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1
East, Georges. "Métaphysique de l'évolution : la substance, le jugement téléologique, la vie créatrice." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0024/NQ36266.pdf.
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Wolfaardt, Christel. "Disneyland : an aesthetic of postmodern consumer culture, hyperreality and semiotic content in the visual arts." Diss., University of Pretoria, 1996. http://hdl.handle.net/2263/23931.
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In this study Disneyland is analysed as a model for the creation of an aesthetic of Postmodern consumer culture, hyperreality and semiotic content. It explores Postmodern society and its visual art preferences, whilst revealing an ubiquitous aesthetic for Postmodern spectator-consumers as actors on the proverbial Postmodern stage. The various manifestations of 'Disneyfied' consumerism, hyperreality and semiotic content collectively reveal a society saturated with mass media produced imagery and messages. In this milieu, this study explores the responsibilities as well as opportunities that are presented to the artist via a Disneyland aesthetic. These include the awareness of stereotypic information in the mass media, the exercise of responsible choice over complacent spectatorship, the celebration of newly acquired imagery, as well as the discovery of richer semiotic essences that assist a society in redefining itself. The central fear of an Orwellian 'Big Brother' syndrome and entertainment or mass media bombardment, indicates a central problem in Postmodern society. In this connection, spectator-consumers are saturated with American cultural goods via imagery, mass media messages, and fabricated 'hyperrealities' which are regarded as master narratives. The final emphasis is placed on responsible choice and meditated comprehension of personal spectatorship, as well as the manifestation of the latent power of mass media in the Information Revolution era.AFRIKAANS : Hierdie studie ondersoek Disneyland as 'n model vir 'n estetiek van Postmoderne verbruikerskultuur, hiperrealiteit en semiotiese inhoude. Dit stel ondersoek in na die Postmoderne gemeenskap se spesifieke visuele kuns voorkeure, terwyl dit 'n onvermydelike estetika vir die Postmoderne toeskouer-verbruiker as protagonis in die Postmoderne milieu bied. Die onderskeie manifestasies van 'Disneyland-tipe' verbruik, hiperrealiteit en semiotiese inhoude skets 'n gemeenskap wat gelei word deur beeldmateriaal en boodskappe wat in die massa media voorkom. Hierdie arena bied vir die visuele kunstenaar sekere verantwoordelikhede en moontlikhede. Die studie weerspieel die wyse waarop die kunstenaar bewus moet bly van stereotipiese data wat in die massa media tentoongestel word, verantwoordelike keuses in plaas van blote passiewe toeskouerskap moet beoefen en nuwe jukstaplasings van beelde moet aanmoedig sodat waardevolle semiotiese essensies nuutgevonde definisie aan 'n gemeenskap kan gee. Die sentrale vrees vir Amerikaans-georienteerde media en vermaaklikheids oorheersing bly kommerwekkend in die Postmoderne gemeenskap. Toeskouer-verbruikers word deurgaans oorval met Amerikaanse kulturele goedere in die vorm van beelde, massa media boodskappe en nagemaakte hiperrealiteite. Die studie ondersteun die belangrikheid van verantwoordelike keuse en 'n begrip vir die manifestasie van die magsbeheer van die massa media in die era van die Inligtings Omwenteling.
Dissertation (MA)--University of Pretoria, 1996.
Visual Arts
Unrestricted
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East, Louise. "Les étapes d'une traduction française de la taxinomie d'adjectifs de Norman et de son application dans un contexte universitaire québécois." Master's thesis, Université Laval, 1988. http://hdl.handle.net/20.500.11794/29344.
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Hölzl, Werner, and Andreas Reinstaller. "The effect of technology and demand shocks on structural and industrial dynamics. Evidence from Austrian manufacturing." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2004. http://epub.wu.ac.at/660/1/document.pdf.
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In this paper we analyse the influence of sector specific developments in productivity and demand on net entry and employment in 19 industrial sectors of the Austrian economy. Based on the model of structural dynamics of Pasinetti, we develop an identification scheme that allows us to extract technology and demand shocks, by means of a structural vector autoregressive (SVAR) model with long-run restrictions. We study the patterns of productivity and demand shocks across industries by means of a principal components analysis and find that sectoral and macro-economic developments in demand strongly correlate, while this is not the case for technology shocks. Impulse-response analysis shows that for almost all sectors productivity growth rates experience an immediate increase to positive technology shocks while the hours worked decline as conjectured by Pasinetti. Finally, we use the identified shocks as explanatory variables in time-series cross-section regressions on net-entry and employment data. Both types of shocks are able to explain dynamics on the industry level in terms of employment and sales but not firm dynamics. (author's abstract)Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"
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East, Jocelyn. "Les dynamismes organisationnels de l'institutionnalisation du sport au Québec (1900-1967)." Doctoral thesis, Université Laval, 2002. http://hdl.handle.net/20.500.11794/28577.
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Wehinger, Gert D. "Exchange rate-based stabilization. Pleasant monetary dynamics?" Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 1997. http://epub.wu.ac.at/356/1/document.pdf.
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High inflation economies have ultimately been successful in stabilising their prices using the exchange rate as a nominal anchor. Besides stabilization, these recent examples have shown boom-recession cycles, contrary to what can be expected from (pure) money-based stabilizations. Various theoretical explanations of such boom-cycles are discussed and a model of aggregate supply and demand generating such an outcome is developed. There the boom dynamics depend mainly on a slump in real interest rates and wage flexibility. (author's abstract)Series: Department of Economics Working Paper Series
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Wehinger, Gert D. "Are exchange rate-based stabilisations expansionary? Theoretical considerations and the Brazilian case." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 1997. http://epub.wu.ac.at/1744/1/document.pdf.
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High inflation economies, especially the Latin American cases like Argentina and Brazil, have ultimately been successful in stabilising their prices using the exchange rate as a nominal anchor. Contrary to conventional wisdom inflation in these cases has not been reduced at the cost of temporary recessions, instead, they have shown positive output effects. Various theoretical explanations of such boom-cycles are discussed and a model generating such an outcome is developed. Some empirical evidence is given by the Brazilian "Real Plan" of 1994. Nevertheless, the medium and long-term effects of such programmes can result in recessions and a resumption of high inflation, although the cases show that such "postponed stabilisation costs" can be overcome by adequate and flexible supply-side policies accompanying the stabilisation programme. (author's abstract)Series: Department of Economics Working Paper Series
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Naqvi, Syed Ali Asjad. "Modeling Growth, Distribution, and the Environment in a Stock-Flow Consistent Framework." WU Vienna University of Economics and Business, 2015. http://epub.wu.ac.at/4468/1/EcolEcon_WorkingPaper_2015_2.pdf.
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Economic policy in the EU faces a trilemma of solving three challenges simultaneously - growth, distribution, and the environment. In order to assess policies that address these
issues simultaneously, economic models need to account for both sector-sector and sector-environment feedbacks within a single framework.This paper presents a multi-sectoral stock-flow consistent (SFC) macro model where a demand-driven economy consisting of multiple institutional sectors - firms, energy, households, government, and financial - interacts with the environment. The model is calibrated for the EU region and five policy scenarios are evaluated; low consumption, a capital stock damage function, carbon taxes, higher share of renewable energy, and technological shocks to productivity. Policy outcomes are tracked on overall output, unemployment, income and income distributions, energy, and emission levels. Results show that investment in mitigation technologies allows for absolute decoupling and ensures that the above three issues can be solved simultaneously. (author's abstract)Series: Ecological Economic Papers
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Naqvi, Asjad. "Modeling Growth, Distribution, and the Environment in a Stock-Flow Consistent Framework. Policy Paper no 18." European Commission, bmwfw, 2015. http://epub.wu.ac.at/4736/1/WWWforEurope_Policy_Paper_018.pdf.
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Economic policy in the EU faces a trilemma of solving three challenges simultaneously - growth, distribution, and the environment. In order to assess policies that address these issues simultaneously, economic models need to account for both sector-sector and sector-environment feedbacks within a single framework.This paper presents a multi-sectoral stock-flow consistent (SFC) macro model where a demand-driven economy consisting of multiple institutional sectors - firms, energy, households, government, and financial - interacts with the environment. The model is calibrated for the EU region and five policy scenarios are evaluated; low consumption, a capital stock damage function, carbon taxes, higher share of renewable energy, and technological shocks to productivity. Policy outcomes are tracked on overall output, unemployment, income and income distributions, energy, and emission levels. Results show that investment in mitigation technologies allows for absolute decoupling and ensures that the above three issues can be solved simultaneously.Series: WWWforEurope
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Stockhammer, Engelbert, and Özlem Onaran. "Accumulation, distribution and employment. A structural VAR approach to a Post-Keynesian Macro Model." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2002. http://epub.wu.ac.at/1220/1/document.pdf.
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The paper investigates the relation between effective demand, income distribution and unemployment empirically. Its aim is to evaluate Keynesian, Kaldorian and neoclassical hypotheses about the determination of labor market variables. To do so, a vector autoregression model consisting of capital accumulation, capacity utilization, the profit share, unemployment and the growth of labor productivity is estimated. A general post-Keynesian model following the lines of Kalecki and Kaldor is presented and provides the specification for a structural VAR. The model is estimated for the USA, UK and France. (authors' abstract)Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"
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Garcia-Hernandez, Margarita. "Systèmes luminescents BaTiO3 : Ln(Ln= Er3+, Yb3+, Eu3+) préparés par chimie douce : poudres, nanopoudres et films nanostructurés." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719196.
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Ce travail concerne, la synthèse, la caractérisation structurale, morphologique et optique de matrices de titanates de baryum (BaTiO3) activées par les ions Eu3+, Er3+ et Yb3+. Trois voies de synthèse sont étudiées : sol-gel, hydrothermale et solide. Il a été montré que la synthèse hydrothermale conduisait à des poudres nanométriques constituées de particules de 20 nm, dix fois plus petites que celles rencontrées dans les poudres obtenues par les techniques classiques de céramisation. L' influence de ce paramètre sur la structure cristallographique des titanates a pu être mise en évidence. L'ajout d'agents chélatants au cours de la synthèse sol-gel permet de modifier la morphologie des poudres et de stabiliser les sols destinés à l'élaboration de revêtements. Des films épais monocouche ( 800 nm) de titanates de baryum dopés Er3+ et Eu3+ ont été ainsi obtenus. Une étude des propriétés optiques des ions de terres rares dans les différents systèmes synthétisés a été menée en enregistrant les différents spectres d'exitation et d'émission. Les phénomènes de transfert d'énergie entre les ions de terres rares ont été étudiés dans les matrices co-dopées
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LIMA, Bismarck Costa. "Estudo da conversão descendente de frequência com íons de Tb3+/Yb3+ , Eu3+ e Er3+ para aplicações fotovoltaicas." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16118.
