(a) (b) (c) (d) Describe two characteristics of linear time-invariant (LTI) systems with appropriate examples or/and equations. [6] Consider the control system shown in Figure Q1b. Correction element, the switch Heating element Temperature measurement Figure Q1b The room Copy the above Figure Q1b into your answer book, labelling the desired output, actual output, process, feedback, error signal, sensor, actuator and control signal. [4] A system is modelled by the differential equation: dx y = x + a dt Show that the system is non-linear. Also, check the homogeneity of the system. [6] Describe the key difference between regulators and servo systems, giving an example for each. [4]