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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Sobre o \'Caso Marie Curie\' - A radioatividade e a subversão do gênero / Marie Curie\'s case: the radioactivity and the subversion of gender

Cardoso, Gabriel Pugliese 21 September 2009 (has links)
Trata-se de um estudo do Caso Marie Curie sob o signo do acontecimento: como a luta desigual de Marie Curie em favor da radioatividade foi suscitada pela possibilidade de afirmar isso é científico. Essa pesquisa se debruça sobre as controvérsias em torno da radioatividade entre os anos 1898 e 1911, que envolveram toda uma política sexual (e depois nacionalista). Em meio a esse conjunto de relações de poder que tornou indissociáveis os assuntos humanos e a gestão-produção das coisas, exploro como esse acontecimento criou uma problematização para os contemporâneos, desabrochando em uma política singular. Recolocar e extrair o caráter auto-evidente da produção de Marie Curie e da radioatividade é um dos objetivos dessa dissertação. Enfim, desejo fazer aparecer uma aclimatação que corrompeu tanto o gênero quanto a ciência, produzindo de modo singular Marie Curie como um ícone da história da ciência, bem como a radioatividade com um fenômeno universal. / It is about a study of Marie Curie Case under the sign of the : how an unequal conflict of Marie Curie in favor of the radioactivity was raised by the possibility of affirming this is scientific. This search focuses on the controversies surrounding the radioactivity between the years 1898 and 1911, which involved a sexual (and after nationalist) politics. In the midst of this set of power relations that made the human affairs and the production-management of things inseparable, I explore how these created a problematization to the contemporaries, unclasping a singular politics. This dissertation aims at replacing and extracting the selfevident character of the production of Marie Curie and radioactivity. Finally, I desire to display an acclimatization that corrupted both gender and science, producing Marie Curie as an icon of science history, and the radioactivity as an universal phenomenon.
12

Élaboration et Caractérisations physiques des manganites à effet magnetocalorique . / Preparation and physical characterization of the magnetocaloric effect in manganites

M'Nassri, Rafik 26 June 2013 (has links)
Les travaux présentés dans ce manuscrit consistent à élaborer par la méthode céramique des oxydes ferromagnétiques de type pérovskite et à étudier leurs propriétés physiques (structurales, magnétiques, magnétocaloriques..). Nous avons commencé ce travail par la synthèse de séries de manganites à base de praséodyme ( Pr0.6-xEuxSr0.4MnO3 et Pr0.6-xErxSr0.4MnO3 ) et de lanthane ( La0.6Sr0.2Ba0.2-x□xMnO3 et (La0.6Sr0.2Ba0.2MnO3)1-x /(Co2O3)x ) en utilisant la méthode solide-solide à haute température. Les échantillons élaborés ont été caractérisés par diffractométrie de poudre RX. Les diffractogrammes obtenues ont été affinés par la méthode Rietveld en utilisant le logiciel Fullprof. L'affinement structural a montré que les manganites synthétisés se présentent sous forme de phases pures avec des raies fines et intenses sans phases parasites et cristallisent dans des structures déformées.Des mesures magnétiques (M(T) et M(H)) ont permis d'obtenir des informations sur le comportement magnétique à basse température, les transitions