The chosen model approach contains modeling of an external exhaust gas recycling system, variable inlet systems and {HEAD ~ systems} with {TAIL ~ variable control valves} 
with
The chosen model approach contains modeling of an external exhaust gas recycling system , variable inlet systems and { HEAD ~ systems } with { TAIL ~ variable control valves }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL