Dissertations / Theses on the topic 'Conversion de modes'
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1
Girel, Etienne. "Modes de stabilisation innovants de catalyseurs pour la conversion de la biomasse." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1214.
Abstract:
La transformation de la biomasse lignocellulosique requiert des conditions opératoires différentes de celles employées dans les procédés du raffinage et de la pétrochimie. Ainsi, certaines transformations de produits bio-sourcés sont opérées en phase aqueuse et en température (« conditions hydrothermales (HT) » : T > 200°C, eau liquide). Les catalyseurs hétérogènes industriels constitués de supports poreux oxydes comme l’alumine se révèlent alors inadaptés. Des modifications structurales et texturales sont observées induisant des performances catalytiques instables et incompatibles avec une viabilité industrielle d’éventuels procédés. La thèse propose de développer des matériaux catalytiques présentant des propriétés de stabilité hydrothermale adaptées au traitement des nouvelles matières premières que sont la biomasse et ses réactifs dérivés. La stratégie consiste à modifier la surface d’alumine afin de la rendre stable en conditions HT. Cette modification de surface est effectuée avec l’aide d’additifs organiques (carbone, polyols) ou inorganiques (silicium).Il est montré que l’alumine devient stable lors de la saturation de certains hydroxyles de sa surface localisés spécifiquement sur les faces basales des cristallites élémentaires. Des stratégies sont développées pour de déposer sélectivement du carbone ou du silicium sur ces sites en question. Une très bonne stabilité HT est ainsi obtenue avec un taux de recouvrement de la surface proche de 20% seulement. Une phase métallique est ensuite déposée sur les matériaux stabilisés et leurs performances catalytiques sont évaluées pour l’hydrogénolyse du glycérolBiomass transformation reactions are carried under very different conditions from those used in petroleum industry. Some bio-products are transformed in aqueous phase underhigh temperatures (hydrothermal conditions). Heterogeneous catalysts are most likely made with a porous oxide like alumina witch is not suited for such conditions. Its textural and structural properties are modified during the treatment making the material incompatible with any process. The aim of the thesis is to develop new catalytic materials with hydrothermal stability properties adapted to the treatment of biomass products. The strategy is to modify alumina surface in order to make it insensitive to water during a hydrothermal treatment. The surface modification is done with inorganic (silicon) and organic (carbon, polyols) additives.We show here that alumina is stable only if some specific hydroxyls located in basal surfaces of crystallites are saturated. We develop strategy to selectively cover those sites with carbon or silica. A very good hydrothermal stability is obtained with a surface coverage close to 20% only. Then, a metal phase is deposited on the stabilized supports and catalytic performances of the materials are evaluated through the glycerol hydrogenolysis reaction
2
Skinner, Jacob Charles. "Energy Down-Conversion Between Classical Electromagnetic Modes via a Quantum Mechanical RF-SQUID." Thesis, University of Sussex, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487564.
Abstract:
This thesis examines the interaction between an RF SQUID ring coupled to two high Q resonant circuit measurement systems, operating at 24 MHz and 1 GHz at 4.2K. Energy is coupled to the system via a microwave source and is used to modulate the screening current of the ring and also to excite transitions between the underlying eigenenergy bands of the ring via non-adiabatic interaction. We study the current literature on such systems, used as qubits and as the building blocks for quantum computing and information processing elements. We discuss the relevance ofour system to those reviewed and suggest useful future direction for this work. We show that the point contact RF-SQUID coupled to multiple resonant circuits can be used as a model for studying the interaction between flux qubits and electromagnetic modes and provides insight in designing future practical qubit systems. In this work a new method of data acquisition is introduced, providing a much improved visualisation of the phase space. A 1 GHz measurement system is used to provide evidence of energy down-conversion from the input electromagnetic mode for a range of frequencies, via the SQUID ring. Previous work has focused on high ratio down conversion of up to 18,806: 1. Our data now shows a ratio of 1.67:1 and allows our fully quantum· mechanical theoretical model to be more usefully applied to give further insight about the system. As well as the 1 GHz measurement system, we also consider measurements from 24 MHz readout for a range of point contact weak links. We conclude the experimental results by showing down conversion taking place to both tank circuits simultaneously from the input mode, operating at 3.9 GHz. Finally we present simulations using the fully quantum model ofthe system, discuss the limitations and draw useful conclusions about the quantum nature of the down-conversion mechanism.
3
Chihani, Omar. "Etude de la fiabilité de composants GaN en conversion d'énergie." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0148/document.
Abstract:
L’industrie des transports aéronautique et terrestre voit une augmentation constante de l’électrification de ses fonctions. Les actionneurs mécaniques ou hydrauliques sont au fil des évolutions technologiques remplacés par des actionneurs électriques.Les composants qui dominent le marché actuellement ne semblent plus capables de suivre la tendance. En effet, les composants de puissance à base de silicium règnent toujours sur le marché actuel, grâce à leur faible coût. Ce matériau commence par contre à atteindre ses limites théoriques en termes de performances. Dans ce contexte, différentes structures en semi-conducteurs à large bande interdite sont en train d’émerger afin de succéder au silicium.Cette étude a pour objectif d’évaluer la fiabilité des transistors de puissance à base de Nitrure de Gallium. Ces composants semblent être très prometteurs pour des applications moyennes puissances. Cependant, les mécanismes de défaillance dont peuvent souffrir ces composants ne sont pas encore suffisamment étudiés. L’étude consiste en l’application de vieillissements alliant contraintes thermiques et électriques. Ces vieillissements sont effectués à différentes conditions de tension et de température. L’objectif de cette méthode est, dans un premier temps, d’isoler l’effet de chaque facteur de stress sur l’état des composants, et dans un second temps, d’identifier les mécanismes de défaillances activés en fonction des conditions de vieillissement.Ce travail a permis d’identifier l’existence de différents mécanismes de défaillance pouvant être activés selon les conditions de vieillissement. En effet, il est apparu que la gamme de température de vieillissement utilisée influe grandement sur la prédominance des mécanismes de défaillance activés. Les résultats obtenus remettent en question les normes de qualification actuellement appliquées aux composants en Nitrure de Gallium. Ces normes devraient revoir à la hausse les températures de vieillissement utilisées afin de couvrir des gammes plus proches des températures d’utilisation pour ce type de composantsThe aeronautical and terrestrial transport industries know a steady increase in the electrification of their functions. In fact, the mechanical or hydraulic actuators are gradually replaced by electric ones.The components dominating the market today seem unable to follow the trend anymore. In fact, silicon-based power components still prevail in the current market, thanks to their low cost. However, this material begins to reach its theoretical limits in terms of performance. In this context, different wide bandgap semiconductor structures are emerging to take on from silicon.The aim of this study is to assess the reliability of power transistors based on Gallium Nitride. These components are very promising for medium power applications. However, the failure mechanisms of these components are not yet sufficiently studied. The study consists in the application of aging tests combining thermal and electrical stresses. These agings are carried out under different conditions of tension and temperature. The objective of this method is, firstly, to isolate the effect of each stressor on the state of the components, and secondly, to identify the failure mechanisms activated according to the aging conditions.This work made it possible to identify the existence of different failure mechanisms that can be activated according to the aging conditions. Indeed, it has emerged that the aging temperature range used influences the predominance of activated failure mechanisms. The results challenge the adequacy of current qualification standards for Gallium Nitride components. These standards should revise upwards the aging temperatures used to cover ranges closer to the operating temperatures of this kind of components
4
Roudet, James. "Analyse et comparaison des divers modes de conversion statique CC-CC : modes de commutation et sûreté de fonctionnement, performances CEM." Grenoble INPG, 1990. http://www.theses.fr/1990INPG0139.
Abstract:
Les travaux présentes dans ce mémoire ont trait a l'amélioration de la conversion statique continu continu vis-à-vis de deux critères différents; la surete de fonctionnement et la compatibilité electromagnetique dont l'importance va croissante de nos jours. Pour ce faire, nous menons une étude comparative concernant une structure de type onduleur de tension mettant en ouvre successivement quatre technologies de semi-conducteurs (igbt-bipolaire, gto, mosfet), et ce dans les trois modes de fonctionnement suivants: thyristor thyristor dual commutation forcée. Un nouveau mode de commande a permis d'atteindre une fiabilité fonctionnelle satisfaisante pour le mode thyristor alors qu'une analyse des cellules de commutation associée a la mesure des pertes par commutation et par conduction constituent un premier pas en direction de la quantification de la fiabilité technologique. Une chaîne de mesure de puissances électriques instantanées developpee pour ces besoins nous permet de dissocier les pertes par commutation des pertes par conduction. De plus un banc de mesures calorimétriques valide le bilan global des pertes. Ces études montrent l'existence d'une certaine adéquation entre le composant semi-conducteur et le mode de commutation. La deuxième partie de ce travail concerne les perturbations émises en mode conduit principalement en mode différentiel et en mode rayonne. Ces investigations s'appuient conjointement sur des simulations et des mesures
5
Bonnelle, Denis. "Tour solaire, tour à vaporisation d'eau, et modes de conversion d'énergie renouvelable : présentation, critiques et suggestions." Lyon 1, 2004. http://www.theses.fr/2004LYO10129.
Abstract:
Sont principalement étudiés : - une tour solaire (un large collecteur circulaire en verre + une cheminée d'1 km de haut dans laquelle l'air chaud monte et entraîne des turbines) ; - et une tour à flux descendant d'air sec refroidi par vaporisation de gouttelettes d'eau. Des publications concurrentes présentant de graves erreurs de principe affectent la crédibilité de ces deux projets, pourtant sérieux malgré leur gigantisme. D'autres modes de conversion d'énergie renouvelable sont, de même, peu étudiés en France, recherchent des processus "pauvres" (rendement, matériaux, fluides moteurs), avec une production centralisée pour bénéficier d'économies d'échelle. Dans tous les cas, l'optimisation économique ne fait pas assez varier ensemble de nombreux paramètres pour déterminer une configuration optimale. Quelques améliorations techniques de la tour solaire sont proposées, en particulier pour pouvoir agrandir le collecteur solaire et la tour, et améliorer le rendement global
6
Wang, Feng. "Modes, Excitation and Applications of Plasmonic Nano-apertures and Nano-cavities." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1348588159.
7
Farhat, Youssef. "Study of Reverberation in a Bilayer Media : Application to the Measurement of Viscosity." Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2023. http://www.theses.fr/2023ISAB0006.
