f) setting electric power supplies in {HEAD ~ contact} with the side surfaces of {TAIL ~ said two elements}, 
f ) setting electric power supplies in { HEAD ~ contact } with the side surfaces of { TAIL ~ said two elements } ,
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH