The work of the Metals Research Laboratory of Brown University is pri¬marily concerned with the study of mechanical properties of solids by means of measuring ultrasonic attenuation by the pulse method.nThe exponential comparator method makes use of a calibrated, decaying exponential wave of vari¬able decay modulus, which is matched to the peaks of the echoes. The pulse com¬parator method makes use of a pul6e, which can be delayed a variable amount with respect to the original pulsed oscillator pulse, and a set of calibrated attenu¬ator boxes. In this second method, the decibel difference in amplitude between pulses can be measured. The exponential comparator method measured the attenu¬ation using the entire echo train in one matching, while the pulse comparator method compares each echo on an individual basis.
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