Dissertations / Theses on the topic 'Mesure elliptique'
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Silvestre, Tello Catherine. "Première mesure de l'asymétrie azimutale de la production du Jpsi vers l'avant dans les collisions Au+Au à 200 GeV par paire de nucléons avec l'expérience PHENIX." Palaiseau, Ecole polytechnique, 2008. http://www.theses.fr/2008EPXX0061.
Silvestre, Tello Catherine. "Première mesure de l'asymétrie azimutale de la production du Jpsi vers l'avant dans les collisions Au+Au à 200GeV par paire de nucléons avec l'expérience PHENIX." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00004636.
Perstneva, Polina. "Elliptic measure in domains with boundaries of codimension different from 1." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASM037.
This thesis studies different counterparts of the harmonic measure and their relations with the geometry of the boundary of a domain. In the first part of the thesis, we focus on the analogue of harmonic measure for domains with boundaries of smaller dimensions, defined via the theory of degenerate elliptic operators developed recently by David et al. More precisely, we prove that there is no non-degenerate one-parameter family of solutions to the equation LμDμ = 0, which constitutes the first step to recover an analogue of the statement ``if the distance function to the boundary of a domain is harmonic, then the boundary is flat'', missing from the theory of degenerate elliptic operators. We also find out and explain why the most natural strategy to extend our result to the absence of individual solutions to the equation LμDμ = 0 does not work. In the second part of the thesis, we focus on elliptic measures in the classical setting. We construct a new family of operators with scalar continuous coefficients whose elliptic measures are absolutely continuous with respect to the Hausdorff measures on Koch-type symmetric snowflakes. This family enriches the collection of a few known examples of elliptic measures which behave very differently from the harmonic measure and the elliptic measures of operators close in some sense to the Laplacian. Plus, our new examples are non-compact. Our construction also provides a possible method to construct operators with this type of behaviour for other fractals that possess enough symmetries
Lavenant, Hugo. "Courbes et applications optimales à valeurs dans l'espace de Wasserstein." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS112/document.
The Wasserstein space is the space of probability measures over a given domain endowed with the quadratic Wasserstein distance. In this work, we study variational problems where the unknowns are mappings valued in the Wasserstein space. When the source space is a segment, i.e. when the unknowns are curves valued in the Wasserstein space, we are interested in models where, in addition to the action of the curves, there are some terms which penalize congested configurations. We develop techniques to extract regularity from the minimizers thanks to the interplay between optimal density evolution (minimization of the action) and penalization of congestion, and we apply them to the study of Mean Field Games and the variational formulation of the Euler equations. When the source space is no longer a segment but a domain of a Euclidean space, we consider only the Dirichlet problem, i.e. the minimization of the action (which can be called the Dirichlet energy) among mappings sharing a fixed value on the boundary of the source space. The solutions are called harmonic mappings valued in the Wasserstein space. We prove that the different definitions of the Dirichlet energy in the literature turn out to be equivalent; that the Dirichlet problem is well-posed under mild assumptions; that the superposition principle fails if the source space is no longer a segment; that a sort of maximum principle holds; and we provide a numerical method to compute these harmonic mappings
Lefkir, Miloud. "Mesure des susceptibilités non linéaires d'ordre trois par auto-modification de l'état de polarisation d'une onde lumineuse : rôle des gradients transversés du champ." Angers, 1996. http://www.theses.fr/1996ANGE0025.
Méès, Loïc. "Diffusion de la lumière par des objets cylindriques : simulations par théorie de Lorenz-Mie généralisée et applications métrologiques." Rouen, 2000. http://www.theses.fr/2000ROUES019.
Opitz, Thomas. "Extrêmes multivariés et spatiaux : approches spectrales et modèles elliptiques." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20125/document.
This PhD thesis presents contributions to the modelling of multivariate andspatial extreme values. Using an extension of commonly used pseudo-polar representations inextreme value theory, we propose a general unifying approachto modelling of extreme value dependence. The radial variable of such coordinates is obtained from applying a nonnegative and homogeneous function, called aggregation function, allowing us to aggregate a vector into a scalar value. The distribution of the angle component is characterized by a so-called angular or spectral measure. We define radial Pareto distribution and an inverted version of thesedistributions, both motivated within the framework of multivariateregular variation. This flexible class of models allows for modelling of extreme valuesin random vectors whose aggregated variable shows tail decay of thePareto or inverted Pareto type. For the purpose of spatial extreme value analysis, we follow standard methodology in geostatistics of extremes and put the focus on bivariatedistributions. Inferentialapproaches are developed based on the notion of a spectrogram,a tool composed of thespectral measures characterizing bivariate extreme value behavior. Finally, the so-called spectral construction of the max-stable limit processobtained from elliptical processes, known as extremal-t process, ispresented. We discuss inference and explore simulation methods for the max-stableprocess and the corresponding Pareto process. The utility of the proposed models and methods is illustrated throughapplications to environmental and financial data
Usseglio-Carleve, Antoine. "Estimation de mesures de risque pour des distributions elliptiques conditionnées." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1094/document.
This PhD thesis focuses on the estimation of some risk measures for a real random variable Y with a covariate vector X. For that purpose, we will consider that the random vector (X,Y) is elliptically distributed. In a first time, we will deal with the quantiles of Y given X=x. We thus firstly investigate a quantile regression model, widespread in the litterature, for which we get theoretical results that we discuss. Indeed, such a model has some limitations, especially when the quantile level is said extreme. Therefore, we propose another more adapted approach. Asymptotic results are given, illustrated by a simulation study and a real data example.In a second chapter, we focus on another risk measure called expectile. The structure of the chapter is essentially the same as that of the previous one. Indeed, we first use a regression model that is not adapted to extreme expectiles, for which a methodological and statistical approach is proposed. Furthermore, highlighting the link between extreme quantiles and expectiles, we realize that other extreme risk measures are closely related to extreme quantiles. We will focus on two families called Lp-quantiles and Haezendonck-Goovaerts risk measures, for which we propose extreme estimators. A simulation study is also provided. Finally, the last chapter is devoted to the case where the size of the covariate vector X is tall. By noticing that our previous estimators perform poorly in this case, we rely on some high dimensional estimation methods to propose other estimators. A simulation study gives a visual overview of their performances
Ariche, Sadjiya. "Régularité des solutions de problèmes elliptiques ou paraboliques avec des données sous forme de mesure." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0015/document.
In this thesis, we study the regularity of elliptic problems (Laplace, Helmholtz) or parabolic problems (heat equation) with measure data in different geometric frames. Thus, we consider for the second members, Dirac masses at a point, on a line, on a half-line, or on a bounded segment, and also on a regular curve. As the solutions of these problems are singular on the fracture (modeled by Dirac mass in the second member), we study their regularity in weighted Sobolev spaces. In the case of a straight fracture, using Fourier or Mellin technique reduces the problem in dimension three to a Helmholtz problem in dimension two. For the latter, we prove uniform estimates, which are then used to apply the inverse transform and to obtain the expected regularity result. Similarly, the Laplace transformation transforms the heat equation into the same Helmholtz equation in 2D. In the case of a smooth curve fracture, thanks to the results of [D'angelo:2012], using a localization argument and a dyadic recovery we get an improved smoothness of the solution always in weighted Sobolev spaces
Le, Borgne Philippe. "Unicité forte et ensembles nodaux pour des opérateurs elliptiques d'ordre 4." Reims, 2000. http://www.theses.fr/2000REIMS030.
ATIK, YOUCEF. "T-ensembles locaux et problèmes elliptiques quasi-linéaires degeneres à donnée mesure sur un ouvert quelconque." Poitiers, 1993. http://www.theses.fr/1993POIT2339.
Alaa, Nour Eddine. "Étude d'équations elliptiques non linéaires à dépendance convexe en le gradient et à données mesures." Nancy 1, 1989. http://www.theses.fr/1989NAN10460.
Chabrier, Thomas. "Arithmetic recodings for ECC cryptoprocessors with protections against side-channel attacks." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00910879.
Salazar-Serrano, Jorge. "Allure des fonctions harmoniques le long des lignes de Green et généralisations (II)." Paris 11, 1988. http://www.theses.fr/1988PA112233.
