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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.
1

Finsler Geometry And Its Applications Toelectromagnetism

Cagil, Ayse 01 January 2003 (has links) (PDF)
In this thesis Finsler geometry is extensively reviewed. The geometrization of fields by a Finslerian approach is considered. Also unification of electrodynamics and gravitation with suitable Finslerian metrics is examined.
2

Regularização geométrica para o problema da análise de ativação de raios gama prontos através de nêutrons (PGNAA) em fluidos multifásicos

Silva, Fabiano Barbosa Mendes da 28 August 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-03-18T12:33:39Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese versão final.pdf: 5433826 bytes, checksum: 6273fd08a4dea93aa7b331550a094b78 (MD5) / Made available in DSpace on 2016-03-18T12:33:39Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese versão final.pdf: 5433826 bytes, checksum: 6273fd08a4dea93aa7b331550a094b78 (MD5) Previous issue date: 2015-08-28 / Este estudo baseia-se no problema apresentado em Meric et al. [25], que consiste na utilização da Análise de Ativação de Raios Gama Prontos Através de Nêutrons (PGNAA), para a determinação das frações em peso das principais substâncias que compõem um fluido multifásico[3] obtido em processos de extração de petróleo submarino. Esse método envolve um problema mal-posto e tem suscitado o desenvolvimento de diferentes abordagens para a sua resolução. Levando-se em consideração os espectros obtidos da PGNAA para as substâncias desse fluido, e ainda estudos recentes, foi desenvolvido neste trabalho um processo de geometrização cuja ideia central é arepre-sentação das fases(substâncias presentes no fluido) através de vértices de triângulos ou de tetraedros, respectivamente para o problema com três e quatro fases. Para tal, foi necessária a utilização de importantes conceitos e ferramentas matemáticas, como o método dos mínimos quadrados e a regularização de Tikhonov, com ênfase em suas características geométricas. Foi ainda desenvolvido um caso especial do método de regularização de Tikhonov: a Regularização Geométrica.Esta nova técnica baseia-se no processo de geometrização proposto e determina um modelo de referência para os casos com três e quatro fases, além de promover mudanças de escalas(normalização de dados) e otimização do condicionamento para todas as escolhas de intervalos de coordenadas. Como objetivo de realizar alguns testes para verificar a eficiência da regularização geométrica, foi gerada uma nova substância a partir das já existentes,como auxílio de alguns códigos computacionais. As soluções encontradas foram representadas graficamente (caso com três fases), juntamente com os espectros das substâncias.Por fim, foram determinados os limites do background para o caso com três fases, estabelecendo-se analiticamente uma previsão para sua localização. / This studyisbasedontheproblempresentedinMeric et al. [25], abouttheuseofPromptGamma- Ray NeutronActivationAnalysis(PGNAA)fordeterminingtheweightfractionsofamultiphase flow[3]obtainedinoffshoreoilextractionprocesses.Thismethodinvolvesanill-posedproblem and hasenabledthedevelopmentofdifferentapproachestoitsresolution.Basedbothonthespectra of substancesinthatfluidandrecentstudies,itwasdevelopmentinthisworkageometricprocess whose centralideaistorepresentthephases(substancespresentinthefluid)throughthevertices of trianglesortetrahedrons,respectivelytotheproblemwiththreeorfourphases.Tothisend,the use ofimportantmathematicalconcepsandtoolswereneeded,suchastheleastsquaresmethod and Tikhonovregularization,withemphasisonitsgeometriccharacteristics.Itwaspresenteda special caseofTikhonovregularizationmethod:theGeometricRegularization.Thisnewtechnique is basedontheproposedgeometricprocessanddeterminesareferencemodeltothecasesofthree and fourfases,aswellaspromotingscalechanging(datanormalization)andconditionnumber optimization forallcoordinaterangesofchoices.Inordertoperformsometeststoverifythe efficiencyofgeometricregularization,itwasgeneratedanewsubstancefromtheotherexisting, aided bysomecomputationalcodes.Thesolutionswereplotted(threephasecase)togetherwith spectra ofsubstances.Finally,thelimitsofbackgroundwerecalculatedtothethreephasescase, establishing apreviewforitslocation.
3

Le manuscrit 2884 du Père Mersenne à la bibliothèque de l’Arsenal. Étude et édition critique / Father Mersenne's manuscript 2884 at the Arsenal Library. Study and critical edition

Taveau, Laurence 25 January 2018 (has links)
Le manuscrit 2884 est un autographe du père Mersenne, unique exemplaire conservé à la bibliothèque de l’Arsenal. Cet écrit constitué en livre et chapitres est une théorie spéculative du son et des consonances inachevée. Comme le manuscrit n’a jamais été édité nous en proposons la transcription selon deux pratiques différentes, une selon le modèle de l’École nationale des Chartes et l’autre diplomatique selon le laboratoire de l’ITEM spécialisé dans les brouillons d’écriture. La transcription est complétée par des notes critiques et historiques, une table des théorèmes reconstituée, d’un index des noms propres. Le fac-simile du manuscrit est proposé dans un volume à part. Dans la première partie une étude codicologique permet de situer le manuscrit dans son aspect matériel. Une étude génétique détermine ses liens avec les imprimés du père Mersenne et retrace son parcours général de rédaction. La dernière partie de la thèse tente de cerner les motifs de son abandon par une analyse comparative avec quelques livres de l’Harmonie Universelle. Notre hypothèse de départ repose sur un changement de philosophie naturelle, passage de la philosophie aristotélicienne à la philosophie d’inspiration galiléenne. En effet nous montrons que tout le discours tenu dans le manuscrit 2884 est ontologiquement fondé dans la conception aristotélicienne alors que les mêmes sujets abordés dans l’Harmonie Universelle manifestent une rupture avec ce fondement ontologique ainsi qu’une profonde évolution de ses idées. / Manuscript 2884 is an autograph by Marin Mersenne, a unique document preserved in the Arsenal Library. This writing formed of books and chapters is an unfinished speculative theory of sound and consonance. As the manuscript has never been edited we propose a transcription following two different usages, the first according to the model of the École nationale des Chartes and the second a diplomatic transcription according to the laboratory of the ITEM (Institut des Textes et Manuscrits modernes) specializing in drafts of texts. The transcriptions are supplemented by critical and historical notes, a reconstructed table of theorems and an index of proper names. The facsimile of the manuscript is proposed in a separate volume. In the first part, a codicological study makes it possible to describe the manuscript in its material aspect. A genetic study determines its links with the printed works of Marin Mersenne and traces its general course of writing. The last part of the thesis attempts to define the reasons for its abandonment by a comparative analysis with some books of Harmonie Universelle. Our initial hypothesis supposes a change in natural philosophy, a change from Aristotelian philosophy to a philosophy of Galilean inspiration. We show that the discourse held in manuscript 2884 as a whole is ontologically based in the Aristotelian conception whereas the same subjects approached in Harmonie Universelle show a break with this ontological foundation as well as a profound evolution of Mersenne’s ideas.
4

Laser-Driven Charged Particles as a Dynamical System

Kwa, Kiam Heong 24 September 2009 (has links)
No description available.

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