WorldCat Identities

Leblond, Juliette (1963-....).

Works: 25 works in 31 publications in 3 languages and 50 library holdings
Roles: Author, Opponent, Thesis advisor, Editor, Other, htt
Publication Timeline
Most widely held works by Juliette Leblond
Harmonic analysis and rational approximation : their roles in signals, control and dynamical systems by Jean-Daniel Fournier( Book )

2 editions published in 2006 in English and held by 9 WorldCat member libraries worldwide

This book - an outgrowth of a topical summer school - sets out to introduce non-specialists from physics and engineering to the basic mathematical concepts of approximation and Fourier theory. After a general introduction, Part II of this volume contains basic material on the complex and harmonic analysis underlying the further developments presented. Part III deals with the essentials of approximation theory while Part IV completes the foundations by a tour of probability theory. Part V reviews some major applications in signal and control theory. In Part VI mathematical aspects of dynamical systems theory are discussed. Part VII, finally, is devoted to a modern approach to two physics problems: turbulence and the control and noise analysis in gravitational waves measurements
Boundary control and observation of some one dimensional vibrating structures : regularity and stabilization = Controle et observation frontiere de structures vibrantes monodimensionnelles : regularite et stabilisation by Juliette Leblond( Book )

1 edition published in 1991 in English and held by 4 WorldCat member libraries worldwide

Abstract: "We study a class of second order evolution equations with unbounded input-output operators. We establish sufficient conditions for the existence and regularity of both solution and output, and for observability. This makes it possible to apply boundary output feedbacks which, in the linear case, lead to uniform exponential stability. These hypotheses are shown to hold for a beam equation. They are only sufficient conditions: they do not hold for a wave equation which posseses [sic] however the same regularity and stability properties."
Analyse harmonique et approximation rationnelle : leurs rôles en théorie du signal, du contrôle et des systèmes dynamiques : support de cours by Ecole d'été analyse harmonique et approximation rationnelle( Book )

1 edition published in 2003 in Multiple languages and held by 4 WorldCat member libraries worldwide

Shortest paths of bounded curvature in the plane = Plus courts chemins de courbure bornée dans le plan by J.-D Boissonnat( Book )

2 editions published in 1991 in English and held by 3 WorldCat member libraries worldwide

Abstract: "Given two oriented points in the plane, we determine and compute the shortest paths of bounded curvature joining them. This problem has been solved recently, by Dubins in the no-cusp case, and by Reeds and Shepp otherwise. We propose a new solution based on the minimum principle of Pontryagin. Our approach simplifies the proofs and makes clear the global or local nature of the results."
Stabilisation de structures flexibles by Juliette Leblond( Book )

2 editions published in 1989 in French and held by 3 WorldCat member libraries worldwide

Cette thèse concerne l'étude des propriétés de stabilité de structures flexibles simples commandées et observées au moyen d'un nombre fini d'actionneurs et de capteurs ponctuels sur la frontière. La première partie est consacrée à la modélisation du comportement de ce type de structures, en particulier de poutres. Dans la seconde partie, on établit des conditions suffisantes à l'existence et à la régularité des solutions et de la sortie d'équations aux dérivées partielles d'évolution du second ordre en temps, avec opérateurs de contrôle et d'observation non bornés. Ces conditions portent principalement sur les éléments spectraux de l'opérateur de déformation. Enfin, on étudie la stabilisation de ces feedbacks de rang fini sur la frontière, linéaires et sous-linéaires. Les propriétés de stabilité mises en évidence sont illustrées par des simulations numériques du comportement d'une poutre d'Euler-Bernoulli
Best Approximation in Hardy Spaces and by Polynomials, with Norm Constraints by Juliette Leblond( )

1 edition published in 2013 in English and held by 2 WorldCat member libraries worldwide

Some results on feedback stabilization of a one-link flexible arm = Quelques résultats sur la stabilisation d'un bras robot flexible by Sylvie Icart( Book )

1 edition published in 1992 in English and held by 2 WorldCat member libraries worldwide

Abstract: "The aim of this report is to exhibit a class of stabilizing feedback laws for a structurally undamped one-link flexible arm with control applied at one extremity. A finite-dimensional model of the arm, corresponding to a discretization in space, is first considered. The arm is then modeled by a classical partial differential equation, no finite dimensional approximation being made in the control analysis. In both cases, stability of the closed-loop system is proven, using a Lyapunov method and applying Lasalle's principle. The practical significance of the proposed results is commented upon and illustrated by simulation experiments."
Bounded extremal problems in Hardy spaces for the conjugate Beltrami equation in simply-connected domains( )

1 edition published in 2011 in English and held by 2 WorldCat member libraries worldwide

A note on shortest paths in the plane subject to a constraint on the derivative of the curvature by J.-D Boissonnat( Book )

1 edition published in 1994 in English and held by 2 WorldCat member libraries worldwide

Asymptotic Estimates for Interpolation and Constrained Approximation in $ H^2} $ by Diagonalization of Toeplitz Operators by Laurent Baratchart( )

1 edition published in 2003 in English and held by 2 WorldCat member libraries worldwide

Contrôle optimal et métriques de Clairaut-Liouville avec applications by Lionel Jassionnesse( Book )

2 editions published in 2014 in French and held by 2 WorldCat member libraries worldwide

The work of this thesis is about the study of the conjugate and cut loci of 2D riemannian or almost-riemannian metrics. We take the point of view of optimal control to apply the Pontryagin Maximum Principle in the purpose of characterize the extremals of the problem considered.We use geometric, numerical and integrability methods to study some Liouville and Clairaut-Liouville metrics on the sphere. In the degenerate case of revolution, the study of the ellipsoid uses geometric methods to fix the cut locus and the nature of the conjugate locus in the oblate and prolate cases. In the general case, extremals will have two distinct type of comportment which correspond to those observed in the revolution case, and are separated by those which pass by umbilical points. The numerical methods are used to find quickly the Jacobi's Last Geometric Statement : the cut locus is a segment and the conjugate locus has exactly four cusps.The study of an almost-riemannian metric comes from a quantum control problem in which the aim is to transfer in a minimal time the state of one spin through an Ising chain of three spins. After reduction, we obtain a metric with a second first integral so it can be written in the Liouville normal form, which leads us to the equations of geodesics. Outside the particular case of Grushin, of which the caustic is described, we use numerical methods to study the conjugate locus and the cut locus in the general case
Approximation and representation of functions on the sphere : applications to inverse problems in geodesy and medical imaging by Ana-Maria Nicu( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

This work concerns the representation and approximation of functions on a sphere with applications to source localization inverse problems in geodesy and medical imaging. The thesis is structured in 6 chapters as follow : Chapter 1 presents an introduction to the geodesy and M/EGG inverse problems. The inverse problem (IP) consists in recovering a density inside the ball (Earth, human brain) from partially known data on the surface. Chapter 2 gives the mathematical background used along the thesis. The resolution of the inverse problem (IP) involves the resolution of two steps : the transmission data problem (TP) and the density recovery (DR) problem. In practice, the data are only available on some region of the sphere, as a spherical cap, like the north hemisphere of the head (M/EGG) or continent (geodesy). For this purpose, in chapter 3, we give an efficient method to build the appropriate Slepian basis on which we express the data. This is set up by using Gauss-Legendre quadrature. The transmission data problem (chapter 4) consists in estimating the data (spherical harmonic expansion) over the whose sphere from noisy measurements expressed in Slepian basis. The second step, density recovery (DR) problem, is detailed in chapter 5 where we study three density models (monopolar, dipolar and inclusions). For the resolution of (DR), we use a best quadratic rational approximation method on planar sections. We give also some properties of the density and the operator which links it to the generated potential. In chapter 6, we study the chapter 3, 4 and 5 from numerical point of view. We present some numerical tests to illustrate source localization results for geodesy and M/EGG problems when we dispose of partial data on the sphere
Approximation dans des classes de fonctions analytiques généralisées et résolution de problèmes inverses pour les tokamaks by Yannick Fischer( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

Cette thèse traite de la résolution théorique et constructive de problèmes inverses pour des équations de diffusion isotropes dans des domaines plan simplement et doublement connexes. A partir de données de Cauchy (potentiel, flux) disponibles sur une partie de la frontière du domaine, il s'agit de retrouver ces quantités sur la partie du bord où l'on ne dispose pas d'information, ainsi qu'à l'intérieur du domaine. L'approche mise au point consiste à considérer les solutions de l'équation de diffusion comme les parties réelles des solutions complexes d'une équation de Beltrami conjuguée. Ces fonctions analytiques généralisées d'un type particulier permettent de définir des classes de Hardy, dans lesquelles le problème inverse est régularisé en étant reformulé comme un problème de meilleure approximation sous contrainte (ou encore problème extrémal borné, d'adéquation aux données). Le caractère bien posé de celui-ci est assuré par des résultats d'existence et de régularité auxquels s'ajoutent des propriétés de densité à la frontière. Une application au calcul de la frontière libre d'un plasma sous confinement magnétique dans le tokamak Tore Supra (CEA-IRFM Cadarache) est proposée. La résolution du problème extrémal à partir d'une base de fonctions adaptées (harmoniques toroïdales) fournit un critère permettant de qualifier les estimations de la frontière plasma. Un algorithme de descente permet de le faire décroître, en améliorant l'estimation de la frontière. Cette méthode, qui ne requiert pas d'intégration de l'équation dans le domaine, fournit de très bons résultats et semble appelée à connaître des extensions pour d'autres tokamaks tels que JET et ITER
Modèles de conductivité patient-spécifiques : caractérisation de l'os du crâne by Christos Papageorgakis( )

1 edition published in 2017 in English and held by 1 WorldCat member library worldwide

One of the major issues related to electroencephalography (EEG) is to localize where in the brain signals are generated, this is so called inverse problem of source localization. The quality of the source localization depends on the accuracy of the geometry and the electrical conductivity model used to solve the problem. Among the head tissues, the skull conductivity is the one that influences most the accuracy of the source localization, due to its low value. Moreover, the human skull is a bony tissue consisting of compact and spongy bone layers, whose thickness vary across the skull. As the skull tissue composition has strong inter-individual variability both in terms of geometry and of individual conductivity, conductivity estimation techniques are required in order to determine the unknown skull conductivity. The aim of this thesis is to reduce the uncertainty on the skull conductivity both in spherical and realistic head geometries in order to increase the quality of the inverse source localization problem. Therefore, conductivity estimation is first performed on a 3-layered spherical head model. Existence, uniqueness and stability of the conductivity in the intermediate skull layer are discussed, together with a constructive recovery scheme. Then a simulation study is performed comparing two realistic head models, a bulk model where the skull is modelled as a single compartment and a detailed one accounting for the compact and spongy bone layers, in order to determine the importance of the internal skull structure for conductivity estimation in EEG
Un problème inverse de source en sciences planétaires. Localisation d'un dipole magnétique dans des roches lunaires à partir de données magnétiques clairsemées by Konstantinos Mavreas( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Magnetic anomalies on the Moon's surface indicate that the Moon used to have a global magnetic field for millions of years that no longer exist. Geoscientists need to study the remanent magnetization (strength and direction) of Moon rocks, in order to understand the origin and the evolution of this ancient lunar field. This remanent magnetization is preserved from ferromagnetic materials. From non-invasive techniques such as with the use of a spinner magnetometer, the available information is some measurements of the sample's magnetic field. This leads to an inverse problem which is to recover the magnetization characteristics from the field it generates.We use the hypothesis of a single pointwise magnetic source (dipolar model). With such an assumption, an existing approach is to set the magnetic source position at the sample's mass center and then solve a linear problem to recover the magnetization. In this thesis we propose to use the available data to first estimate the location of the dipolar source, which is a nonlinear problem. The magnetization is then recovered as with the other approach, by solving a linear problem.In our study, we observe that there is a relation between the poles of a rational function and the magnetic source location. We use rational approximation schemes to recover the pole of the rational function from its values on a circle. Then we propose several methods to use the link between the recovered pole and the source location, in order to estimate it. Methods like these take advantage of the geometrical features derived from our physical model equations. We conducted numerical experiments to analyze the behavior of these methods and compare their qualities
Propriétés spectrales des opérateurs de composition et opérateurs de Hankel by Lobna Merghni( )

1 edition published in 2017 in French and held by 1 WorldCat member library worldwide

Trace de Dixmier d'opérateurs de Hankel by Romaric Tytgat( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

Hardy approximation to L p functions on subsets of the circle by Laurent Baratchart( Book )

1 edition published in 1994 in English and held by 1 WorldCat member library worldwide

Quelques problèmes inverses avec des données partielles by Dmitry Ponomarev( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

The thesis consists of three parts. In Part I, we consider partially overdeterminedboundary-value problemS for Laplace PDE in a planar simply connected domain withLipschitz boundary. Assuming Dirichlet and Neumann data available on its part to be realvaluedfunctions of certain regularity, we develop a non-iterative method for solving thisill-posed Cauchy problem choosing as a regularizing parameter L2 bound of the solutionon complementary part of the boundary. The present complex-analytic approach alsonaturally allows imposing additional pointwise constraints on the solution which, onpractical side, can help incorporating outlying boundary measurements without changingthe boundary into a less regular one. Part II is concerned with spectral structure of atruncated Poisson operator arising in various physical applications. We deduce importantproperties of solutions, discuss connections with other problems and pursue differentreductions of the formulation for large and small values of asymptotic parameter yieldingsolutions by means of solving simpler integral equations and ODEs. In Part III, we dealwith a particular inverse problem arising in real physical experiments performed withSQUID microscope. The goal is to recover certain magnetization features of a sample frompartial measurements of one component of magnetic field above it. We develop newmethods based on Kelvin and Fourier transformations resulting in estimates of netmoment components
Robust identification in the disc algebra from band-limited data by L Baratchart( Book )

1 edition published in 1995 in English and held by 1 WorldCat member library worldwide

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Audience level: 0.82 (from 0.55 for Stabilisat ... to 0.99 for Hardy appr ...)

Harmonic analysis and rational approximation : their roles in signals, control and dynamical systems