Abstract: A process for forming metal components of controlled porosity by welding, in which a predetermined amount of metal elements (50) of oblong shape is introduced into a mold (10) in which it is distributed isotropically. The metal elements are then subjected to increasing pressure (P) until the component has its final shape. The walls of the mold are then held in position and an electric current (I) flows through the metal elements and welds them together by local melting at the points of contact due to the Joule effect.

Abstract: In a process for analyzing the wavefront of a light beam, a diffraction grating with rectangular meshing is placed in a plane perpendicular to the light beam to be analyzed and optically conjugate with the analysis plane. Different emergent beams from the grating interfere to form an image whose deformations are related to the slopes of the wavefront analyzed. The grating multiplies an intensity function, implemented by a two-dimensional intensity grating, which defines a rectangular meshing of sub-pupils transmitting the light from the beam to be analyzed into a plurality of emergent beams disposed in accordance with a rectangular meshing, with a phase function implemented by a two-dimension phase grating which introduces a phase shift between two adjacent emergent beams such that the two emergent beams are in phase opposition.

Abstract: An aerodynamic surface, such as a wing, empennage, angle of drift, nacelle pylon and the like for an aircraft includes at least one lightening hole pertaining to the trailing edge of the underwing, at least one hinged baffle that can be mounted in the lightening hole of the underwing, whereby the chord thereof is equal to a several hundredths of the chord of the aerodynamic surfacer and an actuator for the moveable baffle so that it can rotate around the hinge line.

Abstract: A method and device for measuring the speed of at least one object by Doppler effect, whereby the light diffused by an object illuminated by a laser sheet is transmitted to a CCD video camera by spectral filtering means which are substantially tuned to the laser illumination frequency, means being provided to generate reference monochromatic luminous fluxes having frequencies which are different from the laser illumination frequency by fixed known amounts, and the reference luminous fluxes being transmitted to the CCD video camera.

Abstract: The invention concerns a transducer constituting the sensitive member of a sensor whose frequency varies as a function of the intensity of force applied to it. The force transducer comprises a beam having length and rectangular cross-section with thickness and width and flexionally vibrating. The beam has a thickness reduced over a central portion of its length, its width remaining constant.

Abstract: The present invention relates to a method for reducing the blade-vortex interaction noise of rotary wings. According to the invention: at least one value &PSgr;o of the azimuth of the blades (1) is determined, for which value said blades shed tip vortices giving rise to a peak intensity of noise; a trailing edge flap (2) is disposed on each blade (1), the former generating an auxiliary vortex (11), parallel to the tip vortex (10) and attached to a blade section (8) lying between the blade section (7) around which the speed circulation is a maximum and the tip section (3) of said blade; and a deflection is applied to each of said flaps (2) such that, for said value &PSgr;o, the speed circulation around said blade section (8) is a specified fraction of the maximum speed circulation.

Abstract: Measurements of the instantaneous position and speed of an aircraft are incorporated in co-operation messages regularly broadcast to other aircraft by radio. The device fitted on the aircraft, flying under visual flight rules, analyzes the data contained in the co-operation messages received from other aircraft and its own trajectory in order to identify potential risk of collision. The pilot is alerted to these potential risks of collision, advantageously in voice form, in messages identifying the direction in which the other aircraft is visible as well as an estimation of the time remaining until the potential collision.

Abstract: A heating zone (22) and a detection zone (23) at the surface (1a) of a part (1) are displaced in such a way as to carry out the scanning of the surface (1a) and a flux radiated in the detection zone (23) is detected by using a line of detectors (21) which is chosen from a matrix of detectors (20). The method makes is possible in particular to reduce the time for scanning the surface (1a) of the part and to be able to adjust the offset, in the direction of displacement (24), between the heating zone (22) and the detection (23), simply by choosing the line (21) of the matrix of detectors (20). The method and the device in accordance with the invention make it possible in particular to carry out thermographic inspections of parts made of any materials and in particular of metal parts which may have considerable dimensions and complex shapes.

Abstract: A vibrating rate gyro structure machined in a plate of material and comprising a fixed part, a resonator, and a mechanical system connecting the resonator to the fixed part. The mechanical system comprises a first mobile mass part connected to one end of the resonator, a second mobile mass part (4) connected to the resonator and situated in the vicinity of the other end of the resonator, two flexible arms situated on both sides of the resonator and each connecting the first mobile mass part to the second mobile mass part, and two other flexible arms situated on both sides of the resonator and connecting the second mobile mass part to the fixed part.

Abstract: The invention concerns a method for producing a flame support for a gas burner, which consists in producing disjointed metal fibres (10) in an alloy comprising iron, chromium and aluminium; assembling the fibres together under pressure; bringing the fibre mat to a temperature sufficient to ensure a close bonding between the fibres. The invention is characterised in that it consists in feeding said metal alloy to an overflowing tank (3), to produce the fibres by cooling in contact with a mobile wheel (7); then in arranging in a moulding matrix the resulting disjointed fibres (10) and compressing them to form an agglomerated mat; then in connecting the mat to electrodes and a capacitor, thereby bringing the fibres (10), at their points of contact, to a temperature not less than their melting point, to produce fibres closely welded together, under high voltage.

Abstract: A monolithic miniature accelerometer machined in a plate of material, comprising a fixed part, two first mobile mass parts referred to as inertial masses, two hinge blades each having one end fastened to one of the two mobile mass parts, and two resonators each having one end fastened to one of the two mobile mass parts, a third mobile mass part fastened to the other end of each of the two resonators and of each of the two hinge blades, and a flexible stem situated between the first two mobile mass parts and connecting the third mobile mass part to the fixed part.

Abstract: The invention concerns a blade profile for aircraft rotor, comprising, between a leading edge (1A) and a trailing edge (1B), a suction face (2) and a blade face (3) whereof the geometric locus of the equidistant points of the latter defines the curvature. The invention is characterised in that the value of the ratio of the maximum curvature to the maximum thickness develops linearly with the profile (1) relative thickness and ranges between 0.13 and 0.19 for a relative thickness of 7% of the chord (C) and ranges between 0.18 and 0.24 for a relative thickness of 15% of the chord (C).

Abstract: A vibrating rate gyro structure machined in a plate of material and comprising a fixed part, a resonator, and a mechanical system connecting the resonator to the fixed part. The mechanical system comprises a first mobile mass part connected to one end of the resonator, a second mobile mass part (4) connected to the resonator and situated in the vicinity of the other end of the resonator, two flexible arms situated on both sides of the resonator and each connecting the first mobile mass part to the second mobile mass part, and two other flexible arms situated on both sides of the resonator and connecting the second mobile mass part to the fixed part.

Abstract: The scanning of a surface of a part is carried out by a means of imparting heat to at least one heating zone at the surface of the part. This occurs by relative displacement of the part and of the means of imparting heat. A detector is used to sense the flux radiated by the surface of the part in a detection zone displaced synchronously with the movement of the heating zone. The detector delivers, for each of the positions of a set of successive positions of the detection zone, a signal representative of the flux radiated. The scanning of the surface of the part is carried out along a determined path, in a first direction, then in a second opposite direction. For each of the successive positions of the detection zone, a differential signal is formulated.

Abstract: A monolithic miniature accelerometer machined in a plate of material, comprising a fixed part, two first mobile mass parts referred to as inertial masses, two hinge blades each having one end fastened to one of the two mobile mass parts, and two resonators each having one end fastened to one of the two mobile mass parts, a third mobile mass part fastened to the other end of each of the two resonators and of each of the two hinge blades, and a flexible stem situated between the first two mobile mass parts and connecting the third mobile mass part to the fixed part.

Abstract: The device for the individual control of the blades includes at least two sets of rotating swashplates centered on the rotor axis and non-rotating swashplates at least inclinable in all directions under the action of at least two actuators inserted between the first set and a non-rotating structure, and under the action of at least one other actuator inserted between this structure and the second set. Each non-rotating plate is held by a connecting piece to the non-rotating structure, and each rotating plate is rotated with the rotor and connected to at least one blade respectively of the rotor via a respective pitch rod. The device also includes at least as many actuators as the rotor has blades, and all the actuators are non-rotating.

Abstract: The invention concerns a process for manufacturing a part made of high temperature-resistant, ceramic material based on aluminum nitride and reaction sintering. The process comprises the steps of preparing a homogeneous mixture of boron nitride powder, aluminum powder and a paste-like binder, capable of solidifying by chemical reaction and by solvent loss through drying. The mixture is formed by mold casting and then pressed and heated, to a temperature not exceeding approximately 70° C., to harden the binder and to obtain a solid and manipulable unfired part. The binder is eliminated by heating to a temperature of approximately 300° C. Pores of the unfired part are impregnated by immersing the part in a bath of molten aluminum or aluminum alloy to form an impregnated preform. Thereafter, the impregnated preform is removed from the bath, cooled, and machined to the final dimensions of the part. A ceramic is obtained by reaction sintering the machined part at a temperature of 900 to 1000° C.

Abstract: Alloy of the Ti2AlX type composed at least essentially of the elements Ti, Al, Nb, Ta and Mo and in which the relative amounts as atoms of said elements and of silicon are substantially within the following intervals: Al: 20 to 25% Nb: 10 to 15% Ta: 1.4 to 5%   Mo: 2 to 4% Ti: remainder to 100%. This alloy exhibits properties superior to those of the known titanium alloys.

Abstract: A blade is disclosed for an aircraft rotating aerofoil. The aerodynamically profiled main part of the blade includes an external end part adjacent to the tip of the blade and extending along the span over a distance of at least 0.2 R, where R is the radius of the rotor. The end part having a rear camber over a distance along the span of at least 0.15 R, and the aerodynamically profiled main part includes also a front cambered part, immediately adjacent to the inside of the rear cambered end part.

Abstract: The invention relates to conjugated compounds of general formula (I) ##STR1## wherein X.sub.1 and X.sub.2 are, independently of one another, electron-withdrawing or electron-donating systems, and to a process for the preparation of these compounds.The invention also relates to any material which includes the compounds of general formula I and to the use of said compounds or of any material which includes them in electronic, optoelectronic, nonlinear optical and electrooptical devices.