Дисертації з теми "Contraste dynamique"
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Pauzin, Marie-Christine. "Modélisation du comportement dynamique d'un agent de contraste ultrasonore." Phd thesis, Université de Provence - Aix-Marseille I, 2009. http://tel.archives-ouvertes.fr/tel-00430076.
Повний текст джерелаVan, der Grinten Maurits. "Diffusion des neutrons aux petits angles. Variation de contraste par polarisation dynamique." Paris 11, 1993. http://www.theses.fr/1993PA112213.
Повний текст джерелаAbe, Lyu. "Imagerie à haute dynamique : coronographie à contraste de phase et détecteurs spécifiques." Nice, 2002. http://www.theses.fr/2002NICE5733.
Повний текст джерелаThe existence of extra-solar planets was confirmed in the years 1990, and it is now challenging for astronomers to be able to directly observe them and determine their physical nature. The required performance in terms of high dynamic range imaging is about several tens of million, which has never been reached yet. In order to attain this goal, I have carried out a global reflection on this high dynamic range imaging theme through coronagraphy and specific detectors. The first part of this document is dedicated to the design of photon counting cameras using 800 by 600 pixels CCD with a frame rate of 100 images per second. These developments come within the scope of ground-based observations, especially for stellar coronagraphy and optical long baseline interferometry where the atmospheric turbulence coherence time is only about a few milliseconds in the visible spectrum. The operation of these cameras on the GI2T/REGAIN interferometer could validate my work through scientific programs for which I present the goals and obtained results. The second part more specifically focuses on coronagraphy with the study and the development of the phase knife coronagraph which ultimate goal is to "null" or reject the light from a distant star, so as to detect a faint orbiting companion. This instrument is theoretically compatible with the direct observation of extra-solar planets in terms of intensity ratio (several tens of million). In order to validate the physical principle of this concept, I have built a monochromatic laboratory prototype of this coronagraph, for which I give the obtained performance and extrapolate on the achromatisation possibilities aiming future ground-based observations
Rochefort, Ludovic de. "Imagerie dynamique et vélocimétrie IRM des gaz hyperpolarisés." Paris 11, 2006. https://tel.archives-ouvertes.fr/tel-00083287.
Повний текст джерелаThis work is part of a French project called R-MOD that aims at the development of a morpho-functional simulator of the upper and central airways. Here, hyperpolarized gas (HPG) MRI methods to visualize and quantify gas flows were developed to test the predictions of the simulator. To reach this goal, a dedicated MR-compatible device was built to administrate HPG in a controlled way and different imaging strategies were evaluated. A first qualitative approach was based on dynamic imaging of a HPG inspiration. An analysis of this type of experiment was achieved. The temporal evolution of the phenomenon is too high to be correctly imaged with the state-of-the-art techniques. Nevertheless, spatial distribution of the magnetization within the lung reaches an equilibrium state during a stationary inspiration. This equilibrium state depends on parameters that were explored both theoretically and experimentally through several dynamic imaging techniques. A second approach, more quantitative, is based on phase-contrast velocimetry combined with rapid radial imaging. The technique was first validated on known flow patterns (straight, curved and bifurcating pipes) and then applied on a realistic bronchial tree reconstructed from medical images and compared to computational fluid dynamics simulations. The 3 velocity components were measured within about 1 s, with 1-mm spatial resolution, and a precision of 1cm·s-1. Finally, in vivo feasibility was shown on a human trachea during an inhalation. This flow characterization technique based on HPG MRI is a promising tool for fluid dynamics studies and for related medical applications
Lasoroski, Aurélie. "Etude de complexes de gadolinium d’intérêt pour l’IRM : simulations ab-initio et propriétés magnétiques." Paris 6, 2013. http://www.theses.fr/2013PA066216.
Повний текст джерелаCurrently MRI exams use contrast agents to enhance contrast imaging and so diagnostics. A contrast agent is most of the time a gadolinium complex in which a chelate ligand is used to avoid Gd release, thus preventing toxic ion to spread in patient’s body. In this thesis we studied magnetic properties of gadolinium complexes that affect the relaxation of a water molecule coordinated to Gd, which is the source of contrast imaging. We focused on the commercial contrast agent ProHance, and some derivatives. The first step was to compute ab initio molecular dynamics of the different systems and analyse them. Then we calculated using quantum chemistry hyperfine interaction and Zero-Field Splitting. The analysis of hyperfine tensors was achieved for each system, and average terms were estimated. The origin of tensors’ fast fluctuations in ProHance system was identified thanks to geometrical collectives variables decomposition. ZFS was decomposed into two contributions: static and transient. We can now set up from ab initio all the necessary ingredients for modeling the electronic relaxation time and then the water coordinated molecule proton relaxation for each of the studied systems
Yerly, Fabrice. "Simulation de la structure et de la dynamique d'agents de contraste pour l'imagerie médicale par résonance magnétique /." [S.l.] : [s.n.], 2003. http://library.epfl.ch/theses/?nr=2834.
Повний текст джерелаDe, Rochefort Ludovic. "Imagerie dynamique et vélocimétrie IRM des gaz hyperpolarisés." Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00083287.
Повний текст джерелаPour atteindre cet objectif, un système adapté à l'environnement spécifique de l'IRM a été développé pour permettre l'administration de GHP de manière contrôlée, et différentes approches d'imagerie du flux de GHP ont été explorées.
La 1ère approche est basée sur de l'imagerie dynamique de l'inspiration de GHP. Ce type d'expérience est analysé. L'évolution du phénomène est trop rapide pour être observée correctement avec les techniques actuelles. Néanmoins, un état d'équilibre dynamique de la répartition spatiale de l'aimantation dans les poumons lors d'inspirations en régime stationnaire est observable. Les paramètres dont dépend cet équilibre et une partie de ce qui peut être quantifié par le biais de ce type d'expérience ont été formalisés et les concepts introduits ont été validés par différentes expériences d'imagerie dynamique.
La 2ième approche, quantitative, est basée sur la vélocimétrie par contraste de phase combinée à l'imagerie radiale rapide. D'abord validée quantitativement sur des fantômes d'écoulement connus (tube droit, coude, bifurcation), la technique a ensuite été appliquée sur un modèle réaliste d'arbre bronchique et comparée à une simulation numérique des écoulements. Les 3 composantes de la vitesse ont été mesurées en environ 1 s avec une résolution spatiale du mm et une précision du cm•s-1. Enfin, la faisabilité in vivo de la mesure de vitesse dans les voies aériennes pulmonaires a été démontrée dans la trachée lors d'une inspiration.
