Дисертації з теми "Chair du numérique"
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Puig, Mailhol Vincent. "Le numérique et l'esprit. Prendre soin des technologies numériques de l'esprit à la lumière de Gilbert Simondon, Maurice Merleau-Ponty, Henri Bergson." Electronic Thesis or Diss., Poitiers, 2023. http://www.theses.fr/2023POIT5001.
Повний текст джерелаThis address to designers stems from an approach of anthropological decentering to think and take care of the digital as spiritual in the sense that Derrida designated the process of questioning but also the of technique in Heidegger. This route goes through a critique of the notion of information in Simondon to try to rethink "the soul of objects". It continues with an analysis of the question of the Flesh from Merleau-Ponty to propose the passage from a "digital suffering flesh" to an organology and a pharmacology of the digital gesture. Finally, it approaches what Bernard Stiegler called the technologies of the through the prism of Bergsonian intuition and Simondonian transduction to reintroduce analogical thought into the digital design of a dispositive benevolence, techno-estheú, cosmotechnic, ethical and political condiú)n for the development of the common good and of knowledge
Trabelsi, Brahim. "Simulation numérique de l’écoulement et mélange granulaires par des éléments discrets ellipsoïdaux." Phd thesis, Toulouse, INPT, 2013. http://oatao.univ-toulouse.fr/9300/1/trabelsi.pdf.
Повний текст джерелаGodineau, Kévin. "Optimisation du pilotage de chaînes opto-mécaniques pour l'exécution de trajectoires en fabrication additive par fusion laser sur lit de poudre." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN019.
Повний текст джерелаIn metal additive manufacturing by laser powder bed fusion, the geometry and mechanical characteristics of the produced parts are generated during the manufacturing process. These two aspects are greatly influenced by the laser spot trajectories, and by the control of the energy provided to the powder locally. The numerical control system, whose purpose is to generate instructions to be sent to actuators, has therefore a significant impact on the quality of the parts produced.This work proposes to study the local impact of the operations carried out in the numerical control on both the trajectories executed and the energy provided to the material. In the literature, few studies have addressed these aspects in additive manufacturing. For this reason, an experimental platform is implemented and used to analyze and better understand the operations currently implemented in industrial numerical controls.First, a mathematical model representative of the machine geometry is established. This model converts the laser spot trajectories into instructions for actuators. The model developed is used to improve the calibration step of the machines. Once the system is calibrated, the instructions sent to the actuators are studied. The various processes carried out in the industrial numerical control are analysed, limitations are highlighted and several proposals for improvements are implemented. All these developments are then used to precisely control the energy supplied to the material in the case of certain trajectories adapted to the process. The scientific developments proposed in these works are all validated experimentally on an additive manufacturing machine or on the test bench developed. The work carried out makes it possible to envisage many perspectives concerning the improvement of the treatments carried out inside the numerical control in additive manufacturing
Rivoire, Audrey. "Contributions au guillochage et à l'authentification de photographies." Phd thesis, Université Jean Monnet - Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00976616.
Повний текст джерелаOgier, Maxime. "Contributions à la chaine logistique numérique : conception de circuits courts et planification décentralisée." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00981923.
Повний текст джерелаDumas, Milne Edwards Léonard. "Conception de formes de relecture dans les chaînes éditoriales numériques." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2254/document.
Повний текст джерелаDocumentary production in a professional context often involves a revising process in which documents need to be proofread before validation and publication. This important task faces new challenges when dealing with digital documents. Indeed, three features of digital writing are problematic: documents evolve very frequently and cannot be proofread each time as a whole; interactions provided by hypertexts make the task laborious or even impossible; document repurposing increases the views of content to proofread. As an advanced digital writing technology, XML publishing chains are a relevant framework for studying proofreading of digital documents. Observing that the views of content proposed by publishing chains, namely the generative views (XML sources that can be modified through a WYSIWYM editor) and the published views (documents obtained by transformation of the XML sources), are not adapted for proofreading, we consider designing new views of content dedicated for this activity based on two approaches: linearization, which consists in restoring some material linearity among contents; and tabulation, which aims at parallelizing different repurposing contexts so that they can be better compared. Part of the contribution presented here has led to the development of prototypes that have been experimented in the use of Scenari publishing chains in a pedagogical context. These prototypes rely on linear proofreading views allowing in particular the comparison between two versions of the document based on a diff algorithm
Thirion, Anna. "La "tribune" de Saint-Michel-de-Cuxa (Pyrénées-Orientales, milieu XIIe siècle) : essai de restitution numérique au service d'une nouvelle approche historique, iconographique et liturgique." Thesis, Montpellier 3, 2015. http://www.theses.fr/2015MON30084.
