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