Cet outil de caractérisation des écoulements à l'aide de l'IRM des GHP ouvre des voies prometteuses aussi bien pour la physique des écoulements que pour les applications médicales.
Cwiek, Bellomo Ewa. "La dynamique des contrastes dans la construction romanesque chez Fred Vargas." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM3074.
Повний текст джерелаBuilt on a network of contrasts, the romantic world of Fred Vargas bears the mask of detective fiction.The murders of the present hide the bruises of love in the past.Mediator between these diegetic poles,the passion of Vargas’s character breaches the rules of the game that is imposed on him by the world.For behind these civilized appearances ,the original order continues:predation. Confronted by his failure,the character must take up a challenge that will transform his investigation in a quest for identity. Selecting either transgression or self-sacrifice will determine whether he collapses or reappears with his dignity.Converging the plot and the Story, the diegetic here and now bestows upon the character the role of linking the Here and Elsewhere, and adverse identities. The enquiry approaches, the psyche of the murderer and the investigator, reconstituting the interaction between the individual and the world, defined as its synchronic and diachronic chronotope. The relationship between humans and their Others reveals the person behind the character.The confrontation between the human animal and real and mythologized animals challenges the borders between identity and otherness.The real murderer turns out to embody one of the masks of the imagination, while the imagination, established as an ideal of humanity, becomes a reality to conquer at the price of self-sacrifice, and reveals how flexible the realities of failure and fulfillment can be. Analysing the mirror effect between opposition and complementarity accentuates the union of opposites that create the coexistence of horror and the sublime, and love and death in the dichotomy that make up mankind and the world
Viverge, Kevin. "Modèle de plaques stratifiées à fort contraste : application au verre feuilleté." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSET005/document.
Повний текст джерелаWidely used in recent years, the glass material makes it possible to erect light, aesthetic and resistant structures, in particular with glass lamination method, which consists in assembling two or more sheets of glass by one or more intermediate viscoelastic polymers layer. These viscoelastic interface layers are the source of interactions between the shear, the local bending and the global bending mechanisms that govern the overall behavior of laminated glass. For an optimal dimensioning and an accurate determination of the different fields, we propose a "highlycontrasted" plates model encapsulating these different mechanisms and their coupling. As long as a scale separation between the plate thickness and the caracteristic size of kinematics field variations exists, the asymptotic expansion method can be applied for the study of laminates. The effective plate behaviour is derived from the 3D constitutive law of the materials combined with an asymptotic expansion formulation and an appropriate scaling the tiffness contrast between stiff glass layers and soft viscoelastic polymer layers. The method provides a synthetic and consistent formulation, integrating the dual efforts of the macroscopic descriptors, in-plane and out-of-plane balance equations and the constitutive laws of the laminate. First the model is developped for a 2 stiff layers laminated glass plates, then different static and dynamic loading cases are applied. It is then extended to plates with 3 stiff layers and then generalized to plates with N stiff layers. Experimental campaigns are set up in order to validate the models. Finally, a case study of laminated glass floor design is proposed
Kenouche, Samir. "Études expérimentales et modélisation de la dynamique de distribution des agents de contraste en imagerie RMN : applications à l'agronomie." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01019641.
Повний текст джерелаRaoult, Hélène. "Angio-RM morphologique et dynamique sans injection de contraste dans l'exploration des pathologies neurovasculaires à l'étage cervical et encéphalique." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1B011.
Повний текст джерелаMR angiography (MRA) is well adapted for noninvasive exploration of neurovascular pathologies. The development of innovative unenhanced MRA sequences, combining recent acquisition techniques like arterial spin labeling with high magnetic field and multichannel coils, allows to achieve high spatial and temporal resolution in short acquisition times. These innovative sequences may be proposed as alternatives to common MRA sequences and digital subtraction angiography (DSA) of reference. We focused on optimizing acquisition and post-processing of these sequences in two specific pathological contexts, because of their relevancy in terms of clinical and radiological challenges: cervical carotid stenosis and brain arteriovenous malformations (AVM). Cervical « unenhanced carotid MRA » imaging was improved with a preferential acquisition of the k-space center, an isotropic and submillimetric spatial resolution, an acquisition time below 3 min and a large coverage, not requiring any cardiac synchronization. This sequence showed an improved image quality with regards to TOF providing improved signal homogeneity and less flow artifacts, with higher signal intensity and arterial/tissue contrast. This sequence allowed an accurate detection and quantification of carotid stenosis in comparison with computed tomography angiography as well as the detection of infrapetrous lesions. Perspectives are improving signal and volume coverage in order to propose a fast and simultaneous screening of cervical and intracranial stenosis.Brain « 4D-SL MRA » imaging was improved with IR-STAR labeling and a parabolic flip angle pattern, a temporal resolution below 70 ms and an acquisition window allowing analysis of venous drainage, within 7 minutes. This sequence allowed a reliable analysis of AVM angioarchitecture in comparison with DSA and offered an accurate delineation of the nidus, thus suggesting its value for hemorrhagic risk assessment and therapeutic management. A dedicated post-processing using Matlab and SPM8 was developed to improve vascular network visualization and offer an access to hemodynamic quantification within the AVM. A low arterial to venous “time-to-peak” ratio seemed to be correlated with the rupture risk. 4D-SL MRA may pave the way for a novel AVM classification, integrating hemodynamic parameters within the AVM as well as perfusion and microstructural parameters in the surrounding tissue, in order to propose an individualized patient management
Jahanbin, Tania. "Conception et développement in vitro d'agents de contraste hautement efficace en IRM : apport de la dynamique moléculaire sur le signal RMN." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2566/.
Повний текст джерелаThe objective of this thesis is design and development of two types of MRI contrast agents (CA) with high efficiency, including macromolecule and nanoparticles. The first substance is Gd(III)-meso-tetra(4-pyridyl)porphyrin (Gd(TPyP)). Its efficiency has been compared with two metalloporphyrin compounds, Mn(III)-meso-tetra(4-sulfonatophenyl) porphyrin (Mn(TSPP)) and Fe(II)-meso-tetra(N-methylpyridiniumyl)porphyrin (Fe(TMPyP)) in presence of two magnetic field of 20 and 60 MHz. Among the metallated porphyrins, Gd(TPyP) exhibits the highest r1 of 24 mM-1s-1 (6-fold higher compared to r1 of Gd-DOTA). In the next step, Gd(TPyP) has been conjugated to chitosan nanoparticles in order to improve its biocompatibility and water solubility. The small water-soluble Gd(TPyP)-conjugated chitosan nanoparticles (~40 nm) show higher (56%) r1 of 38 mM-1. S-1 at 3T than the one of Gd(TPyP) in ethanol and 9-fold greater than r1 of Gd-DOTA. The second complex developed as CA is MnxZn1-xS ( 0. 1 =x=0. 3) nanoparticles while the majority of Mn atoms localized on/ or close to the surface of ZnS nanoparticles to enhance their efficiency as MRI CA. Mn:ZnS nanoparticles exhibits higher r1 compared with the one of commercial Mn-DPDP (r1=2. 8 mM-1s-1 at 42 MHz), which significantly increases from 20. 34 to 75. 5 mM-1s-1 with Mn content in the range of 0. 1-0. 3. Thereafter, effect of particle size on relaxivity of Mn0. 3Zn0. 7S has been investigated. We observed that r1 decreases with increasing particle size due to decreasing the surface to volume ratio from 75. 5 to 42. 81 mM-1s-1. In order to obtain the insight through the relaxivity of Mn:ZnS nanoparticles, computational technique has been carried out to predict the interaction and dynamic of Mn:ZnS and solvent (water) via molecular dynamic simulations (MDs). Thereby, MnxZn1-xS with different dopnat contents ( 0. 1 =x=0. 3) has been modeled via MDs. We achieved to reproduce the crystal structure of MnZnS precisely, within a few percent of experimental values. The study has been completed successfully by adding MnZnS nanoparticles in aqueous solution
Galicher, Raphaël. "Étude de techniques d'imagerie à haut contraste basées sur la cohérence." Phd thesis, Université Paris-Diderot - Paris VII, 2009. http://tel.archives-ouvertes.fr/tel-00436293.
Повний текст джерелаFardin, Luca. "Microscopie 3D dynamique in-vivo en contraste de phase : un nouvel outil pour étudier les lésions pulmonaires induites par la ventilation mécanique." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAS037.
Повний текст джерелаMechanical ventilation exposes the lung to mechanical stresses that can exacerbate or induce injury in patients with respiratory failure, a condition known as Ventilator-Induced Lung Injury (VILI). The exact mechanisms through which VILI is initiated and entertained at the acinar level remain elusive: the main hypotheses include excessive stretch of the tissues (volutrauma) and cyclic re-opening of closed regions (atelectrauma). The link between the mechanical stress induced on the alveolar tissue and the inflammatory response at an early stage of the injury is still not understood. Currently, the lack of techniques providing information in-vivo and at the alveolar scale on how the mechanical ventilation deforms the lung parenchyma, represents an obstacle for research in the field. Recent advances in phase-contrast 3D microscopy, obtained in synchrotron radiation facilities, have shown the possibility to image the lungs in-vivo, resolving terminal airways and alveoli. However, none of the available techniques allow to fully reconstruct the complex deformations of the lung parenchyma induced simultaneously by cardiac contractions and mechanical ventilation. To overcome this limitation, a computed tomography imaging acquisition protocol, based on the synchronization between the mechanical ventilation and the cardiac activity, was developed. This technique allowed to resolve and reconstruct the lung parenchymal motion with an effective voxel size of 20 µm, sufficient to visualize terminal airways but not the alveolar structure. The technique was applied to a rabbit model of VILI, in which atelectrauma was quantified within a tidal breath. The data revealed a significant heterogeneity in the opening and closing pressures of the airspaces both within and in between animals. Subsequent histological analysis showed a spatial correlation between atelectrauma and alveolar damage, assessed through qualitative evaluation performed by a pathologist blinded to the presence of atelectrauma (p=0.007). Also, spatial correlation between atelectrauma and cellular infiltration evidenced (p=0.04). This imaging technique was further refined to obtain an effective voxel size of 6 µm, which allowed to visualize the alveolar structure. While this spatial resolution is still limited for studying the thin alveolar walls (̴ 10 µm), to the best of our knowledge it is the highest spatial resolution obtained so far in in-vivo dynamic 3D microscopy. This technique will allow to study the lung parenchyma deformation and represents an important step towards the in-vivo study of VILI at the alveolar scale
Balvay, Daniel. "Qualité de la modélisation en imagerie dynamique de la microcirculation avec injection d'un agent de contraste : nouveaux critères et applications en multimodalité." Paris 11, 2005. http://www.theses.fr/2005PA112147.
Повний текст джерелаThe microcirculation dynamic imaging could be a relevant imaging when used in addition with more conventional medical imaging. The dynamic data are modeled, pixel by pixel, to provide microcirculation parameters maps. However there is no efficient tool to assess the modeling quality. The relevance of the parametric maps provided by the dynamic imaging is then limited. Here, we show that a qualitative and quantitative study of the modeling quality needs first to distinguish two questions : the quality of the data fits and the robusness for the random noise. To separate the questions, we designed a new autocorrelation based method which is able to estimate the amplitude of both the correlated and not correlated component of a signal. This method allowed us to correct the correlation coefficient R² and the covariance matrix estimation. It allowed us to define new reliability criteria and a corrected covariance matrix to replace the more conventional indicators. It was shown, on simulated data and in MR data, that new reliabily criteria are obviously better than the R² to assess fit quality. The corrected covariance matrix which assess the robustness and the redoundancy can be calculated in addition to the reliability criteria unlike conventional one which is limited to good data fits. Thus the modeling quality is obviously improved by the new indicators. It should improve the clinical use of microcirculation dynamic imaging where guaranties are needed against artefact. The interest of the new criteria is showed on many different dynamic data. More generaly the new indicators appear as new efficient tools for signal analysis
Labrousse, Marc. "Le contenu de l'angle ponto-cérébelleux : artères et mouvements : morphogenèse, anatomie statique et dynamique." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10078/document.
Повний текст джерелаSeveral vascular and nervous structures are located within the cerebello-pontine angle. In certain pathological conditions, microvascular compression syndroms may occur, where an artery or a vein is compressing a cranial nerve. The purpose of this work in three parts is to investigate some anatomical and physiological bases of these microvascular compression syndroms. The first part focuses on the vertebrobasilar system morphogenesis. A special designed 3D reconstruction original software allowed us to reformate four human embryos from histological serial sections. The three-dimensional views are confirming the classical features thus creating the basis of a larger study based on multiple embryos. The second part shows for the first time the physiological motion of the vestibulo-cochlear nerve at the level of the cerebello-pontine angle, with the help of a phase-contrast MRI sequence. The cranio-caudal and antero-posterior directions and their amplitudes have been studied. These motions are cardiac-cycle-dependant. We used an "oscillating string" model to explain the VCN motion between the brain stem and the fundus of the internal acoustic meatus. The third part of this work is focused on a preliminary study of the variability of the vertebro-basilar arterial fusion along the lifetime. An original software has been designed and allowing the normalisation from nine post-contrast cerebral CT scanners. A ?mean? brain stem was obtained and visualized in front of nine arterial fusion points
Vautier, Julien. "Développement d'une nouvelle méthode quantitative d'IRM dynamique avec agents de contraste basée sur une acquisition radiale : application à la caractérisation de la vascularisation tumorale." Paris 11, 2010. http://www.theses.fr/2010PA112203.
Повний текст джерелаSince the discovery of angiogenesis importance in tumour growth in the 70s, antiangiogenic and antivascular treatments have been developed in order to stop or destroy tumour vascularisation. A difficulty is that vascular disruption has an effect on the tumour size - and so accessible to conventional imaging - several months later. Moreover, it has been showed that antiangiogenic molecules can have an effect on tumour capillary permeability 24 hours after their administration. Then, it is justified to search methods to assess a biomarker linked to permeability as Ktrans. The theme of this thesis work was the development of a measurement of Ktrans in 3D for mice models in presence of respiratory motion. To overpass a respiratory synchronisation which would be prohibitive in 3D, radial MRI acquisition was used, which has the property to be less sensitive to motion as Cartesian acquisitions. For a relevant measurement of Ktrans, it is important to measure an individual arterial input function (AIF). The original method developed here permits to interlace a measurement of individual AIF with 3D images on tumour. Temporal resolution of AIF is 2 seconds while a 3D image is acquired every 2 minutes. Preliminary study permits to validate this technique on mouse. The method allows hoping an amelioration of preclinical studies, especially in genetically modified mice models
Ygouf, Marie. "Nouvelle méthode de traitement d'images multispectrales fondée sur un modèle d'instrument pour la haut contraste : application à la détection d'exoplanètes." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00843202.
Повний текст джерелаDupont, Jan. "Imagerie polarimétrique de speckle statique pour l’étude de matériaux et dynamique pour la détection de micro-vascularisation tumorale." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0002/document.
Повний текст джерелаWhen an electromagnetic wave is scattered by a rough surface or in a volume, a speckle field is observed, with characterlstlcs depending on the consldered scatterer. Multiple scattering in samples immpact the State of polarizatlon of an incident light. Thus, polarization Is a sensitive parameter for material characterization and study. A spatially resolved polarlmetry method, allowing accurate measurements in speckle fields is proposed. That method is used to study the Impact of various parameters on polarimétrie measurements, especially the depolarization phenomenon due to the observation setup. A polarlzed speskle simulation model is proposed, validated by comparison with expérimentation for various scattering régime. Besides, dynamlc properties of samples can be measured by an analysis of the scattered speckle contrast. A method allowing microvascularization imaging based on dynamic polarized light scattering imaging is optlmlzed, then applied to in-vivo study of the tumor angiogenesis occuring on murine melanoma, as well as the vascularization évolution after a treatment called electrochemotherapy. Potentlal of the method for non invasive détection and study of the murine melanoma is demonstrated, its efflciency on human melanoma for biomédical applications remaning to be characterized
Tardin, Catherine. "Détection de nano-objets individuels dans des cellules : étude de la structure dynamique de la synapse de neurones vivants et développement de l'imagerie par contraste interférentiel photothermique." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12848.
Повний текст джерелаLaredo, Catherine. "Dynamique de populations dans l'asymptotique des grandes déviations : statistiques de diffusions partiellement observées." Paris 11, 1987. http://www.theses.fr/1987PA112060.
Повний текст джерелаThe first part of this thesis is devoted to the study of spatial branching processes using large deviations techniques. We first obtain a spatial generalization of the Malthusian parameter. Then, we prove the almost everywhere continuity of a monotone operator describing the asymptotic behavior of a nonhomogeneous spatial branching process. Finally, for populations with controlled offspring, we compare a deterministic modelisation (reaction-diffusion) and a stochastic modelisation (controlled branching processes) using numerical methods. The second part is concerned with the non-parametric and parametric inference for the drift function of a diffusion processe (Xt) on R, when one only observes either the first hitting times process (Ta) of increasing levels a, or the flat stretches of Xt, = sup (Xs, st) with length greater than η > 0, between two precribed levels x = Xo and A > x. For diffusions having positive drift, we prove that these observations are asymptotically sufficient with respect to the complete observation of (Xt) up to TA, when the variance of (Xt) and η, for the second observation, go simultaneously to O. We constuct estimators based on these observations. They are shown to be asymptotically normal, asymptotically equivalent to the maximum likelihood estimator based on the observation of (Xt) up to TA. We study in the third part models for cereal domestication
Daher, Hani. "Contribution à l'analyse de la dynamique des écritures anciennes pour l'aide à l'expertise paléographique." Phd thesis, Université René Descartes - Paris V, 2012. http://tel.archives-ouvertes.fr/tel-00834687.
Повний текст джерелаBen, Cheikh Mohamed Najeh. "Effet du contraste de la masse volumique sur le déplacement et l'infiltration de substances non réactives en milieu poreux saturé." Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL106N.
Повний текст джерелаLeymarie, Edouard. "Méthodes de variation de contraste par polarisation nucléaire en diffusion de neutrons aux petits angles : Observation de domaines de polarisation nucléaire par diffusion de neutrons." Phd thesis, Paris 11, 2002. https://tel.archives-ouvertes.fr/tel-00002103v2.