Повний текст джерелаIn the middle of the twelfth century, the abbatial church of Saint-Michel-de-Cuxa was endowed with a ''tribune'', a deep choir screen built on two bays. Dismantled in the sixteenth century this ''tribune'' is only known today by its 180 pink marble sculptures scattered throughout France and abroad. Since its discovery in the 1950’s, several attempts have been made to reconstruct this liturgical nonpareil of architecture. Their results differ on several points : the inventory, the location of the construction in the nave of the abbey church, the shapes of the structure and the positioning of the sculptures themselves.The stones preserved, numerous and varied in nature, are sufficient to allow a 3D reconstruction in the form of a digital anastylosis. From the Greek word, anastellein, “to rebuild,” this study appoints an attempt to digitally reconstruct the disappeared monument from its remaining elements. With no contemporaneous descriptions or representations that of the tribune and lacking precise textual and iconographic evidence, it is the careful analysis of the stones themselves that allow the formulation of a new hypotheses. Through this research, a new methodology for the study of the scattered fragments issued from the dismantled structure has been developed and tested for the purpose of their anastylosis. Every stone attributed to the ancient ''tribune'' has been digitized and integrated in the proposition of a 3D reconstruction.The latter has brought a better understanding of the sculpted set and its architecture, renewing discussions on the structure's artistic, liturgical and historical aspects. Thus bringing clarity to its iconography, functions, dating and context of commissioning
Belharet, Mokrane. "Modélisation numérique du transfert du radiocésium dans les chaines trophiques pélagiques marines suite à l'accident nucléaire de Fukushima Dai-ichi (côte Pacifique du Japon)." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30339/document.
Повний текст джерелаHuge amounts of radionuclides, espicially 137Cs, were released to the coastal northwestern Pacific ocean after the Fukushima nuclear power plant accident, that occurred on 11 March 2011. The resultant radiocesium contamination was quickly transferred to marine biota resulting in elevated cesium levels in various organisms. Using a modelling approach, this work aims to study the 137Cs transfer to the marine pelagic food chains, from plankton populations to the large piscivorous fishes. Coupling the radioecological model, developed in this study, with an ecosystem model comprising an NPZD biogeochemical model and a regional ocean circulation model, is appeared to be the most adapted tool for modelling of plankton populations contamination in this accidental situation. The results of this study showed high contamination levels in the plankton populations, especially in the vincity of the power plant, where the maximal concentrations are estimated to be about 4 orders of magnitude higher than those observed before the accident. In spite of these high contamination levels, the maximum 137Cs absorbed dose rates for phyto- and zooplankton populations were estimated to be well below the 10 Gy/h benchmark value, from which a measurable effect on the marine biota can be observed. This study has also highlighted the predominance of the cesium uptake from food and the presence of biomagnification potential at this trophic level. The radioecological model developed to study the nektonic species contamination is based on the individual size. In this approach, each species is represented by a set of cohorts. The number of these cohorts is a function of the species life span and reproduction frequency. Unlike traditional approaches, the organism ingestion rate and diet composition considered in this modelling approach are not constant, but vary over the time according to the size of the organism. The model results are in general satisfactory, and the validation is carried out in both equilibrium and accidental situations. This study highlighted the importance of the organism migratory movements in the radioecological modelling espicially in the accident situations caracterized by a very high spatial variability of radionuclides concentrations in the seawater. The detailed caracteristics of 137Cs concentration dynamics in the different species are discussed. The contamination levels estimated for the different species are significantly higher than those observed before the accident, with a clear tendency to increase with individual size
Abderamane, Hamit. "Étude du fonctionnement hydrogéochimique du système aquifère du Chari Baguirmi (République du Tchad)." Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2294/document.
