L'utilisation de matériaux conducteurs transparents (TCM) a rapidement augmenté au cours des deux dernières décennies en raison de la demande croissante liée à l'usage d'appareils électroniques personnels ainsi qu'au développement de cellules solaires à base de couches minces. Jusqu'à présent, le TCM le plus couramment utilisé a été l'oxyde d'indium et d'étain (ITO), mais l'indium est une terre rare dont l'environnement géopolitique lié à son approvisionnement et à sa production est complexe. En outre, la famille des oxydes transparents conducteurs possèdent de médiocres propriétés mécaniques (associée à une fragilité mécanique) et exige souvent pour leur dépôt soit une synthèse à haute température (> 400 ° C) soit des procédés sous vide. Pour ces raisons, la recherche au cours des dernières années a mis l'accent sur la recherche de TCM alternatifs afin de remplacer l'ITO. Cette thèse s'ancre sur une double approche combinant simulations numériques et des expériences pour explorer le dépôt et l'optimisation des réseaux de nanofils d'argent pour une utilisation comme électrode transparente d'une part et d'améliorer la compréhension de leurs propriétés physiques d'autre part. L'approche par simulation concerne la modélisation de la percolation de réseaux de nanofils 2D tandis que la composante expérimentale explore les propriétés électriques et optiques des réseaux de nanofils d'argent et notamment le comportement de la résistance électrique lors de recuits thermiques. Nous présentons dans ce travail la modélisation 2D de la percolation de systèmes initialement composés de bâtonnets parfaits au sein d'un réseau idéal, puis l'étude de l'influence de paramètres tels que: la distribution des longueurs de bâtonnets, des distributions angulaires ou de la courbure de ces bâtonnets. Nous nous sommes aussi intéressés à la divergence de la densité critique nécessaire pour observer la percolation au sein de systèmes de petite taille (vis-à-vis de la longueur des bâtonnets). Par ailleurs un travail préliminaire sur la simulation de l'efficacité de collecte (ou d'injection) de charges par un réseau de nanofils est présenté. Le volet expérimental fournit une analyse de l'influence de la longueur des fils, de leur diamètre, de la densité du réseau et enfin de la méthode de dépôt sur les propriétés optiques et électriques des réseaux de nanofils d'argent. Une étude approfondie de l'effet de recuit thermique sur les propriétés des réseaux a été réalisée qui a révélé plusieurs mécanismes qui sont à l'origine de la diminution initiale de la résistance électrique à relativement basse température puis la divergence de la résistance électrique observée à haute température. Une observation originale a permis de révéler un phénomène de percolation géométrique quantifiée pour les réseaux peu denses qui a été associé à la présence de chemins efficaces de percolation indépendants. Ce travail permet de conclure que les réseaux de nanofils d'argent constituent une solution intéressante pour une utilisation comme électrode transparente en remplacement de l'ITO ; notamment car ils ont des propriétés mécaniques supérieures et peuvent atteindre des propriétés électro-optiques comparables voire même supérieures. / The use of transparent conductive materials (TCMs) has rapidly increased in the last two decades as a result of increasing demand for personal electronic devices and the development of thin film based solar cells. To date the most commonly used TCM is indium tin oxide (ITO), however indium is a rare earth metal with a complex geopolitical environment surrounding its supply and production. Furthermore the oxide family suffers from poor mechanical properties such as brittleness and generally requires either high temperature synthesis (>400°C) or vacuum processes for their deposition. For these reasons, research in recent years has focused on searching for a TCM to replace ITO. This thesis uses a dual approach combining simulations and experiments to explore the fabrication and optimisation of silver nanowire networks for use as a TCM and to improve the understanding of their physical properties. The simulation component focuses on the application of percolation modelling to 2D nanowire networks while the experimental component explores the electrical and optical properties of silver nanowire networks and their electrical behaviour under thermal annealing. We present in this work the modelling of 2D stick percolation systems initially composed of perfect idealised sticks, and then investigate the influence of parameters such as: length distributions, angular distributions or curved nanowires. We address the divergence of the critical density for the onset of percolation observed for small system sizes and introduce some preliminary work on simulating the collection (or injection) efficiency of charges by a nanowire network. The experimental component provides a discussion of the impact of wire length, wire diameter, network density and fabrication technique on the optical and electrical properties of silver nanowire networks. An in-depth study of the effect of thermal annealing on the networks properties was undertaken which revealed several mechanisms that were responsible for the initial reduction of resistance and final loss of conductivity observed. An original observation enables the revelation of geometrical quantized percolation for rather sparse networks. Finally we conclude that silver nanowire networks are an excellent prospect for a TCM to replace ITO, they have superior mechanical properties and can achieve comparable and even superior electro optical properties.

