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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.
61

Absolutely p-summing and strongly q-summing mappings in normed spaces.

January 1977 (has links)
Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaf [47]
62

Um estudo sobre o polinômio de Hilbert-Samuel /

Mattos, Fabrício Rissão. January 2018 (has links)
Orientador: Parham Salehyan / Banca: Behrooz Mirzaii / Banca: Michelle Ferreira Zanchetta Morgado / Resumo: Neste trabalho definimos o polinômio de Hilbert-Samuel cuja descrição desse polinômio aparecem o foco principal do nosso estudo os coeficientes normalizados de Hilbert. A princípio vamos estudar, sobre determinadas condições iniciais, os sinais dos coeficientes que denotaremos por e0(q,M), e1(q,M) e e2(q,M). Teremos ao final desse trabalho, em formato de comentário, uma condição necessária e suficiente para que todos os coeficientes normalizados de Hilbert sejam nulos / Abstract: In this work we define the Hilbert-Samuel polynomial whose description of this polynomial appear the main focus of our study the normalized Hilbert coefficients. At first, we will study, on certain initial conditions, the signals of the coefficients that we denote by e1 (q, M) e e2 (q, M). We will have at the end of this work, in a comment format, a necessary and sufficient condition so that all normalized Hilbert coefficients are null / Mestre
63

K-theoretic enumerative geometry and the Hilbert scheme of points on a surface

Arbesfeld, Noah January 2018 (has links)
Integrals of characteristic classes of tautological sheaves on the Hilbert scheme of points on a surface frequently arise in enumerative problems. We use the K-theoretic Donaldson-Thomas theory of certain toric Calabi-Yau threefolds to study K-theoretic variants of such expressions. We study limits of the K-theoretic Donaldson-Thomas partition function of a toric Calabi-Yau threefold under certain one-parameter subgroups called slopes, and formulate a condition under which two such limits coincide. We then explicitly compute the limits of components of the partition function under so-called preferred slopes, obtaining explicit combinatorial expressions related to the refined topological vertex of Iqbal, Kos\c{c}az and Vafa. Applying these results to specific Calabi-Yau threefolds, we deduce dualities satisfied by a generating function built from tautological bundles on the Hilbert scheme of points on $\C^2$. We then use this duality to study holomorphic Euler characteristics of exterior and symmetric powers of tautological bundles on the Hilbert scheme of points on a general surface.
64

Identificação e caracterização de não-linearidades em dinâmica estrutural / Identification and characterization of nonlinearities in structural dynamics

Souza, Marcelo Gustavo de 24 March 2008 (has links)
Esta dissertação tem como objetivo principal realizar uma investigação sobre técnicas de identificação e caracterização de não linearidades em dinâmica estrutural. Em particular, busca-se aplicar as transformadas de Hilbert e Hilbert-Huang na identificação e caracterização de um sistema estrutural composto de uma viga metálica em balanço com uma massa concentrada em sua extremidade livre e apresentando uma não linearidade cúbica. Este efeito não linear é obtido através de um fio metálico tracionado que é fixo à extremidade livre da viga em balanço. O sistema é modelado através de ferramentas analíticas convencionais e o modelo do sistema é usado em simulações numéricas. Ensaios experimentais de vibração livre são realizados e os sinais medidos são usados como dados de entradas nas transformadas afim de se investigar o fenômeno não linear presente na estrutura. Os resultados simulados numéricamente apresentaram uma excelente correlação com os resultados experimentais no que se refere à identificação e caracterização do efeito não linear cubico presente no sistema. Algumas distorções entre resultados simulados e experimentais foram observados no que se refere à quantificação do parâmetro não linear, mas de forma geral, as técnicas empregadas produziram resultados bastante satisfatórios. / The major goal of this dissertation is to investigate currently available techniques to the identification and characterization of nonlinearities in structural dynamics. Particular attention is paid to the application of the Hilbert and Hilbert-Huang transforms in the nonlinearity identification and characterization process. For that purpose, a structural system composed of a steel cantilever beam carrying a lumped mass at its free end is used. The nonlinear effect is introduced by attaching the lumped mass to a thin steel wire that is positioned transversely to the beam\'s longitudinal axis. By varying the traction force on this wire different levels of nonlinearity can be observed on the beam\'s bending motion when it undergoes free vibrations. The system analytical model is obtained by employing standard modeling techniques and this model is used in numerical simulations. An experimental survey is carried out on an actual prototype in order to provide a comparison basis for the numerically simulated results. The output vibration signals resulting from either the numerical simulations and experimental tests are then used with the transform methods studied and the results are compared. A good correlation is observed between numerical and experimental data, what is a clear indication of the robustness of the Hilbert and Hilbert-Huang transforms.
65

