NED_UTM18 = project(ned_37057094, geog2utm, bilinear).Effectively what this does is project ned_37057094 using the parameters supplied in the file geog2utm using a bilinear interpolation method. The contents of geog2utm are as follows:
INPUT PROJECTION GEOGRAPHIC UNITS DD DATUM NAD83 PARAMETERS OUTPUT PROJECTION UTM UNITS METERS ZONE 18 DATUM NAD83 PARAMETERSEND