ME2350 Elements of Mechanical Engineering Measurements (Fall 2016) Name Test 1 C

Question

ME2350 Elements of Mechanical Engineering Measurements (Fall 2016) Name Test 1 Close book and close notes (but a calculator is allowed). Work on all four problems. Keep up to 4 decimal spaces or 6 significant digits in your calculations Problem 1 (25 points). Two electrical-based sensors have been used in the first two lab sessions so far. One sensor (thermistor) was used for temperature measurements and another (accelerometer) was used for acceleration measurements. Please answer the following five 1) Among the following modes of electrical sensors: (a) electric inductive; (b) electric resistive; (c) electric capacitive; (c) thermoelectric, the physical mode of the temperature sensor is and that of the acceleration sensor is 2 Elecria- hased seducers may be clasified as being either(o) active or (b) passive. The sensor/transducer unit for temperature measurements is and the 3) One major difference between the temperature and acceleration measurements is unit for acceleration measurements is One maior (a) relative or absolute; (b) that it can be negative or not; (e) that one needs to specify the spatial direction of the measurement or not; (d) that the sensor needs calibration or not. ature and acceleration measurements are based on direct voltage readings. 4) Both temper From what you have known about their relations between the measurands and voltages the temperature sensor is and that of the acceleration sensor is(a) Linear, (b) sinusoidal: (c) exponential; (d) nonlinear 5) A sensor may also be classified as either (a) an invasive one or (b) a non-invasive one. We would call the temperature sensor and the acceleration sensor is Problem 2 (25 points). Besides these two electrical-based sensors used in the first two lab sessions, other electronics components (such as transducer, amplifier, filter, A/D converter, and computer) were also used as part of the complete measurement system. A computer program LabVIEW with a graphical user interface and many data acquisition and control features was also used as part of the measurement system. Please answer the following five questions: I) A simple electrical circuit of voltage divider was used in the myTemp temperature measurement unit (circuit board). Such a circuit may be called(a)a transducer, (b) an amplifier, (c) a filter; (d) an A/D converter; (e) a computer 2) The circuit board of the myQuake vibration (acceleration) measurement unit includes . (a) voltage divider for the accelerometer; (b) Whetstone bridge for the accelerometer, (c) a variable power supply ("battery") for the motor; (d) an A/D converter In the second lab session for vibration measurements, the voltages for XYZ axes were measured only one axis at a time because (a) The accelerometer only outputs voltage one axis at a time; (b) the NI myDAQ device accepts only one input voltage from one sensor (accelerometer) at a time: (c) the specific setting is made in the myQuake LabVIEW VI for data acquisition. There is a "Motor Control % Scale" on the front panel of the mou ake LabVIEW VI for data acquisition. It allows one to (a) Change the resistance of the electric motor (b) change the input voltage from the accelerometer; (c) change the current output from NI myDAQ: (d) change the voltage output that is available to the electric motor. Based on the typical voltage values measured in both labs, the temperature measurement has most likely an analog amplifier and the acceleration measurement has most 3) 4) 5) likely an analog amplifier. (a) Used (b) Not used.

Explanation / Answer

Problem 1

1. The physical mode of temperature sensor is electric resistive and that of the acceleration sensor is electric capacitive.

2. The sensor/ Transducer unit for temperature measurement( thermistor) is Passive and the sensor/trasducer unit for acceleration measurement is also Passive.

3.one major difference between the temperature and acceleration measurement is thermistor measures relative temperature and accelerometer measures absolute acceleration so its answer is Relative or absolute.

4. The relation between measurands and voltage is of temperature sensor is non-linear and that of acceleration sensor is linear.

5. temperature sensor is non-invasive. acceleration sensor is invasive.

PROBLEM 2:

1. A simple electrical circuit of voltage divider was used in myTemp temperature measurement unit. such a circuit may be called a transducer.

2. the circuit board of myQuake vibration( acceleration) measurement unit includes an A/D Converter.

3. the voltages for XYZ axes were voltage one axis at a time because a specific setting is made in the myQuake LabVIEW VI for data acquisition.

4. it allows to change the voltage output that is available to the electric motor.

5. the temperature measurement has most likely not used an analog amplifier and the acceleration measurement has most likely not used an analog amplifier.

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