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