We use a circulating liquid that exchanges heat with cooling water (manipulate valve position z ) to control the temperature T in a well-mixed tank (CSTR) where an exothermic reaction is taking place. The figure shows the existing control structure. However, this structure is not working well. One reason for the problems is that the measurement of T has some delay, and there are also problems with dynamics in the heat exchanger and nonlinearity. Five additional measurements that may be used to improve control are shown on the figure. a) Classify the variables (T,T1,T2,T3,F1,F2,z) as inputs ( u), primary outputs (y), measured secondary outputs (y2) and measured disturbances (d). b) Suggest three possible improvements to the original control structure, with at least one cascade loop and one feedforward controller. Comment on why the improvements will be helpful