P posol RETIRED Aug 16, 2005 #2 this is a good write up on it: http://www.mr2.com/DIGEST/VOLUME2/1806.txt http://www.epi-eng.com/ET-VolEff.htm
this is a good write up on it: http://www.mr2.com/DIGEST/VOLUME2/1806.txt http://www.epi-eng.com/ET-VolEff.htm
