Abstract: A narrow banded acoustic transducer is driven by a VCFO whose output is varied by input signals of variable amplitude. One can simulate acoustic emissions for purposes of calibrating transducers which monitor a structural part for such emissions. Different signals for the control of the VCFO are generated to provide for specific test pulses.

Abstract: Two piezoelectric filters are cascaded for suppression of bulk waves while mutually reinforcing surface wave band pass filtering. Each filter has an apodized central transducer and two outer transducers. In one instance the two outer transducers on one filter differ from the two outer transducers of the other filter with regard to bulk wave generation and reception. In another instance one filter provides asymmetric transmission and symmetry is restored by a wave slow-down for surface waves only. In still another instance the slow-down pad is provided also, but the signals in the two outer transducers are electrically inverted.

Abstract: A method for fabricating a sofa, wherein an integral seat and back is formed by joining the sides of the boards together using a form to create a surface having an upward back portion and a horizontal seat portion. The seat is supported upon a pair of spaced apart legs. A pair of arms is constructed from blocks of wood by cutting through each block to form a convex piece and a mating concave piece. The backsides of the two pieces are joined to each other in a vertically offset manner to form joint surfaces. The upper offset portion is cut off and the remaining arm is joined to the seat utilizing its joint surfaces.