Submitted by GUILHERME RODRIGUES DE LIMA null (guirodrigueslima@hotmail.com) on 2017-09-15T18:57:55Z No. of bitstreams: 1 Defesa_correção_ficha_catalografica.pdf: 3367275 bytes, checksum: 6a436d913d3a352c3a8ec8e237660a1b (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-19T17:42:06Z (GMT) No. of bitstreams: 1 lima_gr_me_sjrp.pdf: 3367275 bytes, checksum: 6a436d913d3a352c3a8ec8e237660a1b (MD5) / Made available in DSpace on 2017-09-19T17:42:06Z (GMT). No. of bitstreams: 1 lima_gr_me_sjrp.pdf: 3367275 bytes, checksum: 6a436d913d3a352c3a8ec8e237660a1b (MD5) Previous issue date: 2017-08-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Transistores de filme fino (TFT) são dispositivos presentes em nosso cotidiano, usados em uma ampla variedade de aplicações, desde de processadores, registradores e monitores de tela plana. Estes dispositivos apresentam diversos benefícios, tais como: transparência, flexibilidade, rapidez, baixo custo e confiabilidade, o que faz com que tenham interesse de muitos grupos de pesquisa nas últimas décadas. Este trabalho visa o desenvolvimento de um novo método de deposição por spray, em atmosfera ambiente e a baixa temperatura (350ºC), para produção de filmes finos de óxidos zinco (ZnO) aplicados como camada ativa em TFTs. Os filmes finos transparentes de ZnO foram depositados por solução de um precursor orgânico (acetato de zinco bi-hidratado (Zn(CH3COO) · 2H2O)) sobre substratos de Si-p/SiO2 pelo método de deposição por spray. Este método emprega uma automação própria de controle na deposição para obter filmes altamente homogêneos e reprodutivos. Um grande conjunto de parâmetros na deposição foram testados para otimização dos filmes semicondutores para TFTs, como por exemplo: distância do spray sobre a placa de aquecimento, tempo de deposição, número de camadas, concentração da solução, entre outros. Os resultados obtidos na caracterização dos dispositivos, como, mobilidade de saturação (µsat), tensão de limiar de operação (Vth) e razão entre a corrente de operação e a corrente intrínseca (ION/OFF), foram comparados para diferentes parâmetros de deposição utilizados. Esse trabalho contribui em utilizar um novo método de deposição de baixo custo, para possíveis aplicações industriais e que pode ser expandido facilmente para larga escala de produção na fabricação de outros dispositivos de filme fino, como, OTFTs (Organic Thin Film Transistors), células solares, LCDs (Liquid Crystal Displays), OLEDs (Organic Light Emitting Diodes), LEDs (Light Emitting Diodes) e sensores. / Thin-film transistors (TFT) are every day devices used in a wide variety of applications, like processors, recorders and flat-panel monitors. These devices that present benefits, such as transparency, flexibility, speed, lower-cost and reliability, which have attracted interest in several research groups in recent decades. The aim of this work is the development of a new method of spray deposition, in ambient atmosphere and at low temperature (350ºC), for the production of thin films of zinc oxide (ZnO) applied as active layer in TFTs. The ZnO thin films were deposited from an organic solution of zinc acetate dihydrate (Zn(CH3COO) · 2H2O) on to Si-p/SiO2 substrates by the spray deposition method. This method employs its own automation for the deposition to obtain highly homogeneous and reproducible films. A large set of parameters in the deposition were tested for optimization of the semiconductor films for TFTs, such as: distance of the spray to the hot-plate, deposition time, number of layers, solution concentration, among others. The results obtained in the characterization of the devices, such as, mobility at saturation (μsat), threshold voltage (Vth) and on/off ratio (ION/OFF), were compared for different deposition parameters. This work contributes to the development of a novel, low-cost deposition method for possible industrial applications that can be easily expanded for large scale production of other thin film devices, such as, Organic Thin Film Transistors (OTFTs), solar cells, LCDs (Liquid Crystal Displays), OLEDs (Organic Light Emitting Diodes), LEDs (Light Emitting Diodes) and sensors. / CNPq: 133952/2015-0

