“…These methods can account for nonlinearities and are relatively computationally inexpensive. In case that the process model equations are not invertible, FLC (Bazaei & Majd, 2003;Hussain, Ho, & Allwright, 2001;Madar, Abonyi, & Szeifert, 2005), sliding mode control (Hussain & Ho, 2004), Model Predictive Con-trol (MPC) (Abonyi et al, 1999;Cubillos, Callejas, Lima, & Vega, 2001;Hermanto et al, 2011;Ibrehem, Hussain, & Ghasem, 2011;Klimasauskas, 1998;Tsen et al, 1996;van Can et al, 1996;Vega et al, 2000;Vega, Lima, & Pinto, 1997), predictive or optimal control (Anderson et al, 2000;Costa et al, 1998;Costa, Henriques, Alves, Maciel Filho, & Lima, 1999;Cubillos & Lima, 1997Schenker & Agarwal, 2000;Vieira et al, 2005) schema can be employed, where FLC and sliding mode control are computational less expensive while MPC or optimal control may provide better performance. When comparing the performances of control schema that utilize hybrid semiparametric models to those using either traditional control methods (such as a self-tuning PID (Xiong & Jutan, 2002), a generalized minimum variance controller (Xiong & Jutan, 2002), a FLC based on a linear model (Hussain et al, 2001) or a MPC based on a linearized model (Anderson et al, 2000)) or to non-parametric model based controllers (Cubillos et al, 2001;Hussain et al, 2001;Ibrehem et al, 2011;Schenker & Agarwal, 2000), it was mostly observed that the hybrid semiparametric model based control schema performed significantly better.…”