Take a harmonic space in the sense of Brelot. We consider a stochastic process verifying some hypotheses. We define a Dirichlet problem and we prove the convergence of solutions in a specific sense. We consider Green’s lines, studied principally by M. Brelot and G. Choquet. We prove that two properties are equivalent: one concerning harmonic functions the other one about the Green kernel. We prove that these properties are verified by. Open sets of RN (N≥2) with boundary included in a hyperplane. We prove a Fatou theorem and the convergence of paths in the R. S. Martin compactification under a hypothesis about potentials. Finally, we extend Green’s lines to elliptic operators in divergence form
Hirata-Kohno, Noriko. "Approximation diophantienne de valeurs et de périodes de fonctions complexes." Paris 6, 1989. http://www.theses.fr/1989PA066244.
Droniou, Jérôme. "Etude théorique et numérique d'équations aux dérivées partielles elliptiques, paraboliques et non-locales." Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2004. http://tel.archives-ouvertes.fr/tel-00008007.
1) la régularité locale de solutions d'EDP elliptiques non-linéaires à données mesures
2) des schémas numériques de type volumes finis pour équations elliptiques à seconds membres peu réguliers
3) l'approximation, par sa régularisation parabolique, d'une loi de conservation scalaire avec conditions au bord
4) des EDP faisant intervenir un opérateur non-local (de type laplacien fractionnaire).
Monteil, Antonin. "Approximations elliptiques d'énergies singulières sous contrainte de divergence." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS135/document.
This thesis is devoted to the study of phase-field type variational models with divergence constraint. These models typically involve an energy depending on a parameter which represents a negligible physical quantity or is linked to some numerical approximation method for instance. A central question concerns the asymptotic behavior of these energies and of their global or local minimizers when this parameter goes to 0. We present different strategies which allow to take the divergence constraint into account. They will be illustrated in two models. The first one is a phase-field type approximation, involving a divergence constraint, of the Eulerian model for branched transportation. We illustrate how uniform estimates on the energy, depending on the constraint on the divergence, allow to establish a Gamma-convergence result. The second model, related to micromagnetics, concerns Aviles-Giga type energies for divergence-free vector fields. We use the entropy method in order to characterize global minimizers. In some situations, we will prove a De Giorgi type conjecture concerning the one-dimensional symmetry of global minimizers under boundary conditions
Hedabou, Mustapha. "Amélioration et sécurisation des calculs arithmétiques pour la cryptographie basée sur les courbes elliptiques." Toulouse, INSA, 2006. http://www.theses.fr/2006ISAT0020.
In this Ph. D, we study some efficiency and security aspects of the implementation of Elliptic Curve Cryptosystems. In the first part, we improve the efficiency of the arithmetic computations on the elliptic curve, by introducing new methods for the scalar multiplication. These methods, which are derived from well-known efficient methods, such as the comb or "tau"-adic methods, allow to reduce the size of the used memory space, the computation time or both, without requiring the insertion of any additional routine. The results found are corroborated by numerical studies. In the second part, we present two types of countermeasures to protect Elliptic Curve Cryptosystems running on limited resources such as smart cards against Side Channel Attacks (SCA). The first type consists in extending or enhancing some known countermeasures. The second one consists in converting the methods proposed in the first part into efficient SCA-resistant methods. Furthermore, we evaluate and compare various combinations of countermeasures in order to be able to come to a conclusion about the best choices for an implementation
Ahmad, Ahmad. "Sécurité orientée utilisateur pour les réseaux personnels sans fil." Thesis, Evry, Institut national des télécommunications, 2010. http://www.theses.fr/2010TELE0009.
