Thesis (Ph. D.)--Texas Woman's University, 1991. / Vita. Includes bibliographical references (leaves 149-160).

Thesis (Ph. D.)--Cornell University, 1997.

Diss. EPFL Lausanne, 2008.

Saarbrücken, Universiẗat, Diss., 2002.

No description available.

The research conducted for this thesis investigates the impact of thesauri on users' information searching behaviour, and the integration of thesauri into information searching interfaces in order to support the searching process. The work reported here consists of two preliminary studies, which served to refine research questions and explore the methodology, followed by two in-depth studies. The two in-depth studies were conducted with FACET, an experimental system developed at the University of Glamorgan in the context of an EPSRC (Engineering and Physical Sciences Research Council)-funded project focussing on faceted information retrieval in indexed multimedia collections. These studies were conducted with the participation of museum and library professionals. The author used a combination of qualitative and quantitative methods, such as "think aloud" protocols, questionnaires, application log files and content analysis. The in-depth studies resulted in important findings regarding the FACET interface which were considered in its further development. Findings also relate to thesaurus use in general - it was for example observed that behaviours such as browsing the thesaurus are not suitable at all search stages, so that users need to be guided in their choice of tools. One of the main findings was that conceptual problems encountered by searchers with little formal search training caused more difficulties than those related to interface design. This resulted in the conclusion that the information searching process needs to be supported by the interface and that more extensive use of thesauri in the form of support tools is possible at different stages of the search process. Based on literature on the information searching process and data from the first FACET study, the basis for a model of information searching in controlled vocabulary enhanced systems was developed and subsequently refined with data from the second in-depth study. This model aims in particular at facilitating the design and development of such systems. It consists of a textual and graphical representation of the search stages and an account of potential problems, their causes, possible detrimental effects on the further progress of the search and suggestions on how these can be avoided, under particular consideration of tools based on controlled vocabularies.

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The World Wide Web as a repository of information has had a great influence on our lives. This influence is increasing as the web introduces applications in addition to information. These applications have several advantages, such as world wide accessibility, distance group learning and collaboration. Furthermore, the web encourages training applications since it offers multi-media that can support all stages of training. On the other hand, the virtual reality technology has been utilised to provide new systematic training methods for surgical procedures. These solutions are usually expensive in terms of cost and computation. In this thesis we propose a novel solution to fulfill the training needs of radiologists performing one type of minimally invasive surgery known as interventional radiology. Our training method combines the capabilities of virtual reality to provide realistic simulation environment together with the web environment to provide platform independent, scalable and accessible system. In this thesis we analyse this type of surgical procedure in order to deduce the training requirements of such an application. Then, we investigate the possibility of fulfilling these requirements within the server-client architecture of the web environment. We study the degree to which current web technologies- such as Java and VRML- can support the development of a three-dimensional virtual environment with complex interactions. Furthermore, we study the plausibility of providing high computational behaviour modelling training environment on the web by utilising physically-based modelling techniques. We also discuss the effect of adopting the web environment on fulfilling the virtual reality and training requirements of our system. Finally, we evaluate the resulting system to find out how useful is the proposed solution from the clinical point of view.

Der große Vorteil eines q-Gramm Indexes liegt darin, dass es möglich ist beliebige Zeichenketten in einer Dokumentensammlung zu suchen. Ein Nachteil jedoch liegt darin, dass bei größer werdenden Datenmengen dieser Index dazu neigt, sehr groß zu werden, was mit einem deutlichem Leistungsabfall verbunden ist. In dieser Arbeit wird eine neuartige Technik vorgestellt, die die Leistung eines q-Gramm Indexes mithilfe zusätzlicher M-Matrizen für jedes q-Gramm und durch die Kombination mit einem invertierten Index erhöht. Eine M-Matrix ist eine Bit-Matrix, die Informationen über die Positionen eines q-Gramms enthält. Auch bei der Kombination von zwei oder mehreren Q-Grammen bieten diese M-Matrizen Informationen über die Positionen der Kombination. Dies kann verwendet werden, um die Komplexität der Zusammenführung der q-Gramm Trefferlisten für eine gegebene Suchanfrage zu reduzieren und verbessert die Leistung des n-Gramm-invertierten Index. Die Kombination mit einem termbasierten invertierten Index beschleunigt die durchschnittliche Suchzeit zusätzlich und vereint die Vorteile beider Index-Formate. Redundante Informationen werden in dem q-Gramm Index reduziert und weitere Funktionalität hinzugefügt, wie z.B. die Bewertung von Treffern nach Relevanz, die Möglichkeit, nach Konzepten zu suchen oder Indexpartitionierungen nach Wichtigkeit der enthaltenen Terme zu erstellen. / The major advantage of the n-gram inverted index is the possibility to locate any given substring in a document collection. Nevertheless, the n-gram inverted index also has its drawbacks: If the collections are getting bigger, this index tends to be very large and the performance drops significantly. A novel technique is proposed to enhance the performance of an n-gram inverted index by using additional m-matrixes for each n-gram and by combining it with an inverted index. An m-matrix is a bit matrix containing information about the positions of an n-gram. When combining two or more n-grams, these m-matrixes provide information about the positions of the combination. This can be used to reduce the complexity of merging the n-gram postings lists for a given search and improves the performance of the n-gram inverted index. The combination with a term based inverted index speeds up the average search time even more and combines the benefits of both index formats. Redundant information is reduced in the n-gram index and further functionality is added like the ranking of hits, the possibility to search for concepts and to create index partitions according to the relevance of the contained terms.