Use of Magnetic Tomography Technology to Evaluate Dowel Placement

APPENDIX A
MIT Scan-2 Operations Guide (continued)

PREMEASUREMENT TESTING

The software that controls the testing and data acquisition activities, as well as preliminary data analysis, is called MagnoNorm. Figure A6 shows the Main Menu of MagnoNorm, which includes the following:

[1] Battery check - utility to check charge state of batteries on the IT2000 and on the scan unit.
[2] Memory state - utility to check the memory status of flash memory on the IT2000.
[3] Measurement - the option to initiate the measurement task.
[4] Settings - utility for setting various testing parameters.
[5] Exit - the option to end the testing and turn off the IT2000.

Figure A6. Main menu of MagnoNorm, the software on IT2000 that controls the testing and data acquisition process, as well as preliminary data analysis.

The testing involves the following tasks:

Checking battery and memory status.
Checking and setting date and time.
Entering setup information.
Entering project information in MagnoNorm.
Scanning the joint.
Data analysis.

Checking Battery and Memory State

Although not required, these tasks are important to verify that the system is functioning properly and that adequate space is available for storing the scan data. Figure A7 shows the Battery State screen; the check Memory State screen is shown in Figure A8.

Figure A7. Battery status check screen.

Press the Main Menu option [1] to check battery status.
Both batteries should be fully charged to ensure 8 hours of testing before recharging.
A display of 0 percent power for MIT Scan-2 can be a result of an improper connection. Check the connecting cable.

Figure A8. Memory status check screen.

Press the Main Menu option [2] to check memory status.
The 32-MB flash memory card provided with IT2000 can hold data for 600 joints (one lane).
Download the data frequently for better tracking of the testing data.

Settings

Selecting option [4] from the Main Menu brings up the Settings menu shown in Figure A9. Before each testing session, the current settings of MagnoNorm should be checked to ensure the various settings are correct, especially the Bar Type.

Figure A9. Settings menu in MagnoNorm.

Setting Date and Time

Setting the correct date (Figure A10) and time (Figure A11) prior to testing is important to keep track of the testing data, because the date and time are used in the naming of the folders and files as described above in the section on Memory Management.

Figure A10. Set date screen.

Press Settings option [1] to set date.
Press [Enter] after entering each number. This is a general convention on all data entry screens on MagnoNorm.

Figure A11. Set time screen.

Press Settings option [2] to set time.

Selecting the Bar Type

Selecting the correct bar type is very important to ensure proper evaluation of the scan data. Figure A12 shows the Bar Type selection screen. The files listed on this screen (the parameter files) contain the calibration data for each bar type, and the correct quantitative evaluation is only possible for the types of bars listed on this screen. The bar types are described in terms of length and diameter in millimeters, as follows:

Figure A12. Bar type (load parameter file) screen.
*lll x dd.CPF-length x diameter in millimeters*

Use [0] to move up and [1] to move down.
Press [2] to load the currently selected bar type.
Press [3] to exit.

General Settings

The General Settings include the unit of measure and the type of output (Figure A13). The Print Layout option affects the format of the field analysis (MagnoNorm analysis) results. Both the field output (IT2000 printouts) and the text files stored on the flash memory are presented in the format selected in the General Settings menu. The Coordinates option provides the x-y-z coordinates of left end, middle, and right end of each bar (Figure A14). The Table option provides the calculated alignment results in a tabular form (Figure A15).

Figure A13. General Settings.

Press [CLR] to change values.
Select the desired unit and type of output, pressing [↵ Enter] after each selection.
Press [↵ Enter] while the cursor is on the [ ↵ ] TAKE VALUES to exit.

Figure A14. Example MagnoNorm printout in coordinates format, which provides the x-y-z coordinates of the left end, middle, and right end of each bar scanned.

Figure A15. Example MagnoNorm printout in the table format, which provides the calculated alignment results in a compact tabular format.

Measuring Mode

Specify whether bare bars (Standard) or dowels placed in baskets (Basket) will be measured (see Figure A16).

Figure A16. Measuring Mode screen.

Press [1] to select bare bars (Standard).
Press [2] to select dowel basket (cut baskets only).

Joint Numbering

Set the automatic joint and station numbering behavior from the screen shown in Figure A17.

Figure A17. Station and joint numbering screen.

Select whether the station number and joint number should increase or decrease after each joint.
Enter joint spacing.

