Durant cette thèse, nous avons d'abord développé un dispositif expérimental permettant de mesurer la dynamique de l'angle de contact avec une précision record de 0,01° sur 7 décades de vitesses de la ligne triple, gamme jamais atteinte auparavant. Pour la première fois, la résolution numérique des équations de lubrification a permis de déduire l'angle de contact à l'échelle microscopique de ces mesures macroscopiques, découplant donc le problème hydrodynamique multi-échelles de la physique de la ligne de contact à petite échelle. Avec ces outils, nous avons montré qu'une pseudo-brosse - une couche nanométrique de polymères - peut complètement piloter la dynamique, en produisant des hystérésis les plus faibles jamais mesurées (<0,07° !) et des surdissipations massives provenant de la nature visco-élastique de la couche. Cette étude ouvre la voie à la nano-rhéologie, permettant de sonder la dynamique extrêmement rapide (~100 ns) de polymères confinés à l'échelle nanométrique. Grâce à un travail collaboratif fructueux, nous avons ensuite développé un modèle permettant de décrire quantitativement et de façon unifiée la dissipation hydrodynamique, l'hystérésis et l'activation thermique. Enfin, beaucoup d'efforts ont été fournis pour la fabrication de surfaces aux défauts nanométriques contrôlés en taille, forme et concentration. La dynamique s'est révélée insensible à cette échelle de désordre, la présence des défauts n'affectant que l'hystérésis. Ces résultats ont été interprétés semi-quantitativement avec des lois d'échelle, et la caractérisation complète des défauts devrait permettre à terme de développer des modèles plus quantitatifs. / During this thesis, we first developed an experimental set-up to measure contact angle dynamics with a record precision of 0.01° over 7 decades of velocity of the triple line, a range never before attained. For the first time, numerically solving the lubrication equations has allowed us to deduce the contact angle at the microscopic scale from these macroscopic measurements, and thus enabled the multi-scale hydrodynamic problem to be disentangled from the physics of the contact line at small scales. With these tools we have shown that the dynamics can be completely piloted by a pseudo-brush -a nanometric layer of polymers-, producing the lowest ever reported hysteresis (<0.07°!) and giving rise to a huge source of dissipation originating from the viscoelasticity of the coating. This study points the way towards nano-rheology, to probe extremely fast dynamics (~100 ns) of polymers confined at the nano-scale. Thanks to a fruitful collaborative work, we then developed a model that provides a single quantitative framework to account for hydrodynamic dissipation, hysteresis and thermal activation. Finally, a great deal of effort has been made to produce nano-defects whose size, shape and density are controlled. The dynamics appears to be insensitive to this scale of disorder, and the presence of defects is observed to only modify the hysteresis. These results have been interpreted semi-quantitatively with scaling laws, and we expect that the complete characterization of the defects should eventually allow the development of more quantitative models.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / The Exchange Bias (EB) phenomenon consists of an interfacial exchange coupling between a ferromagnetic (FM) material and an antiferromagnetic (AFM) one and has as the main characteristics the rise of a unidirectional anisotropy and a rotational hysteresis (HR) in torque curves. In this work we have investigated the behavior of the magnetic behavior of systems presenting EB through magnetization curves, anisotropic magnetorresistance (AMR)and torque magnetometry. We have grown films, via magnetron sputtering, of NiFe/FeMn (bilayers) with different thickness of the FM layer and film structures of NiFe/IrMn/Ta with different repetitions of the basic s tructure. From the X-ray diffraction and reflectivity we have determined the preferential crystallographic growth direction, the thickness and the grain size of the studied samples. It was implemented at the Magnetism and Magnetic Materials Laboratory (LMMM) an apparatus to measure the AMR in two configurations: resistance as a function of the applied field angle and resistance as function of the field applied in a particular angle direction. To adjust the magnetization and AMR data we have used a phenomenological model for EB considering four energy terms: Zeeman, uniaxial, unidirectional and magnetostatic. The AMR curves have shown an asymmetry around 180º when measured at field smaller than the Bias one. According to the used model used, such asymmetry can be caused either by a misalignment between the anisotropy axes (uniaxial and unidirectional) or by a misalignment between the measurement current direction easy magnetization axis of the sample. It was not observed in the multilayers an increase on the uniaxial anisotropy dispersion with increasing on the trilayers number, as expected. In order to fit average torque curves, we have used an equation with two harmonic terms. The resulting parameters allow us to study the field evolution of the harmonic amplitudes Kθ e K2θ. In the multilayer system as higher total energy is, higher is the energy losses by HR. In bilayers system, the HR energy losses still increases even above the saturation field. Such behavior was associated