Parabolic trough collector. As discussed in Section 10.12, the Nyquist stability criterion can be applied to systems with pure time delay without the need for rational approximations as required in Problems 8.72 and 9.59. You will verify this by applying the Nyquist stability criterion to the parabolic trough collector by assuming a unity-feedback system and a forward-path transfer function (Camacho, 2012), 137.2 x 10-6K S2 + 0.0224s + 196 Ã— 10-6 398 G(s)- a. Draw the corresponding Nyquist diagram for K 1 b. Use the Nyquist diagram to find the range of K for which the system is closed-loop stable e. Find the value of K that make the system marginally stable and the associated frequency of oscillation.