Дисертації з теми "Lorentzian"
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Botros, Amir A. "GEODESICS IN LORENTZIAN MANIFOLDS." CSUSB ScholarWorks, 2016. https://scholarworks.lib.csusb.edu/etd/275.
Повний текст джерелаLeón, Guzmán María Amelia. "Clasificación de toros llanos lorentzianos en espacios tridimensionales." Doctoral thesis, Universidad de Murcia, 2012. http://hdl.handle.net/10803/83824.
Повний текст джерелаA classical problem in Lorentzian geometry is the description of the isometric immersions between Lorentzian spaces of constant curvature. We investigate the problem of classifying the isometric immersion from the Lorentz plane into the three-dimensional anti-de Sitter space, providing a representation formula of these isometric immersions in terms of pairs of curves (possibly with singularities) in the hyperbolic plane. We then give an answer to the open problems proposed by Dajczer and Nomizu in 1981. Among all isometric immersions of the Lorentz plane into the anti-de Sitter space, some of them are actually Lorentzian tori (the basic examples are the Hopf tori). As an application of our previous description, we prove that any such torus can be recovered from two closed curves in the hyperbolic plane. Finally, we prove that Lorentzian Hopf tori are the only immersed Lorentzian flat tori in a wide family of Lorentzian three-dimensional Killing submersions.
Leitner, Felipe. "The twistor equation in Lorentzian spin geometry." Doctoral thesis, [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=965107566.
Повний текст джерелаBär, Christian, and Nicolas Ginoux. "Classical and quantum fields on Lorentzian manifolds." Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2012/5997/.
Повний текст джерелаSuhr, Stefan [Verfasser]. "Maximal geodesics in Lorentzian geometry / Stefan Suhr." Freiburg : Universität : Universitätsbibliothek Freiburg, 2010. http://d-nb.info/1008073687/34.
Повний текст джерелаChen, Hao [Verfasser]. "Ball Packings and Lorentzian Discrete Geometry / Hao Chen." Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1054637156/34.
Повний текст джерелаSaloom, Amani Hussain. "Curves in the Minkowski plane and Lorentzian surfaces." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/4451/.
Повний текст джерелаLarssson, Eric. "Lorentzian Cobordisms, Compact Horizons and the Generic Condition." Thesis, KTH, Matematik (Avd.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146276.
Повний текст джерелаHernández, José Javier Cerda. "Ising and Potts model coupled to Lorentzian triangulations." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-18032015-170430/.
Повний текст джерелаO objetivo principal da presente tese é pesquisar : Quais são as propriedades do modelo de Ising e Potts acoplado ao emsemble de CDT? Para estudar o modelo usamos dois métodos: (1) Matriz de transferência e Teorema de Krein-Rutman. (2) Representação FK para o modelo de Potts sobre CDT e dual de CDT. Matriz de transferência permite obter propriedades espectrais da Matriz de transferência utilizando o Teorema de Krein-Rutman [KR48] sobre operadores que conservam o cone de funções positivas. Também obtemos propriedades asintóticas da função de partição e das medidas de Gibbs. Esses propriedades permitem obter uma região onde a energia livre converge. O segundo método permite obter uma região onde a curva crítica do modelo pode estar localizada. Além disso, também obtemos uma cota superior e inferior para a energia livre a volume infinito. Finalmente, utilizando argumentos de dualidade em grafos e expansão em alta temperatura estudamos o modelo de Potts acoplado as triangulações causais. Essa abordagem permite generalizar o modelo, melhorar os resultados obtidos para o modelo de Ising e obter novas cotas, superior e inferior, para a energia livre e para a curva crítica. Além disso, obtemos uma aproximação do autovalor maximal do operador de transferência a baixa temperatura.
Svensson, Maximilian. "On the Construction and Traversability of Lorentzian Wormholes." Thesis, Uppsala universitet, Teoretisk fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388473.
Повний текст джерелаGrotz, Andreas [Verfasser], and Felix [Akademischer Betreuer] Finster. "A Lorentzian quantum geometry / Andreas Grotz. Betreuer: Felix Finster." Regensburg : Universitätsbibliothek Regensburg, 2011. http://d-nb.info/1023282259/34.
Повний текст джерелаBin, Turki Nasser. "Fundamental domains for left-right actions in Lorentzian geometry." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2003726/.
Повний текст джерелаSchemel, Peter. "On the singularitys set of Lorentzian almost Einstein structures." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17546.
Повний текст джерелаAn almost Einstein structure (M,g,sigma) is an n-dimensional connected manifold M equipped with a pseudo-Riemannian metric g and a scale factor sigma in C^infty(M) such that the almost Einstein tensor A[g,sigma] (the trace-free part of Hess[g] sigma + sigma P[g], with Schouten tensor P[g]) vanishes. It generalises the idea of an Einstein manifold in the way that 1/sigma^2 g is an Einstein metric away from the singularity set Sigma = sigma^(-1)(0). The purpose of this thesis is to get a detailed picture of Sigma in Lorentzian signature (-+...+). Part of this thesis is also an index-free survey of selected results on conformally compact Einstein manifolds in Lorentzian signature in the framework of almost Einstein structures. This reformulation is used to suggest a generalisation of the conformal wave equations to arbitrary even dimensions n = 2m > 4.
Davids, Stefan. "A state sum model for (2+1) Lorentzian quantum gravity." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391393.
Повний текст джерелаSchliebner, Daniel. "Contributions to the geometry of Lorentzian manifolds with special holonomy." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17185.
Повний текст джерелаIn the present thesis we study dimensional Lorentzian manifolds with special holonomy, i.e. such that their holonomy representation acts indecomposably but non-irreducibly. Being indecomposable, their holonomy group leaves invariant a degenerate subspace and thus a light-like line. Geometrically, this means that, since being holonomy invariant, this line gives rise to parallel subbundles of the tangent bundle. The thesis uses these and other objects to prove that Lorentian manifolds with Abelian holonomy are geodesically complete. Moreover, we study Lorentzian manifolds with special holonomy and non-negative Ricci curvature on the leaves of the foliation induced by the orthogonal complement of the parallel light-like line whose first Betti number is maximal. Finally, we provide examples of geodesically complete and Ricci-flat Lorentzian manifolds with special holonomy and prescribed full holonomy group.
Dirmeier, Alexander [Verfasser], and Mike [Akademischer Betreuer] Scherfner. "Particular Timelike Flows in Global Lorentzian Geometry / Alexander Dirmeier. Betreuer: Mike Scherfner." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2013. http://d-nb.info/1032693398/34.
Повний текст джерелаDirmeier, Alexander Verfasser], and Mike [Akademischer Betreuer] [Scherfner. "Particular Timelike Flows in Global Lorentzian Geometry / Alexander Dirmeier. Betreuer: Mike Scherfner." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2013. http://nbn-resolving.de/urn:nbn:de:kobv:83-opus-38530.
Повний текст джерелаJÃnior, Eraldo Almeida Lima. "Uniqueness for hypersurfaces immersed on riemannian and lorentzian spaces: results, examples and counter-examples." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14590.
Повний текст джерелаCoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior
In this work we present uniqueness results for constant mean curvature hypersurfaces in Riemannian and Lorentzian products. We dealt with product whose fiber has sectional curvature bounded from below. We considered a certain control in the norm of the gradient of the height function by the norm of the second fundamental form in order to obtain that such a surface is slice. We also obtained uniqueness through integrability conditions in the gradient of the height function. We also presented an extension of a lemma due to Nishikawa which was used to prove the results for the case of maximal surfaces, that is, with zero mean curvature. We have utilized as an essential tool, in the prove of the results, the generalized Omori-Yau maximum principle in one of the latest versions. In the end, we present examples showing and justifying the necessity of required hypothesis in the results.
Neste trabalho, apresentamos resultados de unicidade para hipersuperfÃcies de curvatura mÃdia constante, tanto em um produto Riemanniano como Lorentziano. Tratamos de produtos cuja fibra tenha curvatura seccional limitada por baixo. Para isto, consideramosum certo controle na norma do gradiente da funÃÃo altura pela norma da segunda forma fundamental com o objetivo de obter que tal hipersuperfÃcie deve ser um slice, i.e., uma "fatia". TambÃm obtemos a unicidade atravÃs de condiÃÃes de integrabilidade no gradiente da funÃÃo altura. Apresentamos uma extensÃo de um lema devido a Nishikawa que utilizamos para provar os resultados no caso das superfÃcies mÃximas, ou seja, aquelas com curvatura mÃdia nula. Utilizamos como ferramenta essencial, na prova dos resultados, o princÃpio do mÃximo generalizado de Omori-Yau em suas versÃes mais atuais. Finalmente, apresentamos exemplos que justificam a necessidade das hipÃteses exigidas nos resultados.
Freire, Emanoel Mateus dos Santos. "Representação de Weierstrass em variedades Riemannianas e Lorentzianas." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/55/55135/tde-30102018-145548/.
Повний текст джерелаThe classic Weierstrass Representation Theorem, which makes use of complex analysis to describe a minimal surface immersed in the Euclidean space in terms of holomorphic data, has been extremely useful either to construct new examples of minimal surfaces, rather than to study structural properties of these surfaces. In [24], using the standard harmonic equation, the authors determine a representation formula for simply connected immersed minimal surfaces in a Riemannian manifold. In this case, the holomorphicity condition of the Weierstrass data is a system of partial differential equations with nonconstant coefficients. Therefore, in geral, it is very difficult to determine explicit solutions. However, for particular ambient spaces, these equations become simpler and the formula can be used to produce new examples of conformal minimal immersions. In the three-dimensional Lorentz-Minkowski space a Weierstrass-type representation formula was proved by Kobayashi for spacelike minimal immersions (see [18]), and by Konderak for the case of timelike minimal immersions (see [20]). In the demonstration of these formulas are used the tools of complex and paracomplex analysis, respectively. Recently, in [22] the results of Kobayashi and Konderak were generalized to the case of (spacelike and timelike) minimal surfaces immersed in 3-Lorentzian manifolds. In this dissertation, we will study the Weierstrass representation formula for immersed minimal surfaces in Riemannian and Lorentzian manifolds, that was obtained in the articles [18], [20], [22] and [24].
Turkalj, Ivica [Verfasser], Rudolf [Akademischer Betreuer] Scharlau, and Detlev [Gutachter] Hoffmann. "Reflective Lorentzian lattices of signature (5, 1) / Ivica Turkalj ; Gutachter: Detlev Hoffmann ; Betreuer: Rudolf Scharlau." Dortmund : Universitätsbibliothek Dortmund, 2017. http://d-nb.info/1139892533/34.
Повний текст джерелаTuerxunjiang, Abulikemu. "FDTD measurement of the reflection coefficient associated with total internal reflection from gainy Lorentzian media." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Thesis/Fall2008/A_Tuerxunjiang_120108.pdf.
Повний текст джерелаTitle from PDF title page (viewed on July 10, 2009). "Department of Physics and Astronomy." Includes bibliographical references (p. 64-68).
Chen, Xiaopei. "Ultra-Narrow Laser Linewidth Measurement." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11124.
Повний текст джерелаPh. D.
Schemel, Peter [Verfasser], Helga [Gutachter] Baum, Andreas [Gutachter] Juhl, and Lars [Gutachter] Andersson. "On the singularitys set of Lorentzian almost Einstein structures / Peter Schemel. Gutachter: Helga Baum ; Andreas Juhl ; Lars Andersson." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://d-nb.info/1109846231/34.
Повний текст джерелаSchliebner, Daniel [Verfasser], Helga [Akademischer Betreuer] Baum, Miguel Sánchez [Akademischer Betreuer] Caja, and Charles [Akademischer Betreuer] Frances. "Contributions to the geometry of Lorentzian manifolds with special holonomy / Daniel Schliebner. Gutachter: Helga Baum ; Miguel Sánchez Caja ; Charles Frances." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://d-nb.info/1069896152/34.
Повний текст джерелаCuzzola, Angelo. "Aspects of supergeometry in locally covariant quantum field theory." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10391/.
Повний текст джерелаMehidi, Lilia. "Points conjugués des tores lorentziens." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0295.
