# A melhor ferramenta para a sua pesquisa, trabalho e TCC!

Página 2 dos resultados de 435 itens digitais encontrados em 0.011 segundos

## ‣ "Recuperação de imagens por conteúdo através de análise multiresolução por Wavelets" ; "Content based image retrieval through multiresolution wavelet analysis

Fonte: Biblioteca Digitais de Teses e Dissertações da USP
Publicador: Biblioteca Digitais de Teses e Dissertações da USP

Tipo: Dissertação de Mestrado
Formato: application/pdf

Publicado em 28/02/2003
Português

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#base de dados de imagens#content based image retrieval#feature vector#filtros Gabor#Gabor filters#image database#Recuperação de imagens por conteúdo#transformada de Wavelets#vetor de características#Wavelets transform

Os sistemas de recuperação de imagens por conteúdo (CBIR -Content-based Image Retrieval) possuem a habilidade de retornar imagens utilizando como chave de busca outras imagens. Considerando uma imagem de consulta, o foco de um sistema CBIR é pesquisar no banco de dados as "n" imagens mais similares à imagem de consulta de acordo com um critério dado. Este trabalho de pesquisa foi direcionado na geração de vetores de características para um sistema CBIR considerando bancos de imagens médicas, para propiciar tal tipo de consulta. Um vetor de características é uma representação numérica sucinta de uma imagem ou parte dela, descrevendo seus detalhes mais representativos. O vetor de características é um vetor "n"-dimensional contendo esses valores. Essa nova representação da imagem pode ser armazenada em uma base de dados, e assim, agilizar o processo de recuperação de imagens. Uma abordagem alternativa para caracterizar imagens para um sistema CBIR é a transformação do domínio. A principal vantagem de uma transformação é sua efetiva caracterização das propriedades locais da imagem. Recentemente, pesquisadores das áreas de matemática aplicada e de processamento de sinais desenvolveram técnicas práticas de "wavelet" para a representação multiescala e análise de sinais. Estas novas ferramentas diferenciam-se das tradicionais técnicas de Fourier pela forma de localizar a informação no plano tempo-freqüência; basicamente...

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## ‣ Wavelets and decision trees for target detection over sea surface using cosmo-skymed SAR data

Fonte: Universidade Estadual Paulista
Publicador: Universidade Estadual Paulista

Tipo: Conferência ou Objeto de Conferência
Formato: 582-589

Português

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#decision trees#remote sensing#SAR#target detection#wavelets#Data source#Descriptors#Image descriptors#Maritime surveillance#Oblique decision tree#Ocean feature

We are investigating the combination of wavelets and decision trees to detect ships and other maritime surveillance targets from medium resolution SAR images. Wavelets have inherent advantages to extract image descriptors while decision trees are able to handle different data sources. In addition, our work aims to consider oceanic features such as ship wakes and ocean spills. In this incipient work, Haar and Cohen-Daubechies-Feauveau 9/7 wavelets obtain detailed descriptors from targets and ocean features and are inserted with other statistical parameters and wavelets into an oblique decision tree. © 2011 Springer-Verlag.

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## ‣ Physical wavelets and their sources: Real physics in complex spacetime

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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#Mathematical Physics#General Relativity and Quantum Cosmology#Mathematics - Analysis of PDEs#Mathematics - Complex Variables

For the first time, complete source distributions for the emission and
absorption of acoustic and electromagnetic wavelets are defined and computed,
both in spacetime and Fourier space. The biggest surprise is the great
simplicity of the Fourier sources as compared to the rather convoluted
spacetime expressions obtained from the original wavelets. This suggests that
the associated pulsed-beam propagators may play a fundamental role in emission
and absorption processes including focus or "directivity." It also opens the
way to constructing FFT-based algorithms for pulsed-beam analyses of acoustic
and electromagnetic waves.; Comment: 56 pages, 3 figures. Invited "Topical Review" article for Journal of
Physics A: Mathematical and General, http://www.iop.org/journals/jphysa

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## ‣ Groups, Wavelets, and Wavelet Sets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 23/07/2003
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Wavelet and frames have become a widely used tool in mathematics, physics,
and applied science during the last decade. This article gives an overview over
some well known results about the continuous and discrete wavelet transforms
and groups acting on $\mathbb{R}^n$. We also show how this action can give rise
to wavelets, and in particular, MSF wavelets)in $L^2(\mathbb{R}^n)$.

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## ‣ A Smirnov-Bickel-Rosenblatt theorem for compactly-supported wavelets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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#Mathematics - Statistics Theory#Mathematics - Numerical Analysis#62G20 (Primary), 62G07, 62G08, 62G15, 65T60 (Secondary)

In nonparametric statistical problems, we wish to find an estimator of an
unknown function f. We can split its error into bias and variance terms;
Smirnov, Bickel and Rosenblatt have shown that, for a histogram or kernel
estimate, the supremum norm of the variance term is asymptotically distributed
as a Gumbel random variable. In the following, we prove a version of this
result for estimators using compactly-supported wavelets, a popular tool in
nonparametric statistics. Our result relies on an assumption on the nature of
the wavelet, which must be verified by provably-good numerical approximations.
We verify our assumption for Daubechies wavelets and symlets, with N = 6, ...,
20 vanishing moments; larger values of N, and other wavelet bases, are easily
checked, and we conjecture that our assumption holds also in those cases.

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## ‣ Wavelets from Laguerre polynomials and Toeplitz-type operators

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

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#Mathematics - Functional Analysis#Mathematical Physics#Mathematics - Operator Algebras#47B35 (Primary), 42C40, 47G30 (Secondary), 47L80

We study Toeplitz-type operators with respect to specific wavelets whose
Fourier transforms are related to Laguerre polynomials. On the one hand, this
choice of wavelets underlines the fact that these operators acting on wavelet
subspaces share many properties with the classical Toeplitz operators acting on
the Bergman spaces. On the other hand, it enables to study poly-Bergman spaces
and Toeplitz operators acting on them from a different perspective. Restricting
to symbols depending only on vertical variable in the upper half-plane of the
complex plane these operators are unitarily equivalent to a multiplication
operator with a certain function. Since this function is responsible for many
interesting features of these Toeplitz-type operators and their algebras, we
investigate its behavior in more detail. As a by-product we obtain an
interesting observation about the asymptotic behavior of true polyanalytic
Bergman spaces. Isomorphisms between the Calder\'on-Toeplitz operator algebras
and functional algebras are described and their consequences are discussed.; Comment: 31 pages, v2: some parts substantially rewritten, 3 metapost figures
added, some corrections made, references updated

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## ‣ Non-Haar $p$-adic wavelets and their application to pseudo-differential operators and equations

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 25/08/2008
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#Mathematical Physics#Mathematics - General Mathematics#11F85, 42C40, 47G30 (Primary)#26A33, 46F10 (Secondary)

In this paper a countable family of new compactly supported {\em non-Haar}
$p$-adic wavelet bases in ${\cL}^2(\bQ_p^n)$ is constructed. We use the wavelet
bases in the following applications: in the theory of $p$-adic
pseudo-differential operators and equations. Namely, we study the connections
between wavelet analysis and spectral analysis of $p$-adic pseudo-differential
operators. A criterion for a multidimensional $p$-adic wavelet to be an
eigenfunction for a pseudo-differential operator is derived. We prove that
these wavelets are eigenfunctions of the fractional operator. In addition,
$p$-adic wavelets are used to construct solutions of linear and semi-linear
pseudo-differential equations. Since many $p$-adic models use
pseudo-differential operators (fractional operator), these results can be
intensively used in these models.

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## ‣ Wavelets Beyond Admissibility

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 24/11/2009
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#Mathematics - Functional Analysis#Mathematical Physics#Mathematics - Complex Variables#43A85, 32M99, 43A32, 46E10, 47A60, 47A67, 47C99

The purpose of this paper is to articulate an observation that many
interesting type of wavelets (or coherent states) arise from group
representations which are not square integrable or vacuum vectors which are not
admissible. This extends an applicability of the popular wavelets construction
to classic examples like the Hardy space.
Keywords: Wavelets, coherent states, group representations, Hardy space,
functional calculus, Berezin calculus, Radon transform, Moebius map, maximal
function, affine group, special linear group, numerical range.; Comment: 7 pages, LaTeX2e

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## ‣ Extended MacMahon-Schwinger's Master Theorem and Conformal Wavelets in Complex Minkowski Space

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

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#Mathematical Physics#Mathematics - Combinatorics#Mathematics - Functional Analysis#Mathematics - Representation Theory#42C, 43A, 22E70, 05A10, 81R

We construct the Continuous Wavelet Transform (CWT) on the homogeneous space
(Cartan domain) D_4=SO(4,2)/(SO(4)\times SO(2)) of the conformal group SO(4,2)
(locally isomorphic to SU(2,2)) in 1+3 dimensions. The manifold D_4 can be
mapped one-to-one onto the future tube domain C^4_+ of the complex Minkowski
space through a Cayley transformation, where other kind of (electromagnetic)
wavelets have already been proposed in the literature. We study the unitary
irreducible representations of the conformal group on the Hilbert spaces
L^2_h(D_4,d\nu_\lambda) and L^2_h(C^4_+,d\tilde\nu_\lambda) of square
integrable holomorphic functions with scale dimension \lambda and continuous
mass spectrum, prove the isomorphism (equivariance) between both Hilbert
spaces, admissibility and tight-frame conditions, provide reconstruction
formulas and orthonormal basis of homogeneous polynomials and discuss symmetry
properties and the Euclidean limit of the proposed conformal wavelets. For that
purpose, we firstly state and prove a \lambda-extension of Schwinger's Master
Theorem (SMT), which turns out to be a useful mathematical tool for us,
particularly as a generating function for the unitary-representation functions
of the conformal group and for the derivation of the reproducing (Bergman)
kernel of L^2_h(D_4...

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## ‣ Compactly Supported One-cyclic Wavelets Derived from Beta Distributions

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 07/02/2015
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New continuous wavelets of compact support are introduced, which are related
to the beta distribution. They can be built from probability distributions
using 'blur'derivatives. These new wavelets have just one cycle, so they are
termed unicycle wavelets. They can be viewed as a soft variety of Haar wavelets
whose shape is fine-tuned by two parameters a and b. Close expressions for beta
wavelets and scale functions as well as their spectra are derived. Their
importance is due to the Central Limit Theorem applied for compactly supported
signals.; Comment: 7 pages, 4 figures. Journal of Communication and Information Systems,
former Journal of the Brazilian Telecommunications Society, ISSN 1980-6604
pp.105-111

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## ‣ Compactly Supported Wavelets Derived From Legendre Polynomials: Spherical Harmonic Wavelets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 03/02/2015
Português

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A new family of wavelets is introduced, which is associated with Legendre
polynomials. These wavelets, termed spherical harmonic or Legendre wavelets,
possess compact support. The method for the wavelet construction is derived
from the association of ordinary second order differential equations with
multiresolution filters. The low-pass filter associated with Legendre
multiresolution analysis is a linear phase finite impulse response filter
(FIR).; Comment: 6 pages, 6 figures, 1 table In: Computational Methods in Circuits and
Systems Applications, WSEAS press, pp.211-215, 2003. ISBN: 960-8052-88-2

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## ‣ Large classes of minimally supported frequency wavelets of L^2(\R) and H^2(\R)