nÃo hà / Um grave problema presente quando aplicamos semÃntica composicional, que atribui simples valores de verdade a frases, à que quando essas seqÃÃncias estÃo presentes em alguns contextos especÃficos, a substituiÃÃo de certas expressÃes com a mesma referÃncia pode cambiar o valor de verdade da frase maior ou entÃo impedir que inferÃncias vÃlidas sejam realizadas. Por exemplo, da afirmaÃÃo "Pedro acredita que Alexandre o Grande foi aluno de AristÃteles", nÃo se pode inferir corretamente neste contexto de crenÃa que a substituiÃÃo de "Alexandre o grande" por "o vencedor da batalha de Arbela" seja vÃlida porque eventualmente Pedro pode nÃo saber que "Alexandre o Grande à o vencedor da batalha de Arbela" e por isso a verdade das premissas nÃo garante a verdade da conclusÃo: "Pedro acredita que o vencedor da batalha de Arbela foi aluno de AristÃteles". A conclusÃo nÃo se segue pois ela nÃo depende da relaÃÃo de identidade efetiva entre âAlexandre o Grandeâ e âO vencedor da Arbelaâ, e sim depende, de maneira contingente, do conjunto de crenÃas de Pedro; ou ainda, segundo Frege, depende do sentido que Pedro associa a descriÃÃo âAlexandre o Grandeâ. Em contextos intensionais a verdade da conclusÃo (apÃs substituiÃÃo) depende de uma maneira especÃfica da maneira de conceber o nome em questÃo, por isso a substituiÃÃo entre nomes cujo referente à o mesmo, mas que diferem em sentido, nÃo funciona em todos os casos. O fato à que Frege nunca estabeleceu critÃrios de identidade para o sentido (Sinn), apenas reservou-se a declarar simplesmente que o sentido à o "modo de apresentaÃÃo" da referÃncia. Pretendemos apresentar critÃrios de identidade para o sentido em geral, e em contextos intensionais, em particular. Os sucessores de Frege, dentre eles o lÃgico Alonzo Church e o filÃsofo Rudolf Carnap foram os primeiros a estabelecer que duas expressÃes tÃm o mesmo sentido se e somente se sÃo sinonimamente isomorfas e intensionalmente isomorfas, respectivamente. Tais critÃrios devem ser entendidos à luz dos pressupostos lÃgicos de Church em sua LÃgica do Sentido e da DenotaÃÃo (LSD) e das idÃias de Carnap â muitas delas constituintes do programa filosÃfico do Positivismo lÃgico, em seu livro Meaning and Necessity. Mais recentemente, Pavel Tichà estabeleceu de maneira mais exata o que à o sentido e sua identidade atravÃs do Procedural isomorphism o qual constitui um dos fundamentos da LÃgica Intensional Transparente (TIL). / A feature of the distinction between extensionalism and intensionalism, which has been widely taken as a criterion to separate the two positions, is that within an extensionalist logic, substitution is possible salva veritate (that is, without thereby changing the truth-value of the statement concerned) with respect to identical instances of some basic logical form â and in an intensionalist logic it is not. The different logical forms with respect to which such substitution might take place accounts for some of the variety of different extensionalisms on offer in the current philosophical landscape. So our starting-point is Fregeâs puzzle. This question is frequently accepted as one of the foundations of modern semantics. To explain why a true sentence of the form âa = bâ can be informative, unlike a sentence of the form âa = aâ, Frege introduced an entity standing between an expression and the object denoted (bezeichnet) by the expression. He named this entity Sinn (sense) and explained the informative character of the true âa=bâ-shaped sentences by saying that âaâ and âbâ denote one and the same object but differ in expressing (ausdrÃcken) distinct senses. The problem, though, is that Frege never defined sense. The conception of senses as procedures that is developed here has much in common with a number of other accounts that represent meanings, also, as structured objects of various kinds, though not necessarily as procedures. In the modern literature, this idea goes back to Rudolph Carnapâs (1947) notion of intensional isomorphism. Church in (1954) constructs an example of expressions that are intensionally isomorphic according to Carnapâs definition (i.e., expressions that share the same structure and whose parts are necessarily equivalent), but which fail to satisfy the principle of substitutability. The problem Church tackled is made possible by Carnapâs principle of tolerance (which itself is plausible). We are free to introduce into a language syntactically simple expressions which denote the same intension in different ways and thus fail to be synonymous. TichÃâs objectualist take on âoperation-processesâ may be seen in part as linguistic structures transposed into an objectual key; operations, procedures, structures are not fundamentally and inherently syntactic items, but fully-fledged, non-linguistic entities, namely, constructions.