Showing papers by "Alcatel-Lucent published in 1976"

Image method for efficiently simulating small‐room acoustics

Abstract: Image methods are commonly used for the analysis of the acoustic properties of enclosures. In this paper we discuss the theoretical and practical use of image techniques for simulating, on a digital computer, the impulse response between two points in a small rectangular room. The resulting impulse response, when convolved with any desired input signal, such as speech, simulates room reverberation of the input signal. This technique is useful in signal processing or psychoacoustic studies. The entire process is carried out on a digital computer so that a wide range of room parameters can be studied with accurate control over the experimental conditions. A fortran implementation of this model has been included.

Semiconductor liquid junction solar cells based on anodic sulphide films

Abstract: ALTHOUGH good performance has been achieved with established solid state junction solar cells, their cost remains well above that required for large scale terrestrial applications. New concepts1,2 for photovoltaic energy conversion have been introduced which involve the junction between a semiconductor and an electrolyte. These schemes may lead to new possibilities of considerably reduced materials and fabrication costs, providing that many technical problems could be solved. We report here metal–semiconductor–liquid electrolyte junctions in which an n-type sulphide semiconductor is anodically formed in situ on its metal and, under photoexcitation, drives a sulphide–polysulphide redox couple when connected to a suitable cathode. The original contribution in this area was made by Gerischer2 who demonstrated that the cell (single crystal n-CdS/Fe(CN)64−, Fe(CN)63−/SnO2) has an initial conversion efficiency > 5% (ref. 3) for sunlight to electric power, in spite of the 2.4-eV band gap of CdS, which implies that wavelengths > 550 nm (the greater part of the incident solar photons) are ineffective.

Resonance Raman scattering of light from a diatomic molecule

Abstract: Resonance Raman scattering from a homonuclear diatomic molecule is considered in detail. For convenience, the scattering may be classified into three excitation frequency regions—off‐resonance Raman scattering for incident energies well away from resonance with any allowed transitions, discrete resonance Raman scattering for excitation near or in resonance with discrete transitions, and continuum resonance Raman scattering for excitation resonant with continuum transitions, e.g., excitation above a dissociation limit or into a repulsive electronic state. It is shown that the many differences in scattering properties in these three excitation frequency regions may be accounted for by expressions derived from simple perturbation theory. Scattering experiments from molecular iodine are presented which test and verify the general scattering theories. Spectral measurements, time decay measurements, and pressure broadening measurements were made on I2 in the discrete resonance Raman scattering region; and spectral measurements at several excitation frequencies were made in the continuum resonance Raman scattering region. In each case calculations based on general theories correctly describe the experimental data.

Self-consistent electronic states for reconstructed Si vacancy models

Abstract: Vacancy states in Si are investigated using a recently developed self-consistent pseudopotential technique Three different structural models (ideal and two reconstructions) for a neutral vacancy are considered Vacancy states are found to exist in the Si thermal gap for each structure The character of these states is predominantly dangling-bond $p$-like localized on the four atoms surrounding the vacancy The ideal (unreconstructed) vacancy yields an electronic spectrum, which is unstable with respect to Jahn-Teller type distortions The two different reconstruction models considered yield Jahn-Teller stable situations

Electrical conductivity of tetrathiafulvalenium-tetracyanoquinodimethanide (TTF-TCNQ)

Abstract: New measurements of electrical conductivity along the $b$ axis of tetrathiafulvalenium-tetracyanoquinodimethanide (TTF-TCNQ) are combined with published results to provide a comprehensive summary including approximately 600 samples studied at 18 different laboratories The magnitudes of these measured conductivities do not necessitate the assumption of superconducting fluctuations or any other collective state in which the conductivity exceeds the limitations of single-particle scattering Since an adequate theory of the limitations of single-particle scattering for TTF-TCNQ does not exist at present, experiment alone does not rule out the possibility that collective effects may somewhat enhance or suppress the conductivity

Plasma oxidation of GaAs

Abstract: A new process for plasma oxidation of GaAs has been developed. Oxide films formed by this simple one‐step dry process have amorphous structure, with composition and thickness uniformity better than ±10% over areas ≲1 cm2. They have a gallium‐to‐arsenic ratio of nearly one. The electrical properties (I‐V, C‐V) of the films are such that this process may be useful in device fabrication.

Process and apparatus for the automatic inspection of patterns

Abstract: An object pattern to be inspected, such as a printed circuit board, and a reference pattern are scanned synchronously by respective cameras. The outputs of the cameras are compared and a fault signal is produced when the outputs do not coincide.

Method for using on line optic fiber loss monitor

Abstract: A method and means is disclosed for continuously monitoring an optical fiber's attenuation or loss as it is being formed, which includes: a light source, which may be the heated fiber itself during drawing operations or an external source; passing the light through the fiber being produced; positioning the end of the fiber in a holder adjacent to a light detector, for example a photodiode with or without passing the transmitted light through a filter; detecting the light transmitted by the fiber from the light source; converting the detected light into an electrical equivalent signal; amplifying the signal if necessary and recording or observing the changes in the signal to determine an objective measure of the optical fiber's attenuating characteristic.

Electronic franking machines

Abstract: An electronic franking machine, for example a postal franking machine, has a digital electronic input register, for storing a selected franking value fed in for use in the next franking operation of the machine, and a digital electronic total register which accumulates an indication of the total of the respective franking values used for such operations of the machine since this register was last reset. The machine also has an electrically adjustable printing device, for printing the selected franking value in each franking operation. The printing device is housed in a relatively massive stationary unit of the machine, and the electronic registers and associated circuitry are housed in a relatively light portable unit that is readily separable from the stationary unit to facilitate resetting by a remote authority.

Complexity of trie index construction

Abstract: Trie structures are a convenient way of indexing files in which keys are specified by values of attributes. Records correspond to leaves in the trie. Retrieval proceeds by following a path from the root to a leaf, the choice of edges being determined by attribute values. The size of a trie for a file depends on the order in which attributes are tested. We show that determining minimal size tries is an NP-complete problem for several variants of tries. For tries in which leaf chains are deleted we show that determining the trie for which average access time is minimal is also an NP-complete problem. Our results hold even for files in which attribute values are chosen from a binary or ternary alphabet.

Connection support for optical fibres

Abstract: The invention relates to optical fibre telecommunication engineering. A connection support for optical fibres has a stand one of whose faces has a grid of parallel rectilinear grooves each arranged for accomodating the ends of two optical fibres placed end to end with a view to connecting them together. The middle part of each groove in which is effected the transition between the fibres being formed by an insert in the stand in the shape of a comb and the stand is divided into two halves along a mid plane perpendicular to the grid of grooves.

Electrified channel with corresponding snap acting connector

Abstract: The electrified channel and corresponding snap acting connector of this invention provides for aligned conductors, preferably in the form of bus bars, secured to an insulation body carried by a channel. A mating or corresponding connector includes elastically mounted contacts carried in a housing which has a pair of spring elements on its exterior designed to retain the connector body with the contacts making contact with the conductors. When the contacts are in contact with the conductors they are spring pressed against them. A pair of external shoulder members, which are external to the channel when the connector is in place, can be moved inwardly to engage the spring clips thus permitting the connector to be removed from the channel with the spring pressure on the contacts assisting withdrawal of the connector from the channel.

Continuous process for manufacturing optical fibers

Abstract: A continuous optical fiber manufacturing process utilizes the method of chemical vapor deposition of the glass forming materials within an R.F. excited glow discharge. The rapid deposition rate within the discharge provides a sufficient stream of glass material for winding into a finished fiber on a synchronous take-up mechanism. Alternate embodiments include an oxygen air stream to remove dust particles from the fiber surface and an in-line fluorine stream to terminate surface bonding and reduce moisture attack on fiber surfaces.

Sampled signal processing device

Abstract: A device for performing the discrete Fourier transform on a sequence of an arbitrary number N of equally spaced signal samples. The device includes a digital filter having a transfer function: ##EQU1## Calculation coefficients sin 2πr/N and cos 2πr/N depend on the value of N and are calculated using the same digital filter during a starting-up operation. The values of the coefficients are stored and the device is "primed" to a particular value of N. If a different number of samples N' is subsequently needed, a new priming pass sets the device up.