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 17/07/2002
Português

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We introduce a method to construct large classes of MSF wavelets of the Hardy
space H^2(\R) and symmetric MSF wavelets of L^2(\R), and discuss the
classification of such sets. As application, we show that there are uncountably
many wavelet sets of L^2(\R) and H^2(\R). We also enumerate all symmetric
wavelets of L^2(\R) with at most three intervals in the positive axis as well
as 3-interval wavelet sets of H^2(\R). Finally, we construct families of MSF
wavelets of L^2(\R) whose Fourier transform does not vanish in any
neighbourhood of the origin.; Comment: 28 pages

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## ‣ Wavelets and their use

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 16/01/2001
Português

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#High Energy Physics - Phenomenology#Condensed Matter#Mathematical Physics#Mathematics - Numerical Analysis#Nonlinear Sciences - Chaotic Dynamics#Physics - Computational Physics

This review paper is intended to give a useful guide for those who want to
apply discrete wavelets in their practice. The notion of wavelets and their use
in practical computing and various applications are briefly described, but
rigorous proofs of mathematical statements are omitted, and the reader is just
referred to corresponding literature. The multiresolution analysis and fast
wavelet transform became a standard procedure for dealing with discrete
wavelets. The proper choice of a wavelet and use of nonstandard matrix
multiplication are often crucial for achievement of a goal. Analysis of various
functions with the help of wavelets allows to reveal fractal structures,
singularities etc. Wavelet transform of operator expressions helps solve some
equations. In practical applications one deals often with the discretized
functions, and the problem of stability of wavelet transform and corresponding
numerical algorithms becomes important. After discussing all these topics we
turn to practical applications of the wavelet machinery. They are so numerous
that we have to limit ourselves by some examples only. The authors would be
grateful for any comments which improve this review paper and move us closer to
the goal proclaimed in the first phrase of the abstract.; Comment: 63 pages with 22 ps-figures...

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## ‣ Harmonic Singular Integrals and Steerable Wavelets in $L_2(\mathbb{R}^d)$

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 22/02/2013
Português

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Here we present a method of constructing steerable wavelet frames in
$L_2(\mathbb{R}^d)$ that generalizes and unifies previous approaches, including
Simoncelli's pyramid and Riesz wavelets. The motivation for steerable wavelets
is the need to more accurately account for the orientation of data. Such
wavelets can be constructed by decomposing an isotropic mother wavelet into a
finite collection of oriented mother wavelets. The key to this construction is
that the angular decomposition is an isometry, whereby the new collection of
wavelets maintains the frame bounds of the original one. The general method
that we propose here is based on partitions of unity involving spherical
harmonics. A fundamental aspect of this construction is that Fourier
multipliers composed of spherical harmonics correspond to singular integrals in
the spatial domain. Such transforms have been studied extensively in the field
of harmonic analysis, and we take advantage of this wealth of knowledge to make
the proposed construction practically feasible and computationally efficient.; Comment: 27 pages, 2 figures

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## ‣ Errors Theory using Dirichlet Forms, Linear Partial Differential Equations and Wavelets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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We present an application of error theory using Dirichlet Forms in linear
partial differential equations (LPDE). We study the transmission of an
uncertainty on the terminal condition to the solution of the LPDE thanks to the
decomposition of the solution on a wavelets basis. We analyze the basic
properties and a particular class of LPDE where the wavelets bases show their
powerful, the combination of error theory and wavelets basis justifies some
hypotheses, helpful to simplify the computation.; Comment: 17 pages, some misprints corrected

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## ‣ Characterization of wavelets and MRA wavelets on local fields of positive characteristic

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 02/12/2013
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We provide a characterization of wavelets on local fields of positive
characteristic based on results on affine and quasi affine frames. This result
generalizes the characterization of wavelets on Euclidean spaces by means of
two basic equations. We also give another characterization of wavelets.
Further, all wavelets which are associated with a multiresolution analysis on a
such a local field are also characterized.; Comment: arXiv admin note: text overlap with arXiv:1103.0090

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## ‣ Unitary matrix functions, wavelet algorithms, and structural properties of wavelets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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#Mathematics - Classical Analysis and ODEs#Mathematics - Operator Algebras#42C40, 46L60, 47L30, 42A16, 43A65 (Primary)#46L45, 42A65, 41A15
(Secondary)

