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Matériaux bi-fonctionnels pour applications catalytiques et piézoélectriques, à base d'oxydes de cérium, de lanthane et de langasiteOuzaouit, Khalid 23 October 2007 (has links) (PDF)
Ces études ont pour objectif la mise en œuvre de bi-matériaux constitués d'une phase catalytique active vis-à-vis de divers gaz (méthane), et d'une phase ferroélectrique-piézoélectrique sensible aux modifications de la phase catalytique (ou absorbante). Les phases catalytiques de base sont le dioxyde de cérium CeO2 et le cérate de baryum BaCeO3. Le système « oxyde de lanthane-hydroxycarbonate » La2O3 - La(OH)x (CO3)y a de même été étudié comme phase catalytique potentielle : son intérêt réside dans sa composition, variable en fonction de la température de travail. La phase piézoélectrique choisie est la langasite La3Ga5SiO14 qui présente l'avantage de rester piézoélectrique au-dessus de 1000°C, et peut donc être utilisée dans des systèmes catalytiques à des températures élevées (600°C). Dans une première partie nous présentons une étude bibliographique des enjeux environnementaux de la réalisation de nouveaux capteurs de gaz, notamment fonctionnant selon le principe de perturbation d'ondes acoustiques de surface. Une revue des travaux existants est développée. Les diverses techniques utilisées sont rassemblées dans un chapitre spécifique (méthodes de synthèses, diffraction de rayons X, spectroscopie infrarouge, microscopies électroniques, mesures électriques) .Les synthèses et caractérisations des phases (CeO2, BaCeO3, La2O3 ...) développées en tant que phases catalytiques optimisées sont détaillées dans une première étape. Certaines phases ont été obtenues sous des formes nanostructurées, performantes d'un point de vue conversion de CH4 en CO2. Les comportements lors de décompositions thermiques de l'hydroxycarbonate de lanthane ont été étudiés par analyses thermiques, spectroscopie infrarouge et mesures d'impédances électriques. La phase piézoélectrique La3Ga5SiO14 (langasite) a été synthétisée selon diverses approches nouvelles (réaction solide, sol-gel) : la synthèse est difficile, car, selon divers auteurs, ce composé est caractérisé par une fusion incongruente. La phase polycristalline obtenue après divers cycles thermiques atteint en fait une haute pureté apparente. La vérification de la qualité cristalline a été réalisée par un affinement structural (Rietveld) qui a permis de confirmer la qualité de la phase obtenue. Les coordonnées atomiques affinées à partir de diagrammes de diffraction de rayons X sont très proches de celles figurant dans la littérature pour un monocristal. Des études par spectroscopie IRTF et mesures électriques ont de même été réalisées. Enfin des couches minces de langasite, de lanthane et d'oxycarbonate de lanthane ont été obtenues à partir de voies sol-gel suivies de dépôt par spin-coating (et cela pour la première fois). Des bicouches langasite/lanthane sur substrat silicium ont été obtenues avec une bonne cohésion d'ensemble. Ces premières bicouches feront l'objet d'études ultérieures approfondies
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A history of anti-partitionist terspectives in Palestine 1915-1988Guediri, Kaoutar January 2013 (has links)
The diplomatic and political deadlock in what has come to be known as the Palestine/Israel conflict, has led to the re-emergence of an anti-partition discourse that draws its arguments from the reality on the ground and/or from anti-Zionism. Why such a re-emergence? Actually, anti-partitionism as an antagonism depends on its corollary, partitionism, and as such, they have existed for the same period of time. Furthermore, the debate between antipartitionists and pro-partitionists – nowadays often referred to as a debate between the one-state and the two-state solution – is not peculiar to the period around 2000. It echoes the situation in the late 1910s when the British were settling in Palestine and authorising the Zionist settler colonial movement to build a Jewish homeland thus introducing the seeds of partition and arousing expressions of anti-partitionism. This dissertation aims to articulate a political history of the antipartitionist perspectives against the backdrop of an increasing acceptance of Palestine's partition as a solution. This account runs from 1915 and the first partition – that of the Arab territories of the Ottoman Empire – to 1988 and the Palestinian recognition of the principle of partition. Thus, I argue that the antipartitionist perspectives have persisted throughout history. Such a historical perspective enabled me to consider the acceptance of partition as the result of a shift from a “national and territorial liberation” strategy to the search for “sovereignty and national independence”, a shift that was operated in the Palestinian national movement as well as in the Zionist movement, and which made statehood the main objective. In this regard, the Palestinian acceptance of the principle of partition and of a two-state solution may be regarded as a legitimation of the Israeli colonial settler state.
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Simulation par CFD et mesure en ligne de la distribution des temps de séjour et la qualité de mélange dans une extrudeuse bi-vis / CFD simulation and online measurement of the residence time distribution and mixing quality ina twin- screw extrudersZhang, Xian-Ming 10 November 2008 (has links)
Aujourd’hui le développement de nouveaux matériaux polymères ayant de bonnes propriétés repose de plus en plus sur des procédés de mélange ou de compoundage de polymères au lieu de recourir à la synthèse de nouvelles molécules. L’action du mélange peut fortement influer sur la morphologie des matériaux polymères multi-constituants. Les extrudeuses bi-vis (TSE) sont souvent utilisées comme mélangeurs/réacteurs pour des procédés de mélange, de compoundage et d’extrusion réactive. Cependant, l’étude sur la qualité du mélange dans les TSE demeure un grand défi en raison de la complexité géométrique et du caractère transitoire de l’écoulement. Cette thèse a pour objet de développer un nouvel instrument en line pour mesurer en temps réel la distribution des temps de séjour (DTS) qui caractérise la performance du mélange axial et la capacité de convoyage de différents types d’éléments de vis basées sur l’analyse de l’écoulement transitoire et l’évaluation systématique de la théorie de mélange dans les TSE. Le mélange distributif des polymères fondus est caractérisé par la génération de l’aire des interfaces, un paramètre difficile à mesurer expérimentalement. Alors on fait appel à des simulations numériques de type CFD / The development of new materials with improved properties seems to rely nowadays more on blending and compounding than on the synthesis of chemically new polymers. Mixing may have a great effect on the morphology and structure of multi-component polymer materials. Twin-screw extruders (TSE) are widely used as mixers/reactors for blending, compounding, and reactive processing. This work aimed at developing a new instrument to measure in real time the residence time distribution (RTD) which characterizes the axial mixing and transport abilities of different screw elements based on the analysis of the transient flow pattern and systematic evaluation of mixing theory in TSE. Distributive mixing of polymer melts is characterized by the generation of interfacial area, which is experimentally much more difficult to measure. This 3D numerical simulation based on CFD is adopted
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Etudes théoriques et expérimentales de la processabilité du polyéthylène à ultra-haute masse molaire / Theoretical and experimental studies of the processability of ultra-high molecular weight polyethyleneGai, Jing-Gang 16 July 2009 (has links)
Aujourd’hui le développement de nouveaux matériaux polymères ayant de bonnes propriétés repose de plus en plus sur des procédés de mélange ou de compoundage de polymères au lieu de recourir à la synthèse de nouvelles molécules. L’action du mélange peut fortement influer sur la morphologie des matériaux polymères multi-constituants. Les extrudeuses bi-vis (TSE) sont souvent utilisées comme mélangeurs/réacteurs pour des procédés de mélange, de compoundage et d’extrusion réactive. Cependant, l’étude sur la qualité du mélange dans les TSE demeure un grand défi en raison de la complexité géométrique et du caractère transitoire de l’écoulement. Cette thèse a pour objet de développer un nouvel instrument en line pour mesurer en temps réel la distribution des temps de séjour (DTS) qui caractérise la performance du mélange axial et la capacité de convoyage de différents types d’éléments de vis basées sur l’analyse de l’écoulement transitoire et l’évaluation systématique de la théorie de mélange dans les TSE. Le mélange distributif des polymères fondus est caractérisé par la génération de l’aire des interfaces, un paramètre difficile à mesurer expérimentalement. Alors on fait appel à des simulations numériques de type CFD / The development of new materials with improved properties seems to rely nowadays more on blending and compounding than on the synthesis of chemically new polymers. Mixing may have a great effect on the morphology and structure of multi-component polymer materials. Twin-screw extruders (TSE) are widely used as mixers/reactors for blending, compounding, and reactive processing. This work aimed at developing a new instrument to measure in real time the residence time distribution (RTD) which characterizes the axial mixing and transport abilities of different screw elements based on the analysis of the transient flow pattern and systematic evaluation of mixing theory in TSE. Distributive mixing of polymer melts is characterized by the generation of interfacial area, which is experimentally much more difficult to measure. This 3D numerical simulation based on CFD is adopted
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La distribution adipeuse en lien avec le métabolisme du glucose et de l'insuline chez les femmes obèses post-ménopauséesTousignant, Benoit January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
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Analýza a porovnání BI nástrojů společností Microsoft a Oracle / Analysis and comparison of BI tools from Microsoft and OracleSrnský, Martin January 2010 (has links)
The aim of this thesis is to analyze the global market with Business Intelligence, recognize the most significant companies running a business in this area and try to estimate the future trends and development of the market and then to analyze BI tools of two important companies on the market, Microsoft and Oracle. Analysis and comparison of these tools will be done according to specified metrics, which will focus on both technological and business features of the tools. The main contribution should be complex comparison of quality of tools from two big competitors on the market.
