Global ETD Search

21	Contribution à l’analyse mathématique d’équations aux dérivées partielles structurées en âge et en espace modélisant une dynamique de population cellulaire / Contribution to the mathematical analysis of age and space structured partial differential equations describing a cell population dynamics model Chekroun, Abdennasser 21 March 2016 (has links) Cette thèse s'inscrit dans le cadre général de l'étude de la dynamique de populations. Elle porte sur la modélisation et l'analyse mathématique de l'hématopoïèse, le processus de production et de régulation des cellules sanguines. La population de cellules est perçue comme un milieu continu avec une structuration en âge et en espace. Nous avons commencé par analyser des modèles d'équations différentielles et aux différences à retard discret et distribué. Ces modèles à retard permettent de mettre en évidence des comportements particuliers tels que l'existence de solutions périodiques. Ensuite, nous avons pris en compte l'aspect spatial et la diffusion des cellules dans ces modèles, tout en sachant que la structuration en espace, dans le cas de l'hématopoïèse, a été très peu abordée par le passé. Un nouveau modèle a été obtenu du point de vue mathématique. Une étude d'existence d'ondes progressives est effectuée lorsque le domaine est non borné et lorsque le domaine est borné une étude de stabilité des états stationnaires ainsi que de l'existence d'une bifurcation de Hopf est réalisée / This thesis focuses on the study of population dynamics. It is devoted to the mathematical analysis and modeling of hematopoiesis, which is the process leading to the production and regulation of blood cells. The cell's population is seen as a continuous medium structured in age and space. We analyzed models of differential-difference system with discrete- and distributed -delay. These models can exhibit specific behaviors such as the existence of periodic solutions. Then we consider a space structuration and the diffusion of cells in such models, knowing that the space structure has not been widely studied in the case of hematopoiesis. A new model is obtained from the mathematical point of view. We studied the existence of traveling waves when the domain is unbounded. When the domain is bounded, the stability of stationary solutions and the existence of a Hopf bifurcation are obtained Bifurcation de Hopf Fonctionnelle de Lyapunov-Krasovskii Ondes progressives Sur- et sous-solution Dynamique cellulaire Delay differential-difference system Hopf bifurcation Lyapunov-Krasovskii functional Traveling wave Upper- and lower solution Cell dynamics 515.353
22	La contrôlabilité frontière exacte et la synchronisation frontière exacte pour un système couplé d’équations des ondes avec des contrôles frontières de Neumann et des contrôles frontières couplés de Robin / Exact boundary controllability and exact boundary synchronization for a coupled system of wave equations with Neumann and coupled Robin boundary controls Lu, Xing 01 July 2018 (has links) Dans cette thèse, nous étudions la synchronisation, qui est un phénomène bien répandu dans la nature. Elle a été observée pour la première fois par Huygens en 1665. En se basant sur les résultats de la contrôlabilité frontière exacte, pour un système couplé d’équations des ondes avec des contrôles frontières de Neumann, nous considérons la synchronisation frontière exacte (par groupes), ainsi que la détermination de l’état de synchronisation. Ensuite, nous considérons la contrôlabilité exacte et la synchronisation exacte (par groupes) pour le système couplé avec des contrôles frontières couplés de Robin. A cause du manque de régularité de la solution, nous rencontrons beaucoup plus de difﬁcultés. Aﬁn de surmonter ces difﬁcultés, on obtient un résultat sur la trace de la solution faible du problème de Robin grâce aux résultats de régularité optimale de Lasiecka-Triggiani sur le problème de Neumann. Ceci nous a permis d’établir la contrôlabilité exacte, et, par la méthode de la perturbation compacte, la non-contrôlabilité exacte du système. De plus, nous allons étudier la détermination de l’état de synchronisation, ainsi que la nécessité des conditions de compatibilité des matrices de couplage. / This thesis studies the widespread natural phenomenon of synchronization, which was first observed by Huygens en 1665. On the basis of the results on the exact boundary controllability, for a coupled system of wave equations with Neumann boundary controls, we consider its exact boundary synchronization (by groups), as well as the determination of the state of synchronization. Then, we consider the exact boundary controllability and the exact boundary synchronization (by groups) for the coupled system with coupled Robin boundary controls. Due to difficulties from the lack of regularity of the solution, we have to face a bigger challenge. In order to overcome this difficulty, we take advantage of the regularity results for the mixed problem with Neumann boundary conditions (Lasiecka and Triggiani) to discuss the exact boundary controllability, and by the method of compact perturbation, to obtain the non-exact controllability for the system. Contrôlabilité frontière exacte Synchronisation frontière exacte Contrôle frontière de Neumann Contrôle frontière couplé de Robin Exact boundary controllability Exact boundary synchronization Exact boundary synchronization by groups Coupled system of wave equations Neumann boundary control Coupled Robin boundary control 510