magnétiques et l'évaluation de l'aimantation à saturation. L'aimantation en fonction de la température montre que ces manganites présentent des transitions ferromagnétiques - paramagnétiques et que leurs températures de Curie diminuent sous l'effet de la substitution dans le cas des composés à base du praséodyme et sous l'effet de l'introduction des lacunes dans le système basé sur le lanthane. Les isothermes M (H) confirment le comportement ferromagnétique à basses températures des échantillons étudiés. A partir de ces mesures et en utilisant les relations de Maxwell, on a déterminé les variations d'entropie magnétique ∆Sm et on a évalué l'effet magnétocalorique présent dans ces matériaux. Via la connexion entre la chaleur spécifique et l'aimantation, on a déterminé la variation de la chaleur spécifique ∆Cp dans tous ces échantillons en exploitant les résultats ∆Sm. Nos résultats confirment que les grandeurs caractéristiques de l'effet magnétocalorique sont très sensibles au champ magnétique appliqué, d'où l'étude de leur dépendance en champ magnétique présente un très grand intérêt. Cette dépendance en champ magnétique de la variation d'entropie magnétique peut être exprimée selon une loi de puissance de type ∆Sm ~ a (µ0H)n où n est appelé exposant local. Cette étude permet donc d'une part, d'identifier les matériaux qui se comportent de façon similaire et les voies d'amélioration de ces propriétés et elle constitue, d'autre part, un outil intéressant permettant d'extrapoler ces propriétés dans des conditions non accessibles au laboratoire. / The studies presented in this manuscript deal with the synthesis and characterization of ferromagnetic perovskite oxides. Four material systems have been described in this work ( Pr0.6-xEuxSr0.4MnO3 et Pr0.6-xErxSr0.4MnO3 ) et lanthanum ( La0.6Sr0.2Ba0.2-x□xMnO3 et (La0.6Sr0.2Ba0.2MnO3)1-x /(Co2O3)x ) . Our samples have been synthesized using the solid-state reaction method at high temperatures. Rietveld refinement of the X-ray diffraction patterns using Fullprof program shows that all our samples are single phase and crystallize in the distorted structures. Magnetic measurements show that all our samples exhibit a paramagnetic–ferromagnetic transition with decreasing temperature. The Curie Temperature TC shifts to lower values with increasing substitution in the Pr0.6-x(Eu or Er)xMnO3 system and under the effect of barium deficiency in the La0.6Sr0.2Ba0.2-x□xMnO3 system. From the magnetization isotherms at different temperatures, magnetic entropy change ∆Sm and relative cooling power RCP have been evaluated. By means of the connection between the specific heat and the magnetization was determined the variation of the specific heat ΔCp in these samples using the results ΔSm. Our results confirm that the characteristic values of the magnetocaloric effect are very sensitive to the applied magnetic field, where the study of their dependence on magnetic field has a very great interest. For fixed temperatures, the magnetic field dependence of magnetic entropy change ∆Sm is accounted for by the n exponent, which may be derived by a numerical fitting to the formula ∆Sm ~ a (µ0H)n where a is a constant. This study allows one hand, identify materials that behave similarly and ways to improve these properties and it is, on the other hand, a useful tool to extrapolate these properties under conditions not accessible in the laboratory.
13

