Abstract: A boron and silicon oxynitride obtained by preparing a polyborosiloxane precursor, conducting nitriding pyrolysis of the precursor to obtain an amorphous boron and silicon oxynitride, and optionally conducting additional pyrolysis to obtain a crystallized boron and silicon oxynitride. The polyborosiloxane precursor is prepared by condensation, in the presence of a catalyst, of (2) a polychlorosilane represented by the formula R3R4SiCl2 in which the substituents R3 and R4 are identical or different and each represents a hydrogen atom, a chlorine atom, a linear or branched alkyl or alkenyl or alkynyl radical having 5 or less carbon atoms, or an aryl or aralkyl radical having 6 to 18 carbon atoms, with (2) an alkyl borate represented by the formula (R5O)3B in which R5 represents a linear or branched alkyl radical having 1 to 5 carbon atoms.

Abstract: A subsea thermoelectric generator has a plurality of flat thermoelectric modules attached concentrically to the outside wall of an undersea line in which petroleum products extracted from a subsea drilling well circulate. The thermoelectric modules are disposed in flat-bottomed pans machined into the outside wall of the line. The pans are sealed by lids made of heat-conducting material and in thermal contact with the thermoelectric modules. Each lid defines, with the walls of the corresponding pan, a peripheral sealed chamber. The various chambers in the pans communicate with each other through passages provided in partitions that separate the pans and are filled with a soft (compliant), preferably non-heat-conducting, resin. At least one of the pans is provided with an orifice closed by a sealed deformable element.

Abstract: The invention relates to the field of sonar antennas, in particular those intended to be installed on an underwater vehicle in order to constitute a mounted head of the vehicle. Specifically, the invention relates to a sonar antenna having at least two identical transducers that exhibit sensitivity peaks at at least two frequencies .nu., and .nu..sub.2, wherein the head mass dimension of the transducers is between 0.35 and 0.65 times the wavelength .lambda..sub.2 corresponding to the higher of the frequencies .nu..sub.1 and .nu..sub.2.

Abstract: A high reflectivity, broad band mirror for a high flux laser and a process for producing such a mirror. The mirror includes a substrate on which is formed a metallic layer such as aluminum. A stack of layers are formed on the metallic layer. The stack includes alternating layers of two materials with the refractive index of one material being higher than that of the other. A surface layer of a third material is placed on the stack. The surface layer has a refractive index which varies in accordance with the continuous periodic profile. The mirror is formed by depositing the metallic layer on a substrate and forming the stack by an ion beam sputtering method.

Abstract: The invention relates to a microwave antenna having at least one tubular portion with a central axis, and magnets which are located within the tubular portion along the central axis. The magnets generate a magnetic field in the vicinity of the antenna, with each end of each magnet facing an end having the same polarity of an immediately adjacent magnet. This type of antenna is used in the manufacture of microtips on large surfaces.

Abstract: The invention relates to a device for controlling the kinematics of pivoting elements designed to open substantially simultaneously to allow a clear passage of a weapon in a weapon launch tube equipped with a weapon launch circuit via an air distributor on board a submarine. The invention includes on the axis of rotation of each pivoting element and on the axis of rotation of a rotary element connected to the air distributor, a mechanism for converting a rotation into a translation, a mechanism for converting a translation into a rotation, and an associated mechanism for quantifying these conversions. The mechanism for converting a translation into a rotation on the axis of rotation of the rotary element is activated by the mechanism for converting a rotation into a translation on the axis of rotation of each pivoting element in association with the quantification mechanisms.

Abstract: The present invention relates to a multilayer material useful as an anti-erosion and anti-abrasion coating, and to a process for producing the multilayer material at low temperatures. The multilayer material comprises a substrate covered with at least one metallic tungsten ductile layer and at least one hard layer of a solid solution of an additional element chosen from carbon or nitrogen or a mixture of carbon and nitrogen in tungsten or a tungsten alloy, the two types of layers ar alternating. The multilayer material is particularly useful as a coating for parts used in aeronautics.

Abstract: The invention is directed to the class of submersible electro-acoustic transducers such as double "Tonpilz" transducers, wherein it is desirable to reduce the resonant frequency of the transducers while maintaining a given output power emitted by the transducers. The transducer according to the invention includes at least one horn solid with the end of a motor pillar, a hollow rigid box surrounding the horn and delimiting with the horn a cavity. The cavity communicates via a port with an external fluid, and has determined dimensions and external volume. The transducer further includes a passive radiator made of a material denser than the external fluid. The radiator obturates the port and hangs at a periphery of the port by an elastic material.

