Thèse (M.Inf.) -- Université du Québec à Chicoutimi, programme en extension de l'Université du Québec à Montréal, 2006. / La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Montréal comme exigence partielle de la maîtrise en informatique offerte à l'Université du Québec à Chicoutimi en vertu d'un protocole d'entente avec l'Université du Québec à Montréal. CaQCU Bibliogr.: f. 146-151. Document électronique également accessible en format PDF. CaQCU

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This thesis presents visualisation as a method for research on learner interaction. The visualisation is designed to account for the dynamics of learner interaction across the duration of language classroom activities. The development of this method includes the formulation of a dynamical perspective on learner interaction, which draws on sociocultural and complexity theory. The visualisation is developed with, and applied to, data from three pairs of participants engaged in a series of similar English writing activities in a Norwegian primary classroom. The thesis provides a detailed discussion of how this learner interaction data was transcribed, coded and eventually visualised. The application of the visualisation to the Norwegian primary classroom data resulted in the identification of patterns and phases in the participants' learner interaction. These patterns and phases revealed both common and unique dynamics across the three cases of interaction. The outcome of the visual analysis of one of the cases was used to guide an in-depth analysis of episodes of learner talk. This in-depth analysis confirmed some of the dynamics established by the visual analysis. A final visual analysis identified different change processes in the three cases of learner interaction across the series of similar writing activities. Overall, the visualisation helped to make transparent how both the writing activity and the participants' own contributions affected the dynamics of learner interaction. The thesis concludes that, in the terms of the dynamical perspective developed by the thesis, visualisation was an effective method for describing the dynamics of learner interaction in the writing activities the participants were engaged in. The thesis also suggests that visualisation can be used in conjunction with other methods for researching learner interaction. Finally, the thesis points out some limitations of the present implementation of visualisation, and makes suggestions for how the method can be improved through further research.

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Lors de l'exécution des applications à base d'objets, plusieurs millions d'objets peuvent être créés, utilisés et enfin détruits s'ils ne sont plus référencés. Néanmoins, des dysfonctionnements peuvent apparaitre, quand des objets qui ne sont plus utilisés ne peuvent être détruits car ils sont référencés. De tels objets gaspillent la mémoire principale et les applications utilisent donc d'avantage de mémoire que ce qui est effectivement requis. Nous affirmons que l'utilisation du gestionnaire de mémoire virtuel du système d'exploitation ne convient pas toujours, car ce dernier est totalement isolé des applications. Le système d'exploitation ne peut pas prendre en compte ni le domaine ni la structure des applications. De plus, les applications n'ont aucun moyen de contrôler ou influencer la gestion de la mémoire virtuelle. Dans cette thèse, nous présentons Marea, un gestionnaire de mémoire virtuelle piloté par les applications à base d'objets. Il constitue une solution originale qui permet au développeurs de gérer la mémoire virtuelle au niveau applicatif. Les développeurs d'une application peuvent ordonner à nôtre système de libérer la mémoire principale en transférant les \emph{objets inutilisés, mais encore référencés} vers une mémoire secondaire (telle qu'un disque dur). En plus de la description du modèle et des algorithmes sous-jacents à Marea, nous présentons notre implémentation dans le langage Pharo. Notre approche a été validée à la fois qualitativement et quantitativement. Ainsi, nous avons réalisés des expérimentations et des mesures sur des applications grandeur-nature pour montrer que Marea peut réduire l'empreinte mémoire de 25% et jusqu'à 40%. / During the execution of object-oriented applications, several millions of objects are created, used and then collected if they are not referenced. Problems appear when objects are unused but cannot be garbage-collected because they are still referenced from other objects. This is an issue because those objects waste primary memory and applications use more primary memory than what they actually need. We claim that relying on operating systems (OS) virtual memory is not always enough since it is completely transparent to applications. The OS cannot take into account the domain and structure of applications. At the same time, applications have no way to control nor influence memory management. In this dissertation, we present Marea, an efficient application-level virtual memory for object-oriented programming languages. Its main goal is to offer the programmer a novel solution to handle application-level memory. Developers can instruct our system to release primary memory by swapping out unused yet referenced objects to secondary memory. Marea is designed to: 1) save as much memory as possible i.e., the memory used by its infrastructure is minimal compared to the amount of memory released by swapping out unused objects. 2) minimize the overhead i.e., the swapping process is fast enough to avoid slowing down applications’ primary computations. 3) allow the programmer to control or influence the objects to swap. Besides describing the model and the algorithms behind Marea, we also present our implementation in the Pharo programming language. Our approach has been qualitatively and quantitatively validated. Our experiments and benchmarks on real-world applications show that Marea can reduce the memory footprint between 25% and 40%.

