@article{28598, author = {{Eickelmann, Birgit and Bos, Wilfried and Gerick, Julia}}, journal = {{SchulVerwaltung NRW}}, pages = {{145--148}}, title = {{{Wie geht es weiter? Zentrale Befunde der Studie ICILS 2013 und mögliche Handlungs- und Entwicklungsperspektiven für Einzelschulen}}}, volume = {{5}}, year = {{2015}}, } @misc{286, author = {{Kalde, Benedikt}}, publisher = {{Universität Paderborn}}, title = {{{Implementierung eines hybriden Verschlüsselungsverfahrens nach Cramer und Shoup}}}, year = {{2015}}, } @book{28601, author = {{Eickelmann, Birgit and Bos, Wilfried and Vennemann, Mario}}, publisher = {{Waxmann}}, title = {{{Total digital? - Wie Jugendliche Kompetenzen im Umgang mit neuen Technologien erwerben. Dokumentation der Analysen des Vertiefungsmoduls zu ICILS 2013}}}, year = {{2015}}, } @inbook{28603, author = {{Lai, Kwok-Wing and Davis, Niki and Eickelmann, Birgit and Erstad, Ola and Fisser, Petra and Gibson, David C. and Khaddage, Ferial and Knezek, Gerald and Webb, Mary}}, booktitle = {{KEYCIT 2014. Key Competencies in Informatics and ICT}}, editor = {{Brinda, Torsten and Reynolds, Nicholas and Romeike, Ralf and Schwill, Andreas}}, pages = {{415--424}}, publisher = {{Universitätsverlag}}, title = {{{Tackling Educational Challenges in a Digitally Networked World}}}, year = {{2015}}, } @misc{2865, author = {{Strotmann, Daniela}}, title = {{{Singulärwertzerlegung für μ-ähnliche Bregman-Divergenzen}}}, year = {{2015}}, } @inproceedings{287, abstract = {{The size of modern data centers is constantly increasing. As it is not economic to interconnect all machines in the data center using a full-bisection-bandwidth network, techniques have to be developed to increase the efficiency of data-center networks. The Software-Defined Network paradigm opened the door for centralized traffic engineering (TE) in such environments. Up to now, there were already a number of TE proposals for SDN-controlled data centers that all work very well. However, these techniques either use a high amount of flow table entries or a high flow installation rate that overwhelms available switching hardware, or they require custom or very expensive end-of-line equipment to be usable in practice. We present HybridTE, a TE technique that uses (uncertain) information about large flows. Using this extra information, our technique has very low hardware requirements while maintaining better performance than existing TE techniques. This enables us to build very low-cost, high performance data-center networks.}}, author = {{Wette, Philip and Karl, Holger}}, booktitle = {{Proceedings of the 4th European Workshop on Software Defined Networks (EWSDN 2015)}}, pages = {{1----7}}, title = {{{HybridTE: Traffic Engineering for Very Low-Cost Software-Defined Data-Center Networks}}}, doi = {{10.1109/EWSDN.2015.57}}, year = {{2015}}, } @inproceedings{24073, author = {{Erfurth, Christian and Pottebaum, Jens}}, booktitle = {{45. Jahrestagung der Gesellschaft für Informatik, Informatik 2015, Informatik, Energie und Umwelt, 28. September - 2. Oktober 2015 in Cottbus, Deutschland}}, editor = {{Cunningham, Douglas W. and Hofstedt, Petra and Meer, Klaus and Schmitt, Ingo}}, isbn = {{978-3-88579-640-4}}, keywords = {{Ver{\}}, pages = {{1141--1142}}, publisher = {{GI}}, title = {{{IT-Unterstützung in Emergency Management & Response}}}, year = {{2015}}, } @inproceedings{241, abstract = {{Distributed applications are commonly based on overlay networks interconnecting their sites so that they can exchange information. For these overlay networks to preserve their functionality, they should be able to recover from various problems like membership changes or faults. Various self-stabilizing overlay networks have already been proposed in recent years, which have the advantage of being able to recover from any illegal state, but none of these networks can give any guarantees on its functionality while the recovery process is going on. We initiate research on overlay networks that are not only self-stabilizing but that also ensure that searchability is maintained while the recovery process is going on, as long as there are no corrupted messages in the system. More precisely, once a search message from node u to another node v is successfully delivered, all future search messages from u to v succeed as well. We call this property monotonic searchability. We show that in general it is impossible to provide monotonic searchability if corrupted messages are present in the system, which justifies the restriction to system states without corrupted messages. Furthermore, we provide a self-stabilizing protocol for the line for which we can also show monotonic searchability. It turns out that even for the line it is non-trivial to achieve this property. Additionally, we extend our protocol to deal with node departures in terms of the Finite Departure Problem of Foreback et. al (SSS 2014). This makes our protocol even capable of handling node dynamics.