study contributes to research in mortality forecasting, with a specific focus on semi-supercentenarians and supercentenarians, shedding light on an understudied population segment. Accurate projections carry profound implications for public health, healthcare planning, and social policy. Further research should explore the model's applicability in different contexts, providing a deeper understanding of mortality patterns at advanced ages. As the empirical database of centenarians expands, the model is expected to enhance its precision and reliability in forecasting age-specific mortality rates at advanced ages.
2023-11-01T00:00:00Z
Fast Semi-Iterative Finite Element Poisson Solvers for Tensor Core GPUs Based on Prehandling
Ruda, Dustin
Turek, Stefan
Ribbrock, Dirk
http://hdl.handle.net/2003/42317
2024-02-11T23:10:21Z
2024-01-01T00:00:00Z
Title: Fast Semi-Iterative Finite Element Poisson Solvers for Tensor Core GPUs Based on Prehandling
Authors: Ruda, Dustin; Turek, Stefan; Ribbrock, Dirk
Abstract: The impetus for the research presented in this work is provided by recent developments in the field of GPU computing. Nvidia GPUs that are equipped with Tensor Cores, such as the A100 or the latest H100, promise an immense computing power of 156 and 495 TFLOPS, respectively, but only for dense matrix operations carried out in single precision (with even higher rates in half precision), since this serves their actual purpose of accelerating AI training. It is shown that this performance can also be exploited to a large extent in the domain of matrix-based finite element methods for solving PDEs, if specially tailored, hardware-oriented
methods are used. Such methods need to preserve sufficient accuracy, even if single precision is used, and mostly consist of dense matrix operations. A semi-iterative method for solving Poisson’s equation in 2D and 3D based on prehandling, i.e., explicit preconditioning, by means of hierarchical finite elements or generating
systems, that satisfies these requirements, is derived and analyzed.Actual benchmark results on an H100 allow the determination of optimal solver configurations in terms of performance, which ultimately exceeds that of a standard geometric multigrid solver on CPU.
2024-01-01T00:00:00Z
SchuMaS-Kartenset
Klein, Esther Dominique
Czaja, Susanne Julia
Proskawetz, Franziska Sophie
van Ackeren-Miindl, Isabell
Jenk, Alina
http://hdl.handle.net/2003/42218.2
2024-02-11T23:14:24Z
2024-01-01T00:00:00Z
Title: SchuMaS-Kartenset
Authors: Klein, Esther Dominique; Czaja, Susanne Julia; Proskawetz, Franziska Sophie; van Ackeren-Miindl, Isabell; Jenk, Alina
2024-01-01T00:00:00Z
Ultrastrong poly(2‐oxazoline)/poly(acrylic acid) double‐network hydrogels with cartilage‐like mechanical properties
Benitez-Duif, Paola A.
Breisch, Marina
Kurka, Daniel
Edel, Karlina
Gökcay, Semra
Stangier, Dominic
Tillmann, Wolfgang
Hijazi, Montasser
Tiller, Jörg C.
http://hdl.handle.net/2003/42316
2024-02-08T23:13:22Z
2022-08-11T00:00:00Z
Title: Ultrastrong poly(2‐oxazoline)/poly(acrylic acid) double‐network hydrogels with cartilage‐like mechanical properties
Authors: Benitez-Duif, Paola A.; Breisch, Marina; Kurka, Daniel; Edel, Karlina; Gökcay, Semra; Stangier, Dominic; Tillmann, Wolfgang; Hijazi, Montasser; Tiller, Jörg C.
Abstract: The exceptional stiffness and toughness of double-network hydrogels (DNHs) offer the possibility to mimic even complex biomaterials, such as cartilage. The latter has a limited regenerative capacity and thus needs to be substituted with an artificial material. DNHs composed of cross-linked poly(2-oxazoline)s (POx) and poly(acrylic acid) (PAA) are synthesized by free radical polymerization in a two-step process. The resulting DNHs are stabilized by hydrogen bridges even at pH 7.4 (physiological PBS buffer) due to the pKa-shifting effect of POx on PAA. DNHs based on poly(2-methyl-2-oxazoline), which have a water content (WC) of around 66 wt% and are not cytotoxic, show biomechanical properties that match those of cartilage in terms of WC, stiffness, toughness, coefficient of friction, compression in body relevant stress conditions and viscoelastic behavior. This material also has high strength in PBS pH 7.4 and in egg white as synovial liquid substitute. In particular, a compression strength of up to 60 MPa makes this material superior.
2022-08-11T00:00:00Z
Targeting RNA-protein interactions with peptides and small molecule inhibitors
Chang, Jen-Yao
http://hdl.handle.net/2003/42315
2024-02-13T10:37:37Z
2023-01-01T00:00:00Z
Title: Targeting RNA-protein interactions with peptides and small molecule inhibitors
Authors: Chang, Jen-Yao
Abstract: WD repeat domain 5 (WDR5) is a scaffold protein involved in protein-protein or RNA-protein complexes, and most of these complexes play an important role in various epigenetic modulation processes. In particular, some of the long non-coding RNAs (lncRNAs) rely on the formation of the lncRNA-WDR5 complex to exert their epigenetic modulation, such as the upregulation of the lncRNA itself. If an oncogenic lncRNA relies on this pathway to maintain its expression level, it is possible to inhibit its positive feedback loop and thus reduce the expression of the oncogenic lncRNA. Therefore, this thesis focuses on investigating the potential of targeting lncRNA-WDR5 interactions, followed by evaluating the downregulation of lncRNA in cellulo.
