the pressure determination system is operable to determine the pressure values by determining {HEAD ~ a first pressure value} and a second pressure value of {TAIL ~ the fluid} at a first time and a second time, respectively, during the oscillation of the pressure, and 
of
the pressure determination system is operable to determine the pressure values by determining { HEAD ~ a first pressure value } and a second pressure value of { TAIL ~ the fluid } at a first time and a second time , respectively , during the oscillation of the pressure , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH