lowering the power level applied to the heating means to the next lower power level upon detecting {HEAD ~ a rate} of {TAIL ~ change} exceeding the reference rate and raising the power level applied to the heating means to the next higher power level upon subsequent detection of a rate of change less than the reference rate 
of
lowering the power level applied to the heating means to the next lower power level upon detecting { HEAD ~ a rate } of { TAIL ~ change } exceeding the reference rate and raising the power level applied to the heating means to the next higher power level upon subsequent detection of a rate of change less than the reference rate
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH