TY - JOUR A1 - Dyck, Johannes A1 - Giese, Holger A1 - Lambers, Leen T1 - Automatic verification of behavior preservation at the transformation level for relational model transformation JF - Software and systems modeling N2 - The correctness of model transformations is a crucial element for model-driven engineering of high-quality software. In particular, behavior preservation is an important correctness property avoiding the introduction of semantic errors during the model-driven engineering process. Behavior preservation verification techniques show some kind of behavioral equivalence or refinement between source and target model of the transformation. Automatic tool support is available for verifying behavior preservation at the instance level, i.e., for a given source and target model specified by the model transformation. However, until now there is no sound and automatic verification approach available at the transformation level, i.e., for all source and target models. In this article, we extend our results presented in earlier work (Giese and Lambers, in: Ehrig et al (eds) Graph transformations, Springer, Berlin, 2012) and outline a new transformation-level approach for the sound and automatic verification of behavior preservation captured by bisimulation resp.simulation for outplace model transformations specified by triple graph grammars and semantic definitions given by graph transformation rules. In particular, we first show how behavior preservation can be modeled in a symbolic manner at the transformation level and then describe that transformation-level verification of behavior preservation can be reduced to invariant checking of suitable conditions for graph transformations. We demonstrate that the resulting checking problem can be addressed by our own invariant checker for an example of a transformation between sequence charts and communicating automata. KW - Relational model transformation KW - Formal verification of behavior preservation KW - Behavioral equivalence and refinement KW - Bisimulation and simulation KW - Graph transformation KW - Triple graph grammars KW - Invariant checking Y1 - 2018 U6 - https://doi.org/10.1007/s10270-018-00706-9 SN - 1619-1366 SN - 1619-1374 VL - 18 IS - 5 SP - 2937 EP - 2972 PB - Springer CY - Heidelberg ER - TY - GEN A1 - Hölzle, Katharina A1 - Björk, Jennie A1 - Visscher, Klaasjan T1 - Editorial T2 - Creativity and innovation management N2 - The new year starts and many of us have right away been burdened with conference datelines, grant proposal datelines, teaching obligations, paper revisions and many other things. While being more or less successful in fulfilling To‐Do lists and ticking of urgent (and sometimes even important) things, we often feel that our ability to be truly creative or innovative is rather restrained by this (external pressure). With this, we are not alone. Many studies have shown that stress does influence overall work performance and satisfaction. Furthermore, more and more students and entry‐levels look for work‐life balance and search for employers that offer a surrounding and organization considering these needs. High‐Tech and start‐up companies praise themselves for their “Feel‐Good managers” or Yoga programs. But is this really helpful? Is there indeed a relationship between stress, adverse work environment and creativity or innovation? What are the supporting factors in a work environment that lets employees be more creative? What kind of leadership do we need for innovative behaviour and to what extent can an organization create support structures that reduce the stress we feel? The first issue of Creativity and Innovation Management in 2019 gives some first answers to these questions and hopefully some food for thought. The first paper written by Dirk De Clercq, and Imanol Belausteguigoitia starts with the question which impact work overload has on creative behaviour. The authors look at how employees' perceptions of work overload reduces their creative behaviour. While they find empirical proof for this relationship, they can also show that the effect is weaker with higher levels of passion for work, emotion sharing, and organizational commitment. The buffering effects of emotion sharing and organizational commitment are particularly strong when they are combined with high levels of passion for work. Their findings give first empirical proof that organizations can and should take an active role in helping their employees reducing the effects of adverse work conditions in order to become or stay creative. However, not only work overload is harming creative behaviour, also the fear of losing one's job has detrimental effects on innovative work behaviour. Anahi van Hootegem, Wendy Niesen and Hans de Witte verify that stress and adverse environmental conditions shape our perception of work. Using threat rigidity theory and an empirical study of 394 employees, they show that the threat of job loss impairs employees' innovativeness through increased irritation and decreased concentration. Organizations can help their employees coping better with this insecurity by communicating more openly and providing different support structures. Support often comes from leadership and the support of the supervisor can clearly shape an employee's motivation to show creative behaviour. Wenjing Cai, Evgenia Lysova, Bart A. G. Bossink, Svetlana N. Khapova and Weidong Wang report empirical findings from a large‐scale survey in China where they find that supervisor support for creativity and job characteristics effectively activate individual psychological capital associated with employee creativity. On a slight different notion, Gisela Bäcklander looks at agile practices in a very well‐known High Tech firm. In “Doing Complexity Leadership Theory: How agile coaches at Spotify practice enabling leadership”, she researches the role of agile coaches and how they practice enabling leadership, a key balancing force in complexity leadership. She finds that the active involvement of coaches in observing group dynamics, surfacing conflict and facilitating and encouraging constructive dialogue leads to a positive working environment and the well‐being of employees. Quotes from the interviews suggest that the flexible structure provided by the coaches may prove a fruitful way to navigate and balance autonomy and alignment in organizations. The fifth paper of Frederik Anseel, Michael Vandamme, Wouter Duyck and Eric Rietzchel goes a little further down this road and researches how groups can be motivated better to select truly creative ideas. We know from former studies that groups often perform rather poorly when it comes to selecting creative ideas for implementation. The authors find in an extensive field experiment that under conditions of high epistemic motivation, proself motivated groups select significantly more creative and original ideas than prosocial groups. They conclude however, that more research is needed to understand better why these differences occur. The prosocial behaviour of groups is also the theme of Karin Moser, Jeremy F. Dawson and Michael A. West's paper on “Antecedents of team innovation in health care teams”. They look at team‐level motivation and how a prosocial team environment, indicated by the level of helping behaviour and information‐sharing, may foster innovation. Their results support the hypotheses of both information‐sharing and helping behaviour on team innovation. They suggest that both factors may actually act as buffer against constraints in team work, such as large team size or high occupational diversity in cross‐functional health care teams, and potentially turn these into resources supporting team innovation rather than acting as barriers. Away from teams and onto designing favourable work environments, the seventh paper of Ferney Osorio, Laurent Dupont, Mauricio Camargo, Pedro Palominos, Jose Ismael Pena and Miguel Alfaro looks into innovation laboratories. Although several studies have tackled the problem of design, development and sustainability of these spaces for innovation, there is still a gap in understanding how the capabilities and performance of these environments are affected by the strategic intentions at the early stages of their design and functioning. The authors analyse and compare eight existing frameworks from literature and propose a new framework for researchers and practitioners aiming to assess or to adapt innovation laboratories. They test their framework in an exploratory study with fifteen laboratories from five different countries and give recommendations for the future design of these laboratories. From design to design thinking goes our last paper from Rama Krishna Reddy Kummitha on “Design Thinking in Social Organisations: Understanding the role of user engagement” where she studies how users persuade social organisations to adopt design thinking. Looking at four social organisations in India during 2008 to 2013, she finds that the designer roles are blurred when social organisations adopt design thinking, while users in the form of interconnecting agencies reduce the gap between designers and communities. The last two articles were developed from papers presented at the 17th International CINet conference organized in Turin in 2016 by Paolo Neirotti and his colleagues. In the first article, Fábio Gama, Johan Frishammar and Vinit Parida focus on ideation and open innovation in small‐ and medium‐sized enterprises. They investigate the relationship between systematic idea generation and performance and the moderating role of market‐based partnerships. Based on a survey among manufacturing SMEs, they conclude that higher levels of performance are reached and that collaboration with customers and suppliers pays off most when idea generation is done in a highly systematic way. The second article, by Anna Holmquist, Mats Magnusson and Mona Livholts, resonates the theme of the CINet conference ‘Innovation and Tradition; combining the old and the new’. They explore how tradition is used in craft‐based design practices to create new meaning. Applying a narrative ‘research through design’ approach they uncover important design elements, and tensions between them. Please enjoy this first issue of CIM in 2019 and we wish you creativity and innovation without too much stress in the months to come. Y1 - 2019 U6 - https://doi.org/10.1111/caim.12307 SN - 0963-1690 SN - 1467-8691 VL - 28 IS - 1 SP - 3 EP - 4 PB - Wiley CY - Hoboken ER - TY - THES A1 - Nikaj, Adriatik T1 - Restful choreographies T1 - REST-Choreografien N2 - Business process management has become a key instrument to organize work as many companies represent their operations in business process models. Recently, business process choreography diagrams have been introduced as part of the Business Process Model and Notation standard to represent interactions between business processes, run by different partners. When it comes to the interactions between services on the Web, Representational State Transfer (REST) is one of the primary architectural styles employed by web services today. Ideally, the RESTful interactions between participants should implement the interactions defined at the business choreography level. The problem, however, is the conceptual gap between the business process choreography diagrams and RESTful interactions. Choreography diagrams, on the one hand, are modeled from business domain experts with the purpose of capturing, communicating and, ideally, driving the business interactions. RESTful interactions, on the other hand, depend on RESTful interfaces that are designed by web engineers with the purpose of facilitating the interaction between participants on the internet. In most cases however, business domain experts are unaware of the technology behind web service interfaces and web engineers tend to overlook the overall business goals of web services. While there is considerable work on using process models during process implementation, there is little work on using choreography models to implement interactions between business processes. This thesis addresses this research gap by raising the following research question: How to close the conceptual gap between business process choreographies and RESTful interactions? This thesis offers several research contributions that jointly answer the research question. The main research contribution is the design of a language that captures RESTful interactions between participants---RESTful choreography modeling language. Formal completeness properties (with respect to REST) are introduced to validate its instances, called RESTful choreographies. A systematic semi-automatic method for deriving RESTful choreographies from business process choreographies is proposed. The method employs natural language processing techniques to translate business interactions into RESTful interactions. The effectiveness of the approach is shown by developing a prototypical tool that evaluates the derivation method over a large number of choreography models. In addition, the thesis proposes solutions towards implementing RESTful choreographies. In particular, two RESTful service specifications are introduced for aiding, respectively, the execution of choreographies' exclusive gateways and the guidance of RESTful interactions. N2 - Das Prozessmanagement hat sich zu einer wichtigen Methode zur Organisation von Arbeitsabläufen entwickelt, sodass viele Unternehmen ihre Tätigkeiten mittlerweile in Prozessmodellen darstellen. Unlängst wurden zudem im Kontext der Business Process Model and Notation Choreographiediagramme eingeführt, um Interaktionen zwischen Prozessen verschiedener Partner zu beschreiben. Im Web nutzen interagierende Dienste heutzutage den Representational State Transfer (REST) als primären Architekturstil. Idealerweise implementieren die REST-Interaktionen der Dienste also die Interaktionen, die im Choreographiediagramm definiert wurden. Allerdings besteht zwischen Choreographiediagrammen und RESTInteraktionen eine konzeptuelle Diskrepanz. Auf der einen Seite werden Choreographiediagramme von Domänenexperten mit dem Ziel modelliert, die Interaktionen zu erfassen, zu kommunizieren und, idealerweise, voranzutreiben. Auf der anderen Seite sind REST-Interaktionen abhängig von REST-Schnittstellen, welche von Web-Entwicklern mit dem Ziel entworfen werden, Interaktionen zwischen Diensten im Internet zu erleichtern. In den meisten Fällen sind sich Domänenexperten jedoch der Technologien, die Web-Schnittstellen zu Grunde liegen, nicht bewusst, wohingegenWeb-Entwickler die Unternehmensziele der Web-Dienste nicht kennen. Während es umfangreiche Arbeiten zur Implementierung von Prozessmodellen gibt, existieren nur wenige Untersuchungen zur Implementierung von interagierenden Prozessen auf Basis von Choreographiemodellen. Die vorliegende Dissertation adressiert diese Forschungslücke, indem sie die folgende Forschungsfrage aufwirft: Wie kann die konzeptuelle Diskrepanz zwischen Choreographiediagrammen und REST-Interaktionen beseitigt werden? Somit enthält diese Arbeit mehrere Forschungsbeiträge, um diese Frage zu adressieren. Der primäre Beitrag besteht in dem Design einer Modellierungssprache, um REST-Interaktionen zwischen Diensten zu erfassen—der RESTful Choreography Modeling Language. Formale Vollständigkeitseigenschaften (in Bezug auf REST) werden eingeführt, um Instanzen dieser Modelle, sogennante REST-Choreographien, zu validieren. Ferner wird eine systematische, halb-automatische Methode vorgestellt, um RESTChoreographien von Choreographiediagrammen abzuleiten. Diese Methode setzt Techniken des Natural Language Processing ein, um Interaktionen in REST-Interaktionen zu übersetzen. Die Wirksamkeit des Ansatzes wird durch die Entwicklung eines prototypischen Werkzeugs demonstriert, welches die Ableitungsmethode anhand einer großen Anzahl von Choreographiediagrammen evaluiert. Darüber hinaus stellt diese Arbeit Lösungen zur Implementierung von REST-Choreographien bereit. Insbesondere werden zwei REST-Dienstspezifikationen vorgestellt, welche die korrekte Ausführung von exklusiven Gateways eines Choreographiediagramms und die Führung der REST-Interaktionen unterstützen. KW - business process choreographies KW - RESTful interactions KW - Geschäftsprozess-Choreografien KW - REST-Interaktionen Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-438903 ER - TY - GEN A1 - Schlosser, Rainer A1 - Kossmann, Jan A1 - Boissier, Martin T1 - Efficient Scalable Multi-Attribute Index Selection Using Recursive Strategies T2 - 2019 IEEE 35th International Conference on Data Engineering (ICDE) N2 - An efficient selection of indexes is indispensable for database performance. For large problem instances with hundreds of tables, existing approaches are not suitable: They either exhibit prohibitive runtimes or yield far from optimal index configurations by strongly limiting the set of index candidates or not handling index interaction explicitly. We introduce a novel recursive strategy that does not exclude index candidates in advance and effectively accounts for index interaction. Using large real-world workloads, we demonstrate the applicability of our approach. Further, we evaluate our solution end to end with a commercial database system using a reproducible setup. We show that our solutions are near-optimal for small index selection problems. For larger problems, our strategy outperforms state-of-the-art approaches in both scalability and solution quality. Y1 - 2019 SN - 978-1-5386-7474-1 U6 - https://doi.org/10.1109/ICDE.2019.00113 SN - 1084-4627 SP - 1238 EP - 1249 PB - IEEE CY - New York ER - TY - JOUR A1 - Stojanovic, Vladeta A1 - Trapp, Matthias A1 - Richter, Rico A1 - Döllner, Jürgen Roland Friedrich T1 - Service-oriented semantic enrichment of indoor point clouds using octree-based multiview classification JF - Graphical Models N2 - The use of Building Information Modeling (BIM) for Facility Management (FM) in the Operation and Maintenance (O&M) stages of the building life-cycle is intended to bridge the gap between operations and digital data, but lacks the functionality of assessing the state of the built environment due to non-automated generation of associated semantics. 