Повний текст джерелаIn this thesis we study the theoretical and experimental aspects of Contrast Variation by Nuclear Polarization (CVNP) applied to small-angle neutron scattering. The basics of neutron scattering theory is developed by highlighting the origin of the CVNP method : the strong spin dependence of thermal neutron scattering, especially on protons. We also present the principles of NMR with a special attention on the method of dynamic nuclear polarization by the solid effect which makes it possible to control the proton polarization and therefore the contrast for neutron scattering. We present a theoretical study of the CVNP method called static which supposes that the nuclear polarization is homogeneous in the sample and constant during the experiment. We show that it allows one to obtain partial structure functions of systems with multiple components, by carrying out several acquisitions with different polarizations on a single sample. For this purpose, we tested a simple device to stabilize the nuclear polarization. We describe finally a new application of the CVNP method called dynamic. In a solution of deuterated glycerol-water containing a small concentration of paramagnetic centres, we showed the existence of domains of polarized protons at the onset of dynamic polarization. This reinforces considerably the coherent scattering of paramagnetic centres. We describe the theoretical reasons explaining the appearance of these domains of polarization, as well as the various techniques used to observe them by neutron scattering
Papoular, Robert. "La spectrométrie par échos de spins de neutrons. Application à l'étude de la dynamique des polymères en solution." Paris 11, 1992. http://www.theses.fr/1992PA112092.
Повний текст джерелаThis work focuses on Neutron Spin Echo (NSE) spectroscopy and, particularly, on the NSE spectrometer MESS, which we have built at the L. L. B. (CEN-Saclay). After analyzing in detail the classical and quantum principles of this type of instrument, and illustrated them with optical analogies, we expound a simple formalism for the interpretation of polarized neutron experiments of the most general type. In a second part, we describe the MESS spectrometer extensively: its characteristics and performances as well as the first physics results obtained with this instrument. In particular, we include two papers showing how the neutron depolarization, spin rotation and echoes can be used to investigate high-Tc superconductors. The last part deals with the dynamics of Polymer-Polymer-Solvent ternary solutions and demonstrates how the Neutron Spin Echo technique becomes a privileged tool for such physico-chemical studies thanks to the joint use of NSE and contrast variation methods, coupled with the adequate ranges of time and scattering vectors accessible. Finally, we describe the specific case of partially deuterated polydimethylsiloxane (PDMS) in semi-dilute solution in Toluene. We have experimentally and separately evidenced the cooperative and interdiffusive diffusion modes predicted by the theory of Akcasu, Benoit, Benmouna et al. These results, obtained at the L. L. B. (CEN-Saclay) are the subjectmatter of the last paper included in this work
Bosco, Lionel. "Développement de sondes radicalaires intelligentes pour le diagnostic par IRM réhaussée par l'effet Overhauser." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4756/document.
Повний текст джерелаThis work promotes two strategies for the development of new contrast agents for the diagnosis by Overhauser enhanced MRI. Two approaches have therefore been addressed.The first approach is devoted to the development of a nitroxide-type spin label, which is capable to change its EPR (Electron Paramagnetic Resonance) signature upon a non-radical enzymatic activity. This modification, due to a conformational change, allowed us to perform a selective microwave irradiation of the probe released by proteolysis. This feature was applied to Overhauser enhanced MRI and of the image after enzymatic hydrolysis of 1200% in vitro has been obtained. Due to technical hindrances, a contrast enhancement of 600% has been obtained in vivo, while nowadays, the most common clinical contrast agent, based on GdIII complex, improve image contrast around a value of 50%.The second topic deals with the synthesies and the physico-chemical study of alkoxyamines, as nitroxide precursors, for the diagnosis by MRI enhanced by the Overhauser effect. The key point of this approach is based on the activation of these molecules to quickly release the nitroxide in situ. Encouraged by the results of chemical monoactivation, we performed the double chemical activation of these new alkoxyamines to drastically reduce the half-life time of one of them to obtain values compatible with diagnostic applications. A selective pseudo-peptide of chymotrypsin has also been grafted, which allowed us to achieve an alkoxyamine model that will validate our concept of diagnosis
Margoto, Jean-Baptiste. "Développement de dispositifs de diagnostics ultra-haute dynamique mono-coup avec une grande excursion temporelle et caractérisation spatio-temporelle au foyer de lasers femtosecondes ultra intenses." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX107.
Повний текст джерелаThis thesis has been carried out in the framework of the international development of high peak power ultrafast laser sources (TW to PW) that push forward the limits in terms of focused light intensity on target (>10^19 W/cm²). The chirped-pulse amplification (CPA) technique commonly used to amplify femtosecond laser pulses introduces spatio-temporal couplings (STC) in the event of imperfect alignment in the stretcher or compressor elements inside the amplification chain. These STC greatly reduce the peak power at focus. Controlling the temporal contrast of the pulse over several tens of picoseconds and with a high dynamic range is necessary in order to accurately know the laser-matter interaction conditions during experiments.Several techniques for spatio-temporal characterization of femtosecond pulses were studied during this thesis. The TERMITES technique showed its limits due to the experimental conditions inherent to TW and PW lasers (shot-to-shot and pointing fluctuations) and the maximum intrinsic dynamic range.The second technique is the extension of the Self-Referenced Spectral Interferometry with extended time excursion (SRSI-ETE) that aims at characterizing in single-shot both the spatio-temporal shape (in one transverse dimension) and the temporal contrast of the incident pulse. This technique is based on the spatio-temporal filtering by the cross-polarized wave (XPW) generation. Filtering is only effective for weak distortions and experimental measurements could not reconstruct the spatio-temporal shape of the pulse at the compressor output. However, the single-shot measurement of the temporal contrast of the pulse on ±37 ps and a dynamic range of 10^8 were validated by comparing results with a third order autocorrelator.The novel proposed technique, named CROISSANT, relies on the observation of the spatio-spectral intensity of the XPW pulse. Experimental results could characterize in a single laser shot the spatio-temporal shape of the pulse with high sensitivity. The method for identifying the specific STC and its correction method is given for both first- and second-order STC
Shi, Da. "Préparation et caractérisation de microbulles fonctionnelles stabilisées par des fluorocarbures et décorées de nanoparticules dendronisées : évaluation comme agents du contraste bimodaux pour l'IRM et l'imagerie par ultrasons." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAF053.
