Effective methods for information access are of the greatest importance for our modern lives – particularly with respect to handheld devices. Personalisation is one such method which models a user’s characteristics to deliver content more focused to the user’s needs. The emerging area of sophisticated mobile computing devices has started to inspire new forms of personalised systems that include aspects of the person’s contextual environment. This thesis seeks to understand the role of personalisation and context, to evaluate the effectiveness of context for content personalisation and to investigate the event and map content domain for mobile usage. The work presented in this thesis has three parts: The first part is a user experiment on context that investigated the contextual attributes of time, location and interest, with respect to participants’ perception of their usefulness. Results show highly dynamic and interconnected effects of context on participants’ usefulness ratings. In the second part, these results were applied to create a predictive model of context that was related to attribution theory and then combined with an information retrieval score to create a weighted personalisation model. In the third part of this work, the personalisation model was applied in a mobile experiment. Participants solved situational search tasks using a (i) non-personalized and a (ii) personalized mobile information system, and rating entertainment events based on usefulness. Results showed that the personalised system delivered about 20% more useful content to the mobile user than the non-personalised system, with some indication for reduced search effort in terms of time and the amount of queries per task. The work presented provides evidence for the promising potential of context to facilitate personalised information delivery to users of mobile devices. Overall, it serves as an example of an investigation into the effectiveness of context from multiple angles and provides a potential link to some of the aspects of psychology as a potential source for a deeper understanding of contextual processes in humans.

The field of Information Retrieval recognizes the importance of stemming in improving retrieval effectiveness. This same tool, when applied to searches conducted in the Arabic language, increases the relevancy of documents returned and expands searches to encompass the general meaning of a word instead of the word itself. Since the Arabic language relies mainly on triconsonantal roots for verb forms and derives nouns by adding affixes, words with similar consonants are closely related in meaning. Stemming allows a search term to focus more on the meaning of a term and closely related terms and less on specific character matches. This paper discusses the strengths of light stemming, the best techniques, and components for algorithmic affix-based stemmers used in keyword searching in the Arabic language.

This paper seeks to describe the process by which a database-centric web application was redesigned and rewritten to take advantage of Apache’s Lucene - an open-source information retrieval software library written in the Java programming language. After the implementation of a Lucene-based text index of “semi-structured data”, a college radio station's card catalog application was able to deliver higher-quality search results in significantly less time than it was able to do using just a relational database alone. Additionally, the dramatic improvements in speed and performance even allowed the search results interface to be redesigned and enhanced with an improved pagination system and new features such as faceted search/filtering.

The purpose of this study was to develop a consensus from a panel of experts composed of library deans/directors, reference librarians, and instructors with online teaching experience. The panel developed the methodology necessary for evaluating free sources of information on the Internet for inclusion in academic library holdings by the year 2010. The following areas were explored as they related to the forecast: 1) The changes in higher education institutions that will be necessary to prepare students to deal with free sources of information on the Internet; 2) The procedures that librarians need to develop and implement to ensure that free Internet materials will meet quality standards for inclusion in academic library holdings; and 3) The things that publishers of free sources of information on the Internet need to do to ensure that their materials will be considered for inclusion in academic library holdings. The Delphi panel was composed of 24 members: eight library deans/directors, eight reference librarians, and eight instructors with online teaching experience. The members of the panel were selected from the community colleges of the Tennessee Board of Regents System. In the first round of the study, panelists responded to 10 open-ended questions on an e-mail questionnaire dealing with free sources of information on the Internet. The narrative responses to the questions were specific and provided a basis on which to develop the Round 2 Questionnaire. In the second round of the Delphi study, panelists responded to 9 questions with 42 subparts. The results of this study may be used to project the information needs of students as well as suggest strategies for publishers on the basis of the data collected in this study. A major finding of the study was the need for reliable information in documents on the Internet. The Delphi panel also listed the lack of permanence of Internet sites as a major reason librarians do not use free sources of information on the Internet. The Delphi panel recommended that educators assist students in dealing with Internet materials by teaching them how to use critical thinking skills.

Das Thema Information Retrieval hat insbesondere in Form von Internetsuchmaschinen eine große Bedeutung erlangt. Retrievalsysteme werden für eine Vielzahl unterschiedlicher Rechercheszenarien eingesetzt, unter anderem für firmeninterne Supportdatenbanken, aber auch für die Organisation persönlicher E-Mails. Eine aktuelle Herausforderung besteht in der Bestimmung und Vorhersage der Leistungsfähigkeit einzelner Komponenten dieser Retrievalsysteme, insbesondere der komplexen Wechselwirkungen zwischen ihnen. Für die Implementierung und Konfiguration der Retrievalsysteme und der Retrievalkomponenten werden Fachleute benötigt. Mithilfe der webbasierten Lernanwendung Xtrieval Web Lab können Studierende praktisches Wissen über den Information Retrieval Prozess erwerben, indem sie Retrievalkomponenten zu einem Retrievalsystem zusammenstellen und evaluieren, ohne dafür eine Programmiersprache einsetzen zu müssen. Spielemechaniken leiten die Studierenden bei ihrem Entdeckungsprozess an, motivieren sie und verhindern eine Informationsüberladung durch eine Aufteilung der Lerninhalte. / Information retrieval has achieved great significance in form of search engines for the Internet. Retrieval systems are used in a variety of research scenarios, including corporate support databases, but also for the organization of personal emails. A current challenge is to determine and predict the performance of individual components of these retrieval systems, in particular the complex interactions between them. For the implementation and configuration of retrieval systems and retrieval components professionals are needed. By using the web-based learning application Xtrieval Web Lab students can gain practical knowledge about the information retrieval process by arranging retrieval components in a retrieval system and their evaluation without using a programming language. Game mechanics guide the students in their discovery process, motivate them and prevent information overload by a partition of the learning content.

Das Thema Information Retrieval hat insbesondere in Form von Internetsuchmaschinen eine große Bedeutung erlangt. Retrievalsysteme werden für eine Vielzahl unterschiedlicher Rechercheszenarien eingesetzt, unter anderem für firmeninterne Supportdatenbanken, aber auch für die Organisation persönlicher E-Mails. Eine aktuelle Herausforderung besteht in der Bestimmung und Vorhersage der Leistungsfähigkeit einzelner Komponenten dieser Retrievalsysteme, insbesondere der komplexen Wechselwirkungen zwischen ihnen. Für die Implementierung und Konfiguration der Retrievalsysteme und der Retrievalkomponenten werden Fachleute benötigt. Mithilfe der webbasierten Lernanwendung Xtrieval Web Lab können Studierende praktisches Wissen über den Information Retrieval Prozess erwerben, indem sie Retrievalkomponenten zu einem Retrievalsystem zusammenstellen und evaluieren, ohne dafür eine Programmiersprache einsetzen zu müssen. Spielemechaniken leiten die Studierenden bei ihrem Entdeckungsprozess an, motivieren sie und verhindern eine Informationsüberladung durch eine Aufteilung der Lerninhalte. / Information retrieval has achieved great significance in form of search engines for the Internet. Retrieval systems are used in a variety of research scenarios, including corporate support databases, but also for the organization of personal emails. A current challenge is to determine and predict the performance of individual components of these retrieval systems, in particular the complex interactions between them. For the implementation and configuration of retrieval systems and retrieval components professionals are needed. By using the web-based learning application Xtrieval Web Lab students can gain practical knowledge about the information retrieval process by arranging retrieval components in a retrieval system and their evaluation without using a programming language. Game mechanics guide the students in their discovery process, motivate them and prevent information overload by a partition of the learning content.