Dissertations / Theses on the topic 'Propagation des Données'
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Stattner, Erick. "Contributions à l'étude des réseaux sociaux : propagation, fouille, collecte de données." Phd thesis, Université des Antilles-Guyane, 2012. http://tel.archives-ouvertes.fr/tel-00830882.
Full textHenry, Didier. "Modèles de propagation de l'information et méthodes de sciences des données." Thesis, Antilles, 2018. http://www.theses.fr/2018ANTI0323/document.
Full textNowadays, online social media has transformed the way we create, share and access information. These platforms rely on gigantic networks that promote the free exchange of information between hundreds of millions of people around the world, and this instantly.Whether related to a global event or in connection with a local event, these messages may influence a society and may contain information useful for the detection or prediction of real-world phenomena.However, some broadcast messages can have a very negative impact in real life. These messages containing false information can have disastrous consequences.To avoid and anticipate these dramatic situations, follow rumors, avoid bad reputations, it is necessary to study and then model the propagation of information.However, most of the diffusion models introduced are based on axiomatic hypotheses represented by mathematical models. As a result, these models are far removed from the users' dissemination behaviors in that they do not incorporate observations made on concrete dissemination cases. In our work, we study the phenomenon of diffusion of information at two scales. On a microscopic scale, we observed diffusion behaviors based on the personality traits of users by analyzing the messages they post in terms of feelings and emotions. On a macroscopic scale, we analyzed the evolution of the diffusion phenomenon by taking into account the geographical dimension of the users
Richa, Jean Raphaël. "Amélioration de l'ingénierie des données dans les environnements connectés grâce à la détection de la propagation et de l'obsolescence des données." Electronic Thesis or Diss., Pau, 2024. http://www.theses.fr/2024PAUU3077.
Full textThe relentless expansion of digital technologies has enhanced the capabilities of collecting, visualizing, analyzing, and autonomously managing the environment surrounding us.Intelligent and increasingly connected is the prevailing trend within the rising metaverse, where connected environments are driven to gather a plethora of data.These environments contribute to a better understanding of human activities, improve quality of life, and ease paths for sustainability.This thesis introduces two pivotal concepts - zone continuum and data obsolescence - furthering awareness of connected environments by explaining how data crosses between zones and detecting when data becomes irrelevant with respect to its environment.By addressing these overlooked aspects, we aim to improve data interpretation and management within connected environments.This thesis addresses four key challenges: (1) designing a deep and expressive data model that effectively captures the core components of connected environments, such as hosting zones, smart devices, and their corresponding sensor networks; (2) establishing a mechanism to discover and trace how data propagates between different zones; (3) proposing a large-scale approach to detect data obsolescence while considering the entire environment; and (4) handling the dynamic nature of the CE that could be illustrated by the mobility and failure of the devices, as well as modifications in zone configurations (e.g., combining multiple zones into one or dividing a single zone into several).To address these challenges, we first propose the HSSN+ data model, which underpins a resilient representation of the elements in connected environments.Consequently, in light of this model, we put forward two interconnected frameworks. The first one is the Zone Continuum Computation for Connected Environments (ZCCCE) framework that formalizes the zone continuum concept and enables to understand how data moves between zones. The second one is the Data Obsolescence Detection in Connected Environments (DODCE) framework which offers a structured approach to identify and compute the data obsolescence based on predefined quality indicators.These two frameworks provide opportunities for effective control and understanding in connected environments
Gillier, Martin. "Environnement acoustique de la surface de Mars : analyse des données des microphones de Perseverance et modélisation de la propagation du son." Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0040.
Full textOn February 18, 2021, the Perseverance rover landed in Jezero crater on the surface of Mars. Since then, the two microphones on board have acquired dozens of hours of sound recordings, paving the way for a new method of studying the Martian surface environment. It is within this framework that this thesis takes place, studying the propagation of sound waves on the surface of Mars through the analysis of Martian data and modeling.After briefly discussing how the work presented in this thesis lies at the crossroads of Mars exploration and the study of the atmosphere by acoustic means, the specifics of the data acquired by Martian microphones are presented. I focus in particular on the problem of saturation, to show how the constraints inherent in operating a microphone on the surface of Mars have an impact on this phenomenon, and how desaturation methods make it possible to mitigate this risk to some extent. All the audio recordings are then shown in the form of a catalog, with a presentation of the characteristics of each sound source, from both an individual and statistical point of view. The scientific applications enabled by each type of recording are also described. Secondly, work on modeling sound propagation on the surface of Mars is presented. I first describe how to use a physics-based acoustic model to derive the speed of sound and the acoustic attenuation coefficient at all points on the surface of Mars at all times. Then, I show how the use of an atmospheric acoustics model allows us to account for all the phenomena present on the surface of Mars that have an influence on sound propagation.The result of this thesis is, on the one hand, a demonstration of the scientific interest of using acoustic methods to study the atmosphere and surface of other planets and, on the other, a model enabling us to predict the sound field created by a specific source at all points on the surface of Mars at all times. The lessons learned from this work on the use of microphones for planetary science, and the modeling methods developed here, will be useful for future missions carrying acoustic instruments to other bodies in the Solar System
Sauvé, Alexandre. "Caractérisation des effets systématiques de l'instrument Planck/HFI, propagation et impact sur les données scientifiques." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30362/document.
Full textPlanck is an ESA spacecraft launched in 2009, its mission goal was to map with an exquisite precision the first light of Universe, to help understanding how it has formed. This ambitious objective requires a very high level of control on the instrumental effects. During the mission, it has been found that the component responsible of the digitization of scientific data introduced an unexpectedly high bias effect, preventing full exploitation of data from the Planck/HFI instrument. The present work relates how this bias effect was understood and successfully corrected for. A very deep analysis of the spacecraft detectors, the cryogenic chain, and the digitization component has been performed, which required a specific methodology to gather data from the spacecraft before the end of the mission and its decommissioning
Jégou, Philippe. "Contribution à l'étude des problèmes de satisfaction de contraintes : algorithmes de propagation et de résolution : propagation de contraintes dans les réseaux dynamiques." Montpellier 2, 1991. http://www.theses.fr/1991MON20015.