Повний текст джерелаThe study of the Chari Baguirmi aquifer system aims to improve the knowledge about this system forsustainable groundwater resource management. In the study area, which covers 70,000 km2, measurementcampaigns and sampling of water and sediments were undertaken. The waters have been sampled for chemicaland isotopic analyzes (18O and 2H) to understand the hydrogeochemical behavior of the aquifer system.The synthesis of existing geological data and highlighting the litho-stratigraphic heterogeneity through thegranulometric study confirmed the hydrogeological complexity of the study area. Clay mineralogy showed thatthe deposition of different sediments occurred from the periphery to the center of the depression. This mode ofsedimentation can hypothesize the existence of a depression into which sediments are trained by the transportagent. This assumption of "structural depression" refutes the hypothesis of a hitherto accepted hydrogeologicalorigin (high evaporation) of the piezometric depression. The study based on the piezometry and chemical and isotopic data (18O and 2H) of water enabled to understand the hydrogeochemical processes that govern the mineralization of the water. In addition to isotopes (2H and 18O), the use of ratios Br/Cl, Sr/Ca and base exchanges index has highlighted on the one hand, the origin of the salinity of waters in the piezometric depression and secondly, the phenomena of base exchanges related to longresidence time of water in contact with rocks and areas of potential groundwater recharge. Numerical modeling of the aquifer was performed in steady state and the results confirm the prevalence of the phenomenon of evaporation in the western p
Garcia-Neveu, Fabienne. "Le rôle des projets de systèmes d'information inter-organisationtionnels dans l'intégration et la collaboration de la supply chain : le cas des portails fournisseurs." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0118.
Повний текст джерелаFaced with increasingly complex and globalized Supply Chains (SC), organizations rely on industry 4.0 technologies to support these challenges. Inter-organizational information systems (IOIS), which enable SC integration with information sharing and better collaboration between the various partners, are evolving according to these new technologies in order to improve SC performance. Thus, alongside Electronic Data Interchange (EDI), which concerns a majority of existing research, more collaborative IOIS, better adapted to networked SC, have been introduced. Often available with a cloud computing technology, they can be developed as an industry standard. In this thesis, we focus on the procurement process in the SC and chose to study supplier portals. The adoption of these portals in a SC has often encountered difficulties or even failed, sometimes turning an ambitious industry standard project into a poorly used tool. Indeed, the adoption and implementation of such portals raises issues about system interoperability, process coordination and collaboration among the various partners. Thus, addressing these issues through a multi-level analysis, we raise our research question: how does the implementation of a supplier portal in a SC affect the SC integration and collaboration capabilities? Our methodological approach is based on two longitudinal case studies taking into account the duration of the project. The first case, exploratory in nature, identifies two types of facilitating mechanisms - technological and relational - which, when combined, create an integration-collaboration dynamic between a customer and its suppliers during the implementation of a specific portal. The second case, explanatory in nature, is related to the supplier portal of the European aerospace industry. It presents three levels of analysis (organisational, interorganisational, industry) combining 14 mechanisms which can explain the adoption of an industry portal. Thus, our research makes it possible to characterize the ecosystem favorable to the adoption and success of a supplier portal project, enhancing the SC integration and collaboration capabilities
Bendjebla, Soumiya. "Traitements géométriques et fouille de données pour la reconnaissance d’entités d’usinage complexes." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASN002.
Повний текст джерелаIn response to competition and new industrial challenges, companies are forced to be more and more efficient, productive and competitive. Managing industrial know-how and the data flow of the manufacturing digital chain must be explored in order to shorten the industrialisation time while ensuring better quality.In this context, this thesis focuses on digital chain data exploration for the capture of good practices in NC machining using a feature-based approach. Several issues related to machining feature characterisation and digital chain data exploitation for machining process knowledge reuse have been identified.To address these issues, a new characterization of multi-level complex machining feature has been proposed. The proposed approach is characterized by a hierarchical structuring of digital chain data and a mapping between the geometrical and machining data. A statistical analysis is then carried out to analyse and exploit this data. Curvature-based segmentation and statistical clustering of machining data were combined to define new machining regions based technological segmentation approach. These regions were then used to characterize the machining feature and thus ensure the reuse of machining data through a feature based and a region based approach exploiting similarity measures a similarity measure. Finally, the developed approach was applied on an industrial case in aeronautics
Puengnim, Anchalee. "Classification de modulations linéaires et non-linéaires à l'aide de méthodes bayésiennes." Toulouse, INPT, 2008. http://ethesis.inp-toulouse.fr/archive/00000676/.
