Mine Countermeasures Technology (1993) / Chapter Skim
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Pages 22-42
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From page 23... ...
10. By adjusting the gain on the Strain Analyzer, the pen on the Brush Recorder linear acceleration channel, was set to a convenient deflection equivalent to 6.)
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From page 25... ...
It can be seen that in this case, flat response was realized up to a frequency of approximately 1,00 = 20 cps. This was lower than in the case where the accelerometers were mounted directly on the table because above a frequency of 20 cps the forced vibration of the beam increased the linear acceleration imposed by the table motion on the points of the beam at which the accelerometers were mounted.
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From page 27... ...
TABLE I COMPARISON OF STATIC AND DYNAMIC CALIBRATION Angular Acceleration | Calibration Procedure Calibration Constant Rad/Sec"/mm Dynamic Calibration-f=#10.22cps 2203 Dynamic Calibration-f=21.licps 21h Average Dynamic Calibration 21.8 One Point Static Calibration 217 Although the above comparison was made for angular acceleration only, it was considered valid for linear acceleration inasmuch as the measured quantities involved were actually differences of the outputs of two linear accelerometers, In view of the agreement obtained in this comparison, the static calibration procedure was judged to be entirely satisfactory for both the angular and linear accelero- meters provided that no changes in the measuring and recording system are made subsequent to an initial dynamic calibration check. Accuracy An exact determination of the accuracy of the measuring and recording system is difficult for two reasons.
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From page 29... ...
136 The quantitative use of the system output depends upon the value of an experimental calibration constant. Any error present in this calibration constant will be reflected as a systematic error in the final result.
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From page 31... ...
Use of Equipment to Obtain Shank Accelerations The foregoing laboratory tests were conducted to determine the characteristic properties of the equipment as a distinct méasuring and recording "unit" to insure that initially specified requirements were met. Test runs were then made to test the adaptability of the Nunit" to the particular application at hand.
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From page 33... ...
15. were mounted on the vibrating ‘able.
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From page 35... ...
walking level at normal cadencee The advantage of the Brush Recorder can be demonstrated by noting on Fig. 9 the ease and speed of reading and interpreting the test record.
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From page 37... ...
lie Time Required for Data Reduction The angular acceleration record requires no reduction except possibly to transfer the curve to a standard sheet of graph paper. This operation requires a negligible expenditure of time.
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From page 39... ...
18. Comparison of Accelerometer and Grapho-Numerical Differentiation Methods General Comparison As a result of a separate study, a method for determining angular and linear accelerations from motion picture time-displace- ment data has been developed which is more reliable than other differentiation procedures.
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From page 41... ...
19. and angular velocity, all as functions of time.
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