Abstract: A digital force balanced instrument such as an accelerometer that incorporates a directly digital electrostatic forcer with servo loop plates charged by a digital feedback loop is disclosed. The accelerometer has a proofmass electrode suspended in a cantilever configuration between electrodes on either side thereof, which proofmass is displaced upon acceleration. Each side electrode includes a plurality of electrostatic plates sized in binarily weighted multiples of area. An induced signal in the proofmass electrode is quantized via A/D converter in the feedback loop, which activates the appropriate number of plates to force the proofmass to an initial position.

Abstract: Method and apparatus for determining heterogeneous properties of a core sample by use of pressure transients. In the method, a pressure is applied to a first closed vessel at one end of a core sample. The pressure is then allowed to dissipate into the core and into a second closed vessel at the other end of the core sample. The pressure in at least one of the vessels or the core itself is measured and recorded as a function of time during the pressure dissipation. The volume of the first vessel is then varied and pressure is once again applied to the first vessel and allowed to dissipate into the core and second vessel. The pressure is again measured and recorded as a function of time during the pressure dissipation. The two sets of recorded measurements are then analyzed to detect deviations from theoretical responses in homogeneous cores which identify heterogeneities.