Повний текст джерелаThis Thesis focuses on the preparation and characterization of microbubbles stabilized with a fluorocarbon gas and decorated with dendronized magnetic nanoparticles. The impacts of perfluorohexane exposure mode on Langmuir monolayers formed by phospholipids and on the properties of microbubbles were evaluated. The behaviours of Langmuir monolayers formed by dendrons and of the mixtures of dendrons and phospholipids were investigated. The attractive fluorine-fluorine interactions that develop between the fluorocarbon gas and the fluorinated terminal group prompt the adsorption of nanoparticles grafted with dendrons to the air/water interface. Small and stable microbubbles decorated with dendronized iron oxide nanoparticles were prepared. The magnetic microbubbles were examined as bimodal contrast agents for MRI and ultrasound imaging on a murine model in collaboration with the Universitätklinikum in Freiburg. This work was supported by the INTERREG V (Nanotransmed)
Carré, Maxime. "Interprétation d'images acquises en situation de faible éclairement ou d'éclairement variable." Thesis, Saint-Etienne, 2013. http://www.theses.fr/2013STET4012.
Повний текст джерелаThe quality of image acquisitions is crucial in the resolution of imaging problems. Troubles during acquisiton can lead to unstability for image processing algorithms. We propose different methods (thresholding techniques, contour detection, pattern matching) based on new metrics and contrasts in the LIP context. The LIP (Logarithmic Image Processing) model is recognized as an efficient framework to process images acquired in transmitted light and to take into account the human visual system. LIP operations are also useful to simulate varitations of image parameters in situation of reflected light. Finally, we propose new methods of global and local dynamic enhancement in the LIP framework like a real time and realistic local dynamic correction that brings results close to those obtained by certain tone mapping methods
Chouket, Raja. "New dimensions for multiplexed fluorescence imaging." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS606.
Повний текст джерелаOur research group had previously developed the OPIOM protocols for fluorescence imaging. By exploiting their cross sections of fluorescence photoswiching, OPIOM can selectively extract the response of reversibly photoswitchable fluorophores (RSFs) in the presence of spectrally interfering fluorophores. However, OPIOM allowed us to discriminate only 3 spectrally similar reversibly photoswitchable fluorescent proteins (RSFPs). The goal of this PhD was to augment this number. To reach this goal, a new automated instrumental setup called photoswichometer was first developed to express and screen the rich photochemical signature of 22 RSFPs by analyzing their fluorescence response to light jumps with intensities covering 5 orders of magnitude. This signature has been first exploited in a new fluorescence imaging protocol called HIGHLIGHT, which capitalized on OPIOM and further improved its selectivity. In HIGHLIGHT, the RSFs are submitted to harmonic light modulation and their contribution to the overall fluorescence emission signals is selectively retrieved from exploiting their singular non-linear response under optimized conditions. HIGHLIGHT has been implemented to image RSFPs in cells without interference of autofluorescence, to perform multiplexed imaging of 3 RSFPs which could not be discriminated with OPIOM, and used for its intrinsic optical sectioning. The RSF signature has been then used in a second fluorescence imaging protocol called LIGHTNING. In contrast to OPIOM and HIGHLIGHT which exploit the cross sections of fluorescence photoswitching in a steady-state regime of low light intensity, LIGHTNING exploits the transient time fluorescence response of RSFs under multiple illuminations involving various ranges of light intensities for RSF discrimination. Thus, LIGHTNING allowed us to improve the multiplexing degree of dynamic contrast in fluorescence imaging up to 20 RSFP among 22 studied RSFPs
Lasoroski, Aurélie. "Etude de complexes de gadolinium d'intérêt pour l'IRM : simulations ab initio et propriétés magnétiques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00876988.
Повний текст джерелаPiederriere, Yann. "Etude du speckle de milieux diffusants liquides. Application à la détermination de paramètres biophysiques." Phd thesis, Université de Bretagne occidentale - Brest, 2003. http://tel.archives-ouvertes.fr/tel-00005314.
Повний текст джерелаMassoud, Chadi. "Evaluation de la filtration glomérulaire par IRM." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20037.
Повний текст джерелаThis study seeks to assess the Glomerular Filtration Rate (GFR) in the human kidney by MRI. To quantitatively estimate this parameter requires monitoring of the intrarenal kinetics of Gd after its bolus injection. To achieve this goal, we have developed under IDEA Siemens a SR-FLASH T1-weighted MRI sequence which can follow dynamic NMR signal changes after a bolus injection of Gd. This sequence has a centric phase-encoding scheme, and thus the image contrast was determined at the beginning of the acquisition period. Subsequently, we have implemented an IR-FLASH (with centric phase-encoding scheme) sequence to measure the longitudinal relaxation time in the absence of any injection of Gd ; this parameter is required to convert NMR signal intensities into Gd concentrations. knowing that the relation between the NMR signal intensities and the Gd concentrations is not linear, we have proposed two novel methods and yet fast and robust for conversion of the NMR signal intensities into local Gd concentration. This allowed us to estimate the temporal evolution of Gd concentrations in both kidneys and aorta. The fit of these concentrations measurements by a two-compartments model describing the function of the kidney allowed us to calculate the GFR of each kidney in a population of five subjects with normal renal function
Chevallier, François. "La Contrainte d'endettement dans la dynamique d'une petite économie ouverte." Paris 1, 1985. http://www.theses.fr/1985PA010028.
Повний текст джерелаChevallier, François. "La Contrainte d'endettement dans la dynamique d'une petite économie ouverte." Lille 3 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37594635b.
Повний текст джерелаPianelo, Laurent. "Modélisation géologique contrainte par les données sismiques et dynamiques." Aix-Marseille 1, 2001. http://www.theses.fr/2001AIX11042.
Повний текст джерелаAfonso, Eve. "ETUDE DE LA DYNAMIQUE DE LA TRANSMISSION DE TOXOPLASMA GONDII DANS DES MILIEUX CONTRASTES." Phd thesis, Université de Reims - Champagne Ardenne, 2007. http://tel.archives-ouvertes.fr/tel-00371738.
Повний текст джерелаWohrer, Adrien. "Model and large-scale simulator of a biological retina, with contrast gain control." Nice, 2008. http://www.theses.fr/2008NICE4011.
