Letteratura scientifica selezionata sul tema "Analyse de sensibilité (indice de Sobol)"
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Articoli di riviste sul tema "Analyse de sensibilité (indice de Sobol)":
Séguis, L., e J. C. Bader. "Modélisation du ruissellement en relation avec l'évolution saisonnière de la végétation (mil, arachide, jachère) au centre Sénégal". Revue des sciences de l'eau 10, n. 4 (12 aprile 2005): 419–38. http://dx.doi.org/10.7202/705287ar.
Rossel, F., P. Le Goulven e E. Cadier. "Répartition spatiale de l'influence de l'ENSO sur les précipitations annuelles en Équateur". Revue des sciences de l'eau 12, n. 1 (12 aprile 2005): 183–200. http://dx.doi.org/10.7202/705348ar.
Tesi sul tema "Analyse de sensibilité (indice de Sobol)":
Chastaing, Gaëlle. "Indices de Sobol généralisés par variables dépendantes". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENM046.
A mathematical model aims at characterizing a complex system or process that is too expensive to experiment. However, in this model, often strongly non linear, input parameters can be affected by a large uncertainty including errors of measurement of lack of information. Global sensitivity analysis is a stochastic approach whose objective is to identify and to rank the input variables that drive the uncertainty of the model output. Through this analysis, it is then possible to reduce the model dimension and the variation in the output of the model. To reach this objective, the Sobol indices are commonly used. Based on the functional ANOVA decomposition of the output, also called Hoeffding decomposition, they stand on the assumption that the incomes are independent. Our contribution is on the extension of Sobol indices for models with non independent inputs. In one hand, we propose a generalized functional decomposition, where its components is subject to specific orthogonal constraints. This decomposition leads to the definition of generalized sensitivity indices able to quantify the dependent inputs' contribution to the model variability. On the other hand, we propose two numerical methods to estimate these constructed indices. The first one is well-fitted to models with independent pairs of dependent input variables. The method is performed by solving linear system involving suitable projection operators. The second method can be applied to more general models. It relies on the recursive construction of functional systems satisfying the orthogonality properties of summands of the generalized decomposition. In parallel, we illustrate the two methods on numerical examples to test the efficiency of the techniques
Gayrard, Emeline. "Analyse bayésienne de la gerbe d'éclats provoquée pa l'explosion d'une bombe à fragmentation naturelle". Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC039/document.
During this thesis, a method of statistical analysis on sheaf of bomb fragments, in particular on their masses, has been developed. Three samples of incomplete experimental data and a mechanical model which simulate the explosion of a ring were availables. First, a statistical model based on the mechanical model has been designed, to generate data similar to those of an experience. Then, the distribution of the masses has been studied. The classical methods of analysis being not accurate enough, a new method has been developed. It consists in representing the mass by a random variable built from a basis of chaos polynomials. This method gives good results however it doesn't allow to take into account the link between slivers. Therefore, we decided to model the masses by a stochastic process, and not a random variable. The range of fragments, which depends of the masses, has also been modeled by a process. Last, a sensibility analysis has been carried out on this range with Sobol indices. Since these indices are applied to random variables, it was necessary to adapt them to stochastic process in a way that take into account the links between the fragments. In the last part, it is shown how the results of this analysis could be improved. Specifically, the indices presented in the last part are adapted to dependent variables and therefore, they could be suitable to processes with non independent increases
Chastaing, Gaëlle. "Indices de Sobol généralisés pour variables dépendantes". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00930229.
Kamari, Halaleh. "Qualité prédictive des méta-modèles construits sur des espaces de Hilbert à noyau auto-reproduisant et analyse de sensibilité des modèles complexes". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE010.
In this work, the problem of estimating a meta-model of a complex model, denoted m, is considered. The model m depends on d input variables X1 , ..., Xd that are independent and have a known law. The meta-model, denoted f ∗ , approximates the Hoeffding decomposition of m, and allows to estimate its Sobol indices. It belongs to a reproducing kernel Hilbert space (RKHS), denoted H, which is constructed as a direct sum of Hilbert spaces (Durrande et al. (2013)). The estimator of the meta-model, denoted f^, is calculated by minimizing a least-squares criterion penalized by the sum of the Hilbert norm and the empirical L2-norm (Huet and Taupin (2017)). This procedure, called RKHS ridge group sparse, allows both to select and estimate the terms in the Hoeffding decomposition, and therefore, to select the Sobol indices that are non-zero and estimate them. It makes possible to estimate the Sobol indices even of high order, a point known to be difficult in practice.This work consists of a theoretical part and a practical part. In the theoretical part, I established upper bounds of the empirical L2 risk and the L2 risk of the estimator f^. That is, upper bounds with respect to the L2-norm and the empirical L2-norm for the f^ distance between the model m and its estimation f into the RKHS H. In the practical part, I developed an R package, called RKHSMetaMod, that implements the RKHS ridge group sparse procedure and a spacial case of it called the RKHS group lasso procedure. This package can be applied to a known model that is calculable in all points or an unknown regression model. In order to optimize the execution time and the storage memory, except for a function that is written in R, all of the functions of the RKHSMetaMod package are written using C++ libraries GSL and Eigen. These functions are then interfaced with the R environment in order to propose an user friendly package. The performance of the package functions in terms of the predictive quality of the estimator and the estimation of the Sobol indices, is validated by a simulation study
Tissot, Jean-yves. "Sur la décomposition ANOVA et l'estimation des indices de Sobol'. Application à un modèle d'écosystème marin". Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENM064/document.
In the fields of modelization and numerical simulation, simulators generally depend on several input parameters whose impact on the model outputs are not always well known. The main goal of sensitivity analysis is to better understand how the model outputs are sensisitive to the parameters variations. One of the most competitive method to handle this problem when complex and potentially highly non linear models are considered is based on the ANOVA decomposition and the Sobol' indices. More specifically the latter allow to quantify the impact of each parameters on the model response. In this thesis, we are interested in the issue of the estimation of the Sobol' indices. In the first part, we revisit in a rigorous way existing methods in light of discrete harmonic analysis on cyclic groups and randomized orthogonal arrays. It allows to study theoretical properties of this method and to intriduce generalizations. In a second part, we study the Monte Carlo method for the Sobol' indices and we introduce a new approach to reduce the number of simulations of this method. In parallel with this theoretical work, we apply these methods on a marine ecosystem model
Tissot, Jean-Yves. "Sur la décomposition ANOVA et l'estimation des indices de Sobol'. Application à un modèle d'écosystème marin". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00762800.
Jannet, Basile. "Influence de la non-stationnarité du milieu de propagation sur le processus de Retournement Temporel (RT)". Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22436/document.
The aim of this thesis is to measure and quantify the impacts of uncertainties in the Time Reversal (TR) process. These random variations, coming from diverse sources, can have a huge influence if they happen between the TR steps. On this perspective, the Stochastique Collocation (SC) method is used. Very good results in terms of effectiveness and accuracy had been noticed in previous studies in ElectroMagnetic Compatibility (EMC). The conclusions are still excellent here on TR problems. Although, when the problem dimension rises (high number of Random Variables (RV)), the SC method reaches its limits and the efficiency decreases. Therefore a study on Sensitivity Analysis (SA) techniques has been carried out. Indeed, these methods emphasize the respective influences of the random variables of a model. Among the various quantitative or qualitative SA techniques the Morris method and the Sobol total sensivity indices have been adopted. Since only a split of the inputs (point out of the predominant RV) is expected, they bring results at a lesser cost. That is why a novel method is built, combining SA techniques and the SC method. In a first step, the model is reduced with SA techniques. Then, the shortened model in which only the prevailing inputs remain, allows the SC method to show once again its efficiency with a high accuracy. This global process has been validated facing Monte Carlo results on several analytical and numerical TR cases subjet to random variations
Andrianandraina. "Approche d'éco-conception basée sur la combinaison de l'analyse de cycle de vie et de l'analyse de sensibilité : Cas d'application sur le cycle de vie du matériau d'isolation thermique biosourcé, le béton de chanvre". Ecole centrale de Nantes, 2014. http://www.theses.fr/2014ECDN0005.
