Alcatel-Lucent

About: Alcatel-Lucent is a based out in Stuttgart, Germany. It is known for research contribution in the topics: Signal & Network packet. The organization has 37003 authors who have published 53332 publications receiving 1430547 citations. The organization is also known as: Alcatel-Lucent S.A. & Alcatel.

Metal-insulator transition in a doped semiconductor

Abstract: Millikelvin measurements of the conductivity as a function of donor density and uniaxial stress in bulk samples of phosphorus-doped silicon establish that the transition from metal to insulator is continuous, but sharper than predicted by scaling theories of localization The divergence of the dielectric susceptibility as the transition is approached from below also points out problems in current scaling theories The temperature dependence of the conductivity and the magnetoresistance in the metal indicate the importance of Coulomb interactions in describing the behavior of disordered systems

Spontaneous breaking of time-reversal symmetry in the pseudogap state of a high- T c superconductor

Abstract: A change in ‘symmetry’ is often observed when matter undergoes a phase transition—the symmetry is said to be spontaneously broken. The transition made by underdoped high-transition-temperature (high-Tc) superconductors is unusual, in that it is not a mean-field transition as seen in other superconductors. Rather, there is a region in the phase diagram above the superconducting transition temperature Tc (where phase coherence and superconductivity begin) but below a characteristic temperature T* where a ‘pseudogap’ appears in the spectrum of electronic excitations1,2. It is therefore important to establish if T* is just a cross-over temperature arising from fluctuations in the order parameter that will establish superconductivity at Tc (refs 3, 4), or if it marks a phase transition where symmetry is spontaneously broken5,6,7,8,9,10. Here we report that, for a material in the pseudogap state, left-circularly polarized photons give a different photocurrent from right-circularly polarized photons. This shows that time-reversal symmetry is spontaneously broken11 below T*, which therefore corresponds to a phase transition.

Recognition unit model training based on competing word and word string models

Abstract: A system pattern-based speech recognition, e.g., a hidden Markov model (HMM) based speech recognizer using Viterbi scoring. The principle of minimum recognition error rate is applied by the present invention using discriminative training. Various issues related to the special structure of HMMs are presented. Parameter update expressions for HMMs are provided.

Micromechanical optical modulator having a reduced-mass composite membrane

Abstract: A method and apparatus for a micromechanical modulator having a reduced-mass multilayer membrane is disclosed. The modulator includes a movable composite membrane suspended over a subtrate. The composite membrane consists of an overlayer and an underlayer. The overlayer is characterized by a thickness that is less than one-quarter of a wavelength of the optical signal being modulated. Under the action of a bias voltage, the movable membrane moves from a quiescent position to a second position closer to the substrate. The modulator is fabricated so that in either the quiescent position or the second position the gap between the composite membrane and the substrate is equal to d=mλ/4-n s s when n u is about equal to (n s ) 0 .5, where m is an even integer, λ is the wavelength of the optical signal being modulated, n s is the refractive index of the subtrate, n u is the refractive index of the underlayer, n o is the refractive index of the overlayer, and s is the thickness of the overlayer. More generally, the gap may be given by d=mλ/4-n s s+(n u -n s 0 .5) (λ/10) sin (4πn o s/λ).

Geometry-driven photorealistic facial expression synthesis

Abstract: Expression mapping (also called performance driven animation) has been a popular method for generating facial animations. A shortcoming of this method is that it does not generate expression details such as the wrinkles due to skin deformations. In this paper, we provide a solution to this problem. We have developed a geometry-driven facial expression synthesis system. Given feature point positions (the geometry) of a facial expression, our system automatically synthesizes a corresponding expression image that includes photorealistic and natural looking expression details. Due to the difficulty of point tracking, the number of feature points required by the synthesis system is, in general, more than what is directly available from a performance sequence. We have developed a technique to infer the missing feature point motions from the tracked subset by using an example-based approach. Another application of our system is expression editing where the user drags feature points while the system interactively generates facial expressions with skin deformation details.