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Dissertations / Theses on the topic 'Stability estimates'

Author: Grafiati

Published: 4 June 2021

Last updated: 10 March 2023

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1

Steinbach, Olaf. "Stability estimates for hybrid coupled domain decomposition methods." Berlin ; Heidelberg : Springer, 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967658128.

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2

Ingle, William Nathan. "Stability estimates for inverse problems of some elliptic equations." Diss., Wichita State University, 2011. http://hdl.handle.net/10057/5149.

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In this dissertation we obtain new Carleman formulas for the solution of the Cauchy problem for equations P u = h, in Ω, u|E = f , where E ⊂ ∂Ω and | E | > 0. Our elliptic operator is of the form P = [ [2∂¯ 0 ; 0 2δ ] + A (x), where A is a 2 x 2 matrix. We also obtain estimates for the solution of equation P u = 0 when u is given at a finite number of points, and we prove that non-trivial solutions to the equation can not be small on large portions of the boundary, | Eδ | ≤ c / ln δ−1 , δ ∈ (0, 1), where Eδ = {z ∈ ∂Ω| | u(z) | < δ} and |

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3

Tautenhahn, Ulrich, Uno Hämarik, Bernd Hofmann, and Yuanyuan Shao. "Conditional stability estimates for ill-posed PDE problems by using interpolation." Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-72654.

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The focus of this paper is on conditional stability estimates for ill-posed inverse problems in partial differential equations. Conditional stability estimates have been obtained in the literature by a couple different methods. In this paper we propose a method called interpolation method, which is based on interpolation in variable Hilbert scales. We are going to work out the theoretical background of this method and show that optimal conditional stability estimates are obtained. The capability of our method is illustrated by a comprehensive collection of different inverse and ill-posed PDE p

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4

Feleqi, Ermal. "Spectral stability estimates for the eigenfunctions of second order elliptic operators." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3421876.

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The thesis deals with a new direction in the spectral stability problem of elliptic operators, namely to find estimates for the variation of eigenfunctions due to domain perturbation. Unlike the problem of the variation of the eigenvalues, this problem had practically never been investigated previously. The approach developed in the thesis is based on the concept of "gap'' between linear operators. This concept, which measures the proximity of two unbounded linear operators, extends to the case of operators defined on different domains. Thereafter, there are obtained estimates of the gap

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5

Andersson, Joel. "On Invertibility of the Radon Transform and Compressive Sensing." Doctoral thesis, KTH, Matematik (Avd.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141837.

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This thesis contains three articles. The first two concern inversion andlocal injectivity of the weighted Radon transform in the plane. The thirdpaper concerns two of the key results from compressive sensing.In Paper A we prove an identity involving three singular double integrals.This is then used to prove an inversion formula for the weighted Radon transform,allowing all weight functions that have been considered previously.Paper B is devoted to stability estimates of the standard and weightedlocal Radon transform. The estimates will hold for functions that satisfy an apriori bound. When wei

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6

Weidling, Frederic [Verfasser]. "Variational Source Conditions and Conditional Stability Estimates for Inverse Problems in PDEs / Frederic Weidling." Göttingen : Universitätsverlag Göttingen, 2019. http://d-nb.info/118965363X/34.

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7

Ready, Doreen. "The stability of item parameter estimates in the context of a second language competency test." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9721.

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The purpose of this study was to examine the feasibility of using IRT models to equate test versions of an English second language (ESL) test through the use of subsets of linking items. The test was designed to measure global comprehension at the intermediate level, of listening and reading texts and general knowledge of vocabulary, grammar and structure as measured by a cloze text. The data were subsets of listening, reading and cloze items used on two or more occasions. The procedure used was to ascertain the stability of the item parameter estimates from correlations and other descriptive

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8

Kaye, Tari Eileen Carleton University Dissertation Engineering Mechanical and Aerospace. "Techniques for aircraft force and moment model development using geometry and stability and control derivative estimates." Ottawa, 1994.

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9

Liefvendahl, Mattias. "Stability results for viscous shock waves and plane Couette flow." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3241.

