Abstract: Disclosed is a sample-and-hold unit more especially designed to work at microwave frequencies (>1 GHz). In order to increase the sampling frequency, the disclosed circuit has at least two identical parallel channels. Each channel has a first follower switch (9) a capacitor (11) and a second holding switch (15). The channels are controlled by a single clock, the complementary or phase-shifted signals (H, H) of which address the samples sequentially towards the output (8). The disclosed device can be applied to the processing of analog signals.

Abstract: Oil compositions comprising crude oils, fuel oils, mineral oils and synthetic oils having high pour points are provided with one or more enhanced characteristics such as improved pour point, viscosity or viscosity index by the addition of a terpolymer comprising an alkyl ester of an unsaturated monocarboxylic acid, an olefinically unsaturated homo or heterocyclic-nitrogen compound, and an allyl acrylate or methacrylate or a perfluoroalkyl ethyl acrylate or methacrylate.

Abstract: Enhanced recovery of oil from an oil-containing particulate shale sludge is achieved by contacting the sludge with a light hydrocarbon solvent fraction, obtained from the processing of oil derived from the shale, in the presence of water to form an oil-solvent liquid phase which is separated from an aqueous phase containing oil-depleted shale. The oil-solvent liquid phase when introduced into a slurry of product oil and particulate contained within a shale retort provides several advantages, including lowering the viscosity of the product oil and enhanced separation of the product oil from the particulate shale.

Abstract: Morphologically improved, aggregated, monodispersed rare earth trifluoride particulates having a controlled and narrow grain size distribution, and a mean diameter of less than 1 .mu.m, are prepared by (i) reacting an aqueous solution of a rare earth salt with a solution of ammonium fluoride, (ii) separating the precipitate thus formed, and (iii) heat treating the separated precipitate.

Abstract: The invention provides a method for the catalytic low pressure reforming of gasolines, in the presence of hydrogen, in a reaction zone defined by a substantially cylindrical enclosure. The reaction contains a catalyst bed which has the form of a ring defined by two coaxial cylindrical walls, in which a plurality of hollow internal spaces defined by walls are entirely disposed. A heat-carrying fluid flows through the hollow internal spaces. The gasoline pass through the catalyst bed substantially perpendicularly to the longitudinal axis of the reaction zone.

Abstract: A process for the preparation of an aromatic ether of general formula: ##STR1## by the action of 3-chloro-1,2-propanediol sulfate on a phenol of general formula:Ar--OHin the presence of an inorganic base.Use of a product obtained according to the process for the preparation of adrenergic .beta.-blockers.

Abstract: A device for multimeasurement of vertical position variation of one or a number of predetermined points of an industrial or scientific construction of installation comprises means for measuring pressure which appears at the locations of these points and the variation of which is directly related to a variation in level of said points.

Abstract: A needle connecting apparatus for connecting a needle to a syringe and for covering the needle for disposal includes a connector housing. A first mounting point on the connector housing mounts the housing to a syringe body. A second mounting point on the connector housing mounts base of a needle to the housing. A rigid needle cover is movably mounted to the connector housing for exposing a needle mounted to the connector housing when in a first position and for covering a needle mounted to the connector housing when in a second position.

Abstract: The object of the present invention is a ceric oxide with new morphological characteristics. The invention also relates to one of the methods for obtaining said oxide.The method of the invention is characterized by the fact that a ceric hydroxide, prepared by base precipitation using a solution of a cerium salt, undergoes a solvo-thermal treatment before the calcination operation.The ceric oxide obtained has a large specific surface at high temperatures.

Abstract: Disclosed is a microwave (1 GHZ) sample-and-hold unit having a field-effect transistor, to which an input signal is applied, and a storage capacitor. The transistor is made of materials of the III-V group, such as GaAs or InP, and Its channel region is controlled by an optical control device formed by an optic fiber and a pulsed laser semiconductor. In order to reduce the switching time of the transistor, this transistor and the laser are both biased at points close to their thresholds. The disclosed device can be applied in signal processing, at frequencies of the order of 1 GHz.

Abstract: A blowout preventer is provided with an improved sealing assembly for sealing engagement with a pipe extending through the blowout preventer into a well bore. The sealing assembly includes an elastomeric seal and a plurality of circumferentially spaced metal inserts within the seal for substantially minimizing or preventing extrusion of the seal under high fluid pressure. The BOP be reliably used for sealing engagement with pipes of varying diameters. Each insert has a substantially I-shaped configuration with an upper flange, a lower flange, and a rib fixedly interconnecting the flanges. A slot is provided within at least one of the flanges and forms a cavity for receiving a male interconnecting member extending circumferentially from an adjacent one of the inserts, such that the circumferentially spaced inserts are interconnected to minimize extrusion gaps between the inserts and to better enable the sealing assembly to form a positive seal with the pipe.

Abstract: Ammonia synthesis gas is produced by reaction of steam, an oxidant, and a major portion of fresh hydrocarbon feed in an exothermic catalytic reforming zone to a first reformed gas having very low methane content. The balance of the fresh feed is reacted with steam in an endothermic catalytic reforming zone to a second reformed gas having a low methane content. The first and second reformed gases are combined and passed in indirect heat exchange with reactants in the endothermic reforming zone to provide all of the heat required therein and are then recovered as raw ammonia synthesis gas.