Synthesis, high-pressure study and dielectric characterization of two lead-free perovskite materials : SrTi1-xZrxO3 and KNb1-xTaxO3 / Synthèse, étude sous haute pression et caractérisation diélectrique des deux matériaux pérovskites sans plomb : SrTi1-xZrxO3 and KNb1-xTaxO3

Di Geronimo Camacho, Elizabeth Carolina 15 December 2016 (has links)
Les matériaux de structure pérovskite de formule générale ABO3 sont les ferroélectriques les plus étudiés pour leurs propriétés intéressantes dans de nombreuses applications technologiques. Cependant leurs propriétés sont directement reliées à la structure et sont fortement conditionnées par les transitions de phases qui dépendent de la température, de la composition chimique et de la pression. Dans le manuscrit de thèse, le comportement sous haute pression de deux matériaux pérovskite SrTi1-xZrxO3 (STZ) et KNb1-XTaXO3 (KNT) est étudié et différentes techniques de frittage pour améliorer la densité des céramiques et optimiser les propriétés ferroélectriques des céramiques K(Nb0.40Ta0.60)O3 et (KxNa1-x)Nb0.6Ta0.4O3 sont examinées.Des analyses sous hautes pressions par spectroscopie Raman et diffraction des rayons X des poudres de SrTi1-xZrxO3 (x= 0.3, 0.4, 0.5, 0.6, 0.7) et KNb1-XTaXO3 (x=0.4, 0.5, 0.6, 0.9) en enclume diamant ont été réalisées. Les spectres Raman montrent une augmentation des modes Raman avec la pression pour les poudres de STZ indiquant que la pression induit des transitions de phases vers des symétries plus basses de la maille dans ces composés.De plus, les expériences de spectroscopie Raman ont fait apparaître une décroissance des modes Raman lorsque la pression est augmentée, montrant bien que la pression induit des transitions de phases vers des structure plus symétriques. L'évolution du mode Raman principal pour les phases orthorhombique et quadratique a été suivi jusqu'à ce que la phase cubique apparaîsse, ce qui nous a permis de proposer un diagramme de phase pression-composition pour les composés KNT.Trois différentes techniques de frittage, utilisation d'additifs, frittage en deux paliers et SPS ont été étudiées pour les céramiques de K(Nb0.4Ta0.6)O3 et (KxNa1-x)Nb0.6Ta0.4O3 . La constante diélectrique et les pertes en fonction de la température des céramiques ont été améliorées par l'utilisation du KF comme additif de frittage et par le frittage en deux paliers. Les échantillons densifiés par SPS présentent une microstructure fine et possèdent les plus fortes densités. Ils ont les meilleurs propriétés ferroélectriques. Aucun changement significatif de la température de Curie ne semble être induit par le taux de Na, et on observe cependant une augmentation de la constante diélectrique et des propriétés ferroélectriques suivant le taux de Na. / Perovskite materials whose general chemical formula is ABO3 are one of the most study ferroelectrics due to the interesting properties that they have for technological applications. However, their properties are directly related to structural phase transitions that could depend of temperature, composition and pressure. In the studies presented here, we first examined the high-pressure behavior of two perovskite materials SrTi1-xZrxO3 (STZ) and KNb1-XTaXO3 (KNT), and we later continued to investigate different sintering techniques in order to improve the densification, dielectric and ferroelectric properties of K(Nb0.40Ta0.60)O3 and (KxNa1-x)Nb0.6Ta0.4O3 ceramics.High-pressure Raman scattering and X-ray diffraction investigations of SrTi1-xZrxO3 (x= 0.3, 0.4, 0.5, 0.6, 0.7) and KNb1-XTaXO3 (x=0.4, 0.5, 0.6, 0.9) powders were conducted in diamond anvil cells. Raman scattering experiments showed and increased of Raman modes with pressure for the STZ samples, which indicates that pressure induced phase transitions towards lower symmetry for these compounds.Moreover, high pressure Raman spectroscopy experiments showed a decrease of the Raman modes as the pressure was increased for the KNT samples, showing that pressure induced phase transitions towards higher symmetries. The evolution of the main Raman modes for the orthorhombic and tetragonal phases were followed until the cubic phase was reach, and allowed us to propose a pressure-composition phase diagram for the KNT compounds.Three different sintering techniques, sintered aids, two step sintering and spark plasma sintering, were used on K(Nb0.4Ta0.6)O3 and (KxNa1-x)Nb0.6Ta0.4O3 ceramics. The use of KF as sintered aid and the two step sintering method showed an improvement of the dielectric constant and dielectric losses of these samples. SPS samples presented a fine microstructure with the highest density and the best ferroelectric behavior. We did not detect any changes on the Curie temperature due the amount of Na but and increase of the dielectric constant and the ferroelectric properties was observed due to the amount of Na.
14

Proposta de caracterização da metodologia de ensino da cientista e educadora Marie Curie no início do século XX na "cooperativa de ensino"

