Showing papers by "Alcatel-Lucent published in 1977"

A unified approach to short-time Fourier analysis and synthesis

Abstract: Two distinct methods for synthesizing a signal from its short-time Fourier transform have previously been proposed. We call these methods the filter-bank summation (FBS) method and the overlap add (OLA) method. Each of these synthesis techniques has unique advantages and disadvantages in various applications due to the way in which the signal is reconstructed. In this paper we unify the ideas behind the two synthesis techniques and discuss the similarities and differences between these methods. In particular, we explicitly show the effects of modifications made to the short-time transform (both fixed and time-varying modifications are considered) on the resulting signal and discuss applications where each of the techniques would be most useful The interesting case of nonlinear modifications (possibly signal dependent) to the short-time Fourier transform is also discussed. Finally it is shown that a formal duality exists between the two synthesis methods based on the properties of the window used for obtaining the short-time Fourier transform.

Multimicrophone signal‐processing technique to remove room reverberation from speech signals

Abstract: It is well known that room reverberation can significantly impair one’s perception of sounds recorded by a microphone in that room. Acoustic recordings produced in untreated rooms are characterized by a hollow echolike quality resulting from not locating the microphone close to the source. In this paper we discuss a multimicrophone digital processing scheme for removing much of the degrading distortion. To accomplish this the individual microphone signals are divided into frequency bands whose corresponding outputs are cophased (delay differences are compensated) and added. Then the gain of each resulting band is set based on the cross correlation between corresponding microphone signals in that band. The reconstructed broadband speech is perceived with considerably reduced reverberation.

Electron states in α-quartz: A self-consistent pseudopotential calculation

Abstract: Self-consistent pseudopotentials are used to investigate the electronic structure of $\ensuremath{\alpha}$-quartz. We present calculations for the band structure, electronic density of states, optical response functions, pseudocharge densities, and x-ray emission spectra. We find excellent agreement between theory and experiment with respect to photoemission and uv absorption data. The chemical bonding present in $\ensuremath{\alpha}$-quartz as determined from pseudocharge density contour maps is consistent with other theoretical calculations. The theoretical x-ray emission spectra, as obtained from an orthogonalized-plane-wave scheme, are compared with experimental data. The calculated silicon and oxygen $K$ spectra agree very well with experiment; however, the $\mathrm{Si} {L}_{2,3}$ spectrum exhibits substantial disagreement with the data. An explanation is proposed based upon the formation of amorphous elemental Si in Si${\mathrm{O}}_{2}$ during electron irradiation.

Two‐dimensional cochlear fluid model: New results

Abstract: Many theories have been developed in past years which have attempted to model the function of the human cochlea. With the recent availability of the physical measurements of Rhode [J. Acoust. Soc. Am. 49, 1218 (1971)], these theories now appear to be inadequate. In this paper, improved numerical solutions have been found for the two‐dimensional cochlear model proposed by Lesser and Berkley [J. Fluid Mech. 51,497 (1970)], using the Green’s‐function method as first suggested by Cox and Lien [(1973) unpublished]. The Green’s‐function method is used to derive an integral equation which may then be solved numerically. This procedure has proven to be stable, accurate, and faster than several other numerical solution techniques that have been tried. With an appropriate selection of the assumed membrane dissipation, the results are seen to agree within a few decibels of the Mossbauer measurements of Rhode, including the sharp change in slope observed in his amplitude ratio measurements just above the best frequency. This plateau occurs at a level which is 58 dB lower in amplitude than the amplitude at the best frequency.

Solar Conversion Efficiency of Pressure Sintered Cadmium Selenide Liquid Junction Cells

Abstract: Pressure sintered electrodes of cadmium selenide subsequently doped with cadmium vapor have shown solar energy conversion efficiencies approaching /sup 3///sub 4/ of those of single crystal specimens in sunlight experiments. The cell CdSe/1F Na/sub 2/S-1F S-1F NaOH/C has operated at 5.1% conversion efficiency under AM2 conditions with polycrystalline electrodes. The relatively small sacrifice of efficiency from single crystal values of 7.5 +- 0.5% suggests the possibility of substantial cost advantage. The temperature and pressure conditions, cadmium doping procedure, material characterization, and the voltammetric behavior of the cell are discussed.

