Abstract: Some embodiments are directed to a high impedance surface device. The high impedance surface device can include a set of at least two separate, substantially cylindrical compartments, that have internal surfaces in an electrically conductive material. The compartments each define, at one end, a single aperture, oriented on the same side, and covered by at least one periodic structure of electrically conductive patterns. Each compartment is filled with a dielectric material, and is thus covered forming at least one electromagnetic resonator. Each electromagnetic resonator exhibits a resonant wavelength. The at least two compartments are separated from one another by a distance less than the shortest resonant wavelength exhibited by the resonators that they form. At least two respective resonant wavelengths of the electromagnetic resonators formed by the at least two covered compartments are different, and the periodic structure exhibits a spatial period less than half the shortest resonant wavelength.

Abstract: A blade for a fan of a turbomachine, for example of unducted fan type, a corresponding fan, and a corresponding turbomachine. The blade includes a mechanism arranged, at a single location, to locally, as the fan rotates, disturb a distribution of flow around the blade so as to form two independent main vortices downstream.

Abstract: A blade for a fan of a turbomachine, for example of unducted fan type, a corresponding fan, and a corresponding turbomachine. The blade includes a mechanism arranged, at a single location, to locally, as the fan rotates, disturb a distribution of flow around the blade so as to form two independent main vortices downstream.

Abstract: A method for forming a protective coating containing aluminum on the surface of a metal part, wherein the part is contacted with a carburizer made of an aluminum alloy, at a treatment temperature and in a chamber, the atmosphere of which contains an active gas which reacts with the carburizer to form a gaseous aluminum halide, which decomposes upon contacting the part while depositing aluminum metal thereon. In the method the aluminum alloy of the carburizer includes at least one element, zirconium and/or hafnium, the active gas reacting with the carburizer to also form a halide of the reactive element which decomposes upon contacting the part while depositing the element thereon at the same time as the aluminum.

Abstract: A method for forming a protective coating containing aluminum on the surface of a metal part, wherein the part is contacted with a carburizer made of an aluminum alloy, at a treatment temperature and in a chamber, the atmosphere of which contains an active gas which reacts with the carburizer to form a gaseous aluminum halide, which decomposes upon contacting the part while depositing aluminum metal thereon. In the method the aluminum alloy of the carburizer includes at least one element, zirconium and/or hafnium, the active gas reacting with the carburizer to also form a halide of the reactive element which decomposes upon contacting the part while depositing the element thereon at the same time as the aluminum.

Abstract: A process for measuring speed or vibration characteristics using a LIDAR device allows the separation of a useful contribution and an interfering contribution in a backscattered signal. To this purpose, a phase characteristic of an optical wave emitted in the direction of a target volume is modulated. The interfering contribution, which originates from a source at a distance from the target volume, appears with variable shifts of said phase characteristic in a heterodyne detection signal. An accumulation then isolates the useful contribution, from which a result is obtained for the speed or vibration measurement. The process can be implemented with a frequency modulation or phase modulation of the optical wave.

Abstract: The invention relates to a three-dimensional sheet structure characterised in that it comprises at least: a first sheet (1) comprising a plurality of first ribs (3) on one surface thereof; and a second sheet (2) including on one surface thereof a plurality of second ribs (6) intersected by flutes (9) having a shape complementary to that of the first ribs (3) of said first sheet (1); and in that said first and second sheets (1, 2) are superimposed and attached together, each of said first ribs (3) of said first sheet (1) being received in one of said flutes (9) of said second sheet (2).

Abstract: The engine comprises a low pressure stage (1) and a high pressure stage (2) with two independent rotors (3,4) and associated fixed fluid preparation members (9,10,13,14), combining “compressor” means (15,16) and “expander” means (17,18) and at least one combustion chamber (19,20) in a central volume defined axially by the rotors (3,4) and laterally by three substantially cylindrical, coaxial walls (22,23,24), defining in pairs an outer duct (25) connecting the outlet of the LP compressor (15) to the inlet of the HP compressor (16) and an inner duct (26) connecting the outlet of the HP compressor (16) to the inlet of a first combustion chamber (19), whose outlet supplies the HP expander (18) with gases produced by combustion guided to the inlet of the LP expander (17), whose outlet is in communication with the outside via at least one exhaust opening (41) for the combustion gases.

