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Pisharody, Sandhya. "A shape analysis approach to prediction of bone stiffness using FEXI." Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:2685.
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The preferred method of assessing the risk of an osteoporosis related fracture is currently a measure of bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA). However, other factors contribute to the overall risk of fracture, including anatomical geometry and the spatial distribution of bone. Finite element analysis can be performed in both two and three dimensions, and predicts the deformation or induced stress when a load is applied to a structure (such as a bone) of defined material composition and shape. The simulation of a mechanical compression test provides a measure of whole bone stiffness (N mm−1). A simulation system was developed to study the sensitivity of BMD, 3D and 2D finite element analysis to variations in geometric parameters of a virtual proximal femur model. This study demonstrated that 3D FE and 2D FE (FEXI) were significantly more sensitive to the anatomical shape and composition of the proximal femur than conventional BMD. The simulation approach helped to analyse and understand how variations in geometric parameters affect the stiffness and hence strength of a bone susceptible to osteoporotic fracture. Originally, the FEXI technique modelled the femur as a thin plate model of an assumed constant depth for finite element analysis (FEA). A better prediction of tissue depth across the bone, based on its geometry, was required to provide a more accurate model for FEA. A shape template was developed for the proximal femur to provide this information for the 3D FE analysis. Geometric morphometric techniques were used to procure and analyse shape information from a set of CT scans of excised human femora. Generalized Procrustes Analysis and Thin Plate Splines were employed to analyse the data and generate a shape template for the proximal femur. 2D Offset and Depth maps generated from the training set data were then combined to model the three-dimensional shape of the bone. The template was used to predict the three-dimensional bone shape from a 2D image of the proximal femur procured through a DXA scan. The error in the predicted 3D shape was measured as the difference in predicted and actual depths at each pixel. The mean error in predicted depths was found to be 1.7mm compared to an average bone depth of 34mm. 3D FEXI analysis on the predicted 3D bone along with 2D FEXI for a stance loading condition and BMD measurement were performed based on 2D radiographic projections of the CT scans and compared to bone stiffness results obtained from finite element analysis of the original 3D CT scans. 3D FEXI provided a significantly higher correlation (R2 = 0.85) with conventional CT derived 3D finite element analysis than achieved with both BMD (R2 = 0.52) and 2D FEXI (R2 = 0.44).
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Lampinen, Björn. "Protocol optimization of the filter exchange imaging (FEXI) sequence and implications on group sizes : a test-retest study." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-196327.
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Diffusion weighted imaging (DWI) is a branch within the field of magnetic resonance imaging (MRI) that relies on the diffusion of water molecules for its contrast. Its clinical applications include the early diagnosis of ischemic stroke and mapping of the nerve tracts of the brain. The recent development of filter exchange imaging (FEXI) and the introduction of the apparent exchange rate (AXR) present a new DWI based technique that uses the exchange of water between compartments as contrast. FEXI could offer new clinical possibilities in diagnosis, differentiation and treatment follow-up of conditions involving edema or altered membrane permeability, such as tumors, cerebral edema, multiple sclerosis and stroke. Necessary steps in determining the potential of AXR as a new biomarker include running comparative studies between controls and different patient groups, looking for conditions showing large AXR-changes. However, before designing such studies, the experimental protocol of FEXI should be optimized to minimize the experimental variance. Such optimization would improve the data quality, shorten the scan time and keep the required study group sizes smaller. Here, optimization was done using an active imaging approach and the Cramer-Rao lower bound (CRLB) of Fisher information theory. Three optimal protocols were obtained, each specialized at different tissue types, and the CRLB method was verified by bootstrapping. A test-retest study of 18 volunteers was conducted in order to investigate the reproducibility of the AXR as measured by one of the protocols, adapted for the scanner. Group sizes required were calculated based on both CRLB and the variability of the test-retest data, as well as choices in data analysis such as region of interest (ROI) size. The result of this study is new protocols offering a reduction in coefficient of variation (CV) of around 30%, as compared to previously presented protocols. Calculations of group sizes required showed that they can be used to decide whether any patient group, in a given brain region, has large alterations of AXR using as few as four individuals per group, on average, while still keeping the scan time below 15 minutes. The test-retest study showed a larger than expected variability however, and uncovered artifact like changes in AXR between measurements. Reproducibility of AXR values ranged from modest to acceptable, depending on the brain region. Group size estimations based on the collected data showed that it is still possible to detect AXR difference larger than 50% in most brain regions using fewer than ten individuals. Limitations of this study include an imprecise knowledge of model priors and a possibly suboptimal modeling of the bias caused by weak signals. Future studies on FEXI methodology could improve the method further by addressing these matters and possibly also the unknown source of variability. For minimal variability, comparative studies of AXR in patient groups could use a protocol among those presented here, while choosing large ROI sizes and calculating the AXR based on averaged signals.
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Molina-Sepulveda, Roberto. "Hybridization of FETI Methods." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066455/document.
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Dans le présent travail, des nouvelles méthodes de décomposition de domaine et des nouvelles implémentations pour des méthodes existantes sont développées. Une nouvelle méthode basée sur les méthodes antérieures de décomposition du domaine est formulée. Les méthodes classiques FETI plus FETI-2LM sont utilisées pour construire le nouveau Hybrid-FETI. L'idée de base est de développer un nouvel algorithme qui peut utiliser les deux méthodes en même temps en choisissant dans chaque interface l'état le plus adapté en fonction des caractéristiques du problème. En faisant cela, nous recherchons un code plus rapide et plus robuste qui peut fonctionner avec des configurations selon lesquelles les méthodes de base ne le géreront pas de manière optimale par lui-même. La performance est testée sur un problème de contact. La partie suivante implique le développement d'une nouvelle implémentation pour la méthode S-FETI, l'idée est de réduire l'utilisation de la mémoire de cette méthode, afin de pouvoir fonctionner dans des problèmes de taille plus important. Différentes variantes pour cette méthode sont également proposées, tout en cherchant la réduction des directions stockées chaque itération de la méthode itérative. Finalement, une extension de la méthode FETI-2LM à sa version en bloc comme dans S-FETI, est développée. Les résultats numériques pour les différents algorithmes sont présentésIn this work new domain decomposition methods and new implementations for existing methods are developed. A new method based on previous domain decomposition methods is formulated. The classic FETI plus FETI-2LM methods are used to build the new Hybrid-FETI. The basic idea is to develop a new algorithm that can use both methods at the same time by choosing in each interface the most suited condition depending on the characteristics of the problem. By doing this we search to have a faster and more robust code that can work with configurations that the base methods will not handle it optimally by himself. The performance is tested on a contact problem. The following part involves the development of a new implementation for the S-FETI method, the idea is to reduce the memory usage of this method, to make it able to work in larger problem. Different variation for this method are also proposed, all searching the reduction of directions stored each iteration of the iterative method. Finally, an extension of the FETI-2LM method to his block version as in S-FETI, is developed. Numerical results for the different algorithms are presented
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Liu, Fei. "Réactions de fluoration de dérivés azotés insaturés en milieu superacide." Poitiers, 2010. http://theses.edel.univ-poitiers.fr/theses/2010/Liu-Fei/2010-Liu-Fei-These.pdf.
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L'utilisation des milieux superacides modifiant la réactivité des substrats organiques permet d'effectuer de nouvelles réactions et d'accéder rapidement à des produits originaux difficilement accessibles par les méthodes classiques. Il est alors possible de réaliser de nombreuses transformations directes, notamment des réactions de fluoration originales. Ce travail est consacré à l'étude de la réactivité de dérivés azotés insaturés en milieu superacide HF/SbF5 et en particulier au développement de nouvelles méthodes de fluoration de ce type de composés. Basée sur la formation d'intermédiaires dicationiques superélectrophiles, une nouvelle réaction d'hydrofluoration a été développée. L'utilisation de l'activation superélectrophile en milieu superacide a également permis la synthèse originale de sulfonamides cycliques et/ou fluorés. Après identification d'intermédiaires réactionnels polycationiques par analyse RMN in situ, une nouvelle méthode de synthèse de dérivés azotés gem-chlorofluorés et gem-difluorés a finalement été élaboréeIn superacid the reactivity of organic substrates is strongly modified and new reactions can be performed, which allows a rapid access to original products. In these conditions, multiple direct transformations occur and especially original fluorination reactions. This work was devoted to the study of the reactivity of unsaturated nitrogen derivatives in superacid (HF/SbF5) and to the development of new methods of fluorination of these compounds. Based on the formation of superelectrophilic dicationic intermediates, a new reaction of hydrofluorination has been developed. The use of superelectrophilic activation in superacid also allowed the original synthesis of benzofused sultams and/or fluorinated sulfonamides. After identification of reaction polycationic intermediates by NMR in situ analysis, a new synthetic route to gem-chlorofluoro nitrogen derivatives or gem-difluoro nitrogen derivatives has finally been set up
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Toulougoussou, Ange Barthélemy. "Méthodes de sous-domaines pour le système de Stokes." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066694.
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L'objectif de cette thèse est de développer une méthode de décomposition de domaine pour la résolution du système de Stokes discrétisé avec les éléments finis mixtes stables où la pression est continue comme Hood-Taylor et Mini. La nouvelle méthode résulte dela combinaison de FETI qui est appliquée à la vitesse et de BDD qui est appliquée à la pression sans découpler les inconnues. Elle hérite et découple les projecteurs grossiers associés à FETI et à BDD. La méthodologie débouche sur un système linéaire symétrique,semi-défini positif que nous avons résolu par la méthode du gradient conjugué projeté préconditionné. La méthode contient deux préconditionneurs grossiers creux et des préconditionneurs locaux exacts qui assurent son extensibilié, sa robustesse et son efficacité. L'introduction de projecteurs locaux construits à partir des modes de pression des sousdomaines étend la méthode aux éléments finis mixtes discontinues en pression et rend le problème grossier de BDD facultatif même en présence de la pression aux interfaces.Nous avons aisément appliqué la méthode à l'élasticité incompressible et quasi-incompressible et elle peut s'étendre de la même façon au cadre plus général des systèmes de point-selle issus des problèmes de minimisation sous contraintes grâce à sa nature algébriqueThe purpose of this thesis is to develop a domain decomposition method suitable tosolve the Stokes system discretized with stable mixte finite elements where pressure is continuous such as Hood-Taylor and Mini. The new method arises from the combinaison of FETI applied to the velocity and BDD applied to the pressure without decoupling the unknowns. It inherits and decouples the coarse projectors included in FETI and BDD. The methodology leads to a symmetric, positive semi-definite linear system that we solveby projected preconditioned conjugate gradient. The method contains two sparse coarse preconditionners and exact local preconditionners that ensure its scalability, its robustness and its efficiency. We use local projectors constructed from the constant pressure modes of the subdomains that enable an extension to mixte finite elements with discontinuous pressure and that make the coarse problem of BDD optional even in the presence of pressure on the interfaces. We have easily applied the method to incompressibleand almost incompressible elasticity and it can be extended the same way to other saddle-point systems arising from minimization problems under constraints due to its algebraic property
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Adeyemi, Adesola Olusiji. "The dramaturgy of Femi Osofisan." Thesis, University of Leeds, 2009. http://etheses.whiterose.ac.uk/8935/.