Повний текст джерелаIn the first part of this thesis, we give a description of simply connected maximal Lorentzian surfaces whose group of isometries is of dimension 1 (i.e. with a complete Killing field), in terms of a 1-dimensional generally non-Hausdorff Riemannian manifold and a smooth function defined there. Next, we study the geodesic completeness of such surfaces. In the second part which is the main part of this thesis, we give infinitely many new examples of compact Lorentzian surfaces without conjugate points. Further, we study the existence and the stability of this property among Lorentzian metrics with a Killing field. We obtain a new obstruction and prove that the Clifton- Pohl torus and some of our examples are as stable as possible. This shows that in constrast with the Riemannian Hopf theorem, the absence of conjugate points in the Lorentzian setting is neither "special" nor rigid
LIMA, JÚNIOR Eraldo Almeida. "Resultados do tipo Calabi-Bernstein em −R × Hn." Universidade Federal de Campina Grande, 2011. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1244.
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Neste trabalho, apresentamos um estudo das hipersuperfícies tipo-espaço imersas no ambiente −R × Hn, exibindo condições para que tais hipersuperfícies sejam slices {t0}×Hn. Para uma melhor compreensão das demonstrações e dos resultados, inserimos processos de diferenciação, cálculos de gradientes e Laplacianos que, juntamente com o princípio do máximo de Omori-Yau, foram cruciais no desenvolvimento dos resultados que, em sua maioria são do tipo Bernstein. Também incluímos um resultado do tipo Calabi.
In this work we present a study of the spacelike hypersurfaces immersed in the manifold −R × Hn providing sufficient conditions for such hypersurfaces be slices, {t0}×Hn. For a better understanding of the proofs and results, we have added differentiation processes, gradient computations and Laplacians which jointly with the Omori-Yau Maximum Principle were crucial in the developing of the results whose are mostly Bernstein-type. In the elapsing we also included Calabi-type results.
Labeni, Hicham. "Réalisation de métrique CAT(k) sur les surfaces dans les variétés lorentziennes de courbure constante." Thesis, CY Cergy Paris Université, 2020. http://www.theses.fr/2020CYUN1007.
Повний текст джерелаWe prove that any metric with curvature leq k (in the sense of A. D. Alexandrov) on a closed surface is isometric to the induced intrinsic metric on a space-like convex surface in a Lorentzian manifold of dimension 3 with sectional curvature k
Nicotra, Alessandro. "Analytical map between EPRL spin foam models in loop quantum gravity." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23179/.
Повний текст джерелаPrabhu, G. Radhakrishna. "Studies On Surface Plasmon Resonance And Related Experimental Methods Using Fixed Plasmon Angle." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/205.
Повний текст джерелаHassani, Masoud. "Study of cohomogeneity one three dimensional Einstein universe." Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0421/document.
Повний текст джерелаIn this thesis, the conformal actions of cohomogeneity one on the three-dimensional Einstein universe are classified. Our strategy in this study is to determine the representation of the acting group in the group of conformal transformations of Einstein universe up to conjugacy. Also, we describe the topology and the causal character of the orbits induced by cohomogeneity one actions in Einstein universe
Ribeiro, Pedro Lauridsen. "Aspectos estruturais e dinâmicos da correspondência AdS/CFT: Uma abordagem rigorosa." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-14012008-131931/.
