12 research outputs found
Engineering Agile Big-Data Systems
To be effective, data-intensive systems require extensive ongoing customisation to reflect changing user requirements, organisational policies, and the structure and interpretation of the data they hold. Manual customisation is expensive, time-consuming, and error-prone. In large complex systems, the value of the data can be such that exhaustive testing is necessary before any new feature can be added to the existing design. In most cases, the precise details of requirements, policies and data will change during the lifetime of the system, forcing a choice between expensive modification and continued operation with an inefficient design.Engineering Agile Big-Data Systems outlines an approach to dealing with these problems in software and data engineering, describing a methodology for aligning these processes throughout product lifecycles. It discusses tools which can be used to achieve these goals, and, in a number of case studies, shows how the tools and methodology have been used to improve a variety of academic and business systems
Modellierung von touristischen Merkmalen in RDF und Evaluation am Anwendungsfall Vakantieland
Die Tourismus-Domäne ist eine sehr informations-intensive Industrie. Im eTourismus-Bereich ist daher eine mächtiges Datenschema zur geeigneten Speicherung und Abfrage der Daten erforderlich. Bis vor einigen Jahren haben dafür relationale Datenbanken und Dokumenten-zentrierte Systeme ausgereicht. Für einen Touristen spielt aber heute das schnelle und einfache Befriedigen seines Informationsbedürfnisses eine immer größer werdende Rolle. Aus diesem Grund wird mehr und mehr auf den Einsatz von semantischen Technologien im Bereich des eTourismus gesetzt. So geschehen auch bei der Transformation des Tourismus-Portals vakantieland.nl zu einer semantischen Web-Applikation. Eine solche Umstellung bringt jedoch auch neue Probleme mit sich. Zum Beispiel die Frage, wie touristische Informationen geeignet mit Hilfe des Resource Description Frameworks (RDF) modelliert werden können. In dieser Arbeit wird dieser Frage in Bezug auf die Modellierung von Eigenschaften von touristischen Zielen nachgegangen. Dazu wird eine bestehende eTourismus- Ontologie analysiert und basierend darauf ein geeignetes Schema definiert. Anschließend wird die Ontologie einer Evolution unterzogen, um diese an das neue Schema anzupassen. Um den Nutzen des Tourismus- Portals zusätzlich zu erhöhen, werden außerdem die bereits existierenden Filterfunktionen erweitert
Methodology for Conflict Detection and Resolution in Semantic Revision Control Systems
Revision control mechanisms are a crucial part of information systems to keep track of changes. It is one of the key requirements for industrial application of technologies like Linked Data which provides the possibility to integrate data from different systems and domains in a semantic information space. A corresponding semantic revision control system must have the same functionality as established systems (e.g. Git or Subversion). There is also a need for branching to enable parallel work on the same data or concurrent access to it. This directly introduces the requirement of supporting merges.