Relational information visualisation concerns viewing relational data, where the underlying data model is a graph. Hierarchical visualisation is one of hot topics in graph visualisation in which the data is organised in a hierarchical structure. As the amount of information, that we want to visualise, becomes larger and the relations become more complex, classical visualisation techniques and hierarchical drawing methods tend to be inadequate.Traditional hierarchical visualisation algorithms are more concerned with the readability of the layouts. They usually do not consider the efficient utilisation of the geometrical plane for the drawings. Therefore, for most hierarchical layouts, a large portion of display space is wasted as background. The aim of this research is to investigate a space-efficient approach to handle the visualisation of large hierarchies in two-dimensional spaces. This thesis introduces a new graph visualisation approach called enclosure+ connection for visualizing large hierarchies. This approach maximises the space utilisation by taking advantages of the traditional enclosure partitioning approach, while it retains the display of a traditional node-link diagram to hopefully provide users a direct perception of relational structures. The main contribution of this thesis is layout and navigation algorithms for visualising large hierarchies. Two layout algorithms, the space-optimised tree and the EncCon tree, have been developed to achieve the space-efficient visualisation. Both algorithms use the enclosure concept to define layout of hierarchies, which ensure the efficient utilisation of display space. Two focus+context navigation and interaction methods have been proposed to cooperate with the visualization of large hierarchies. Several advanced computer graphics approaches, such as graphic distortion and transparency, are used for the development of these navigation methods. Two case studies have been implemented to evaluate the layout algorithms and the associated navigation methods. The first case study is an application of a shared collaborative workspace which aims to provide users with a better assistance for visual manipulation and navigation of knowledge-based information. The second case study is a visual browser for navigating large-scale online product catalogues. Although the case studies have provided some useful evaluation, formal usability studies would be required to justify fully the effectiveness of these layout and navigation methods. Although this task has not carried out in this research, the author has presented his usability study's plan as a future work.

This study explores the potential for British housing developers to use virtual reality (VR) for the design and evaluation of housing developments. Four research questions were formulated after a review of relevant literature on house-building, VR technology and industrial innovation. These cover the context, technical problems and implementation issues related to VR use in the house-building industry. To address these questions the following tasks were undertaken: firstly a survey of the top 100 British housing developers' use of computer-aided design (CAD) and visualisation software and their attitudes to VR; secondly practical trials of PC-based VR systems for the modelling of housing developments; thirdly a case study of VR implementation in a British house-building company; and fourthly a multiple case study of VR use in Japanese house-building companies. The overall research problem is addressed by recourse to the findings of the different research methods. The use of IT and the house-building organisation, similarities and differences between CAD and VR implementation, and comparison between Japanese and British house-builders VR use are discussed. VR in house-building practice and policy is then considered. A number of general conclusions are drawn from this study. First, that PC-based VR is of use to British housing developers for explaining design intent to non-designers, both within and outside to the organisation. Second, that housing developers' use of virtual reality at the early design stages is hampered by the current state of the technology. Third, that organisational transformation is required for housing developers to implement and obtain maximum benefit from virtual reality. Finally future scenarios are explored to provide the house-building industry and policy makers with information on which to base decisions about how to invest or promote investment in virtual reality.

Relational information visualisation concerns viewing relational data, where the underlying data model is a graph. Hierarchical visualisation is one of hot topics in graph visualisation in which the data is organised in a hierarchical structure. As the amount of information, that we want to visualise, becomes larger and the relations become more complex, classical visualisation techniques and hierarchical drawing methods tend to be inadequate.Traditional hierarchical visualisation algorithms are more concerned with the readability of the layouts. They usually do not consider the efficient utilisation of the geometrical plane for the drawings. Therefore, for most hierarchical layouts, a large portion of display space is wasted as background. The aim of this research is to investigate a space-efficient approach to handle the visualisation of large hierarchies in two-dimensional spaces. This thesis introduces a new graph visualisation approach called enclosure+ connection for visualizing large hierarchies. This approach maximises the space utilisation by taking advantages of the traditional enclosure partitioning approach, while it retains the display of a traditional node-link diagram to hopefully provide users a direct perception of relational structures. The main contribution of this thesis is layout and navigation algorithms for visualising large hierarchies. Two layout algorithms, the space-optimised tree and the EncCon tree, have been developed to achieve the space-efficient visualisation. Both algorithms use the enclosure concept to define layout of hierarchies, which ensure the efficient utilisation of display space. Two focus+context navigation and interaction methods have been proposed to cooperate with the visualization of large hierarchies. Several advanced computer graphics approaches, such as graphic distortion and transparency, are used for the development of these navigation methods. Two case studies have been implemented to evaluate the layout algorithms and the associated navigation methods. The first case study is an application of a shared collaborative workspace which aims to provide users with a better assistance for visual manipulation and navigation of knowledge-based information. The second case study is a visual browser for navigating large-scale online product catalogues. Although the case studies have provided some useful evaluation, formal usability studies would be required to justify fully the effectiveness of these layout and navigation methods. Although this task has not carried out in this research, the author has presented his usability study's plan as a future work.