Дисертації з теми "Diagnostic – Simulation par ordinateur"
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Girard, Patrick. "Diagnostic de pannes temporelles dans les circuits digitaux." Montpellier 2, 1992. http://www.theses.fr/1992MON20053.
Повний текст джерелаMaalej, Mohamed-Amine, and Véronique Delcroix. "Diagnostic multiple des systèmes complexes à base de réseaux bayésiens." Valenciennes, 2006. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/46028b3e-dbca-41c6-a69f-b740ee4d0519.
Повний текст джерелаModel Based Diagnosis approach revolutionizes the field of the diagnosis as overcoming the lack of knowledge by using Model. Our research focuses on the task of multiple diagnosis, from failure observations, for complex and highly-reliable large systems. We take the advantages of the Bayesian networks models to improve the diagnosis of this type of systems. These models integrate the components failures prior probabilities, and allow estimating posterior probabilities of diagnoses, by an approached calculation. We present a methodology of diagnosis using Bayesian network. Our approach integrates a model design method, in addition to two diagnosis algorithms : the first algorithm allows calculating the most probable diagnoses for a failing system; the second provides quickly representatives of the diagnosis classes, it reveals also the cases while additional observations are necessary. Finally we test these algorithms in terms of computing time and results quality for digital circuits of various sizes
Diallo, Ibrahima. "Etude physique de la détection pour la tomographie de transmission avec simulateur-scanneur : mise en oeuvre d'une barrette d'oxysulfure de gadolinium." Toulouse 3, 1995. http://www.theses.fr/1995TOU30202.
Повний текст джерелаValla, Anthony. "Une méthodologie de diagnostic de la performance d'une chaîne logistique." Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0070/these.pdf.
Повний текст джерелаThe importance of supply chain management has gre ally lncreased lately in the se arch for company performance. The analysis of su chextended systems, of the ir various types of flows and of the in coordination has been studied by several modelling approaches in the field of lndustrial Engineering. None of them seems suitable to supply chain context, taking account of: several views, dynamic and stochastic characteristics, combined global and detailed models. Our contribution consists in proposing a methodology for supply chain performance diagnostic supported by generic decision support tools and easily usable by actors. Lt is a four-step methodology. The first step aims at precisely defining the sequence and the positioning of the methodology within the company. The goal of the second step is modelling supply chain processes. Thirdly, the functioning analysis step deals with a complete analysis of every process in order to identify malfunctionings which penalise supply chain performance. Lastly, the optimisation step leads to the implementation of improvement actions. The methodology supported by ARIS and ARENA, was experimented on an industrial case with Company Valrhona
Grondin, Olivier. "Modélisation du moteur à allumage par compression dans la perspective du contrôle et du diagnostic." Rouen, 2004. http://www.theses.fr/2004ROUES054.
Повний текст джерелаThis thesis has described an investigation into the modelling of compression ignition engine for control and diagnosis purpose. The Diesel engine is the most efficient and clean internal combustion engine due to modern electromechanical actuators. However, pollutant emission regulations are much more stricter, thus, these complex systems need sophisticated and efficient control algorithms to reach very low emission levels. For this task, engine models are required at each step of the control system development : control laws synthesis, simulation and validation. The system under study is a six cylinder direct injection Diesel engine fitted with a turbocharger. The model of this system is based on physical laws for some parts of the engine such as cylinders, manifolds, turbocharger and crank-slider system. In order to reduce computing time we choose to model heat transfer and heat release during combustion using simple empirical correlations. Resulting model has been implemented in the Matlab-Simulink environment and it can predict variables of interest for control purpose with one degree crank angle resolution. The model has been tested numerically and compared with an industrial engine simulation code with good results. Moreover, model output variables are in good agreement with experimental data recorded on a heavy-duty research engine. The engine model has been embedded on a board providing enough computing performances to perform real-time simulations, this will be helpful for “hardware-in-the-loop” simulations. Another part of this study is dedicated to the combustion process modelling using a non linear phenomenological model : the NARMAX model. The goal is to predict the in-cylinder pressure evolution using other measurements available on the engine. The NARMAX model parameters have been identified using input-output data carried out from the experimental engine. Such model is well suited for real-time applications compare to numerically cost effective physical models. First results are promising and demonstrate that non linear “black-box” models can be employed to model the combustion process with the crankshaft speed as main model input
Mama, Daouda. "Méthodologie et résultats du diagnostic de l'eutrophisation du lac Nokoué (Bénin)." Limoges, 2010. https://aurore.unilim.fr/theses/nxfile/default/c873af12-66c0-4338-85b4-2f73c2c6e45e/blobholder:0/2010LIMO4015.pdf.
Повний текст джерелаThis thesis focuses on the methodology and results of the diagnosis of eutrophication of Nokoue lake in Benin (West Africa). It dealt mainly with the question of water hyacinth infest. The problem of water hyacinth, a consequence of eutrophication and the need for a systemic approach by computer modeling have been reported. The chemical quality of water and sediment were monitored for two years (2006 and 2007). The results confirmed eutrophic status of Nokoue lake and showed the water quality changes with seasons. The production of water hyacinth is regulated by salinity with a threshold of growth lower than in temperate zone (10 ‰ for Nokoue against 15 ‰ in temperate zone). The model results show that nutrient inputs are mainly from the Sô River (97% N 89% P). Salinity has a dominant effect on the integrated index of water hyacinth growth (SII) in all followed stations
Gil, Marion. "Rétrodiffusion lumineuse pour le diagnostic précoce et le suivi de pathologies du stroma cornéen : étude expérimentale ex vivo et modélisation." Thesis, Aix-Marseille, 2019. http://theses.univ-amu.fr.lama.univ-amu.fr/190521_GIL_362fb71obz103p970n_TH.pdf.
Повний текст джерелаOne of the main functions of the cornea is to allow light to enter the eye. This characteristic is especially related to a very particular organization of its volume at the nanometric scale. This makes it possible to minimize light scattering. The apparition of certain pathologies will induce an increase of this scattering. As scattering can be directly linked to structural modification of the tissue at different scales, the objective of this thesis work is to show how the study of angular scattering provides a way to characterize the condition of the cornea. This is based on both experimental results and numerical simulations. This information leads to diverse applications including monitoring of the growth of edema, sorting corneal grafts and testing the efficiency of drugs. An early diagnosis tool for corneal pathologies is also proposed giving a quantification of the rate of tissue disorganization at the nanoscale
Devanneaux, Vincent. "Modélisation des machines asynchrones triphasées à cage d'écureuil en vue de la surveillance et du diagnostic." Toulouse, INPT, 2002. http://www.theses.fr/2002INPT038H.
Повний текст джерелаAfnouch, Marwa. "Machine Learning Applications in Medical Diagnosis, case study : bone metastasis." Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0039.
Повний текст джерелаMetastases are a group of abnormal cells that develop outside the original organ bound aries and spread to other organs. In particular, bone metastases originate in one organ of the body, such as the breast, lung, or prostate, and spread to the bone. Although this disease was discovered more than a century ago, it is still not well defined, and exist ing treatments are weakly effective, possibly because it is difficult and time-consuming to detect. To help physicians, new machine learning technologies promise to improve overall accuracy. This dissertation aims to help radiologists routinely detect bone metas tases using machine learning algorithms. The discovery of methodological biases in studies of bone metastasis diagnosis and the lack of consensus on the interpretability of machine learning have shifted the focus of this dissertation. It now focuses primarily on data collection and overcoming the challenges of validation and interpretability of machine learning. In order to properly assess the ability of machine learning to detect bone metastases, three experimental studies were conducted. The first proposing a novel segmentation approach supported by an attention mechanism to localize bone lesions. The second is a study of machine learning methods for identifying bone metastases cases. Finally, the last study highlights the lack of robustness of classification using machine learning methods and proposes a method to improve accuracy based on both CNN and Transformer approaches. The experimental results of this dissertation are evaluated on our introduced BM-Seg dataset, which is the first benchmark dataset for bone metasta sis segmentation and classification using CT-scans. This novel open-source dataset was used to improve the reproducibility of machine learning experiments. The results of the various preliminary studies are encouraging and promising
Vela, Valdes Luis Gerardo. "Etude et élaboration d'une approche fonctionnelle pour la localisation de défauts en diagnostic : application à la simulation d'un moteur à courant continu." Nancy 1, 1998. http://www.theses.fr/1998NAN10221.
Повний текст джерелаThe work presented in this thesis deals with the development of a functional approach in the fault diagnostic field. This approach is based on the classIfication of knowledge about the system in order to detect and isolate faults with respect to the principal characteristics in the behavior of the system. The objective of this work is to end at a best knowledge specification and utilization of abilities and tools in order to increase the quantity of isolated faults. The functional approach in diagnostic is based on the function. This approach is used in order to isolate the faults that have same signatures. The principal characteristics of parity space, observers and parameter estimation are classified using an ontological model. The function, in the ontological model frame, let to interpret otherwise the knowledge contents in residuals and signatures. This interpretation is based on the definition and. Specification of a generic frame using a structural, behavioral and functional analysis of residual generation, residual evaluation and decision tasks. The proposed approach is used on a simulated application concerning a D. C. Motor in open and closed loop, in order to detect and isolate sensor, actuator and component faults which have the same signatures. The contribution of this work is placed on the intersection of two fields: artificial intelligence and automatic control
Fiard, Gaëlle. "Apprentissage des biopsies prostatiques par la simulation : vers la validation du simulateur Biopsym." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAS037/document.
Повний текст джерелаProstate cancer is the most common malignancy and the 3rd cause of death among men in France. It is a major public health problem with around 50 000 new cases diagnosed each year. The diagnosis is suspected based on an abnormal digital rectal examination or an increase in the prostatic specific antigen level (PSA). Systematic, randomized, ultrasound-guided prostate biopsies are currently recommended first-line to confirm the diagnosis and define the tumor location, volume, and aggressiveness using the Gleason grading system. The conventional training method, based on mentoring, without quantitative feedback on the distribution of the biopsies, has limitations which can partly explain the lack of precision offered by systematic prostate biopsies.The Biopsym simulator was designed in this context to enhance prostate biopsy teaching through 7 exercises and a module replicating the performance of a 12-core systematic biopsy scheme. Several levels of assistance can be offered and a performance feedback is provided. A first validation study allowed to validate face, content and reliability of the simulator, but failed to prove its ability to discriminate between experts and novices (construct validity), in part due to a lack of realism. Two new validation studies on the new version of the simulator were set up during this thesis. The first one allowed for validation of the construct. The second one was able to demonstrate the transfer of skills acquired on the simulator under real-life conditions
Meftah, Tayeb. "Contributions au formalisme de l'élargissement de raies dans les plasmas : application au diagnostic de la raie Paschen alpha de He II." Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11035.
Повний текст джерелаBraham, Najoua. "Organisation d'un système de simulation de cas autour d'un système expert en hématologie." Compiègne, 1986. http://www.theses.fr/1986COMPS144.
Повний текст джерелаGodbert, Laurence. "Contribution au développement de méthodes de diagnostics et de simulation pour les plasmas de haute énergie." Aix-Marseille 1, 1994. http://www.theses.fr/1994AIX11055.
Повний текст джерелаDavari, Far Mehrdad. "Contribution to the fault diagnosis in photovoltaic systems." Amiens, 2014. http://www.theses.fr/2014AMIE0117.