Full textClarke, Richard William Barnes. "Modélisation et inversion de données cinématiques complexes en 3D." Pau, 1997. http://www.theses.fr/1997PAUU3010.
Full textGrimald, Sandrine. "Etude de l'émission et de la propagation du Continuum terrestre à partir des données des satellites Cluster." Phd thesis, Université d'Orléans, 2007. http://tel.archives-ouvertes.fr/tel-00143912.
Full textLe, Pape Cécile. "Contrôle de qualité des données répliquées dans un Cluster." Paris 6, 2005. http://www.theses.fr/2005PA066433.
Full textVanderbecken, Pierre J. Y. "Apport des infrasons pour l'assimilation de données dans un modèle global de prévision numérique du temps." Electronic Thesis or Diss., Toulouse 3, 2020. http://www.theses.fr/2020TOU30328.
Full textInfrasounds are acoustic waves between 0 and 20 Hz emitted by a wide variety of sources. Due to their low frequencies, vertical gradients of winds and temperature lead to the formation of waveguides in which they can propagate over thousands of kilometers with little attenuation. Since this type of propagation is intrinsically linked to the atmospheric circulation, these waves can be used as tracers. The general circulation in the stratosphere and the mesosphere, which forms the middle atmosphere, provides the most efficient acoustic waveguides. It is proposed here to use ground-based infrasound signals to provide new information on the circulation of the middle atmosphere. It can be used to improve the initialization of numerical weather prediction (NWP) models. For an observation to be assimilated, it is necessary to define an observation operator, able to simulate it from model predictions. The aim of this thesis is to examine how to assimilate infrasounds by designing a dedicated observation operator. After presenting the state of knowledge on atmospheric circulation and the principle of data assimilation, we examine the infrasound data of the international monitoring system. This system is maintained by the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). An observation operator compatible with the needs of assimilation can be designed from a propagation model by taking advantage of fast propagation methods and well-known natural sources such as volcanoes. Given the limitations associated with these methods and sources, it is difficult to design an observation operator allowing the direct assimilation of infrasound data. We propose then to solve the inverse problem by retrieving vertical profiles of winds and temperature consistent with the recorded infrasound signals. Firstly, we have highlighted the need to superimpose a disturbance onto the atmospheric profiles in order to simulate real acoustic signals using ray tracing or modal decomposition methods. Then, within the frame of a simplified atmosphere with two degrees of freedom and simulated signals, we examined the ability of local optimization methods to estimate the atmospheric disturbance minimizing the discrepancies between modelled and observed signals. The results of this study show the difficulty in obtaining an optimal disturbance without prior information on it. This led us to develop a Bayesian approach, taking as prior information an ensemble of analyzes and short-term forecasts of the Météo-France global NWP model. The differences between the simulation results from a ray tracing code and the infrasound measurements are used to compute the likelihood of each member of the ensemble. This method was assessed using infrasound signals emitted by Mount Etna eruptions during May 2016. We show that this method allows to select the most likely members of the ensemble, and thus to provide atmospheric profiles, in agreement with observed infrasounds. These profiles could then be considered as pseudo-observations in a data assimilation system
Ghelfi, Alexandre. "Analyse des données de l'expérience AMS-02 pour la propagation du rayonnement cosmique dans la cavité solaire et la Galaxie." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY044/document.
Full textCosmic rays (CR) were discovered by Viktor Hess in 1912. Charged CR are synthesized and supposedly accelerated in supernova remnants, then propagate through the Galaxy. CR flux measurement set constraints on CR sources and propagation, but may also bring answers to the dark matter problem.AMS-02 is a high precision particle physics detector placed on the international space station since may 2011. It measures the CR fluxes of many species.This thesis deals with the proton flux estimation measured by the AMS-02 instrument. The focus is set on the unfolding of the instrument energy response impacting the flux, and on the caracterisation of the high-energy spectral break.The Sun produces a plasma which interacts with CR particles, modifying the flux obtained from galactic propagation. This modification evolves through time following the solar activity cycle, and is denoted solar modulation. In this framework, decolving from this effect, a robust determination of the proton and helium interstellar fluxes is obtained using recent high precision CR data including AMS-02. The associated solar modulation levels are cross-checked with a second estimation taken from neutron monitors (ground based detectors) data, allowing solar modulation time series reconstruction from the 50s
Benna, Mehdi. "Génération et inversion de données de propagation d'ondes radio à travers un noyau cométaire (simulation de l'expérience CONSERT)." Toulouse 3, 2002. http://www.theses.fr/2002TOU30116.
Full textRochoux, Mélanie Catherine. "Vers une meilleure prévision de la propagation d'incendies de forêt : évaluation de modèles et assimilation de données." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0009/document.
Full textBecause wildfires feature complex multi-physics occurring at multiple scales, our ability to accurately simulate their behavior at large regional scales remains limited. The mathematical models proposed to simulate wildfire spread are currently limited because of their inability to cover the entire range of relevant scales, because also of knowledge gaps and/or inaccuracies in the description of the physics as well as inaccuracies in the description of the controlling input parameters (i.e., the vegetation, topographical and meteorological properties). For this purpose, the uncertainty in regional-scale wildfire spread modeling must be quantified and reduced. In this context, the goals of this thesis are two-fold. First, multi-physics detailed simulations of fire propagation, solving for the flame structure using Navier-Stokes equations for multi-species reacting flow and including radiation heat transfer, biomass pyrolysis as well as a flame/vegetation interface, were performed at the flame scale. These simulations were compared to measurements to provide a comprehensive understanding of the mechanisms underlying fire propagation. Second, the use of a data-driven simulator that sequentially integrates remote sensing measurements and relies on an empirical spread model was explored for regional-scale fire front tracking. The idea underlying this data assimilation strategy was to translate the differences in the observed and simulated fire front locations into a correction of the input parameters of the empirical model or directly of the fire front location via the ensemble Kalman filter algorithm. Since these two approaches account for uncertainties in fire spread modeling and measurements, they improve our ability to forecast wildfire dynamics and plume emissions. These challenges have been identified as a valuable research objective with direct applications in fire emergency response for civil defense and environmental protection
Collino, Francis. "Analyse numérique de modèles de propagation d’ondes : application à la migration et à l’inversion des données sismiques." Paris 9, 1987. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1987PA090076.
Full textHoang, Tuan Nha. "Incertitude des données biomécaniques : modélisation et propagation dans les modèles de diagnostic des pathologies du système musculosquelettique." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2171/document.
Full textThe aim of the project is to investigate the modeling of the reliability/incertitude/imprecision of biomedical and biomechanics data (medical images, kinematics/kinetics/EMG data, etc.) and its propagation in the predictive diagnosls models of the disorders of musculoskeletal systems. These diagnosis models will be based on multimodal and multidimensional patient data (3D medical imaging, mechanical data,dinical data,etc.). The literature-based data have been collected to estabish an uncertainty space, which represents fused data from multiple sources, of morphological, mechanical, and movement analysis properties of the musculoskeletal system from multiple sources (i.e. research papers from Science Direct and Pubmed). After that,a new clustering method (US-ECM) is proposed for integrating fused data from multiple sources ln form of a multidimensional uncertainty space (US). Reliability of biomechanical data was evaluated by a fusion approach expert opinion. Reliability criteria of a data source (ie scientific paper published) focus on the technique used the acquisition protocol and measurement and the number of data. A system of questionnaires was developed to co!lect expert opinion. Then, the theory of beliet functions has been applied to merge these opinion to establish a confidence level each data source
Claverie, Jacques. "Application des données météorologiques de l'expérience "Pacem 1" à l'étude des situations atmosphériques conduisant à des phénomènes de propagation par trajets multiples." Paris 11, 1985. http://www.theses.fr/1985PA112152.
Full textBased upon the data collected during the PACEM 1 experiment, this thesis studies the meteorological conditions observed when the propagation on line-of-sight radio links suffers from multipath fading. After a complete discussion if the meteorological measurements accuracy, we analyze the results provided by a ray-tracing program. Then, three particular but quite representative cases are more precisely examined leading to some general conclusions
Hanatani, Yoshito. "Trompette à six trous ou Analyse sémantique de corrélation dans les bases de données." Paris 11, 1987. http://www.theses.fr/1987PA112488.
Full textThis thesis addresses the following two issues of relational database theory: (1) a two-level update propagation model and (2) a representation theory of dependency constraints. The two-level propagation model is proposed for the auto-deductive updates with the minimum loop cost and with the strict respect of the semantics of the Universe. The theory of representation of constraints is developed as a design tool. By virtue of its radical reduction of the expression complexity through the use of the simple abject called "bases" of constraints, this theory enables us to seize the deductive power and all other characteristics of the constraints, which are necessary for the conception of the database scheme. Starting from a uniform representation of the FD + MVD constraints, we see that its extension to the FD + multi-JD constraints is more natural and significant. The foundation of this extension leads us to the direct grasp of the constraint using a configuration CDDO, which can be seen as a dependency expression of new category
Marie, Nicolas. "Recherche exploratoire basée sur des données liées." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4129/document.
Full textThe general topic of the thesis is web search. It focused on how to leverage the data semantics for exploratory search. Exploratory search refers to cognitive consuming search tasks that are open-ended, multi-faceted, and iterative like learning or topic investigation. Semantic data and linked data in particular offer new possibilities to solve complex search queries and information needs including exploratory search ones. In this context the linked open data cloud plays an important role by allowing advanced data processing and innovative interactions model elaboration. First, we detail a state-of-the-art review of linked data based exploratory search approaches and systems. Then we propose a linked data based exploratory search solution which is mainly based on an associative retrieval algorithm. We started from a spreading activation algorithm and proposed new diffusion formula optimized for typed graph. Starting from this formalization we proposed additional formalizations of several advanced querying modes in order to solve complex exploratory search needs. We also propose an innovative software architecture based on two paradigmatic design choices. First the results have to be computed at query-time. Second the data are consumed remotely from distant SPARQL endpoints. This allows us to reach a high level of flexibility in terms of querying and data selection. We specified, designed and evaluated the Discovery Hub web application that retrieves the results and present them in an interface optimized for exploration. We evaluate our approach thanks to several human evaluations and we open the discussion about new ways to evaluate exploratory search engines
Séchet, Etienne. "Modélisation d'une connaissance imprécise sur les influences des conditions météorologiques dans la propagation du son, à partir de données expérimentales." Paris 9, 1996. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1996PA090026.
Full textFruit, Gabriel. "Propagation des ondes MHD dans les couches de courant.Structure des modes et transferts énergétiques.Comparaison avec les données CLUSTER." Phd thesis, Université Paul Sabatier - Toulouse III, 2003. http://tel.archives-ouvertes.fr/tel-00094680.
Full textdonnées cette thèse propose un cadre théorique auto-cohérent visant à étudier la réponse linéaire
d'une couche de plasma non homogène à une perturbation initiale, dans l'approximation de la MHD
idéale. En particulier, le calcul est mené jusqu'à la reconstruction finale des signaux
spatio-temporels avec une discussion des amplitudes obtenues et des transferts énergétiques qui en
découlent. Cette dernière étape est essentielle dans la perspective d'une comparaison avec les
données CLUSTER.
