Abstract: The sensor is constituted by a magnetic core with pole pieces and by an electric coil wound on the body of said core. With said coil there are associated a sinusoidal current generator and impedance measurement means. A processor determines the thickness from the measured value of said impedance.

Abstract: The detector comprises an electro-optical section for the signal analysis, a transmission fibre-optic, a fibre-optic coupling of high immunity to environmental noise, and a fibre-optic sensor terminating in a reflecting element. It can be provided in either homodyne or heterodyne version (phase or frequency modulation). This latter version has the advantage of detecting phase modulations exceeding 2.pi. radians. Both the versions have the advantage of enabling measurements to be made which are not influenced by environmental disturbances affecting the transmission fibre-optic.

Abstract: A method for restarting the longitudinal welding seam when producing thin-walled tubes from a metal tape comprises the steps of starting welding with the tape in motion and the welding current amperage being gradually raised from zero to the steady state values, a steady state step in which the longitudinal welding seam is continuously produced and the welding current amperage is at its steady state value, a third step in which the welding is stopped and the welding current amperage is gradually decreased from its steady state value to nearly zero, and a restarting stage in which the welding seam is overcast partially behind the point at which it had been stopped and the welding current amperage is gradually raised from nearly zero to the steady state value once again. An apparatus for performing the method is also disclosed.

Abstract: This invention provides a system for the flexible composition of laser beams, in which several beams of substantially annular cross-section can be fed to a composition unit which combines them by causing them to propagate one within the other in such a manner that the cross-section of the composite beam is constituted by the cross-sections of the component beams.

Abstract: A high-sensitivity device for measuring the mutual level differentials among a certain number of reading locations, the device comprising a plurality of containers, one for each reading location, mutually connected at the bottom ends by a piping opening into a balancing tank which holds a liquid mass. Each container is equipped in its interior with a float which is held spaced apart from the container walls by flexible retaining members, a level-differential sensitive transducer being mounted in correspondence with the walls. The apparatus further comprises a device for measuring the signals delivered by the transducers.

Abstract: An apparatus for measuring the degree of sensitization of metal articles comprises an electrochemical cell in which the potential of a test-piece of the article with respect to a reference electrode is made to vary linearly with time by feeding currents of suitable intensity from the passivation field to the activation field by means of the counter-electrode; a pair of electrodes moves along the test-piece surface with the respective electrode ends kept equidistant and disposed along an axis substantially perpendicular to the test-piece surface, one of them being in contact with said surface; by measuring the potential difference of this pair of electrodes as a function of their position, the local degree of sensitization of the test-piece is obtained.

Abstract: This invention relates to an instrumented unit for measuring temperatures and heat flux in evaporative walls of steam generators composed of a series of parallel tubes comprising a temperature measurement device formed from a plurality of sensors extending fluid-tight from a support member and inserted non-forcibly into complementary curved seats of constant radius provided in the cross-section of one of the tubes, the support member being fixed in straddling relationship and comprising, for the sensors, seats which are fluid-tight against the tube.

Abstract: An apparatus for detecting the displacements of points of structures which are excited either by artificially or naturally produced forces comprises, in combination:coherent-light vibration-sensing means composed of at least one group of two laser-beam interferometers focused at a common target point of a structure;angle-sensing means rigidly connected to the interferometers of at least either group, andmeans for processing the interferometric data coming from said vibration-sensing means and the angular data coming from said angle-sensing means.

Abstract: A planar oscillator (9, 109) having a dielectric cavity (25, 125) and which is operative at microwave frequencies, said oscillator consisting of a dielectric material base (10, 110) one surface of which has, superposed thereto, a continuous layer (11,111) of a conductive material which coats portions of said face; the remaining portions (10A, 10B, 110A', 110A", 110B) of the surface have, superposed thereto, strips of a conductive material (12,13,14,112,113,114) which are separate from each other and are electrically connected to an active element (19, 119), a dielectric cavity (25,125) adhering to the opposite surface of the dielectric material base (10,110), the layer of conductive material (11,111) providing a grounding plane and the strips of conductive material (12,13,14,112,113,114) providing transmission and output lines for the oscillator.

Abstract: A device capable of measuring the position of the level surface of a molten metal bath by exploiting a microwave signal emerging from a waveguide which impinges perpendicularly onto the molten metal so as to originate a standing wave, the position of which is determined by the position of the level surface. The parameters of the standing wave are detected so as to obtain an indication as to the level.

Abstract: The invention relates to an inerferometer based on the exploitation of an optical fibre through which both the phase signal which is of interest for the measurements concerned and a reference signal are simultaneously forwarded in order that in the differential measurement the noise introduced by the optical fibre for both thermal and mechanical reasons is ruled out.

Abstract: The transmission structure comprises at least two parallel conducting bands placed on an support of semi-insulating semiconductor material. Said conducting bands are electrically interconnected by concentrated capacities, which are spaced apart at predetermined distances, which are less than the wavelength of the signal to be transmitted.

Abstract: This invention relates to a method for constructing multispectral infrared detectors formed by three HgCdTe photovoltaic elements disposed in the form of a sandwich. According to the invention, each photovoltaic element is constructed by preparing a suitable slice of HgCdTe, by polishing the faces of said slice, by chemically attacking the slice, by heating the slice in the presence of mercury inside a test tube within a furnace having a suitable temperature profile, by constructing the ground contact by catalytic deposition of gold, by cementing the slice onto a support, by depositing a layer of photoresist on the slice, by masking the photoresist with the exception of a small exposure region, by eliminating the photoresist in the exposure region, by grafting the slice and by depositing the upper contact and an entire flecting layer. The individual elements are finally assembled and electrically connected to output terminals.