evaluating a conversion capability of {TAIL ~ the catalytic converter volume} on {HEAD ~ the basis} of a value which is a function of the first difference, the value being normalized to a value which is a function of the second difference 
evaluating a conversion capability of { TAIL ~ the catalytic converter volume } on { HEAD ~ the basis } of a value which is a function of the first difference , the value being normalized to a value which is a function of the second difference
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD 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