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CAPES, CNPq, FACEPE
C elulas solares apresentam-se como uma alternativa vi avel para a gera c~ao de energia limpa e renov avel pela sua capacidade de convers~ao da energia solar em el etrica atrav es do efeito fotovoltaico. Entretanto, um dos fatores limitantes na utiliza c~ao deste tipo de energia tem sido a incompatibilidade espectral, a qual implica que apenas uma determinada parte do espectro solar seja efetivamente utilizado no processo de convers~ao fotovoltaica. Entre os diversos materiais fot^onicos, pesquisas em materiais dopados com ons de Terras Raras capazes de realizar a convers~ao de f otons de infravermelho para vis vel-UV ou vice-versa tem sido realizadas. Em aplica c~oes fotovoltaicas, este efeito pode melhorar a coleta da radia c~ao solar. Para a realiza c~ao desta tarefa dois mecanismos s~ao utilizados: Convers~ao Ascendente de Frequ^encia e Convers~ao Descendente de Frequ^encia. Este trabalho teve como objetivo estudar as propriedades espectrosc opicas e o mecanismo de Convers~ao Descendente de Frequ^encia em vidros dopados com os ons de Terras Raras Tb3+/Yb3+, Eu3+ e Er3+, e veri car suas poss veis aplica c~oes no melhoramento da e ci^encia de c elulas solares. A mesma matriz hospedeira foi utilizada. O estudo das propriedades espectrosc opicas foi realizado atrav es de medidas de absor c~ao, luminesc^encia e evolu c~ao temporal da luminesc^encia. Observamos o processo de convers~ao descendente de frequ^encia com emiss~ao no infravermelho, regi~ao que as c elulas solares de sil cio cristalino possuem maior e ci^encia, com excita c~ao em 355nm, que promoveu uma maior e ci^encia, e 482nm. Em seguida, para as matrizes dopadas com ons de Tb3+/Yb3+, foi determinado o mecanismo gerador do processo de convers~ao descendente de frequ^encia e a e ci^encia de transfer^encia de energia. Foi obtida uma e ci^encia de transfer^ encia de energia m axima de 112,7%. Para as matrizes dopadas com Eu3+ e Er3+ foram realizadas medidas de luminesc^encia com excita c~ao via laser de 482nm. Como aplica c~ao, foram realizadas medidas el etricas, para c elulas convencionais de Si e GaP, usando como fonte de radia c~ao um simulador solar com ltro AM 1.5. Os resultados foram avaliadas na presen ca e aus^encia dos vidros dopados com ons de Terras Raras na superf cie da c elula solar. Foi observado um aumento na e ci^encia de convers~ao fotovoltaica das c elulas de sil cio cobertas pelos vidros dopadas com 1%Tb3+ e 1%Eu3+ em rela c~ao a matriz sem dopagem.
Solar cells are shown as a viable alternative for generation renewable and clean energy due their ability of converter solar power in electric power by the photovoltaic e ect. However, one of the limitant facts to use photovoltaic devices to make electricity is spectral mismatch, that implies only a speci c range of solar spectrum is e ectively used in the process of photovoltaic conversion. Between the several photonics devices, research in Rare Earth ions doped materials able to do the conversion of infrared photons in visible-UV photons or the opposite have been performed. In photovoltaic applications, this e ect can enhance the harvesting of solar light. To realize this task two mechanism are used: Frequency up-conversion and frequency down-conversion. This work had the goal of study the spectroscopic properties and the Frequency Down-conversion mechanism in Tb3+/Yb3+, Eu3+ and Er3+ Rare Earth doped glasses, and check their possible applications to enhance solar cell e ciency. The same host matrix are used. The spectroscopic study was realized by luminescence, absorption, and temporal evolution luminescence measurements. We observe the frequency down-conversion and infrared emission, zone that crystaline silicon solar cell have the best e ciency, with 355nm excitation, that promote the best e ciency, and 482nm excitation. Then, for host matrix doped with Tb3+/Yb3+ ions, was determined the generation mechanism of frequency down-conversion and energy transfer e ciency. The major energy transfer e ciency was 112,7%. For host matriz doped with Eu3+ and Er3+ ions, was realized luminescence measurements with 482nm excitaion. Was realized electric measurements as applications in Si and GaP cells, solar simulator with AM 1.5 lter was used as radiation source. The results were evaluated with and without Rare Earth ions doped glasses on the surface of solar cell. We observed the enhancement of photovoltaic conversion when the silicon solar cell are covered with by glasses doped with 1%Tb3+ and 1%Eu3+ with respect to matrix covered.
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Halambalakis, Georgios. "Optical and structural properties of Tm3+, Eu3+ and Er3+ doped GaN thin films grown by MBE technology." Montpellier 2, 2005. http://www.theses.fr/2005MON20045.
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Les propriétés optiques des couches épitaxiées de GaN dopées aux terres rares ont attiré l'attention pour des applications optoélectroniques tels que la signalisation, [la] lumière blanche et [les] communications optiques. Nous avons étudié les propriétés optiques et structurales des couches minces de GaN dopées aux terres rares (Er3+, Eu3+, Tm3+), réalisées par GSMBE (Gas Source Molecular Beam Epitaxy). La totalité du spectre de la lumière visible a été observé, du GaN:Eu (Rouge : 622 nm) au GaN:Tm (Bleu : 477 nm), en passant par le GaN:Er (Vert : 537 nm, 558 nm). La diffraction de rayons X a été utilisée pour étudier la qualité cristalline des couches. La microscopie électronique en transmission (TEM) a été utilisée pour étudier les défauts dus à l'incorporation d'ions de terres rares dans la matrice de GaN. Des mesures AFM ont aussi été utilisées pour étudier les effets de la température de croissance et de la concentration de terres rares sur la morphologie de la surface des couches dopées. Les études structurales sur les couches de GaN dopées aux terres rares ont montré que les défauts participent au mécanisme de transfert d'énergie de la matrice vers les ions de terres rares, ce qui accroît l'émission de lumière relative aux transitions intra-4f des terres rares, observées par photoluminescence.
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Onaran, Özlem, and Engelbert Stockhammer. "Do profits affect investment and employment? An empirical test based on the Bhaduri-Marglin model." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2005. http://epub.wu.ac.at/1534/1/document.pdf.
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In this study, a Kaleckian-Post-Keynesian macroeconomic model, which is an extended version of the Bhaduri and Marglin (1990) model, serves as the starting point. The merit of a Kaleckian model for our purposes is that it highlights the dual function of wages as a component of aggregate demand as well as a cost item as opposed to the mainstream economics, which perceive wages merely as a cost item. Depending on the relative magnitude of these two effects, Kaleckian models distinguish between profit-led and wage-led regimes, where the latter is defined as a low rate of accumulation being caused by a high profit share. Are actual economies wage-led or profit-led? Current orthodoxy implicitly assumes that they are profit-led, and thus supports the neoliberal policy agenda. The purpose of the paper is to carry this discussion into the empirical terrain, and to test whether accumulation and employment are profit-led in two groups of countries. We do so by means of a structural vector autoregression (VAR) model. The model is estimated for USA, UK and France to represent the major developed countries, and for Turkey and Korea to represent developing countries. The latter are chosen since they represent two different export-oriented growth experiences. The results of the adjustment experiences of both countries are in striking contrast to orthodox theory, however they also present counter-examples to each other in terms of their ways of integrating into the world economy. (author's abstract)Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"
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Garcia-Hernandez, Margarita. "Luminescent systems of Ln (Ln=Er3+, Yb3+ , Eu3+) doped BaTiO3 nanostructured powders and films prepared by soft chemical routes." Clermont-Ferrand 2, 2010. http://www.theses.fr/2010CLF22040.
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Ce travail concerne, la synthèse, la caractérisation structurale, morphologique et optique de matrices de titanates de baryum (BaTiO3) activées par les ions Eu3+, Er3+ et Yb3+. Trois voies de synthèse sont étudiées : sol-gel, hydrothermale et solide. Il a été montré que la synthèse hydrothermale conduisait à des poudres nanométriques constituées de particules de 20 nm, dix fois plus petites que celles rencontrées dans les poudres obtenues par les techniques classiques de céramisation. L' influence de ce paramètre sur la structure cristallographique des titanates a pu être mise en évidence. L'ajout d'agents chélatants au cours de la synthèse sol-gel permet de modifier la morphologie des poudres et de stabiliser les sols destinés à l'élaboration de revêtements. Des films épais monocouche ( 800 nm) de titanates de baryum dopés Er3+ et Eu3+ ont été ainsi obtenus. Une étude des propriétés optiques des ions de terres rares dans les différents systèmes synthétisés a été menée en enregistrant les différents spectres d'exitation et d'émission. Les phénomènes de transfert d'énergie entre les ions de terres rares ont été étudiés dans les matrices co-dopées
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Bodiou, Loic. "Etude des mécanismes d'excitation et d'émission de couches minces de GaN dopées Eu3+, Er3+ et Tm3+ pour nouveaux dispositifs électroluminescents." Phd thesis, Université de Caen, 2007. http://tel.archives-ouvertes.fr/tel-00324656.
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Cette thèse porte sur les mécanismes d'excitation et d'émission des couches minces de nitrure de gallium dopées par des ions de terre rare (Eu3+, Er3+ et Tm3+) suite à une excitation optique (photoluminescence) ou électrique (électroluminescence) du matériau semi-conducteur.A l'intérieur du GaN, deux catégories de site d'incorporation d'ions de terre rare peuvent être distinguées, à savoir les ions de terre rare "isolés" (c'est-à-dire ne contenant aucun défaut dans leur voisinage) et les complexes associant un ion de terre rare avec un piège, celui-ci pouvant provenir du dopage lui-même ou d'un défaut cristallin. L'excitation non-résonante est réservée au second type de centres et a lieu par transfert d'énergie lors de la recombinaison non radiative d'un exciton lié sur un piège proche de la terre rare.
La comparaison d'échantillons de GaN dopés in situ et par implantation ionique par l'ion Eu3+ montre que ces films présentent chacun deux types de complexes "Eu3+-piège" dont l'un est commun à tous les échantillons. Les différences d'efficacité d'excitation respectives des deux complexes s'expliquent par la proximité du piège correspondant.
Grâce à des expériences pompe-sonde combinant des lasers impulsionnel et continu, le chemin d'excitation des ions de terre rare est confirmé expérimentalement et deux des mécanismes d'extinction de leur luminescence (la photo-ionisation de pièges et l'effet Auger avec des porteurs libres) sont étudiés.
L'excitation électrique du GaN:Er3+ est également présentée. Les études en fonction de la température, du courant parcourant l'échantillon ou de la tension de polarisation mettent en évidence l'excitation par impact des ions de terre rare.
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Bahtat, Abdelhalim. "Elaboration et étude spectroscopique de couches minces de TiO2 optiquement guidantes : rôle du dopage par les ions Eu3+ et Er3+." Lyon 1, 1996. http://www.theses.fr/1996LYO10013.