L'étude des modes propres de la queue magnétosphérique terrestre montre l'existence de deux
catégories d'oscillations : des modes globaux oscillant à des fréquences discrètes et confinés au
centre de la couche, et des modes continus liés au phénomène d'absorption résonante et dont
l'amplitude décroît au cours du temps. En utilisant diverses géométries de pulses initiaux, nous
étudions le couplage entre l'excitateur et ces modes propres. Il est mis en évidence que le
couplage avec les modes globaux est optimal pour un pulse dont la taille est voisine de l'épaisseur
de la couche. Même dans ce cas, les fluctuations restent cependant modestes. En revanche, avec le
même pulse initial, l'absorption du signal dans le continuum est efficace et conduit à un transfert
d'énergie non négligeable des ondes vers le plasma.
Enfin, un exemple d'oscillations magnétiques mesurées par CLUSTER est analysé et confronté
avec les résultats du modèle théorique. En effet l'étude théorique permet de préciser la nature des
perturbations ainsi que leur origine, dans l'hypothèse où ces fluctuations obéissent à une
description MHD.
Desquesnes, Xavier. "Propagation de fronts et p-laplacien normalisé sur graphes : algorithmes et applications au traitement d'images et de données." Phd thesis, Université de Caen, 2012. http://tel.archives-ouvertes.fr/tel-00773434.
Full textDesquesnes, Xavier. "Propagation de fronts et p-laplacien normalisé sur graphes : algorithmes et applications au traitement d’images et de données." Caen, 2012. http://www.theses.fr/2012CAEN2073.
Full textThis work deals with the transcription of continuous partial derivative equations to arbitrary discrete domains by exploiting the formalism of partial difference equations defined on weighted graphs. In the first part, we propose a transcription of the normalized p-Laplacian operator to the graph domains as a linear combination between the non-local infinity Laplacian and the normalized Laplacian (both in their discrete version). This adaptation can be considered as a new class of p-Laplacian operators on graphs that interpolate between non-local infinity Laplacian and normalized Laplacian. In the second part, we present an adaptation of fronts propagation equations on weighted graphs. These equations are obtained by the transcription of the continuous level sets method to a discrete formulation on the graphs domain. Beyond the transcription in itself, we propose a very general formulation and efficient algorithms for the simultaneous propagation of several fronts on a single graph. Both transcription of the p-Laplacian operator and level sets method enable many applications in image segmentation and data clustering that are illustrated in this manuscript. Finally, in the third part, we present a concrete application of the different tools proposed in the two previous parts for computer aided diagnosis. We also present the Antarctic software that was developed during this PhD
Badard, Thierry. "Propagation des mises à jour dans les bases de données géographiques multi-représentations par analyse des changements géographiques." Marne-la-Vallée, 2000. http://www.theses.fr/2000MARN0141.
Full textBlondel-Couprie, Elise. "Reconstruction et prévision déterministe de houle à partir de données mesurées." Phd thesis, Ecole centrale de nantes - ECN, 2009. http://tel.archives-ouvertes.fr/tel-00449343.
Full textMehdi, Benna. "Génération et inversion de données de propagation d'ondes radio à travers un noyau comètaire (Experience CONSERT - Mission Spatiale ROSETTA)." Phd thesis, Université Paul Sabatier - Toulouse III, 2002. http://tel.archives-ouvertes.fr/tel-00007990.
Full textKrivtchik, Guillaume. "Analysis of uncertainty propagation in nuclear fuel cycle scenarios." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI050/document.
Full textNuclear scenario studies model nuclear fleet over a given period. They enablethe comparison of different options for the reactor fleet evolution, and the management ofthe future fuel cycle materials, from mining to disposal, based on criteria such as installedcapacity per reactor technology, mass inventories and flows, in the fuel cycle and in the waste.Uncertainties associated with nuclear data and scenario parameters (fuel, reactors and facilitiescharacteristics) propagate along the isotopic chains in depletion calculations, and throughoutthe scenario history, which reduces the precision of the results. The aim of this work isto develop, implement and use a stochastic uncertainty propagation methodology adaptedto scenario studies. The method chosen is based on development of depletion computationsurrogate models, which reduce the scenario studies computation time, and whose parametersinclude perturbations of the depletion model; and fabrication of equivalence model which takeinto account cross-sections perturbations for computation of fresh fuel enrichment. Then theuncertainty propagation methodology is applied to different scenarios of interest, consideringdifferent options of evolution for the French PWR fleet with SFR deployment
Benoit, Jean-Christophe. "Développement d'un code de propagation des incertitudes des données nucléaires sur la puissance résiduelle dans les réacteurs à neutrons rapides." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-01064275.
Full textBenoit, Jean-christophe. "Développement d’un code de propagation des incertitudes des données nucléaires sur la puissance résiduelle dans les réacteurs à neutrons rapides." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112254/document.
Full textThis PhD study is in the field of nuclear energy, the back end of nuclear fuel cycle and uncertainty calculations. The CEA must design the prototype ASTRID, a sodium cooled fast reactor (SFR) and one of the selected concepts of the Generation IV forum, for which the calculation of the value and the uncertainty of the decay heat have a significant impact. In this study is developed a code of propagation of uncertainties of nuclear data on the decay heat in SFR.The process took place in three stages.The first step has limited the number of parameters involved in the calculation of the decay heat. For this, an experiment on decay heat on the reactor PHENIX (PUIREX 2008) was studied to validate experimentally the DARWIN package for SFR and quantify the source terms of the decay heat.The second step was aimed to develop a code of propagation of uncertainties : CyRUS (Cycle Reactor Uncertainty and Sensitivity). A deterministic propagation method was chosen because calculations are fast and reliable. Assumptions of linearity and normality have been validated theoretically. The code has also been successfully compared with a stochastic code on the example of the thermal burst fission curve of 235U.The last part was an application of the code on several experiments : decay heat of a reactor, isotopic composition of a fuel pin and the burst fission curve of 235U. The code has demonstrated the possibility of feedback on nuclear data impacting the uncertainty of this problem.Two main results were highlighted. Firstly, the simplifying assumptions of deterministic codes are compatible with a precise calculation of the uncertainty of the decay heat. Secondly, the developed method is intrusive and allows feedback on nuclear data from experiments on the back end of nuclear fuel cycle. In particular, this study showed how important it is to measure precisely independent fission yields along with their covariance matrices in order to improve the accuracy of the calculation of the decay heat
Fruit, Gabriel. "Propagation des ondes MHD dans les couches de courant. Structure des modes et transferts énergétiques. Comparaison avec les données cluster." Toulouse 3, 2003. http://www.theses.fr/2003TOU30018.