3D point clouds can be used to capture the physical state of the built environment, but also lack these associated semantics. A prototypical implementation of a service-oriented architecture for classification of indoor point cloud scenes of office environments is presented, using multiview classification. The multiview classification approach is tested using a retrained Convolutional Neural Network (CNN) model - Inception V3. The presented approach for classifying common office furniture objects (chairs, sofas and desks), contained in 3D point cloud scans, is tested and evaluated. The results show that the presented approach can classify common office furniture up to an acceptable degree of accuracy, and is suitable for quick and robust semantics approximation - based on RGB (red, green and blue color channel) cubemap images of the octree partitioned areas of the 3D point cloud scan. Additional methods for web-based 3D visualization, editing and annotation of point clouds are also discussed. Using the described approach, captured scans of indoor environments can be semantically enriched using object annotations derived from multiview classification results. Furthermore, the presented approach is suited for semantic enrichment of lower resolution indoor point clouds acquired using commodity mobile devices. KW - Semantic enrichment KW - 3D point clouds KW - Multiview classification KW - Service-oriented KW - Indoor environments Y1 - 2019 U6 - https://doi.org/10.1016/j.gmod.2019.101039 SN - 1524-0703 SN - 1524-0711 VL - 105 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Reimann, Max A1 - Klingbeil, Mandy A1 - Pasewaldt, Sebastian A1 - Semmo, Amir A1 - Trapp, Matthias A1 - Döllner, Jürgen Roland Friedrich T1 - Locally controllable neural style transfer on mobile devices JF - The Visual Computer N2 - Mobile expressive rendering gained increasing popularity among users seeking casual creativity by image stylization and supports the development of mobile artists as a new user group. In particular, neural style transfer has advanced as a core technology to emulate characteristics of manifold artistic styles. However, when it comes to creative expression, the technology still faces inherent limitations in providing low-level controls for localized image stylization. In this work, we first propose a problem characterization of interactive style transfer representing a trade-off between visual quality, run-time performance, and user control. We then present MaeSTrO, a mobile app for orchestration of neural style transfer techniques using iterative, multi-style generative and adaptive neural networks that can be locally controlled by on-screen painting metaphors. At this, we enhance state-of-the-art neural style transfer techniques by mask-based loss terms that can be interactively parameterized by a generalized user interface to facilitate a creative and localized editing process. We report on a usability study and an online survey that demonstrate the ability of our app to transfer styles at improved semantic plausibility. KW - Non-photorealistic rendering KW - Style transfer KW - Neural networks KW - Mobile devices KW - Interactive control KW - Expressive rendering Y1 - 2019 U6 - https://doi.org/10.1007/s00371-019-01654-1 SN - 0178-2789 SN - 1432-2315 VL - 35 IS - 11 SP - 1531 EP - 1547 PB - Springer CY - New York ER - TY - JOUR A1 - Kötzing, Timo A1 - Krejca, Martin Stefan T1 - First-hitting times under drift JF - Theoretical computer science N2 - For the last ten years, almost every theoretical result concerning the expected run time of a randomized search heuristic used drift theory, making it the arguably most important tool in this domain. Its success is due to its ease of use and its powerful result: drift theory allows the user to derive bounds on the expected first-hitting time of a random process by bounding expected local changes of the process - the drift. This is usually far easier than bounding the expected first-hitting time directly. Due to the widespread use of drift theory, it is of utmost importance to have the best drift theorems possible. We improve the fundamental additive, multiplicative, and variable drift theorems by stating them in a form as general as possible and providing examples of why the restrictions we keep are still necessary. Our additive drift theorem for upper bounds only requires the process to be lower-bounded, that is, we remove unnecessary restrictions like a finite, discrete, or bounded state space. As corollaries, the same is true for our upper bounds in the case of variable and multiplicative drift. By bounding the step size of the process, we derive new lower-bounding multiplicative and variable drift theorems. Last, we also state theorems that are applicable when the process has a drift of 0, by using a drift on the variance of the process. KW - First-hitting time KW - Random process KW - Drift Y1 - 2019 U6 - https://doi.org/10.1016/j.tcs.2019.08.021 SN - 0304-3975 SN - 1879-2294 VL - 796 SP - 51 EP - 69 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Friedrich, Tobias A1 - Kötzing, Timo A1 - Krejca, Martin Stefan T1 - Unbiasedness of estimation-of-distribution algorithms JF - Theoretical computer science N2 - In the context of black-box optimization, black-box complexity is used for understanding the inherent difficulty of a given optimization problem. Central to our understanding of nature-inspired search heuristics in this context is the notion of unbiasedness. Specialized black-box complexities have been developed in order to better understand the limitations of these heuristics - especially of (population-based) evolutionary algorithms (EAs). In contrast to this, we focus on a model for algorithms explicitly maintaining a probability distribution over the search space: so-called estimation-of-distribution algorithms (EDAs). We consider the recently introduced n-Bernoulli-lambda-EDA framework, which subsumes, for example, the commonly known EDAs PBIL, UMDA, lambda-MMAS(IB), and cGA. We show that an n-Bernoulli-lambda-EDA is unbiased if and only if its probability distribution satisfies a certain invariance property under isometric automorphisms of [0, 1](n). By restricting how an n-Bernoulli-lambda-EDA can perform an update, in a way common to many examples, we derive conciser characterizations, which are easy to verify. We demonstrate this by showing that our examples above are all unbiased. (C) 2018 Elsevier B.V. All rights reserved. KW - Estimation-of-distribution algorithm KW - Unbiasedness KW - Theory Y1 - 2019 U6 - https://doi.org/10.1016/j.tcs.2018.11.001 SN - 0304-3975 SN - 1879-2294 VL - 785 SP - 46 EP - 59 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Mandal, Sankalita T1 - Event handling in business processes T1 - Ereignisbehandlung in Geschäftsprozessen BT - flexible event subscription for business process enactment BT - flexibles Ereignisabonnement für die Durchführung von Geschäftsprozessen N2 - Business process management (BPM) deals with modeling, executing, monitoring, analyzing, and improving business processes. During execution, the process communicates with its environment to get relevant contextual information represented as events. Recent development of big data and the Internet of Things (IoT) enables sources like smart devices and sensors to generate tons of events which can be filtered, grouped, and composed to trigger and drive business processes. The industry standard Business Process Model and Notation (BPMN) provides several event constructs to capture the interaction possibilities between a process and its environment, e.g., to instantiate a process, to abort an ongoing activity in an exceptional situation, to take decisions based on the information carried by the events, as well as to choose among the alternative paths for further process execution. The specifications of such interactions are termed as event handling. However, in a distributed setup, the event sources are most often unaware of the status of process execution and therefore, an event is produced irrespective of the process being ready to consume it. BPMN semantics does not support such scenarios and thus increases the chance of processes getting delayed or getting in a deadlock by missing out on event occurrences which might still be relevant. The work in this thesis reviews the challenges and shortcomings of integrating real-world events into business processes, especially the subscription management. The basic integration is achieved with an architecture consisting of a process modeler, a process engine, and an event processing platform. Further, points of subscription and unsubscription along the process execution timeline are defined for different BPMN event constructs. Semantic and temporal dependencies among event subscription, event occurrence, event consumption and event unsubscription are considered. To this end, an event buffer with policies for updating the buffer, retrieving the most suitable event for the current process instance, and reusing the event has been discussed that supports issuing of early subscription. The Petri net mapping of the event handling model provides our approach with a translation of semantics from a business process perspective. Two applications based on this formal foundation are presented to support the significance of different event handling configurations on correct process execution and reachability of a process path. Prototype implementations of the approaches show that realizing flexible event handling is feasible with minor extensions of off-the-shelf process engines and event platforms. N2 - Das Prozessmanagement befasst sich mit der Modellierung, Ausführung, Überwachung, Analyse und Verbesserung von Geschäftsprozessen. Während seiner Ausführung kommuniziert der Prozess mit seiner Umgebung, um relevante Kontextinformationen in Form von Ereignissen zu erhalten. Der jüngste Fortschritt im Bereich Big Data und dem Internet der Dinge ermöglicht Smart Devices und Sensoren eine Vielzahl von Ereignissen zu generieren, welche gefiltert, gruppiert und kombiniert werden können, um Geschäftsprozesse zu triggern und vor anzutreiben. Der Industriestandard Business Process Model and Notation (BPMN) stellt mehrere Ereigniskonstrukte bereit, um die Interaktionsmöglichkeiten eines Prozesses mit seiner Umgebung zu erfassen. Beispielsweise können Prozesse durch Ereignisse gestartet, laufende Aktivitäten in Ausnahmefällen abgebrochen, Entscheidungen auf Basis der Ereignisinformationen getroffen, und alternative Ausführungspfade gewählt werden. Die Spezifikation solcher Interaktionen wird als Event Handling bezeichnet. Allerdings sind sich insbesondere in verteilten Systemen die Ereignisquellen des Zustands des Prozesses unbewusst. Daher werden Ereignisse unabhängig davon produziert, ob der Prozess bereit ist sie zu konsumieren. Die BPMN-Semantik sieht solche Situationen jedoch nicht vor, sodass die Möglichkeit besteht, dass das Auftreten von relevanten Ereignissen versäumt wird. Dies kann zu Verzögerungen oder gar Deadlocks in der Prozessauführung führen. Die vorliegende Dissertation untersucht die Mängel und Herausforderungen der Integration von Ereignissen und Geschäftsprozessen, insbesondere in Bezug auf das Subscription Management. Die grundlegende Integration wird durch eine Architektur erreicht, die aus einer Prozessmodellierungskomponente, einer Ausführungskomponente und einer Ereignisverarbeitungskomponente besteht. Ferner werden Points of Subscription and Unsubscription für verschiedene BPMN-Ereigniskonstrukte entlang der Zeitachse der Prozessausführung definiert. Semantische und temporale Abhängigkeiten zwischen der Subscription, dem Auftreten, dem Konsumieren und der Unsubscription eines Ereignisses werden betrachtet. In dieser Hinsicht wird ein Event Bufferdiskutiert, welcher mit Strategien zum Update des Puffers, zum Abruf der geeigneten Ereignisse für den laufenden Prozess, sowie zur Wiederverwendung von Ereignissen ausgestattet ist. Die Abbildung des Event Handling Modells in ein Petri-Netz versieht den beschriebenen Ansatz mit einer eindeutigen Semantik. Basierend auf diesem Formalismus werden zwei Anwendungen demonstriert, die die Relevanz verschiedener Konfigurationen des Event Handlings für eine korrekte Prozessausführung aufzeigen. Eine prototypische Implementierung des Ansatzes beweist dessen Umsetzbarkeit durch geringe Erweiterungen bestehender Software zur Prozessausführung und Ereignisverarbeitung. KW - business process managament KW - complex event processing KW - BPMN KW - event subscription KW - Geschäftsprozessmanagement KW - komplexe Ereignisverarbeitung KW - BPMN KW - Ereignisabonnement Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-441700 ER - TY - JOUR A1 - Nikaj, Adriatik A1 - Weske, Mathias A1 - Mendling, Jan T1 - Semi-automatic derivation of RESTful choreographies from business process choreographies JF - Software and systems modeling N2 - Enterprises reach out for collaborations with other organizations in order to offer complex products and services to the market. Such collaboration and coordination between different organizations, for a good share, is facilitated by information technology. The BPMN process choreography is a modeling language for specifying the exchange of information and services between different organizations at the business level. Recently, there is a surging use of the REST architectural style for the provisioning of services on the web, but few systematic engineering approach to design their collaboration. In this paper, we address this gap in a comprehensive way by defining a semi-automatic method for the derivation of RESTful choreographies from process choreographies. The method is based on natural language analysis techniques to derive interactions from the textual information in process choreographies. The proposed method is evaluated in terms of effectiveness resulting in the intervention of a web engineer in only about 10% of all generated RESTful interactions. KW - Business process choreographies KW - RESTful choreographies KW - Natural language analysis Y1 - 2019 U6 - https://doi.org/10.1007/s10270-017-0653-2 SN - 1619-1366 SN - 1619-1374 VL - 18 IS - 2 SP - 1195 EP - 1208 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Schlosser, Rainer A1 - Richly, Keven T1 - Dynamic pricing under competition with data-driven price anticipations and endogenous reference price effects JF - Journal of revenue and pricing management N2 - Online markets have become highly dynamic and competitive. Many sellers use automated data-driven strategies to estimate demand and to update prices frequently. Further, notification services offered by marketplaces allow to continuously track markets and to react to competitors’ price adjustments instantaneously. To derive successful automated repricing strategies is challenging as competitors’ strategies are typically not known. In this paper, we analyze automated repricing strategies with data-driven price anticipations under duopoly competition. In addition, we account for reference price effects in demand, which are affected by the price adjustments of both competitors. We show how to derive optimized self-adaptive pricing strategies that anticipate price reactions of the competitor and take the evolution of the reference price into account. We verify that the results of our adaptive learning strategy tend to optimal solutions, which can be derived for scenarios with full information. Finally, we analyze the case in which our learning strategy is played against itself. We find that our self-adaptive strategies can be used to approximate equilibria in mixed strategies. KW - Dynamic pricing competition KW - Data-driven price anticipation KW - e-Commerce KW - Dynamic programming KW - Response strategies Y1 - 2019 U6 - https://doi.org/10.1057/s41272-019-00206-5 SN - 1476-6930 SN - 1477-657X VL - 18 IS - 6 SP - 451 EP - 464 PB - Palgrave Macmillan CY - Basingstoke ER - TY - JOUR A1 - Pufahl, Luise A1 - Weske, Mathias T1 - Batch activity: enhancing business process modeling and enactment with batch processing JF - Computing N2 - Organizations strive for efficiency in their business processes by process improvement and automation. Business process management (BPM) supports these efforts by capturing business processes in process models serving as blueprint for a number of process instances. In BPM, process instances are typically considered running independently of each other. However, batch processing-the collectively execution of several instances at specific process activities-is a common phenomenon in operational processes to reduce cost or time. Currently, batch processing is organized manually or hard-coded in software. For allowing stakeholders to explicitly represent their batch configurations in process models and their automatic execution, this paper provides a concept for batch activities and describes the corresponding execution semantics. The batch activity concept is evaluated in a two-step approach: a prototypical implementation in an existing BPM System proves its feasibility. Additionally, batch activities are applied to different use cases in a simulated environment. Its application implies cost-savings when a suitable batch configuration is selected. The batch activity concept contributes to practice by allowing the specification of batch work in process models and their automatic execution, and to research by extending the existing process modeling concepts. KW - Batch activity KW - Batch processing KW - Business process models KW - Process Enactment KW - Colored Petri Net Y1 - 2019 U6 - https://doi.org/10.1007/s00607-019-00717-4 SN - 0010-485X SN - 1436-5057 VL - 101 IS - 12 SP - 1909 EP - 1933 PB - Springer CY - Wien ER - TY - JOUR A1 - Bazhenova, Ekaterina A1 - Zerbato, Francesca A1 - Oliboni, Barbara A1 - Weske, Mathias T1 - From BPMN process models to DMN decision models JF - Information systems N2 - The interplay between process and decision models plays a crucial role in business process management, as decisions may be based on running processes and affect process outcomes. Often process models include decisions that are encoded through process control flow structures and data flow elements, thus reducing process model maintainability. The Decision Model and Notation (DMN) was proposed to achieve separation of concerns and to possibly complement the Business Process Model and Notation (BPMN) for designing decisions related to process models. Nevertheless, deriving decision models from process models remains challenging, especially when the same data underlie both process and decision models. In this paper, we explore how and to which extent the data modeled in BPMN processes and used for decision-making may be represented in the corresponding DMN decision models. To this end, we identify a set of patterns that capture possible representations of data in BPMN processes and that can be used to guide the derivation of decision models related to existing process models. Throughout the paper we refer to real-world healthcare processes to show the applicability of the proposed approach. (C) 2019 Elsevier Ltd. All rights reserved. KW - Business process models KW - Decision models KW - BPMN KW - DMN KW - Pattern Y1 - 2019 U6 - https://doi.org/10.1016/j.is.2019.02.001 SN - 0306-4379 SN - 1873-6076 VL - 83 SP - 69 EP - 88 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Risch, Julian A1 - Krestel, Ralf T1 - Domain-specific word embeddings for patent classification JF - Data Technologies and Applications N2 - Purpose Patent offices and other stakeholders in the patent domain need to classify patent applications according to a standardized classification scheme. The purpose of this paper is to examine the novelty of an application it can then be compared to previously granted patents in the same class. Automatic classification would be highly beneficial, because of the large volume of patents and the domain-specific knowledge needed to accomplish this costly manual task. However, a challenge for the automation is patent-specific language use, such as special vocabulary and phrases. Design/methodology/approach To account for this language use, the authors present domain-specific pre-trained word embeddings for the patent domain. The authors train the model on a very large data set of more than 5m patents and evaluate it at the task of patent classification. To this end, the authors propose a deep learning approach based on gated recurrent units for automatic patent classification built on the trained word embeddings. Findings Experiments on a standardized evaluation data set show that the approach increases average precision for patent classification by 17 percent compared to state-of-the-art approaches. In this paper, the authors further investigate the model’s strengths and weaknesses. An extensive error analysis reveals that the learned embeddings