LMA - Laboratoire de Mécanique et d’Acoustique

Post-doctoral position : "Identification of objects in heterogeneous media from their bistatic acoustic responses"

Le 10 mai 2022 à 17h00

Keywords : Acoustic propagation, heterogeneous medium, mechanical impedance, finite elements, boundary elements, acoustic holography.

Post-doctoral position at LMA (Marseille) in collaboration with M2P2 (Marseille), MPL and NRL (USA)

Deadline : June 15th 2022

Employer : Aix-Marseille University
Duration : 12 months starting between September 2022 and December 2022
Gross salary : 2450 euros/months to 2850 euros/months depending on qualification and experience
Location : Laboratory of Mechanics and Acoustics of Marseille UMR7031, Aix-Marseille University
Supervisors : Sandrine Rakotonarivo (LMA), Régis Cottereau (LMA)

Context

This project seeks to develop a method for identifying an inclusion in a heterogeneous medium using acoustic measurements. One targeted application is the discrimination of objects buried in the seabed. In the case of the installation of an underwater wind farm, for example, it is necessary to first detect whether inclusions are present in the targeted bottom. Once the detection is done, it is fundamental to be able to distinguish a rock from a historical explosive device from the first two world wars, which are still very present on the French coast. The resolution of the latter inverse identification problem is based on the analysis of the diffracted echoes.The process consists of a parsimonious measurement of the response of the medium to a controlled incident field in a bistatic configuration (sources and receivers are not at the same location). Recent research has shown convincing results for in situ detection of inclusions in the seabed [4]. However, the problem of identification, which is at the heart of this project, remains an open problem [7]. This challenge is mainly related to :
- The complexity of the acoustic response of the target. The objects can be manufactured, of complex shapes and made of different materials. This diversity will induce diffraction phenomena and various resonances, and thus a complex response.
- The complexity of the environment. This complexity can be multiple reflections from the heterogeneous structure of the marine sediment, which makes its modeling difficult [3]. In addition, fluctuations and variability of the marine environment, whose influence on the response must be understood in a statistical sense .[2].
- The coupling between the target’s response and its environment. The main goal of this post-doc is to propose a robust and computationally efficient forward modeling of a target in a complex medium. In particular, challenges related to the environment complexity (heterogeneity and variability) and the coupling between the target’s response and the surrounding medium will be addressed.

Candidate profil

Candidates must hold a Ph.D. in mechanics, acoustics or applied mathematics or related field.
Skills : Wave modeling in heterogeneous media or Structural acoustics, numerical modeling or Boundary/Finite element methods
Knowledge of Matlab or Python required
Knowledge of Comsol Multiphysics would be also appreciated

Applications

Please send your application including a CV with a list of publications, a cover letter and the names/contact information of 1-2 referees who can provide a detailed account of your accomplishments and abilities to :
- Sandrine Rakotonarivo (sandrine.rakotonarivo@univ-amu.fr) and
- Régis Cottereau (cottereau@lma.cnrs-mrs.fr)

More details, plan of work and references here :

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