“…Presently, several methods are used to predict the surface concentration: finite difference method [11], finite element method [11,12], polynomial approximation [6,13], differential quadrature [11], Duhamel's superposition method [13], diffusion length method [13], analytical methods [8,14,15], pseudo steady state methods [13,14,16,17], orthogonal collocation on finite elements [5] and Pad e approximation state space method [4,18]. Results presented in Refs.…”