}}, author = {{Scheideler, Christian and Setzer, Alexander and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 19th International Conference on Principles of Distributed Systems (OPODIS)}}, title = {{{Towards Establishing Monotonic Searchability in Self-Stabilizing Data Structures}}}, doi = {{10.4230/LIPIcs.OPODIS.2015.24}}, year = {{2015}}, } @inproceedings{242, abstract = {{A fundamental problem for overlay networks is to safely exclude leaving nodes, i.e., the nodes requesting to leave the overlay network are excluded from it without affecting its connectivity. There are a number of studies for safe node exclusion if the overlay is in a well-defined state, but almost no formal results are known for the case in which the overlay network is in an arbitrary initial state, i.e., when looking for a self-stabilizing solution for excluding leaving nodes. We study this problem in two variants: the Finite Departure Problem (FDP) and the Finite Sleep Problem (FSP). In the FDP the leaving nodes have to irrevocably decide when it is safe to leave the network, whereas in the FSP, this leaving decision does not have to be final: the nodes may resume computation when woken up by an incoming message. We are the first to present a self-stabilizing protocol for the FDP and the FSP that can be combined with a large class of overlay maintenance protocols so that these are then guaranteed to safely exclude leaving nodes from the system from any initial state while operating as specified for the staying nodes. In order to formally define the properties these overlay maintenance protocols have to satisfy, we identify four basic primitives for manipulating edges in an overlay network that might be of independent interest.}}, author = {{Koutsopoulos, Andreas and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 17th International Symposium on Stabilization, Safety, and Security of Distributed Systems (SSS)}}, pages = {{201--216}}, title = {{{Towards a Universal Approach for the Finite Departure Problem in Overlay Networks}}}, doi = {{10.1007/978-3-319-21741-3_14}}, year = {{2015}}, } @inproceedings{243, abstract = {{This paper introduces the problem of communication pattern adaption for a distributed self-adjusting binary search tree. We propose a simple local algorithm, which is closely related to the nearly thirty-year-old idea of splay trees and evaluate its adaption performance in the distributed scenario if different communication patterns are provided.To do so, the process of self-adjustment is modeled similarly to a basic network creation game, in which the nodes want to communicate with only a certain subset of all nodes. We show that, in general, the game (i.e., the process of local adjustments) does not converge, and convergence is related to certain structures of the communication interests, which we call conflicts.We classify conflicts and show that for two communication scenarios in which convergence is guaranteed, the self-adjusting tree performs well.Furthermore, we investigate the different classes of conflicts separately and show that, for a certain class of conflicts, the performance of the tree network is asymptotically as good as the performance for converging instances. However, for the other conflict classes, a distributed self-adjusting binary search tree adapts poorly.}}, author = {{Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 9th International Workshop on Algorithms and Computation (WALCOM)}}, pages = {{175----186}}, title = {{{The impact of communication patterns on distributed locally self-adjusting binary search trees}}}, doi = {{10.1007/978-3-319-15612-5_16}}, year = {{2015}}, } @article{244, abstract = {{We revisit the simple class of weighted congestion games on parallel links [10], where each player has a non-negative weight and her cost on the link she chooses is the sum of the weights of all players choosing the link. We extend this class to mix-weighted congestion games on parallel links, where weights may as well be negative. For the resulting simple class, we study the complexity of deciding the existence of a pure equilibrium, where no player could unilaterally improve her cost by switching to another link.We show that even for a singlenegative weight, this decision problem is strongly NP-complete when the number of links is part of the input; the problem is NP-complete already for two links. When the number of links is a fixed constant, we show, through a pseudopolynomial, dynamic programming algorithm, that the problem is not strongly NP-complete unless P = NP; the algorithm works for any number of negative weights.}}, author = {{Monien, Burkhard and Mavronicolas, Marios}}, journal = {{Information Processing Letters}}, number = {{12}}, pages = {{927--931}}, publisher = {{Elsevier}}, title = {{{The complexity of pure equilibria in mix-weighted congestion games on parallel links}}}, doi = {{10.1016/j.ipl.2015.07.012}}, volume = {{115}}, year = {{2015}}, } @inproceedings{245, abstract = {{In cloud computing, software architects develop systems for virtually unlimited resources that cloud providers account on a pay-per-use basis. Elasticity management systems provision these resources autonomously to deal with changing workload. Such changing workloads call for new objective metrics allowing architects to quantify quality properties like scalability, elasticity, and efficiency, e.g., for requirements/SLO engineering and software design analysis. In literature, initial metrics for these properties have been proposed. However, current metrics lack a systematic derivation and assume knowledge of implementation details like resource handling. Therefore, these metrics are inapplicable where such knowledge is unavailable.To cope with these lacks, this short paper derives metrics for scalability, elasticity, and efficiency properties of cloud computing systems using the goal question metric (GQM) method. Our derivation uses a running example that outlines characteristics of cloud computing systems. Eventually, this example allows us to set up a systematic GQM plan and to derive an initial set of six new metrics. We particularly show that our GQM plan allows to classify existing metrics.