Tesis sobre el tema "Modélisation de distorsion"
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Béra, Jean-Christophe. "Produits de distorsion acoustiques auditifs : modélisation cochléaire et mesure". Ecully, Ecole centrale de Lyon, 1993. http://www.theses.fr/1993ECDL0023.
Texto completoCherif, Iheb. "Modélisation et validation expérimentale de la distorsion de plaques usinées". Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0040.
Texto completoHeat exchangers used in new nuclear power generation plants are made of AISI 316L stainless steel plates stacked in order to improve their efficiency and compactness. During the plates production, residual stresses appear and could cause distortion. To ensure the assembly, this distortion must be controlled and minimized, mainly by controlling the evolution of the residual stress field. Residual stresses generated by manufacturing processes preceding machining were measured using various methods. Then, the obtained residual stresses distributions were integrated into a developed model to predict part distortion, considering the clamping and machining sequence effects. Experimental validation was carried out using a smart experimental device with force sensors integrated in a clamping system was developed. The influence of machining conditions on the plate distortion was also studied using this set-up. Finally, the developed model was used to optimize the machining strategy in order to minimize the distortion
Kassab, Rabih Kamal. "Modélisation par la méthode des éléments finis des distorsion dues au soudage d'un joint en T". Mémoire, École de technologie supérieure, 2007. http://espace.etsmtl.ca/231/1/KASSAB_Rabih_Kamal.pdf.
Texto completoDolganov, Rostislav. "Développement d'un modèle LES basé sur la théorie de la distorsion rapide". Phd thesis, Ecole Centrale de Lille, 2009. http://tel.archives-ouvertes.fr/tel-00577098.
Texto completoColin, Yann. "Simulation numérique de la distorsion générée par une entrée d'air de moteur civil par vent de travers". Toulouse, ISAE, 2007. http://www.theses.fr/2007ESAE0013.
Texto completoBelhadj, Youssef Nesrine. "Modélisation et commande des redresseurs triphasés fonctionnnant à haut rendement et à faible taux de distorsion harmonique : application au redresseur triphasé de Vienne". Mémoire, École de technologie supérieure, 2007. http://espace.etsmtl.ca/244/1/BELHADJ_YOUSSEF_Nesrine.pdf.
Texto completoSchaefer, Pierre-Loup. "Reconstruction de la déformée d’une aiguille instrumentée". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAS025/document.
Texto completoMost of navigation system dedicated to interventional radiology make the assumption that needles stay straight during insertions in tissues. In practice, this hypothesis is not verified as the interactions between needles and surrounding tissues cause the needles to bend, resulting in a loss of accuracy. My PhD thesis is a part of the national projet GAME-D whose goal is to solve that problem by developing and studying instrumented needles which should eventually provide 3D deformed shape of the needle to clinicians in real-time. My reasearch work focus on reconstruction of deformed needle shape from its strain sensors data. Precision needed for clinical use faces technical limitations which restraint number of sensors embedded on the needle. Methods developped to adress this issue fall into one of these two categories: sensors data retrieving and sensors data processing. Use of beam theory to study sensors deformations gives strain information such as torsion. It also allows to develop reconstruction methods able to use these informations to gain accuracy. An optimization method of the sensors positions based on needle insertions experimental data is proposed. Sensors optimal positions make sensors data much more significant. A statistical processing of experimental data is performed to extract deformation features of needles in tissue. It is further used in a a specially built reconstruction method. Representativeness of these features improve the reconstrution of the deformed shape of the needle
Reveyrand, Tibault. "Conception d'un système de mesure d'enveloppes temporelles aux accès de modules de puissance : application à la mesure du NPR et à la modélisation comportementale d'amplificateurs". Limoges, 2002. http://www.theses.fr/2002LIMO0013.
Texto completoThis work deals with the characterization and the analysis of envelope distortions due to power amplifiers when they are driven by complex modulations
Hamoud, Houssam Eddine. "Linéarisation par pré-distorsion numérique d'amplificateurs de puissance pour les nouvelles générations des systèmes de télécommunications". Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0110.
Texto completoModern communications systems converge towards multi-standard operation combined with high PAPR modulation formats where the power amplifier must first be optimized in efficiency and where linearity will then be corrected by adding a predistorter. If this solution seems functional, it seems inadequate and ineffective on 5G systems where the targeted bandwidths pose both architectural problems (complexity of the observation path) and problems of accuracy of the usual behavioural models based on a simplification of the Volterra series in its discrete form (GMP, DDR) in the face of exacerbated memory effects but also of energy efficiency of the linearized system (DPD+PA). In this context, it becomes necessary to move towards a predistorter model less dependent on the characteristics of the signal to be linearized, in particular by the TPM (Two path Memory) model developed at XLIM, based on a simplification of the Volterra series in its continuous form, is independent of the characteristics of the signal to be linearized.Our work focused on evaluating the linearity performance of the classical models (GMP, DDR) and the TPM model on different power amplifiers either from simulations or from physical measurements of the PA. To do this, we have set up a simulation environmentand an evaluation bench for predistortion models with physical PA in order to quantify ACPR performance according to the variation in signal characteristics (power, frequency, statistics). All these experiments made it possible to verify, on the one hand,the poor robustness of traditional approaches (GMP/DDR) and, on the other hand, the stability of the performance of the TPM approach, whatever the scenario envisaged. This study therefore paves the way for a new generation of pre-distributor which, if extracted once and for all, would only require an update on slow dynamic phenomena (ageing) and would make it possible to consider a simplified architecture of the DPD observation path; thus improving the overall energy efficiency of the linearizedsystem
Chouman, Mehdi. "Plasticité cyclique et phénomène de rochet : amélioration de la prédiction de l’ovalisation des tubes en acier durant le cintrage cyclique par modélisation de la distorsion de la surface de charge". Paris 13, 2010. http://www.theses.fr/2010PA132015.
Texto completoThe reel-lay installation process of offshore pipelines requires their transport in the form of reels. The cyclic reeling-straightening of these pipes induces an accumulation of ovalisation which decreases their resistance to collapse. This accumulation being a phenomenon of ratcheting, two possibilities were explored to improve its prediction: the law of kinematic hardening and the yield criterion. The capacity to predict the ovalisation was evaluated for several models of kinematic hardening coupled with the von Mises yield criterion. These models largely overpredict the ovalisation of the tubes. The influence of the yield criterion was evaluated by using the non quadratic yield function of Bron and Besson which has a set of « shape parameters ». The implementation of this model in the code Abaqus had highlighted a larger influence of the yield surface on the ovalisation. The use of this criterion improves the prediction of the ovalisation but insufficiently. This is due mainly to the invariant shape of the yield surface. Thus, we have proposed a phenomenological elastoplastic model describing distortion of yield surface based on Bron and Besson criterion: the distortion is modelled by varying the most influential parameter on the ovality according evolution laws depending on the strain path. The identification of the parameters of this model for the X60 and St52 steels shows its great capacity to predict the evolution of the ovality of the tube, as well as the strain (ratcheting) measured during the cyclic reeling test
Fakher, El Abiari Salah Eddine. "Modélisation des régimes d'écoulements instationnaires rencontrés en turbomachine axiale". Ecully, Ecole centrale de Lyon, 1987. http://www.theses.fr/1987ECDL0007.
Texto completoAbi, Hussein Mazen. "Linéarisation des amplificateurs de puissance : prédistorsion numérique adaptative en bande de base". Nantes, 2009. http://www.theses.fr/2009NANT2036.
