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Dissertations / Theses on the topic 'Inverted structure'
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Alqurashi, Rania. "Interface electronic structure of inverted polymer solar cells." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19062/.
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Lindsjö, Martin. "Inverted Zintl phases and ions - A search for new electronic properties." Licentiate thesis, KTH, Chemistry, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1488.
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Sternadori, Miglena Wise Kevin Robert. "Cognitive processing of news as a function of structure a comparison between inverted pyramid and chronology /." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/6643.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 25, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Kevin Wise. Vita. Includes bibliographical references.
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Liu, Xilan. "Polymer Photodetectors: Device Structure, Interlayer and Physics." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384334220.
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Cortes, Avellaneda Douglas D. "Inverted base pavement structures." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37305.
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An inverted base pavement is a new pavement structure that consists of an unbound aggregate base between a stiff cement-treated foundation layer and a thin asphalt cover. Unlike conventional pavements which rely on upper stiff layers to bear and spread traffic loads, the unbound aggregate inter-layer in an inverted base pavement plays a major role in the mechanical response of the pavement structure. Traditional empirical pavement design methods rely on rules developed through long-term experience with conventional flexible or rigid pavement structures. The boundaries imposed on the unbound aggregate base in an inverted pavement structure change radically from those in conventional pavements. Therefore, current empirically derived design methods are unsuitable for the analysis of inverted base pavements. The present work documents a comprehensive experimental study on a full-scale inverted pavement test section built near LaGrange, Georgia. A detailed description of the mechanical behavior of the test section before, during and after construction provides critically needed understanding of the internal behavior and macro-scale performance of this pavement structure. Given the critical role of the unbound aggregate base and its proximity to the surface, a new field test was developed to characterize the stress-dependent stiffness of the as-built layer. A complementary numerical study that incorporates state-of-the-art concepts in constitutive modeling of unbound aggregates is used to analyze experimental results and to develop preliminary guidelines for inverted base pavement design. Simulation results show that an inverted pavement can deliver superior rutting resistance compared to a conventional flexible pavement structure with the same fatigue life. Furthermore, results show that an inverted base pavement structure can exceed the structural capacity of conventional flexible pavement designs for three typical road types both in rutting and fatigue while saving up to 40% of the initial construction costs.
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Irakarama, Modeste. "Towards Reducing Structural Interpretation Uncertainties Using Seismic Data." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0060/document.
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Les modèles géologiques sont couramment utilisés pour estimer les ressources souterraines, pour faire des simulations numériques, et pour évaluer les risques naturels ; il est donc important que les modèles géologiques représentent la géométrie des objets géologiques de façon précise. La première étape pour construire un modèle géologique consiste souvent à interpréter des surfaces structurales, telles que les failles et horizons, à partir d'une image sismique ; les objets géologiques identifiés sont ensuite utilisés pour construire le modèle géologique par des méthodes d'interpolation. Les modèles géologiques construits de cette façon héritent donc les incertitudes d'interprétation car une image sismique peut souvent supporter plusieurs interprétations structurales. Dans ce manuscrit, j'étudie le problème de réduire les incertitudes d'interprétation à l'aide des données sismiques. Particulièrement, j'étudie le problème de déterminer, à l'aide des données sismiques, quels modèles sont plus probables que d'autres dans un ensemble des modèles géologiques cohérents. Ce problème sera connu par la suite comme "le problème d'évaluation des modèles géologiques par données sismiques". J'introduis et formalise ce problème. Je propose de le résoudre par génération des données sismiques synthétiques pour chaque interprétation structurale dans un premier temps, ensuite d'utiliser ces données synthétiques pour calculer la fonction-objectif pour chaque interprétation ; cela permet de classer les différentes interprétations structurales. La difficulté majeure d'évaluer les modèles structuraux à l'aide des données sismiques consiste à proposer des fonctions-objectifs adéquates. Je propose un ensemble de conditions qui doivent être satisfaites par la fonction-objectif pour une évaluation réussie des modèles structuraux à l'aide des données sismiques. Ces conditions imposées à la fonction-objectif peuvent, en principe, être satisfaites en utilisant les données sismiques de surface (« surface seismic data »). Cependant, en pratique il reste tout de même difficile de proposer et de calculer des fonctions-objectifs qui satisfassent ces conditions. Je termine le manuscrit en illustrant les difficultés rencontrées en pratique lorsque nous cherchons à évaluer les interprétations structurales à l'aide des données sismiques de surface. Je propose une fonction-objectif générale faite de deux composants principaux : (1) un opérateur de résidus qui calcule les résidus des données, et (2) un opérateur de projection qui projette les résidus de données depuis l'espace de données vers l'espace physique (le sous-sol). Cette fonction-objectif est donc localisée dans l'espace car elle génère des valeurs en fonction de l'espace. Cependant, je ne suis toujours pas en mesure de proposer une implémentation pratique de cette fonction-objectif qui satisfasse les conditions imposées pour une évaluation réussie des interprétations structurales ; cela reste un sujet de rechercheSubsurface structural models are routinely used for resource estimation, numerical simulations, and risk management; it is therefore important that subsurface models represent the geometry of geological objects accurately. The first step in building a subsurface model is usually to interpret structural features, such as faults and horizons, from a seismic image; the identified structural features are then used to build a subsurface model using interpolation methods. Subsurface models built this way therefore inherit interpretation uncertainties since a single seismic image often supports multiple structural interpretations. In this manuscript, I study the problem of reducing interpretation uncertainties using seismic data. In particular, I study the problem of using seismic data to determine which structural models are more likely than others in an ensemble of geologically plausible structural models. I refer to this problem as "appraising structural models using seismic data". I introduce and formalize the problem of appraising structural interpretations using seismic data. I propose to solve the problem by generating synthetic data for each structural interpretation and then to compute misfit values for each interpretation; this allows us to rank the different structural interpretations. The main challenge of appraising structural models using seismic data is to propose appropriate data misfit functions. I derive a set of conditions that have to be satisfied by the data misfit function for a successful appraisal of structural models. I argue that since it is not possible to satisfy these conditions using vertical seismic profile (VSP) data, it is not possible to appraise structural interpretations using VSP data in the most general case. The conditions imposed on the data misfit function can in principle be satisfied for surface seismic data. In practice, however, it remains a challenge to propose and compute data misfit functions that satisfy those conditions. I conclude the manuscript by highlighting practical issues of appraising structural interpretations using surface seismic data. I propose a general data misfit function that is made of two main components: (1) a residual operator that computes data residuals, and (2) a projection operator that projects the data residuals from the data-space into the image-domain. This misfit function is therefore localized in space, as it outputs data misfit values in the image-domain. However, I am still unable to propose a practical implementation of this misfit function that satisfies the conditions imposed for a successful appraisal of structural interpretations; this is a subject for further research
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Bittencourt, Marcelo Corrêa de. "Comparing different and inverter graph data structure." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/185987.
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Este documento apresenta uma análise de desempenho de quatro diferentes implementações de And-Inverter Graph (AIG). AIGs são estruturas de dados normalmente utilizadas em programas que são utilizados para design de circuitos digitais. Diferentes implementações da mesma estrutura de dados pode afetar o desempenho. Isto é demonstrado em trabalhos anteriores que avaliam o desempenho de diferentes pacotes BDD (Binary Decision Diagram), que é outra estrutura de dados largamente utilizada em síntese lógica. Foram implementadas quatro estruturas de dados diferentes utilizando grafos unidirecionais ou bidirecionais aos quais os nodos são referenciados utilizando ponteiros ou índices de inteiros não-negativos. Utilizando estas diferentes estruturas de dados de AIG, medimos como diferentes aspectos das implementações afetam o desempenho da execução de um algoritmo básico.This document presents a performance analysis of four different And-Inverter Graph (AIG) implementations. AIG is a data structure commonly used in programs used for digital circuits design. Different implementations of the same data structure can affect performance. This is demonstrated by previous works that evaluate performance for different Binary Decision Diagram (BDD) packages, another data structure widely used in logic synthesis. We have implemented four distinct AIG data structures using a choice of unidirectional or bidirectional graphs in which the references to nodes are made using pointers or indexed using non-negative integers. Using these different AIG data structures, we measure how different implementation aspects affect performance in running basic algorithm.
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Kefal, Adnan. "Structural health monitoring of marine structures by using inverse finite element method." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27863.
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Structural health monitoring (SHM) is a process aimed at providing accurate and real-time information concerning structural condition and performance. SHM is a very important discipline in the areas of civil, aerospace, and marine engineering because the utilization of SHM allows us to increase both human and environmental safety in conjunction with reduction in direct economic losses. A key component of the SHM process is real-time reconstruction of a structure’s three-dimensional displacement and stress fields using a network of in situ strain sensors and measured strains, which is commonly referred to as “shape and stress sensing”. The inverse finite element method (iFEM) is a revolutionary shape- and stress-sensing methodology shown to be fast, accurate, and robust for usage as a part of SHM systems. In the present thesis, the general framework of iFEM, i.e., least-squares variational principle, is adopted to develop unconventional and more effective shape- and stress-sensing techniques, with focus on general engineering structures and marine structures in particular. Firstly, the original iFEM formulation for plate and shell structures, developed on the basis of first-order shear deformation theory, is summarized. Then, this formulation is utilized to develop a new four-node quadrilateral inverse-shell element, iQS4, which further extends the practical utility of iFEM for shape sensing of large-scale structures including marine structures. Various numerical examples are presented and it is demonstrated that the iQS4 formulation is robust with respect to the membrane- and shear-locking phenomena. Moreover, the iFEM/iQS4 methodology is applied to various types of marine structures including a stiffened plate, a chemical tanker, and a container ship. To simulate experimentally measured strains and to establish reference displacements, a coupled hydrodynamic and high-fidelity finite element analyses are performed. Utilizing the simulated strain-sensor strains, iFEM analysis of each marine structure is performed. As a result, the optimum locations of the on-board strain sensors are determined for each marine structure. Furthermore, a novel isogeometric Kirchhoff–Love inverse-shell element (iKLS) for more accurate shape-sensing analysis of curved/complex shell structures is presented. The new formulation employs the iFEM as a general framework and the non-uniform rational B-splines (NURBS) as the discretization technology for both structural geometry and displacement domain. Therefore, this new formulation couples the concept of isogeometric analysis with iFEM methodology and creates an innovative “isogeometric iFEM formulation”. The superior shape-sensing capability of the isogeometric iFEM formulation (i.e., iKLS) is demonstrated for curved shell structures when using low-fidelity discretizations with few strain sensors. Finally, an improved iFEM formulation for dealing with shape and stress sensing of multilayered composite and sandwich plate/shell structures is described. The present iFEM formulation is based upon the minimization of a weighted-least-squares functional that uses the complete set of strain measures of refined zigzag theory (RZT). A new three-node inverse-shell element, i3-RZT, is developed based on the enhanced iFEM formulation. Various validation and demonstration problems are solved to examine the precision of the iFEM/i3-RZT methodology. The numerical results demonstrate the superior accuracy and robustness of the i3-RZT element for performing accurate shape and stress sensing of complex composite structures. In conclusion, all proposed iFEM frameworks are computationally efficient, accurate, and powerful, hence they can be helpful for shape sensing and SHM of general engineering structures, especially of marine structures.
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Zhu, Qing. "Semiconductor vertical quantum structures self-formed in inverted pyramids /." Lausanne : EPFL, 2008. http://library.epfl.ch/theses/?nr=4145.
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Thèse Ecole polytechnique fédérale de Lausanne EPFL, no 4145 (2008), Faculté des sciences de base SB, Programme doctoral Physique, Institut de photonique et d'électronique quantiques IPEQ (Laboratoire de physique des nanostructures LPN). Dir.: Elyahou Kapon.
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Babincová, Kristina. "Pasivace aktivní vrstvy perovskitových solárních článků s invertovanou strukturou." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444540.
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The topic of this work is the passivation of the active layer of perovskite solar cells with an inverted structure. The work is divided into theoretical and experimental part. The theoretical part describes in particular the passivation and modification of the perovskite layer as well as the characteristic properties of perovskite, including structure and stability. The experimental part deals with the preparation of photovoltaic cells with an inverted structure. For the characterization of photovoltaic cells, reference samples were prepared and their active layer was modified by plasma. The most used deposition technique for the preparation of layers was the spin coating method. From the performed experiments it can be concluded that the preparation of samples and their subsequent modification under laboratory conditions does not lead to the improvement of the final parameters of photovoltaic conversion. By transferring the sample preparation and passivation of the active layer to an inert atmosphere, it was possible to produce cells with higher efficiencies (compared to the reference sample), around 10 %. Another advantage of this plasma treatment of the active layer is that it also improves the stability of the prepared structures, which even after a few days in air show almost 80 % of the original efficiency.
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Montagud, Santiago. "Simulation temps réel en dynamique non linéaire : application à la robotique souple." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0384/document.
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L’intégration des méthodes numériques dans les procédés industriels à son origine à l’apparition des ordinateurs, et est de plus en plus intégré parallèlement au développement de la technologie. Dans le cadre des procédés industriels où interviennent des structures en mouvement, il est intéressant d’avoir de méthodes de calcul rapide pour de problèmes non linéaires, comme par exemple, la manipulation de matériaux souples par robots. La résolution de ce type de problème reste encore comme un défi pour l’ingénierie. Malgré l’existence de nombreuses méthodes pour résoudre les problèmes dynamiques, aucun n’est adaptée à la simulation en temps réel. Pour la façon de résolution, nous avons divisé le problème dynamique en deux sous-problèmes : le problème direct, qui consiste à calculer les déplacements en fonction de la force appliqué, et le problème inverse, dans lequel on calcule la force en fonction des déplacements appliquésIntegration of numeric methodes in industrial procedures starts with the development of the computers, and its being integrated as its grows the technology. In the industrial procedures where moving structrues are involved, its necessary the hability of fast computing in non lineare problems, for example, material manipulation by soft robots. The solution of this kind of problems is still a challenge for the engineering. Despite the existance of numerous methodes to solve the dynamic problem, non of them is adapted to real time simulation. By the way of facing the problem, we have divised the dynamic problem in two subproblems: the direct problem, where displacements are computed when an external force is applied, and the inverse problem, where the external force is computed from the displacements
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Thite, Anand Narasinha. "Inverse determination of structure-borne sound sources." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273993.
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Mudry, Emeric. "Resolution improvement in fluorescence and phase optical microscopy." Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2012. http://tel.archives-ouvertes.fr/tel-00822086.
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La microscopie optique est une technique essentielle pour de nombreuses disciplines des sciences expérimentales qui nécessitent des résolutions sans cesse plus petites. Dans ce travail de thèse sont présentés plusieurs travaux pour l'amélioration de la résolution en microscopie de fluorescence et en microscopie tomographique par diffraction (MTD), une récente technique de microscopie de phase. Dans un premier temps, il est montré que déposer l'échantillon sur un miroir permet d'augmenter la résolution axiale en MTD et en microscopie confocale de fluorescence. En microscopie confocale, il faut pour cela mettre en forme le faisceau incident grâce à un modulateur spatial de lumière. En MTD, il suffit d'adapter le programme de reconstruction. La deuxième partie présente des algorithmes pour reconstruire des images haute résolution à partir de mesures en éclairement structuré avec de champs d'illumination inconnus, à la fois en microscopie de fluorescence (algorithme blind-SIM) et en MTD. En microscopie de fluorescence, ces algorithmes permettent de simplifier drastiquement les montages expérimentaux produisant l'éclairement structuré et en MTD, d'obtenir des images d'échantillons à fort indice.
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Dantas, Cássio Fraga. "Accelerating sparse inverse problems using structured approximations." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S065.
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En raison de la vertigineuse croissance des données disponibles, la complexité computationnelle des algorithmes traitant les problèmes inverses parcimonieux peut vite devenir un goulot d'étranglement. Dans cette thèse, nous explorons deux stratégies pour accélérer de tels algorithmes. D'abord, nous étudions l'utilisation de dictionnaires structurés rapides à manipuler. Une famille de dictionnaires écrits comme une somme de produits Kronecker est proposée. Ensuite, nous développons des tests d'élagage sûrs, capables d'identifier et éliminer des atomes inutiles (colonnes de la matrice dictionnaire ne correspondant pas au support de la solution), malgré l'utilisation de dictionnaires approchésAs the quantity and size of available data grow, the existing algorithms for solving sparse inverse problems can become computationally intractable. In this work, we explore two main strategies for accelerating such algorithms. First, we study the use of structured dictionaries which are fast to operate with. A particular family of dictionaries, written as a sum of Kronecker products, is proposed. Then, we develop stable screening tests, which can safely identify and discard useless atoms (columns of the dictionary matrix which do not correspond to the solution support), despite manipulating approximate dictionaries
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Li, Jing. "Inverse Problems in Structural Mechanics." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30075.