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Le present travail est consacre a l'etude de guides d'ondes planaires d'oxyde de titane (tio#2), dopes avec des ions erbium et europium, fabriques par le procede sol-gel. La synthese du sol precurseur de tio#2 ainsi que le protocole utilise pour le depot des couches sont decrits en detail. Les proprietes de guidage, obtenues des une temperature d'elaboration relativement basse (100 c), sont utilisees pour suivre la densification de ces guides et pour la determination de leur coefficient d'attenuation. Les parametres optogeometriques (indice de refraction et epaisseur) sont determines par spectroscopie des lignes noires. La rugosite de surface est mise en evidence par microscopie a force atomique (afm). La potentialite du procede sol-gel dans le domaine de l'optique integree est illustree par le matricage de microstructures (reseaux) dans les guides de tio#2. La technique de spectroscopie raman en configuration guidee, est utilisee pour l'etude de la densification de ces guides, notamment pour suivre le processus de cristallisation. Dans le meme but, le dopage avec des ions europium trivalents fournit une information plus locale. Enfin, les proprietes spectroscopiques (fluorescence et durees de vie) de l'ion erbium dans les guides de tio#2, sont etudiees en fonction du taux de dopage (0,1 a 15%) et de la temperature de recuit: l'emission de fluorescence a 1,5 m (#4i#1#3#/#2#4i#1#5#/#2) ainsi que celle de up-conversion sont analysees en configuration guidee. L'influence des groupements hydroxyles sur les declins de fluorescence est suffisamment reduite par un traitement des couches a 600 c. A cette temperature, le maximum de la duree de vie du niveau #4i#1#3#/#2 (4 ms) est atteint dans le cas des guides dopes a 0,1% en ion erbium. Les declins de fluorescence sont ensuite analyses dans l'approximation de judd-ofelt
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Krömmelbein, Natascha [Verfasser]. "Analyse der Cytomegalovirus-Infektion in Adenovirus Typ 5 E1A/E1B-transformierten Zellen zur Entwicklung eines Zellsubstrats für die Impfstoffproduktion / Natascha Krömmelbein." Mainz : Universitätsbibliothek Mainz, 2016. http://d-nb.info/1112153306/34.
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Remonte, Ádamo Rossano Vicentini. "Síntese e caracterização de nanocompósitos vitrocerâmicos transparentes a base de SiO2-ZrO2 dopados com íons Eu3+ e Er3+ via processo sol-gel." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-26052009-165942/.
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A preparação de vitrocerâmicas transparentes a base de SiO2-ZrO2 dopado com íons Eu3+ e Er3+ através da metodologia sol-gel foi o objetivo desta dissertação. São apresentados resultados estruturais e óticos deste sistema, em função de temperatura, tempo e composição (variando-se a concentração de zircônia). Os sóis foram preparados em meio ácido e deixados em repouso até evaporação total do solvente, obtendo-se assim monolitos amorfos, os quais foram submetidos a tratamentos a 900, 1000 e 1100ºC durante 2, 4 e 8 horas visando eliminação de resíduos orgânicos, moléculas de água, grupos hidroxilas e densificação do material. O processo de densificação com os tratamentos leva a formação inicial da fase tetragonal de ZrO2. Foi observado o crescimento de nanopartículas de ZrO2 com dimensão dependente do tempo e temperatura de tratamento térmico, além da composição do nanocompósito. As nanopartículas obtidas apresentam tamanho que variam entre 3,1 a 5,5 nm, observadas por microscopia eletrônica de transmissão. A partir da adição de 20% de óxido de zircônio é possível observar uma mistura de fases entre tetragonal e monoclínica, resultado este evidenciado principalmente por espectroscopia Raman. Neste trabalho, o íon Eu3+ foi usado como sonda estrutural e um possível luminóforo na região do vermelho. Íons lantanídeos encontram-se parcialmente distribuídos na rede amorfa à base de sílica, apresentando um tempo de vida do 5D0 de 1,5 ms e em óxido de zircônio, com um tempo de vida de 2,7 ms. À medida que ocorre cristalização, aumenta-se a proporção de íons no óxido de zircônio, sugerindo que os íons lantanídeos preferencialmente encontram-se distribuídos em regiões ricas de ZrO2. Todas as amostras dopadas com íons Er3+ apresentam emissão no infravermelho próximo, na região da banda C utilizada em telecomunicações. A emissão do íon Er3+ em 1532 nm, atribuída à transição 4I13/2 4I15/2, apresentou uma largura a meia altura que variou entre 29 a 56 nm, dependendo da composição e do tratamento térmico realizado. O tempo de vida (1/e) do estado excitado 4I13/2 é de 5,3 ms a 6,5 ms dependendo do tratamento térmico.The preparation of transparent glass-ceramic based on the SiO2-ZrO2 doped with Eu3+ and Er3+ ions by the sol-gel methodology was the aim of this work. The structural and optical properties of the systems as a function of the time and temperature of annealing and also zirconium concentration are presented. The sol was prepared in acid solution and left in rest until total evaporation solvent, to obtaining the amorphous monoliths. The follow, the growthing of ZrO2 nanoparticles were induced and by the Transmission Electron Microscopy sizes between 3.1 and 5.5 nm were observed to be dependent to the time and temperature of annealing. The densification from the annealing at 900, 1000 and 1100ºC initially takes the formation of the tetragonal phase of ZrO2, and after 20 mol% of zirconium oxide is observed a mixture of phases between the tetragonal and monoclinic phase, result this evidenced by Raman spectroscopy. In this work the Eu3+ ion was used as a structural and possible luminescent material in the red region, displaying a life time value between 1.4 - 2.3 ms, for samples contend 0.3 mol% of Eu3+. The life time values increases as a function of time and temperature of annealing due the increase of the crystallinity of material that decreases the sites number of Eu3+ ions on the system. The Er3+ ions emission assigned to 4I13/2 4I15/2 localized around 1532 nm, showed a full width half maximum between 29 and 56 nm. The lifetime measurements were realized for Er3+ ions. The larger values of lifetime obtained are correspondent to samples with less crystalinity. Samples annealed in less temperatures show 5.3 ms of lifetime while samples annealed in higher temperatures show 6.5 ms of lifetime.
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Bodiou, Loïc. "Etude des mécanismes d’excitation et d’émission de couches minces de nitrure de gallium dopées Eu3+, Er3+ et Tm3+ pour nouveaux dispositifs électroluminescents." Caen, 2007. http://www.theses.fr/2007CAEN2039.
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Cette thèse porte sur les mécanismes d’excitation et d’émission des couches minces de nitrure de gallium dopées par des ions de terre rare (Eu3+, Er3+ et Tm3+) suite à une excitation optique (photoluminescence) ou électrique (électroluminescence) du matériau semi-conducteur. A l’intérieur du GaN, deux catégories de site d’incorporation d’ions de terre rare peuvent être distinguées, à savoir les ions de terre rare "isolés" (c’est-à-dire ne contenant aucun défaut dans leur voisinage) et les complexes associant un ion de terre rare avec un piège, celui-ci pouvant provenir du dopage lui-même ou d’un défaut cristallin. L’excitation non-résonante est réservée au second type de centres et a lieu par transfert d’énergie lors de la recombinaison non radiative d’un exciton lié sur un piège proche de la terre rare. La comparaison d’échantillons de GaN dopés in situ et par implantation ionique par l’ion Eu3+ montre que ces films présentent chacun deux types de complexes "Eu3+-piège" dont l’un est commun à tous les échantillons. Les différences d’efficacité d’excitation respectives des deux complexes s’expliquent par la proximité du piège correspondant. Grâce à des expériences pompe-sonde combinant des lasers impulsionnel et continu, le chemin d’excitation des ions de terre rare est confirmé expérimentalement et deux des mécanismes d’extinction de leur luminescence (la photo-ionisation de pièges et l’effet Auger avec des porteurs libres) sont étudiés. L’excitation électrique du GaN:Er3+ est également présentée. Les études en fonction de la température, du courant parcourant l’échantillon ou de la tension de polarisation mettent en évidence l’excitation par impact des ions de terre rareThe PhD dissertation is devoted to the understanding of the excitation and quenching mechanisms of rare-earth (Eu3+, Er3+ and Tm3+) doped gallium nitride thin films. Rare-earth doping of GaN thin films results in two different types of incorporation sites for rare-earth ions: "isolated" ions (without any defect in their vicinity) and "rare-earth - trap" complexes. This trap can originate from the lattice distortion induced by the doping itself or from defects. Non-resonant excitation is reserved to this second kind of centres and occurs by energy transfer arising from the non radiative recombination of an exciton trapped in the vicinity of the rare-earth ion. Eu-implanted and in situ doped gallium nitride samples have been compared. Each presents two optically active "rare-earth - trap" complexes, one of which is common to all samples. Excitation efficiency differences between these complexes are found to be dependent on the distance between the trap and the rare-earth ion. Pump-probe experiments confirm experimentally the excitation path towards rare-earth ions and allow the study two quenching mechanisms namely photo-ionisation of traps and Auger effect with free carriers. Electroluminescence of GaN:Er3+ is also presented. Temperature, current and voltage dependant measurements indicate that electrical excitation of rare-earth ions take place by impact excitation
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Lukmanova, Elizaveta, and Katrin Rabitsch. "New VAR evidence on monetary transmission channels: temporary interest rate versus inflation target shocks." WU Vienna University of Economics and Business, 2018. http://epub.wu.ac.at/6681/1/wp274.pdf.
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We augment a standard monetary VAR on output growth, inflation and the nominal interest rate with the central bank's inflation target, which we estimate from a New Keynesian DSGE model. Inflation target shocks give rise to a simultaneous increase in inflation and the nominal interest rate in the short run, at no output expense, which stands at the center of an active current debate on the Neo-Fisher effect. In addition, accounting for persistent monetary policy changes reflected in inflation target changes improves identification of a standard temporary nominal interest rate shock in that it strongly alleviates the price puzzle.Series: Department of Economics Working Paper Series
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Glockzin, Gabriel. "Molekulare Expressionsanalyse und Replikationskinetik des rekombinanten E1-, E3-deletierten adenoviralen Vektors AdYB-1." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978929659.
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Smithin, John. "The rate of interest, economic growth, and inflation. An alternative theoretical perspective." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2002. http://epub.wu.ac.at/1458/1/document.pdf.
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The premise of this paper is that in a monetary production economy, policy decisions of the central bank, or more generally the 'monetary authority', set the tone not only for nominal interest rates but also for 'real' interest rates defined in the usual way. This is a different question than that of which institution(s) acquire the status of monetary authority at any particular stage of socioeconomic or technological development. Rather the suggestion is that the existence of some such social structure is a prerequisite if anything resembling capitalist monetary production is to be viable. The paper demonstrates that a coherent macroeconomic theory can be elaborated on this basis, including an explanation of economic growth, the business cycle, inflation, the functional distribution of income, the 'Keynesian' problem of the impact of demand growth on economic growth, endogenous money, cumulative causation, and endogenous technical change. (author's abstract)Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"
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Tumanov, Aleksandr. "E11 invariant field theories." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/e11-invariant-field-theories(ef80bfeb-8d8f-41d8-8815-a2159eb2c242).html.
