Institut für Informatik und Computational Science
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Institute
Researchers and developers worldwide have put their efforts into the design, development and use of information and communication technology to support teaching and learning. This research is driven by pedagogical as well as technological disciplines. The most challenging ideas are currently found in the application of mobile, ubiquitous, pervasive, contextualized and seamless technologies for education, which we shall refer to as pervasive education. This article provides a comprehensive overview of the existing work in this field and categorizes it with respect to educational settings. Using this approach, best practice solutions for certain educational settings and open questions for pervasive education are highlighted in order to inspire interested developers and educators. The work is assigned to different fields, identified by the main pervasive technologies used and the educational settings. Based on these assignments we identify areas within pervasive education that are currently disregarded or deemed challenging so that further research and development in these fields are stimulated in a trans-disciplinary approach. (C) 2013 Elsevier B.V. All rights reserved.
This paper describes the implementation of a workflow model for service-oriented computing of potential areas for wind turbines in jABC. By implementing a re-executable model the manual effort of a multi-criteria site analysis can be reduced. The aim is to determine the shift of typical geoprocessing tools of geographic information systems (GIS) from the desktop to the web. The analysis is based on a vector data set and mainly uses web services of the “Center for Spatial Information Science and Systems” (CSISS). This paper discusses effort, benefits and problems associated with the use of the web services.
Boolean constraint solving technology has made tremendous progress over the last decade, leading to industrial-strength solvers, for example, in the areas of answer set programming (ASP), the constraint satisfaction problem (CSP), propositional satisfiability (SAT) and satisfiability of quantified Boolean formulas (QBF). However, in all these areas, there exist multiple solving strategies that work well on different applications; no strategy dominates all other strategies. Therefore, no individual solver shows robust state-of-the-art performance in all kinds of applications. Additionally, the question arises how to choose a well-performing solving strategy for a given application; this is a challenging question even for solver and domain experts. One way to address this issue is the use of portfolio solvers, that is, a set of different solvers or solver configurations. We present three new automatic portfolio methods: (i) automatic construction of parallel portfolio solvers (ACPP) via algorithm configuration,(ii) solving the $NP$-hard problem of finding effective algorithm schedules with Answer Set Programming (aspeed), and (iii) a flexible algorithm selection framework (claspfolio2) allowing for fair comparison of different selection approaches. All three methods show improved performance and robustness in comparison to individual solvers on heterogeneous instance sets from many different applications. Since parallel solvers are important to effectively solve hard problems on parallel computation systems (e.g., multi-core processors), we extend all three approaches to be effectively applicable in parallel settings. We conducted extensive experimental studies different instance sets from ASP, CSP, MAXSAT, Operation Research (OR), SAT and QBF that indicate an improvement in the state-of-the-art solving heterogeneous instance sets. Last but not least, from our experimental studies, we deduce practical advice regarding the question when to apply which of our methods.
Institutions are facing the challenge to integrate legacy systems with steadily growing new ones, using different technologies and interaction patterns. With the demand of offering the best potential of all systems, several not matching systems including their functions have to be aggregated and offered in a useable way. This paper presents an adaptive, generalizable and self-organized Personal Learning Environment (PLE) framework with the potential to integrate several heterogeneous services using a service-oriented architecture. First, a general overview over the field is given, followed by the description of the core components of the PLE framework. A prototypical implementation is presented. Finally, it’s shown how the PLE framework can be dynamically adapted to a changing system environment, reflecting experiences from first user studies.
While the maturity of process mining algorithms increases and more process mining tools enter the market, process mining projects still face the problem of different levels of abstraction when comparing events with modeled business activities. Current approaches for event log abstraction try to abstract from the events in an automated way that does not capture the required domain knowledge to fit business activities. This can lead to misinterpretation of discovered process models. We developed an approach that aims to abstract an event log to the same abstraction level that is needed by the business. We use domain knowledge extracted from existing process documentation to semi-automatically match events and activities. Our abstraction approach is able to deal with n:m relations between events and activities and also supports concurrency. We evaluated our approach in two case studies with a German IT outsourcing company. (C) 2014 Elsevier Ltd. All rights reserved.
The correctness of model transformations is a crucial element for model-driven engineering of high-quality software. A prerequisite to verify model transformations at the level of the model transformation specification is that an unambiguous formal semantics exists and that the implementation of the model transformation language adheres to this semantics. However, for existing relational model transformation approaches, it is usually not really clear under which constraints particular implementations really conform to the formal semantics. In this paper, we will bridge this gap for the formal semantics of triple graph grammars (TGG) and an existing efficient implementation. While the formal semantics assumes backtracking and ignores non-determinism, practical implementations do not support backtracking, require rule sets that ensure determinism, and include further optimizations. Therefore, we capture how the considered TGG implementation realizes the transformation by means of operational rules, define required criteria, and show conformance to the formal semantics if these criteria are fulfilled. We further outline how static and runtime checks can be employed to guarantee these criteria.
claspfolio 2
(2014)
Building on the award-winning, portfolio-based ASP solver claspfolio, we present claspfolio 2, a modular and open solver architecture that integrates several different portfolio-based algorithm selection approaches and techniques. The claspfolio 2 solver framework supports various feature generators, solver selection approaches, solver portfolios, as well as solver-schedule-based pre-solving techniques. The default configuration of claspfolio 2 relies on a light-weight version of the ASP solver clasp to generate static and dynamic instance features. The flexible open design of claspfolio 2 is a distinguishing factor even beyond ASP. As such, it provides a unique framework for comparing and combining existing portfolio-based algorithm selection approaches and techniques in a single, unified framework. Taking advantage of this, we conducted an extensive experimental study to assess the impact of different feature sets, selection approaches and base solver portfolios. In addition to gaining substantial insights into the utility of the various approaches and techniques, we identified a default configuration of claspfolio 2 that achieves substantial performance gains not only over clasp's default configuration and the earlier version of claspfolio, but also over manually tuned configurations of clasp.
Cloud-RAID
(2014)
In this project I constructed a workflow that takes a DNA sequence as input and provides a phylogenetic tree, consisting of the input sequence and other sequences which were found during a database search. In this phylogenetic tree the sequences are arranged depending on similarities. In bioinformatics, constructing phylogenetic trees is often used to explore the evolutionary relationships of genes or organisms and to understand the mechanisms of evolution itself.
In the geoinformatics field, remote sensing data is often used for analyzing the characteristics of the current investigation area. This includes DEMs, which are simple raster grids containing grey scales representing the respective elevation values. The project CREADED that is presented in this paper aims at making these monochrome raster images more significant and more intuitively interpretable. For this purpose, an executable interactive model for creating a colored and relief-shaded Digital Elevation Model (DEM) has been designed using the jABC framework. The process is based on standard jABC-SIBs and SIBs that provide specific GIS functions, which are available as Web services, command line tools and scripts.
Through the use of next generation sequencing (NGS) technology, a lot of newly sequenced organisms are now available. Annotating those genes is one of the most challenging tasks in sequence biology. Here, we present an automated workflow to find homologue proteins, annotate sequences according to function and create a three-dimensional model.
E-Learning Symposium 2014
(2014)
Der Tagungsband zum E-Learning Symposium 2014 an der Universität Potsdam beleuchtet die diversen Zielgruppen und Anwendungsbereiche, die aktuell in der E-Learning-Forschung angesprochen werden. Während im letzten Symposium 2012 der Dozierende mit den unterschiedlichen Möglichkeiten der Studierendenaktivierung und Lehrgestaltung im Fokus der Diskussionen stand, werden in diesem Jahr in einem großen Teil der Beiträge die Studierenden ins Zentrum der Aufmerksamkeit gerückt. Dass nicht nur der Inhalt des Lernmediums für den Lernerfolg eine Rolle spielt, sondern auch dessen Unterhaltungswert und die Freude, die die Lernenden während des Prozesses der Wissensakquise empfinden, zeigt sehr anschaulich die Keynote von Linda Breitlauch zum Thema „Faites vos Jeux“ (Spielen Sie jetzt). Der Beitrag von Zoerner et al. verbindet den Gedanken des spiele-basierten Lernens mit dem nach wie vor aktuellen Thema des mobilen Lernens. Auch in diesem Forschungsbereich spielt die Fokussierung auf den Lernenden eine immer herausragendere Rolle. Einen Schritt weiter in Richtung Individualisierung geht in diesem Zusammenhang der eingeladene Vortrag von Christoph Rensing, der sich mit der Adaptivität von mobilen Lernanwendungen beschäftigt. Mit Hilfe zur Verfügung stehender Kontextinformationen sollen gezielt individuelle Lernprozesse unterstützt werden. Alle Beiträge, die sich auf mobile Applikationen und auf Spiele beziehen, sprechen auch die zwischenmenschliche Komponente am Lernen an. So wird neben der Mobilität insbesondere auch der Austausch von Lernobjekten zwischen Lernenden (vergleiche den Beitrag von Zoerner et al.) sowie die Kooperation zwischen Lernenden (siehe Beitrag von Kallookaran und Robra-Bissantz) diskutiert. Der interpersonelle Kontakt spielt allerdings ebenfalls in den Beiträgen ohne Spiel- oder App-Fokussierung eine Rolle. Tutoren werden beispielsweise zur Moderation von Lernprozessen eingesetzt und Lerngruppen gegründet um das problem-orientierte Lernen stärker in den Mittelpunkt zu rücken (siehe Beitrag von Mach und Dirwelis) bzw. näher am Bedarf der Studierenden zu arbeiten (wie in eingeladenen Vortrag von Tatiana N. Noskova sowie in dem Beitrag von Mach und Dirwelis beschrieben). In der Evaluation wird ebenfalls der Schritt weg von anonymen, akkumulierten statistischen Auswertungen hin zu individualisierten Nutzerprofilen im Bereich des Learning Analytics untersucht (vergleiche dazu den Beitrag von Ifenthaler). Neben der Schwerpunktsetzung auf die Lernenden und deren Mobilität rückt das Thema Transmedialität stärker ins Zentrum der Forschung. Während schon die Keynote mit ihrem Spielefokus darauf anspricht, geht es in weiteren Beiträgen darum Abläufe aus der analogen Welt bestmöglich in der digitalen Welt abzubilden. Lerninhalte, die bisher mittels Bildern und Texten für Lehrende und Lernende zugänglich gemacht wurden, werden nunmehr mit weiteren Medien, insbesondere Videos, angereichert um deren Verständnis zu erhöhen. Dies ist beispielsweise geeignet, um Bewegungsabläufe im Sport (vergleiche dazu den Beitrag von Owassapian und Hensinger) oder musikpraktische Übungen wie Bodyperkussion (beschrieben im Beitrag von Buschmann und Glasemann) zu erlernen Lernendenfokussierung, persönlicher Austausch, Mobilität und Transmedialität sind somit einige der Kernthemen, die Sie in diesem Sammelband erwarten. Auch zeigt die häufige Verknüpfung verschedener dieser Kernthemen, dass keines davon ein Randthema ist, sondern sich die Summe aus allen im E-Learning bündelt und damit eine neue Qualität für Lehre, Studium und Forschung erreicht werden kann.