Abstract:
Le contrôle par ultrasons (UT) classique est une méthode utilisée pour évaluer les paramètres des matériaux à l'aide d'une onde mécanique. La plupart de ces méthodes fournissent des informations locales sur les propriétés du milieu le long des trajets directs entre l'émetteur et le récepteur. Or, certaines de ces méthodes dépendent de la coda ou des réflexions tardives, qui fournissent des informations globales sur le support. Dans ce travail, une méthode inspirée des techniques d'acoustique des salles est proposée pour déterminer les propriétés du milieu En effet, le signal réverbéré est très sensible aux paramètres mécaniques et aux conditions aux limites. Dans la théorie acoustique des salles, qui utilise ces signaux réverbérés pour déterminer le temps de réverbération, ce qui est très utile pour améliorer la qualité sonore des salles. Cependant, cette technique ne fonctionne que pour un seul mode de propagation, puisque l'onde se propage dans l'air à l'intérieur de la pièce acoustique. Contrairement aux fluides, au moins deux modes de propagation se produisent dans un milieu solide homogène et isotrope. Cependant, en considérant qu'un milieu solide est analogue à la cavité acoustique, les parois sont équivalentes à des conditions limites. Tout d'abord, un modèle est développé pour estimer l'intensité acoustique de chaque mode de propagation dans un milieu solide en tenant compte du couplage dû à la conversion de mode. Il permet d'estimer le temps de réverbération en milieu solide. Dans un deuxième temps, un dispositif expérimental est proposé. Cinq plaques piézoélectriques (PZT), réparties de manière aléatoire sur un bloc d'aluminium, l'une agissant comme émetteur et les autres comme récepteurs pour effectuer des mesures expérimentales du temps de réverbération. Ensuite, une comparaison entre les résultats simulés et expérimentaux est effectuée, et la résolution de problèmes inverses est réalisée pour retrouver les atténuations. Un bon accord entre les valeurs d'atténuation récupérées et celles de la littérature pour les deux ondes de masse a été observé dans l'aluminium. Enfin, en utilisant l'atténuation récupérée des ondes de masse, les travaux ont été étendus aux systèmes multicouches, tels que le milieu solide est entouré de différents fluides à ses frontières Il a été démontré que le temps de réverbération est directement lié aux paramètres mécaniques du fluide environnant, tels que la densité, la célérité et leur viscositéClassical ultrasonic testing (UT) is a method used to evaluate the parameters of materials using mechanical wave. Most of these methods provide local information about the properties of the medium along the direct paths between emitter and receiver. Yet, some of these methods depend on the coda or late reflections, which provide global information about the medium. In this work, a method inspired by room acoustic techniques is proposed to determine medium properties. In fact, the reverberated signal is highly sensitive to mechanical parameters and boundary conditions. In acoustic room theory, which uses these reverberated signals, for determination of the reverberation time which is very useful to enhance the sound quality of rooms. However, this technique only works for one propagation mode, since the wave propagates through the air inside the acoustic room. In contrast to fluids, at least two propagation modes occur in a homogeneous and isotropic solid medium. However, by considering that a solid medium is analogous to the acoustic cavity, the walls are equivalent to boundary conditions. Firstly, a model is developed to estimate the acoustic intensity of each propagation mode in solid medium taking into account the coupling due to mode conversion. It allows the reverberation time to be estimated in solid medium. Secondly, an experimental setup is proposed. A five piezoelectric (PZT) patches, randomly distributed on an aluminum block, one acting as an emitter and the others as receivers to perform experimental reverberation time measurements. Then, a comparison between the simulated and experimental results is done, and inverse problem solving is performed to retrieve the attenuations. A good agreement between the retrieved and literature attenuation values of both bulk waves has been observed in aluminum. Finally, using the retrieved attenuation of bulk waves, the work has been extended to multilayer system, such as the solid medium is surrounded by different fluids at its boundaries. It has been demonstrated that the reverberation time is directly related to the mechanical parameters of the surrounded fluid, such as density, celerity, and their viscosity
8
Wilson, Daniel W. "Optical waveguiding in photorefractive crystals : photoinduced polarization conversion and electron waveguiding in semiconductor nanostructures : modes, directional coupling, and discontinuities." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/14934.
9
Obeid, Hussein. "Contribution à la commande et à l'observation adaptatives par modes glissants d'ordres supérieurs : Application aux systèmes de gestion de l'énergie." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCA023/document.
Abstract:
Cette thèse porte sur le développement de nouvelles stratégies de commande et d’observation adaptatives par Modes Glissants (MG) et par Modes Glissants d’Ordres Supérieurs (MGOS). En effet, la mise en œuvre des commandes par MG et MGOS classiques nécessite la connaissance des limites supérieures des perturbations ou de leurs dérivées, souvent inconnues. Le premier apport de cette thèse est la synthèse d’une stratégie d’adaptation permettant d'assurer la convergence de la variable de glissement vers un voisinage prédéfini de zéro sans nécessiter d'informations sur les perturbations ou leurs dérivées et sans surestimation du gain. Cette stratégie est ensuite déclinée pour concevoir : deux commandes par MG d’ordre 1 et 2, une commande par mode glissant intégral, ainsi qu’une version du différenciateur de Levant. La deuxième contribution de la thèse est la mise au point de deux commandes adaptatives par MGOS discontinues. Ces deux algorithmes assurent un mode glissant d'ordre n en s’affranchissant de la connaissance de la limite supérieure de la perturbation et de sa dérivée. Enfin, afin de montrer l’efficacité des algorithmes proposés, ils sont appliqués avec succès à travers des simulations pour la commande d’un système de conversion de l’énergie éolienne et la commande d’un moteur à induction linéaire pour la cogénérationThis thesis deals with the development of novel strategies to adapt higher order sliding mode controllers and observers. The implementation of classics first order and higher order sliding mode controllers requires the knowledge of the upper bound of the disturbance or its derivative, which are often not known. The first contribution of this thesis is the design of an adaptive strategy that can ensure the convergence of the sliding variable to a predefined neighborhood of zero without requiring any information of the disturbance or its derivative and without overestimating the adaptive gain. This adaptive strategy is then declined for the design of the first order, second order and integral sliding mode controllers, and for the Levant's differentiator. The second contribution of the thesis is the development of two adaptive strategies for discontinuous higher order sliding mode control. The proposed two algorithms can provide the achievement of n-order sliding mode despite disturbances with unknown upper bounds or with unknown upper bounds of their derivatives. Finally, in order to show the effectiveness of the proposed algorithms, they are successfully applied through simulations to control the wind energy conversion system and the linear induction motor system for cogeneration
10
Cabral, Sânzio Fernandes. "Fluxo de operações ligadas à análise de contas no TCE/PB sob a ótica dos modos de conversão do conhecimento organizacional." Universidade Federal da Paraíba, 2008. http://tede.biblioteca.ufpb.br:8080/handle/tede/3788.
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Previous issue date: 2008-03-04Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In the current context of transformation, the so called knowledge organizations seek to integrate, at least, three important components: infrastructure, people and technology. In this study, it is supposed that the process of knowledge management should consider this trilogy integrated. This research aimed to describe the main flow of operations related to the Analysis of Municipal Accounts in TCE-PB, external controlization of the state of Paraiba, from the perspective of modes of conversion of organizational knowledge. This investigation characterized itself as a basic search, with a mixed qualitative and quantitative as well as descriptive and exploratory approach, also using as technical procedures the bibliographic review, and the single case study method, limited to five Divisions of Monitoring of Municipal Management. The search tools used were the questionnaire, the focus group, quantitative statistical analysis and qualitative analysis of content, respectively. Through this case, it was found the need of technology to be properly harnessed, because it is used merely as tool for serving data without significant support for people, despite a good infrastructure. In addition to conditioning factors of the process of knowledge management, such as centralization of decisions and organizational culture in the public sector, it has shown that the knowledge creation process faces a number of baniers such as the absence of the practice of outsourcing and socialization, due to a misunderstanding of the concepts of socialization and combination. It was conclued that the flow of operations in the review of municipal accounts are handcared lack of incentive to the best practices of dissemination of tacit knowledge between servers and preservation of organizational memory, such as formation of discussion groups, expertises maps and disclosure of creative methods of network analysis.
No atual contexto de transformação, as chamadas organizações do conhecimento buscam integrar, pelo menos três componentes essenciais: infraestrutura, pessoas e tecnologia. Neste estudo, entende-se que o processo de gestão do conhecimento deve considerar essa trilogia integrada. O objetivo da pesquisa foi descrever o fluxo das operações relacionadas à Análise de Prestação de Contas no TCE-PB, órgão de controle externo do Estado da Paraíba, sob a ótica dos modos de conversão do conhecimento organizacional. Tal investigação se caracterizou como uma pesquisa básica, com abordagem mista quantitativo-qualitativa, enfoque descritivo-exploratório, usando também como procedimentos técnicos a pesquisa bibliográfica e documental e o método de estudo de caso único, limitado ao âmbito de cinco Divisões de Acompanhamento da Gestão Municipal do TCE-PB, envolvidas na análise de contas. Como instrumento de pesquisa, para a técnica de coleta e tratamento de dados, utilizaram-se o questionário, o grupo focal e a análise de conteúdo qualitativa e de procedimentos estatísticos, respectivamente. Por intermédio desse caso, foi constatada a necessidade de a tecnologia ser adequadamente aproveitada, pois é utilizada meramente como instrumento de veiculação de dados, sem expressivo suporte para as pessoas, apesar de uma boa infra-estrutura. Além de fatores condicionantes do processo de Gestão do Conhecimento, como centralização das decisões e a cultura organizacional do setor público, evidenciou-se que o processo de criação do conhecimento enfrenta uma série de lacunas, a partir da ausência da prática da externalização e da socialização, bem como da concepção equivocada entre o conceito de socialização e de combinação. Concluiu-se que o fluxo de operações da análise de prestação de contas municipais fica prejudicado pela falta de incentivo às melhores práticas de disseminação do conhecimento tácito entre servidores e à preservação da memória organizacional, tais como: formação de grupos de discussão, mapas de expertises e uso de métodos criativos de análise em rede.
11
Diblanc, Frédérique. "Conversion de fréquences optiques appliquée au blocage de modes d'un laser Nd/YAG impulsionnel et à l'analyse spectrale large bande." Limoges, 1996. http://www.theses.fr/1996LIMO0012.
Abstract:
La premiere partie des travaux presentes correspond a la realisation d'impulsions breves de fortes puissances a partir d'un laser nd/yag impulsionnel. Dans les lasers existant actuellement, ces breves impulsions sont obtenues en utilisant un absorbant saturable comme dispositif passif de blocage de modes en phase. Ce colorant presentant differents inconvenients, nous avons effectue une etude theorique et experimentale d'un autre systeme passif de blocage de modes en phase. Ce nouveau dispositif constitue un miroir non lineaire dont la reflectivite evolue avec la densite de puissance. Il est constitue d'un miroir dichroique et d'un cristal non lineaire utilise a l'aller en doubleur de frequence, et au retour en amplificateur parametrique. Il presente differents avantages tels que sa simplicite, sa durabilite et son utilisation dans un large domaine spectral. Son etude a mis en evidence l'influence de plusieurs parametres importants tels que la reflectivite lineaire du miroir dichroique ou l'orientation de la polarisation du champ incident au cristal dans le cas d'un accord de phase de type ii. En effet nous avons montre que par un choix correct de cette orientation, un coefficient de reflexion du miroir non lineaire de plus de 80% peut etre obtenu pour une reflectivite de 10% du miroir dichroique. Son application au blocage de modes en phase d'un laser nd/yag impulsionnel a permis d'obtenir des impulsions de 18ps. Cette performance est plus interessante que les resultats publies a ce jour. La seconde partie est consacree a une autre application de la conversion de frequence, a savoir l'analyse spectrale large bande. En effet la conversion realise un transfert en longueur d'onde d'un signal de spectre etendu vers un domaine spectral ou les detecteurs ont de bonnes sensibilites. Un dispositif optique permettant d'obtenir la conversion de maniere simultanee des differents composants d'une onde a spectre large est presente. Un logiciel a ete developpe afin de determiner les conditions experimentales ideales
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Zou, Xiao-Lan. "Conversion linéaire de mode et diffusion d'ondes électromagnétiques par des fluctuations magnétiques dans un plasma." Paris 11, 1988. http://www.theses.fr/1988PA112282.