Full textSince the success of the CLUSTER mission the tridimensional structure of the low frequency perturbations propagating in the key regions of the Earth magnetosphere can be studied. In order to help the interpretation of these data, this thesis propose a theoretical and self-consistent model aiming the study of the linear response of an inhomogeneous plasmasheet to an initial excitation, in the frame of the ideal MHD. Especially the calculus is lead to the final reconstruction of the spatial-temporal signals with a discussion of the amplitudes and of the energetic transfers. This last step is essential for a precise comparison with CLUSTER data. .
Clairais, Aurélien. "Calage en ligne d'un modèle dynamique de trafic routier pour l'estimation en temps réel des conditions de circulation." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSET004/document.
Full textTraffic models are of paramount importance for understanding and forecasting traffic dynamics. They represent a significant support for all the stages of traffic management. This thesis focuses on issues related to daily traffic management. For road network managers, four challenges are addressed. The speed refers to the choice of the scale of representation and formulation of the flow model. The selected model is the Lagrangian-Space LWR model. The reliability is associated to the integration of the model errors in the traffic conditions estimation process. The reactivity is described as the capacity of the method to take into account the prevailling traffic states in real time. Finally, the versatility refers to the capacity of the method parameters to evolve considering the observed traffic situations.The scientific challenges that the presented works aim are based on the four issues. The integration of the uncertainties into the flow model is a first challenge. Then, the production of operational indicators that account for the reliability of the results is discussed. Concerning the reactivity, the addressed scientific challenges are the establishment of a vehicle indexes based sequential data assimilation process and the calibration of the model's internal conditions. Finally, concerning the versatility, the associated scientific question is the online calibration of the parameters of the traffic flow model. A model for tracking the errors,assumed to be distributed following Gaussian mixtures, is developped. The error tracking is achieved thanks to an original perturbation method designed for multi-modal Gaussian mixtures. A sensitivity analysis is performed in order to establish a link between the designed method's robustness and the discretization of the network, the number of modes in the Gaussian mixture and the errors on the flow model's parameters. The data assimilation process enables to propagate traffic conditions in accordance with the observed situation in case of non-calibrated demand and supply. The posterior state is calculated by means of a Bayesian inference formulation knowing the prior and observed states. Two methods for model update have been tested. Facing model inconsistencies introduced by the method of substituting \textit{prior} states by \textit{posterior} states, the update acts also on the vehicles by means of addition, deletion, advancing and delaying of the passing times. The validation of the proposed solutions is achieved on a network composed of a simple homogeneous link without discontinuity. When the parameters of the traffic flow models are not calibrated, the data assimilation alone is not able to propagate the traffic states in accordance with the observed situation. The calibration of the parameters is addressed in an opening chapter in which several research avenues are proposed to resolve this last scientific question. The works in this thesis pave the way to perspectives in both research and operational domains. Indeed, it is interesting to quantify the reinforcement brought by model centered methods to usual data centered methods for the real time estimation and the short term forecasting of traffic conditions. Furthermore, the developed methods, associated to the cited research avenues, may represent a significant intake in the daily traffic management tools
Ermolaev, Andrei. "Data-driven methods for analysing nonlinear propagation in optical fibres." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCD020.
Full textThis thesis aims to apply machine learning methods specifically tailored to the analysis and interpretation of optical pulses as they propagate in a single pass through an optical fiber, and under a variety of conditions. In particular, we will focus on data-driven model discovery approaches that involve the use of machine learning to analyze physical system data with the aim of discovering interpretable and generalizable models and developing methods that can substantially accomplish and/or complement conventional theoretical analysis. To this end, both supervised and unsupervised learning methods will be used to deepen understanding of ultrafast nonlinear phenomena in fiber optics systems
Lebrun, Dominique. "Inversion linéarisée de données sismiques à deux composantes." Montpellier 2, 1997. http://www.theses.fr/1997MON20055.
Full textEckert, Nicolas. "Couplage données historiques - modélisation numérique pour la prédétermination des avalanches : une approche bayésienne." Phd thesis, AgroParisTech, 2007. http://pastel.archives-ouvertes.fr/pastel-00003404.
Full textRifi, Mounir. "Etude théorique de la propagation des ondes électromagnétiques sur les lignes de transport d'énergie aériennes pour une application à un système de transmission de données." Lille 1, 1987. http://www.theses.fr/1987LIL10117.
Full textClément, François. "Une formulation en temps de parcours par migration pour la détermination des vitesses de propagation acoustique à partir de données sismiques bi-dimensionnelles." Paris 9, 1994. http://www.theses.fr/1994PA090033.
