## 41. A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency. This is __________ criterion.

## 42. In a single tank system, the transfer function of __________ to inlet flow rate is $$\frac{1}{{{\text{TS}} + 1}}.$$

## 43. Which of the systems having following transfer functions is stable?

## 44. For an input forcing function, X(t) = 2t^{2}, the Laplace transform of this function is

^{2}, the Laplace transform of this function is

## 45. Thermal conductivity measurement is used for the determination of

## 46. Bode diagram are generated from output response of the system subjected to which of the following input?

## 47. Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.

## 48. Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function $${{\text{G}}_{\text{p}}}\left( {\text{s}} \right) = \frac{1}{{\left( {4{\text{s}} + 1} \right)\left( {2{\text{s}} + 1} \right)\left( {{\text{s}} + 1} \right)}}.$$

## 49. Temperature measurement range of iron-constantan thermocouple is 0 to 870°C. It can be used to measure sub zero temperature, because at lower temperature

## 50. A proportional controller with a gain of K_{c} is used to control a first order process. The offset will increase, if

_{c}is used to control a first order process. The offset will increase, if

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