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Sanghavi, Chaitanya. "FETI methods for acoustic problems with porous materials." Thesis, Le Mans, 2020. http://www.theses.fr/2020LEMA1021.
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E présent travail traite de la modélisation numérique de traitements acoustiques à grande échelle en utilisant des méthodes de décomposition de domaine (MDD). Les principaux objectifs de la thèse sont triples : Premièrement, un choix de méthode de décomposition de domaine (DDM) approprié pour résoudre des problèmes de Helmholtz homogènes et hétérogènes à grande échelle est fait. Deux variantes différentes des méthodes FETI, à savoir FETI-2LM et FETI-H, sont mises en œuvre et comparées. Un choix approprié de la méthode est fait. Ensuite, une nouvelle stratégie de résolution est appliquée au DDM choisi pour résoudre de nombreux traitements acoustiques. Cette stratégie vise à réduire les coûts de calcul associés aux étapes. Troisièmement, des stratégies alternatives sont examinées pour réduire les coûts associés aux coûts itératifs du DDM. Une nouvelle méthode FETI-2LM à deux niveaux est formulée pour réduire les coûts des évaluations successives des revêtements. Une autre stratégie de recyclage basée sur l'utilisation des valeurs propres les plus influentes est examinée pour la méthode FETI-2LM. Un choix approprié de ces méthodes est fait. La modélisation numérique des traitements acoustiques à l'aide de méthodes efficaces nécessite des coûts de calcul importantss dans la phase de conception. Ce travail fournit une contribution permettant de résoudre ce problème à l'aide de la DDMSound absorbing materials such as foams are widelyused in many industrial and domestic applications toabsorb undesirable sound. One needs to perform many calculations to get desirable properties of thetreatment using optimization strategies.The state-of-the-art computational models requireprohibitively high computational time. Theproblematic of this PhD is to reduce thecomputational time for such models to speed updesign calculations.This document is a synthesis of the work carried outin this direction. The problem is addressed usingDomain Decompostion methods (DDM). It consists ofsplitting the original problem into small parts referredto as subdomains. A partial solution is computed onthese subdomains to match the global continuity inthe domain of interest. Different DDM methods are benchmarked in termsof performance and scalability , specific for porousmaterials. Any DDM consists of two major costs, thefactorization of the subdomains and iterative part forthe global convergence. A novel factorizationstrategy is implemented and applied in 2D and 3Dto demonstrate savings in time compared toconventional approaches. In the second part, themethod is further improved to reduce the iterativecosts for a series of calculations.A final workflow is proposed to make thecomputationa cost of these models afforable withinindustrial timeframes
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Hamrit, Oussama. "Etude des pertes magnétiques dans les matériaux magnétiques destinés aux applications de transport en haute fréquence et sous champ bidirectionnel." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN003/document.
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Les pertes fer dans une machine électrique sont d'importance capitale, une estimation approximative de ces pertes peu mener à des solutions non viable sur le plan thermique, c'est dans ce contexte qu'il est indispensable d'avoir les caractéristiques les plus précises des matériaux magnétiques utilisés, de plus avec l'engouement récent pour les machines électriques haute vitesse (donc haute fréquence), il est important de caractériser les matériaux à haute fréquence. Dans les travaux de cette thèse, un système de mesure haute fréquence (1 T - 10 kHz) en champ unidirectionnel a été mis en place et des modèles de pertes magnétiques hautes fréquences ont été étudiés et discutés. Les champs magnétiques circulant dans une machine électrique sont de type alternatifs dans une direction donnée ou des champs elliptiques et tournants. C'est dans ce contexte qu'une caractérisation et un modèle en champ tournant ont été proposés. Enfin, dans le cas où le stator d'une machine électrique est découpé d'un seul tenant, la direction de découpe par rapport àla direction de laminage change d'un pas dentaire à un autre, pour cela une étude sur l'anisotropie des matériaux FeSi non orientés a été menéeIron losses in electrical machine applications are of paramount importance, an approximate estimation of these losses can easily lead to a thermally unsustainable solution, in this context, it is essential to get exactly the magnetic characteristics of the magnetic materials used, moreover, with the recent interest for high speed electrical machines (high frequency), It is important to characterize magnetic materials at high frequency. In this work, a high frequency characterizing system (1 T - 10 kHz) under unidirectional field has been proposed and magnetic losses models has been studied and discussed. Magnetic fields in electrical machines could be alternative in one direction, elliptical or circular. In this context, a characterization under rotating field and a magnetic loss model has been proposed. Finally, when stator steel sheets are cut all in one piece, the cutting direction with regard to the rolling direction will change from one tooth pitch to another, for that a study of the FeSi non oriented anisotropy has been performed
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Luk, Yu-shing. "A study of Yue Fei studies since late Qing Qing mo yi lai zhi Yue Fei yan jiu /." Click to view the E-thesis via HKUTO, 1995. http://sunzi.lib.hku.hk/hkuto/record/B31950838.
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Reeve, Michael Andrew Hall. "Demonstrating the world mind and society in the Shuo Lin chapters of the "Han Fei Zi" /." online access from Digital Dissertation Consortium access full-text, 2003. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?3080034.
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Lundahl, Bertil. "Han Fei Zi : the man and the work." Doctoral thesis, Stockholm : Institute of oriental languages, 1992. http://catalogue.bnf.fr/ark:/12148/cb35722167q.
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Castro, Edgar David Guarin. "Análise das microestruturas magnéticas em filmes de FeNi." reponame:Repositório Institucional da UnB, 2017. http://repositorio.unb.br/handle/10482/23286.
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Dissertação (mestrado)—Universidade de Brasília, Instituto de Física, Programa de Pós-Graduação em Física, 2017.Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2017-04-06T18:08:38Z No. of bitstreams: 1 2017_EdgarDavidGuarinCastro.pdf: 13967221 bytes, checksum: 5cf464b7be6dd878aa1766e53fd3f994 (MD5)
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O presente trabalho expõe um estudo estrutural e magnético feito em filmes policristalinos de FeNi sobre substratos de Si. Medidas de energia dispersiva de raios X indicaram concentrações relativas de 64% para o ferro e 36% para o níquel, o que significa que os filmes possuem a concentração Invar, fenômeno caracterizado pela queda do coeficiente de dilatação da liga até valores muito baixos. Estudos experimentais mostram que este fenômeno deve estar fortemente vinculado com a estrutura magnética das ligas, mas os modelos teóricos ainda não conseguem explicar completamente a relação entre suas propriedades magnéticas e mecânicas, motivando continuados estudos sobre suas propriedades magnéticas. Nesta pesquisa foi proposto estudar e analisar a configuração micromagnética para três filmes de FeNi na concentração Invar, para três diferentes espessuras (30, 70 e 140 nm), por meio de técnicas experimentais como a magnetometria e a microscopia de força magnética (MFM), assim como por meio do uso de simulações computadorizadas, para oferecer mais bases experimentais que contribuam na compreensão dos fenômenos presentes nas ligas Invar. Os resultados revelaram inomogeneidades magnéticas causadas pela policristalinidade dos filmes. As amostras também manifestaram um comportamento ferromagnético mole, com magnetizações de saturação e anisotropias efetivas crescentes com o aumento das espessuras. Os resultados também mostraram uma grande influência da anisotropia de forma que faz com que os filmes sejam facilmente magnetizados no plano. Finalmente, com base nas medidas de magnetometria, a estrutura micromagnética dos filmes foi mapeada por medidas de MFM e posteriormente simulada com o software MuMax3. Os mapas revelaram domínios com magnetizações locais paralelas à superfície dos filmes, enquanto que as paredes possuem uma estrutura tipo Bloch, principalmente no interior dos filmes mais grossos. Deste modo, percebe-se que a anisotropia do material define eixos fáceis de magnetização no plano dos filmes, por causa da anisotropia de forma, que obriga às paredes de domínio a se distribuírem nos filmes, formando padrões de ziguezague irregulares na superfície.
The present work reports structural and magnetic study of FeNi polycrystalline films on Si substrates. X-ray dispersive energy measurements indicated relative concentrations of 64% iron and 36% nickel, which means that the films present Invar concentration, a phenomenon characterized by the decrease of the thermal expansion coefficient of the alloy to very low values. Experimental studies show that this phenomenon is strongly related to the magnetic structure of the alloys, but current theoretical models still cannot fully explain the relation between magnetic and mechanical characteristics of Invar alloys, motivating continued studies on their magnetic properties. In this research, the micromagnetic configuration for three FeNi films in Invar concentration and three different thicknesses (30, 70 and 140 nm) is analyzed according to their thicknesses. Experimental techniques such as SQUID magnetometry and Magnetic Force Microscopy (MFM) were used, as well as computer simulations, to offer more experimental bases that contribute to the understanding of the phenomena present in FeNi36 Invar alloys. Results revealed magnetic inhomogeneities caused by film polycrystallinity. The samples also showed a soft ferromagnetic behavior, with increasing saturation magnetizations and effective anisotropies with increasing thicknesses. Results also showed a great influence of shape anisotropy so that the films are easily magnetized in-plane. Finally, magnetometry measurements were complemented by micromagnetic structure mapping by Magnetic Force Microscopy, the resulting magnetic images were later simulated with the software MuMax3. The maps revealed domains with local magnetizations parallel to the surface of the films, while the walls have a Bloch-like structure, mainly inside the thicker films. In this way, the anisotropy of the material defines an easy axis of magnetization in the plane of the films, because of the shape anisotropy, which forces the domain walls to distribute in the films, forming irregular zigzag like patterns on the surface.