to the configuration of interfacial spins and suggests the need of an additional contribution to total energy of the magnetic system. / O fenômeno de Exchange Bias (EB) consiste de um acoplamento de troca interfacial entre um material ferromagnético (FM) e um material antiferromagnético (AFM) e tem como características principais o surgimento de uma anisotropia unidirecional e a histerese rotacional (HR) em curvas de torque. Neste trabalho investigamos o comportamento de sistemas magnéticos com EB através de curvas de magnetização, magnetorresistência anisotrópica (AMR) e magnetometria de torque. Foram crescidos filmes via magnetron sputtering, de NiFe/FeMn (bicamadas) variando a espessura da camada de NiFe e filmes de NiFe/IrMn/Ta com diferentes números de repetições dessa estrutura básica (multicamadas). A partir da difração e refletividade de raios-X determinamos a direção preferencial de crescimento cristalográfico, espessura e o tamanho de grão das amostras estudadas. Foi implementado no Laboratório de Magnetismo e Materiais Magnéticos (LMMM) um aparato experimental para medidas de AMR: resistência em função do ângulo do campo aplicado e resistência em função do campo aplicado para um determinado ângulo escolhido. Para o ajuste aos dados das curvas de magnetização e AMR é apresentado um modelo fenomenológico para EB considerando quatro termos de energia: Zeeman, uniaxial, unidirecional e magnetostático. As curvas de AMR apresentam uma assimetria em torno de 180º quando medidas em valores de campo menores que o campo de Bias. De acordo com o modelo utilizado, tal assimetria pode ser causada por um desalinhamento entre os eixos de anisotropia (uniaxial e unidirecional) ou por um desalinhamento entre a direção da corrente de medida e o eixo fácil de magnetização da amostra. Não foi observado um aumento na dispersão da anisotropia uniaxial com o aumento das repetições das tricamadas, conforme esperado. Para o ajuste das curvas de torque médio utilizamos uma equação com dois termos harmônicos. Os parâmetros resultantes do ajuste das curvas de torque permitiram estudar a evolução das componentes harmônicas Kθ e K2θ. Nas multicamadas quanto maior a energia associada ao torque médio maiores são as perdas de energia por HR. Já nas bicamadas, as perdas de energia por HR aumentam mesmo acima do campo de saturação. Tal comportamento foi associado à configuração de spins interfaciais e sugere a necessidade de uma contribuição adicional para a energia total do sistema magnético.

Dans un contexte de performance énergétique et de durabilité dans le secteur du bâtiment, la maîtrise du comportement hygrothermique des matériaux d'enveloppe, notamment hygroscopiques, est essentielle. Les travaux réalisés concernent la compréhension et la modélisation des transferts de chaleur et d'humidité au sein d'une paroi multicouche de bâtiment composée de matériaux biosourcés.Une attention particulière est portée sur les phénomènes d'hystérésis observés sur les isothermes de sorption. Un modèle numérique 1D développé sur COMSOL Multiphysics est exploité pour simuler en régime transitoire les champs de température et de pression de vapeur dans trois situations. La première concerne l'étude du comportement hygrothermique de matériaux fortement hygroscopique (béton de chanvre) et faiblement hygroscopiques (enduits à base de chaux) soumis à diverses variations cycliques d'humidité relative. Un bon accord est constaté entre les simulations et des mesures d'humidité relative, de température et de teneur en eau. Néanmoins, les résultats présentent une forte sensibilité aux propriétés hydriques. Dans un second temps, une étude est menée sur une paroi de béton de chanvre instrumentée placée dans une enceinte bi-climatique et exposée à des variations de température et d'humidité relative. La confrontation des évolutions mesurées et calculées montre la nécessité de bien définir le champ de teneur en eau initiale. La dernière étude concerne une paroi multicouche (béton de chanvre et enduits). Il apparaît que les enduits jouent un rôle important sur le comportement de la paroi et il est nécessaire de prendre en compte l'influence de la température sur les courbes de sorption. / In a context of energy efficiency and durability in the field of building, the understanding of hygrothermal behaviour of building materials, especially hygroscopic ones, is essential. This study aim to understand and model heat and moisture transfers in a multi-layer building wall made of biosourced materials. We focus in particular on hysteretic phenomena observed on sorption isotherms. A one-dimensional numerical model developed with the COMSOL Multiphysics software is used to simulate transient temperature and vapour pressure in three situations. The first one is about the hygrothermal behaviour of materials, highly hygroscopic (hemp concrete) and lowly hygroscopic (lime-based plasters), exposed to several cyclical variations of relative humidity. A good agreement is observed between simulated and measured values of relative humidity, temperature and moisture content. However, results are highly sensitive to hydric properties. Then, a study is performed on an instrumented hemp-concrete wall built in a bi-climatic chamber and exposed to simultaneous temperature and relative humidity variations. The confrontation between measured and simulated values shows the importance of initial moisture content.

