Showing papers by "Alcatel-Lucent published in 1979"

Invertibility of a room impulse response

Abstract: When a conversation takes place inside a room, the acoustic speech signal is distorted by wall reflections. The room’s effect on this signal can be characterized by a room impulse response. If the impulse response happens to be minimum phase, it can easily be inverted. Synthetic room impulse responses were generated using a point image method to solve for wall reflections. A Nyquist plot was used to determine whether a given impulse response was minimum phase. Certain synthetic room impulse responses were found to be minimum phase when the initial delay was removed. A minimum phase inverse filter was successfully used to remove the effect of a room impulse response on a speech signal.

Speaker-independent recognition of isolated words using clustering techniques

Abstract: A speaker-independent isolated word recognition system is described which is based on the use of multiple templates for each word in the vocabulary. The word templates are obtained from a statistical clustering analysis of a large database consisting of 100 replications of each word (i.e., once by each of 100 talkers). The recognition system, which accepts telephone quality speech input, is based on an LPC analysis of the unknown word, dynamic time warping of each reference template to the unknown word (using the Itakura LPC distance measure), and the application of a K-nearest neighbor (KNN) decision rule. Results for several test sets of data are presented. They show error rates that are comparable to, or better than, those obtained with speaker-trained isolated word recognition systems.

A bound for the least prime ideal in the Chebotarev Density Theorem

Abstract: as x --, oc. In [7] two versions of the Chebotarev density theorem were proved, one unconditional and the other on the assumption of the Generalized Riemann Hypothesis (GRH), each of which expressed ~Zc(X ) as the sum of the main term ICI IC]_lGt Li(x) and an error term which is an effectively computable function of x, i-~-' and the associated field constants n K = [ K : Q ], h i = [L :Q] and dK,dz, (the absolute values of the discriminants of the two fields). Assuming the truth of the GRH for ~L(s), that paper also proved the existence of an effectively computable constant b (independent of K and L) such that for any conjugacy class C, there exists a prime

Effects of Cations on the Performance of the Photoanode in the n-GaAs |K2Se-K2Se2-KOH|C Semiconductor Liquid Junction Solar Cell

Abstract: Cations adsorbed onto the surface of an n-GaAs photoanode have been found to increase the fill factor and open-circuit voltage of the cell, and a conversion efficiency of 12% (under AM1 solar radiation) has been attained by chemisorbing Ru(III) onto the photoanode. The action of the Ru ions on the surface density of the photoanode is explained in detail. 19 references.

Speaker independent recognition of isolated words using clustering techniques

Abstract: A speaker independent, isolated word recognition system is proposed which is based on the use of multiple templates for each word in the vocabulary. The word templates are obtained from a statistical clustering analysis of a large data base consisting of 100 replications of each word (i.e. once by each of 100 talkers). The recognition system, which uses telephone recordings, is based on an LPC analysis of the unknown word, dynamic time warping of each reference template to the unknown word (using the Itakura LPC distance measure), and the application of a K-nearest neighbor (KNN) decision rule to lower the probability of error. Results are presented on two test sets of data which show error rates that are comparable to, or better than, those obtained with speaker trained, isolated word recognition systems.

13C nuclear magnetic resonance studies of anaerobic glycolysis in suspensions of yeast cells

Abstract: Anaerobic glycolysis in Saccharomyces cerevisiae has been studied by 13C NMR at 90.5 MHz. [1-13c]Glucose and [6-13C]glucose were fed to suspensions of yeast cells. Time courses for concentration changes of the starting material, of courses for concentration changes of the starting material, of the intermediate fructose 1,6-bisphosphate (Fru-P2), and of the end products, ethanol and glycerol, have been followed with 1-min time resolution. The glucose uptake was well fitted by a Michaelis-Menten model, assuming competition of alpha- and beta-glucose for the same site. The Km for the uptake was found to be 10 mM for beta-glucose and 5 mM for alpha-glucose. The concentration of Fru-P2 showed an initial oscillation before it reached a co,stant level. The 13C label, introduced only as [-13C]- or [6-13C]glucose, was observed in Fru-P2 in both the C1 and C6 positions, simultaneously. From the relative intensities of the C1 Fru-P2 and C6 Fru-P2 peaks in the presence of [1-13C]- and [6-13C]glucose, in vivo kinetic information was obtained about the aldolase-triosephosphate isomerase triangle. We found that under the conditions of these experiments the ratios of backward to forward velocities through aldolase and triosephosphate isomerase were 0.9 +/- 0.1 and 0.8 +/- 1, respectively, indicating they were close to equilibrium.

Cochlear macromechanics: Time domain solutions

Abstract: In this paper we report on a new method of solving a previous derived, two‐dimensional model, integral equation for basilar membrane (BM) motion. The method uses a recursive algorithm for the solution of an initial‐value problem in the time domain, combined with a fast Fourier transform (FFT) convolution in the space domain at each time step. Thus, the method capitalizes on the high speed and accuracy of the FFT yet allows the BM to have nonlinear mechanical properties. Using the new method we compute (linear) solutions for various choices of model parameters and compare the results to the experimental measurements of Rhode. [J. Acoust. Soc. Am. 49, 1218–1231 (1971)]. We also demonstrate the effect of including longitudinal stiffness along the BM and conclude that it is useful in matching the high‐frequency slope as measured by Rhode.

Interactive clustering techniques for selecting speaker-independent reference templates for isolated word recognition

Abstract: It is demonstrated that clustering can be a powerful tool for selecting reference templates for speaker-independent word recognition. We describe a set of clustering techniques specifically designed for this purpose. These interactive procedures identify coarse structure, fine structure, overlap of, and outliers from clusters. The techniques have been applied to a large speech data base consisting of four repetitions of a 39 word vocabulary (the letters of the alphabet, the digits, and three auxiliary commands) spoken by 50 male and 50 female speakers. The results of the cluster analysis show that the data are highly structured containing large prominent clusters. Some statistics of the analysis and their significance are presented.

The liquid‐crystal alignment properties of photolithographic gratings

Abstract: The liquid‐crystal alignment properties of gratings with a 1–10‐μm period are described. Experiments are presented to compare the roles of interfacial interactions and surface topography in determining alignment. It is shown that grooves are neither necessary nor always sufficient to produce alignment. Interfacial forces can give rise to strongly pinned alignment, governed by various biases applied during the first appearance of long‐range order at the interface.

Protein-heme interaction in hemoglobin: evidence from Raman difference spectroscopy

Abstract: Raman difference spectroscopy measurements on native and chemically modified human deoxyhemoglobins stabilized in either the R or the T quaternary structure revealed frequency differences in the oxidation state marker lines. The differences indicate that the R structure has an effective increase in the electron density of the antibonding pi* orbitals of the porphyrin rings. This increase is explained by a charge transfer interaction between donor orbitals and the pi* orbitals of the porphyrins. The relative amount of charge transferred, which is inferred from the Raman difference measurements, correlates with some but not all factors that influence the energetics of the quaternary structure equilibrium. In addition, the free energy of cooperativity for a variety of ligated proteins follows the same order as that of the degree of charge depletion of the pi* orbitals upon ligation as determined from the frequency of a Raman mode. The proposed electronic interaction between the protein and heme could result in energies large enough to provide a significant contribution to the energetics of hemoglobin cooperativity.

Studies of the Si‐SiO2 interface by MeV ion channeling

Abstract: By performing backscattering‐channeling measurements in two different geometries on thin Si crystals thermally oxidized at 800 °C, we have obtained upper and lower limits of the number of reconstructed Si layers at the Si‐SiO2 interface. The results indicate an abrupt Si‐SiO2 interface with one to two monolayers of Si reconstruction.

Decimator apparatus for decreasing the word rate of a digital signal of the type employed in digital telephone systems

Abstract: There is disclosed a decimator structure which incorporates the cascade of an FIR filter with a low pass recursive filter. The input to the decimator is obtained from a high rate analog to digital converter. The output from the decimator is a low rate digital signal having an increased word length. The decimator serves to reduce the word rate and increase the word length of the output digital signal of the analog to digital converter. In this manner, the low rate digital signal at the output of the decimator can be easily accommodated by the telephone system. The decimator described does not require conventional hardware multipliers and hence, affords efficient and economical circuit components which can be implemented by conventional integrated circuit techniques. A register further reduces the pulse rate for transmission.

