“…In order to solve (D V ar ; IP; α; β), which seems to be a non-convex problem (the cost function associated to the problem appears to have various local minima, see Figure 2), we use a particular global optimization algorithm based on the steepest descent algorithm, where the initial condition is generated using the secant method [25]. A complete description and validation of this algorithm can be found in the following literature [20,18,13,22,21,16,17]. The obtained solutions are denoted by λ (α,β) .…”