Disclosed is a propulsion system having a structural configuration that provides easy and convenient access to the interior regions of a liquid fuel tank and a hybrid rocket motor case. A plurality of surface-mountable contacts are arranged in an array exposed at a major surface of the microelectronic element. The elevation can also be combined and simultaneously displayed with another tissue layerboundary dependent set of image data to provide additional information for diagnostics. The measurement head may also have a thermo-element, and the device may be used to determine the concentration of silicon andor carbon in the melt, based on the oxygen activity measurement. Aspects of the invention provide wide temperature-range smectic materials and devices using the smectic materials. The learning data is associated with a second data source type and representing at least one item to be added to the aggregate list from the second data source type.