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ANR funded project

Accompagnement spécifique des travaux de recherches et d’innovation défense (ASTRID) 2014
Projet MEDUSES 2

Electromagnec Numerical Model with thermal coupling for Computational Dosimetry on Highly Heterogeneous Structures

The new 2013/35 EU Directive, defining minimum health and safety requirements regarding the exposure of workers to electromagnetics fields, shall be transposed in member states regulations by July 2016. These exposure limits for workers are expressed in terms of internal electric field and Specific Absorption Rate (SAR). Similar exposure limits (head and trunk current densities and SAR) have already been applied in the French Ministry of Defence since 2003. Indeed, soldiers also evolve next to high power emitters which can radiate fields above accepted reference levels over large areas. A trade-off between jamming efficiency or communication distance (in HF, VHF or UHF) and conformity with respect to regulation on personnel exposure is therefore sought.
As it is difficult to measure the EM quantities inside the human body, the demonstration of conformity versus regulation usually relies on numerical simulation (dosimetry) taking into account complex human models as well as surrounding emitters and structures. These numerical tools solving Maxwell’s equations must be adapted in order to meet the new challenges brought by civil and military regulations (exposure limits expressed in terms of SAR, current densities or internal electric fields).
Tools able to handle such complex models rely on few numerical methods: the Finite Element Method (FEM), the Finite Difference Time Domain (FDTD) method, the resolution of integral equations with the Method of Moment (MoM), the Transmission-Line Matrix (TLM) method, and the recent Galerkin Discontinuous Time Domain (GDTD) method. Each of these can be the most suitable method to use depending on the case. For numerical dosimetry, volumic methods are preferred as human models are usually described in terms of volumic pixels (voxels) with similar size as the computation cell. If transients are to be included, then both FDTD and TLM prevail. The first one is the more popular because of its simple algorithm, and has been implemented into several commercial tools. Although published a decade later, TLM has not been as widely used. It is however proved to be less dispersive, more physical because of its analogy with circuit models, and inherently stable while using the maximum allowed time step for stability. Moreover, recent works showed that TLM provides faster convergence and is more accurate than FDTD (or FIT) for structures with highly contrasted constitutive parameters such as voxel human heterogeneous models. However, only one commercial tool (developed by a foreign company) is currently based on TLM, with little past and foreseen evolution, as FDTD prevails among electromagnetic simulation users.
The objective of the present project is to elaborate the bricks of a versatile TLM simulator oriented towards military and civil dosimetry needs with extensions such as thermal coupling (strong hybridization) not available in commercial tools. It will rely on the recognized competence of 2 French laboratories working on TLM along with the competence of DGA Aeronautical Systems for Defence applications, and will be based on existing modules developed in these laboratories. Thermal effects of electromagnetic waves will also be studied through a novel TLM thermal model. Significant outcome is foreseen. First, the competence of the French TLM community will be sustained and reinforced. Second, the project will deliver a novel TLM simulator with open computation core and massively paralleled features, of significant use for Defence and for industrial applications. Finally, the structure of this demonstrator will enable constant evolution and diffusion towards telecommunications, biomedical applications, as well as RF drying (wood, vegetables, …) and RF cooking.

Partners

DGA TA DGA Techniques aéronautiques

Télécom Bretagne INSTITUT MINES-TELECOM-TELECOM BRETAGNE

LEAT - UMR 7248 Laboratoire d'Electronique, Antennes et Télécommunications

ANR grant: 271 965 euros
Beginning and duration: janvier 2015 - 36 mois

 

ANR Programme: Accompagnement spécifique des travaux de recherches et d’innovation défense (ASTRID) 2014

Project ID: ANR-14-ASTR-0020

Project coordinator:
Monsieur Michel Ney (INSTITUT MINES-TELECOM-TELECOM BRETAGNE)

 

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The project coordinator is the author of this abstract and is therefore responsible for the content of the summary. The ANR disclaims all responsibility in connection with its content.