Abstract: A method and apparatus are provided for determining an estimate of flow stability, in addition to providing a measurement of flow velocity distribution. To this end, monitoring is provided of the changes over time of flow measurements from a plurality of spaced apart measuring points. An indication of the reliability of the flow velocity distribution measurement is produced based on the estimate of stability.

Abstract: A drive arrangement, for example for a writing head, comprising a piezoelectrically actuated lever arrangement (1d) for moving a writing tip (21) in the direction of a recording medium when writing on the recording medium. This drive arrangement is characterized in that a piezoelectric actuator (4) is used, which is separate from the lever arrangement (1d) and in that the lever arrangement (1d) exerts a compressive force on the piezoelectric actuator (4), which is supported against a rigid abutment (section 1b). This drive arrangement can be used for a series of other applications as a positioning drive. Inverse arrangements are also described.

Abstract: An improvement over conventional electromagnetic flowmeters which signal a measure of flow rate by controlling the current in a current signalling loop (also known as a sensing loop) and in which power for the flowmeter is derived from the current in the signalling/sensing loop. Conventional electromagnetic flowmeters use a standard current range (typically 4-20 mA), in which zero flow is indicated by controlling the current in the loop to a minimum predeterimened value and maximum flow is indicated by controlling the current to a maximum predetermined value. In the improved flowmeter of the invention, minimum flow is signalled by maximum current in the signalling/sensing loop and maximum flow is signalled by minimum current. This has been found to enable improved accuracy to be obtained at low flow rates without requiring complex flowmeter circuitry.

Abstract: In an electromagnetic flowmeter, the conventional derivation of flow velocity is corrected or replaced by an alternative calculation to take into account estimated non-linear dependence of field strength produced by the coil with applied coil current. This can be used to enable more accurate measurement, over a wider range of coil current. The improved accuracy allows the coil current to be adjusted to optimise power consumption; the adjustment of coil current in this manner is another aspect of the invention.