Abstract: The disclosure concerns X-ray tubes that are placed in a sealed casing and filled with a cooling liquid. The disclosed safety device is constituted by a thermostat and/or a pressure-sentitive switch, series connected in the power supply circuit of the filament of the cathode. In the case of a cathod with two filaments, the thermostat and/or the pressure-sensitive switch is or are connected to the common conductor. Thus, should a temperature or pressure threshold be exceeded, the supply to the filament is cut off, thus cutting-off the X-radiation.

Abstract: Synthetic lubricating oils having a predetermined alkylaromatic structure are prepared from a mixture of mono- or dialkenyl benzene with an aliphatic olefin by free-radical reaction in the presence of ditertiary-butyl peroxide, for example. Equivalent napthalene derivatives may be substituted for the dialkenyl benzene. The oils that are formed exhibit a high Viscosity Index, and a low pour point. The viscosity of the synthetic lube stock produced may be controlled by changing the amount of peroxide used.

Abstract: The acquisition of images of moving parts by NMR experiments requires the prolonged use of two series of excitation sequences. In the invention, only one sequence is enough. The radiofrequency electromagnetic excitation is itself modified to impose, from the very outset, a piece of information, representing the speed of the concerned moving parts, on the free precession signal. The imaging encodings which follow this particular excitation are standard ones. This particular excitation comprises, in principle, two excitations at 90.degree., having opposite directions, applied to one and the same axis and separated in time by a period during which a bipolar pulse of a magnetic field gradient is applied. It is shown that the magnetic moments of the fixed particles are re-aligned, at the end, with the orienting field while the magnetic moments of the moving particles are flipped with respect to this orientation, by an angle proportionate to their speed.

Abstract: A nitroxide radical of the formula (I) or (II): ##STR1## in which R.sub.1 and R.sub.2 are independently chosen from among the optionally deuterated alkyl, alkoxyl, dialkylaminyl and phenyl radicals, H, D or Cl; R.sub.3, R.sub.8 and R.sub.9 are independently chosen from among the optionally deuterated alkyl, alkoxyl and phenyl radicals; R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are independently chosen from among the optionally deuterated alkyl, alkoxyl, dialkylaminyl and phenyl radicals, COOH, OH, OD, H, D, a halogen, COOR (in which R is an alkyl radical); R.sub.10 and R.sub.11 are independently chosen from among optionally deuterated alkyl, alkoxyl, dialkylaminyl and phenyl radicals, COOH, OH, OD, H, D, a halogen, COOR (in which R is an alkyl radical) or represent an oxygen atom linked with the cycle of the radical by a double bond is described.

Abstract: A signal generator generates a temporal signal with a periodic configuration defined by an arrangement of seed patterns resulting from a branching construction iteratively using laws for composing several patterns and consisting in defining the periodic configuration of the signal as a component "a.sub.n " of the nth term Un with several components (a.sub.n, b.sub.n) of a recurrent sequence defined at the level of each of its components by a specific recurrent composition law, the initial term U0 having for its components the seed patterns (a.sub.0, b.sub.0). The temporal signals known as "fractal" signals result from a branching construction of this kind. The generator comprises a microprocessor (10) associated with a keyboard-display system (11), a read-only memory (12) for programs, a random access memory (13) and an output digital-to-analog converter (14).

Abstract: The invention relates to a dual brake compensator for a motor vehicle, comprising two correcting valves, of which the inlets are intended to be connected separately to two independent brake-pressure sources and the outlets to two independent brake motors, each correcting valve being capable of controlling the values of the pressures at its inlet and at its outlet according to a predetermined relation and comprising a piston subjected to elastic return means by an inlet member. According to the invention, the dual corrector includes a mechanism for comparing the positions of the inlet members of each correcting valve.

Abstract: The invention includes a control vector checking code respository located either within the same system as the crytographic facility or alternately remotely from the system containing the cryptographic facility. The control vector checking code repository will be linked to the cryptographic facility by one of several means. A first means for linking the repository to the cryptographic facility would include a physically secure data communications link. A second means for connecting the repository to the cryptographic facility would be by using an insecure channel with authentication, wherein either a modification detection code or alternately a message authentication code would be transmitted to the cryptographic facility and then the desired control vector checking code would be transmitted over the link. The cryptographic facility will include a code authorization mechanism to compare the transmitted MAC or MDC with a corresponding value computed from the received control vector checking code.

Abstract: The present invention relates to a method of manufacturing a heat exchanger comprising a bundle which consists of a plurality of tubes, a plurality of fins alternating with the tubes, at least one terminal end beam extending parallel to the tubes, and at least one collector plate at the end of the bundle. Clamping means are arranged in the vicinity of the collector plate, and in line with deformable means which are provided on projecting portions of the end beam or end beams.The invention is especially applicable to a heat exchanger for use in automotive vehicles.