Abstract: The electrochemical measuring technique of the present invention employs, as the barrier material, a concentrated electrolyte, which also forms a medium for the controlled dissolution of a surface of the semiconductor so as to provide a continuous depth profile. The depth profile characteristic may be determined by capacitance-voltage measurements on n-type bulk GaAs, using KOH as the electrolyte.

Abstract: Apparatus for reproducing a half-tone image of an original comprises a support, preferably in the form of a cylinder, for a light-sensitive record medium, an exposing head for exposing a record medium on the support, and means preferably in the form of a mechanism for rotating the cylinder and a lead screw for moving the head axially of the cylinder, to produce a relative scanning motion between the exposing head and the record medium. The exposing head includes a row of side-by-side light modulators or light sources extending in a direction such that the areas illuminated by the modulators or sources on the record medium extend in a direction across the width of a scanning line on the record medium. The area of illumination of the record medium provided by each light modulator or source varies in the said direction and is of lower intensity at its ends than at its middle and each area overlaps the areas of illumination provided by adjacent modulators or sources.

Abstract: A system for positioning a displaceable member with respect to a reference conventionally uses a servo-mechanism having feedback position sensing and speed sensing loops connected to an input of the control path of the servo. Usually, the system operates in two successive phases:- a coarse positioning phase and a fine positioning phase. In the fine positioning phase, both loops are active. Nevertheless, if the reference tends to fluctuate, the accuracy of the final positioning may be less than acceptable. In a system according to this invention, an additional device is provided which, under a threshold value of the output of the position difference sensor, disconnects the speed difference sensor and inserts in the single remaining loop series correcting networks which, in addition to ensuring improved accuracy of the final positioning, also ensures an accurate follow-up of the fluctuations of the reference.

Abstract: A process for establishing gold contact studs on thin film circuits consists in localized sublayer deposition of a platinum-gold alloy followed by subsequent electrolytic gold thickening of the studs. The studs so produced are particularly fit for thermocompression interconnection.

Abstract: A field selection data operating device consists of three cascade connected circuits: a field selector and shifter circuit, an arithmetical and logical operator circuit and a bit shifter and concatenator circuit. The selector and shifter circuit is controlled by a field length code, a shift value code and a first field bit rank code. It comprises two stages of multiplexing members. The first stage ensures, in circular permutation, a shift of the bytes of an applied data word so as to place the byte containing the bit of the first field bit rank code at the place in the word pointed by the shift value code and the second stage completes the shift to the said bit in the byte and generates an output mask according to the field length code. The mask is also applied to concatenation control inputs of the bit shifter and concatenator circuit.

Abstract: A flat bed truck or trailer is provided with extensible side plate members or segments to increase the area of the truck or trailer bed. The side members are capable of being retracted when not in use so as to lie substantially within the area of the truck or trailer bed. When in their extended position, the side members are provided with suitable supports to lend strength and rigidity thereto. The increased bed area enables farm machines, such as tractors, combines, windrowers and the like as well as off highway earth working machinery to be readily supported thereon while being transported from one area to another.

Abstract: The invention concerns an integrated magnetic head adapted to cooperate with a track of a very narrow width, f.i. of about twenty microns, of a recording medium which moves perpendicularly to said width in close proximity to the frontal gap face of the head. The frontal width of the pole-piece layers of the head is reduced after said layers have been formed with a larger width adapted to a normal electromagnetic efficiency of the head in the parts of the said pole-pieces which encase the front branch of its flat conductor winding coil. The reduction is obtained by removal of the lateral parts of the pole-pieces over a predetermined depth with respect to the frontal face. Any registering part of an intervening dielectric layer between the pole-piece layers for defining the magnetic gap of the head is simultaneously removed. It is important that the removal be made by an attack such as a ionic erosion process perpendicularly oriented to the frontal plane of the head.

Abstract: Sequential/interlace scan conversion of NTSC or PAL color television signals is effected by an encoder the output of which is connected to the input of scan conversion apparatus. Controllable phase shift means is included in either the color signal input or the subcarrier input of the encoder and is adapted to vary the phase of the modulated subcarrier for each line of the received color signal by an essentially integral number of quarter cycles in dependence upon the line number. The control is such that the conversion apparatus provides an encoded output signal with the color subcarrier in PAL or NTSC format. The invention can also be used in converting between different types of interlace systems.

Abstract: This invention concerns gyrator circuits, and particularly gyrator circuits used in filters. The gyrator network contains two differential input operational amplifiers and an input network, some of the elements of which are variable to enable the Q, the bandwidth and the resonant frequency to be adjusted in such a way that previously adjusted parameters are not changed. The circuit may have three configurations according to the position of a pair of ganged switches, alternatively the switches may be replaced by fixed links.

Abstract: Two microprogrammed processors of identical hardware and software facilities are synchronously operated for exchange operations with a plurality of external store and peripheral units. The exchange connections from the processors to the external units pass through gate circuits one of which only is operative at a time. Each processor has an output at which all processed words, whether instructions, microinstructions, operands or results are successively available. Comparator means permanently compare such words from the two processors and, when a mismatch occurs, block the gate circuits and their own comparison outputs and control execution in both processors of a failure detection and check up routine. Each processor includes exchange control claiming and exchange control disclaiming outputs.