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Witkowski, Thomas. "Software concepts and algorithms for an efficient and scalable parallel finite element method." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-141651.
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Software packages for the numerical solution of partial differential equations (PDEs) using the finite element method are important in different fields of research. The basic data structures and algorithms change in time, as the user\'s requirements are growing and the software must efficiently use the newest highly parallel computing systems. This is the central point of this work. To make efficiently use of parallel computing systems with growing number of independent basic computing units, i.e.~CPUs, we have to combine data structures and algorithms from different areas of mathematics and computer science. Two crucial parts are a distributed mesh and parallel solver for linear systems of equations. For both there exists multiple independent approaches. In this work we argue that it is necessary to combine both of them to allow for an efficient and scalable implementation of the finite element method. First, we present concepts, data structures and algorithms for distributed meshes, which allow for local refinement. The central point of our presentation is to provide arbitrary geometrical information of the mesh and its distribution to the linear solver. A large part of the overall computing time of the finite element method is spend by the linear solver. Thus, its parallelization is of major importance. Based on the presented concept for distributed meshes, we preset several different linear solver methods. Hereby we concentrate on general purpose linear solver, which makes only little assumptions about the systems to be solver. For this, a new FETI-DP (Finite Element Tearing and Interconnect - Dual Primal) method is proposed. Those the standard FETI-DP method is quasi optimal from a mathematical point of view, its not possible to implement it efficiently for a large number of processors (> 10,000). The main reason is a relatively small but globally distributed coarse mesh problem. To circumvent this problem, we propose a new multilevel FETI-DP method which hierarchically decompose the coarse grid problem. This leads to a more local communication pattern for solver the coarse grid problem and makes it possible to scale for a large number of processors. Besides the parallelization of the finite element method, we discuss an approach to speed up serial computations of existing finite element packages. In many computations the PDE to be solved consists of more than one variable. This is especially the case in multi-physics modeling. Observation show that in many of these computation the solution structure of the variables is different. But in the standard finite element method, only one mesh is used for the discretization of all variables. We present a multi-mesh finite element method, which allows to discretize a system of PDEs with two independently refined meshesSoftwarepakete zur numerischen Lösung partieller Differentialgleichungen mit Hilfe der Finiten-Element-Methode sind in vielen Forschungsbereichen ein wichtiges Werkzeug. Die dahinter stehenden Datenstrukturen und Algorithmen unterliegen einer ständigen Neuentwicklung um den immer weiter steigenden Anforderungen der Nutzergemeinde gerecht zu werden und um neue, hochgradig parallel Rechnerarchitekturen effizient nutzen zu können. Dies ist auch der Kernpunkt dieser Arbeit. Um parallel Rechnerarchitekturen mit einer immer höher werdenden Anzahl an von einander unabhängigen Recheneinheiten, z.B.~Prozessoren, effizient Nutzen zu können, müssen Datenstrukturen und Algorithmen aus verschiedenen Teilgebieten der Mathematik und Informatik entwickelt und miteinander kombiniert werden. Im Kern sind dies zwei Bereiche: verteilte Gitter und parallele Löser für lineare Gleichungssysteme. Für jedes der beiden Teilgebiete existieren unabhängig voneinander zahlreiche Ansätze. In dieser Arbeit wird argumentiert, dass für hochskalierbare Anwendungen der Finiten-Elemente-Methode nur eine Kombination beider Teilgebiete und die Verknüpfung der darunter liegenden Datenstrukturen eine effiziente und skalierbare Implementierung ermöglicht. Zuerst stellen wir Konzepte vor, die parallele verteile Gitter mit entsprechenden Adaptionstrategien ermöglichen. Zentraler Punkt ist hier die Informationsaufbereitung für beliebige Löser linearer Gleichungssysteme. Beim Lösen partieller Differentialgleichung mit der Finiten Elemente Methode wird ein großer Teil der Rechenzeit für das Lösen der dabei anfallenden linearen Gleichungssysteme aufgebracht. Daher ist deren Parallelisierung von zentraler Bedeutung. Basierend auf dem vorgestelltem Konzept für verteilten Gitter, welches beliebige geometrische Informationen für die linearen Löser aufbereiten kann, präsentieren wir mehrere unterschiedliche Lösermethoden. Besonders Gewicht wird dabei auf allgemeine Löser gelegt, die möglichst wenig Annahmen über das zu lösende System machen. Hierfür wird die FETI-DP (Finite Element Tearing and Interconnect - Dual Primal) Methode weiterentwickelt. Obwohl die FETI-DP Methode vom mathematischen Standpunkt her als quasi-optimal bezüglich der parallelen Skalierbarkeit gilt, kann sie für große Anzahl an Prozessoren (> 10.000) nicht mehr effizient implementiert werden. Dies liegt hauptsächlich an einem verhältnismäßig kleinem aber global verteilten Grobgitterproblem. Wir stellen eine Multilevel FETI-DP Methode vor, die dieses Problem durch eine hierarchische Komposition des Grobgitterproblems löst. Dadurch wird die Kommunikation entlang des Grobgitterproblems lokalisiert und die Skalierbarkeit der FETI-DP Methode auch für große Anzahl an Prozessoren sichergestellt. Neben der Parallelisierung der Finiten-Elemente-Methode beschäftigen wir uns in dieser Arbeit mit der Ausnutzung von bestimmten Voraussetzung um auch die sequentielle Effizienz bestehender Implementierung der Finiten-Elemente-Methode zu steigern. In vielen Fällen müssen partielle Differentialgleichungen mit mehreren Variablen gelöst werden. Sehr häufig ist dabei zu beobachten, insbesondere bei der Modellierung mehrere miteinander gekoppelter physikalischer Phänomene, dass die Lösungsstruktur der unterschiedlichen Variablen entweder schwach oder vollständig voneinander entkoppelt ist. In den meisten Implementierungen wird dabei nur ein Gitter zur Diskretisierung aller Variablen des Systems genutzt. Wir stellen eine Finite-Elemente-Methode vor, bei der zwei unabhängig voneinander verfeinerte Gitter genutzt werden können um ein System partieller Differentialgleichungen zu lösen
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Xu, Fei-Fei [Verfasser]. "Synthetic Oligosaccharides as Tools to Investigate Bacterial Capsular Polysaccharides and Teichoic Acids / Fei-Fei Xu." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1160235759/34.
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Ma, Chi-kin Patrick. "The death of Yue Fei (1103-1142) a critical study = Yue Fei si yin yan jiu /." Click to view the E-thesis via HKUTO, 1999. http://sunzi.lib.hku.hk/hkuto/record/B31952239.
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Razafindramanana, Volatiana. "Amélioration et compréhension du mécanisme d'activation de l'alliage FeTi dopé avec de l'hafnium, pour le stockage de l'hydrogène." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0907/document.
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La problématique de la première absorption (i.e. étape d’activation) de l’intermétallique FeTi, pour le stockage de l’hydrogène est souvent un frein pour son industrialisation. Le challenge réside dans la conception d’un « nouveau matériau » dont la première étape d’hydrogénation, s’effectue dans les mêmes conditions de température et de pression modérées, que lors de l’hydrogénation réversible. Une solution est de faire appel aux performances d’un élément dopant et/ou à la technique du broyage mécanique. Dans ce manuscrit, nous proposons l’utilisation de l’hafnium comme dopant. Ce projet complète les études qui ont été effectuées sur le zirconium (e.g. le zirconium commercial contient toujours une certaine quantité d’hafnium). L’ajout d’une faible quantité d’hafnium induit la formation d’une phase secondaire, « riche » en hafnium et en fer. Grâce à la présence de cette phase, la cinétique de première absorption est considérablement améliorée, et ce, sans traitement thermique préalable. L’étape d’activation comprend un seul mécanisme lorsque la taille des particules est faible. A contrario, un second mécanisme est mis en évidence, pour des particules de taille supérieure à 0,5 mm. La mécanosynthèse a permis non seulement d’obtenir la phase principale FeTi, mais aussi de favoriser la première absorption d’hydrogène. Des paramètres d’élaboration méticuleusement optimisés ont rendu possible la conception d’un matériau « modèle », par pulvérisation cathodique magnétron, sous forme de couche mince. Ce matériau modèle pourrait servir à étudier et à comprendre la diffusion de l’hydrogène à l’interface de la matrice FeTi et du dopant Zr ou HfThe issue of the first hydrogenation (i.e. activation process) of the intermetallic FeTi for the storage of hydrogen is often a brake for its use in industry. The challenge lies in the design of a "new material" whose first hydrogenation is carried out under the same conditions of moderate temperature and pressure, as during reversible absorption. Efficient solutions are to use a doping element and/or mechanical alloying process. In this work, we propose to use hafnium as a dopant. This project completes the studies that have been carried out on zirconium (e.g. commercial zirconium always contains a certain amount of hafnium). The addition of a small amount of hafnium induces the formation of a secondary phase, "rich" in hafnium and iron. Thanks to the presence of this phase, the kinetics of activation process is improved, without prior heat treatment. The activation process consists of a single step, when the particle size is small. However, a second step appears, for particles bigger than 0.5 mm. The mechanical alloying allowed the formation of the main phase FeTi, and also enhanced the activation process. An accurate control of deposition conditions allow us to design a ″model″ material by magnetron sputtering as thin layers. This ″model″ material can be used to study and understand the hydrogen diffusion, at the interface of the matrix (FeTi) and the dopant (Zr or Hf)
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Kwan, Miu-fan, and 關妙芬. "Characterization of TM4 of NRAMP1: implication for FEII transport." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29275143.
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Alonzo-Proulx, Olivier. "Low-temperature thermal conductivity of the amorphous superconductor FexNi₁-xZr₂." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97890.
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Thermal conductivity is a powerful tool to probe the phonon and electron exitations in a solid, especially in superconductors were one can basically tune the respective electronic and phononic contributions by applying a magnetic field below Tc.After a short review on the concepts of superconductivity, thermal conductivity and amorphous matter, we present a study of the thermal conductivity of an exotic material, the amorphous metallic superconductor Fe0.5Ni 0.5Zr2. The results indicate an unexpected dominant electonic contribution to the thermal conductivity across the superconducting transition, in accordance with an inhomogeneous sample composed of a bulk normal phase with inhomogeneous superconducting phases.
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Okoh, Julie Omoifo. "Théâtre et société : Femi Osofisan et S.A. Zinsou : étude comparée." Bordeaux 3, 1992. http://www.theses.fr/1992BOR30042.
