@inproceedings{10258, abstract = {{Für die Zerstäubung hochviskoser Flüssigkeiten werden neben Düsenzerstäubern vor allem UltraschallStehwellenzerstäuber angewendet [1]. Diese ermöglichen ohne weitere Maßnahmen zwar keine gerichtete Zerstäubung, benötigen jedoch im Gegensatz zu Düsenzerstäubern keine hohen Drücke und haben keine hohen Austrittsgeschwindigkeiten. Zur Erzeugung der Ultraschallwellen werden typischerweise piezoelektrische, mit Bolzen verschraubte LangevinWandler verwendet [1-4], die eine starke Schallabstrahlung bei einer elektrischen Eingangsleistung von bis zu einigen Kilowatt erzeugen können. Wie bei jedem anderen schwingenden System emittiert der Ultraschallwandler zunächst eine Wanderwelle. Mit einem Reflektor, der gegenüber der Sonotrode angeordnet ist, wird eine stehende Welle erzeugt. Im Resonanzabstand zwischen Reflektor und Wandler werden abgestrahlte und reflektierte Wellen so überlagert, dass höhere Schalldruckamplituden erzielt werden. Ein einfacher Ansatz zur Maximierung des Schallpegels im Stehwellenfeld ist die Erhöhung der Schwingungsamplituden des Wandlers, die jedoch zu Schäden oder zumindest zu einer Verringerung der Lebensdauer führen kann. Hohe Schalldrücke werden auch bei geringen Abständen zwischen Wandler und Reflektor erreicht. Das Volumen des Schallfeldes ist in diesem Fall jedoch für die meisten Prozesse zu klein. Ein weiterer Ansatz ist die Verwendung zweier entgegengesetzt angeordneter Wandler [5]. In diesem Fall erfordert jedoch die Erzeugung einer stehenden Welle eine genaue Abstimmung von Frequenz und Phase beider Wandler, was eine komplexe Steuerung erfordert. Ebenso ist es möglich, geometrische Randbedingungen des Stehwellensystems zu optimieren, sodass es zu optimaler Interferenz der Wellen kommt. Im Folgenden wird der Anschaulichkeit halber vereinfachend angenommen, dass der Wandler an seiner Sonotrodenoberfläche einzelne Schallstrahlen aussendet, die in Nähe des Wandlers nahezu parallel verlaufen und sich mit zunehmender Entfernung vom Wandler auffächern. Ein einfaches Stehwellensystem, bestehend aus ebener Sonotrode und ebenem Reflektor, erzeugt bei kleinem Abstand zwischen Sonotrode und Reflektor sehr hohe Schallpegel, da nahezu sämtliche ausgesandten Schallstrahlen in Richtung der Sonotrode reflektiert werden positive Interferenz entsteht. Erhöht man jedoch den Abstand zwischen Sonotrode und Reflektor, so nehmen die Verluste durch Schallstrahlen, die den Prozessraum verlassen, zu. Wie Abbildung 1 gezeigt, werden nur Schallstrahlen, die in etwa parallel zur Rotationsachse verlaufen, zum Wandler zurück reflektiert und tragen zum Stehwellenfeld bei. Die Strahlen haben zudem abhängig vom Abstrahlwinkel unterschiedliche Weglängen. Die Stehwellenbedingung ist demnach nur für Strahlen in der Nähe der Rotationsachse exakt erfüllt. Um dies zu vermeiden, müssen die Geometrien von Wandler und Reflektor optimiert werden. In den folgenden Abschnitten wird zunächst ein Optimierungsansatz vorgestellt. Mithilfe eines FiniteElemente-Modells werden die Auswirkungen einer optimierten Geometrie auf den maximalen Schalldruckpegel untersucht. Ergebnisse werden durch Messungen an einem experimentellen Aufbau eines Stehwellensystems validiert. Es wird gezeigt, wie sich die Optimierung der geometrischen Randbedingungen auf die Zerstäubung hochviskoser Flüssigkeiten auswirkt.}}, author = {{Dunst, Paul and Hemsel, Tobias and Bornmann, Peter and Littmann, Walter and Sextro, Walter}}, booktitle = {{DAGA 2019}}, location = {{Rostock}}, title = {{{Modellbasierte und experimentelle Charakterisierung von intensiven Ultraschall-Stehwellenfeldern für die Zerstäubung hochviskoser Flüssigkeiten}}}, year = {{2019}}, } @misc{10271, author = {{N., N.}}, publisher = {{Universität Paderborn}}, title = {{{Implementation and Evaluation of Authenticated Data Structures Using Intel SGX Enclaves}}}, year = {{2019}}, } @misc{10277, author = {{Althaus, Steffen}}, title = {{{Optimizing Sales Channel Performance with Digital Experiments in the Crafting Industry}}}, year = {{2019}}, } @article{10279, abstract = {{Are cryptocurrency traders driven by a desire to invest in a new asset class to diversify their portfolio or are they merely seeking to increase their levels of risk? To answer this question, we use individual-level brokerage data and study their behavior in stock trading around the time they engage in their first cryptocurrency trade. We find that when engaging in cryptocurrency trading investors simultaneously increase their risk-seeking behavior in stock trading as they increase their trading intensity and use of leverage. The increase in risk-seeking in stocks is particularly pronounced when volatility in cryptocurrency returns is low, suggesting that their overall behavior is driven by excitement-seeking. }}, author = {{Pelster, Matthias and Breitmayer, Bastian and Hasso, Tim}}, issn = {{0165-1765}}, journal = {{Economics Letters}}, keywords = {{cryptocurrencies, bitcoin, investor, risk-seeking}}, pages = {{98--100}}, title = {{{Are cryptocurrency traders pioneers or just risk-seekers? evidence from brokerage accounts}}}, doi = {{10.1016/j.econlet.2019.06.013}}, volume = {{182}}, year = {{2019}}, } @inproceedings{10281, abstract = {{Competing firms tend to select similar locations for their stores. This phenomenon, called the principle of minimum differentiation, was captured by Hotelling with a landmark model of spatial competition but is still the object of an ongoing scientific debate. Although consistently observed in practice, many more realistic variants of Hotelling's model fail to support minimum differentiation or do not have pure equilibria at all. In particular, it was recently proven for a generalized model which incorporates negative network externalities and which contains Hotelling's model and classical selfish load balancing as special cases, that the unique equilibria do not adhere to minimum differentiation. Furthermore, it was shown that for a significant parameter range pure equilibria do not exist. We derive a sharp contrast to these previous results by investigating Hotelling's model with negative network externalities from an entirely new angle: approximate pure subgame perfect equilibria. This approach allows us to prove analytically and via agent-based simulations that approximate equilibria having good approximation guarantees and that adhere to minimum differentiation exist for the full parameter range of the model. Moreover, we show that the obtained approximate equilibria have high social welfare.}}, author = {{Feldotto, Matthias and Lenzner, Pascal and Molitor, Louise and Skopalik, Alexander}}, booktitle = {{Proceedings of the 18th International Conference on Autonomous Agents and MultiAgent Systems}}, location = {{Montreal QC, Canada}}, pages = {{1949----1951}}, publisher = {{International Foundation for Autonomous Agents and Multiagent Systems}}, title = {{{ From Hotelling to Load Balancing: Approximation and the Principle of Minimum Differentiation}}}, year = {{2019}}, } @article{10282, author = {{Lin, Zemeng and Huang, Lingling and Zhao, Ruizhe and Wei, Qunshuo and Zentgraf, Thomas and Wang, Yongtian and Li, Xiaowei}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{13}}, pages = {{18740--18750}}, title = {{{Dynamic control of mode modulation and spatial multiplexing using hybrid metasurfaces}}}, doi = {{10.1364/oe.27.018740}}, volume = {{27}}, year = {{2019}}, } @inproceedings{10284, abstract = {{We study text reuse related to Wikipedia at scale by compiling the first corpus of text reuse cases within Wikipedia as well as without (i.e., reuse of Wikipedia text in a sample of the Common Crawl). To discover reuse beyond verbatim copy and paste, we employ state-of-the-art text reuse detection technology, scaling it for the first time to process the entire Wikipedia as part of a distributed retrieval pipeline. We further report on a pilot analysis of the 100 million reuse cases inside, and the 1.6 million reuse cases outside Wikipedia that we discovered. Text reuse inside Wikipedia gives rise to new tasks such as article template induction, fixing quality flaws, or complementing Wikipedia's ontology. Text reuse outside Wikipedia yields a tangible metric for the emerging field of quantifying Wikipedia's influence on the web. To foster future research into these tasks, and for reproducibility's sake, the Wikipedia text reuse corpus and the retrieval pipeline are made freely available.}}, author = {{Alshomary, Milad and Völske, Michael and Licht, Tristan and Wachsmuth, Henning and Stein, Benno and Hagen, Matthias and Potthast, Martin}}, booktitle = {{Advances in Information Retrieval}}, editor = {{Azzopardi, Leif and Stein, Benno and Fuhr, Norbert and Mayr, Philipp and Hauff, Claudia and Hiemstra, Djoerd}}, isbn = {{978-3-030-15712-8}}, pages = {{747--754}}, publisher = {{Springer International Publishing}}, title = {{{Wikipedia Text Reuse: Within and Without}}}, year = {{2019}}, } @phdthesis{10290, author = {{Gutt, Dominik}}, title = {{{Essays on Drivers and Economic Outcomes of Online-Reviews}}}, doi = {{10.17619/UNIPB/1-688}}, year = {{2019}}, } @misc{10306, author = {{Porzenheim, Laurens Alexander}}, title = {{{Post-Quantum Secure Group Signatures}}}, year = {{2019}}, } @article{10325, author = {{Peuster, Manuel and Marchetti, Michael and García de Blas, Gerardo and Karl, Holger}}, issn = {{1687-1499}}, journal = {{EURASIP Journal on Wireless Communications and Networking}}, publisher = {{Springer}}, title = {{{Automated testing of NFV orchestrators against carrier-grade multi-PoP scenarios