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10

Webb, Benjamin Zachary. "Isospectral graph reductions, estimates of matrices' spectra, and eventually negative Schwarzian systems." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39521.

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This dissertation can be essentially divided into two parts. The first, consisting of Chapters I, II, and III, studies the graph theoretic nature of complex systems. This includes the spectral properties of such systems and in particular their influence on the systems dynamics. In the second part of this dissertation, or Chapter IV, we consider a new class of one-dimensional dynamical systems or functions with an eventual negative Schwarzian derivative motivated by some maps arising in neuroscience. To aid in understanding the interplay between the graph structure of a network and its dynamics

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11

Cao, Xue. "A novel zonal adaptive DG anti-islanding protection scheme to enhance future system stability using real-time inertia estimates." Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27332.

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Emerging power system designs are driven towards supporting the diversity of generation supply through increased flexibility and progressive employment of renewable resources, in order to fulfil sustainable and low carbon energy development strategies. The resulting impact on system response, especially during and following disturbances, can incur negative power system stability issues. With particular attention given to the anticipated reduction and variation of system inertia, concerns are growing with respect to power system frequency stability following large disturbances. This is attribut

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12

Miraglio, Pietro. "Estimates and rigidity for stable solutions to some nonlinear elliptic problems." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/668832.

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My thesis deals with the study of elliptic PDE. It is divided into two parts, the first one concerning a nonlinear equation involving the p-Laplacian, and the second one focused on a nonlocal problem. In the first part, we study the regularity of stable solutions to a nonlinear equation involving the p-Laplacian in a bounded domain. This is the nonlinear version of the widely studied semilinear equation involving the classical Laplacian. Stable solutions to semilinear equations have been very recently proved to be bounded, and therefore smooth, up to dimension n=9 by Cabré, Figalli, Ros-Oto

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13

MIRAGLIO, PIETRO. "ESTIMATES AND RIGIDITY FOR STABLE SOLUTIONS TO SOME NONLINEAR ELLIPTIC PROBLEMS." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/704717.

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Questa tesi è incentrata sullo studio di equazioni differenziali alle derivate parziali di tipo ellittico. La prima parte della tesi riguarda la regolarità delle soluzioni stabili per un'equazione nonlineare con il p-Laplaciano, in un dominio limitato dello spazio Euclideo. La tecnica è basata sull'uso di disuguaglianze di tipo Hardy-Sobolev su ipersuperfici, del quale viene approfondito lo studio. Nella seconda parte viene preso in esame un problema nonlocale di tipo Dirichlet-Neumann. Studiamo la simmetria unidimensionale di alcune sottoclassi di soluzioni stabili, ottenendo risultati in dim

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14

Ben, Aicha Ibtissem. "Etude mathématique de problèmes inverses non autonomes de types hyperbolique et quantique." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4114/document.

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Cette thèse est consacrée à l’étude de problèmes inverses associés à des équations aux dérivées partielles hyperboliques et de type Schrödinger.La première partie de la thèse est consacrée à l’étude de problèmes inverses pour l’équation des ondes. Il s’agit d’examiner les propriétés de stabilité et d’unicité dans l’identification de certains coefficients apparaissant dans l’équation des ondes, à partir de différents types d’observation.La deuxième partie de cette thèse, traite du problème de l’identification du champ magnétique et du potentiel électrique apparaissant dans l’équation du Schrödi

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15

Svärd, Magnus. "Stable High-Order Finite Difference Methods for Aerodynamics." Doctoral thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4621.

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In this thesis, the numerical solution of time-dependent partial differential equations (PDE) is studied. In particular high-order finite difference methods on Summation-by-parts (SBP) form are analysed and applied to model problems as well as the PDEs governing aerodynamics. The SBP property together with an implementation of boundary conditions called SAT (Simultaneous Approximation Term), yields stability by energy estimates. The first derivative SBP operators were originally derived for Cartesian grids. Since aerodynamic computations are the ultimate goal, the scheme must also be stable on

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16

Al-Shanfari, Fatima. "High-order in time discontinuous Galerkin finite element methods for linear wave equations." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15332.

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In this thesis we analyse the high-order in time discontinuous Galerkin nite element method (DGFEM) for second-order in time linear abstract wave equations. Our abstract approximation analysis is a generalisation of the approach introduced by Claes Johnson (in Comput. Methods Appl. Mech. Engrg., 107:117-129, 1993), writing the second order problem as a system of fi rst order problems. We consider abstract spatial (time independent) operators, highorder in time basis functions when discretising in time; we also prove approximation results in case of linear constraints, e.g. non-homogeneous boun

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17

Ramoul, Hichem. "Inégalités de Carleman pour des systèmes paraboliques et applications aux problèmes inverses et à la contrôlabilité : contribution à la diffraction d'ondes acoustiques dans un demi-plan homogène." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10025.

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Dans la première partie, on démontre des inégalités de Carleman pour des systèmes paraboliques. Au chapitre 1, on démontre des inégalités de stabilité pour un système parabolique 2 x 2 en utilisant des inégalités de Carleman avec une seule observation. Il s'agit d'un problème inverse pour l'identification des coefficients et les conditions initiales du système. Le chapitre2 est consacré aux inégalités de Carleman pour des systèmes paraboliques dont les coefficients de diffusion sont de classe C1 par morceaux ou à variations bornées. A la fin, on donne quelques applications à la contrôlabilité

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18

Hofmann, B., and O. Scherzer. "Local Ill-Posedness and Source Conditions of Operator Equations in Hilbert Spaces." Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199800957.

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The characterization of the local ill-posedness and the local degree of nonlinearity are of particular importance for the stable solution of nonlinear ill-posed problems. We present assertions concerning the interdependence between the ill-posedness of the nonlinear problem and its linearization. Moreover, we show that the concept of the degree of nonlinearity com bined with source conditions can be used to characterize the local ill-posedness and to derive a posteriori estimates for nonlinear ill-posed problems. A posteriori estimates are widely used in finite element and multigrid methods fo

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19

Edington, Joy Lynn. "Investigating the Stability of Bootstrapped Confirmatory Factor Analysis Estimates for Multiple Dimensions of the 2010 National Youth Nutrition and Physical Activity Study using Linear Structural Relations (LISREL)." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343847941.

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20

Buoso, Davide. "Shape sensitivity analysis of the eigenvalues of polyharmonic operators and elliptic systems." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3423926.

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In this thesis, we study the dependence of the eigenvalues of elliptic partial dierential operators upon domain perturbations in the N-dimensional space. Namely, we prove analyticity results for the eigenvalues of polyharmonic operators and elliptic systems of second order partial differential equations, and we apply them to certain shape optimization problems. On the other hand, we also prove spectral stability estimates for general elliptic systems of partial differential equations of higher order. In order to prove analyticity, we use a general technique developed by Lamberti and Lan

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21

Amaral, Fabíolo Moraes. "Caracterização, estimativas e bifurcações da região de estabilidade de sistemas dinâmicos não lineares." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-29102010-145102/.

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Estimar a região de estabilidade de um ponto de equilíbrio assintoticamente estável é importante em aplicações tais como sistemas de potência, economia e ecologia. A compreensão da estrutura qualitativa da fronteira da região de estabilidade é fundamental para estimar com eficiência a região de estabilidade. Caracterizações topológicas e dinâmicas da fronteira da região de estabilidade foram desenvolvidas ao longo das últimas décadas. Estas caracterizações foram desenvolvidas sob hipóteses de hiperbolicidade dos pontos de equilíbrio na fronteira e transversalidade. Para sistemas que dependem d

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22

Dang, Thi To Nhu. "Estimation des indices de stabilité et d'autosimilarité par variations de puissances négatives." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAM033/document.

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Ce travail porte sur l'estimation des indices d'autosimilarité et de stabilité d'un processus ou champ stable fractionnaire et autosimilaire ou d'un processus stable multifractionnaire.Plus précisément, soit X un processus ou un champ stable H-autosimilaire à accroissements stationnaires (H-sssi) ou un processus stable multifractionnaire. Nous observons X aux points k/n, k=0,..., n.Nos estimations sont basées sur des variations de puissances négatives beta avec -1/2<br>This work is concerned with the estimation of the self-similarity and the stability indices of a H-self-similarity stable proc

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23

Hodgson, J. E. "A comprehensive method to estimate power system stability constraint costs." Thesis, University of Bath, 1997. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362150.