Texto completoThis work deals with the linearization of power amplifiers. The aim is to evaluate experimentally linearization performance of digital baseband predistortion techniques and to propose some novel efficient implementation approaches. First, the traditional study based on power series modeling of the PA was repeated. Nonlinear phenomena were described and quantified. In the second part, we present a state of the art on the various linearization techniques. The most important part of this study was dedicated to the adaptive digital baseband predistortion technique. A new method for the implementation of digital predistortion was then proposed. This method was validated with simulations under Matlab and with measures. Its performances were compared to other classical implementation methods. An investigation on implementation complexity was also realized when continuous adaptation is adopted. The proposed method forms a good compromise between complexity and speed of convergence. The last part of this thesis was devoted to measurements. An automated measurement test bench has been specifically developed for the evaluation of digital baseband predistortion techniques. Two sets of measurements with two amplifiers, low and high power amplifiers, were carried out. The aim was to evaluate experimentally the performances of the proposed method and to highlight the memory effects in high power amplifiers, and evaluate the performance of digital predistortion techniques in this case
Rioual, Pascal. "Modélisation et commande d'un redresseur à MLI alimenté par un réseau déséquilibré". Cachan, Ecole normale supérieure, 1993. http://www.theses.fr/1993DENS0008.
Texto completoVanhatalo, Tara. "Simulation en temps réel d'effets audio non-linéaires par intelligence artificielle". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0077.
Texto completoCertain products in the realm of music technology have uniquely desirable sonic characteristics that are often sought after by musicians. These characteristics are often due to the nonlinearities of their electronic circuits. We are concerned with preserving the sound of this gear through digital simulations and making them widely available to numerous musicians. This field of study has seen a large rise in the use of neural networks for the simulation in recent years. This work applies neural networks for the task. Particularly, we focus on real-time capable black-box methods for nonlinear effects modelling, with the guitarist in mind. We cover the current state-of-the-art and identify areas warranting improvement or study with a final goal of product development. A first step of identifying architectures capable of real-time processing in a streaming manner is followed by augmenting and improving these architectures and their training pipeline through a number of methods. These methods include continuous integration with unit testing, automatic hyperparameter optimisation, and the use of transfer learning. A real-time prototype utilising a custom C++ backend is created using these methods. A study in real-time anti-aliasing for black-box models is presented as it was found that these networks exhibit high amounts of aliasing distortion. Work on user control incorporation is also started for a comprehensive simulation of the analogue systems. This enables a full range of tone-shaping possibilities for the end user. The performance of the approaches presented is assessed both through objective and subjective evaluation. Finally, a number of possible directions for future work are also presented
Dubé, Jean-François. "Modélisation simplifiée et comportement visco-endomageable des structures en béton : applications aux séismes et aux choc des ouvrages en béton armé". Cachan, Ecole normale supérieure, 1994. http://www.theses.fr/1994DENS0021.
Texto completoDuan, Yonggang. "Modélisation numérique des distorsions résiduelles de soudage de structures minces". Saint-Etienne, EMSE, 2007. http://www.theses.fr/2007EMSE0027.
Texto completoWelding technology is one of the main joining techniques used in industry for parts assembly in aeronautics, automobiles and ships. One major industrial concern is to limit the use of clamping tools to reduce the cost and facilitate the automation of assembly lines. Optimization of the welding sequence and process is one way to reach this goal. However, experimental optimization requires prototyping and measurements which are extremely expensive and time consuming and finally, very few solutions can be used. Inite element simulations can be used in that aim but the difficulty is, on one hand, that welding processes involve complex physical phenomena and, on the other hand, that where local models are sufficient to predict stresses, only global 3D models can correctly evaluate distortions. N this thesis, a 3D/shell adaptive approach has been thus studied. This method consists in moving a block of 3D elements with the heat source over a mesh initially constituted by shell elements. Specific elements (transition elements) on the boundary of the 3D block have been taken into account. Hereafter, a part of this thesis has been devoted to a local/global approach, which is proposed to determine the welding residual distortions of large structures. The principle of the local/global approach and the problems raised by this approach have been described. Finally, a study of the definition of the local model, by numerical simulations as well as a numerical solution concerning a simplified model, has been carried out
Rambaud, Pierrick. "Modélisation numérique des distorsions post usinage pour les pièces aéronautiques en alliage d’aluminium : application aux parois minces". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM025/document.
Texto completoThe manufacture of large aeronautical structural parts made of aluminium alloys requires multiple forming steps (rolling, die forging, forging, etc.), heat treatment and machining. During these manufacturing steps, the various thermomechanical loads suffered by the part before its machining induce plastic deformations as well as modifications of the microstructure which are sources of residual stresses. In addition to these residual stresses resulting from the thermomechanical history of the part, others result directly from the machining step. Indeed, during this step, up to 90% of the raw material of a part can be removed using sometimes severe cutting conditions. Aeronautical parts sometimes have complex geometries with thin walls. Thus, during and after machining, the geometry of the machined part is significantly modified by the redistribution of residual stresses at work. These residual stresses, whether inherited or induced by the process, strongly influence the final geometry obtained and are one of the main causes of non-conformity of the parts with the dimensional tolerances of the finished product. This results in a significant loss for manufacturing industries. In this thesis work, we focused on considering these two types of residual stresses in a numerical model predicting distortions. We focused only on aluminium parts from the aeronautics industry. We have thus coupled advanced numerical fitting and remeshing models with existing industrial software to provide a new numerical solution, fast and efficient. Based on the assumptions in the literature, we decided to model machining as a massive material removal where tool path and interaction with the machine will be neglected. The numerical objective is therefore to propose a method that can account for the redistribution of residual stresses within the part. Each step of the machining plan is thus represented by a remeshing step where the "machined volume" will be removed from the mesh followed by a mechanical computation to account for the reorganization of stresses and the deformations they induce. This iterative process, carried out in a parallel environment, required many numerical developments. Thus, a new remeshing and repartitioning strategy has been proposed to obtain a mesh capable of capturing the residual stresses resulting from near-surface machining and to significantly reduce the calculation times associated with changes in geometry through cutting. A simplified linear elasticity model has also been added to the approach to reduce the numerical cost of mechanical computation and allow for larger problems to be addressed on computers of reasonable power. In order to confirm the results obtained by these computations, the simulations were compared with experimental results from the literature and carried out specifically for this thesis work
Sobczyk, Christophe. "Modélisation des distorsions non-linéaires générées par les amplificateurs de télédistribution par câble : étude de dispositifs de compensation". Metz, 1995. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1995/Sobczyk.Christophe.SMZ9546_1.pdf.
Texto completoThis document presents some mathematical models which allow us to observe the non-linear distorsions created by CATV networks amplifiers. These models are : the Volterra model, the Price model and three models that use an approximation of the amplifier's transfert function. A comparative study, non-linear measurements made with three types of amplifier are used. Another part of this study is realized with a cascade of three identical amplifiers. A private appendix proposes solutions to reduce the non-linear distorsions generated by a cascade of amplifiers
Toussaint, Pierre. "De la quasi-resonance introduite dans les convertisseurs, DC-DC de moyenne puissance : application à l'absorption sinusoïdale". Cachan, Ecole normale supérieure, 1994. http://www.theses.fr/1994DENS0013.
Texto completoGuigue, Lisa. "Evaluation clinique de la pression artérielle centrale à partir de la mesure par cathétérisme radial en utilisant la modélisation de l'arbre artériel, de la liaison hydraulique et du capteur. Intégration de la fonction dans un dispositif de surveillance de la qualité de la mesure de la pression artérielle". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAS036.
