Taguchi categorizes the objective functions into three groups: the smaller-the-better type, the larger-the-better type, and the nominal-is-the-best type. Since the objective function of our problem is the smaller-the-better type, its corresponding S/N ratio is: S/N ratio=−10 log10 (objective)2. The control factors in our nested SA are as follows: initial temperatures for SA1 and SA2 (A: SA1, D: SA2), lengths of each temperature level for SA1 and SA2 (B: SA1, E: SA2), and cooling rates for SA1 and SA2 (C: SA1, F: SA2
Crystallization temperature of SA1 and SA2 are fixed to 0.1. After the upper and lower levels of the parameters are determined through the preliminary experiments, the different levels of the parameters that are reviewed to calibrate the nested SA have been taken as shown