Cette thèse est consacrée à la restauration et l'estimation des paramètres par filtrage dans les modèles de chaîne de Markov cachée classique, couple et triplet à sauts Markoviens. Nous proposons deux nouvelles méthodes d'approximation dans le cas des systèmes linéaires gaussiens à sauts Markoviens. La première est fondée sur l'utilisation des chaînes de Markov cachées par du bruit à mémoire longue, on obtient alors une méthode " partiellement non supervisée" dans la quelle certains paramètres, peuvent être estimés en utilisant une version adaptative de l'algorithme EM ou ICE, les résultats obtenus sont encourageant et comparables avec les méthodes classiquement utilisées du type (Kalman/Particulaire). La deuxième exploite l'idée de ne garder à chaque instant que les trajectoires les plus probables; là aussi, on obtient une méthode très rapide donnant des résultats très intéressants. Nous proposons par la suite deux familles de modèles à sauts qui sont originaux. la première est très générale où le processus couple composé du processus d'intérêt et celui des observations conditionnellement aux sauts, est une chaîne de Markov cachée, et nous proposons une extension du filtrage particulaire à cette famille. La deuxième, est une sous famille de la première où le couple composé de la chaîne des sauts et le processus d'observations est Markovien dans ce dernier cas le filtrage optimal exact est possible avec une complexité linéaire dans le temps. L'utilisation de la deuxième famille en tant qu'approximation de la première est alors étudiée et les résultats exposés dans ce mémoire semblent très encourageants / This thesis is devoted to the restoration problem and the parameter estimation by filtering in the traditional hidden Markov chain model, couple and triplet with Markovian jumps. We propose two new approximate methods in the case of Gaussian linear systems with Markovian jumps. first is founded to use the hidden Markov chains by noise with long memory, we obtains a method " partially not supervised" some parameters, can be estimated by using an adaptive version of EM or ICE algorithm, the results obtained are encouraging and comparable with the methods used classically (Kalman/Particle). The second one exploits idea to keep at every moment only the most probable trajectories; we obtains a very fast method giving very interesting results. Then we propose two families of models to jumps which are original. The first one is very general where the process couples made up of the hidden and the observations process conditionally to the jumps, are a hidden Markov chain, and we propose an extension of particulate filtering to this family. The second is under family of the first, where the couple made up of the jumps and the observations process is Markovian, in this last case exact optimal filtering is possible with a linear complexity in time. Using of the second family to approach the first one is studied and the results exposed in this memory seem very encouraging

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Cette thèse est consacrée à la restauration et l'estimation des paramètres par filtrage dans les modèles de chaîne de Markov cachée classique, couple et triplet à sauts Markoviens. Nous proposons deux nouvelles méthodes d'approximation dans le cas des systèmes linéaires gaussiens à sauts Markoviens. La première est fondée sur l'utilisation des chaînes de Markov cachées par du bruit à mémoire longue, on obtient alors une méthode " partiellement non supervisée" dans la quelle certains paramètres, peuvent être estimés en utilisant une version adaptative de l'algorithme EM ou ICE, les résultats obtenus sont encourageant et comparables avec les méthodes classiquement utilisées du type (Kalman/Particulaire). La deuxième exploite l'idée de ne garder à chaque instant que les trajectoires les plus probables; là aussi, on obtient une méthode très rapide donnant des résultats très intéressants. Nous proposons par la suite deux familles de modèles à sauts qui sont originaux. la première est très générale où le processus couple composé du processus d'intérêt et celui des observations conditionnellement aux sauts, est une chaîne de Markov cachée, et nous proposons une extension du filtrage particulaire à cette famille. La deuxième, est une sous famille de la première où le couple composé de la chaîne des sauts et le processus d'observations est Markovien dans ce dernier cas le filtrage optimal exact est possible avec une complexité linéaire dans le temps. L'utilisation de la deuxième famille en tant qu'approximation de la première est alors étudiée et les résultats exposés dans ce mémoire semblent très encourageants