En repartant des recherches qui ont été menées par Pierre Curie sur la dynamique des matériaux et du magnétisme, nous montrerons comment l’hypothèse du sujet de l’inconscient peut s’expliquer par la théorie de la courbe d’hystérésis. L’ambition de ce travail est de montrer comment la question du sujet et son désir peuvent être intégrables à la théorie de l’hystérèse et décrire ce qu’on appellera l’hystérèse du sujet de l’inconscient et de son rapport à la sexualité. Par retour au théorème de Thalès et à sa déclinaison la division harmonique, nous verrons comment l’hystérèse du sujet permet de revisiter de façon originale la théorie des quatre discours posée par Jacques Lacan dans son séminaire livre XVII. Cette nouvelle approche épistémologique aura des implications psychanalytiques notamment sur la question du phallus, de la dette en psychanalyse et va nous mener progressivement à la prolonger à la question du non-discours mais également l’étendre à partir de la théorie freudienne sur les souvenirs écrans au concept d’Écran en psychanalyse. Des précisions et un complément conceptuel seront apportés sur la question de la culture et des invariants qui la structure dans sa fonction capitalistique. Ce nouvel apport conceptuel, qu’on appellera la fonction capitalistique de la culture, sera par ailleurs déterminant pour faire montre des caractéristiques d’une société sous gouvernance néolibérale. En conjuguant l’hystérèse du sujet par la fonction capitaliste de la culture, vont s’agencer différents types de gouvernances sociales, et mettre à jour leurs implications sur les liens des individus entre eux et leur rapport à la liberté versus insécurité. Enfin, à partir de ce nouvel apport conceptuel nous pourrons tirer des enseignements et affiner notre analyse sur le malaise actuel. Un malaise soutenu par un type de discours analytique qui au lieu d’épanouir l’individu dans sa sexualité le plonge dans la misère. Une misère qui selon toute vraisemblance offre la garantie au système sous gouvernance néolibérale de se pérenniser par la mise en place de dispositifs de contrôle et d’évaluation de renforcer sa prégnance et son éthique sur la question de la rentabilité économique. / By restarting the research which has been led by Pierre Curie on the dynamics of materials and magnetism, we will demonstrate how the hypothesis of the subject « unconscious fantasy » can be explained by the hysteresis curve. The goal of this work is to show how the subject in question and their desire can be integrated into the hysteresis theory and describe what we would call the subject's unconscious hysteresis, and its relationship with sexuality. By returning to the Thales theoreom and its declension; the harmonic division, we will see how the subject's hysteresis allows to revisit the Four Speeches theory in an original way, posed by Jacques Lacan in his seminary book. This new epistemological approach would have psychoanalytical implications, notably on the question concerning the phallus, from the debt of psychoanalysis and leading us progressively to extend the question of non speech but equally extending from the Freudian theory of screen memories from the concept Screen Psychoanalysis. Some details and an abstract complement will be provided on the question of culture and its variations which has its structure in the capital-intensive function. This new abstract contribution, which we will call the Capital-Intensive Culture will be furthermore decisive in demonstrating the characteristics of a society under neoliberal governance. By conjugating the subject's hysteresis by the capital-intensive culture, different types of social governance are going to be implemented followed by their implications on the relationship between individuals and their freedom versus insecurity. Finally, from this new abstract contribution, we can teach and refine our analysis on the current unrest. An unrest supported by a type of analytical speech which sends the individual into destitution instead of opening up to their sexuality. Destitution which apparently guarantees being controlled by a system of neoliberal governance and perpetuating the implementation of measures to control and evaluate to strengthen its way and ethics on the question of economic profitability.

