Cette thèse porte sur l'élaboration d'un système de manipulation de vidéo. De manière plus précise il s'agit d'extraction et de composition d'objets vidéo. Dans le domaine du traitement d'image fixe, les techniques d'extraction et de démélange (connus sous le nom de matting) et de composition ont vu une réelle amélioration au cours de la dernière décennie, surtout avec l'apparition de méthodes semi-automatiques profitant d'une interaction avec l'utilisateur pour surmonter le gap sémantique. Cela a permis d'aboutir à des algorithmes de plus en plus rapides et de plus en plus robustes. Dans le cadre du traitement de vidéo, cette problématique forme encore un très intéressant challenge, issu du caractère volumineux, en termes complexité de données et de nombre d'images dans la vidéo. Cet élément fait en sorte que la tâche accomplie par l'utilisateur pour marquer un objet d'intérêt peut être très fastidieuse ou souvent impossible. Les travaux que nous avons réalisés au cours de cette thèse se sont concentrés sur l'extension et l'adaptation de la transformée en distance et des courbes actives pour la propagation des marquages d'objets vidéo. Nous avons aussi proposé une amélioration d'une technique pouvant être utilisée avec ces marquages pour l'extraction d'objet vidéo.Dans le premier chapitre nous présentons le contexte et la problématique de nos travaux. Dans le deuxième chapitre nous faisons un tour d'horizon des approches, des outils d'édition de vidéo existant sur le marché, tout en les classant en deux familles : édition par morceaux ou par blocs et édition par objets vidéo. Ensuite, nous présentons un rapide état de l'art sur la segmentation que nous décomposons en trois parties : la segmentation classique, la segmentation interactive et l'image matting. Aussi nous détaillons l'extension de l'image matting au video matting en présentant les principales approches existantes. Le chapitre 3 présente notre première approche pour la propagation de marquage dans les vidéos. Cette approche est une approche volumique 2D+T tirant sa puissance de ce que nous avons bâti une CDT (transformée en distance couleur). Le chapitre 4, lui, présente notre évolution de perception vers un processus de propagation de marquages plus robuste et plus performant basé sur les courbes actives. Nous commençons par faire un état de l'art abrégé sur les courbes actives et nous présentons par la suite notre modélisation et son application. Nous détaillons, aussi le mécanisme de gestion dynamique des poids que nous avons mis en place. Dans le chapitre 5, nous allons discuter de l'application de notre système pour le matting vidéo et nous présentons les améliorations que nous avons apportés à l'approche Spectral Matting, dans ce but

Le corpus de cette thèse est fourni par les exemples en langue grecque de la grande grammaire de Priscien, ouvrage rédigé dans le premier tiers du VIe siècle à Constantinople. La première partie est une longue introduction, qui présente un historique des recherches et évalue la fiabilité de l'édition de référence établie par Martin Hertz en 1855-1859. Un retour à la tradition manuscrite permet de proposer des amendements au texte grec. La deuxième partie présente une typologie de l'utilisation du grec dans la grammaire, à l'exclusion du vocabulaire technique. Ainsi, le recours au grec de Priscien est mis en relation avec la pratique des autres grammairiens latins de l'Antiquité tardive. Elle permet de relativiser l'idée d'une fonction purement heuristique du grec, éclaircissement du latin. La troisième partie consiste en une étude des sources grecques des exemples de Priscien, qu'elles soient nommées comme Apollonios Dyscole ou Hérodien, ou implicites comme la métrique ou les dialectologues. Priscien apparaît très proche, dans son maniement de la littérature technique d'époque romaine, de ses successeurs grammairiens d'époque byzantine. La quatrième et dernière partie se concentre sur la théorie et la pratique comparatistes de Priscien, en particulier dans son étude syntaxique. On y avance l'hypothèse que la recherche d'une correspondance entre faits de langue grecs et latins conduit à transférer des notions et des règles grammaticales du latin vers le grec. Le développement est complété par deux annexes : comparaison du texte des citations grecques de Priscien avec la tradition directe, accords entre les analyses de Priscien et celles des grammairiens grecs.

In this thesis I examine the impact of interaction and participation on Facebook between private individuals and certain hierarchical groups in society, particularly with regard to individual privacy; consider the structure of Facebook’s privacy programming; and seek to establish where the balance of power lies between private individuals and commercial, political and media organisations. I make reference to Foucault’s theory of power, Bourdieu’s theories of power in social space and habitus and Althusser’s theory of interpellation as I record my research. This thesis is a qualitative research project, and I employ Critical Discourse Analysis as the principal research methodology. I focus on four cases studies: Facebook both as the internet platform which facilitates such interaction and the company which operates it; the developers of applications, such as online games, which are mounted on the platform; the network’s use by political parties and their leaders during the UK 2010 General Election campaign; and traditional media platforms as represented by two television annual ‘events’. My findings relate the manner in which individual users are constantly prompted to upload content, principally personal information, thoughts, preferences and relationships to the network, and simultaneously are pressurised into granting access to this information as they seek to fully participate on the social platform. This pressure is applied through applications that are mounted on the platform by commercial, media and political organisations, and I find that Facebook’s affordances to applications developers are instrumental in this process. My research associates these processes with the aforementioned theories of Foucault, Althusser and Bourdieu. My conclusion is that while Facebook continually revises its privacy policy to grant private individuals control over the content, that is the personal information, they upload to the social network, access to this information is a prerequisite for their full participation in the network. Facebook’s continuous introduction of new programmes ensures that private individuals have to choose between interaction and participation on the social network, or exclusion as access to many of the activities it offers is conditional on third party access to their personal information. Further pressure to grant access to the required information is applied through the ability of organisations to feature photographs of users’ Friends who are already using the relevant application. The processes indicate that Facebook creator Mark Zuckerberg is slowly progressing his aim to place the social network at the centre of a newly structured Web based on private individuals.

Within developing countries, there is a digital divide between rural and urban areas. In order to overcome this division, we need to provide locally relevant Information and Communication Technology (ICT) services to these areas. Traditional software development methodologies are not suitable for developing software for rural and underserviced areas because they cannot take into account the unique requirements and complexities of such areas. We set out to find the most appropriate way to engineer suitable software applications for rural communities. We developed a methodological framework for creating software applications for a rural community. We critically examined the restrictions that current South African telecommunications legislation places on software development for underserviced areas. Our socially aware computing framework for creating software applications uses principles from Action Research and Participatory Design as well as best practice guidelines; it helps us address all issues affecting the project success. The validity of our framework was demonstrated by using it to create Multi-modal Telemedicine Intercommunicator (MuTI). MuTI is a prototype system for remote health consultation for a rural community. It allowed for synchronous and asynchronous communications between a clinic in one village and a hospital in the neighbouring village, nearly 20 kilometers away, in the Eastern Cape province of South Africa. It used Voice over Internet Protocol (VoIP) combined with a store and forward approach for communication. MuTI was tested over a Wireless Fidelity (WiFi) network for several months. Our socially aware framework proved to be appropriate for developing locally relevant applications for rural areas in South Africa. We found that MuTI was an improvement on the previous telemedicine solution in the target community. Using the approach also led to several insights into best practice for ICT development projects. We also found that VoIP and WiFi are relevant technologies for rural regions and that further telecommunication liberalisation in South Africa is required in order to spur technological developments in rural and underserviced areas.