Texto completoAortic pressure is generally recognized as a good index of the hemodynamic state of a patient. In intensive care units, aortic pressure is indirectly estimated via a radial catheter-tansducer system. The present study aims to remove the obstacles to a reliable evaluation of central pressure via the radial catheter-transducer system commonly used in clinics. These obstacles can be due to :1.technical problems occurring between the radial catheter and the sensor;}2.pathophysiological problems affecting the arterial tree between the heart and peripheral arteries. Several clinical situations have been identified in which alterations of the physical properties of the vasculature do not allow a reliable estimation of central arterial pressure using the common radial setting. One of these phenomena is the so called central-to-radial arterial pressure gradient.CATARSI, a medical device developped by AII SAS, affords a solution to the first group of problems by providing an index of the quality of the signal provided by the radial catheter-transducer system.Under pathophysiological conditions affecting the arterial vascualture of the patient, early detection of a mismatch between peripheral and central arterial pressure would also be of great clinical value. In this view, a new functionality could be develop to implement CATARSI. However, to achieve this goal, it is first necessary to understand, evaluate and modelize the precise pathophysiological mechanisms involved in these particular situations.The study contains three steps :1.Experimental evaluation, by oscillometry and catheterization, of AP propagation-time on the human arterial tree (aortic, radial, femoral arterial pressure) during a central-to-radial arterial pressure gradient. This evaluation has been carried out on patients undergoing Cardio Pulmonary Bypass (CPB). Several measurements have been performed: before, during and after CPB.2.Development and optimization of a method allowing the detection of an uncoupling between central and peripheral arterial pressure thanks to AP signal analysis in real time and a potential complementary measurement performed with CATARSI.3.Several central to radial arterial modelling propositions in order to present a better evaluation of central arterial pressure estimated by radial arterial pressure
Tchoumi, Nyankam Thierry Colin. "Modélisation multi-physique de l'arc de soudage et du dépôt du cordon de soudure lors d'une opération de soudage : prédiction des distorsions et des contraintes résiduelles". Thesis, Belfort-Montbéliard, 2016. http://www.theses.fr/2016BELF0296/document.
Texto completoThis thesis is dedicated to the development of numerical simulation tools allowing to understand complex multi-physics phenomena (thermal, solid mechanics, fluid mechanics and sciences materials) involved in TIG (Tungsten Inert Gas) welding operations of 316L thin plate used in the food industry. The local fusion of the elements to be assembled by welding has indeedthe disadvantage of inducing significant local deformations that complicate the assembly of parts. Another The disadvantage is the appearance of residual stresses that impact the durability of the welded structure. In order to predict these deformations and constraints during the design phase, for example in order to minimize them in playing on parameters such as the speed of execution and the intensity of the welding current, digital tools Predictors have been developed as part of this work.A model finite elements 3D of coupling between the thermal one and the mechanics, in the transient and nonlinear domains,was programmed in Ansys Parametric Design Language (APDL) using the software multi-physics ANSYS. The mobile source of heat by welding has been represented by a Gaussian profile whose parameters have been calibrated to optimize the geometric shape of the cord. To do this, the surface of Response of a factorial experiment plan was used. The numerical results obtained are quite satisfactory since the parameters of the Gaussian heat source identified using the factorial experiment planallow a faithful reproduction of the geometry of the cord. The comparison between the experimental values and Calculated deviation also shows good consistency with a relative difference of less than 5%. In order to study the voltage and the electrical conductivity during the priming and the maintenance of the welding arc, a Two-dimensional axisymmetric model of the electric arc was realized using FLUENT software. Geometry actual torch components such as the gas diffuser, the nozzle and the electrode were taken into account. The model integrates a fluid-structure coupling in which the electromagnetic and thermal equations are resolved in the solid cathode. The additional equations governing the flow are considered in the gaseous domain where the arc is generated. For the maintenance of the arc, these equations, which have been programmed in C ++, make it possible to overcome the artificial conductivity often used in the literature. The model allows to obtain the plasma temperature fields, the voltage drops at the anode and at the cathode of the welding, the voltage in the arc as well as the efficiency of the energy input. Numerical results indicate that plasma temperature and flow velocity increase with the intensity of the current and with the inter-electrode distance. The same goes for the electric potential but with a stronger influence of the inter-electrode distance. Finally, the gas flow plays no role on the temperature and on the electric potential. It influences the speed of flow of the plasma. The higher the flow, the higher the Plasma flow rate is low
Nicolazzi, William. "Modélisation des processus à l’équilibre et hors équilibre de matériaux à transition de spin : application à la simulation des diagrammes de diffraction des rayons X". Thesis, Nancy 1, 2008. http://www.theses.fr/2008NAN10078/document.