indeed mirror patent-specific language use. The imbalanced training data and underrepresented classes are the most difficult remaining challenge. Originality/value The proposed approach fulfills the need for domain-specific word embeddings for downstream tasks in the patent domain, such as patent classification or patent analysis. KW - Deep learning KW - Document classification KW - Word embedding KW - Patents Y1 - 2019 U6 - https://doi.org/10.1108/DTA-01-2019-0002 SN - 2514-9288 SN - 2514-9318 VL - 53 IS - 1 SP - 108 EP - 122 PB - Emerald Group Publishing Limited CY - Bingley ER - TY - JOUR A1 - Möring, Sebastian A1 - de Mutiis, Marco T1 - Camera Ludica BT - Reflections on Photography in Video Games JF - Intermedia games - Games inter media : Video games and intermediality Y1 - 2019 SN - 978-1-5013-3051-3 SN - 978-1-5013-3049-0 SP - 69 EP - 93 PB - Bloomsbury academic CY - New York ER - TY - GEN A1 - Matthies, Christoph T1 - Agile process improvement in retrospectives T2 - 41st International Conference on Software Engineering: Companion Proceedings (ICSE-Companion) N2 - Working in iterations and repeatedly improving team workflows based on collected feedback is fundamental to agile software development processes. Scrum, the most popular agile method, provides dedicated retrospective meetings to reflect on the last development iteration and to decide on process improvement actions. However, agile methods do not prescribe how these improvement actions should be identified, managed or tracked in detail. The approaches to detect and remove problems in software development processes are therefore often based on intuition and prior experiences and perceptions of team members. Previous research in this area has focused on approaches to elicit a team's improvement opportunities as well as measurements regarding the work performed in an iteration, e.g. Scrum burn-down charts. Little research deals with the quality and nature of identified problems or how progress towards removing issues is measured. In this research, we investigate how agile development teams in the professional software industry organize their feedback and process improvement approaches. In particular, we focus on the structure and content of improvement and reflection meetings, i.e. retrospectives, and their outcomes. Researching how the vital mechanism of process improvement is implemented in practice in modern software development leads to a more complete picture of agile process improvement. KW - Agile KW - Scrum KW - software process improvement KW - retrospective Y1 - 2019 SN - 978-1-7281-1764-5 SN - 978-1-7281-1765-2 U6 - https://doi.org/10.1109/ICSE-Companion.2019.00063 SN - 2574-1934 SN - 2574-1926 SP - 150 EP - 152 PB - IEEE CY - New York ER - TY - GEN A1 - Matthies, Christoph T1 - Feedback in Scrum BT - Data-Informed Retrospectives T2 - 2019 IEEE/ACM 41st International Conference on Software Engineering: Companion Proceedings (ICSE-Companion) N2 - Improving the way that teams work together by reflecting and improving the executed process is at the heart of agile processes. The idea of iterative process improvement takes various forms in different agile development methodologies, e.g. Scrum Retrospectives. However, these methods do not prescribe how improvement steps should be conducted in detail. In this research we investigate how agile software teams can use their development data, such as commits or tickets, created during regular development activities, to drive and track process improvement steps. Our previous research focused on data-informed process improvement in the context of student teams, where controlled circumstances and deep domain knowledge allowed creation and usage of specific process measures. Encouraged by positive results in this area, we investigate the process improvement approaches employed in industry teams. Researching how the vital mechanism of process improvement is implemented and how development data is already being used in practice in modern software development leads to a more complete picture of agile process improvement. It is the first step in enabling a data-informed feedback and improvement process, tailored to a team's context and based on the development data of individual teams. KW - agile KW - software development KW - Scrum KW - retrospective KW - software process improvement Y1 - 2019 SN - 978-1-7281-1764-5 SN - 978-1-7281-1765-2 U6 - https://doi.org/10.1109/ICSE-Companion.2019.00081 SN - 2574-1934 SN - 2574-1926 SP - 198 EP - 201 PB - IEEE CY - New York ER - TY - GEN A1 - Brand, Thomas A1 - Giese, Holger T1 - Generic adaptive monitoring based on executed architecture runtime model queries and events T2 - IEEE Xplore N2 - Monitoring is a key functionality for automated decision making as it is performed by self-adaptive systems, too. Effective monitoring provides the relevant information on time. This can be achieved with exhaustive monitoring causing a high overhead consumption of economical and ecological resources. In contrast, our generic adaptive monitoring approach supports effectiveness with increased efficiency. Also, it adapts to changes regarding the information demand and the monitored system without additional configuration and software implementation effort. The approach observes the executions of runtime model queries and processes change events to determine the currently required monitoring configuration. In this paper we explicate different possibilities to use the approach and evaluate their characteristics regarding the phenomenon detection time and the monitoring effort. Our approach allows balancing between those two characteristics. This makes it an interesting option for the monitoring function of self-adaptive systems because for them usually very short-lived phenomena are not relevant. Y1 - 2019 SN - 978-1-7281-2731-6 U6 - https://doi.org/10.1109/SASO.2019.00012 SN - 1949-3673 SP - 17 EP - 22 PB - IEEE CY - New York ER - TY - GEN A1 - Bruechner, Dominik A1 - Renz, Jan A1 - Klingbeil, Mandy T1 - Creating a Framework for User-Centered Development and Improvement of Digital Education T2 - Scale N2 - We investigate how the technology acceptance and learning experience of the digital education platform HPI Schul-Cloud (HPI School Cloud) for German secondary school teachers can be improved by proposing a user-centered research and development framework. We highlight the importance of developing digital learning technologies in a user-centered way to take differences in the requirements of educators and students into account. We suggest applying qualitative and quantitative methods to build a solid understanding of a learning platform's users, their needs, requirements, and their context of use. After concept development and idea generation of features and areas of opportunity based on the user research, we emphasize on the application of a multi-attribute utility analysis decision-making framework to prioritize ideas rationally, taking results of user research into account. Afterward, we recommend applying the principle build-learn-iterate to build prototypes in different resolutions while learning from user tests and improving the selected opportunities. Last but not least, we propose an approach for continuous short- and long-term user experience controlling and monitoring, extending existing web- and learning analytics metrics. KW - learning platform KW - user experience KW - evaluation KW - HPI Schul-Cloud KW - user research framework KW - user-centered design Y1 - 2019 SN - 978-1-4503-6804-9 U6 - https://doi.org/10.1145/3330430.3333644 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Bilo, Davide A1 - Friedrich, Tobias A1 - Lenzner, Pascal A1 - Melnichenko, Anna T1 - Geometric Network Creation Games T2 - SPAA '19: The 31st ACM Symposium on Parallelism in Algorithms and Architectures N2 - Network Creation Games are a well-known approach for explaining and analyzing the structure, quality and dynamics of real-world networks like the Internet and other infrastructure networks which evolved via the interaction of selfish agents without a central authority. In these games selfish agents which correspond to nodes in a network strategically buy incident edges to improve their centrality. However, past research on these games has only considered the creation of networks with unit-weight edges. In practice, e.g. when constructing a fiber-optic network, the choice of which nodes to connect and also the induced price for a link crucially depends on the distance between the involved nodes and such settings can be modeled via edge-weighted graphs. We incorporate arbitrary edge weights by generalizing the well-known model by Fabrikant et al. [PODC'03] to edge-weighted host graphs and focus on the geometric setting where the weights are induced by the distances in some metric space. In stark contrast to the state-of-the-art for the unit-weight version, where the Price of Anarchy is conjectured to be constant and where resolving this is a major open problem, we prove a tight non-constant bound on the Price of Anarchy for the metric version and a slightly weaker upper bound for the non-metric case. Moreover, we analyze the existence of equilibria, the computational hardness and the game dynamics for several natural metrics. The model we propose can be seen as the game-theoretic analogue of a variant of the classical Network Design Problem. Thus, low-cost equilibria of our game correspond to decentralized and stable approximations of the optimum network design. KW - Network creation games KW - edge-weighted networks KW - price of anarchy KW - Nash equilibrium KW - game dynamics KW - computational hardness Y1 - 2019 SN - 978-1-4503-6184-2 U6 - https://doi.org/10.1145/3323165.3323199 SP - 323 EP - 332 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Gonzalez-Lopez, Fernanda A1 - Pufahl, Luise T1 - A Landscape for Case Models T2 - Enterprise, Business-Process and Information Systems Modeling N2 - Case Management is a paradigm to support knowledge-intensive processes. The different approaches developed for modeling these types of processes tend to result in scattered models due to the low abstraction level at which the inherently complex processes are therein represented. Thus, readability and understandability is more challenging than that of traditional process models. By reviewing existing proposals in the field of process overviews and case models, this paper extends a case modeling language - the fragment-based Case Management (fCM) language - with the goal of modeling knowledge-intensive processes from a higher abstraction level - to generate a so-called fCM landscape. This proposal is empirically evaluated via an online experiment. Results indicate that interpreting an fCM landscape might be more effective and efficient than interpreting an informationally equivalent case model. KW - Case Management KW - Process landscape KW - Process map KW - Process architecture KW - Process model Y1 - 2019 SN - 978-3-030-20618-5 SN - 978-3-030-20617-8 U6 - https://doi.org/10.1007/978-3-030-20618-5_6 SN - 1865-1348 VL - 352 SP - 87 EP - 102 PB - Springer CY - Berlin ER - TY - JOUR A1 - Schlosser, Rainer A1 - Walther, Carsten A1 - Boissier, Martin A1 - Uflacker, Matthias T1 - Automated repricing and ordering strategies in competitive markets JF - AI communications : AICOM ; the European journal on artificial intelligence N2 - Merchants on modern e-commerce platforms face a highly competitive environment. They compete against each other using automated dynamic pricing and ordering strategies. Successfully managing both inventory levels as well as offer prices is a challenging task as (i) demand is uncertain, (ii) competitors strategically interact, and (iii) optimized pricing and ordering decisions are mutually dependent. We show how to derive optimized data-driven pricing and ordering strategies which are based on demand learning techniques and efficient dynamic optimization models. We verify the superior performance of our self-adaptive strategies by comparing them to different rule-based as well as data-driven strategies in duopoly and oligopoly settings. Further, to study and to optimize joint dynamic ordering and pricing strategies on online marketplaces, we built an interactive simulation platform. To be both flexible and scalable, the platform has a microservice-based architecture and allows handling dozens of competing merchants and streams of consumers with configurable characteristics. KW - Dynamic pricing KW - inventory management KW - demand learning KW - oligopoly competition KW - e-commerce Y1 - 2019 U6 - https://doi.org/10.3233/AIC-180603 SN - 0921-7126 SN - 1875-8452 VL - 32 IS - 1 SP - 15 EP - 29 PB - IOS Press CY - Amsterdam ER - TY - GEN A1 - Halfpap, Stefan A1 - Schlosser, Rainer T1 - Workload-Driven Fragment Allocation for Partially Replicated Databases Using Linear Programming T2 - 2019 IEEE 35th International Conference on Data Engineering (ICDE) N2 - In replication schemes, replica nodes can process read-only queries on snapshots of the master node without violating transactional consistency. By analyzing the workload, we can identify query access patterns and replicate data depending to its access frequency. In this paper, we define a linear programming (LP) model to calculate the set of partial replicas with the lowest overall memory capacity while evenly balancing the query load. Furthermore, we propose a scalable decomposition heuristic to calculate solutions for larger problem sizes. While guaranteeing the same performance as state-of-the-art heuristics, our decomposition approach calculates allocations with up to 23% lower memory footprint for the TPC-H benchmark. KW - database replication KW - allocation problem KW - linear programming Y1 - 2019 SN - 978-1-5386-7474-1 SN - 978-1-5386-7475-8 U6 - https://doi.org/10.1109/ICDE.2019.00188 SN - 1084-4627 SN - 2375-026X SN - 1063-6382 SP - 1746 EP - 1749 PB - IEEE CY - New York ER - TY - GEN A1 - Halfpap, Stefan A1 - Schlosser, Rainer T1 - A Comparison of Allocation Algorithms for Partially Replicated Databases T2 - 2019 IEEE 35th International Conference on Data Engineering (ICDE) N2 - Increasing demand for analytical processing capabilities can be managed by replication approaches. However, to evenly balance the replicas' workload shares while at the same time minimizing the data replication factor is a highly challenging allocation problem. As optimal solutions are only applicable for small problem instances, effective heuristics are indispensable. In this paper, we test and compare state-of-the-art allocation algorithms for partial replication. By visualizing and exploring their (heuristic) solutions for different benchmark workloads, we are able to derive structural insights and to detect an algorithm's strengths as well as its potential for improvement. Further, our application enables end-to-end evaluations of different allocations to verify their theoretical performance. Y1 - 2019 SN - 978-1-5386-7474-1 SN - 978-1-5386-7475-8 U6 - https://doi.org/10.1109/ICDE.2019.00226 SN - 1084-4627 SN - 2375-026X SN - 1063-6382 SP - 2008 EP - 2011 PB - IEEE CY - New York ER - TY - JOUR A1 - Friedrich, Tobias A1 - Krejca, Martin Stefan A1 - Rothenberger, Ralf A1 - Arndt, Tobias A1 - Hafner, Danijar A1 - Kellermeier, Thomas A1 - Krogmann, Simon A1 - Razmjou, Armin T1 - Routing for on-street parking search using probabilistic data JF - AI communications : AICOM ; the European journal on artificial intelligence N2 - A significant percentage of urban traffic is caused by the search for parking spots. One possible approach to improve this situation is to guide drivers along routes which are likely to have free parking spots. The task of finding such a route can be modeled as a probabilistic graph problem which is NP-complete. Thus, we propose heuristic approaches for solving this problem and evaluate them experimentally. For this, we use probabilities of finding a parking spot, which are based on publicly available empirical data from TomTom International B.V. Additionally, we propose a heuristic that relies exclusively on conventional road attributes. Our experiments show that this algorithm comes close to the baseline by a factor of 1.3 in our cost measure. Last, we complement our experiments with results from a field study, comparing the success rates of our algorithms against real human drivers. KW - Parking search KW - probabilistic routing KW - constrained optimization KW - field study Y1 - 2019 U6 - https://doi.org/10.3233/AIC-180574 SN - 0921-7126 SN - 1875-8452 VL - 32 IS - 2 SP - 113 EP - 124 PB - IOS Press CY - Amsterdam ER - TY - GEN A1 - Chakraborty, Dhiman A1 - Hammer, Christian A1 - Bugiel, Sven T1 - Secure Multi-Execution in Android T2 - Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing N2 - Mobile operating systems, such as Google's Android, have become a fixed part of our daily lives and are entrusted with a plethora of private information. Congruously, their data protection mechanisms have been improved steadily over the last decade and, in particular, for Android, the research community has explored various enhancements and extensions to the access control model. However, the vast majority of those solutions has been concerned with controlling the access to data, but equally important is the question of how to control the flow of data once released. Ignoring control over the dissemination of data between applications or between components of the same app, opens the door for attacks, such as permission re-delegation or privacy-violating third-party libraries. Controlling information flows is a long-standing problem, and one of the most recent and practical-oriented approaches to information flow control is secure multi-execution. In this paper, we present Ariel, the design and implementation of an IFC architecture for Android based on the secure multi-execution of apps. Ariel demonstrably extends Android's system with support for executing multiple instances of apps, and it is equipped with a policy lattice derived from the protection levels of Android's permissions as well as an I/O scheduler to achieve control over data flows between application instances. We demonstrate how secure multi-execution with Ariel can help to mitigate two prominent attacks on Android, permission re-delegations and malicious advertisement libraries. KW - Android KW - Information flow control KW - secure multi-execution Y1 - 2019 SN - 978-1-4503-5933-7 U6 - https://doi.org/10.1145/3297280.3297469 SP - 1934 EP - 1943 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Welearegai, Gebrehiwet B. A1 - Schlueter, Max A1 - Hammer, Christian T1 - Static security evaluation of an industrial web application T2 - Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing N2 - JavaScript is the most popular programming language for web applications. Static analysis of JavaScript applications is highly challenging due to its dynamic language constructs and event-driven asynchronous executions, which also give rise to many security-related bugs. Several static analysis tools to detect such bugs exist, however, research has not yet reported much on the precision and scalability trade-off of these analyzers. As a further obstacle, JavaScript programs structured in Node. js modules need to be collected for analysis, but existing bundlers are either specific to their respective analysis tools or not particularly suitable for static analysis. KW - JavaScript KW - WALA KW - SAFE KW - comparison Y1 - 2019 SN - 978-1-4503-5933-7 U6 - https://doi.org/10.1145/3297280.3297471 