Adenine nucleotide storage and secretion in platelets as studied by 31P nuclear magnetic resonance.

Abstract: Suspensions of human and pig blood platelets have been studied by 31P NMR at 145.7 MHz and by chemical and radiochemical determination of nucleotide levels. In both types of platelets the cytoplasmic nucleotide pool, which was prelabeled by incubation with [14C]adenine, was selectively reduced by addition of H2O2/NaN3 or 2-deoxyglucose/antimycin A. After the reduction of cytoplasmic ATP in human platelets, the 31P NMR spectra showed an almost complete loss of the nucleoside di- and triphosphate resonances at temperatures examined (4--50 degrees C), indicating that only the cytoplasmic nucleotides had been observed, with no detectable contributions from the granular ATP, ADP, and pyrophosphate. Slow tumbling of the granular nucleotides, possibly due to aggregation, is the probable explanation of their undetectability at 145.7 MHz. Similar experiments showed that in pig platelets, granular ATP and ADP were not detected by 31P NMR at 4 degrees C but were observed at higher temperatures, indicating that aggregation may be occurring at the lower temperatures. Upon thrombin stimulation of human platelets, the NMR spectra and the chemical and radioactivity analyses showed that the granular adenylates and pyrophosphate were secreted, and that cytoplasmic ATP levels were appreciably reduced.

Multiplex space switch

Abstract: The space switch has an inlet series to parallel converter (1) arranged to take sequential data from the i-th time slot of each of a plurality of synchronized inlet multiplexes and apply them simultaneously to a parallel connection (11) within one time slot period. These time slots are written into one of two signal stores (2 and 3), e.g. sequentially. A control store (4) controls the order in which data is read from the signal store and re-assembled into outlet multiplexes by a parallel to series converter (5), thereby performing space switching between the stored time slots. The signal stores alternate between reading and writing, and each has a capacity equal to the product of the number (p) of inlet multiplexes (E1, . . . Ep) multiplied by a submultiple of the number of time slots to a frame. When the submultiple is greater than 1 there is a possibility of limited time switching within a sector of successive time slots, the number of time slots in each sector being equal to the submultiple.

7.3% Efficient thin-film, polycrystalline n-GaAs semiconductor liquid junction solar cell [14]

Abstract: By elimination of grain boundary effects, it is possible to approach single-crystal efficiency provided that the mobility remains high and an optimal, uniform doping level is maintained throughout the grains. Such a situation is approached in thin-film, chemically vapor deposited n-GaAs, following exposure to a Ru(III) solution. The anode used was n-GaAs/n/sup +/-GaAs/W/graphite. A 24-..mu..m thick layer of n-GaAs was deposited on a 2 to 3-..mu..m tungsten-on-POCO graphite substrate by the reaction by hydrogen chloride, gallium, and arsine at 775/sup 0/C. The grains were of 1 to 20 ..mu..m diameter, with an average linear dimension of 9 ..mu..m. The measurements were done under 96.4 mW/cm/sup 2/ incident sunlight. The insolation was determined by an Eppley Model PSP radiometer, which measures the direct and scattered insolation from the entire sky. This demonstrates that grain-boundary diffusion of a strongly bound impurity can reduce the grain-boundary-related losses in solar cells made with thin-film polycrystalline semiconductors. This work suggests that it is possible to approach more closely single-crystal efficiencies in thin-film polycrystalline solar cells than originally thought. 2 figures. (DP)

