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