Повний текст джерелаThe aim of this thesis was to develop methods for detecting faults in photovoltaic installations. An approach based on model and simulation to detect defects in the residential photovoltaic System (RPS) is proposed. A simplified hybridphotovoltaic panel used with MATLAB environment is developed and validated in this thesis. Its originality is that it runs in real time and it is flexible enough to simulate solar photovoltaic Systems with different scales, with or without bypass diodes and various technologies. Then a new technique for fault détection has been introduced. It consists of two main parts. A passive part, which will detect a fault by comparing the measured signals, and those obtained by the model. The active part is to analyze the different attributes to locale and identify the type of fault. Finally, the results obtained by simulation or practice of the method and the proposed techniques are satisfactory and open more perspectives in this area
Philip-Alliez, Camille. "Etude numérique et expérimentale de l'écoulement nasal chez les enfants présentant une obstruction nasale." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10140/document.
Повний текст джерелаOne of the essential data sought by the clinician in his diagnosis on the functionality of the nasal cavity. In some cases, this function is only partially approached by various measurement methods at its disposal. The prevalence of chronic nasal obstruction in the population (30% of the population) underlines the interest to orthodontists must wear respiratory disorders. The acquisition of a reliable diagnostic tool of nasal obstruction will allow for earlier treatment to guide the best craniofacial growth. The RAA can not be currently used as single diagnostic test, because its correlation with subjective assessments can remain low. The objective of this work is to provide a model for the diagnosis of nasal obstruction for all patients. In cases where the RAA does not allow a definite diagnosis of nasal obstruction, numerical simulations allow, after identifying the particular anatomical situations, to obtain a functional objective or not confirming the diagnosis of rheumatic fever. The methodology for this thesis consists of a complete resolution of the Navier-Stokes equations in geometries reconstructed in 3D, that is to say who received a digital processing to extract the contours and surface meshes and create volume. The development of objective measurement tools is a key issue in determining optimal treatment strategies and to evaluate treatment outcomes. Computer modeling of the dynamics of air flow within the nasal cavity from three-dimensional CT reconstructions may have clinical applications. One of its applications allow to visualize the flow postoperative virtually
Valotti, Andrea. "Analyse cosmologique d'amas de galaxies à partir de diagrammes de diagnostic en rayons X." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC301.
Повний текст джерелаCosmology is one of the fundamental pillars of astrophysics, as such it contains many unsolvedpuzzles. To investigate some of those puzzles, we analyze X-ray surveys of galaxy clusters. These surveys are possible thanks to the bremsstrahlung emission of the intra-cluster medium. The simultaneous fit of cluster counts as a function of mass and distance provides an independent measure of cosmological parameters such as m, _8, and the dark energy equation of state w0. A novel approach to cosmological analysis using galaxy cluster data, called top-down, was developed in N. Clerc et al. (2012). This top-down approach is based purely on instrumental observables that are considered in a two-dimensional X-ray color-magnitude diagram. The method self-consistently includes selection effects and scaling relationships. It also provides a means of bypassing the computation of individual cluster masses. My work presents an extension of the top-down method by introducing the apparent size of the cluster, creating a three-dimensional X-ray cluster diagram. The size of a cluster is sensitive to both the cluster mass and its angular diameter, so it must also be included in the assessment of selection effects. The performance of this new method is investigated using a Fisher analysis. In parallel, I have studied the effects of the intrinsic scatter in the cluster size scaling relation on the sample selection as well as on the obtained cosmological parameters. To validate the method, I estimate uncertainties of cosmological parameters with MCMC method Amoeba minimization routine and using two simulated XMM surveys that have an increasing level of complexity. The first simulated survey is a set of toy catalogues of 100 and 10000 deg2, whereas the second is a 1000 deg2 catalogue that was generated using an Aardvark semi-analytical N-body simulation. This comparison corroborates the conclusions of the Fisher analysis. In conclusion, I find that a cluster diagram that accounts for the fluxes, colors, sizes, and redshifts of the clusters performs well. Additionally, I find that it is at least as efficient as the traditional M,z method for the same cluster samples. I also discuss a proposition to apply this method to the XXL survey data
Hugon, Robert. "Diagnostics d'un plasma pulse d'azote pour l'étude de sa réactivité : comparaison des résultats expérimentaux avec un modèle numérique." Nancy 1, 1994. http://www.theses.fr/1994NAN10427.
Повний текст джерелаFanack, Catherine. "Etude analytique et numérique de la réflectométrie dans un plasma fluctuant : modèles à une et deux dimensions." Nancy 1, 1997. http://www.theses.fr/1997NAN10260.
Повний текст джерелаReflectometry is widely used in fusion plasmas for electron density profile measurements: the phase shift of a microwave reflected at a outoff layer depends upon the density profile. Density fluctuations may strongly disturb the profile reconstruction. It is therefore of primary importance to understand the role of the fluctuations (cutoff layer oscillation and Bragg backscattering) and to determine the correspondent phase shift. In this thesis, numerical and analytical models( one- and two-dimensional) are developed to study the effect of coherent fluctuations. After an overview of the principles of refleofometry and of the wave propagation in plasmas, the first part is devoted to the 1D numerical model ("radial" fluctuations). The spectral characteristics of the fluctuation are shown to play an important role. Analytical expressions of the phase shift are obtained under the Born approximation and are found in agreement with the numerical results. The nonlinear regime of Bragg scattering (Iarge amplitude fluctuations) exhibits phase jumps. This behavior is well reproduced by an analytical model. A second part describes the 2D code that allows for "azimuthal"fluctuations. The source is modeled as an emitting horn. The numerical results are compared with several existing theories. Only qualitative agreement is found. For fusion plasmas, the study confirms that fluctuations close to the cutoff layer play a dominant role
Mahyob, Amin. "Modélisation des machines électriques tournantes défectueuses par la méthode des réseaux de perméances : application à la machine asynchrone." Le Havre, 2009. http://www.theses.fr/2009LEHA0017.