Повний текст джерелаThe retina is a complex neural structure. The characteristics of retinal processing are reviewed extensively in Part I of this work: It is a very ordered structure, which proceeds to band-pass spatio-temporal enhancements of the incoming light, along different parallel output pathways with distinct spatio-temporal properties. The spike trains emitted by the retina have a complex statistical structure, such that precise spike timings may play a role in the code conveyed by the retina. Several mechanisms of gain control provide a constant adaptation of the retina to luminosity and contrast. The retina model that we have defined and implemented in Part II can account for a good part of this complexity. It can model spatio-temporal band-pass behavior with adjustable filtering scales, with the inclusion of plausible mechanisms of contrast gain control and spike generation. The gain control mechanism proposed in the model provides a good fit to experimental data, and it can induce interesting effects of local renormalization in the output retinal image. Furthermore, a mathematical analysis confirms that the gain control behaves well under simple sinusoidal stimulation. Finally, the simulator /Virtual Retina/ implements the model on a large-scale, so that it can emulate up to around 100,000 cells with a processing speed of about 1/100 real time. It is ready for use in various applications, while including a number of advanced retinal functionalities which are too often overlooked
Louis, Jean-Sébastien. "Développements en IRM quantitative de perfusion pour le diagnostic de fibrose myocardique." Thesis, Université de Lorraine, 2020. http://www.theses.fr/2020LORR0061.
Повний текст джерелаHeart failure represents a major public health issue in western world. It is a complex syndrome that could be the cause and/or the consequence of underlying pathologies such interstitial diffuse fibrosis. Magnetic Resonance Imaging (MRI) is the reference imaging modality for soft tissue assessment and especially the myocardium. Several imaging biomarkers such relaxation time T1 or extracellular volume fraction (ECV) have proven their diagnostic power in term of sensitivity and specificity. MRI with contrast agent injection has also demonstrated its usefulness in diagnostic of post-infarct local fibrosis for instance. Dynamic contrast enhancement (DCE) is widely investigated for its supposed ability to discriminate areas from which perfusion/permeability properties have been altered by the presence of fibrosis deposition. We hypothesized that the quantification of myocardial permeability and the estimation of the extracellular extravascular volume fraction Ve could led to a better detection of diffuse fibrosis. Consequently, we investigated the possibility of a shorter protocol for the evaluation of ECV. In this manuscript, we first present the methodological developments that allow the quantitative analysis of DCE cardiac MRI. This implied the development of a post-processing method for Arterial Input Function reconstruction, allowing DCE quantification without the need of specific sequences or protocols. A post-processing algorithm for perfusion images registration have been developed for pixel-wise parametric maps reconstruction. Data acquisition have been simulated in a Monte-Carlo fashion in order to assess the impact of acquisition strategies on parameters accuracy. This eventually led to the design of the shortest possible imaging strategy for Ve quantification. Secondly, clinical results obtained with our quantitative DCE analysis framework have been confronted to those obtained with classical ECV method for diffuse fibrosis detection. Correlation between those two parameters have been found a group of 12 patients presenting mitral valve prolapses. Permutation test on Ve distribution allowed us to show a significant difference between two groups the same way the ECV values did. The presented work describes a full quantitative DCE analysis framework that could allow to a shorter imaging protocol for extracellular extravascular estimation for diffuse myocardial fibrosis diagnosis
Blanc, Annie. "Analyse du comportement dynamique des raquettes de tennis." Lyon, INSA, 1986. http://www.theses.fr/1986ISAL0033.
Повний текст джерелаFombaron, Nathalie. "Contrats d'assurance dynamiques en presence d'antiselection : les effets d'engagement sur des marches concurrentiels." Paris 10, 1997. http://www.theses.fr/1997PA100188.
Повний текст джерелаSylvestre, Mélody. "Modélisation numérique de la dynamique atmosphérique de Saturne contrainte par les données Cassini-Huygens." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066446/document.
Повний текст джерелаSaturn's atmosphere undergoes important seasonal variations of insolation, due to its obliquity, its eccentricity and the shadow of its rings. In the stratosphere (from 20 hPa to 10-4 hPa), radiative and photochemical timescales are in the same order as Saturn's revolution period (29.5 ans). Hence, significative seasonal and meridional variations of temperature and photochemical by-products (especially C2H6, C2H2, and C3H8) are expected. Because of its duration (2004-2017), the Cassini mission is an unprecedented opportunity to monitor the seasonal evolution of Saturn's atmosphere. During my PhD, I analysed Cassini/CIRS limb observations as they probe the meridional and vertical structure of Saturn's stratosphere. Hence, I measured seasonal variations of temperature and abundances of C2H6, C2H2, and C3H8. I also contributed to the development of a radiative-convective model and a GCM (Global Climate Model) of Saturn's atmosphere. The predictions of these models are compared with the temperatures measured from CIRS observations, in order to study the radiative and dynamical processes which contribute to the seasonal evolution. Numerical simulations performed with the GCM also allowed me to study atmospheric waves propagation and the effects of rings shadowing in Saturn's atmosphere. Besides, comparison between C2H6, C2H2, and C3H8 distributions and photochemical models (Moses and Greathouse 2005, Hue et al., 2015) give insights on meridional transport
Martin, Bruno. "Application de la photoélasticité à la mesure de la contrainte dynamique des engrenages cylindriques." Mémoire, École de technologie supérieure, 2006. http://espace.etsmtl.ca/483/1/MARTIN_Bruno.pdf.
Повний текст джерелаAfonso, Eve. "Etude de la dynamique de la transmission de Toxoplasma gondii dans des mileux contrastés." Reims, 2007. http://theses.univ-reims.fr/exl-doc/GED00000735.pdf.
Повний текст джерелаWe studied the dynamic of the transmission of a parasite with complex life-cycle, Toxoplasma gondii, in contrasted environments. First, the dynamic of the parasite transmission was studied in an urban area where a population of domestic cats (Felis catus) live at high density. Our results raise the hypothesis that the parasite transmission could occur via a simple life-cycle when intermediate hosts are in very low density, relative to cats. We also highlighted the presence of localised areas contaminated by T. Gondii oocysts, which correspond to defecation site of cats. Second, we studied the dynamic of the transmission of T. Gondii in environments where intermediate hosts are in high density. We found indicators of the interspecific variability in the level of infection of intermediate hosts, such as body mass or habitat. Moreover, we showed that environment composition, climate fluctuations and the level of infection of toxoplasmosis in domestic cats and wildcats (Felis silvestris) could be related. The whole study shows the interest of an eco-epidemiological approach to understand the variability of the life-cycle of T. Gondii
Martin, Bruno. "Application de la photoélasticité à la mesure de la contrainte dynamique des engrenages cylindriques /." Thèse, Montréal : École de technologie supérieure, 2006. http://proquest.umi.com/pqdweb?did=1292462021&sid=1&Fmt=2&clientId=46962&RQT=309&VName=PQD.
