Academic literature on the topic 'Modélisation prédictive – Dissertation universitaire'
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Dissertations / Theses on the topic "Modélisation prédictive – Dissertation universitaire":
Bremaud, Luc. "Contribution à la modélisation de l’endommagement sous sollicitations dynamiques de céramiques." Electronic Thesis or Diss., Paris, HESAM, 2023. http://www.theses.fr/2023HESAE092.
Ceramics play a crucial role in both the industrial and military sectors due to their unique thermomechanical properties. However, their behavior under dynamic loading is complex, with significantly lower tensile strength compared to compression, leading to cracking, damage, and multi-fragmentation. The pursuit of advanced technology necessitates continuous development of the ballistic properties of ceramics. The high cost and technical complexity of dynamic experiments have given rise to simulation programs that seek to digitally replicate the dynamic fracture behavior of these materials.This thesis explored the application of the Discrete Element Method (DEM) to enhance the reproduction of dynamic phenomena in brittle ceramics, with a focus on representing cracking and the evolution of stress at fracture with strain rate. Alumina was chosen as the study material due to the abundance of experimental data available in the literature.The third chapter dealt with the representation of the material in the elastic regime, while the fourth chapter examined the incorporation of different damage models within the discrete approach. Comparisons between experimental and numerical rear face velocity profiles from Gas Gun Projectile Impact (GEPI) tests showed that the use of the Denoual-Forquin-Hild (DFH) and Kachanov laws provided good correlation with experimental data.The fifth chapter presents various types of experimental dynamic fragmentation tests on AL23 alumina: Rockspall tests, edge-on impact tests (from the literature), and laser shock experiments. DEM numerical simulations, using the previously identified damage law as the one that best reproduces GEPI spall tests, were conducted to represent the damage mechanisms, simple and multiple fragmentation of AL23 alumina targets subjected to extreme loading conditions.Finally, to obtain experimental data on dynamic tests of a new ceramic with a more complex behavior, an experimental campaign was conducted on plasma-sprayed yttria-stabilized zirconia. Impact-on-edge and Rockspall tests were carried out to study simple and multi-fragmentation of this ceramic with a complex microstructure. This provided experimental data that will be used in future modeling efforts.In summary, this thesis contributes to improving the replication of the behavior of brittle ceramics subjected to dynamic loading such as impacts or shocks. It highlights the potential of the DEM method to represent multi-fragmentation phenomena and identifies relevant damage models for simulating dynamically observed effects. These results have significant implications for representing the dynamic fracture behavior of high-performance armor materials in various industrial and military applications
Amoretti, Thomas. "Développement d’un outil de modélisation et d’optimisation pour les éoliennes à double rotor : application à la comparaison avec l’éolien classique." Electronic Thesis or Diss., Paris, HESAM, 2023. http://www.theses.fr/2023HESAE079.
The production of energy with low greenhouse gas emissions is a major objective of global sustainabledevelopment. One of the promising technologies for achieving this is wind power. The work presented in this manuscript concerns the study of an innovative horizontal-axis wind turbine system with two successive rows of rotors. The main objective is to compare multi-rotor technology with "conventional" wind turbine technology, in order to establish the advantages and disadvantages of each in a given use case. Dual-rotor wind turbines can have the rotors turning in opposite directions (contra-rotating) or in the same direction (co-rotating), which influences the performance obtained.To make this comparison, modeling and optimization tools were developed to compare the technologies as broadly as possible, without any preconceived ideas about the parameters to be set. Following a literature review, the comparison criteria selected were AEP (Annual Energy Production) and turbine mass. The modeling is based on a faithful, fast-resolving aerodynamic model, based on BEM (Blade Element Momentum) theory adapted for two rotors. This aerodynamic model interacts with mechanical, electromechanical and component weight models to describe the behavior of each technology. The models are coupled with a control strategy to provide performance values for thewind turbines modeled in this way. To find instances of each wind turbine technology for comparison, single-objective optimization algorithms (PSO) or unweighted multi-objective optimization algorithms (NSGA-II) were used. The models were validated by comparison with data from the literature and specialized software (Qblade and HELICIEL), and the comparison between technologies was carried out on a case study including a specific statistical wind distribution
Mboup, Bassirou. "Validation de biomarqueurs prédictifs de la réponse au traitement : extension des courbes de prédictivités à un critère de jugement censuré On Evaluating How Well a Biomarker Can Predicttreatment Response With Survival Data Insights for Quantifying the Long-Term Benefit of Immunotherapy Using Quantile Regression." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASR011.