SP - 1952 EP - 1961 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Friedrich, Tobias T1 - From graph theory to network science BT - the natural emergence of hyperbolicity (Tutorial) T2 - 36th International Symposium on Theoretical Aspects of Computer Science (STACS 2019) N2 - Network science is driven by the question which properties large real-world networks have and how we can exploit them algorithmically. In the past few years, hyperbolic graphs have emerged as a very promising model for scale-free networks. The connection between hyperbolic geometry and complex networks gives insights in both directions: (1) Hyperbolic geometry forms the basis of a natural and explanatory model for real-world networks. Hyperbolic random graphs are obtained by choosing random points in the hyperbolic plane and connecting pairs of points that are geometrically close. The resulting networks share many structural properties for example with online social networks like Facebook or Twitter. They are thus well suited for algorithmic analyses in a more realistic setting. (2) Starting with a real-world network, hyperbolic geometry is well-suited for metric embeddings. The vertices of a network can be mapped to points in this geometry, such that geometric distances are similar to graph distances. Such embeddings have a variety of algorithmic applications ranging from approximations based on efficient geometric algorithms to greedy routing solely using hyperbolic coordinates for navigation decisions. KW - Graph Theory KW - Graph Algorithms KW - Network Science KW - Hyperbolic Geometry Y1 - 2019 SN - 978-3-95977-100-9 U6 - https://doi.org/10.4230/LIPIcs.STACS.2019.5 VL - 126 PB - Schloss Dagstuhl-Leibniz-Zentrum für Informatik CY - Dragstuhl ER - TY - GEN A1 - Brand, Thomas A1 - Giese, Holger Burkhard T1 - Towards Generic Adaptive Monitoring T2 - 2018 IEEE 12th International Conference on Self-Adaptive and Self-Organizing Systems (SASO) N2 - Monitoring is a key prerequisite for self-adaptive software and many other forms of operating software. Monitoring relevant lower level phenomena like the occurrences of exceptions and diagnosis data requires to carefully examine which detailed information is really necessary and feasible to monitor. Adaptive monitoring permits observing a greater variety of details with less overhead, if most of the time the MAPE-K loop can operate using only a small subset of all those details. However, engineering such an adaptive monitoring is a major engineering effort on its own that further complicates the development of self-adaptive software. The proposed approach overcomes the outlined problems by providing generic adaptive monitoring via runtime models. It reduces the effort to introduce and apply adaptive monitoring by avoiding additional development effort for controlling the monitoring adaptation. Although the generic approach is independent from the monitoring purpose, it still allows for substantial savings regarding the monitoring resource consumption as demonstrated by an example. Y1 - 2019 SN - 978-1-5386-5172-8 U6 - https://doi.org/10.1109/SASO.2018.00027 SN - 1949-3673 SP - 156 EP - 161 PB - IEEE CY - New York ER - TY - GEN A1 - Richly, Keven T1 - A survey on trajectory data management for hybrid transactional and analytical workloads T2 - IEEE International Conference on Big Data (Big Data) N2 - Rapid advances in location-acquisition technologies have led to large amounts of trajectory data. This data is the foundation for a broad spectrum of services driven and improved by trajectory data mining. However, for hybrid transactional and analytical workloads, the storing and processing of rapidly accumulated trajectory data is a non-trivial task. In this paper, we present a detailed survey about state-of-the-art trajectory data management systems. To determine the relevant aspects and requirements for such systems, we developed a trajectory data mining framework, which summarizes the different steps in the trajectory data mining process. Based on the derived requirements, we analyze different concepts to store, compress, index, and process spatio-temporal data. There are various trajectory management systems, which are optimized for scalability, data footprint reduction, elasticity, or query performance. To get a comprehensive overview, we describe and compare different exciting systems. Additionally, the observed similarities in the general structure of different systems are consolidated in a general blueprint of trajectory management systems. KW - Trajectory Data Management KW - Spatio-Temporal Data KW - Survey Y1 - 2019 SN - 978-1-5386-5035-6 U6 - https://doi.org/10.1109/BigData.2018.8622394 SN - 2639-1589 SP - 562 EP - 569 PB - IEEE CY - New York ER - TY - GEN A1 - Richly, Keven T1 - Leveraging spatio-temporal soccer data to define a graphical query language for game recordings T2 - IEEE International Conference on Big Data (Big Data) N2 - For professional soccer clubs, performance and video analysis are an integral part of the preparation and post-processing of games. Coaches, scouts, and video analysts extract information about strengths and weaknesses of their team as well as opponents by manually analyzing video recordings of past games. Since video recordings are an unstructured data source, it is a complex and time-intensive task to find specific game situations and identify similar patterns. In this paper, we present a novel approach to detect patterns and situations (e.g., playmaking and ball passing of midfielders) based on trajectory data. The application uses the metaphor of a tactic board to offer a graphical query language. With this interactive tactic board, the user can model a game situation or mark a specific situation in the video recording for which all matching occurrences in various games are immediately displayed, and the user can directly jump to the corresponding game scene. Through the additional visualization of key performance indicators (e.g.,the physical load of the players), the user can get a better overall assessment of situations. With the capabilities to find specific game situations and complex patterns in video recordings, the interactive tactic board serves as a useful tool to improve the video analysis process of professional sports teams. KW - Spatio-temporal data analysis KW - soccer analytics KW - graphical query language Y1 - 2019 SN - 978-1-5386-5035-6 U6 - https://doi.org/10.1109/BigData.2018.8622159 SN - 2639-1589 SP - 3456 EP - 3463 PB - IEEE CY - New York ER - TY - JOUR A1 - Yousfi, Alaaeddine A1 - Batoulis, Kimon A1 - Weske, Mathias T1 - Achieving Business Process Improvement via Ubiquitous Decision-Aware Business Processes JF - ACM Transactions on Internet Technology N2 - Business process improvement is an endless challenge for many organizations. As long as there is a process, it must he improved. Nowadays, improvement initiatives are driven by professionals. This is no longer practical because people cannot perceive the enormous data of current business environments. Here, we introduce ubiquitous decision-aware business processes. They pervade the physical space, analyze the ever-changing environments, and make decisions accordingly. We explain how they can be built and used for improvement. Our approach can be a valuable improvement option to alleviate the workload of participants by helping focus on the crucial rather than the menial tasks. KW - Business process improvement KW - ubiquitous decision-aware business process KW - ubiquitous decisions KW - context KW - uBPMN KW - DMN Y1 - 2019 U6 - https://doi.org/10.1145/3298986 SN - 1533-5399 SN - 1557-6051 VL - 19 IS - 1 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Brinkmann, Maik A1 - Heine, Moreen T1 - Can Blockchain Leverage for New Public Governance? BT - a Conceptual Analysis on Process Level T2 - Proceedings of the 12th International Conference on Theory and Practice of Electronic Governance N2 - New Public Governance (NPG) as a paradigm for collaborative forms of public service delivery and Blockchain governance are trending topics for researchers and practitioners alike. Thus far, each topic has, on the whole, been discussed separately. This paper presents the preliminary results of ongoing research which aims to shed light on the more concrete benefits of Blockchain for the purpose of NPG. For the first time, a conceptual analysis is conducted on process level to spot benefits and limitations of Blockchain-based governance. Per process element, Blockchain key characteristics are mapped to functional aspects of NPG from a governance perspective. The preliminary results show that Blockchain offers valuable support for governments seeking methods to effectively coordinate co-producing networks. However, the extent of benefits of Blockchain varies across the process elements. It becomes evident that there is a need for off-chain processes. It is, therefore, argued in favour of intensifying research on off-chain governance processes to better understand the implications for and influences on on-chain governance. KW - Blockchain KW - New Public Governance KW - Blockchain Governance KW - Co-production KW - Conceptual Fit KW - Blockchain-enabled Governance Y1 - 2019 SN - 978-1-4503-6644-1 U6 - https://doi.org/10.1145/3326365.3326409 SP - 338 EP - 341 PB - Association for Computing Machinery CY - New York ER - TY - THES A1 - Batoulis, Kimon T1 - Sound integration of process and decision models T1 - Korrekte Integration von Prozess- und Entscheidungsmodellen N2 - Business process management is an established technique for business organizations to manage and support their processes. Those processes are typically represented by graphical models designed with modeling languages, such as the Business Process Model and Notation (BPMN). Since process models do not only serve the purpose of documentation but are also a basis for implementation and automation of the processes, they have to satisfy certain correctness requirements. In this regard, the notion of soundness of workflow nets was developed, that can be applied to BPMN process models in order to verify their correctness. Because the original soundness criteria are very restrictive regarding the behavior of the model, different variants of the soundness notion have been developed for situations in which certain violations are not even harmful. All of those notions do only consider the control-flow structure of a process model, however. This poses a problem, taking into account the fact that with the recent release and the ongoing development of the Decision Model and Notation (DMN) standard, an increasing number of process models are complemented by respective decision models. DMN is a dedicated modeling language for decision logic and separates the concerns of process and decision logic into two different models, process and decision models respectively. Hence, this thesis is concerned with the development of decisionaware soundness notions, i.e., notions of soundness that build upon the original soundness ideas for process models, but additionally take into account complementary decision models. Similar to the various notions of workflow net soundness, this thesis investigates different notions of decision soundness that can be applied depending on the desired degree of restrictiveness. Since decision tables are a standardized means of DMN to represent decision logic, this thesis also puts special focus on decision tables, discussing how they can be translated into an unambiguous format and how their possible output values can be efficiently determined. Moreover, a prototypical implementation is described that supports checking a basic version of decision soundness. The decision soundness notions were also empirically evaluated on models from participants of an online course on process and decision modeling as well as from a process management project of a large insurance company. The evaluation demonstrates that violations of decision soundness indeed occur and can be detected with our approach. N2 - Das Prozessmanagement ist eine etablierte Methode für Unternehmen zur Verwaltung und Unterstützung ihrer Geschäftsprozesse. Solche Prozesse werden typischerweise durch graphische Modelle dargestellt, welche mit Modellierungssprachen wie etwa der Business Process Model and Notation (BPMN) erstellt werden. Da Prozessmodelle nicht nur der Dokumentation der Prozesse dienen, sondern auch die Grundlage für deren Implementierung und Automatisierung sind, müssen sie bestimmte Korrektheitsanforderungen erfüllen. In dieser Hinsicht wurde der Begriff der Soundness einesWorkflow-Netzes entwickelt, welcher auch auf BPMN-Prozessmodelle angewendet werden kann, um deren Korrektheit zu prüfen. Da die ursprünglichen Soundness-Kriterien sehr restriktiv bezüglich des Verhaltens des Modells sind, wurden zudem Varianten des Soundness-Begriffs entwickelt. Diese können in Situationen verwendet werden, in denen bestimmte Verletzungen der Kriterien tolerabel sind. Diese Soundness-Begriffe berücksichtigen allerdings ausschließlich den Kontrollfluss der Prozessmodelle. Dies stellt ein Problem dar, weil viele Prozessmodelle heutzutage durch Entscheidungsmodelle ergänzt werden. In diesem Kontext ist die Decision Model and Notation (DMN) eine dedizierte Sprache zur Modellierung von Entscheidungen und unterstüzt die Trennung von Kontrollfluss- und Entscheidungslogik. Die vorliegende Dissertation befasst sich daher mit der Entwicklung von erweiterten Soundness-Begriffen, die sowohl Prozess- als auch Entscheidungsmodelle berücksichtigen. Ähnlich zu den bestehenden Soundness-Varianten, werden in dieser Arbeit Varianten des erweiterten Soundness-Begriffs untersucht, die je nach gewünschtem Restriktionsgrad angewendet werden können. Da Entscheidungstabellen eine in der DMN standadisierte Form sind, um Entscheidungslogik auszudrücken, fokussiert sich diese Arbeit inbesondere auf Entscheidungstabellen. So wird diskutiert wie DMN-Tabellen in ein eindeutiges Format übersetzt werden können und wie sich deren möglichen Rückgabewerte effizient bestimmen lassen. Ferner beschreibt die Arbeit eine prototypische Implementierung, die das Prüfen einer elementaren Variante des erweiterten Soundness-Begriffs erlaubt. Die Begriffe wurden außerdem empirisch evaluiert. Dazu dienten zum einen Modelle von Teilnehmern eines Online-Kurses zur Prozess- und Entscheidungsmodellierung. Zum anderen wurden Modelle eines Versicherungsunternehmens analysiert. Die Evaluierung zeigt, das Verstöße gegen den erweiterten Soundness-Begriff in der Tat auftreten und durch den hier beschriebenen Ansatz erkannt werden können. KW - decision-aware process models KW - soundness KW - decision soundness KW - formal verification KW - entscheidungsbewusste Prozessmodelle KW - Korrektheit KW - Entscheidungskorrektheit KW - formale Verifikation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-437386 ER - TY - JOUR A1 - Dombrowski, Sebastian A1 - Ermakova, Tatiana A1 - Fabian, Benjamin T1 - Graph-based analysis of cloud connectivity at the internet protocol level JF - International Journal of Communication Networks and Distributed Systems (IJCNDS) N2 - Internet connectivity of cloud services is of exceptional importance for both their providers and consumers. This article demonstrates the outlines of a method for measuring cloud-service connectivity at the internet protocol level from a client's perspective. For this, we actively collect connectivity data via traceroute measurements from PlanetLab to several major cloud services. Furthermore, we construct graph models from the collected data, and analyse the connectivity of the services based on important graph-based measures. Then, random and targeted node removal attacks are simulated, and the corresponding vulnerability of cloud services is evaluated. Our results indicate that cloud service hosts are, on average, much better connected than average hosts. However, when interconnecting nodes are removed in a targeted manner, cloud connectivity is dramatically reduced. KW - cloud computing KW - connectivity KW - availability KW - reliability KW - internet topology KW - graph analysis KW - complex networks Y1 - 2019 U6 - https://doi.org/10.1504/IJCNDS.2019.100644 SN - 1754-3916 SN - 1754-3924 VL - 23 IS - 1 SP - 117 EP - 142 PB - Inderscience Enterprises Ltd CY - Geneva ER - TY - THES A1 - Groß, Sascha T1 - Detecting and mitigating information flow threats in Android OS Y1 - 2019 ER - TY - GEN A1 - Bin Tareaf, Raad A1 - Berger, Philipp A1 - Hennig, Patrick A1 - Meinel, Christoph T1 - Personality exploration system for online social networks BT - Facebook brands as a use case T2 - 2018 IEEE/WIC/ACM International Conference on Web Intelligence (WI) N2 - User-generated content on social media platforms is a rich source of latent information about individual variables. Crawling and analyzing this content provides a new approach for enterprises to personalize services and put forward product recommendations. In the past few years, brands made a gradual appearance on social media platforms for advertisement, customers support and public relation purposes and by now it became a necessity throughout all branches. This online identity can be represented as a brand personality that reflects how a brand is perceived by its customers. We exploited recent research in text analysis and personality detection to build an automatic brand personality prediction model on top of the (Five-Factor Model) and (Linguistic Inquiry and Word Count) features extracted from publicly available benchmarks. The proposed model reported significant accuracy in predicting specific personality traits form brands. For evaluating our prediction results on actual brands, we crawled the Facebook API for 100k posts from the most valuable brands' pages in the USA and we visualize exemplars of comparison results and present suggestions for future directions. KW - Big Five Model KW - Brand Personality KW - Personality Prediction KW - Machine Learning KW - Social Media Analysis Y1 - 2019 SN - 978-1-5386-7325-6 U6 - https://doi.org/10.1109/WI.2018.00-76 SP - 301 EP - 309 PB - IEEE CY - New York ER - TY - GEN A1 - Bender, Benedict A1 - Grum, Marcus A1 - Gronau, Norbert A1 - Alfa, Attahiru A1 - Maharaj, B. T. T1 - Design of a worldwide simulation system for distributed cyber-physical production networks T2 - 2019 IEEE International Conference on Engineering, Technology and Innovation (ICE/ITMC) N2 - Modern production infrastructures of globally operating companies usually consist of multiple distributed production sites. While the organization of individual sites consisting of Industry 4.0 components itself is demanding, new questions regarding the organization and allocation of resources emerge considering the total production network. In an attempt to face the challenge of efficient distribution and processing both within and across sites, we aim to provide a hybrid simulation approach as a first step towards optimization. Using hybrid simulation allows us to include real and simulated concepts and thereby benchmark different approaches with reasonable effort. A simulation concept is conceptualized and demonstrated qualitatively using a global multi-site example. KW - production networks KW - geographical distribution KW - task realization strategies KW - Industry 4.0 KW - simulation KW - evaluation Y1 - 2019 SN - 978-1-7281-3401-7 SN - 978-1-7281-3402-4 U6 - https://doi.org/10.1109/ICE.2019.8792609 SN - 2334-315X PB - IEEE CY - New York ER - TY - GEN A1 - Ullrich, Andre A1 - Enke, Judith