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[en] BILINGUALITY MEASUREMENT: A PROPOSE / [pt] MEDIDAS DE BILINGUALIDADE: UMA PROPOSTAANA CLAUDIA PETERS SALGADO 29 December 2008 (has links)
[pt] O presente estudo propõe uma metodologia para medir graus de
bilingualidade. A proposta é tentar quantificar esse
conceito. Considerando que o
comportamento bilíngüe não deve ser descrito como um aspecto
universalista ou
essencialista do indivíduo bilíngüe, os conhecimentos
objetivos de estatística ou
de probabilidade e as metodologias formais de coletas de
dados, por exemplo, não
contemplam os aspectos subjetivos e contextuais de
manifestações bilíngües. A
ortodoxia e inflexibilidade das metodologias disponíveis não
conseguem
apreender a fluidez de um conceito como bilingualidade.
Nossa questão é mostrar
que a lógica fuzzy apresenta-se como uma possível ferramenta
de medida porque
leva em consideração as percepções individuais e as
experiência culturais do
observador/pesquisador quando este tenta definir o que
constitui o fenômeno
observado. A verdade de qualquer afirmação se torna uma
questão de gradação. A
metodologia usada foi: 1) gravação e transcrição de
entrevista com indivíduos
bilíngües; 2) seleção das narrativas de histórias de vida
presentes nas entrevistas;
3) identificação das variáveis relevantes para a análise; 4)
análise das
bilingualidades dos indivíduos usando a Fuzzy Logic Toolbox
do software
MATLAB. As bilingualidades dos indivíduos são analisadas nos
contextos
familiar, social e profissional. Um aspecto importante a ser
considerado é que,
devido à fluidez da bilingualidade, fatores diferentes e
variáveis múltiplas
concorrem para configurar uma análise de manifestações de
bilingüismo. Assim,
conseguimos mostrar matematicamente, através do uso da
lógica fuzzy, o que
conhecemos com base em nossa experiência de vida: um mesmo
indivíduo
apresenta diferentes graus de bilingualidade em diferentes
contextos sociais. Da
mesma forma, comprovamos que em um mesmo contexto social, um
mesmo
indivíduo pode apresentar diferentes graus de
bilingualidade, dependendo do
estágio de vida em que se encontra. / [en] This study proposes a methodology to evaluate degrees of
bilinguality. The
objective is to quantify the concept bilinguality.
Considering that the bilingual
behavior should not be taken as one`s universalist or
essentialist aspect, objective
knowledge of statistics and probability, and formal
methodology of data
gathering, for example, do not cope with the subjective and
contextual aspects of
the bilingual manifestations. The orthodoxy and
inflexibility of the available
methodologies can not apprehend such a fluid concept as
bilinguality. The
propose of this study is to present Fuzzy Logic as a
possible tool to measure
bilinguality for it takes into account the
observer/researcher`s individual
perceptions and cultural experience for defining what
constitutes the observed
phenomenon. The truth of any affirmation is a matter of
gradation. The
methodology used was: 1) recording and transcription of
interviews with bilingual
individuals; 2) selection of life story narratives inside
these interviews; 3)
identification of the relevant variables for the analysis;
4) analysis of bilinguality
using Fuzzy Logic Toolbox in MATLAB. The bilinguality of the
individuals is
analyzed in real everyday life situations, in contexts such
as: familiar, social and
professional. An important aspect to be considered is that,
due to the fluidity of
bilinguality, different factors and multiple variables
compete to set up an analysis
of bilingualism manifestations. Thus, we could prove
mathematically, using fuzzy
logic, what we might previously know based on our life
experience: one
individual presents different degrees of bilinguality,
depending on the moment of
their life they are.
