Electrical Engineering Answers

Design and implementation of HA, FA, HS, FS both using interactive digital input and SPDT switch.

A chemical process is controlled by a logic circuit. The circuit uses three sensors A, B and C, which

switch an alarm, Q = 1, when certain conditions are reached.

Flow rate ≥ 5 litre/second 1

Flow rate < 5 litre/second 0

Temperature ≥ 30 o C 1

Temperature < 30 o C 0

Pressure ≥ 1 atmosphere 1

Pressure < 1 atmosphere 0

(i) Construct a schematic diagram and simulate the operation of the logic circuit using standard logic gates.

(ii) Minimise the logic circuit using a Karnaugh Map, and then construct a schematic diagram, and simulate the operation of the minimised logic circuit, using standard logic gates.

(iii) Use De Morgan’s Theorems to convert the minimized circuit to use only NAND gates.

(iv) Build a prototype of your final circuit and verify that it meets the conditions in the truth table, and then compare the results from theory, simulation and measurement.

An energy source forces a constant current of 2 A for 10 s to flow through a lightbulb. If 2.3 kJ is given off in the form of light and heat energy, calculate the voltage drop across the bulb.

The relationship between the bandwidth expansion factor and the SNR is exponential

SNR2≈SNR1^B1/B2

•Double/triple the bandwidth & see the effect? Is it true the other way around (Effects of changing SNR)?

The full-load efficiency of a 400 V, 3-phase, 6 pole induction motor is 85%. It draws a line current of 80 A at 0.8 power factor lagging when it delivers full-load at 5% slip. Calculate the shaft output and shaft torque.

A pressure transmitter has the following specifications:

Lower Range Limit = 0.5 MPa

Upper Range Limit = 10.5 MPa

Reference Accuracy = .05% of span

Span Error = .10% of span

Zero Error = .05% of span

Thermal Span Error = .10% of span

Overpressure Error = .09% of span

What is the total error budget in MPa? (Type in a four-place decimal).

CrownHill Hospital Osogbo, assuming there is only one Consultant in the hospital.

Patients wait at the receptions until an auxiliary nurse call their names, and such a patient enters the consultancy room. The auxiliary nurse moves in between the consultancy room and the reception multiple times depending on the number of patient in the waiting room. In some cases when the auxiliary nurse is not with the doctor, the doctor has to shout on top of his voice to call the next patient. Now, assuming you are called upon to solve the problem in this hospital by designing a digital circuit.

a. Which of the sequential logic circuit can best used to model the solution of this problem?

b. Assuming the patients were in a group of 12 per consultation session, sketch the state diagram of the circuit.

c. Draw the truth table for your circuit.

Consider two radars. The first is a 3-GHz weather radar having a desired

unambiguous range of 300 km and unambiguous velocity of 50m/s. The second is.

10-GHz airborne radar having a desired unambiguous range of 100 km and

unambiguous velocity of 250 m/s. For each radar, is a 1 kHz PRF considered to be low

or high PRF?

Consider a 5GHz (C band) radar using a pulse repetition frequency of 3500

pulses per second. The radar collects 30 pulses of data. The slow time data sequence

is zero-padded and input to a 64-point DFT to compute the Doppler spectrum.

(a) What is Doppler frequency resolution in Hertz (with and without zero padding)?

(b) What is the spacing in meters per second (with and without zero padding)?

(c) What are the blind velocities of this radar?

Consider a continuous wave (single tone)

transmitted waveform of carrier frequency . The signal impinges on a target, moving

with radial velocity , and returns to the radar. The resulting signal, after down-

conversion from an IQ quadrature receiver, is given by

In the above expression, is the strength of the returned signal, is the positive

Doppler shift due to the target’s radial motion and t is the slow time. The signal over

a duration of T is digitized with a sampling frequency . Process the signal using

Fourier transform to obtain the correct estimate of the target velocity. Use the

values in the table below.

S. No. Parameters Values

1 Carrier frequency ( 5 GHz

2 Sampling frequency (.) 500 Hz

3 Dwell time (T) 1 second

4 Target return strength () 1 Volt

5 Radial velocity (,) 3 m/s