173,694 research outputs found
A note on Legendre foliations
No full textIn a previous paper the author proved that any flat Legendre foliation on a contact
manifold, under certain natural assumptions, admits an Ehresmann connection. In this note we
extend such result also to the non-flat case
Suite à un appel nominal, le représentant Legendre de Paris a été proclamé président de la Convention nationale, lors de la séance du 16 brumaire an III (6 novembre 1794)
No full textLegendre (de Paris) Louis. Suite à un appel nominal, le représentant Legendre de Paris a été proclamé président de la Convention nationale, lors de la séance du 16 brumaire an III (6 novembre 1794). In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome C - Du 3 au 18 brumaire an III (24 octobre au 8 novembre 1794) Paris : CNRS éditions, 2000. p. 478
Projeto de filtros transicionais baseados em aproximações polinomiais clássicas /
Full text linkDissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Este trabalho propõe uma metodologia de projeto de filtros transicionais passa-baixas que usam seis aproximações clássicas bem conhecidas de filtros polinomiais (Chebyshev, Legendre, Butterworth, Bessel, Gauss e Multiplicidade-n). O projeto leva em conta um gabarito, proporcionando um melhor compromisso entre a magnitude, fase e/ou resposta temporal. Com esta aproximação é possível projetar filtros que têm um desempenho melhor que aqueles projetados com funções polinomiais clássicas ou, mesmo, outros filtros transicionais propostos na literatura. São apresentados exemplos que demonstram os resultados e a eficiência do método proposto
Le représentant Legendre (de la Nièvre) fait son rapport sur les ressources de la République en grains et fers, lors de la séance du 17 brumaire an III (7 novembre 1794)
No full textLegendre (de la Nièvre) François-Paul. Le représentant Legendre (de la Nièvre) fait son rapport sur les ressources de la République en grains et fers, lors de la séance du 17 brumaire an III (7 novembre 1794). In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome C - Du 3 au 18 brumaire an III (24 octobre au 8 novembre 1794) Paris : CNRS éditions, 2000. p. 522
Two New Integral Transforms and Their Applications
Full text linkThis thesis is in two parts. In Part I the independent
variable θ in the trigonometric form of Legendre's equation is
extended to the range ( -∞, ∞). The associated spectral
representation is an infinite integral transform whose kernel
is the analytic continuation of the associated Legendre function
of the second kind into the complex θ-plane. This new transform
is applied to the problems of waves on a spherical shell, heat
flow on a spherical shell, and the gravitational potential of a
sphere. In each case the resulting alternative representation of
the solution is more suited to direct physical interpretation than
the standard forms.
In Part II separation of variables is applied to the
initial-value problem of the propagation of acoustic waves in an
underwater sound channel. The Epstein symmetric profile is taken
to describe the variation of sound with depth. The spectral
representation associated with the separated depth equation is
found to contain an integral and a series. A point source is
assumed to be located in the channel. The nature of the
disturbance at a point in the vicinity of the channel far removed
from the source is investigated.</p
Translation and scale invariants of Legendre moments
No full textBy convention, the translation and scale invariant functions of Legendre moments are achieved by using a combination of the corresponding invariants of geometric moments. They can also be accomplished by normalizing the translated and/or scaled images using complex or geometric moments. However, the derivation of these functions is not based on Legendre polynomials. This is mainly due to the fact that it is difficult to extract a common displacement or scale factor from Legendre polynomials. In this paper, we introduce a new set of translation and scale invariants of Legendre moments based on Legendre polynomials. The descriptors remain unchanged for translated, elongated, contracted and reflected non-symmetrical as well as symmetrical images. The problems associated with the vanishing of odd-order Legendre moments of symmetrical images are resolved. The performance of the proposed descriptors is experimentally confirmed using a set of binary English, Chinese and Latin characters. In addition to this, a comparison of computational speed between the proposed descriptors and the aforesaid geometric moments-based method is also presented. (C) 2003 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved
Le représentant Legendre (de la Nièvre) fait son rapport sur les ressources de la République en grains et fers, lors de la séance du 17 brumaire an III (7 novembre 1794)
No full textLegendre (de la Nièvre) François-Paul. Le représentant Legendre (de la Nièvre) fait son rapport sur les ressources de la République en grains et fers, lors de la séance du 17 brumaire an III (7 novembre 1794). In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome C - Du 3 au 18 brumaire an III (24 octobre au 8 novembre 1794) Paris : CNRS éditions, 2000. p. 522
Palmprint authentication using modified legendre moments
No full textAbstractThe resolution of the acquired biometric image is considered as one of the primary factors affecting the performance of a biometric authentication system. For low quality images, a powerful feature extraction method is very essential. Orthogonal Legendre moments are used in several pattern recognition and image processing applications for feature extraction. Translation and scale invariant Legendre moments are achieved directly by using the Legendre polynomial. However, this method does not yield a rotational invariant form. In this paper we propose a palmprint verification system in which the 2D Legendre moments are represented as a linear combination of geometric moment invariants. Geometric moments are invariant to translation, non-uniform scaling and rotation. The modified Legendre moments are used for feature extraction and a weighted fusion technique is used to fuse the matching scores of the sub-images. The results obtained using a Baye’s classifier indicate an impressive prediction accuracy of 98%, validating the choice of low order Legendre moment for effective palmprint verification
Interaction between two spherical bubbles rising in a viscous liquid
Full text linkThe three-dimensional flow around two spherical bubbles moving in a viscous fluid is studied numerically by solving the full Navier-Stokes equations. The study considers the interaction between two bubbles for moderate Reynolds numbers (50 ≤ Re ≤ 500, Re being based on the bubble diameter) and for positions described by the separation S (2.5 ≤ S ≤ 10, S being the distance between the bubble centres normalized by the bubble radius) and the angle θ (0o ≤ θ ≤ 90o ) formed between the line of centre and the direction perpendicular to the direction of the motion. We provide a general description of the interaction extending the results obtained for two bubbles moving side by side (θ = 0o ) by Legendre, Magnaudet & Mougin 2003 (J. Fluid Mech., 497,133-166) and for two bubbles moving in line (θ = 90o ) by Yuan & Prosperetti 1994 (J. Fluid Mech., 278, 325-349). Simple models based on physical arguments are given for the drag and lift forces experienced by each bubble. The interaction is the combination of three effects: a potential effect, a viscous correction (Moore correction) and a significant wake effect observed on both the drag and the transverse force of the second bubble when located in the wake of the first one
Convection in porous media and Legendre, Chebyshev Galerkin methods
Full text linkThe subject of thermal convection in fluid and porous media is investigated, coupled with the development of efficient spectral finite element methods to improve on the more commonly used techniques for these types of problems. Convection induced by the selective absorption of radiation in a porous medium is investigated in the first four chapters. For the Darcy and Brinkman models for fluid flow the thresholds of the linear and nonlinear theories are shown to be extremely close, demonstrating that the linear theory is accurate enough to predict the onset of convective motion. The exploration of a quadratically modelled internal heat source is discussed next. It is shown that the linear and nonlinear thresholds are close unless the quadratic term becomes dominant over the linear term. Developing a double- diffusive model yields a critical parameter for which no oscillatory convection occurs when it is exceeded. This is an unobserved phenomenon in the present literature. Thermal convection in a linearly viscous fluid in a finite box is also explored. It is demonstrated that the linear and nonlinear thresholds do not coincide, which contradicts results by Georgescu & Mansutti [25]. Legendre and Chebyshev polynomial based spectral methods are also developed for the evaluation of eigenvalues and eigenfunctions inherent in stability analysis in porous media, drawing on the experience of the implementation of the well established techniques in the previous work. These generate sparse matrices, where the standard homogeneous boundary conditions for both porous and fluid media problems are contained within the method
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