Dissertations / Theses on the topic 'Erreur inverse'
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Fu, Shuai. "Inverse problems occurring in uncertainty analysis." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112208/document.
This thesis provides a probabilistic solution to inverse problems through Bayesian techniques.The inverse problem considered here is to estimate the distribution of a non-observed random variable X from some noisy observed data Y explained by a time-consuming physical model H. In general, such inverse problems are encountered when treating uncertainty in industrial applications. Bayesian inference is favored as it accounts for prior expert knowledge on Xin a small sample size setting. A Metropolis-Hastings-within-Gibbs algorithm is proposed to compute the posterior distribution of the parameters of X through a data augmentation process. Since it requires a high number of calls to the expensive function H, the modelis replaced by a kriging meta-model. This approach involves several errors of different natures and we focus on measuring and reducing the possible impact of those errors. A DAC criterion has been proposed to assess the relevance of the numerical design of experiments and the prior assumption, taking into account the observed data. Another contribution is the construction of adaptive designs of experiments adapted to our particular purpose in the Bayesian framework. The main methodology presented in this thesis has been applied to areal hydraulic engineering case-study
Beuzeville, Theo. "Analyse inverse des erreurs des réseaux de neurones artificiels avec applications aux calculs en virgule flottante et aux attaques adverses." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP054.
The use of artificial intelligence, whose implementations are often based on artificial neural networks, is now becoming widespread across a wide variety of tasks. These deep learning models indeed yield much better results than many specialized algorithms previously used and are therefore being deployed on a large scale.It is in this context of very rapid development that issues related to the storage of these models emerge, since they are sometimes very deep and therefore comprise up to billions of parameters, as well as issues related to their computational performance, both in terms of accuracy and time- and energy-related costs. For all these reasons, the use of reduced precision is increasingly being considered.On the other hand, it has been noted that neural networks suffer from a lack of interpretability, given that they are often very deep models trained on vast amounts of data. Consequently, they are highly sensitive to small perturbations in the data they process. Adversarial attacks are an example of this; since these are perturbations often imperceptible to the human eye, constructed to deceive a neural network, causing it to fail in processing the so-called adversarial example.The aim of this thesis is therefore to provide tools to better understand, explain, and predict the sensitivity of artificial neural networks to various types of perturbations.To this end, we first extended to artificial neural networks some well-known concepts from numerical linear algebra, such as condition number and backward error. These quantities allow to better understand the impact of perturbations on a mathematical function or system, depending on which variables are perturbed or not.We then use this backward error analysis to demonstrate how to extend the principle of adversarial attacks to the case where not only the data processed by the networks is perturbed but also their own parameters. This provides a new perspective on neural networks' robustness and allows, for example, to better control quantization to reduce the precision of their storage. We then improved this approach, obtained through backward error analysis, to develop attacks on network input comparable to state-of-the-art methods.Finally, we extended approaches of round-off error analysis, which until now had been approached from a practical standpoint or verified by software, in neural networks by providing a theoretical analysis based on existing work in numerical linear algebra.This analysis allows for obtaining bounds on forward and backward errors when using floating-point arithmetic. These bounds both ensure the proper functioning of neural networks once trained, and provide recommendations on architectures and training methods to enhance the robustness of neural networks
Huang, Shaojuan. "Multi-scale identification of composite materials." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2244/document.
Composite materials are more and more important in the industry community. For the identification of the heterogeneous and anisotropic mechanical behavior of some composite, the full-field measurements are widespread in the mechanics community, because they can offer a very rich information of displacement or strain to exploit heterogeneous tests. During last thirty years, some specific inverse identification strategies have been proposed but most of these methods consider the identification problem only on the measured area and would usually need boundary conditions to be performed. However, the boundary conditions are not always completely known and might not be on the measurement zone. There is hence a need of identification methods allowing both the identification over the whole specimen and the dealing of missing boundary conditions. The Modified Constitutive Relation Error (M-CRE) allows dealing with such situations through the taking into account of the whole available information from a theoretical and experimental point of view without additional assumption. For the identification of elastic properties, a first mono-scale strategy has been proposed and actually used to process different types of boundary conditions as well as their absence. Considering the identification of heterogeneous elastic properties, the lack of information outside the measurement zone prevents from identifying heterogeneous properties in this area. It leads us to propose a multi-scale approach where micro heterogeneous properties are sought at the measurement level and macro homogeneous ones at the specimen level
Barbarella, Elena. "Towards the localization and characterization of defects based on the Modified error in Constitutive Relation : focus on the buckling test and comparison with other type of experiments." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN066/document.
