Literatura científica selecionada sobre o tema "Analyse ellipsoïdale"
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Teses / dissertações sobre o assunto "Analyse ellipsoïdale"
Zammali, Chaima. "Robust state estimation for switched systems : application to fault detection". Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS124.
Texto completo da fonteThis thesis deals with state estimation and fault detection for a class of switched linear systems. Two interval state estimation approaches are proposed. The first one is investigated for both continuous and discrete-time linear parameter varying switched systems subject to measured polytopic parameters. The second approach is concerned with a new switching signal observer, combining sliding mode and interval techniques, for a class of switched linear systems with unknown input. State estimation remains one of the fundamental steps to deal with fault detection. Hence, robust solutions for fault detection are considered using set-membership theory. Two interval techniques are achieved to deal with fault detection for discrete-time switched systems. First, a commonly used interval observer is designed based on an L∞ criterion to obtain accurate fault detection results. Second, a new interval observer structure (TNL structure) is investigated to relax the cooperativity constraint. In addition, a robust fault detection strategy is considered using zonotopic and ellipsoidal analysis. Based on optimization criteria, the zonotopic and ellipsoidal techniques are used to provide a systematic and effective way to improve the accuracy of the residual boundaries without considering the nonnegativity assumption. The developed techniques in this thesis are illustrated using academic examples and the results show their effectiveness
Saint-Guirons, Anne-Gaëlle. "Construction et analyse de conditions absorbantes de type Dirichlet-to-Neumann pour des frontières ellipsoïdales". Phd thesis, Université de Pau et des Pays de l'Adour, 2008. http://tel.archives-ouvertes.fr/tel-00356994.
Texto completo da fonteSaint-Guirons, Anne-Gaëlle. "Construction et analyse de conditions absorbantes de type Diritchlet-to-Neumann pour des frontières ellipsoïdales". Pau, 2008. http://tel.archives-ouvertes.fr/docs/00/35/69/94/PDF/TheseAGStGuirons_HALinria.pdf.
Texto completo da fonteNew approximate local DtN boundary conditions are proposed to be set on elliptical- or prolate-spheroidal exterior boundaries when solving respectively two- or three-dimensional acoustic scattering problems by elongated obstacles. These new absorbing conditions are designed to be exact for the first modes. They can be easily incorporated in any finite element parallel code while preserving the local structure of the algebraic system. Moreover, since the proposed conditions are applicable to exterior elliptical-shaped boundaries that are more suitable for surrounding elongated scatterers, they yield to smaller computational domains which contributes to limit computational burden. In the low frequency regime, using an on-surface radiation condition formulation, we perform the mathematical and numerical analysis of the effect of the frequency and the eccentricity values of the boundary on the accuracy of these conditions, when applied for solving radiating and scattering problems (2D and 3D). It reveals - in particular - that the new second-order DtN boundary condition retains a very good level of accuracy regardless of the slenderness of the boundary. In the high frequency regime we study the volumic formulation of the problem. It shows that it is not necessary to consider a big computational domain around the scatterer to obtain accurate results with the new second-order local DtN condition. The high frequency analysis of the reflection coefficient shows that it tends to 0 for propagative modes and it converges exponentially towards 0 for a special class of propagative, grazing and evanescent modes
Madou, Komlanvi. "Contribution à l'étude des effets de forme des cavités en rupture ductile des métaux". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00833021.
Texto completo da fonteMadou, Komlanvi. "Contribution à l'étude des effets de forme des cavités en rupture ductile des métaux". Phd thesis, Paris 6, 2012. http://www.theses.fr/2012PA066245.
Texto completo da fonteDuctile fracture of materials occurs by nucleation, growth and coalescence of microvoids. The most classical model describing the voids growth in plastic porous materials is introduced by Gurson. This model was derived from limit-analysis of a hollow sphere subjected to conditions of homogeneous boundary strain rate. Gurson’s model was extended to spheroidal, both prolate and oblate voids by Gologanu et al. In this work, we further extend Gologanu et al’s model to general ellipsoidal voids. In a first step, the velocity field satisfying conditions of homogenous strain rate on all ellipsoids confocal with the void and the outer boundary, discovered by Leblond and Gologanu, is used in a limit-analysis of an ellipsoidal domain. A Gurson-like approximate yield function is obtained. In a second step, the preceding limit-analysis is improved: (i) For hydrostatic loadings, by performing micromechanical finite element computations in a number of significant cases; (ii) For deviatoric loadings, by directly using some general rigorous results for nonlinear composites. In a third step, the yield function proposed is validated versus a number of numerical computations of yield surfaces of hollow cells of various ellipsoidal shapes. In a fourth step, suitable evolution equations for the shape and orientation of the voids in plastic material are defined. The last step is devoted to the implementation of the Hill’s criterion in SYSTUS software and makes it possible to consider the extension of the model to plastic anisotropic materials
Loukkas, Nassim. "Synthèse d'observateurs ensemblistes pour l’estimation d’état basées sur la caractérisation explicite des bornes d’erreur d’estimation". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT040/document.
Texto completo da fonteIn This work, we propose two main new approaches for the set-membershipstate estimation problem based on explicit characterization of the estimation error bounds. These approaches can be seen as a combination between a punctual observer and a setmembership characterization of the observation error. The objective is to reduce the complexity of the on-line implimentation, reduce the on-line computation time and improve the accuracy of the estimated state enclosure.The first approach is a set-membership observer based on ellipsoidal invariant sets for linear discrete-time systems and also for Linear Parameter Varying systems. The proposed approach provides a deterministic state interval that is build as the sum of the estimated system states and its corresponding estimation error bounds. The important feature of the proposed approach is that does not require propagation of sets.The second approach is an interval version of the Luenberger state observer for uncertain discrete-time linear systems based on interval and invariant set computation. The setmembership state estimation problem is considered as a punctual state estimation issue coupled with an interval characterization of the estimation error
Lu, Chia Yu. "Contribution à l'étude de la déformation de la paléomarge téthysienne dans les Alpes occidentales. Analyses tectoniques et microtectoniques dans la zone des brèches de Tarentaise ( région de Moutiers) et dans les schistes lustrés du Mont Jovet . Alpes françaises". Phd thesis, 1985. http://tel.archives-ouvertes.fr/tel-00547430.
Texto completo da fonteLivros sobre o assunto "Analyse ellipsoïdale"
Linear programming. New York: Birkhäuser, 2009.
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