Повний текст джерелаThis thesis studies classification of digital linear and nonlinear modulations using Bayesian methods. Modulation recognition consists of identifying, at the receiver, the type of modulation signals used by the transmitter. It is important in many communication scenarios, for example, to secure transmissions by detecting unauthorized users, or to determine which transmitter interferes the others. The received signal is generally affected by a number of impairments. We propose several classification methods that can mitigate the effects related to imperfections in transmission channels. More specifically, we study three techniques to estimate the posterior probabilities of the received signals conditionally to each modulation
Lyu, Fen. "The path of the adoption of digital technology to SMEs’ business performance : evidence from China." Thesis, Paris 1, 2020. http://www.theses.fr/2020PA01E070.
Повний текст джерелаImpressive developments in digital technology such as big data, virtual reality, cloud computing and artificial intelligence have been continually and thoroughly penetrating various fields, which have reshaped innovation landscape by accelerating growth of internet of everything, data-driven computation, platform support and intelligence industry. The mushrooming of digital technology is accelerating the integration with the real economy, driving the digital innovation to expand with full extent. Small and medium enterprises (SMEs) are the basic units to promote employment, economic development and innovative activities. They are the largest and most dynamic parts in the market economy and thus digital innovation is central to the survival and growth of Chinese SMEs. Therefore, a clear understanding both of processes by which SMEs develop digital innovation and the benefits which flow from digital innovation in terms of market share and profit level is important. This thesis demonstrates the use of a conceptual framework, the digital innovation value chain (DIVC), and shows how the DIVC approach helps to understand the process in digital innovation for SMEs. The value of the DIVC is expressed in showing the key interrelationships in the process of digital innovation from adoption of digital technology (ADT) through digital innovation to business performance in terms of the market share and profit level. This research empirically showed that the ADT can have a positive influence on both business networks and personal networks for SMEs. Furthermore, the results indicated that heterogeneous networks including business networks and personal networks afforded by ADT allows SMEs to continuously deal with digital innovation activities. We extend existing knowledge about innovation value chain by empirically illustrating the importance of digital technology with respect to digital innovation activities, in particular for digital products innovation, digital service innovation and business model innovation , which has indirect influence on SMEs’ business performance. A key benefit of the DIVC approach is therefore its ability to emphasize the roles of different factors at various chain of the digital source-digital innovation-SMEs’ business performance nexus, and to show their indirect and direct impact. This research provides a contribution in the area of digital innovation aimed at categorizing dimensions of digital innovation by suggesting that digital innovation involve digital products innovation, digital service innovation and business model innovation according to review on previous studies of innovation. It extends existing knowledge about innovation value chain by empirically illustrating the importance of digital technology with respect to digital innovation activities, in particular for digital products innovation, digital service innovation and business model innovation. This research also corresponds with the need to make today’s digital innovation more fluid, thereby facilitating the diversity and flexibility of DIVC with regard to dynamic and boundless environment
Daval, Vincent. "Chaine 3D interactive." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS068/document.
Повний текст джерелаWith constant evolution of technology, 3D scanners are providing more and more data with ever greater precision. However, the substantial increase of the data size is problematic. Files become very heavy and can cause problems in data transmission or data storage. Therefore, most of the time, the data obtained by the 3d scanners will be analyzed, processed and simplify; this is called 3D acquisition chain.This manuscript presents an approach which digitize objects dynamically by adapting point density during the acquisition depending on the object complexity, without informations on object shape. This system allows to avoid the use of the classic 3D chain. This system do not calculate a dense points cloud which will be simplify later, but it adapts the points density during the acquisition in order to obtain directly simplified data to the acquisition output. This process allows to reduce significantly processing time
Senegas, Julien. "Méthodes de Monte Carlo en Vision Stéréoscopique." Phd thesis, École Nationale Supérieure des Mines de Paris, 2002. http://tel.archives-ouvertes.fr/tel-00005637.
Повний текст джерелаAfin d'aborder ce problème, nous proposons un cadre bayésien et l'application de méthodes de Monte Carlo par chaînes de Markov. Celles-ci consistent à simuler la distribution conditionnelle du champ de disparité connaissant le couple stéréoscopique et permettent de déterminer les zones où des erreurs importantes peuvent apparaitre avec une probabilité éventuellement faible. Différents modèles stochastiques sont comparés et testés a partir de scènes stéréoscopiques SPOT, et nous donnons quelques pistes pour étendre ces modèles à d'autres types d'images. Nous nous intéressons également au probleme de l'estimation des paramètres de ces modèles et proposons un certain nombre d'algorithmes permettant une estimation automatique. Enfin, une part importante du travail est consacrée à l'étude d'algorithmes de simulation reposant sur la théorie des chaînes de Markov. L'apport essentiel réside dans l'extension de l'algorithme de Metropolis-Hastings dans une perspective multi-dimensionnelle. Une application performante reposant sur l'utilisation de la loi gaussienne est donnée. De plus, nous montrons comment le recours à des techniques d'échantillonnage d'importance permet de diminuer efficacement le temps de calcul.
Roumieh, Nour. "Confiance, réputation et manipulation : une perspective théorique et empirique appliquée au cas de eBay." Thesis, Paris 2, 2019. http://www.theses.fr/2019PA020065.
Повний текст джерелаTrust concept stands out as highly polysemic in social science. The crucial role of trust extends across many different disciplines, including sociology, philosophy, psychology and economy. This "six chapters" thesis treats the question of establishing trust between buyers and sellers while completing online purchase. Seller reputation is the main determinant of trust. Empirical and theoretical studies are based on the eBay's online rating system. The six chapters are preceded by a general introduction and a literature review (Chapter one). The second chapter examines the impact of feedback - particularly negative feedbacks - left from a buyer to a specific seller on staying or running out the market using Markov Chain. Chapter three provided a formula that depends on rating to optimize the number of items being sold over a certain period of time for a specific seller through stochastic processes. Chapter four is an empirical study of the effect of seller reputation on sales and trust. The fifth chapter presents the challenges faced by rating systems, and proposed solutions. This chapter highlights the concept of manipulation. Chapter six is an empirical study of the effect of rating manipulation on sales and trust
Nguyen, Nho Gia Hien. "The role of the microstructure in granular material instability." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI062/document.
Повний текст джерелаGranular materials consist of dense pack of solid grains and a pore-filling element such as a fluid or a solid matrix. The grains interact via elastic repulsion, friction, adhesion and other surface forces. External loading leads to grain deformations as well as cooperative particle rearrangements. The particle deformations are of particular importance in many industry applications and research subjects, such as powder metallurgy and soil mechanics. The response of granular materials to external loading is complex, especially in case when failure occurs: the mode of the failure can be diffuse or localized, and the development of specimen pattern can be drastically different when the specimen can no longer sustain external loading. In this thesis, a thorough numerical analysis based on a discrete element method is carried out to investigate the macroscopic and microscopic behavior of granular materials when a failure occurs. The numerical simulations include the vanishing of the second-order work instability criterion to detect failure. Furthermore, it is proved that the vanishing of second-order work coincides with the change from a quasi-static regime to a dynamic regime in the response of the specimen. Then, microstructure evolution is investigated. Evolution of force-chains and grain-loops are investigated during the deformation process until reaching the failure. The second-order work is once again taken into account to elucidate the local aspect that governs the failure, taking place at the particle scale. The collapse of the discrete specimen when it turns from quasi-static to dynamic regime is accompanied with a burst in kinetic energy. This rise of kinetic energy occurs when the internal stress cannot balance with the external loading when a small perturbation is added to the boundary, resulting in a difference between the internal and external second-order works of the system. The mesostructures have a symbiosis relationship with each other and their evolution decides the macroscopic behavior of the discrete system. The distribution of the collapse of force-chain correlates with the vanishing of the second-order work at the grain scale. The mesostructures play an important role in the instability of granular media. The second-order work can be used as an effective criterion to detect the instability of the system on both the macroscale and microscale (grain scale)
Laranjeira, Moreira Matheus. "Visual servoing on deformable objects : an application to tether shape control." Electronic Thesis or Diss., Toulon, 2019. http://www.theses.fr/2019TOUL0007.