}}, author = {{Becker, Matthias and Lehrig, Sebastian and Becker, Steffen}}, booktitle = {{Proceedings of the 6th ACM/SPEC International Conference on Performance Engineering}}, pages = {{169----174}}, title = {{{Systematically Deriving Quality Metrics for Cloud Computing Systems}}}, doi = {{10.1145/2668930.2688043}}, year = {{2015}}, } @inproceedings{24530, author = {{Moritzer, Elmar and Hopp, Matthias}}, booktitle = {{68th Annual Assembly of the International Institute of Welding (IIW)}}, title = {{{Bonding of Wood Plastic Composites (WPC) - Material and Surface Modification for Special Applications}}}, year = {{2015}}, } @article{24531, author = {{Moritzer, Elmar and Hopp, Matthias}}, issn = {{1618-8357}}, journal = {{Jahresmagazin Kunststofftechnik}}, title = {{{Kleben von Wood-Plastic-Composites (WPC) - Material- und Oberflächenmodifizierung für spezielle Anwendungen}}}, year = {{2015}}, } @phdthesis{246, author = {{Besova, Galina}}, publisher = {{Universität Paderborn}}, title = {{{Systematic Development and Re-Use of Model Tranformations}}}, year = {{2015}}, } @inproceedings{247, abstract = {{Multi-rooted trees are becoming the norm for modern data-center networks. In these networks, scalable flow routing is challenging owing to vast number of flows. Current approaches either employ a central controller that can have scalability issues or a scalable decentralized algorithm only considering local information. In this paper we present a new decentralized approach to least-congested path routing in software-defined data center networks that has neither of these issues: By duplicating the initial (or SYN) packet of a flow and estimating the data rate of multiple flows in parallel, we exploit TCP’s habit to fill buffers to find the least congested path. We show that our algorithm significantly improves flow completion time without the need for a central controller or specialized hardware.}}, author = {{Schwabe, Arne and Karl, Holger}}, booktitle = {{Proceedings of the 4th European Workshop on Software Defined Networks (EWSDN 2015)}}, pages = {{37--42}}, title = {{{SynRace: Decentralized Load-Adaptive Multi-path Routing without Collecting Statistics}}}, doi = {{10.1109/EWSDN.2015.58}}, year = {{2015}}, } @misc{258, author = {{Sonntag, Melissa}}, publisher = {{Universität Paderborn}}, title = {{{Reputation und Vertrauen auf Online-Märkten}}}, year = {{2015}}, } @inproceedings{259, author = {{Gutt, Dominik and Kundisch, Dennis}}, booktitle = {{INFORMS Annual Meeting}}, location = {{Philadelphia, USA}}, title = {{{Rating Aggregation in Multi-Dimensional Rating Systems: How Do Reviewers Form Overall Ratings?}}}, year = {{2015}}, } @article{260, abstract = {{During the last decade, researchers have proposed a number of model transformations enabling performance predictions. These transformations map performance-annotated software architecture models into stochastic models solved by analytical means or by simulation. However, so far, a detailed quantitative evaluation of the accuracy and efficiency of different transformations is missing, making it hard to select an adequate transformation for a given context. This paper provides an in-depth comparison and quantitative evaluation of representative model transformations to, e.g., Queueing Petri Nets and Layered Queueing Networks. The semantic gaps between typical source model abstractions and the different analysis techniques are revealed. The accuracy and efficiency of each transformation are evaluated by considering four case studies representing systems of different size and complexity. The presented results and insights gained from the evaluation help software architects and performance engineers to select the appropriate transformation for a given context, thus significantly improving the usability of model transformations for performance prediction.}}, author = {{Brosig, Fabian and Meier, Philipp and Becker, Steffen and Koziolek, Anne and Koziolek, Heiko and Kounev, Samuel}}, journal = {{Transactions on Software Engineering}}, number = {{2}}, pages = {{157----175}}, publisher = {{IEEE}}, title = {{{Quantitative Evaluation of Model-Driven Performance Analysis and Simulation of Component-based Architectures}}}, doi = {{10.1109/TSE.2014.2362755}}, year = {{2015}}, } @misc{261, author = {{Eisenhofer, Thorsten}}, publisher = {{Universität Paderborn}}, title = {{{Protokolle zur authentifizierten Schüsselvereinbarung}}}, year = {{2015}}, }