It is common in oncology to want to determine whether or not only a subgroup of patients will benefit from a treatment. This is one of the paradigms of personalized or stratified medicine. Predictive biomarkers are often used to select these patients and most of these biomarkers are continuous. For example genomic signatures such as Oncotype-Dx. A methodology for evaluating a biomarker with binary response has been proposed in the literature. The objective of this thesis is in first work to extend this methodology with right-censored data and to determine at different prediction horizons the optimal threshold of the biomarker beyond which treatment will be attributed or avoided. A model whose estimates of these parameters are based on inverse censored probability weights is proposed to provide consistent estimators. An extension of the predictiveness curves will be carried out. In a second work, a test of the calibration hypothesis with right-censored data has been proposed. This test will be valid beyond the 60% censoring rate contrary to those already existing in the literature and will allow us to study the influence of a bad calibration on the determination of the threshold. A third work focuses on the determination of the threshold of a new prognostic biomarker for ovarian cancer in order to classify patients at high or low risk of relapse. Finally, a fourth work consists in illustrating the relevance of the censored quantile regression for quantifying the long term benefit of immunotherapy in a reconstructed data set from a single randomized trial. The proposed methodology can be readilty employed for individual patients data meta-analysis to summarize evidence of immunotherapy as quantified by the upper quantile of the survival distribution
Loisel, François. "Analyse cinématique et biomécanique de la main et du poignet par modélisation personnalisée. Effet de lésions et d’instrumentations." Electronic Thesis or Diss., Paris, HESAM, 2023. http://www.theses.fr/2023HESAE097.
The architecture of the hand and wrist is a complex set of articulations enabling the efficient execution of all the gestures of daily life.Precision of movement and transmission of effector forces require optimal joint congruence and bone cohesion ensured by an organized ligament system.Any trauma resulting in articular step off (fracture) or loss of bone cohesion (ligament rupture) is likely to produce pathological kinematics within these joints. The result is pain, decrease range of motion and impaired overall function. Knowledge of the pathophysiological mechanisms leading to these disorders is essential on several levels: firstly, in a diagnostic context, to be able to identify and treat any injury, even a partial one. Secondly, to improve overall knowledge of the physiological and pathological kinematics of the hand and wrist. And lastly, as part of an innovation drive to propose new solutions (implants) to unresolved problems.The design of customized geometric and biomechanical models in the general context of the study of human joints provides answers to these types of questions. In preliminary work, linked to my Master's research and Stan Durand's thesis, biomechanical tests were carried out on anatomical parts to analyze the effect of a specific implant on the kinematic behavior of the wrist, and to design a method for personalized modeling of the hand and wrist using low-dose biplane X-rays.Following on from this project, this thesis has several objectives.The first objective is to validate our method of personalized hand and wrist modeling in living subjects, by comparing it with the reference technique of TDM segmentation.Secondly, we will apply this method to create a corridor of physiological displacement of certain carpal bones of interest (scaphoid, lunate, triquetrum), between two reference positions (wrist in neutral position or closed fist) among a population of volunteers free of ligament lesions. This corridor of normality is useful for comparing physiological and pathological displacements in clinical practice.Indeed, the third objective is to compare carpal kinematic data from patients with infra-radiological ligament lesions with this corridor of normality. The aim is to assess the diagnostic capabilities of the customized model. By analyzing pre- and post-operative data, a feasibility study will also investigate the field of objective follow-up of surgical restoration by suture or ligament re-anchoring.The aim of such a study is therefore to use geometric, kinematic and biomechanical models of the hand and wrist to assess normal and pathological kinematics (diagnosis), and to analyze current surgical implants in order to propose areas for improvement
Aussem, Alexandre. "Théorie et applications des réseaux de neurones récurrents et dynamiques à la prédiction, à la modélisation et au contrôle adaptif des processus dynamiques." Paris 5, 1995. http://www.theses.fr/1995PA05S002.