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This dissertation deals with the solution of three inverse problems in structural mechanics. The first one is load updating for finite element models (FEMs). A least squares fitting is used to identify the load parameters. The basic studies are made for geometrically linear and nonlinear FEMs of beams or frames by using a four-noded curved beam element, which, for a given precision, may significantly solve the ill-posed problem by reducing the overall number of degrees of freedom (DOF) of the system, especially the number of the unknown variables to obtain an overdetermined system. For the basic studies, the unknown applied load within an element is represented by a linear combination of integrated Legendre polynomials, the coefficients of which are the parameters to be extracted using measured displacements or strains. The optimizer L-BFGS-B is used to solve the least squares problem.
The second problem is the placement optimization of a distributed sensing fiber optic sensor for a smart bed using Genetic Algorithms (GA), where the sensor performance is maximized. The sensing fiber optic cable is represented by a Non-uniform Rational B-Splines (NURBS) curve, which changes the placement of a set of infinite number of the infinitesimal sensors to the placement of a set of finite number of the control points. The sensor performance is simplified as the integration of the absolute curvature change of the fiber optic cable with respect to a perturbation due to the body movement of a patient. The smart bed is modeled as an elastic mattress core, which supports a fiber optic sensor cable. The initial and deformed geometries of the bed due to the body weight of the patient are calculated using MSC/NASTRAN for a given body pressure. The deformation of the fiber optic cable can be extracted from the deformation of the mattress. The performance of the fiber optic sensor for any given placement is further calculated for any given perturbation.
The third application is stiffened panel optimization, including the size and placement optimization for the blade stiffeners, subject to buckling and stress constraints. The present work uses NURBS for the panel and stiffener representation. The mesh for the panel is generated using DistMesh, a triangulation algorithm in MATLAB. A NASTRAN/MATLAB interface is developed to automatically transfer the data between the analysis and optimization processes respectively. The optimization consists of minimizing the weight of the stiffened panel with design variables being the thickness of the plate and height and width of the stiffener as well as the placement of the stiffeners subjected to buckling and stress constraints under in-plane normal/shear and out-plane pressure loading conditions.Ph. D.
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Petit, Christophe. "Relation entre structure et réactivité en micelles inverses d'AOT." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37617448c.
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Girault, Pascal. "Etude d'une nouvelle structure acceleratrice a ondes progressives inverses." Paris 11, 1990. http://www.theses.fr/1990PA112372.
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L'elargissement du champ d'application des accelerateurs lineaires d'electrons et le succes des compresseurs d'impulsion hf denommes sled ou lips ont renouvele l'interet des structures acceleratrices a ondes progressives. L'etude des proprietes dispersives de ces structures monoperiodiques differencie le couplage electrique du couplage magnetique. L'analyse des fonctionnements en ondes stationnaires et progressives conduit a definir l'ensemble des parametres hf et justifie le choix du couplage magnetique en ondes progressives afin d'ameliorer l'efficacite d'acceleration. Se basant sur une etude experimentale et sur des calculs effectues a l'aide de codes a deux dimensions, on a pu determiner l'influence des fentes de couplage magnetique sur les valeurs des parametres hf. La construction d'une structure a ondes inverses et les mesures hf associees ont permis de mettre au point un accelerateur. Le compresseur d'impulsion est analyse theoriquement. Les mesures du gain d'energie sans lips et les tests de puissance avec lips ont confirme l'efficacite des cavites a couplage magnetique au mode 4 pi/5 et ont permis d'etudier les limites de champ de claquage ainsi que le courant produit par l'emission de champ. La recherche du mode optimum a ensuite montre que le mode 3 pi/4 est finalement le plus interessant en ondes inverses. En resume, en comparant les structures a couplages electrique et magnetique, il apparait que l'utilisation de ces dernieres augmente significativement le gain d'energie en ondes progressives et offre, avec ou sans compresseur hf, une alternative interessante dans le domaine des injecteurs de faible ou haute energie, de futurs accelerateurs industriels, et meme de futurs collisionneurs. La premiere application de ce travail est illustree par le choix de ce nouveau type d'accelerateur pour l'injecteur 1. 5 gev du synchrotron de trieste elettra
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Petit, Christophe. "Relation entre structure et reactivite en micelles inverses d'aot." Paris 6, 1988. http://www.theses.fr/1988PA066473.
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Les micelles inverses d'aerosol ot sont des muroemulsions eau/huile dont la taille est controlee par la quantite d'eau solubilisee. La solubilisation des petites molecules ainsi que des petites proteines entrainent des perturbations dans la structure et la reactivite. Un modele de localisation des sondes en micelle est propose a partir des mesures de structure, par diffusion des rayons x, et de reactivite par radiolyse pulse. De plus, une synthese in situ des semiconducteurs en micelle inverse est exposee
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BOUMRICHE, AHMED. "Structure et dynamique de la perovskite inversee balif#3." Le Mans, 1989. http://www.theses.fr/1989LEMA1008.
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De nombreuses etudes ont ete consacrees, recemment, aux fluoperovskites amf#3 (a=k, rb, cs, nh#4; m=mg, mn, co, ni, zn, cd, ca). La plupart de ces composes cristallises ont la structure perovskite avec un motif par maille, le groupe d'espace o#1#hpm3m et les atomes dans les positions 0, 0, 0 (a); 1/2, 1/2, 1/2 (m); 1/2, 1/2, 0; 1/2, 0, 1/2; 0, 1/2, 1/2 (f). Dans le cas de balif#3, compte tenu de la petite taille des ions li#+, l'arrangement stable des ions n'est pas la perovskite ideale mais une structure perovskite inversee avec l'ion monovalent li#+ au centre de l'octaedre f#6 et l'ion divalent ba#+#+ dans le site de coordinence 12. Cette situation originale et unique dans la famille de composes amf#3 donne un interet particulier a l'etude des proprietes dynamiques de balif#3. Dans ce travail nous presentons a la fois des donnees de diffraction des rayons x qui confirment la structure ainsi que des spectres de reflexion infrarouge et des resultats de diffusion inelastiques des neutrons qui permettent de determiner les parametres d'un modele a ions rigides. Tous ces resultats indiquent que balif#3 est l'une des fluoperovskites la moins anharmonique et la plus stable
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Margerit, Pierre. "Caractérisation large bande du comportement dynamique linéaire des structures hétérogènes viscoélastiques anisotropes : application à la table d'harmonie du piano." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1151/document.
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Le présent travail, réalisé dans le cadre du projet ANR MAESSTRO, concerne le remplacement des tables d’harmonie de piano traditionnellement constituées d’épicéa par des structures composites stratifiées. Cette démarche suppose une connaissance fine des matériaux à remplacer et des matériaux de remplacement. La contribution de la thèse consiste donc en le développement d’outils de caractérisation du comportement dynamique de structures viscoélastiques anisotropes hétérogènes sur une large bande de fréquence. Dans une première partie, l’étude théorique de la propagation des ondes planes dans ces structures est étudiée. Contrairement à une approche modale classique, les conditions aux limites et chargements sont écartés du problème. Les surfaces de dispersion obtenues contiennent la signature de l’anisotropie, de l’hétérogénéité des propriétés mécaniques ou encore du comportement dissipatif de la structure. La deuxième partie est dédiée au développement d’un moyen de mesure plein-champ robotisé. Celui-ci permet la mesure du champ de vitesse tridimensionnel instantané d’une structure soumise à un chargement dynamique répétable. La définition de l’expérience est intégrée dans un environnement CAO, permettant la prise en compte des problématiques liées à l’utilisation d’un bras robot, ainsi que l’automatisation complète de la mesure. La troisième partie est consacrée à la formulation de procédures d’identification basées sur les mesures obtenues. Les paramètres d’un modèle réduit de la mesure sont identifiés par le biais d’une méthode ESPRIT originale, intégrant des développements spécifiques aux mesures plein-champ. Ces paramètres sont ensuite utilisés pour exprimer un problème aux valeurs propres inverse permettant l’identification des propriétés de la structure mesurée. La démarche est mise en œuvre dans le cadre de l’analyse modale (régime transitoire) et l’analyse en vecteurs d’onde proposée (régime permanent). Des validations expérimentales sur des poutres homogènes et plaques anisotropes sont présentées. Le manuscrit conclut par l’application des méthodes proposées à l’identification des propriétés matériau d’une table d’harmonie de piano à queue Stephen Paulello Technologies SP190//The present work, as part of the MAESSTRO ANR project, is motivated by the replacement of wood by composite material in the design of the piano soundboard. The main focus is on the characterization of the mechanical properties of both replaced and replacement materials in a wide frequency range, taking into account anisotropy, heterogeneous and viscoelastic behavior. First, the wave propagation in such structures is investigated; boundary conditions and loads are discarded to focus on the mechanisms responsible for the energy transmission in the media. The footprint of the complex behavior of the studied structures is represented and interpreted via the dispersion surfaces. Second, a robotized setup is proposed, allowing for the measurement of the full-field instantaneous 3D velocity along the surface of structures submitted to a repeated dynamic load. Third, identification methods using this experimental data are proposed. Based on the parameters of a reduced signal model of the measurement identified with an original ESPRIT method, inverse eigenvalue problems are formulated. Both transient and steady regime are investigated, respectively through modal analysis and the proposed wavevector analysis. The proposed methods are validated through applications on homogeneous beams and anisotropic plates. Finally, the overall proposed procedure is applied for the identification of the material properties of the soundboard of the Stephen Paulello technologies SP190// grand piano
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Andresen, Marte Pernille Hatlo. "Inverse scattering of two-dimensional photonic structures." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for matematiske fag, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16862.