Scope and mechanism of carbohydrase action: stereospecific hydration of D-glucal catalyzed by α- and β-glucosidase

Abstract: A unique demonstration is presented of the capacity of glycosidases to create anomeric configuration de novo. Purifed Candida tropicalis alpha-glucosidase and sweet almond beta-glucosidase have been found to attack the same substrate, D-glucal, and to convert this unusual glycosyl substrate (which lacks alpha or beta anomeric configuration) to 2-deoxy-alpha-(or beta-) D-glucose, respectively. The stereospecificity of the hydration reaction catalyzed by each enzyme in D2O was revealed by the use of high-resolution (270 MHz) 1H magnetic resonance spectroscopy. The alpha-glucosidase caused a specific axial protonation (deuteration) of D-glucal at C-2, and formation of 2-deoxy-alpha-D-[2(a)-2H]glucose. The beta-glucosidase catalyzed an oppositely directed axial protonation at C-2 and formation of 2-deoxy-beta-D-[2(e)-2H]glucose. These results are not accounted for by the generally accepted mechanisms of carbohydrase action derived from studies with glycosidically linked substrates alone. D-Glucal apparently binds to the enzymes with essentially the same overall orientation as the D-glucosyl moiety of glycosidically linked substrates (with the double bond of D-glucal lying essentially in the plane of the similarly bound D-glucosyl group). Thus, the alpha-glucosidase evidently protonates D-glucal from above the double bond and alpha-D-glucosidic substrates from below the glycosidic oxygen; beta-glucosidase apparently protonates D-glucal from below the double bond and beta-D-glucosides from above the glycosidic oxygen. A detailed mechanism is proposed for the hydration of D-glucal by each enzyme, involving an incipient glycosyl carbonium ion and assuming the presence at the active site of two carboxyl groups arranged to account for catalysis of glycosylations from glycosidically linked substrates. That D-glucal serves as a glycosyl substrate for these enzymes strongly supports the concept that glycosidases and glycosyltransferases are catalysts of glycosylation (i.e., glycosylases), since this concept does not make the usual assumption that carbohydrases are restricted to acting on substrates having a glycosidic bond and either alph- or beta-anomeric configuration.

A systematic study of an isomorphous series of organic solid state conductors based on tetrathiafulvalene

Abstract: The solid state physical properties of an isomorphous series of TTF salts (TTF11 (SCN)6, TTF11 (SeCN)6, and TTF7I5) were examined. While there was no noticeable trend in the conductivity (as a function of temperature and anion), the effective Fermi energy (?F) and the magnetic susceptibility transition temperature exhibited a definite trend as a function of anion. There is a correlation between the above properties and subtle variations in solid state structure of each of the above salts.

Textures and NMR in superfluid /sup 3/He- (B)

Abstract: The nature of the spatial variation of the order parameter of the B phase of /sup 3/He is detailed. It is shown that in this phase there is a single vector component of the order parameter which undergoes spatial variation under normal circumstances and the detailed nature of its variation is calculated for cylindrical and parallel-plate geometries. The effect of these textures on nuclear magnetic resonance is discussed and it is shown that the textures should allow one to observe standing spin waves as well as the line-shape effects discussed in an earlier letter. (AIP)

Cochlear micromechanics—a mechanism for transforming mechanical to neural tuning within the cochlea

Abstract: A linear mathematical model is proposed which will account for the differences observed between mechanically measured data of Rhode (1971) for basilar membrane motion, and the responses of neural tuning curves (Kiang et al., 1974). We show that theoretical tuning curves may be derived from mechanical responses by forming the difference between the pressure across the basilar membrane and its displacement. Some ramifications of this proposal are discussed. We then propose a hypothetical physical model which could perform such a function.

Excited state lifetimes in cytochromes measured from Raman scattering data: evidence for iron-porphyrin interactions.

Abstract: Resonance Raman scattering excitation profile data have been obtained on ferrocytochromes c and b5 in the alpha absorption band region. We observe in cytochrome c that the shape of the excitation profile agrees with the absorption band shape, while in cytochrome b5 it does not. In addition, we observe in cytochrome b5 a linewidth substantially larger than that in cytochrome c. From our data we conclude that the excited state lifetime in cytochrome c is longer than that in cytochrome b5 and that in cytochrome b5 the relaxation of the pi-pi* excited state configuration of the porphyrin ring is different in the x direction than in the y direction. Possible origins of these effects due to coupling to the d-d transitions of the iron atom are discussed.

A new proof of the linearity of the Boyer-Moore string searching algorithm

Abstract: The Boyer-Moore algorithm searches for all occurrences of a specified string, the pattern, in another string, the text. We study the combinatorial structure of periodic strings and use these results to derive a new proof of the linearity of the Boyer-Moore algorithm in the worst case. Our proof reduces the previously best known bound of $7n$ to $4n$, where n is the length of the text.

Plasma oxidation of aluminum film on GaAs—A study by Auger spectroscopy and transmission electron microscopy

Abstract: Plasma oxidation of thin polycrystalline aluminum films (∼100 A) on GaAs has shown that oxidation of aluminum proceeds by an initial rapid grain‐boundary oxidation of the aluminum followed by a slower oxidation towards the centers of the individual grains. Continued oxidation results in the growth of Ga‐As‐ oxide layers on both sides of the Al‐oxide film indicating that the oxidation of GaAs proceeds by an electric‐field‐assisted in‐migration of oxygen through the Al‐oxide layer toward the interface and the out‐migration of Ga and As toward the surface. This oxidation process can be used to form an amorphous film of Al‐oxide on GaAs. By using the Al‐oxide film as a preferential filter for the migration of Ga and As, an amorphous Ga‐As‐oxide film with a Ga/As concentration ratio of unity all the way to the GaAs substrate can also be achieved.

Analysis of plasma‐grown GaAs oxide films

Abstract: Thin oxide films of GaAs grown in a plasma have been analyzed using Rutherford backscattering and ion‐induced x rays. Films whose thicknesses are greater than 1000 A have a composition of O:Ga:As of 3:1.07:1. For the thinner films, the oxygen content is less indicating an incomplete oxidation.

Evaluation of a word recognition system using syntax analysis

Abstract: A speech recognition system has been implemented which accepts reasonably natural English sentences spoken as isolated words. The major components of the system are a speaker dependent word recognizer and a syntax analyzer. The set of sentences selected for investigation is intended for use as requests in an automated flight information and reservation system. Results are presented of evaluations for speakers using their own stored reference patterns, the reference patterns of other speakers and reference patterns averaged over several speakers. For speakers using their own reference pattern the median word recognition error rate fell from 11.7% to 0.4% with the use of syntax analysis.

Conference circuit using PCM techniques

Abstract: Conference circuit which uses a read/write memory divided into groups of memory lines, with each group corresponding to a conference. Each line is assigned to store data from a single subscriber and to store the code words coming from that subscriber. The memory stores non-linear subscribers' codes. The codes are expanded and the codes of other subscribers in the same conference are added and compressed for transmission and decoding at any other exchange of other conference members. The conference circuit may be inserted in one position of a group of junction circuits or may be placed in a subscriber line concentrator.

Self-correcting equalization system

Abstract: The invention consists in an equalization system with two sections, one at each end of a transmission channel. The section at the transmission end adds control signals to information signals to be transmitted over the line. The section at the reception end generates control signals identical to those added at the transmission end and in phase with the control signals received over the transmission channel, which are separated from the received information signals by means of a first transversal filter with controllable weighting coefficients, the reciprocal transfer function of the transmission channel being synthesized from the locally generated and the received control signals by means of a second transversal filter with controllable weighting coefficients, equalization being achieved by means of a third transversal filter with the same design and same weighting coefficients as the second transversal filter. The invention is applicable to the transmission of data over telephone lines.

