Fraunhofer Institut für Integrierte Publikations-und Informationssysteme IPSI

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  • Publication
    Efficient entity resolution for large heterogeneous information spaces
    ( 2011)
    Papadakis, G.
    ;
    Loannou, E.
    ;
    Niederée, C.
    ;
    Fankhauser, P.
    We have recently witnessed an enormous growth in the volume of structured and semi-structured data sets available on the Web. An important prerequisite for using and combining such data sets is the detection and merge of information that describes the same real-world entities, a task known as Entity Resolution. To make this quadratic task efficient, blocking techniques are typically employed. However, the high dynamics, loose schema binding, and heterogeneity of (semi-)structured data, impose new challenges to entity resolution. Existing blocking approaches become inapplicable because they rely on the homogeneity of the considered data and a-priory known schemata. In this paper, we introduce a novel approach for entity resolution, scaling it up for large, noisy, and heterogeneous information spaces. It combines an attribute-agnostic mechanism for building blocks with intelligent block processing techniques that boost blocks with high expected utility, propagate knowledg e about identified matches, and preempt the resolution process when it gets too expensive. Our extensive evaluation on real-world, large, heterogeneous data sets verifies that the suggested approach is both effective and efficient. Copyright 2011 ACM.
  • Publication
    Context-oriented communication and the design of computer-supported discursive learning
    ( 2008)
    Herrmann, T.
    ;
    Kienle, A.
    Computer-supported discursive learning (CSDL) systems for the support of asynchronous discursive learning need to fulfil specific socio-technical conditions. To understand these conditions, we employed design experiments combining aspects of communication theory, empirical findings, and continuous improvement of the investigated prototypes. Our theoretical perspective starts with a context-oriented model of communication which is-as a result of the experiments-extended by including the role of a third-party such as a facilitator. The theory-driven initial design requirements lead to the CSCL-prototype, KOLUMBUS, emphasizing the role of annotations. In KOLUMBUS, annotations can be immediately embedded in their context of learning material. Practical experience with the prototype in five cases reveals possibilities for implementing improvements and observing their impact. On this basis, we provide guidelines for the design of CSDL systems that focus on the support of asyn chronous discursive learning.
  • Publication
    Smart artefacts as affordances for awareness in distributed teams
    ( 2007)
    Streitz, N.
    ;
    Prante, T.
    ;
    Röcker, C.
    ;
    Alphen, D. van
    ;
    Stenzel, R.
    ;
    Magerkurth, C.
    ;
    Lahlou, S.
    ;
    Nosulenko, V.
    ;
    Jegou, F.
    ;
    Sonder, F.
    ;
    Plewe, D.
  • Publication
    Framework for combined video frame synchronization and watermark detection
    ( 2007)
    Hauer, E.
    ;
    Bölke, T.
    ;
    Steinebach, M.
    Most of the MPEG watermarking schemes can only be embedded into I-frames. The other frames will not be marked. Different attacks like frame rate changing can change the frame type of the marked I-frames. Thus the watermark could be detected from wrong I-frames. Due to these attacks an important issue of digital watermarking solutions for MPEG video is the temporal synchronization of the video material to the proportions before the attacks to detect the watermark successfully. The synchronization information can be embed as part of the information watermark or as a second watermark. The weakness point is with the destruction of the synchronization information the watermark can not be detected more. We provide a solution which analyzes the I-frames based on a robust image hash system. The hash solution was developed for JPEG images and can also be used for MPEG I-frames because of their similar structure. The hash values are robust against common manipulations, like compr ession, and can be used to detect the marked frames also after manipulations at the video material. We analyze the usability of the image hash system and develop a concept based on video and MPEG properties.
  • Publication
    Privacy and interruptions in team awareness systems
    ( 2007)
    Röcker, C.
    ;
    Magerkurth, C.
  • Publication
    Informations- und Wissensmanagement
    ( 2007)
    Brocks, H.
    ;
    Hofmann, T.
    ;
    Kamps, T.
  • Publication
    Intelligent privacy support for large public displays
    ( 2007)
    Röcker, C.
    ;
    Hinske, S.
    ;
    Magerkurth, C.