Mobile Endgeräte und die dazugehörigen Applikationen sind zu einem unverzichtbaren Bestandteil des täglichen Lebens geworden und ermöglichen den ortsund zeitunabhängigen Zugriff auf wichtige Informationen. Hochschulspezifische An- gebote sind im mobilen Bereich hingegen noch immer nicht flächendeckend anzutreffen und lassen sich i. d. R. nur auf Einzelaktivitäten Studierender und Lehrender zurückführen. Dabei können mobile Applikationen einen essentiellen Beitrag zur Verbesserung der studentischen Selbstorganisation sowie für die Ausgestaltung und Ergänzung von konkreten Lehr-/Lernszenarien leisten. Dieser Artikel stellt ein modulares Hochschul-App-Framework vor, das sowohl zentrale campusbezogene Dienste als auch dezentrale Lernapplikationen unter einer Oberfläche vereint anbietet. Anhand einer Analyse von Stärken und Schwächen werden verschiedene Ansätze in Hinblick auf Anforderungen, Entwicklung, Wartung und Betrieb der Hochschul-App zusammengefasst und bewertet. Es wird auf die zugrundeliegende serviceorientierte Architektur eingegangen, die eine Portierung der Applikation auf andere Hochschulen mit einem vertretbaren Aufwand ermöglicht. Der Beitrag schließt mit einer Darstellung der ersten Ergebnisse und weiterführender Überlegungen und Arbeiten.
Enterprise-specific in-memory data managment : HYRISEc - an in-memory column store engine for OLXP
(2014)
Exploratory Data Analysis
(2014)
In bioinformatics the term exploratory data analysis refers to different methods to get an overview of large biological data sets. Hence, it helps to create a framework for further analysis and hypothesis testing. The workflow facilitates this first important step of the data analysis created by high-throughput technologies. The results are different plots showing the structure of the measurements. The goal of the workflow is the automatization of the exploratory data analysis, but also the flexibility should be guaranteed. The basic tool is the free software R.
Students beginning their studies at university face manifold problems such as orientation in a new environment and organizing their courses. This article presents the implementation and successful empirical evaluation of the pervasive browser-based educational game "FreshUP", which aims at helping to overcome the initial difficulties of freshmen. In contrast to a conventional scavenger hunt, mobile pervasive games like FreshUP, bridging in-game and real world activities, have the potential to provide help in a motivating manner using new technology which is currently becoming more and more common. (C) 2013 Elsevier B.V. All rights reserved.
In task-oriented communication, references often need to be effective in their distinctive function, that is, help the hearer identify the referent correctly and as effortlessly as possible. However, it can be challenging for computational or empirical studies to capture referential effectiveness. Empirical findings indicate that human-produced references are not always optimally effective, and that their effectiveness may depend on different aspects of the situational context that can evolve dynamically over the course of an interaction. On this basis, we propose a computational model of effective reference generation which distinguishes speaker behaviour according to its helpfulness to the hearer in a certain situation, and explicitly aims at modelling highly helpful speaker behaviour rather than speaker behaviour invariably. Our model, which extends the planning-based paradigm of sentence generation with a statistical account of effectiveness, can adapt to the situational context by making this distinction newly for each new reference. We find that the generated references resemble those of effective human speakers more closely than references of baseline models, and that they are resolved correctly more often than those of other models participating in a shared-task evaluation with human hearers. Finally, we argue that the model could serve as a methodological framework for computational and empirical research on referential effectiveness.
Geocoder accuracy ranking
(2014)
Finding an address on a map is sometimes tricky: the chosen map application may be unfamiliar with the enclosed region. There are several geocoders on the market, they have different databases and algorithms to compute the query. Consequently, the geocoding results differ in their quality. Fortunately the geocoders provide a rich set of metadata. The workflow described in this paper compares this metadata with the aim to find out which geocoder is offering the best-fitting coordinate for a given address.