Controlled barrier height InP Schottky diodes prepared by sulfur diffusion

Abstract: Schottky barrier diodes with adjusted effective barrier heights have been obtained by diffusing sulfur into n‐type InP to form a shallow highly doped layer at the surface. The necessary geometry and doping conditions for achieving lowered barrier heights are described and the experimental procedure for the diffusion of sulfur in InP is outlined. Data are presented on several devices having different surface layer impurity concentrations and effective barrier heights.

Physical and electrical properties of plasma-grown oxide on Ga 0.64Al0.36As

Abstract: Auger, Rutherford backscattering, and x‐ray‐diffraction measurements show that plasma‐grown oxide films on Ga0.64Al0.36As are amorphous, uniform in composition with depth, and possess very sharp oxide‐semiconductor interfaces. The electrical properties (I‐V, C‐V) of these films are such that they may be used for surface passivation of optoelectronic devices and as dielectric layers in electronic device fabrication.

Empirical potential energy surface for the Hg+I2 reaction

Abstract: The general features of the ground state adiabatic potential energy hypersurface for the Hg+I2 system have been deduced using results of recent molecular beam scattering experiments, spectroscopic and structural data, and electronic state correlation diagrams. The key element of the potential energy surface (p.e.s.) is a deep attractive ’’basin,’’ implied from the reactive scattering data which provided evidence for the existence of a long‐lived intermediate complex, believed to be IHgI. This empirical p.e.s. is characterized by the following features: (a) a shallow well in the entrance valley corresponding to the weakly bound (by ∼0.06 eV) van der Waals adduct Hg⋅I2; (b) a subsequent barrier of ∼0.7 eV in the entrance valley due to avoided crossings of diabatic potential curves, followed by a ’’falloff’’ leading to insertion of the Hg(1S0) into the I2(1Σg+) molecule; (c) a deep potential well (−1.45 eV) corresponding to the stable IHgI complex, taken to be gaseous mercuric iodide in its ground electronic...

Device for the digital multiplexing of quasi-synchronous trains

Abstract: A device for multiplexing n quasi-synchronous digital trains into one digital train at least n times faster, with a rate of Fs, comprises n channel elements for synchronizing together the quasi-synchronous trains by the addition of extra bits called "justification bits", and a multiplexing element for delivery, from the synchronized trains, the multiplex train (T) (rapid) formed by successive frames. According to the invention, the multiplexing element supplies to each channel element a signal SJ constituted by a pulse Fs/n at each of the places except for the last place, provided in the train synchronized at the frame frequency of the multiplex train and by a pulse covering this latter location and maintained up to the beginning of the following frame and each channel element comprises means for ensuring, on differentiated edges of the signal SJ the insertion of justification indications, of value 1 or 0 according to whether there is or is not a request for justification in the synchronized train.

Control unit for a time-division telecommunications exchange

Abstract: In an existing time division exchange system the known switching network and connection units are retained, but the control of these units is taken over by a pair of new control units which replace a collection of previous units such as multi-registers, markers, translators, call charging devices etc. The new control units each comprise a multi-register portion and a dialogue portion with the multi-register portion governing the setting up and the clearing down of traffic while the dialogue portion performs most of the communication between the multi-register portion and the rest of the exchange equipment. The control units are microprogrammed machines under the control of a "macroprogram" assembled using the conventional computer techniques. The control units are connected to a data processing center via a monitoring unit.

Connector for optical fibres

Abstract: The ends of two optical fibres to be joined are housed in sleeves which include assembly means for uniting the sleeves front face to front face. A point-line-plane positioning arrangement ensures that each time the connector is re-closed its sleeves take up the same axial disposition with respect to each other. Structure is provided to adjust the axial position of the fibres so that they look into each other at the said same axial disposition. Once set up the connection can be repeatedly opened and closed with reproducible transmission characteristics.

Method of compensation of intermodulation noise and devices for the implementing thereof

Abstract: The present invention relates to amplifier chains such as are found, for example, in carrier analog transmission by cable with repeaters. Intermodulation noise is reduced by opposing an intermodulation noise generated by a compensation source from the signal available at the chain output to the intermodulation noise generated by the chain. It applies in particular to cable transmission links with repeaters to improve the signal-to-noise ratio thereof.