“…Even though the penalty function is very simple and popular, it is not trivial to define a set of appropriate penalty factors. To circumvent this problem, researchers have proposed many variants of penalty function method to deal with penalty factor values, such as dynamic method (Paszkowicz, 2009), adaptive method (Tessema & Yen, 2009), co-evolved method (Coello Coello, 2000), fuzzy method (Wu, Yu, & Liu, 2001), and some other methods (Lin, 2013). Among these methods, the adaptive penalty function is one of the most competitive approaches.…”