246. A process with open-loop model Ke-st G (s) TS + 1 is controlled by a P1D controller. For this process.

A. the integral mode improves transient performance.

B. the integralmode improves steady-state performance

C. the derivative mode improves transient performance.

D. the derivative mode improves steady-state performance.

247. A linear discrete-time system has the characteristic equation, z3 -0.81z = 0 The system

A. is stable

B. is marginally stable

C. is unstable

D. stability cannot be assessed from the given information.

248. Signal flow graph is used to find

A. stability of the system

B. controllability of the system

C. transfer function of the system

D. poles of the system

249. The step error coefficient of a system (s + 6) (s + 1) with unity feedback is

A. 1/6

B.1

C.0

D.1

250. For a second order system, damping ratio, (4) is 0 < 4 < 1, then the roots of the characteristic polynomial are

A. real but not equal

B. real and equal

C. complex conjugates

D. imaginary

251. The transfer function of a linear system is the

A. ratio of the output, Vo (t), and input, V1 (t)

B. ratio of the derivatives of the output and the input

C. ratio of the Laplace transform of the output and that of the input with all initial conditions zero

D. none of these

252. Non-minimum phase transfer function is defined as the transfer function, which has

A. zeros in the right-half s-plane

B. zeros only in the left-half s-plane

C. poles in the right-half s-plane

D. which has lopes in the left half s-pane.

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