Wireless Personal Area Network (WPAN) communications concept is generally restricted to couples of devices (a phone, a headset, a camera) and strongly related to a user and communicating very periodically (exchanges of differentBtypes). Nonetheless, we believe that the concept will evolve in the near future to create a distributed communication network all around users with more devices. Such a distributed network is called a Personal Network (PN). The next step after the distributed network creation is to interconnect them with certain restrictions. Since the WPAN is generally a private area, we do not like to expose all the resources to external users but still we would like to let them have restricted access to certain facilities. Similarly, we would like to peer friends to let us use their own resources with equivalent conditions. As devices involved in the Personal Networks, in some cases, have a LowData Rate nature, implementing legacy security protocols seems to be inefficient.In fact, such devices require a minimal implementation of security solutions withlow cost which can not be provided by known protocols. Moreover, a verticaloverview of the communication stack gives insight on the difficulties of applyingthese protocols. We propose an efficient physical layer encryption to be implementedafter the error coding process. The proposed architecture relies on the use of the well proven secure Output Feedback Mode OFB using AES algorithm as a Cipher. The next contribution is targeting the development of a hierarchical key agreement between multi-parties to secure communication between many clusters related to only one owner. One step after securing the Intra-Personal Network is to secure resource sharing between many PNs. Resources are not necessarily in the same authentication domain and the group that uses them is called a federation. Our contribution is based on two components: A signaling protocol and a group key management system. We close our work by providing a security solution that targets the integration of the PN within the future internet, more precisely, the network of information. In the future internet, everything is mobile and virtually connected to everything where the object takes the cornerstone. In the other hand, Personal net works are evolving to create Smart personal networks around the user. In the object-centric and user-centric concepts, information access becomes easier but establishing good security becomes harder. The difficulty is not finding new secure algorithms but rather that of adapting and enhancing existing solutions to meet the security requirements desirable for the interaction between these networks. In this contribution, we propose a new solution that merges Identity-Based cryptography and the Certificateless Cryptography cryptographic systems into only one in order to keep their advantages and to resolve their problems
Seddiki, Sélim. "Contribution au développement du détecteur de Vertex de l'expérience CBM et étude de faisabilité des mesures du flot elliptique des particules à charme ouvert." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00862654.
Oropeza, Alip. "Sur une classe de problèmes elliptiques quasilinéaires avec conditions de Robin non linéaires et données L1 : existence et homogénéisation." Rouen, 2016. http://www.theses.fr/2016ROUES043.
Ahmad, Ahmad. "Sécurité orientée utilisateur pour les réseaux personnels sans fil." Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2010. http://www.theses.fr/2010TELE0009.
Wireless Personal Area Network (WPAN) communications concept is generally restricted to couples of devices (a phone, a headset, a camera) and strongly related to a user and communicating very periodically (exchanges of differentBtypes). Nonetheless, we believe that the concept will evolve in the near future to create a distributed communication network all around users with more devices. Such a distributed network is called a Personal Network (PN). The next step after the distributed network creation is to interconnect them with certain restrictions. Since the WPAN is generally a private area, we do not like to expose all the resources to external users but still we would like to let them have restricted access to certain facilities. Similarly, we would like to peer friends to let us use their own resources with equivalent conditions. As devices involved in the Personal Networks, in some cases, have a LowData Rate nature, implementing legacy security protocols seems to be inefficient.In fact, such devices require a minimal implementation of security solutions withlow cost which can not be provided by known protocols. Moreover, a verticaloverview of the communication stack gives insight on the difficulties of applyingthese protocols. We propose an efficient physical layer encryption to be implementedafter the error coding process. The proposed architecture relies on the use of the well proven secure Output Feedback Mode OFB using AES algorithm as a Cipher. The next contribution is targeting the development of a hierarchical key agreement between multi-parties to secure communication between many clusters related to only one owner. One step after securing the Intra-Personal Network is to secure resource sharing between many PNs. Resources are not necessarily in the same authentication domain and the group that uses them is called a federation. Our contribution is based on two components: A signaling protocol and a group key management system. We close our work by providing a security solution that targets the integration of the PN within the future internet, more precisely, the network of information. In the future internet, everything is mobile and virtually connected to everything where the object takes the cornerstone. In the other hand, Personal net works are evolving to create Smart personal networks around the user. In the object-centric and user-centric concepts, information access becomes easier but establishing good security becomes harder. The difficulty is not finding new secure algorithms but rather that of adapting and enhancing existing solutions to meet the security requirements desirable for the interaction between these networks. In this contribution, we propose a new solution that merges Identity-Based cryptography and the Certificateless Cryptography cryptographic systems into only one in order to keep their advantages and to resolve their problems
Nguyen, Phuoc Tai. "Trace au bord de solutions d'équations de Hamilton-Jacobi elliptiques et trace initiale de solutions d'équations de la chaleur avec absorption sur-linéaire." Phd thesis, Université François Rabelais - Tours, 2012. http://tel.archives-ouvertes.fr/tel-00710410.
Abdel, Hamid Haydar. "Etude de deux problèmes quasilinéaires elliptiques avec terme de source relatif à la fonction ou à son gradient." Phd thesis, Université François Rabelais - Tours, 2009. http://tel.archives-ouvertes.fr/tel-00441100.
Briançon, Tanguy. "Problemes de régularité en optimisation de formes." Phd thesis, Université Rennes 1, 2002. http://tel.archives-ouvertes.fr/tel-00002013.