Повний текст джерелаThis thesis addresses the problem of tether shape contrai for small remotely operated underwater vehicles (mini-ROVs), which are suitable, thanks to their small size and high maneuverability, for the exploration of shallow waters and cluttered spaces. The management of the tether is, however, a hard task, since these robots do not have enough propulsion power to counterbalance the drag forces acting on the tether cable. ln order to cape with this problem, we introduced the concept of a Chain of miniROVs, where several robots are linked to the tether cable and can, together, manage the external perturbations and contrai the shape of the cable. We investigated the use of the embedded cameras to regulate the shape of a portion of tether linking two successive robots, a leader and a follower. Only the follower robot deals with the tether shape regulation task. The leader is released to explore its surroundings. The tether linking bath robots is assumed to be negatively buoyant and is modeled by a catenary. The tether shape parameters are estimated in real-time by a nonlinear optimization procedure that fits the catenary model to the tether detected points in the image. The shape parameter regulation is thus achieved through a catenary-based contrai scheme relating the robot motion with the tether shape variation. The proposed visual servoing contrai scheme has proved to properly manage the tether shape in simulations and real experiments in pool
M'Saad, Soumaya. "Détection de changement de comportement de vie chez la personne âgée par images de profondeur." Thesis, Rennes 1, 2022. http://www.theses.fr/2022REN1S039.
Повний текст джерелаThe number of elderly people in the world is constantly increasing, hence the challenge of helping them to continue to live at home and ageing in good health. This PhD takes part in this public health issue and proposes the detection of the person behavior change based on the recording of activities in the home by low-cost depth sensors that guarantee anonymity and that operate autonomously day and night. After an initial study combining image classification by machine learning approaches, a method based on Resnet-18 deep neural networks was proposed for fall and posture position detection. This approach gave good results with a global accuracy of 93.44% and a global sensitivity of 93.24%. The detection of postures makes possible to follow the state of the person and in particular the behavior changes which are assumed to be the routine loss. Two strategies were deployed to monitor the routine. The first one examines the succession of activities in the day by computing an edit distance or a dynamic deformation of the day, the other one consists in classifying the day into routine and non-routine by combining supervised (k-means and k-modes), unsupervised (Random Forest) or a priori knowledge about the person's routine. These strategies were evaluated both on real data recorded in EHPAD in two frail people and on simulated data created to fill the lack of real data. They have shown the possibility to detect different behavioral change scenarios (abrupt, progressive, recurrent) and prove that depth sensors can be used in EHPAD or in the home of an elderly person
Yahiaoui, Meriem. "Modèles statistiques avancés pour la segmentation non supervisée des images dégradées de l'iris." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLL006/document.
Повний текст джерелаIris is considered as one of the most robust and efficient modalities in biometrics because of its low error rates. These performances were observed in controlled situations, which impose constraints during the acquisition in order to have good quality images. The renouncement of these constraints, at least partially, implies degradations in the quality of the acquired images and it is therefore a degradation of these systems’ performances. One of the main proposed solutions in the literature to take into account these limits is to propose a robust approach for iris segmentation. The main objective of this thesis is to propose original methods for the segmentation of degraded images of the iris. Markov chains have been well solicited to solve image segmentation problems. In this context, a feasibility study of unsupervised segmentation into regions of degraded iris images by Markov chains was performed. Different image transformations and different segmentation methods for parameters initialization have been studied and compared. Optimal modeling has been inserted in iris recognition system (with grayscale images) to produce a comparison with the existing methods. Finally, an extension of the modeling based on the hidden Markov chains has been developed in order to realize an unsupervised segmentation of the iris images acquired in visible light
Lafaye, de Micheaux Téo. "Modélisation des écoulements d’air et des transferts de chaleur dans un camion frigorifique : Etude des performances d’un dispositif de rideau d’air innovant pour le maintien de la chaîne du froid et la réduction des pertes à l’ouverture des portes." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI057.
Повний текст джерелаCold chain safety is a key parameter for urban distribution where the frequent door-opening induces a heat infiltration. In order to reduce heat and mass transfer, air curtain have recently been installed to protect the doorway of refrigerated truck. The aim of this work is to study this type of door insulation. Two CFD numerical models were developed to simulate the temperature and velocity fields in a closed refrigerated truck. These models showed that modifying the blowing velocity does not modify the air flow structure inside the cavity. Different air chutes were modelled. Numerical results demonstrate that the configuration with a convergent and an open duct strongly improves the air renewal. A numerical investigation was performed in order to study heat and mass infiltration rates during the opening. The infiltration flow rate is well predicted by the CFD model, except at the transition between both flow regimes. An experimental truck was equipped with an air curtain setup, composed by an ambient air jet, a cold air jet or a double jet. In parallel, a numerical CFD model was developed to study the influence of various parameters. Experimental and numerical results were found to be in good agreement. The maximum efficiency of the ambient air curtain is reached when the impact point of the jet occurs in the door plane at the ground level. This configuration is only relevant for short opening times. The double air curtain efficiently maintains the temperature homogeneity for short openings. The cold air curtain is the best configuration which strongly limits the temperature increase during the opening and allows important energy savings
Gosselin, Frédéric. "Modèles stochastiques d'extinction de population : propriétés mathématiques et leurs applications." Paris 6, 1997. http://www.theses.fr/1997PA066358.
