TY - JOUR A1 - Yousfi, Alaaeddine A1 - Weske, Mathias T1 - Discovering commute patterns via process mining JF - Knowledge and Information Systems N2 - Ubiquitous computing has proven its relevance and efficiency in improving the user experience across a myriad of situations. It is now the ineluctable solution to keep pace with the ever-changing environments in which current systems operate. Despite the achievements of ubiquitous computing, this discipline is still overlooked in business process management. This is surprising, since many of today’s challenges, in this domain, can be addressed by methods and techniques from ubiquitous computing, for instance user context and dynamic aspects of resource locations. This paper takes a first step to integrate methods and techniques from ubiquitous computing in business process management. To do so, we propose discovering commute patterns via process mining. Through our proposition, we can deduce the users’ significant locations, routes, travel times and travel modes. This information can be a stepping-stone toward helping the business process management community embrace the latest achievements in ubiquitous computing, mainly in location-based service. To corroborate our claims, a user study was conducted. The significant places, routes, travel modes and commuting times of our test subjects were inferred with high accuracies. All in all, ubiquitous computing can enrich the processes with new capabilities that go beyond what has been established in business process management so far. KW - Commute pattern KW - Commute process KW - Process mining KW - Ubiquitous computing KW - Location-based services Y1 - 2019 U6 - https://doi.org/10.1007/s10115-018-1255-1 SN - 0219-1377 SN - 0219-3116 VL - 60 IS - 2 SP - 691 EP - 713 PB - Springer CY - London ER - TY - JOUR A1 - Yeung, Ching-man Au A1 - Noll, Michael G. A1 - Gibbins, Nicholas A1 - Meinel, Christoph A1 - Shadbolt, Nigel T1 - Spear spamming-resistant expertise analysis and ranking incollaborative tagging systems JF - Computational intelligence N2 - In this article, we discuss the notions of experts and expertise in resource discovery in the context of collaborative tagging systems. We propose that the level of expertise of a user with respect to a particular topic is mainly determined by two factors. First, an expert should possess a high-quality collection of resources, while the quality of a Web resource in turn depends on the expertise of the users who have assigned tags to it, forming a mutual reinforcement relationship. Second, an expert should be one who tends to identify interesting or useful resources before other users discover them, thus bringing these resources to the attention of the community of users. We propose a graph-based algorithm, SPEAR (spamming-resistant expertise analysis and ranking), which implements the above ideas for ranking users in a folksonomy. Our experiments show that our assumptions on expertise in resource discovery, and SPEAR as an implementation of these ideas, allow us to promote experts and demote spammers at the same time, with performance significantly better than the original hypertext-induced topic search algorithm and simple statistical measures currently used in most collaborative tagging systems. KW - collaborative tagging KW - expertise KW - folksonomy KW - HITS KW - ranking KW - spamming Y1 - 2011 U6 - https://doi.org/10.1111/j.1467-8640.2011.00384.x SN - 0824-7935 SN - 1467-8640 VL - 27 IS - 3 SP - 458 EP - 488 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Yang, Yong A1 - Dumas, Marlon A1 - Garcia-Banuelos, Luciano A1 - Polyvyanyy, Artem A1 - Zhang, Liang T1 - Generalized aggregate quality of service computation for composite services JF - The journal of systems and software N2 - This article addresses the problem of estimating the Quality of Service (QoS) of a composite service given the QoS of the services participating in the composition. Previous solutions to this problem impose restrictions on the topology of the orchestration models, limiting their applicability to well-structured orchestration models for example. This article lifts these restrictions by proposing a method for aggregate QoS computation that deals with more general types of unstructured orchestration models. The applicability and scalability of the proposed method are validated using a collection of models from industrial practice. KW - Service-oriented computing KW - Service composition KW - Service orchestration KW - Quality of service Y1 - 2012 U6 - https://doi.org/10.1016/j.jss.2012.03.005 SN - 0164-1212 VL - 85 IS - 8 SP - 1818 EP - 1830 PB - Elsevier CY - New York ER - TY - JOUR A1 - Yang, Haojin A1 - Quehl, Bernhard A1 - Sack, Harald T1 - A framework for improved video text detection and recognition JF - Multimedia tools and applications : an international journal N2 - Text displayed in a video is an essential part for the high-level semantic information of the video content. Therefore, video text can be used as a valuable source for automated video indexing in digital video libraries. In this paper, we propose a workflow for video text detection and recognition. In the text