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Synthèse de groupements protecteurs photolabiles pro-fluorescents sensibles à l’excitation bi-photonique / Synthesis of two-photon sensitive pro-fluorescent photoremovable protecting groupsAbou Nakad, Elie 16 November 2018 (has links)
Les groupes protecteurs photolabile (GPP) ont été largement utilisés en synthèse organique et pour des applications biologiques. Parmi la grande diversité de ces groupes, les groupement o-nitrobenzyl sont les plus utilisés. En particulier, ils ont été abondamment employés dans la préparation de nombreux précurseurs photolabiles d’effecteurs biologiques. Ce qui permet d’utiliser une réaction photochimique afin de transformer un composé biologiquement inerte en composé actif avec formation d’un sous-produit de photolyse. Afin de pouvoir quantifier le saut de concentration de l’effecteur biologique en particulier sur des cellules, nous avons développé des nouveaux GPP dérivés d’o-nitrobenzyle, qui libère un sous-produit de photolyse présentant des propriétés de fluorescence. Ainsi en nous basant sur le mécanisme de photolyse de dérivés o-nitrobenzyl sensible à l’excitation bi-photonique, nous avons pu concevoir un GPP non-fluorescent qui libère un fluorophore après photoclivage. Les propriétés de fluorescence du sous-produit de photolyse ont également été optimisées. Enfin à l’aide de ces PPG pro-fluorescent nous avons pu valider que la réaction photolytique peut être suivie par microscopie de fluorescence sur des cellules en culture. / Photoremovable Protecting Groups (PPG) have been widely used in organic synthesis and in various biological applications. Among the wide diversity of these groups, o-nitrobenzyl groups are the mostly used chromophores. In particular, they have been extensively used for the design of caged compounds. Those latter type of compounds are able to release a biological effector together with an uncaging side-product leading to the spatiotemporal control of various biological processes. In order to acutely monitor the uncaging event for example in cells, we developed new PPGs, based on o-nitrobenzylderivatives, able to release a fluorescent side product. Based on the photolytical mechanism of two-photon sensitive o-nitrobenzyl PPGs, we were able to design new non-fluorescent PPGs able to release fluorophores as side products. We were also able to tune the fluorescent properties of the photo-released by product using molecular engineering. Finally, those pro-fluorescent PPGs have been used in order to follow the uncaging events by fluorescent microscopy on cell cultures.
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Mistura de ondas em meio Kerr e bi-estabilidade óptica em filmes / Four wave mixing in Kerr medium and optical bistability in thin filmsGouveia, Evandro Jose Tavares de Araujo 11 February 1992 (has links)
Desenvolvemos um modelo teórico para tratar a mistura de várias ondas em meios absorvedores saturáveis, considerando a auto-difração de duas ondas incidentes numa grade de população, a qual é induzida no meio não-linear. O modelo foi investigado através de resultados experimentais observados em rubi (Al2O3:Cr3+), alexandrita (BeAl2O4:Cr3+) e GdAlO3: Cr3+. Demonstramos, pela primeira vez, transferência de energia por mistura não degenerada de duas ondas (NDTWM) em alexandrita e GdAlO3: Cr3+. Neste ultimo, também observamos a difração de primeira ordem do feixe forte e medimos a variação de sua intensidade com relação a velocidade de deslocamento da grade. No GdAlO3: Cr3+, medimos o espectro de absorção do estado excitado e o espectro da parte real do índice de refração não-linear em quatro linhas do laser de argônio e na região de 560-620 nm de um laser de corante operando com rodamina 6G. Os resultados indicam uma interação entre pares de cromo no estado excitado, seguida da absorção de um fóton, a qual pode explicar a variação da parte imaginaria n2 com a intensidade, conforme observado experimentalmente. Nós tentamos observar bi-estabilidade óptica em GdAlO3: Cr3+ mas não tivemos êxito, provavelmente por causa de efeitos transversais e também pelo aumento da absorção com a intensidade. Por outro lado, observamos um regime multi-estável numa cavidade Fabry-Perot vazia, onde o meio não-linear é o material usado na fabricação dos espelhos, que no caso foi o ZrO2. Também observamos comportamento multi-estável em filtros de inconel, causado pelo acoplamento termo-óptico entre o filtro e a radiação laser. / We have developed a new approach to deal with multi-wave mixing in saturable absorbing media, by considering the self diffraction of two incident waves in a population grating which is created by them in the nonlinear medium. Wehave also made experimental work on ruby (Al2O3:Cr3+), alexandrite (BeAl2O4:Cr3+) and GdAlO3: Cr3+ in order to compare with our theoretical model. We have demonstrated energy transfer by nearly degenerated two wave mixing (NDTWM) in alexandrite and GdAlO3: Cr3+ for the first time. We measured the intensity of the first order diffracted intense beam as a function of the frequency shift between the incident beams in GdAlO3: Cr3+. For this crystal, we have obtained the spectra of the excited state absorption and the real part of the nonlinear index at four wavelengths of an argon laser and in the range 560-620 nm of a rodamine 6G dye laser. These kinds of spectra had never been reported before in that material. The result seems to support our proposal of an excited chromium pair interaction with an additional photon absorption which can explain the observed variation of the imaginary part of the nonlinear Kerr index with the intensity. We tried to observe optical bistability in GdAlO3: Cr3+ but we were unsuccessful, probably due to strong transverse effects and increasing absorption with the intensity. However we observed multistable regime in empty Fabry-Perot cavities in which the mirrors were made of thin films of ZrO2 deposition. A multistable thermo-optical behavior in inconel filters was also observed.
