The plates may be {HEAD ~ actuators}, which couple energy into {TAIL ~ the attached structure}, or sensors which respond to strain coupled from the attached structure 
couple energy into
The plates may be { HEAD ~ actuators } , which couple energy into { TAIL ~ the attached structure } , or sensors which respond to strain coupled from the attached structure
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH