Abstract: The invention relates to a method for marine seismic prospecting, of the type in which a seismic wave is emitted at a determined point close to the surface of the water and the waves reflected by the interfaces between geological formations of the subsoil are recorded as a function of time using receivers arranged at a plurality of locations close to the surface of the water. A mathematical model of multiple signals and peg legs is produced from known wave equations. Data calculated using the mathematical model M(t,x) are adapted with polynomial transfer functions and are subtracted from the data recorded by each of the sensors in order to obtain final data. Using the final data, a graphic representation is prepared of the geological formations of the subsoil in which the seismic wave is propagated.The invention proposes mathematical processing of the data enabling the elimination of multiple signals and peg legs.

Abstract: The extrusion screw for thermoplastic material comprises a helical thread, having a trapezoidal profile with a flat crest and inclined flanks, the pitch and the width or the root of which remains constant, while the inside diameter of the screw increases from the entry of the screw in the direction of the exit.

Abstract: A device for injecting aqueous nutrient solution (2) for hydroponic culture constituted of substantially horizontal supply pipes (9) located in the air space (3), held against the lateral walls (10) of the tank (1), injecting the nutrient solution (2) in the form of droplets through injection orifices (11) on opposed, substantially horizontal trajectories, thus improving their gaseous transfer capacity and their penetration into the nutrient solution to accomplish a continual saturation of this nutrient solution (2) with oxygen.

Abstract: An injection blow moulding apparatus and method, in which a preform (or "parison") is formed on a blow tube in a preform mould, the preform mould is opened, the blow tube and preform are moved clear of the opened preform mould, a blow mould is closed around the blow tube and preform, and a hollow body is blown in the blow mould and then released, the blow mould parts being continuously around the blow tube and being moved together and apart to close and open the blow mould.