Cette étude traite d’une machine doublement saillante à aimants permanents, utilisée en entraînement direct pour application hydrolienne. Dans un premier temps, différentes approches technologiques utilisées pour l’exploitation hydrolienne sont passées en revue. Ensuite, la génératrice est modélisée par approche circuit. Cette méthode permet de tenir compte de la saturation magnétique et de la variation d’entrefer, tout en offrant un compromis intéressant entre la précision des résultats et le temps de simulation. Le modèle de la DSPM est ensuite couplé avec son convertisseur. Un modèle thermique est également mis en place. Ce modèle est ensuite utilisé pour optimiser simultanément la denture de la DSPM et les paramètres de la commande afin de maximiser le couple et de réduire ses ondulations, importantes dans les machines à saillance. Les paramètres de commande sont également optimisés sur un cycle hydrolien. Le premier critère à minimiser sur cycle concerne les ondulations de couple. Les pertes Joule sont ensuite rajoutées comme second critère. Des fronts de Pareto sont alors déduits et analysés. Finalement, des essais à vide et en charge sur un prototype 2 kW, 50 tr/min ont permis de valider le modèle théorique développé. / This study deals with a doubly salient permanent magnet machine, used in direct drive for tidal application. First, different technological approaches used for tidal power generation are reviewed. Then, the generator is modelled by circuit approach. This method allows for magnetic saturation and airgap variation to be taken into account, while offering an interesting compromise between the accuracy of the results and the simulation time. The DSPM model is then coupled with its converter. A thermal model is also implemented. This model is then used to optimize simultaneously the DSPM teeth and its control parameters in order to maximize the torque and reduce its ripples which are important in salient machines. The control parameters are also optimized on a tidal cycle. The first criterion to be minimized on cycle is the torque ripples. Joule losses are added as a second criterion and Pareto fronts are deduced and analyzed. Finally, tests at no-load and also at load operations on a prototype 2 kW, 50 rpm validate the theoretical model developed

IsaMill is a stirred type mill used in mineral industry for fine and ultra-fine grinding. The difficulty in obtaining the internal flow information in the mill by experimental techniques has prevented the development of the fundamental understanding of the flow and generating general methods for reliable scale-up and optimized design and control parameters. This difficulty can be effectively overcome by numerical simulation based on discrete element method (DEM). In this work a DEM model was developed to study particle flow in a simplified IsaMill. The DEM model was validated by comparing the simulated results of the flow pattern, mixing pattern and power draw with those measured from a same scale lab mill. Spatial distributions of microdynamic variables related to flow and force structure such as local porosity, particle interaction forces, collision velocity and collision frequency have been analyzed. Among the materials properties of particles, it is shown that by decreasing particle/particle sliding friction coefficient, the particle flow becomes more vigorous which is useful to grinding performance. Restitution coefficient does not affect the particle flow significantly. A too low or too high particle density could decrease grinding efficiency. Although grinding medium size affects the flow, its selection may depend on the particle size of the products. Among the operational variables considered, the results show that fill volume and mill speed proved to be important factors in IsaMil process. Increase of fill volume or mill speed increases the interaction between particles and agitating discs which results in a more vigorous motion of the particles. Among the mill properties, particle/stirrer sliding friction plays a major role in energy transfer from stirrer to particles. Although there exists a minimum collision energy as particle/stirrer sliding friction increases, large particle/stirrer sliding friction may improve grinding performance as it has both large collision frequency and collision energy. However, that improvement is only up to a critical particle/disc sliding friction beyond which only input energy increases with little improvement on collision frequency and collision energy. Reducing the distance between stirrers or increasing the size of disc holes improves high energy transfer from discs to particles, leading to high collision frequency and collision energy. Among the different stirrer types, the energy transfer is more effective when disc holes are present. Pin stirrer shows increased collision energy and collision frequency which also result in a high power draw. Using the DEM results, a wear model has been developed to predict the wear pattern of the discs. This model can be used to predict the evolution of the disc wear with the time. It is shown that energy transfer from discs to particles are increased when discs are worn out. An attempt has also been made to analyze the microdynamic properties of the mill for different sizes. It is shown that specific power consumption and impact energy are correlated regardless of the mill size and mill speed.