Повний текст джерелаFault diagnosis in electrical machines needs a modelling approach reliable and as close to the reality as possible. It is shown that by proper modelling of the electrical machines it is possible to detect the effect of the different faults on the different machine quantities. This work proposes a robust modular model based on Permeance Network Method (PNM) for the diagnosis of induction machine stator and rotor faults. The proposed model allows taking into account the local magnetic saturation of the magnetic circuit due to heavy fault currents, especially in the case of inter-turn short circuit fault, and remains moderately time consuming. In this model, the magnetic circuit of the machine was represented by a set of permeances (reluctances); their values vary as functions of the magnetic state of the machine. Firstly, the system of algebraic equations describing the developed permeance network is written. Then, this magnetic model is coupled to the electrical and mechanical differential equations describing the induction machine operation in presence of different faults to achieve a final system of algebro-differential equations of first order with variable coefficients whose numerical solution is provided by the iterative Newton-Raphson method. The comparison between the experimental results and simulation results obtained by the proposed model in the presence of inter-turn short circuit fault shows the relevance of the chosen method to identify the signature of this fault in the measurable quantities
Coulanges, Matthieu. "Gestion des incertitudes et des connaissances expertes en radiothérapie assistée par l'image : contribution à l'optimisation des plans de traitement." Lille 1, 2005. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/b9de7357-3664-43ec-99bb-38c8be326cb3.
Повний текст джерелаLe chapitre 2 traite de l'évaluation de l'extension tumorale qui est un pré-requis à la définition d'un plan de traitement. Ceci correspond à la définition précise du CTV qui doit conduire à l'élimination totale des cellules cancéreuses. La difficulté de cette tâche repose sur l'histoire de la tumeur, sa nature, sa position et les organes à risque environnant. Un premier axe de travail concerne l'étude de bases de données de patients (cas du caner du sein) au travers de modèles de type statistiques ou notamment des KPPV. Un deuxième axe de travail concerne l'élaboration de modèles prédictifs de croissance tumorale. Le chapitre 3 est consacré à la prise en compte des incertitudes de mouvement ou de position dans le plan de traitement. Après avoir analyser l'influence de ces incertitudes sur les doses reçues, puis proposer un modèle rapide d'évaluation du calcul de dose en fonction du positionnement, nous proposerons une nouvelle méthode globale d'évaluation de plan de traitement par calcul des DVH statistiques prenant en compte les incertitudes de positionnement et de bougé. Ce travail se voulant très prospectif, nous conclurons en analysant les perspectives potentielles à donner à ce travail, d'une part concernant l'évaluation de l'envahissement tumoral, et d'autre part concernant la nécessité de réduire les incertitudes de positionnement
Bacchus, Alexandre. "Représentativité de la modélisation aux éléments finis pour le diagnostic de machines synchrones de grande puissance." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10014/document.
Повний текст джерелаAn identification method of rotor inter-turn short-circuits and static eccentricities of an operating turboalternator is developed. This approach provides the type of the machine functional state such as its seriousness and location. The electromotive force obtained from a radial flux sensor is considered in order to identify the machine faults. Some previous works have shown that learning methods are efficient to characterize precisely the fault of a machine. Thus, a fault signatures data set, i.e. prototypes matrix, is built thanks to simulations using finite element method applied to the machine considering a great number of functional states. Therefore, the goal of this work is to identify the class (fault) of experimental measurements using the simulated output. To do that, a small scale alternator is modelled and simulation outputs are compared to the experimental measurements. The application of supervised classification method chosen beyond the shape of data shows that a good classification rate of 79 % for short-circuits and 93 % for eccentricities can be achieved thanks to specific features and simulation output treatments. An identification rule of the fault type is designed by considering a hierarchical classification approach. It achieves excellent results since all experimental measurements are assigned to the right type of fault. Finally, the use of a finite state automaton achieves better results for short-circuits identification by taking into account the temporal evolution of the machine functional state
Homssi, Louay. "Outils de modélisation, identification et traitement du signal pour le diagnostic des défauts dans les systèmes continus." Toulouse, INSA, 1992. http://www.theses.fr/1992ISAT0017.
Повний текст джерелаAnselmi, Amedeo. "Ajustement anatomique des dispositifs d’assistance cardiaque mécanique de longue durée par exploitation de l’imagerie et de la simulation." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B001.
Повний текст джерелаLong-term circulatory mechanical assist devices are increasingly employed in the management of patients with advanced heart failure. Nonetheless, this therapeutic strategy is still associated with immediate and long-term complications; among these, pump thrombosis, thromboembolic events and pump dysfunction are particularly dreadful. Mechanical factors are involved in their pathogenesis. We hypothesize that the analysis of the post-implantation positioning of the devices (and particularly of the admission cannula for left ventricular assist devices) might provide additional useful information for the prediction of the above events. We also hypothesize that it is possible to optimize the management of these patients (under the perspective of device selection, choice of the left ventricular implantation site and implantation modalities) through computer-assisted preoperative planning. We have therefore established two axes of research. With the first axis, we propose an original system for orientation analysis of the intraventricular admission cannula with respect to the mitral valve (postoperative CT scan). This analysis indicates a significant association between the cannula orientation towards the interventricular septum and the occurrence of early/delayed complications. This novel method will be validated in larger cohorts and tested in a prospective clinical investigation. With the second axis, we propose a virtual implantation solution (environment Cami-TK), based on semi-automatic segmentation of cardiac structures (preoperative CT scan), augmented visualization of the CT scan images, virtual positioning of a 3D mesh representing the devices, and collision analysis with the thoracic structures (left ventricular assist devices and total artificial heart) or the right ventricle (ventricular assist devices only). We finally indicate future investigations concerning the application of computational fluid dynamics to facilitate computer simulation of the hemodynamics within the assisted left ventricle, and refined prediction of adverse events
Gautier, Pierre. "Dosage des polluants NO et CO par imagerie de fluorescence induite par laser dans les écoulements réactifs." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMIR26/document.