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

In this study, the possibility of using low pressure hydrogenated steam to simulate primary water reactor conditions is examined. The oxides formed on Alloy 600 (WF675) between 350 Celsius and 500 Celsius in low pressure hydrogenated steam (with a ratio of oxygen at the Ni/NiO to oxygen in the system of 20) have been characterised using analytical electron microscopy (AEM) and compared to oxide that formed in a high pressure water in a autoclave at 350 Celsius with 30 cc/kg of hydrogen. Preferential oxidation of grain boundaries and bulk internal oxidation were observed on samples prepared by oxide polishing suspension (OPS). Conversely, samples mechanically ground to 600 grit produced a continuous, protective oxide film which suppressed the preferential and internal oxidation. The surface preparation changed the form of the oxides in both steam and autoclave tests. The preferential oxidation rate has been determined to be K_{oxide} = Aexp{-Q/RT}with A = 2.27×10^(−3) m^(2)s^(−1) and Q = 221 kJ.mol^(−1) (activation energy) for WF675 and A = 5.04 × 10^(−7) m^(2)s^(−1) and Q = 171 kJ.mol^(−1) for 15% cold worked WF675. These values are consistent with the activation energy of primary water stress corrosion cracking (PWSCC) initiation. Bulk oxygen diffusivities were calculated from the internal oxidation after 500 h exposures. At 500 Celsius the oxygen diffusivity was determined to be 1.79×10^(−20) m^(2)s^(−1) for WF675 and 1.21×10^(−20) m^(2)s^(−1) for 15% cold worked WF675, the oxygen diffusivity at 400 Celsius in 15% cold worked WF675 was calculated to be 1.49×10^(−22) m^(2)s^(−1).The Cr-depletion associated with preferential oxidation has been assessed by AEM. The Cr-depletion was asymmetric and it could not be accounted for by local variations in the diffusion rate. Chemically induced grain boundary migration is suggested as a possible explanation. Constant load SCC tests conducted in hydrogenated steam at 400 Celsius have shown a similar trend to the classical dependency of PWSCC as a function of potential. The SCC samples were also prepared with two surface finishes, OPS and 600 grit. In all SCC tests, significantly more cracking was observed on the OPS surface and all failures initiated from this surface.

Philosophiae Doctor - PhD / This thesis examines the way in which the recognition of diversity can be applied as a strategy in South African education to erode the bitter legacy of colonial education. The establishment of formal education, built on a western foundation, was set up against a background of colonisation as a process aimed at political subjugation and economic exploitation. It is especially how education was utilised as a tool of colonisation in order to facilitate the above-mentioned subjugation and exploitation through a process of cultural subjugation that will be placed under the spotlight. In chapter three, the process of cultural subjugation outlined in chapter two, is related to the establishment and development of colonial education in South Africa and also how Apartheid was a form of internal colonialism with apartheid education continuing the process of cultural subjugation for political control and economic exploitation. Colonial subjugation was, however, not passively accepted by the subjugated. From the outset, subjugation spawned resistance and would eventually grow into large-scale opposition aimed at the overall casting off of the colonial yoke. This opposition eventually led to the political freedom of 1994. The political freedom of 1994 and the judicial framework for the dismantling of the legacy of colonial education would not, on its own or overnight, be able to dismantle the effects of centuries of subjugation. The dismantling of the inheritance of colonialism, together with colonial education, requires deliberate and constructive action. Such a process will have to include putting an end to the subjugation of the numerous voices characteristic of South Africa. Ending this subjugation does not mean the continuation of a position alongside and beneath a socially constructed dominant, but rather a process (a struggle?) where it can take its place impartially, alongside and equal to other voices in the greater diverse whole. It is against the above background that teaching strategies for the handling of diversity will be critically examined and for which recommendations are made for strategies, within the South African context, through which the dismantling of the colonial legacy of cultural subjugation for political control and economic exploitation can take place.

