Détail de l'auteur
|
|
Documents disponibles écrits par cet auteur (5)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externesDirect measurement of evapotranspiration from a forest using a superconducting gravimeter / Michel Van Camp in Geophysical research letters, vol 43 n° 19 (15 October 2016)
Titre : Direct measurement of evapotranspiration from a forest using a superconducting gravimeter Type de document : Article/Communication Auteurs : Michel Van Camp, Auteur ; Olivier de Viron, Auteur ; Gwendoline Pajot-Métivier Année de publication : 2016 Article en page(s) : pp 10225 - 10231 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Belgique
[Termes IGN] évapotranspiration
[Termes IGN] feuillu
[Termes IGN] forêt tempérée
[Termes IGN] gravimètre supraconducteur
[Termes IGN] humidité du sol
[Termes IGN] levé gravimétrique
[Termes IGN] variation diurneRésumé : (auteur) Evapotranspiration (ET) controls the flux between the land surface and the atmosphere. Assessing the ET ecosystems remains a key challenge in hydrology. We have found that the ET water mass loss can be directly inferred from continuous gravity measurements: as water evaporates and transpires from terrestrial ecosystems, the mass distribution of water decreases, changing the gravity field.
Using continuous superconducting gravity measurements, we were able to identify daily gravity changes at the level of, or smaller than 10-9 nm.s-2 (or 10-10 g) per day. This corresponds to 1.7 mm of water over an area of 50 ha. The strength of this method is its ability to enable a direct, traceable and continuous monitoring of actual ET for years at the mesoscale with a high accuracy.Numéro de notice : A2016-684 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2016GL070534 Date de publication en ligne : 07/10/2016 En ligne : http://dx.doi.org/10.1002/2016GL070534 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81973
in Geophysical research letters > vol 43 n° 19 (15 October 2016) . - pp 10225 - 10231[article]Documents numériques
peut être téléchargé
Direct measurement of evapotranspiration ... - pdf éditeurAdobe Acrobat PDF
Titre : Fast computation of general forward gravitation problems Type de document : Article/Communication Auteurs : Fabien Casenave Année de publication : 2016 Article en page(s) : pp 655 – 675 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] France (géographie physique)
[Termes IGN] masse de la Terre
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] vitesseRésumé : (auteur) We consider the well-known problem of the forward computation of the gradient of the gravitational potential generated by a mass density distribution of general 3D geometry. Many methods have been developed for given geometries, and the computation time often appears as a limiting practical issue for considering large or complex problems. In this work, we develop a fast method to carry out this computation, where a tetrahedral mesh is used to model the mass density distribution. Depending on the close- or long-range nature of the involved interactions, the algorithm automatically switches between analytic integration formulae and numerical quadratic formulae, and relies on the Fast Multipole Method to drastically increase the computation speed of the long-range interactions. The parameters of the algorithm are empirically chosen for the computations to be the fastest possible while guarantying a given relative accuracy of the result. Computations that would load many-core clusters for days can now be carried out on a desk computer in minutes. The computation of the contribution of topographical masses to the Earth’s gravitational field at the altitude of the GOCE satellite and over France are proposed as numerical illustrations of the method. Numéro de notice : A2016-427 Affiliation des auteurs : LASTIG LAREG (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0900-2 Date de publication en ligne : 08/04/2016 En ligne : http://dx.doi.org/ 10.1007/s00190-016-0900-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81321
in Journal of geodesy > vol 90 n° 7 (July 2016) . - pp 655 – 675[article]
Titre : Variants of the empirical interpolation method: symmetric formulation, choice of norms and rectangular extension Type de document : Article/Communication Auteurs : Fabien Casenave Année de publication : 2016 Article en page(s) : pp Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse numérique
[Termes IGN] approximation
