@inproceedings{61149, abstract = {{The use of continuous fiber-reinforced thermoplastics (FRTP) in automotive industry increases due to their excellent material properties and possibility of rapid processing. The scale spanning heterogeneity of their material structure and its influence on the material behavior, however, presents significant challenges for most joining technologies, such as self-piercing riveting (SPR). During mechanical joining, the material structure is significantly altered within and around the joining zone, heavily influencing the material behavior. A comprehensive understanding of the underlying phenomena of material alteration during the SPR process is essential as basis for validating numerical simulations. This study examines the material structure at ten stages of a step-setting test of SPR with two FRTP sheets with glass-fiber reinforcement. Utilizing X-ray computed tomography (CT), the damage phenomena within different areas of the setting test are analyzed three-dimensionally and key parameters are quantified. Dominating phenomena during the penetration of the rivet into the laminate are fiber failure (FF), interfiber failure (IFF) and fiber bending, while delamination, fiber kinking and roving splitting are also observed. At the final stages, the bottom layers of the second sheet collapse and form a bulge into the cavity of the die.}}, author = {{Dargel, Alrik and Gröger, Benjamin and Schlichter, Malte Christian and Gerritzen, Johannes and Köhler, Daniel and Meschut, Gerson and Gude, Maik and Kupfer, Robert}}, booktitle = {{Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)}}, editor = {{Gomes, J.F. Silva and Meguid, Shaker A.}}, isbn = {{9789727523238}}, keywords = {{self-piercing riveting, computed tomography, thermoplastic composites, process-structure-interaction}}, location = {{Porto}}, publisher = {{FEUP}}, title = {{{LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION}}}, doi = {{10.24840/978-972-752-323-8}}, year = {{2025}}, } @inproceedings{54513, abstract = {{Learning argumentative writing is challenging. Besides writing fundamentals such as syntax and grammar, learners must select and arrange argument components meaningfully to create high-quality essays. To support argumentative writing computationally, one step is to mine the argumentative structure. When combined with automatic essay scoring, interactions of the argumentative structure and quality scores can be exploited for comprehensive writing support. Although studies have shown the usefulness of using information about the argumentative structure for essay scoring, no argument mining corpus with ground-truth essay quality annotations has been published yet. Moreover, none of the existing corpora contain essays written by school students specifically. To fill this research gap, we present a German corpus of 1,320 essays from school students of two age groups. Each essay has been manually annotated for argumentative structure and quality on multiple levels of granularity. We propose baseline approaches to argument mining and essay scoring, and we analyze interactions between both tasks, thereby laying the ground for quality-oriented argumentative writing support.}}, author = {{Stahl, Maja and Michel, Nadine and Kilsbach, Sebastian and Schmidtke, Julian and Rezat, Sara and Wachsmuth, Henning}}, keywords = {{Annotation, Corpus, Argumentative Structure}}, title = {{{A School Student Essay Corpus for Analyzing Interactions of Argumentative Structure and Quality}}}, doi = {{10.48550/arXiv.2404.02529}}, year = {{2024}}, } @article{46637, author = {{Gonchikzhapov, Munko and Kasper, Tina}}, issn = {{2666-352X}}, journal = {{Applications in Energy and Combustion Science}}, keywords = {{Nanoparticle synthesis, Flame spray pyrolysis, SpraySyn burner, Flame structure, Species distribution, Temperature distribution}}, publisher = {{Elsevier BV}}, title = {{{Thermal and chemical structure of ethanol and 2-ethylhexanoic acid/ethanol SpraySyn flames}}}, doi = {{10.1016/j.jaecs.2023.100174}}, volume = {{15}}, year = {{2023}}, } @inproceedings{20159, abstract = {{Let G = (V,E) be an undirected graph on n vertices with non-negative capacities on its edges. The mincut sensitivity problem for the insertion of an edge is defined as follows. Build a compact data structure for G and a given set S ⊆ V of vertices that, on receiving any edge (x,y) ∈ S×S of positive capacity as query input, can efficiently report the set of all pairs from S× S whose mincut value increases upon insertion of the edge (x,y) to G. The only result that exists for this problem is for a single pair of vertices (Picard and Queyranne, Mathematical Programming Study, 13 (1980), 8-16). We present the following results for the single source and the all-pairs versions of this problem. 1) Single source: Given any designated source vertex s, there exists a data structure of size 𝒪(|S|) that can output all those vertices from S whose mincut value to s increases upon insertion of any given edge. The time taken by the data structure to answer any query is 𝒪(|S|). 2) All-pairs: There exists an 𝒪(|S|²) size data structure that can output all those pairs of vertices from S× S whose mincut value gets increased upon insertion of any given edge. The time taken by the data structure to answer any query is 𝒪(k), where k is the number of pairs of vertices whose mincut increases. For both these versions, we also address the problem of reporting the values of the mincuts upon insertion of any given edge. To derive our results, we use interesting insights into the nearest and the farthest mincuts for a pair of vertices. In addition, a crucial result, that we establish and use in our data structures, is that there exists a directed acyclic graph of 𝒪(n) size that compactly stores the farthest mincuts from all vertices of V to a designated vertex s in the graph. We believe that this result is of independent interest, especially, because it also complements a previously existing result by Hariharan et al. (STOC 2007) that the nearest mincuts from all vertices of V to s is a laminar family, and hence, can be stored compactly in a tree of 𝒪(n) size.}}, author = {{Baswana, Surender and Gupta, Shiv and Knollmann, Till}}, booktitle = {{28th Annual European Symposium on Algorithms (ESA 2020)}}, editor = {{Grandoni, Fabrizio and Herman, Grzegorz and Sanders, Peter}}, isbn = {{978-3-95977-162-7}}, issn = {{1868-8969}}, keywords = {{Mincut, Sensitivity, Data Structure}}, pages = {{12:1--12:14}}, publisher = {{Schloss Dagstuhl -- Leibniz-Zentrum für Informatik}}, title = {{{Mincut Sensitivity Data Structures for the Insertion of an Edge}}}, doi = {{10.4230/LIPIcs.ESA.2020.12}}, volume = {{173}}, year = {{2020}}, } @article{64018, abstract = {{CO oxidation is an extensively studied reaction in heterogeneous catalysis due to its seeming simplicity and its great importance for emission control. However, the role of particle size and more specifically structure sensitivity in this reaction is still controversial. In the present study, colloidal “surfactant-free” Pt nanoparticles (NPs) in a size regime of 1–4 nm with narrow size distribution and control over particle size were synthesized and subsequently supported on Al2O3 to prepare model catalysts. CO oxidation was performed using Pt NPs catalysts with particles sizes of 1, 2, 3, and 4 nm at different reaction temperatures. It is shown that the reaction exhibits a particle size effect that depends strongly on the reaction conditions. At 170 °C, the reaction seems to proceed within the same kinetic regime for all particle sizes, but the surface normalized activity depends strongly on the particle size, with maximum activity for nanoparticles 2 nm in diameter. A temperature increase to 200 °C leads to a change of the kinetic regime that depends on the particle size. For Pt NPs 1 nm in diameter a reaction order of 1 for O2 was observed, indicating that O2 adsorbs molecularly and dissociates in a following step, which represents the generally accepted mechanism on Pt surfaces. The reaction order of −1 for CO demonstrates that the surface is saturated with CO under reaction conditions. With increasing particle size, the reaction orders of O2 and CO change. For particles 2 nm in size, an increase in temperature also results in reaction orders of 1 for O2 and −1 for CO; NPs of 3 and 4 nm, even at higher temperatures, show no clear kinetic behavior that can be explained by a single reaction mechanism. Instead, the Boudouard reaction between two adjacent adsorbed CO molecules was identified as an important additional reaction pathway that occurs preferentially on large particles and causes more complex kinetics.}}, author = {{Neumann, Sarah and Gutmann, Torsten and Buntkowsky, Gerd and Paul, Stephen and Thiele, Greg and Sievers, Heiko and Bäumer, Marcus and Kunz, Sebastian}}, journal = {{Journal of Catalysis}}, keywords = {{Solid state NMR, “Surfactant-free” platinum nanoparticles, CO oxidation, Particle size effect, Structure sensitivity}}, pages = {{662–672}}, title = {{{Insights into the reaction mechanism and particle size effects of CO oxidation over supported Pt nanoparticle catalysts}}}, doi = {{10.1016/j.jcat.2019.07.049}}, volume = {{377}}, year = {{2019}}, } @article{2331, abstract = {{A user generally writes software requirements in ambiguous and incomplete form by using natural language; therefore, a software developer may have difficulty in clearly understanding what the meanings are. To solve this problem with automation, we propose a classifier for semantic annotation with manually pre-defined semantic categories. To improve our classifier, we carefully designed syntactic features extracted by constituency and dependency parsers. Even with a small dataset and a large number of classes, our proposed classifier records an accuracy of 0.75, which outperforms the previous model, REaCT.