Furtivity and Masking Problems in Time-Dependent Electromagnetic Obstacle Scattering

• Published in: Journal of optimization theory and applications 2004-05, Vol.121 (2), p.233-257
• Main Authors: Fatone, L, Recchioni, M C, Zirilli, F
• Format: Article
• Language: English
• Subjects: Algorithms; Electromagnetism; Mathematical models; Numerical analysis; Optimization; Parallel processing; Partial differential equations; Studies
• ISSN: 0022-3239; 1573-2878

This paper proposes a criterion based on a merit function to minimize or to mask the electromagnetic field scattered by a bounded obstacle when hit by an incoming electromagnetic field and, with respect to this criterion, we drive the optimal strategy. These problems are natural generalizations to the context of electromagnetic scattering of the furtivity problem in time-dependent acoustic obstacle scattering presented in Ref. 1. We propose mathematical models of the furtivity and masking time-dependent three-dimensional electromagnetic scattering problems that consist in optimal control problems for systems of partial differential equations derived from the Maxwell equations. These control problems are approached using the Pontryagin maximum principle. We formulate the first-order optimality conditions for the control problems considered as exterior problems defined outside the obstacle for systems of partial differential equations. Moreover, the first-order optimality conditions derived are solved numerically with a highly parallelizable numerical method based on a perturbative series of the type considered in Refs. 2-3. Finally, we assess and validate the mathematical models and the numerical method proposed analyzing the numerical results obtained with a parallel implementation of the numerical method in several experiments on test problems. Impressive speedup factors are obtained executing the algorithms on a parallel machine when the number of processors used in the computation ranges between 1 and 100.