[Abstract]: There is currently a shortage of irrigation water available for cotton production in Australia due to recent climatic and legislative conditions. Some growers have responded to this water shortage by changing from traditional furrow irrigation to alternative irrigation systems such as centre pivots and lateral move irrigations(collectively known as large mobile irrigation machines – LMIMs). Improved efficiency of irrigation application, as well as labour savings, have been the main reasons for the increased adoption of LMIMs. The use of LMIMs also enables a higher level of control in water application in terms of irrigation volume, timing and placement. As a result, growers now have much greater control over soil moistureconditions which enables the implementation of improved irrigation management strategies that have the potential for improved crop water use productivity (yield/ML).Two irrigation strategies which have been demonstrated to achieve benefits in terms of crop water use are partial rootzone drying (PRD) and deficit irrigation (DI). PRDand DI involve manipulating the placement of irrigation water and the moisture deficit maintained in the root zone, respectively. Neither PRD nor DI is able to beapplied easily under furrow irrigation. However, both PRD and DI may be able to be implemented under LMIMs within the Australian cotton industry. Deficit irrigation has been shown to be effective at improving water use productivity in cotton, although it is not widely used within the Australian cotton industry.Similarly, there has been little research conducted to identify whether cotton responds to partial rootzone drying and there is currently little understanding of theway in which DI and PRD strategies could be implemented commercially using LMIMs.This research carried out from 2002 to 2005 investigated the response of cotton to a range of PRD and deficit irrigation strategies for use under LMIMs. Assessment ofthe biochemical and physiological response of cotton to PRD and regulated deficit irrigation strategies was conducted under glasshouse conditions in Toowoomba, Qld.Field trials conducted under a commercial centre pivot and lateral move situated on the Darling Downs assessed the crop response, soil moisture movement, yield andgross production water use associated with the implementation of a range of PRD and deficit treatments. Modelling of rainfall probability and soil moisture movement were also undertaken to quantify constraints to the successful commercial implementation of irrigation management strategies such as PRD within theAustralian cotton industry.PRD applied to cotton grown in split-pot containers under glasshouse conditions was found to produce a biochemical response in the form of a four fold increase in xylemAbscisic Acid concentration. The application of alternated PRD strategies was generally found to reduce both vegetative (i.e. height, leaf area) and reproductive(i.e. fruiting sites) plant growth compared to Control treatments irrigated on both sides of the plant. Increasing the period between PRD alternations from 5 to 15days when the soil moisture potential in the wet root zone was maintained between 30 and 60 kPa also reduced the plant height and the number of fruiting sites.However, where the soil moisture in the wetted root zone was maintained at <3 kPa and alternation was based on the dry root zone moisture levels 16% (~350 kPa) and10% (>1500 kPa) there was no difference in the major plant growth indicators (i.e. height, fruiting branches, fruiting sites, leaf area) between the various alternatedPRD treatments. This suggests that the level of moisture availability in the wet root zone area is a key factor influencing water uptake and crop stress under alternatedPRD conditions.No significant difference in crop growth or yield was found as a result of the PRD treatments implemented under commercial field conditions. However, this may havebeen attributed to the inability to apply and maintain a sufficient soil moisture gradient across the root zone to successfully induce biochemical signalling from PRD. Practical limitations in the successful application of PRD in cotton production are attributed to the soil hydraulic properties, current irrigation practices (i.e. volumeand frequency of water applied) and the occurrence of in-season rainfall events. Rainfall probability and soil moisture modelling were used to evaluate the practical application of PRD within the Australian cotton industry. This work suggested thatthe creation of a soil moisture gradient across the plant root zone large enough to trigger a PRD response is most likely to be achieved on light textured soils located insemi-arid regions which experience minimal in-season rainfall events. However, the conditions are only met for a relatively small proportion of the current Australiancotton industry. Hence, it would seem that further research into the benefits of implementing PRD in cotton under LMIMs is not warranted.Regulated deficit irrigation applied under glasshouse conditions was found to have a controlling influence over partitioning between vegetative and reproductive growth.Improved physiological and gross production to water use benefits were measured as a result of deficit irrigation under field conditions and regulated deficit irrigationunder glasshouse conditions. Deficit irrigation (79% of predicted ET) under field conditions produced a 31.5% improvement in gross production water use index(GPWUI = Yield / Total water applied (rainfall, irrigation and stored soil moisture)) over commercial practice (i.e. applying 100% of predicted ET). However, thelargest benefits derived from deficit irrigation were associated with the management of crop agronomics (i.e. vegetative growth, retention rate and crop earliness) and the increased ability for capture of in-crop rainfall. Hence, deficit irrigation may provide substantial benefits for the cotton industry in terms of productivity of irrigation water applied as well as total water applied (irrigation, rainfall and soil moisture reserves).The ability to implement a suitable deficit irrigation strategy is regionally and seasonally dependent as the uncertainty over the timing of rainfall events andirrigation allocation both within and between seasons makes the optimal use of water resources difficult. Hence, future research should aim to enhance current cropproduction models to predict crop growth and response to a range of deficit irrigation treatments. Greater knowledge and adoption in the use of climatic predictors (suchas SOI) are required to improve the volume and timing of deficit irrigations applied. An economics framework should be developed which encompasses resource costs and constraints on a farm basis to enable the identification of optimal management practices based on the risk profiles of the various deficit irrigation strategies.Irrigation scheduling under LMIMs is also currently limited by the use of point scale soil moisture measurements (especially under low energy precision applicator LEPA) socks) and this may be improved by the use of plant based sensors.

This work investigates some of the issues and consequences for the field of artificial intelligence and cognitive science, which are related to the perceived limits of computation with current digital equipment. The Church -Turing thesis and the specific properties of Turing machines are examined and some of the philosophical 'in principle' objections, such as the application of G??del's incompleteness theorem, are discussed. It is argued that the misinterpretation of the Church-Turing thesis has led to unfounded assumptions about the limitations of computing machines in general. Modern digital computers, which are based on the von Neuman architecture, can typically be programmed so that they interact effectively with the real word. It is argued that digital computing machines are supersets of Turing machines, if they are, for example, programmed to interact with the real world. Moreover, computing is not restricted to the domain of discrete state machines. Analog computers and real or simulated neural nets exhibit properties that may not be accommodated in a definition of computing, which is based on Turing machines. Consequently, some of the philosophical 'in principle' objections to artificial intelligence may not apply in reference to engineering efforts in artificial intelligence.

L'étude présentée se place dans le contexte de la réduction des perturbations d'origines électrique et mécanique liées aux systèmes industriels de variation de vitesse des machines électriques tournantes. Partant d'une approche tensorielle dédiée à l'étude des machines électriques, nous avons développé un modèle prenant en compte les imperfections d'origine géométrique, celles-ci se traduisant en termes d'harmoniques spatiales. Chaque harmonique est alors considérée comme le fondamental d'une machine virtuelle, sur la base du principe de superposition. Le modèle est ainsi constitué d'autant de machines virtuelles que d'harmoniques. L'étude du modèle d'un point de vue automatique est ensuite effectuée. Enfin, un observateur d'état de type Kalman associé à ce modèle est développé. Le cas du modèle à une harmonique d'espace est traité et la validation de cet observateur est effectué sur un moteur asynchrone à rotor bobiné. Les courants à estimer sont mesurés pour validation expérimentale.

Il s 'agit ici, de mettre en place des méthodologies de détermination des modèles électriques des machines à griffes, en régime permanent et transitoire. Une description de l'alternateur à griffes et de son principe de fonctionnement sera présentée dans le premier chapitre. Ensuite, dans le deuxième chapitre, une analyse fine sera réalisée sur les méthodes d'identification actuellement en vigueur sur les alternateurs de grande puissance en régime permanent. A l'issue de cette analyse, on adaptera ces méthodes aux alternateurs à griffes. Le troisième chapitre consistera en l'étude de la machine en régime transitoire dans le but essentiel de pouvoir évaluer les pertes fer notamment dans le rotor massif. Ceci permettra d'élaborer une méthodologie de séparations des pertes tant en essais qu'en simulations par éléments finis. Dans un quatrième chapitre nous développerons des axes d'améliorations des performances de la machine.

