Dr. Stéphane Roux: "From tomography to motion ... and from motion to tomography"
Event details
| Date | 08.06.2022 |
| Hour | 17:00 › 18:00 |
| Speaker | Dr. Stéphane Roux, CNRS |
| Location | Online |
| Category | Conferences - Seminars |
| Event Language | English |
Abstract. Materials science and now solid mechanics are revolutionised by the use of tomography. It provides a complete microscale 3D image of both microstructure and kinematics in a non-intrusive way. To reveal the mechanical properties of materials or structures, a series of tomographic images acquired in situ all along a mechanical test appears to be the ideal way to measure 3D displacement fields based on non-rigid tomographic image registration (called Digital Volume Correlation, or DVC, in solid mechanics) from which the parameters of its constitutive law can be calibrated. Tomographic reconstruction, registration, and identification of the mechanical behaviour are three inverse problems, which can be chained or fused optimally with respect to noise (i.e. showing the least sensitivity). Integrating all those operations into a single procedure has the additional benefit of cutting down the needed acquisition time by a significant factor (from several days to a few minutes). The principle of such an approach is first to perform a plain tomography of a sample (potentially with no applied load) and then, under increasing load, evaluate the constitutive parameters from a series of radiographs or projections. In this way, motion (and its mechanical justification) could be obtained efficiently at high temporal resolution.
Yet, a first static reconstructed image is still needed in such a procedure. Thus, a natural question is whether this first step is dispensable. This opens the way to “dynamic tomography”, whereby a series of radiographs (not longer than for a usual tomography) of a non-rigid body is used to reconstruct both the body and its motion at each instant of time. An application to medical imaging (chest tomography of a breathing patient) will be shown.
Biography. Stéphane Roux is a CNRS Research Professor at the Ecole Normale Supérieure Paris-Saclay. After graduating from Ecole Polytechnique, and Ecole Nationale des Ponts et Chaussées, he earned a Ph.D. in 1990 in Statistical Physics, before joining the CNRS as a Research Professor in 1991 at Ecole Supérieure de Physique et Chimie Industrielles de Paris. From 1998 to 2007, he was the Director of a Joint Research Unit between Saint-Gobain (a worldwide company in material manufacturing and distribution) and the CNRS. He has worked at ENS Paris-Saclay since then. There, his research interests are in Digital Image Correlation, Stereo-vision, and Tomography at the interface between experimental solid mechanics and modelling. He received the CNRS Silver Medal in 2006, and the Prix Jaffé from the French Academy of Science in 2019.
Yet, a first static reconstructed image is still needed in such a procedure. Thus, a natural question is whether this first step is dispensable. This opens the way to “dynamic tomography”, whereby a series of radiographs (not longer than for a usual tomography) of a non-rigid body is used to reconstruct both the body and its motion at each instant of time. An application to medical imaging (chest tomography of a breathing patient) will be shown.
Biography. Stéphane Roux is a CNRS Research Professor at the Ecole Normale Supérieure Paris-Saclay. After graduating from Ecole Polytechnique, and Ecole Nationale des Ponts et Chaussées, he earned a Ph.D. in 1990 in Statistical Physics, before joining the CNRS as a Research Professor in 1991 at Ecole Supérieure de Physique et Chimie Industrielles de Paris. From 1998 to 2007, he was the Director of a Joint Research Unit between Saint-Gobain (a worldwide company in material manufacturing and distribution) and the CNRS. He has worked at ENS Paris-Saclay since then. There, his research interests are in Digital Image Correlation, Stereo-vision, and Tomography at the interface between experimental solid mechanics and modelling. He received the CNRS Silver Medal in 2006, and the Prix Jaffé from the French Academy of Science in 2019.
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