MEASUREMENT

The Measurement option (Main Menu option [3]) should only be selected after date, time, and bar type information has been entered in the Settings menu:

The measurement screen is shown in Figure A18. The information entered on this screen is used to identify the joints tested and is printed with the analysis results. The following data are required (all numeric input):

Highway type
Highway number
Highway direction
Concrete thickness

Figure A18. Project information screen that is displayed when Measurement (option [3]) is selected.

As on other screens, press [Enter] after each input. Be sure to enter valid information on all data fields. After entering the last field (Concrete thickness), you have the option of selecting:

[ ↵ ] - The entries are correct. Take the values and go to next screen.
[CLR] - Corrections are required.

The Highway Type listed in Figure A18 can be customized by modifying the file "Highways.txt" in the Input folder. Enter the description of the four types of highways in the file "Highways.txt" in the following convention:

Description, e.g., Interstate, U.S. highway, or State Route
Short description, e.g., "I" for Interstate, "US" for U.S. highway, and "SR" for State Route

Four sets of such descriptions must be provided in "Highways.txt."

After a successful entry of the project information, you will be prompted to enter or correct the station number (Figure A19). The station number is automatically incremented by 1 after each joint is scanned, so that the number may be conveniently used as the joint number.

Figure A19. Station number entry screen. The station number is automatically incremented by 1 for convenience when used as the joint number.

Next, the lane selection menu is displayed as shown in Figure A20. When a lane is selected for the first time, you will be prompted to enter the lane width in centimeters and bar spacing in millimeters (Figure A21).

Figure A20. Lane selection menu.

Figure A21. Lane description menu.

Each lane definition specifies the scan length (lane width) and bar spacing.

Each lane definition specifies the joint length (lane width), offset of the first dowel bar from the edge of the lane, and bar spacing.
The joint length defines the length over which the scan data are collected. The scanning process can be manually stopped at any time by pressing [0].
The bar spacing input has no influence on the analysis results but defines the specified location of the dowel bars for the graphical output.

When the last input (bar spacing) is entered, MIT Scan-2 is ready to scan a joint. Before starting to measure, set the scan unit against the stopper as shown in Figure A22 to properly set the starting position.

Figure A22. Properly positioned scan unit against the stopper for accurate determination of bar positions along the joint.

Figure A23 shows the screen displayed when the device is ready for measurement. During the measurement, MagnoNorm displays the signal strength detected by each of the five sensors (Figure A24).

Before pressing [Enter] to begin measurements, set the scan unit against the stopper as shown in Figure A22 to set the correct starting position.
Press [1] to start the measurements.
Do not move the unit backward after pressing [1] to begin measurements.
The measurement will stop automatically when the specified scan length (joint length) is reached.
Stop the measurement at any time by pressing [0].

Figure A23. MagnoNorm screen when the device is ready for a measurement.

Figure A24. The signal intensity at each sensor.

Upon completion of measurements, MagnoNorm displays a plot of the measured signal intensity along the joint just scanned. You can press any key to evaluate the data. The data analysis is automatic. The evaluation can take 2-3 minutes, depending on the length scanned. If MagnoNorm was able to evaluate the scan data, the results can be printed or viewed on the screen. Figure A25 shows the results screen for the coordinates print layout.

Press [0] to move up, and [1] to move down.
Press [2] to print results.
Press [3] to view a grey-scale map of the scan data.
Press [4] to continue testing or exit this menu.

Figure A25. Evaluation results screen.

MagnoNorm provides reliable results under the following conditions:

Bar depth from 100 to 180 mm (4 to 7 in.)
Horizontal misalignment less than 40 mm (1.5 in.)
Vertical misalignment less than 40 mm (1.5 in.)
Side shift less than 80 mm (3 in.)

The position errors listed above are well outside the typical specification limits. If desired, the laptop software MAGNOPROOF can be used to analyze the scan data more precisely.

CONTINUATION

The options available after each measurement are shown in Figure A26.

Select [1] to repeat measurement. When this option is selected, the data from previous measurements are overwritten. The data from all repeat measurements are saved under the same file name that was created when the joint was first scanned.
Select [2] to measure next joint. Select this option to measure successive joints in the same project. Different joints in the same project are differentiated by the joint number rather than the station number. The joint number is a sequential number that is automatically updated by MagnoNorm. The station number is used only to denote the location of the first joint, and the user is not prompted to enter the station number at each joint. The joint number is printed on evaluation results.
Select [3] to go to the Main Menu. Use this option if a different lane needs to be measured.
Select [4] to end testing and shut off IT2000.

Figure A26. Available options after each measurement.

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