Bouchitte, Guy. "Calcul des variations en cadre non reflexif : representation et relaxation de fonctionnelles integrales sur un espace de mesures, applications en plasticite et homogeneisation." Perpignan, 1987. http://www.theses.fr/1987PERP0033.
Lucas, Audrey. "Support logiciel robuste aux attaques passives et actives pour l'arithmétique de la cryptographie asymétrique sur des (très) petits coeurs de calcul." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S070.
This thesis deals with protection development and evaluation against fault attacks (FA) and side channel attacks (SCA) simultaneously. These protections have been developed for elliptic curves cryptography (ECC) and its main operation, the scalar multiplication (MS). Two protections have been proposed. The first is point verification (PV) checking that the current point is effectively on the curve, with a uniformization behavior. Thus, this new SM with PV is robust against some FAs and also SPA, since it is uniform. The second one is called counter iteration (IC). ICC protects the scalar against major FAs with a uniform behavior. Its overhead is very small. Our protections have been implemented on Cortex M0 microcontroller for Weiertrass and Montgomery curves and for different types of coordinates. The overhead is between 48 % and 62 %, in the worst case (when the PV is made at each SM iteration). This overhead is smaller than overhead of usual basic protections against SPA. A theorical activity simulator has also been developed. It reproduces the architecture of a simple 32-bit microcontroller. Theoric activity is modeled by the Hamming weigh variations of manipulated data during execution. Thanks to the simulator, the impact of operands is illustrated for arithmetic units. Moreover, SPA and DPA attacks were made for evaluating our protections. Our protections show some security improvements
Dosso, Fangan Yssouf. "Contribution de l'arithmétique des ordinateurs aux implémentations résistantes aux attaques par canaux auxiliaires." Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0007.
This thesis focuses on two currently unavoidable elements of public key cryptography, namely modular arithmetic over large integers and elliptic curve scalar multiplication (ECSM). For the first one, we are interested in the Adapted Modular Number System (AMNS), which was introduced by Bajard et al. in 2004. In this system of representation, the elements are polynomials. We show that this system allows to perform modular arithmetic efficiently. We also explain how AMNS can be used to randomize modular arithmetic, in order to protect cryptographic protocols implementations against some side channel attacks. For the ECSM, we discuss the use of Euclidean Addition Chains (EAC) in order to take advantage of the efficient point addition formula proposed by Meloni in 2007. The goal is to first generalize to any base point the use of EAC for ECSM; this is achieved through curves with one efficient endomorphism. Secondly, we propose an algorithm for scalar multiplication using EAC, which allows error detection that would be done by an attacker we detail
Nguyen, Quoc-Hung. "THÉORIE NON LINÉAIRE DU POTENTIEL ET ÉQUATIONS QUASILINÉAIRES AVEC DONNÉES MESURES." Phd thesis, Université François Rabelais - Tours, 2014. http://tel.archives-ouvertes.fr/tel-01063365.
Muzellec, Boris. "Leveraging regularization, projections and elliptical distributions in optimal transport." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAG009.
Comparing and matching probability distributions is a crucial in numerous machine learning (ML) algorithms. Optimal transport (OT) defines divergences between distributions that are grounded on geometry: starting from a cost function on the underlying space, OT consists in finding a mapping or coupling between both measures that is optimal with respect to that cost. The fact that OT is deeply grounded in geometry makes it particularly well suited to ML. Further, OT is the object of a rich mathematical theory. Despite those advantages, the applications of OT in data sciences have long been hindered by the mathematical and computational complexities of the underlying optimization problem. To circumvent these issues, one approach consists in focusing on particular cases that admit closed-form solutions or that can be efficiently solved. In particular, OT between elliptical distributions is one of the very few instances for which OT is available in closed form, defining the so-called Bures-Wasserstein (BW) geometry. This thesis builds extensively on the BW geometry, with the aim to use it as basic tool in data science applications. To do so, we consider settings in which it is alternatively employed as a basic tool for representation learning, enhanced using subspace projections, and smoothed further using entropic regularization. In a first contribution, the BW geometry is used to define embeddings as elliptical probability distributions, extending on the classical representation of data as vectors in R^d.In the second contribution, we prove the existence of transportation maps and plans that extrapolate maps restricted to lower-dimensional projections, and show that subspace-optimal plans admit closed forms in the case of Gaussian measures.Our third contribution consists in deriving closed forms for entropic OT between Gaussian measures scaled with a varying total mass, which constitute the first non-trivial closed forms for entropic OT and provide the first continuous test case for the study of entropic OT. Finally, in a last contribution, entropic OT is leveraged to tackle missing data imputation in a non-parametric and distribution-preserving way
Cornelie, Marie-Angela. "Implantations et protections de mécanismes cryptographiques logiciels et matériels." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAM029/document.
The protection of cryptographic mechanisms is an important challenge while developing a system of information because they allow to ensure the security of processed data. Since both hardware and software supports are used, the protection techniques have to be adapted depending on the context.For a software target, legal means can be used to limit the exploitation or the use. Nevertheless, it is in general difficult to assert the rights of the owner and prove that an unlawful act had occurred. Another alternative consists in using technical means, such as code obfuscation, which make the reverse engineering strategies more complex, modifying directly the parts that need to be protected.Concerning hardware implementations, the attacks can be passive (observation of physical properties) or active (which are destructive). It is possible to implement mathematical or hardware countermeasures in order to reduce the information leakage during the execution of the code, and thus protect the module against some side channel attacks.In this thesis, we present our contributions on theses subjects. We study and present the software and hardware implementations realised for supporting elliptic curves given in Jacobi Quartic form. Then, we discuss issues linked to the generation of curves which can be used in cryptography, and we propose an adaptation to the Jacobi Quartic form and its implementation. In a second part, we address the notion of code obfuscation. We detail the techniques that we have implemented in order to complete an existing tool, and the complexity module which has been developed
Droniou, Jérôme. "Etude de Certaines Equations aux Dérivées Partielles." Phd thesis, Université de Provence - Aix-Marseille I, 2001. http://tel.archives-ouvertes.fr/tel-00001180.
Venelli, Alexandre. "Contribution à la sécurite physique des cryptosystèmes embarqués." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22005/document.
This thesis focuses on the study of side-channel attacks as well as their consequences on the secure implementation of cryptographic algorithms. We first analyze different side-channel attacks and we propose an improvement of a particularly interesting generic attack: the mutual information analysis. We study the effect of state of the art entropy estimation techniques on the results of the attack. We propose the use of B-spline funtions as estimators as they are well suited to the side-channel attack scenario. We also investigate the consequences of this kind of attack on a well known symmetric cryptosystem, the Advanced Encryption Standard (AES), and we propose a countermeasure based on the algebraic structure of AES. The main operation of ECC is the scalar multiplication that consists of adding an elliptic curve point to itself a certain number of times. In the second part, we investigate how to secure this operation. We propose a scalar multiplication algorithm that is both efficient and secure against main side-channel attacks. We then study pairings, a mathematical construction based on elliptic curves. Pairings have many interesting properties that allow the creation of new cryptographic protocols. We finally evaluate the side-channel resistance of pairings
Martin, Hugo. "Étude de données et analyse de modèles intégro-différentiels en biologie cellulaire." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS668.
In this dissertation, we are interested in the study of some dynamics in molecular biology, making us of mathematical analysis of established models, modelling and data analysis. The first two chapters focus on growth-fragmentation equations with linear growth rate. We are first interested in the recent so-called incremental model, describing a bacterial population. We prove the existence and uniqueness of the solution of the eigenproblem in a weighted Lebesgue space. Then we study the asymptotic behaviour of measures solutions of the growth-fragmentation equation in the equal mitosis case. A solution is then expressed as a semigroup acting on an initial condition. We extend to this framework a known phenomenon of long time oscillating dynamics, which results here in a weak convergence of the solution towards a periodic family of measures. The third chapter deals with the joint dynamics between mesenchymal, pre-adipocyte and adipocyte cells. We propose a non-linear model in which the growth rate depends on the average size of the latter and analyze it using both analytical and numerical approaches. In the last chapter, we carry out a statistical analysis of experimental data from individual yeast lines. In particular, we highlight the existence of distinct phenomena between early arrests and replicative senescence. Finally, we propose a refinement of an existing model, now able to describe the generation of onset of senescence for all the lineages
El, Moustaine Ethmane. "Authentication issues in low-cost RFID." Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2013. http://www.theses.fr/2013TELE0030.