Повний текст джерелаWe elaborate a detailed study of certain aspects of (a version of) the AdS/CFT correspondence, conjectured by Maldacena and Witten, between quantum field theories in a gravitational background given by an asymptotically anti-de Sitter (AAdS) spacetime, and conformally covariant quantum field theories in the latter\'s conformal infinity (in the sense of Penrose), aspects such that: (a) are independent from (the pair of) specific models in Quantum Field Theory, and (b) susceptible to a recast in a mathematically rigorous mould. We adopt as a starting point the theorem demonstrated by Rehren in the context of Local Quantum Physics (also known as Algebraic Quantum Field Theory) in anti-de Sitter (AdS) spacetimes, called algebraic holography or Rehren duality. The main body of the present work consists in extending Rehren\'s result to a reasonably general class of d-dimensional AAdS spacetimes (d>3), scrutinizing how the properties of such an extension are weakened and/or modified as compared to AdS spacetime, and probing how non-trivial gravitational effects manifest themselves in the conformal infinity\'s quantum theory. Among the obtained results, we quote: not only does the imposition of reasonably general conditions on bulk null geodesics (whose plausibility we justify through geometrical rigidity techniques) guarantee that our generalization is geometrically consistent with causality, but it also allows a ``holographic\'\' reconstruction of the bulk topology in the absence of horizons and singularities; the implementation of conformal symmetries in the boundary, which we explicitly associate to an intrinsically constructed family of bulk asymptotic isometries, have a purely asymptotic character and is dynamically attained through a process of return to equilibrium, given suitable boundary conditions at infinity; gravitational effects may cause obstructions to the reconstruction of the bulk quantum theory, either by making the latter trivial in sufficiently small regions or due to the existence of multiple inequivalent vacua, which on their turn lead to the existence of solitonic excitations localized around domain walls, similar to D-branes. The proofs make extensive use of global Lorentzian geometry. The language employed for the quantum theories relevant for our generalization of Rehren duality follows the functorial formulation of Local Quantum Physics due to Brunetti, Fredenhagen and Verch, extended afterwards by Sommer in order to incorporate boundary conditions. (An English translation of the full text can be found at arXiv:0712.0401)
Vasconcellos, João Braga de Góes e. "Equações de onda generalizadas e quantização funtorial para teorias de campo escalar livre." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-31052016-103235/.
Повний текст джерелаIn this thesis we present a both mathematical and conceptually rigorous quantization method for the neutral scalar field free of interactions. Initially, we introduce some aspects of the Theory of Distributions and we establish some points of Lorentzian geometry. The rest of the work is divided in two parts: in the first one, we study wave equations on globally hyperbolic Lorentzian manifolds, hence presenting the concept of fundamental solutions within the context of locally defined wave equations. Next, we progressively construct fundamental solutions for the wave operator from the Riesz distribution. Once established a solution to the wave equation in a neighbourhood of a point of the manifold, we move forward to produce a global solution from the extension of the Cauchy problem to the whole manifold. At this stage, fundamental solutions are replaced by Green\'s operators by the imposition of appropriate boundary conditions. In the last part, we present a minimum on the Theory of Categories and Functors. This is followed by the use of this formalism in the development of a second-quantization functor between the category of Lorentzian globally hyperbolic manifolds and the category of nets of C*-algebras obeying Haag-Kastler axioms. Finally, we turn our attention to the particular case of the quantum free scalar field.
Lärz, Kordian. "Global aspects of holonomy in pseudo-Riemannian geometry." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2011. http://dx.doi.org/10.18452/16363.
Повний текст джерелаIn this thesis we study the interaction of holonomy and the global geometry of Lorentzian manifolds and pseudo-Riemannian submanifolds in spaces of constant curvature. In particular, we construct weakly irreducible, reducible Lorentzian metrics on the total spaces of certain circle bundles leading to a construction of Lorentzian manifolds with specified holonomy representations. Then we introduce a Bochner technique for Lorentzian manifolds admitting a nowhere vanishing parallel lightlike vector field whose orthogonal distribution has compact leaves. Finally, we classify normal holonomy representations of spacelike submanifolds in spaces of constant curvature and extend the classification to more general submanifolds.
Cortier, Julien. "Etude mathématique de trous noirs et de leurs données initiales en relativité générale." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20068/document.