Повний текст джерела"Mémoire présenté à l'École de technologie supérieure comme exigence partielle à l'obtention de la maîtrise en génie mécanique". CaQMUQET Bibliogr.: f. [226]-228. Également disponible en version électronique. CaQMUQET
Afonso, Eve Poulle Marie-Lazarine Gilot-Fromont Emmanuelle. "Etude de la dynamique de la transmission de Toxoplasma gondii dans des mileux contrastés." Reims : S.C.D. de l'Université, 2007. http://scdurca.univ-reims.fr/exl-doc/GED00000735.pdf.
Повний текст джерелаRazumnaya, Anna. "Propriétés dynamiques des couches minces et des super-réseaux ferroélectriques contrôlées par la contrainte." Thesis, Amiens, 2018. http://www.theses.fr/2018AMIE0009.
Повний текст джерелаWe investigate near- and sub-Terahertz dynamics of soft and Debye-type central modes by the polarized Raman spectroscopy in ferroelectric BaTiO3/BaxSr1-xTiO3 superlattices in a broad temperature range. Coexistence of the central peak and the underdamped soft mode suggests complicated order-disorder character of successive phase transitions in these superlattices. The occurrence of the pronounced central mode can explain the recently observed relaxor-like dielectric anomaly in such superlattices. We explore and compare the lattice dynamics of three-layer and two-layer superlattices. We show that the using layers of different chemical compositions in multilayered superlattices one can obtain heterostructures with the desirable characteristics and realize fine tuning of their parameters due to strain effects between alternating layers.We construct the “temperature-misfit strain” theoretical phase diagrams for BaxSr1-xTiO3 thin films grown on (111)-oriented cubic substrates. The phase diagrams are useful for practical applications in thin-film engineering. We experimentally investigate a Ba0.8Sr0.2TiO3 thin film deposited on (111)MgO substrate with the aim to verify our theoretical predictions. We study the field-induced polarization reversal in the c-oriented ferroelectric phase of strained perovskite films. We show that in addition to the conventional longitudinal switching mechanism, when the c-oriented polarization vector changes its modulus, the longitudinal-transversal and transversal mechanisms when the perpendicular component of polarization is dynamically admixed are possible
Senger, Fabrice. "Dynamique du cytosquelette et polarité cellulaire." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV089/document.
Повний текст джерелаCells sense and integrate a wealth of mechanical and biochemical signals. Signal integration is part of a process, which ensures that cellular functions are in accordance with the extracellular environment. While these processes are highly regulated by biochemical and mechanical signalling and feedback loops, some of the fundamental processes appear to rely on actin cytoskeleton autoassembly giving raise to modules with defined geometrical and mechanical properties. Thus the actin cytoskeleton is a modular architecture, and the modules co-exist within the cell with spatial and functional specificity. The actin cytoskeleton, notably, is involved in cell/matrice signalling. This interaction relies mainly on mechanical signalling involving the actin cytoskeleton, cell/matrix adhesions and the extracellular matrix. To characterize these mechanisms we took advantage of advanced micropatterning techniques, traction force measurements and laser microdissection. By downregulating the expression of α-actinin, one of the main actin crosslinking proteins, we demonstrated that actin cytoskeleton connectivity is essential for proper integration of cell/matrix signalling. Connectivity is essential for rigidity sensing and haptotaxis by ensuring balanced force distribution through the whole cell. Therefore connectivity might be crucial for cell differentiation processes and cellular polarity. Further, in the context of a collaborative project, we have contributed to the characterization of a novel cell adhesion protein, namely, Kank2. We showed, by traction force measurements, that this protein is essential for rigidity sensing. Globally this study demonstrated the implication of Kank2 in cell adhesion maturation and mecanotransduction
De, Franco Carmine. "Deux études en gestion du risque : assurance de portefeuille avec contrainte en risque et couverture quadratique dans les modèles à sauts." Paris 7, 2012. http://www.theses.fr/2012PA077122.
Повний текст джерелаIn this thesis I first study the problem of portfolio insurance from the point of view of a fund manager, who guarantees to the investor that the portfolio value will be above a fixed threshold. If it is not the case, a third party will refund the investor up to the guarantee. In exchange, the third party imposes a limit on the risk exposure of the fund manager, in the form of a convex monetary risk measure. The fund manager tries to maximize the investor's utility function subject to the risk measure constraint. I give a full solution to this non-convex optimization problem and show that the choice of the risk measure constraint. I give a full solution to this non-convex optimization problem and show that the choice of the risk measure is crucial for the optimal portfolio to exist. Explicit results are provided for the entropic risk measure, for spectral risk measures and for the G-divergence. In the secon part I study the problem of quadratic hedge in incomplete markets. I work with a three-dimensional Markov jump process : the first variable represents the hedging instrument and is not traded in the market, as a volatility factor ; the third one is a source of risk which affects the option's pay-off and is also not traded. I prove that the value function of the problem, as a function of the initial wealth, is a second order polynomial whose coefficients are characterized as the unique smooth solutions of a triplet of PIDEs, the first of which is semilinear and does not depend on the option, the other two being linear. This result is stated for non-degenerate jump-diffusions and for pure jump processes. I apply my results to an example in the context of electricity markets
Grenier, Mathieu. "Optimisation de l'ordonnancement sous contrainte de faisabilité." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2007. http://tel.archives-ouvertes.fr/tel-00192466.
Повний текст джерелаpropres à l'application.
Deux cas ont été analysés : le cas de tâches indépendantes périodiques s'exécutant sur un processeur et le cas de flux de messages indépendants périodiques sur un réseau de terrain avec accès au médium priorisé.
Nous avons donc proposé pour traiter les deux problèmatiques abordées :
1) des méthodes de configurations permettant d'optimiser l'utilisation de la plate-forme d'exécution en fixant d'une manière appropriée les paramètres : des politiques ou des activités du système considéré. Deux études ont été conduites dans ce cadre~: l'allocation des ``offsets'' dans les systèmes ``offset free'' et l'allocation de priorités, de politiques et de quantum dans
les systèmes conformes au standard Posix~1003.1b,
2) une nouvelle classe de politiques d'ordonnancement permettant
d'optimiser des critères de performances propres à l'application.