Abstract: A Marx generator, includes a number of capacitors (E) connected in series via spark gaps (E), between two output terminals and a power supply circuit that charges the capacitors in parallel. The capacitors are connected in series by a flat line formed of two metal strips running parallel and facing one another. These strips are connected together electrically at one end of the line and respectively to the output terminals at the other end and consist of one continuous strip and a second strip subdivided by transverse slots into successive plane sections interconnected in series alternately by a capacitor and a surface spark gap. A structure of this kind reduces the inductance of the generator and hence improves the rise time of the output pulses.

Abstract: The present invention relates to a process and transducer for emitting wide and and low frequency acoustic waves in unlimited immersion depth.The invention is applied to tranducers comprising at least one electro-acoustic motor (1) causing any wall 3 of the said waves to vibrate, and a hollow shell 5 enclosing the said motor 1, and delimiting with the said vibrating wall 3 among others, a cavity 7, characterised in that:at least one opening 5, causing cavity 7 to communicate with ambient medium 4, is made in said shell 5;in at least part of the volume of the said cavity 7, at least one flexible bladder 7, is installed;this bladder 8 is filled with a fluid 9 more compressible than fluid 4.

Abstract: A transducer includes at least one cylindrical driving assembly and at least one headmass coupled to an end of the cylindrical driving assembly. The headmass has an external ring that surrounds a core. The core is made from a core material that is less dense than the material from which the external ring is made. The headmass is dimensioned to occupy a predetermined volume so as to transmit waves within a predetermined frequency range. As a result, the transducer provides higher power waves, yet occupies the same volume as the transducers of the prior art.

Abstract: The invention concerns a process of preparation of the polyazido alcohols by reaction of a polysubstituted oxirane having in position .beta. a nucleofuge group with a metal nitride, characterized in that the reaction is performed in an aqueous medium.The oxirane formula is: ##STR1## in which X represents a nucleofuge substituent, R1 represents an atom of hydrogen, a lower alkyl group substituted or not by a halogen, an aryl group possibly substituted, R2 and R3 represent an atom of hydrogen, a lower alkyl radical possibly substituted, an aryl group possibly substituted, R4 represents an atom of hydrogen, a lower alkyl group possibly substituted, an aryl group possibly substituted by an alkoxy group. Application to the preparation of polyamino alcohols, ureas, polyazidothiols and binding compositions for propergols.

Abstract: The invention concerns an anti-corrosive pigmentary composition characterized in that contains zinc 8-hydroxy-quinolate.

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: A mechanism is described for attaching a fin to a projectile and for deploying the fin from a stowed position to a deployed position. In the stowed position the fin is parallel to a centrally located axis which extends from the front portion to the rear portion of the projectile. A mounting which is disposed in a bearing and to which the fin is attached permits pivoting of the fin and deployment of the fin in two phases. During the first phase the fin moves from the stowed position to a semideployed positions by rotation in the bearing about an axis normal to the projectile's centrally located axis. During the second phase the fin moves from the semideployed position to the deployed position by pivoting relative to the mounting.

Abstract: A device for measuring the wake of a sailing model in a trail tank is equiped with a platform capable of pursuing the model in the same direction and at the same speed as the model. The device includes five optical point measurement heads, carried on the platform and capable of moving horizontally with respect to the platform and crosswise with respect to the direction of pursuit of the model, thereby scanning the wake transversely and measuring the water surface undulation due to the model wake, in five adjacent vertical parallel planes forming a strip.

Abstract: A Tonpilz type piezoelectric transducer which can be used alternately as a wide-band receiver and an emitter includes a stack of pairs of piezoelectric segments separated by electrodes, the stack being placed between a horn and a countermass. An emitter is connected by a conductor to one of the two electrodes for each segment pair. One pair of segments next to the countermass is separated from the others by an insulator. The two electrodes to either side of the one pair are connected in parallel to a receiver and, through two diodes connected in opposition, to a grounded common conductor.

Abstract: A sabot arrangement is produced in accordance with an improved manufacturing method. The sabot arrangement includes a rotational symmetrical sabot body having a central axial bore and radial separating grooves or slots. The radial grooves or slots divide the sabot body into a plurality of equal segments. These slots nearly sever the sabot body into separate segments, so that a material bridge remains near a forward edge and a material bridge remains near a rear edge of the sabot body, which material bridges function as fracture zones.

Abstract: The present invention concerns hull shapes for a surface effect ship, including a catamaran type supported structure with two side walls (100) connected by a center platform (200), able to operate either as a buoyant displacement vehicle, or as an air cushion supported vehicle, the side walls (100) confining, with two sealing devices (310, 320), the supporting center air cushion (c).

Abstract: The device comprises a variable frequency AC generator with means of exitation supplied by means for controlling exitation current, means for regulation of the frequency of the generator as a function of an index value, means for measuring actual speed of the mobile portion of the motor, and means for comparing actual speed with the index value. According to the invention, the means for controlling the exitation current are connected to the means for comparing actual speed with the index value, and the generator has a high internal reactance.