Bauvin, Pierre. "Modélisation de la stéatose hépatique (NAFLD) et de ses facteurs de risque par apprentissage sur des données de santé." Thesis, Lille 2, 2020. http://www.theses.fr/2020LIL2S028.
Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease which is a combination of simple, slowly progressing steatosis, and non-alcoholic steatohepatitis (NASH), an inflammatory form which accelerates its progression. It is estimated that one in four people in the world is affected by NAFLD, and its prevalence is increasing rapidly, in parallel with the prevalence of its main risk factors: overweight, obesity and type 2 diabetes.This pathology is asymptomatic up to the complications, cirrhosis and liver cancer (hepatocellular carcinoma, HCC), which leads to late diagnosis and a negative impact on the associated morbidity and mortality. Furthermore, the reference diagnosis requires a liver biopsy, an invasive examination that cannot be performed routinely. As a result, the progression of the disease is poorly known and its estimation may suffer from a selection bias, towards patients with significant risk factors, who require a biopsy in the first place. A better understanding would allow the implementation of strategies to reduce its burden.The modelling approach is appropriate to take into account all susceptible patients, without having to carry out a large-scale follow-up study using liver biopsies in patients who are mostly asymptomatic. The objectives of this thesis are to describe and quantify the progression of NAFLD, to predict the associated morbidity and mortality, and to identify the population at risk, using Markov models. To do this, it is necessary to fill in some of the progression parameters via a literature review, to characterise the initial states (population likely to develop NAFLD) and the final states (mortality due to NAFLD), in order to deduce the missing progression parameters between the onset of the disease and mortality, by back-calculation.To exhaustively characterise NAFLD mortality, we identified all patients with cirrhosis or HCC from national hospital databases, representing more than 380,000 patients. We then developed an identification algorithm to determine the etiology underlying the hepatic complication, based on all the stays of the identified patients. This algorithm requires the identification of patients with cirrhosis or HCC of alcoholic or viral origin, to obtain by elimination only NAFLD patients. Once the specific mortality data had been obtained, we estimated the population likely to develop NAFLD, defined as all individuals with overweight or type 2 diabetes, excluding the population of excessive drinkers. We estimated the prevalence and incidence of this population, and modelled its evolution with age and years, based on individual data from surveys representative of the French population.Finally, we quantified the progression of NAFLD, and the impact of risk factors, using two approaches: from the literature, and from biopsy data from more than 1,800 obese patients who were candidates for bariatric surgery, resulting in a tool for predicting the progression of NAFLD in this population. We chose to back-calculate the progression parameters corresponding to the asymptomatic states, which are the most susceptible to selection bias.We obtained a model of the progression of NAFLD, taking into account the dynamic distribution of the population among weight classes and diabetes status, and resulting in the observed statistics of NAFLD deaths. The model takes into account gender, age, year, BMI (body mass index) class, diabetes status and the presence of a genetic polymorphism (PNPLA3 rs738409, C→G) as covariates of progression. It is a tool for assessing the impact of a possible treatment or public health policy on morbidity and mortality
Vuillod, Bruno. "Stratégie de modélisation multi-fidélité via une approche système incluant des métamodèles basés sur les entités NURBS." Electronic Thesis or Diss., Paris, HESAM, 2024. http://www.theses.fr/2024HESAE003.