}}, author = {{Kim, Yeongsu and Lee, Seungwoo and Dollmann, Markus and Geierhos, Michaela}}, issn = {{2207-6360}}, journal = {{International Journal of Advanced Science and Technology}}, keywords = {{Software Engineering, Natural Language Processing, Semantic Annotation, Machine Learning, Feature Engineering, Syntactic Structure}}, pages = {{123--136}}, publisher = {{SERSC Australia}}, title = {{{Improving Classifiers for Semantic Annotation of Software Requirements with Elaborate Syntactic Structure}}}, doi = {{10.14257/ijast.2018.112.12}}, volume = {{112}}, year = {{2018}}, } @inproceedings{4411, abstract = {{While a lot of research in distributed computing has covered solutions for self-stabilizing computing and topologies, there is far less work on self-stabilization for distributed data structures. Considering crashing peers in peer-to-peer networks, it should not be taken for granted that a distributed data structure remains intact. In this work, we present a self-stabilizing protocol for a distributed data structure called the hashed Patricia Trie (Kniesburges and Scheideler WALCOM'11) that enables efficient prefix search on a set of keys. The data structure has a wide area of applications including string matching problems while offering low overhead and efficient operations when embedded on top of a distributed hash table. Especially, longest prefix matching for $x$ can be done in $\mathcal{O}(\log |x|)$ hash table read accesses. We show how to maintain the structure in a self-stabilizing way. Our protocol assures low overhead in a legal state and a total (asymptotically optimal) memory demand of $\Theta(d)$ bits, where $d$ is the number of bits needed for storing all keys.}}, author = {{Knollmann, Till and Scheideler, Christian}}, booktitle = {{Proceedings of the 20th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)}}, editor = {{Izumi, Taisuke and Kuznetsov, Petr}}, keywords = {{Self-Stabilizing, Prefix Search, Distributed Data Structure}}, location = {{Tokyo}}, publisher = {{Springer, Cham}}, title = {{{A Self-Stabilizing Hashed Patricia Trie}}}, doi = {{10.1007/978-3-030-03232-6_1}}, volume = {{11201}}, year = {{2018}}, } @article{13186, abstract = {{Ligands DMEG6etqu, TMG6etqu, DMEG6buqu, and TMG6buqu were developed on the basis of guanidine quinoline (GUAqu) ligands 1,3-dimethyl-N-(quinolin-8-yl)imidazolidin-2-imine (DMEGqu) and 1,1,3,3-tetramethyl-2-(quinolin-8-yl)guanidine (TMGqu). These ligands feature an alkyl substituent at the C6 of the quinoline backbone. The synthetic strategy developed here enables inexpensive syntheses of any kind of C6-substituted GUAqu ligands. On one hand, the alkylation increases the solubility of corresponding copper complexes in apolar atom transfer radical polymerization (ATRP) monomers like styrene. On the other hand, it has a significant electronic influence and thus an effect on the donor properties of the new ligands. Seven CuI and CuII complexes of DMEG6etqu and TMG6etqu have been crystallized and were studied with regard to their structural and electrochemical properties. CuI and CuII complexes of DMEG6buqu and TMG6buqu turned out to be perfectly soluble in pure styrene even at room temperature, which makes them excellent catalysts in the ATRP of apolar monomers. The key characteristics of the ATRP equilibrium, KATRP and kact, were determined for the new complexes. In addition, we used our recently developed DFT methodology, NBO analysis, and isodesmic reactions to predict the influence of the introduced alkyl substituents. It turned out that high conformational freedom in the complex structures leads to a significant uncertainty in prediction of the thermodynamic properties.