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It has been proposed that the low energy e↵ective action of the theory of strings and branes possesses a large symmetry described by the Kac-Moody algebra E11. The non-linear realisation of this algebra and its vector representation determines the fields and coordinates of the theory, as well as the equations that describe their dynamics. In order to construct the generators of E11 algebra it is split into representations of its GL(d) ⇥ E11−d subalgebra. Here d is an integer that determines the dimension of the corresponding E11 theory. The low levels of the non-linear realisation contain the set of equations of the supergravity theory in corresponding space-time dimension, while the higher levels introduce an infinite number of fields that are connected to the supergravity ones via a chain of duality relations, as well as standalone fields that have no counterparts in standard supergravity theory. In this thesis we derive the set of commutators of E11 algebra and its vector representation up to a certain level in five and ten-dimensional cases. We use the non-linear realisation approach to construct the generalised vielbein and the Cartan forms of the E11 theory in four, five, ten and eleven dimensions. We then build a set of E11 invariant equations in five and eleven-dimensional theories from the non-linear realisation of E11. The low level equations, when appropriately truncated, are shown to perfectly reproduce the dynamics of the standard supergravity theories in corresponding dimensions. The dynamics of certain higher level fields are considered, including the dual graviton field and an eleven-dimensional field that, when reduced to ten dimensions, gives rise to the Romans mass term in type IIA theory. Lastly, we describe the non-linear realisation of very extended A1 algebra, called A+++ 1 , together with its commutators, Cartan forms and generalised vielbein.
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Markson, Gabriel Benjamin. "A systematic analysis of the E1, E2, and E3 interactions within the human protein ubiquitination system." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612409.
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Williams, Diane Keith. "Particle Size Dependence on the Luminescence Spectra of Eu3+:Y2O3 and Eu3+:CaO." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29719.
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Since the Eu3+ ion can occupy different cation sites in a host material, it can serve as a useful probe of nanocrystalline structures to gain more insight into the structural changes that can occur when the particle size is reduced from the bulk to nanometer regime. The use of laser spectroscopy to probe two nanocrystalline structures, Eu3+:Y2O3 and Eu3+:CaO, was investigated. The nanocrystalline structures were prepared by the laser-vaporization-gas-phase condensation of the bulk oxides. The particle size distribution and dominant particle diameters of the nanocrystals were determined by transmission electron microscopy.
The particle size dependency results of Eu3+:Y2O3 revealed three distinct phases: (1) the sharp lines of the monoclinic Y2O3 were dominant in the larger particles; (2) the C2 site of the cubic phase, which appears in the smaller particles; and (3) the amorphous phase that increases in intensity as the particle size decreases. The observation of distinct spectral lines from the monoclinic phase confirms the presence of a crystalline phase for all of particle sizes studied.
The site-selective results of various concentrations of 13-nm Eu3+:CaO showed that the laser-vaporization-gas-phase condensation method of preparation produced two europium-containing phases at most concentrations: cubic CaO and monoclinic Eu2O3. Results showed that the monoclinic Eu2O3 phase could be reduced by 95% by annealing at 800 0C for 30 minutes without particle growth.
Since the Eu3+ ion and the Y3+ ion are isovalent, the substitution of a Eu3+ ion into Y2O3 is considered a trivial case of extrinsic disorder since the impurity is neutral relative to a perfect crystal1. As a result, it is not necessary to have any other defects present in the crystals to maintain charge neutrality. With Eu3+:CaO, the dopant and host cation charges are different and therefore the dopant distribution can be investigated by site-selective spectroscopy.
Since the experimental dopant distribution results for nanocrystalline Eu3+:CaO were inconclusive, a model to predict the theoretical change in the dopant distribution in Eu3+:CaO as a function of particle size was developed. The model predicts that the defect chemistry is affected when the particle size is approximately 50 nm and smaller.Ph. D.
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Fógia, Michelly Patrícia Santana de Almeida. "Síntese e caracterização de materiais do sistema ternário SiO2-ZnO-TiO2 obtido por sol-gel/Pechini." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4390.
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In this work the structural and optical properties of SiO2-ZnO-TiO2 system doped with of Eu3+ (1% in mol) or Er3+ ions (0,2% to 2,0% in mol) were investigated. The compositions xSiO2-([100-x]/2)ZnO-([100-x]/2)TiO2 with x ranging from 40 to 80 were synthesized and studied. A mixed methodology using the traditional sol-gel process and Pechini method was employed to prepare stable and transparent sols, homogeneous gels, powders and transparent thin films without cracks. The prepared powders were heat treated from 100°C to 1100°C. The optical “band gap” values, the lifetime of Eu3+ 5D0 level, the R/O ratio of Eu3+ emissions and refractive index are dependent on the composition and thermal treatment of the powders. Multilayered thin films were deposited onto silica substrates using the “spin coating” technique. Afterwards, the as-prepared thin films were calcined at 500°C followed by annealings from 700°C to 1000°C. The X-ray diffraction of powders showed that the crystallization starts at 800°C with a mixture of zinc titanate phases (ZnTiO3, Zn2TiO4) and titanium rutile (TiO2). In compositions with low silica content (x = 40 or 50) the formation of zinc silicate (Zn2SiO4) occurs at high temperatures. The optical properties were evaluated for both powders and thin films. Particularly, thin films exhibit transmittance above 80% in the visible region. The refractive index at 632.8 nm and thickness of thin films were estimated using the envelope method and m-Line spectrocopy. Furthermore, morphological analysis of the thin films surface was performed by scanning electron microscopy. The characteristic emission peaks of Er3+ or Eu3+ doped powders and thin films were measured. The photoluminescent emission of Eu3+ ions, obtained the highest intensities for the powders treated at 800°C, for films treated at 700°C, under excitation at 394 nm, where the system remains primarily amorphous. The photoluminescent emission of the Er3+ ions was more intense for the powders treated at 1100°C under excitation at 980 nm, mainly due to reduction of hydroxyl groups which act as photoluminescence quenchers. In the film the highest intensity occurred at a temperature of 700°C under excitation at 378 nm and showing only one guided mode. Thus, the obtained thin films can be suitable for application as waveguides in integrated optical systems. Moreover, the Eu and Er doped powders can be used as phosphors in displays.
Este trabalho avalia as propriedades estruturais e ópticas do sistema ternário SiO2-ZnO-TiO2 dopado com íons Eu3+ (1% em mol) ou Er3+ (0,2% a 2,0% em mol). As composições xSiO2-([100-x]/2)ZnO-([100-x]/2)TiO2, com x = 40, 50, 60, 70 e 80 foram estudadas. Através de metodologia mista do processo sol-gel com o método Pechini foi possível obter sóis estáveis e transparentes, géis homogêneos, pós tratados termicamente de 100ºC a 1100°C e filmes finos transparentes e sem trincas. Filmes finos multicamadas foram depositados sobre substratos de sílica usando “spin coating” e calcinados a 500°C, seguido de um tratamento térmico entre 700°C e 1000°C. Por fotoluminescência foram observadas as transições de emissão características de íons Er3+ e Eu3+. A caracterização por difração de raios X dos pós mostrou que a cristalização tem início a partir de 800°C, com uma mistura de fases de titanatos de zinco (ZnTiO3, Zn2TiO4) e segregação de titânio rutilo (TiO2). Em composições com menores proporções de sílica (x= 40 ou 50) também ocorreu a formação de silicato de zinco (Zn2SiO4) em temperaturas mais elevadas. Os espectros de transmissão dos filmes apresentaram transmitância superior a 80%. Os valores de “band gap” óptico, o tempo de vida, as razões R/O e o índice de refração são dependentes do tratamento térmico e da composição dos pós. Usando o método da envoltória, pôde-se calcular o índice de refração a 632,8 nm e a espessura dos filmes finos, sendo que esta também foi estimada por microscopia eletrônica de varredura (MEV) e espectroscopia m-Line. A emissão fotoluminescente dos íons Eu3+ tem maior intensidade nos pós tratados à 800°C e nos filmes tratados à 700°C, sob excitação a 394 nm. Nestas temperaturas o sistema permanece predominantemente amorfo. A emissão fotoluminescente dos íons Er3+ foi mais intensa para os pós tratados a 1100°C, sob excitação a 980 nm, devido à eliminação de grupos OH supressores das emissões de Er3+. Nos filmes a maior intensidade se deu à temperatura de 700°C, sob excitação a 378 nm. Os filmes apresentaram apenas um modo guiado, sendo o mais apropriado para uso como guia de onda e os pós são indicados como fósforos podendo ser aplicados em “displays".
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Kharbache, Hayat. "Propriétés de fluorescence de l'ion Eu3+ dans K2(Y, Gd)F5 : analyse des couplages Eu3+-Eu3+ et des mécanismes de division de photons." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00728845.
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La spectroscopie de fluorescence induite par laser et par rayonnement synchrotron a été utilisée pour analyser l'intense émission de l'ion Eu3+ dans les fluorures K2YF5 et K2GdF5. L'utilisation conjuguée de la spectroscopie résolue dans le temps, de la variation de la concentration en ions Eu3+ a permis d'identifier les niveaux électroniques de l'ion Eu3+ après excitation dans les niveaux 5D2, 5D1 et 5D0. Les répartitions spectrales de la fluorescence se corrèlent parfaitement avec un ion Eu3+ inséré dans un site de symétrie C1 . A basse température, en dessous de 100 K, des structures satellites apparaissent de part et d'autre des raies principales d'excitation 7F0 -> 5D0-2. L'analyse des évolutions spectrales et temporelles des fluorescences à partir du niveau 5D0 sous excitation sélective dans les raies principales d'excitation et dans les raies satellites en fonction de la température et de la concentration en ion EU3+ a permis d'attribuer les structures supplémentaires à des signatures de paires Eu3+-Eu3+ dont l'existence est favorisée par le caractère unidimensionnel de la structure cristallographique, y compris le composé K2EuF5. Des mécanismes de cascades et de divisions de photons impliquant les ions Gd3+ et Eu3+ ont été identifiés dans K2GdF5 sous excitation VUV. Finalement le caractère unidimensionnel de la structure s'avère être un handicap pour réaliser des luminophores à rendement quantique supérieur à l'unité.
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Brett, Tricia Korrin. "The fate of estrone (E1), 17beta-estradiol (E2), estriol (E3) and 17alpha-ethinylestradiol (EE2) in surface waters." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46253.