The purpose of this PhD thesis is to establish an ecodesign method based on Life Cycle Assessment, that should allow identifying action levers specific for each economic actor of the life cycle of a product, for improved environmental performances. Life Cycle Assessment was coupled with two methods of sensitivity analysis in five steps: (i) definition of objectives and system, (ii) modeling calculation of inventory and impact indicators with different approaches according to foreground and background sub-systems, (iii) characterization of parameters using a typology specific to possibilities of control of the considered economic actor, (iv) application of two sensitivity analysis methods (Morris and Sobol) and (v) results interpretation in order to identify potential efficient improvements. The approach was applied on the hemp concrete insulation product, including agricultural production, industrial transformation of hemp fibers, and use of hemp concrete as a thermal insulator for buildings. The approach provides potential technological scenarios improving environmental performances for each single economic actor of the product’s life cycle. Performing the method presently requires additional information, but will probably be paid back in the future by driving more robust choices for a given product
Gilquin, Laurent. "Échantillonnages Monte Carlo et quasi-Monte Carlo pour l'estimation des indices de Sobol' : application à un modèle transport-urbanisme". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAM042/document.
Land Use and Transportation Integrated (LUTI) models have become a norm for representing the interactions between land use and the transportation of goods and people in a territory. These models are mainly used to evaluate alternative planning scenarios, simulating their impact on land cover and travel demand.LUTI models and other mathematical models used in various fields are most of the time based on complex computer codes. These codes often involve poorly-known inputs whose uncertainty can have significant effects on the model outputs.Global sensitivity analysis methods are useful tools to study the influence of the model inputs on its outputs. Among the large number of available approaches, the variance based method introduced by Sobol' allows to calculate sensitivity indices called Sobol' indices. These indices quantify the influence of each model input on the outputs and can detect existing interactions between inputs.In this framework, we favor a particular method based on replicated designs of experiments called replication method. This method appears to be the most suitable for our application and is advantageous as it requires a relatively small number of model evaluations to estimate first-order or second-order Sobol' indices.This thesis focuses on extensions of the replication method to face constraints arising in our application on the LUTI model Tranus, such as the presence of dependency among the model inputs, as far as multivariate outputs.Aside from that, we propose a recursive approach to sequentially estimate Sobol' indices. The recursive approach is based on the iterative construction of stratified designs, latin hypercubes and orthogonal arrays, and on the definition of a new stopping criterion. With this approach, more accurate Sobol' estimates are obtained while recycling previous sets of model evaluations. We also propose to combine such an approach with quasi-Monte Carlo sampling.An application of our contributions on the LUTI model Tranus is presented
Causse, Mathieu. "Contributions à l'extension de la méthode des Sparse Grids pour les calculs de fiabilité en modélisation de processus". Toulouse 3, 2010. http://www.theses.fr/2010TOU30336.
The aim of this thesis is to show the efficiency of Sparse Grid approximation method applied to high dimensional real-life problems. For that kind of problems main parameters detection is fundamental. First we introduce Sparse Grid approximation method and emphasize its adaptive form. Then we show the efficiency of the method on standard test functions to show Sparse Grid specificities in main parameters detection. Due to excellent performance properties of the method, we apply it to a real-life problem and obtain accurate results with a reduced computation cost. The first application is dedicated to a pollutant diffusion problem, the second one aims to evaluate the performance of a power network
Capitoli di libri sul tema "Analyse de sensibilité (indice de Sobol)":
DUBREUIL, Sylvain, Nathalie BARTOLI, Christian GOGU e Thierry LEFEBVRE. "Réduction d’incertitudes en analyse multidisciplinaire basée sur une étude de sensibilité par chaos polynomial". In Ingénierie mécanique en contexte incertain, 121–50. ISTE Group, 2021. http://dx.doi.org/10.51926/iste.9010.ch4.
CHABRIDON, Vincent, Mathieu BALESDENT, Guillaume PERRIN, Jérôme MORIO, Jean-Marc BOURINET e Nicolas GAYTON. "Analyse de sensibilité globale ciblée pour la fiabilité en présence d’incertitudes sur les paramètres de distribution". In Ingénierie mécanique en contexte incertain, 255–304. ISTE Group, 2021. http://dx.doi.org/10.51926/iste.9010.ch7.