Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
2011-05-24
2011-05-24
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S609000, C702S039000
Reexamination Certificate
active
07946176
ABSTRACT:
Methods and apparatus for extracting the first arrival wave packet of an acoustic signal in a structural health monitoring (SHM) system include receiving an acoustic signal transmitted between two transducers thereof. Electromagnetic cross-talk is removed from the signal. Signal amplitude threshold values used for picking out the first arrival wave packet are chosen based on signal characteristics or chosen adaptively as the value that leads to the minimum variance of the group velocity estimates of all the actuation-sensing transducer pairs. The group velocity is estimated as the known actuator-sensor distance divided by the propagation time of the first wave packet of which the envelope exceeds a candidate threshold value. The first arrival wave packet is determined as the signal segment where the signal envelope first exceeds the chosen amplitude threshold and the segment length exceeds a specified threshold of time width.
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Beard Shawn J
Liu Bao
Acellent Technologies, Inc.
Innovation Counsel LLP
Miller Rose M
Williams Hezron
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