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