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24

Ahmed, Faisal Mahmood. "Estimated Droop Control for Parallel Connected Voltage Source Inverters : Stability Enhancement." Thesis, Karlstads universitet, Avdelningen för fysik och elektroteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-30794.

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Renewable Energy Sources (RES) are considered as the replacement of conventionalenergy sources. These RES can use wind energy, solar light, bio waste and can alsobe in the form of small hydro power units. These RES has very poor power qualityand contains voltage uctuations and variable frequency. These factors make RES astability risk for the main utility grid. As a solution, currently inverters with dierentdesign techniques are being used as an interface between RES and main utility grid. Thecurrent study proposed a new technique "estimated droop control" for inverter design.The conventional

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25

He, Yuan. "Analyse et contrôle de modèles de dynamique de populations." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14918/document.

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La présente thèse est divisée en deux parties. La première partie concerne l'analyse mathématique et la contrôlabilité exacte à zéro pour une catégorie de systèmes structurés décrivant la dynamique d'une population d'insectes. La seconde partie est consacrée à l'étude de la stabilité de la conductivité d'un système de réaction diffusion modélisant l'activité électrique du coeur.Dans le chapitre 2, on considère que la population d'adultes se diffuse dans la vignoble,la fonction de la croissance des individus à chaque stade dépend des variations climatiques et de la variété des raisins. En utili

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26

Higashimori, Nobuyuki. "A Conditional Stability Estimate for Identifying a Cavity by an Elastostatic Measurement." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148501.

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27

GARCIA, OLGA CECILIA CARVAJAL. "ESTIMATE OF THE INFLUENCE OF ROCK-DRILLING FLUID INTERACTION ON WELLBORE STABILITY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4141@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>AGÊNCIA NACIONAL DE PETRÓLEO<br>Os problemas na perfuração associados à instabilidade do poço são geralmente agravados quando camadas de folhelho são atravessadas, as quais constituem uma alta porcentagem do total das rochas perfuradas no mundo. O folhelho, quando submetido às tensões in situ, pode atuar como uma membrana semipermeável à passagem de íons através do seus poros. Este comportamento e o desenvolvimento de pressões osmóticas ao redor do poço, desempenham um papel fundamental no balanço das forças que instabiliza

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28

Shikongo, Albert. "Numerical Treatment of Non-Linear singular pertubation problems." Thesis, Online access, 2007. http://etd.uwc.ac.za/usrfiles/modules/etd/docs/etd_gen8Srv25Nme4_3831_1257936459.pdf.

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29

Hofmann, B. "On Ill-Posedness and Local Ill-Posedness of Operator Equations in Hilbert Spaces." Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199801185.

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In this paper, we study ill-posedness concepts of nonlinear and linear inverse problems in a Hilbert space setting. We define local ill-posedness of a nonlinear operator equation $F(x) = y_0$ in a solution point $x_0$ and the interplay between the nonlinear problem and its linearization using the Frechet derivative $F\acent(x_0)$ . To find an appropriate ill-posedness concept for the linarized equation we define intrinsic ill-posedness for linear operator equations $Ax = y$ and compare this approach with the ill-posedness definitions due to Hadamard and Nashed.

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30

Rovnak, Amanda M. "A PSYCHOMETRIC INVESTIGATION OF THE EMOTIONAL QUOTIENT INVENTORY IN ADOLESCENTS: A CONSTRUCT VALIDATION AND ESTIMATE OF STABILITY." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1175100013.

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Dissertation (Ph. D.)--University of Akron, Dept. of Counseling, 2007.<br>"May, 2007." Title from electronic dissertation title page (viewed 04/02/2008) Advisor, Cynthia Reynolds; Committee members, Isadore Newman, Carole Newman, Sandra Perosa, Fred Ziegler; Interim Department Chair, Sajit Zachariah; Dean of the College, Patricia A. Nelson; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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31

Shao, Yuanyuan. "Beiträge zur Regularisierung inverser Probleme und zur bedingten Stabilität bei partiellen Differentialgleichungen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-102801.

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Wir betrachten die lineare inverse Probleme mit gestörter rechter Seite und gestörtem Operator in Hilberträumen, die inkorrekt sind. Um die Auswirkung der Inkorrektheit zu verringen, müssen spezielle Lösungsmethode angewendet werden, hier nutzen wir die sogenannte Tikhonov Regularisierungsmethode. Die Regularisierungsparameter wählen wir aus das verallgemeinerte Defektprinzip. Eine typische numerische Methode zur Lösen der nichtlinearen äquivalenten Defektgleichung ist Newtonverfahren. Wir schreiben einen Algorithmus, die global und monoton konvergent für beliebige Startwerte garantiert. Um

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32

ISAK, ILENA. "STABLE ISOTOPE TRACERS TO ESTIMATE SURFACTANT METABOLISM IN NEWBORNS WITH RESPIRATORY DISTRESS SYNDROME." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427467.

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Aims of the thesis are to describe new applications of stable isotope tracers, applied to study pulmonary surfactant kinetics in human newborns. My PhD project was initially focused on the most suitable metabolic substrate to measure surfactant DSPC synthesis and more specifically on the difference between de-novo synthesis an remodeling synthesis using free fatty acids derived from the circulating blood. In the second part a newly synthesized stable isotope tracer, 2H3-U13C PA-DPPC, was used to investigate the different kinetics of the sn-1 and sn-2 palmitate moieties in infants with differ

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33

Zetlaoui, Mélanie. "Aspects statistiques de la stabilité en dynamique des populations : application au modèle de Usher en foresterie." Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00133544.

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Le modèle de Usher est un modèle matriciel qui décrit l'évolution en temps discret d'une population<br />structurée par taille et qui restreint les transitions entre les classes d'état. Il est particulièrement<br />adapté pour décrire la dynamique d'un peuplement forestier et sert de guide dans la gestion des<br />forêts. Cette étude porte sur les prédictions dans l'état stationnaire du modèle. L'objectif principal<br />est la construction d'intervalles de confiance de ces prédictions. Dans un premier temps, des<br />intervalles de confiance asymptotiques sont construits en utilisant les estim

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Lamonica, Giulia. "Stable isotope tracers to estimate lung surfactant metabolism in vivo." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423360.

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Aim of this thesis was to apply the stable isotopes technique to study pulmonary surfactant kinetics. Lung surfactant is essential to live, because it prevents the alveoli to collapse during normal breathing. Lung surfactant is composed of lipids and specific proteins, and nowadays it is well known that alterations on the composition and amount of surfactant are involved in acute and chronic lung diseases. This work presents two studies about lung surfactant kinetics. The first one is about the synthesis of disaturated phosphatidylcholine, the main lipid in the pulmonary surfactant system,

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Lichtner, Mark. "Exponential dichotomy and smooth invariant center manifolds for semilinear hyperbolic systems." Doctoral thesis, [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981306659.

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Mildner, Marcus. "Stabilité de l'équation d'advection-diffusion et stabilité de l'équation d'advection pour la solution du problème approché, obtenue par la méthode upwind d'éléments-finis et de volumes-finis avec des éléments de Crouzeix-Raviart." Phd thesis, Université du Littoral Côte d'Opale, 2013. http://tel.archives-ouvertes.fr/tel-00839524.

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On considère le problème d'advection-diffusion stationnaire v(∇u, ∇v)+( β*∇u, v) = (f, v) et non stationnaire d/dt (u(t), v) + v(∇u, ∇v)+( β*∇u, v) = (g(t), v), ainsi que le problème d'advection (β*∇u, v) = (f, v) sur un domaine polygonal borné du plan. Le terme de diffusion est approché par des éléments de Crouzeix Raviart et le terme de convection par une méthode upwind sur des volumes barycentriques finis avec un maillage triangulaire. Pour le problème stationnaire d'advection-diffusion, la L²-stabilité (c'est-à-dire indépendante du coefficient de diffusion v) est démontrée pour la solution

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Gibert, Pierre-Marie. "Utilisation de prédicteurs sinusoïdaux pour la simulation temporelle de systèmes électriques en courant alternatif." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1275/document.

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Simuler temporellement les réseaux électriques modernes requiert d'importants moyens de calcul de par la dimension et la raideur des systèmes différentiels algébriques résultants. De plus, la fréquence d'oscillation de certains signaux simulés contraint fortement le pas d'intégration des schémas classiques, y compris en régime établi où ils sont proches de sinusoïdes oscillant à la fréquence nominale du système. L'objectif de la méthode des prédicteurs sinusoïdaux proposée dans cette thèse est donc de tirer parti de cette propriété afin d'améliorer les performances du solveur tout en contrôlan

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BOUHADJRA, DYHIA. "Modeling and Estimation of Biological Plants." Doctoral thesis, Università degli studi di Genova, 2022. https://hdl.handle.net/11567/1101093.

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Estimating the state of a dynamic system is an essential task for achieving important objectives such as process monitoring, identification, and control. Unlike linear systems, no systematic method exists for the design of observers for nonlinear systems. Although many researchers have devoted their attention to these issues for more than 30 years, there are still many open questions. We envisage that estimation plays a crucial role in biology because of the possibility of creating new avenues for biological studies and for the development of diagnostic, management, and treatment tools. To thi

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Koumaiha, Marwa. "Analyse numérique pour les équations de Hamilton-Jacobi sur réseaux et contrôlabilité / stabilité indirecte d'un système d'équations des ondes 1D." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1122/document.

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Cette thèse est composée de deux parties dans lesquelles nous étudions d'une part des estimations d'erreurs pour des schémas numériques associés à des équations de Hamilton-Jacobi du premier ordre. D'autre part, nous nous intéressons a l'étude de la stabilité et de la contrôlabilité exacte frontière indirecte des équations d'onde couplées.Dans un premier temps, en utilisant la technique de Crandall-Lions, nous établissons une estimation d'erreur d'un schéma numérique monotone aux différences finies pour des conditions de jonction dites a flux limité, pour une équation de Hamilton-Jacobi du pre

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Murgueytio, Zoraida Violeta López. "Estudo sobre a garantia de estabilidade em malha fechada com estimação algébrica de derivadas." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-26012017-110642/.

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A presente tese trata do estudo dos estimadores algébricos aplicados a sistemas de controle. Tais estimadores são filtros variantes no tempo que estimam as derivadas dos sinais de entrada e funcionam como uma alternativa ao uso de observadores. Este trabalho inclui uma contribuição teórica que permite determinar um limite superior do erro do estimador algébrico. Também, mostramos um resultado que garante estabilidade em malha fechada no contexto do princípio da separação para esta classe particular de sistemas. Um exemplo de levitação magnética baseado em linearização exata com estimadores alg

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Feng, Yuehong. "Stabilité de solutions régulières pour des systèmes d'Euler-Maxwell et de Navier-Stokes-Maxwell compressibles." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22484/document.

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Cette thèse est essentiellement composée de deux parties traitant des problèmes de Cauchy ou des problèmes périodiques. Dans la première partie, on étudie la stabilité de solutions régulières au voisinage d'états d'équilibre non constants pour un système d'Euler-Maxwell isentropique compressible bipolaire. Par des estimations d'énergie classiques et un argument de récurrence sur l'ordre des dérivées des solutions, on montre l'existence globale et l'unicité des solutions régulières du système lorsque les données initiales sont proches des états d'équilibre. On obtient aussi le comportement asym

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Abbas, Qaisar. "Weak Boundary and Interface Procedures for Wave and Flow Problems." Doctoral thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159440.

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In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems. The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries

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Viel, Christophe. "Control law and state estimators design for multi-agent system with reduction of communications by event-triggered approach." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS274/document.