The more complex the problem, the greater the amount of computational resources needed to simulate it. On the other hand, the need for accuracy in the results of a system will not be the same depending on its design phase and the domain studied. The goal of this thesis is to propose a fast, low-cost multi-fidelity modeling strategy. To meet this need, a hybrid modeling approach is developed that combines Model-Based System Engineering (MBSE) and a metamodel based on Non-Uniform Rational Basis-Spline (NURBS) hypersurfaces. More specifically, the scientific challenge of this work is to develop a metamodel based on NURBS entities to simulate the behavior of highly nonlinear systems that require high fidelity modeling but are capable of providing results in real time to be compatible with the MBSE approach. In this context, the NURBS entity-based metamodel is obtained as a solution to an optimization problem solved with a gradient algorithm. In addition, a smoothing term is included in the problem formulation, not only to reduce the influence of any spurious nonlinearities in the training database, but also to limit the phenomenon of overfitting. The technical and scientific challenge of this work is to couple the general MBSE approach with the NURBS-based metamodel
Werbrouck, Coralie. "Modélisation in vitro & in vivo de la résistance à la radiothérapie dans les gliomes infiltrants du tronc cérébral (DIPG) TP53 Pathway Alterations Drive Radioresistance in Diffuse Intrinsic Pontine Gliomas (DIPG)." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL001.
Diffuse intrinsic pontine gliomas (DIPG) are the most severe pediatric brain tumours. Though accepted as the main therapeutic, radiotherapy is only transiently efficient and not even in every patient. We previously identified a heterogeneous response to radiotherapy at diagnosis (Castel et al., 2015). The aim of the project was to define the mechanisms of radioresistance.First, we assessed in vitro response to ionizing radiations in a collection of DIPG cellular models derived from treatment-naïve biopsies and we uncovered TP53 mutation as the main driver of increased radioresistance. We validated this finding in 4 isogenic pairs of DIPG cells with TP53WT and TP53KD. Then, we demonstrated with an extended cohort of 73 DIPG patients that mutated TP53 patients had a poor response to radiotherapy. Using a kinome-wide synthetic lethality RNAi screen, we further identified target genes that can sensitize TP53MUT DIPG to ionizing radiations. CHK1 inhibition increases response to radiation specifically in TP53MUT cells and could be considered as a new therapeutic approach in this setting. Finally, we established in vitro radioresistant DIPG cells to study tumour relapse and we developed tools to model post-radiotherapy relapse through the study of clonal dynamics using single cell RGB marking.In all, this results go further in the understanding of the DIPG radioresistance. We demonstrated that a TP53 alteration is a theranostic marker to predict radioresistance and we opened new therapeutic opportunities in combination with radiotherapy for the treatment of this pediatric disease, which remains incurable
Tounsi, Latifa. "Microalgue rouge du genre porphyridium : modélisation de la production de métabolites et application dans la production d'emballages actifs." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0144.