detection stage, we have developed a fast localization-verification scheme, in which an edge-based multi-scale text detector first identifies potential text candidates with high recall rate. Then, detected candidate text lines are refined by using an image entropy-based filter. Finally, Stroke Width Transform (SWT)- and Support Vector Machine (SVM)-based verification procedures are applied to eliminate the false alarms. For text recognition, we have developed a novel skeleton-based binarization method in order to separate text from complex backgrounds to make it processible for standard OCR (Optical Character Recognition) software. Operability and accuracy of proposed text detection and binarization methods have been evaluated by using publicly available test data sets. KW - Video OCR KW - Video indexing KW - Multimedia retrieval Y1 - 2014 U6 - https://doi.org/10.1007/s11042-012-1250-6 SN - 1380-7501 SN - 1573-7721 VL - 69 IS - 1 SP - 217 EP - 245 PB - Springer CY - Dordrecht ER - TY - BOOK A1 - Wätzoldt, Sebastian A1 - Giese, Holger T1 - Modeling collaborations in self-adaptive systems of systems BT - terms, characteristics, requirements, and scenarios N2 - An increasing demand on functionality and flexibility leads to an integration of beforehand isolated system solutions building a so-called System of Systems (SoS). Furthermore, the overall SoS should be adaptive to react on changing requirements and environmental conditions. Due SoS are composed of different independent systems that may join or leave the overall SoS at arbitrary point in times, the SoS structure varies during the systems lifetime and the overall SoS behavior emerges from the capabilities of the contained subsystems. In such complex system ensembles new demands of understanding the interaction among subsystems, the coupling of shared system knowledge and the influence of local adaptation strategies to the overall resulting system behavior arise. In this report, we formulate research questions with the focus of modeling interactions between system parts inside a SoS. Furthermore, we define our notion of important system types and terms by retrieving the current state of the art from literature. Having a common understanding of SoS, we discuss a set of typical SoS characteristics and derive general requirements for a collaboration modeling language. Additionally, we retrieve a broad spectrum of real scenarios and frameworks from literature and discuss how these scenarios cope with different characteristics of SoS. Finally, we discuss the state of the art for existing modeling languages that cope with collaborations for different system types such as SoS. N2 - Steigende Anforderungen zum Funktionsumfang und der Flexibilität von Systemen führt zur Integration von zuvor isolierten Systemlösungen zu sogenannten System of Systems (SoS). Weiterhin sollten solche SoS adaptive Eigenschaften aufweisen, die es ihm ermöglichen auf sich ändernde Anforderungen und Umwelteinflüsse zu reagieren. Weil SoS aus unterschiedlichen, unabhängigen Subsystemen zusammengesetzt sind, die wiederum das übergeordnete SoS zu beliebigen Zeitpunkten erweitern oder verlassen können, ist das SoS durch eine variable Systemstruktur gekennzeichnet. Weiterhin definieren sich der Funktionsumfang des SoS und dessen Potenzial aus den enthaltenen Subsystemen. Solche komplexen Systemzusammenstellungen erfordern neue Untersuchungstechniken, um die Interaktion der einzelnen Subsysteme, die Kopplung von geteilten Daten und den Einfluss von lokalen Adaptionsstrategien auf das Gesamtsystem besser verstehen zu können. In diesem Bericht formulieren wir aktuelle Forschungsfragen mit dem Fokus auf der Modellierung von Interaktionen zwischen verschiedenen Systemteilen innerhalt eines SoS. Weiterhin definieren wir wichtige Systemtypen und Begriffe aus diesem Bereich durch das Zusammentragen aktueller Literatur. Nachdem wir ein gemeinsames Verständnis über SoS geschaffen haben, leiten wir typische SoS Eigenschaften und allgemeine Anforderungen für eine Modellierungssprache für Kollaborationen ab. Zusätzlich führen wir eine Literaturstudie durch, in der wir ein breites Spektrum von realen Szenarios und existierenden Frameworks zusammentragen, an denen wir die aufgezeigten SoS Eigenschaften diskutieren. Abschließend beschreiben wir den Stand der Wissenschaft bezüglich existierender Modellierungssprachen, die sich mit Kollaborationen in verschiedenen Arten von Systemen, wie SoS, beschäftigen. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 96 KW - modeling KW - collaboration KW - system of systems KW - cyber-physical systems KW - feedback loops KW - adaptive systems KW - Modellierung KW - Kollaborationen KW - System of Systems KW - Cyber-Physical Systems KW - Feedback Loops KW - adaptive Systeme Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-73036 SN - 978-3-86956-324-4 SN - 1613-5652 SN - 2191-1665 IS - 96 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - THES A1 - Wätzoldt, Sebastian T1 - Modeling collaborations in adaptive systems of systems T1 - Modellierung von Kollaborationen für adaptive Systeme von Systemen N2 - Recently, due to an increasing demand on functionality and flexibility, beforehand isolated systems have become interconnected to gain powerful adaptive Systems of Systems (SoS) solutions with an overall robust, flexible and emergent behavior. The adaptive SoS comprises a variety of different system types ranging from small embedded to adaptive cyber-physical systems. On the one hand, each system is independent, follows a local strategy and optimizes its behavior to reach its goals. On the other hand, systems must cooperate with each other to enrich the overall functionality to jointly perform on the SoS level reaching global goals, which cannot be satisfied by one system alone. Due to difficulties of local and global behavior optimizations conflicts may arise between systems that have to be solved by the adaptive SoS. This thesis proposes a modeling language that facilitates the description of an adaptive SoS by considering the adaptation capabilities in form of feedback loops as first class entities. Moreover, this thesis adopts the Models@runtime approach to integrate the available knowledge in the systems as runtime models into the modeled adaptation logic. Furthermore, the modeling language focuses on the description of system interactions within the adaptive SoS to reason about individual system functionality and how it emerges via collaborations to an overall joint SoS behavior. Therefore, the modeling language approach enables the specification of local adaptive system behavior, the integration of knowledge in form of runtime models and the joint interactions via collaboration to place the available adaptive behavior in an overall layered, adaptive SoS architecture. Beside the modeling language, this thesis proposes analysis rules to investigate the modeled adaptive SoS, which enables the detection of architectural patterns as well as design flaws and pinpoints to possible system threats. Moreover, a simulation framework is presented, which allows the direct execution of the modeled SoS architecture. Therefore, the analysis rules and the simulation framework can be used to verify the interplay between systems as well as the modeled adaptation effects within the SoS. This thesis realizes the proposed concepts of the modeling language by mapping them to a state of the art standard from the automotive domain and thus, showing their applicability to actual systems. Finally, the modeling language approach is evaluated by remodeling up to date research scenarios from different domains, which demonstrates that the modeling language concepts are powerful enough to cope with a broad range of existing research problems. N2 - Seit einiger Zeit führen ein ansteigender Bedarf nach erweiterter Systemfunktionalität und deren flexible Verwendung zu vernetzten Systemen, die sich zu einem übergeordneten adaptiven System von Systemen (SoS) zusammenschließen. Dieser SoS Zusammenschluss zeigt ein gewünschtes, robustes und flexibles Gesamtverhalten, welches sich aus der Funktionalität der einzelnen Systeme zusammensetzt. Das SoS beinhaltet eine Vielzahl von verschiedenen Systemarten, die sich von eingebetteten bis hin zu Cyber-Physical Systems erstrecken. Einerseits optimiert jedes einzelne System sein Verhalten bezüglich lokaler Ziele. Anderseits müssen die Systeme miteinander interagieren, um neue, zusammengesetzte Funktionalitäten bereitzustellen und damit vorgegebene SoS Ziele zu erreichen, welche durch ein einzelnes System nicht erfüllt werden können. Die Schwierigkeit besteht nun darin, Konflikte zwischen lokalen und globalen Verhaltensstrategien zwischen Systemen innerhalb des SoS zu beseitigen. Diese Doktorarbeit stellt eine Modellierungssprache vor, welche für die Beschreibung von adaptiven SoS geeignet ist. Dabei berücksichtigt die Modellierungssprache die Adaptionslogik des SoS in Form von periodischen Adaptationsschleifen als primäres Sprachkonstrukt. Außerdem übernimmt diese Arbeit den Models@runtime Ansatz, um verfügbares Systemwissen als Laufzeitmodelle in die Adaptationslogik des Systems zu integrieren. Weiterhin liegt der Fokus der Modellierungssprache auf der Beschreibung von Systeminteraktionen innerhalb des SoS. Dies ermöglicht Schlussfolgerungen von individuellem Systemverhalten sowie deren Aggregation zu kollaborativem Verhalten im Kontext von Systeminteraktionen im SoS. Damit unterstützt die entwickelte Modellierungssprache die Beschreibung von lokalem adaptivem Verhalten, die Integration von Wissen über die Modellierung von Laufzeitmodellen und Systeminteraktionen in Form von kollaborativem Verhalten. Alle drei Aspekte werden in die adaptive SoS Architektur integriert. Neben der entwickelten Modellierungssprache führt diese Doktorarbeit Analyseregeln zur Untersuchung des modellierten SoS ein. Diese Regeln ermöglichen die Erkennung von Architekturmustern und möglichen Schwächen im Systementwurf. Zusätzlich wird eine Simulationsumgebung für die Modellierungssprache präsentiert, welche die direkte Ausführung von einer modellierten SoS Architektur erlaubt. Die Analyseregeln und die Simulationsumgebung dienen demnach sowohl der Verifizierung von Systeminteraktionen als auch der spezifizierten Adaptationslogik innerhalb des SoS. Die vorliegende