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Entre le theatre et la societe existent des rapports dialectiques. Et notre but dans ce travail consiste a faire un rapprochement synthetique des oeuvres de deux dramaturges africains contemporains : femi osofisan, nigerian et s. A. Zinsou, togalais. Rapprochement qui permet de deceler des analogies ou des dissemblances dans leur vision du monde a travers leur theatre. Deux visions principales semblent caracteriser leurs oeuvres : pessimisme et optimisme. Le pessimisme ressort de l' evolution des faits sociaux et de la peinture des moeurs contemporaines. D'ou une satire de moeurs et mentalite. En revanche, l'optimisme s'affiche dans leur vision de l'avenir. Face a l' etat d anomie qui domine actuellement leur societe, ils lancent un appel a leurs compatriotes afin qu' ils conjuguent leurs efforts pour la reconstruction du pays. Tandis qie osofisan propose a son public une nouvelle societe de modele socialiste, fondee sur le recours a la raison, a l' esprit scientifique et a la philosophe du travail, excluant les croyances traditionnelles, zinsou preconise le retour aux sources et la rehabilitation de la culture traditionnelle togolaiseBetween theatre and society eexist a dialectic relationship. The theatre gets its material from the society and sends back messages to the society. Our present aim is to make a comparative study of the image of the society in the plays of two african contemporary playwrights : femi osofisan, nigerian and s. A. Zinsou, togolese. Comparison that will enable us to point out the analogy and the dissimilarity in their visions and aldo in the way they try and use theatre to solve some current social issues. Their plays seem mainly caracterised by two antithetical visions : pessimim and optimism. Their evocation of social reality and their picture of contemporary norms ans conventions is couched in pesssimistic tones. On the other hand, optimism appears in their projection towards the future. They appeal to their compatriots to rally together to build their nation. Osofisan proposes a socialist system. Zinsou recommends the re-establishment of a traditional social set up
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Ma, Chi-kin Patrick, and 馬志堅. "The death of Yue Fei (1103-1142)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31952239.
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DUARTE, C. N. B. "Processos Identitários e Saúde Reprodutiva: Estudos com Um Grupo de Doulas." Universidade Federal do Espírito Santo, 2016. http://repositorio.ufes.br/handle/10/3118.
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tese_8336_Duarte, Camila Nogueira Bonfim - Dissertação versão digital.pdf: 809018 bytes, checksum: 2607f2465617864e77029e4a50f63245 (MD5)
Previous issue date: 2016-02-22Tendo em vista a importância do apoio oferecido às mulheres pelas doulas, e sua crescente atuação no cenário mundial e brasileiro a pesquisa relatada nesta dissertação buscou investigar processos identitários de um grupo de doulas que atua em conjunto, tendo como base a Teoria da Identidade Social. Para isso foram realizados dois estudos com um grupo de cinco doulas, com nome fictício Bem Nascer, atuante em uma cidade do estado do Espírito Santo. Elas concordaram, voluntariamente, em participar desta pesquisa. Os dois estudos são apresentados em formato de artigo para apresentar os resultados e discussões de forma estruturada. O primeiro artigo apresenta os resultados obtidos através de observação participante, realizada em dez encontros mensais sobre gestação e parto, promovidos pelo grupo Bem Nascer junto a gestantes. Foi produzido um diário de campo, cujos dados são analisados a partir do método hermenêutico-dialético (Minayo, 1992). Foram identificadas três categorias: 1) Descrição dos encontros; 2) Cenas de interações com o endogrupo; 3) Cenas de interações com exogrupos. Observou-se que as doulas, nas interações com as gestantes, exerciam papeis tais como: amigas; instrutoras-esclarecedoras; profissionais; militantes feministas; e que valorizavam homens pró-parto e médicos humanizados em detrimento de homens tradicionais e médicos tecnocratas. Infere-se que essa valorização ocorre por categorização cruzada. Verificou-se que as contribuições das doulas para a saúde reprodutiva eram condizentes com diretrizes do sistema público de saúde brasileiro e que elas disseminavam ideais feministas para mulheres de classe média. O segundo artigo utiliza entrevistas individuais semiestruturadas, analisadas através da análise de conteúdo temática (Bardin, 1977), que permitiu identificar 134 temas e seis categorias. Os processos identitários das doulas estão ligados à militância feminista, ao movimento de humanização do parto, e ao pertencimento a um grupo de trabalho que constitui laços profissionais, de amizade e confiança. Há atitudes negativas quanto à maioria dos profissionais de medicina, com exceção daqueles percebidos como humanizados. Observa-se que doulas estão construindo processos identitários ligados ao feminismo; e que o ativismo, o grupo de trabalho das doulas e a promoção de encontros com mulheres grávidas constituem estratégias de mudança social, contribuindo para a transformação da assistência à saúde e das relações de gênero. Palavras-chave: cuidado pré-natal; doulas; saúde reprodutiva; atitudes; feminismo; identidade social.
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Izanlou, Afshin. "An Ab Initio Surface Study Of Feti For Hydrogen Storage Applications." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611010/index.pdf.
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In this study, the effect of surface crystallography on hydrogen molecule adsorption properties on FeTi surfaces is presented. Furthermore, the substitutional adsorption of 3d-transition metals on (001), (110) and (111) surfaces of FeTi is studied. Using ab initio pseudopotential methods, the adsorption energies of hydrogen and 3d-transition metals are calculated. In substitutional adsorption of 3d-transition metals, Fe-terminated (111) and Ti-terminated (001) surfaces, are found to express the lowest adsorption energies. The adsorption energy versus adsorbed elements&rsquocurves are very alike for all the surfaces. According to this, going from the left to right of periodic table, the adsorption energies increase first. The maximum energy belongs to Cr, Mn and Fe for all the surfaces. Then a minimum is observed in Co for all the surfaces and after that the energy increases again. Adsorption energies of atomic and molecular hydrogen are calculated on high symmetry sites of surfaces. As a result, top and bridge sites came out to be the most stable positions for molecular and atomic hydrogen adsorption, respectively, for (001) and (111) surfaces in all terminations. In (110) surface
however, 3-fold (Ti-Ti)L-Fe and 3-fold (Ti-Ti)S-Fe hollow sites express the lowest adsorption energies for molecular and atomic hydrogen, respectively. Considering the minimum adsorption energy sites for hydrogen molecule and atom, a path of dissociation of hydrogen molecule on surfaces is represented. After that by fully relaxing the hydrogen molecule on the surface and using CI-NEB method the activation energy for hydrogen dissociation is calculated. So it has been found that on Fe-terminated (111) and FeTi (110) surfaces the dissociation of hydrogen molecule happens without activation energy. Meanwhile, the activation energy for Fe-terminated (001) surface and Ti-terminated (001) surface, is calculated to be 0.178 and 0.190 eV, respectively.
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Bonder, M. J. "Magnetic and structural properties of nitrided Fe and FeTi thin films." Thesis, University of Salford, 2001. http://usir.salford.ac.uk/2087/.
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This thesis investigates the magnetic and structural properties of Fe and Fe$STi1s thin films nitrided using a nitrogen atom source. In this novel technique, the atom source produces an atomic nitrogen beam for which multilayer samples with bilayers of the form Fe/FeN or FeTi/FeTiN were synthesized by varying the thickness of the Fe or FeTi exposed to the nitrogen beam. The samples studied here are all in the as-deposited state. X-Ray reflectivity confirms the presence of a multilayer structure showing sharp multilayer peaks indicative of good quality interfaces. The electron diffraction data shows a variation of nitride phases as the thickness of the Fe layer was varied. Fe2N was present when the bilayer was 7A thick. Increasing the bilayer thickness led to a bilayer consisting of two different nitride phases until the Fe layer was 42A thick and the bilayer consisted of a-Fe and Fe4N. In contrast, when Ti was present the phase was body centred cubic for all but the thinnest bilayers considered in this thesis. The grain structure of the two systems was also quite different. The Fe/FeN grain sizes ranged from 50 to 1000A in diameter as the bilayer was varied. In the FeTi/FeTiN sample set the grain growth was inhibited with no noticeable increase with nitriding. Despite these structural differences the magnetic character of the two series of samples were consistent. The samples ranged from nonferromagnetic to ferromagnetic with the presence of weak perpendicular anisotropy occurring as the bilayer thickness increased. As the bilayer thickness was increased there was an asymptotic approach of the magnetization to the level of the unexposed materials. The presence of the perpendicular anisotropy was maintained for a larger parameter space. In both series the anisotropy is attributed to stress induced by the substrate. Nitriding Fe and FeTi using the aforementioned technique provides a controlled and viable way to alter the magnetic and structural properties.
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OLIVEIRA, Murilo Marinello Assis de. "Propriedades físicas da emissão de FeII em núcleos ativos de galáxias." reponame:Repositório Institucional da UNIFEI, 2015. http://repositorio.unifei.edu.br:8080/xmlui/handle/123456789/185.
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Apresentamos, pela primeira vez, um estudo da emissão de Fe II na região do infravermelho próximo (NIR) em uma amostra de 25 núcleos ativos de galáxias (AGN) com o objetivo de obter informações sobre a física desta emissão, particularmente sobre os mecanismos de excitação e a localização mais provável da sua região de formação. Para a análise da emissão de Fe II foi utilizado o template desenvolvido por Garcia-Rissmann et al. (2012), que foi convoluído em FWHM e escalonado em fluxo para cada objeto da amostra. O template se mostrou eficiente na modelagem e subtração da emissão de Fe II na NIR, particularmente para as região das linhas de 1 μm, sugerindo a existência de um mecanismo de excitação dominante a todos os objetos da amostra. A presença do bump de Fe II em λ9200 foi observada em toda a amostra confirmando a presença do processo de fluorescência de Lyα em AGNs. Foi encontrada uma forte correlação entre a emissão do bump de λ9200, as linhas de 1 μm e a emissão óptica de Fe II, indicando que o processo de fluorescência de Lyα é um mecanismo importante na produção de Fe II em AGNs. Utilizando os resultados acima e os fluxos medidos de Fe II foi estimado um limite inferior para a contribuição do processo de flourescência de Lyα na produção de Fe II no óptico. Os resultados mostram que cerca de 18% dos fótons observados no óptico são produzidos por esse processo. Foram comparados os perfis das linhas de Fe II λ10502, O I λ11287, Ca II λ8664 e Paβ λ12812 a fim de obter informações sobre a região de formação destes íons. Os resultados mostram que as linhas de Fe II, O I e Ca II possuem larguras similares e em média 30% mais estreitas que as Paβ. Isto significa que as três primeiras são formadas em uma mesma região, mais externa à aquela onde é produzida as linhas de Hidrogênio. Supondo que o movimento das nuvens emissoras dessas linhas é virializado, os resultados obtidos neste trabalho mostram que o Fe II (bem como o O I e o Ca II) é produzido em uma região, em média, duas vezes mais distante da fonte central que Paβ. As distâncias encontradas para a regiões emissoras de Fe II variam com grande amplitude: de 8,5 dias-luz para NGC4051 até 198,2 dias-luz para Mrk 509. Os resultados derivados deste estudo ressaltam a importância do estudo do Fe II na NIR para vincular parâmetros fundamentais da física deste íon.
