Abstract: Disclosed is a new antenna structure having a quasi-hemispherical radiation pattern and capable of having a relatively wide passband, so that it is possible to define two neighboring transmission sub-bands therein or, again, a single wide transmission band. The antenna is of the type comprising a quadrifilar helix (11) formed by two bifilar helices (11.sub.1, 11.sub.2, 11.sub.3, 11.sub.4) positioned orthogonally and excited in phase quadrature, and including at least one second quadrifilar helix that is coaxial and electromagnetically coupled with said first quadrifilar helix (11). Preferred application to L band communications among geostationary satellites or transiting satellites with moving bodies fitted out with such antennas.

Abstract: A burner is disclosed which can be used in an apparatus for analyzing a gas omposition by flame spectrophotometry, comprising, disposed coaxially with each other, a tubular body having an open end on which an optical system is mounted coaxially, a sample taking nozzle which extends the body while defining an intake chamber, a collar fast with the body through which passes a tubular chimney, a nozzle for intake of the gas composition which is fitted in the chimney while forming therewith an annular intercalary chamber into which opens a fuel gas intake duct and a capillary tube for intake of the gas composition to be analyzed, this capillary tube being connected to the intake duct at the level of its end situated in the intake chamber.

Abstract: Method for producing a display screen with a matrix of transistors provided with an optical mask. This method consists of depositing on a substrate (100) a layer of black polyimide (102) absorbing the visible light and followed by a layer of photosensitive resin, of insolating the resin through a mask masking the channels of the transistors to be embodied, of eliminating the zones insolated with the resin and the sub-adjacent zones of the polyimide, of depositing an ITO layer (106) on the unit, of eliminating the rest of the resin and the ITO surmounting said resin so as to form the drains/sources of the transistors, of successively depositing a layer of hydrogenated amorphous silicon (110), a layer of silicon nitride (112) and a layer of aluminium (114), then of photoengraving the stack of these layers so as to form the gate of the transistors, and finally to render passive the unit with a layer of silicon (116).

Abstract: A device for coupling microwave energy with at least one exciter, and for distributing it therealong for the purpose of producing a plasma, includes a first enclosure whose inside is bathed in microwave energy, a second enclosure containing a gaseous medium to be ionized, and a first series of at least one communication passage between the two enclosures. An exciter is mounted to pass through each communication passage at a distance from the inside surfaces and to extend into the first and second enclosures in order to couple with a portion of the microwave energy and convey the coupled microwave energy locally into association with the gaseous medium. The exciter constitutes, together with the passage and portions of the sidewalls of the enclosures facing the exciter, a coaxial-type structure.

Abstract: A device providing physiological protection of aircraft pilots against the effects of altitude and accelerations includes a source of oxygen; a chest jacket fitted with at least one inflation bladder connected to a pressure reducing valve installed on a source of gas under pressure by a pipe; an oxygen mask connected to a source of oxygen by a conduit and a pressure reducing valve. The anti-g trousers include at least one inflation bladder connected to a pressure reducing valve, the bladder being mounted on a source of gas under pressure. The device further includes a mechanism to detect accelerations which delivers a signal representative of the acceleration. The device is characterized by a deformable volume located inside the inflating bladder of the chest jacket connecting the mask to the source of oxygen.

Abstract: A device for measuring radioactive contamination of a body includes a scintillator crystal (1) sensitive to gamma radiation emitted during disintegration of the radioactive elements (I, Cs, Co) contaminating a body to which the end of scintillator (1) is applied. A photodiode (2) converts the photons generated in scintillator (1) by the gamma radiation into electric charges. A mechanism (3, 7) converts these charges into amplified, frequency-filtered voltage pulses. Pulse counts in a plurality of bands and deconvolution effected by an electronic mechanism (8) built into the device allow measurement of the contamination of the body by each of the radioactive elements in question.

Abstract: According to the invention, the chip card issues a first certificate comprising its letter of credentials (Crc), an exponential (X), an optional message (M), these quantities being signed. The security module verifies the signature and in return issues a second certificate containing its letter of credentials (Crm), an exponential (Y), an optional message (M'), a cryptogram (C), these quantities being signed. A common secret key is constituted between the card and the security module by the exponentials and allows the card to interpret the cryptogram addressed to it and to act in accordance therewith.

