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