A full optimization procedure that combines the Parallel Self-Adaptive Low-High Evaluation - Evolutionary Algorithm with the Finite Element Method - Robin Boundary Condition Iteration numerical method is proposed for the design of electromagnetic mantle cloaks enclosing arbitrary objects. The procedure is efficiently applied to optimize an ultrathin, conformal FSS, placed around an inhomogeneous dielectric cylinder to be made invisible. Two very different optimal solutions have been found, and this can be a great advantage for the designer using the proposed optimization strategy.

This paper presents a modified version of the hybrid FEM-DBCI (Finite Element Method-Dirichlet Boundary Condition Iteration) method to solve static and quasi-static electromagnetic field problems in open boundary domains. The modification consists of overlapping the fictitious truncation boundary with the integration one, as in the FEM-BEM (Boundary Element Method) method. The global algebraic system obtained is solved iteratively by means of the GMRES (Generalized Minimal Residual) solver, applied virtually to a reduced system in which the unknowns are those relative to the potential on the truncation boundary only. Some validation examples are provided.

Purpose – The purpose of this paper is to present a modified version of the hybrid Finite Element Method-Dirichlet Boundary Condition Iteration method for the solution of open-boundary skin effect problems. Design/methodology/approach – The modification consists of overlapping the truncation and the integration boundaries of the standard method, so that the integral equation becomes singular as in the well-known Finite Element Method-Boundary Element Method (FEM-BEM) method. The new method is called FEM-SDBCI. Assuming an unknown Dirichlet condition on the truncation boundary, the global algebraic system is constituted by the sparse FEM equations and by the dense integral equations, in which singularities arise. Analytical formulas are provided to compute these singular integrals. The global system is solved by means of a Generalized Minimal Residual iterative procedure. Findings – The proposed method leads to slightly less accurate numerical results than FEM-BEM, but the latter requires much more computing time. Practical implications – Then FEM-SDBCI appears more appropriate than FEM-BEM for applications which require a shorter computing time, for example in the stochastic optimization of electromagnetic devices. Originality/value – Note that FEM-SDBCI assumes a Dirichlet condition on the truncation boundary, whereas FEM-BEM assumes a Neumann one.

Thin-film solar cells enable a strong reduction of the amount of silicon needed to produce photovoltaic panels but their efficiency lowers. Placing metallic or dielectric nanoparticles over the silicon substrate increases the light trapping into the panel thanks to the plasmonic scattering from nanoparticles at the surface of the cell. The goal of this paper is to optimize the geometry of a thin-film solar cell with silver and silica nanoparticles in order to improve its efficiency, taking into account the amount of silver. An efficient evolutionary algorithm is applied to perform the optimization with a reduced computing time.