Consider p(s) = s3 + $${a_2}$$s2 + $${a_1}$$s + $${a_0}$$ with all real coefficients. It is known that its
derivative p'(s) has no real roots. The number of real roots of p(s) is
A
0
B
1
C
2
D
3
2
GATE ECE 2018
MCQ (Single Correct Answer)
+2
-0.67
The state equation and the output equation of a control system are given below:
The transfer function representation of the system is
A
$${{3s + 5} \over {{s^2} + 4s + 6}}$$
B
$${{3s - 1.875} \over {{s^2} + 4s + 6}}$$
C
$${{4s + 1.5} \over {{s^2} + 4s + 6}}$$
D
$${{6s + 5} \over {{s^2} + 4s + 6}}$$
3
GATE ECE 2018
MCQ (Single Correct Answer)
+1
-0.33
The Nyquist stability criterion and the Routh criterion both are powerful analysis tools for
determining the stability of feedback controllers. Identify which of the following statements
is FALSE.
A
The closed-loop frequency response for a unity feedback system cannot be obtained
from the Nyquist plot.
B
The Routh criterion is not applicable in the condition of transport lag, which can be
readily handled by the Nyquist criterion.
C
The general shape of the Nyquist plot is readily obtained from the Bode magnitude plot
for all minimum-phase systems.
D
Both the criteria provide information relative to the stable gain range of the system.
4
GATE ECE 2018
Numerical
+2
-0
The figure below shows the Bode magnitude and phase plots of a stable transfer function
Consider the negative unity feedback configuration with gain k in the feedforward path.
The closed loop is stable for k < k0. The maximum value of k0 is ______.