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Lakes and rivers receiving wastewater treatment plant effluent contain many different endocrine disrupting compounds. Previous research into the fate of these compounds has focused on laboratory experiments that investigate a single scavenging mechanism, and there has been little research on the overall loss rate constants in receiving waters. This study evaluated the fate of estrone (E1), 17??-estradiol (E2), estriol (E3) and 17??-ethinylestradiol within three different receiving waters (a river, a large lake and a small reservoir) represented by two different mathematical models (plug flow reactor and continuously stirred tank reactor) and three different hydraulic residence times (<8 hours, >50 years and about 1 year). Wastewater treatment plant effluent samples and receiving waters were analysed for the four estrogens over a one year period. E1 and E2 were the only compounds detected and there was only enough data determine the fate of E1. A receiving water loss rate constant for E1 was calculated assuming first-order reaction kinetics. E1 loss was not detectable in the river and the large lake due to a very short and very long residence time, respectively. The time-weighted E1 loss rate constant within the small reservoir was found to be 0.0106 d-??. Data suggested that there may be a seasonal component to this loss rate that requires further investigation. The rate constant found suggests that E1 can be transported great distances within rivers.
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Santana, Ricardo Costa de. "Espectroscopia de centros opticamente ativos em cristais de Ca3Ga2Ge3O12 dopados com Er3+ e Er3+,Cr3+." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-13062008-110813/.
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O objetivo principal deste trabalho foi identificar e separar os níveis de energia dos multipletos excitado, 4S3/2, e fundamental, 4I15/2, provenientes do íon Er3+ alojado nos vários sítios não equivalentes existentes no garnet Ca3Ga2Ge3O12. Várias técnicas de espectroscopia óptica (absorção, luminescência com bombeio seletivo, excitação e conversão ascendente de luz) foram usadas com este objetivo. A partir dos resultados experimentais foram calculados, pela primeira vez, os parâmetros de íon livre e de campo cristalino para o Er3+ em cada um dos sítios identificados. Experimentos de luminescência e absorção sob a influência de campo magnético também foram realizados, e o fator g tanto do estado 4S3/2 quanto do 4I15/2 do Er3+ neste garnet foram determinados.The main objective of this work was to identify and attribute the energy levels of excited 4S3/2 and ground 4I15/2states, corresponding to the Er3+ ions located at the various non equivalent sites present in the Ca3Ga2Ge3O12 garnet. Several optical spectroscopic techniques, (absorption, site-selective luminescence, excitation and upconversion of light), were used with this objective. From the experimental results, it was possible, for the first time, to calculate the free ion parameters, as well as the crystalline field parameters, for the Er3+ ions in each of the identified sites. Luminescence experiments and absorption under the influence of the magnetic field were performed, and the g factor associated to both, 4S3/2 and 4I15/2 estates in this garnet were determined.
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Figueiredo, Marcio da Silva [UNESP]. "Avaliação óptica de vidros teluritos preparados com Er3+ e Er3+/Yb3+ para aplicação em fotônica." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/102527.
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figueiredo_ms_dr_ilha.pdf: 1006805 bytes, checksum: 5c550a3c14783fc554cc37dba6517cff (MD5)No presente trabalho foram sintetizados vidros Te-Li-Ti (TLT) dopados com Er3+ e também codopados com Er3+/Yb3+ para o estudo das propriedades da emissão em 1,5m do íon. Inicialmente foi estudado um conjunto com diferentes concentrações de Er3+ para ver a dependência com a concentração de dopante da eficiência quântica de emissão (). Foi empregado como método experimental de análise a técnica de lente térmica (LT) e os resultados foram confrontados com os determinados usando dados espectroscópicos combinados com a teoria de Judd-Ofelt. Embora sejam fortemente dependentes com a concentração, os valores de para as concentrações mais baixas de dopante (~76% para o vidro TLT: 0,05% molar de Er2O3) são maiores que os valores reportados na literatura para o mesmo íon em outras matrizes teluritos. Adicionalmente, o sistema codopado com Er3+/Yb3+ foi estudo a fim de avaliar se a adição do Yb3+ na matriz promove o aumento da emissão do érbio em 1,5 m, excitando o nível emissor via Yb3+. Os resultados mostraram que há um eficiente mecanismo de transferência de energia do Yb3+ para o Er3+ de maneira que a intensidade de emissão no infravermelho foi aumentada. Ademais, avaliou-se a existência ou não da emissão “downconversion” em 980 nm do itérbio mediante excitação do Er3+ no visível. Do ponto de vista do “downconversion”, que é interessante para aplicação do material em placas solares à base de silício, os resultados mostraram, pela primeira vez em um vidro telurito, que o efeito ocorre com uma eficiência na transferência de energia do Er3+ para o Yb3+ de 56%, indicando que o material tem boa perspectiva para utilização comercial
In this paper Er3+ doped and Yb3+/ Er3+codoped Te-Li-Ti (TLT) glasses were synthesized to study the properties of the emission at 1.5 m. One set was initially studied with different Er3+ concentrations to see the dependence of emission quantum efficiency () with the dopant concentration. The thermal lens spectrometry (TL) was employed as the method of experimental analysis and the results were compared with those determined using spectroscopic data combined with the Judd-Ofelt theory. Although they are highly dependent on the concentration, the values for the lower dopant concentrations (~ 76% for the TLT glass doped with 0.05 mol% Er2O3) are higher than those reported in literature for the same ion at tellurite other matrices. Additionally, the Er3+ / Yb3+ codopado system was studied to evaluate the increased emission of erbium at 1.5 m as a function of Yb3+ increment by excitation in the metastable state in Yb3+. The results show that there is an efficient transfer of energy from Yb3+ to Er3+, so that the infrared emission of Er3+ was increased, as was desired. Furthermore, we assessed whether or not the issue ytterbium downconversion emission at 980 nm upon excitation visible in the Er3+. From the viewpoint of the downconversion mechanism, which is interesting for application of the material in solar cells based on silicon, the results showed for the first time in a glass tellurite, which effect occurs with efficiency in energy transfer from Er3+ Yb3+ to 56%, indicating that the material has good prospects for commercial use
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Figueiredo, Marcio da Silva. "Avaliação óptica de vidros teluritos preparados com Er3+ e Er3+/Yb3+ para aplicação em fotônica /." Ilha Solteira, 2013. http://hdl.handle.net/11449/102527.
Full textAbstract:
Orientador: João Carlos Silos MoraesCoorientador: Sandro Márcio Lima
Banca: Eudes Borges de Araújo
Banca: Antonio Carlos Ferreira Seridonio
Banca: Noelio Oliveira Dantas
Banca: Luiz Antonio de Oliveira Nunes
Resumo: No presente trabalho foram sintetizados vidros Te-Li-Ti (TLT) dopados com Er3+ e também codopados com Er3+/Yb3+ para o estudo das propriedades da emissão em 1,5m do íon. Inicialmente foi estudado um conjunto com diferentes concentrações de Er3+ para ver a dependência com a concentração de dopante da eficiência quântica de emissão (). Foi empregado como método experimental de análise a técnica de lente térmica (LT) e os resultados foram confrontados com os determinados usando dados espectroscópicos combinados com a teoria de Judd-Ofelt. Embora sejam fortemente dependentes com a concentração, os valores de para as concentrações mais baixas de dopante (~76% para o vidro TLT: 0,05% molar de Er2O3) são maiores que os valores reportados na literatura para o mesmo íon em outras matrizes teluritos. Adicionalmente, o sistema codopado com Er3+/Yb3+ foi estudo a fim de avaliar se a adição do Yb3+ na matriz promove o aumento da emissão do érbio em 1,5 m, excitando o nível emissor via Yb3+. Os resultados mostraram que há um eficiente mecanismo de transferência de energia do Yb3+ para o Er3+ de maneira que a intensidade de emissão no infravermelho foi aumentada. Ademais, avaliou-se a existência ou não da emissão "downconversion" em 980 nm do itérbio mediante excitação do Er3+ no visível. Do ponto de vista do "downconversion", que é interessante para aplicação do material em placas solares à base de silício, os resultados mostraram, pela primeira vez em um vidro telurito, que o efeito ocorre com uma eficiência na transferência de energia do Er3+ para o Yb3+ de 56%, indicando que o material tem boa perspectiva para utilização comercial
Abstract: In this paper Er3+ doped and Yb3+/ Er3+codoped Te-Li-Ti (TLT) glasses were synthesized to study the properties of the emission at 1.5 m. One set was initially studied with different Er3+ concentrations to see the dependence of emission quantum efficiency () with the dopant concentration. The thermal lens spectrometry (TL) was employed as the method of experimental analysis and the results were compared with those determined using spectroscopic data combined with the Judd-Ofelt theory. Although they are highly dependent on the concentration, the values for the lower dopant concentrations (~ 76% for the TLT glass doped with 0.05 mol% Er2O3) are higher than those reported in literature for the same ion at tellurite other matrices. Additionally, the Er3+ / Yb3+ codopado system was studied to evaluate the increased emission of erbium at 1.5 m as a function of Yb3+ increment by excitation in the metastable state in Yb3+. The results show that there is an efficient transfer of energy from Yb3+ to Er3+, so that the infrared emission of Er3+ was increased, as was desired. Furthermore, we assessed whether or not the issue ytterbium downconversion emission at 980 nm upon excitation visible in the Er3+. From the viewpoint of the downconversion mechanism, which is interesting for application of the material in solar cells based on silicon, the results showed for the first time in a glass tellurite, which effect occurs with efficiency in energy transfer from Er3+ Yb3+ to 56%, indicating that the material has good prospects for commercial use
Doutor
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Karlsson, Johan, and Andreas Ljung. "Bors E23 - Framtagning av eldriven röravklippningsmaskin." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-943.
Full textAbstract:
Our Bachelor´s Thesis has been performed in co-operation with Bors Automation & Tool AB.
Our task was to develop a servomotor powered tube cutting-machine with initial point from
today's hydraulic driven tube cutting machine Bors HYD 23. The purpose with the new
construction was to achieve a more power-efficient tube cutting machine which could lower
the power consumption, and also meet the market continued growing demand for
environmental-conscious production.
Bors Automation & Tool gave us relatively free hands in order to enable new thinking ideas
without following their traditional constructional solutions.
Our solution resulted in a construction based on a power source existing of a servomotordriven
rollerscrew, witch provides a more rational use of energy compared with the current
method.
Bors Automation & Tool AB has decided to fabricate a prototype of Bors E 23 during the
autumn of 2007, which they are planning to revile at the Tube 2008 exhibition in Düsseldorf,
Germany.
NOTE:
Due to an agreement signed by the authors in the beginning of this project, no appendix is published at this time.
If you want to wiew these documents, please contact the authors.
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Bosco, Giácomo Bizinoto Ferreira 1987. "Luminescência do Eu3+ em a-SiNx:H." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278134.