On computing artin l-functions in the critical strip

Abstract: This paper gives a method for computing values of certain nonabelian Artin L-functions in the complex plane. These Artin L-functions are attached to irreducible characters of degree 2 of Galois groups of certain normal extensions K of Q. These fields K are the ones for which G = Gal(K/Q) has an abelian subgroup A of index 2, whose fixed fileld Q(,fd) is complex, and such that there is a a G G A for which aaa 1 = a-1 for all a E A. The key property proved here is that these particular Artin L-functions are Hecke (abelian) L-functions attached to ring class characters of the imaginary quadratic field Q(-d) and, therefore, can be expressed as linear combinations of Epstein zeta functions of positive definite binary quadratic forms. Such Epstein zeta functions have rapidly convergent expansions in terms of incomplete gamma functions. In the special case K = Q(\/, a1/3), where a > 0 is cube-free, the Artin L-function attached to the unique irreducible character of degree 2 of Gal(K/Q) -S3 is the quotient of the Dedekind zeta function of the pure cubic field L = Q(a1/3) by the Riemann zeta function. For functions of this latter form, representations as linear combinations of Epstein zeta functions were worked out by Dedekind in 1879. For a = 2, 3, 6 and 12, such representations are used to show that all of the zeroes p = a + it of these L-functions with 0 < a < 1 and Iti < 15 are simple and lie on the critical line a = 1/2. These methods currently cannot be used to compute values of L-functions with Im(s) much larger than 15, but approaches to overcome these deficiencies are discussed in the final section.

Protein influence on the heme in cytochrome c: evidence from Raman difference spectroscopy

Abstract: Raman difference spectra have been obtained for the cytochromes c of a number of species by simultaneous data acquisition from two samples. Frequency differences as small as 0.1 cm-1 can be measured reproducibly by the technique we have developed. In comparisons between cytochromes c isolated from two different species, the frequency differences in the heme vibrational modes range from 0 to 6 cm-1. The vibrational frequencies of the heme are sensitive to the electronic charge density on the porphyrin macrocycle. The frequency differences are interpreted in terms of the influence of the heme-packed aromatic and highly electronegative amino acid side chains on the pi* charge density and distribution on the heme. Such a control of the electronic properties of the heme by the protein may be important for the function of cytochrome c.

Multidielectrics for GaAs MIS devices using composition‐graded AlxGa1−xAs and oxidized AlAs

Abstract: Metal‐insulator‐semiconductor (MIS) structures were prepared by dry thermal oxidation of an AlAs layer that had been grown on a composition‐graded AlxGa1−xAs layer on GaAs. The epitaxial layers were grown by molecular beam epitaxy. Capacitance‐voltage (C‐V) measurements of these MIS structures demonstrated the achievement of inversion behavior with essentially no hysteresis and flatband voltages ranging from 0 to 0.1 V, which correspond to a fixed interface charge density of less than 2×1010 cm−2. It was also found that the stress developed between the oxide film and the epilayer was reduced in these MIS structures.

Short-time Fourier analysis tecniques for FIR system identification and power spectrum estimation

Abstract: A wide variety of methods have been proposed for system modeling and identification. To date, the most successful of these methods have been time domain procedures such as least squares analysis, or linear prediction (ARMA models). Although spectral techniques have been proposed for spectral estimation and system identification, the resulting spectral and system estimates have always been strongly affected by the analysis window (biased estimates), thereby reducing the potential applications of this class of techniques. In this paper we propose a novel short-time Fourier transform analysis technique in which the influences of the window on a spectral estimate can essentially be removed entirely (an unbiased estimator) by linearly combining biased estimates. As a result, section (FFT) lengths for analysis can be made as small as possible, thereby increasing the speed of the algorithm without sacrificing accuracy. The proposed algorithm has the important property that as the number of samples used in the estimate increases, the solution quickly approaches the least squares (theoretically optimum) solution. The method also uses a fixed Fourier transform length independent of the amount of data being analyzed, allowing the estimate to be recursively updated as more data is made available. The method assumes that the system is a finite impulse response (FIR) system.

Application of selective chemical reaction concept for controlling the properties of oxides on GaAs

Abstract: We demonstrate how GaAs can be selectively oxidized in a plasma to control the physical and chemical properties of the oxides. Electrical measurements indicate that charged traps can be removed.

Fixed optical attenuator for light rays guided by optical fibres

Abstract: The present invention relates to the optical fibre technology and more particularly to fixed optical attenuators for insertion in an optical fibre transmission path. The optical attenuator includes an attenuator element 1, two lenses 2, 3 which are aligned with each other and separated by the attenuator element 1 and two optical fibre connections disposed on either side of the assembly formed by the lenses 2, 3 and the attenuator element 1. It may be used as a level adaptor between a source of light rays and a device which is connected to it by an optical fibre or in test, calibration or measuring instruments for optical fibre systems.

Digital generator for producing a sinewave

Abstract: A digital sinewave generator can be used in digital equipment, e.g. instead of a local oscillator for modulation/demodulation of signals. If there is no simple relationship between sampling rate and the frequency of the sinewave, successive sample values must be calculated since storage of these values would be prohibitive. For a sinewave Re jk φ sampled at successive instants k=0, 1, 2, . . . etc. separated by a phase angle φ, quadrature components A k +jB k =Re jk φ can be calculated using the algorithm: A.sub.k+1 =cosφA.sub.k -sinφB.sub.k B.sub.k+1 =sinφA.sub.k +cosφB.sub.k. Unfortunately it is impossible for cos 2 φ+sin 2 φ to be exactly equal to unity if calculations are performed with finite precision using an even number base, which as the effect of causing the modulus of a sinewave generated by this algorithm to tend exponentially to 0 to ∞. The present invention overcomes this by using the above algorithm to obtain approximations A k+1 ' and B k+1 ' to the desired result at terminals (9 and 10) and then multiplying (22,23) the approximations A k+1 ' and B k+1 ' by a correction factor ( 1-1/2e) to obtain better approximations A k+1 and B k+1 which are stable about the desired amplitude R. ##EQU1## Such a generator can be used as a local oscillator in a modem for example.

Circuit for recovering the carrier of an amplitude modulated synchronous digital signal

Abstract: The present invention comes within the field of synchronous digital transmission. It relates to the recovering the carrier (which may be suppressed carrier) of an amplitude modulated synchronous digital signal. It provides a circuit which includes an oscillator (41) of adjustable frequency and phase to generate a local carrier, a demodulation circuit whose input(s) receives the local carrier (possibly phase shifted by ±Ψ (42,44,46,47) and the amplitude modulated synchronous digital signal e(t) and control means (48,49) which control the phase and the frequency of the oscillator from the signals delivered by the demodulation circuit and which comprise at least one sign coincidence autocorrelator. It advantageously applies to demodulating amplitude modulated single side band bipolar coded synchronous digital signals.

Connector for printed circuit board

Abstract: A connector comprises a base portion provided with contacts, a movable block and a device for displacing the movable blocks perpendicularly to the base portion, operation of the displacing device causing the movable block to take up a raised position in which it is possible to insert above the base portion a printed circuit board bearing contacts on one side facing the base portion, and a lowered position in which the printed circuit board is pressed against the said contacts provided on the base portion.

Fabrication and barrier diagnostics of superconductive tunnel junctions on Nb-Sn and V-Si

Abstract: The procedures found to lead to good tunnel junctions on the Al5 superconductor Nb-Sn are described. The use of an acetic acid atmosphere and/or oxidized Si layer barriers is shown to be particularly effective. The role of excess Sn in good oxide barrier formatiom on bare Nb-Sn is discussed. These results are related to earlier work using oxidized Si barriers on V 3 Si.

Time-division switching network and means of mitigating the effect of fault conditions

Abstract: A switching network is disclosed having a time-division or space-division multiplex incoming stage and outgoing stage in which a terminal unit of the incoming stage and a terminal unit of the outgoing stage form a terminal module (ME1, ME2 . . . MEn) which can handle n multiplex links (LE1, . . . LEn). The terminal modules are formed into groups in which the traffic of a faulty module is distributed among the other terminal modules of the group and forwarded over an auxiliary incoming line (L9, L10, L11, L12) of each terminal module by an input switch (5, 6, 7, 8) associated with each terminal module. An output switch (9, 10, 11, 12) associated with each terminal module and linked to the auxiliary outgoing line (13, 14, 15, 16) of the other modules collects the distributed traffic.

Automatic equalizer for a synchronous digital transmission signal

Abstract: The present invention comes within the field of synchronous digital transmission. It provides an automatic variable equalization network (1) equipped with phase-locking means, in which a sign coincidence autocorrelator (30) correlates the polarities of two versions of the equalized signal delayed in relation to each other by τ, an integer multiple of the unit time interval of the transmission. It is used advantageously for equalizing synchronous digital transmission channels in switched telephone or telegraph networks.