“…These algorithms, which are based on stochastic strategies, offer advantages relative to local inversion algorithms, including strong search ability simplicity, robustness, and insensitivity to 452 C.-C. Chiu and C.-H. Sun ill-posedness. In contrast to traditional computation systems, evolutionary computation (Sun et al, 2010a(Sun et al, , 2010c(Sun et al, , 2008Rekanos, 2008;Semnani et al, 2009Semnani et al, , 2010Chien et al, 2009;Donelli et al, 2006;Chiu et al, 2009;Chien & Chiu, 2005) provides a more robust and efficient approach for solving inverse scattering problems. Particle swarm optimization (PSO) has proven to be a useful method of optimization for difficult and discontinuous multidimensional engineering problems (Poli et al, 2010).…”