Повний текст джерелаThe aim of this thesis is the mathematical study of families of spacetimes satisfying the Einstein's equations of General Relativity. Two methodsare used in this context.The first part, consisting of the first three chapters of this work,investigates the geometric properties of the Emparan-Reall andPomeransky-Senkov families of 5-dimensional spacetimes. We show that they contain a black-hole region, whose event horizon has non-spherical compact cross sections. We construct an analytic extension, and show its maximality and its uniqueness within a natural class in the Emparan-Reallcase. We further establish the Carter-Penrose diagram for these extensions, and analyse the structure of the ergosurface of the Pomeransky-Senkovspacetimes.The second part focuses on the study of initial data, solutions of theconstraint equations induced by the Einstein's equations. We perform agluing construction between a given family of inital data sets andinitial data of Kerr-Kottler-de Sitter spacetimes, using Corvino'smethod.On the other hand, we construct 3-dimensional asymptotically hyperbolicmetrics which satisfy all the assumptions of the positive mass theorem but the completeness, and which display an energy-momentum vector of arbitry causal type
Figueiredo, Vera Lucia Xavier 1948. "Estrutura spinorial em variedades lorentzianas." [s.n.], 1987. http://repositorio.unicamp.br/jspui/handle/REPOSIP/306696.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Ciencia da Computação
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Resumo: Este trabalho tem dois objetivos principais. O primeiro consiste em eslcarecer as diferentes definições e representações de spinores que aparecem na literatura, a saber: Spinores covariantes (c-spinor) definidos como elementos de espaços vetoriais complexos, munidos de um "produto escalar" que não invariantes sob a ação de certos grupos Lie ...Observação: O resumo, na íntegra poderá ser visualizado no texto completo da tese digital
Abstract: This thesis have two main purposes. The first is to clear up the different definitions and representations of spinors appearing in the literature. These are: covafitant iptnofiA (c-spinors) defined as elements of complex vector spaces equiped with a "scalar product" which are invariant under the action of certain Lie groups ...Note: The complete abstract is available with the full electronic digital thesis or dissertations
Doutorado
Doutor em Matemática
Cintra, Adriana Araujo 1985. "Superfícies mínimas em variedades lorentzianas." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307110.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica
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Resumo: Nesta tese estudamos as superfícies mínimas imersas em variedades Lorentzianas. Desenvolvemos uma versão geral da fórmula da representação de Weierstrass para superfícies mínimas do tipo tempo e tipo espaço imersas em uma variedade Lorentziana n-dimensional. Um tratamento especial é apresentado para o caso em que a variedade é um grupo de Lie munido de uma métrica Lorentziana invariante à esquerda. Mais especificamente, tratamos o caso do espaço de Damek-Ricci 4-dimensional, Riemanniano e Lorentziano. Usando a fórmula da representação de Weierstrass mostramos que existe uma única solução do problema de Björling para superfícies imersas em grupo de Lie Lorenzianos. Por fim, apresentamos alguns exemplos de superfícies mínimas construídas através do prolema de Björling para os casos em que os espaços ambientes, dotados de uma métrica Lorentziana invariante à esquerda, são o grupo de Heisenberg de dimensão três, o espaço de De Sitter e o espaço dado pelo produto do plano hiperbólico com a reta real
Abstract: In this thesis we study minimal surfaces immersed in Lorentzian manifolds. First, we develop a general version of the Weierstrass representation formula for timelike and spacelike minimal surfaces immersed in a n-dimensional Lorentzian manifold. A special treatment is presented for the case of a Lie group equipped with a left invariant Lorentzian metric. More specifically, we consider the case of the 4-dimensional Damek-Ricci space, Riemannian and Lorentzian. Applying the Weierstrass representation formula, we prove that there exists a unique solution to the Bj\"{o}rling problem for timelike surfaces immersed in a Lorenzian Lie group, when the initial curve is a timelike or spacelike curve. Finally, we present some examples of minimal surfaces constructed via Bj\"{o}rling problem for the cases in which the ambient manifolds, equipped with a left invariant Lorentzian metric, are the Heisenberg group, the De Sitter space, and the product of the hyperbolic plane and the real line
Doutorado
Matematica
Doutora em Matemática
Shafiq, Muhammad. "Test Charge Response of a Dusty Plasma with Grain Size Distribution and Charging Dynamics." Doctoral thesis, Stockholm : Space and Plasma Physics, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4134.
Повний текст джерелаManfio, Fernando. "Imersões isométricas em 3-variedades Lorentzianas homogêneas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/45/45131/tde-01072008-163534/.