Abstract: The present invention relates to a composite material. This material comprises at least one layer A of III-V compound and one epitaxial layer B on said layer of III-V compounds, the epitaxial layer corresponding to the empirical formula REPc, where RE is chosen from the group comprising the rare earths (scandium, yttrium, preferably lanthanum, lanthanides, and their mixtures); and where Pc is chosen from the elements of column V of the periodic table of the elements and their mixtures, and, when Pc contains arsenic, the compound REPc is at least a ternary compound.Application is to the electronics industry.

Abstract: The invention relates to equipment which includes a device for the analysis of gaseous compositions (1) to which is attached a device (16) for taking a sample of the substance to be analyzed and then vaporizing it. The analysis device (1) is connected to the sampling device (16) in such a way that it can use the vapors produced by the latter as a gaseous composition. The substance to be analyzed may consist of a liquid, or even of solid particles. The invention makes it possible to detect contaminated zones as well as the composition of the substances which cause contamination.

Abstract: The invention relates to a device for measuring the electrode potential of the reinforcement in underwater concrete. The device is of the type comprising a reference electrode placed against the facing of the concrete and a voltmeter connected to the reference electrode and to the reinforcement. The reference electrode is disposed in a bell suitable for pressing in watertight manner against a facing of the concrete, thereby delimiting an enclosure. The device further includes means for injecting compressed air into the enclosure and means for enabling the water imprisoned therein to escape.

Abstract: A device for the transmission of digital data with at least two levels of protection, of the type providing for the distribution of the data to be transmitted in the form of digital elements in the time-frequency space and the transmission of symbols each formed by a multiplex of N orthogonal carriers modulated by a set of the digital elements, and transmitted simultaneously, the device including channel encoding means comprising at least two types of modulation and/or at least two encoding efficiency levels. This enables to optimize the use of the transmission channel by assigning differentiated transmission techniques to portions of data of a same digital train as a function of the different levels of protection sought, against transmission errors.

Abstract: An encoding and transmission method with at least two levels of quality of digital pictures, each digital picture being formed by at least one matrix of encoded picture elements, wherein each of the pictures is cut up into blocks of picture elements, a reversible mathematical transformation is applied to each of the blocks of picture elements, the coefficients of the transformed picture blocks are quantized and the quantized coefficients are encoded. The transformed coefficients are divided into at least two digital trains, the first train including basic coefficients enabling the reconstruction of a standard quality picture, and at least one second digital train including a set of complementary coefficients enabling the reconstruction of higher quality pictures, in combination with the basic coefficients of the first digital train and possibly the coefficients of other complementary digital trains, the digital trains being processed and/or used distinctly, during the encoding.

Abstract: A monoaxial differential accelerometer with frequency output, includes a thin monolithic piezoelectric sensitive plate (10) in which plane a sensitive axis (X) is located. The plate (10) comprises two rectilinear slits (15, 15') parallel with the sensitive axis (X) and defining between them two zones of vibration aligned along the sensitive axis (X) and identically sensitive to the temperature variations. Each vibration zone is located between two electrodes (3, 4, 3, 4') to form resonators (20, 21) whose frequency variations are added for an acceleration directed along the sensitive axis (X) and whose the frequency variations are subtracted for an acceleration directed in a plane perpendicular to the sensitive axis (X). The resonators (20, 21) are inserted in the circuits of two oscillators (73, 74) whose beat frequency constitutes the output signal of the differential accelerometer.

Abstract: A method for the diffusion of digital data designed to be received notably by mobile receivers moving in an urban environment, that is, in the presence of stray signals and jamming, and in conditions of multiple propagation (Rayleigh process) providing an optimized mode of setting up the frame structure of the broadcast signal, so as to derive the maximum benefit from the resistance of the system to pulsed stray signals and to jamming. The header of each frame has a first empty synchronization symbol and eventually a second, unmodulated wobbled signal forming a two-stage analog synchronization system. So, the recovery of synchronization is achieved in an analog way, without prior extraction of a clock signal at the binary level. The constitution of the sequence of the useful symbols in the frame results from temporal and sequential interlacing operations, combined to obtain an implicit de-interlacing at the receiver.