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Patel, Merul. "Magnetotransport in magnetic multilayers : a study of FeNi/Cu/Co trilayers." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/251735.
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Shi, Fei [Verfasser]. "Asymmetric Information and Learning in Games / Fei Shi." Konstanz : Bibliothek der Universität Konstanz, 2010. http://d-nb.info/1017235961/34.
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Bernardi, Nara Saraiva [UNESP]. "Treinamento de cavalos de enduro FEI*: abordagem fisiológica." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/89181.
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bernardi_ns_me_jabo.pdf: 642579 bytes, checksum: d0b78376c5154b3de57f0e9f7b33561c (MD5)O presente estudo avaliou o condicionamento físico de equinos por meio de alterações musculares e metabólicas observadas antes e após treinamento de resistência, correlacionando tais alterações com o desempenho durante uma competição de enduro. Onze equinos da raça Puro Sangue Árabe foram submetidos a dois testes incrementais (TIs) a campo para determinação das concentrações sanguíneas de lactato, e hemogasometria antes e após período de três meses de treinamento em trilha com duas sessões semanais predominantemente ao passo, e uma sessão semanal com predomínio do galope. Antes e após o treinamento também foi realizada avaliação ultrassonográfica do músculo Longissimus dorsi e Gluteus medius e, avaliação histológica e histoquímica do músculo Gluteus medius colhido por biópsia percutânea. Após o término do período de treinamento, os animais realizaram um teste de resistência de 80 km a campo. Foram colhidas amostras de sangue no repouso, durante a competição e no período de recuperação, para realização de análises hematológicas, bioquímicas e hemogasométricas. As variáveis estudadas foram submetidas à Análise de Variância e os valores médios comparados pelo teste Tukey (P<0,05). Foram encontradas diferenças nas concentrações de lactato entre os testes, os valores máximos de lactato no TI1 foram superiores aos encontrados no TI2, esse aumento foi seguido por diminuições nos valores do pH. A área total relativa das fibras musculares do tipo IIX aumentou em detrimento das fibras do tipo I. Durante o enduro de 80 km, os cavalos apresentaram quadro de alcalose metabólica mista, por meio do desenvolvimento de alcalose metabólica hipoclorêmica e alcalose respiratória. Baixas concentrações sanguíneas de lactato demonstraram predomínio do metabolismo aeróbico durante...
The purpose of the present study was to assess the physical conditioning of horses through muscle and metabolic variables evaluated before and after one resistance training program, as well as correlate these findings with performance during an endurance competition. Eleven Arabian horses performed two incremental exercise tests (IETs) in the field for determination of blood lactate and blood gases. The tests were carried out before and after a training program of 3 months duration, consisted by two weekly sessions on track predominantly walking, and one weekly session with a predominance of canter. After the end of training and the second IET, the horses participated of an 80 km endurance test (FEI*). Blood samples were collected during competition and at recovery phase to analyze hematological, biochemical and blood gases. Ultrasonographic measurements of the Longissimus dorsi and muscles were also harvested before and after training. Furthermore, muscular tissue was obtained from Gluteus medius through percutaneous biopsy for microscopic and histochemical analysis. The variables were subjected to ANOVA and mean values compared by Tukey test (p<0.05). Maximal lactate values increased during the second IET comparing to the first IET, and this increasing was followed by decreased values of pH. The total relative area of type IIX muscular fibers increased over type I fibers. Ultrasound did not show differences. During the 80 km endurance, horses showed a mixed alkalosis, through development of hypochloremic metabolic alkalosis and respiratory alkalosis. A predominance of aerobic metabolism throughout the track was detected via lactate analysis, as expected for this modality. It was suggested that muscle and metabolic changes observed before and after training were possibly related to each other, demonstrating... (Complete abstract click electronic access below)
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Bernardi, Nara Saraiva. "Treinamento de cavalos de enduro FEI* : abordagem fisiológica /." Jaboticabal, 2013. http://hdl.handle.net/11449/89181.
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Orientador: José Corrêa de Lacerda NetoCoorientador: Lina Maria Wehrle Gomide
Banca: Guilherme de Camargo Ferraz
Banca: Marcos Jun Watanabe
Resumo: O presente estudo avaliou o condicionamento físico de equinos por meio de alterações musculares e metabólicas observadas antes e após treinamento de resistência, correlacionando tais alterações com o desempenho durante uma competição de enduro. Onze equinos da raça Puro Sangue Árabe foram submetidos a dois testes incrementais (TIs) a campo para determinação das concentrações sanguíneas de lactato, e hemogasometria antes e após período de três meses de treinamento em trilha com duas sessões semanais predominantemente ao passo, e uma sessão semanal com predomínio do galope. Antes e após o treinamento também foi realizada avaliação ultrassonográfica do músculo Longissimus dorsi e Gluteus medius e, avaliação histológica e histoquímica do músculo Gluteus medius colhido por biópsia percutânea. Após o término do período de treinamento, os animais realizaram um teste de resistência de 80 km a campo. Foram colhidas amostras de sangue no repouso, durante a competição e no período de recuperação, para realização de análises hematológicas, bioquímicas e hemogasométricas. As variáveis estudadas foram submetidas à Análise de Variância e os valores médios comparados pelo teste Tukey (P<0,05). Foram encontradas diferenças nas concentrações de lactato entre os testes, os valores máximos de lactato no TI1 foram superiores aos encontrados no TI2, esse aumento foi seguido por diminuições nos valores do pH. A área total relativa das fibras musculares do tipo IIX aumentou em detrimento das fibras do tipo I. Durante o enduro de 80 km, os cavalos apresentaram quadro de alcalose metabólica mista, por meio do desenvolvimento de alcalose metabólica hipoclorêmica e alcalose respiratória. Baixas concentrações sanguíneas de lactato demonstraram predomínio do metabolismo aeróbico durante... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The purpose of the present study was to assess the physical conditioning of horses through muscle and metabolic variables evaluated before and after one resistance training program, as well as correlate these findings with performance during an endurance competition. Eleven Arabian horses performed two incremental exercise tests (IETs) in the field for determination of blood lactate and blood gases. The tests were carried out before and after a training program of 3 months duration, consisted by two weekly sessions on track predominantly walking, and one weekly session with a predominance of canter. After the end of training and the second IET, the horses participated of an 80 km endurance test (FEI*). Blood samples were collected during competition and at recovery phase to analyze hematological, biochemical and blood gases. Ultrasonographic measurements of the Longissimus dorsi and muscles were also harvested before and after training. Furthermore, muscular tissue was obtained from Gluteus medius through percutaneous biopsy for microscopic and histochemical analysis. The variables were subjected to ANOVA and mean values compared by Tukey test (p<0.05). Maximal lactate values increased during the second IET comparing to the first IET, and this increasing was followed by decreased values of pH. The total relative area of type IIX muscular fibers increased over type I fibers. Ultrasound did not show differences. During the 80 km endurance, horses showed a mixed alkalosis, through development of hypochloremic metabolic alkalosis and respiratory alkalosis. A predominance of aerobic metabolism throughout the track was detected via lactate analysis, as expected for this modality. It was suggested that muscle and metabolic changes observed before and after training were possibly related to each other, demonstrating... (Complete abstract click electronic access below)
Mestre
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Voznyuk, Ivan. "Méthodes de décomposition de domaines pour la modélisaton électromagnétique et l'imagerie micro-onde quantitative dans des configurations tridimensionnelles de grande taille." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4732/document.
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Cette thèse porte sur la modélisation des ondes électromagnétiques en milieu complexe et à haute fréquence. Ceci reste un défi, de part les besoins en temps de calcul et en place mémoire que cela suscite. L'idée de la méthode Finite Element Tearing and Interconnect (FETI) est de diviser le domaine en sous-domaines distincts dans lesquels des problèmes électromagnétiques peuvent être résolus de manière indépendante. Une modification de la méthode classique, appelée FETI-DPEM2-full, est ici proposée afin d'améliorer le processus numérique. Les champs diffractés par différents objets ont ainsi été simulés et comparés avec succès à des champs expérimentaux. A partir de ces champs, les techniques d'imagerie micro-onde permettent de déterminer les paramètres électromagnétiques des objets illuminés. Ce problème inverse peut être réécrit sous la forme d'un problème d'optimisation faisant appel à la résolution de deux problèmes directs à chaque itération. Une méthode de type quasi-Newton a donc été couplée efficacement avec la méthode FETI-DPEM2-full. Des reconstructions obtenues à partir de champs mesurés sont présentées et valident la chaîne méthodologique proposéeThis PhD work is devoted to the electromagnetic modeling of threedimensional large-scale wave propagation problems, which is very challenging in terms of memory and computation time. The main idea of the Finite Element Tearing and Interconnect (FETI) method is to divide the domain into non-overlapping subdomains where each electromagnetic problem can be independently solved. A modification of the classical FETI method, called the FETI-DPEM2-full method, is proposed herein to improve the numerical process. The fields scattered by various structures have thus been computed and successfully compared with measured fields. From these experiments, quantitative microwave imaging algorithms attempt to estimate the physical parameters of the illuminated target. This inverse problem is recasted into a minimization problem where two forward problems are required at each iteration step. A quasi-Newton algorithm has thus been efficiently coupled with the FETI-DPEM2-full method. Reconstructions of various targets from measured scattered fields have been successfully performed, which validates the effectiveness of the proposed methodology
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Chui, Mai-hing. "A study of the Ming and Qing historical novels related to Yue Fei Yi Yue Fei wei ti cai de Ming Qing yan yi yan jiu /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record/B38803835.