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Une méthode de mesure des fluctuations magnétiques dans un plasma chaud est étudiée. Le principe est celui du changement de la polarisation d'une onde électromagnétique diffusée par les électrons, en présence de fluctuations magnétiques B₁ On étudie d'abord le cas d'une onde incidente de haute fréquence (ωi >> ωpe, ωce). On montre en particulier que l'amplitude de la diffusion en polarisation croisée par B₁ est faible vis-à-vis de la diffusion Thomson (par des fluctuations de densité n₁), dans le rapport (ωce / ωι)². Ceci impose des Conditions très sévères en pratique sur la polarisation des ondes incidente et diffusée, qui sont explicitées. On a ensuite étudié l'équivalent de cet effet en basse fréquence (ωi ≃, ωpe , ωce ), qui est la conversion linéaire des modes propres par le processus de diffusion. L'élimination des effets intrinsèques affectant la polarisation, qui deviennent gênants en basse fréquence, devient possible si on utilise une séparation physique des modes propres dans le plasma. Dans cet objectif, nous étudions le schéma suivant : la fréquence de l'onde ordinaire incidente est assez basse pour rencontrer sa couche de coupure dans le plasma (ωi = ω pe → (r)). Alors cette onde incidente est réfléchie, ainsi que les ondes diffusées par B₁ (mode extraordinaire) traversent librement cette couche. C'est un effet dit de ''Miroir Polarisant". On étudie aussi la localisation spatiale de mesure de B₁ dans la couche de coupure. Enfin, des applications au Tokamak sont examinées en donnant le niveau mesurable de B₁.
13
Bjork, David Eugène. "Logiques de conversion individuelle et logiques confessionnelles : les modes d'évangélisation mises en oeuvre par les pasteurs anglo-américains présents en France." Paris, EPHE, 2003. http://www.theses.fr/2003EPHE5035.
Abstract:
La problématique centrale de cette thèse est celle de l’expérience de la conversion en milieu protestant évangélique et de son rôle dans la construction d’une vision unique du monde. L’étude de plusieurs milieux évangéliques, issus de l’œuvre des missionnaires anglo-américains en France, permet de constater la variété et la vitalité religieuse de ce mouvement transatlantique. Elle révèle aussi les dynamismes socioreligieux par lesquels ces groupes maintiennent la plausibilité de leurs croyances et le sens individuel et collectif de leur appartenance. Autour de cette problématique centrale, nous privilégions trois orientations : la compréhension de la mentalité et de l’expérience religieuse des missionnaires évangéliques nord-américains, l’exposé de e qu’ils cherchent à accomplir pendant leur séjour en France ainsi que l’accueil qu’ont réservé les Français à leurs projets missionnaires, la mise ne lumière de la façon dont les mutations dans le vécu religieux des Français influent sur les milieux évangéliques issus de l’œuvre missionnaire des anglo-saxons. Par l’étude de ces groupes évangéliques nous voulons tester, en milieu français, l’hypothèse de Christian Smith selon laquelle la religion peut survivre et montrer une certaine vigueur au sein d’une société moderne et pluraliste. Nous en concluons que les missionnaires évangéliques anglo-saxons ont réussi à fonder en France des communautés qui tirent de leur lecture de la Bible, de leur expérience de la conversion et de leur cheminement religieux, des convictions, perspectives, valeurs et engagements distinctifs qui les démarquent de façon positive et dynamisante de leurs concitoyensThe question examined by this thesis is that of the experience of conversion in the Protestant Evangelical context and its role in the construction of a unique worldview. The study of several Evangelical groups, fruit of the work of Anglo-American missionaries in France, permits us to observe the variety and religious vitality of this transatlantic movement. It also reveals the dynamics by which these groups maintain the plausibility of their beliefs and their collective and individual sense of belonging. The experience of conversion, and of witnessing, is mot important among theses dynamics. Around this central question we privilege three orientations: the understanding of the mindset and religious experience of the North American Evangelical Missionaries, the examination of what is that these missionaries hope to accomplish and the ways in which they and their communities have been received by the French, the exposition of the influence of recent transformations in religious experience of the French on their work. By studying these Evangelical groups we wish to test, in the French context, the hypothesis of Christian Smith which suggests that a religious movement that unites both clear cultural distinction and intense social engagement will be capable of thriving in a pluralistic, modern society. We conclude that the Anglo-Saxon Evangelical missionaries have indeed been able to start communities in France which draw from their reading of the Bible, from their experience of conversion, and from their religious pilgrimage, convictions, perspectives, values and distinctive commitments which distinguish them in a positive and energizing way from their fellow citizens
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Garcia, Jennifer A. "Conversion Theory Through the Cognitive Science of Religion Lense in a Christian-Muslim Context." Scholarship @ Claremont, 2012. http://scholarship.claremont.edu/scripps_theses/128.
Abstract:
The Cognitive Science of Religion (CSR) in recent years is beginning to become more popular. This project evolves around the development of the field as well as critiques of the field. Because of the interdisciplinary nature of CSR, it lends an interesting way to understand religion as well as religious experiences. One of those religious experiences, conversion, is examined and explored through the use of conversion narratives from western women who were formally Christian but converted to Islam. Many themes arise out of this research that paves the way for trying to understand religious experiences. Overall, the project focuses on interpreting the conversion narratives to gain a better understanding of religious conversions for the sake of anthropology, philosophy, and cognitive psychology.
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Cros, Brigitte. "Évolution non linéaire des ondes de plasma excitées par conversion de mode au voisinage de la résonance de plasma : application aux expériences de modification de l'ionosphère." Paris 11, 1989. http://www.theses.fr/1989PA112373.
Abstract:
L'évolution non linéaire d'ondes de plasma excitées par conversion de mode est étudiée dans un plasma inhomogène, non collisionnel et sans champ magnétique extérieur. Des expériences dans le domaine microonde (f = 3. 5 GHz) réalisées dans un plasma créé à l'aide d'un dispositif multipolaire, permettent de montrer que l'évolution des ondes de plasma présente une transition entre un régime non-linéaire régime stochastique lorsqu'on augmente électromagnétiques incidentes ou la longueur quasi-stationnaire et un la puissance des ondes de gradient du plasma. Une résolution numérique des équations de Zakharov, qui décrivent l'évolution couplée de l'enveloppe des ondes de plasma et des perturbations de densité basse fréquence, effectuée avec des paramètres proches des paramètres expérimentaux, a permis de caractériser ces régimes. Le premier régime est dominé par la convection des ondes de plasma; le régime stochastique est caractérisé par une modification du profil de densité due à l'excitation et à la propagation d'ondes acoustiques ioniques et par une amplification des ondes de plasma qui sont piégées dans des dépressions de densité se produisant au voisinage de la densité de résonance initiale.
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Sitel, Azzedine. "Méthodes de mesure des matrices acoustiques des discontinuités à un ou deux ports en présence des modes élevés." Compiègne, 2005. http://www.theses.fr/2005COMP1603.
Abstract:
Cette étude présente la mise en oeuvre dans le cas d'un champ acoustique multimodal des méthodes expérimentales pour la caractérisation d'une discontinuité à deux ports par mesure de sa matrice de diffusion et de transmission ainsi que sa dissipation acoustique, et d'une discontinuité à un port par mesure de sa matrice de réflexion. La méthode proposée est appliquée à la mesure de la matrice de diffusion d'un tronçon droit sans discontinuités et d'un tronçon réactif. Les matrices de réflexion et de transmission sont mesurées pour un tronçon droit couplé avec une terminaison ouverte du conduit. Avec le surdimensionnement sur le nombre des charges, les coefficients expérimentaux de la matrice de diffusion mesurés pour le tronçon droit montrent un très bon accord avec la théorie, sauf, à l'approche des fréquences de coupure des modes. Pour le tronçon réactif, une très bonne concordance entre l'expérience et la théorie est notée pour les coefficients de diffusion associés aux ondes incidentes du côté de la source. En revanche, pour les bandes de fréquences où le tronçon filtre un des modes, la méthode des charges ne peut être utilisée pour mesurer les coefficients de diffusion associés aux ondes incidentes du côté de la charge. Pour caractériser complètement un tronçon non symétrique, un essai supplémentaire après son inversion est donc nécessaire. Pour les matrices de transmission et de réflexion, le surdimensionnement sur le nombre des configurations de la source apporte une grande amélioration sur les résultats. D'un autre côté, et afin d'estimer la sensibilité des différentes méthodes aux imprécisions de mesure, une méthode de simulation analytique de l'expérience est développéeThis study presents the development of experimental methods to characterise a two-port discontinuity by measurement of its scattering and transmission matrices and its power dissipation, and a one-port discontinuity by measurement of its reflection matrix in higher order modes propagation conditions. This method is applied to the measurement of a scattering matrix of a straight cylindrical duct and a reactive chamber. Reflection and transmission matrices are measured for an open end coupled with a straight duct. With the use of the overdetermination on the number of loads, a good agreement was found between analytical and experimental scattering-matrix coefficients measured for the straight duct except near of eut-off frequencies. The test with the reactive type muffler shows that the load method fails in determining the coefficients associated to the wave coming in the discontinuity from the open side because modes are filtered by the reactive chamber. To characterise completely an asymmetrical section, an additionnel test after its inversion is therefore necessary. Results of transmission and reflection matrices shows that the overdetermination procedure on the number of source configurations improves the results. Ln another side, and in order to estimite the sensitivity of various methods to measurement errors, an analytical procedure of simulation of the experience is developed
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Garayt, Jean-Philippe. "Etude de la réalisation d'un isolateur optique intégré sur verre." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSES044/document.
Abstract:
L’essor des télécommunications par fibre optique nécessite l’insertion en sortie des lasers d’un isolateur optique intégré protégeant celui-ci des réflexions qui le déstabilisent. Ce composant existe à l’heure actuelle sous forme massive, mais son intégration sur la même plaquette que le laser pose problème du fait de la difficulté à intégrer les bons matériaux magnétooptiques sur les substrats usuels de l’optique guidée. Dans cette perspective, l’intégration de nanoparticules magnétiques dans un sol-gel déposé sur les guides optiques est une voie prometteuse, développée par le laboratoire Hubert Curien. Cette thèse a eu pour but d’étudier de manière plus systématique le composant non-réciproque qui entre dans la fabrication des isolateurs à conversion de mode, à savoir le rotateur non-réciproque. Deux études poussées, l’une théorique, l’autre expérimentale, recoupées entre elles par des modèles numériques, ont été mises en oeuvre au cours des années de cette thèse. L’étude théorique a permis de tenir compte tous les paramètres ayant une influence sur l’état de polarisation de la lumière dans un guide magnétooptique, y compris les dichroïsmes souvent négligés. L’étude pratique, à partir d’échantillons sur verre réalisés en collaboration avec l’IMEP-LAHC et le laboratoire PHENIX, a abouti à une caractérisation quasi complète des effets magnétooptiques — longitudinaux et transverses — dans les guides et de l’influence des paramètres de fabrication sur ceux-ci. Au final, ces résultats nous ont donné une compréhension plus complète du fonctionnement des guides magnétooptiques, et nous ont permis de prédire les paramètres optimaux qu’il faudra mettre afin de fabriquer, dans un futur proche, l’isolateur complet sur une seule plaque de verreThe development of optical-fiber telecommunications requires the insertion of optical isolator between lasers and fibers, in order to protect them against perturbating reflexions. This component is currently inserted in a bulk form, but the goal is to integrate it on the same wafer than the laser; nevertheless, this is problematic due to the difficulty to integrate good magnetooptical materials on usual substrates as glass or silicon. One of the promising way to achieve this, developped by the Laboratoire Hubert Curien, is the embedding of magnetic nanoparticles into a sol-gel matrix deposited above the optical guides. This thesis aimed at studying more deeply the main non-reciprocal component of integrated mode conversion optical isolators: the non-reciprocal rotator. A theorical and a practical study have both been performed, with numerical simulations to confront them. The theorical study aimed at describing the evolution of propagation in magnetooptical waveguides with respect to all effects, even absorption and dichroïsm. Then a practical study was performed on glass samples engineered in collaboration with IMEP-LAHC and the PHENIX laboratory, and lead to a full measurement of longitudinal and transverse magnetooptical effects, and their evolution related to the fabrication parameters of the samples. Finally, these results gave us a comprehensive view of how magnetooptical waveguides behave, and we were able to predict the good parameters to choose in order to construct, in a close future, a glass-integrated optical isolator
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Lienhardt, Anne-Marie. "Étude de la commande et de l'observation d'une nouvelle structure de conversion d'énergie de type SMC (Convertiseur Multicellulaire Superposé)." Toulouse, INPT, 2006. http://ethesis.inp-toulouse.fr/archive/00000335/.
