Abstract: A method of analysing a welding parameter associated with a linear friction welding process. The linear friction welding process incorporates a weld cycle comprising a burn-off phase, the end of the burn- off phase being determined during the weld cycle by reference to a respective weld upset target. The method comprises: recording a profile of the weld parameter as a function of time during the weld cycle and assessing the recorded profile against a predetermined, respective threshold profile for the weld parameter which is based on a pre-estimate of the end of the burn-off phase. The assessment is carried out retrospectively following a determination of the actual end of the burn-off phase for the recorded profile, and comprises time-shifting the threshold profile relative to the recorded profile so that the pre-estimated endpoint of the burn-off phase is closer to, and preferably coincidental with, the actual endpoint of the burn off phase.

Abstract: Apparatus for generating hydrogen by the electrolysis of water comprising an electrolytic cell having a cathode and an anode separated by a solid electrolyte, an electrical power supply connected to the cell for applying a voltage across the cathode and anode, a water reservoir connected to the cell for supplying water to the anode side, a hydrogen-water separator connected to the cell for receiving hydrogen and water from the cathode side and separating the hydrogen from the water, and a water return line connecting the hydrogen-water separator to the water reservoir for returning water to the water reservoir whereby the water is recycled to the anode side. A float valve in the upper region of the hydrogen-water separator closes the hydrogen outlet in response to an increase in the water level in the separator to the level of the hydrogen outlet, to prevent water from entering the hydrogen outlet in the event of a malfunction.