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Walther, Feli Mascha [Verfasser]. "Untersuchungen zur Eisenspeicherung in Mammalymphknoten des Hundes / eingereicht von Feli Mascha Walther." Giessen : VVB Laufersweiler, 2009. http://d-nb.info/1000345408/34.
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Lefebvre, Josianne. "Peak effect, hall effect and vortex phases in FexNi₁-xZr₂ superconducting glasses." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81354.
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The mixed state of type II superconductors is an ideal medium for the study of correlated systems since the density of vortices which penetrate the sample, as well as the driving force, can be tuned such as to measure their effects on correlations. The weak pinning character of the Fe xNi1-xZr2 metal glasses permits vortex phases to be probed by dissipative transport (longitudinal and Hall) measurements. The complete phase diagram in this regime is mapped out as a function of magnetic field, driving current and temperature using results from longitudinal resistance measurements. The longitudinal measurements show a huge peak effect with a driving force induced pinning phase known to arise from a disordering transition. The Hall resistance measurements lead to remarkable new results: a critical angle dependence of the vortex flow direction when entering or leaving the disordered phase is revealed, which suggests the existence of orientational phase transitions.
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Koçdemir, Bora. "Thermisches Ausdehnungsverhalten von MoCu-, WCu-Werkstoffen und FeNi-Schichten für mikrosystemtechnische Anwendungen." Aachen Shaker, 2007. http://d-nb.info/988749548/04.
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Pérez, Margarita. "Phytochemische und pharmakologische Untersuchung von Qualea multiflora Mart. und Polypodium feei Meet. /." [S.l. : s.n.], 1997. http://www.gbv.de/dms/bs/toc/250653869.pdf.
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Pittioni, Eugenio <1975>. "Indagine istopatologica ed immunoistochimica su feti bovini abortiti in Friuli Venezia Giulia." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/128/.
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Gallas, Marcia Russman. "Efeito de altas pressões, temperatura e bombardeamento iônico em ligas invar FeNi." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1992. http://hdl.handle.net/10183/29706.
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Neste trabalho foi estudado o efeito de altas pressões, temperatura e bombardeamento de íons em ligas Invar FeNi. Analisamos os resultados destes diferentes tratamentos, principalmente através das técnicas de Efeito Mõssbauer por transmissão e por elétrons de conversão, medidas de temperatura de Curie e difração de raio-X. A investigação com pressões de até 10 GPa, para diferentes concentrações da liga FeNi, mostrou que a pressão não favorece a ordenação e separação de fases. No estudo da temperatura de Curie de ligas com concentração em torno de 30 at.% de Ni, como função do tempo de recozimento para diferentes temperaturas, observamos um aumento em Tc de mais de 20°C, em temperaturas da ordem de 340°C. A variação de T c com o tempo foi similar à observada em ligas amorfas, sendo interpretada como um rearranjo atômico, numa escala muito pequena. A energia de ativação para o processo foi estimada em torno de 1.5 eV, indicando o movimento de vacâncias congeladas como o principal mecanismo de relaxação. No estudo dos efeitos de bombardeamento com íons de Ar, Ne e Kr, para diferentes doses e temperaturas, em ligas com concentrações em torno de 30 e 40 at.% de Ni, observamos uma separação de fases, para as amostras bombardeadas com Ne e Ar, mas nenhuma evidência de ordenação, como ocorre em amostras irradiadas com elétrons e neutrons. Para o bombardeamento com Kr, não observamos nenhuma mudança, exceto para as amostras que já apresentavam separação de fases, as quais voltaram a seu estado inicial de fase única. Estes resultados indicam que existe uma predominância de mistura para bombardeamento com íons pesados, e de difusão auxiliada por irradiação para íons leves.We studied in this work the effect of high pressure, temperature and ion bombardment in FeNi Invar alloys. The results of the different treatments were analysed mainly, by Transmission MOssbauer Spectroscopy, Conversion Electron MOssbauer Spectroscopy, measurements of Curie temperature and X-Ray diffraction. The pressure investigation until 10 GPa, for different concentrations of the FeNi alloy, showed that pressure does not favour ordering and phase separation. The study of Curie temperature of alloys near 30 at.% de Ni, as a function of the annealing time at different temperatures showed an increase in Tc of more than 20°C, with annealing at temperatures as low as 340°C. The change in Tc with time was similar to that observed in amorphous alloys, and was interpreted as an atomic rearrangement, in a very small scale. The activation energy for the process was estimated to be about 1.5 eV, indicating movement of quenched-in vacancies as the main relaxation mechanism. The study of the effect of ion bombardment at different doses and temperature, with Ar, Ne and Kr, in FeNi alloys with 30 e 40 at.% de Ni, indicated a phase separation, for samples bombarded with Ne and Ar, but no evidence of ordering, as in samples irradiated with electrons and neutrons. For bombardment with Kr, we didn't observe any change, but samples already showing a phase separation, returned to the single phase state. Our results give evidences of prevalence of mixing for bombardment with heavy ions, and of radiation enhanced diffusion for bombardment with lighter ions.
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Messal, Oualid. "Caractérisation et modélisation du comportement thermomagnétique d'alliages FeNi pour le prototypage virtuel." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10304/document.
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L’avènement du Génie électrique, il y a plus d’un siècle maintenant, s’est accompagné dès ses débuts, de recherche de matériaux ferromagnétiques performants pour la réalisation de l’élément central des dispositifs électromagnétiques, le circuit ou noyau magnétique. Ces matériaux, constitués initialement de fer, ont été très vite alliés au silicium, au cobalt et au nickel pour plusd’efficacité énergétique. Pour un dispositif donné, le choix d’un tel ou tel matériau passe souvent par un exercice de compromis vis-à-vis des besoins applicatifs (performances magnétiques, caractéristiques mécaniques et thermiques, etc., et bien sûr coût). La fréquence et la température de fonctionnement sont entre autres des paramètres importants. Parmi ces matériaux, les FeNi, bien qu’ils soient matures industriellement, voient toujours de nouveaux marchés s’ouvrirent à eux année après année grâce à l’attrait technique qu’ils exercent. Ce travail s'inscrit dans la continuité des recherches engagées à AMPERE sur les modèles comportementaux de matériaux magnétiques avec prise en compte des effets de la température. En effet, la recherche permanente de performances et de compacité ou intégration pour tous les dispositifs électromagnétiques soumet les circuits magnétiques à des contraintes physiques et en particulier thermiques de plus en plus sévères. Il est donc nécessaire de caractériser et modéliserprécisément les matériaux ferromagnétiques, et plus particulièrement les alliages FeNi, afin de les intégrer dans les outils de conception et d’optimisation de ces dispositifs. Pour cela, nous avons notamment dû mettre en oeuvre un dispositif expérimental adapté, et réaliser de nombreuses et longues expérimentations afin d’élaborer des modèles performants de comportement de ces matériaux. Ces modèles étudiés ou/et développés ont été ensuite testés sur une démonstrateur réel. Dans le cadre de cette thèse qui s’est déroulée en collaboration avec le Centre de Recherche du groupe APERAM, nous avons choisi une application particulièrement sensible en matière de sécurité des personnes « le système de protection différentielle » où le circuit magnétique (en alliage Fe–50%Ni ou Supra50) constitue une part très importante des performances et de la fiabilité. Enfin, de nouveaux alliages FeNi(Cr, Cu) à faible teneur en Ni (donc économiques) issus du Centre de Recherche d’APERAM ont été étudiés en vue de tester leur aptitude à remplacer le Supra50 dans ces systèmes. Le but est au final de proposer des alliages FeNi économiques aptesà la fabrication du circuit magnétique des relais de disjoncteurs différentiels à propre courantThe advent of Electrical Engineering has been accompanied since its beginning, by the research of high performance ferromagnetic materials for the realization of the central element of electromagnetic devices, the magnetic core/circuit. These materials initially consisting of iron were alloyed with silicon, cobalt and nickel for more energy efficiency. For a given device, the material must be designed to meet the requirements of the application (magnetic performances, mechanical and thermal characteristics...and cost. The frequency and the operating temperature are, among others, important parameters to be taken into account. Among these materials, the FeNi alloys, although they are industrially mature, see new markets opened to them thanks to their certain specific characteristics and the innovations brought by the manufacturers of these materials. This work is a continuation of ongoing researches in AMPERE laboratory dealing with thebehavioral models of magnetic materials taking into account the effects of temperature. Indeed, there is a trend in a growing number of electromagnetic devices to require high performance and compactness or integration. Thus, in this context, the magnetic circuits are subjected to physical and thermal stresses that are becoming more and more stringent. It is therefore necessary to resort to the experimental characterization and modeling of the behavior of ferromagnetic materials, particularly the FeNi alloys, in order to integrate them into the design and optimization tools of these devices. To do so, we have implemented an appropriate experimental bench, andachieve many and long experiments to develop advanced behavioral models of these materials. These models were then tested on a particularly sensitive application in the field of safety of persons, the differential protection system where the magnetic circuit (of Fe-50% Ni or Supra50) is a very important part of performance and reliability. Finally, new low Ni content FeNi (Cr, Cu) alloys provided by Aperam Research Center in Imphy, were studied in order to test their ability to replace the usual Supra50 alloy in these systems. The final aim is to propose new economic FeNi alloys suitable for the manufacture of the magnetic circuit of industrial ground fault circuit-breaker relay
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Luk, Yu-shing, and 陸汝誠. "A study of Yue Fei studies since late Qing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31950838.
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Kudo, Akemi. "Mr Maybe : Fei Ming as a pastoral fiction writer." Thesis, SOAS, University of London, 1993. http://eprints.soas.ac.uk/29565/.