Composite materials are nowadays extending their operational field to industrial applications other than aeronautics. New potential markets, such as automotive, imply the need to comply with different constraints; reduced cost and production time become more binding, taking the lead over the complete absence of defects. The drawback to fast automatized procedure is the higher defectiveness of the components produced, a deeper control of the part is therefore needed. Non-destructive techniques are expensive both in terms of cost and time and therefore the main question we tried to answer in this thesis is: is it possible to detect and estimate the effect of defects without resorting to the complex and time-consuming NDT techniques? An acceptable answer may potentially lead to a lower precision but should guarantee sufficient quantitative information for these applications. The thesis aims at exploring possibilities to use classical mechanical test combined with Digital Image correlation and inverse procedure to localize and characterized possible (large) defects. Buckling tests have been chosen at first due their supposed sensitivity to defects. Among the possible inverse technique, we have chosen to extend the so-called Modified Error in Constitutive Relation to the case of buckling because, in the case of vibration tests performed with several frequencies, the MCRE proved to have very good localization properties. The dedicated formulation of the MCRE for linearized buckling requires a post-processing of the non-linear experimental results. The Southwell plot is here employed to reconstruct the eigenvalue, the critical load, of the equivalent eigenvalue problem (i.e. the solution of the problem with material defect and no geometrical ones) and the Stereo Digital Image Correlation (StereoDIC) is exploited to reconstruct the deformed shape of the specimen during the test, used as mode. The interests and limits of the methodology are discussed notably through the comparison of numerical results using the MCRE in case of traction, flexion or vibration tests. It is shown that the linearized buckling based MCRE technique proves well for pseudo-experimental measurements at least for moderate geometrical imperfections. In addition first experiments have been performed; the defects are characterized from real experimental specimens, both for a nominally perfect specimen and for a defective one, where a zone of fibre waviness is induced. Stereo Digital Image Correlation (StereoDIC) is exploited to reconstruct the deformed shape of the specimen during the test, this shape being used as an approximation of the buckling mode. While on the first one no defects are detected, on the flawed specimen the localized area is in reasonable agreement with the area affected by fibre undulations
Koohkan, Mohammad Reza. "Multiscale data assimilation approaches and error characterisation applied to the inverse modelling ofatmospheric constituent emission fields." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1140/document.
Data assimilation in geophysical sciences aims at optimally estimating the state of the system or some parameters of the system's physical model. To do so, data assimilation needs three types of information: observations and background information, a physical/numerical model, and some statistical description that prescribes uncertainties to each componenent of the system.In my dissertation, new methodologies of data assimilation are used in atmospheric chemistry and physics: the joint use of a 4D-Var with a subgrid statistical model to consistently account for representativeness errors, accounting for multiple scale in the BLUE estimation principle, and a better estimation of prior errors using objective estimation of hyperparameters. These three approaches will be specifically applied to inverse modelling problems focussing on the emission fields of tracers or pollutants. First, in order to estimate the emission inventories of carbon monoxide over France, in-situ stations which are impacted by the representativeness errors are used. A subgrid model is introduced and coupled with a 4D-Var to reduce the representativeness error. Indeed, the results of inverse modelling showed that the 4D-Var routine was not fit to handle the representativeness issues. The coupled data assimilation system led to a much better representation of theCO concentration variability, with a significant improvement of statistical indicators, and more consistent estimation of the CO emission inventory. Second, the evaluation of the potential of the IMS (International Monitoring System) radionuclide network is performed for the inversion of an accidental source. In order to assess the performance of the global network, a multiscale adaptive grid is optimised using a criterion based on degrees of freedom for the signal (DFS). The results show that several specific regions remain poorly observed by the IMS network. Finally, the inversion of the surface fluxes of Volatile Organic Compounds (VOC) are carried out over Western Europe using EMEP stations. The uncertainties of the background values of the emissions, as well as the covariance matrix of the observation errors, are estimated according to the maximum likelihood principle. The prior probability density function of the control parameters is chosen to be Gaussian or semi-normal distributed. Grid-size emission inventories are inverted under these two statistical assumptions. The two kinds of approaches are compared. With the Gaussian assumption, the departure between the posterior and the prior emission inventories is higher than when using the semi-normal assumption, but that method does not provide better scores than the semi-normal in a forecast experiment
Marchand, Basile. "Assimilation de données et recalage rapide de modèles mécaniques complexes." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN053/document.
For several years, the considerable changes that have occurredin computing tools have led to new practices in the simulation of mechanical structures. Among them, the motivation for this work is the Dynamic Data Driven Application Systems paradigm (DDDAS). The founding idea of this approach is to establish a dialogue between a physical system and its numericalmodel. The objective is then to (i) allow a calibration of the numerical model by means of measurements performed on the physical system; (ii) control the evolution of the physical system using theprediction given by numerical simulation. The major difficulty is to realize this dialogue in real time. This work focuses on the model updating step of the DDDAS paradigm. The problem is then to develop methods and tools to solve inverse problems taking into account various constraints, namely: (i) robustness with respect to corrupted data; (ii) genericity for considering a wide variety of problems and mechanical models; (iii) a reduced computation time in order to tend towards a real-time model updating.The starting point of this work is the modified Constitutive Relation Error, an energetic approach dedicated to the solution of inverse problems in mechanics, notably illustrated by its robustness with respect to measurement noises. First, in order to guarantee a fast identification process, we have coupled the modified Constitutive Relation Error with the PGD model reduction in the linear model framework, thus enabling a fast and automatic identification process. Then, in order to be applied to the DDDAS paradigm, we have developed an identification method based on a data assimilation process (the Kalman filter) and using the modified Constitutive Relation Error as an observer alwayswithin the framework of linear problems. We have then extended this data assimilation approach to the problem of the identification of parameter fields by introducing a separation of the spatial discretizations and by introducing tools resulting from the mesh adaptation framework. We have then addressed the problem of non-linear mechanical models, through damage and visco-plasticitymodels. To this end, we have first recast and extended the concept of the modified Constitutive Relation Error to this nonlinear material framework and we have implemented a dedicated resolution process, based on the LaTIn method. Finally, we have introduced this reformulation of the modified Constitutive Relation Error in the previously data assimilation method in order to process the model updating of nonlinear models
Ben, Azzouna Mouldi. "Identification à partir de mesures de champs : application de l'erreur en relation de comportement modifiée." Phd thesis, Université de Technologie de Compiègne, 2013. http://tel.archives-ouvertes.fr/tel-00968138.
Casanove, Marie-José. "Deconvolution partielle et reconstruction d'image : un nouveau principe de regularisation." Toulouse 3, 1987. http://www.theses.fr/1987TOU30022.
Nouisri, Amine. "Identification paramétrique en dynamique transitoire : traitement d’un problème couplé aux deux bouts." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN005/document.
This thesis deals with parameters identification in transient dynamic in case of highly noisy experimental data. One long-term goal is the derivation of a non-intrusive method dedicated to the implementation in a commercial finite element code.In this work, the modified error in the constitutive relation framework is used to treat the identification of material parameters. The minimization of the cost function under constraints leads, in the case of transient dynamics, to a « two points boundary value problem » in which the differential space-time problem involves both initial and final time conditions. This results in a problem coupling the direct and adjoint fields, whose treatment is difficult.In the first part, methods such as those based on the « Riccati equations » and the « shooting methods » have been studied. It is shown that the identification is robust even in the case of highly corrupted measures, but these methods are limited either by the implementation intrusiveness, conditioning problems or the numerical cost.In the second part, an iterative over-relaxation approach is developed and compared to the aforementioned approaches on academic problems in order to validate the interest of the method. Finally, comparisons are carried out between this approach and a « discretized » variation of the formulation introduced by Bonnet and Aquino [Inverse Problems, vol. 31, 2015]
Khazâal, Ali. "Reconstruction d'images pour la mission spatiale SMOS." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/917/.
Synthetic aperture imaging radiometers are powerful sensors for high-resolution observations of the Earth at low microwave frequencies. Within this context, the European Space Agency is currently developing the Soil Moisture and Ocean Salinity (SMOS) mission devoted to the monitoring of SMOS at global scale from L-band space-borne radiometric observations obtained with a 2-D interferometer. This PhD is concerned with the reconstruction of radiometric brightness temperature maps from interferometric measurements through a regularization approach called Band Limited Regularization. More exactly, it concerns with the reduction of the systematic error (or bias) in the reconstruction of radiometric brightness temperature maps from SMOS interferometric measurements. It also extends the concept of "band-limited regularization approach" to the case of the processing of dual and full polarimetric data. Also, two problems that may affect the quality of the reconstruction are investigated. First, the impact of correlators and receivers failures on the reconstruction process is studied. Then, the calibration of MIRAS antenna's voltage patterns, when the instrument is in orbit, is also studied where a general approach is proposed to estimate this antenna's patterns
Elamine, Abdallah Bacar. "Régression non-paramétrique pour variables fonctionnelles." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20017.
This thesis is divided in four sections with an additionnal presentation. In the first section, We expose the essential mathematics skills for the comprehension of the next sections. In the second section, we adress the problem of local non parametric with functional inputs. First, we propose an estimator of the unknown regression function. The construction of this estimator is related to the resolution of a linear inverse problem. Using a classical method of decomposition, we establish a bound for the mean square error (MSE). This bound depends on the small ball probability of the regressor which is assumed to belong to the class of Gamma varying functions. In the third section, we take again the work done in the preceding section by being situated in the frame of data belonging to a semi-normed space with infinite dimension. We establish bound for the MSE of the regression operator. This MSE can be seen as a function of the small ball probability function. In the last section, we interest to the estimation of the auxiliary function. Then, we establish the convergence in mean square and the asymptotic normality of the estimator. At last, by simulations, we study the bahavour of this estimator in a neighborhood of zero
Nguyen, Hong-Minh. "Une stratégie d'identification robuste pour la localisation et la rupture." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2006. http://tel.archives-ouvertes.fr/tel-00140895.
Les difficultés rencontrées dans ces cas résident dans la non-linéarité et le caractère instable du problème de minimisation sous contraintes non linéaires auquel la formulation nous amène. Une extension de la méthode LATIN aux problèmes mal posés a été proposée et développée afin de permettre la résolution itérative de ce type de problèmes d'optimisation. La résolution de ces derniers fait appel à une méthode de traitement robuste issue du contrôle optimal et basée sur l'équation de Riccati.
Une fois ces difficultés résolues et dans les cas simples unidimensionnels traités pour le moment, la stratégie d'identification proposée s'avère très robuste face aux perturbations des mesures même dans le cas très sévère de la localisation et de la rupture.
Madani, Tarik. "Identification expérimentale de comportements élastoplastiques de matériaux hétérogènes pour des sollicitations complexes." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS173.
The present work follows a first approach where a strategy for identifying the shape and the parameters of cohesive-zone laws has been developed for homogeneous materials. The extension of this method to heterogeneous material requires the knowledge of the local stress state.The study aims at developing a local characterization method for mechanical properties and stresses. This method is based on the constitutive equation gap principles and relies on the knowledge of mechanical kinematic fields and particularly of the strain fields. These fields are obtained by the numerical differentiation of displacement fields measured by digital image correlation.This identification method is based on the iterative minimization of an energy norm involving the secant elastoplastic tensor. Various numerical simulations were used to illustrate the performance of the procedure for locally identifying heterogeneous property fields, and to characterize its robustness and its stability with respect to noise to the values of the algorithm initialization parameter and to the mesh refinement.Finally, various experimental tests with different specimen geometries were performed and a test has been developed to obtain a controlled heterogeneous initial state. The multilinear elastoplastic identification results showed the ability of the method to identify the local behavior properties on heterogeneous materials
Fu, Shuai. "Inversion probabiliste bayésienne en analyse d'incertitude." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00766341.