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Goswami, Sudipta. "Inverted metamorphism in the Sikkim-Darjeeling Himalaya : structural, metamorphic and numerical studies." Thesis, University of Cambridge, 2005. https://www.repository.cam.ac.uk/handle/1810/284048.
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The structural and metamorphic evolution of the Darjeeling-Sikkim Himalaya, a “classical” region of inverted metamorphism in the Himalaya, has been investigated by field studies combined with 2-D numerical modelling of the thermal evolution. In the Himalaya, an orogen-wide zone of inverted isograds is spatially associated with the Main Central Thrust (MCT). In the Sikkim-Darjeeling region, an inverted metamorphic field gradient is indicated by garnet-grade rocks in the upper Lesser Himalaya (LH), which increase in grade to sillimanite + K-feldspar assemblages in the middle to upper structural levels of the Higher Himalayan Crystallines (HHC). Metamorphic breaks in the “Barrovian sequence” have been established between the garnet- and sillimanite-bearing rocks in the Darjeeling region and between the kyanite-staurolite schists and biotite-sillimanite schists in Sikkim. Since the accurate location of the MCT is critical to constraining the metamorphic evolution of the Higher and Lesser Himalaya, a number of criteria are used in defining the MCT zone in this region. These include lithologic contrasts, increase in non-coaxial deformation features towards the MCT zone and geomorphology. The MCT forms a zone of distributed ductile deformation that has propagated southwards with time, resulting in a 3-10 km wide zone, containing rocks from both the Higher and Lesser Himalaya. Four episodes of deformation and two metamorphic events have been identified in the HHC. Textural evidence and garnet zoning profiles indicate a single episode of prograde metamorphism, but four deformation events in the MCT zone and the LH. Garnet zoning profiles from the HHC indicate retrograde equilibrium. M1 resulted in a peak assemblage of prismatic sillimanite + K-feldspar as well as muscovite dehydration melting resulting in millimetre to centimetre scale leucosomes, while M2 is associated with rapid exhumation of the HHC during simultaneous movement along the MCT and the South Tibetan Detachment System (STDS) forming decompression textures in metabasic boudins and pelites.
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Wentzell, Jamie Calvin. "Characteristics and structure of inverse flames of natural gas." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/MQ28263.pdf.
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Artemov, Anton G. "Inverse factorization in electronic structure theory : Analysis and parallelization." Licentiate thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-381333.
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This licentiate thesis is a part of an effort to run large electronic structure calculations in modern computational environments with distributed memory. The ultimate goal is to model materials consisting of millions of atoms at the level of quantum mechanics. In particular, the thesis focuses on different aspects of a computational problem of inverse factorization of Hermitian positive definite matrices. The considered aspects are numerical properties of the algorithms and parallelization. Not only is an efficient and scalable computation of inverse factors necessary in order to be able to run large scale electronic computations based on the Hartree–Fock or Kohn–Sham approaches with the self-consistent field procedure, but it can be applied more generally for preconditioner construction. Parallelization of algorithms with unknown load and data distributions requires a paradigm shift in programming. In this thesis we also discuss a few parallel programming models with focus on task-based models, and, more specifically, the Chunks and Tasks model.eSSENCE
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Lu, Zhiqiang. "Planification hiérarchisée et optimisation des systèmes logistiques avec flux inverses." Nantes, 2003. http://www.theses.fr/2003NANT2006.
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Dans les systèmes logistiques, la prise en considération des flux inverses et des flux directs introduit un nouveau domaine : la logistique inverse (LI). Dans cette thèse, nous avons caractérisé les particularités de la logistique inverse, ses activités ainsi que la structure des tels systèmes. Selon les spécificités des différents contextes d'application, quatre familles typiques des systèmes LI ont été proposées : la Réutilisation Directe, la Refabrication, le Service de Réparation et le Recyclage. Entre les flux inverses et les flux directs, nous avons identifié trois principales catégories de corrélation (nulle, faible, forte), qui jouent un rôle très important dans la modélisation d'un modèle LI de planification. Au niveau stratégique de planification du cadre hiérarchisée, nous proposons des modèles de localisation avec capacité et sans capacité pour ces quatre familles de systèmes LI en introduisant certaines contraintes spécifiques. . .
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Bey, Temsamani Mohammed. "Structure d'hydratation et interactions ioniques dans les micelles inverses d'AOT." Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211664.
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Sadeghzadeh, Mohammad Ali. "Electrical properties of Si/Siâ†1â†-â†xGeâ†x/Si inverted modulation doped structures." Thesis, University of Warwick, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343950.
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Cao, Xinlin. "Geometric structures of eigenfunctions with applications to inverse scattering theory, and nonlocal inverse problems." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/754.
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Inverse problems are problems where causes for desired or an observed effect are to be determined. They lie at the heart of scientific inquiry and technological development, including radar/sonar, medical imaging, geophysical exploration, invisibility cloaking and remote sensing, to name just a few. In this thesis, we focus on the theoretical study and applications of some intriguing inverse problems. Precisely speaking, we are concerned with two typical kinds of problems in the field of wave scattering and nonlocal inverse problem, respectively. The first topic is on the geometric structures of eigenfunctions and their applications in wave scattering theory, in which the conductive transmission eigenfunctions and Laplacian eigenfunctions are considered. For the study on the intrinsic geometric structures of the conductive transmission eigenfunctions, we first present the vanishing properties of the eigenfunctions at corners both in R2 and R3, based on microlocal analysis with the help of a particular type of planar complex geometrical optics (CGO) solution. This significantly extends the previous study on the interior transmission eigenfunctions. Then, as a practical application of the obtained geometric results, we establish a unique recovery result for the inverse problem associated with the transverse electromagnetic scattering by a single far-field measurement in simultaneously determining a polygonal conductive obstacle and its surface conductive parameter. For the study on the geometric structures of Laplacian eigenfunctions, we separately discuss the two-dimensional case and the three-dimensional case. In R2, we introduce a new notion of generalized singular lines of Laplacian eigenfunctions, and carefully investigate these singular lines and the nodal lines. The studies reveal that the intersecting angle between two of those lines is closely related to the vanishing order of the eigenfunction at the intersecting point. We provide an accurate and comprehensive quantitative characterization of the relationship. In R3, we study the analytic behaviors of Laplacian eigenfunctions at places where nodal or generalized singular planes intersect, which is much more complicated. These theoretical findings are original and of significant interest in spectral theory. Moreover, they are applied directly to some physical problems of great importance, including the inverse obstacle scattering problem and the inverse diffraction grating problem. It is shown in a certain polygonal (polyhedral) setup that one can recover the support of the unknown scatterer as well as the surface impedance parameter by finitely many far-field patterns. Our second topic is concerning the fractional partial differential operators and some related nonlocal inverse problems. We present some prelimilary knowledge on fractional Sobolev Spaces and fractional partial differential operators first. Then we focus on the simultaneous recovery results of two interesting nonlocal inverse problems. One is simultaneously recovering potentials and the embedded obstacles for anisotropic fractional Schrödinger operators based on the strong uniqueness property and Runge approximation property. The other one is the nonlocal inverse problem associated with a fractional Helmholtz equation that arises from the study of viscoacoustics in geophysics and thermoviscous modelling of lossy media. We establish several general uniqueness results in simultaneously recovering both the medium parameter and the internal source by the corresponding exterior measurements. The main method utilized here is the low-frequency asymptotics combining with the variational argument. In sharp contrast, these unique determination results are unknown in the local case, which would be of significant importance in thermo- and photo-acoustic tomography.
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Collins, I. R. "Inverse photoemission of graphite, sodium(110), tantalum(001), and gold/chromium." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233804.
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Garcia, Martin Juan Antonio. "RNA inverse folding and synthetic design." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:106989.