Повний текст джерелаThis PhD work is to develop a quantitative imaging technique for measurements of the concentration of pollutants in reactive flows. On one hand, the concern was to develop the NO fluorescence imaging technique. For this purpose, an n-level fluorescence model was first developed to calculate the behavior of fluorescence signals with temperature, species concentration, and pressure. Then this model was validated with fluorescence and absorption measurements acquired in an optical cell up to 800 K and to 20 bar and in a high-pressure laminar burner. From this model, a strategy used to measure the instantaneous NO distribution in a stratified flame was defined. Then, a similar study to detect CO with fluorescence was then investigated. Two-photon fluorescence measurements were performed in the optical cell and in a flame. The results make clear that the spectroscopic diagnostic becomes operational with the need to improve the performances of propulsion systems
Tagliante-Saracino, Fabien. "Combined study by Direct Numerical Simulation and optical diagnostics of the flame stabilization in a diesel spray." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC017/document.
Повний текст джерелаThe understanding of the stabilization process of Diesel spray flames is a key challenge because of its effect on pollutant emissions. In particular, the close relationship between lift-off length and soot production is now well established. However, different stabilization mechanisms have been proposed and are still under debate. The objective of this PhD is to provide an experimental and numerical contribution to the investigation of these governing mechanisms.Combustion of an n-dodecane spray issued from a single-hole nozzle was studied in a constant-volume precombustion vessel using a combination of optical diagnostic techniques. Simultaneous high frame rate schlieren, 355LIF (laser-induced fluorescence) and high-temperature chemiluminescence or OH* chemiluminescence are respectively used to follow the evolution of the gaseous jet envelope, formaldehyde location and lift-off position. Additional experiments are performed where the ignition of the mixture is forced at a location upstream of the natural lift-off position by laser-induced plasma ignition. The analysis of the evolution of the lift off position without laser ignition reveals two main types of behaviors: sudden jumps in the upstream direction and more progressive displacement towards the downstream direction. While the former is attributed to auto-ignition events, the latter is studied through the forced laser ignition results. It is found that the location of formaldehyde greatly impacts the return velocity of the lift-off position.A two-dimensional Direct Numerical Simulation (DNS) of a spatially developing turbulent lifted flame at the same operating conditions than the experiments and reproducing the temporal evolution of the lift-off length is proposed to provide a better understanding of the flame stabilization mechanisms. The DNS only covers a downstream region where the flow can be reduced to a gaseous jet, since experimental observations have shown that the flame stabilized downstream of the liquid spray. N-dodecane chemistry is modeled using a reduced chemical kinetics scheme (28 species transported) accounting for the low- and high temperature reaction pathways. Similar to what has been observed in the experiments, the flame stabilization is intermittent: flame elements first auto-ignite before being convected downstream until another sudden auto-ignition event occurs closer to the fuel injector. The flame topologies, associated to such events, are discussed in detail, using the DNS results, and a conceptual model summarizing the observations made is proposed. Results show that the main flame stabilization mechanism is auto-ignition. However, multiple reaction zone topologies, such as triple flames, are also observed at the jet periphery of the fuel jet helping the flame to stabilize by filling high-temperature burnt gases reservoirs localized at the periphery, which trigger in its turn auto-ignitions.Finally, a model predicting the fluctuations of the lift-off length around its time-averaged value is proposed. This model has been developed based on observations made in the experimental and numerical study: first, the lift-off length time-evolution was decomposed into a succession of auto-ignition events and downstream evolutions. Second, the period between two auto-ignition and the velocity of the downstream evolution was modeled using experimental correlations available in the literature. Third, the model has been adapted to take into account the effect of the high-temperature reservoirs on the flame fluctuations. Last, the model was compared to experimental data, where the ambient temperature, oxygen concentration and injection pressure were varied. Since the model showed good agreement with the experimental data, it can be used in addition to the model predicting the time-averaged lift-off length to better describe the Diesel flame stabilization
Bouaou, Kevin. "Apport de la mécanique des fluides dans l'étude des flux sanguins aortiques." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS076.
Повний текст джерелаAging is associated with morphological, functional and hemodynamic changes in the arterial system, most often aggravated by cardiovascular disease. Understanding these aggravating interactions is important to reduce patients risk. Medical imaging plays a major role in this context through modalities such as velocity encoding MRI combined with quantitative image processing and computational resolution of Navier-Stokes equations that govern blood flow hemodynamics. The aim of this thesis is to develop and combine image processing methods dedicated to 4D flow MRI data analysis with computational fluid dynamics to extract quantitative biomarkers such as intra-aortic pressure fields and their spatio-temporal propagations, aortic wall shear stress and intra-aortic vorticity. We have demonstrated the ability of these biomarkers to detect age-related sub-clinical aortic impairment and to characterize pathological aortic dilatation. In addition, association of spatio-temporal aortic pressure distributions with vortex occurrence and duration as well as with wall shear stress were studied. In a second work, we developed a numerical simulation software to solve the Navier-Stokes system using finite element models. An iterative projection method was applied to 2D and 3D vessel stenosis models as well as to 3D geometrical aortic models resulting from segmentation to validate our implementation. Finally, a preliminary work applying our numerical model to patient-specific geometries was performed revealing encouraging associations between simulated data and MRI measures
Coron, Laurent. "Les modèles hydrologiques conceptuelssont-ils robustes face à un climat en évolution ? Diagnostic sur un échantillon de bassins versants français et australiens." Phd thesis, AgroParisTech, 2013. http://pastel.archives-ouvertes.fr/pastel-00879090.
Повний текст джерелаEl, Kabir Taoufik. "Analyse d'objets par vision par ordinateur : géométrie et colorimétrie." Thesis, Poitiers, 2020. http://www.theses.fr/2020POIT2262.
Повний текст джерелаDigital image processing allows to perform non-destructive control in order to determine accurately the state of the analysed surfaces. In the medical field, it can improve patient care and assist clinicians in diagnosis and post-treatment follow-up. The work realised in this thesis focuses on Photometric-Stereo, one of the most important methods for information extraction by digital image processing. The Photometric-Stereo relies on the acquisition of the analysed surface from a fixed point of view but under different lighting positions. It enables the simultaneous extraction of the geometry and colorimetry of the analysed surfaces. It enables a simultaneous extraction of the geometry and colorimetry of the analysed surfaces. However, its application requires the formulation of several hypotheses that are not always valid under real conditions. Thus, we propose a solution to one of the most reductive hypotheses related to the photometric nature of the analysed surfaces. On the other hand, a new mathematical formulation of Photometric-Stereo is proposed to avoid the numerical integration step for the 3D reconstruction estimation. This original approach based on discrete geometry offers an inclusive numerical framework with a spatial character. As an application for this work, we propose a diagnostic aid system for psoriasis severity evaluation from the study of Photometric-Stereo previously carried out. The results obtained through these different contributions extend the use of Photometry-Stereo and demonstrate its potential in a rigorous application framework
Pelouze, Gabriel. "Interprétation unifiée des écoulements associés à des cycles de condensation et d’évaporation dans les boucles coronales." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS247/document.
Повний текст джерелаThe outermost layer of the solar atmosphere, the corona, is composed of plasma which is hotter than the surface by several orders of magnitude.One of the main challenges in solar physics is to explain how the corona is formed and heated to temperatures of a few million degrees.In this context, I focus on the heating of coronal loops (which are structures composed of plasma confined in magnetic field tubes), and more precisely on thermal non-equilibrium (TNE) cycles.Studying these cycles allows us to characterize the heating of coronal loops.These cycles occur in loops with a highly stratified heating, localized near their footpoints.Among other effects, they cause periodic variations of the temperature and density of the plasma in the loop.These variations result in long-period intensity pulsations, which have recently been detected in the extreme-ultraviolet (EUV) emission of some coronal loops.In addition, periodic flows of plasma at coronal temperatures occur during these cycles.In some cases, the flowing plasma can cool down by several orders of magnitude, and thus form periodic coronal rain.During my thesis, I worked on the first detection of these periodic plasma flows at coronal and lower temperatures.Using time series of spatially-resolved EUV spectra from the instrument Hinode/EIS, I measured the Doppler velocity of plasma in loops undergoing long-period intensity pulsations.This allowed me to detect flows of plasma at coronal temperatures associated with some maxima of the intensity pulsations.In addition, I took part in the detection of an event of periodic coronal rain (at cooler temperatures), using series of images from the instrument SDO/AIA.These detections confirm that the long-period intensity pulsations detected in coronal loops are indeed the result of TNE cycles, and allow better constrain the heating of the loops.From this, conclude that the heating of coronal loops is highly stratified, localized near their footpoints, with a repetition time shorter than the cooling time of the plasma.Detecting the flows of plasma at coronal temperatures required that I correct many EIS instrumental effects.To that aim, I developed a new method for coalinging EIS spectra with images from AIA.This method can correct the roll angle and the jitter (a random variation of the pointing) of EIS.By applying it to a large number of spectra, I carried out a comprehensive determination of the EIS roll angle.I also performed numerical simulations of the periodic coronal rain event.In these simulations, I computed the evolution of the plasma in the loop for different values of the heating parameters, as well as several magnetic field geometries.This allowed me to determine the heating parameters which are required to reproduce the observed behavior of this loop.By analyzing these simulations, I was also able to understand how the asymmetry of the loop and of the heating determine the minimum temperature of the plasma flows which form during thermal non-equilibrium cycles
Biasiori-Poulanges, Luc. "Fragmentation aérodynamique d’une goutte liquide induite par une onde de choc plane High-magnification shadowgraphy for the study of dropbreakup in a high-speed gas flow On the formation and recurrent shedding of ligaments in droplet aerobreakup Data on eosin y solutions for laser-induced fluorescence in water flows Multimodal imaging for intra-droplet gas-cavity observation during droplet fragmentation." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0002.
Повний текст джерелаThis thesis proposed a groundbreaking description of the shock-induced aerodynamic fragmentation of a water droplet at the transition of the Rayleigh-Taylor Piercing and the Shear-Induced Entrainment regimes. An experimental facility consisting of a shock tube and high-speed imaging diagnostics is used to investigate the fragmentation processes. Experimental results are supported with numerical simulations performed with the open-source code ECOGEN dedicated to multiphase compressible flows. The shock wave effect on the droplet is assessed by a theoretical modelling based on geometrical acoustics which allows for the description of the wave spatio-temporal dynamics and enables to predict the time-dependent location of the highest energy density. Pressure fields are determined using numerical simulations. It appears that the water tensile rupture is reached for a shock wave Mach number of 1.7 from which bubble cloud cavitation may occur by causing signification changes in the fragmentation dynamics. As regards to the interfacial dynamics, both experiments and numerical simulations show the development of a transverse azimutal modulation resulting in the periodic ligament structure at the droplet surface. Contrary to the modulation growth, its initiation seems to be independent of the capillary effects as revealed by a Fourier analysis of the 3-D numerical results. The ligament dynamics is a cyclic process driven by the vortex shedding process in the wake of the droplet. Four cycles have been observed before the residual droplet core breaks up owing to the growth of an air cavity inside the droplet that acts as weak spot, and thus facilitating the droplet split-off
Béraud, Nicolas. "Fabrication assistée par ordinateur pour le procédé EBM." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI052/document.