Romano, John. "Tracking error of leveraged and inverse etfs." Honors in the Major Thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/616.
B.S.B.A.
Bachelors
Business Administration
Finance
Hablot, Jean-Michel. "Construction de solutions exactes en élastoplasticité. Application à l'estimation d'erreur par apprentissage." Phd thesis, Ecole Nationale des Ponts et Chaussées, 1990. http://tel.archives-ouvertes.fr/tel-00518462.
Hablot, Jean-Michel. "Construction de solutions exactes en élastoplasticité. Application à l'estimation d'erreur par apprentissage." Phd thesis, Marne-la-vallée, ENPC, 1990. http://www.theses.fr/1990ENPC9012.
Kim, Sungsu. "Inverse circular regression with possibly asymmetric error distribution." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=90&did=1887560071&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270249121&clientId=48051.
Includes abstract. Includes bibliographical references (leaves 107-109). Issued in print and online. Available via ProQuest Digital Dissertations.
Sivira, Ramses. "Exploitation des mesures "vapeur d'eau" du satellite Megha-Tropiques pour l'élaboration d'un algorithme de restitution de profils associés aux fonctions de densité de probabilité de l'erreur conditionnelle." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-01025685.
Kite, Thomas David. "Design and quality assessment of forward and inverse error diffusion halftoning algorithms /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Carouge, Claire. "Vers une estimation des flux de CO2 journaliers européens à haute résolution par inversion du transport atmosphérique." Paris 6, 2006. http://www.theses.fr/2006PA066013.
LeÃo, JoÃosuà de ArÃa. "InfluÃncia de manobras de vÃlvulas na identificaÃÃo das rugosidades em tubulaÃÃes de redes de distribuiÃÃo de Ãgua." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13749.
Currently, based on computational analysis, more accurate assessments have been possible in studies of design of water supply networks. The hydraulic transient is a phenomenon that can affect all forced drainage system. Understanding this phenomenon and the constant search for solutions to avoid its harmful effects cause significant technological advances, principally through the application of computational methods. The present work is to use the Transient Inverse Method (TIM) with a genetic algorithm to calibrate the absolute roughness of pipes of two water distribution networks using four different types of maneuvers through genetic parameters. The study was done in two fictitious networks, but with physical characteristics of real networks. We analyzed the influence of valves maneuvers in the identification of roughness in pipes of water distribution networks. The simulations were made by varying two types of selection: elitism with and without elitism, considering the efficiency indicators: Average Relative Error (EMR), Relative Error (RE) and Objective Function (OF), where the results of the Network proved best for the relative error (RE) with elitism in four maneuvers. In network B, the best indicator of efficiency for the calibration of the four maneuvers was the mean relative error (EMR) with elitism and the indicators Relative Error (RE) and Objective Function (OF) vary according to the analyzed maneuver.
Narayanamurthi, Mahesh. "Advanced Time Integration Methods with Applications to Simulation, Inverse Problems, and Uncertainty Quantification." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/104357.
Doctor of Philosophy
The study of modern science and engineering begins with descriptions of a system of mathematical equations (a model). Different models require different techniques to both accurately and effectively solve them on a computer. In this dissertation, we focus on developing novel mathematical solvers for models expressed as a system of equations, where only the initial state and the rate of change of state as a function are known. The solvers we develop can be used to both forecast the behavior of the system and to optimize its characteristics to achieve specific goals. We also build methodologies to estimate and control errors introduced by mathematical solvers in obtaining a solution for models involving multiple interacting physical, chemical, or biological phenomena. Our solvers build on state of the art in the research community by introducing new approximations that exploit the underlying mathematical structure of a model. Where it is necessary, we provide concrete mathematical proofs to validate theoretically the correctness of the approximations we introduce and correlate with follow-up experiments. We also present detailed descriptions of the procedure for implementing each mathematical solver that we develop throughout the dissertation while emphasizing on means to obtain maximal performance from the solver. We demonstrate significant performance improvements on a range of models that serve as running examples, describing chemical reactions among distinct species as they diffuse over a surface medium. Also provided are results and procedures that a curious researcher can use to advance the ideas presented in the dissertation to other types of solvers that we have not considered. Research on mathematical solvers for different mathematical models is rich and rewarding with numerous open-ended questions and is a critical component in the progress of modern science and engineering.
Koohkan, Mohammad Reza, and Mohammad Reza Koohkan. "Multiscale data assimilation approaches and error characterisation applied to the inverse modelling ofatmospheric constituent emission fields." Phd thesis, Université Paris-Est, 2012. http://pastel.archives-ouvertes.fr/pastel-00807468.
Espinoza, Mario Sáenz. "Inverse kinematics of a 10 DOF modular hyper-redundant robot resorting to exhaustive and error-optimization methods (a comparative study)." Master's thesis, Instituto Politécnico de Bragança, Escola Superior de Tecnologia e Gestão, 2012. http://hdl.handle.net/10198/8027.
Chen, Jixin. "Some Domain Decomposition and Convex Optimization Algorithms with Applications to Inverse Problems." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/271782.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Camp, Brian David. "A Class of Immersed Finite Element Spaces and Their Application to Forward and Inverse Interface Problems." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29923.
Ph. D.
Tate, D. "A microprocessor controlled error switching inverter used in the uninterruptible power supply environment." Thesis, University of Bath, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275883.
Bampi, Carole. "Implications de la protéine de nucléocapside et de la transcriptase inverse dans la spécificité et les erreurs de la réplication des rétroéléments Ty1 et HIV-1." Lyon, École normale supérieure (sciences), 2005. http://www.theses.fr/2005ENSL0348.
Stephan, Anna [Verfasser], Denis Akademischer Betreuer] Belomestny, Volker [Akademischer Betreuer] Krätschmer, and John [Akademischer Betreuer] [Schoenmakers. "On an inverse problem of financial mathematics with error in the operator / Anna Stephan. Gutachter: Volker Krätschmer ; John Schoenmakers. Betreuer: Denis Belomestny." Duisburg, 2014. http://d-nb.info/1050348680/34.
Alarcon, Cot Albert. "Une approche de l'identification en dynamique des structures combinant l'erreur en relation de comportement et le filtrage de Kalman." Phd thesis, Ecole Polytechnique X, 2012. http://pastel.archives-ouvertes.fr/pastel-00724815.
Sheng, Jing Jing. "An error detection-based droop-boost control method for the capacitive-coupling grid-connected inverter." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691771.
Alarcon, Cot Albert. "Une approche de l'identification en dynamique des structures combinant l'erreur en relation de comportement et le filtrage de Kalman." Phd thesis, Palaiseau, Ecole polytechnique, 2012. https://pastel.hal.science/docs/00/72/48/15/PDF/these_Albert_Alarcon.pdf.
Error in Constitutive Relation (ECR) methods measure model error by evaluating the difference between admissible fields using an energy norm. This technique presents interesting features such as good ability to spatially localize erroneously modeled regions, strong robustness in presence of noisy data, and good regularity properties of cost functions. On the other hand, the Kalman filter (KF) is a prediction-correction algorithm for recursive system estimation. The KF is particularly suitable for studying evolutionary systems embedding noisy data from both model and observation. The main part of this work is devoted to establish and evaluate a general-purpose identification approach using ECR and KF. In order to achieve this goal, the ECR is initially used to improve the a priori knowledge of model errors. Furthermore, ECR functionals are introduced in a state-space description of the identification problem. Its resolution is performed by means of the Unscented Kalman Filter (UKF), a second-order, reduced-cost, Kalman filter. The adequacy of the ECR-UKF approach to address problems of industrial relevance is shown through different numerical examples and complex industrial cases, such as structural time-varying damage assessment, boundary conditions identification of in-operation structures and field reconstruction problems. Moreover, these examples are used to improve the performance of the ECR-UKF algorithm, particularly the introduction of algebraic constraints in the ECR-UKF algorithm and the influence of error covariance matrix design
Carlsson, Jesper. "Pontryagin approximations for optimal design." Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4089.
Costa, BÃrbara Cristina Alves da. "Load measurement error influence on friction factor calibration of pipe water distribution networks through do reverse transient method and genetic algorithm." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13621.
The study of hydraulic networks for operation purposes or viability analysis for extension or renovation of the same is started the calibration in this context understood as identification parameters, such as friction coefficient, surface roughness and diameter. The Transient Inverse Method in conjunction with genetic algorithm is efficient in this task shows. This method employs the method of characteristics in the solution of the equations of motion for transient flow in networks of pipes and the optimization of solutions is based on Evolutionary Theory and evaluated by an objective function, which in this study is the sum of the difference between the module loads measured and calculated by the model for each set of solutions. Whereas the objective of the development of mathematical models for calibration hypothetical networks is their use in real networks, and that these, the collection of payload data is subject to measurement errors, is due to defects in the equipment or by conditions unfavorable environment or other random effects and taking into account the relevance of friction factors in pipelines, by their relationship to head losses that must be controlled to a great operation of networks, ensuring a continuous supply in quantity and appropriate operating conditions, this work is proposed to verify the influence of the presence of transient load measurement errors in the identification of friction factors in two hypothetical hydraulic networks. They are of different sizes with the number of rings, knots and tubes. Both are each fed by a reservoir. The transient conditions are assigned to a valve maneuver installed in one of the nodes of each network. The load data collection is restricted to 20% of the nodes in each network, one of which is the node where the valve is located. The hydraulic transient observation time is restricted to the valve maneuver time, 20s, and occurs at intervals of 0.1s, resulting in 200 charge records. The permanent condition of networks is initially unknown knowledge about the same is restricted to load in the reservoirs and demands on us as well as pipe diameter, the friction factors are initially stipulated. The determination of the permanent and transient conditions and the identification of the friction factors is performed using a hydraulic model and generate transient loads which are conventionally considered true, then these various steps of receiving systematic and random errors, which generate new burdens and these are considered collected with measurement errors. From these new loads are carried IDs friction factors, which are compared with those obtained considering an ideal case with no measurement errors loads. This comparison is performed using the mean relative error and function great goal. The results show that measurement errors in the identification of interfering friction factors although not possible to draw a relationship between them.
Ozhamam, Murat. "Accuracy And Efficiency Improvements In Finite Difference Sensitivity Calculations." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12609128/index.pdf.
Shikhar. "COMPRESSIVE IMAGING FOR DIFFERENCE IMAGE FORMATION AND WIDE-FIELD-OF-VIEW TARGET TRACKING." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/194741.
Guo, Ruchi. "Design, Analysis, and Application of Immersed Finite Element Methods." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90374.
Doctor of Philosophy
Interface problems arise from many science and engineering applications modeling the transmission of some physical quantities between multiple materials. Mathematically, these multiple materials in general are modeled by partial differential equations (PDEs) with discontinuous parameters, which poses challenges to developing efficient and reliable numerical methods and the related theoretical error analysis. The main contributions of this dissertation is on the development of a special finite element method, the so called immersed finite element (IFE) method, to solve the interface problems on a mesh independent of the interface geometry which can be advantageous especially when the interface is moving. Specifically, this dissertation consists of three projects of IFE methods: elasticity interface problems, higher-order IFE methods and interface inverse problems, including their design, analysis, and application.
Richardson, Omar. "Mathematical analysis and approximation of a multiscale elliptic-parabolic system." Licentiate thesis, Karlstads universitet, Institutionen för matematik och datavetenskap (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-68686.
Sandberg, Henrik. "Linear Time-Varying Systems: Modeling and Reduction." Licentiate thesis, Lund University, Department of Automatic Control, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-74720.
QC 20120208
Akbari, Ali. "Modélisation parcimonieuse des signaux : application a la compression d'image, compensation d'erreurs et à l'acquisition comprimée." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS461.pdf.
Signal models are a cornerstone of contemporary signal and image processing methodology. In this report, two particular signal modeling methods, called analysis and synthesis sparse representation, are studied which have been proven to be effective for many signals, such as natural images, and successfully used in a wide range of applications. Both models represent signals in terms of linear combinations of an underlying set, called dictionary, of elementary signals known as atoms. The driving force behind both models is sparsity of the representation coefficients, i.e. the rapid decay of the representation coefficients over the dictionary. On the other hands, the dictionary choice determines the success of the entire model. According to these two signal models, there have been two main disciplines of dictionary designing; harmonic analysis approach and machine learning methodology. The former leads to designing the dictionaries with easy and fast implementation, while the latter provides a simple and expressive structure for designing adaptable and efficient dictionaries. The main goal of this thesis is to provide new applications to these signal modeling methods by addressing several problems from various perspectives. It begins with the direct application of the sparse representation, i.e. image compression. The line of research followed in this area is the synthesis-based sparse representation approach in the sense that the dictionary is not fixed and predefined, but learned from training data and adapted to data, yielding a more compact representation. A new Image codec based on adaptive sparse representation over a trained dictionary is proposed, wherein different sparsity levels are assigned to the image patches belonging to the salient regions, being more conspicuous to the human visual system. Experimental results show that the proposed method outperforms the existing image coding standards, such as JPEG and JPEG2000, which use an analytic dictionary, as well as the state-of-the-art codecs based on the trained dictionaries. In the next part of thesis, it focuses on another important application of the sparse signal modeling, i.e. solving inverse problems, especially for error concealment (EC), wherein a corrupted image is reconstructed from the incomplete data, and Compressed Sensing recover, where an image is reconstructed from a limited number of random measurements. Signal modeling is usually used as a prior knowledge about the signal to solve these NP-hard problems. In this thesis, inspired by the analysis and synthesis sparse models, these challenges are transferred into two distinct sparse recovery frameworks and several recovery methods are proposed. Compared with the state-of-the-art EC and CS algorithms, experimental results show that the proposed methods show better reconstruction performance in terms of objective and subjective evaluations. This thesis is finalized by giving some conclusions and introducing some lines for future works
Nilsson, Martin. "Fast Numerical Techniques for Electromagnetic Problems in Frequency Domain." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3884.
Penin, Fernandez Natalia <1976>. "La competencia lexicografica y su influencia en el error en la traduccion inversa italiano espa?ol. Propuesta de formacion en modalidad SPOC para la adquisicion de la competencia lexicografica en la didactica de la traduccion no especializada." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9230/1/Tesis%20depositada%20UNIBO_La%20competencia%20lexicogra%CC%81fica%20y%20su%20influencia%20en%20el%20error%20...%20.pdf.
La presente tesi, sviluppata nel Dipartimento di Traduzione, Interpretazione e Interculturalità dell'Università di Bologna in cotutela con l'Área de Traducción e Interpretación —Departamento de Lengua Española— della Universidad de Valladolid, si inquadra nell’ambito disciplinare della Didattica della traduzione e si concentra sullo studio dell'errore e del suo rapporto con la competenza lessicografica nella traduzione attiva non specializzata. I suoi due obiettivi principali sono, da un lato, ottenere la tipizzazione e la frequenza degli errori di traduzione attraverso un corpus composto dagli esercizi presentati dagli studenti di Traduzione dall'italiano allo spagnolo e, dall'altro, progettare una proposta pedagogica in modalità SPOC per sviluppare le competenze lessicografiche degli studenti e realizzare un corso pilota in aula per convalidarla. Per questa ragione, la tesi è divisa in due parti. La prima, si basa sul corpus TRADITES e consiste nella sua compilazione e analisi quantitativa e qualitativa. Nella seconda parte, sulla base dei risultati dell'analisi, è stata elaborata una proposta pedagogica in modalità SPOC sull'introduzione alle risorse lessicografiche monolingui e bilingui di due lingue correlate —italiano e spagnolo— al fine di sviluppare in aula la competenza lessicografica degli studenti. Successivamente, la proposta è stata convalidata attraverso l'implementazione di un corso pilota in classe. I risultati confermano che nella traduzione attiva la difficoltà maggiore risiede nella fase di riproduzione del testo nella lingua di arrivo e non nella fase di comprensione come nella traduzione diretta. Un'immediata deduzione dall’analisi qualitativa conferma che parte dei problemi alla base degli errori linguistici rilevati trovano una possibile soluzione “nell’uso intelligente" delle opere lessicografiche consultate.
