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Name:_____________________________________
MAE 4800 Exam II
May 13, 2005
Open notes
Open book
Closed neighbors
Open mind
Notes:
•
Start exam when instructed – you will be given 120 minutes to complete the exam
•
Write name at top of each page and any additional pages
•
Read each problem carefully – if you still do not understand, ask
•
Clearly state all assumptions
•
Clearly show all your work, commenting on what you are doing – keep in mind that your exam
communicates to those who are grading what you know
•
To maximize points, plug in numbers at the end – solve algebraically first
•
Reference table you are using for properties
•
Good luck!
MAE 4800, Winter 2005
5/13/05
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Problem 1 (50 points)
A factorial study was conducted on a TE module, such as the one in Figure 1, to determine if the load resistance
or the temperature difference across the TE is the most dominant parameter influencing the generated power.
A
simple, 2 factor study was conducted based on the experiment design shown in Table 1 below.
The load power
for each design point was calculated by averaging 4 replications.
Each replication was found from a
measurement of the voltage across the load resistor, R
L
, and a measurement of the load resistance (P
L
= V
2
/R
L
).
The nominal values for the voltage and resistance are also shown in the table.
The standard deviations (s) for
single voltage and resistance measurements are shown in Table 2.
R
L
Figure 1.
Sketch of TE Module Attached to a Load Resistor, R
L
Table 1.
Factorial Experiment Design
R
L
∆
T
P
L
[W]
V [volts]
R
L
[
Ω
]
+
+
0.192
0.64
2.1
+

0.021
0.21
2.1

+
0.256
0.43
0.7


0.028
0.14
0.7
Table 2.
Measurement Standard Deviations for Single Replicate Measurements
Measurement
Standard Deviation
Voltage
0.01 V
Resistance
0.1 Ohms
Determine which parameter, the load resistance or the temperature difference, is the most dominant factor.
Also, show which effects (main and interaction) are statistically significant at a 95% confidence level.
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