Documents disponibles écrits par cet auteur

Numeric-analytic form of the adomian decomposition method for two-point boundary value problems in nonlinear mechanics / S. Ghosh in Journal of engineering mechanics, Vol. 133 N°10 (Octobre 2007) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1124-1133 Titre : Numeric-analytic form of the adomian decomposition method for two-point boundary value problems in nonlinear mechanics Type de document : texte imprimé Auteurs : S. Ghosh, Auteur ; D. Roy, Auteur Année de publication : 2007 Article en page(s) : pp. 1124-1133 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Decomposition  Numerical  analysis  Algorithms  Differential  equations Résumé : A new numeric-analytic technique is developed for two-point nonlinear boundary-value problems (BVPs) of engineering interest. The analytic part of the method is based on a conventional Adomian decomposition method (ADM). However, given a discretization of the one-dimensional domain, the present algorithm applies the ADM, repetitively over successive intervals and exploits a shooting algorithm to solve the BVPs. Apart from a very high rate of convergence as the discretization is made finer, yet another significant advantage of the method is that it provides the solution in a piecewise functional form and one can finally arrive at a continuous form of the global solution. The procedure is used to study planar, large-deflection (Elastica) problem of a cantilever beam subjected to a transverse, concentrated load, at its free end. Moreover the elastoplastic behavior of a cantilever is also studied. Comparisons with exact solutions as well as with results via a few other competing algorithms demonstrate the remarkable accuracy of the proposed method. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160819 [article] Numeric-analytic form of the adomian decomposition method for two-point boundary value problems in nonlinear mechanics [texte imprimé] / S. Ghosh, Auteur ; D. Roy, Auteur . - 2007 . - pp. 1124-1133. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 133 N°10 (Octobre 2007) . - pp. 1124-1133 Mots-clés : Decomposition  Numerical  analysis  Algorithms  Differential  equations Résumé : A new numeric-analytic technique is developed for two-point nonlinear boundary-value problems (BVPs) of engineering interest. The analytic part of the method is based on a conventional Adomian decomposition method (ADM). However, given a discretization of the one-dimensional domain, the present algorithm applies the ADM, repetitively over successive intervals and exploits a shooting algorithm to solve the BVPs. Apart from a very high rate of convergence as the discretization is made finer, yet another significant advantage of the method is that it provides the solution in a piecewise functional form and one can finally arrive at a continuous form of the global solution. The procedure is used to study planar, large-deflection (Elastica) problem of a cantilever beam subjected to a transverse, concentrated load, at its free end. Moreover the elastoplastic behavior of a cantilever is also studied. Comparisons with exact solutions as well as with results via a few other competing algorithms demonstrate the remarkable accuracy of the proposed method. ISSN : 0733-9399 En ligne : http://cedb.asce.org/cgi/WWWdisplay.cgi?160819

Two-stage extended kalman filters with derivative-free local linearizations / Nilanjan Saha in Journal of engineering mechanics, Vol. 137 N° 8 (Août 2011) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 137 N° 8 (Août 2011) . - pp.537546 Titre : Two-stage extended kalman filters with derivative-free local linearizations Type de document : texte imprimé Auteurs : Nilanjan Saha, Auteur ; D. Roy, Auteur Année de publication : 2011 Article en page(s) : pp.537546 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Two-stage  filter  Extended  Kalman  filters  Model  uncertainty  Derivative-free  local  linearizations  Parameter  estimations Résumé : This paper proposes a derivative-free two-stage extended Kalman filter (2-EKF) especially suited for state and parameter identification of mechanical oscillators under Gaussian white noise. Two sources of modeling uncertainties are considered: (1) errors in linearization, and (2) an inadequate system model. The state vector is presently composed of the original dynamical/parameter states plus the so-called bias states accounting for the unmodeled dynamics. An extended Kalman estimation concept is applied within a framework predicated on explicit and derivative-free local linearizations (DLL) of nonlinear drift terms in the governing stochastic differential equations (SDEs). The original and bias states are estimated by two separate filters; the bias filter improves the estimates of the original states. Measurements are artificially generated by corrupting the numerical solutions of the SDEs with noise through an implicit form of a higher-order linearization. Numerical illustrations are provided for a few single- and multidegree-of-freedom nonlinear oscillators, demonstrating the remarkable promise that 2-EKF holds over its more conventional EKF-based counterparts. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i8/p537_s1?isAuthorized=no [article] Two-stage extended kalman filters with derivative-free local linearizations [texte imprimé] / Nilanjan Saha, Auteur ; D. Roy, Auteur . - 2011 . - pp.537546. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 137 N° 8 (Août 2011) . - pp.537546 Mots-clés : Two-stage  filter  Extended  Kalman  filters  Model  uncertainty  Derivative-free  local  linearizations  Parameter  estimations Résumé : This paper proposes a derivative-free two-stage extended Kalman filter (2-EKF) especially suited for state and parameter identification of mechanical oscillators under Gaussian white noise. Two sources of modeling uncertainties are considered: (1) errors in linearization, and (2) an inadequate system model. The state vector is presently composed of the original dynamical/parameter states plus the so-called bias states accounting for the unmodeled dynamics. An extended Kalman estimation concept is applied within a framework predicated on explicit and derivative-free local linearizations (DLL) of nonlinear drift terms in the governing stochastic differential equations (SDEs). The original and bias states are estimated by two separate filters; the bias filter improves the estimates of the original states. Measurements are artificially generated by corrupting the numerical solutions of the SDEs with noise through an implicit form of a higher-order linearization. Numerical illustrations are provided for a few single- and multidegree-of-freedom nonlinear oscillators, demonstrating the remarkable promise that 2-EKF holds over its more conventional EKF-based counterparts. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i8/p537_s1?isAuthorized=no