Enviaments recents

  • Filtering the time sequences of spectral parameters for speech recognition 

    Nadeu Camprubí, Climent; Paches, Pau; Biing-Hwang, Juang (1997-09)
    Article
    Accés restringit per política de l'editorial
    In automatic speech recognition, the signal is usually represented by a set of time sequences of spectral parameters (TSSPs) that model the temporal evolution of the spectral envelope frame-to-frame. Those sequences are ...
  • Self-splitting of beams into spatial solitons in planar waveguides made of quadratic nonlinear media 

    Perez, J; Torner Sabata, Lluís (1997-09)
    Article
    Accés restringit per política de l'editorial
    The propagation of intense light beams in planar optical waveguides made of quadratic nonlinear media under conditions for second-harmonic generation is investigated. It is shown numerically that under appropriate conditions, ...
  • Cross-coupled doa trackers 

    Pérez Neira, Ana Isabel; Lagunas Hernandez, Miguel A.; Kirlin, R L (1997-10)
    Article
    Accés obert
    A new robust, low complexity algorithm for multiuser tracking is proposed, modifying the two-stage parallel architecture of the estimate-maximize (EM) algorithm. The algorithm copes with spatially colored noise, large ...
  • Integral equation mei applied to three-dimensional arbitrary surfaces 

    Rius Casals, Juan Manuel; Parrón Granados, Josep; Úbeda Farré, Eduard; Mosig, J R (Institution of Electrical Engineers, 1997-11)
    Article
    Accés obert
    The authors present a new formulation of the integral equation of the measured equation of invariance (MEI) as a confined field integral equation discretised by the method of moments, in which the use of numerically derived ...
  • Soliton evolution in quasi-phase-matched second-harmonic generation 

    Torner Sabata, Lluís; Stegeman, G I (1997-11)
    Article
    Accés restringit per política de l'editorial
    We investigate the formation and evolution of spatial solitons with light beams propagating in quadratic nonlinear media under conditions for second-harmonic generation in quasi-phase-matched samples. We study the properties ...
  • Asymmetrical splitting of higher-order optical solitons induced by quintic nonlinearity 

    Artigas García, David; Torner Sabata, Lluís; Pérez Torres, Juan; Akhmediev, Juan P Torres I Nail N (1997-11)
    Article
    Accés restringit per política de l'editorial
    We address the effect of quintic nonlinearities in the propagation of optical solitons in cubic nonlinear media. Our focus is on the decay of higher-order solitons in the presence of self-defocusing quintic perturbations. ...
  • Stochastic vector quantization of images 

    Torres Urgell, Lluís; Casas Pla, Josep Ramon; Arias, E (1997-11)
    Article
    Accés restringit per política de l'editorial
    One of the most important steps in the vector quantization of images is the design of the codebook. The codebook is generally designed using the LBG algorithm, that is in essence a clustering algorithm which uses a large ...
  • Second-harmonic generation by intense beams containing phase dislocations:self-breaking into sets of solitons 

    Petrov, D V; Torner Sabata, Lluís (1997-12)
    Article
    Accés restringit per política de l'editorial
    Second-harmonic generation of light in bulk quadratic non-linear media with intense input beams containing phase dislocations is studied numerically under conditions for TypeI phase-matching. We investigate how, above a ...
  • Walking solitons in type II second-harmonic generation 

    Mihalache, Dumitru; Mazilu, D; Crasovan, L C; Torner Sabata, Lluís (1997-12)
    Article
    Accés restringit per política de l'editorial
    We find the families of spatial walking solitons propagating in quadratic nonlinear media under conditions for type II second-harmonic generation in the presence of Poynting vector walk-off between the interacting beams. ...
  • Walking solitons 

    Torner Sabata, Lluís; Santos Blanco, M. Concepción; Mihalache, Dumitru; Mazilu, D; Crasovan, L C (1997-12)
    Article
    Accés restringit per política de l'editorial
    By and large, optical

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