This thesis set out to ascertain the position of recent Australian Governments on the latest instalments of Asian regionalism in the context of an assessment of whether there has been a redefinition of Asia and thus a redefinition of Australia???s engagement with Asia. It will concentrate on the broad themes of politico-strategic and economic engagement. Whilst there has been extensive research and documentation on the Asian economic crisis there has been less work on the issue of a new Asian regionalism and the implications for Australia???s complex and variable engagement with the region. This is the basis for the claim to originality of this thesis, a claim supported by its focus on the practical and policy implications of Australia???s engagement, or lack of it, with regional institutions. The process of regional integration has been extremely slow, thus supporting the conclusion that there is no evidence of a major redefinition of Asia. Efforts at Asian regionalism are meeting obstacles that pose immense challenges. Asian regionalism remains nascent and poorly defined. This reflects the diversity and enormous disparities in cultures, political systems and the levels of economic development and differences over economic philosophies within East Asia. What is discernible is that the regionalism is proceeding more rapidly on financial issues than on trade, and in the security area it is conspicuously absent. This research highlights the fact that the question of Asian engagement remains a sensitive issue in Australia and continues to grow more complex. Australia???s engagement with Asia since 1996 has been variable because of the Howard Government???s broader balance of priorities between global and regional issues, and because of the changing nature of the Asian region. The perception gleaned from sources is that, for the Australian Government, regionalism initiatives are characterised by much discussion but lack substance. Consequently, this appears to have led the Government to the position that exclusion from some manifestations of regionalism is not so important. Australia is excluded from some of the regional architectures being constructed. In its efforts to seek inclusion in ASEAN + 3 and ASEM, Australia is facing the same barriers that have stood in the way of an AFTA-CER agreement. Exclusion would be important if the performance of regional groupings was not so indifferent. Exclusion from ASEAN + 3 and ASEM, however, does not equate to Australia???s exclusion from the region.

This thesis set out to ascertain the position of recent Australian Governments on the latest instalments of Asian regionalism in the context of an assessment of whether there has been a redefinition of Asia and thus a redefinition of Australia???s engagement with Asia. It will concentrate on the broad themes of politico-strategic and economic engagement. Whilst there has been extensive research and documentation on the Asian economic crisis there has been less work on the issue of a new Asian regionalism and the implications for Australia???s complex and variable engagement with the region. This is the basis for the claim to originality of this thesis, a claim supported by its focus on the practical and policy implications of Australia???s engagement, or lack of it, with regional institutions. The process of regional integration has been extremely slow, thus supporting the conclusion that there is no evidence of a major redefinition of Asia. Efforts at Asian regionalism are meeting obstacles that pose immense challenges. Asian regionalism remains nascent and poorly defined. This reflects the diversity and enormous disparities in cultures, political systems and the levels of economic development and differences over economic philosophies within East Asia. What is discernible is that the regionalism is proceeding more rapidly on financial issues than on trade, and in the security area it is conspicuously absent. This research highlights the fact that the question of Asian engagement remains a sensitive issue in Australia and continues to grow more complex. Australia???s engagement with Asia since 1996 has been variable because of the Howard Government???s broader balance of priorities between global and regional issues, and because of the changing nature of the Asian region. The perception gleaned from sources is that, for the Australian Government, regionalism initiatives are characterised by much discussion but lack substance. Consequently, this appears to have led the Government to the position that exclusion from some manifestations of regionalism is not so important. Australia is excluded from some of the regional architectures being constructed. In its efforts to seek inclusion in ASEAN + 3 and ASEM, Australia is facing the same barriers that have stood in the way of an AFTA-CER agreement. Exclusion would be important if the performance of regional groupings was not so indifferent. Exclusion from ASEAN + 3 and ASEM, however, does not equate to Australia???s exclusion from the region.

