Abstract: Disclosed is a device to control the output power of an amplifier working in class C mode and comprising at least one bipolar transistor. The bias resistance of the bipolar transistor is made variable through the presence of a field effect transistor, to the gate of which is applied a voltage Vgs, chosen from a set of values that are determined experimentally as a function of the output power to be obtained, the power and frequency of the input signal and the temperature of the bipolar transistor.

Abstract: Non symmetrical hollow fibres presenting a relatively dense layer (`skin`) (H) of a very small thickness (<1 .mu.m) at their outer periphery, which is bound to a so called `open` structure of which the porosity increases in the direction to the inner face; said porous structure comprises microvoids (1) shaped like elongate fingers open to the inside. The invention also relates to the method for obtaining such a symmetrical hollow fibres by known spinning techniques by dry-wet process, by adding to the solution for spinning the polymer in the solvent at least one particular additive and by adding a particular fluid through the hole of the extruded product. Finally, the invention aims at applying the hollow fibres in question to various fields and particularly in ultra-filtration or micro-filtration, in dialysis, reverse osmosis, in gas permeation or pervaporation or they may also be used as supports for liquid membranes.

Abstract: A measurement while drilling nuclear tool adapted to be coupled in the drill string to make formation evaluations and methods of using are described. A neutron source is positioned on the cylindrical axis of the tool while a connected gamma ray source is eccentered against an interior side of the cylindrical tool. Both sources can be axially removed from the tool along its interior. Novel source-detector configurations are provided in order to accommodate the constraints of the MWD environment. Gamma ray transparent windows are provided through both the drill collar and an external fluid excluder (stabilizer) at the positions of the gamma ray source and scintillator detectors. Neutron detectors may be of two different types at the same spacing from the source. Corrections are made for microphonic noise that arises while drilling and for natural gamma ray background. A drilling fluid density determination is made and is utilized to compensate for "borehole" or "standoff" effects.

Abstract: This unit is provided with two hydropneumatic jacks (2) having parallel vertical axes X--X and comprising bodies (5) adapted to be rigidly connected by a plate (3) and mounted slidably on rods (6) fixed to the chassis (7) of the vehicle. The plate (3) is sufficiently wide to allow if desired the passage of a transmission for the corresponding wheel. This arrangement improves the guiding of the wheels by holding them in fixed planes and enables them if desired to be made into driving and/or steered wheels.

Abstract: A method and apparatus for depositing a primer of programmed color on an object are described. In the method, a neutral primer base and at least one mono- or poly-pigmented paste are fed independently to a projection or spray device such an electrostatic deposition device comprising a rotary bowl. The base and paste are mixed in the device simultaneously while being projected or sprayed on the object.

Abstract: (a) Apparatus for regulating the concentration of an oxidizing solution, particularly a solution containing disinfecting molecules.(b) Apparatus characterized in that it comprises a secondary pipe (6) branched to a main pipe (1) upstream of a readjustment pipe (5) to which is fitted a measuring cell (2), as well as an addition pipe (12) connected to a reservoir (8) containing an adapting solution (7).

Abstract: A polycyclic heterocyclic compound has the formula ##STR1## wherein n is 1 or 2,R.sub.1 l represents (i) lower alkyl, (ii) --CH.sub.2 OH or (iii) ##STR2## R.sub.2 represents (a) hydrogen, (b) ##STR3## or (c)--OR.sub.3, R.sub.3 represents hydrogen, C.sub.1 -C.sub.20 alkyl mono or polyhydroxyalkyl, aryl or aralkyl optionally substituted, the residue of a sugar or ##STR4## wherein p is 1, 2, or 3, and r' and r" represent hydrogen, lower alkyl, mono or polyhydroxyalkyl, aryl optionally substituted, amino acid residue, aminated sugar residue, or together form a heterocycle,X represents oxygen, sulfur, SO, SO.sub.2 or --NR.sub.4,Y represents CR.sub.4 or a nitrogen atom andR.sub.4 represents hydrogen or lower alkyl.This polycyclic heterocyclic compound can be used in human and veterinary medicine and especially in the topical or systemic treatment of determatologic diseases.

Abstract: The network comprises several memory elements made of ferroelectric polymer, arranged in a matrix organization at the intersections of row and column electrodes. Each memory element (Mij) memorizes a synaptic coefficient a.sub.ij of the network which may be restored by pyroelectric effect on the corresponding column of the network. Amplifier circuits, respectively connected to the columns, give a voltage which is equal to the sum, to which a sign is assigned, of the products of the synaptic coefficients by the voltage components applied to each of the lines of the network.

Abstract: A sheath for a nuclear reactor control rod consists of chromium nickel stainless steel. It is protected against friction wear by nitridation over a depth of from 15 to 50 .mu.m obtained by an electric discharge in a nitrogen containing atmosphere.

Abstract: The invention relates to an angular measurement device comprising a variable reluctance magnetic circuit comprising a fixed portion (3) associated with a coil (2) and at least a moving element (4) attached to a part (5) rotating in front of the fixed portion, the angular position of which is to be detected, comprising: means (I) for integrating the voltage across the coil, means for measuring the instantaneous value of the integrated voltage (15), means for comparing this measure to a calibrating curve of the integrated voltage versus the angle.

Abstract: The invention relates to a process for preparing mineral and in particular, carbon-containing membranes on a porous mineral support. According to the process, at least one layer of a stable emulsion of mineral particles in a solution containing a thermosetting resin is deposited on a permeable, porous, mineral support. The resin undergoes a polycondensation treatment followed by coking, and the coke formed insures the mechanical connection of the mineral particles both to one another and to the support. The membranes produced according to the invention can be used in separating processes, particularly in microfiltration and ultrafiltration.

