Abstract: A resonance testing apparatus has a plurality of arms for supporting a workpiece. At least one of said arms incorporates an articulation assembly having: a strut, a joint element which is movable in response to movement of the strut, and a clamp arrangement for clamping the joint element. The assembly has a first condition in which the joint element is movable and a second condition in which the clamp arrangement acts on the joint element to damp or restrict movement of the strut. The assembly includes a seating for the joint element, and a biasing arrangement for the seating. The assembly has a first condition in which the joint element is arranged on the seating and is movable on the seating and a second condition in which the biasing arrangement acts on the seating to damp or restrict movement of the joint element on the seating.

Abstract: A system for transmitting electrical power and communication signals is provided. The system comprises a transmission line, a source of electrical power for supplying electrical power to the transmission line, a first communication unit configured to supply communication signals to the transmission line, a power extraction unit configured to extract and use electrical power from the transmission line, a second communication unit configured to receive communication signals from the transmission line; and a control unit configured to control operation of the system. The source supplies electrical power to the transmission line for respective periods of time which are different from respective periods of time in which the first communication unit supplies communication signals to the transmission line.

Abstract: A system for transmitting alternating current power and communication signals between a first location and a second location through a communication path which includes at least one inductive load and at least one switch configured to switch power to the at least one inductive load on and off is disclosed herein. The system comprises a control configured to control the at least one switch so that, if the power is switched on during a particular phase of the power, is the power is switched off during the opposite phase of the power, and if the power is switched off during a particular phase of the power, the power is switched on during the opposite phase of the power.

Abstract: A communication arrangement for a subsea well control system, comprising an umbilical between a topside location and a subsea location, an electrical conductor in said umbilical, and a data transmission system configured to transmit and receive data between said locations via said conductor, wherein a return path for said data comprises the sea.

Abstract: A system for transmitting alternating current power and communication signals between a first location and a second location via a communication path which includes at least one inductive load and at least one switching means for switching power to said at least one load on and off, the system including control means adapted for controlling said at least one switching means so that, in response to switching off said power, a direct current is applied to said at least one inductive load and, in response to actuation of said at least one switching means to switch said power on, said power is switched on during a phase of the power which results in a magnetization of said at least one inductive load opposite to that resulting from said direct current.

Abstract: A resonance testing apparatus has a plurality of arms for supporting a workpiece. At least one of said arms incorporates an articulation assembly having: a strut, a joint element which is movable in response to movement of the strut, and a clamp arrangement for clamping the joint element. The assembly has a first condition in which the joint element is movable and a second condition in which the clamp arrangement acts on the joint element to damp or restrict movement of the strut. The assembly includes a seating for the joint element, and a biasing arrangement for the seating. The assembly has a first condition in which the joint element is arranged on the seating and is movable on the seating and a second condition in which the biasing arrangement acts on the seating to damp or restrict movement of the joint element on the seating.

Abstract: A resonance testing apparatus has a plurality of arms for supporting a workpiece. At least one of said arms incorporates an articulation assembly having: a strut, a joint element which is movable in response to movement of the strut, and a clamp arrangement for clamping the joint element. The assembly has a first condition in which the joint element is movable and a second condition in which the clamp arrangement acts on the joint element to damp or restrict movement of the strut. The assembly includes a seating for the joint element, and a biasing arrangement for the seating. The assembly has a first condition in which the joint element is arranged on the seating and is movable on the seating and a second condition in which the biasing arrangement acts on the seating to damp or restrict movement of the joint element on the seating.

Abstract: A resonance testing apparatus has a plurality of arms for supporting a workpiece. At least one of said arms incorporates an articulation assembly having: a strut, a joint element which is movable in response to movement of the strut, and a clamp arrangement for clamping the joint element. The assembly has a first condition in which the joint element is movable and a second condition in which the clamp arrangement acts on the joint element to damp or restrict movement of the strut. The assembly includes a seating for the joint element, and a biasing arrangement for the seating. The assembly has a first condition in which the joint element is arranged on the seating and is movable on the seating and a second condition in which the biasing arrangement acts on the seating to damp or restrict movement of the joint element on the seating.

Abstract: In a surface inspection system a detector responds to light received from the surface to give a detector signal including disturbances due to surface faults, and includes an equalizer circuit to control the gain of a photomultiplier, and therefore signal amplitude, in response to a peak level detector, to control the level of the signal in relation to the amplitude of the disturbances and a band-pass filter to compensate for variations in the signals due to changes in the optical gain of the detector. The equalizer circuit is an amplifier and the control is achieved by way of feedback and feedforward control loops. In a modification the system may comprise a row of detectors and the equalizer circuit may be arranged to accommodate changes in the amount of light received at the junctions of detectors.

Abstract: A circuit arrangement for use with a scanned-beam moving-surface blemish detector uses the detection of leading-and trailing-edges of the surface in each scan to provide in the following scan a margin or margins, the separation of which provides a measure of the surface width over which detection can take place without the edges being detected as faults. In a modification the margins are extended to the direction of surface movement by introducing a minimum width, between leading-and trailing-edge margins, which must exist before fault detection is permitted.

Abstract: A discrimination circuit arrangement operable to discriminate between signals in the form of d.c. pedestals and superimposed thereon disturbance signals in the form of voltage variations, comprises high pass filter means to remove the d.c. pedestal, except adjacent the leading edge where a decaying impulse is produced by the filter means. A rectangular pulse is generated, triggered by the discontinuity of the pedestal and having an amplitude related to that of the pedestal; the pulse is passed through further high-pass filter means having the same time constant as the input signal filter means to produce a replica signal of the filtered input signal in the form of a decaying impulse, free of disturbance signals. The two decaying impulse signals are compared in comparison means, with a threshold signal, and disturbance signals exceeding the threshold signal produce an output signal.

Abstract: A detector of blemishes in a surface comprises a transmitting station from which a beam of light is caused to scan a moving surface to produce a raster pattern thereon. Light specularly reflected from, or transmitted by, the surface is collected at a receiving station after being diffused by a sheet of translucent material disposed in the path of this light. The diffused light in the receiving station is collected and directed by reflective surfaces towards a photodetector such that when the beam engages a blemish in the surface, the amount of light detected falls. The detector combines the sensitivity of collecting large amounts of specularly reflected light with a simple optical system associated with the collecting of diffused light.