Landwirt:innen prägen Agrarlandschaften und beeinflussen die Biodiversität maßgeblich. Ein tiefgehendes Verständnis ihrer Entscheidungen zu biodiversitätsfreundlichen Maßnahmen (BFFM) ist essenziell für wirksame Biodiversitätsstrategien. Diese sollen nicht nur Anreize schaffen, sondern auch Maßnahmen auf Landschaftsebene koordinieren. Ziel dieser Dissertation ist es, die Faktoren des Biodiversitätsmanagements europäischer Landwirt:innen zu untersuchen, insbesondere ihre Verhaltensweisen, Wahrnehmungen und räumlichen Entscheidungsprozesse. Die Arbeit umfasst drei aufeinander aufbauende Studien: (i) eine systematische Literaturanalyse zu Motiven und Hindernissen für BFFM, (ii) qualitative Interviews zur Wahrnehmung von Biodiversität und deren Schutz sowie (iii) ein räumliches Entscheidungsexperiment zu Präferenzen für die Platzierung linearer Biodiversitätsmaßnahmen. Die Ergebnisse zeigen, dass betriebliche Entscheidungen durch ein komplexes Zusammenspiel verschiedener Faktoren beeinflusst werden. Über wirtschaftliche und praktische Gesichtspunkte hinaus sind diese Entscheidungen tief in Wertvorstellungen und der Wahrnehmung von Biodiversität verwurzelt. Wenngleich die meisten Befragten ihre landwirtschaftlichen Tätigkeiten möglichst wenig beeinträchtigen wollten, erkannten sie die ökologische Relevanz ihrer Arbeit und waren offen für Anpassungen, sofern sich Möglichkeiten zur Vernetzung bestehender Habitate ergaben. Die erheblichen regionalen Unterschiede verdeutlichen die Notwendigkeit, Biodiversitätsstrategien an spezifische sozioökonomische, kulturelle und ökologische Kontexte anzupassen. Die Berücksichtigung intrinsischer Werte und der kulturellen Verbundenheit mit dem Land kann die Akzeptanz und das Engagement fördern. Zudem kann eine gezielte Abschätzung der Bereitschaft zur Habitatvernetzung die Planung ökologischer Netzwerke optimieren und Transaktionskosten senken, indem Wildtierkorridore mit Präferenzen der Landwirt:innen abgestimmt werden. / Farmers are key actors in agricultural landscapes and have a profound impact on biodiversity. Understanding their decisions to adopt biodiversity-friendly farming measures (BFFM) is crucial for developing effective conservation strategies that not only motivate farmers but also coordinate their efforts to achieve greater biodiversity outcomes at the landscape scale. This dissertation aims to explore the factors that influence farmers’ biodiversity management across Europe, integrating behavioural, perceptual, and spatial dimensions of their decision-making processes. Three interrelated studies were conducted: (i) a systematic literature review synthesising evidence on motivations for and barriers to BFFM adoption, (ii) qualitative interviews exploring farmers’ perceptions of biodiversity and its management, and (iii) a spatial choice experiment investigating preferences for the placement of linear biodiversity measures. The studies show that farmers’ biodiversity management decisions are shaped by a complex interplay of factors. Beyond economic and practical concerns, these decisions are deeply rooted in farmers’ values and perceptions of biodiversity. Although most farmers sought to minimise disturbance to their farming activities, they recognised the ecological significance of their practices at the landscape level and were willing to adapt them where opportunities arose to connect habitats. The considerable regional variability indicates that biodiversity conservation strategies need to be tailored to the specific socio-economic, cultural, and environmental contexts. Conservation measures that resonate with farmers’ intrinsic values and cultural connections to the land may increase adoption and commitment. In view of the habitat fragmentation, predicting farmers’ willingness to participate in connectivity measures can inform efficient ecological network planning and reduce transaction costs by aligning potential corridors with their preferences.