Causal Surrogate Modeling for High Performance Finite Element Earthquake Simulations

High-resolution earthquake simulations are essential for understanding seismic wave propagation in complex geological structures. However, finite element simulations require significant computational resources, particularly when exploring multiple scenarios or accounting for uncertainties. This PhD project aims to develop causal surrogate models that reduce computational costs while preserving the physical consistency of seismic simulations. The proposed approach combines causal machine learning, Bayesian statistics, and high-performance computing (HPC). Using data generated by large-scale finite element simulations, the research will investigate methods for identifying directed relationships between seismic variables across space and time. These causal relationships will then be used to construct surrogate models capable of approximating selected components of numerical simulators. Bayesian approaches will also be explored to quantify uncertainties in the learned causal structures and model predictions. The developed methods will be integrated into parallel simulation environments, particularly ArcaneFEM and PSD, to ensure their applicability to large-scale problems. The expected results include efficient causal learning algorithms, computationally scalable surrogate models, and hybrid simulation strategies combining numerical methods and artificial intelligence. Ultimately, this research aims to improve the efficiency of earthquake simulations and support uncertainty quantification, adaptive mesh refinement, and data assimilation.

Accelerated design of High Entropy Oxide thin films for carbon-free energies

Over the past decade, high-entropy oxides have emerged as a promising new class of materials for energy-related applications and corrosion resistance in extreme environments, both of which are central areas of CEA's activities.
However, their optimization remains limited by the vast compositional space that needs to be explored, leading most studies to focus on equimolar compositions.
This PhD project aims to overcome this limitation by combining combinatorial PVD using HiPIMS technology with artificial intelligence approaches based on Bayesian optimization, an approach that has not yet been explored for these materials.
The objective is to master the deposition of high-entropy oxides and optimize their properties for corrosion protection in high-temperature electrolyzers dedicated to low-carbon hydrogen production.
The deposited coatings will exhibit controlled stoichiometry, structure, microstructure, and texture, and will be characterized both in situ and ex situ using complementary techniques.
The project will provide a proof of concept for coupling combinatorial PVD with Bayesian optimization to accelerate the discovery and optimization of new materials.
This PhD project is part of the international doctoral programme of PEPR DIADEM and will bring together CEA (Saclay), ESRF (Grenoble), and NIMS (Japan).

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