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This thesis deals with Fei Ming (the pen-name of Feng Wenbing, 1901-1967), a writer who was active mainly in the 1920s and 1930s and who has been disregarded since 1949 until only recently. Fei Ming's works include stories, essays and poems, and this thesis concentrates on his pastoral stories written between 1923 and 1932. The aim of this thesis is threefold. First, it attempts to illuminate the individuality of Fei Ming's pastoral stories by analysing their thematic and stylistic characteristics. The second objective is to examine the influence of foreign modern pastoral stories and Chinese traditional pastoral works on Fei Ming. The third is to outline the changes in his pastoral fiction writing. In so doing, I hope this thesis will invite a fresh look at this writer who is barely mentioned in China, Japan and the West, and has never been made the subject of a systematic critical study. The thesis consists of seven chapters: Chapter One describes the literary life of Fei Ming. Chapter Two introduces an outline of Fei Ming's creative writings. Chapter Three discusses the thematic characteristics of his stories about the countryside in Southern China. Chapter Four investigates the pastoral elements in his stories. The term, 'pastoral' is defined, and the argument on influences on Fei Ming's work is developed. Chapter Five analyzes the stylistic characteristics of his pastoral stories. Chapter Six explores the novel. The Life of Mr Maybe, which I define as 'mock-pastoral'. Chapter Seven examines the serial published in 1947-1948, "After Mr Maybe Flew in an Aeroplane" to see how Fei Ming's views of country life changed after 1932. The conclusion discusses Fei Ming's influence on Chinese writers from the late 1920s onwards and sums up Fei Ming's achievements as a fiction writer.
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Zvařič, Filip. "Přenosová technologie G.fast." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-376968.
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This diploma thesis focuses on G.fast and VDSL2 technologies and their comparison. G.fast has the prerequisites for replacing VDSL2 for short distances. This work describes in detail the modulation techniques of both DSL technologies - DMT modulation used by both technologies. The aim of this work is to create a software for comparing the transfer rates of all profiles of both technologies, including the effects of far-end crosstalk. This is performed in the Matlab environment. This work describes how the program works and how to run the simulations. The results of selected simulations and their charts are enclosed in this work.
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Thabethe, Sibongiseni Stanley. "Growth and characterization of FeSi nanowires by chemical vapor deposition for gas sensing applications." Thesis, University of the Western Cape, 2014. http://hdl.handle.net/11394/4239.
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>Magister Scientiae - MScFeSi nanowires were synthesized via a chemical vapor deposition method. Anhydrous FeCl3 powder in this case served as the Fe source and was evaporated at a temperature of 1100oC to interact with silicon substrates which served as the silicon source. The nanowires followed the vapor solid (VS) growth mechanism, which does not require the use of a metal catalyst; the native silicon oxide layer on the silicon substrates played the role of the catalyst in the growth of these nanostructures. A second growth mechanism, involving the use of a metal catalyst to assist in the growth of the nanowires was attempted by depositing a thin film of gold on silicon substrates. The reaction yielded SiOx nanowires; these results are discussed in detail in Chapter 5. All the nanostructures were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Photoluminescence Spectroscopy (PL), Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR).
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Blixt, Anna Maria. "Growth and Magnetic Properties of Fe- and FeNi-based Thin Films and Multilayers." Doctoral thesis, Uppsala University, Department of Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3940.
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This thesis concerns the growth and magnetic properties of thin films and multilayers. The samples were grown by magnetron sputtering, and characterized structurally mainly by x-ray diffraction and reflectivity. The magnetic characterization of the multilayers was done by magneto-optical Kerr technique, SQUID magnetometry and, in two samples, by neutron reflectometry.
Arrays of small elements of polycrystalline permalloy (FeNi alloy with 19 wt% Fe) are of interest as a component in non-volatile magnetic random access memories (MRAM). Here the shape dependence of the domain structure in such elements was studied by magnetic force microscopy (MFM) and in thin ring magnets the 'onion' state could be seen for the first time. Also, by post-annealing in hydrogen atmosphere the number of domains decreased in each element due to enhanced relaxation and defect reduction.
Furthermore, permalloy-based anisotropic magnetoresistance (AMR) in read heads are nowadays replaced by material combinations that have a giant magnetoresistance (GMR) effect. In this work Fe/V(001) and Fe0.82Ni0.18/V(001) superlattices, i.e. single-crystal-like multilayers, were investigated. These systems showed much smaller GMR effect compared to the Fe/Cr system. However, by introducing Ni into the Fe layers the magnetic anisotropy and the interlayer exchange coupling (IEC) decreased, thereby increasing the sensitivity, which is a key property for a magnetic sensor. The interface region showed a reduced magnetic moment, and the influence of the structural quality was modelled and investigated theoretically in the Fe0.82Ni0.18/V case. Also, in the Fe(2-3 ML)/V(x ML) superlattices (ML=monolayers) the transition temperature from long-range magnetic order to paramagnetic order oscillated with the V layer thickness (x) as a result of the oscillatory behaviour of the IEC.
The introduction of hydrogen in the non-magnetic layers of, for example, Fe/V(001) superlattices is a way to tune the IEC strength. Here the tuning was used as a tool to study the magnetic order in a low-dimensional magnet. At the critical hydrogen concentration
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Assuming-Gyimah, Kofi Tutu Addo. "Time domain studies of training effects in Co/Cu/FeNi/FeMn spin valves." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13267.
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The recovery and the relaxation behaviors of the exchange bias (HE) in a Co/Cu/FeNi/FeMnspin valve has been studied via point contact technique with high field scan rates ranging from 1050 to 13500 Oe/s. The evolution of the exchange bias with the number of field cycles(n) shows a one over the square root of (n) dependence as against ln(n) in a previous study. A recovery of the exchange bias when the field cycling is stopped has been observed and the recovery ratio (R) is found to be a function of the logarithm of the recovery time (log(t)) in agreement with previous studies. The relaxation time of the exchange bias is estimated to be 6.62, 20.85, 43.10, 109.02, and 297.24 s for 13500, 5400, 2700, 1350, and 1050 Oe/s respectively. The one over the square root of (n) dependence of HE and the log (t) dependence of R have been discussed using thermal activation model.
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Graells, Castellà Simó. "Creixement de nanoestructures plamòniques mitjançant la deposició induïda per un feix d'electrons focalitzat." Doctoral thesis, Universitat Ramon Llull, 2009. http://hdl.handle.net/10803/9143.
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L'enginyeria de les propietats plasmòniques de les nanoestructures metàl·liques requereix un control acurat de les seves formes i distribució. Això normalment s'aconsegueix amb l'ús de la litografia per feix d'electrons sobre polímers electro-sensibles combinat amb la deposició de capes fines de metall i el lift-off. La deposició directa i localitzada de metalls induïda per un feix d'electrons (FEBID per Focused Electron Beam Induced Deposition) és un mètode alternatiu querecentment ha rebut un interès creixent en microelectrònica però encara no ha despertat massa atenció dins la comunitat d'òptica. L'FEBID és el resultat de la descomposició local, per un feix
d'electrons focalitzat, de les molècules d'un precursor adsorbides sobre una superfície. Aquesta s'ha aplicat majoritàriament en la escriptura directa de contactes o per a la reparació de circuits, però amb l'ús de metalls nobles podria aprofitar-se per a l'òptica de plasmons.
En aquesta tesi es demostra l'ús de l'FEBID per a fabricar nanoestructures d'or per a aplicacions d'òptica de plasmons. S'investiguen els efectes del material del substrat i dels paràmetres de deposició, com ara el corrent del feix i la pressió de vapor d'aigua, sobre el ritme de creixement i la puresa de l'or. S'ha emprat un recuit ex situ de la mostra com a mètode de millora de la puresa. Les mesures òptiques de dispersió sobre les estructures purificades evidencien que suporten plasmons de superfície localitzats. Aquest mètode de fabricació permet el creixement d'estructures plasmòniques amb una elevada relació d'aspecte i ha de facilitar l'escriptura en superfícies no planes com l'extremitat d'una sonda de rastreig allargada.
La ingeniería de las propiedades plasmónicas de las nanoestructuras metálicas requiere un control preciso de sus formas y distribución. Esto normalmente se consigue con el uso de la litografía por haz de electrones sobre polímeros electro-sensibles combinado con la deposición de capas finas de metal y el lift-off. La deposición directa y localizada de metales inducida por un haz de electrones (FEBID por Focused Electron Beam Induced Deposition) es un método alternativo que recientemente ha despertado un interés creciente en microelectrónica pero todavía no ha recibido demasiada atención dentro de la comunidad de óptica. La FEBID es el resultado de la descomposición local, por un haz de electrones focalizado, de las moléculas de un precursor adsorbidas sobre una superficie. Esta se ha aplicado mayoritariamente en la escritura directa de contactos o para la reparación de circuitos, pero con el uso de metales nobles podría ser aprovechada para la óptica de plasmones.
En esta tesis se demuestra el uso de la FEBID para fabricar nanoestructuras de oro para aplicaciones de óptica de plasmones. Se investigan los efectos del material del sustrato y de los parámetros de deposición, como la corriente del haz y la presión de vapor de agua, sobre el ritmo de crecimiento y la pureza del oro. Se ha utilizado un recocido ex situ de la muestra
como método de mejora de la pureza. Las medidas ópticas de dispersión sobre las estructuras purificadas evidencian que soportan plasmones de superficie localizados. Este método de fabricación permite el crecimiento de estructuras plasmónicas con una elevada relación de aspecto y tiene que facilitar la escritura en superficies no planas como la extremidad de una sonda de rastreo alargada.
Engineering the plasmon properties of metal nanostructures requires an accurate control on their shapes and distribution. This is conventionally achieved by using electron-beam lithography on electro-sensitive polymers combined with thin-metal-film deposition and lift-off. Direct local deposition of metals induced by a focused electron beam (FEBID for Focused Electron
Beam Induced Deposition) is an alternative method that has been receiving a growing interest in microelectronics but it has not yet received much attention in the optical community. The FEBID is the result of the local decomposition, by a focused electron beam, of precursor molecules adsorbed on a surface. It has mostly been applied to direct-contact writing or to circuit reparation, but can be applied advantageously to plasmon optics when involving noble metals.
In this thesis the use of the FEBID to fabricate gold nanostructures for plasmon optics applications is demonstrated. The effects of the substrate material and the deposition parameters, such as beam current and water vapor pressure, on both the deposition rate and the gold purity are investigated. Ex-situ annealing of the sample is used as a purity improvement method. Scattering optical measurements on the purified structures evidence that they support localized surface plasmon resonances. This fabrication method enables to grow high aspect ratio plasmonic structures and to render much easier nano-patterning on non-flat surfaces such as the extremity of an elongated scanning probe.
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Sansa, Myriam. "Modélisation de la ségrégation superficielle dans les aciers FeNi par des approches atomistiques." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0542/document.