Abstract:
Le convertisseur multicellulaire superposé, breveté par le LEEI en 2001, connaît un intérêt croissant surtout pour les applications moyenne tension/forte puissance. La première partie de ce mémoire est consacrée à l'étude comparative des pertes, performances et coûts des topologies 2 et 3 niveaux à base d’IGBTs pour une application basse tension/forte puissance. L'enjeu consiste à légitimer l'utilisation du SMC pour ce domaine. La deuxième partie est dédiée à l'observation des tensions internes du SMC. Leur contrôle actif conditionne la survie du convertisseur et nécessite leur connaissance. Trois méthodes sont présentées : un reconstructeur de tension, une simulation en temps réel associée à une mesure de tension et un observateur à modes glissants. L'objectif est de réduire le nombre de capteurs nécessaires au contrôle, afin de diminuer les coûts industriels. Elles ont été validées par simulation pour le SMC 7 niveaux. L'observateur à modes glissants sera validé expérimentalementDedicated to medium voltage high power applications, the Stacked Multicell Converter was developed and validated within the LEEI at the beginning of years 2000. The first part of this manuscript consists in a comparative study of the losses, performances and costs of IGBT-based 2 and 3-level topologies. The main objective is to legitimate the use of the SMC structure for low voltage/high power applications. The second part is dedicated to the observation of the SMC flying capacitor voltages. An active control of those voltages has to be introduced to ensure a good balancing of the voltage constraint over the power switches. Three estimation methods are presented: a voltage reconstruction, a digital real time simulation of the converter combined with a voltage measure and a sliding mode observer. The aim is to reduce the number of sensors and thus the SMC industrial cost. They were validated by simulation for a 7-level SMC. The sliding mode observer is confirmed experimentally
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Parpiiev, Tymur. "Ultrafast magneto-acoustics in magnetostrictive materials." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1044/document.
Abstract:
Avec l’avènement du laser femtoseconde il est devenu possible de mesurer comment la démagnétisation femtoseconde peut permettre de sonder l’interaction d’échange dans les métaux ferromagnétiques. La démagnétisation induite par laser d’un matériau avec un fort couplage magnéto-élastique amène à la relaxation des contraintes mécaniques, générant ainsi des ondes acoustiques longitudinales (L) et transversales (T). Dans ce travail de thèse, la génération d’impulsions acoustiques picosecondes T par le mécanisme de démagnétostriction dans des matériaux fortement magnétostrictifs est traitée analytiquement et montrée expérimentalement dans le cas d’un alliage de Terfenol. En premier lieu, nous avons développé un modèle phénoménologique de magnétostriction directe dans un film monocristallin de Terfenol. Les expériences pompe-sonde linéaire MOKE résolues en temps montrent que la relaxation transitoire des contraintes magnéto-élastiques du film amène à l’excitation d’ondes GHz acoustiques L at T. Ces résultats sont la première observation expérimentale de l’excitation d’ondes acoustiques transversales picoseconde par mécanisme de démagnétostriction induit par laser. En second lieu, nous avons analysé le processus d’interaction d’ondes acoustiques L avec l’aimantation d’un film mince de Terfenol. L’onde acoustique picoseconde produit un changement de magnétisation du film et induit la conversion de modes acoustiques. C’est une autre voie de génération d’ondes acoustiques T que nous avons mis en évidence. La gamme de fréquence des impulsions générées est liée à l’échelle de temps de démagnétisation, qui corresponds à quelques centaines de GHz - 1 THzWith the advent of femtosecond lasers it became possible to measure how femtosecond optical demagnetization can probe the exchange interaction in ferromagnetic metals. Laser-induced demagnetization of materials with strong magneto-elastic coupling should lead to the release of its build-in strains, thus to the generation of both longitudinal (L) and shear (S) acoustic waves. In this thesis, generation of shear picosecond acoustic pulses in strongly magnetostrictive materials such as Terfenol is processed analytically and shown experimentally. In case of Terfenol with strong magneto-crystalline anisotropy, laser induced demagnetostriction is responsible for S excitation. First, the phenomenological model of direct magnetostriction in a Terfenol monocrystalline film is developed. The shear strain generation efficiency strongly depends on the orientation of the film magnetization. Time-resolved linear MOKE pump-probe experiments show that transient laser-induced release of the magnetoelastic strains lead to the excitation of GHz L and S acoustic waves. These results are the first experimental observation of picosecond shear acoustic wave excitation by laser-induced demagnetostriction mechanism. Second, the interaction of an optically generated L acoustic pulse with the magnetization of a Terfenol thin film is reported. Arrival of the picosecond strain wave alters a change of its magnetization and leads to acoustic mode conversion, which is another pathway of shear acoustic wave generation. The frequency bandwidth of the generated acoustic pulses matches the demagnetization timescale and lies in the range of several hundreds of GHz, close to 1 THz
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Alectoridis, Dímitra. "Interação entre profissionais de contabilidade gerencial e gestão de operações: uma observação baseada na construção de conhecimento." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/956.
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Previous issue date: 2015-02-04The pursuit of excellence in action and consistent results makes professionals have responsibility in managing their own knowledge and transformation in these techniques and tools capable of broadening the qualitative and quantitative gains within departments and companies. Knowledge management well applied to professional practice is a way of ensure good results, but this should be shared - as individual knowledge - and built - as possibility of collective knowledge. This study aims to evaluate the interaction between professionals of management accounting, also called controllership, and operations management professionals, by the light of Nonaka and Takeuchi's theory (1997) on knowledge creation in the company. Its objective was to provide a measure able to identify the maturity level of professionals in each area on modes of knowledge convertion proposed in this theory, including creating entrepreneurial knowledge in the general context. The results show that the professionals care about their individual knowledge and the transmission of this to their own teams, in addition to being concerned about internalize explicit knowledge for themselves. But when evaluating the results of conversion modes that require further relationship with other teams and availability to create knowledge independent of the immediate need, we have a group of professionals evaluated showing restrictions, partly due to lack of incentive from the company, for lack of intent of other professionals for that. The measurement of the knowledge creation to company receives the impact of these restrictions, and the general result this research shows that there is need for improvement in the behavior of management accounting managers and operations managers for the Knowledge Creation bring more effective results for companies.
A busca pela excelência nas ações e por resultados sólidos faz com que os profissionais tenham responsabilidade na gestão de seus próprios conhecimentos e na transformação destes em técnicas e ferramentas capazes de ampliar os ganhos qualitativos e quantitativos nos departamentos e nas empresas. A gestão do conhecimento bem aplicado às práticas dos profissionais é um meio de garantir bons resultados, mas para isso deve ser compartilhado enquanto conhecimentos individuais e construído enquanto possibilidade de conhecimentos coletivos. Este trabalho objetiva avaliar a interação entre profissionais das áreas de contabilidade gerencial, também chamada de controladoria, e de profissionais de gestão de operações, sob a luz da teoria de Nonaka e Takeuchi (1997) da Criação de Conhecimento na empresa. Seu objetivo foi gerar uma mensuração capaz de identificar o nível de maturidade dos profissionais de cada área nos modos de conversão de conhecimento proposto nesta teoria, incluindo a criação de conhecimento empresarial no contexto geral. Os resultados encontrados mostram que os profissionais se preocupam com seu conhecimento individual e a transmissão deste para suas próprias equipes, além de se preocuparem em internalizar conhecimentos explícitos para si. Porém quando são avaliados os resultados dos modos de conversão que exigem maior relacionamento com outras equipes e disponibilidade para criar conhecimento independente da necessidade imediata, temos um grupo de profissionais avaliados que mostram restrições, parte em função da falta de incentivo da empresa, parte por falta de intenção dos outros profissionais para isso. A mensuração da criação de conhecimento para empresa recebe o impacto dessas restrições, e como resultado geral a pesquisa mostra que há necessidade de melhoria no comportamento dos gestores de contabilidade gerencial e gestores de operações para que a Criação de Conhecimento traga resultados mais efetivos para as empresas.
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Sena, Edmar Avelar de. "O Islã do sudeste do Brasil: modos de adesão, identidades e dinâmicas sociais." Universidade Federal de Juiz de Fora, 2013. https://repositorio.ufjf.br/jspui/handle/ufjf/979.
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Esta tese é fruto de um trabalho de campo realizado nas comunidades muçulmanas de Belo Horizonte, Rio de Janeiro e São Bernardo do Campo que procurou analisar como os crentes destas comunidades vivenciam sua crença frente à sociedade mais ampla em que estão inseridos. A opção por pesquisar três comunidades teve aqui o objetivo de ampliar o campo de investigação no intuito de entender a dinâmica destes grupos e questões fundamentais como adesão, identidade e dinâmicas sociais. Levou-se em consideração neste trabalho as diferenças entre as comunidades e a tendência de universalização que esta religião vem tomando na sociedade brasileira. Estas comunidades eram basicamente compostas por imigrantes sírios e libaneses, portanto eram comunidades étnicas, mas em um período de pouco mais de uma década, vem se reconfigurando a partir da conversão de brasileiros que, sem ascendência muçulmana têm aderido a esta religião. Este fenômeno das conversões ao Islã é um dos traços comuns nestas comunidades, consideradas, atualmente, comunidades mistas e não mais étnicas. Esta reconfiguração trouxe para o interior destas comunidades o dilema da identidade, uma vez que a adesão feita pelos novos membros diz respeito à religião muçulmana e não à cultura árabe. O Islã no Brasil se estrutura como mais uma religião, portanto mais uma opção religiosa, e apresenta-se como uma realidade plural, fato que torna estas comunidades socialmente dinâmicas em sua relação com a sociedade local marcando sua presença no cenário religioso brasileiro atual. Ao observar o cotidiano destas comunidades evidenciou-se aspectos da vida social, tais como a relação entre imigrantes e convertidos, a construção de uma identidade, a estrutura social e política.
This thesis is the result of fieldwork done with Muslim communities in Belo Horizonte, Rio de Janeiro and São Bernardo do Campo that tried to analyze how Muslims in this community experience their believes compared to a larger society in which they live. The option of studying three communities had here the main objective to expand the field of research in order to understand the dynamics of these groups and fundamental issues as accession identity and internal tensions. It was taken into consideration in this study the differences between communities and the tendency to universalize that this religion has been taking in Brazilian society. These communities were basically composed of Syrians and Lebanese immigrants, so these were ethnic communities, but in a period of just over a decade, they were reconfiguring from conversion of Brazilians without Muslin background adhered to this religion. This phenomenon of conversions to Islam is one of the common traits in these communities, considered now mixed communities and not ethnic. This reconfiguration brought into the dilemma of these communities identity, since conversions made by the new members, concerns muslin religion and not Arabian culture. Islam in Brazil is structured like one more religion therefore one more religious option, and presents itself as plural reality, a fact that makes these communities socially dynamic in their relationship with local society its making presence in the Brazilian religious scene. By observing the daily life of these communities, it was evident the aspects of social life, such as the relationship between immigrants and converts, building an identity and social structure and politics.
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Forsyth, A. J. "Switched-mode power conversion." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233948.
