1
GATE ECE 2006
MCQ (Single Correct Answer)
+2
-0.6
A linear system is described by the following state equation $$$\mathop x\limits^ \bullet \left( t \right) = AX\left( t \right) + BU\left( t \right),A = \left[ {\matrix{ 0 & 1 \cr { - 1} & 0 \cr } } \right].$$$
The state-transition matrix of the system is
A
$$\left[ {\matrix{ {\cos t} & {\sin t} \cr { - \sin t} & {\cos t} \cr } } \right]$$
B
$$\left[ {\matrix{ { - \cos t} & {\sin t} \cr { - \sin t} & { - \cos t} \cr } } \right]$$
C
$$\left[ {\matrix{ { - \cos t} & { - \sin t} \cr { - \sin t} & {\cos t} \cr } } \right]$$
D
$$\left[ {\matrix{ {\cos t} & { - \sin t} \cr {\cos t} & {\sin t} \cr } } \right]$$
2
GATE ECE 2006
MCQ (Single Correct Answer)
+2
-0.6
Consider a unity-gain feedback control system whose open-loop transfer function is G(s)=$${{as + 1} \over {{s^2}}}$$ The value of 'a', so that the system has a phase-margin equal to $$\pi $$/4 is approximately equal to
A
2.40
B
1.40
C
0.84
D
0.74
3
GATE ECE 2006
MCQ (Single Correct Answer)
+2
-0.6
Consider two transfer functions $${G_1}\left( s \right) = {1 \over {{s^2} + as + b}}$$ and $${G_2}\left( s \right) = {s \over {{s^2} + as + b}}.$$ The 3-dB bandwidths of their frequency responses are, respectively
A
$$\sqrt {{a^2} - 4b,} $$ $$\sqrt {{a^2} + 4b,} $$
B
$$\sqrt {{a^2} - 4b,} $$ $$\sqrt {{a^2} - 4b,} $$
C
$$\sqrt {{a^2} + 4b,} $$ $$\sqrt {{a^2} - 4b,} $$
D
$$\sqrt {{a^2} + 4b,} $$ $$\sqrt {{a^2} + 4b,} $$
4
GATE ECE 2006
MCQ (Single Correct Answer)
+2
-0.6
The Nyquist plot of G(jω)H(jω) for a closed loop control system, passes through (-1,j0) point in the GH plane. The gain margin of the system in dB is equal to
A
infinite
B
greater than zero
C
less than zero
D
zero