A1 - Teichmann, Malte A1 - Kress, Antonio A1 - Gronau, Norbert T1 - Audit - and then what? BT - a roadmap for digitization of learning factories T2 - Procedia Manufacturing N2 - Current trends such as digital transformation, Internet of Things, or Industry 4.0 are challenging the majority of learning factories. Regardless of whether a conventional learning factory, a model factory, or a digital learning factory, traditional approaches such as the monotonous execution of specific instructions don‘t suffice the learner’s needs, market requirements as well as especially current technological developments. Contemporary teaching environments need a clear strategy, a road to follow for being able to successfully cope with the changes and develop towards digitized learning factories. This demand driven necessity of transformation leads to another obstacle: Assessing the status quo and developing and implementing adequate action plans. Within this paper, details of a maturity-based audit of the hybrid learning factory in the Research and Application Centre Industry 4.0 and a thereof derived roadmap for the digitization of a learning factory are presented. KW - Audit KW - Digitization KW - Learning Factory KW - Roadmap Y1 - 2019 U6 - https://doi.org/10.1016/j.promfg.2019.03.025 SN - 2351-9789 VL - 31 SP - 162 EP - 168 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Teichmann, Malte A1 - Ullrich, Andre A1 - Gronau, Norbert T1 - Subject-oriented learning BT - a new perspective for vocational training in learning factories T2 - Procedia Manufacturing N2 - The transformation to a digitized company changes not only the work but also social context for the employees and requires inter alia new knowledge and skills from them. Additionally, individual action problems arise. This contribution proposes the subject-oriented learning theory, in which the employees´ action problems are the starting point of training activities in learning factories. In this contribution, the subject-oriented learning theory is exemplified and respective advantages for vocational training in learning factories are pointed out both theoretically and practically. Thereby, especially the individual action problems of learners and the infrastructure are emphasized as starting point for learning processes and competence development. KW - Subject-oriented learning KW - action problems KW - vocational training KW - learning factories Y1 - 2019 U6 - https://doi.org/10.1016/j.promfg.2019.03.012 SN - 2351-9789 VL - 31 SP - 72 EP - 78 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Perscheid, Cindy A1 - Grasnick, Bastien A1 - Uflacker, Matthias T1 - Integrative Gene Selection on Gene Expression Data BT - Providing Biological Context to Traditional Approaches JF - Journal of Integrative Bioinformatics N2 - The advance of high-throughput RNA-Sequencing techniques enables researchers to analyze the complete gene activity in particular cells. From the insights of such analyses, researchers can identify disease-specific expression profiles, thus understand complex diseases like cancer, and eventually develop effective measures for diagnosis and treatment. The high dimensionality of gene expression data poses challenges to its computational analysis, which is addressed with measures of gene selection. Traditional gene selection approaches base their findings on statistical analyses of the actual expression levels, which implies several drawbacks when it comes to accurately identifying the underlying biological processes. In turn, integrative approaches include curated information on biological processes from external knowledge bases during gene selection, which promises to lead to better interpretability and improved predictive performance. Our work compares the performance of traditional and integrative gene selection approaches. Moreover, we propose a straightforward approach to integrate external knowledge with traditional gene selection approaches. We introduce a framework enabling the automatic external knowledge integration, gene selection, and evaluation. Evaluation results prove our framework to be a useful tool for evaluation and show that integration of external knowledge improves overall analysis results. KW - Gene Expression Data Analysis KW - Integrative Gene Selection KW - Pattern Recognition KW - Prior Knowledge KW - Knowledge Bases Y1 - 2019 U6 - https://doi.org/10.1515/jib-2018-0064 SN - 1613-4516 VL - 16 IS - 1 PB - De Gruyter CY - Berlin ER - TY - GEN A1 - Kovacs, Robert A1 - Ion, Alexandra A1 - Lopes, Pedro A1 - Oesterreich, Tim A1 - Filter, Johannes A1 - Otto, Philip A1 - Arndt, Tobias A1 - Ring, Nico A1 - Witte, Melvin A1 - Synytsia, Anton A1 - Baudisch, Patrick T1 - TrussFormer BT - 3D Printing Large Kinetic Structures T2 - The 31st Annual ACM Symposium on User Interface Software and Technology N2 - We present TrussFormer, an integrated end-to-end system that allows users to 3D print large-scale kinetic structures, i.e., structures that involve motion and deal with dynamic forces. TrussFormer builds on TrussFab, from which it inherits the ability to create static large-scale truss structures from 3D printed connectors and PET bottles. TrussFormer adds movement to these structures by placing linear actuators into them: either manually, wrapped in reusable components called assets, or by demonstrating the intended movement. TrussFormer verifies that the resulting structure is mechanically sound and will withstand the dynamic forces resulting from the motion. To fabricate the design, TrussFormer generates the underlying hinge system that can be printed on standard desktop 3D printers. We demonstrate TrussFormer with several example objects, including a 6-legged walking robot and a 4m-tall animatronics dinosaur with 5 degrees of freedom. KW - fabrication KW - 3D printing KW - variable geometry truss KW - large-scale mechanism Y1 - 2019 SN - 978-1-4503-5971-9 U6 - https://doi.org/10.1145/3290607.3311766 PB - Association for Computing Machinery CY - New York ER - TY - THES A1 - Krejca, Martin Stefan T1 - Theoretical analyses of univariate estimation-of-distribution algorithms N2 - Optimization is a core part of technological advancement and is usually heavily aided by computers. However, since many optimization problems are hard, it is unrealistic to expect an optimal solution within reasonable time. Hence, heuristics are employed, that is, computer programs that try to produce solutions of high quality quickly. One special class are estimation-of-distribution algorithms (EDAs), which are characterized by maintaining a probabilistic model over the problem domain, which they evolve over time. In an iterative fashion, an EDA uses its model in order to generate a set of solutions, which it then uses to refine the model such that the probability of producing good solutions is increased. In this thesis, we theoretically analyze the class of univariate EDAs over the Boolean domain, that is, over the space of all length-n bit strings. In this setting, the probabilistic model of a univariate EDA consists of an n-dimensional probability vector where each component denotes the probability to sample a 1 for that position in order to generate a bit string. My contribution follows two main directions: first, we analyze general inherent properties of univariate EDAs. Second, we determine the expected run times of specific EDAs on benchmark functions from theory. In the first part, we characterize when EDAs are unbiased with respect to the problem encoding. We then consider a setting where all solutions look equally good to an EDA, and we show that the probabilistic model of an EDA quickly evolves into an incorrect model if it is always updated such that it does not change in expectation. In the second part, we first show that the algorithms cGA and MMAS-fp are able to efficiently optimize a noisy version of the classical benchmark function OneMax. We perturb the function by adding Gaussian noise with a variance of σ², and we prove that the algorithms are able to generate the true optimum in a time polynomial in σ² and the problem size n. For the MMAS-fp, we generalize this result to linear functions. Further, we prove a run time of Ω(n log(n)) for the algorithm UMDA on (unnoisy) OneMax. Last, we introduce a new algorithm that is able to optimize the benchmark functions OneMax and LeadingOnes both in O(n log(n)), which is a novelty for heuristics in the domain we consider. N2 - Optimierung ist ein Hauptbestandteil technologischen Fortschritts und oftmals computergestützt. Da viele Optimierungsprobleme schwer sind, ist es jedoch unrealistisch, eine optimale Lösung in angemessener Zeit zu erwarten. Daher werden Heuristiken verwendet, also Programme, die versuchen hochwertige Lösungen schnell zu erzeugen. Eine konkrete Klasse sind Estimation-of-Distribution-Algorithmen (EDAs), die sich durch das Entwickeln probabilistischer Modelle über dem Problemraum auszeichnen. Ein solches Modell wird genutzt, um neue Lösungen zu erzeugen und damit das Modell zu verfeinern, um im nächsten Schritt mit erhöhter Wahrscheinlichkeit bessere Lösungen zu generieren. In dieser Arbeit untersuchen wir die Klasse univariater EDAs in der booleschen Domäne, also im Raum aller Bitstrings der Länge n. Das probabilistische Modell eines univariaten EDAs besteht dann aus einem n-dimensionalen Wahrscheinlichkeitsvektor, in dem jede Komponente die Wahrscheinlichkeit angibt, eine 1 an der entsprechenden Stelle zu erzeugen. Mein Beitrag folgt zwei Hauptrichtungen: Erst untersuchen wir allgemeine inhärente Eigenschaften univariater EDAs. Danach bestimmen wir die erwartete Laufzeit gewisser EDAs auf Benchmarks aus der Theorie. Im ersten Abschnitt charakterisieren wir, wann EDAs unbefangen bezüglich der Problemcodierung sind. Dann untersuchen wir sie in einem Szenario, in dem alle Lösungen gleich gut sind, und zeigen, dass sich ihr Modell schnell zu einem falschen entwickelt, falls es immer so angepasst wird, dass sich im Erwartungswert nichts ändert. Im zweiten Abschnitt zeigen wir, dass die Algorithmen cGA und MMAS-fp eine verrauschte Variante des klassischen Benchmarks OneMax effizient optimieren, bei der eine Gaussverteilung mit Varianz σ² hinzuaddiert wird. Wir beweisen, dass die Algorithmen das wahre Optimum in polynomieller Zeit bezüglich σ² und n erzeugen. Für den MMAS-fp verallgemeinern wir dieses Ergebnis auf lineare Funktionen. Weiterhin beweisen wir eine Laufzeit von Ω(n log(n)) für den Algorithmus UMDA auf OneMax (ohne Rauschen). Zuletzt führen wir einen neuen Algorithmus ein, der die Benchmarks OneMax und LeadingOnes in O(n log(n)) optimiert, was zuvor für noch keine Heuristik gezeigt wurde. T2 - Theoretische Analysen univariater Estimation-of-Distribution-Algorithmen KW - theory KW - estimation-of-distribution algorithms KW - univariate KW - pseudo-Boolean optimization KW - run time analysis KW - Theorie KW - Estimation-of-Distribution-Algorithmen KW - univariat KW - pseudoboolesche Optimierung KW - Laufzeitanalyse Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-434870 ER - TY - GEN A1 - Kruse, Sebastian A1 - Kaoudi, Zoi A1 - Quiane-Ruiz, Jorge-Arnulfo A1 - Chawla, Sanjay A1 - Naumann, Felix A1 - Contreras-Rojas, Bertty T1 - Optimizing Cross-Platform Data Movement T2 - 2019 IEEE 35th International Conference on Data Engineering (ICDE) N2 - Data analytics are moving beyond the limits of a single data processing platform. A cross-platform query optimizer is necessary to enable applications to run their tasks over multiple platforms efficiently and in a platform-agnostic manner. For the optimizer to be effective, it must consider data movement costs across different data processing platforms. In this paper, we present the graph-based data movement strategy used by RHEEM, our open-source cross-platform system. In particular, we (i) model the data movement problem as a new graph problem, which we prove to be NP-hard, and (ii) propose a novel graph exploration algorithm, which allows RHEEM to discover multiple hidden opportunities for cross-platform data processing. Y1 - 2019 SN - 978-1-5386-7474-1 SN - 978-1-5386-7475-8 U6 - https://doi.org/10.1109/ICDE.2019.00162 SN - 1084-4627 SN - 1063-6382 SP - 1642 EP - 1645 PB - IEEE CY - New York ER - TY - GEN A1 - Andjelkovic, Marko A1 - Babic, Milan A1 - Li, Yuanqing A1 - Schrape, Oliver A1 - Krstić, Miloš A1 - Kraemer, Rolf T1 - Use of decoupling cells for mitigation of SET effects in CMOS combinational gates T2 - 2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS) N2 - This paper investigates the applicability of CMOS decoupling cells for mitigating the Single Event Transient (SET) effects in standard combinational gates. The concept is based on the insertion of two decoupling cells between the gate's output and the power/ground terminals. To verify the proposed hardening approach, extensive SPICE simulations have been performed with standard combinational cells designed in IHP's 130 nm bulk CMOS technology. Obtained simulation results have shown that the insertion of decoupling cells results in the increase of the gate's critical charge, thus reducing the gate's soft error rate (SER). Moreover, the decoupling cells facilitate the suppression of SET pulses propagating through the gate. It has been shown that the decoupling cells may be a competitive alternative to gate upsizing and gate duplication for hardening the gates with lower critical charge and multiple (3 or 4) inputs, as well as for filtering the short SET pulses induced by low-LET particles. KW - decoupling cells KW - radiation hardening KW - SET effects KW - CMOS technology KW - combinational logic Y1 - 2019 SN - 978-1-5386-9562-3 U6 - https://doi.org/10.1109/ICECS.2018.8617996 SP - 361 EP - 364 PB - IEEE CY - New York ER - TY - GEN A1 - Han van der, Aa A1 - Di Ciccio, Claudio A1 - Leopold, Henrik A1 - Reijers, Hajo A. T1 - Extracting Declarative Process Models from Natural Language T2 - Advanced Information Systems Engineering (CAISE 2019) N2 - Process models are an important means to capture information on organizational operations and often represent the starting point for process analysis and improvement. Since the manual elicitation and creation of process models is a time-intensive endeavor, a variety of techniques have been developed that automatically derive process models from textual process descriptions. However, these techniques, so far, only focus on the extraction of traditional, imperative process models. The extraction of declarative process models, which allow to effectively capture complex process behavior in a compact fashion, has not been addressed. In this paper we close this gap by presenting the first automated approach for the extraction of declarative process models from natural language. To achieve this, we developed tailored Natural Language Processing techniques that identify activities and their inter-relations from textual constraint descriptions. A quantitative evaluation shows that our approach is able to generate constraints that closely resemble those established by humans. Therefore, our approach provides automated support for an otherwise tedious and complex manual endeavor. KW - Declarative modelling KW - Natural language processing KW - Model extraction Y1 - 2019 SN - 978-3-030-21290-2 SN - 978-3-030-21289-6 U6 - https://doi.org/10.1007/978-3-030-21290-2_23 SN - 0302-9743 SN - 1611-3349 VL - 11483 SP - 365 EP - 382 PB - Springer CY - Cham ER - TY - THES A1 - Gawron, Marian T1 - Towards automated advanced vulnerability analysis N2 - The identification of vulnerabilities in IT infrastructures is a crucial problem in enhancing the security, because many incidents resulted from already known vulnerabilities, which could have been resolved. Thus, the initial identification of vulnerabilities has to be used to directly resolve the related weaknesses and mitigate attack possibilities. The nature of vulnerability information requires a collection and normalization of the information prior to any utilization, because the information is widely distributed in different sources with their unique formats. Therefore, the comprehensive vulnerability model was defined and different sources have been integrated into one database. Furthermore, different analytic approaches have been designed and implemented into the HPI-VDB, which directly benefit from the comprehensive vulnerability model and especially from the logical preconditions and postconditions. Firstly, different approaches to detect vulnerabilities in both IT systems of average users and corporate networks of large companies are presented. Therefore, the approaches mainly focus on the identification of all installed applications, since it is a fundamental step in the detection. This detection is realized differently depending on the target use-case. Thus, the experience of the user, as well as the layout and possibilities of the target infrastructure are considered. Furthermore, a passive lightweight detection approach was invented that utilizes existing information on corporate networks to identify applications. In addition, two different approaches to represent the results using attack graphs are illustrated in the comparison between traditional attack graphs and a simplistic graph version, which was integrated into the database as well. The implementation of those use-cases for vulnerability information especially considers the usability. Beside the analytic approaches, the high data quality of the vulnerability information had to be achieved and guaranteed. The different problems of receiving incomplete or unreliable information for the vulnerabilities are addressed with different correction mechanisms. The corrections can be carried out with correlation or lookup mechanisms in reliable sources or identifier dictionaries. Furthermore, a machine learning based verification procedure was presented that allows an automatic derivation of important characteristics from the textual description of the vulnerabilities. N2 - Die Erkennung von Schwachstellen ist ein schwerwiegendes Problem bei der Absicherung von modernen IT-Systemen. Mehrere Sicherheitsvorfälle hätten durch die vorherige Erkennung von Schwachstellen verhindert werden können, da in diesen Vorfällen bereits bekannte Schwachstellen ausgenutzt wurden. Der Stellenwert der Sicherheit von IT Systemen nimmt immer weiter zu, was auch mit der Aufmerksamkeit, die seit kurzem auf die Sicherheit gelegt wird, zu begründen ist. Somit nimmt auch der Stellenwert einer Schwachstellenanalyse der IT Systeme immer mehr zu, da hierdurch potenzielle Angriffe verhindert und Sicherheitslücken geschlossen werden können. Die Informationen über Sicherheitslücken liegen in verschiedenen Quellen in unterschiedlichen Formaten vor. Aus diesem Grund wird eine Normalisierungsmethode benötigt, um die verschiedenen Informationen in ein einheitliches Format zu bringen. Das damit erzeugte Datenmodell wird in der HPI-VDB gespeichert, in die auch darauf aufbauende Analyseansätze integriert wurden. Diese Analysemethoden profitieren direkt von den Eigenschaften des Datenmodells, das maschinenlesbare Vor- und Nachbedingungen enthält. Zunächst wurden verschiedene Methoden zur Erkennung von Schwachstellen in IT Systemen von durchschnittlichen Nutzern und auch in Systemen von großen Firmen entwickelt. Hierbei wird der Identifikation der installierten Programme die größte Aufmerksamkeit beigemessen, da es der grundlegende Bestandteil der Erkennung von Schwachstellen ist. Für die Ansätze wird weiterhin die Erfahrung des Nutzers und die Eigenschaften der Zielumgebung