23	Stabilisation polynomiale et contrôlabilité exacte des équations des ondes par des contrôles indirects et dynamiques / Polynomial stability and exact controlability of wave equations with indirect and dynamical control Toufayli, Laila 18 January 2013 (has links) La thèse est portée essentiellement sur la stabilisation et la contrôlabilité de deux équations des ondes moyennant un seul contrôle agissant sur le bord du domaine. Dans le cas du contrôle dynamique, le contrôle est introduit dans le système par une équation différentielle agissant sur le bord. C'est en effet un système hybride. Le contrôle peut être aussi applique directement sur le bord d'une équation, c'est le cas du contrôle indirecte mais non borne. La nature du système ainsi coupledépend du couplage des équations, et ceci donne divers résultats par la stabilisation (exponentielle et polynomiale) et la contrôlabilité exacte (espace contrôlable). Des nouvelles inégalités d'énergie permettent de mettre en oeuvre la Méthode fréquentielle et la Méthode d'Unicité de Hilbert. / This thesis is concerned with the stabilization and the exact controllability of two wave equations by means of only one control acting on the boundary of the domain. In the case of dynamic control, the control is introduced into the system by differential equation acting on the boundary. It is indeed a hybrid system. The control can be also applied directly on the boundary of one of the equations. In this case, the control is indirect but unbounded. The behavior of the obtained system depends on theways of coupling. Various results are established for the stabilization (exponential or polynomial) and the exact controllability (controllable space of initial data). A new inequality of energy allows to apply the Frequency Method and the Hilbert Uniqueness Method. Semi groupes Équations des ondes Système d'équations couplées Contrôle dynamique frontière Contrôle direct Méthode de HUM Méthode des multiplicateurs Méthode fréquentielle Stabilité forte Stabilité uniforme Stabilité polynomiale Contrôlabilité exacte Semi-group Wave equations Coupled system Boundary dynamical control HUM method Multiplier method Frequency domain method Uniform stability Polynomial stability Exact controllability 515.3 530.14
24	Analysis of a novel thermoelectric generator in the built environment Lozano, Adolfo 05 October 2011 (has links) This study centered on a novel thermoelectric generator (TEG) integrated into the built environment. Designed by Watts Thermoelectric LLC, the TEG is essentially a novel assembly of thermoelectric modules whose required temperature differential is supplied by hot and cold streams of water flowing through the TEG. Per its recommended operating conditions, the TEG nominally generates 83 Watts of electrical power. In its default configuration in the built environment, solar-thermal energy serves as the TEG’s hot stream source and geothermal energy serves as its cold stream source. Two systems-level, thermodynamic analyses were performed, which were based on the TEG’s upcoming characterization testing, scheduled to occur later in 2011 in Detroit, Michigan. The first analysis considered the TEG coupled with a solar collector system. A numerical model of the coupled system was constructed in order to estimate the system’s annual energetic performance. It was determined numerically that over the course of a sample year, the solar collector system could deliver 39.73 megawatt-hours (MWh) of thermal energy to the TEG. The TEG converted that thermal energy into a net of 266.5 kilowatt-hours of electricity in that year. The second analysis focused on the TEG itself during operation with the purpose of providing a preliminary thermodynamic characterization of the TEG. Using experimental data, this analysis found the TEG’s operating efficiency to be 1.72%. Next, the annual emissions that would be avoided by implementing the zero-emission TEG were considered. The emission factor of Michigan’s electric grid, RFCM, was calculated to be 0.830 tons of carbon dioxide-equivalent (CO2e) per MWh, and with the TEG’s annual energy output, it was concluded that 0.221 tons CO2e would be avoided each year with the TEG. It is important to note that the TEG can be linearly scaled up by including additional modules. Thus, these benefits can be multiplied through the incorporation of more TEG units. Finally, the levelized cost of electricity (LCOE) of the TEG integrated into the built environment with the solar-thermal hot source and passive ground-based cold source was considered. The LCOE of the system was estimated to be approximately $8,404/MWh, which is substantially greater than current generation technologies. Note that this calculation was based on one particular configuration with a particular and narrow set of assumptions, and is not intended to be a general conclusion about TEG systems overall. It was concluded that while solar-thermal energy systems can sustain the TEG, they are capital-intensive and therefore not economically suitable for the TEG given the assumptions of this analysis. In the end, because of the large costs associated with the solar-thermal system, waste heat recovery is proposed as a potentially more cost-effective provider of the TEG’s hot stream source. / text Thermoelectric generator TEG Novel thermoelectric generator Thermoelectrics Thermoelectric effect Thermoelectric modules Thermoelectric device Patent application Hot stream source Cold stream source EIA EERE Systems-level analysis Energy balance Control volume analysis Thermodynamic analysis Insolation data Insolation incident on a panel Incident insolation Extraterrestrial insolation NREL Ambient temperature data NOAA Renewable energy sources Energy generation technology Electricity generation technology Thermal energy Coupled system Emissions Greenhouse gas GHG Emissions analysis Zero-emission Emissions avoided Emission factor EF Reliability First Corporation RFC Built environment Integrated into the built environment Solar-thermal energy Solar collector system Photovoltaic thermal PVT panel Thermal storage tank Geothermal energy Geothermal heat pump GHP Ground source heat pump GSHP Numerical analysis Numerical model MATLAB Finite-difference Euler explicit Electric grid Annual energetic performance Annual electricity generation Operating efficiency System efficiency Thermodynamic characterization Economic analysis Levelized cost of energy LCOE Waste heat recovery Carbon dioxide equivalent CO2e Capital costs Installed costs Operating and maintenance costs

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Stabilisation polynomiale et contrôlabilité exacte des équations des ondes par des contrôles indirects et dynamiques / Polynomial stability and exact controlability of wave equations with indirect and dynamical control

Analysis of a novel thermoelectric generator in the built environment