Full textThe aim of this thesis is the implantation of a method, wich consists in a migration-based traveltime formulation, allowing the automatic detremination of the velocities from 2D seismic data. This approach interprets itself as a duality method applied ti the usual minimisation problem of the least-square error between data and predicted measures. The three chapters of the first part deal with the construction of basic tools : finite differences numerical simulation of the acoustic wave equation, separation of the propagation and reflection effects by representation of the acoustic parameters on a multiscaled basis and quantitative migration through a preconditionning of the usual migration operator obtained via a gradient calculation. The four chapters of the second part deal with the time formulation itself : motivations and key ideas, description of the new forward model, computation and visualisation of the gradients of the new cost functionand results of the minimisation of this cost function. Numerical illustrations are obtained with synthetic data wich are computed from a model with a simple structure but with important lateral velocity variations. THe results of the inversion of these data are very satisfying as they are obtained by a local (Quasi-Newton-based) minimisation method from a very poor initial point (constant)
Trieu, Thanh Ngoan. "Open data and environment simulation : environmental and social simulation on distributed process systems based on irregular cell space." Electronic Thesis or Diss., Brest, 2024. http://www.theses.fr/2024BRES0047.
Full textThe combination of Cellular automata (CA) and distributed systems provide a simple way to model environmental and social issues by dividing the relevant areas into discrete spatial segments for parallel computation. The state evolution of each segment is divided into discrete time steps. Geographic divisions as irregular cell space give a chance to take advantage of Open Data in feeding the simulation systems. Data are analyzed to deduce the transition rules bringing distributed influences in a neighborhood. A case study of epidemic propagation modeling based on geographic divisions is presented. Given an assumption that the epidemic is spreading to people living in the neighborhood, a simulation system is generated based on adjacent neighbors with initial conditions collected from the government open data portal. A hybrid approach is introduced with the cooperation between regular tiles and irregular cellspaces in modeling shore activities. Environmental simulation is needed to represent ground and sea characteristics modeling spreading occurring on both spaces. These characteristics are very different due to soil capability and reaction, and sea behavior, in particular currents and tides. The problem of green tides is modeled when nutrients arepresented in high concentrations and entrapped by tidal currents
Fortin, Michelle. "Analyse de la propagation des erreurs spatiales induites par l'intégration de données multisources dans le modèle de vulnérabilité de la nappe d'eau souterraine DRASTIC." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0026/MQ31720.pdf.
Full textLabonne, Claire. "Analyse de la polarisation de données multi-composantes à partir d'une seule station ou d'une antenne : méthodes et applications à la caractérisation du champ d'ondes sismiques." Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4135/document.
Full textThe analysis of the seismic wavefield is an essential pre-requisite to the study of seismic wave propagation which in turns helps improving our understanding of the physical processes behind the sources and our knowledge of the propagation medium. The objective of this thesis is to further develop signal processing techniques to more fully exploit the information brought by the 3 component stations and arrays in order to characterize the seismic wavefield. The thesis work focuses on polarization analysis, its extension to 3-component arrays and its joint use with classical array processing. A review of the existing methods that attempt to extend array processing to the 3-components leads to the observation that these methods are complex and their use is limited. Therefore, two alternative methods that associate array processing and polarization sequentially are suggested. In order to best exploit the polarization analyses, a standardized parametrization system describing the polarization is developed and associated with a visualization solution regrouping all the parameters necessary for the interpretation on one figure. Finally, a polarization analysis performed on data from the LSBB 3-component array demonstrates the possibility to use spatial coherency to assist with the interpretation of seismograms
Houni, Karim. "Modélisation et étude de la transmission d'information par codes graphiques." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10002/document.
Full textGraphical Codes such as barcodes and 2D codes are a leading technology in identification and EDI. Displaying and reading these black and white pictograrns is equivalent to a singular digital communication system such that we drove our study according to information theory. From radiometry and optics principles, we've proposed a transmission channel model as a linear filter with Gaussian noise. Model parameters are thus function of code and camera characteristics, positioning and radiating power. System performances are evaluated with the computation of average mutual information (AMI). ln the 1D case (barcodes), AMI is estimated with a version of the BCJR Forward recursion by using channel markovianity. AMI is then an objective measure from which we define a theoretic depth of field and spatial resolution. These two criteria complement their geometrical equivalent by considering channel distortions and noise. ln the 2D case, we've shown that the model imply that the probability distribution of data knowing observations (a posteriori) is a Gibbs random field. We have thus highlighted that the evaluation of system's information rate is equivalent to the estimation of the random field free energy. The perspectives of the works are: adding colour to the codes, channel coding and the application of turbo principles
Guillet, Julien. "Caractérisation et modélisation spatio-temporelles du canal de propagation radioélectrique dans le contexte MIMO." Phd thesis, INSA de Rennes, 2004. http://tel.archives-ouvertes.fr/tel-00008011.
Full textSmittarello, Delphine. "Propagation des intrusions basaltiques. Modélisation analogique et suivi temporel par inversion des données de déplacements Combining InSAR and GNSS to Track Magma Transport at Basaltic Volcanoes Magma propagation at Piton de la Fournaise From Joint Inversion of InSAR and GNSS." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU033.
Full textWe study magma transport in the upper crust by propagation of a buoyancy-driven fluid-filled crack. Two schools of thought formalize the modelling of this phenomenon. They provide a framework to interpret either the geometrical aspects (shape, trajectory) when fluid viscosity is neglected, or the temporal aspect (flow velocity of the fluid) when, resistance to fracturation of the medium is neglected. We use two complementary approaches~: temporal in situ monitoring by inversion of displacement data and analogue modelling, in order to constrain both the geometry and the timing and to discriminate the field of application of each school of thought.We combine InSAR and GNSS data in an original inversion procedure, taking advantage of both the spatial coverage of InSAR and the temporal resolution of GNSS. The method is applied to study the complex propagation (changes of direction and velocity) that led to the eruption of 26 May 2016 at Piton de la Fournaise. This makes it possible to validate the method and provides new constraints on the supply and triggering of this eruption. In the laboratory, we are investigating the influence of fluid viscosity on the velocity and trajectory of a buoyancy-driven fluid-filled crack during ascent in the presence of a heterogeneous stress field. We used gelatine an analogue of elastic host-rock and we show that the addition of salt increases its resistance to fracture. We also show that the trajectory is the result of a competition between the internal pressure, the external stress field and the crack length. Finally, we highlight the influence of the properties of the medium, as well as those of the injected fluid on the propagation velocity and the velocity variations during ascent in the presence of a heterogeneous stress field
Huyghe, Jordan. "Exploitation du corpus de données expérimentales pour la puissance résiduelle des combustibles de réacteurs à eau pressurisée afin d'accroître la maîtrise des biais et incertitudes de calcul avec l'OCS DARWIN2.3." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0359.