[Termes IGN] interpolationRésumé : (auteur) The Empirical Interpolation Method (EIM) is a greedy procedure that constructs approximate representations of two-variable functions in separated form. In its classical presentation, the two variables play a non-symmetric role. In this work, we give an equivalent definition of the EIM approximation, in which the two variables play symmetric roles. Then, we give a proof for the existence of this approximation, and extend it up to the convergence of the EIM, and for any norm chosen to compute the error in the greedy step. Finally, we introduce a way to compute a separated representation in the case where the number of selected values is different for each variable. In the case of a physical field measured by sensors, this is useful to discard a broken sensor while keeping the information provided by the associated selected field. Numéro de notice : A2016--173 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.aml.2015.11.010 Date de publication en ligne : 07/12/2015 En ligne : https://doi.org/10.1016/j.aml.2015.11.010 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91780
in Applied Mathematics Letters > vol 56 (June 2016) . - pp[article]
Titre : Boundary element and finite element coupling for aeroacoustics simulations Type de document : Article/Communication Auteurs : Nolwenn Balin, Auteur ; Fabien Casenave Année de publication : 2015 Article en page(s) : pp 274 - 296 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse numérique
[Termes IGN] méthode des éléments finisRésumé : (auteur) We consider the scattering of acoustic perturbations in the presence of a flow. We suppose that the space can be split into a zone where the flow is uniform and a zone where the flow is potential. In the first zone, we apply a Prandtl–Glauert transformation to recover the Helmholtz equation. The well-known setting of boundary element method for the Helmholtz equation is available. In the second zone, the flow quantities are space dependent, we have to consider a local resolution, namely the finite element method. Herein, we carry out the coupling of these two methods and present various applications and validation test cases. The source term is given through the decomposition of an incident acoustic field on a section of the computational domain's boundary. Validations against analytic, another numerical method and measurements on different test cases are presented. Numéro de notice : A2015-003 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.jcp.2015.03.044 Date de publication en ligne : 31/03/2015 En ligne : https://doi.org/10.1016/j.jcp.2015.03.044 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93241
in Journal of Computational Physics > vol 294 [01/08/2015] . - pp 274 - 296[article]
Titre : A fast summation method for translation invariant kernels Type de document : Article/Communication Auteurs : Fabien Casenave Editeur : Ithaca [New York - Etats-Unis] : ArXiv - Université Cornell Année de publication : 2015 Importance : 19 p. Format : 21 x 30 cm Note générale : arXiv:1408.0210v3 [math.NA] 22 Aug 2015
ex titre : An Empirical Interpolation based Fast Summation Method for translation invariant kernelsLangues : Anglais (eng) Descripteur : [Termes IGN] méthode fondée sur le noyau Résumé : (auteur) We derive a Fast Multipole Method (FMM) where a low-rank approximation of the kernel is obtained using the Empirical Interpolation Method (EIM). Contrary to classical interpolation-based FMM, where the interpolation points and basis are fixed beforehand, the EIM is a nonlinear approximation method which constructs interpolation points and basis which are adapted to the kernel under consideration. The basis functions are obtained using evaluations of the kernel itself. We restrict ourselves to translation-invariant kernels, for which a modified version of the EIM approximation can be used in a multilevel FMM context; we call the obtained algorithm Empirical Interpolation Fast Multipole Method (EIFMM). An important feature of the EIFMM is a built-in error estimation of the interpolation error made by the low-rank approximation of the far-field behavior of the kernel: the algorithm selects the optimal number of interpolation points required to ensure a given accuracy for the result, leading to important gains for inhomogeneous kernels. Numéro de notice : P2015-002 Affiliation des auteurs : LASTIG LAREG (2012-mi2018) Thématique : MATHEMATIQUE Nature : Preprint nature-HAL : Préprint DOI : 10.48550/arXiv.1408.0210 Date de publication en ligne : 22/08/2015 En ligne : https://doi.org/10.48550/arXiv.1408.0210 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88642 Documents numériques
peut être téléchargé
A fast summation method - pdf auteurAdobe Acrobat PDF
