0.24
Raw Data
0.22
Low Counts Removed
0.20
Average of Total Duration
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0.01
0.10
1.00
10.00
100.00
Concentration (grams/liter)
Figure 48. Calculation of a vertical sediment concentration profile
Calibration of beach profile indicator
A permanent benchmark was installed to verify the "offset" in the calibration
equation for the profile indicator, to ensure consistency from one experiment to
the next. The benchmark is located at X = 0.697 m and Y = 16.015 m on top of the
concrete beach and can be accessed by lowering the sensor down through the
moveable-bed into a 0.2-m-diam polyvinyl chloride pipe, as shown in Figure 49.
The surface of the benchmark is located at an elevation of Z = 0.742 m. A graded
scale, with a 1.52-m vertical range, is located on the front of the vertical shaft of
the profile indicator. The elevation of the vertical scale was adjusted so that the
vertical scale reads exactly 0.742 m if the sensor is resting on the benchmark.
The scale has a gradation of 0.01-m major increments and 0.001-m minor
increments.
The profile indicator is calibrated using a similar procedure as that used to
calibrate the linear actuators that control the elevation of the wave gauges. The
PV-12 Profiler Calibration panel is accessed under the Calibration menu of the
MTS control software, (Figure 50). The first step in the calibration process is to
lower the sensor onto the benchmark. After the sensor is motionless, the "Read
Cal Step," or toggle, button is pressed and the MTS control software records the
output voltage from the profile indicator. The operator manually enters the
physical elevation of the sensor in the "Measured Value" column. For example,
in Figure 50, the first calibration step obtained with the sensor resting on the
benchmark (measured elevation of 0.742 m) has an output voltage of 6.014 volts.
The profile indicator is moved offshore to a location where the sensor can be
lowered down close to the horizontal floor of the facility. This is approximately
88
Chapter 8
Sensor Calibration, Measurement, and Data Analysis
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