Computer scientists must align social and technical factors for communication technologies in developing regions yet lack a framework to do so. The novel Softbridge framework comprises several components to address this gap. The Softbridge stack abstraction supplements the established Open Systems Interconnect model with a collection of technical layers clustered around 'people' issues. The Softbridge stack aligns the technological design of communication systems with awareness of social factors characteristic of developing regions. In a similar fashion, a new evaluation abstraction called Quality of Communication augments traditional Quality of Service by considering socio-cultural factors of a user's perception of system performance. The conceptualisation of these new abstractions was driven by long-term experimental interventions within two South African digital divides. One field study concerned communication bridges for socio-economically disadvantaged Deaf users. The second field study concerned a wireless telehealth system between rural nurses and doctors. The application domains were quite different yet yielded similarities that informed the Softbridge and Quality of Communication abstractions. The third Softbridge component is an iterative socially aware software engineering method that includes action research. This method was used to guide cyclical interventions with target communities to solve community problems with communication technologies. The Softbridge framework components are recursive products of this iterative approach, emerging via critical reflection on the design, evaluation and methodological processes of the respective field studies. Quantitative and qualitative data were triangulated on a series of communication prototypes for each field study with usage metrics, semi-structured interviews, focus groups and observation in the field. Action research journals documented the overall process to achieve post-positivist recoverability rather than positivistic replicability. Analysis of the results from both field studies was iteratively synthesised to develop the Softbridge framework and consider its implications. The most significant finding is that awareness of social issues helps explain why users might not accept a technically sound communication system. It was found that when facilitated effectively by intermediaries, the Softbridge framework enables unintended uses of experimental artefacts that empower users to appropriate communication technologies on their own. Thus, the Softbridge framework helps to align technical and socio-cultural factors.

South Africa has one of the highest HIV+ prevalence rates in the world [1]. Furthermore, social support is beneficial to HIV+ people. Informational support is a type of social support which is used to increase one’s knowledge base [2]. Hayes et al. state that informational support is especially beneficial for those in the early stages of HIV infection [3]. Computer technologies have been used successfully in providing informational support to their users. However, virtual reality (VR) is a relatively unexplored technology in South Africa, and we feel it is a highly appropriate medium for a context where users have little or no prior computing experience. Traditionally, computer interfaces require users to have a learned skillset, but a VR interface does not necessarily require this as it maps more directly to users’ natural interaction techniques with the real world. A key benefit of a virtual environment (VE) is the interactivity and user involvement that it offers through a high degree of navigation and interaction with objects [4]. VR may, initially, seem to be an expensive technology to use in a developing country but it is possible to make use of desktop VR on a consumer-grade PC relatively affordably. This dissertation presents a comparison of the effects of two media, VR and paper (i.e. pamphlets) in communicating supportive information to an HIV+ sample group. We created a VE to provide social and informational support for HIV+ people in the South African context. The design of the VE placed emphasis on creating a typically South African space which users could recognize and find familiar. Our research focused on two rooms containing virtual agents and points of possible interaction: the lounge and the kitchen. In the lounge, a HIV/Aids support group was simulated while the kitchen contained two areas which presented nutritional informational support: Diet and Cleanliness & Hygiene. We conducted a pre- post-test study with 22 HIV+ women at two clinics in Cape Town. Participants were randomly assigned into one of three groups. One group experienced the informational VE (VE), one group received information pamphlets (Text), the control group who received no information until the end of the study (Ctrl). Participants attended three experiment meetings over a five week period. Participants completed two 3-day food diaries and completed questionnaires that provided measurement for two sets of variables: Food Safety Behaviours (a measure of knowledge of correct food and water safety practices to prevent food-borne illnesses) and Dietary Quality (measure of the diet quality – in terms of quantity, variety, water intake and vitamin supplements, as well as specific food items for the prevention of stomach ailments, a common complaint of HIV infection). While we found no differences between the Text and Ctrl groups, the VE group showed a significant improvement in consuming two (of three) specific food items recommended for the prevention of stomach complaints. This is a particularly striking result given that more than half the participants stated that they routinely did not have enough money to buy food let alone specific healthy foods. The area that contained the information related to stomach complaints was the last imagery experienced by all VE participants. That it was the only area that showed improvement highlights how careful VE authors should be in choosing the actual content for the environment, as well as how that content is delivered. Despite very minimal computing experience and only short training sessions, all participants mentioned that they found the VE easy to use and enjoyed their experience of it. Our results show that VR can indeed be used to deliver informational content to HIV+ women in South Africa.

Digital video games are an immensely popular form of entertainment. The meaningful positive experiences that games facilitate are fundamental to the activity; players are known to invest a lot of time playing games in search of those experiences. Digital games research is polarized. Some studies find games to be a healthy hobby with positive effects; games promote well-being through regular experience of positive psychological experiences such as flow and positive emotions. Others have identified rare problematic use in those players who devote excessive amounts of time to gaming, associating them with social dysfunction, addiction, and maladaptive aggression. While it remains unclear if games cause these effects, or merely coincide with play, the negative effects historically receive more attention in both popular media and academia. Some authorities attempt to reduce the harms associated with games to such an extent that their methods have become national policy affecting all players including those who exhibit no negative outcomes. In South Korea and Taiwan, policing authorities employ a behaviour policy that sets strict daily limits on session length, thereby controlling the amount of time people spend playing games each day. In China, the General Administration of Press and Publication employ a design policy requiring that games service-providers fatigue their games’ mechanics after a period to coax them to take a break sooner than they ordinarily would. Both policy types alter player interaction with games in any given session and it is unclear how these policies affect players in general. This research aims to compare sessions affected by the behaviour policy, design policy, and policy-free sessions in terms of session length, measurable subjective user-experience, the player's intention to return to the game, and their reasons for choosing to stop playing in a particular session. For use in a repeated-measures experiment, we modified the action RPG Torchlight II to simulate both policies. Participants had one session at the same time each week for three consecutive weeks. In varied sequences, participants played a control session unaffected by policy, a one-hour shutdown session representing behaviour policy, and a fatigue session representing design policy. After each session, we recorded their session's length, their user-experience in terms of flow and affect, their intention to return to the game, and their reason for ending the current session. We found that our shutdown condition successfully decreases session length, when compared to the other conditions. The condition facilitates strong flow, moderate positive-affect, and weak negative-affect. The shutdown event does not appear to degrade positive experiences and makes participants slightly more upset (statistically significant) than they would be after choosing to stop playing. This is because players do not get to make that decision, and because players are unable to complete the goals they have set for themselves. Most players intended to play the game again immediately or sometime later in that same day, much sooner (statistically significant) than they would after choosing to stop. This also may be due to satisfaction associated with choosing to stop, or being unable to complete their self-set goals. We found that our fatigue condition increases session length when compared to the other conditions. This result contradicts the intentions associated with design policies: shorter sessions. The fatigue mechanics make the game more difficult, which increases the time required for players to complete the goals they have set for themselves, whether it is to complete a level, quest, or narrative sequence. The condition facilitates high levels of flow, moderate positive-affect and low negative-affect; the condition does not appear to degrade these positive experiences, nor increase negative experience. Most players intended to take the longest breaks between sessions of at least one day, and although we observed that these were longer than the control condition, the differences is not statistically significant. We found that most participants chose to stop playing when the game stopped providing them with positive experiences, or begins to generate discomfort. A large group of participants chose to stop because another activity took priority. Few participants chose to stop because they were satisfied with their session. Less than one third of players explicitly referenced the fatigue mechanics in their decision to stop. Neither policy is holistically better than the other. Both provide strong positive experiences, and have different effects on session length. Whereas it appears that the fatigue condition fails to reduce session length, it also appears that players intend taking longer breaks between sessions, which may reduce total play-time across all sessions. Similarly, the shutdown condition may increase total play time, or at least bring it closer to normal amounts of play-time while also making players more upset. Our operational definition of user-experience is bi-dimensional, and does not include many experiential constructs commonly associated with digital games. During this research, several reliable and valid, and more representative experience measures became available. Any future work on this topic should make use of one of these. Our experiment tested the effects of player experience associated with a single game, genre, and context. Future research should reduce the variation of player factors by focusing on single personalities, typologies, or risk-factors rather than generalizing to all players. We tested out participants only as they played in the early stages of Torchlight II. It is possible that the game's narrative elements, rather than the gameplay mechanics fatigued by the design policy, motivated continued play. We suggest a longitudinal study of the individual policies to explore their effects over many sessions.

L'objectif de cette thèse est d'étudier les problèmes de simulation et d'aide à la décision pour la gestion et le pilotage des systèmes hospitaliers (plateaux médico-techniques, unité de soins, services d' urgence ...). Cette problématique est très importante et fait l'objet depuis quelques années de travaux de recherche dans des laboratoires. A l'heure actuelle, les approches proposées sont des approches prédictives et s'inspirent des méthodes mises en oeuvre dans les systèmes industriels. Il apparaît indispensable de proposer des approches réactives permettant un suivi quasiment en temps réel des systèmes. Le sujet proposé concerne la modélisation des différents types de flux (patients, personnels, matériels, ...) et de leurs interactions et l'évaluation d'indicateurs de performance à définir. Il s'agit donc d'étudier la classe (le domaine) des systèmes et de proposer une méthodologie de simulation et d'aide à la décision pour la gestion et le pilotage. Cette problématique est étudiée dans le cadre du projet NHE (Nouvel hôpital Estaing) à Clermont-Ferrand et s'intéresse plus particulièrement à la conception de modèles génériques des différentes classes de systèmes, à la définition d'indicateurs de performance et à la conception et mise en oeuvre d'outils d'aide à la décision pour les managers hospitaliers (directeur, chef de servive, médecin, cadre de santé ...)

De nos jours, les réseaux sociaux numériques sont devenus des outils de communication incontournables. Chaque jour des dizaines de nouveaux réseaux se créent, des chroniques à la radio leurs sont consacrées, sans parler des livres, des émissions télévisuelles ou les articles de presse. Cette ascension rapide de cet outil communicationnel à usages multiples, suscite l'intérêt de la part d'acteurs provenant des différentes sphères (publique, politique,...) Dispositif sociotechnique, les RSN de par leur facilité d'utilisation et de mise en oeuvre, se sont imposés comme un support favorisant l'échange, le partage (de photos, de vidéos, de liens), l'interaction et la diffusion d'informations de tout ordre. Dans sa première, cette thèse fait l'objet d'une mise en perspective historique de l'emploi de la notion du " réseau ", " réseau social " et des " réseaux sociaux numériques ". Nous verrons que ces termes révèlent des détours d'usages à travers le temps. De plus, nous décrivons les réseaux sociaux numériques par rapport à d'autres possibilités du web 2.0. A partir d'approches philosophiques et théoriques, la deuxième partie tente la construction d'un modèle théorique d'analyse qui prend comme dimension fondamentale l'homme et la technique. Ensuite l'analyse du matériel de recherche dans une démarche empirique/descriptive et une approche exploratoire, permet d'une part, d'élaborer de nouvelles typologies et catégories de réseaux sociaux numériques, et d'autre part, de construire des cartographies des différentes controverses qui entourent cet objet communicationnel complexe.

L'interopérabilité revêt un enjeu majeur pour l'industrie et son absence peut être vue comme un des principaux freins à un travail collaboratif, et plus particulièrement dans les processus collaboratifs aussi bien publics (inter-entreprises) que privé (intra-entreprise). Il parait donc pertinent d'analyser et de détecter d'éventuels manques ou défauts d'interopérabilité dans des entreprises impliquées dans un processus collaboratif. Les recherches en interopérabilité ont montré l'intérêt de mesurer et d'évaluer l'interopérabilité avec la proposition de cadres et de modèles de maturité dans le but d'éviter d'éventuels problèmes d'interopérabilité. Cependant, des approches de détection et d'anticipation de problèmes d'interopérabilité n'existent pas à notre connaissance. Les travaux de recherche proposés dans cette thèse se développent dans un contexte d'ingénierie de processus guidée par les modèles et se proposent d'utiliser des techniques de vérification formelle pour détecter différents types de problèmes ou de pré-somption de problèmes d'interopérabilité. Ceci implique, dans un premier temps, de définir les besoins particuliers en interopérabilité devant être pris en compte dans un contexte colla-boratif. Dans un second temps, il est nécessaire de formaliser ces besoins en un ensemble d'exigences d'interopérabilité, de manière aussi formelle que possible. Ceci a abouti à quatre classes d'exigences d'interopérabilité respectant le cycle de vie d'un processus collaboratif : les exigences de compatibilité, les exigences d'interopération, les exigences d'autonomie et les exigences de réversibilité. Enfin, ces exigences doivent être vérifiées en se référant aux modèles du ou des processus étudiés.