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Le vieillissement des aciers est un problème crucial dans bien des industries (automobile, nucléaire) puisqu’il détermine la durée de vie des éléments. En effet, la ségrégation aux défauts du matériau d'éléments tels que le carbone, ou les additifs métalliques (nickel, chrome), modifie fortement ses propriétés mécaniques d'une part, et sa résistance à la corrosion d'autre part. Modéliser de tels phénomènes n'est pas chose simple. Jusqu'ici, le choix des méthodes utilisées s'est partagé entre des calculs dits "de premiers principes", basés sur la Théorie de la Fonctionnelle de la Densité, trop lourds pour rendre compte de matériaux réalistes, et des méthodes basées sur des potentiels semi-empiriques difficilement transférables d'un système à l'autre. Dans ce travail de thèse, nous avons développé une approche effective de la structure électronique originale, fondée sur l'approximation des Liaisons Fortes, pour décrire les aciers Fer-Nickel. Nous avons dû pour cela identifier les règles d’auto-cohérence auxquelles doivent obéir les charges électroniques et les populations de spin : neutralité locale pour les premières, variation en concentration du moment magnétique pour les secondes Cette méthodologie nous a permis de mettre en évidence le rôle essentiel joué par le magnétisme dans les phénomènes d’ordre-désordre en volume, et de ségrégation d’équilibre en surface, première étape vers une modélisation cinétique du vieillissement de ces aciersThe aging of steel is a crucial problem in many industries (automobile, nuclear) since it determines the lifetime of the elements. Indeed, the segregation at material defects of elements such as carbon, or metal additives (nickel, chromium), strongly modifies its mechanical properties and its resistance to corrosion. Modelling such phenomena is not simple. So far, the choice of methods used has been divided into "first principles" calculations, based on the Densitu Functional Theory, too heavy to account for realistic materials, and methods based on semi-empirical potentials that are difficult to transfer from one system to another. In this thesis, we have developed an original effective approach of the electronic structure, based on Tight-Binding approximation, to describe the iron-nickel steels. To do this, we had to identify the self-consistency rules that electronic charges and spin populations must obey: local neutrality for the former, concentration dependence of the magnetic moment for the latter. This methodology allowed us to highlight the essential role played by magnetism in order-disorder phenomena in the bulk, and in equilibrium segregation at the surface, which is the first step towards a kinetic modelling of the aging of these steels
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Rouve, Laure-Line. "Prise en compte du comportement magnétique fréquentiel des tôles FeSi en modélisation électrotechnique." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0027.
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La bonne description du flux magnétique à travers les tôles magnétiques Fesi couramment utilisées en électrotechnique nécessite la prise en compte de l'hystérésis et des courants induits qui se développent dans l'épaisseur des tôles avec la fréquence. Le calcul des grandeurs magnétiques dans la section des tôles par résolution numérique de l'équation de la diffusion montre qu'un modèle de Preisach dynamique donne une bonne représentation du comportement magnétique local. Ce modèle permet en effet de décrire le comportement systématique du matériau ainsi que l'effet d'amortissement des courants induits sur le mouvement des parois. Grâce et ce modèle, l'induction moyenne sur la section et les pertes dissipées dans la tôle sont approchées de façon très satisfaisante gour un champ en surface sinusoïdal et des fréquences supérieures à la fréquence de travail habituelle des tôles. Pour les mêmes conditions de travail, une méthode est proposée pour résoudre analytiquement l'équation de la diffusion magnétique. Cette méthode repose sur l'utilisation du modèle de Preisach dynamique et des hypothèses simplificatrices concernant les variations de perméabilité différentielle dans le temps et l'espace dues à l'hystérésis. Elle donne des résultats très proches de ceux de la méthode numérique. Ainsi, ce travail présente-t'il les bacs d'un modèle reliant l'induction moyenne sur la section d'une tôle au champ appliqué en surface. Ce modèle, supposé scalaire (induction et champ colinéaires), permet également d'approcher les pertes dans les structures électrotechniques
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Le, Thanh Vinh. "Hétéroépitaxie du disiliciure semiconducteur de fer, beta-fesI#2, sur substrat silicum(111)." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX22014.
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Cette these presente une etude systematique de la croissance epitaxiale de beta-fesi#2 sur silicium(111) par jet moleculaire (mbe). Deux techniques de croissance epitaxiales ont ete exploitees: solid phase epitaxy (spe) et reactive deposition epitaxy (rde). Les caracterisations in situ ont ete effectuees par rheed, xps, ups, auxquelles sont associees des mesures ex-situ de diffraction des rayons x, microscopie electronique a transmission, microprofilometre auger. Les resultats obtenus ont montre que l'epaisseur initiale de fer depose est un parametre tres sensible a la cinetique de croissance et a la morphologie du film de beta-fesi#2. Outre la confirmation des relations d'epitaxie de beta-fesi#2 sur silicium, nous avons revele l'existence d'une phase hors d'equilibre de fesi#2 epitaxiee et contrainte sur la face (111) du silicium. Contrairement a la phase semiconductrice, orthorhombique beta-fesi#2, cette phase possede des proprietes metalliques et cristalline dans une structure cubique. Le domaine d'existence de cette phase est caracterise par une epaisseur critique et une temperature critique. Au-dela de ces valeurs critiques, cette phase relaxe vers la phase semiconductrice beta-fesi#2. Nous avons aussi montre, pour la premiere fois, deux types de transition de phases differentes: l'une est la transition de la phase contrainte fesi#2 vers le mono-siliciure fesi observee dans la gamme de temperature 300-350c, l'autre est la relation de la phase contrainte fesi#2 a beta-fesi#2 observee dans la gamme 400-450c
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Zhan, Fei [Verfasser], and Peter [Akademischer Betreuer] Hänggi. "Heat Transport in Molecular Junctions / Fei Zhan. Betreuer: Peter Hänggi." Augsburg : Universität Augsburg, 2012. http://d-nb.info/1077700903/34.
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Ho, Chin-jun, and 何金潤. "Magnetic and Thermal Properties of Molecular Magnet [FeII(Δ)FeII(Λ)(ox)2(Phen)2]n." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/q5d9h4.
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碩士國立中山大學
物理學系研究所
95
The molecular magnet [FeII(Δ)FeII(Λ)(ox)2(Phen)2]n, whose chemical formula is C28H16Fe2N4O8 for unity, has been studied by magnetization measurements, neutron diffraction, and field-dependent specific heat. From the magnetization measurements, the quasi-ferrimagnetic behavior at T>Tm region can be well described with alternating Landé factors within 1D Ising chain model. However, in T
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"Phase and microstructure of FeSi₂ thin films." 2006. http://library.cuhk.edu.hk/record=b5892816.
Full textAbstract:
Chong Yuen Tung = 硅化鐵薄膜的相和微觀結構 / 莊宛曈.Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 63-65).
Text in English; abstracts in English and Chinese.
Chong Yuen Tung = Gui hua tie bo mo de xiang he wei guan jie gou / Zhuang Wantong.
Abstract --- p.i
摘要 --- p.ii
Acknowledgment --- p.iii
Table of contents --- p.iv
List of Figures --- p.viii
List of Tables --- p.x
Chapter CHAPTER 1: --- Introduction --- p.1
Chapter CHAPTER 2: --- Background --- p.4
Chapter 2.1 --- Phases of crystalline FeSi2 --- p.4
Chapter 2.2 --- Electronic structure of β-FeSi2 --- p.7
Chapter 2.3 --- Orientation relationship between β-FeSi2 and Si --- p.8
Chapter CHAPTER 3: --- Instrumentation --- p.10
Chapter 3.1 --- Metal vapor vacuum arc ion source implantation --- p.10
Chapter 3.2 --- Rutherford backscattering --- p.12
Chapter 3.3 --- Transmission Electron Microscopy (TEM) --- p.13
Chapter 3.3.1 --- Principles of TEM --- p.13
Chapter 3.3.2 --- Electron specimen interaction and contrast --- p.14
Chapter 3.3.3 --- Electron Diffraction --- p.15
Chapter 3.3.4 --- Sample Preparation --- p.17
Chapter 3.3.4.1 --- Plan-view sample --- p.17
Chapter 3.3.4.2 --- Cross-section sample --- p.17
Chapter CHAPTER 4: --- FeSi2 films fabricated by ion implantation --- p.18
Chapter 4.1 --- Introduction --- p.18
Chapter 4.2 --- Experimental details --- p.18
Chapter 4.3 --- Ion energy series --- p.19
Chapter 4.3.1 --- As-implanted sample --- p.19
Chapter 4.3.1.1 --- Results --- p.20
Chapter 4.3.1.2 --- Discussions --- p.20
Chapter 4.3.2 --- Annealed samples --- p.24
Chapter 4.3.2.1 --- Morphology of the annealed samples and the damage on Si substrate --- p.24
Chapter 4.3.2.2 --- Identification of the FeSi2 phase and their orientation relationship with the Si matrix --- p.24
Chapter 4.3.2.3 --- Photoluminescence of the samples --- p.26
Chapter 4.3.2.4 --- Discussions --- p.26
Chapter 4.4 --- Ion dosage series --- p.31
Chapter 4.4.1 --- Results --- p.31
Chapter 4.4.2 --- Discussions --- p.32
Chapter 4.5 --- Summary --- p.36
Chapter CHAPTER 5: --- Effect of post annealing on the phase and microstructure of FeSi2 --- p.37
Chapter 5.1 --- Introduction --- p.37
Chapter 5.2 --- Experimental details --- p.37
Chapter 5.3 --- The correlation between microstructure of FeSi2 synthesized under different annealing conditions and their PL --- p.38
Chapter 5.3.1 --- RTA series --- p.38
Chapter 5.3.1.1 --- Results --- p.38
Chapter 5.3.1.2 --- Discussions --- p.39
Chapter 5.3.2 --- FA series --- p.42
Chapter 5.3.2.1 --- Results --- p.42
Chapter 5.3.2.2 --- Discussions --- p.44
Chapter 5.3.3 --- RTAFA series --- p.45
Chapter 5.3.3.1 --- Results --- p.45
Chapter 5.3.3.2 --- Discussions --- p.45
Chapter 5.4 --- The existence of alpha phase and its special shape --- p.51
Chapter 5.4.1 --- Results --- p.51
Chapter 5.4.2 --- Discussions --- p.52
Chapter 5.5 --- The existence of gamma phase in 1050°C furnace annealed sample
Chapter 5.5.1 --- Results --- p.56
Chapter 5.5.2 --- Discussions --- p.57
Chapter 5.6 --- Summary --- p.59
Chapter CHAPTER 6: --- Conclusions --- p.61
References --- p.63