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Thesis advisor: Welkin E. JohnsonThesis advisor: Peter G. Clote
Synthetic biology currently is a rapidly emerging discipline, where innovative and interdisciplinary work has led to promising results. Synthetic design of RNA requires novel methods to study and analyze known functional molecules, as well as to generate design candidates that have a high likelihood of being functional. This thesis is primarily focused on the development of novel algorithms for the design of synthetic RNAs. Previous strategies, such as RNAinverse, NUPACK-DESIGN, etc. use heuristic methods, such as adaptive walk, ensemble defect optimization (a form of simulated annealing), genetic algorithms, etc. to generate sequences that minimize specific measures (probability of the target structure, ensemble defect). In contrast, our approach is to generate a large number of sequences whose minimum free energy structure is identical to the target design structure, and subsequently filter with respect to different criteria in order to select the most promising candidates for biochemical validation. In addition, our software must be made accessible and user-friendly, thus allowing researchers from different backgrounds to use our software in their work. Therefore, the work presented in this thesis concerns three areas: Create a potent, versatile and user friendly RNA inverse folding algorithm suitable for the specific requirements of each project, implement tools to analyze the properties that differentiate known functional RNA structures, and use these methods for synthetic design of de-novo functional RNA molecules
Thesis (PhD) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Biology
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Bardez, Elisabeth. "Relation entre structure et réactivité acido-basique de l'eau incluse dans les micelles inverses." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb376026026.
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Bertoglio, Cristobal. "Problèmes Directs et Inverses en Interaction Fluide-Structure. Application à l'hémodynamique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00768188.
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Dans cette thèse nous traitons de la simulation d'interaction fluide- structure (FSI) dans les problèmes en hémodynamique, en mettant l'accent sur l'assimilation de données et sur la simulation dans les conditions physiologiques. La première partie présente et analyse un schéma de couplage semi-implicite des équations de Navier-Stokes (NSE) et d'un modèle de conditions aux limites réduit, lorsque les NSE sont résolues avec une méthode de projection. Cela permet de simuler des problèmes de mécanique de fluides et de FSI de fac ̧on plus robuste, c'est à dire en évitant les possibles instabilités associées à des cas-tests réalistes. La deuxième partie est consacrée à l'assimilation des données avec des méthodes séquentielles en FSI. Nous présentons d'abord une étude sur l'application d'un fil- tre de Kalman réduit pour l'estimation efficace des paramètres physiques d'intérêt, comme la distribution de la rigidité de la paroi de l'artère et la résistance proximale dans le fluide, à partir des mesures de deplacement à l'interface fluide-structure. Ensuite, nous analysons certains observateurs de Luenberger utilisés pour la mé- canique des solides en FSI, dans le but de construire des estimateurs d'état efficaces pour des problèmes FSI de grande taille. Dans la troisième et dernière partie, nous appliquons les méthodologies mention- nées ci-dessus aux problèmes physiques réels. Tout d'abord, la rigidité de la paroi est estimée (pour des modèles solides linéaires et non linéaires) à partir de données provenant d'un tube de silicone simulant une aorte. Pour finir, nous analysons une aorte réelle avec une coarctation réparée, nous testons les techniques d'estimation avec des données synthétiques et nous montrons quelques résultats obtenues à partir de données issues du patient.
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Bertoglio, Beltran Cristobal Andrés. "Problèmes directs et inverses en interaction fluide-structure : Application à l’hémodynamique." Paris 6, 2012. http://www.theses.fr/2012PA066632.
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Dans cette thèse nous traitons de la simulation d’interaction fluide structure (FSI) dans les problèmes en hémodynamique, en mettant l’accent sur l’assimilation de données et sur la simulation dans les conditions physiologiques. La première partie présente et analyse un schéma de couplage semi-implicite des équations de Navier-Stokes (NSE) et d’un modèle de conditions aux limites réduit, lorsque les NSE sont résolues avec une méthode de projection. Cela permet de simuler des problèmes de mécanique de fluides et de FSI de facon plus robuste, c’est à dire en évitant les possibles instabilités associées à des cas-tests réalistes. La deuxième partie est consacrée à l’assimilation des données avec des méthodes séquentielles en FSI. Nous présentons d’abord une étude sur l’application d’un filtre de Kalman réduit pour l’estimation efficace des paramètres physiques d’intérêt, comme la distribution de la rigidité de la paroi de l’artère et la résistance proximale dans le fluide, à partir des mesures de deplacement à l’interface fluide-structure. Ensuite, nous analysons certains observateurs de Luenberger utilisés pour la mécanique des solides en FSI, dans le but de construire des estimateurs d’état efficaces pour des problèmes FSI de grande taille. Dans la troisième et dernière partie, nous appliquons les méthodologies mentionnées ci-dessus aux problèmes physiques réels. Tout d’abord, la rigidité de la paroi est estimée (pour des modèles solides linéaires et non linéaires) à partir de données provenant d’un tube de silicone simulant une aorte. Pour finir, nous analysons une aorte réelle avec une coarctation réparée, nous testons les techniques d’estimation avec des données synthétiques et nous montrons quelques résultats obtenues à partir de données issues du patientIn this thesis we deal with the simulation of fluid-structure interac- tion (FSI) problems in hemodynamics, with the emphasis in data assimilation and simulation in physiological regimes. The first part presents and analyzes a semi-implicit coupling scheme between the three-dimensional Navier-Stokes equations (NSE) and lumped parameter models, when the NSE are solved in a projection framework. This allows to simulate fluid and FSI problems more robustly, i. E. , avoiding instabilities that may occur when dealing with realistic test-cases. The second part of the work is devoted to the study of sequential data assimila- tion techniques in FSI. We first present a study about the application of a reduced- order Unscented Kalman Filter for the effective estimation of relevant physical pa- rameters, like the stiffness distribution of the vessel wall and the proximal resistance in the fluid, from displacement measurements at the fluid-structure interface. Next, we analyze some Luenberger observers from solid mechanics in FSI, with the aim to construct tractable state estimators for large-scale FSI problems. In the third and final part, we apply some of the aforementioned methodologies to real physical problems. First, we perform the estimation of the wall stiffness (for linear and non-linear solid models) from data coming from MR-images of a silicone rubber aortic phantom. To finish, we deal with the forward analysis of a real aorta with repaired coarctation and we test the estimation techniques with synthetic data and show some results with real data
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LALEM, NOUREDDINE. "Etude de la structure et de la dynamique de microemulsions inverses." Université Louis Pasteur (Strasbourg) (1971-2008), 1992. http://www.theses.fr/1992STR13081.
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Nous avons etudie l'effet du cotensioactif, du tensioactif et de la concentration en glycerol dans le cur aqueux de micelles inverses sur la structure et la dynamique de microemulsions eau dans huile en utilisant les methodes de conductivite electrique et de declin de fluorescence resolue dans le temps. La taille des micelles inverses et les interactions attractives entre micelles augmentent lorsque la longueur de la molecule du cotensioactif ou du tensioactif diminue. Avec un cotensioactif court, la solubilite de l'eau est limitee par les interactions attractives entre micelles, le phenomene de percolation electrique apparait et la valeur de la constante de vitesse d'echange de matiere entre micelles k#e est egale a (1-2)10#9 m##1s##1 au seuil de percolation electrique. Avec un contensioactif long; la solubilite de l'eau est limitee par le rayon de courbure spontane du film interfacial a la surface des micelles, le phenomene de percolation electrique n'apparait pas et la valeur de k#e est inferieure a 10#9 m##1s##1. Des correlations ont ete etablies qui permettent de faire des previsions sur l'evolution et la taille des micelles et les interactions attractives entre micelles lorsque la longueur de la chaine alkyle du contensioactif ou du tensioactif varie. La taille des micelles est independante de la concentration en glycerol et les interactions attractives entre micelles augmentent avec le contenu en glycerol dans le cur des micelles
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Laligant, Yvon. "Les Wéberites inverses MFeF(HO).... évolution thermique de leur structure cristalline et de leur structure magnétique frustrée." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375989087.
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Ledi, Koffi Sénanou. "Approche inverse pour l’identification des propriétés viscoélastiques de structures sandwichs amorties." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0250/document.
