Abstract: Method and apparatus are disclosed for measuring the thickness of a workpiece by periodically transmitting ultrasonic pulses into the workpiece, receiving ultrasonic echo pulses reflected from the bottom surface of the workpiece, measuring the period of time elapsed from the time of transmission of each ultrasonic pulse to the time of reception of its related echo pulse by counting the number of clock pulses within the time period, counting each of such measured time periods by clock pulses, and deriving from each of such counted time periods and number of clock pulses within the time periods values a signal representing the thickness of the workpiece, wherein the measurement of the elapsed time period is effected with respect to a plurality of successive echo pulses, during which the phase of the clock pulses is caused to be shifted by a predetermined amount of 2 .pi.

Abstract: In the exemplary embodiments, the apparatus comprises: an ultrasonic transducer arrangement; a drive arranged to pivotably displace the transducer arrangement within a predetermined angular range; an actual-value generator for supplying a signal (F.sub.I (.rho.) dependent upon the angular position of the transducer arrangement within the said range; a desired-value generator for supplying a signal (F.sub.S (.rho.)) representing a desired angular position of the transducer arrangement within the said range; and a control for controlling the drive in dependence upon such signals from the actual-value and desired-value generators. The actual-value and desired-value generators are adapted to supply respective signals having the same or similar forms over a relatively large signal range within the said range.

Abstract: A mounting structure for double-bar resonators to ensure symmetrical loading of the resonator responsive to external forces. In one embodiment, the resonator is connected to a pair of mounting pads through compliant coupling members. The coupling members allow longitudinal, force-induced displacements of the mounting pads to load the resonator while making the resonator insensitive to spurious transverse displacements of the mounting pads. In another embodiment, a force is applied to a load-sensitive, double-bar resonator through a force-transmitting bar which is mounted on an elongated flexure hinge. The hinge is compliant about an axis of rotation which is perpendicular to the longitudinal axis of the resonator so that the hinge attenuates any force component acting perpendicular to the longitudinal axis of the resonator which would otherwise non-symmetrically load the resonator.

Abstract: To monitor a nuclear fuel element or fuel elements located in a store, e.g. a pond in a swimming pool reactor, the store is illuminated ultrasonically using one or more transducers transmitting ultrasonic signals in one or more predetermined directions to obtain an output which, because it depends on the number and relative location of the fuel elements in the store, and the structure of the store itself is distinctive to the fuel elements or elements stored therein. From this distinctive output is derived an identity unique to the stored fuel element or elements and a reference signal indicative of the whole structure when intact, the reference signal and identity being recorded. Subsequent ultrasonic testing of the store and its contents under identical operating conditions produces a signal which is compared to the recorded reference signal and if different therefrom reveals the occurrence of tampering with the store and/or the fuel element or elements.

Abstract: A system, suitable for use as an identity seal for an object, such as a container for fissile material, comprises a body including a cap for fitting over one end of the object, and a recess which contains a material such as "ARALDITE" or aluminium acting as a matrix for a plurality of inclusions of e.g. bronze embedded therein in a random configuration. The recess is closed by a cover which includes a central electrically conductive part. Also embedded in the matrix material and constituting further "inclusions" are two piezoelectric crystal transducers each electrically connected to the central cover part. In use, the transducers are electrically connected via the central cover part to external ultrasonic testing apparatus to provide a unique output indicative of the particular structure of the seal particularly the inclusion configuration and hence providing a unique "identity" and hence indication of integrity for the seal.

Abstract: Methods and means for testing and storing data relating to the quality of resistance spot welds in an automotive wheel are provided. The wheel may be rotated for one revolution or less, dependent upon the number of transducers used, while a counter generates pulse signals representative of the locations of the wheel as it is revolved. Ultrasonic signals are transmitted towards and received from locations in the wheel at which the presence of welds is being tested. Storage devices, responsive to signals from the counter and the received ultrasonic signals store counts representative of the locations on the wheel where acceptable welds start and end to thereby determine the diameters of the welds. The data stored also indicate locations and durations of voids in the welded areas.

Abstract: A device for protecting a self-propelled rail vehicle against swaying, which device includes a measuring member for ascertaining the torsional vibrations of the wheels of a driving wheel set with regard to each other. This measuring member is arranged between the respective wheel set bearing and the carriage frame, preferably in the longitudinal direction of the vehicle. The measuring member is operable to ascertain the torsional vibration reactions between the respective wheel set bearing and the carriage frame and to bring about a corresponding control of the vehicle drive motor for a corresponding change in the pulling force of the wheel set.