Measurements prelab quizzes
Which of the following is NOT a standard thermocouple circuit maintained by NIST?
V-type: silicon and lanthanum
what type if impact hammer will excie the greatedt range of frequencies in a structure?
a hard tip
Which of the following instruments are available for measuring the local acceleration constant? Tape measure Platinum RTD thermometer A mercury column barometer An encoder
all
From the following list of thermocouple connectors, select the two that are available through Omega, Inc
b. Standard connectors c. Mini-type connectors
Rotameters are instruments used to measure volume flow rate. When they are used, the should ... (select the most true answer)
be operated in a vertical orientation
What is the full scale pressure range of the PX236 pressure transducer?
100 psi
True or false? Runs in a DOE should ALWAYS be randomized.
true
Which of the following is the correct procedure for preparing thermocouple wires to be welded?
(1) Remove ~10 mm of insulation from wires, (2) tightly twist the exposed conductors together with two needle-nose pliers, (3) snip off the twisted part so that 1 or 2 twists remain and the end is square
If you have a time record that is 5 seconds long, what spacing will you have between frequency lines (resolution) in the frequency domain?
0.2 Hz
The SCC-TC02 module includes a dual-pole 2 Hz low-pass filter and an amplifier with a gain of _____ to improve the quality of thermocouple circuit signals
100
What excitation voltage is specified by the manufacturer of the PX236 pressure transducer?
10V
If four factors are known to influence the response of a system, how many experiments are required in a 2-level full factorial design?
16 (2^factors)
How many analog inputs and analog outputs does the NI PCI-6251 DAQ card feature?
16 inputs, 2 outputs
If you have 100 time samples, how many lines or components will you have in the frequency domain?
50
aliasing
Aliasing is the incorrect identification of the frequency content of a signal as a result of sampling the signal too slowly.
In a design-stage uncertainty analysis, an engineer accounts for which of the following sources of error in a measurement?
Bias error estimated in the instrument calibration Random error due to instrument resolution
You must select a thermocouple-based temperature measuring system to measure the temperature of a steady-state process in which the fluid is corrosive. Which of the following statements is most correct?
Choose a thermocouple probe with a sheath material that is resistant to the corrosive fluid in order to protect the wires in the thermocouple circuit.
Which of the following algorithms is used to transform a signal from the time domain to the frequency domain?
FFT algorithm
how is the FRF of the cantileverd beam calculated?
FRF=A(iw)/F(iw)
True or false? A small hammer may be used to excite the Golden Gate Bridge and measure its natural frequency?
False. small hammer not enough mech energy
Which of the following statements is the most accurate? a. Signals are transformed from the time domain to the frequency domain in order to more easily interpret complex signals. b. Signals are transformed from the time domain to the frequency domain in order to fix any problems with the analog-to-digital conversion of the signal. c. Signals are transformed from the time domain to the frequency domain in order to reduce the noise content of the signals. d. Signals are transformed from the time domain to the frequency domain in order to ensure that the signals are correct before they are used in analysis.
Signals are transformed from the time domain to the frequency domain in order to more easily interpret complex signals
Which of the following statements best describes the function of an I-P transducer?
The I-P transducer converts an input current into an output pressure through an electromagnetic-based force balance. In this lab, we use it to create a sinusoidal pressure input signal to the Bourdon tube gauge
What must be true about the Setra pressure transducer in the experiment to determine the magnitude ratio portion of the frequency response function of the Bourdon tube pressure gauge?
The Setra pressure transducer must have a flat frequency response (magnitude ratio of 1.0) over the 0.2 to 20 Hz frequency range
If you want to quickly switch between the front panel and the block diagram while programming in LabVIEW, you press what keys on the keyboard?
control + e
In the ANOVA results of a 2-level factorial designed experiment, the p-value for a factor is 0.078. If the level of significance is set at α=0.05, what can you conclude about the factor?
factor does not significantly influence the output.
True or false? Any real world waveform can be exactly described as a unique combination of sine waves of various amplitudes, frequencies, and phase shifts
false
True or false? Even if a signal is transformed without dynamic or sampling error, some information is always lost when a signal is transformed from the time domain and into the frequency domain
false
True or false? The Setra pressure transducer is located in the driver section of the shock tube.
false
True or false? The block diagram in a LabVIEW VI is where the user provides inputs to the VI and where outputs are displayed.
false
True or false? The goal of a screening design, e.g. a half factorial, is to develop the most robust statistical model of a process possible
false
True or false? The pressure indicated by the Bourdon tube pressure gage is gage pressure
false
True or false? The purpose of an anti-aliasing filter is to remove noise in a signal in the frequency range that would be aliased AFTER the signal has been sampled.
false
True or false? To approximate a step change input to the thermocouple probe measurement system in forced air convection, you should slowly insert the probe into the heated gas stream exiting the heat gun from the quiescent surroundings
false
True or false? When the diaphragm of the shock tube bursts, rarefaction waves are generated that travel over the transducer port to approximate a step-change pressure input to the Setra pressure transducer
false
True or false? You should open and close the isolation valve on the deadweight tester as needed when adding and removing weights from the piston.
false
True or false? The time constant of a first-order measurement system is defined as the time required for the measurement system to achieve 71.8% of the step change magnitude.
false. 63.2%
True or false? Design of Experiments (DOE) is particularly useful when a physiological model is available to describe the system under study
false. For when a physiological model is not present
Complete the sentence: In order to prevent aliasing in a sample signal, the signal must be sampled at a rate that is...
greater than twice the maximum frequency on interest in the signal
The PX236 pressure transducer is a four-wire transducer. The red and black wires are used to apply the excitation voltage and the green and white wires are used to ____________________ .
measure the output voltage
yes or no? A laminar flow element is designed such that when water at 70 °F passes through the meter at 0.5 CFM, the pressure drop across the element is 10 in H2O. Given this information, can the laminar flow element be used to measure an identical air volume flow rate if the air is at 70 °F and 1 bar.
no
Randomization is a way to _________________ in Design of Experiments (DOE)
prevent uncontrolled variables from influencing the outcome
The purpose of averaging signals is to improve the ______________________ ratio of the signal.
signal to noise
What is the velocity of the incident normal shock wave in the shock tube?
speed of sound
When the input signal to a measuring device does not vary in time during the calibration, the calibration is said to be a _____________ calibration.
static
Thermocouples are the most common devices used to measure temperature because...
they can be made small in size. they are relatively inexpensive. they provide the best value for accuracy
What is the function of an indicator in the LabVIEW front panel?
to display numeric values of variables in the labview program
Complete the sentence: When a time record is transformed to the frequency domain, the data is ____________________________.
transformed as complete block of time samples
True of false? An impact hammer with a hard tip produces the sharpest impulse
true
True of false? In this lab, we use a shock tube to achieve a step change in pressure over a time scale on the order of tens of microseconds because the shock tube achieves the change in pressure faster than even the quickest acting valves
true
True of false? One type of thermocouple probe sheath material offered by the probe manufacturer Omega, Inc. is called OMEGACLAD
true
True or false? An advanced-stage uncertainty analysis is conducted after an experiment has been completed
true
True or false? In a grounded thermocouple probe, the junction of the thermocouple circuit is mechanically joined to the sheath
true
True or false? In this lab, the magnitude ratio portion of the frequency response function of the Boudron tube pressure gauge is calculated using the following equation: M=(delta P bourdon)/(delta P setra)
true
True or false? Leakage is the result of performing the Fourier transform on a signal over a finite time record. Leakage creates "fictional" frequency content in signals because the energy of the signal is spread out over the frequency spectrum.
true
True or false? One possible use of an analog output channel in a data acquisition system is to generate a control signal for an automatic control system.
true
True or false? The Fourier series is an expansion of sine waves, each with a different frequency, phase shift, and amplitude, that are combined to approximate any periodic signal.
true
True or false? The Pareto chart is a graphical representation of the absolute value of the effects of factors and factor interactions on the system output
true
True or false? The Sensidyne Gilibrator-2 is a type of positive displacement meter
true
True or false? The first-order uncertainty of a measurement represents the engineer's best estimate of the probable range of the random errors in a measurement.
true
True or false? The output of the paddlewheel meter is a square wave whose fundamental frequency is proportional to the flow rate
true
True or false? To change the frequency of the sinusoidal pressure input to the Bourdon tube pressure gauge in lab, you will set the frequency of the electrical signal generated by the Agilent function generator
true
What are the two essential elements of a thermocouple circuit?
two dissimilar metals the metals are electrically connected at a junction
What is used to reduce the problem caused by leakage?
windowing