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The thesis begins with a general introduction to switched-mode power conversion. The main application areas of the technique are outlined and a summary is presented of current research work. The following chapters then focus on one recent development in the field, the Cuk converter and integrated magnetics. First, the steady-state performance limitations of the Cuk converter are explored through a comparison with the basic switched-mode converter topologies. The circuit is seen to possess several attractive properties including input and output current waveforms which are continuous rather than pulsating. However, the switching losses are shown to be high. A regenerative snubber is presented which reduces the transistor turn-off loss whilst preserving the high-quality input and output current waveforms of the converter. The integrated magnetics technique is discussed in the following chapter. This is the technique whereby converter magnetic components are coupled to eliminate input and output ripple currents and therefore improve steady-state performance. The possible problems are highlighted of attempting to couple transformers and inductors on a single core and an alternative coupling technique is outlined which uses an auxiliary electric circuit. The introduction of magnetic coupling in the Cuk converter to eliminate input and output ripple currents and improve steady-state performance results in more complicated dynamic characteristics and a more complex control problem. The state-space averaging technique is used in chapter 4 with the aid of a control engineering design package, CLADP, to analyse the problem. The impact of component coupling on the converter dynamic characteristics is explained and possible control strategies are suggested and verified. Finally, the Cuk converter with component coupling is assessed as a large-signal waveshaper. Several inverter configurations are examined in which a switched-mode converter operating under closed-loop control is used as a waveshaper to synthesise high-quality sinusoidal output currents. The implementation of the schemes using a Cuk converter with component coupling is described.
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Hamitouche, Zahia. "Études expérimentales et numériques de la propagation dans des guides d'onde à section linéairement variable." Le Havre, 2008. http://www.theses.fr/2008LEHA0003.
Abstract:
Le but de ce travail est de fournir des résultas expérimentaux et numériques sur le comportement d'une onde de Lamb dans des guides d'onde élastiques en duraluminium comportant une zone de section linéairement variable, localisés entre deux secteurs d'épaisseurs constantes de 2 mm et 5 mm. Ces guides d'onde ne sont différents que par la pente de leur zone de section variable. Plusieurs phénomènes ont été observés : l'adiabaticité des modes de Lamb dans la zone de section variable, leur réflexion à leur épaisseur de coupure et leur transmission en dehors de cette zone par effet tunnel en d'autres modes de Lamb (conversion de modes). Les résultats expérimentalement et numériquement obtenus montrent l'existence d'ondes adiabatiques dans tous les guides étudiés. En particulier, l'amplitude des déplacements normaux de l'onde adiabatique S0 sur la surface plane varie en fonction de l'épaisseur de la zone de section variable et montre un nombre de résonances localisées dans cette zone. Le nombre et la position des résonances varient en fonction de la pente du guide et de la zone dispersive. Dans le cas où le mode se propage vers les épaisseurs décroissantes dans un guide d'onde de forte pente, une transmission de l'onde incidente a été observée à la sortie de la zone de section variable en d'autres modes. Lorsque les modes de Lamb d'ordres supérieurs, et donc possédant un produit fréquence-épaisseur de coupure, se propagent vers les épaisseurs décroissantes, une réflexion de ces modes à leur épaisseur de coupure est observée, et ce avant d'atteindre la fin de la zone de section variable. Une faible part de leur énergie est transmise par effet tunnel en dehors de la zone de section variable en modes de Lamb différents. L'énergie des modes transmis a été mesurée et représente 2% au maximum, selon la pente du guide, de celle du mode incident. Par ailleurs, la zone de section variable montre un phénomène de filtrage fréquentiel pour les modes de Lamb ayant des produits fréquence-épaisseur de coupure. Les résultats expérimentaux sont en bon accord avec les résultats numériques. Grâce à l'étude numérique nous avons pu établir un modèle prédictif fiable et expliquer les phénomènes physiques observésThe aim of this work is to provide the experimental and numerical results on the behaviour of a Lamb wave in duraluminium elastic waveguides. These waveguides include an area of linearly varying section, located between two areas of constant thickness of 2 mm and 5 mm. These waveguides are only differing by the slope of their varying section domain. Several phenomena were observed : the adiabaticity of the Lamb modes in the area of varying section, the reflexion of an incident Lamb mode when it reaches its thickness cut-off in the varying section area and its transmission outside this zone by tunnel effect. The experimental and numerical results obtained show the existence of adiabatic waves in all the studied guides. In particular, the amplitude of normal displacements of the adiabatic S0 mode on the plane surface varies according to the thickness and shows a number of resonances located in this zone. The number and the positions of resonances are strongly depending of the varying section slope. If the same mode is propagated towards the decreasing thicknesses in a waveguide of strong slope, a transmission of this incident wave is observed at the end of the varying section domain into other modes. When the Lamb modes having cut-off are propagated towards the decreasing thicknesses, a reflexion at their thickness cut-off is observed. Nevertheless, a small part of their energy is transmitted by tunnel effect into other Lamb modes in the thinner part of the waveguide. The energy of the transmitted modes have been measured and represents a maximum of 2% of the energy of the incident mode. In addition, the varying section area shows a phenomenon of frequency filtering for the Lamb modes having cut-off. The experimental results are in good agreement with the numerical results. The numerical study allowed the obtention of a reliable predictive model and helped to highlight the physical meaning of the observed phenomenon
24
Yin, Changjie. "Impact of diesel generator operating modes on standalone DC microgrid and control strategies implying supercapacitor." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2411/document.
Abstract:
La nature intermittente et aléatoire des sources renouvelables, telles que le photovoltaïque et l’éolien, nécessite un complément de stockage, tel une batterie et un système de secours énergétique, tel un générateur diesel, en particulier dans un système autonome. En ce qui concerne le générateur diesel, il a besoin d'un certain temps pour démarrer et il ne peut pas donner immédiatement la puissance nécessaire, en raison de son comportement dynamique. Alors, la qualité de l'énergie est abaissée pendant cette période en raison du manque de puissance. Par conséquent, pendant la période de démarrage du générateur diesel, un supercondensateur est suggéré pour équilibrer la puissance en raison de sa réponse rapide et de sa densité de puissance élevée. Une stratégie de contrôle de puissance est proposée pour réaliser la coordination entre le générateur diesel et le supercondensateur. La simulation et les résultats expérimentaux montrent que la stratégie de contrôle proposée est capable de réguler la tension du bus continu dans des limites acceptables et d’alimenter la charge pendant la sous production d'énergie renouvelable ou lors d'augmentation de la demande de la charge. De plus, le supercondensateur peut également être utilisé pour surmonter les limites de stockage électrochimique telles que son état de charge et son courant maximal. Ainsi, cette thèse propose le contrôle de puissance en temps réel pour un micro réseau continu avec un système hybride photovoltaïque-batterie-supercondensateur-diesel, visant à répondre à la demande de puissance de charge avec fiabilité et à stabiliser de la tension du bus continu. La simulation et les résultats expérimentaux montrent également que la stratégie de contrôle améliore les performances dynamiques et statiques du micro réseau continu pour différentes conditions de fonctionnement. De plus, afin de minimiser le coût énergétique du groupe diesel, le coût du carburant et la consommation de carburant sont analysés à travers plusieurs tests expérimentaux. Par conséquent, la valeur optimale de sa production d'énergie est déduite et appliquée dans une nouvelle stratégie de gestion de la puissance est proposée. Cette stratégie peut atteindre l'objectif de maximiser l'utilisation de l'énergie photovoltaïque et de prendre en compte la caractéristique de démarrage lent et le coût énergétique du générateur diesel. Les simulations et expérimentations sont réalisées en utilisant des données photovoltaïques réelles pour illustrer les performances et le comportement du système hybride. Les résultats obtenus vérifient l'efficacité de cette stratégie. De plus la comparaison avec la stratégie de gestion de la puissance précédente, dans laquelle le coût d’énergie du générateur diesel n'est pas pris en compte, démontre que la nouvelle stratégie de gestion peut réduire le coût total du système de puissance à courant continu hybrideThe intermittent and random nature of renewable sources, such as photovoltaic and wind turbine, asks for the complement of storage, such as battery and back-up energy, such as diesel generator, especially in a standalone power system. Concerning the diesel generator, it needs some time to start up and cannot immediately offer the needed power, due to its dynamic behavior. Hence, the power quality is lowered down during this period because of the shortage of power. Therefore, during the period of the diesel generator starting up, a supercapacitor is suggested to compensate the power balance because of its fast response and high power density. A power control strategy is proposed to achieve the coordination between diesel generator and supercapacitor. Both simulation and experimental results show that the proposed control strategy is able to regulate the DC bus voltage within the acceptable limits and supplying the load during the renewable power under generation or load step-increase situations. In addition, the supercapacitor can be also used to overcome the electrochemical storage limits like its state of charge and maximum current. So, this thesis proposes the real time power control for a hybrid photovoltaic-battery-supercapacitor-diesel generator DC microgrid system, aiming to meet the load power demand with reliability and stabilizing the DC bus voltage. Both simulation and experimental results show that the designed control strategy improves the DC microgrid dynamic and static performances under different operating conditions. Furthermore, in order to minimize the diesel generator energy cost, the fuel cost and fuel consumption are analysed through several experimental tests. Therefore, the optimal value of its power generation is deduced and applied in a newly proposed energy management strategy. This strategy can achieve the goal of maximizing the utilization of photovoltaic energy and taking into account the slow start-up characteristic and energy cost of diesel generator. Both simulation and experimental studies are carried out by using the real photovoltaic data to illustrate the performance and the behavior of the hybrid system. The obtained results verify the effectiveness of this strategy. Furthermore, the comparison with the previous energy management strategy, in which the diesel generator energy cost is not considered, demonstrates that the newly proposed energy management strategy can reduce the total cost of the hybrid DC power system
25
Woods, Anna Maria. "Mode conversion of plasma waves." Thesis, University of St Andrews, 1987. http://hdl.handle.net/10023/13965.
Abstract:
Linear mode conversion processes are much studied in plasma physics because they determine the efficiency of any radio frequency heating scheme. Mode coupling model equations, extracted with varying degrees of rigour from the Maxwell-linearized kinetic equations, are usually fourth or higher order O.D.E's. These are solved by complicated methods to obtain transmission, conversion, reflection and absorption coefficients. Recently, Fuchs et al and Cairns and Lashmore-Davies (C.L-D.) have postulated second order O.D.E's to describe pairwise coupling events. The second order theories have reproduced results previously obtained by much more sophisticated treatments. In this thesis, we firstly examine the hybrid resonances in a cold plasma and show that they have a mode conversion interpretation in the framework of the C.L-D. model. The Budden tunnelling coefficients are recovered for this case. Next, mode conversion between the fast and slow electromagnetic waves in the lower hybrid frequency range is considered. This phenomenon determines the accessibility of the lower hybrid resonance to the slow wave, and is also of theoretical interest because the mode coupling differs in certain aspects from cases previously investigated by C.L-D. A second order approximation to the dispersion relation is used in the mode conversion region leading to Weber's equation from which transmission coefficients are then obtained in various cases. Finally, we provide justification for the use of Weber's equation. The exact fourth order system of O.D.E's for the problem is set down, and a linear transformation, which is an extension of that given by Heading, reveals the second order nature of the coupling process. Numerical solutions of the fourth order system yield transmission coefficients in excellent agreement with the second order theory, and also demonstrate that the electric field variation across the mode conversion region is well approximated, via the above transformation, by our second order theory.
26
Rasmus, Siljedahl. "3D Conversion from CAD models to polygon models." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129881.
Abstract:
This thesis describes the design and implementation of an application that converts CAD models into polygon models. When going from CAD models to 3D polygon models a conversion of the file type has to be performed. XperDI uses these polygon models in their tool, called sales configurator, to create a photo realistic environment to be able to have a look at the end product before it is manufactured. Existing tools are difficult to use and is missing features that is important for the Sales Configurator. The purpose of this thesis is to create a proof of concept application that converts CAD models into 3D polygon models. This new lightweight application is a simpler alternative to convert CAD models into polygon models and offers features needed for the intended use of these models, that the alternative products do not offer.
27
Layden, Andrew. "Mode Conversion Processes in Magnetized Plasmas." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/10437.