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Dans ce travail de thèse, une méthode d’identification inverse des propriétés mécaniques du matériau viscoélastique (module de cisaillement et facteur de perte) fonctionnalisé dans une structure sandwich à trois couches symétriques est proposée. L’objectif de ce travail est de pouvoir identifier les propriétés mécaniques in situ. A travers un modèle éléments finis basé sur le modèle Zig-Zag de Rao, notre modèle assure la détermination des paramètres modaux de la poutre sandwich. L'approche inverse consiste en une procédure itérative qui détermine les formes de mode étant donné les paramètres matériaux puis calcule les propriétés viscoélastiques à partir des modes en utilisant un quotient de Rayleigh jusqu'à ce que la convergence sur les propriétés du matériau soit satisfaite. Les paramètres d’entrée du modèle inverse sont les fréquences de résonance et facteurs de perte de la poutre sandwich obtenues expérimentalement. En conséquence, la dépendance en fréquence des propriétés du matériau viscoélastique de la poutre sandwich est déterminée par une démarche automatisée. La méthode a été comparée avec succès aux formules de Ross-Kerwin-Ungar ; à une approche d'optimisation standard et à la littérature. A partir des résultats, nous avons pu déduire les lois de comportement du cœur viscoélastique suivant des modèles rhéologique tels que le modèle de Maxwell généralisé, d’ADF, de GHM et du Zéner fractionnaire. Ce dispositif expérimental couplé à la méthode d’indentification a permis l’investigation des paramètres modaux de la poutre à différentes températures pour étudier l’effet de la température sur les lois rhéologiques. Pour étudier la robustesse de notre méthode, nous avons procédé des essais de reproductibilité, de reproductibilité sur une population d’échantillon. L’efficacité de notre méthode étant été prouvée, une étude de sensibilité a été menée sur les caractéristiques géométriques de notre structure et les paramètres d’entrée. Les résultats obtenus montrent le fort impact de certains paramètres sur l’identificationIn this work, a inverse identification method of the mechanical properties of the viscoelastic material (shear modulus and loss factor) functionalized in a sandwich structure with three symmetrical layers is proposed. The objective of this work is to be able to identify the mechanical properties in situ. Through a finite element model based on Rao's Zig-Zag model, our model ensures the modal parameter determination of the sandwich beam. The inverse approach consists of an iterative procedure that determines the mode shapes given the material parameters and then calculates the viscoelastic properties from the modes using a Rayleigh quotient until convergence on the properties of the material is satisfied. The input parameters of the inverse model are the resonance frequencies and loss factors of the sandwich beam obtained experimentally. As a result, the frequency dependence of the viscoelastic properties of the sandwich beam is determined by an automated way. The method has been successfully compared to Ross-Kerwin-Ungar formulas; a standard optimization approach and the literature. From the results, we have been able to deduce the constitutive laws of the viscoelastic heart according to rheological models such as the generalized Maxwell model, ADF, GHM and fractional Zener. This experimental device coupled to the method of identification allowed the investigation of modal parameters of the beam at different temperatures to study the effect of the temperature on the rheological laws. To study the robustness of our method, we carried out tests repeatability, reproducibility on a sample population. Since the effectiveness of our method has been proven, a sensitivity study has been carried out on the geometrical characteristics of our structure and the input parameters. The results obtained show the strong impact of certain parameters on identification
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Schorderet, Alain. "Synthèse modale et problème inverse en dynamique des structures /." [S.l.] : [s.n.], 1997. http://library.epfl.ch/theses/?nr=1698.
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Trentin, Bernadette. "Transcriptase inverse du HTLV-I : expression, structure et rôle dans l'infectiosité/." Bordeaux 2, 1999. http://www.theses.fr/1999BOR28640.
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Bauer, Tobias. "Structural and sedimentological reconstruction of the inverted Vargfors basin : a base for 4D-modelling." Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17596.
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The Palaeoproterozoic Skellefte mining district in northern Sweden covers an area of 120 by 30 km and is one of the most important mining districts in Europe, producing mainly Zn, Cu, Pb, As and Au from volcanogenic massive sulfide (VMS) and orogenic gold deposits.Detailed mapping of structures and stratigraphy within the sedimentary Vargfors Group combined with a structural analysis revealed a syn-extensional fault pattern of NW-SE-trending normal faults and associated NE-SW-trending transfer faults, creating the segmented sedimentary Vargfors basin. It comprises distinct fault-bound compartments, which incluence the sedimentary stratigraphy in each of these compartments.Syn-rift subsidence affected the sedimentary conditions from near-shore to shallow submarine environment.Intensive fault movements associated with mafic volcanic activity along these faults resulted in the rapid uplift of the oldest phase of the Jörn intrusive complex and/or subsidence of its surrounding areas. Subsequent erosion of the intrusive rocks led to the formation of a tonalite to granodiorite bearing conglomeratic sequence, representing an alluvial fan. Further uplift to the north of the district resulted in the erosion of Arvidsjaur volcanic rocks and the formation of a braided river system. Subsidence of the intrusive complex and/or a sedimentary coverage on top of the same caused a break in sedimentation of tonalite to granodiorite clasts. Stratigraphical evolution of the sedimentary rocks and the Vargfors Group - Skellefte Group contact relationships show that rifting started in the centre and proceeded with time towards SE and NW. Subsequent basin inversion resulted in the reactivation of the existing normal faults along a carbonate-rich basal layer forming asymmetric synclines. Primary geometries of sedimentary strata within each fault-bound compartment controlled their deformation styles. Furthermore, strain was partitioned into the faults, forming high strain zones along the basin margins, where foliations parallel the main faults, and low strain domains in the core of the basin, where foliation is oblique to the main structural grain of the basin. This oblique foliation is either a result of a rotating stress field or a transpressional regime. This case study on basin inversion gives implications for accretion processes along the Svecokarelian Craton margin as well as forthe formation of VMS-deposits and their possible transposition. Basic modelling of the main geological boundaries in the central Skellefte district was performed by integrating data from regional to outcrop scale using the GoCAD (Paradigm) software platform. Available data included geographical and geological data, which were imported from ArcGIS (ESRI) as well as drill-hole data, seismic profiles, resistivity and gravimetry profiles and EM-profiles. Creation of the main geological boundaries utilized GoCAD and SPARSE (Mirageoscience) algorithms, whereas structural geological data was exclusively modelled with SPARSE. Furthermore, this study provides a base for refining the 3-dimensional model and developing a 4-dimensional model, showing the geological evolution of the Skellefte district.Godkänd; 2010; 20101029 (tobbau); LICENTIATSEMINARIUM Ämnesområde: Malmgeologi/Ore Geology Examinator: Professor Pär Weihed, Luleå tekniska universitet Diskutant: Dr Peter Sorjonen-Ward, GTK, Kuopio, Finland Tid: Torsdag den 16 december 2010 kl 10.00 Plats: F531, Luleå tekniska universitet
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Maerten, Frantz. "Geomechanics to solve geological structure issues : forward, inverse and restoration modeling." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20031.
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Différentes applications de l'élasticité linéaire en géologie structurale sont présentées dans cette thèse à travers le développement de trois types de codes numériques. Le premier utilise la modélisation directe pour étudier les déplacements et champs de contraintes autour de zones faillées complexes. On montre que l'ajout de contraintes inégalitaires, telles que la friction de Coulomb, permet d'expliquer l'angle d'initiation des dominos dans les relais extensifs. L'ajout de matériaux hétérogènes et d'optimisations, telles la parallélisation sur processeurs multi-coeurs ainsi que la réduction de complexité des modèles, permettent l'étude de modèles beaucoup plus complexes. Le second type de code numérique utilise la modélisation inverse, aussi appelée estimation de paramètres. L'inversion linéaire de déplacements sur les failles ainsi que la détermination de paléo-contraintes utilisant une approche géomécanique sont développées. Le dernier type de code numérique concerne la restoration de structures complexes plissées et faillées. Il est notamment montré qu'une telle méthode permet de vérifier l'équilibre de coupes géologiques, ainsi que de retrouver la chronologie des failles. Finalement, nous montrons que ce même code permet de lisser des horizons 3D faillés, plissés et bruités en utilisant la géomécaniqueDifferent applications of linear elasticity in structural geology are presented in this thesis through the development of three types of numerical computer codes. The first one uses forward modeling to study displacement and perturbed stress fields around complexly faulted regions. We show that incorporating inequality constraints, such as static Coulomb friction, enables one to explain the angle of initiation of jogs in extensional relays. Adding heterogeneous material properties and optimizations, such as parallelization on multicore architectures and complexity reduction, admits more complex models. The second type deals with inverse modeling, also called parameter estimation. Linear slip inversion on faults with complex geometry, as well as paleo-stress inversion using a geomechanical approach, are developed. The last type of numerical computer code is dedicated to restoration of complexly folded and faulted structures. It is shown that this technique enables one to check balanced cross-sections, and also to retrieve fault chronology. Finally, we show that this code allows one to smooth noisy 3D interpreted faulted and folded horizons using geomechanics
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Ding, Hao. "The structure of a general type of inverse problem in metrology." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/28349/.
