Abstract: In one aspect the invention comprises a system and a method for marine geophysical exploration, which includes a first cable connected to a vessel and a plurality of streamer cables connected to the first cable. The first cable includes all towing strength members and all electrical power and data transmission conductors for the connected streamer cables.

Abstract: In one aspect the invention comprises a system and a method for marine geophysical exploration, which includes a first cable connected to a vessel and a plurality of streamer cables connected to the first cable. The first cable includes all towing strength members and all electrical power and data transmission conductors for the connected streamer cables.

Abstract: Flextensional acoustic source with sound-emitting surfaces (1, 2, 3, 4) adapted to be excited into vibrational movement, and for use in seismic exploration at sea. The source comprises a drive unit (21) being through the intermediary of at least one push element (22A, 22B) adapted to impose vibrational movement to the sound-emitting surfaces. Between at least one push element (22A, 22B) and the associated sound-emitting surface(s) (1, 2, 3, 4) there is provided a non-linear spring element (27, 28) the spring constant of which is controllable. Two oppositely acting push elements (22A, 22B) are arranged in axial alignment and preferably centrally in the source, and in addition thereto there are provided at least two tension elements (39, 40) with associated controllable, non-linear spring elements (35, 36, 37, 38) and being coupled to the sound-emitting surfaces (1, 2, 3, 4).

Abstract: Acoustic transmitter in particular for use in offshore seismic explorations, having sound-emitting surfaces (1, 2) being adapted to be subjected to vibrational movement by means of a drive unit (21) through at least one push element (22A, 22B) and two plate-like end pieces (3, 4) which are connected to the sound-emitting surfaces. The sound-emitting surfaces are formed by two curved plate members (1, 2) being of comparable width and heigth dimensions. The end pieces (3, 4) have a generally rectangular shape with a first pair of opposing side edges connected (5, 6, 7, 8) to end portions of the plate members (1, 2). Another pair of side edges on each end piece (3, 4) as well as side edges of the plate members engage two side plates (9, 10) which at either side closes the acoustic transmitter, preferably in a tightly enclosing manner.

Abstract: A drive system for acoustic devices comprising drive devices, the projecting driving studs (14,15) of which are connected to pressure beams (27,28) of the acoustic device, the drive devices comprising a fixture frame (26) inside of which there are located drive units with an intermediate mechanical prestress device (22,23,24,25), the drive units comprising stator and drive cells stacked by means of guide rings (4,5) and guide discs (11), the stator cell comprising a magnetizing coil (1) with a surrounding tube (2) of soft-magnetic material fixed inside a fixture tube (3), and the drive cell comprising a cylindrical magnetic pellet (6) , discs of soft-magnetic material (7,8) and of permanent-magnetic material (9,10) making contact with said magnetic pellet.

Abstract: A drive package for acoustic transmitters includes a frame (6) of magnetic material with windows for accommodating driving members (20) and prestress devices (22) . Two windows with driving members and an intermediate window with a prestress device form a column which, by way of pressure studs (24) in the driving members and holes (14) in the frame, clamp pressure rods (4) located inside the transmitter against the shell (1) of the transmitter. The drive package may include several columns.

Abstract: An electric switching device according to the invention comprises two fixed contacts and one movable contact, referred to jointly as the main contact system. The main contact system is located in an oil-insulated cavity enclosed in a housing. In its direction of movement, the movable contact has an extension in the form of a shaft. The shaft is formed with a hydraulic piston by which the movable contact is operated. The hydraulic piston is surrounded by a cavity in which a piston cavity is formed on each side of the hydraulic piston. The piston cavities are oil-filled. The movement of the shaft is determined by an electrically controlled directional valve. The directional valve receives signals as to whether the electric switching device is to be opened or closed. At a given signal, the directional valve distributes a high pressure to the piston cavity that is to be enlarged.

Abstract: In subsea production of oil and gas, a pressurized fluid is needed for operation of valves for the production system. To be able to supply a hydraulic actuator with pressure medium for valve operation without arranging any pressurization from a platform-based pump, a liquid pump has been produced which is driven by rods of a giant magnetostriction material and which may be connected to operating devices and valves at the bottom of the sea. The liquid pump has a high efficiency and has few movable parts. By utilizing the giant magnetostrictive in two alternately operating rods (11) which are arranged in pairs and are surrounded by coils (15) supplied with current, the first rod imparting a movement when magnetic energy is transformed into mechanical energy in the form of a deformation and the second rod dynamically prestressing the first rod together with a load, a piston (12) in a cylinder space (17) of a pump housing (16) may be caused to oscillate for transporting liquid.