Table 1.

Independent variables and their levels in the RSM.

Independent Variable	Factor Levels
	Lowest	Low	Center	High	Highest
	(−1.41)	(−1)	0	(+1)	(+1.41)
Time (Factor 1, A) (min)	2	5	8	11	14
Amplitude (Factor 2, B) (%)	40	55	70	85	100