Повний текст джерелаThe Electron Beam Melting (EBM) process allows to build metallic parts from powder. Thanks to the geometric and mechanical quality of the parts produced, the EBM process can be used to manufacture functional parts and not only prototypes. This process, with other additive metallic processes, make it possible to consider a transition from 3D printing to metallic additive manufacturing.The use of additive manufacturing in an industrial environment requires compliance with quality, cost and time criteria for the parts produced. The production of manufactured parts involves a series of numerical stages which is called the numerical chain. The numerical chain has a significant impact on the three criteria mentioned above. Thus, this thesis provides an answer to the following question:How Computer Aided Manufacturing can improve the quality, cost and time of the EBM manufacturing process?This problem is addressed through the following underlying question:What are the required characteristics for a Computer Aided Manufacturing system adapted to the EBM process?In order to answer this question, the current numerical chain is analyzed. Three main limitations are found:- the use of STL files format- the process cannot be optimized at different scales- the process cannot be simulatedTo solve these issues, a CAM environment is proposed. It allows the centralization of all numerical operations in a single environment. All supported formats can be used within this environment, such as native CAD file formats or STEP format. Software developments are done to prove the feasibility of such an environment.The CAM environment implementation reveals the crucial role of simulation in this system. It is therefore necessary to answer this second question:How to obtain an EBM process simulation allowing the development of parameters, virtually?Although EBM simulation is a recurrent subject in scientific literature, existing studies are based on the finite elements method but the calculation time needed is too important to be used in an CAM environment. Thus, an alternative type of simulation is created in this thesis: a simulation based on abacus. It is composed of a finite elements model, that allows heat maps generation for standards cases of heating and cooling. These heat maps are then transformed in abacus. The simulation algorithm based on abacus search the nearest abacus from the simulated situation in order to estimate the temperatures at the next time step.This simulation method was used to reduce the calculation time while keeping a sufficient precision to optimize process parameters.With the simulation based on abacus, a tool for the optimization of melting strategies is developed. This tool allows quality improvement for the produced parts through the calculation of melting strategies according to thermic criteria.To summarize, the main contributions of this work are:- the definition of requirements specifications of a powerful numerical chain for the EBM process- the development of a CAM environment adapted to the EBM process- the proposal of a fast simulation for the EBM process, based on abacus- the development of a tool for the optimization of melting strategies
Djian, Francis. "Modélisation thermique des thermostats pour oscillateurs à quartz et applications." Besançon, 1991. http://www.theses.fr/1991BESA2021.
Повний текст джерелаFadlallah, Majida. "Application de la spectroscopie Stark de l'hydrogène atomique à la mesure du champ électrique dans les décharges luminescentes." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10058.
Повний текст джерелаLouin, Jean-Charles. "Effets d'hétérogénéités de teneur en carbone sur les cinétiques de transformations de phase et sur la genèse des contraintes internes lors du refroidissement d'aciers." Vandoeuvre-les-Nancy, INPL, 2003. http://www.theses.fr/2003INPL077N.
Повний текст джерелаHeat treatment is a process that needs the control of both final microstructures and residual stresses and deformations. Numerical simulation is a useful tool for a better optimization of this process. The aim of our work was to contribute to the development of a numerical tool for the prediction of microstructures, stresses and strains during cooling of pieces that may contain chemical heterogeneities, particularly carbon content heterogeneities. Firstly, an existing model for the prediction of transformation kinetics in steels has been further developped in order to take into account the effects of the carbon content enrichment of austenite due to a partial ferritic transformation on the subsequent transformations. Coupled thermal, metallurgical, mechanical calculations have then been performed to study the effects of carbon content gradients on the microstructural evolutions and on the residual stresses development during cooling. Particularly, the possible effects of solidification macro and mesosegregations have been quantified in massive cylinders with sizes close to the size of an ingot. Secondly, experimental validations have been performed for homogeneous cylindrical specimen (40CrMnMo8 steel) and for a chemically heterogeneous specimen specifically designed for our study. The complete set of input data necessary for the simulations has been established from experimental characterizations of the steel. The role of chemical heterogeneity has been analysed through the experimental and calculated results. Finally, a good correlation has been obtained between measurements and calculation of the deformation during cooling of a 3D "croissant" shaped specimen
Sech, Nicolas Le. "Photocathodes à base de nanotubes de carbone sur substrats semi-conducteurs de type III-V. Application aux amplificateurs hyperfréquence." Palaiseau, Ecole polytechnique, 2010. http://pastel.archives-ouvertes.fr/docs/00/50/14/43/PDF/These_N_Le_Sech.pdf.
Повний текст джерелаFauchet, Gauthier. "Modélisation en deux points de la turbulence isotrope compressible et validation à l'aide de simulations numériques." Lyon 1, 1998. http://www.theses.fr/1998LYO10027.
Повний текст джерелаMenezla, Rabea. "Réalisation d'un logiciel de résolution de l'équation de poisson à trois dimensions : Simulation numérique tridimensionnelle du claquage des composants à jonctions P-N." Ecully, Ecole centrale de Lyon, 1990. http://www.theses.fr/1990ECDL0027.
Повний текст джерелаDAEMERS, YVES. "Enseignement assiste par ordinateur, application aux candidoses : mycologie, clinique, diagnostic de laboratoire." Nice, 1988. http://www.theses.fr/1988NICE6547.
Повний текст джерелаChen, Dai. "Diagnostic des incohérences des systèmes de gestion de production assisté par ordinateur." Bordeaux 1, 1988. http://www.theses.fr/1988BOR10570.
Повний текст джерелаChevalier, Frédéric. "Le diagnostic assisté par ordinateur de l'image tomodensitométrique : étude de paramètres adaptés." Paris 12, 1991. http://www.theses.fr/1991PA120036.
Повний текст джерелаChen, Dai. "Diagnostic des incohérences des systèmes de gestion de production assisté par ordinateur." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37612644b.
Повний текст джерелаJoly, Cécile. "Simulations numériques d'un jet rond turbulent et de son interaction avec un tourbillon de sillage." Université de Marne-la-Vallée, 2002. http://www.theses.fr/2002MARN0147.