This paper presents an approach which makes it possible to merge branches and to detect inconsistencies before creating the merged revision. We use a structural analysis of triple differences as the smallest comparison unit between the branches. The differences that are detected can be accumulated to high level changes, which is an essential step towards semantic merging. We implemented our approach as a prototypical extension of therevision control system R43ples to show proof of concept
Ensimmäinen ja toinen käsikirjoitusversio väitöskirjaa varten
This publication contains the first and the second manuscript version for LauriLahti’s doctoral dissertation in 2015 "Computer-assisted learning based on cumulative vocabularies, conceptual networks and Wikipedia linkage".Tämä julkaisu sisältää ensimmäisen ja toisen käsikirjoitusversion Lauri Lahden väitöskirjaan vuonna 2015 "Tietokoneavusteinen oppiminen perustuen karttuviin sanastoihin, käsiteverkostoihin ja Wikipedian linkitykseen".Not reviewe
Distributed Semantic Social Networks: Architecture, Protocols and Applications
Online social networking has become one of the most popular services on the Web. Especially Facebook with its 845Mio+ monthly active users and 100Mrd+ friendship relations creates a Web inside the Web. Drawing on the metaphor of islands, Facebook is becoming more like a continent. However, users are locked up on this continent with hardly any opportunity to communicate easily with users on other islands and continents or even to relocate trans-continentally. In addition to that, privacy, data ownership and freedom of communication issues are problematically in centralized environments. The idea of distributed social networking enables users to overcome the drawbacks of centralized social networks. The goal of this thesis is to provide an architecture for distributed social networking based on semantic technologies. This architecture consists of semantic artifacts, protocols and services which enable social network applications to work in a distributed environment and with semantic interoperability. Furthermore, this thesis presents applications for distributed semantic social networking and discusses user interfaces, architecture and communication strategies for this application category.Soziale Netzwerke gehören zu den beliebtesten Online Diensten im World Wide Web. Insbesondere Facebook mit seinen mehr als 845 Mio. aktiven Nutzern im Monat und mehr als 100 Mrd. Nutzer- Beziehungen erzeugt ein eigenständiges Web im Web. Den Nutzern dieser Sozialen Netzwerke ist es jedoch schwer möglich mit Nutzern in anderen Sozialen Netzwerken zu kommunizieren oder aber mit ihren Daten in ein anderes Netzwerk zu ziehen. Zusätzlich dazu werden u.a. Privatsphäre, Eigentumsrechte an den eigenen Daten und uneingeschränkte Freiheit in der Kommunikation als problematisch empfunden. Die Idee verteilter Soziale Netzwerke ermöglicht es, diese Probleme zentralisierter Sozialer Netzwerke zu überwinden. Das Ziel dieser Arbeit ist die Darstellung einer Architektur verteilter Soziale Netzwerke welche auf semantischen Technologien basiert. Diese Architektur besteht aus semantischen Artefakten, Protokollen und Diensten und ermöglicht die Kommunikation von Sozialen Anwendungen in einer verteilten Infrastruktur. Darüber hinaus präsentiert diese Arbeit mehrere Applikationen für verteilte semantische Soziale Netzwerke und diskutiert deren Nutzer-Schnittstellen, Architektur und Kommunikationsstrategien.

Ubiquitous Semantic Applications
As Semantic Web technology evolves many open areas emerge, which attract more research focus. In addition to quickly expanding Linked Open Data (LOD) cloud, various embeddable metadata formats (e.g. RDFa, microdata) are becoming more common. Corporations are already using existing Web of Data to create new technologies that were not possible before. Watson by IBM an artificial intelligence computer system capable of answering questions posed in natural language can be a great example.
On the other hand, ubiquitous devices that have a large number of sensors and integrated devices are becoming increasingly powerful and fully featured computing platforms in our pockets and homes. For many people smartphones and tablet computers have already replaced traditional computers as their window to the Internet and to the Web. Hence, the management and presentation of information that is useful to a user is a main requirement for today’s smartphones. And it is becoming extremely important to provide access to the emerging Web of Data from the ubiquitous devices.
In this thesis we investigate how ubiquitous devices can interact with the Semantic Web. We discovered that there are five different approaches for bringing the Semantic Web to ubiquitous devices. We have outlined and discussed in detail existing challenges in implementing this approaches in section 1.2. We have described a conceptual framework for ubiquitous semantic applications in chapter 4. We distinguish three client approaches for accessing semantic data using ubiquitous devices depending on how much of the semantic data processing is performed on the device itself (thin, hybrid and fat clients). These are discussed in chapter 5 along with the solution to every related challenge. Two provider approaches (fat and hybrid) can be distinguished for exposing data from ubiquitous devices on the Semantic Web. These are discussed in chapter 6 along with the solution to every related challenge. We conclude our work with a discussion on each of the contributions of the thesis and propose future work for each of the discussed approach in chapter 7
Ontology evolution: a process-centric survey
Ontology evolution aims at maintaining an ontology up to date with respect to changes in the domain that it models or novel requirements of information systems that it enables. The recent industrial adoption of Semantic Web techniques, which rely on ontologies, has led to the increased importance of the ontology evolution research. Typical approaches to ontology evolution are designed as multiple-stage processes combining techniques from a variety of fields (e.g., natural language processing and reasoning). However, the few existing surveys on this topic lack an in-depth analysis of the various stages of the ontology evolution process. This survey extends the literature by adopting a process-centric view of ontology evolution. Accordingly, we first provide an overall process model synthesized from an overview of the existing models in the literature. Then we survey the major approaches to each of the steps in this process and conclude on future challenges for techniques aiming to solve that particular stage
Operational change management and change pattern identification for ontology evolution
Ontologies can support a variety of purposes, ranging from capturing the conceptual knowledge to the organization of digital content and information. However, information systems are always subject to change and ontology change management can pose challenges. In this sense, the application and representation of ontology changes in terms of higher-level change operations can describe more meaningful semantics behind the applied change. We propose a four phase process that covers the operationalization, representation and detection of higher-level changes in ontology evolution life cycle. We present different levels of change operators based on the granularity and domain-specificity of changes. The first layer is based on generic atomic level change operators, whereas the next two layers are user-defined (generic/domain-specific) change patterns. We introduce the layered change logs for an explicit and complete operational representation of ontology changes. The layered change log model has been used to achieve two purposes, i.e. recording of ontology changes and mining of implicit knowledge such as intent of change, change patterns etc. We formalize the change log using a graph-based approach. We introduce a technique to identify composite changes that not only assist in formulating ontology change log data in a more concise manner, but also help in realizing the semantics and intent behind any applied change. Furthermore, we discover the reusable ordered/unordered domain-specific change patterns. We describe the pattern mining algorithms and evaluate their performance
Ontology change management and identification of change patterns
Ontologies can support a variety of purposes,
ranging from capturing the conceptual knowledge
to the organisation of digital content and information.
However, information systems are always subject to
change and ontology change management can pose challenges.
In this sense, the application and representation
of ontology changes in terms of higher-level change operations
can describe more meaningful semantics behind
the applied change. In this paper, we propose a
fourphase process that covers the operationalization,
representation and detection of higherlevel changes in
ontology evolution life cycle. We present different levels
of change operators based on the granularity and
domainspecificity of changes. The first layer is based on
generic atomic level change operators, whereas the next
two layers are user-defined (generic/domainspecific) change
patterns. We introduce layered change logs for the explicit operational representation of ontology changes.
We formalised the change log using a graph-based approach.
We introduce a technique to identify composite
changes that not only assists in formulating ontology
change log data in a more concise manner, but
also helps in realizing the semantics and intent behind
any applied change. Furthermore, we identify frequent
change sequences that are applied as a reference in order
to discover reusable, often domainspecific and usagedriven
change patterns. We describe the pattern identification
algorithms and evaluate their performance
ConceptMapWiki - a collaborative framework for agglomerating pedagogical knowledge
We propose a new educational framework,ConceptMapWiki, that is a wiki representing pedagogicalknowledge with a collection of concept maps which iscollaboratively created, edited and browsed. The learners andeducators provide complementing contribution to evolvingshared knowledge structures that are stored in a relationaldatabase forming together inter-connected overlappingontologies. Every contribution is stored supplied with timestamps and a user profile enabling to analyze maturing ofknowledge according to various learner-driven criteria.Pedagogically motivated learning paths can be collaborativelydefined and evaluated, and educational games can beincorporated based on browsing and editing concept maps.The proposed framework is believed to be the first wikiarchitecture of it's kind, designed for personalized learningwith an evolving knowledge repository relying on adaptivevisual representations and sound pedagogical motivation.Initial experiments with a functional online prototype indicatepromising educational gain and suggest further research.Peer reviewe