Targeting lncRNA-WDR5 interactions could be achieved by designing an inhibitor that targets the same binding pocket on WDR5. Several lncRNA are reported to recognize WDR5-binding motif (WBM) site, as a result, a study of structure-activity relationship of peptide-based inhibitors derivatize from protein-WDR5 interactions to target WBM site are performed. Further optimizations are performed by tailor-design macrocycle structure to facilitate peptides adopt the binding conformation and indeed the binding affinity is improved. The ability of macrocycle to disrupt lncRNA-protein interaction is verified by competitive in vitro RNA immunoprecipitation (iv-RIP).
Cellular experiments are performed to determine whether targeting lncRNA-WDR5 interactions leads to downregulation of the lncRNA itself. Several strategies show their ability to enhance cell uptake of macrocycles. Finally, two molecules show that targeting lncRNA-WDR5 complexes can lead to reduction of the lncRNA itself and that different lncRNA have different sensitivity to the treatment.
2023-01-01T00:00:00Z
A bacterial surface display platform for the discovery of cytosine modification readers from cDNA libraries
Schiller, Damian
http://hdl.handle.net/2003/42314
2024-02-07T23:12:34Z
2023-01-01T00:00:00Z
Title: A bacterial surface display platform for the discovery of cytosine modification readers from cDNA libraries
Authors: Schiller, Damian
Abstract: 5-methylcytosine (5mC) occurs in palindromic cytosine guanine dyads (CpGs) of mammalian genomes and is a key element of epigenetic transcription regulation. Central to these regulatory functions is the ability of cytosine modifications to modulate the interaction of chromatin proteins with DNA. In this context, reader proteins are known to selectively recognize the cytosine modification. Interactome profiling studies based on pulldowns of nuclear extracts in combination with mass spectrometry-based (MS) proteomics have been the main approach to discovering readers of 5mC. However, this approach may miss important (anti-)readers due to the competition of proteins for the probe and low expression levels. Moreover, direct readers cannot be distinguished from indirect binders of protein complexes.
In the scope of this thesis, a bacterial surface display system for discovering novel reader candidates from human cDNA was established. In detail, our approach offers screenings of cDNA-encoded protein libraries independent of their endogenous expression levels and without competition with other proteins. It further allows for rapid iterative FACS selections with defined, fluorescently labeled on- and off-target DNA probes. Furthermore, the system benefits from the fast protein expression machinery and growth of bacterial cells. We created surface display libraries of full-length and fragmented coding sequences (CDS) from human cDNA and demonstrated the compatibility of the Intimin surface display platform with displaying human proteins and protein fragments. Moving on, we proved the functionality of our selection system by enriching known 5mC reader candidates from a display library of human thyroid cDNA. In addition, we were able to identify novel reader candidates. Therefore, this study offers a promising tool to complement existing efforts in discovering 5mC reader candidates. Furthermore, the tool bears the potential to be extended to the oxidized derivates of 5mC and their combinations in CpGs, which have not been investigated so far.
2023-01-01T00:00:00Z
Biophysikalische Einblicke in heterogene Modellbiomembranen, G-Quadruplexe und Eigenschaften der Flüssig-Flüssig-Phasentrennung von Peptiden
Manisegaran, Magiliny
http://hdl.handle.net/2003/42313
2024-02-07T23:12:52Z
2023-01-01T00:00:00Z
Title: Biophysikalische Einblicke in heterogene Modellbiomembranen, G-Quadruplexe und Eigenschaften der Flüssig-Flüssig-Phasentrennung von Peptiden
Authors: Manisegaran, Magiliny
Abstract: Die biophysikalische Chemie ist eine Forschungsdisziplin, die Antworten auf medizinische und biochemische Fragen liefert. Modellsysteme biologischer Makromoleküle werden verwendet, um ein umfassendes Verständnis biologischer Prozesse zu fördern. Dies kann Ansätze für die Diagnose und Behandlung von Krankheiten liefern. In dieser Arbeit werden physikalisch-chemische Einflüsse auf heterogene Modellbiomembranen, G-Quadruplexe und die Eigenschaften der Flüssig-Flüssig-Phasentrennung von Peptiden untersucht: Das erste Thema in der Arbeit ist der Einfluss des Immunregulators 25-Hydroxycholesterol auf das thermotrope und barotrope Phasenverhalten und die Struktur von Modellbiomembranen, das zweite die Bindungseigenschaften von Berberin an den G-Quadruplex der RG-1-Sequenz der RNA des SARS-CoV-2-Virus unter verschiedenen Lösungsbedingungen und das letzte Thema behandelt die Wechselwirkung zwischen zwei Phasenkoexistenzen verschiedener biologischer Systeme: Heterogene Membransysteme zeigen eine Phasenkoexistenz, die als Kompartimentierung der Zellmembran verstanden werden kann. Proteine und Nukleinsäuren können die Eigenschaft der Flüssig-Flüssig-Phasentrennung aufweisen.
2023-01-01T00:00:00Z