Full textThe decay heat is a dimensioning parameter at every step of the back-end nuclear cycle, from the reactor shutdown until the final storage of non-recoverable radioactive waste. Accurate control of the calculation of the decay heat and its uncertainty is essential for all the Pressurized Water Reactors (PWRs) in the french reactor infrastructure : PWR-UOx and PWR-MOx fuels, over a wide range of cooling times. The calculation of the decay heat and its uncertainty is performed at CEA with the french reference DARWIN2.3 package. To answer the ASN's guide number 28 relative to the safety demonstration for the first barrier resistance, DARWIN2.3 follows a verification, validation & uncertainty quantification process, in order to prove the control of the decay heat calculation and the associated uncertainty. To define the latter, the propagation of nuclear data covariances to the decay heat or the transposition of the DARWIN2.3's experimental validation are possible. The approach considered for the thesis consisted in studying the representativity of experiments coming from the DARWIN2.3's experimental validation or the literature with PWR fuels. These studies enabled the definition of a 'validity domain' with DARWIN2.3 for the decay heat calculation of PWR-UOx and MOx fuels. Then, the thesis consisted in identifying the gaps in the DARWIN2.3 'validity domain' for the PWR-UOx and PWR-MOx fuels and in identifying the decay heat experiments to be carried out to fill these gaps
Vauzelle, Rodolphe. "Un modèle de diffraction en 3D dans le premier ellipsoi͏̈de de Fresnel." Poitiers, 1994. http://www.theses.fr/1994POIT2255.
Full textLavoué, François. "Inversion des formes d'ondes électromagnétiques en 2D pour le géoradar : vers une imagerie multi-paramètre à partir des données de surface." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU050/document.
Full textThe quantitative characterization of the shallow subsurface of the Earth is a critical issue for many environmental and societal challenges. Ground penetrating radar (GPR) is a geophysical method based on the propagation of electromagnetic waves for the prospection of the near subsurface. With central frequencies between 10~MHz and a few GHz, GPR covers a wide range of applications in geology, hydrology and civil engineering. GPR data are sensitive to variations in the electrical properties of the medium which can be related, for instance, to its water content and bring valuable information on hydrological processes. In this work, I develop a quantitative imaging method for the reconstruction of 2D distributions of permittivity and conductivity from GPR data acquired from the ground surface. The method makes use of the full waveform inversion technique (FWI), originating from seismic exploration, which exploits the entire recorded radargrams and has been proved successful in crosshole GPR applications.In a first time, I present the numerical forward modelling used to simulate the propagation of electromagnetic waves in 2D heterogeneous media and generate the synthetic GPR data that are compared to the recorded radargrams in the inversion process. A frequency-domain finite-difference algorithm originally developed in the visco-acoustic approximation is adapted to the electromagnetic problem in 2D via an acoustic-electromagnetic mathematical analogy.In a second time, the inversion scheme is formulated as a fully multiparameter optimization problem which is solved with the quasi-Newton L-BFGS algorithm. In this formulation, the effect of an approximate inverse Hessian is expected to mitigate the trade-off between the impact of permittivity and conductivity on the data. However, numerical tests on a synthetic benchmark of the literature display a large sensitivity of the method with respect to parameter scaling, showing the limits of the L-BFGS approximation. On a realistic subsurface benchmark with surface-to-surface configuration, it has been shown possible to ally parameter scaling and regularization to reconstruct 2D images of permittivity and conductivity without a priori assumptions.Finally, the imaging method is confronted to two real data sets. The consideration of laboratory-controlled data validates the proposed workflow for multiparameter imaging, as well as the accuracy of the numerical forward solutions. The application to on-ground GPR data acquired in a limestone massif is more challenging and necessitates a thorough investigation involving classical processing techniques and forward simulations. Starting permittivity models are derived from the velocity analysis of the direct arrivals and of the reflected events. The estimation of the source signature is performed together with an evaluation of an average conductivity value and of the unknown antenna height. In spite of this procedure, synthetic data do not reproduce the observed amplitudes, suggesting an effect of the radiation pattern of the shielded antennae. In preliminary tests, the inversion succeeds in fitting the data in the considered frequency range and can reconstruct reflectors from a smooth starting model
Musset, Sophie. "Accélération et propagation des particules énergétiques dans la couronne solaire : de l'analyse des données de l'instrument RHESSI à la préparation de l'exploitation de l'instrument STIX sur Solar Orbiter." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEO011/document.
Full textThe Sun is an active star and one manifestation of its activity is the production of solar flares. It is currently admitted that solar flares are caused by the release of magnetic energy during the process of magnetic reconnection in the solar upper atmosphere, the solar corona. During these flares, a large fraction of the magnetic energy is transferred to the acceleration of particles (electrons and ions). However, the details of particle acceleration during flares are still not completely understood.Several scenarios and models have been developed to explain particle acceleration. In some of them, electric fields, produced at the location of current sheets, which can be fragmented or collapsing, and which are preferentially located on quasi-separatrix layers (QSLs), are accelerating particles. To investigate a possible link between energetic particles and direct electric fields produced at current sheet locations, we looked for a correlation between X-ray emission from energetic electrons and electric currents which can be measured at the photospheric level. We used the Reuven Ramaty High Energy Solar Spectrometric Imager (RHESSI) data to produce spectra and images of the X-ray emissions during GOES X-class flares, and spectropolarimetric data from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) to calculate the vertical current densities from the reconstructed 3D vector magnetic field. A correlation between the coronal X-ray emissions (tracing the energetic electrons near the acceleration site) and the strong current ribbons at the photospheric level (tracing the coronal current sheet) was found in the five studied X-class flares. Moreover, thanks to the 12-minute time cadence of SDO/HMI, we could study for the first time the time evolution of electric currents: in several flares, a change in the current intensity, occurring during the flare peak, was found to be spatially correlated with X-ray emission sites. These observations enlighten a common evolution of both electric currents and X-ray emissions during the
Kueviakoe, Kangni. "Localisation multi-capteurs garantie : résolution d'un problème de satisfaction de contraintes." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112241/document.
Full textThis thesis deals with the vehicle locationand addresses the problem of SLAM (simultaneous localization and mapping). Several methods are used to solve this kind of problem. They can be classified into two broad categories of approaches: probabilistic approach and deterministic approaches. This work addresses the deterministic approaches and more precisely the approach based on interval analysis. The work has been conducted on real data sets collected in outdoor environments with proprioceptive and exteroceptive sensors.When multiple sensors providing complementary or redundant information are put into play, it is important to merge the data to improve the estimated pose. The approach detailed in this document uses the intervals methods and presents the localization problem as a constraint satisfaction problem.The resolution is done using a solver interval. Several solvers were compared. One thing is clear: local consistency algorithms do not address the uncertainty of the orientation. This thesis proposes a method of locating usable in real time applications and corrects the uncertainty in the heading of the vehicle. We compared our results with those of the extended Kalman filter (probabilistic reference method) and highlighted one of the interests of our method: the assurance of consistency of the pose (position and orientation of the mobile).This thesis proposes two contributions. The first is methodological. In the state of the art all works affirm the need (or obligation) to pre-decompose the constraints of the problem before the resolution step. Our work allows to prove otherwise. The second contribution relates to the reduction of the orientation uncertainty by combining constraint propagation and a bisection approach
Beaufils, Mickaël. "Fusion de données géoréférencées et développement de services interopérables pour l’estimation des besoins en eau à l’échelle des bassins versants." Thesis, Paris, CNAM, 2012. http://www.theses.fr/2012CNAM0847/document.
Full textNowadays, preservation of the environment is a main priority. Understanding of environmental phenomena requires the study and the combination of an increasing number of heterogeneous data. Several international initiatives (INSPIRE, GEOSS) aims to encourage the sharing and exchange of those data.In this thesis, the interest of making scientific models available on the web is discussed. The value of using applications based on geospatial data is demonstrated. Several methods and means that satisfy the requirements of interoperability are also purposed.Our approach is illustrated by the implementation of models for estimating agricultural and domestic water requirements. Those models can be used at different spatial scales and temporal granularities. A prototype based on a complete web service oriented architecture was developed. The tool is based on the OGC standards Web Feature Service (WFS), Sensor Observation Service (SOS) and Web Processing Service (WPS).Finally, taking into account the imperfections of the data is also discussed with the integration of methods for sensitivity analysis and uncertainty propagation
Hossaert-McKey, Martine. "Des fleurs comment et à quoi bon ? : Données et réflexions sur la reproduction sexuée de deux espèces pérennes affines, à propagation végétative, Lathyrus latifolius et Lathyrus sylvestris (légumineuses, papilionaceae)." Pau, 1988. http://www.theses.fr/1988PAUU3013.
Full textSabouri, Pouya. "Application of perturbation theory methods to nuclear data uncertainty propagation using the collision probability method." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI071/document.
Full textThis dissertation presents a comprehensive study of sensitivity/uncertainty analysis for reactor performance parameters (e.g. the k-effective) to the base nuclear data from which they are computed. The analysis starts at the fundamental step, the Evaluated Nuclear Data File and the uncertainties inherently associated with the data they contain, available in the form of variance/covariance matrices. We show that when a methodical and consistent computation of sensitivity is performed, conventional deterministic formalisms can be sufficient to propagate nuclear data uncertainties with the level of accuracy obtained by the most advanced tools, such as state-of-the-art Monte Carlo codes. By applying our developed methodology to three exercises proposed by the OECD (UACSA Benchmarks), we provide insights of the underlying physical phenomena associated with the used formalisms
Yu, Ting. "Modélisation de la propagation des ondes ultrasonores dans le béton pour l'amélioration du diagnostic des structures de génie civil." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0210/document.
Full textUltrasonic non-destructive testing (NDT) is used to characterize concrete, without degrading it, because of its relationship to its mechanical properties and composition. However, the measured signals resulting from successive diffusions and thus from multiple scattering are therefore complex to analyze. In order to optimize ultrasonic techniques, it is thus necessary to better understand the wave-material interactions in this type of medium and to better model the associated phenomena. In order to go beyond the limits of analytical homogenization models, in this thesis a two-dimensional numerical model describing the propagation of ultrasonic waves in a heterogeneous medium, adapted to concrete, is built in the SPECFEM2D software package. This model is compared to analytical models, and validated experimentally using a synthetic medium with high heterogeneity by comparing the two effective parameters of coherent waves: phase velocity and attenuation. This numerical model also makes it possible to take into account the viscoelasticity of the mortar by means of a quality factor. This quality factor is determined from measurements made for a series of mortars that we study. The complete set of numerical tools developed in this work can be used for several purposes: firstly, to carry out studies to evaluate the influence of certain parameters on wave propagation (the shape and distribution of aggregates), and secondly, the simulation of the measurement configurations implemented for a structure in order to optimize them in terms of the parameters involved, in particular the wave frequency. This better control of the measures will ultimately lead to better diagnosis