La théorie des automates est apparue pour résoudre des problèmes aussi bien pratiques que théoriques, et ceci dès le début de l'informatique. Désormais, les automates font partie des notions fondamentales de l'informatique, et se retrouvent dans la plupart des logiciels. En 1974, Samuel Eilenberg proposa un modèle de calcul qui unifie la plupart des automates (transducteurs, automates à pile et machines de Turing) et qui a une propriété de modularité intéressante au vu d'applications reposant sur différentes couches d'automates ; comme cela peut être le cas en linguistique computationnelle. Nous proposons d'étudier les techniques permettant d'avoir des machines d'Eilenberg effectives. Cette étude commence par la modélisation de relations calculables à base de flux, puis continue avec l'étude de la simulation des machines d'Eilenberg définies avec ces relations. Le simulateur est un programme fonctionnel énumérant progressivement les solutions, en explorant un espace de recherche selon différentes stratégies. Nous introduisons, en particulier, la notion de machine d'Eilenberg finie pour laquelle nous fournissons une preuve formelle de correction de la simulation. Les relations sont une première composante des machines d'Eilenberg, la deuxième composante étant son contrôle, qui est défini par un automate fini. Dans ce contexte, on peut utiliser une expression régulière comme syntaxe pour décrire la composante de contrôle d'une machine d'Eilenberg. Récemment, un ensemble de travaux exploitant la notion de dérivées de Brzozowski, a été la source d'algorithmes efficaces de synthèse d'automates non-déterministes à partir d'expressions régulières. Nous faisons l'état de l'art de ces algorithmes, tout en donnant une implémentation efficace en OCaml permettant de les comparer les uns aux autres.

Les machines électriques deviennent le mode principal de propulsion des navires civils depuis quelques années car elles présentent de nombreux avantages. Cependant, l'application aux bâtiments militaires pose des problèmes de discrétion magnétique, notamment pour la lutte anti-mines. Le but de cette thèse est par conséquent de déterminer les champs magnétiques émis par une machine électrique. L'étude et la connaissance de ces champs permettent alors de les compenser de manière à rendre la machine magnétiquement discrète. La solution réside dans un système de compensation externe composé de bobines alimentées judicieusement selon les champs rotorique et statorique de la machine.

We address the problem of integrating objects from a source taxonomy into a master taxonomy. This problem is not only pervasive on the nowadays web, but also important to the emerging semantic web. A straightforward approach to automating this process would be to train a classifier for each category in the master taxonomy, and then classify objects from the source taxonomy into these categories. In this paper we attempt to use a powerful classification method, Support Vector Machine (SVM), to attack this problem. Our key insight is that the availability of the source taxonomy data could be helpful to build better classifiers in this scenario, therefore it would be beneficial to do transductive learning rather than inductive learning, i.e., learning to optimize classification performance on a particular set of test examples. Noticing that the categorization of the master and source taxonomies often have some semantic overlap, we propose a new method, Cluster Shrinkage (CS), to further enhance the classification by exploiting such implicit knowledge. Our experiments with real-world web data show substantial improvements in the performance of taxonomy integration. / Singapore-MIT Alliance (SMA)

Variations between the software environments(e.g., installed applications, versions of libraries) on different high-performance computing (HPC) systems lead to a heterogeneity problem. Therefore, we design an optimized, homogeneous virtual machine (VM) called a virtual application appliance (VAA). Scientists can package scientific applications, and all supporting software components, as VAAs and run them independently from the underlying heterogeneous HPC systems. However, securely moving data in and out of the VAA and controlling the execution of applications are not trivial for a non-computer scientist. Consequently, we develop two automated stage-in/stage-out secure data movement mechanisms. We also explore a migration mechanism to further simplify the control of the VAA execution. Empirical evaluation results show that VAAs achieve near-native performance in widely used bioinformatics applications that we tested. Data movement, VM boot up, shutdown and migration overheads of VAAs are negligible with respect to total run-times.