Abstract: A method of using an umbilical between a surface location and an underwater location of an underwater fluid extraction well system is provided. The umbilical includes an electrical power conductor configured to transmit electrical power at a first frequency from a source at the surface location to the underwater location. The method comprises detecting that the umbilical has been compromised by the ingress of water. In response thereto, the method comprises converting electrical power from the source to electrical power at a second frequency, wherein the second frequency is lower than the first frequency or DC electrical power; transmitting the electrical power at the second frequency or DC electrical power to the underwater location via the conductor; and converting, at the underwater location, the electrical power at the second frequency or DC electrical power to electrical power at a frequency used by the underwater equipment of the well system.

Abstract: A method of using an umbilical between a surface location and an underwater location of an underwater fluid extraction well system is provided. The umbilical includes an electrical power conductor configured to transmit electrical power at a first frequency from a source at the surface location to the underwater location. The method comprises detecting that the umbilical has been compromised by the ingress of water. In response thereto, the method comprises converting electrical power from the source to electrical power at a second frequency, wherein the second frequency is lower than the first frequency or DC electrical power; transmitting the electrical power at the second frequency or DC electrical power to the underwater location via the conductor; and converting, at the underwater location, the electrical power at the second frequency or DC electrical power to electrical power at a frequency used by the underwater equipment of the well system.

Abstract: A method of supplying electrical power to at least one device at a tree of an underwater fluid extraction well is disclosed. The method comprises using magnetic resonance coupling for wirelessly transmitting power from a supply to each device.

Abstract: A method of removing oil from the surface of a body of water is provided. The method comprising collecting oil on the surface using a plurality of floating booms moved by a vessel floating on the surface, skimming oil collected by the booms using a moving continuous belt carried by the vessel and removing from the belt oil which has been skimmed from the surface.

Abstract: A boom for retaining oil on the surface of a body of water is provided. The boom comprising a sensor for detecting the oil and electronic circuitry coupled with the sensor.

Abstract: A method of supplying electrical power to at least one device at a tree of an underwater fluid extraction well is disclosed. The method comprises using magnetic resonance coupling for wirelessly transmitting power from a supply to each device.

Abstract: A component for an optical communication network comprises a source (6) for an optical communication signal, an output port (11) for outputting the optical communication signal on an optical transmitting fiber (1), a light sensor (14; 15) and an optical circulator (9) for transmitting the optical communication signal from the source (6) to the output port (11) and for transmitting light reflected or received from outside at the output port (11) to the light sensor (14; 15). The light sensor (14, 15) has an evaluation circuit (13) connected to it for detecting a time delay between a time marker of a light signal from the source and the corresponding time marker of the light arriving at the light sensor (14; 15).

Abstract: A retaining clip for connecting two or more items together is in the form of a single strip of resilient material comprising a planer rear portion, a planer front portion overlying it and a spring portion integrally connected to the front and rear portions and adapted to exert a force on them to move relative to one another parallel to their planes. The front and rear portion for respective apertures and releasably engageable locking means. The front and rear portions are relatively movable between a locked position, in which the spring portion is stressed and exerts a force on the front and rear portions and a locking means are in engagement and restrain relatively movement of the front and rear portions and the apertures are substantially in registry and portions of the two or more items to be connected can thus be inserted into them, and an unlocked position, in which the locking means are disengaged and the two apertures are at least partially off set from one another.

Abstract: A system for controlling gain of an optical amplifier that is disposed in a WDM optical communication network for amplifying an input WDM signal to produce a corresponding amplified output WDM signal is operative for measuring average optical powers of the input WDM signal over first and second wavebands, each covering a wavelength range that includes at least one wavelength channel of the WDM network and is operative for measuring the average optical powers of the amplified output WDM signal over the first and second wavebands. The system further determines gain values over the first and second wavebands from the average input and output powers and adjusts a variable of the optical amplifier to ensure that the difference between the gain values is maintained to within a predetermined value thereby ensuring a substantially flat gain slope profile.