Full textAbstract:
Orientador: Leandro Russovski TesslerDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Neste trabalho estudamos a fotoluminescência (PL) do Eu3+ em filmes finos de subnitretos de silício amorfo hidrogenado (a-SiNx:H) dopados com európio. No total, 85 amostras do material foram preparadas por RF-sputtering reativo variando o conteúdo de nitrogênio e európio. A caracterização composicional foi feita por RBS (Rutherfod Backscattering Spectroscopy). Coeficientes de absorção, índices de refração e espessuras das amostras foram determinados por espectroscopia de transmitância ótica UV-VIS. A PL foi medida a temperatura ambiente e a 10K em função da temperatura de recozimento entre 250 e 1100°C sob atmosfera redutora de nitrogênio ou oxidante de oxigênio. Para as amostras recozidas em atmosfera de N2, não foi observada nenhuma PL proveniente dos íons Eu3+. Há, no entanto indicações da PL característica de íons Eu2+. Após quase um ano de tentativas frustradas de obter PL dos íons Eu3+ foram determinados os parâmetros das amostras que otimizam o processo: concentração de nitrogênio x em torno de 1,17, temperatura de recozimento de 1100oC em atmosfera de oxigênio e concentração de európio y = [Eu]/[Si] = 8,9 at%.. A emissão do Eu3+ em a-SiNx:H foi analisada pela teoria de campo cristalino usando um pacote de programas que otimiza os parâmetros de campo cristalino da camada f. Para isso, analisamos também o espectro do Eu2O3 em pó, usado como referencia. Assim confirmamos que os íons ativos de Eu3+ ocupam sítios de simetria pontual C2. A analise dos dados para a-SiNx:H sugere que nesse material os íons Eu3+ ocupam sítios com a mesma simetria encontrada em Eu2O3 mas muito mais suscetíveis aos efeitos de desordem. Considerando essa simetria e o tratamento térmico necessário, e razoável supor a formação de clusters de oxido de európio de dimensões nanométricas em torno dos íons Eu3+
Abstract: In this work we studied the photoluminescence (PL) of Eu3+ in europium doped hydrogenated amorphous silicon subnitrides thin films (a-SiNx:H). In total, 85 samples of the material were prepared by reactive RF-sputtering varying the nitrogen and europium contents. Compositional characterization was obtained by RBS (Rutherford Backscattering Spectroscopy). Absorption coefficients, refraction indexes ans sample thicknesses were determined by UV-VIS optical transmittance spectroscopy. The PL was measured at room temperature and at 10K as a function of the sample annealing temperature between 250 and 1100°C under a reductive nitrogen atmosphere or an oxidant oxygen atmosphere. For the N2 annealed samples, we did not observe any PL from Eu3+ íons. There are, however, indications of Eu2+ characteristic emission. After almost a year of frustrated attempts to obtain PL from Eu3+ ions the parameters which optimize the process were determined: nitrogen content x around 1,17, annealing temperature of 1100oC under oxygen atmosphere and europium content y = [Eu]/[Si] = 8,9 at%. The Eu3+ emission in a-SiN1,17:H was analyzed using crystal field theory and a program suite to optimize f-shell crystal field parameters. We also analyzed the PL spectrum of powder Eu2O3 to use as a reference. The data analysis for a-SiNx:H suggests that in this material the Eu3+ active ions occupy sites with the same C2 point symmetry found in Eu2O3 but much distorted due to disorder. Considering this symmetry and the sample treatment necessary to obtain the PL, it is reasonable suppose the formation of europium oxide nanometer scale clusters around the Eu3+ ions
Mestrado
Física
Mestre em Física
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Santos, Clenilton Costa dos. "Propriedades Ãpticas dos vidros Er3+:PbPO4." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4874.
Full textAbstract:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorNeste trabalho utilizamos vÃrias tÃcnicas para investigar as propriedades Ãpticas dos vidros fosfato de chumbo (PbPO4) com concentraÃÃes moderadamente altas de Ãons de Ãrbio (Er3+), EDLP. Medimos a susceptibilidade de terceira ordem, χ3, e a dispersÃo do Ãndice de refraÃÃo linear, n0(λ), dos vidros EDLP na regiÃo de comprimento de onda entre 400 e 1940 nm, por meio da tÃcnica de Franjas de Maker. A partir do valor de χ3, calculamos o Ãndice de refraÃÃo nÃo-linear, n2, cujo valor à cerca de cinco vezes maior que o da sÃlica (SiO2). TambÃm obtivemos os valores de n2 dos vidros EDLP, atravÃs da tÃcnica de varredura Z para vÃrios comprimentos de onda. A diferenÃa entre os valores obtidos pelas duas tÃcnicas foi de 15%. Realizamos medidas de absorÃÃo Ãptica, cujos dados foram utilizados para calcular os parÃmetros fenomenolÃgicos Ωλ da teoria de Judd-Ofelt. Observamos que Ω4 e Ω6 permanecem praticamente constante com o aumento da concentraÃÃo de Er3+, ao passo que Ω2 diminui. Excitando as amostras em 800 nm foi possÃvel verificar emissÃes no verde, vermelho e infravermelho, centradas em 530, 550, 660 e 1530 nm, respectivamente. O tempo de vida da transiÃÃo 4I13/2 → 4I15/2 (em 1530 nm) do Er3+ diminui com o aumento da concentraÃÃo de Er3+, refletindo o quÃo importante à o processo nÃo-radiativo associado a esta transiÃÃo. A teoria de McCumber foi usada para calcular, a partir da seÃÃo de choque de absorÃÃo, a seÃÃo de choque da emissÃo estimulada da transiÃÃo 4I13/2 → 4I15/2 do Er3+. Observamos e analisamos uma forte reabsorÃÃo da fluorescÃncia em 1530 nm. Finalmente, discutimos a aplicabilidade dos vidros EDLP em dispositivos fotÃnicos.
In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index, n2, obtained from the third-order susceptibility was found to be five times higher than that of silica. For comparison purposes, the Z-scan technique was also employed to obtain the values of n2 of EDLP at several wavelengths, and the values obtained using the two techniques agree to within 15%. From the data obtained by absorption measurements, the Judd-Ofelt theory was employed to calculate the intensity-dependent parameters Ωλ (λ = 2, 4, and 6). We observed that increasing Er3+ content, Ω4 and Ω6 remain constant, while Ω2 decreases. Green, red, and infrared emissions centered at 530, 550, 660, and 1530 nm were observed under excitation at 800 nm. The lifetime of the Er3+: 4I13/2 → 4I15/2 (1530 nm) transition decreases with increasing Er3+ content, reflecting how significant the non-radiative process associated with this transition is. The McCumber theory was used to calculate, from absorption cross-section, the stimulated emission cross-section of the Er3+: 4I13/2 → 4I15/2 transition. A strong re-absorption of the fluorescence at 1530 nm was also observed and analyzed. Finally, we discuss the potential use of Er3+:PbPO4 glasses in photonics devices.
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Santos, Clenilton Costa dos. "Propriedades ópticas dos vidros Er3+:PbPO4." reponame:Repositório Institucional da UFC, 2010. http://www.repositorio.ufc.br/handle/riufc/9652.
Full textAbstract:
SANTOS, Clenilton Costa dos. Propriedades ópticas dos vidros Er3+:PbPO4. 2010. 96 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2010.Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-11-03T18:38:41Z No. of bitstreams: 1 2010_tese_ccsantos.pdf: 4778732 bytes, checksum: e9324ded793c2e668aa603d0ce9ecc71 (MD5)
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In this work we employ several techniques to investigate the optical properties of moderately high Er3+-doped lead phosphate (EDLP) glasses. The third-order optical susceptibility, χ3, and dispersion of the linear refractive index, n0(λ), of Er3+:PbPO4 were measured in the wavelength range between 400 and 1940 nm by using the spectrally resolved femtosecond Maker fringes technique. The nonlinear refractive index, n2, obtained from the third-order susceptibility was found to be five times higher than that of silica. For comparison purposes, the Z-scan technique was also employed to obtain the values of n2 of EDLP at several wavelengths, and the values obtained using the two techniques agree to within 15%. From the data obtained by absorption measurements, the Judd-Ofelt theory was employed to calculate the intensity-dependent parameters Ωλ (λ = 2, 4, and 6). We observed that increasing Er3+ content, Ω4 and Ω6 remain constant, while Ω2 decreases. Green, red, and infrared emissions centered at 530, 550, 660, and 1530 nm were observed under excitation at 800 nm. The lifetime of the Er3+: 4I13/2 → 4I15/2 (1530 nm) transition decreases with increasing Er3+ content, reflecting how significant the non-radiative process associated with this transition is. The McCumber theory was used to calculate, from absorption cross-section, the stimulated emission cross-section of the Er3+: 4I13/2 → 4I15/2 transition. A strong re-absorption of the fluorescence at 1530 nm was also observed and analyzed. Finally, we discuss the potential use of Er3+:PbPO4 glasses in photonics devices.
Neste trabalho utilizamos várias técnicas para investigar as propriedades ópticas dos vidros fosfato de chumbo (PbPO4) com concentrações moderadamente altas de íons de érbio (Er3+), EDLP. Medimos a susceptibilidade de terceira ordem, χ3, e a dispersão do índice de refração linear, n0(λ), dos vidros EDLP na região de comprimento de onda entre 400 e 1940 nm, por meio da técnica de Franjas de Maker. A partir do valor de χ3, calculamos o índice de refração não-linear, n2, cujo valor é cerca de cinco vezes maior que o da sílica (SiO2). Também obtivemos os valores de n2 dos vidros EDLP, através da técnica de varredura Z para vários comprimentos de onda. A diferença entre os valores obtidos pelas duas técnicas foi de 15%. Realizamos medidas de absorção óptica, cujos dados foram utilizados para calcular os parâmetros fenomenológicos Ωλ da teoria de Judd-Ofelt. Observamos que Ω4 e Ω6 permanecem praticamente constante com o aumento da concentração de Er3+, ao passo que Ω2 diminui. Excitando as amostras em 800 nm foi possível verificar emissões no verde, vermelho e infravermelho, centradas em 530, 550, 660 e 1530 nm, respectivamente. O tempo de vida da transição 4I13/2 → 4I15/2 (em 1530 nm) do Er3+ diminui com o aumento da concentração de Er3+, refletindo o quão importante é o processo não-radiativo associado a esta transição. A teoria de McCumber foi usada para calcular, a partir da seção de choque de absorção, a seção de choque da emissão estimulada da transição 4I13/2 → 4I15/2 do Er3+. Observamos e analisamos uma forte reabsorção da fluorescência em 1530 nm. Finalmente, discutimos a aplicabilidade dos vidros EDLP em dispositivos fotônicos.
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Massai, Lelio Ronaldo. "Analises quimicas e teste de toxicidade dos efluentes Kraft-E1 e final E3 apostratamento com o fungo Lentinus edodes." [s.n.], 1996. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314600.