This thesis focuses on issues related to authentication in low-cost radio frequency identification technology, more commonly referred to as RFID. This technology it is often referred to as the next technological revolution after the Internet. However, due to the very limited resources in terms of computation, memory and energy on RFID tags, conventional security algorithms cannot be implemented on low-cost RFID tags making security and privacy an important research subject today. First of all, we investigate the scalability in low-cost RFID systems by developing a ns-3 module to simulate the universal low-cost RFID standard EPC Class-1 Generation-2 in order to establish a strict framework for secure identification in low-cost RFID systems. We show that, the symmetrical key cryptography is excluded from being used in any scalable low-cost RFID standard. Then, we propose a scalable authentification protocol based on our adaptation of the famous public key cryptosystem NTRU. This protocol is specially designed for low-cost RFID systems, it can be efficiently implemented into low-cost tags. Finally, we consider the zero-knowledge identification i.e. when the no secret sharing between the tag and the reader is needed. Such identification approaches are very helpful in many RFID applications when the tag changes constantly the field of administration. We propose two lightweight zero-knowledge identification approaches based on GPS and randomized GPS schemes. The proposed approaches consist in storing in the back-end precomputed values in the form of coupons. So, the GPS-based variant can be private and the number of coupons can be much higher than in other approaches thus leading to higher resistance to denial of service attacks for cheaper tags
Chen, Huyuan. "Fully linear elliptic equations and semilinear fractionnal elliptic equations." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4001/document.
This thesis is divided into six parts. The first part is devoted to prove Hadamard properties and Liouville type theorems for viscosity solutions of fully nonlinear elliptic partial differential equations with gradient term
Robert, Jean-Marc. "Contrer l'attaque Simple Power Analysis efficacement dans les applications de la cryptographie asymétrique, algorithmes et implantations." Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0039/document.
The development of online communications and the Internet have made encrypted data exchange fast growing. This has been possible with the development of asymmetric cryptographic protocols, which make use of arithmetic computations such as modular exponentiation of large integer or elliptic curve scalar multiplication. These computations are performed by various platforms, including smart-cards as well as large and powerful servers. The platforms are subject to attacks taking advantage of information leaked through side channels, such as instantaneous power consumption or electromagnetic radiations.In this thesis, we improve the performance of cryptographic computations resistant to Simple Power Analysis. On modular exponentiation, we propose to use multiple multiplications sharing a common operand to achieve this goal. On elliptic curve scalar multiplication, we suggest three different improvements : over binary fields, we make use of improved combined operation AB,AC and AB+CD applied to Double-and-add, Halve-and-add and Double/halve-and-add approaches, and to the Montgomery ladder ; over binary field, we propose a parallel Montgomery ladder ; we make an implementation of a parallel approach based on the Right-to-left Double-and-add algorithm over binary and prime fields, and extend this implementation to the Halve-and-add and Double/halve-and-add over binary fields
El, Moustaine Ethmane. "Authentication issues in low-cost RFID." Phd thesis, Institut National des Télécommunications, 2013. http://tel.archives-ouvertes.fr/tel-00997688.
Ge, Yuxin. "Sur quelques équations aux dérivées partielles nonlinéaires provenant de la géométrie." Cachan, Ecole normale supérieure, 1997. http://www.theses.fr/1997DENS0029.
Hatchi, Roméo. "Analyse mathématique de modèles de trafic routier congestionné." Thesis, Paris 9, 2015. http://www.theses.fr/2015PA090048/document.