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Inverse problems are ubiquitous in science. The theory and techniques of inverse problems play important roles in metrology owing to the close relation between inverse problems and indirect measurements. However, the essential connection between the concepts of inverse problems and measurement has not been deeply discussed before. This thesis is focused on a general type of inverse problem in metrology that arises naturally in indirect measurements, called the inverse problem of measurement (IPM). Based on the representational theory of measurement, a deterministic model of indirect measurements is developed, which shows that the IPM can be taken as an inference process of an indirect measurement and defined as the inference of the values of the measurand from the observations of some other quantity(s). The desired properties of solving the IPMs are listed and investigated in detail. The importance of estimating empirical relations is emphasised. Based on the desired properties, some structural properties of the IPMs are derived using category theory and order theory. Thereby, it is demonstrated that the structure of the IPMs can be characterised by a notion in order theory, called ‘Galois connection’. The deterministic model of indirect measurements is generalised to a probabilistic model by considering the effects of measurement uncertainty and intrinsic uncertainty. The propagation of uncertainty from the observed data to the values of measurands is investigated using a method of covariance matrices and a Bayesian method. The methods of estimating empirical relations with probability assigned using the solutions of IPM are discussed in two different approaches: the coverage interval approach and the random variable approach. For estimating empirical relations and determining the conformity of measurement results in indirect measurements, a strategy of estimating the empirical relations with high resolution is developed which significantly reduced the effect of measurement uncertainty; a method of estimating specification uncertainty is proposed for evaluating the intrinsic uncertainties of measurands; the impact of model resolution on the specifications of the indirectly measured quantities is discussed via a contradiction in the specifications of surface profiles.
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Wang, Chong Aerospace & Mechanical Engineering Australian Defence Force Academy UNSW. "Vibro-acoustic analysis of inverter driven induction motors." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace and Mechanical Engineering, 1998. http://handle.unsw.edu.au/1959.4/38706.
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With the advent of power electronics, inverter-driven induction motor are finding increased use in industries because of applications that demand variable speed operations and because of the potential savings in energy usage. However, these drives sometimes produce unacceptably high levels in vibration and acoustic noise. A literature survey has revealed that while there has been intensive research on the design of inverters to minimize acoustic noise radiation from these drives, the vibro-acoustic behaviour of an induction motor structure has received relatively little attention. The primary objective of this research project, therefore, is to develop a general strategy/algorithm for estimating the acoustic noise radiated from inverter-driven induction motors. By using a three-phase, 2.2 kW induction motor, the vibration modes due to various structural components (such as the rotor, the stator/casing, the endshields and the base plate) of the motor structure were analysed by experimental modal testing. Results indicate that the vibration modes due to the rotor are only important at low frequencies. It has been found that the power injection method gives more accurate measurement of the damping of a motor structure than the modal testing and the time decay methods. If a point force excitation is used, then it is more accurate to measure the sound radiation efficiency than the power conversion efficiency for motor structures. The effect of three different inverter designs (an ideal ???almost sinusoidal??? controller and two commercially available PWM inverters) on the radiated acoustic power were assessed for both no-load and load conditions using sound intensity measurements conducted in an anechoic room. The results indicate that although the sound power level due to aerodynamic and mechanical noise increases at a rate of 12 dB per doubling of the motor speed, the electromagnetic noise dominates at low motor speeds and is still a significant noise source even at high motor speeds. For inverters with low switching frequencies, the radiated sound power level is almost 15 dB higher than the ideal case at low speeds and is relatively insensitive to the motor speed. For inverters that implement the random modulation technique, the change in the total sound power level with the level of the random modulation is very small but the tonal nature of the noise is greatly reduced. The vibration behaviour of a motor structure was modeled using the finite element method (FEM) and validated using the experimental modal testing results. It has been found that it is essential to model the laminated stator as an orthotropic structure. While the details of other structural components (such as the endshields, the teeth in the stator and the windings) are not so important, it is essential that they are incorporated into the structural model as simplified structures to account for their mass, stiffness and boundary conditions imposed on the motor structure. Based on this structural model, the radiated acoustic power for various operating conditions has been predicated using the boundary element (BEM) and the electromagnetic force calculated from an electromagnetic finite element model. The predicted results agree reasonably well with experimental measurements. Despite the success of the FEM/BEM approaches, they can be prohibitively expensive (in terms of computer resources required) to apply to large motors and high frequencies. Thus the feasibility of using a statistical method, namely, the statistical energy analysis (SEA), to estimate the radiated acoustic sound power from an inverter-driven induction motor has been examined. In order to carry out this analysis, analytical expressions for calculating the natural frequencies and radiation efficiency of finite length circular cylindrical shells (which are simplified models of the stator and casing of a motor structure) were firstly derived. The internal loss factors and coupling loss factors of the motor structure were determined experimentally using the power injection method. Then by introducing an equivalent surface mobility of circular cylindrical shells for the electromagnetic force, the vibration response and the acoustic noise radiated from each part of the motor structure were estimated. Results indicate that SEA method is potentially an efficient and effective tool in estimating the noise radiated from inverter-driven induction motors.
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Liu, Tianyi. "Control strategy for a mono-inverter multi-PMSM system - Stability and efficiency." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19624/7/tianyi_liu.pdf.
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During these decades, Permanent Magnet Synchronous Motor (PMSM) has become a vital part of military, industry and civil applications due to the advantages of high power density, high efficiency, high reliability and simple structure, small volume and light weight. Sometimes, multiple PMSMs are used to carry out cooperative functions. For example, the bogie of a locomotive, the flight control surface of an airplane. These PMSMs usually operates at the same speed. To reduce the volume and weight, an idea of sharing the static power conversion devices, which is called Mono-Inverter Multi-PMSM system (MIMPMSM), is raised. Although many researchers have given different controller solutions for the MIMPMSM system, most of them are not clear in the aspects of system stability and efficiency issues. This has become the biggest obstacle to the practical use of MIMPMSM. Oriented with these problems, starting with a MIMPMSM system with 2 motors, in the first step, we have tested some control strategies by an experiment to verify the feasibility and performance of them. In final, based on the experiment data, we have figured that the overconstraint problem exists in some control strategies. Then, an analysis and controller design based on steady-state model of a Mono-Inverter Dual-PMSM (MIDPMSM) system is carried out.By studying the solution existence problem of the steady-state model, we give out the design guideline to the controller structure. Combining the open-loop stability and steady-state solution, the region of controllability and stability is obtained. Lagrange Multiplier is used develop theexpression of efficiency-optimal steady-staterelated to torque and speed. The experiment has shown that the efficiency of the new controller has improved significantly. Meanwhile, we have explored the influence of parameter variation in system stability and efficiency-optimization. The variation will influence the stability region. But its influence can be eliminated by using Master- Slave strategy. On the other hand, in the aspect of efficiency optimization, the simulation results have shown that parameter mismatch, especially the permeant flux, can cause high efficiency loss. In the last step, this controller is also adapted to a MIMPMSM system with more than two motors. The simulation results demonstrate the effectiveness.
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Nguyen, Dinh Liem. "Spectral Methods for Direct and Inverse Scattering from Periodic Structures." Phd thesis, Ecole Polytechnique X, 2012. http://tel.archives-ouvertes.fr/tel-00771746.
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The main topic of the thesis are inverse scattering problems of electromagnetic waves from periodic structures. We study first the direct problem and its numerical resolution using volume integral equation methods with a focus on the case of strongly singular integral operators and discontinuous coefficients. In a second investigation of the direct problem we study conditions on the material parameters under which well-posedness is ensured for all positive wave numbers. Such conditions exclude the existence of guided waves. The considered inverse scattering problem is related to shape identification. To treat this class of inverse problems, we investigate the so-called Factorization method as a tool to identify periodic patterns from measured scattered waves. In this thesis, these measurements are always related to plane incident waves. The outline of the thesis is the following: The first chapter is the introduction where we give the state of the art and new results of the topics studied in the thesis. The main content consists of five chapters, divided into two parts. The first part deals with the scalar case where the TM electromagnetic polarization is considered. In the second chapter we present the volume integral equation method with new results on Garding inequalities, convergence theory and numerical validation. The third chapter is devoted to the analysis of the Factorization method for the inverse scalar problem as well as some numerical experiments. The second part is dedicated to the study of 3-D Maxwell's equations. The fourth and fifth chapters are respectively generalizations of the results of the second and third ones to the case of Maxwell's equations. The sixth chapter contains the analysis of uniqueness conditions for the direct scattering problem, that is, absence of guided modes.
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Lebrun, Delphine. "Fabrication of inverse opal oxide structures for efficient light harvesting." Licentiate thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-232228.
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Artificial opals are self-assembled face centered cubic (fcc) structures of spherically shaped beads, which interesting applications as photonic band gap materials. Inverse opals are photonic crystals consisting of fcc paced voids of a low refractive index material imbedded in a high refractive index material. Such structures has been used to enhance the photocatalytic effect of different materials and motivates further studies to improve the deposition process of the opal templates and their inversion. We state the fabrication method to design and model metal oxide inverse opals. We have successfully created alumina and alumina-titania inverse opals. With the help of simulations, we engineered inverse opals with self-assembly and atomic layer deposition.
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Tyler, Arwen Irene Ingrid. "Ordered inverse micellar phases of lipids : structures and transition kinetics." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/12668.
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Non-bilayer phases are thought to be of considerable biological relevance. Whenever there is a topological change in the membrane, corresponding to events such as membrane fusion, non-bilayer structures are assumed to be adopted locally. Several complex three-dimensional lyotropic liquid crystal phases are already known, such as the bicontinuous cubic phases, but for many years only a single example was found – a cubic phase of spacegroup Fd3m – of a structure based upon a complex close packing of inverse micelles. A novel lyotropic liquid crystal phase has been discovered and its structure has been solved. The new phase belongs to spacegroup P63/mmc, whose structure is based upon a hexagonal close packing of identical quasi-spherical inverse micelles. [147]. The equilibrium phase behaviour of binary Phospholipid: Diacylglycerol [172] and ternary Phospholipid:Diacylglycerol:Cholesterol mixtures in excess water have been investigated as a function of hydrostatic pressure and temperature using synchrotron x-ray diffraction. By changing hydration and hydrocarbon chain unsaturation, and by varying the mole ratio of the mixtures, the interfacial curvature of the system can be tuned and a plethora of phases are found to be adopted by the various mixtures. There is a scarcity of knowledge regarding the kinetics and mechanisms of lyotropic phase transitions; such transitions are relevant in understanding fundamental cellular processes such as membrane fusion and fission. Time resolved x-ray diffraction experiments, using pressure as the trigger mechanism have been employed in order to investigate lamellar – non-lamellar transition kinetics in cholesterol/ phospholipid/diacylglycerol model membrane systems and preliminary results are presented.
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ZHANG, GUXIANG. "Determination des forces appliquees aux structures industrielles par des methodes inverses." Toulouse 3, 1998. http://www.theses.fr/1998TOU30029.
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Afin de caracteriser indirectement des forces appliquees sur les structures industrielles a partir de la mesure de leur comportement dynamique, trois methodes inverses (la methode de la matrice des transformees de fourier des reponses vibratoires, la methode de la matrice interspectrale des reponses vibratoires et la methode inverse utilisant la technique pca) sont presentees. Les avantages et les contraintes d'utilisation de chacune sont analyses. Pour evaluer leurs performances, des tests de l'identification des forces par ces trois methodes inverses sont realises sur des structures simples ainsi que sur des structures complexes. A travers des simulations numeriques, les principales causes d'erreurs existant dans l'identification des forces par les methodes inverses sont mises en evidence. La propagation des erreurs sur les reponses vibratoires et sur les fonctions de transfert vers les forces estimees a fait objet d'une evaluation quantitative. Le role du nombre de conditionnement de la matrice des fonctions de transfert est mis en lumiere. Des techniques pour l'amelioration du conditionnement de la matrice des fonctions de transfert sont proposees. En utilisant la variance comme estimateur, les erreurs statistiques sur les forces identifiees sont determinees a partir des donnees initialement mesurees et des parametres experimentaux. L'application des methodes inverses proposees a une structure mecanique complexe montre l'efficacite et les perspectives de la determination indirecte des forces agissant sur les structures mecaniques industrielles.
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Ahmed, Bacha Rekia Meriem. "Sur un problème inverse en pressage de matériaux biologiques à structure cellulaire." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2439.
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Cette thèse, proposée dans le cadre du projet W2P1-DECOL (SAS PIVERT), financée par le ministère de l’enseignement supérieur est consacrée à l’étude d’un problème inverse de pressage des matériaux biologiques à structure cellulaire. Le but est d’identifier connaissant les mesures du flux d’huile sortant, le coefficient de consolidation du gâteau de pressage et l’inverse du temps caractéristique de consolidation sur deux niveaux : au niveau de la graine de colza et au niveau du gâteau de pressage. Dans un premier temps, nous présentons un système d’équations paraboliques modélisant le problème de pressage des matériaux biologiques à structure cellulaire, il découle de l’équation de continuité de la loi de Darcy et d’autres hypothèses simplificatrices. Puis l’analyse théorique et numérique du modèle direct est faite dans le cas linéaire. Enfin la méthode des différences finies est utilisée pour le discrétiser. Dans un second temps, nous introduisons le problème inverse du pressage où l’étude de l’identifiabilité de ce problème est résolue par une méthode spectrale. Par la suite, nous nous intéressons à l’étude de stabilité lipschitzienne locale et globale. De plus une estimation de stabilité lipschitzienne globale, pour le problème inverse de paramètres, dans le cas du système d’équations paraboliques, à partir des mesures sur ]0,T[ est établie. Enfin l’identification des paramètres est résolue par deux méthodes, l’une basée sur l’adaptation de la méthode algébrique et l’autre formulée comme la minimisation au sens des moindres carrés d’une fonctionnelle évaluant l’écart entre les mesures et les résultats du modèle direct, la résolution de ce problème inverse se fait en utilisant un algorithme itératif BFGS, l’algorithme est validé puis testé numériquement dans le cas des graines de colza, en utilisant des mesures synthétiques. Il donne des résultats très satisfaisants, malgré les difficultés rencontrés à manipuler et exploiter les données expérimentalesThis thesis, proposed in the framework of the W2P1-DECOL project (SAS PIVERT) and funded by the Ministry of Higher Education, is devoted to the study an inverse problem of pressing biological materials with a cellular structure. The aim is to identify, of the outgoing oil flow, the coefficient of consolidation of the pressing cake and the inverse of the characteristic time of consolidation on two levels : at the level of the rapeseed and at the level of the pressing cake. First, we present a system of parabolic equations modeling the pressing problem of biological materials with cellular structure; it follows from the continuity equation of Darcy’s law and other simplifying hypotheses. Then a theoretical and numerical analysis of a direct model is made in the linear case. Finally the finite difference method is usedt o discretize it. In a second step, we introduce the inverse problem of the pressing where the study of the identifiability of this problem is solved by a spectral method. Later we are interested in the study of local and global Lipschitizian stability. Moreover, global Lipschitz stability estimate for the inverse problem of parameters in the case of the system of parabolic equations from the measures on ]0,T[ is established. Finally, the identification of the parameters is solved by two methods; one based on the adaptation of the algebraic method and the other formulated as the minimization in the least squares sense of a functional evaluating the difference between measurements and the results of the direct model; the resolution of this inverse problem is done using an iterative algorithm BFGS, the algorithm is validated and then tested numerically in the case of rapeseeds, using synthetic measures. It gives very satisfactory results, despite the difficulties encountered in handling and exploiting the experimental data
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Poudel, Chetan. "Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles." Oberlin College Honors Theses / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1400251699.
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Wery-Venturini, Jany. "Contribution à l'étude de la structure microscopique de micelles inverses d'octanoate de plomb." Nantes, 1992. http://www.theses.fr/1992NANT2012.
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Le travail presente l'etude de systemes micellaires inverses constitues de dispersions de dimethyl-3,5-hexanoate de plomb neutres et surbasees dans un hydrocarbure. Le memoire comporte deux parties. La premiere, concerne la caracterisation des curs mineraux des micelles inverses a l'aide de differentes techniques complementaires. La microscopie electronique a transmission (sad) et a la spectroscopie de perte d'energie en electrons transmis (eels), a permis de mettre en evidence la tres petite taille (10 a environ), l'ordre local (presence d'un anneau de diffraction elargi), ainsi que l'environnement moleculaire (groupements carboxyliques) du cur micellaire. Les resultats quantitatifs, quant a l'ordre local existant dans les curs mineraux ont ete obtenus par spectroscopie exafs (extended x-ray absorption fine structure) et nous ont ainsi permis de proposer deux structures conduisant a une forme discoide des micelles et expliquant en partie leur facilite d'agregation. L'etude des micelles en met ayant revele une evolution importante des echantillons sous le faisceau, la 2eme partie s'est attachee a caracteriser les degats d'irradiation subis a temperature ambiante par les micelles surbasees en cours d'observation. Les etudes faites en sad et en eels (a faible dose) puis en spectrometrie de masse, nous ont permis d'apprehender les parametres cinetiques de ce phenomene et de proposer un mecanisme probable de degradation