Abstract: A sonar dome having an external wall in which a central layer is formed by a plurality of woven webs of glass fibers impregnated with a resin and by two peripheral layers located on each side of the central layer, the peripheral layers being constituted by a plurality of woven webs of carbon fibers impregnated with a resin.

Abstract: A circuit arrangement for controlling a brushless electric motor in which a control voltage derived from the rotor position is used to control the supply of line voltage to the stator winding of the motor. A control circuit which provides the control voltage is actuated several times over the areas intervals during one period of the line voltage, so that current pulses are applied to the stator winding for generating magnetic poles of opposite polarity to produce a rotating field with a frequency that is greater than the frequency of the line voltage.

Abstract: The invention pertains to a method and a device for the compression of digital images, the image being made up of a set of pixels, these pixels being assembled in classes, the number of which is predetermined, the method consisting in the creation, during the analysis of the image and each time that a pixel does not belong to the classes already created, a class to which the pixel would belong, this class being created on the basis of the radiometric characteristics of the pixel analyzed.

Abstract: A system is provided for the high speed reading of an image formed on the CCD sensor where the useful zones are formed of bands parallel to one of the directions of the matrix, and separated from each other by a gap without useful video information, each band and each gap being formed of several scanning lines, the geometrical arrangement of the bands on the matrix being known beforehand. The lines of each gap are transferred in succession into the register and the corresponding noise signals are not taken into account. The lines of each band are also transferred in succession so as to provided, pixel by pixel, the video signals summated in analog form for the band considered. The system applies more particularly to multichannel recording systems with streak camera.

Abstract: The present invention relates to an improvement to solid state photosensible devices of the type having a charge storing capacitor preceding the charge--voltage conversion stage. The photosensitive device of the invention comprises photosensitive detectors, each detector being connected to a charge integration cell, which is itself connected via a multiplexer to a charge--voltage conversion stage, preceded by a first storage capacitor connected to a resetting means with a supplementary storage capacitor located upstream of the first capacitor. The bias voltage of the supplementary capacitor can be brought to a high or a low level, as a function of the charge quantity to be integrated, for modifying the value of the capacitor receiving the charges.

Abstract: A circuit for high speed control a field effect power transistors. This circuit has a transformer with a primary winding and a secondary winding. The secondary winding transmits control signals to gates of the field effect power transistors. An energy storage structure is coupled to the transformer, and stores energy required for controlling the gates of the field effect power transistors. This energy is stored during an inactive phase of the control signal. A transmission structure is coupled to the transformer, and is fed with energy stored in the energy storage structure. In this way, the transmission structure uses energy stored in the energy storage structure to supply the control signals to the gates of the field effect power transistors. Therefore, the secondary of the transformer is not loaded during this time. At other times, the transmission structure isolates the output of the transformer from the rest of the circuit.

Abstract: An elastic foot for apparatus of consumer electronics, preferably a compact disc player, in which a rubber spherical part is provided with a convex cross-section and with a height which decreases under the weight of a load. In order to maintain the resonance frequency constant even when the foot is subjected to high weight of a series of stacked equipment units on the compact disc player, a protuberance formed inside the rubber part provides for an additional elasticity when the load exceeds a predetermined threshold value.

Abstract: An electrical and mechanical coupling for coupling a microwave head case both to its source and to its support including a back stop and source-positioning pegs. A toggle fastener system is mounted on one of its faces with the toggle fastener system including a draw-bar, a fixing portion, and an operating lever. A blade-shaped return spring has one end fixed to the support and is situated so as to enable the draw-bar to rest on the free end of the spring when the operating lever is pushed back. The source includes structure for engaging said source-positioning pegs, a flexible metal waveguide, a special flange disposed on a free end face of the flexible waveguide and having an opening therethrough and two centering pegs disposed on the special flange. A damper is disposed between the special flange and the body of the source. The microwave head case includes an assembly flange on a first face thereof. The assembly flange includes an opening for co-operating with said opening through the special flange.

Abstract: Field effect transistors are provided and more particularly those which work at very high frequencies.According to the invention the field effect transistor has a vertical structure, comprising an access electrode, source or drain, on each of the two faces of the substrate wafer. The gate is formed by an N type epitaxial layer thickness sandwiched between two N.sup.+ type layers. The gate thickness is then limited by the epitaxial layer thickness which can be obtained of the order of a few hundred angstroms. The gate contact is taken by means of lateral metal layers, on the chamfered sides of the epitaxial layer.

