Mohamed Jebahi

Industrial dynamical systems contain states measured only at sparse checkpoints, whileengineers often know which mechanisms govern their evolution. We propose an expertconstrained completion model that learns initial conditions and corrections to an imperfectaffine dynamical system from sparse observations. Two neural networks use operating context to estimate the initial state and dynamical coefficients. Nested binary supports specifyadmissible state and control couplings and their possible context modulation. Hard masksenforce expert knowledge, soft penalties allow additional corrections, and evanescent regularization stabilizes training. A local Laplace approximation uses Gauss-Newton curvatureand Kronecker factorization to estimate trajectory uncertainty, followed by calibration onvalidation measurements.A synthetic benchmark evaluates fixed latent trajectories under five observation schedules and several expert-support regimes. The correct hard-constrained model attains a testtrajectory RMSE of 0.0452 ± 0.0129 across five training seeds under the reference sparseschedule. Measurement timing changes completion accuracy at fixed observation budget,and omitted true couplings bias the hard model. Retrospective conditioning on measurements from the same run improves initial-state inference in three of five channels under thelearned dynamics.

Discrete-continuum coupling method for simulation of laser-inducced damage in silica glass: Une méthode de couplage continu-discret a été développée pour simuler les mécanismes complexes d'endommagement de la silice soumise à un choc laser de haute puissance. Dans un premier temps, une classification des méthodes numériques existantes a été faite pour choisir celles les mieux adaptées à la simulation du comportement sous choc de la silice. Comme résultat de cette classification, deux méthodes ont été retenues: la méthode des éléments discrets (DEM) et la méthode des éléments naturels contraints (CNEM). Ces méthodes sont alors couplées en se basant sur la technique dite "Arlequin". Puis, un modèle numérique permettant de tenir compte des différents phénomènes qui caractérise le comportement de la silice sous haute pression a été développé. Pour bien caractériser les mécanismes de fissuration de la silice à l’échelle microscopique, un nouveau modèle de rupture a été développé dans ce travail. Finalement, ces deux modèles, modèle de comportement et modèle de rupture, ont été intégrés dans la méthode du couplage pour simuler d'un point de vue mécanique le choc laser sur un échantillon en silice.

This study proposes a novel refined differential quadrature finite element (DQFE) framework for the size-dependent dynamic analysis of thick quadrilateral microplates, incorporating couple-stress effect and two kinematic variables. The proposed methodology addresses inter-element compatibility through fifth-order differential quadrature geometric mapping while achieving geometric adaptability via global-local coordinate transformation. Detailed procedures for assembling element matrices and imposing boundary conditions are provided. Validation through representative quadrilateral plate configurations confirms the efficacy of the proposed framework, with particular success in modeling asymmetric trapezoidal plates through experimental correlation. The enhanced DQFE framework further elucidates fundamental mechanisms governing cyclic quadrilateral microplate dynamics by systematically investigating three critical factors: material length scale parameters (MLSP), thickness-to-length ratios, and boundary constraint configurations. Mode localization characteristics are quantitatively assessed using the mode assurance criterion. The principal conclusions reveal: (1) Superior convergence characteristics of the fifty-degree-of-freedom DQFE formulation compared to conventional lower-order implementations; (2) Emergence of mode-transition phenomena driven by central angle variations; (3) Differential sensitivity of critical mode-transition angles to MLSP variations under contrasting boundary constraint intensities; (4) Characteristic modification of vibration mode contours induced by size-dependent effects.