Derossi, Ingrid Nunes 25 July 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-03-21T13:55:49Z No. of bitstreams: 1 ingridnunesderossi.pdf: 1682945 bytes, checksum: 0589e9b31e14e8174e8bd4f784deadbe (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-04-24T02:14:47Z (GMT) No. of bitstreams: 1 ingridnunesderossi.pdf: 1682945 bytes, checksum: 0589e9b31e14e8174e8bd4f784deadbe (MD5) / Made available in DSpace on 2016-04-24T02:14:47Z (GMT). No. of bitstreams: 1 ingridnunesderossi.pdf: 1682945 bytes, checksum: 0589e9b31e14e8174e8bd4f784deadbe (MD5) Previous issue date: 2013-07-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho é uma proposta de caracterização da metodologia de ensino utilizada pela cientista e educadora Marie Curie em aulas experimentais de física, anotadas por uma de suas alunas no projeto educacional de uma “Cooperativa de Ensino” criado pela pesquisadora e alguns colegas da Universidade Sorbonne para ensinar a seus filhos. Publicado pela primeira vez em 2007 com o título Aulas de Marie Curie – Anotadas por Isabelle Chavannes em 1907 através da editora Edusp sob a responsabilidade de tradução e apresentação de Waldyr Muniz Oliva, certamente atraiu os olhares tanto da comunidade de Ensino de Ciências como dos Historiadores da Ciência, que afinal, ha muito vêm estreitando um, já inadiável, diálogo. A partir dessas anotações do fichário da aluna Isabelle Chavannes, fomos buscar subsídios no The Improvement of the Mind do reverendo Isaac Watts (1674-1748), publicado pela primeira vez em 1741 para analisar a metodologia utilizada pela cientista/educadora, além de outros pensadores como John Locke (1632-1704). Abordamos brevemente, a vida da pesquisadora ambicionando tecer um enredo que nos permitisse colocar em primeiro plano seu perfil de educadora. Após uma explanação sobre o The Improvement of the Mind de Isaac Watts, obra muito utilizada por estudiosos como Michael Faraday (1791-1867) e Jane Marcet (1769-1858) e que utilizamos como base da caracterização de cada uma das dez aulas de física ministradas por Madame Curie no referido projeto, passamos ao âmago de nosso trabalho, que demandou um enorme cuidado para não cedermos a propostas de análise contemporâneas. / The following paper is a proposal of characterization of the teaching methodology used by the scientist and educator Marie Curie in her practical physics experiment classes, which was written down by her students in the educational project of a “Teaching Cooperative” created by the researcher and some colleagues from Sorbonne University to teach their children. First published in 2007 entitled Aulas de Marie Curie – Anotadas por Isabelle Chavannes em 1907, by the editorial Edusp under the translating and presenting responsibility of Waldyr Muniz Oliva, it certainly attracted the looks of not only the Community of Science Teaching such as the Science Historians, which have been, after all, narrowing an unavoidable dialogue. From these notes in the student Isabelle Chavannes’ binder, we went searching for subsidies in The Improvement of the Mind by reverend Isaac Watts (1674-1748), first time published in 1741 to analyze the methodology used by the scientist/educator, along with other thinkers such as John Locke (1632-1704). We briefly discuss the life of the researcher, plotting a path, which allows us to put in first plan her profile as an educator. After an explanation of The Improvement of the Mind of Isaac Watts, literary work widely used by researchers such as Michael Faraday (1791-1867) and Jane Marcet (1769-1858) and that we use as a basis of the characterization of each one of the ten physic classes taught by Madame Curie in the referred project, we pass to the very core of our study, which demanded an enormous care to not exceed the proposals of contemporary analysis.
15

Sobre o \'Caso Marie Curie\' - A radioatividade e a subversão do gênero / Marie Curie\'s case: the radioactivity and the subversion of gender

Gabriel Pugliese Cardoso 21 September 2009 (has links)
Trata-se de um estudo do Caso Marie Curie sob o signo do acontecimento: como a luta desigual de Marie Curie em favor da radioatividade foi suscitada pela possibilidade de afirmar isso é científico. Essa pesquisa se debruça sobre as controvérsias em torno da radioatividade entre os anos 1898 e 1911, que envolveram toda uma política sexual (e depois nacionalista). Em meio a esse conjunto de relações de poder que tornou indissociáveis os assuntos humanos e a gestão-produção das coisas, exploro como esse acontecimento criou uma problematização para os contemporâneos, desabrochando em uma política singular. Recolocar e extrair o caráter auto-evidente da produção de Marie Curie e da radioatividade é um dos objetivos dessa dissertação. Enfim, desejo fazer aparecer uma aclimatação que corrompeu tanto o gênero quanto a ciência, produzindo de modo singular Marie Curie como um ícone da história da ciência, bem como a radioatividade com um fenômeno universal. / It is about a study of Marie Curie Case under the sign of the : how an unequal conflict of Marie Curie in favor of the radioactivity was raised by the possibility of affirming this is scientific. This search focuses on the controversies surrounding the radioactivity between the years 1898 and 1911, which involved a sexual (and after nationalist) politics. In the midst of this set of power relations that made the human affairs and the production-management of things inseparable, I explore how these created a problematization to the contemporaries, unclasping a singular politics. This dissertation aims at replacing and extracting the selfevident character of the production of Marie Curie and radioactivity. Finally, I desire to display an acclimatization that corrupted both gender and science, producing Marie Curie as an icon of science history, and the radioactivity as an universal phenomenon.
16

Vida de cientista: um estudo sobre a construção da biografia de Mme Curie (1867-1934)

Tonetto, Sonia Regina 13 May 2009 (has links)
Made available in DSpace on 2016-04-28T14:16:39Z (GMT). No. of bitstreams: 1 Sonia Regina Tonetto.pdf: 626804 bytes, checksum: c63e9e43e4f66f52141b6a21a0d3e6ce (MD5) Previous issue date: 2009-05-13 / Secretaria da Educação do Estado de São Paulo / The object of analysis of this study is the first biography of Madame Curie, written by her daughter Eve Curie. This book portrays the historical period, family life and the rise of the professional scientist. The first chapter reviews the author's intent in building the image of the biographied. The expressions used, the chosen facts to be portrayed. The selected correspondence is also analyzed as part of building of this image. In the second chapter, the works of Eulália Sedeño Peres and Margaret W. Rossiter are used as reference to analyze both, the path followed by the scientist and her strategies. The attitudes and reactions of Mme. Curie, facing different situations and in different periods are analyzed in the scientist's correspondence with family and friends and other events in the life of the scientist that don t appear in the biography written by her daughter. The third chapter discusses the work of the scientist in the laboratory. The working conditions, the equipment developed by Pierre Curie, some factors that led the scientist to focus her studies on radioactive materials and the consequences of that choice. Moreover, facts reported are discussed in biography written by Eve Curie and others that were missing and could blacken her image. Thus, the analysis of the biography written by Eve Curie, other biographies and subsequent studies carried on the work of Mme Curie, show the importance of the biography for the History of the Science and the intent of the biographer to write about the history of a scientist / O objeto de análise deste estudo é a primeira biografia sobre Mme Curie, escrita por sua filha Eve Curie. Esta obra retrata o período histórico, a vida familiar e a ascensão profissional da cientista. No primeiro capítulo é analisada a intencionalidade da autora na construção da imagem da biografada. As expressões utilizadas, os fatos escolhidos para serem retratados. A correspondência selecionada também é analisada como parte da construção dessa imagem. No segundo capítulo as obras de Eulália Peres Sedeño e Margaret W. Rossiter são utilizadas como referência para analisar tanto o caminho seguido pela cientista quanto suas estratégias. As atitudes e reações de Mme. Curie, diante de diferentes situações e em diversos períodos, são analisados nas correspondências da cientista com familiares e amigos, além de outros fatos ocorridos na vida da cientista e que não aparecem na biografia escrita por sua filha. O terceiro capítulo aborda o trabalho da cientista no laboratório. As condições de trabalho, os equipamentos desenvolvidos por Pierre Curie. Alguns fatores que levaram a cientista a focalizar seus estudos nos materiais radioativos e as conseqüências dessa escolha. Além disso, são discutidos fatos relatados na biografia escrita por Eve Curie e outros que foram omitidos e poderiam denegrir sua imagem. Dessa forma, a análise da biografia escrita por Eve Curie, de outras biografias posteriores e dos estudos desenvolvidos sobre o trabalho de Mme Curie, mostrará a importância da biografia para a História da Ciência, além de pontuar a intencionalidade do biógrafo ao escrever sobre a história de um cientista
17

Chování feroelektrik v teplotní oblasti / The behaviour of ferroelectrics in the temperature range

Czanadi, Jindřich January 2012 (has links)
The submitted thesis describes characteristics and use of the ferroelectric material which has their utilization in electronics and electro technical industry. The thesis describes behaviour ferroelectrics in temperature range. A suitable workplace was designed and its functionality was verified in selected ferroelectrics samples dependence of temperature of components of complex permittivity.
18

Vlastnosti perspektivních feroelektrických materiálů / Properties of the perspective ferroelectric materials

Krejčí, Josef January 2012 (has links)
This thesis studies the properties and the applications of prospective ferroelectric materials which are used in electrical engineering and electronic industry. Further are physically explained and mathematically described the basic principles running in their structure. The practical part is aimed to build a workplace for measuring the components of the complex permittivity in the frequency and temperature area, controlled by the programmed measurement and service application using the Agilent VEE Pro 8.0 and MS Excel. The functionality of the workplace was verified on the selected material samples by measurement and evaluation of selected properties. For this issue was created electronic text, which can be used as a guide for laboratory exercises and it is an integral part of this work.
19

Curie temperature and magnetic phase transition of nanostructured ultrathin Fe/GaAs(001) size dependence and relevance of dipolar coupling

Meier, Roland January 2009 (has links)
Zugl.: Regensburg, Univ., Diss., 2009
20

Pfalz-Neuburg und die kurie; beiträge zur geschichte der politischen agenten des 17. jahrhunderts ...

Kühn-Steinhausen, Hermine, January 1936 (has links)
Thesis--München.

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