A technique for stimulating production of fluids from a subterranean formation. The ink passage has an exit connected to the ink jet print head and an inlet, and the membrane has a first side and a second side. In some situations, the inferences include repeatedly determining current traffic flow characteristics andor predicted future traffic flow characteristics for road segments of interest during time periods of interest, such as to determine average traffic speed, traffic volume andor occupancy, and include weighting various data samples in various ways.