Повний текст джерелаOulad, Ameziane Mehdi. "Amélioration de l'exploration de l'espace d'état dans les méthodes de Monte Carlo séquentielles pour le suivi visuel." Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0007.
Повний текст джерелаIn computer vision applications, visual tracking is an important and a fundamental task. Solving the tracking problematic based on a statistical formulation in the Bayesian framework has gained great interest in recent years due to the capabilities of the sequential Monte Carlo (SMC) methods to adapt to various tracking schemes and to take into account model uncertainties. In practice, the efficiency of SMC methods strongly depends on the proposal density used to explore the state space, thus the choice of the proposal is essential. In the thesis, our approach to efficiently explore the state space aims to derive a close approximation of the optimal proposal. The proposed near optimal proposal relies on an approximation of the likelihood using a new form of likelihood based on soft detection information which is more trustworthy and requires less calculations than the usual likelihood. In comparison with previous works, our near optimal proposal offers a good compromise between computational complexity and optimality.Improving the exploration of the state space is most required in two visual tracking applications: abrupt motion tracking and multiple object tracking. In the thesis, we focus on the ability of the near optimal SMC methods to deal with abrupt motion situations and we compare them to the state-of-the-art methods proposed in the literature for these situations. Also, we extend the near optimal proposal to multiple object tracking scenarios and show the benefit of using the near optimal SMC algorithms for these scenarios. Moreover, we implemented the Local PF which partition large state spaces into separate smaller subspaces while modelling interactions
Helali, Amine. "Vitesse de convergence de l'échantillonneur de Gibbs appliqué à des modèles de la physique statistique." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0002/document.
Повний текст джерелаMonte Carlo Markov chain methods MCMC are mathematical tools used to simulate probability measures π defined on state spaces of high dimensions. The speed of convergence of this Markov chain X to its invariant state π is a natural question to study in this context.To measure the convergence rate of a Markov chain we use the total variation distance. It is well known that the convergence rate of a reversible Markov chain depends on its second largest eigenvalue in absolute value denoted by β!. An important part in the estimation of β! is the estimation of the second largest eigenvalue which is denoted by β1.Diaconis and Stroock (1991) introduced a method based on Poincaré inequality to obtain a bound for β1 for general finite state reversible Markov chains.In this thesis we use the Chen and Shiu approach to study the case of the Gibbs sampler for the 1−D Ising model with three and more states which is also called Potts model. Then, we generalize the result of Shiu and Chen (2015) to the case of the 2−D Ising model with two states.The results we obtain improve the ones obtained by Ingrassia (1994). Then, we introduce some method to disrupt the Gibbs sampler in order to improve its convergence rate to equilibrium
Sodjo, Jessica. "Modèle bayésien non paramétrique pour la segmentation jointe d'un ensemble d'images avec des classes partagées." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0152/document.
Повний текст джерелаThis work concerns the joint segmentation of a set images in a Bayesian framework. The proposed model combines the hierarchical Dirichlet process (HDP) and the Potts random field. Hence, for a set of images, each is divided into homogeneous regions and similar regions between images are grouped into classes. On the one hand, thanks to the HDP, it is not necessary to define a priori the number of regions per image and the number of classes, common or not.On the other hand, the Potts field ensures a spatial consistency. The arising a priori and a posteriori distributions are complex and makes it impossible to compute analytically estimators. A Gibbs algorithm is then proposed to generate samples of the distribution a posteriori. Moreover,a generalized Swendsen-Wang algorithm is developed for a better exploration of the a posteriori distribution. Finally, a sequential Monte Carlo sampler is defined for the estimation of the hyperparameters of the model.These methods have been evaluated on toy examples and natural images. The choice of the best partition is done by minimization of a numbering free criterion. The performance are assessed by metrics well-known in statistics but unused in image segmentation
Paul, Dominique. "Entre chair et lumière : actualité de la photographie." Thèse, 2008. http://www.archipel.uqam.ca/2461/1/D1837.pdf.
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