berücksichtigt. Zusätzlich wurden zwei weitere Ansätze zur Repräsentation der Ergebnisse integriert. Hierfür wurden traditionelle Angriffsgraphen mit einer vereinfachten Variante verglichen, die auch in die Datenbank integriert wurde. Des Weiteren spielt die Datenqualität eine wichtige Rolle, da die Effizienz der Analysemethoden von der Qualität der Informationen abhängt. Deshalb wurden Probleme wie Unvollständigkeit und Unzuverlässigkeit der Informationen mit verschiedenen Korrekturansätzen bewältigt. Diese Korrekturen werden mithilfe von Korrelationen und Maschinellem Lernen bewerkstelligt, wobei die automatische Ausführbarkeit eine grundlegende Anforderung darstellt. KW - IT-security KW - vulnerability KW - analysis KW - IT-Sicherheit KW - Schwachstelle KW - Analyse Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-426352 ER - TY - THES A1 - Rezaei, Mina T1 - Deep representation learning from imbalanced medical imaging N2 - Medical imaging plays an important role in disease diagnosis, treatment planning, and clinical monitoring. One of the major challenges in medical image analysis is imbalanced training data, in which the class of interest is much rarer than the other classes. Canonical machine learning algorithms suppose that the number of samples from different classes in the training dataset is roughly similar or balance. Training a machine learning model on an imbalanced dataset can introduce unique challenges to the learning problem. A model learned from imbalanced training data is biased towards the high-frequency samples. The predicted results of such networks have low sensitivity and high precision. In medical applications, the cost of misclassification of the minority class could be more than the cost of misclassification of the majority class. For example, the risk of not detecting a tumor could be much higher than referring to a healthy subject to a doctor. The current Ph.D. thesis introduces several deep learning-based approaches for handling class imbalanced problems for learning multi-task such as disease classification and semantic segmentation. At the data-level, the objective is to balance the data distribution through re-sampling the data space: we propose novel approaches to correct internal bias towards fewer frequency samples. These approaches include patient-wise batch sampling, complimentary labels, supervised and unsupervised minority oversampling using generative adversarial networks for all. On the other hand, at algorithm-level, we modify the learning algorithm to alleviate the bias towards majority classes. In this regard, we propose different generative adversarial networks for cost-sensitive learning, ensemble learning, and mutual learning to deal with highly imbalanced imaging data. We show evidence that the proposed approaches are applicable to different types of medical images of varied sizes on different applications of routine clinical tasks, such as disease classification and semantic segmentation. Our various implemented algorithms have shown outstanding results on different medical imaging challenges. N2 - Medizinische Bildanalyse spielt eine wichtige Rolle bei der Diagnose von Krankheiten, der Behandlungsplanung, und der klinischen Überwachung. Eines der großen Probleme in der medizinischen Bildanalyse ist das Vorhandensein von nicht ausbalancierten Trainingsdaten, bei denen die Anzahl der Datenpunkte der Zielklasse in der Unterzahl ist. Die Aussagen eines Modells, welches auf einem unbalancierten Datensatz trainiert wurde, tendieren dazu Datenpunkte in die Klasse mit der Mehrzahl an Trainingsdaten einzuordnen. Die Aussagen eines solchen Modells haben eine geringe Sensitivität aber hohe Genauigkeit. Im medizinischen Anwendungsbereich kann die Einordnung eines Datenpunktes in eine falsche Klasse Schwerwiegende Ergebnisse mit sich bringen. In die Nichterkennung eines Tumors Beispielsweise brigt ein viel höheres Risiko für einen Patienten, als wenn ein gesunder Patient zum Artz geschickt wird. Das Problem des Lernens unter Nutzung von nicht ausbalancierten Trainingsdaten wird erst seit Kurzem bei der Klassifizierung von Krankheiten, der Entdeckung von Tumoren und beider Segmentierung von Tumoren untersucht. In der Literatur wird hier zwischen zwei verschiedenen Ansätzen unterschieden: datenbasierte und algorithmische Ansätze. Die vorliegende Arbeit behandelt das Lernen unter Nutzung von unbalancierten medizinischen Bilddatensätzen mittels datenbasierter und algorithmischer Ansätze. Bei den datenbasierten Ansätzen ist es unser Ziel, die Datenverteilung durch gezieltes Nutzen der vorliegenden Datenbasis auszubalancieren. Dazu schlagen wir neuartige Ansätze vor, um eine ausgeglichene Einordnung der Daten aus seltenen Klassen vornehmen zu können. Diese Ansätze sind unter anderem synthesize minority class sampling, patient-wise batch normalization, und die Erstellung von komplementären Labels unter Nutzung von generative adversarial networks. Auf der Seite der algorithmischen Ansätze verändern wir den Trainingsalgorithmus, um die Tendenz in Richtung der Klasse mit der Mehrzahl an Trainingsdaten zu verringern. Dafür schlagen wir verschiedene Algorithmen im Bereich des kostenintensiven Lernens, Ensemble-Lernens und des gemeinsamen Lernens vor, um mit stark unbalancierten Trainingsdaten umgehen zu können. Wir zeigen, dass unsere vorgeschlagenen Ansätze für verschiedenste Typen von medizinischen Bildern, mit variierender Größe, auf verschiedene Anwendungen im klinischen Alltag, z. B. Krankheitsklassifizierung, oder semantische Segmentierung, anwendbar sind. Weiterhin haben unsere Algorithmen hervorragende Ergebnisse bei unterschiedlichen Wettbewerben zur medizinischen Bildanalyse gezeigt. KW - machine learning KW - deep learning KW - computer vision KW - imbalanced learning KW - medical image analysis KW - Maschinenlernen KW - tiefes Lernen KW - unbalancierter Datensatz KW - Computervision KW - medizinische Bildanalyse Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-442759 ER - TY - THES A1 - Amirkhanyan, Aragats T1 - Methods and frameworks for GeoSpatioTemporal data analytics T1 - Methoden und Frameworks für geo-raumzeitliche Datenanalysen N2 - In the era of social networks, internet of things and location-based services, many online services produce a huge amount of data that have valuable objective information, such as geographic coordinates and date time. These characteristics (parameters) in the combination with a textual parameter bring the challenge for the discovery of geospatiotemporal knowledge. This challenge requires efficient methods for clustering and pattern mining in spatial, temporal and textual spaces. In this thesis, we address the challenge of providing methods and frameworks for geospatiotemporal data analytics. As an initial step, we address the challenges of geospatial data processing: data gathering, normalization, geolocation, and storage. That initial step is the basement to tackle the next challenge -- geospatial clustering challenge. The first step of this challenge is to design the method for online clustering of georeferenced data. This algorithm can be used as a server-side clustering algorithm for online maps that visualize massive georeferenced data. As the second step, we develop the extension of this method that considers, additionally, the temporal aspect of data. For that, we propose the density and intensity-based geospatiotemporal clustering algorithm with fixed distance and time radius. Each version of the clustering algorithm has its own use case that we show in the thesis. In the next chapter of the thesis, we look at the spatiotemporal analytics from the perspective of the sequential rule mining challenge. We design and implement the framework that transfers data into textual geospatiotemporal data - data that contain geographic coordinates, time and textual parameters. By this way, we address the challenge of applying pattern/rule mining algorithms in geospatiotemporal space. As the applicable use case study, we propose spatiotemporal crime analytics -- discovery spatiotemporal patterns of crimes in publicly available crime data. The second part of the thesis, we dedicate to the application part and use case studies. We design and implement the application that uses the proposed clustering algorithms to discover knowledge in data. Jointly with the application, we propose the use case studies for analysis of georeferenced data in terms of situational and public safety awareness. N2 - Heute ist die Zeit der sozialen Netzwerke, des Internets der Dinge und der Standortbezogenen Diensten (Location-Based services). Viele Online-Dienste erzeugen eine riesige Datenmenge, die wertvolle Informationen enthält, wie z. B. geographische Koordinaten und Datum sowie Zeit. Diese Informationen (Parameter) in Kombination mit einem Textparameter stellen die Herausforderung für die Entdeckung von geo-raumzeitlichem (geospatiotemporal) Wissen dar. Diese Herausforderung erfordert effiziente Methoden zum Clustering und Pattern-Mining in räumlichen, zeitlichen und textlichen Aspekten. In dieser Dissertation stellen wir uns der Herausforderung, Methoden und Frameworks für geo-raumzeitliche Datenanalysen bereitzustellen. Im ersten Schritt gehen wir auf die Herausforderungen der Geodatenverarbeitung ein: Datenerfassung, -Normalisierung, -Ortung und -Speicherung. Dieser Schritt ist der Grundstein für die nächste Herausforderung – das geographische Clustering. Es erfordert das Entwerfen einer Methode für das Online-Clustering georeferenzierter Daten. Dieser Algorithmus kann als Serverseitiger Clustering-Algorithmus für Online-Karten verwendet werden, die massive georeferenzierte Daten visualisieren. Im zweiten Schritt entwickeln wir die Erweiterung dieser Methode, die zusätzlich den zeitlichen Aspekt der Daten berücksichtigt. Dazu schlagen wir den Dichte und Intensitätsbasierten geo-raumzeitlichen Clustering-Algorithmus mit festem Abstand und Zeitradius vor. Jede Version des Clustering-Algorithmus hat einen eigenen Anwendungsfall, den wir in dieser Doktorarbeit zeigen. Im nächsten Kapitel dieser Arbeit betrachten wir die raumzeitlich Analyse aus der Perspektive der sequentiellen Regel-Mining-Herausforderung. Wir entwerfen und implementieren ein Framework, das Daten in textliche raumzeitliche Daten umwandelt. Solche Daten enthalten geographische Koordinaten, Zeit und Textparameter. Auf diese Weise stellen wir uns der Herausforderung, Muster- / Regel-Mining-Algorithmen auf geo-raumzeitliche Daten anzuwenden. Als Anwendungsfallstudie schlagen wir raumzeitliche Verbrechensanalysen vor – Entdeckung raumzeitlicher Muster von Verbrechen in öffentlich zugänglichen Datenbanken. Im zweiten Teil der Arbeit diskutieren wir über die Anwendung und die Fallstudien. Wir entwerfen und implementieren eine Anwendungssoftware, die die vorgeschlagene Clustering-Algorithmen verwendet, um das Wissen in Daten zu entdecken. Gemeinsam mit der Anwendungssoftware betrachten wir Anwendungsbeispiele für die Analyse georeferenzierter Daten im Hinblick auf das Situationsbewusstsein. KW - geospatial data KW - data analytics KW - clustering KW - situational awareness KW - Geodaten KW - Datenanalyse KW - Clustering KW - Situationsbewusstsein Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-441685 ER - TY - THES A1 - Krentz, Konrad-Felix T1 - A Denial-of-Sleep-Resilient Medium Access Control Layer for IEEE 802.15.4 Networks T1 - Eine Denial-of-Sleep-Resiliente Mediumzugriffsschicht für IEEE-802.15.4-Netzwerke N2 - With the emergence of the Internet of things (IoT), plenty of battery-powered and energy-harvesting devices are being deployed to fulfill sensing and actuation tasks in a variety of application areas, such as smart homes, precision agriculture, smart cities, and industrial automation. In this context, a critical issue is that of denial-of-sleep attacks. Such attacks temporarily or permanently deprive battery-powered, energy-harvesting, or otherwise energy-constrained devices of entering energy-saving sleep modes, thereby draining their charge. At the very least, a successful denial-of-sleep attack causes a long outage of the victim device. Moreover, to put battery-powered devices back into operation, their batteries have to be replaced. This is tedious and may even be infeasible, e.g., if a battery-powered device is deployed at an inaccessible location. While the research community came up with numerous defenses against denial-of-sleep attacks, most present-day IoT protocols include no denial-of-sleep defenses at all, presumably due to a lack of awareness and unsolved integration problems. After all, despite there are many denial-of-sleep defenses, effective defenses against certain kinds of denial-of-sleep attacks are yet to be found. The overall contribution of this dissertation is to propose a denial-of-sleep-resilient medium access control (MAC) layer for IoT devices that communicate over IEEE 802.15.4 links. Internally, our MAC layer comprises two main components. The first main component is a denial-of-sleep-resilient protocol for establishing session keys among neighboring IEEE 802.15.4 nodes. The established session keys serve the dual purpose of implementing (i) basic wireless security and (ii) complementary denial-of-sleep defenses that belong to the second main component. The second main component is a denial-of-sleep-resilient MAC protocol. Notably, this MAC protocol not only incorporates novel denial-of-sleep defenses, but also state-of-the-art mechanisms for achieving low energy consumption, high throughput, and high delivery ratios. Altogether, our MAC layer resists, or at least greatly mitigates, all denial-of-sleep attacks against it we are aware of. Furthermore, our MAC layer is self-contained and thus can act as a drop-in replacement for IEEE 802.15.4-compliant MAC layers. In fact, we implemented our MAC layer in the Contiki-NG operating system, where it seamlessly integrates into an existing protocol stack. N2 - Mit dem Aufkommen des Internets der Dinge (IoT), werden immer mehr batteriebetriebene und energieerntende Geräte in diversen Anwendungsbereichen eingesetzt, etwa in der Heimautomatisierung, Präzisionslandwirtschaft, Industrieautomatisierung oder intelligenten Stadt. In diesem Kontext stellen sogenannte Denial-of-Sleep-Angriffe eine immer kritischer werdende Bedrohung dar. Solche Angriffe halten batteriebetriebene, energieerntende oder anderweitig energiebeschränkte Geräte zeitweise oder chronisch ab, in energiesparende Schlafmodi überzugehen. Erfolgreiche Denial-of-Sleep-Angriffe führen zumindest zu einer langen Ausfallzeit der betroffenen Geräte. Um betroffene batteriebetriebene Geräte wieder in Betrieb zu nehmen, müssen zudem deren Batterien gewechselt werden. Dies ist mühsam oder eventuell sogar unmöglich, z.B. wenn solche Geräte an unzugänglichen Orten installiert sind. Obwohl die Forschungsgemeinschaft bereits viele Denial-of-Sleep-Abwehrmechanismen vorgeschlagen hat, besitzen die meisten aktuellen IoT-Protokolle überhaupt keine Denial-of-Sleep-Abwehrmechanismen. Dies kann zum einen daran liegen, dass man des Problems noch nicht gewahr ist, aber zum anderen auch daran, dass viele Integrationsfragen bislang ungeklärt sind. Des Weiteren existieren bisher sowieso noch keine effektiven Abwehrmechanismen gegen bestimmte Denial-of-Sleep-Angriffe. Der Hauptbeitrag dieser Dissertation ist die Entwicklung einer Denial-of-Sleep-resilienten Mediumzugriffsschicht für IoT-Geräte, die via IEEE-802.15.4-Funkverbindungen kommunizieren. Die entwickelte Mediumzugriffsschicht besitzt zwei Hauptkomponenten. Die erste Hauptkomponente ist ein Denial-of-Sleep-resilientes Protokoll zur Etablierung von Sitzungsschlüsseln zwischen benachbarten IEEE-802.15.4-Knoten. Diese Sitzungsschlüssel dienen einerseits der grundlegenden Absicherung des Funkverkehrs und andererseits der Implementierung zusätzlicher Denial-of-Sleep-Abwehrmechanismen in der zweiten Hauptkomponente. Die zweite Hauptkomponente ist ein Denial-of-Sleep-resilientes Mediumzugriffsprotokoll. Bemerkenswert an diesem Mediumzugriffsprotokoll ist, dass es nicht nur neuartige Denial-of-Sleep-Abwehrmechanismen enthält, sondern auch dem Stand der Technik entsprechende Mechanismen zur Verringerung des Energieverbrauchs, zur Steigerung des Durchsatzes sowie zur Erhöhung der Zuverlässigkeit. Zusammenfassend widersteht bzw. mildert unsere Denial-of-Sleep-resiliente Mediumzugriffsschicht alle uns bekannten Denial-of-Sleep-Angriffe, die gegen sie gefahren werden können. Außerdem kann unsere Denial-of-Sleep-resiliente Mediumzugriffsschicht ohne Weiteres an Stelle von IEEE-802.15.4-konformen Mediumzugriffsschichten eingesetzt werden. Dies zeigen wir durch die nahtlose Integration unserer Mediumzugriffsschicht in den Netzwerk-Stack des Betriebssystems Contiki-NG. KW - medium access control KW - denial of sleep KW - internet of things KW - Mediumzugriffskontrolle KW - Schlafentzugsangriffe KW - Internet der Dinge Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-439301 ER - TY - BOOK A1 - Beckmann, Tom A1 - Hildebrand, Justus A1 - Jaschek, Corinna A1 - Krebs, Eva A1 - Löser, Alexander A1 - Taeumel, Marcel A1 - Pape, Tobias A1 - Fister, Lasse A1 - Hirschfeld, Robert T1 - The font engineering platform T1 - Eine Plattform für Schriftarten BT - collaborative font creation in a self-supporting programming environment BT - kollaborative Schriftartgestaltung in Einer selbsttragenden Programmierumgebung N2 - Creating fonts is a complex task that requires expert knowledge in a variety of domains. Often, this knowledge is not held by a single person, but spread across a number of domain experts. A central concept needed for designing fonts is the glyph, an elemental symbol representing a readable character. Required domains include designing glyph shapes, engineering rules to combine glyphs for complex scripts and checking legibility. This process is most often iterative and requires communication in all directions. This report outlines a platform that aims to enhance the means of communication, describes our prototyping process, discusses complex font rendering and editing in a live environment and an approach to generate code based on a user’s live-edits. N2 - Die Erstellung von Schriften ist eine komplexe Aufgabe, die Expertenwissen aus einer Vielzahl von Bereichen erfordert. Oftmals liegt dieses Wissen nicht bei einer einzigen Person, sondern bei einer Reihe von Fachleuten. Ein zentrales Konzept für die Gestaltung von Schriften ist der Glyph, ein elementares Symbol, das ein einzelnes lesbares Zeichen darstellt. Zu den erforderlichen Domänen gehören das Entwerfen der Glyphenformen, technische Regeln zur Kombination von Glyphen für komplexe Skripte und das Prüfen der Lesbarkeit. Dieser Prozess ist meist iterativ und erfordert ständige Kommunikation zwischen den Experten. Dieser Bericht skizziert eine Plattform, die darauf abzielt, die Kommunikationswege zu verbessern, beschreibt unseren Prototyping-Prozess, diskutiert komplexe Schriftrendering und -bearbeitung in einer Echtzeitumgebung und einen Ansatz zur Generierung von Code basierend auf direkter Manipulation eines Nutzers. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 128 KW - smalltalk KW - squeak KW - font rendering KW - font engineering KW - prototyping KW - Smalltalk KW - Squeak KW - Schriftrendering KW - Schriftartgestaltung KW - Prototyping Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-427487 SN - 978-3-86956-464-7 SN - 1613-5652 SN - 2191-1665 IS - 128 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Schneider, Sven A1 - Lambers, Leen A1 - Orejas, Fernando T1 - A logic-based incremental approach to graph repair T1 - Ein logikbasierter inkrementeller Ansatz für Graphreparatur N2 - Graph repair, restoring consistency of a graph, plays a prominent role in several areas of computer science and beyond: For example, in model-driven engineering, the abstract syntax of models is usually encoded using graphs. Flexible edit operations temporarily create inconsistent graphs not representing a valid model, thus requiring graph repair. Similarly, in graph databases—managing the storage and manipulation of graph data—updates may cause that a given database does not satisfy some integrity constraints, requiring also graph repair. We present a logic-based incremental approach to graph repair, generating a sound and complete (upon termination) overview of least-changing repairs. In our context, we formalize consistency by so-called graph conditions being equivalent to first-order logic on graphs. We present two kind of repair algorithms: State-based repair restores consistency independent of the graph update history, whereas deltabased (or incremental) repair takes this history explicitly into account. Technically, our algorithms rely on an existing model generation algorithm for graph conditions implemented in AutoGraph. Moreover, the delta-based approach uses the new concept of satisfaction (ST) trees for encoding if and how a graph satisfies a graph condition. We then demonstrate how to manipulate these STs incrementally with respect to a graph update. N2 - Die Reparatur von Graphen, die Wiederherstellung der Konsistenz eines Graphen, spielt in mehreren Bereichen der Informatik und darüber hinaus eine herausragende Rolle: Beispielsweise wird in der modellgetriebenen Konstruktion die abstrakte Syntax von Modellen in der Regel mithilfe von Graphen kodiert. Flexible Bearbeitungsvorgänge erstellen vorübergehend inkonsistente Diagramme, die kein gültiges Modell darstellen, und erfordern daher eine Reparatur des Diagramms. Auf ähnliche Weise können Aktualisierungen in Graphendatenbanken - die das Speichern und Bearbeiten von Graphendaten verwalten - dazu führen, dass eine bestimmte Datenbank einige Integritätsbeschränkungen nicht erfüllt und auch eine Graphreparatur erforderlich macht. Wir präsentieren einen logikbasierten inkrementellen Ansatz für die Graphreparatur, der eine solide und vollständige (nach Beendigung) Übersicht über die am wenigsten verändernden Reparaturen erstellt. In unserem Kontext formalisieren wir die Konsistenz mittels sogenannten Graphbedingungen die der Logik erster Ordnung in Graphen entsprechen. Wir stellen zwei Arten von Reparaturalgorithmen vor: Die zustandsbasierte Reparatur stellt die Konsistenz unabhängig vom Verlauf der Graphänderung wieder her, während die deltabasierte (oder inkrementelle) Reparatur diesen Verlauf explizit berücksichtigt. Technisch stützen sich unsere Algorithmen auf einen vorhandenen Modellgenerierungsalgorithmus für in AutoGraph implementierte Graphbedingungen. Darüber hinaus verwendet der deltabasierte Ansatz das neue Konzept der Erfüllungsbäume (STs) zum Kodieren, ob und wie ein Graph eine Graphbedingung erfüllt. Wir zeigen dann, wie diese STs in Bezug auf eine Graphaktualisierung inkrementell manipuliert werden. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 126 KW - nested graph conditions KW - graph repair KW - model repair KW - consistency restoration KW - verschachtelte Graphbedingungen KW - Graphreparatur KW - Modellreparatur KW - Konsistenzrestauration Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-427517 SN - 978-3-86956-462-3 SN - 1613-5652 SN - 2191-1665 IS - 126 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Giese, Holger A1 - Maximova, Maria A1 - Sakizloglou, Lucas A1 - Schneider, Sven T1 - Metric temporal graph logic over typed attributed graphs BT - extended version N2 - Graph repair, restoring consistency of a graph, plays a prominent role in several areas of computer science and beyond: For example, in model-driven engineering, the abstract syntax of models is usually encoded using graphs. Flexible edit operations temporarily create inconsistent graphs not representing a valid model, thus requiring graph repair. Similarly, in graph databases—managing the storage and manipulation of graph data—updates may cause that a given database does not satisfy some integrity constraints, requiring also graph repair. We present a logic-based incremental approach to graph repair, generating a sound and complete (upon termination) overview of least-changing repairs. In our context, we formalize consistency by so-called graph conditions being equivalent to first-order logic on graphs. We present two kind of repair algorithms: State-based repair restores consistency independent of the graph update history, whereas deltabased (or incremental) repair takes this history explicitly into account. Technically, our algorithms rely on an existing model generation algorithm for graph conditions implemented in AutoGraph. Moreover, the delta-based approach uses the new concept of satisfaction (ST) trees for encoding if and how a graph satisfies a graph condition. We then demonstrate how to manipulate these STs incrementally with respect to a graph update. N2 - Verschiedene Arten typisierter attributierter Graphen können verwendet werden, um Systemzustände aus einem breiten Bereich von Domänen darzustellen. Für dynamische Systeme können etablierte Formalismen wie die Graphtransformation ein formales Modell für die Definition von Zustandssequenzen liefern. Wir betrachten den Fall, in dem zwischen Zustandsänderungen Zeit vergehen kann, und führen eine Logik ein, die als Metric Temporal Graph Logic (MTGL) bezeichnet wird, um über solche zeitgesteuerten Graphsequenzen zu urteilen. Mit dieser Logik drücken wir Eigenschaften der Struktur und der Attribute von Zuständen sowie des Auftretens von Zuständen über die Zeit aus, die durch ihre innere Struktur miteinander verbunden sind, was bisher keine formale Logik über Graphen präzise bewerkstelligt. Erstens, basierend auf zeitgesteuerten Graphsequenzen als Modelle für die Systemevolution, definieren wir MTGL, indem wir den zeitlichen Operator bis zu einer gewissen Zeitgrenze in die etablierte Logik von (verschachtelten) Graphbedingungen integrieren. Zweitens skizzieren wir, wie eine endliche zeitgesteuerte Diagrammsequenz als einzelnes Diagramm dargestellt werden kann, das alle zeitlichen Änderungen enthält (als Diagramm mit Verlauf bezeichnet), wie die Erfüllung von MTGL-Bedingungen für ein solches Diagramm definiert werden kann, und zeigen, dass beide Darstellungen dieselben MTGL-Bedingungen erfüllen. Drittens zeigen wir, wie MTGL-Bedingungen auf (verschachtelte) Diagrammbedingungen reduziert werden können, und zeigen anhand dieser Reduzierung, dass beide zugrunde liegenden Logiken gleichermaßen aussagekräftig sind. Schließlich stellen wir eine Erweiterung des Tools AutoGraph vor, mit der die Erfüllung der MTGL-Bedingungen für zeitgesteuerte Diagrammsequenzen überprüft werden kann, indem die Erfüllung der (verschachtelten) Diagrammbedingungen überprüft wird, die unter Verwendung der vorgeschlagenen Reduzierung für das Diagramm mit dem Verlauf entsprechend dem zeitgesteuerten Diagramm erhalten wurden. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 127 KW - typisierte attributierte Graphen KW - metrisch temporale Graph Logic KW - Spezifikation von gezeiteten Graph Transformationen KW - typed attributed graphs KW - metric termporal graph logic KW - specification of timed graph transformations Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-427522 SN - 978-3-86956-463-0 SN - 1613-5652 SN - 2191-1665 IS - 127 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - THES A1 - Perlich, Anja T1 - Digital collaborative documentation in mental healthcare T1 - Digitale Mittel zur kooperativen Dokumentation im Bereich der psychischen Gesundheit N2 - With the growth of information technology, patient attitudes are shifting – away from passively receiving care towards actively taking responsibility for their well- being. Handling doctor-patient relationships collaboratively and providing patients access to their health information are crucial steps in empowering patients. In mental healthcare, the implicit consensus amongst practitioners has been that sharing medical records with patients may have an unpredictable, harmful impact on clinical practice. In order to involve patients more actively in mental healthcare processes, Tele-Board MED (TBM) allows for digital collaborative documentation in therapist-patient sessions. The TBM software system offers a whiteboard-inspired graphical user interface that allows therapist and patient to jointly take notes during the treatment session. Furthermore, it provides features to automatically reuse the digital treatment session notes for the creation of treatment session summaries and clinical case reports. This thesis presents the development of the TBM system and evaluates its effects on 1) the fulfillment of the therapist’s duties of clinical case documentation, 2) patient engagement in care processes, and 3) the therapist-patient relationship. Following the design research methodology, TBM was developed and tested in multiple evaluation studies in the domains of cognitive behavioral psychotherapy and addiction care. The results show that therapists are likely to use TBM with patients if they have a technology-friendly attitude and when its use suits the treatment context. Support in carrying out documentation duties as well as fulfilling legal requirements contributes to therapist acceptance. Furthermore, therapists value TBM as a tool to provide a discussion framework and quick access to worksheets during treatment sessions. Therapists express skepticism, however, regarding technology use in patient sessions and towards complete record transparency in general. Patients expect TBM to improve the communication with their therapist and to offer a better recall of discussed topics when taking a copy of their notes home after the session. Patients are doubtful regarding a possible distraction of the therapist and usage in situations when relationship-building is crucial. When applied in a clinical environment, collaborative note-taking with TBM encourages patient engagement and a team feeling between therapist and patient. Furthermore, it increases the patient’s acceptance of their diagnosis, which in turn is an important predictor for therapy success. In summary, TBM has a high potential to deliver more than documentation support and record transparency for patients, but also to contribute to a collaborative doctor-patient relationship. This thesis provides design implications for the development of digital collaborative documentation systems in (mental) healthcare as well as recommendations for a successful implementation in clinical practice. N2 - Die Verbreitung von Informationstechnologie kann die Rolle von Patienten verändern: weg vom passiven Erhalt ärztlicher Zuwendung hin zur eigenverantwortlichen Mitwirkung an ihrer Genesung. Wesentliche Schritte zur Ermündigung von Patienten sind eine gute Zusammenarbeit mit dem behandelnden Arzt und der Zugang zu den eigenen Akten. Unter Psychotherapeuten gibt es jedoch einen impliziten Konsens darüber, dass die Einsicht in psychiatrische Akten unvorhersehbare, nachteilige Effekte auf die klinische Praxis hervorrufen könnte. Um auch Patienten aktiver an der Erhaltung und Wiederherstellung ihrer mentalen Gesundheit zu beteiligen, ermöglicht Tele-Board MED (TBM) das gemeinschaftliche Erstellen von digitalen Notizen. Diese Dissertation beschreibt die Entwicklung des TBM Software-Systems, das es Therapeut und Patient ermöglicht, gemeinsam während der Sitzung wie auf einem Whiteboard Notizen zu machen. Außerdem bietet TBM Funktionen, um auf Grundlage der digitalen Gesprächsnotizen automatisch Sitzungsprotokolle und klinische Fallberichte zu erstellen. Methodologisch basiert die Entwicklung und Evaluierung von TBM auf dem Paradigma für Design Research. Es wurden vielfältige Studien in den Bereichen der Verhaltens- und Suchttherapie durchgeführt, um die Auswirkungen auf folgende Aspekte zu evaluieren: 1) die Erfüllung der Dokumentationspflichten von Therapeuten, 2) das Engagement von Patienten in Behandlungsprozessen und 3) die Beziehung zwischen Patient und Therapeut. Die Studien haben gezeigt, dass Therapeuten dazu geneigt sind, TBM mit ihren Patienten zu nutzen, wenn sie technologie-freundlich eingestellt sind und wenn es zum Behandlungskontext passt. Zur Akzeptanz tragen auch die schnelle Erstellung von klinischen Dokumenten sowie die Erfüllung der gesetzlichen Forderung nach Aktentransparenz bei. Weiterhin schätzen Therapeuten TBM als Werkzeug, um Therapiegespräche zu strukturieren und während der Sitzung schnell auf Arbeitsblätter zuzugreifen. Therapeuten äußerten hingegen auch Skepsis gegenüber der Technologienutzung im Patientengespräch und vollständiger Aktentransparenz. Patienten erhoffen sich von TBM eine verbesserte Kommunikation mit ihrem Therapeuten und denken, dass sie sich besser an die Gesprächsinhalte erinnern können, wenn sie eine Kopie ihrer Akte erhalten. Patienten brachten Bedenken zum Ausdruck, TBM in Situationen zu nutzen, in denen der Beziehungsaufbau im Vordergrund steht, und darüber, dass Therapeuten sich abgelenkt fühlen könnten. Als TBM im klinischen Umfeld eingesetzt wurde, wurde ein erhöhtes Patientenengagement und ein gesteigertes Teamgefühl beobachtet. Außerdem stieg bei Patienten die Akzeptanz ihrer Diagnosen, welche wiederum ein wichtiger Prädiktor für Therapieerfolg ist. Zusammenfassend lässt sich festhalten, dass TBM großes Potential hat: Über die damit mögliche Dokumentationsunterstützung und Aktentransparenz hinaus wird auch die Zusammenarbeit von Therapeut und Patient unterstützt. Diese Dissertation fasst Kriterien zur Entwicklung von gemeinschaftlichen Dokumentationssystemen in der (psychischen) Gesundheitsfürsorge sowie Empfehlungen für eine erfolgreiche Implementierung in der klinischen Praxis zusammen. KW - medical documentation KW - psychotherapy KW - addiction care KW - computer-mediated therapy KW - digital whiteboard KW - patient empowerment KW - doctor-patient relationship KW - design research KW - user experience KW - evaluation KW - medizinische Dokumentation KW - Psychotherapie KW - Suchtberatung und -therapie KW - computervermittelte Therapie KW - digitales Whiteboard KW - Patientenermündigung KW - Arzt-Patient-Beziehung KW - Design-Forschung KW - User Experience KW - Evaluation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-440292 ER - TY - GEN A1 - Bock, Benedikt A1 - Matysik, Jan-Tobias A1 - Krentz, Konrad-Felix A1 - Meinel, Christoph T1 - Link Layer Key Revocation and Rekeying for the Adaptive Key Establishment Scheme T2 - 2019 IEEE 5TH World Forum on internet of things (WF-IOT) N2 - While the IEEE 802.15.4 radio standard has many features that meet the requirements of Internet of things applications, IEEE 802.15.4 leaves the whole issue of key management unstandardized. To address this gap, Krentz et al. proposed the Adaptive Key Establishment Scheme (AKES), which establishes session keys for use in IEEE 802.15.4 security. Yet, AKES does not cover all aspects of key management. In particular, AKES comprises no means for key revocation and rekeying. Moreover, existing protocols for key revocation and rekeying seem limited in various ways. In this paper, we hence propose a key revocation and rekeying protocol, which is designed to overcome various limitations of current protocols for key revocation and rekeying. For example, our protocol seems unique in that it routes around IEEE 802.15.4 nodes whose keys are being revoked. We successfully implemented and evaluated our protocol using the Contiki-NG operating system and aiocoap. KW - IEEE 802.15.4 KW - key management KW - key establishment KW - key revocation KW - rekeying KW - link layer security KW - MAC security Y1 - 2019 SN - 978-1-5386-4980-0 U6 - https://doi.org/10.1109/WF-IoT.2019.8767211 SP - 374 EP - 379 PB - IEEE CY - New York ER - TY - GEN A1 - Staubitz, Thomas A1 - Meinel, Christoph T1 - Graded Team Assignments in MOOCs BT - Effects of Team Composition and Further Factors on Team Dropout Rates and Performance T2 - SCALE N2 - The ability to work in teams is an important skill in today's work environments. In MOOCs, however, team work, team tasks, and graded team-based assignments play only a marginal role. To close this gap, we have been exploring ways to integrate graded team-based assignments in MOOCs. Some goals of our work are to determine simple criteria to match teams in a volatile environment and to enable a frictionless online collaboration for the participants within our MOOC platform. The high dropout rates in MOOCs pose particular challenges for team work in this context. By now, we have conducted 15 MOOCs containing graded team-based assignments in a variety of topics. The paper at hand presents a study that aims to establish a solid understanding of the participants in the team tasks. Furthermore, we attempt to determine which team compositions are particularly successful. Finally, we examine how several modifications to our platform's collaborative toolset have affected the dropout rates and performance of the teams. KW - Teamwork KW - MOOCs KW - Team-based Learning KW - Team Assessment KW - Peer Assessment KW - Project-based learning Y1 - 2019 SN - 978-1-4503-6804-9 U6 - https://doi.org/10.1145/3330430.3333619 PB - Association for Computing Machinery CY - New York ER - TY - GEN A1 - Renz, Jan A1 - Meinel, Christoph T1 - The "Bachelor Project" BT - Project Based Computer Science Education T2 - 2019 IEEE Global Engineering Education Conference (EDUCON) N2 - One of the challenges of educating the next generation of computer scientists is to teach them to become team players, that are able to communicate and interact not only with different IT systems, but also with coworkers and customers with a non-it background. The “bachelor project” is a project based on team work and a close collaboration with selected industry partners. The authors hosted some of the teams since spring term 2014/15. In the paper at hand we explain and discuss this concept and evaluate its success based on students' evaluation and reports. Furthermore, the technology-stack that has been used by the teams is evaluated to understand how self-organized students in IT-related projects work. We will show that and why the bachelor is the most successful educational format in the perception of the students and how this positive results can be improved by the mentors. KW - computer science education KW - project based learning KW - bachelor project Y1 - 2019 SN - 978-1-5386-9506-7 U6 - https://doi.org/10.1109/EDUCON.2019.8725140 SN - 2165-9567 SP - 580 EP - 587 PB - IEEE CY - New York ER - TY - GEN A1 - Staubitz, Thomas A1 - Teusner, Ralf A1 - Meinel, Christoph T1 - MOOCs in Secondary Education BT - Experiments and Observations from German Classrooms T2 - 2019 IEEE Global Engineering Education Conference (EDUCON) N2 - Computer science education in German schools is often less than optimal. It is only mandatory in a few of the federal states and there is a lack of qualified teachers. As a MOOC (Massive Open Online Course) provider with a German background, we developed the idea to implement a MOOC addressing pupils in secondary schools to fill this gap. The course targeted high school pupils and enabled them to learn the Python programming language. In 2014, we successfully conducted the first iteration of this MOOC