Повний текст джерелаIn this work we prove an isometric embedding theorem in homogeneous Lorentzian manifolds of dimension 3, that were recently classified by Dumitrescu and Zeghib in [11]. We also prove a rigidity result of isometric embeddings of hypersurfaces in semi-Riemannian manifolds endowed with an infinitesimally homogeneous G-structure. In the special case that the semi-Riemannian manifolds are produtcs of the type Q^n_cxR, or Riemannian homogeneous 3-manifolds, the result is proven under wear assumptions.
Van, den Broeck Samuel. "Optique statistique appliquée à la granulométrie submicronique : simulation d'un signal gaussien lorentzien." Rouen, 1998. http://www.theses.fr/1998ROUES020.
Повний текст джерелаEscobar, Montecino Claudia Evelyn. "Classificação das hipersuperfícies lorentzianas de R1n para Rn1+1." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7189.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
In this dissertation we present a result of classi cation of isometric hypersurfaces between Lorentz-Minkowski spaces due to L. K. Graves [5], which generalizes a classic theorem of Hartman and Nirenberg [7], where hypersurfaces were classi ed among Euclidean spaces. The technique we use in this classi cation of hypersurfaces is to rst study the completeness of the relative nullity foliation, and split the demonstration in two cases depending of the foliation be degenerate or not degenerate.
Nesta dissertação apresentamos um resultado de classi cação das hipersuperfícies isométricas entre espaços de Lorentz-Minkowski devida a L. K. Graves [5], o qual generaliza um teorema clássico de Hartman e Nirenberg [7], em que foram classi cadas as hipersuperfícies isométricas entre espaços euclidianos. A técnica que usamos na classi cação dessas hipersuperfícies é estudar primeiro a completitude da folheação de nulidade relativa e dividir a demonstração em dois casos dependendo da folheação ser degenerada ou não degenerada.
Albujer, Brotons Alma Luisa. "Geometría global de superficies espaciales en espacios producto lorentzianos." Doctoral thesis, Universidad de Murcia, 2008. http://hdl.handle.net/10803/10968.
Повний текст джерелаAlong this PhD thesis we study the global geometry of spacelike surfaces, and in particular maximal surfaces, in Lorentzian product spaces. Firstly, we generalize the Calabi-Bernstien theorem when considering maximal surfaces in a Lorentzian product. We also study some local problems, which a posteriori will have important global consequences. The Lorentzian products are part of the family of the generalized Robertson-Walker spaces. Also the steady state type spaces form a subfamily of such spaces. The equivalent surfaces to the maximal ones in a steady state type space are the spacelike surfaces with H=1. In this context, we give a uniqueness result for complete spacelike surfaces with constant mean curvature bounded from the infinity of a steady state type space. Finally, we consider spacelike surfaces with constant Gaussian curvature in Riemannian and Lorentzian product spaces. In this case, we obtain some Calabi-Bernstein type results when M is the sphere S2
Rosa, Valeria Mattos da. "Estabilidade de curvas tipo-tempo fechadas em variedades lorentzianas." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/306273.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
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Resumo: Várias soluções das equações de Einstein admitem curvas tipo-tempo fechadas (CTCs). Estudamos o comportamento deste tipo de curva quanto à estabilidade linear. Analisando as CTCs no universo de Gödel, encontramos que elas são linearmente estáveis, assim como as curvas desse tipo encontradas em um exemplo particular de métrica tipo-Gödel com fundo plano. As CTCs que aparecem no modelo contendo uma única corda cósmica girante também apresentam estabilidade linear. Estudamos todos os exemplos conhecidos de soluções das equações de Einstein que possuem geodésicas tipo-tempo fechadas (CTGs). Encontramos que a CTG apresentada pelos autores da solução dos dois perjeons não é linearmente estável, mas obtivemos condições, para os parâmetros desse modelo, sob as quais ela admite outras CTGs e, sob condições mais restritivas, obtivemos CTGs linearmente estáveis. As CTGs apresentadas por Soares em seu modelo topológico e por Grøn e Johannesen em seu modelo da núvem de cordas não possuem estabilidade linear. Já as CTGs de uma das soluções dada por van Stockum foram analisadas e verificamos que são linearmente estáveis. Encontramos CTGs em um exemplo particular de métrica tipo-Gödel com fundo conformemente plano, e estas também são estáveis. Analisamos, também, a deformação provocada pelo buraco negro de Schwarzschild ao ser colocado em um espaço-tempo com uma corda cósmica girante. Encontramos as CTGs desse espaço-tempo e determinamos as condições para que estas sejam estáveis
Abstract: Several solutions of Einstein¿s field equations admit closed timelike curves (CTCs). We study the linear stability of this kind of curve. We analyze the CTCs in Gödel universe and we find that these curves are stable. The same occurs with the CTCs of a particular case of Gödel-type metric with flat background and with CTCs of a model that contains a single spinning cosmic string. We study all known solutions of Einstein¿s equations that contain closed timelike geodesics (CTGs). We find that the CTG presented by Bonnor and Steadman in their model of two Perjeons is not stable under linear perturbations, but we present conditions to have stable CTGs in this model. The CTGs presented by Soares in his topological model and those presented by Grøn and Johannensen in their model of the cloud of strings are not stable. But, analizing the CTGs presented by Steadman in a solution gave by van Stockum, we conclude that these curves are stable. Besides these known CTGs, we find this kind of curve in a particular case of G¨odel-type metric with conformally flat background and we also find that they are stable. We also study the deformation that a Schwarzschild black hole causes in the spacetime of a single spinning cosmic string. We find the CTGs of this new spacetime and we determine conditions to have linear stability
Doutorado
Fisica-Matematica
Doutor em Matemática Aplicada
Schlenker, Jean-Marc. "Surfaces convexes dans des espaces lorentziens a courbure constante." Palaiseau, Ecole polytechnique, 1994. http://www.theses.fr/1994EPXX0025.
Повний текст джерелаRodriguez, Blanco Esther. "Etude des systèmes lorentziens dans le spectre des quasars." Paris 7, 2005. http://www.theses.fr/2005PA077119.
Повний текст джерелаLorentzen, Kai [Verfasser]. "Systematische Variabilitätsreduktion zur kontinuierlichen Verbesserung von Fließlinien / Kai Lorentzen." Aachen : Shaker, 2012. http://d-nb.info/1067736077/34.
Повний текст джерелаMonclair, Daniel. "Dynamique lorentzienne et groupes de difféomorphismes du cercle." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2014. http://tel.archives-ouvertes.fr/tel-01061010.
Повний текст джерелаNoterdaeme, Pasquier. "Systèmes Lorentziens Lyman-alpha à grand décalage spectral: Etude de l'hydrogène moléculaire." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00414784.
Повний текст джерелаDans cette thèse, j'étudie la présence d'hydrogène moléculaire dans le milieu interstellaire à grand décalage spectral en m'appuyant sur un échantillon unique de systèmes Lorentziens Lyman-alpha observés à grand rapport signal-à-bruit et haute résolution spectrale. Je présente des travaux dont l'objectif est de comprendre les propriétés et les conditions physiques du gaz neutre associé à ces systèmes (température, densité, composition chimique, fraction moléculaire, contenu en poussières, intensité du champ de radiation incident).
J'effectue en parallèle une recherche systématique et une étude statistique des systèmes Lorentziens afin de mesurer le contenu en gaz neutre de l'Univers, caractériser sa distribution et son évolution au cours du temps et contraindre ainsi la formation des galaxies.
Je montre enfin la possibilité de détecter et d'étudier d'autres molécules telles que l'hydrogène moléculaire deutéré et le monoxyde de carbone dans le milieu interstellaire à grand décalage spectral. Les outils d'analyse automatique de spectres développés dans cette thèse ont conduit à la première détection de CO dans un tel milieu, ouvrant la voie à l'astrochimie du milieu interstellaire dans l'Univers lointain.
Noterdaeme, Pasquier. "Systèmes Lorentziens Lyman-α à grand décalage spectral : étude de l'hydrogène moléculaire". Paris 6, 2008. https://tel.archives-ouvertes.fr/tel-00414784.
Повний текст джерелаBelraouti, Mehdi. "Convergence asymptotique des niveaux de temps quasi-concaves dans un espace temps à courbure constante." Phd thesis, Université d'Avignon, 2013. http://tel.archives-ouvertes.fr/tel-00978618.
Повний текст джерела