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In the present work, we performed a study of the structural, electrical and optical properties of the compound LaCr1-xAlxO3 (x = 0.0, 0.05, 0.5, 0.95 and 1.0) produced by the combustion method. The structural analyzes were performed by X-ray diffraction (XRD) and Rietveld refinement, the electrical measurements using impedance spectroscopy and IV measurements, and optical measurements using UV-Vis spectroscopy. The results of XRD allied to the Rietveld method of refinement indicate that the samples with x = 0.0 and 0.05, have an orthorhombic structure belonging to the space group Pnma (62), and for x = 0.5, 0.95 and 1.0, a rhombohedral structure belonging to the space group R-3c (167), thus taking place a structural transition in the material. The impedance spectroscopy measurements associated to the IV curves show that the samples with higher concentration of Al present higher resistance, and the samples with lower concentration of Al present less resistance. We observe that for high frequencies a decrease of dielectric constant with frequency occurs. In addition, the appearance of only a semicircle establishes the presence of non-Debye type relaxation, where an equivalent circuit composed of two resistors (R1 and R2) and a constant phase element (CPE) were used. By means of the absorption measurements in the ultraviolet to visible region (UV-Vis), we estimated the optical gap of the samples, through the tauc equation, which vary between 3.27 - 3.43 eV. Still, we observed that the increase in Al concentration favors the increase in transmittance in the material. / No presente trabalho, realizamos um estudo das propriedades estruturais, elétricas e ópticas do composto LaCr1-xAlxO3 (x=0,0; 0,05; 0,5; 0,95 e 1,0) produzido pelo método da combustão. As análises estruturais foram realizadas por meio de difração de raios-X (DRX) e refinamento Rietveld, as elétricas por meio de espectroscopia de impedância e medidas IV, e ópticas por meio de espectroscopia de UV-Vis. Os resultados de DRX aliados ao método de refinamento Rietveld indicam que as amostras com x = 0,0 e 0,05, apresentam uma estrutura ortorrômbica pertencente ao grupo espacial Pnma (62), e para x = 0,5; 0,95 e 1,0, uma estrutura romboédrica pertencente ao grupo espacial R-3c (167), ocorrendo assim uma transição estrutural no material. As medidas de espectroscopia de impedância associadas às curvas IV mostram que as amostras com maior concentração de Al apresentam maior resistência, e as amostras com menor concentração de Al apresentam menor resistência. Observamos que para altas frequências ocorre uma diminuição da constante dielétrica com a frequência. Além disso, o aparecimento de apenas um semicírculo estabelece a presença do relaxamento do tipo não-Debye, onde foi utilizado um circuito equivalente composto por duas resistências (R1 e R2), e um elemento de fase constante (CPE). Através das medidas de absorção na região do ultravioleta ao visível (UV-Vis) estimamos o gap óptico das amostras, através da equação de tauc, os quais variam entre 3,27 - 3,43 eV. Além disso, observamos que o aumento da concentração de Al favorece o aumento da transmitância no material. / São Cristóvão, SE

O objetivo desta pesquisa foi avaliar o desempenho térmico de brises transparentes, por meio de medidas em células-teste construídas em escala 1:1, na cidade de Campinas, São Paulo. Trata-se de um estudo que faz avaliação comparativa das temperaturas internas e superficiais dos brises e do vidro da janela em seis células-teste, quatro delas protegidas com brises transparentes horizontais e verticais combinados, constituídos por vidros, outra protegida com brise-soleil metálico horizontal e uma sem dispositivo de proteção solar, sendo esta considerada de referência. Foram selecionados quatro tipos de vidro com diferentes características ópticas: vidro float comum incolor, vidro impresso mini-boreal, vidro float comum azul e vidro refletivo metalizado a vácuo prata médio. Foi possível concluir que os brises de vidro refletivo prata, float azul e impresso possuem um desempenho térmico similar entre si e ao brise metálico estudado, e que o brise de vidro float incolor não apresenta um resultado de desempenho térmico satisfatório. Com relação aos procedimentos de medidas de campo, foram verificadas as modificações necessárias, para trabalhos futuros que tenham o mesmo objetivo dessa pesquisa, ou similares a esse. Além da avaliação do desempenho térmico, foi também iniciada uma avaliação do desempenho luminoso dos brises. Por meio das medidas dos níveis de iluminação natural dentro das células-teste constatou-se que o brise de vidro impresso apresentou um ótimo desempenho luminoso e que o brise de vidro refletivo prata reduziu significativamente