4. Consider the feedback control system for the stirred tank blending process. A step test is applied to obtain the resulting response as shown in following figure. The controller was initially in the manual mode, and then its output was suddenly changed from 30% to 43%. The measured exit composition changed from 35% to 55% which is equivalent to the mole fraction changing from 0.1 to 0.3. (a) Determine an appropriate process model for G=GtpG.G.Gm. (b) If a PI controller is implemented what will be its setting based on Z-N tuning rule. (c) With these tuning setting for Pl controller please find the Gain and Phase Margin for this controller you designed. Time M 0 Loon opened X G OP PE loul 0 op Ikamin traction frad Feedback controller Control valve X G Transmitter