Full textAbstract:
Orientador: Nora Marcela Haun QuirosDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Muitos métodos - físicos, químicos e biológicos - têm sido testados na redução da poluição dos efluentes Kraft. E mesmo a tecnologia da reciclagem das águas de processo, que reduz consideravelmente o volume do efluente produzido está sendo muito estudado, contudo a reciclagem parcial utilizada na indústria não reduz necessariamente a emissão de resíduos tóxicos, a menos que se consiga zero de descartes de efluente. Muitos dos compostos formados durante o branqueamento da polpa, não são removidos no tratamento secundário causando sérios danos ao meio ambiente. Neste estudo, análises químicas comparativas e um teste de toxicidade, foram realizados nos efluentes Kraft-E1 (primeira extração) e Final-E3 (tratamento secundário). As amostras com o pH ajustados para 5,0 com H2SO4 1M foram estocadas à 4°C em frascos de 500mL de polietileno. Após serem tratadas com o fungo Lentinus edodes UEC-2021 e após filtração (Millipore 0.22mm) as amostras foram analisadas. Foram obtidos, entre outros resultados, 51 % de redução de cor e 65% de redução na concentração de fenol
Abstract: Kraft Effluents with main purposes: the reuse of water tap and reduce volumes to be discharged. Despite their low toxicity, pulp and paper discharges have a toxic impact on receiving waters because of tremendous volumes discharged with color persisting and organic pollutants even in treated and partially treated effluents. Many compounds formed during pulp bleaching are not removed in the secondary treatment leading to a pulp mill effluent content of hundred different compounds. In this study a comparative chemical analysis was made with samples of Kraft Effluent-E1 (first extraction) a main type of chlorine bleach plant wastewater and with the Final Effluent-E3 after treatment in aerated lagoon with hydraulic dectention time of 3 days. The samples were pH adjusted to 5.0 with H2SO4 1M and stored at 4°C in polyethylene bottles in volumes of 500mL to ensure that all assays would be done with same effluent samples. After incubation with Lentinus edodes UEC-2021 and filtration (Millipore 0.22mm) samples were conveniently prepared for analysis. It was obtained a 51 % color removal and a 65% reduction value for phenol
Mestrado
Bioquimica
Mestre em Ciências Biológicas
38
Li, Chuin. "Spectroscopie, dynamique de fluorescence et potentialité laser des cristaux Y2SiO5:Er3+, Y2SiO5:Yb3+, Er3+ et Y2SiO5:Tm3+." Lyon 1, 1992. http://www.theses.fr/1992LYO10306.
Full textAbstract:
Les emissions laser a 1. 55 et 2 micron des ions de terre-rares er#3#+, tm#3#+ et ho#3#+ sont susceptibles de nombreuses applications tant dans le domaine des telecommunications par fibres optiques que dans les domaines medical et militaire. Cette these porte precisement sur l'etude spectroscopique et dynamique et sur l'evaluation des potentialites laser de monocristaux d'orthosilicate d'yttrium de formule chimique y#2sio#5 dopes soit par les ions er#3#+ ou tm#3#+ soit codopes par les ions yb#3#+ et er#3#+, l'ion yb#3#+ servant d'adsorbant (sensibilisateur) pour la lumiere d'excitation. Une part importante du travail est consacree a la description et a l'utilisation de la theorie de judd-ofelt dans la determination des differents parametres regissant les proprietes optiques de ces cristaux. Les resultats montrent que les cristaux dopes er#3#+, grace a une emission infrarouge bien centree autour de 1. 55 micron, une bonne section efficace d'emission stimulee, des relaxations non-radiatives entre etats excites favorables a un bon peuplement de l'etat emetteur, peuvent concurrencer valablement les verres phosphates dopes er#3#+ kigre qe-7 du commerce, tout en presentant de meilleures proprietes thermomecaniques. Les cristaux dopes tm, avec une emission large bande autour de 2 micron et les sections efficaces stimulees notablement plus elevees que dans la plupart des autres systemes, apparaissent quant a eux comme de bons candidats pour une emission laser accordable entre environ 1. 8 et 2. 1 micron
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AKRIM, ABDELLATIF. "Proprietes structurales et optiques des pyrophosphates ayp207 : tb3+, eu3+ (a = rb, cs). mecanisme de transfert tb3+ - eu3+." Clermont-Ferrand 2, 1994. http://www.theses.fr/1994CLF21641.
Full textAbstract:
Le travail effectue au cours de la these a porte sur l'etude des proprietes optiques et structurales des pyrophosphates ayp207 (a = rb, cs) dopes en ions eu3+ et tb3+. Dans la premiere partie de ce travail, nous avons realise d'une part la synthese des materiaux par voie solide, et d'autre part l'affinement de leur structure par diffraction des rayons x sur poudre. L'affinement structural a ete base sur la methode de rietveld. Dans les deux materiaux rbyp207 et csyp207 les polyedres de coordination de l'alcalin et du phosphore presentent des distorsions dues a la taille de l'ion trivalent. La deuxieme partie du travail a ete consacree a l'etude des proprietes optiques des ions tb3+ et eu3+ dopant individuellement chacun des deux materiaux. Pour les materiaux dopes au terbium, nous avons mis en evidence une faible extinction par concentration de la fluorescence 5d4 - 7f5 et une diffusion rapide assistee de phonons se produisant pour les fortes concentrations en ions terbium. L'etude des proprietes optiques des materiaux dopes en ions eu3+ nous a permis de noter l'existence de deux sites optiques pour l'ion trivalent, lorsque la synthese impliquait le carbonate d'yttrium. Le premier est le site intrinseque prevu par l'etude structurale. Le deuxieme est un site supplementaire du a la presence d'ions co32- residuels dans le reseau anionique. Lorsque la synthese des materiaux est realisee en utilisant l'oxyde d'yttrium comme produit de depart seul le site intrinseque est observe. La derniere partie du travail a porte sur l'etude du transfert d'energie tb3+ - eu3+. Il a ete mis en evidence grace a l'analyse des spectres d'excitation de l'ion eu3+ et des declins de fluorescence de l'ion tb3+ et de l'ion eu3+ dans les materiaux codopes en ces deux ions. Le mecanisme de transfert met en jeu les niveaux 5d4, 7f4 de l'ion tb3+ et 5do, 7fo,1 de l'ion eu3+ a temperature ambiante. Par contre a 77 k, le mecanisme fait intervenir les niveaux 5d4, 7f6 de l'ion tb3+ et 5d1, 7fo de l'ion eu3+
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Gomes, Manassés Almeida. "Síntese via sol gel proteico e caracterização estrutural e óptica do CaAl2O4:Eu3+, CaAl2O4:Ce3+, CaAl2O4:Eu3+;Dy3+." Universidade Federal de Sergipe, 2013. https://ri.ufs.br/handle/riufs/5367.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqIn this work were studied the optical and structural properties of the calcium aluminate in the stoichiometry 1:2:4 (CaAl2O4) doped with rare earths (RE = Ce, Eu, EuDy). The material was produced via the Sol-Gel Proteic Method that is so known because of its capacity of producing nanosized particles. The structural characterization of the samples was performed by Differential Thermic and Thermogravimetric Analysis (DTA/TG), Scattering electron microscopy (SEM), X-ray diffraction (XRD), where the last one reveals the formation of the single phase of CaAl2O4 calcined at 1200ºC for 2 hours. The study of the optical properties this material has started from 4f-4f and 5d-4f transitions identification, related to the rare earths, through the Photoluminescence (PL) and Radioluminescence (RL) techniques. The Absorption of ionizing radiation, the conversion of radiation into visible light, important factors in the properties that define the application of a material, it was studied by X-Ray Excited Optical Luminescence (XEOL) and Optical Absorption (AO) techniques. The results obtained with these techniques together X-ray Absorption Spectroscopy (XAS) analysis possible a broad understanding of the properties of material.
Neste trabalho foram estudadas as propriedades ópticas e estruturais do Aluminato de Cálcio na estequiometria 1:2:4 (CaAl2O4) dopado com terras raras (TR = Ce, Eu, EuDy). O material foi produzido utilizando o método Sol Gel Proteico conhecido por produzir partículas de tamanho nanométrico. A caracterização estrutural das amostras foi realizada através das técnicas de Analise Térmica Diferencial juntamente com a Termogravimétria (DTA/TG), Microscopia Eletrônica de Varredura (MEV) e Difração de Raios X (DRX), sendo que este último possibilitou a identificação da formação da fase única para o CaAl2O4 à uma temperatura de calcinação de 1200ºC por 2 horas. O estudo das propriedades ópticas do material iniciou a partir da identificação das transições 4f-4f e 5d-4f, referentes aos íons terras raras, através da técnica de Fotoluminescência (PL) e Radioluminescência (RL). A absorção de radiação ionizante e conversão da radiação em luz visível, fatores importantes nas propriedades que definem sua aplicação, foram estudadas pelas técnicas de Emissão Luminescente Estimulada por Raios X (XEOL) e Absorção Óptica (AO). Os resultados obtidos com estas técnicas juntamente com análises de Espectroscopia de Absorção Raios X (XAS) possibilitaram um entendimento amplo das propriedades do material.
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Barral, Paola. "Characterization of a novel hnRNP : E1B-AP5." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403905.
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Souza, Eunezio Antonio de. "Aplicações de fibras ópticas dopadas com Er3+." [s.n.], 1991. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277456.
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Orientador: Carlos Henrique de Brito CruzTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Apresentamos nesta tese um estudo das aplicações de fibras ópticas dopadas com Érbio em amplificadores e lasers. Como amplificadores, determinamos as características das fibras de forma a apresentarem um melhor desempenho em sistemas de comunicação via fibra óptica. Para tal, concluímos que as fibras devem possuir um núcleo pequeno e/ou a concentração de Érbio confinada em seu centro, para haver maior superposição entre a região dopada e os feixes de bombeio e sinal. Concluímos também que a concentração de Érbio deve ser pequena para evitar efeitos cooperativos de conversão ascendente de energia que depopulam o nível meta-estável (I13/2), diminuindo a eficiência do bombeio. Como laser, obtivemos a operação CW, à temperatura ambiente. O laser de fibra dopado com Érbio, apesar de operar como um sistema de 3-níveis, apresentou uma baixíssima potência de limiar (~20mW). Isto se deve à sua favorável geometria e À alta intensidade no núcleo. Com uma fibra multimodo obtivemos um laser de fibra com alta potência (~500 mW) que pode ser usado como fonte de bombeio para medidas de óptica não linear. Utilizamos também o laser de fibra para geração de pulsos curtos pela técnica de acoplamento de modos passivos, usando um filme semicondutor de IaGaAs/InP como absorvedor saturável, obtivemos pulsos de 1 ns de duração com potência de pico de ~ 12 W
Abstract: In this work we study the applications of Erbium doped fiber as amplifiers and lasers. As an amplifier, we determined the fiber characteristics which optimize its performance at an optical fiber communication system. We conclude that the fibers should have a small core radius and/or an Erbium distribution confined as close as possible the center of the fiber in order to optimize the overlap between the doped region and the light of the pump and signal. We also conclude that the concentration should be low to prevent cooperative upconversion mechanisms that depopulate the meta stable level reducing the pump efficiency. As a laser, we obtained CW operation at room temperature. The Erbium doped fiber laser, despite its operation as a 3-level system, had a very low threshold pimp power (~20 mW). This is due to the favorable geometry and the high intensity in the core region. Using a multimode Erbium doped fiber, we obtained a high power output of ~500 mW. We also obtained passive and active mode locking operation of the Erbium doped fiber laser. In active mode locking, pulses of 80 psec duration with 03,6 W of peak power were obtained. The passive mode locking operation, using a bulk semiconductor as saturable absorber, generated pulses of 1 nsec of duration with peak power of ~12 W
Doutorado
Física
Doutor em Ciências
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Teodoro, Junior Jose. "Fluorescência do íon Er3+ em AlCl3 monocristalino." [s.n.], 1990. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278075.
