An adaptive signal detector to detect a signal in a spectrum space includes a software defined receiver for calculating a cumulative decision statistic for determining the presence of the signal in the spectrum space. After patterning a nitride film, the thickness of an SOI layer 3 is measured and, by using the result of measurement, etching conditions for SOI layer 3 are determined. In some embodiments highpass filters, are used to detect ultrasonic acoustic signals in about the MHz range. The rotor core pack is mounted at the first end to the integrated torsional vibration damper by suitable structure members such as a mounting flange and is not fixedly mounted directly to the rotatable shaft. The sulfur grafted poly includes a poly matrix and sulfur dispersed in the poly matrix.