Abstract:
Mode conversion processes in plasmas allow wave energy to transferred between two or more different wave modes, and are often invoked in theories of space and astrophysical phenomena. For instance, electrostatic Langmuir waves which are trapped in the solar wind plasma can be converted to electromagnetic radiation and produce radio bursts, which can propagate through the plasma and thus be observed remotely. In environments where mode conversion has been invoked there is often a significant ambient magnetic field. This modifies the dispersion relations of the wave modes and can result in additional wave modes. However, magnetization effects have been neglected in the analyses of certain mode conversion processes. This thesis presents a number of investigations into mode conversion processes as they occur in magnetized plasmas, focusing on the magnetization of the Langmuir mode.
28
O'Heron, Patrick James 1966, and Patrick James 1966 O'Heron. "A multibody model simulating tilt-wing conversion." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/291353.
Abstract:
A multibody model is presented which simulates the conversion process associated with tilt-wing aircraft. A multibody dynamics approach is used to derive the equations of motion for a tilting articulated rotor with flap-pitch-lag root geometry. An enhanced model is used for the near-wake aerodynamics and uniform dynamic-inflow is used for the far-wake aerodynamics. A thrust control system computes the required trim settings. It is found that the controller can "fly" the model to a hover condition at a desired altitude, and can be used to achieve desired thrust levels during conversion. It is noted that conventional blade twist is inadequate during conversion. It is observed that unsteady aerodynamics are important during conversion. Also nonlinear effects on the tilt-wing cause large variations in tilt-torque during conversion.
29
Harris, Carol, Michele Mascari, Kevin Rice, Jeff Smith, and John Steedman. "ASYNCHRONOUS TRANSFER MODE (ATM) CONVERSION DEVICE (ACD)." International Foundation for Telemetering, 1997. http://hdl.handle.net/10150/607525.
Abstract:
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe Asynchronous Transfer Mode (ATM) Conversion Device (ACD) System is based on state-of-the-art ATM technology. The system interfaces between high-rate ECL/RS-422 raw data bitstreams and Synchronous Optical Network (SONET) OC-3 fiber. The SONET OC-3 interface uses ATM Adaptation Layer Type Five (AAL5) format. The system exceeds its 50 Mbps raw data, single stream requirement and provides single stream raw data throughput at rates up to 75 Mbps. With ATM and SONET packaging overhead, this translates into 90 Mbps on the OC-3 fiber. In addition to high-rate throughput, the system provides multiplexing and demultiplexing of multiple stream throughput based on the ATM cell header Virtual Path and Virtual Channel Identifier (VPI/VCI) values. The system is designed with the flexibility to provide between three and six throughput channels. All of which are multiplexed/demultiplexed to and from the same OC-3 interface. Multiple stream cumulative raw data throughput rates of up to 80 Mbps, or 96 Mbps on the fiber, have successfully run.
30
Schleyer, Fiona. "Linear mode conversion and Earth's continuum radiation." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21745.
Abstract:
Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma that is relevant to a variety of solar system radio emissions. The primary focus of this thesis is on the detailed properties of LMC of radio emission from Langmuir/z-mode waves. Chapter 2 calculates energy ε and power εp conversion efficiencies as functions of the angle of incidence of the Langmuir/z-mode wave relative to the density gradient ∇N0, the electron temperature parameter β = Te/mec2, the adiabatic index γ, and the angle between ∇N0 and ambient magnetic field B0 using a simulation code for a warm, magnetized plasma. Chapter 3 extends on from this by calculating angle-averaged ε and εp in both 2D and 3D in turbulent plasmas as it considers that a radio source is not homogeneous and will contain density and/or magnetic turbulence, so that these parameters vary with time and position. The results from Chapter 2 and 3 demonstrate that ε is strongly dependent on γβ, φ and θ and maximum for perpendicular density gradients, the averaged and un-averaged conversion efficiencies are dependent on γβ according to various power laws. The special case of a perpendicular density gradient is used to predict conversion efficiencies of terrestrial nonthermal continuum radiation (TCR); a radio emission thought to be generated by Langmuir/z-mode waves propagating close to perpendicular to the plasma's ambient magnetic field B0 by either LMC or nonlinear processes. These theoretical predictions were then applied to observations in Chapter 4, which analyses observational data of TCR measured by NASA's Van Allen Probes. The observations confirm the expected inverse square fall off with distance of the radiation level and ε is found to vary between 10-7 to 10-4, consistent with previous observations. These results confirm that LMC remains a possible generation mechanism for TCR.
31
Clabby, Darragh. "Wave energy conversion at prototype and model scales." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.673795.
Abstract:
The performance of a Wave Energy Converter (WEC) may be estimated using both physical and numerical modelling techniques. Since numerical models are often informed by, and validated against data obtained from physical models, it is important to assess the accuracy with which a prototype's behaviour is predicted by its physical model. This thesis makes such an assessment for the case of a pitching flap type WEC, by comparing the performance of Aquamarine Power's Oyster1 prototype device to that of a representative physical model. This comparison was informed by considering the device in terms of three sub-systems, namely: the flap; the incident waves; and the power take-off (PTO) system. Understanding the effects of characteristics associated with each of these sub-systems on the device's behaviour was pursued using both physical and numerical modelling techniques. As well as informing the comparison between the device's performance at each scale, the conclusions drawn from this work, particularly in relation to the modelling of sea conditions and PTO systems, are relevant to WEC modelling in general. Agreement between the device's behaviour at each scale was assessed by comparing measurements of the flap's angular position and velocity, and the power captured by the PTO. The velocity measured at prototype scale was 12% greater than that measured at model scale. The disagreement between velocity measurements directly affected agreement between power capture measurements, which were also 12% greater at prototype scale compared to model scale. Damage to the PTO cylinders meant that the device's performance was sub-optimal. Extrapolation of the comparison between the device's performance at each scale suggested that the power captured was 7% greater at prototype scale relative to model scale at magnitudes of power capture more representative of optimal performance.
32
Malik, Mohammad Rafi. "Reduced-orderCombustion Models for Innovative Energy Conversion Technologies." Doctoral thesis, Universite Libre de Bruxelles, 2021. https://dipot.ulb.ac.be/dspace/bitstream/2013/318799/4/TOC.pdf.
Abstract:
The present research seeks to advance the understanding and application of Principal Component Analysis (PCA)-based combustion modelling for practical systems application. This work is a consistent extension to the standard PC-transport model, and integrates the use of Gaussian Process Regression (GPR) in order to increase the accuracy and the potential of size reduction offered by PCA. This new model, labelled PC-GPR, is successively applied and validated in a priori and a posteriori studies.In the first part of this dissertation, the PC-GPR model is validated in an a priori study based on steady and unsteady perfectly stirred reactor (PSR) calculations. The model showed its great accuracy in the predictions for methane and propane, using large kinetic mechanisms. In particular, for methane, the use of GPR allowed to model accurately the system with only 2 principal components (PCs) instead of the 34 variables in the original GRI-3.0 kinetic mechanism. For propane, the model was applied to two different mechanisms consisting of 50 species and 162 species respectively. The PC-GPR model was able to achieve a very significant reduction, and the thermo-chemical state-space was accurately predicted using only 2 PCs for both mechanisms.The second part of this work is dedicated to the application of the PC-GPR model in the framework of non-premixed turbulent combustion in a fully three-dimensional Large Eddy Simulation (LES). To this end, an a posteriori validation is performed on the Sandia flames D, E and F. The PC-GPR model showed very good accuracy in the predictions of the three flames when compared with experimental data using only 2 PCs, instead of the 35 species originally present in the GRI 3.0 mechanism. Moreover, the PC-GPR model was also able to handle the extinction and re-ignition phenomena in flames E and F, thanks to the unsteady data in the training manifold. A comparison with the FPV model showed that the combination of the unsteady data set and the best controlling variables for the system defined by PCA provide an alternative to the use of steady flamelets parameterized by user-defined variables and combined with a PDF approach.The last part of this research focuses on the application of the PC-GPR model in a more challenging case, a lifted methane/air flame. Several key features of the model are investigated: the sensitivty to the training data set, the influence of the scaling methods, the issue of data sampling and the potential of a subgrid scale (SGS) closure. In particular, it is shown that the training data set must contain the effects of diffusion in order to accurately predict the different properties of the lifted flame. Moreover, the kernel density weighting method, used to address the issue of non-homogenous data density usually found in numerical data sets, allowed to improve the predictions of the PC-GPR model. Finally, the integration of subgrid scale closure to the PC-GPR model allowed to significantly improve the simulations results using a presumed PDF closure. A qualitative comparison with the FPV model showed that the results provided by the PC-GPR model are overall very comparable to the FPV results, with a reduced numerical cost as PC-GPR requires a 4D lookup table, instead of a 5D in the case of FPV.Le double défi de l'énergie et du changement climatique mettent en avant lanécessité de développer des nouvelles technologies de combustion, étantdonné que les projections les plus réalistes montrent que la plus grandeaugmentation de l'offre d'énergie pour les décennies à venir se fera à partirde combustibles fossiles. Ceci représente donc une forte motivation pour larecherche sur l'efficacité énergétique et les technologies propres. Parmicelles-ci, la combustion sans flamme est un concept nouvellementdéveloppé qui permet d'obtenir des rendements thermiques élevés avecdes économies de carburant tout en maintenant les émissions polluantes àun niveau très bas. L'intérêt croissant pour cette technologie est égalementmotivé par sa grande flexibilité de carburant, ce qui représente uneprécieuse opportunité pour les carburants à faible valeur calorifique, lesdéchets industriels à haute valeur calorifique et les combustibles à based'hydrogène. Etant donné que cette technologie est plutôt récente, elle estde ce fait encore mal comprise. Les solutions d'une application industriellesont très difficiles à transposer à d'autres. Pour améliorer les connaissancesdans le domaine de la combustion sans flamme, il est nécessaire de menerdes études fondamentales sur ce nouveau procédé de combustion afin defavoriser son développement. En particulier, il y a deux différencesmajeures par rapport aux flammes classiques :d’une part, les niveaux deturbulence rencontrés dans la combustion sans flamme sont rehaussés, enraison des gaz de recirculation, réduisant ainsi les échelles de mélange.D'autre part, les échelles chimiques sont augmentées, en raison de ladilution des réactifs. Par conséquent, les échelles turbulentes et chimiquessont du même ordre de grandeur, ce qui conduit à un couplage très fort.Après un examen approfondi de l'état de l'art sur la modélisation de lacombustion sans flamme, le coeur du projet représentera le développementd'une nouvelle approche pour le traitement de l'interaction turbulence /chimie pour les systèmes sans flamme dans le contexte des simulationsaux grandes échelles (Large Eddy Simulations, LES). Cette approche serafondée sur la méthode PCA (Principal Component Analysis) afin d'identifierles échelles chimiques de premier plan du processus d'oxydation. Cetteprocédure permettra de ne suivre sur la grille LES qu'un nombre réduit descalaires non conservés, ceux contrôlant l'évolution du système. Destechniques de régression non-linéaires seront couplées avec PCA afind’augmenter la précision et la réductibilité du modèle. Après avoir été validégrâce à des données expérimentales de problèmes simplifiés, le modèlesera mis à l'échelle afin de gérer des applications plus grandes, pertinentespour la combustion sans flamme. Les données expérimentales etnumériques seront validées en utilisant des indicateurs de validationappropriés pour évaluer les incertitudes expérimentales et numériques.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
33
McDougall-Bagnall, A. M. Dee. "MHD mode conversion of fast and slow magnetoacoustic waves in the solar corona." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1361.