}}, author = {{Rösener, Thomas and Hoffmann, Alexander and Herres-Pawlis, Sonja}}, journal = {{European Journal of Inorganic Chemistry}}, keywords = {{Copper, Polymerization, Redox chemistry, Structure elucidation, Ligand effects}}, number = {{27}}, pages = {{3164--3175}}, title = {{{Next Generation of Guanidine Quinoline Copper Complexes for Highly Controlled ATRP: Influence of Backbone Substitution on Redox Chemistry and Solubility}}}, doi = {{10.1002/ejic.201800511}}, volume = {{2018}}, year = {{2018}}, } @article{64057, abstract = {{Self-assembly of nanoparticles (NPs) forming unique structures has been investigated extensively over the past few years. However, many self-assembled structures by NPs are irreversible, because they are generally constructed using their suspensions. It is still challenging for NPs to reversibly self-assemble in dry state, let alone of polymeric NPs with general sizes of hundreds of nm. Herein, this study reports a new reversible self-assembly phenomenon of NPs in dry state, forming thermoreversible strip-like supermolecular structures. These novel NPs of around 150 nm are perfluorinated surface-undecenoated cellulose nanoparticles (FSU-CNPs) with a core-coronas structure. The thermoreversible self-assembled structure is formed after drying in the air at the interface between FSU-CNP films and Teflon substrates. Remarkably, the formation and dissociation of this assembled structure are accompanied by a reversible conversion of the surface hydrophobicity, film transparency, and anisotropic properties. These findings show novel feasibility of reversible self-assembly of NPs in dry state, and thereby expand our knowledge of self-assembly phenomenon.}}, author = {{Wang, Yonggui and Groszewicz, Pedro B. and Rosenfeldt, Sabine and Schmidt, Hendrik and Volkert, Cynthia A. and Vana, Philipp and Gutmann, Torsten and Buntkowsky, Gerd and Zhang, Kai}}, journal = {{Advanced Materials}}, keywords = {{nanoparticles, self-assembly, cellulose, core-coronas structure, thermoreversible}}, pages = {{1702473}}, title = {{{Thermoreversible Self-Assembly of Perfluorinated Core-Coronas Cellulose-Nanoparticles in Dry State}}}, doi = {{10.1002/adma.201702473}}, year = {{2017}}, } @inproceedings{191, abstract = {{One purpose of requirement refinement is that higher-level requirements have to be translated to something usable by developers. Since customer requirements are often written in natural language by end users, they lack precision, completeness and consistency. Although user stories are often used in the requirement elicitation process in order to describe the possibilities how to interact with the software, there is always something unspoken. Here, we present techniques how to automatically refine vague software descriptions. Thus, we can bridge the gap by first revising natural language utterances from higher-level to more detailed customer requirements, before functionality matters. We therefore focus on the resolution of semantically incomplete user-generated sentences (i.e. non-instantiated arguments of predicates) and provide ontology-based gap-filling suggestions how to complete unverbalized information in the user’s demand.}}, author = {{Geierhos, Michaela and Bäumer, Frederik Simon}}, booktitle = {{Proceedings of the 21st International Conference on Applications of Natural Language to Information Systems (NLDB)}}, editor = {{Métais, Elisabeth and Meziane, Farid and Saraee, Mohamad and Sugumaran, Vijayan and Vadera, Sunil }}, isbn = {{978-3-319-41753-0}}, keywords = {{Requirement refinement, Concept expansion, Ontology-based instantiation of predicate-argument structure}}, location = {{Salford, UK}}, pages = {{37--47}}, publisher = {{Springer}}, title = {{{How to Complete Customer Requirements: Using Concept Expansion for Requirement Refinement}}}, doi = {{10.1007/978-3-319-41754-7_4}}, volume = {{9612}}, year = {{2016}}, } @article{34439, abstract = {{A method for the reconstruction of turned shaft surfaces with a (fractal) Weierstrass–Mandelbrot-function (WMF) is presented. The WMF is modified to allow to freely choose a phase-shift for every frequency. The reconstruction is based on distinct profiles in axial and tangential direction and the statistical distribution of low-wavelength portions of the surface is taken into account by adding t-distributed random deviations to the surface. The work is validated by reconstructing measured shaft surfaces with different manufacturing parameters, which shows good accuracy for periodic surfaces. This method allows for a characterization of surfaces with a limited number of parameters and can be used to store the characteristics of measured surfaces with a reduced amount of data compared to a point-cloud surface.