This thesis is devoted to the mathematical analysis of some models of congested road traffic. The essential notion is the Wardrop equilibrium. It continues Carlier and Santambrogio's works with coauthors. With Baillon they studied the case of two-dimensional cartesian networks that become very dense in the framework of $\Gamma$-convergence theory. Finding Wardrop equilibria is equivalent to solve convex minimisation problems.In Chapter 2 we look at what happens in the case of general networks, increasingly dense. New difficulties appear with respect to the original case of cartesian networks. To deal with these difficulties we introduce the concept of generalized curves. Structural assumptions on these sequences of discrete networks are necessary to obtain convergence. Sorts of Finsler distance are used and keep track of anisotropy of the network. We then have similar results to those in the cartesian case.In Chapter 3 we study the continuous model and in particular the limit problems. Then we find optimality conditions through a duale formulation that can be interpreted in terms of continuous Wardrop equilibria. However we work with generalized curves and we cannot directly apply Prokhorov's theorem, as in \cite{baillon2012discrete, carlier2008optimal}. To use it we consider a relaxed version of the limit problem with Young's measures. In Chapter 4 we focus on the long-term case, that is, we fix only the distributions of supply and demand. As shown in \cite{brasco2013congested} the problem of Wardrop equilibria can be reformulated in a problem à la Beckmann and reduced to solve an elliptic anisotropic and degenerated PDE. We use the augmented Lagrangian scheme presented in \cite{benamou2013augmented} to show a few numerical simulation examples. Finally Chapter 5 is devoted to studying Monge problems with as cost a Finsler distance. It leads to minimal flow problems. Discretization of these problems is equivalent to a saddle-point problem. We then solve it numerically again by an augmented Lagrangian algorithm
Giard, Antoine. "La mesure de Mahler d’une forme de Weierstrass." Thèse, 2019. http://hdl.handle.net/1866/22549.
Silvestre, Tello Catherine. "Première mesure de l'asymétrie azimutale de la production du J/psi vers l'avant dans les collisions Au+Au à 200 GeV par paire de nucléons avec l'expérience PHENIX." Phd thesis, 2008. http://tel.archives-ouvertes.fr/tel-00359208/en/.
L'étude de la production du $\jpsi$, particule lourde formée d'une paire de quarks charme ($c \bar c$), est une des sondes initialement proposée pour étudier le QGP. Une suppression de la production du $\jpsi$ était en effet attendue en présence d'un QGP, en raison de l'écrantage du potentiel de liaison entre les quarks charme le constituant par la présence du milieu dense coloré environnant. De nombreuses mesures du $\jpsi$ ont eu lieu depuis au SPS (CERN) et à RHIC (BNL). Elles ont permis de mettre en évidence non seulement l'existence d'une telle suppression, mais également la présence de mécanismes supplémentaires, rendant plus difficile l'interprétation des résultats correspondants.
L'expérience PHENIX est la seule des quatre expériences de RHIC capable de mesurer le $\jpsi$ à rapidité positive via sa désintégration en deux muons. En 2007 des collisions Au+Au à une énergie par paire de nucléons dans le centre de masse $\sqrt{s_{NN}}=200$~GeV ont été réalisées à BNL, ce qui a permis d'augmenter d'un facteur quatre la statistique disponible pour l'étude du $\jpsi$ par rapport aux résultats publiés précédemment. Cette augmentation, ajoutée à la mise en oeuvre de nouveaux détecteurs dans PHENIX, a permis de préciser les mesures précédentes, et de mesurer des observables jusqu'alors inaccessibles telles que l'asymétrie azimutale de la production du $\jpsi$.
Ce manuscrit présente la compréhension actuelle de la production de quarkonia et l'utilisation de cette sonde dans l'étude du QGP. L'analyse conduisant à la première mesure de l'anisotropie azimutale du $\jpsi$ à rapidité positive dans les collisions Au+Au à 200~GeV par paire de nucléons est détaillée. Cette mesure devrait permettre de préciser le mécanisme de production du méson, en particulier en ce qui concerne la part de recombinaison des quarks $c$ en $\jpsi$.
Roy, Subham. "Generalized Mahler measure of a family of polynomials." Thèse, 2019. http://hdl.handle.net/1866/23797.
In this thesis we consider a variation of the Mahler measure where the defining integral is performed over a more general torus. Our work is based on a tempered family of polynomials originally studied by Boyd, Boyd P_k (x, y) = x + 1/x + y + 1/y + k with k ∈ R_{>4}. For the k = 4 case we use special values of the Bloch-Wigner dilogarithm to obtain the Mahler measure of P_4 over an arbitrary torus (T_ {a, b})^2 = {(x, y) ∈ C* X C* : | x | = a, | y | = b } with a, b ∈ R_{> 0}. Next we establish a relation between the Mahler measure of P_8 over a torus(T_ {a, √a} )^2 and its standard Mahler measure. The combination of this relation with results due to Lalin, Rogers, and Zudilin leads to a formula involving the generalized Mahler measure of this polynomial given in terms of L'(E, 0). In the end, we propose a strategy to prove some similar results for the general case k > 4 over (T_ {a, b})^2 with some restrictions on a, b.