with more than 7000 participants. However, the share of pupils in the course was not quite satisfactory. So we conducted several workshops with teachers to find out why they had not used the course to the extent that we had imagined. The paper at hand explores and discusses the steps we have taken in the following years as a result of these workshops. KW - MOOC KW - Secondary Education KW - School KW - Teamwork KW - K-12 KW - Programming course KW - Java KW - Python Y1 - 2019 SN - 978-1-5386-9506-7 U6 - https://doi.org/10.1109/EDUCON.2019.8725138 SN - 2165-9567 SP - 173 EP - 182 PB - IEEE CY - New York ER - TY - JOUR A1 - Omotosho, Adebayo A1 - Ayegba, Peace A1 - Emuoyibofarhe, Justice A1 - Meinel, Christoph T1 - Current State of ICT in Healthcare Delivery in Developing Countries JF - International Journal of Online and Biomedical Engineering N2 - Electronic health is one of the most popular applications of information and communication technologies and it has contributed immensely to health delivery through the provision of quality health service and ubiquitous access at a lower cost. Even though this mode of health service is increasingly becoming known or used in developing nations, these countries are faced with a myriad of challenges when implementing and deploying e-health services on both small and large scale. It is estimated that the Africa population alone carries the highest percentage of the world’s global diseases despite its certain level of e-health adoption. This paper aims at analyzing the progress so far and the current state of e-health in developing countries particularly Africa and propose a framework for further improvement. KW - E-health KW - developing countries KW - framework KW - ICT KW - healthcare Y1 - 2019 U6 - https://doi.org/10.3991/ijoe.v15i08.10294 SN - 2626-8493 VL - 15 IS - 8 SP - 91 EP - 107 PB - Kassel University Press CY - Kassel ER - TY - GEN A1 - Sianipar, Johannes Harungguan A1 - Sukmana, Muhammad Ihsan Haikal A1 - Meinel, Christoph T1 - Moving sensitive data against live memory dumping, spectre and meltdown attacks T2 - 26th International Conference on Systems Engineering (ICSEng) N2 - The emergence of cloud computing allows users to easily host their Virtual Machines with no up-front investment and the guarantee of always available anytime anywhere. But with the Virtual Machine (VM) is hosted outside of user's premise, the user loses the physical control of the VM as it could be running on untrusted host machines in the cloud. Malicious host administrator could launch live memory dumping, Spectre, or Meltdown attacks in order to extract sensitive information from the VM's memory, e.g. passwords or cryptographic keys of applications running in the VM. In this paper, inspired by the moving target defense (MTD) scheme, we propose a novel approach to increase the security of application's sensitive data in the VM by continuously moving the sensitive data among several memory allocations (blocks) in Random Access Memory (RAM). A movement function is added into the application source code in order for the function to be running concurrently with the application's main function. Our approach could reduce the possibility of VM's sensitive data in the memory to be leaked into memory dump file by 2 5% and secure the sensitive data from Spectre and Meltdown attacks. Our approach's overhead depends on the number and the size of the sensitive data. KW - Virtual Machine KW - Memory Dumping KW - Security KW - Cloud Computing KW - Spectre KW - Meltdown Y1 - 2019 SN - 978-1-5386-7834-3 PB - IEEE CY - New York ER - TY - THES A1 - Yang, Haojin T1 - Deep representation learning for multimedia data analysis Y1 - 2019 ER - TY - JOUR A1 - Kunft, Andreas A1 - Katsifodimos, Asterios A1 - Schelter, Sebastian A1 - Bress, Sebastian A1 - Rabl, Tilmann A1 - Markl, Volker T1 - An Intermediate Representation for Optimizing Machine Learning Pipelines JF - Proceedings of the VLDB Endowment N2 - Machine learning (ML) pipelines for model training and validation typically include preprocessing, such as data cleaning and feature engineering, prior to training an ML model. Preprocessing combines relational algebra and user-defined functions (UDFs), while model training uses iterations and linear algebra. Current systems are tailored to either of the two. As a consequence, preprocessing and ML steps are optimized in isolation. To enable holistic optimization of ML training pipelines, we present Lara, a declarative domain-specific language for collections and matrices. Lara's inter-mediate representation (IR) reflects on the complete program, i.e., UDFs, control flow, and both data types. Two views on the IR enable diverse optimizations. Monads enable operator pushdown and fusion across type and loop boundaries. Combinators provide the semantics of domain-specific operators and optimize data access and cross-validation of ML algorithms. Our experiments on preprocessing pipelines and selected ML algorithms show the effects of our proposed optimizations on dense and sparse data, which achieve speedups of up to an order of magnitude. Y1 - 2019 U6 - https://doi.org/10.14778/3342263.3342633 SN - 2150-8097 VL - 12 IS - 11 SP - 1553 EP - 1567 PB - Association for Computing Machinery CY - New York ER - TY - JOUR A1 - Wuttke, Matthias A1 - Li, Yong A1 - Li, Man A1 - Sieber, Karsten B. A1 - Feitosa, Mary F. A1 - Gorski, Mathias A1 - Tin, Adrienne A1 - Wang, Lihua A1 - Chu, Audrey Y. A1 - Hoppmann, Anselm A1 - Kirsten, Holger A1 - Giri, Ayush A1 - Chai, Jin-Fang A1 - Sveinbjornsson, Gardar A1 - Tayo, Bamidele O. A1 - Nutile, Teresa A1 - Fuchsberger, Christian A1 - Marten, Jonathan A1 - Cocca, Massimiliano A1 - Ghasemi, Sahar A1 - Xu, Yizhe A1 - Horn, Katrin A1 - Noce, Damia A1 - Van der Most, Peter J. A1 - Sedaghat, Sanaz A1 - Yu, Zhi A1 - Akiyama, Masato A1 - Afaq, Saima A1 - Ahluwalia, Tarunveer Singh A1 - Almgren, Peter A1 - Amin, Najaf A1 - Arnlov, Johan A1 - Bakker, Stephan J. L. A1 - Bansal, Nisha A1 - Baptista, Daniela A1 - Bergmann, Sven A1 - Biggs, Mary L. A1 - Biino, Ginevra A1 - Boehnke, Michael A1 - Boerwinkle, Eric A1 - Boissel, Mathilde A1 - Böttinger, Erwin A1 - Boutin, Thibaud S. A1 - Brenner, Hermann A1 - Brumat, Marco A1 - Burkhardt, Ralph A1 - Butterworth, Adam S. A1 - Campana, Eric A1 - Campbell, Archie A1 - Campbell, Harry A1 - Canouil, Mickael A1 - Carroll, Robert J. A1 - Catamo, Eulalia A1 - Chambers, John C. A1 - Chee, Miao-Ling A1 - Chee, Miao-Li A1 - Chen, Xu A1 - Cheng, Ching-Yu A1 - Cheng, Yurong A1 - Christensen, Kaare A1 - Cifkova, Renata A1 - Ciullo, Marina A1 - Concas, Maria Pina A1 - Cook, James P. A1 - Coresh, Josef A1 - Corre, Tanguy A1 - Sala, Cinzia Felicita A1 - Cusi, Daniele A1 - Danesh, John A1 - Daw, E. Warwick A1 - De Borst, Martin H. A1 - De Grandi, Alessandro A1 - De Mutsert, Renee A1 - De Vries, Aiko P. J. A1 - Degenhardt, Frauke A1 - Delgado, Graciela A1 - Demirkan, Ayse A1 - Di Angelantonio, Emanuele A1 - Dittrich, Katalin A1 - Divers, Jasmin A1 - Dorajoo, Rajkumar A1 - Eckardt, Kai-Uwe A1 - Ehret, Georg A1 - Elliott, Paul A1 - Endlich, Karlhans A1 - Evans, Michele K. A1 - Felix, Janine F. A1 - Foo, Valencia Hui Xian A1 - Franco, Oscar H. A1 - Franke, Andre A1 - Freedman, Barry I. A1 - Freitag-Wolf, Sandra A1 - Friedlander, Yechiel A1 - Froguel, Philippe A1 - Gansevoort, Ron T. A1 - Gao, He A1 - Gasparini, Paolo A1 - Gaziano, J. Michael A1 - Giedraitis, Vilmantas A1 - Gieger, Christian A1 - Girotto, Giorgia A1 - Giulianini, Franco A1 - Gogele, Martin A1 - Gordon, Scott D. A1 - Gudbjartsson, Daniel F. A1 - Gudnason, Vilmundur A1 - Haller, Toomas A1 - Hamet, Pavel A1 - Harris, Tamara B. A1 - Hartman, Catharina A. A1 - Hayward, Caroline A1 - Hellwege, Jacklyn N. A1 - Heng, Chew-Kiat A1 - Hicks, Andrew A. A1 - Hofer, Edith A1 - Huang, Wei A1 - Hutri-Kahonen, Nina A1 - Hwang, Shih-Jen A1 - Ikram, M. Arfan A1 - Indridason, Olafur S. A1 - Ingelsson, Erik A1 - Ising, Marcus A1 - Jaddoe, Vincent W. V. A1 - Jakobsdottir, Johanna A1 - Jonas, Jost B. A1 - Joshi, Peter K. A1 - Josyula, Navya Shilpa A1 - Jung, Bettina A1 - Kahonen, Mika A1 - Kamatani, Yoichiro A1 - Kammerer, Candace M. A1 - Kanai, Masahiro A1 - Kastarinen, Mika A1 - Kerr, Shona M. A1 - Khor, Chiea-Chuen A1 - Kiess, Wieland A1 - Kleber, Marcus E. A1 - Koenig, Wolfgang A1 - Kooner, Jaspal S. A1 - Korner, Antje A1 - Kovacs, Peter A1 - Kraja, Aldi T. A1 - Krajcoviechova, Alena A1 - Kramer, Holly A1 - Kramer, Bernhard K. A1 - Kronenberg, Florian A1 - Kubo, Michiaki A1 - Kuhnel, Brigitte A1 - Kuokkanen, Mikko A1 - Kuusisto, Johanna A1 - La Bianca, Martina A1 - Laakso, Markku A1 - Lange, Leslie A. A1 - Langefeld, Carl D. A1 - Lee, Jeannette Jen-Mai A1 - Lehne, Benjamin A1 - Lehtimaki, Terho A1 - Lieb, Wolfgang A1 - Lim, Su-Chi A1 - Lind, Lars A1 - Lindgren, Cecilia M. A1 - Liu, Jun A1 - Liu, Jianjun A1 - Loeffler, Markus A1 - Loos, Ruth J. F. A1 - Lucae, Susanne A1 - Lukas, Mary Ann A1 - Lyytikainen, Leo-Pekka A1 - Magi, Reedik A1 - Magnusson, Patrik K. E. A1 - Mahajan, Anubha A1 - Martin, Nicholas G. A1 - Martins, Jade A1 - Marz, Winfried A1 - Mascalzoni, Deborah A1 - Matsuda, Koichi A1 - Meisinger, Christa A1 - Meitinger, Thomas A1 - Melander, Olle A1 - Metspalu, Andres A1 - Mikaelsdottir, Evgenia K. A1 - Milaneschi, Yuri A1 - Miliku, Kozeta A1 - Mishra, Pashupati P. A1 - Program, V. A. Million Veteran A1 - Mohlke, Karen L. A1 - Mononen, Nina A1 - Montgomery, Grant W. A1 - Mook-Kanamori, Dennis O. A1 - Mychaleckyj, Josyf C. A1 - Nadkarni, Girish N. A1 - Nalls, Mike A. A1 - Nauck, Matthias A1 - Nikus, Kjell A1 - Ning, Boting A1 - Nolte, Ilja M. A1 - Noordam, Raymond A1 - Olafsson, Isleifur A1 - Oldehinkel, Albertine J. A1 - Orho-Melander, Marju A1 - Ouwehand, Willem H. A1 - Padmanabhan, Sandosh A1 - Palmer, Nicholette D. A1 - Palsson, Runolfur A1 - Penninx, Brenda W. J. H. A1 - Perls, Thomas A1 - Perola, Markus A1 - Pirastu, Mario A1 - Pirastu, Nicola A1 - Pistis, Giorgio A1 - Podgornaia, Anna I. A1 - Polasek, Ozren A1 - Ponte, Belen A1 - Porteous, David J. A1 - Poulain, Tanja A1 - Pramstaller, Peter P. A1 - Preuss, Michael H. A1 - Prins, Bram P. A1 - Province, Michael A. A1 - Rabelink, Ton J. A1 - Raffield, Laura M. A1 - Raitakari, Olli T. A1 - Reilly, Dermot F. A1 - Rettig, Rainer A1 - Rheinberger, Myriam A1 - Rice, Kenneth M. A1 - Ridker, Paul M. A1 - Rivadeneira, Fernando A1 - Rizzi, Federica A1 - Roberts, David J. A1 - Robino, Antonietta A1 - Rossing, Peter A1 - Rudan, Igor A1 - Rueedi, Rico A1 - Ruggiero, Daniela A1 - Ryan, Kathleen A. A1 - Saba, Yasaman A1 - Sabanayagam, Charumathi A1 - Salomaa, Veikko A1 - Salvi, Erika A1 - Saum, Kai-Uwe A1 - Schmidt, Helena A1 - Schmidt, Reinhold A1 - Ben Schottker, A1 - Schulz, Christina-Alexandra A1 - Schupf, Nicole A1 - Shaffer, Christian M. A1 - Shi, Yuan A1 - Smith, Albert V. A1 - Smith, Blair H. A1 - Soranzo, Nicole A1 - Spracklen, Cassandra N. A1 - Strauch, Konstantin A1 - Stringham, Heather M. A1 - Stumvoll, Michael A1 - Svensson, Per O. A1 - Szymczak, Silke A1 - Tai, E-Shyong A1 - Tajuddin, Salman M. A1 - Tan, Nicholas Y. Q. A1 - Taylor, Kent D. A1 - Teren, Andrej A1 - Tham, Yih-Chung A1 - Thiery, Joachim A1 - Thio, Chris H. L. A1 - Thomsen, Hauke A1 - Thorleifsson, Gudmar A1 - Toniolo, Daniela A1 - Tonjes, Anke A1 - Tremblay, Johanne A1 - Tzoulaki, Ioanna A1 - Uitterlinden, Andre G. A1 - Vaccargiu, Simona A1 - Van Dam, Rob M. A1 - Van der Harst, Pim A1 - Van Duijn, Cornelia M. A1 - Edward, Digna R. Velez A1 - Verweij, Niek A1 - Vogelezang, Suzanne A1 - Volker, Uwe A1 - Vollenweider, Peter A1 - Waeber, Gerard A1 - Waldenberger, Melanie A1 - Wallentin, Lars A1 - Wang, Ya Xing A1 - Wang, Chaolong A1 - Waterworth, Dawn M. A1 - Bin Wei, Wen A1 - White, Harvey A1 - Whitfield, John B. A1 - Wild, Sarah H. A1 - Wilson, James F. A1 - Wojczynski, Mary K. A1 - Wong, Charlene A1 - Wong, Tien-Yin A1 - Xu, Liang A1 - Yang, Qiong A1 - Yasuda, Masayuki A1 - Yerges-Armstrong, Laura M. A1 - Zhang, Weihua A1 - Zonderman, Alan B. A1 - Rotter, Jerome I. A1 - Bochud, Murielle A1 - Psaty, Bruce M. A1 - Vitart, Veronique A1 - Wilson, James G. A1 - Dehghan, Abbas A1 - Parsa, Afshin A1 - Chasman, Daniel I. A1 - Ho, Kevin A1 - Morris, Andrew P. A1 - Devuyst, Olivier A1 - Akilesh, Shreeram A1 - Pendergrass, Sarah A. A1 - Sim, Xueling A1 - Boger, Carsten A. A1 - Okada, Yukinori A1 - Edwards, Todd L. A1 - Snieder, Harold A1 - Stefansson, Kari A1 - Hung, Adriana M. A1 - Heid, Iris M. A1 - Scholz, Markus A1 - Teumer, Alexander A1 - Kottgen, Anna A1 - Pattaro, Cristian T1 - A catalog of genetic loci associated with kidney function from analyses of a million individuals JF - Nature genetics N2 - Chronic kidney disease (CKD) is responsible for a public health burden with multi-systemic complications. Through transancestry meta-analysis of genome-wide association studies of estimated glomerular filtration rate (eGFR) and independent replication (n = 1,046,070), we identified 264 associated loci (166 new). Of these,147 were likely to be relevant for kidney function on the basis of associations with the alternative kidney function marker blood urea nitrogen (n = 416,178). Pathway and enrichment analyses, including mouse models with renal phenotypes, support the kidney as the main target organ. A genetic risk score for lower eGFR was associated with clinically diagnosed CKD in 452,264 independent individuals. Colocalization analyses of associations with eGFR among 783,978 European-ancestry individuals and gene expression across 46 human tissues, including tubulo-interstitial and glomerular kidney compartments, identified 17 genes differentially expressed in kidney. Fine-mapping highlighted missense driver variants in 11 genes and kidney-specific regulatory variants. These results provide a comprehensive priority list of molecular targets for translational research. Y1 - 2019 U6 - https://doi.org/10.1038/s41588-019-0407-x SN - 1061-4036 SN - 1546-1718 VL - 51 IS - 6 SP - 957 EP - + PB - Nature Publ. Group CY - New York ER - TY - BOOK A1 - Adriano, Christian A1 - Bleifuß, Tobias A1 - Cheng, Lung-Pan A1 - Diba, Kiarash A1 - Fricke, Andreas A1 - Grapentin, Andreas A1 - Jiang, Lan A1 - Kovacs, Robert A1 - Krejca, Martin Stefan A1 - Mandal, Sankalita A1 - Marwecki, Sebastian A1 - Matthies, Christoph A1 - Mattis, Toni A1 - Niephaus, Fabio A1 - Pirl, Lukas A1 - Quinzan, Francesco A1 - Ramson, Stefan A1 - Rezaei, Mina A1 - Risch, Julian A1 - Rothenberger, Ralf A1 - Roumen, Thijs A1 - Stojanovic, Vladeta A1 - Wolf, Johannes ED - Meinel, Christoph ED - Plattner, Hasso ED - Döllner, Jürgen Roland Friedrich ED - Weske, Mathias ED - Polze, Andreas ED - Hirschfeld, Robert ED - Naumann, Felix ED - Giese, Holger ED - Baudisch, Patrick ED - Friedrich, Tobias ED - Böttinger, Erwin ED - Lippert, Christoph T1 - Technical report BT - Fall Retreat 2018 N2 - Design and Implementation of service-oriented architectures imposes a huge number of research questions from the fields of software engineering, system analysis and modeling, adaptability, and application integration. Component orientation and web services are two approaches for design and realization of complex web-based system. Both approaches allow for dynamic application adaptation as well as integration of enterprise application. Commonly used technologies, such as J2EE and .NET, form de facto standards for the realization of complex distributed systems. Evolution of component systems has lead to web services and service-based architectures. This has been manifested in a multitude of industry standards and initiatives such as XML, WSDL UDDI, SOAP, etc. All these achievements lead to a new and promising paradigm in IT systems engineering which proposes to design complex software solutions as collaboration of contractually defined software services. Service-Oriented Systems Engineering represents a symbiosis of best practices in object-orientation, component-based development, distributed computing, and business process management. It provides integration of business and IT concerns. The annual Ph.D. Retreat of the Research School provides each member the opportunity to present his/her current state of their research and to give an outline of a prospective Ph.D. thesis. Due to the interdisciplinary structure of the research school, this technical report covers a wide range of topics. These include but are not limited to: Human Computer Interaction and Computer Vision as Service; Service-oriented Geovisualization Systems; Algorithm Engineering for Service-oriented Systems; Modeling and Verification of Self-adaptive Service-oriented Systems; Tools and Methods for Software Engineering in Service-oriented Systems; Security Engineering of Service-based IT Systems; Service-oriented Information Systems; Evolutionary Transition of Enterprise Applications to Service Orientation; Operating System Abstractions for Service-oriented Computing; and Services Specification, Composition, and Enactment. N2 - Der Entwurf und die Realisierung dienstbasierender Architekturen wirft eine Vielzahl von Forschungsfragestellungen aus den Gebieten der Softwaretechnik, der Systemmodellierung und -analyse, sowie der Adaptierbarkeit und Integration von Applikationen auf. Komponentenorientierung und WebServices sind zwei Ansätze für den effizienten Entwurf und die Realisierung komplexer Web-basierender Systeme. Sie ermöglichen die Reaktion auf wechselnde Anforderungen ebenso, wie die Integration großer komplexer Softwaresysteme. Heute übliche Technologien, wie J2EE und .NET, sind de facto Standards für die Entwicklung großer verteilter Systeme. Die Evolution solcher Komponentensysteme führt über WebServices zu dienstbasierenden Architekturen. Dies manifestiert sich in einer Vielzahl von Industriestandards und Initiativen wie XML, WSDL, UDDI, SOAP. All diese Schritte führen letztlich zu einem neuen, vielversprechenden Paradigma für IT Systeme, nach dem komplexe Softwarelösungen durch die Integration vertraglich vereinbarter Software-Dienste aufgebaut werden sollen. "Service-Oriented Systems Engineering" repräsentiert die Symbiose bewährter Praktiken aus den Gebieten der Objektorientierung, der Komponentenprogrammierung, des verteilten Rechnen sowie der Geschäftsprozesse und berücksichtigt auch die Integration von Geschäftsanliegen und Informationstechnologien. Die Klausurtagung des Forschungskollegs "Service-oriented Systems Engineering" findet einmal jährlich statt und bietet allen Kollegiaten die Möglichkeit den Stand ihrer aktuellen Forschung darzulegen. Bedingt durch die Querschnittstruktur des Kollegs deckt dieser Bericht ein weites Spektrum aktueller Forschungsthemen ab. Dazu zählen unter anderem Human Computer Interaction and Computer Vision as Service; Service-oriented Geovisualization Systems; Algorithm Engineering for Service-oriented Systems; Modeling and Verification of Self-adaptive Service-oriented Systems; Tools and Methods for Software Engineering in Service-oriented Systems; Security Engineering of Service-based IT Systems; Service-oriented Information Systems; Evolutionary Transition of Enterprise Applications to Service Orientation; Operating System Abstractions for Service-oriented Computing; sowie Services Specification, Composition, and Enactment. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 129 KW - Hasso Plattner Institute KW - research school KW - Ph.D. retreat KW - service-oriented systems engineering KW - Hasso-Plattner-Institut KW - Forschungskolleg KW - Klausurtagung KW - Service-oriented Systems Engineering Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-427535 SN - 978-3-86956-465-4 SN - 1613-5652 SN - 2191-1665 IS - 129 PB - Universitätsverlag Potsdam CY - Potsdam ER -