Digital Signal Processing (DSP)
1. _____ Vibration data were acquired during the start-up (increasing speed) of a steam turbine. This signal is
A. Non-stationary with constant frequency as a function of time.
B. Stationary with constant frequency as a function of time.
C. Stationary with an increasing frequency component as a function of time.
D. Non-stationary with an increasing frequency component as a function of time.
2. _____ The cross spectrum between two signals at a frequency f = 10 Hz is given
A. (9 + 19)
B. 9/19
C. 9 x 19
D. 10.0
3. _____ Two shafts are connected by a belt drive with two pulleys of diameter 18 inches and 6 inches, respectively. If the speed of the shaft with the 6-inch pulley is 1182 RPM, the speed of the second shaft is
A. 394 RPM.
B. 591 RPM.
C. 3546 RPM.
D. 197 RPM.
4. _____ Which of the following installation of an accelerometer exhibits the best frequency bandwidth characteristic?
A. Magnetically mounted.
B. Quick connect.
C. Stud mounted.
D. Glue mounted.
5. _____ The frequency range of ultrasonic pulses used in NDE is about
A. 0-200 Hz.
B. 1-10 kHz.
C. 0.5-10 MHz
D. Less than 20 kHz.
6. _____ Materials to be examined using eddy current testing must have the following property
A. Must be magnetic.
B. Must be electrically non-conductive.
C. Must be electrically conductive.
D. Must be both magnetic and electrically conductive.
7. _____ The inductive reactance of an eddy current coil is 10 Ohms and its resistance is 4 Ohms. The magnitude of the coil impedance is
A. 14 Ohms
B. 2.5 Ohms
C. (102 + 42) Ohms
D. Ohms 116
8. _____ In eddy current testing, as the test coil frequency decreases, the depth of penetration of the induced field
A. Increases
B. Decreases
C. Is independent of the coil frequency
D. Remains constant
9. _____ In pulse-echo ultrasonic testing (UT) the UT transducer-receiver configuration has the following form.
A. Transducer and receiver are on opposite sides of the test specimen
B. Transducer and receiver are on the same side of the test specimen
C. There is no need for a receiver
D. There is no need for a transducer
10. _____ Radiographic examination uses the following penetrating radiation
A. X-rays
B. Gamma rays
C. Neutron beams
D. All the above
11. _____ NDE technique based on non-magnetic and electrically non-conductive property is
A. Visual inspection
B. Dye penetrant testing
C. Ultrasonic testing
D. All the above
12. _____ The drum in a clothes dryer is driven by a belt drive which is connected to the drive shaft with a 2-inch pulley and the drive shaft motor has a speed of 600 RPM. If the rotational speed of the drum is 60 RPM, the drum outside diameter is equal to
A. 10 inches.
B. 20 inches.
C. 30 inches.
D. 40 inches.
13. _____ Which of the following is not a candidate for thermography?
A. Monitoring hot spots on electric motors.
B. Boiler tubing inspection in a coal-fired power plant.
C. Monitoring insulation breakdown in a pipe.
D. Monitoring poor contact in electric breakers.
14. _____ Which of the following NDE method is applicable for inspecting a part made of plastic?
A. Eddy current testing
B. Ultrasonic testing
C. Magnetic particle testing
D. All the above
15. _____ Eddy current testing is most effective for detecting
A. Surface and near-surface discontinuities
B. Deep surface discontinuities
C. Cracks in thin-wall piping
D. A and C
16. _____ A couplant is generally required for this NDE technique
A. Eddy current testing
B. Radiographic testing
C. Infrared inspection
D. Ultrasonic testing
17. _____ What is the most effective transducer for measuring the displacement of the shaft in a sleeve (journal) bearing?
A. High bandwidth accelerometer
B. Proximity probe that uses eddy current principle
C. Thermal imaging camera
D. Velocity transducer