a iluminância dentro da célula-teste, obtendo um desempenho luminoso inferior até mesmo ao brise metálico / This research intended to evaluate thermal performance of transparent solar protections using measurements in full scale test cells, located in the city of Campinas, São Paulo, Brazil. Surface (window and shading device) and internal air temperatures were compared for six test cells. One of them was unprotected, for reference purposes, another was obstructed with a metallic shading device and the other four had transparent glass horizontal and vertical shades installed. Four different types of glass with different optical properties were selected: float clear glass, mini-boreal printed glass, float blue glass and metallic silver reflective glass. The results of the thermal appraisal showed that silver reflective glass, float blue and printed glass shadings achieved similar performance, not very different to the ones obtained for the metallic shading device. Therefore the float clear glass shading did not attain a satisfactory result. The field measurements procedures were also evaluated and test cells characteristics problems were identified, in order to suggest changes for future research in this area. This research began to evaluate light performance of the same solar protections. For light performance evaluation were measured the daylight in the center of each test cell and outside. It was concluded that printed glass shadings presented very good results and silver reflective glass reduced the daylight inside the test cell

L'utilisation de matériaux transparents et conducteurs a subi une croissance exponentielle lors de la dernière décennie, puisque faisant partie intégrante de nombreux dispositifs optoélectroniques tels que les écrans tactiles & les cellules solaires. Parmi ces matériaux, l'oxyde d'indium-étain occupe la quasi-totalité du marché puisqu'il associe une conductivité élevée et une transparence supérieure à 90% sous forme de film mince. Cependant, le développement de technologies flexibles pousse à rechercher des alternatives à son utilisation car son cout élevé et sa faible flexibilité le rendent incompatible. Au milieu des alternatives carbonées (graphène et nanotubes), les nanomatériaux métalliques ou les polymères conducteurs se présentent comme des alternatives intéressantes : bas cout et facilité à mettre en forme pour les polymères conducteurs, hautes performances pour les nanofils métalliques. Cette thèse présente la mise en œuvre de ces matériaux alternatifs par la méthode originale d'électrofilage et l'étude de leurs propriétés optoélectroniques. La maitrise des conditions de mise en forme (champ, débit, paramètres environnementaux) et l'optimisation des solutions utilisées (rhéologie, concentration en polymère, co-solvants) nous a permis d'obtenir 2 types de nanostructures : des nanofibres 100% polymériques à base de PEDOT:PSS et des nanofibres composites PVP:Nanofils d'argent. L'étude des propriétés opto-électroniques des réseaux ainsi obtenus a aussi été étudiée / The use of transparent and conductive materials has been growing exponentially in the last decade as they are part of many optoelectronic devices such as touch screens and solar cells. Among these materials, Indium-Tin Oxide (ITO) is the market reference since it combines a low resistivity and a high transparency up to 90% in the form of thin film. However, the growing in the development of flexible technologies created a real need in alternatives as ITO has poor mechanical properties. Carbon nanotubes and graphene are potential substitutes, but metallic nanowires and conductive polymers have been developed for their high performances and low cost respectively.This thesis presents the implementation of these alternatives by the original method of electrospinning and the study of their optoelectronic properties. The optimization of the experimental setup (field, rate, environmental parameters) and solutions (rheology, polymer concentration, co-solvents) allowed us to obtain 2 different kinds of nanostructures: fully polymeric with PEDOT:PSS and composite with PVP and silver nanowires. The study of the optoelectronic properties of the resulting networks has also been investigated

Les céramiques polycristallines transparentes de YAG (Yttrium Aluminium Garnet, Y3Al5O12) et de YAG dopé par des lanthanides (Nd, Er, Ho, etc.) ont des propriétés optiques comparables aux monocristaux et peuvent être utilisées comme milieu laser solide dans les lasers solides à haute capacité calorifique. L’utilisation de ces céramiques polycristallines transparentes présente de nombreux avantages comparés aux monocristaux. Ces matériaux ont une meilleure conductivité thermique et sont fabriqués à plus faible coût tout en présentant des propriétés mécaniques améliorées et ce, sur des pièces de plus grandes dimensions. De plus, il est possible d’atteindre de plus forts taux de dopage avec une répartition uniforme du dopant. Le dopage du YAG par l’erbium (0.25 %at.) permet une émission laser « eye-safe » de 1645nm. De plus, un faible taux de dopage permet d’éviter le phénomène d’upconversion lors de l’effet laser.Les conditions pour obtenir la transparence sont, entre autres, l’absence de défauts, une très grande pureté (>99.9%), une répartition de taille de grains homogène et une densité très élevée (>99.9%).Les céramiques transparentes sont obtenues par la voie métallurgie des poudres. La synthèse par voie chimique (co-précipitation, sol-gel, voie hydrothermale…) permet la production de poudres très pures, avec une taille de particules homogène et nanométrique, comparée à la synthèse par voie mécanique (broyage d’oxydes). Le frittage SPS (Spark Plasma Sintering) permet quant à lui une densification rapide, à plus basse température, empêchant ainsi une croissance excessive et anormale des grains lors de la densification. L’application d’un courant électrique de forte intensité associée à une charge uniaxiale permet d’accélerer la cinétique de frittage comparé aux méthodes de frittage conventionelles.Ce travail porte sur l’élaboration de céramiques polycristallines transparentes Er:YAG par la voie métallurgie des poudres. La synthèse de poudre est réalisée par co-précipitation inverse d’une solution de nitrates dans l’hydrogénocarbonate d’ammonium. L’influence des paramètres de synthèse tels que le pH, la concentration, le temps de maturation ou encore le cycle de calcination a été étudiée. Après optimisation des conditions de synthèse, des particules d’Er:YAG pur présentant une taille moyenne de 50nm ont été obtenues. L’étude des mécanismes réactionnels a été menée en associant différentes techniques de caractérisations en température telles que la spectrométrie IR, la diffraction des rayons X, ainsi que des analyses thermo-gravimétriques et différentielles. La formation de la phase YAG à 1050°C passe par la formation d’une phase intermédiaire, le YAP (Yttrium Aluminium Perovskite, YAlO3) à 900°C.Les poudres synthétisées ont ensuite été frittées par frittage flash SPS. L’étude de l’influence du cycle de frittage (température, charge, rampe, maintien) sur la microstructure et son optimisation a été réalisée à partir de poudre commerciale et a permis l’obtention de céramiques transparentes de diamètre 30mm et d’épaisseur 3mm. Un changement d’échelle a également été réalisé permettant la réalisation d’échantillons de diamètre 60mm d’une part, et d’épaisseur 6mm d’autre part / Yttrium aluminium garnet (YAG, Y3Al5O12) transparent ceramics have attracted much attention since it can replace single crystals as host materials in solid state heat capacity lasers. These polycrystalline ceramics present improved mechanical and spectroscopic properties, as well as a better heat conductivity, lower fabrication costs for larger size materials. Furthermore, it is possible to reach higher doping concentrations as well a uniform distribution. Doping YAG with Erbium (Er:YAG) allows eye-safe emission at 1645nm. Moreover, a low doping rate (0.5%at.) enables upconversion process during laser operation. Conditions for transparency are amongst others, the absence of defects, a high purity (>99.9%), an homogeneous grain size as well as a high density (>99.9%).Transparent polycrystalline ceramics can be obtained by powder metallurgy route. Powders, synthesized by chemical reactions such as sol-gel process, co-precipitation or hydrothermal methods, present some advantages like high purity, homogeneity and nano-sized particles compared to those obtained by solid-state reactions. A recent process called Spark Plasma Sintering (SPS) is presented to be a promising technique for the densification of nanostructured materials. Indeed, high current and pressure allow sintering at lower temperatures in shorter sintering time than in regular processes. Besides, rapid heating enables to limit excessive grain growth.In this study, Er:YAG nanopowders have been synthesized by co-precipitation using nitrates as precursors and ammonium hydrogen carbonate as precipitant. The influence of precipitation parameters such as pH, concentration, aging time, or even calcination temperature, has been studied. Er:YAG nanoparticles, with an average grain size of 30nm have been successfully synthesized. The reaction mechanisms have been investigated using different techniques such as infrared spectroscopy, x-ray diffraction, thermal analyses… The YAG phase is formed around 1050°C passing through an intermediate phase called YAP (Yttrium Aluminium Perovskite, YAlO3) at 900°C.Synthesized and commercial powders have been sintered to transparency using SPS device. Optimisation of the sintering conditions (temperature, load, heating rate, dwell time) have been realized using commercial powder. Transparent polycrystalline ceramic specimens with a 30mm diameter and 3mm thickness have been successfully obtained. A scale-up study enabled to produce samples with a diameter up to 60mm and also with 6mm thickness

Cette thèse est consacrée à la conception et au développement d’un système de reconstruction tridimensionnelle d’objets transparents par imagerie polarimétrique. Nous présentons tout d’abord une extension de la technique de “Shape from Polarization” aux surfaces transparentes. Après réflexion sur la surface, la lumière incidente non polarisée devient partiellement linéairement polarisée, en fonction de l’angle d’incidence et de l’indice de réfraction du matériau. Ainsi, les normales de la surface sont calculées à partir des paramètres de polarisation de la lumière réfléchie. L’ambiguïté concernant l’orientation des normales est ici levée grâce à l’utilisation d’un éclairage multispectral dont la difficulté de calibration est expliquée dans ce manuscrit. Pour finir, nous détaillons précisément le prototype développé, et présentons des résultats de reconstruction 3D sur des objets parfaitement calibrés. / This thesis deals with a new automated tridimensional inspection system for transparent surfaces, based on polarization analysis. We first present an extension of the ‘Shape from Polarization’ method for transparent surfaces. After being reflected, an unpolarized light wave becomes partially linearly polarized, depending on the surface normal and on the refractive index of the media it impinges on. Hence, by measuring the polarization parameters of the reflected light, the surface normals are computed. The ambiguity concerning the normal orientation is solved here with a multispectral lighting system. Finally, the description of the whole acquisition prototype is given as well as some experimental results on calibrated objects are presented.

The thesis deals with financial accounting and taxation; i.e. areas with increased risk of unethical behaviour. It presents and critically evaluates the measures introduced by the European Union, the Organisation for Economic Co-operation and Development (OECD) and the authors of Taxparency project - the nongovernmental organisation Transparency International Česká republika and Lexperanto association. The introductory chapters of the thesis offer a brief excursion into the realms of philosophy, law and psychology. Their purpose is to provide a comprehensive summary of the most important findings from these disciplines for better understanding of the meaning and fundamentals of ethics. Subsequently, three key areas of financial accounting and taxation are discussed - non-transparent ownership structures, virtual offices and transfer prices - with the objective to determine the motives of entrepreneurs to use these practices. LuxLeaks case is mentioned as a practical example of unethical behaviour of entrepreneurs, tax advisers as well as of civil servants. The conclusion outlines the Taxparency project. The aim of the thesis is not only to introduce but also critically evaluate the project. Based on the results of a questionnaire survey, the possibilities of the project implementation in the conditions of the Czech Republic are analysed. The official websites of individual institutions and organisations became the main information source for the thesis.

Cílem této práce je návrh a implementace řešení transparentního šifrování pro platformu Microsoft Windows. Řešení by mělo být propojitelné s produktem prevence proti úniku dat (DLP) a rozšiřovat jej. K implementaci byl využit framework Microsoft File System Minifilter Driver, s jehož pomocí je možné sledovat a upravovat přístup k jednotlivým souborům na externích zařízeních nebo discích za běhu systému. Soubory jsou zabezpečeny na pozadí tak, aby uživatel nebyl neovlivněn při práci. Ovladač zajišťuje, že uživatel vždy pracuje s rozšifrovanými daty. Dále bude také vyvinuta externí aplikace, která umožňuje uživateli přistoupit k zašifrovaným datům, aniž by musel být v síti, kde DLP produkt běží.