Abstract:
A cryogenic current limiting fuse is disclosed together with a method of manufacturing a cryogenic current limiting fuse, the cryogenic current limiting fuse comprising a first cryogenic composite and a second cryogenic composite wherein at least one of the first and the second cryogenic composites has a non-linear and increasing resistivity with respect to at least one of temperature and current.
Abstract:
This network, intended for the transmission of information in optical form, wavelength multiplexed, comprises nodes (N1, N2) linked to each other by at least one optical fiber (F1), at least one wavelength being treated in each node. The system comprises unit (OF1, OF2, OS1, OS2) for superimposing on the information, for at least one wavelength per node, a surveillance signal whose frequency is outside the transmission band and, in each node, a surveillance circuit (CS1, CS2) for sampling at least one part of the surveillance signals, elaborating surveillance information in function of this part and sending this information to the processing units of the network. Application in optical telecommunications.
Abstract:
A method and apparatus for ultrasonically characterizing a polymer melt flowing in a predetermined direction between two opposed parallel surfaces spaced from one another to define a gap filled with polymer are disclosed. Ultrasonic pulses are propagated through the polymer melt between the two surfaces in a direction normal to the direction of flow for interaction with the polymer, the ultrasonic pulses having a duration such as to prevent successive echoes from overlapping with one another while reverberating between the two surfaces. The time delay between two echoes exiting from the polymer melt and generated from each pulse having interacted with the polymer is continuously monitored while simultaneously monitoring amplitude variations of the two echoes, to provide output signals representative of ultrasonic velocity and attenuation in the polymer melt. These output signals are processed to obtain data comprising ultrasonic velocity and attenuation values measured simultaneously as a function of time. The data is then processed to derive quantitative information relating to viscoelastic properties, structure or composition of the polymer, which can be used as input data in a closed-loop process control system.
Abstract:
An optical distributor which comprises M inputs (M>1) each receiving signals. M modules (MT1 to MT4) are connected to the M inputs and each simultaneously process N consecutive signals (N>1). N optical couplers (CO1 to CO4) each having M inputs and 1 output are connected to one of the N outputs. A control means (G) controls the modules and enables the distributor to scramble the signals so that a given signal reaches a given output of the distributor. Each module electronically demultiplexes the N consecutive signals, time rearranges the demultiplexed signals in accordance with the output of the distributor imposed by the control means for each of these signals, transposes the latter into optical form at N different wavelengths and switches each transposed signal to the desired output of the distributor. Such a device finds particular application in optical telecommunication system.
Abstract:
According to the present invention, an optical communications network is provided, which network comprises control means for controlling the network and a plurality of stations each having an information emitter and receiver. The stations are interconnected by optical signal transmission supports and the control means. According to the present invention, main delays of the stations are controllably modifiable, as desired, by the control means. Particular utility is found in the area of private communications networks, although other utilities are contemplated.
Abstract:
A multi-purpose component with integrated optics includes an optical light guide (12) formed on one face of a substrate (10) made of a double refracting material having neutral axes orientated so that one electromagnetic wave extending into the guide (12) is split up into two waves having polarizations perpendicular to each other and along the neutral axes. A power source (18) applies an electric filed perpendicular to the optical light guide (12) and uniformly along the guide (12). Two rectilinear polarizers (20, 22) with polarization directions (d1, d2) parallel to each other are each disposed at one extremity of the guide (12). The component also includes focussing means (24, 26, 28, 30). The component has particular utility for tuneable optical filtering and optical telecommunications.
Abstract:
An enclosure for electric device, in particular for surge arrester, comprises an outer, cylindrical envelope and an inner wall both made of electrically non conducting materials. One of the ends of the envelope is closed while the other is open. An electrode with a principal portion inside the enclosure extends through the envelope and projects outside the latter. Bolt anchors are used for fixing the enclosure on a mechanical support and for mounting a closure device on the open end of the envelope. The material constituting the inner wall is impervious to humidity and protects the envelope against breaking thereof by thermal shock caused for example by the production of an electric arc within the enclosure, while the material constituting the cylindrical envelope is a synthetic insulating material capable of withstanding a high mechanical tension. The envelope is molded on the inner wall and around the electrode and the bolt anchors, whereby the inner wall and the electrode are integrated to the envelope, and the bolt anchors are fixedly attached to the synthetic insulating material.
Abstract:
A method and an apparatus for ultrasonically characterizing polymer materials under simulated processing conditions are disclosed. According to the invention, a sample of a polymer is held in confinement between two axially aligned buffer rods having opposed parallel end surfaces spaced from one another to define a gap filled with the polymer sample, the polymer sample being acoustically coupled to the opposed end surfaces of the buffer rods. Ultrasonic waves are transmitted through one of the buffer rods in a direction toward the polymer sample for interaction therewith, and the polymer sample is subjected to controlled temperature or pressure variations over a predetermined period of time, the variation in temperature or pressure being effected via the buffer rods. Phase and amplitude variations of the ultrasonic waves having interacted with the polymer sample are continuously monitored as well as thickness variations of the polymer sample, over the predetermined period of time, to obtain data comprising phase, amplitude and thickness values measured as a function of temperature or pressure and time, which are then processed to derive characteristic parameters providing both a thermodynamic and viscoelastic characterization of the polymer. The present invention enables one to more adequately control the polymer processing conditions, with a view to optimizing the properties of a given polymer for a given application.
Abstract:
This ring network for wavelength-multiplexed information transmission. comprises two optical fibres (F1, F2) passing through nodes (N1 to N4) of the network and traversed in the opposite direction by informations, electronic add-drop multiplexers (ME1 to ME4) or ADM, each ADM supplying information to other ADM's, of the network at given wavelengths and optical add-drop multiplexers (M01 to M04) or OADM, each OADM adding to the fibres the informations from the associated ADM and extracting from said fibres the informations intended for said ADM. Application to optical telecommunications.
Abstract:
An add-drop multiplexer includes a first photodector (14), which receives informations in optical form, some of which are to be supplied to users addressees or recipients chosen from among N users addressees or recipients associated with the wavelengths L1, . . . , LN, whilst the other informations form an output flow at wavelength LO, a second photodetector (16) receiving in optical form informations to be inserted in said flow, a tunable source (18), which converts the signals from the first photodetector into optical signals of wavelengths chosen from among LO, L1 . . . LN under the control of control unit (20) and as a function of their destination, another source (22), which converts the signals from the second photodetector into optical signals of wavelength LO, a coupler (24) connecting the sources to N+1 filters (f0 . . . , f3) only respectively permitting the passage of LO . . . LN. Application to optical telecommunications.