543 research outputs found
Communications-Inspired Projection Design with Application to Compressive Sensing
We consider the recovery of an underlying signal x \in C^m based on
projection measurements of the form y=Mx+w, where y \in C^l and w is
measurement noise; we are interested in the case l < m. It is assumed that the
signal model p(x) is known, and w CN(w;0,S_w), for known S_W. The objective is
to design a projection matrix M \in C^(l x m) to maximize key
information-theoretic quantities with operational significance, including the
mutual information between the signal and the projections I(x;y) or the Renyi
entropy of the projections h_a(y) (Shannon entropy is a special case). By
capitalizing on explicit characterizations of the gradients of the information
measures with respect to the projections matrix, where we also partially extend
the well-known results of Palomar and Verdu from the mutual information to the
Renyi entropy domain, we unveil the key operations carried out by the optimal
projections designs: mode exposure and mode alignment. Experiments are
considered for the case of compressive sensing (CS) applied to imagery. In this
context, we provide a demonstration of the performance improvement possible
through the application of the novel projection designs in relation to
conventional ones, as well as justification for a fast online projections
design method with which state-of-the-art adaptive CS signal recovery is
achieved.Comment: 25 pages, 7 figures, parts of material published in IEEE ICASSP 2012,
submitted to SIIM
Método automático de análisis de señales acústicas no-estacionarias
Método automático de análisis de señales acústicas noestacionarias.
Esta patente de invención presenta un método de análisis
de la señal acústica temporal generada durante determinados
eventos o sucesos de cambio de estado o transformaciones
en todo tipo de sistemas fÃsicos caracterizada
por presentar una distribución tiempo-frecuencia cualesquiera.
Un método basado en un algoritmo matemático
permite, después de varias etapas intermedias, la determinación
univoca de la cantidad de información (entropÃa)
a partir de un espectro sonoro. Este procedimiento
es aplicable a todo sistema de cálculo automático y es de
especial interés en ciencias biomédicas, es válido en la
determinación de fracturas en estructuras metálicas asÃ
como en la prevención de movimientos sÃsmicos. La presente
invención constituye una mejora en los métodos actualmente operativos.Consejo Superior de Investigaciones CientÃficas (España)B1 Patente con informe sobre el estado de la ténic
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