Abstract: A differential absorption polarizer is constructed to be used in accordance with integrated optics.This polarizer includes, on a waveguide layer formed on a substrate, a layer of dielectric material whose surface has hollows and bosses and therefore several inclined zones. The hollows and bosses define minimum (em) and maximum (eM) thicknesses of the layer, which bracket the resonance thickness of the dielectric for the polarization there to be absorbed.The dielectric material layer is coated with a metal layer.

Abstract: Valve seat structure for an automotive thermostatic fluid control valve device which is adapted to be positioned within a coolant fluid conduit system of an automotive engine. The valve seat structure has a rigid fluid flow control member which includes a cylindrical wall which forms a fluid flow passage. The rigid fluid flow control member also has an annular base which encompasses the cylindrical wall. An elastomeric sealing member resiliently encompasses the cylindrical wall. The elastomeric sealing member has an abutment portion and a clamping portion. Preferably, the abutment portion and the clamping portion are separated by a shoulder. A rigid clamping member has a clamping portion which is in engagement with the clamping portion of the elastomeric sealing member and is adapted to be clampingly engaged by a part of the coolant fluid conduit system. The rigid clamping member also has a shoulder portion which engages the shoulder of the elastomeric sealing member.

Abstract: A switching control circuit for a power transistor is provided. For applying an initial negative base current for disabling of the power transistor, a capacitor is provided which stores the energy required by charging not only when the power transistor is enabled but also when it is disabled. The capacitor discharges through a circuit for a time fixed by the time constant of a series RC network; this time is chosen of the order of time required for destoring the charges of the power transistor.

Abstract: A device is provided for mechanically coupling two parallel shafts together allowing rotation thereof in a 2/1 ratio in an angular sector defined, by producing a very rigid connection without lost motion, with a minimum of parasite torque and insensitive to environmental vibrations. It includes a first piece mounted on a shaft and having two guide elements and a second piece mounted on a shaft having two arms provided with flat surfaces on which the guide elements move. The center of these latter, as well as the axis of rotation of the second shaft, are on a circle centered on the axis of rotation of the first shaft. Preferably, one of the pieces is made in two parts, one being integral with the associated shaft and the other freely mounted on this shaft, and a return spring holds said guide elements against the flat surfaces, these elements being formed by ball bearings.

Abstract: A protection device for switch mode power supplies includes a main switch controlled by the output signals of a flip-flop. The flip-flop input receives regulation control signals. A first protection circuit supplies priority signals with respect to the regulation signals on the reset input of the flip-flop. The protection device also includes a cycle detector of the first protection circuit, a memory for accumulating at each cycle a value proportional to the duration between a signal of the detector and the set signal associated with the regulation cycle of the following cycle, and inhibiting of the flip-flop when the memory has accumulated a signal higher than a predetermined threshold.

Abstract: A device is provided forming a strictly ring interferometer having a ring formed by a monomode fiber, a source, separation and recombination means, and a monomode fiber segment forming mode filter. According to the invention, this monomode fiber segment is provided with a shutter generating directional losses intercepted by an optoelectronic detection member.

Abstract: A method for monitoring temperature in an enclosed space, especially a means of transportation such as an aircraft is disclosed. The method uses a wire or cable which has, between an inner conductor and an outer conductor, an element made of a material, the resistivity and dielectric permittivity of which vary with temperature. At one end of the cable, a check is made on the product RC of the resistance and the capacitance between the central conductor and the outer conductor.

Abstract: A vibration damper is provided for a towed body usable more particularly as head section of an underwater antenna towed by a boat and containing detection and measuring instruments.The damper of the invention comprises at least one piece with high loss angle in contact with a traction element so that vibrations perceived by the traction element cause deformations of said piece.

Abstract: A circuit device is provided for feedback controlling a transistor to switch off which is incorporated to a transfer circuit as the last stage thereof, and when, during the "off" phase, a current is drawn through its base by another transistor, referred to as the switch-off transistor, which is conductive for just the time required for said switching off to take place.

Abstract: The present invention provides a vacuum envelope for a radiation image intensifying tube and a process for manufacturing same. In a vacuum envelope of the type comprising a central body, an input window made from aluminum or an aluminum alloy at one end of said central body and a transparent output window at the other end of the body, said input window comprises a peripheral skirt fitting over a ring having the same section as said skirt, and made from iron or an iron alloy, integral with the end of the body, said skirt being welded to the ring by magnetic induction welding so as to be vacuum tight.