Повний текст джерелаThe general context of this study concerns the impact of contrails, these famous white plumes frequently observed in the aircraft wake, on the atmosphere. From an aerodynamic point of view, the formation of the contrails is characterised by the interaction between a turbulent jet and a wing-tip vortex. The aim of this thesis is to contribute to a better understanding of the thermal and dynamic phenomena involved in this flow. This work is based on the numerical resolution of the three-dimensional, unsteady and compressible Navier-Stokes and energy conservation equations. Two approaches are considered: the direct numerical simulation and the large eddy simulation. A temporal simulation of the transition to turbulence of a non-isothermal jet is performed without accounting for the vortex flow field. A the end of this simulation, a vortex model is superimposed on the jet flow field. The first part of this thesis describes the two approaches, the different subgrid models chosen for the large eddy simulations, and the numerical techniques employed. The second part is devoted to the jet flow simulation, and here the objective is to determine the subgrid model appropriated to this flow configuration. The third part is dedicated to the simulation of interaction between the jet and the vortex. Results are compared to experimental data. The simulations have demonstrated the development of large scale structures all around the vortex core. The temperature field concentrates in the large scale structures
Quatravaux, Thibault. "Évolution de la modélisation du procédé VAR : contribution à la description de la dispersion inclusionnaire dans le puits liquide et à la prévention de défauts de solidification." Vandoeuvre-les-Nancy, INPL, 2004. http://www.theses.fr/2004INPL037N.
Повний текст джерелаThis thesis deals with the modelling of Vacuum Arc Remelting process (VAR) using the numerical software SOLAR. The first aim of the study is a better description of several physical phenomena which occur during melting, in order to extend the application of the software to simulate the remelting of steel. The evolution in the modelling of transport phenomena in the secondary ingot is based on three major improvements: - lateral thermal transfer modelling, in order to take into account the formation of a gap between the ingot and the mould walls, a possible injection of a neutral gas, and the heating of water in the coolant circuit, according to its flow, - a better turbulence model, since the k-E model implemented previously in the numerical code was not accurate enough to correctly descri~ the flow of the liquid metal in the pool, - a new method to simulate the ingot growth, based on a cyclic operation of splitting and growth/migration of control volumes, which reproduces the continuous growth of the secondary ingot and allows for the refinement of the mesh close to the free surface. Finally, the improved model has been validated by comparison with experimental results provided from four remeltings carried out on full-scale furnaces. The second objective is the characterization of the quality of the manufactured products in terms of inclusion cleanliness and risk of freckles segregated channel generation. Ln order to describe the behaviour of inclusions in the liquid pool, a trajectory model, adapted to account for turbulent flows, was validated and then implemented in the code. Various particle behaviours were distinguished. A study on the risk of freckles generation led to the establishment of a criterion particularly weIl adapted to the process. A generalization of this criterion, suggested in this work, would allow the prediction of the probable orientation of such segregated channels
Ribot, Bénédicte. "Modélisation numérique d'un système de ventilation d'un tunnel routier par une trappe de désenfumage dans le cas d'un incendie." Lyon 1, 1999. http://www.theses.fr/1999LYO10195.
Повний текст джерелаDiener, Julien. "Acquisition et génération du mouvement de plantes." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0080.
Повний текст джерелаThe primary goal of my Ph. D. Has been to develop innovative animation techniques for virtual plants. Two main approaches have been explored: the reproduction real motion and real-time simulation. First, I have mixed vision algorithms and user interface in order to extract reliable motion data from videos. An innovative method has then been designed to estimate a valid hierarchical structure of branches using statistical study which is used to retarget the video movement on a wide range of virtual plants. Second, I have developed new animation method that computes the response of plants to interactively controllable wind. The main contribution has been to show that simple approximations of the wind load model leads to a drastic reduction of the run-time computations. The simulation algorithm takes full advantage of the parallel processing capabilities of computer graphics cards allowing the animation of thousand trees in real-time
Yu, Qizhi. "Modèles de rivières animées pour l'exploration intéractive de paysages." Grenoble INPG, 2008. http://www.theses.fr/2008INPG0126.
Повний текст джерелаRivers are ubiquitous in nature, and thus are an important component of the visual simulation of nature scenes. In nature, rivers are dynamic, therefore animation of rivers is necessary in these visual simulation applications. However, animation of rivers is a challenging problem. It incorporates multi-scale surface details and flow motion, and many phenomena involved have complex underlying physical causes. River animation is particular difficult in emerging interactive applications like Google Earth or games, which allow users to explore a very large scene and observe rivers at a very small scale or a very large scale at any moment. Controlling the design of water simulations is another hard problem. The goal of this dissertation is to achieve real-time, scalable, and controllable river animation with a detailed and space-time continuous appearance. To achieve this goal, we break down the river animation problem into macro-, meso-, and micro-scale subproblems from coarse to fine. We propose appropriate models for each scale that capture relevant surface details and fluid motion. In the macro-scale, we propose a procedural method that can compute velocities of rivers with curved banks, branchings and islands on the fly. In themeso-scale, we propose an improved featured-based simulationmethod to generate the crests of the quasi-stationary waves that obstaclesmake. We also propose a method for constructing an adaptive and feature-aligned water surface according to the given wave crests. In the micro-scale, we propose the use of wave sprites, a sprite-based texture model, to represent advected details with stationary spectrum properties on flow surfaces. Armed with wave sprites and a dynamic adaptive sampling scheme, we can texture the surface of a very large or even unbounded river with scene-independent performance. In addition, we propose a Lagrangian texture advection method that has other applications beyond river animation. We demonstrate that combining our models in three scales helps us incorporate visually convincing animated rivers into a very large terrain in real-time interactive applications
Morel, Hervé. "Diagnostic du rotor principal de l'hélicoptère : analyse de signatures vibratoires par réseaux de neurones." Paris, ENSAM, 2007. http://www.theses.fr/2007ENAM0001.
Повний текст джерелаChen, Haifeng. "Système de simulation de spectres de masse assisté par ordinateur." Paris 7, 2003. http://www.theses.fr/2003PA077143.
Повний текст джерелаBenchamma, Mérièm. "Réalisation d'un simulateur d'étude et de faisabilité pour la radiothérapie externe dynamique." Aix-Marseille 3, 1995. http://www.theses.fr/1995AIX30013.
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