This dissertation thesis deals with relation between labour market and monetary policy referring to two fundamental theoretical concepts -- natural rate hypothesis (or NAIRU) and unemployment hysteresis hypothesis. The first chapter outlines the most frequent values of the Phillips curve, the fundamental model of macroeconomics theory in the relation between the labour market and the monetary policy. The following chapter deals with the exogenous NAIRU concept which works as natural unemployment rate approximation. The unemployment hysteresis deals with the NAIRU as endogenous variable which is dependent on preceding imbalanced situations on labour market. The thesis outlines the main causes of the hysteresis: capital scrapping effect, role of the long-term unemployment and the insider-outsider hypothesis. The third chapter also comprises simple econometric tests of both particular mechanisms and the hysteresis itself based on usual unit roots tests. The results show the hysteresis using data from both the Czech Republic and Central and Eastern Europe countries (CEEC). The fourth chapter deals with monetary-political implications of the unemployment hysteresis. The practical part of the thesis is based on two hypotheses of the relation between inflation (policy interest rate) and NAIRU. The last chapter based on the VAR model outlines short-term relations between the labour market and monetary policy variables. Long-term relations are tested by both the co-integration analysis and vector error correction model (VECM). These models are examined on the data from the Czech Republic and Poland (2000-2013). The thesis also applies pooled regression estimate for ten CEEC. The results show that the monetary policy does have impact on the labour market not only in the short-term but also in the long-term period and thus they confirm the hysteresis hypothesis

Orientadores: Kleber Roberto Pirota, Fanny Béron / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T01:32:45Z (GMT). No. of bitstreams: 1 CostaArzuza_LuisCarlos_D.pdf: 5838350 bytes, checksum: f92268a1c7835ed7d3d7f0a83abe2e63 (MD5) Previous issue date: 2016 / Resumo: Este trabalho visa estudar a inversão da magnetização de redes de nanofios de níquel modulados, incorporados em membranas porosas de alumina. A modulação do nanofio foi obtida a partir da variação do diâmetro, resultando em nanofios com dois segmentos. O diâmetro de cada segmento está ao redor do diâmetro crítico do Ni (40 nm), onde, abaixo e acima do mesmo, a inversão da magnetização acontece por meio de diferentes estruturas da parede de domínio; transversais e vórtex. A caracterização magnética das redes de nanofios foi feita usando simulações micromagnéticas e curvas de histerese magnética e de reversão de primeira ordem (método FORC). As medidas foram realizadas em vários arranjos de nanofios ordenados com diferentes razões de comprimento e diâmetros de segmentos, e estas foram comparadas com o arranjo de nanofios sem variação do diâmetro. Simulações micromagnéticas em nanofios isolados e arranjo de nanofios de primeiros vizinhos, mostram que a estrutura da parede de domínio, a qual depende do diâmetro do segmento, sofre uma transformação ao cruzar a região da modulação do diâmetro, porém a dinâmica da transformação depende das dimensões de cada segmento do nanofio. O comportamento magnético experimental do arranjo é atribuído a um campo de interação não homogêneo entre os nanofios, o qual surge devido a modulação do diâmetro. Este campo dá origem a uma interação mais forte na extremidade com diâmetro maior em relação à extremidade com diâmetro menor, resultando em um comportamento da susceptibilidade bastante complexo. Consideramos como principal resultado deste trabalho à possibilidade de controlar o mecanismo de inversão da magnetização em rede de nanofios modulados através da modulação do diâmetro. Os resultados obtidos foram interpretados através dos diagramas FORC, onde o processo dinâmico da inversão da magnetização é evidenciado por meio de diagramas estáticos (diagramas FORC), similar a uma foto estroboscópica / Abstract: We studied the magnetization reversal in modulated nickel nanowire arrays, embedded in porous alumina membranes. The modulation of the nanowire was obtained from the variation in diameter, resulting in nanowires with two segments. The diameter of each segment is below and above the critical diameter for Ni (40 nm), for which the reversal of magnetization changes from transversal to vortex domain wall structure. Magnetic characterization of nanowire networks was made using micromagnetic simulations, magnetic hysteresis and First-order reversal curves (FORC method). The measurements were performed in nanowire arrays with different ratios of length and diameter. The results were compared with the arrangement of nanowires without diameter variation. Micromagnetic simulations for isolated nanowires and nanowire array with few magnetic entities show that the structure of domain wall, which depends on the segment diameter, changes when it crosses the separation region of the diameter modulation and the dynamics of transformation depends on the dimensions of each nanowire¿s segment. The experimental magnetic behavior of the nanowire array is attributed to an inhomogeneous interaction field among the nanowires due to diameter modulation. This effect gives rise to a stronger interaction in the larger diameter segment resulting in a very complex susceptibility behavior. We consider the possibility to control the reversal magnetization mechanism in nanowire array through diameter modulation as the main result of this work. The results were interpreted using the FORC diagrams where the dynamic process of magnetization reversal is evidenced by static diagrams (FORC diagrams), similar to a stroboscopic picture / Doutorado / Física / Doutor em Ciências / 1060136/2011 / CAPES

This work describes a possibility to use a shape memory alloy as a non-traditional actuator in a particular mechatronic system. The practical part of this work is dedicated to the experimental property verification of the chosen shape memory alloy and also to the design and realization of the new type of electrically controlled gabled valve that uses a shape memory alloy as an actuator. This valve is designed as a replacement of the traditional solution and is also integrated into McKibbens pneumatic muscle endcap. There are also results of practical functional verification of the designed gabled valve solution listed here, and the limited condition for its manufacturing and use is stated here. In the theoretical part of this work, firstly, the shape memory alloy and non-linear systems hysteresis type are discussed. Secondly a new particular solution is designed, which is based on a non-linear computational element, defined by goniometric cosine function. Finally, the properties of the designed solution are verified through the simulations and with the use of experimentally gained datas.

This diploma thesis is focused on investigation of metallic thin films and nanostructures using scanning probe microscopy. Magnetic properties of these objects are studied by magnetic force microscopy, which is modification of scanning probe microscopy. In the theoretical part basic principles of scanning probe microscopy and magnetic force microscopy are summarized, and also principle of creation of magnetic domains and some special properties of ferromagnetic and antiferromagnetic materials. Further, two techniques of fabricating nanostructures are described. Experimental part is focused on imaging and simulating of magnetic domains. Further, exchange bias is revealed. This phenomenon is present in systems composed from ferromagnetic and antiferromagnetic materials. One part of this diploma thesis is also focused on discussion of problems with magnetic force microscopy.

This thesis deals with the ferroresonance phenomenon and ferroresonance overvoltage in electric networks. That’s why the introduction part explains the theoretical basis of ferroresonance and its consequences in the power system. The work then focuses on the power system as a non-linear dynamic system and describes various analytical methods for solving these systems. These methods are further applied to diagnose specific systems. There are a number of various power system configurations susceptible to ferroresonance. The most frequent one is theoretically analyzed in this thesis and a number of recommendations are offered for reducing the ferroresonance phenomenon. The thesis further deals with the selection of suitable software for this computationally chal-lenging task. A number of different tools are considered and efficiently reduced to Matlab Sim-ulink and PSCAD software. Matlab Simulink and its SimPowerSystem Toolbox are used to ana-lyze the effect of hysteresis of the magnetic core of the transformer on the emergence and course of the ferroresonance phenomenon. Using PSCAD, various configurations of the power systems are compared in terms of possible emergence and course of ferroresonance and also to find the limiting conditions that increase the probability of this phenomenon. The possibility of using arti-ficial neural networks for ferroresonance diagnosis is also mentioned in this thesis. The final part provides a number of recommendations for design and operation of both new and existing power systems.

This diploma thesis deals with the design of pneumatic pressure switch with adjustable hysteresis. In the thesis is carried out the introduction in the theory of compressed air and research of the pressure switches at the market. Based on the gathered information and customer specification, the design draft of the pressure switch has been created. In the thesis are described three main parts of the prototype: transform of the pressure, adjustable hysteresis and synchronization of the microswitches. In the end of the thesis is described the testing of prototype and summary of the results.