A microalga was isolated from the Tunisian coast in the Mahdia governorate and subsequently identified using morphological criteria as well as molecular biology techniques. The isolate was identified as belonging to the genus Porphyridium. In the 1st part, Porphyridium sp. and Porphyridium cruentum UTEX 161 were grown in 3 culture media to identify the optimal growth medium and enhance the production of metabolites. Results showed that Porphyridium could thrive in a wide range of media. The highest biomass production was achieved with the Pm medium (2 × 107 cells/mL) for Porphyridium sp. The highest pigment content (chlorophyll a = 0.678 ± 0.005 pg/cell, total carotenoids = 0.18 ± 0.003 pg/cell, B-phycoerythrin = 3.88 ± 0.003 pg/cell) and soluble proteins (14.58 ± 0.35 pg/cell) were observed with F/2 medium. Porphyridium sp. accumulated a higher amount of starch in the F/2 medium (0.69 ± 0.016%) and was on par with the Hemerick medium (0.62 ± 0.050%). The Hemerick medium showed the most promise in terms of lipid (2.23%) and EPS (5.41 ± 0.56) production. For Porphyridium cruentum, the F/2 medium was the best medium for growth (4.65 × 106 cells/mL) and production of pigments (chlorophyll a = 1.76 ± 0.007 pg/cell, total carotenoids = 0.48 ± 0.0022 pg/cell, B-phycoerythrin = 15.77 ± 0.6 pg/cell), starch (3.97 ± 0.22%) and proteins (34.36 ± 1.035 pg/cell). However, the Pm and Hemerick media proved to be the best for supporting the production of lipid (4.51 ± 0.45%) and EPS (14.19 ± 0.19 pg/cell),. In the 2nd part, bioactive films based on gelatin and sodium alginate were developed by incorporating an aqueous extract of B-phycoerythrin from Porphyridium cruentum at different concentrations (45, 67.5, and 90 μg/mL). The optimization process yielded a maximum B-phycoerythrin content of 4.16 ± 0.24% under the following conditions: NaCl = 17 g/L, MgCl2.6H2O = 2.6 g/L and K2HPO4 = 0 g/L. The B-phycoerythrin extract demonstrated antibacterial and antioxidant properties. The incorporation of B-phycoerythrin led to a significant increase in water swelling index and solubility, as well as a notable decrease in moisture content. Furthermore, when added to gelatin and sodium alginate films, the B-phycoerythrin extract improved the L*, a*, and ΔE* values. X-ray diffraction analysis revealed that the addition of B-phycoerythrin extract had a positive influence on the crystallinity of the developed films. The films incorporating the B-phycoerythrin extract exhibited a homogeneous structure with a slightly rough surface. The new films demonstrated complete biodegradability and promising antioxidant potential
Sotty, Jules. "Toxicité in vitro des particules atmosphériques fines et ultrafines : focus sur les bronchopneumopathies chroniques et la fonction mitochondriale." Thesis, Lille 2, 2019. http://www.theses.fr/2019LIL2S024.
Epidemiological studies have highlighted an association between ambient particulate matter (PM) level and hospital admissions or even mortality related with exacerbation of asthma and chronic obstructive pulmonary disease (COPD). While the role of inhaled PM in exacerbating these pathologies has been reported, pathophysiological mechanisms initiating and maintaining airway inflammation are not yet well understood. Reported health issues seems to be mostly caused by finest particles, due to their ability to diffuse deeply in the lungs, where clearance is less effective. Although numerous experimental studies demonstrated the toxicity of fine particles (PM2.5), mainly through oxidative stress-induced airway inflammation, only few studies have paid close attention to the ultrafine fraction (PM0.1), which attains new properties at nanometric scale. Because of its high specific surface area, PM0.1 is likely to be more biologically reactive. In this study, in vitro assays were conducted, exposing differentiated models of human bronchial epithelial cells (HBEC), from healthy, asthmatic and COPD-diseased donors, to one or three low dose of PM0.18-2.5 and PM0.18. Cytotoxicity, extracellular secretion of proinflammatory mediators and gene expression were studied. Furthermore, mitochondrion is a major endogenous source of reactive oxygen species (ROS) through oxidative metabolism, and coordinate many cell survival signaling processes. In this context, alterations in mitochondrial dynamic and function might play a key role in maintaining PM-induced oxidative stress and inflammation within lung cells, especially in case of chronic lung diseases initiation and/or exacerbation. Human bronchial epithelial BEAS-2B cells were also acutely or repeatedly exposed to low doses of fine (PM0.18-2.5) or ultrafine (PM0.18) particles, in order to characterize mitochondrial dynamic and function without massive cell death. Results highlighted in this study should contribute to a better understanding of the mechanisms governing the initiation and/or exacerbation of chronic airway lung diseases induced by air pollution-derived fine and ultra-fine PM