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Les systèmes multi-agents (MAS) et la commande coopérative ont fait l'objet de nombreuses recherches ces dernières années. Les domaines d'application sont très diverses et dans le cas des systèmes multi-véhicules, des approches ont été développées pour des unmanned air vehicles (UAVs), satellites, avions... Les types de missions envisagées sont des missions complexes telles l’exploration ou la surveillance de zones, la recherche et le suivi de cibles d'intérêt. Cependant, la coopération requière des échanges de communication entre les agents. Lorsque ceux-ci sont nombreux, cet échange peut con

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Ailliot, Pierre. "Modèles autorégressifs à changements de régimes markoviens. Applications aux séries tempo-relles de vent." Phd thesis, Université Rennes 1, 2004. http://tel.archives-ouvertes.fr/tel-00007602.

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Dans cette thèse, plusieurs modèles originaux, utilisant les modèles autorégressifs à change-ments de régimes markoviens, sont proposés pour les séries temporelles de vent. L'étude théorique de ces modèles fait l'objet du premier chapitre. Nous abordons en particulier les problèmes du calcul numérique des estimateurs du maximum de vraisemblance, de l'étude de leurs comportements asymptotiques ainsi que celui de la validation de modèle. Dans le deuxième chapitre, nous proposons divers modèles autorégressifs à changements de régimes markoviens permettant de décrire l'évolution du vent en un poin

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Wade, Bruce A. "Stability and sharp convergence estimates for symmetrizable difference operators." 1987. http://catalog.hathitrust.org/api/volumes/oclc/17003019.html.

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Zemas, Konstantinos. "Geometric rigidity estimates for isometric and conformal maps from S^(n-1) to R^n." 2020. https://ul.qucosa.de/id/qucosa%3A73090.

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In this thesis we study qualitative as well as quantitative stability aspects of isometric and conformal maps from S^(n-1) to R^n, when n is greater or equal to 2 or 3 respectively. Starting from the classical theorem of Liouville, according to which the isometry group of S^(n-1) is the group of its rigid motions and the conformal group of S^(n-1) is the one of its Möbius transformations, we obtain stability results for these classes of mappings among maps from S^(n-1) to R^n in terms of appropriately defined deficits. Unlike classical geometric rigidity results for maps defined on domains o

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Leger, Nicholas Matthew. "A fragmentation model for sprays and L² stability estimates for shockes solutions of scalar conservation laws using the relative entropy method." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1305.

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We present a mathematical study of two conservative systems in fluid mechanics. First, we study a fragmentation model for sprays. The model takes into account the break-up of spray droplets due to drag forces. In particular, we establish the existence of global weak solutions to a system of incompressible Navier-Stokes equations coupled with a Boltzmann-like kinetic equation. We assume the particles initially have bounded radii and bounded velocities relative to the gas, and we show that those bounds remain as the system evolves. One interesting feature of the model is the apparent accumulatio

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Lapšanská, Alica. "Úlohy vícestupňového stochastického programování - dekompozice." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-336705.

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The thesis deals with a multistage stochastic model and its application to a number of practical problems. Special attention is devoted to the case where a random element follows an autoregressive sequence and the constraint sets correspond to the individual probability constraints. For this case conditions under which is the problem well-defined are specified. Further, the approximation of the problem and its convergence rate under the empirical estimate of the distribution function is analyzed. Finally, an example of the investment in financial instruments is solved, which is defined as a tw

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Uhliar, Miroslav. "Ekonomické růstové modely ve stochastickém prostředí." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-367898.

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Li, Cha-Bin, and 李家賓. "Estimate Frequency Stability of Oscillators by Using GPS." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/b33xzv.

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碩士<br>國立臺灣大學<br>電機工程學研究所<br>92<br>Precise frequency oscillators play very important roles in many applications, for example: high-speed communications, navigations, instrumentation etc. How to obtain more precise clock become the challenges of time and frequency applications technology. The GPS(Global Positioning System) not only can provide low cost and precise navigation information, but also can solve the problem of frequency synchronization. To obtain the frequency offset of an oscillator via GPS is the topic to of this thesis. However, there are errors which pollute the satellite broa

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