Schémas de Hilbert et décompositions de tenseurs

Brachat, Jerome 04 July 2011 (has links) (PDF)
Cette thèse est constituée de deux parties. La première regroupe les chapitres 2 et 3 et traite du schéma de Hilbert. Ces chapitres correspondent respectivement à des travaux en collaboration avec M.E. Alonso et B. Mourrain : [3] et avec P. Lella, B. Mourrain et M. Roggero : [10]. Nous nous intéresserons aux équations qui le définissent comme sous-schéma fermé de la grassmannienne et plus précisément à leur degré. Nous fournirons ainsi de nouvelles équations globales, plus simples que celles qui existent déjà. Le chapitre 2 se concentre sur le cas des polynômes de Hilbert constants égaux à μ. Après avoir rappelé les définitions et propriétés élémen- μ taires du foncteur de Hilbert associé à μ, noté HilbPn , nous montrerons que celui-ci est représentable. Nous adopterons pour cela une approche locale et construirons un recouvrement ouvert de sous-foncteurs représen- tables, dont les équations correspondent aux relations de commutation qui caractérisent les bases de bord. Son représentant s'appelle le schéma de Hilbert associé à μ, noté Hilbμ(Pn). Nous fournirons ensuite, grâce aux théorèmes de Persistance et de Régularité de Gotzmann, une description globale de ce schéma. Nous donne- rons un système d'équations homogènes de degré 2 en les coordonnées de Plücker qui caractérise Hilbμ(Pn) comme sous-schéma fermé de la Grassmannienne. Nous conclurons ce chapitre par une étude du plan tangent au schéma de hilbert en exploitant l'approche locale et les relations de commutation précédemment introduites. Le chapitre 3 traite le cas général du schéma de Hilbert associé à un polynôme P de degré d ≥ 0, noté HilbP (Pn). Nous généraliserons le chapitre précédent en fournissant des équations globales homogènes de degré d + 2 en les coordonnées de Plücker. La deuxième partie de cette thèse concerne la décomposition de tenseurs, chapitre 4. Nous commencerons par étudier le cas symétrique, qui correspond à l'article [9] en collaboration avec P. Comon, B. Mourrain et E. Tsi- garidas. Nous étendrons pour cela l'algorithme de Sylvester proposé pour le cas binaire. Nous utiliserons une approche duale et fournirons des conditions nécessaires et suffisantes pour l'existence d'une décomposition de rang donné, en utilisant les opérateurs de Hankel. Nous en déduirons un algorithme pour le cas symétrique. Nous aborderons aussi la question de l'unicité de la décomposition minimale. Enfin, nous conclurons en étu- diant le cas des tenseurs généraux qui correspond à un article en collaboration avec A. Bernardi, P. Comon et B. Mourrain : [6]. Nous montrerons en particulier comment le formalisme introduit pour le cas symétrique peut s'adapter pour résoudre le problème.
66

Phylogenetic Toric Varieties on Graphs

Buczynska, Weronika J. 2010 August 1900 (has links)
We define the phylogenetic model of a trivalent graph as a generalization of a binary symmetric model of a trivalent phylogenetic tree. If the underlining graph is a tree, the model has a parametrization that can be expressed in terms of the tree. The model is always a polarized projective toric variety. Equivalently, it is a projective spectrum of a semigroup ring. We describe explicitly the generators of this projective coordinate ring for graphs with at most one cycle. We prove that models of graphs with the same topological invariants are deformation equivalent and share the same Hilbert function. We also provide an algorithm to compute the Hilbert function, which uses the structure of the graph as a sum of elementary ones. Also, this Hilbert function of phylogenetic model of a graph with g cycles is meaningful for the theory of connections on a Riemann surface of genus g.
67

L' anneau de cohomologie des résolutions crépantes de certaines singularités-quotient

Garino, Sébastien Sorger, Christoph. January 2007 (has links)
Thèse doctorat : Géométrie algébrique : Nantes : 2007. / Bibliographie p. 125-128. Index.
68

Global asymptotics of orthogonal polynomials via Riemann-Hilbert approach /

Zhang, Lun. January 2009 (has links) (PDF)
Thesis (Ph.D.)--City University of Hong Kong, 2009. / "Submitted to Department of Mathematics in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves [95]-100)
69

Spectral theory of normal operators on Hilbert space

Franklin, Monte Alan 08 1900 (has links)
No description available.
70

A class of solutions in non-homogeneous fluid dynamics obtained by the Riemann-invariant method /

Reid, Cynthia, 1958- January 1985 (has links)
No description available.

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