Abstract: Composite material comprising a CAS+BAS vitroceramic matrix reinforced with SiC fibers and exhibiting a small difference between the thermal expansion coefficients of the matrix and the fibers is obtained by using a matrix having a BaO/(BaO+CaO) molar ratio of between 25% and 55% and predominant phases of triclinic anorthite and monoclinic celsian.

Abstract: An electromagnetic method for detecting and/or locating a person constituting a non-cooperative target, in which an electromagnetic signal is transmitted (1) in the vicinity of a search zone (N), and the signal returned by said zone (N) is detected (2) in the vicinity thereof, the method being characterized in that transmission and reception are performed by means of at least two distinct antennas, each signal obtained in this way is filtered by a lowpass or a bandpass filter (12) so as to extract therefrom components corresponding to human movement, and in that each filtered signal obtained in this way is processed (14) to deduce therefrom the presence of a person and/or to locate that person. The system enables the method to be implemented. Application to locating avalanche victims.

Abstract: A "master-slave" remote manipulation apparatus having six degrees of freedom. The apparatus includes a flexible parallelogram with two parallel arms hinged to a cross member with one degree of rotational freedom and to a frame with two degrees of rotational freedom; two parallel-hinged "master" and "slave" devices at the end of each respective arm; and five two-way linear motion transmitting devices between the "master" and "slave" devices.

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.

Abstract: A monolithic accelerometric transducer comprises a fixed part, two mobile mass parts and a resonator having ends fastened to said mobile parts, a flexible frame around the two mobile parts, and two connecting members connecting the frame to the second mobile part and to the fixed part. The frame provides a mechanical filter between the resonator and the fixed part which is not affected by the vibrations of the resonator. The quality factor Q of the resonator is not degraded and the measurement provided by the transducer is more accurate. In a differential output accelerometer, the position of the transducer is deduced from that of another, identical transducer by rotation of 180.degree. about an axis parallel to the resonator, the fixed parts of the transducers being fastened together.

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.

Abstract: A thermal barrier coating for a superalloy part used, in particular, in turbomachines comprises a ceramic coating and a sub-layer interposed between the superalloy substrate and the ceramic coating, the sub-layer being composed of a nickel and/or cobalt aluminide containing at least one platinum-like metal and at least one metal for promoting the formation of a layer of oxide constituted by the alpha-allotropic variety of alumina.

Abstract: Low viscosity, crosslinkable polysilanes that are liquid at ambient temperatures and essentially free of volatiles, well adapted for conversion into silicon carbide ceramics at elevated temperatures, are prepared by (a) reacting at least one silane monomer of the formula (1):R.sup.1 R.sup.2 SiCl.sub.2 (1)in which R.sup.1 is a hydrogen atom or a hydrocarbon radical and R.sup.2 is a vinyl radical, with at least one organic or organosilicon monochlorinated comonomer, in the presence of molten sodium in an organic solvent and wherein the ratio r.sub.1 of the number of moles of the silane monomer of formula (1) to the number of moles of the monochlorinated comonomer ranges from 0.

Abstract: A system for transmitting optical information uses several transmitters and receivers connected by optical fibers. The transmitters and receivers are arranged in individual networks in each of which all the optical fibers leaving the transmitters are coupled to one another and all the optical fibers arriving at the receivers are coupled to one another. In addition, all the optical fibers leaving the transmitters in each individual network are interconnected to the corresponding optical fibers, i.e., those leaving the transmitters, in all the other networks.

Abstract: A two dimensional supersonic air intake is provided for the combustion air f an aircraft engine comprising on one side a front flap (3) forming a visor and on the other side a fairing (4). The front flap (3) is movable about a pivoting axis (5) situated opposite the fairing (4). The front flap (3) is fast with a mobile fairing nose (6) situated in front of fairing (4) and moving in front of the latter when the front flap (3) moves in the direction which increases the air intake section.

Abstract: Apparatus for processing digitized images, the apparatus being of the type comprising a matrix memory (104) of pixels (106) organized as N lines (108) by P columns (110), together with processing means (130) for determining which pixels (106) are in the excited state by reading the memory (104). The processing means (130) operate by determining and storing the address of an excited pixel (106) that occupies an extreme position in a line or a column position, by switching said pixel (106) to a non-excited state, and by reiterating these operations until none of the pixels (106) is excited.

Abstract: The optical sighting device makes it possible to increase the quality of ical transmission by preventing turbulences from forming in the field of vision at high speed, by means of an airstream-deflecting device which is mounted in the turbulence formation zone and which has a profile in the form of a stem-post to dispel the air-streams laterally. In the case of transparent plane wall via which vision takes place in this zone, the deflecting device can consist of an attached plates which is connected to or located in the vicinity of the wall.