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Orientador: Jose Antonio SanjurjoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Usando espectroscopia de luminescência excitada por laser em amostras de Er9+:AlCl3 monocristalinas foram determinados os desdobramentos de campo cristalino nos termos 4S3/2, 2H11/2, 4F9/2 e 4I15/2 ( estado fundamental ). As transições fluorescentes correspondentes aos níveis das configurações 4S3/2 ® 4I15/2 permitiram determinar os parâmetros de campo cristalino para o hamiltoniano de spin quase-cúbico proposto. As medidas de ESR sobre as amostras à baixa temperatura confirmam a natureza do estado fundamental no multipleto 4I15/2 determinado pelos espectros de luminescência. É observada a desexcitação não radiativa da transição 2H11/2 ® 4I15/2 transferindo intensidade para a transição 4S3/2 ® 4I15/2 por emissão de fonons ópticos. A realização deste trabalho foi motivada pela possibilidade de introduzir moléculas de Er3+:AlCl3 como impurezas nos Compostos de Grafite Intercalados ( GIC's ) para obter informações sobre os mecanismos de transição de fase destes compostos a partir da modificação do "splitting" de campo cristalino pelas camadas de grafite
Abstract: Not informed.
Mestrado
Física
Mestre em Física
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Cruz, Gerson Kniphoff da. "Propriedades óticas do íon Er3+ em Y2BaZnO5." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-31032015-161954/.
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A família de óxidos Re2BaCuO5 (Re = Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu e Y) é freqüentemente encontrada como impureza na síntese dos supercondutores óxidos de alta temperatura (ReBa2Cu3O7-x). Uma família isoestrututal a essa é a família de óxidos Re2BaZnO5. Em ambos os casos, uma série de estudos têm sido realizados em espectroscopia ótica. No entanto, nenhuma atenção especial é dada ao íon Er3+ como dopante desses óxidos. Nesta tese foi promovida com sucesso, através de medidas de absorção, luminescência e tempos de vida de estados excitados dos multipletos 4S3/2 e 4F9/2 de excitação seletiva de sítio do multipleto 4S3/2 completa identificação experimental dos níveis de energia do multipleto excitado (4S3/2) e fundamental (4I15/2), do íon Er3+, na amostra de (Er0.05Y0.95)2BaZnO5. Os resultados obtidos e aqui apresentados são inéditos e mostram a existência de comunicação, por transferência de energia, entre os dois sítios presentes no materialThe family of oxides Re2BaCuO5 (Re = Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu and Y) have been found very often as impurities in the synthesis of high temperature superconducting RBa2Cu3O7-x oxides. The family of oxides Re2BaZnO5 is isostructural to the first one. In both cases, optical spectroscopy had been applied to the study of them Some works had been published in both cases but no attention has been given to erbium as dopant of these oxides. In this work we successfully carried out the experimental identification of the fundamental (4I15/2) and the excited (4S3/2) configurations of the erbium ion in (Er0.05Y0.95)2BaZnO5. This identification had been made with absorption, luminescence and time decay measurement of the 4S3/2 and 4F9/2 multipletes and site selective excitation of the 4S3/2 multiplete. These results are original and show the energy transference between two different sites in the material
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Lacot, Eric. "Dynamique d'un laser à fibre dopée Er3+." Grenoble 1, 1992. http://www.theses.fr/1992GRE10202.
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La dynamique d'un laser a fibre dopee er#3#+ a ete analysee aussi bien en regime de pompage continu qu'en regime de pompage module. En pompage continu, lorsque l'on augmente la puissance de pompe, le laser atteint un second seuil et une bifurcation de hopf apparait menant le laser d'un regime de fonctionnement continu a un regime de fonctionnement pulse. Une etude de l'influence des parametres aussi bien intrinseques (dopage, longueur,. . . ) que extrinseques (pompage, cavite,. . . ) nous a permis de determiner dans un espace de parametres propres au laser la frontiere entre les differents regimes de fonctionnement. Nous avons aussi pu observer, aussi bien en regime de fonctionnement continu qu'en regime de fonctionnement pulse, que le comportement transitoire de l'intensite totale du laser est en fait la somme des comportements transitoires de deux etats orthogonaux de polarisation. En regime transitoire (reponse a un pompage en echelon) le laser a fibre presente des oscillations de relaxation. C'est en modulant la puissance de pompe de maniere sinusoidale au voisinage de la frequence de relaxation que nous avons pu observer dans le comportement dynamique du laser a fibre une cascade de doublement de periodes conduisant a un fonctionnement chaotique. Nous avons developpe un modele semi-classique decrivant de la dynamique du laser a fibre dopee. Cette dynamique est parfaitement decrite par un modele de deux lasers couples pompes de maniere coherente. La transition entre le regime continu et le regime pulse est bien decrite ainsi que les deux etats propres de polarisation et le comportement chaotique
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Williamson, James. "Icebergs in the desert : the links between capitalist expansion and the spread of 'American' values in Utah, 1847-1896." Thesis, Keele University, 2018. http://eprints.keele.ac.uk/4595/.
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This thesis analyses debates over the economic future of postbellum Utah Territory, in order to demonstrate the connection between economic expansion and the promotion of a homogenous ‘American’ identity. Following the American Civil War, a dominant Republican establishment sought to reform Utah Mormons, whose practices of polygamy, theocratic government and economic protectionism represented a rejection of key party values. While support for reforming Mormonism was widespread, anti-Mormon advocates struggled to pass stronger legislation due to the limits of federal authority. Many Republicans came to believe that economic integration offered the potential for a gradual reformation of Utah. Creating systems of economic reciprocity and demonstrating the benefits of capitalist culture would weaken Mormons’ desire for isolationism and erode their peculiarities. The development of a transcontinental railroad and promotion of mining in Utah became tools of assimilation, ways to spread the values of the dominant political power. The Mormon leadership made efforts to resist these market pressures, both rhetorically and practically. It warned its followers of the long-term risks of economic integration and tried to introduce redistributionist initiatives which would foster group spirit and create a more equitable society. However, the reluctance of many Saints to adhere to Church regulation would repeatedly undermine these efforts, as the attractions of the free market made inroads that political reform had struggled to achieve. By the end of the century, a transformation had taken place within Mormon society. The encroachment of capitalist networks into Utah had damaged the Church’s ability to maintain regional autonomy and resulted in the adoption of more ‘American’ business practices. While Mormon economic discourse demonstrated how fringe groups could respond to the pressure to adopt free-labour capitalism, the Church’s inability to create an alternative socioeconomic model shows how the expansion of trading networks formed a key part of postbellum Republican nationalisation.
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Ganly, Ian. "E1B attenuated adenoviruses in genetic therapy for cancer." Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266588.
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Leal, Luis Carlos Avila. "Intracavity absorption spectroscopy with Er3+-doped fiber lasers." Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7371.
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Mestrado em Engenharia FísicaEspectroscopia de absorção de intracavidade com um laser de banda larga de fibra dopada com Er3+ é aplicada para medidas resolvidas no tempo de moléculas de CO2 revelando informações quantitativas sobre a concentração do gás exalado na respiração humana. A gama espectral das medições estende-se de 1.52 μm – 1.61 μm através da deslocação da lente de intracavidade. Com um laser pulsado aplicado nesta experiência, a sensibilidade à absorção corresponde a um comprimento do percurso de absorção efectiva de 6 km assumindo que a cavidade está completamente preenchida com a amostra. O aumento da sensibilidade é alcançada através da construção de um laser de configuração em anel unidirecional. O comprimento do percurso de absorção efectiva é aumentado por um factor de três comparando com uma configuração linear com o mesmo comprimento da cavidade.
Intracavity absorption spectroscopy with a broadband Er3+-doped fiber laser is applied for time-resolved measurements of CO2 molecules revealing quantitative information about the gas concentration in exhaled human breath. The spectral range of measurements extends from 1.52 to 1.61 μm by moving an intracavity lens. With a pulsed laser applied in this experiment, the sensitivity to absorption corresponds to an effective absorption path length of 6 km assuming the cavity is completely filled with the sample. Sensitivity enhancement is achieved by employing an unidirectional ring laser. The effective absorption path length is enhanced by a factor of three compared to a linear configuration with the same cavity length.
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Ebbeni, May. "Watt-class continuous wave Er3+/Yb3+ fiber amplifier." Kansas State University, 2011. http://hdl.handle.net/2097/13256.
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Master of ScienceDepartment of Physics
Brian R. Washburn
Rare-earth doped optical fibers can be used to make optical amplifiers in the near infrared with large optical gain in an all fiber based system. Indeed, erbium doped fibers made gain possible within the 1532 to 1560 nm band which makes long span fiber optical communication systems a possibility. Erbium doped fibers have also been used to make narrow linewidth or mode-locked lasers. Other rare-earth doped fibers can be used for amplifiers in other near-infrared spectral regions. Recently, fiber amplifier technology has been pushed to produce watt level outputs for high power applications such as laser machining. These high power amplifiers make new experiments in ultrafast fiber optics a possibility. This report reviews the current literature on Watt-class continuous wave erbium doped amplifiers and discussed our attempt to develop a high power Yb/Er amplifier. After the design of the cladding pump in 1999, the world’s first single mode fiber laser with a power greater than 100 Watts of the continuous wave light was introduced. After 2002 there was a huge spike in the output powers (up to 2 kW) of lasers based on rare-earth doped fibers. Our own work involved developing a 10 W amplifier at 1532 nm and 1560 nm. A high power amplifier was made by seeding a dual-clad Yb/Er co-doped fiber pumped at 925 nm using a lower power erbium doped fiber amplifier. We will discuss the design and construction of the amplifier, including the technical difficulties for making such an amplifier.
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Norouzi, Kandalan Roya. "The Modeling and Simulation of EV3 Motor Dynamics." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862751/.
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This paper describes a procedure to find the transfer function for the Lego Mindstorms Ev3. Lego Mindstorms Ev3 can serve as the platform for a system modeling and a controller design course. It is economical and accessible. It is also very compatible with Matlab and Simulink. This platform can be used for concepts of modeling, feedback, and controller design. The main approach in this work focuses on the closed loop instead of open loop. Although this approach turns the problem into a more complicated puzzle, it reveals more details. In this work, different techniques have been used, such as time domain, root locus, and least square estimation. Different tools have also been utilized such as Matlab SISO tool, the Matlab System Identification tool, and Simulink. These methods and implementations assisted to acquire different types of transfer functions for the system. By simulating the transfer functions and comparing them with experimental studies, the matching scores were calculated to decide on the best transfer function. Finding the finest transfer function for this gadget enables us to prepare diverse practical undergraduate and graduate curricula.