Some connections between operator theory and wavelet analysis: Since the mid
eighties, it has become clear that key tools in wavelet analysis rely crucially
on operator theory. While isolated variations of wavelets, and wavelet
constructions had previously been known, since Haar in 1910, it was the advent
of multiresolutions, and subband filtering techniques which provided the tools
for our ability to now easily create efficient algorithms, ready for a rich
variety of applications to practical tasks. Part of the underpinning for this
development in wavelet analysis is operator theory. This will be presented in
the lectures, and we will also point to a number of developments in operator
theory which in turn derive from wavelet problems, but which are of independent
interest in mathematics. Some of the material will build on chapters in a new
wavelet book, co-authored by the speaker and Ola Bratteli, see
http://www.math.uiowa.edu/~jorgen/ .; Comment: 63 pages, 10 figures/tables, LaTeX2e ("mrv9x6" document class),
Contribution by Palle E. T. Jorgensen to the Tutorial Sessions, Program:
``Functional and harmonic analyses of wavelets and frames,'' 4-7 August 2004,
Organizers: Judith Packer, Qiyu Sun, Wai Shing Tang. v2 adds Section 2.3.4...

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## ‣ Examples of wavelets for local fields

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 01/12/2003
Português

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#Mathematics - Classical Analysis and ODEs#Mathematics - Number Theory#11S85 (Primary) 42C40 (Secondary)

Using the wavelet theory introduced by the author and J. Benedetto, we
present examples of wavelets on p-adic fields and other locally compact abelian
groups with compact open subgroups. We observe that in this setting, the Haar
and Shannon wavelets (which are at opposite extremes over the real numbers)
coincide and are localized both in time and in frequency. We also study the
behavior of the translation operators required in the theory.; Comment: 21 pages; LaTeX2e; to appear in the proceedings of the AMS Special
Session on Wavelets, Frames, and Operator Theory held at Baltimore, January
2003

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## ‣ Higher Rank Wavelets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 28/08/2008
Português

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A theory of higher rank multiresolution analysis is given in the setting of
abelian multiscalings. This theory enables the construction, from a higher rank
MRA, of finite wavelet sets whose multidilations have translates forming an
orthonormal basis in $L^2(\bR^d)$. While tensor products of uniscaled MRAs
provide simple examples we construct many nonseparable higher rank wavelets. In
particular we construct Latin square wavelets as rank 2 variants of Haar
wavelets. Also we construct nonseparable scaling functions for rank 2 variants
of Meyer wavelet scaling functions, and we construct the associated
nonseparable wavelets with compactly supported Fourier transforms. On the other
hand we show that compactly supported scaling functions for biscaled MRAs are
necessarily separable.; Comment: 35 pages, 3 figures

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## ‣ Applications of the work of Stone and von Neumann to wavelets

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 02/07/2004
Português

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#Mathematics - Functional Analysis#Mathematics - Operator Algebras#Primary 46L99#22D20#22D30#42C40#Secondary 42C15#47C05#47L30

This survey paper examines the work of J. von Neumann and M.H. Stone as it
relates to the abstract theory of wavelets. In particular, we discuss the
direct integral theory of von Neumann and how it can be applied to
representations of certain discrete groups to study the existence of normalized
tight frames in the setting of Gabor systems and wavelets, via the use of group
representations and von Neumann algebras. Then the extension of Stone's theorem
due to M. Naimark, W. Ambrose and R. Godement is reviewed, and its relationship
to the multiresolution analyses of S. Mallat and Y. Meyer and the generalized
multiresolution analyses of L. Baggett, H. Medina, and K. Merrill. Finally, the
paper ends by discussing some recent work due to the author, Baggett, P.
Jorgensen and Merrill, and its relationship to operator theory.; Comment: 27 pages, will appear in Contemporary Mathematics Volume edited by R.
Doran and R. Kadison, minor corrections added

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