Abstract: Disclosed is a suspension spring for a vibrating piezoelectric plate including a first part fixed on a base and a second part for supporting the vibrating plate, the second part a tongue having a first and second end, the second end of the tongue supporting the vibrating plate, the spring being designed so that the end of the tongue which is the closest to the fixing point of the first part to the base is that which supports the vibrating plate.

Abstract: The installation comprises a certain number of measuring stations, represed here as three in number referenced respectively 1, 2 and 3, equipped respectively with antennae I.sub.1, I.sub.2, I.sub.3, which are connected by transmission lines L.sub.1, L.sub.2 and L.sub.3 to a central data acquisition unit 4, itself connected to a real time data processing unit 5. The central unit 4 comprises receiving means, means for sorting and associating the data and means for momentary storage of the sorted and associated data.

Abstract: A propeller nozzle, particularly for a missile, comprises a revolution pipe having a forward convergent portion, a minimum section, and a rearward divergent portion with a large outlet throat section. The invention is designed to minimize lateral forces in the nozzle due to a separation of gaseous fluid exhausting from the propeller, during the start of the propeller pressure increase. For this purpose, the pipe comprises means disposed in the vicinity of a section internal to the divergent portion and substantially downstream from the minimum section for making a gaseous fluid separation stable, symmetrical and coaxial to the nozzle. These means can include a groove and/or a projection, preferably destroyable through mechanical erosion and/or melting under the effects of the gaseous fluid.

Abstract: A low density nickel based superalloy having good creep characteristics w hot, and intended in particular for making turbomachine parts by monocrystalline solidification, wherein the composition of the alloy in percentages by weight is as follows:______________________________________ Co: 5% to 7% Cr: 5% to 10% Mo: 0.5% to 2.5% W: 3% to 5% Al: 6% to 7.5% Ti: 1.5% to 2.25% Nb: 0% to 0.5% Ta: 2% to 4% V: 0.3% to 0.6% Ni: balance to 100%. ______________________________________Parts, e.g. turbomachine blades, made from the alloy.

Abstract: The electron gun comprises an ionization chamber, adjacent to a high voltage chamber. In the wall common the both chambers provision is made for an extraction grid. On the opposite side, the ionization chamber comprises an outlet window for the electrons similar in shape to the extraction grid, and accompanied by a fine metallic foil. The high voltage chamber comprises a cathode brought to a high negative voltage. By giving the two grids the shape of similar parallel strips, a masking effect and a focusing effect are obtained at one and the same time which allows the efficiency of the electron gun to be increased.

Abstract: The invention relates to improvements to air propellers in so far as the profile of their blades is concerned. The law of evolution of the curvatures of the extrados 2 is the following: the curvature, maximum at the leading edge A, increases first of all rapidly to reach a value of about 4 at the point B at about 4% of the length of the chord, and then decreases regularly to reach a substantially zero value at the trailing edge F. The law of evolution of the curvatures of intrados 3 is the following: the curvature, maximum at the leading edge A, decreases first of all rapidly to reach a value of about 8 at a point D at about 3.5% of the length of the chord, then decreases less rapidly to reach a zero value at a point E situated between 10% and 60% of the length of the chord, decreases further to a slightly negative value and then remains practically constant as far as the trailing edge F.

Abstract: A microwave phase shifter comprise a dielectric waveguide having a flat side and a moving conductor plane member substantially parallel to the waveguide side. Piezoelectric means are provided to move the plane member with respect to the waveguide side between a portion relatively remote from the waveguide side and an other position substantially in contact with the waveguide side. The piezoelectric means consists preferably of a stack of piezoelectric members supplied by a variable d.c. power source. Owing to the piezoelectric means for moving the conductor plane member, a variable phase shift is continuously adjusted. Such a phase shifter can be as an antenna network when the dielectric waveguide contains groups of radiator perturbations, such as conductor strips, respectively controlled by one or several piezoelectric means carrying conductor plates facing waveguide portions including the perturbations groups.

Abstract: An optical system for analyzing and correcting wave fronts comprising a deformable mirror for correcting wave fronts and a system for analyzing and detecting phase distortion, an interferometer with lateral duplication constituting the analysis system, receiving the wave front for analysis and duplicating it and deducing from two neighboring wave fronts obtained signals to control deformation of the deformable mirror, wherein this lateral duplication interferometer is a polarization interferometer consisting of a Wollaston double-refractive biprism with an angle .theta., the two prisms being assembled head to tail and cut parallel to the crystallographic axis such that the respective axes are parallel and perpendicular to the edges of the prisms, a polarizer and an analyzer on either side of the biprism and an oscillating optical member on the path of the biprism.