Texto completoModelisation of Equilibrium and non equilibrium processes experimentally observed in spin crossover compounds is essential for a better understanding of mechanisms of the transition existing in those bistable solids which are good candidates for future industrial applications in computing data storage. Measurements following the molecular spin state change (magnetic, optical…) have been successfully reproduced, using various models, in particular Ising-like models. However, structural phase changes, occurring during the spin state change and only accessible with X-ray or neutron diffraction experiments, can’t be reproduce with Ising-like models. The aim of this work is to interpret both kinds of measures: magnetic and diffraction. We have also introduced a new microscopic spin model in which lattice degrees of freedom have been explicitly taken into account. This anharmonic model has been solved analytically in the one dimensional case and numerically in higher dimensions using Monte Carlo simulation of equilibrium and non equilibrium processes. This model retrieves most of results or Ising-like models and simulates lattice expansion or contraction during the spin transition. We have coupled this anharmonic model with a soft called DISCUS, in order to simulate diffraction experimental conditions and to calculate the intensity diffracted by the lattice. Diffraction patterns have been reproduced in the different cases (thermal transition, thermal relaxation, photoexcitation…) observed experimentally. Conditions for the observation of the coexistence of HS and LS Bragg peak are discussed and analyzed. The concept of “like spin domains” (LSD) is then defined more precisely by introducing the concept of “molecular like spin domains” (MLSD) and structural like spin domains” (SLSD)
Cerutti, Xavier. "Modélisation numérique et analyse mécanique de l'usinage de grandes pièces aéronautiques : Amélioration de la qualité d'usinage". Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0029/document.
Texto completoThe manufacturing of aluminium alloy structural aerospace parts involves multiple forming (rolling, forging, etc.) and heat treatment steps. The mechanical and thermal loads that the workpieces undergo during these manufacturing steps result in unequal plastic deformation and in metallurgical changes which are both sources of residual stresses. Machining is usually the last manufacturing step during which the final geometry of the parts is obtained. Up to 90% of the initial volume of the workpiece can be removed during the machining of aerospace structural parts which can furthermore have complex geometries. The residual stress redistribution is one of the main causes of the non-conformity of parts with the geometrical and dimensional tolerance specifications and therefore of the rejection of parts.Nowadays, initial residual stresses and their effect during the machining are often not taken into account in the definition of the machining process plan. This work aims to propose an evolution in the establishment of machining process plans of aluminium structural parts. It has been organised along two principal lines of research: a numerical line and a mechanical analysis line.The numerical line is based on the development of a modelling approach and of a numerical tool adapted to the simulation of the machining process. The modelling approach has been defined based on assumptions deduced from literature reviews on aluminium alloys, on the machining process and on residual stresses. A massive material removal approach has then been developed. All the numerical developments have been implemented into the finite element software FORGE® and are suited to a parallel computing environment.The mechanical analysis line is based on the study of the residual stress redistribution and its effect on the workpiece deflections during the machining as well as on the post-machining distortion. A first study on the layer removal method used to determine the initial residual stress profiles in an AIRWARE® 2050-T84 2050-T84 alloy rolled plate has been realised. The simulation of these experiments has allowed a first validation of the numerical tool and to demonstrate the necessity to define machining process plans in function of the residual stresses. Other studies on the influence of some machining process parameters on the machining quality have then been performed. Simulation results have been validated by multiple comparisons with experimental tests, showing the capability of the numerical tool to predict the final machined part geometries.Using the results of the studies mentioned above, a numerical procedure and first recommendations for the definition of machining process plans allowing to obtain the desired machining quality depending on the initial residual stresses have been established