Abstract: The invention provides a structure for a read-only integrated magnetic head which, without any recourse to a shield, ensures or at least enables the elimination from the read-out signal transferred from the head to the external circuits it must feed, any component which might be due to the application of spurious electromagnetic fields to the surface comprised by the flat conductor winding coil and to the surface intervening between the output leads of said coil up to the rear edge of the substrate which carries the integrated magnetic head.An additional flat conductor winding coil is provided over the read-out coil. Said two coils register but they are mutually magnetically decoupled, by means for instance of an intervening non-magnetic dielectric layer of appropriate thickness.

Abstract: An active resonant circuit to be used as a cell for a low insertion loss high level microwave filter is disclosed comprising a circuit tuned at f.sub.o inductively coupled with a negative resistance amplifier consisting of a transistor with a cut-off frequency high with respect to f.sub.o , an emitter circuit coupled to said tuned circuit, with a high transformer ratio, an adjustable tuned circuit in the base of said transistor and means for biassing said transistor for maximum negative resistance at f.sub.o . Two or more cells may be associated to constitute a filter.

Abstract: A valve device for use in liquid pressure vehicle braking systems to control rear brake pressure comprises a plunger in a cavity in a housing, the cavity being closed at one end. The plunger has a land which slides within a portion of the cavity. The area of the plunger that is exposed to liquid pressure at the closed end of the cavity is greater than the area of the plunger that is exposed to liquid pressure on the other side of the land. A passage through the land is inclined to the axis of the plunger. A valve unseating pin in the inclined passage co-operates with a frusto-conical surface of the cavity to unseat a ball in the inclined passage. A biassing spring surges the plunger towards the closed end of the cavity against the action upon the plunger of rear brake pressure which acts upon the larger presented area portion of the plunger. Liquid pressure is transmitted from the master cylinder to the rear brake operating motor cylinders when the ball is unseated and not when the ball is seated.

Abstract: A dielectric optical waveguide coupler for optically coupling together two lengths of dielectric optical waveguide consists of a tube having a capillary bore, into which may be inserted, from each end of the tube, the two dielectric optical waveguides to be joined. The capillary bore is tapered at each end to facilitate the insertion of the dielectric optical waveguides. The dielectric optical waveguide coupler may be made by immersing a capillary bore tube with its capillary bore filled with water into an etchant solution.

Abstract: An apparatus for expanding a tube or pipe by axially compressing an annular resilient element to cause said element to radially expand into engagement with the inner surface of the tube or pipe. The compressing of the resilient element and its radial expansion is caused by a main piston and cylinder structure which is subjected to fluid under pressure. A secondary or impact piston is provided in the main piston for applying higher stresses to the tube or pipe through the resilient element. The resilient element is interposed between a plurality of spaced annular ring members which constitute guide means therefor.

Abstract: Digital words are transmitted together with associated parity or checking digits. The parity bits are each related to a group of bits of the same significance from several different words. At a receiving station, a parity bit is generated for the same group from the incoming words and compared with the corresponding received parity bit. When the generated and received parity bits differ, a value is estimated for each word containing a bit from the respective group, and the estimated and received values for the word are compared to detect any word containing an erroneous bit, which bit is then corrected.This invention relates to the transmission of digital signals.In digital television systems the video signal is commonly represented by a series of eight-digit binary numbers. If any of the bits are altered by errors, then the effect appears as a brightness error in the picture, the magnitude of which depends on the significance of the affected bit.

Abstract: An electric timing circuit for the time delayed delivery of a voltage pulse to an electric fuze element or other current or voltage sensitive element uses a capacitor voltage source which can be charged from an external source of electric potential. The capacitor discharges through the leakage resistance of its dielectric and through leakage resistance of semiconductor devices in the biased "off" state, until the capacitor voltage decreases to a preset value, at which time a threshold value switch connects the electric element to the capacitor voltage source. The threshold value switch is constituted by two series connected Field Effect Transistors, one N channel type and one P channel type. Both transistors are biased in the "off" condition by the circuit connections until the capacitor voltage decreases to the threshold level and turns both transistors "on". The two non-conducting transistor channels in series permit a very long discharge time for a given capacitor.

Abstract: Dielectric optical waveguides can be made having a core of vitreous silica doped with nitrogen in the form of silicon nitride, and a cladding of pure vitreous silica. Silicon nitride may be present in the core material in quantities varying between .1% to 10% by weight. The silicon nitride doped silica glass can be formed in a boule by passing a mixture of gaseous compounds containing silicon and nitrogen through a induction coupled plasma discharge. The outside of the doped silica boule may be oxidized to reduce the nitrogen content.

Abstract: For avoiding the formation of sharp edges and lateral depressions in the conductors engraved from a conductive layer coated over an insulating surface, a thin film of a conductive material other than the conductive material of the layer is first coated over the said layer. After deposition of a mask of resist over said film, two successive engraving operations are made, the first one with a first acid solution inactive with respect to the material of the layer, the second one with a second acid solution inactive with respect to the material of the film.

Abstract: When a load is to be moved between preselected points along a path such that its weight aids movement in one direction and opposes it in the other (for example when scenery supported from a hoist is to be moved between "deads" in a theater or studio), the supported load is initially weighed and a signal representing its weight is stored. This signal is extracted from store when movement between positions is required and is applied to the hoist driving system to provide a torque balancing the load weight before a brake on the hoist driving system is removed. Thereafter the load is moved to the new position, the brake is reapplied and the stored weight signal is removed from the driving system.