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Proteção contra a corrosão das ligas de alumínio AA7075-T6 e AA8006-F utilizando bicamadas do tipo polianilina e camadas de cerato / Corrosion protection of AA7075-T6 and AA8006-F aluminum alloys using bi-layers based on polyaniline and cerium conversion layersBisanha, Leandro Duarte 23 January 2014 (has links)
O desenvolvimento de novos revestimentos ou métodos de proteção considerados ambientalmente amigáveis é extremamente importante para a substituição das eficientes camadas de conversão do cromo, as quais são amplamente utilizadas para proteção anticorrosiva do alumínio e suas ligas. Entre as alternativas relatadas na literatura, podemos destacar a aplicação de filmes de polianilina (PAni) e o uso de camadas de conversão de cério. Neste trabalho é proposta a utilização de revestimentos do tipo bicamadas formada pela combinação de: 1) duas camadas de polianilina ou 2) camadas de conversão de cério (depositadas pelo método electroless ou catodicamente) e filmes de PAni para proteção contra a corrosão das ligas de alumínio AA7075-T6 e AA8006-F em meio aquoso contendo íons cloreto. Nos ensaios de corrosão foram utilizados o monitoramento do potencial de circuito aberto e a polarização potenciodinâmica em meio de NaCl 0,6 mol L-1. A superfície das ligas com e sem os recobrimentos foram analisadas por microscopia óptica e microscopia eletrônica de varredura. Também foi realizado o teste de aderência dos filmes de PAni presentes nas bicamadas sobre as ligas estudadas. O revestimento bicamada composto por uma camada de filme de PAni quimicamente depositada e um filme casting de PAni apresenta excelente aderência sobre as ligas AA7075-T6 e AA8006-F e combina a proteção oferecida pelos filmes casting com a boa aderência dos filmes de PAni depositados quimicamente. O uso da bicamada de cerato electroless e PAni apresenta propriedades anticorrosivas inferiores quando comparadas ao filme de PAni aplicado diretamente sobre o substrato metálico, entretanto, o uso de cerato electroless melhora a aderência dos filmes casting de PAni sobre as ligas estudas. O uso de bicamadas formadas por cerato depositado catodicamente e PAni sobre a liga AA8006-F apresenta valores de potencial de corrosão e potencial de pite inferiores ao do filme casting de PAni aplicado diretamente sobre o substrato metálico, enquanto que para a liga AA7075-T6 foram obtidas melhores propriedades anticorrosivas quando utilizada uma camada de cerato espessa (obtida utilizando uma solução de cério contendo 8 ou 25 µL mL-1 de H2O2). / The development of new coatings or protection methods considered environmentally friendly is extremely important to replace the efficient conversion layers of chromium, which are widely used for corrosion protection of aluminum and its alloys. Among the alternative methods reported in the literature, it can be highlighted the application of polyaniline (PAni) films and the use of cerium conversion layers. This work proposes the use of bi-layers based on: 1) two layers of polyanilines or 2) combination cerium conversion layers (deposited by electroless or cathodic electrodeposition) and PAni films for corrosion protection of AA7075-T6 and AA8006-F alloys in aqueous solutions containing chloride ions. Open circuit potential and potentiodynamic polarization curves were used for the corrosion tests, which were performed in 0.6 mol L-1 NaCl solution. The surface of the alloys with and without the coatings were characterized by optical microscopy and scanning electronic microscopy. It was also performed the adhesion test of the PAni films present in the bi-layers on the studied alloys. The bi-layers formed by a layer of PAni chemically deposited and a layer of PAni film exhibited excellent adhesion to the AA7075-T6 and AA8006-F alloys and combined the protection offered by the cast film of PAni with the good adhesion of PAni chemically deposited. The use of a bi-layer formed by cerium oxides (deposited by electroless) with PAni film as coating presented lower anticorrosive properties compared to the PAni films applied directly on the substrate, however, the use of the cerium layer improves the adhesion of the PAni films on the alloys. The use of bi-layers formed by electrodeposited cerium oxides and PAni films on AA8006-F showed corrosion potential and pitting potential lower when compared with the PAni film directly applied on the substrate, whereas for AA7075-T6, the best anticorrosive properties was obtained using a thick cerium layer (cerium solution containing 8 or 25 µL mL-1 of H2O2).
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