Arbeit implementiert die vorgestellten Konzepte der Modellierungssprache durch deren Abbildung auf einen aktuellen Standard im Automobilbereich und zeigt damit die Anwendbarkeit der Sprache auf gegenwärtige Systeme. Zum Schluss findet eine Evaluierung der Modellierungssprache statt, wobei aktuelle Forschungsszenarien aus unterschiedlichen Bereichen erneut mit der vorgestellten Sprache modelliert werden. Dies zeigt, dass die Modellierungskonzepte geeignet sind, um weite Bereiche existierender Forschungsprobleme zu bewältigen. KW - deurema modeling language KW - adaptive systems KW - systems of systems KW - runtime models KW - feedback loop modeling KW - collaborations KW - Deurema Modellierungssprache KW - Kollaborationen KW - adaptive Systeme KW - Systeme von Systemen KW - Laufzeitmodelle KW - Feedback Loop Modellierung Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-97494 ER - TY - JOUR A1 - Wist, Dominic A1 - Wollowski, Ralf A1 - Schaefer, Mark A1 - Vogler, Walter T1 - Avoiding irreducible CSC conflicts by internal communication N2 - Resynthesis of handshake specifications obtained e. g. from BALSA or TANGRAM with speed-independent logic synthesis from STGs is a promising approach. To deal with state-space explosion, we suggested STG decomposition; a problem is that decomposition can lead to irreducible CSC conflicts. Here, we present a new approach to solve such conflicts by introducing internal communication between the components. We give some first, very encouraging results for very large STGs concerning synthesis time and circuit area. Y1 - 2009 UR - http://iospress.metapress.com/content/300178/ U6 - https://doi.org/10.3233/Fi-2009-140 SN - 0169-2968 ER - TY - BOOK A1 - Wist, Dominic A1 - Wollowski, Ralf T1 - STG decomposition : avoiding irreducible CSC conflicts by internal communication N2 - Inhalt: 1 Introduction 2 Basic Definitions 3 Achieving SI Implementability by Internal Communication 4 Towards a Structural Method 5 Examples 6 Conclusions and Future Work T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 20 Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-32968 SN - 978-3-940793-02-7 ER - TY - JOUR A1 - Wist, Dominic A1 - Schaefer, Mark A1 - Vogler, Walter A1 - Wollowski, Ralf T1 - Signal transition graph decomposition internal communication for speed independent circuit implementation JF - IET Computers and digital techniques N2 - Logic synthesis of speed independent circuits based on signal transition graph (STG) decomposition is a promising approach to tackle complexity problems like state-space explosion. Unfortunately, decomposition can result in components that in isolation have irreducible complete state coding conflicts. In earlier work, the authors showed how to resolve such conflicts by introducing internal communication between components, but only for very restricted specification structures. Here, they improve their former work by presenting algorithms for identifying delay transitions and inserting gyroscopes for specifications having a much more general structure. Thus, the authors are now able to synthesise controllers from real-life specifications. For all algorithms, they present correctness proofs and show their successful application to benchmarks, including very complex STGs arising in the context of control resynthesis. Y1 - 2011 U6 - https://doi.org/10.1049/iet-cdt.2010.0162 SN - 1751-8601 VL - 5 IS - 6 SP - 440 EP - 451 PB - Institution of Engineering and Technology CY - Hertford ER - TY - BOOK A1 - Wist, Dominic A1 - Schaefer, Mark A1 - Vogler, Walter A1 - Wollowski, Ralf T1 - STG decomposition : internal communication for SI implementability N2 - STG decomposition is a promising approach to tackle the complexity problems arising in logic synthesis of speed independent circuits, a robust asynchronous (i.e. clockless) circuit type. Unfortunately, STG decomposition can result in components that in isolation have irreducible CSC conflicts. Generalising earlier work, it is shown how to resolve such conflicts by introducing internal communication between the components via structural techniques only. N2 - STG-Dekomposition ist ein bewährter Ansatz zur Bewältigung der Komplexitätsprobleme bei der Logiksynthese von SI (speed independent) Schaltungen – ein robuster asynchroner (d.h. ohne Taktsignal arbeitender digitaler) Schaltungstyp. Allerdings können dabei Komponenten mit irreduziblen CSC-Konflikten entstehen. Durch Verallgemeinerung früherer Arbeiten wird gezeigt, wie solche Konflikte durch Einführung interner Kommunikation zwischen den Komponenten gelöst werden können, und zwar ausschließlich durch Verwendung an der Graphenstruktur ansetzender Verfahren. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 32 KW - Asynchrone Schaltung KW - Petrinetz KW - Signalflankengraph (SFG oder STG) KW - STG-Dekomposition KW - speed independent KW - CSC KW - Controller-Resynthese KW - Asynchronous circuit KW - petri net KW - signal transition graph KW - STG decomposition KW - speed independent KW - CSC KW - control resynthesis Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-40786 SN - 978-3-86956-037-3 PB - Universitätsverlag Potsdam CY - Potsdam ER -