Abstract: A sensor comprises two identical vibrating members operating with a common working frequency and joined to each other by a mechanical decoupling device. The device comprises a frame and two connecting bridges each supporting one member. The frame comprises a succession of mass portions and thinned portions so that the frequency of one mode of structural resonance of the frame is substantially equal to the common working frequency, and each connecting bridge is disposed in a node of vibration of the frame at the common working frequency. Thus, the vibrations of the two vibrating members are decoupled from each other.

Abstract: In a nonlinear optical medium such as the gallium arsenide, two collinear incident monochromatic waves are injected to generate a monochromatic wave. The medium induces between the three waves a propagation phase-shift that has a value ? if the three waves travel a coherence length in the medium and that is compensated at the value 0 modulo 2? each time that the three waves have travelled a periodic distance in the medium. In order to significantly increase the conversion efficiency, the periodic distance between two successive bounces of total internal reflection of the waves in zig-zag is strictly less than the coherence length. The high conversion efficiency on a very short material length leads to product high-power coherent optical sources particularly with wavelengths of approximately 10 ?m.

Abstract: The invention aims to integrate a two-wave stationary interferometer on a photodetector during fabrication in order to constitute a miniature stationary Fourier transform spectrometer. The interferometer essentially comprises a plate having a first plane face coinciding with an image plane on semiconductor photosensitive elements and a second face that is not parallel to the first face. The second face reflects a wave that has a phase difference relative to the incident wave interfering with it that is a function of the local thickness of the plate.

Abstract: The present invention relates to a sandwich-structure flat active actuator that is symmetrical relative to the mid-plane comprising at least one piezoelectric flat layer having an active direction superpose and fixedly attached to at least one passive flat layer of fabric with rigid warp and weft oriented in two directions forming a mesh; the two directions of each layer of fabric are the same. The active direction of each piezoelectric layer is oriented along one and the same diagonal of the mesh of the layers of fabric. The invention is also aimed at a device consisting of two actuators mounted head-to-tail. The invention applies to the active torsion of structures such as, for example, a helicopter blade.

Abstract: The invention concerns a passive radar receiver with an array of antennas for a OFDM received signal comprising frames of symbols each emitted on coded orthogonal carriers. After formatting received signals into digital symbols, dummy signals from dummy OFDM emitters at different distances from and in different directions relative to the receiver are generated and added to the signals picked up by the antennas. The modified received signals are filtered by means of inverse covariance matrices in order to eliminate at least unwanted zero Doppler effect signals and to provide an isotropic reception diagram without blind sector of direct path being generated and by detecting mobile targets along the direct path.

Abstract: The invention concerns a passive radar receiver for a received orthogonal frequency division multiplex-type signal consisting of symbol frames each emitted on coded orthogonal carriers. After formatting the received signals into digital symbols (S1 S1), a filtering circuit (2) eliminates by subtraction or using a covariance matrix, in the symbol signal at least unwanted signals with null Doppler effect so as to apply a filtered signal (X?) including essentially signals backscattered by mobile targets to a Doppler-distance correlator (4).

Abstract: The invention aims to integrate a two-wave stationary interferometer on a photodetector during fabrication in order to constitute a miniature stationary Fourier transform spectrometer. The interferometer essentially comprises a plate having a first plane face coinciding with an image plane on semiconductor photosensitive elements and a second face that is not parallel to the first face. The second face reflects a wave that has a phase difference relative to the incident wave interfering with it that is a function of the local thickness of the plate.

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: 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: 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: 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 present invention relates to a blade with a swept-back tip for a rotary wings of an aircraft, a blade being formed of successive elemental cross sections. The blade is divided into different regions, with the chord length L and the offset y'f of the center of pressure from the pitch-change axis and the relative thickness of each elemental section are optimized for high-speed flight. The first region has a linearly increasing chord length, the second region has the maximum and constant chord length, the third region has a linearly decreasing chord length and the fourth region has a decreasing chord length according to a parabolic function. The offset of the aerodynamic center is positive and increases in proportional to the distance in the first region, is at its maximum and constant in the second region, and decreases linearly and become negative in the third region.