}}, author = {{Thielen, Stefan and Magyar, Balázs and Piros, Attila}}, issn = {{0301-679X}}, journal = {{Tribology International}}, keywords = {{Roughness, Structure, Fractal, Machining}}, pages = {{349--357}}, title = {{{Reconstruction of three-dimensional turned shaft surfaces with fractal functions}}}, doi = {{https://doi.org/10.1016/j.triboint.2015.11.028}}, volume = {{95}}, year = {{2016}}, } @article{5195, abstract = {{This article analyses 336 German venture capital transactions from 1990 to 2005 and seeks to determine why selected financial securities differ across deals. We find that a broad array of financial instruments is used, covering straight equity, mezzanine and debt‐like securities. Based on the chosen financial securities’ upside potential and downside protection characteristics, we provide an explanation for the differing use of these securities. Our results show that investors’ deal experience, adverse selection risks and economic prospects in the public equity market influence the selection of financial securities. }}, author = {{Hartmann-Wendels, Thomas and Keienburg, Georg and Sievers, Sönke}}, journal = {{European Financial Management (VHB-JOURQUAL 4 Ranking B)}}, keywords = {{venture capital, capital structure, contract theory, deal experience}}, number = {{3}}, pages = {{464--499}}, publisher = {{Wiley Online Library}}, title = {{{Adverse selection, investor experience and security choice in venture capital finance: evidence from Germany}}}, doi = {{10.1111/j.1468-036X.2010.00568.x}}, volume = {{17}}, year = {{2011}}, } @article{4406, abstract = {{Using aggregate balance sheet data from banks across the EU-25 over the period from 1997 to 2005 we provide empirical evidence that national banking market concentration has a negative impact on European banks’ financial soundness as measured by the Z-score technique while controlling for macroeconomic, bank-specific, regulatory, and institutional factors. Furthermore, our analysis reveals that Eastern European banking markets exhibiting a lower level of competitive pressure, fewer diversification opportunities and a higher fraction of government-owned banks are more prone to financial fragility whereas capital regulations have supported financial stability across the entire European Union.}}, author = {{Uhde, André and Heimeshoff, Ulrich}}, journal = {{Journal of Banking & Finance}}, keywords = {{Market structure, Financial stability, Banking regulation}}, number = {{7}}, pages = {{1299--1311}}, title = {{{Consolidation in banking and financial stability in Europe: Empirical evidence}}}, doi = {{https://doi.org/10.1016/j.jbankfin.2009.01.006}}, volume = {{33}}, year = {{2009}}, } @inproceedings{11733, abstract = {{Current navigation systems like GPS (Global Positioning System) and its Russian counterpart GLONASS (Global Navigation Satellite System) only evaluate the direct signal path. The receivers treat the reflected paths also reaching the receiver antenna as disturbance which has to be suppressed. Multipath affects the tracking accuracy by resulting in a degeneration of the S-curve of the DLL (delay locked loop). Nowadays the future European systems GALILEO and GPSIIF/III with two new signals are on the way to the market and it is time to think about new receiver structures. Therefore we investigated if it is possible to use multipath for navigation constructively.}}, author = {{Bischoff, Renke and Haeb-Umbach, Reinhold and Schulz, Wolfgang and Heinrichs, Guenther}}, booktitle = {{IEEE 55th Vehicular Technology Conference (VTC 2002 Spring)}}, keywords = {{combined GALILEO/UMTS receiver, delay locked loop, delay lock loops, DLL, Global Positioning System, GLONASS, GPS, GPSIIF/III, mobile satellite communication, multipath channels, multipath receiver structure, radio receivers, RAKE receiver, S-curve}}, pages = {{1844--1848 vol.4}}, title = {{{Employment of a multipath receiver structure in a combined GALILEO/UMTS receiver}}}, doi = {{10.1109/VTC.2002.1002940}}, volume = {{4}}, year = {{2002}}, } @inbook{34447, abstract = {{The Object Constraint Language (OCL) was introduced to support the specification of constraints for UML diagrams and is mainly used to formulate invariants and operation pre- and postconditions. Though OCL is also applied in behavioral diagrams, e.g., as guards for state transitions, it is currently not possible to specify constraints concerning the dynamic behavior and timing properties of such diagrams. This article discusses OCL’s application for the dynamic behavior of UML Statechart diagrams and presents an OCL extension for specification of state-oriented time-bounded constraints.We introduce operations to extract state configurations from diagrams and define additional predicates over states and state configurations. The semantics of our OCL extension is given by employing time-bounded Computational Tree Logic (CTL) formulae. An example of a flexible manufacturing system with automated guided vehicles demonstrates the application of our extension.}}, author = {{Flake, Stephan and Müller, Wolfgang}}, booktitle = {{Advances in Object Modelling with the OCL}}, editor = {{Clark, T. and Warmer, J.}}, isbn = {{978-3-540-45669-8}}, keywords = {{Model Check Temporal Logic Object Constraint Language Execution Path Kripke Structure}}, pages = {{150 -- 171}}, publisher = {{Springer-Verlag}}, title = {{{An OCL Extension for Real-Time Constraints}}}, doi = {{10.1007/3-540-45669-4_8}}, year = {{2002}}, }