This thesis, developed in the Department of Translation, Interpretation and Interculturality of the University of Bologna and the Universidad de Valladolid, is part of the disciplinary field of Translation Teaching and focuses on the study of error and its relationship with lexicographic competence in active non-specialized translation. Its two main objectives are, on the one hand, to obtain the typing and the frequency of translation errors through a corpus consisting of the exercises presented by the translation students from Italian to Spanish and, on the other, to design a pedagogical proposal in SPOC mode to develop students' lexicographical skills and carry out a pilot classroom course to validate it. The thesis is divided into two parts. The first is based on the TRADITES corpus and consists of its compilation and quantitative and qualitative analysis. In the second part, based on the results of the analysis, was developed a pedagogical proposal in SPOC mode on the introduction to monolingual and bilingual lexicographic resources of two related languages - Italian and Spanish - in order to develop the students' lexicographic competence in the classroom. Subsequently, the proposal was validated through the implementation of a pilot course in the classroom. The results confirm that in reverse translation the greatest difficulty lies in the reproduction of the text in the target language and not in the comprehension phase as in direct translation. An immediate deduction from the qualitative analysis confirms that part of the problems underlying the detected linguistic errors find a possible solution "in the intelligent use" of the lexicographic works consulted
Maršálek, Tomáš. "Návrh vyhledávacího systému pro moderní potřeby." Master's thesis, Vysoká škola ekonomická v Praze, 2016. http://www.nusl.cz/ntk/nusl-262227.
Nyman, Peter. "On relations between classical and quantum theories of information and probability." Doctoral thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-13830.
Wikström, Gunilla. "Computation of Parameters in some Mathematical Models." Doctoral thesis, Umeå University, Computing Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-565.
In computational science it is common to describe dynamic systems by mathematical models in forms of differential or integral equations. These models may contain parameters that have to be computed for the model to be complete. For the special type of ordinary differential equations studied in this thesis, the resulting parameter estimation problem is a separable nonlinear least squares problem with equality constraints. This problem can be solved by iteration, but due to complicated computations of derivatives and the existence of several local minima, so called short-cut methods may be an alternative. These methods are based on simplified versions of the original problem. An algorithm, called the modified Kaufman algorithm, is proposed and it takes the separability into account. Moreover, different kinds of discretizations and formulations of the optimization problem are discussed as well as the effect of ill-conditioning.
Computation of parameters often includes as a part solution of linear system of equations Ax = b. The corresponding pseudoinverse solution depends on the properties of the matrix A and vector b. The singular value decomposition of A can then be used to construct error propagation matrices and by use of these it is possible to investigate how changes in the input data affect the solution x. Theoretical error bounds based on condition numbers indicate the worst case but the use of experimental error analysis makes it possible to also have information about the effect of a more limited amount of perturbations and in that sense be more realistic. It is shown how the effect of perturbations can be analyzed by a semi-experimental analysis. The analysis combines the theory of the error propagation matrices with an experimental error analysis based on randomly generated perturbations that takes the structure of A into account
Erdogan, Ahmet Yasin. "Analysis of the effects of phase noise and frequency offset in orthogonal frequency division multiplexing (OFDM) systems." Thesis, Monterey California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1712.
Orthogonal frequency division multiplexing (OFDM) is being successfully used in numerous applications. It was chosen for IEEE 802.11a wireless local area network (WLAN) standard, and it is being considered for the fourthgeneration mobile communication systems. Along with its many attractive features, OFDM has some principal drawbacks. Sensitivity to frequency errors is the most dominant of these drawbacks. In this thesis, the frequency offset and phase noise effects on OFDM based communication systems are investigated under a variety of channel conditions covering both indoor and outdoor environments. The simulation performance results of the OFDM system for these channels are presented.
Lieutenant Junior Grade, Turkish Navy
Li, Qiaochu. "Contribution à la planification d'expériences, à l'estimation et au diagnostic actif de systèmes dynamiques non linéaires : application au domaine aéronautique." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2231/document.
In this work, we will study the uncertainty integration problem in a bounded error context for the dynamic systems, whose input and the initial state have to be optimized so that some other operation could be more easily and better obtained. This work is consisted of 6 chapters : the chapter 1 is an introduction to the general subject which we will discuss about. The chapter 2 represents the basic tools of interval analysis.The chapter 3 is dedicated to state estimation and parameter estimation. We explain at the first, how to solve the ordinary differential equation using interval analysis, which will be the basic tool for the state estimation problem given the initial condition of studied systems. On the other ride, we will look into the parameter estimation problem using interval analysis too. Based on a simple hypothesis over the uncertain variable, we calculate the system's parameter in a bounded error form, considering the operation of intervals as the operation of sets. Guaranteed results are the advantage of interval analysis, but the big time consumption is still a problem for its popularization in many non linear estimation field. We present our founding techniques to accelerate this time consuming processes, which are called contractor in constraint propagation field. At the end of this chapter, différent examples will be the test proof for our proposed methods.Chapter 4 presents the searching for optimal input in the context of interval analysis, which is an original approach. We have constructed several new criteria allow such searching. Some of them are intuitive, the other need a theoretical proof. These criteria have been used for the search of optimal initial States and le better parameter estimation results. The comparisons are done by using multiple applications and the efficiency is proved by evidence.In chapter 5, we applied the approaches proposed above in diagnosis by state estimation and parameter estimation. We have developed a complete procedure for the diagnosis. The optimal input design has been reconsidered in an active diagnosis context. Both state and parameter estimation are implemented using an aeronautical application in literature.The last chapter given a brief summary over the realized subject, some further research directions are given in the perspective section.All the algorithms are written in C/C++ on a Linux based operation system
Saleem, Rashid. "Towards an end-to-end multiband OFDM system analysis." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/towards-an-endtoend-multiband-ofdm-system-analysis(e711f32f-1ac6-4b48-8f4e-58309c0482d3).html.
