Abstract: A range of motion (ROM) prosthetic foot and passive dampening ankle joint have limited dorsiflexion-plantarflexion (up and down) pivoting to accommodate different environments, and a spring to provide resilient resistance to plantarflexion (or lowering of the toe), and to bias the foot in dorsiflexion (or raising the toe). The ankle joint has a rear pivot rearward of a hydraulic link for a smooth feel. The ankle joint has an internal bumper in a hydraulic cylinder for a smooth feel. The ankle joint has an internal hydraulic compensator disposed in the cylinder and carried by the piston to equalize volume.

Abstract: A Smart Card has an electronic circuit connected to a source of potential capable of destroying at least a portion of the electronic circuit. The potential is normally short circuited, but the path of the short circuit traverses a frangible portion of the card. When the portion is broken, so potential from the source is applied to destroy the portion of the electronic circuit.

Abstract: A method for determining the resonant frequency of vibration of a rotating blade comprises determining the approximate resonance frequency and rotating a blade at a plurality of frequencies in a range above and below the approximate frequency. At each frequency two measurements are taken representative of synchronous amplitudes at each measurement point (P.sub.1 and P.sub.2) wherein the two points are separated by an angle .beta. and there are an unknown number x of complete synchronous vibrations between the two points. A set of data is provided and a plot of P.sub.1 and P.sub.2 produced, the data being analysed to determine a likely value of x and hence the resonant frequency.