Abstract:
There are three main wave types present in the Sun’s atmosphere: Alfvén waves and fast and slow magnetoacoustic waves. Alfvén waves are purely magnetic and would not exist if it was not for the Sun’s magnetic field. The fast and slow magnetoacoustic waves are so named due to their relative phase speeds. As the magnetic field tends to zero, the slow wave goes to zero as the fast wave becomes the sound wave. When a resonance occurs energy may be transferred between the different modes, causing one to increase in amplitude whilst the other decreases. This is known as mode conversion. Mode conversion of fast and slow magnetoacoustic waves takes place when the characteristic wave speeds, the sound and Alfvén speeds, are equal. This occurs in regions where the ratio of the gas pressure to the magnetic pressure, known as the plasma β, is approximately unity. In this thesis we investigate the conversion of fast and slow magnetoacoustic waves as they propagate from low- to high-β plasma. This investigation uses a combination of analytical and numerical techniques to gain a full understanding of the process. The MacCormack finite-difference method is used to model a wave as it undergoes mode conversion. Complementing this analytical techniques are employed to find the wave behaviour at, and distant from, the mode-conversion region. These methods are described in Chapter 2. The simple, one-dimensional model of an isothermal atmosphere permeated by a uniform magnetic field is studied in Chapter 3. Gravitational acceleration is included to ensure that mode conversion takes place. Driving a slow magnetoacoustic wave on the upper boundary conversion takes place as the wave passes from low- to high-β plasma. This is expanded upon in Chapter 4 where the effects of a non-isothermal temperature profile are examined. A tanh profile is selected to mimic the steep temperature gradient found in the transition region. In Chapter 5 the complexity is increased by allowing for a two-dimensional model. For this purpose we choose a radially-expanding magnetic field which is representative of a coronal hole. In this instance the slow magnetoacoustic wave is driven upwards from the surface, again travelling from low to high β. Finally, in Chapter 6 we investigate mode conversion near a two-dimensional, magnetic null point. At the null the plasma β becomes infinitely large and a wave propagating towards the null point will experience mode conversion. The methods used allow conversion of fast and slow waves to be described in the various model atmospheres. The amount of transmission and conversion are calculated and matched across the mode-conversion layer giving a full description of the wave behaviour.
34
Naswa, Sudhir. "Representation of Biochemical Pathway Models : Issues relating conversion of model representation from SBML to a commercial tool." Thesis, University of Skövde, School of Humanities and Informatics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-28.
Abstract:
Background: Computational simulation of complex biological networks lies at the heart of systems biology since it can confirm the conclusions drawn by experimental studies of biological networks and guide researchers to produce fresh hypotheses for further experimental validation. Since this iterative process helps in development of more realistic system models a variety of computational tools have been developed. In the absence of a common format for representation of models these tools were developed in different formats. As a result these tools became unable to exchange models amongst them, leading to development of SBML, a standard exchange format for computational models of biochemical networks. Here the formats of SBML and one of the commercial tools of systems biology are being compared to study the issues which may arise during conversion between their respective formats. A tool StoP has been developed to convert the format of SBML to the format of the selected tool.
Results: The basic format of SBML representation which is in the form of listings of various elements of a biochemical reaction system differs from the representation of the selected tool which is location oriented. In spite of this difference the various components of biochemical pathways including multiple compartments, global parameters, reactants, products, modifiers, reactions, kinetic formulas and reaction parameters could be converted from the SBML representation to the representation of the selected tool. The MathML representation of the kinetic formula in an SBML model can be converted to the string format of the selected tool. Some features of the SBML are not present in the selected tool. Similarly, the ability of the selected tool to declare parameters for locations, which are global to those locations and their children, is not present in the SBML.
Conclusions: Differences in representations of pathway models may include differences in terminologies, basic architecture, differences in capabilities of software’s, and adoption of different standards for similar things. But the overall similarity of domain of pathway models enables us to interconvert these representations. The selected tool should develop support for unit definitions, events and rules. Development of facility for parameter declaration at compartment level by SBML and facility for function declaration by the selected tool is recommended.
35
Markham, Paul N. "Conversion converted : a new model of Christian conversion in light of Wesleyan theology and nonreductive physicalism." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/1289/.
Abstract:
The doctrine of conversion is central to Christian community life. There are a number of issues that influence how one conceives the phenomenon of conversion. Among these are one's view of spirituality, human nature, and basic notions of the 'self'. This thesis begins with the claim that contemporary views of Christian spirituality, particularly in the American Evangelical tradition, disproportionately emphasise the interior and individual nature of spiritual experience. This has a direct influence on doctrines of conversion in that their salient feature emerges as the redemption of an inner self or `salvation of the soul'. In order to promote a Christian community life that places discipleship at a premium, the author argues that a new model of conversion is needed within American Evangelicalism. Resources for such a model are found in the Wesleyan theological tradition as well as gathered from philosophical and scientific insights found in a nonreductive physicalist view of human nature. This thesis represents an integrated work in science and religion in that the author considers` data' from both theology and science. The author claims that Christian conversion is a process involving normal human biological capacities. It is characterised by a change in socio-moral attitude and behaviour, and is best understood as the acquisition of virtues intrinsic to Christian faith. Such acquisitions are facilitated through social interaction and participation in practices inherent to the Christian community. Furthermore, the conversion process should be viewed as the co-operant result of Divine grace and human participation.
36
Taillefer, Christopher. "Analog-to-digital conversion via time-mode signal processing." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18669.
Abstract:
Conventional voltage-mode analog-to-digital converters use voltage amplifiers, voltage comparators, and switch capacitor networks to perform their signal processing. When compared to digital circuitry, these analog circuit blocks consume significant power, occupy large silicon areas, and operate at relatively slow data processing speeds. A signal processing methodology is proposed that performs analog-to-digital conversion on voltage signals while implementing all the circuits in a digital CMOS logic style. This methodology, called time-mode signal processing, uses time-difference variables as an intermediate signal between the input voltage and digital output. The resulting silicon devices offer very compact, low power, high-speed, and robust analog-to-digital converter alternatives. There are five main analog-to-digital converter topologies: flash, successiveapproximation, pipeline, delta-sigma, and integrating converters. Each converter topology is presented in the context of the time-mode signal processing methodology. The circuits that implement each time-mode data converter are described and when appropriate system-level, transistor-level, and experimental results are revealed. Three integrated circuits (IC) were fabricated in a 0.18-µm CMOS technology to demonstrate the feasibility of the time-mode ADC methodology. The first IC implemented the time-mode comparator and a time-mode flash ADC. The timemode delta-sigma ADC design was demonstrated in the second IC. Two circuits were implemented in the third IC: a differential-input time-mode delta-sigma ADC and a cyclic (or algorithmic) ADC.Les convertisseurs conventionnels pour changer la tension analogique à une tension numérique emploient les amplificateurs de tension, les comparateurs de tension, et les résaux de condensateur sélectionable pour acquir leur traitement de signal. En comparaison le circuit des modules analogues vis-à-vis le circuit numérique nous constatons une augmentation de puissance, une superficie de silicium moins compacte, et un traitement de données beaucoup plus lent. Une méthodologie est proposée pour le traitement du signal qui établi la conversion analogue à numérique sur les signaux de tension et tout en mettant en oeuvre tous les circuits dans un format numérique de type circuit à semiconducteur oxyde-métal à symétrie complémentaire (CMOS). Cette méthodologie reconnue sur le nom de technique-temporelle donne un traitement de signal par domaine temporel en employant la variance de cadence entre les temps comme un signal intermédiare entre la tension d'entrée et la tension de sortie numérique. Les formats numériques de type circuit semiconducteur nous offrent une alternative en temps convertisseur d'analogue à numérique avec l'avantage d'une unité compact, robuste, un coût de puissance réduit, et une haute-vitesse efficace. Il existe cinq topologies principales dans les convertisseurs analogiques à numérique: flash, approximations successives, pipeline, delta-sigma, convertisseurs intégrés. Dans chacune des topologies mentionnées ci-dessus, le traitement de signal par technique-temporelle est une méthode réconnue. Les circuits employés par chaque convertisseur de donnée par technique temporelle sont décrits lorsque le niveau du système est approprié, le niveau du transitor, et les données expérimentales sont identifiés. Trois circuits intégrés (CI) ont été conçus et fabriqués, avec une technologie de 0,18-µm CMOS pour démontrer la possibilité de la méthodologie du techniquetemporelle convertisseur analogique-numéri
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Parisot, Alexandre 1979. "Mode conversion current drive experiments on Alcator C-Mod." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40505.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 189-197).
In tokamak plasmas with multiple ion species, fast magnetosonic waves (FW) in the Ion Cyclotron Range of Frequency can mode convert to shorter wavelength modes at the Ion-Ion hybrid layer, leading to localized electron heating and current drive. Due to k1l upshifts associated with the poloidal magnetic field, only small net driven currents were predicted from mode converted Ion Bernstein Waves (IBW). As studied first by Perkins, and later confirmed experimentally with Phase Contrast Imaging measurements on Alcator C-Mod, poloidal field effects can also lead to mode conversion to Ion Cyclotron Waves (MCICW), on the low field side of the mode conversion layer. In this thesis, mode conversion current drive in the ICW-dominated regime is studied numerically and through experiments on Alcator C-Mod. Solving a dispersion relation for the mode converted waves in a slab geometry relevant to tokamak equilibria and in the finite Larmor radius limit, we find that mode conversion to Ion Cyclotron Waves is ubiquitous to high temperature conventional tokamaks, as a result of the central value for the safety factor qo 1. MCICWs are identified as kinetically modified Ion Cyclotron Waves in the regime w/kllVthe < 1. Full wave simulations with the TORIC code predict net currents can be driven by MCICW as a result of up-down asymmetries in the mode conversion process. Initial estimates with the Ehst-Karney parametrization indicated up to -- 100 kA could be driven for 3 MW input power in C-Mod plasmas. More accurate calculations, consistent with the polarization of MCICWs, were carried out by importing a quasilinear diffusion operator build from the TORIC fields in the Fokker-Planck code DKE, and predicted lower current drive efficiencies by a factor of 2.
(cont.) The TFTR discharges in 1996 where net MCCD currents were inferred experimentally from loop voltage differences were simulated with TORIC, which indicates mode conversion to ICW can account for the driven currents. Similar loop voltage experiments in D(3He) plasmas were attempted on Alcator C-Mod, but did not yield conclusive current drive measurements. The lack of control over Zeff in C-Mod, which is illustrative of ICRF operation in tokamaks with metallic walls, makes reaching optimal plasma conditions for MCCD difficult, and limits the range of parameters in which MCCD can be useful as a net current drive tool in C-Mod. Solving the current diffusion equation in the cylindrical limit and with sawtooth reconnection models, the large sawtooth oscillations in C-Mod plasmas were also found to complicate current relaxation and hinder the loop voltage analysis for small central driven currents inside the q = 1 surface. In separate experiments on Alcator C-Mod, sawtooth period changes were used to infer localized MCCD near the q = 1 surface. The mode conversion layer was swept outward through the q = 1 surface in D(3He) plasmas, and the sawtooth period was found to vary from 3 to 12 ms, which is consistent wih localized current drive and TORIC predictions. A similar evolution was found in heating and co-current drive phasing, which suggests net currents are driven with a symmetric antenna spectrum, as predicted by TORIC as a result of asymmetries in the mode conversion process. Simulations of the sawtooth cycle with the Porcelli trigger model indicate that TORIC currents can account for the sawtooth period evolution in heating phasing.
(cont.) Based on simulations of the saw-tooth cycle with the Porcelli trigger model, localized electron heating, which could also explain the experimental results, was found not to be dominant compared to the current drive effect. The experimental results demonstrate that, while not optimal, MCCD can be used for sawtooth control.
by Alexandre Parisot.
Ph.D.
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Freethy, Simon. "Synthetic aperture imaging of B-X-O mode conversion." Thesis, University of York, 2012. http://etheses.whiterose.ac.uk/2352/.