using emulation-based smoke testing}}}, doi = {{10.1186/s13638-019-1493-2}}, year = {{2019}}, } @techreport{10332, abstract = {{We analyze the incentives for retail bundling and the welfare effects of retail bundling in a decentralized distribution channel with two retailers and two monopolistic manufacturers. One manufacturer exclusively sells his good to one retailer, whereas the other manufacturer sells his good to both retailers. Thus, one retailer is a monopolist for one product but competes with the other retailer in the second product market. The two-product retailer has the option to bundle his goods or to sell them separately. We find that bundling aggravates the double marginalization problem for the bundling retailer. Nevertheless, when the retailers compete in prices, bundling can be more profitable than separate selling for the retailer as bundling softens the retail competition. The ultimate outcome depends on the manufacturers’ marginal costs. Given retail quantity competition, however, bundling is in no case the retailer’s best strategy. Furthermore, we show that profitable bundling reduces consumer and producer surplus in the equilibrium.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{retail bundling, leverage theory, double marginalization}}, publisher = {{CIE Working Paper Series}}, title = {{{Bundling in a Distribution Channel with Retail Competition}}}, year = {{2019}}, } @misc{10344, author = {{Pukrop, Simon}}, publisher = {{Universität Paderborn}}, title = {{{Scheduling Algorithms for Multi-Operation Jobs with Setups on a Single Machine}}}, year = {{2019}}, } @inproceedings{13554, abstract = {{We propose a novel personal reputation system for cross-platform reputation. We observe that, in certain usage scenarios, e.g. crowd work, the rater anonymity property typically imposed on reputation systems is not necessary. Instead, we propose a relaxed notion of rater anonymity that is more applicable in the crowd work scenario. This allows us to construct a secure personal reputation system from simple cryptographic primitives.}}, author = {{Blömer, Johannes and Löken, Nils}}, booktitle = {{Security and Trust Management, STM 2019}}, title = {{{Personal Cross-Platform Reputation}}}, doi = {{10.1007/978-3-030-31511-5_9}}, volume = {{11738}}, year = {{2019}}, } @inproceedings{13557, abstract = {{We present a searchable encryption scheme for dynamic document collections in a multi-user scenario. Our scheme features fine-grained access control to search results, as well as access control to operations such as adding documents to the document collection, or changing individual documents. The scheme features verifiability of search results. Our scheme also satisfies the forward privacy notion crucial for the security of dynamic searchable encryption schemes.}}, author = {{Blömer, Johannes and Löken, Nils}}, booktitle = {{12th International Symposium on Foundations and Practice of Security, FPS 2019}}, publisher = {{Springer}}, title = {{{Dynamic Searchable Encryption with Access Control}}}, volume = {{12056}}, year = {{2019}}, } @inproceedings{13585, author = {{Bohn, Nicolai and Kundisch, Dennis}}, booktitle = {{Proceedings of the 40th International Conference on Information Systems (ICIS)}}, location = {{Munich, Germany}}, title = {{{All Things Considered? – Technology Design Decision-making Characteristics in Digital Startups}}}, year = {{2019}}, } @inproceedings{13586, author = {{Seutter, Janina and Neumann, Jürgen}}, booktitle = {{Proceedings of the 40th International Conference on Information Systems (ICIS)}}, location = {{Munich, Germany}}, title = {{{Head over Feels? Differences in Online Rating Behavior for Utilitarian and Hedonic Service Aspects}}}, year = {{2019}}, } @inproceedings{13587, author = {{Gutt, Dominik and Neumann, Jürgen and Jabr, W. and Kundisch, Dennis}}, booktitle = {{Proceedings of the 40th International Conference on Information Systems (ICIS)}}, location = {{Munich, Germany}}, title = {{{The App Updating Conundrum: Implications of Platform’s Rating Resetting on Developers’ Behavior}}}, year = {{2019}}, } @misc{13592, author = {{Pilot, Matthias}}, publisher = {{Universität Paderborn}}, title = {{{Efficient Finite-Field Arithmetic for Elliptic Curve Cryptography in Java}}}, year = {{2019}}, } @inproceedings{13647, author = {{Claes, Leander and Johannesmann, Sarah and Baumhögger, Elmar and Henning, Bernd}}, booktitle = {{2019 International Congress on Ultrasonics}}, location = {{Bruges}}, title = {{{Quantification of frequency-dependent absorption phenomena}}}, doi = {{10.1121/2.0001043}}, year = {{2019}}, } @misc{13648, author = {{Scholz, Swante}}, publisher = {{Universität Paderborn}}, title = {{{Implementation and Comparison of Elliptic Curve Algorithms in Java}}}, year = {{2019}}, }