Стрембіцький, Михайло Олексійович, and Michael Strembitskyy. "Нейромережеві технології підвищення точності вимірювання та керування в системах наведення антен." Thesis, Тернопільський національний технічний університет ім. Івана Пулюя, 2016. http://elartu.tntu.edu.ua/handle/123456789/15664.
Дисертацію присвячено вирішенню наукового завдання підвищення точності вимірювання та керування в системах наведення антен із використанням нейромережевих технологій. Проаналізовано тенденції розвитку систем керування наведенням антен. Зроблено висновки про процес налаштування параметрів класичного ПІД- регулятора, який потребує побудови детальної моделі системи керування антени. Проведений огляд підходів до застосування нейронних мереж у моделюванні динамічних систем. Запропоновано використання рекурентної нейронної мережі для побудови контролера наведення антени. Запропоновано метод ідентифікації параметрів антени, реалізація якого потребує подання на вхід тестових сигналів та врахування перехідного процесу. Такий спосіб дозволяє формувати послідовності для проведення навчання нейромережевого контролера наведення антени. Запропонована схема навчання нейронної мережі, яка відтворює інверсну динаміку антени, використана для синтезу контролера керування антеною. Використання модифікованої нейронної мережі Елмана підвищило точність керування антеною порівняно із розрахованим та налаштованим аналітичним методом ПІД-регулятором. На основі отриманих результатів розроблено розподілену систему для керування антеною. Навчання нейромережевого контролера для запропонованої системи проведено шляхом відтворення інверсної динаміки самого об’єкту керування.
Диссертация посвящена решению научной задачи повышения точности измерения и управления в системах наведения антенн с использованием нейросетевых технологий. Проанализированы тенденции развития систем управления для наведения антенн. Сделаны выводы о процессе настройки параметров классического ПИД-регулятора, который требует построения детальной модели системы управления антенны. Проведенный обзор подходов к применению НС в моделировании динамических систем. Предложено использование рекуррентной нейронной сети для построения контроллера наведения антенны. Использование наследуемого нейроуправления не обеспечивает желаемого результата, так как погрешность регулирования не может принимать значения менее чем при управлении с применением эталонной модели. В отличие от наследуемого нейроуправления реализация инверсного нейрокерування не требует использования эталонной модели контроллера управления, а модель для формирования обучающей выборки формируют на основе идентификационной модели объекта управления. Предложен метод идентификации параметров антенны, реализация которого требует представления на вход тестовых сигналов и учета переходного процесса. Такой подход позволил формировать последовательности для проведения обучения нейросетевого контроллера наведения антенны. Предложено использование контроллера на основе рекуррентной НС для наведения антенны, который путем реализации нейросетевого эмулятора обеспечивает отображение инверсной динамики системы наведения антенны, не требует знания точной математической модели управляемого объекта и позволяет избежать громоздких расчетов на стадии описания модели управления. Проведено моделирование работы нейросетевого контроллера наведения антенны и проведение идентификации антенной установки с использованием рекуррентной НС Элмана. Предложен метод выбора способа обучения рекуррентной НС Элмана для наведения антенны, при воспроизведении инверсной динамики управляемого объекта, который обеспечивает уменьшение погрешности при проведении обучения синтезированной нейросетевой структуры. Предложенная схема обучения нейронной сети для воспроизведения инверсной динамики антенны была использована для синтеза контроллера управления антенной. Усовершенствован метод синтеза нейроконтроллера управления антенным устройством на основе рекуррентной нейронной сети Элмана введением глобальных обратных связей, что позволило повысить точность управления при сопровождении антенной системой тестовой траектории на 3,7% по сравнению с рассчитанным и настроенным аналитическим методом ПИД-регулятором. Усовершенствован метод управления вводом антенной установки для распределенной системы, путем использования рекуррентной нейронной сети. Обучена воспроизводить инверсную динамику антенной системы НС-регулятор повысил быстродействие системы на 3%, по сравнению с настроенным ПИД-регулятором. Результаты исследования использованы для нейросетевого контроллера, синтезированного средствами Matlab, и который через последовательный интерфейс считывает текущее значение положения осей антенной системы и производит управляющую действие для сопровождения и наведения АС, может быть использовано для управления и сопровождения по траектории в системах наведения реальных антенн. На основе полученных результатов разработано распределенную систему для управления антенной. Обучение нейросетевого контроллера для предложенной системы проводили, путем воспроизведения инверсной динамики самого объекта управления.
Dissertation is sanctified to the decision of scientific task of increase of efficiency of aiming of antenna complexes of accompaniment of space objects. Basic factors that influence on exactness of management of antenna complexes are analyzed, using of neural network is offered as an identifier of dynamic object that recreates the mechanical part of the antenna system and allows to estimate work of neural network. The use of recurrent neural networks is offered for the management of dynamic objects, in particular by the antenna complexes of accompaniment of space objects. The use of the modified Elman neural network is reasonable for the construction of regulator in the contour of aiming of the aerial system, the optimal number of neurons in the intermediate layer of neural network is defined and an effective algorithm for realization of adjustment of weight and displacements of neural network is offered. A hold neural network training using identity management model of the object, thus forming sequence for inputs and set the system into line output value. Based on developed a distributed system designed to control antenna. Training neural network controller for the proposed system was performed conducted by inverse dynamics of reproduction facility management.