Abstract:
The conversion of thermally-born electrostatic waves in tokamak plasmas has the potential to be a powerful diagnostic for tokamak edge physics. Analytic theory and full wave modelling both conclude that analysis of emission in the microwave region carries with it information on the magnetic field in spatially localised areas which depend on density and frequency. Knowing these quantities and the 3D (2D + frequency) microwave emission pattern, it is in theory possible to calculate the current density which is vital to the understanding of the plasma pedestal. Motivated by a pilot experiment carried out on the Mega Ampere Spherical Tokamak (MAST), a novel microwave imaging device has been developed to obtain the first images of mode conversion in a Tokamak and to prove the principle of the synthetic aperture imaging technique on Tokamak devices. Here the design and calibration of the Synthetic Aperture Microwave Imaging (SAMI) radiometer is described, as well as the presentation and comparison of some of the first images of mode conversion with full wave simulations.
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Johnston, David Gregory. "A global normal form for two-dimensional mode conversion." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639767.
Abstract:
Mode conversion is a phenomenon that is of interest as a method for heating in fusion reactors. A magnetosonic wave with dispersion relation DMS propagates toward the interior of the plasma, where it excites an ion-hybrid wave with dispersion relation DIH and thereby transfers energy to the plasma. We wish to study this process using ray-based methods. The 2 2 dispersion matrix D, which is, in general, a function of the phase space variables (x; y; kx; ky), must be put into normal form, in which the diagonals of D, identied as the uncoupled dispersion relations, DMS and DIH, Poisson-commute with the o-diagonals, identied as the coupling constants. Once in this form, we look at the points in the four- dimensional phase space that satisfy DMS(x; y; kx; ky) = 0 = DIH(x; y; kx; ky), which, in general, will be a two-dimensional surface we call the conversion surface. We implement our normal form algorithm on two models. First, we consider a slab model, in which D depends only on (x; kx; ky). Then we consider a two-dimensional model of the polodial cross section of a tokamak reactor with a DT plasma with a density ratio of one- to-one. Using numerical methods, we put D into normal form and identify the conversion surface. For both models, we nd that there are regions in the four-dimensional phase space where the normal form transformation is well behaved and the conversion surface is what we expect. These are where the two dispersion surfaces DMS(x; y; kx; ky) = 0 and DIH(x; y; kx; ky) = 0 intersect transversely. However, there are also regions in the phase space where the normal form transformation is not well behaved. These coincide with tangential conversions, that is, where the two dispersion surfaces intersect tangentially. In this case, we must revisit the normal form theory and adapt it to this non-generic situation. Finally, we compute the transmission and conversion coecients for such tangential conversions.
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Midha, Amit. "Conversion of 2-dimensional drawings into 3-dimensional solid model." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1183733016.
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Siddique, Zahed. "Conversion of CAD model data for virtual prototypes for disassembly." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/17877.
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Cummings, Jeremy P. "Spiritual Identity Formation: Testing a Model of Religious Conversion Processes." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1321191940.
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Holland, Troy Michael. "A Comprehensive Coal Conversion Model Extended to Oxy-Coal Conditions." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6525.
Abstract:
CFD simulations are valuable tools in evaluating and deploying oxy-fuel and other carbon capture technologies either as retrofit technologies or for new construction. However, accurate predictive simulations require physically realistic submodels with low computational requirements. In particular, comprehensive char oxidation and gasification models have been developed that describe multiple reaction and diffusion processes. This work extends a comprehensive char conversion code (the Carbon Conversion Kinetics or CCK model), which treats surface oxidation and gasification reactions as well as processes such as film diffusion, pore diffusion, ash encapsulation, and annealing. In this work, the CCK model was thoroughly investigated with a global sensitivity analysis. The sensitivity analysis highlighted several submodels in the CCK code, which were updated with more realistic physics or otherwise extended to function in oxy-coal conditions. Improved submodels include a greatly extended annealing model, the swelling model, the mode of burning parameter, and the kinetic model, as well as the addition of the Chemical Percolation Devolatilization (CPD) model. The resultant Carbon Conversion Kinetics for oxy-coal combustion (CCK/oxy) model predictions were compared to oxy-coal data, and further compared to parallel data sets obtained at near conventional conditions.
44
Youngsman, John M'Kay. "An extensional mode resonator for vibration harvesting." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Spring2009/j_youngsman_042109.pdf.
Abstract:
Thesis (Ph. D.)--Washington State University, May 2009.Title from PDF title page (viewed on Apr. 19, 2010). "College of Engineering and Architecture." Includes bibliographical references (p. 113-116).
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Dombek, Priscilla Emily 1961. "IMPROVING THE CONVERSION OF THE SULFUR DIOXIDE - LIME REACTION BY USING ADDITIVES." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291523.
46
Bogan, Christina [Verfasser]. "Stabilized High Power Lasers and Spatial Mode Conversion / Christina Bogan." München : Verlag Dr. Hut, 2013. http://d-nb.info/1033041505/34.
47
Silva, Alexandre Herculano Mendes. "Pipelined analog-to-digital conversion using current-mode reference shifting." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8265.
Abstract:
Dissertação para obtenção do grau de Mestre em
Engenharia Electrotécnica e de ComputadoresPipeline Analog-to-digital converters (ADCs) are the most popular architecture for high-speed medium-to-high resolution applications. A fundamental, but often unreferenced building block of pipeline ADCs are the reference voltage circuits. They are required to maintain a stable reference with low output impedance to drive large internal switched capacitor loads quickly. Achieving this usually leads to a scheme that consumes a large portion of the overall power and area. A review of the literature shows that the required stable reference can be achieved with either on-chip buffering or with large off-chip decoupling capacitors. On-chip buffering is ideal for system integration but requires a high speed buffer with high power dissipation. The use of a reference with off-chip decoupling results in significant power savings but increases the pads of chip, the count of external components and the overall system cost. Moreover the amount of ringing on the internal reference voltage caused by the series inductance of the package makes this solution not viable for high speed ADCs. To address this challenge, a pipeline ADC employing a multiplying digital-to-analog converter (MDAC) with current-mode reference shifting is presented. Consequently, no reference voltages and, therefore, no voltage buffers are necessary. The bias currents are generated on-chip by a reference current generator that dissipates low power. The proposed ADC is designed in a 65 nm CMOS technology and operates at sampling rates ranging from 10 to 80 MS/s. At 40 MS/s the ADC dissipates 10.8 mW from a 1.2 V power supply and achieves an SNDR of 57.2 dB and a THD of -68 dB, corresponding to an ENOB of 9.2 bit. The corresponding figure of merit is 460 fJ/step.
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Carpintero, Moreno Efrain. "Wave energy conversion based on multi-mode line absorbing systems." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/wave-energy-conversion-based-on-multimode-line-absorbing-systems(dc39c038-c89e-4243-be4c-062a6e27be5b).html.
Abstract:
Wave energy conversion remains a promising technology with substantial renewable resources to be exploited in many parts of the world. However to be commercially attractive more effective conversion is desirable. There is scope for increasing power capture by use of several bodies responding with several modes, some or all of which may undergo resonance for frequencies within a wave climate. This theme is explored here with a floating moored line absorber system where the relative motion generates power by incorporation of a damper to represent the power take off. To be most effective the bodies should be responding in anti-phase requiring spacing between adjacent bodies of half a wavelength. First a converter design including two bodies is investigated experimentally and numerically responding solely in heave. The bodies have drafts to provide resonant frequencies within a wave spectrum, the stern diameter is as large as possible within the inertia regime and the bow diameter is optimised to provide maximum power. Experiments showed this system to be limited since the desirable anti phase heave modes were contaminated with other modes for off resonance response considerably reducing power generation. To stabilise motion in the desired modes another small float was introduced as the bow float rigidly connected by a beam to the mid float with the added benefit of adding forcing due to surge and pitch to some degree (following Prof Peter Stansby’s design). The sizes of the three floats increase from bow to stern, causing the line absorber to align with the wave direction. This system was optimised through experiments varying float spacing, diameter, draft and the hinge point above the mid float about which relative angular motion occurs. These experiments were undertaken at small scale in the wide Manchester University flume at about 1/40th scale. Regular and random (JONSWAP) waves were investigated including directionality and different spectral peakedness factor. Corresponding experiments were undertaken at five time larger scale (about 1/8th) in the wave basin at the COAST laboratory of Plymouth University. These tests were for a flat-based floats; the mechanical damping coefficient for larger scale was within the range for the smaller scale tests after appropriate (Froude) scaling. Tests at Manchester showed that the more rounded base floats (the mid float being hemi spherical) provided improved power capture. Device effectiveness is defined in terms of capture width ratio; that is the average power divided by the wave power per metre divided by the wavelength, defined by the energy period in the case of irregular waves. The experiments showed that capture width ratios were greater than 25% in regular waves and greater than 20% in irregular waves across a broad range of wave periods. With rounded base floats capture width ratios over 20% were achieved for a broad range of wave frequencies up to a maximum greater than 35%. Limited experiments at larger scale showed that increasing the damping coefficient could increase power capture by about 50%. Characterisation by capture width ratio is convenient for determining annual energy yield from scatter diagrams. This was undertaken for six sites of interest for wave energy conversion. It was assumed that the greatest power to weight ratio determines the most economic device; it was found that large devices could produce very large average power, for example average power of 2 MW, but the optimum power/weight ratio occurred at smaller scale, with average power typically 0.3 MW.
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Uwaha, Makio. "Simple Models for Chirality Conversion of Crystals and Molecules by Grinding." The Physical Society of Japan, 2008. http://hdl.handle.net/2237/13865.
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Johannesson, Elin. "A model for heterogenic catalytic conversion of carbon dioxide to methanol." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-167498.
Abstract:
Since our society became industrialised, the levels of carbon dioxide in our atmosphere have been steadily rising, to the point where it in early 2020 at is 413 ppm. The high concentration is causing several troubling effects worldwide because of the increase in mean temperature that it creates, which causes longer draughts, more severe floods, and rising seawater levels to name a few. There are a few measures that can be taken to reduce carbon dioxide in the atmosphere, among which there are a number of methods that currently are being researched and/or used. The prospect of capturing carbon dioxide and using it as a carbon building block to make methanol is one solution that is particularly interesting, since it in theory could provide a fuel for combustion engines that is net neutral regarding carbon emission. Methanol can be synthesised from carbon dioxide using a heterogeneous catalyst consisting of copper, Cu, and zinc oxide, ZnO. This research is focused on one of the components of the catalyst, the metal oxide ZnO in the form of crystallites or nanoparticles (ZnO)n. Quantum chemistry is a branch of computational chemistry which is centered on solving the Schrödinger equation for molecular systems. Density functional theory, DFT, is an approach to quantum theory which in this study was used to calculate the geometry and energy of the particles. The supercomputer Tetralith in the National Supercomputer Centre, NSC, was used to carry out the calculations. The DFT calculations utilized the functional B3LYP and the basis set 6-31G (d,p). One of the largest particle sizes studied, (ZnO)20, with a structure that has a large, flat surface, was found to be the most energetically favourable. According to studies, the presence of an oxygen vacancy on the surface of ZnO reduces the amount of activation energy required for CO2 to bond to the particle, which increases the chance of forming CO and thus continuing the process of forming methanol. Two structures of (ZnO)20 were investigated in this regard, where oxygen atoms were removed at different locations, creating four versions of Zn20O19 in total. This proved yet again that the version with a large, flat surface yields the lesser amount of energy when an O atom is removed from the centre of its surface. The adsorption of CO2 to the ZnO clusters was studied by calculating the energy of adsorption, and this showed that it was the second version of (ZnO)20, without an O vacancy, that yielded the least amount of energy, thus being the most favourable species to engage in physisorption with CO2. Lastly, the activation energy was investigated, and a diagram of the reaction process of CO2 adsorbing to Zn20O19 forming (ZnO)20 and CO is presented in this paper, which shows that the required activation energy is 127 kJ/mol.