Abstract: Shock absorber (31) for a hydropneumatic vehicle suspension element, comprising a disk (32) fastened in an outer casing having ports (30, 38) for the passage of the hydraulic fluid, first elements (48, 49, 37a, 37b) allowing this passage in only one direction for some ports (30) and in the opposite direction for the other ports (38), and second elements (53, 54, 55) for fastening the first elements to the disk; the abovementioned first elements comprise, mounted on the two opposite faces of the disk (32), stacks (46, 47) of elastically flexible metal washers (46a-46c; 47a-47c) arranged in rigid annular deflectors (48, 49) located opposite the hydraulic-fluid passage ports (30, 38). The deflectors protect the flexible washers against any damage caused by the very high peaks of hydraulic pressure which occur on uneven ground.

Abstract: A tubular structure is provided including an internal tube and an external tube which is formed from at least a straight strip bent or undulated, whose width is disposed substantially along at least a line normal to said tubes which it separates. It may be used, for example filled with an insulating lagging, by surrounding a pipe line or being adapted to the pipe line which then forms the internal tube.

Abstract: The hydropneumatic jack comprises a tubular body (14) closed at one end and open at the other end. A hollow rod (9) is slidably mounted in the body (14) in a sealed manner and in the rod is formed a first chamber (18) containing a freely slidable piston (19) which divides the chamber into two compartments (18a, 18 b) which are sealed off from each other, a second chamber (23) being defined between a transverse end wall (21) constituting the end of the hollow rod (9) and the inner wall of the body (14). The transverse end wall (21) is provided with a nozzle (22) putting the second chamber (23) in communication with the neighbouring compartment (18b) of hollow rod (9). The compartment (18b) and the second chamber (23) are filled with a hydraulic liquid under pressure and the second compartment (18a) is filled with a pressurized gas. This jack automatically and instantaneously corrects the decreases in tension of the track (1) in the static state, subsequent to wear or expansion of the track and rollers.

Abstract: The graphic processor output dynamic range corrector system according to the present invention includes an input adapter for receiving a brightness signal from a graphic processor, an attenuator with an adjustable attenuation coefficient connected to the output of the input adapter, a reference voltage generator with an adjustable voltage level, a summing circuit for receiving output signals from the attenuator and reference voltage generator and for producing a corrected brightness signal, and decoding logic circuits connected to a computer connected to the graphic processor via an input interface, and connected to the attenuator and the reference voltage generator to control adjustment of the attenuation coefficient of the attenuator and the reference voltage level of the generator. The correction generator can be used in a brightness contrast analysis instrument equipped with a CRT to display stimuli at various spatial and time frequencies.

Abstract: Process for the manufacture of dialkylaminoalkyl (meth)acrylates (I) of formula:H.sub.2 C.dbd.C(R.sub.1)-C(O)-O-A-N(R.sub.2)(R.sub.3)R.sub.1 being a hydrogen atom or a methyl radical, A being a linear or branched alkyl radical containing 1 to 5 carbon atoms, and R.sub.2 and R.sub.3, which are identical or different from each other, are an alkyl radical containing 1 to 5 carbon atoms, or an aryl group, or R.sub.2 and R.sub.3 form a cyclic alkyl radical, in which ethyl (meth)acrylate is reacted with an aminoalcohol (II) of formula (R.sub.3)(R.sub.2)N-A-OH, A being a linear or branched alkyl radical containing 1 to 5 carbon atoms, in the presence of a polymerization inhibitor, at a temperature of between 20.degree. and 120.degree. C. and at a pressure equal to or lower than atmospheric pressure, in a molar ratio of ethyl (meth)acrylate to aminoalcohol (II) of between 1.

Abstract: An overheating and scaling control device for a fluid heating apparatus, such as a domestic water heater, removes the hot fluid in the heater when demand ceases. A piston (46) mobile within a case (28) separates the latter into two compartments (32, 36) respectively connected to the cold water supply pipe (16) and to the hot water discharge pipe (22). In operation, the pressure in pipe (16) is higher than the pressure in pipe (22) and piston (46) is moved to the left. On stopping, the pressures are equal in both pipes and spring (40) moves piston (46) to the right. Cold water is fed into the exchanger tube (20), so that the hot water contained in the latter is discharged into pipe (38) and compartment (36).

Abstract: An apparatus for the heat treatment of the necks 1 of performs 2 includes a rotatable mandrel 3, which is inserted in and engaged with the neck of the preform to rotate it, a fixed protective skirt 4, and a heater 5 situated at the level of the neck. A sliding weight 28 is applied to the upper end of the neck during the heat treatment.

Abstract: A device forming a swivel joint for a cryogenic liquid with at least one central duct for the flow of said cryogenic liquid through the joint and comprising at least one annular duct co-axially surrounding said central duct for the return of the cold gas originating from the vaporization of the moving liquid, said annular duct comprising gas inlet and outlet pipes; a stationary portion and a portion mounted in rotating relation to said stationary portion by means of a ball or roller bearing operating at a temperature close to ambient temperature, a double set of sealing gaskets also operating at a temperature close to ambient temperature; and heat insulation of at least the parts of said stationary and movable portions forming said annular duct and contacted by said cold gas, so arranged as to prevent any cooling-down of said sealing gaskets through convection or radiation; the device being applicable in particular to the off-shore transfer of liquefied natural gas.

Abstract: Several different symbols may be assigned to each key of the keyboard as requested by the operator. All the various symbols of the keys are recorded in a memory where they are organized in a certain number of pre-defined, distinct configurations of the keyboard. The configuration chosen by the operator is recorded in a display memory and displayed by means of a graphic unit on a flat panel, for example a liquid crystal display panel. The key actuated by the operator is identified by a decoding circuit to determine its symbol by means of the display memory and to display it on the flat panel.