Device for numerically generating a wave which is phase modulated and which is free from unwanted modulation products

Abstract: A digital device has an input for receiving successive samples of input d in digital form representative of phase values ζ. A sequence of the most recent input samples is stored in an input memory. A carrier phase source provides a signal representative of the phase θ of a carrier wave. A function memory stores values of a function k i · sin (ζ n-i +θ n ) and is addressed by first selection means which select a group corresponding to a coefficient k i and second selection means which select a member of the group corresponding to the value of (ζ + θ). During a calculation period the sum of all values of the function is calculated for i varying between l and a predetermined number r. Each such sum forms a sample of the output wave which is converted to analogue form and filtered to remove unwanted sampling components.

Digital image memory adapted to distribute image blanks

Abstract: The invention comes within the domain of synthetic images on a cathode scn and concerns a digital memory whose contents are cyclically read to constitute an image on the screen. The memory is divided into blocks each of which contains the data of a part of the image and which are cyclically controlled in such a way that within a line of the image, the blocks are read successively, whereas at the end of a line, a block is skipped. Thus, possible blanks in the image due to the breakdown of one of the blocks are distributed over the image and no longer erase a vertical column of the image.

Device for synchronizing a binary data train in relation to a reference train

Abstract: The invention comes within the field of digital transmission and concerns e synchronization of two bit trains in relation to the beginning of a frame. According to the invention, one of the trains crosses a memory of the FIFO type, whose writing speed corresponds to the frequency of that train and whose reading is controlled by a detector of the locking word in that frame and by a signal indicating the synchronization of the two trains. Application: digital PCM terminals comprising thirty telephone channels.

Pumping unit for television tubes

Abstract: A two stage pumping unit for evacuating tubes, and in particular televisionubes. A primary mechanical pump is air-cooled and is connected in series with an oil diffusion pump. The inlet for the stem of a tube to be evacuated has a sealing ring and between the sealing ring and the diffusion pump there is a baffle. Between the two pumps there is an oil condensation device and an oil trap. The trap, the condensation device, the oil diffusion pump, the baffle and the sealing ring are arranged for cooling by forced air.

Process and apparatus for the purification of fumes and gases and for the production of sulfuric acid

Abstract: A process for purifying combustion gases by removing the sulfur dioxide which they contain and for producing sulfuric acid, consisting in rinsing said gases by means of an aqueous solution capable of oxidizing said sulfur dioxide, said rinsing operation being effected in the presence of oxygen, characterized in that said aqueous rinsing solution comprises at least one element capable of combining with said sulfur dioxide to form within the aqueous solution and in the presence of sulfuric acid a sulfur type intermediate coordination complex capable of cooperating with oxygen and said element to produce at least one oxidizing compound (product) capable of oxidizing said sulfur dioxide at a rapid rate.

Device for forming channels

Abstract: Device for forming channels using detectors regularly spaced out on a cirar base comprising a chain constituted by an alternate sequence of identical adders and identical delay devices. The outputs of the detectors are sampled and applied through shift registers enabling them to be delayed more or less on the lateral inputs of the adders. The device comprises less elements than known channel forming devices. Application to sonars.

Microwave mode transducer

Abstract: The invention relates to a microwave mode transducer for changing between e rectangular TE 10 mode and the semi-circular or circular TE 01 mode. It comprises a microwave mode transducer comprising a semi-circular wave guide and a rectangular wave guide, the wave guides having substantially parallel longitudinal axes and being separated by a web which forms at least a part of the plane wall of the semi-circular guide and one of the smaller side walls of the rectangular guide, the guides being coupled by orifices in the web which orifices are substantially contiguous and are substantially as wide at their maximum width as the wall of the rectangular guide in which they are made.

Data collection system for use with a system of flexible working hours

Abstract: A terminal is connected by a transmission link to a computer coupler. The rminal has a reader for a worker's card or badge. A number written on the badge is sent to the computer for verification and is echoed back if OK. The return number is checked against the number sent and if still OK the badge number is displayed. Communication takes place over two telephone lines which may be taken from amongst pre-existing telephone lines in a work location. Other data such as time and total hours worked may be displayed by the terminal once a badge has been verified.