Abstract: The station, in particular a terminal, comprises an oscillator (OS) having a feedback loop (1) and a station inductor element (L10) suitable for conferring a working frequency to the oscillator which varies relative to a rest frequency. The station also includes a station processor connected to the oscillator and capable of processing variations in the working frequency of the oscillator. The portable object, in particular a memory card, includes an electronic circuit which is switchable between an inactive state and an active state in which it sets up a resonant circuit tuned on a frequency which is distinct from the rest frequency while remaining suitable for being coupled inductively with the feedback loop (1) at the rest frequency. The portable object also includes an object processor capable of switching the electronic circuit as a function of the information to be transmitted to the station.

Abstract: Method for obtaining an organic polycrystalline material having in particular electro-optical properties, said material obtained and an electro-optical modulator comprising said material.This method includes a stage (1) for preparing a powder having a size grading of 500 to 800 nm of an organic compound having a delocalized system of electrons .pi. and presenting a non-centrosymmetrical crystalline structure, as well as intramolecular load transfer groupings, a stage (2) for drying the powder under vacuum, a stage (3) for pre-pressing the powder under vacuum, and a hot stage (5) for the uniaxial compression of the dried powder under vacuum.This method enables polycrystalline materials to be obtained, said materials comprising elongated monocrystalline grains orientated according to a given direction.

Abstract: An audio and video communications terminal, of the type comprising a housing, a camera provided with an optical system, a display screen, a microphone, a loudspeaker, and a central unit including a sound and image information encoder and decoder, and an interface in association with the elements for communication with another terminal of the same type via a digital transmission network, the terminal further comprising electric motors and clutches for adjusting at least one camera parameter; a manual control suitable for generating control information for adjusting the parameter(s); and a switch for switching between a local adjustment mode in which the control information is applied to the electric motors and clutches, and a remote adjustment mode in which the control information is sent to the other terminal over the digital network in parallel with the sound and image information, and in which control information received from the other terminal, likewise over the digital network and in parallel with sound

Abstract: The present invention concerns a convertible the capable of being transformed to change from a conventional mode of propulsion to a nuclear mode of propulsion. The submarine includes an aft section delimited by a pressure tight hull and two transverse bulkheads in which are located electric energy production and storage installations using batteries and diesel-generators. The aft section can be transformed to convert the submarine to the use of an anaerobic energy source by substituting for these installations, installations adapted to the anaerobic source of energy while preserving the integrity of the pressure tight hull and bulkheads, without internal substitution causing any substantial modification in the weight or centering of the aft section.

Abstract: Method for analysis of the content of certain elements in a continuous flow of bulk materials by neutron bombardment and measurement of the gamma radiation emitted by such elements, which makes it possible to distinguish between the capture radiation and the activation radiation. The neutron source is a neutron-generating tube which is activated periodically. The signals from a single gamma radiation detector are considered only after neutron emission has ceased, during distinct intervals corresponding to the phenomena of capture and radiation of the activated elements, respectively. The respective signals are treated in two distinct measurement routes, and the measurements are then combined automatically. A third measurements route can be provided for gamma radiation resulting from inelastic collisions. The source and the detector are positioned in a probe lodged in a polyethylene protective tube within the flow of the materials.

Abstract: A discontinuous drawn steel wire fiber for incorporation in a fiber composite, in particular a cement material, the fiber being made from a length of steel wire which is shaped so that the fiber is contained in a plane and, in said plane, is in the configuration of a loop which is convex and closed, wherein it has the configuration of an oblong loop whose ends are delimited by curvilinear wire portions, said curvilinear wire portions being interconnected by rectilinear wire portions, and wherein the two end portions of said length of wire are disposed side by side and in opposite directions, said end portions extending between said curvilinear wire portions to form one of said rectilinear wire portions.