determining a total amount of {HEAD ~ fuel} required to raise {TAIL ~ the temperature} of exhaust above a regeneration temperature based on the determined flow rate and the determined temperature; and 
required to raise
determining a total amount of { HEAD ~ fuel } required to raise { TAIL ~ the temperature } of exhaust above a regeneration temperature based on the determined flow rate and the determined temperature ; and
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH