Smooth Adaptation by Sigmoid Shrinkage

Smooth Adaptation by Sigmoid Shrinkage AbdourrahmaneM . Atto ( EURASIPMember ) , Dominique Pastor ( EURASIPMember )

This paper addresses the properties of a subclass of sigmoid-based shrinkage functions: the non zeroforcing smooth sigmoid-based shrinkage functions or SigShrink functions. It provides a SURE optimization for the parameters of the SigShrink functions. The optimization is performed on an unbiased estimation risk obtained by using the functions of this subclass. The SURE SigShrink performance mea...

Wavelet shrinkage: unification of basic thresholding functions and thresholds

This work addresses the unification of some basic functions and thresholds used in nonparametric estimation of signals by shrinkage in the wavelet domain. The Soft and Hard thresholding functions are presented as degenerate smooth sigmoid based shrinkage functions. The shrinkage achieved by this new family of sigmoid based functions is then shown to be equivalent to a regularisation of wavelet ...

Wavelet shrinkage: from sparsity and robust testing to smooth adaptation

Bayesian sigmoid shrinkage with improper variance priors and an application to wavelet denoising

The normal Bayesian linear model is extended by assigning a flat prior to the δ power of the variance components of the regression coefficients (0<δ≤1⁄2) in order to improve prediction accuracy. In the case of orthonormal regressors, easy-to-compute analytic expressions are derived for the posterior distribution of the shrinkage and regression coefficients. The expected shrinkage is a sigmoid f...

Buckling Behaviors of Symmetric and Antisymmetric Functionally Graded Beams

The present study investigates buckling characteristics of both nonlinear symmetric power and sigmoid functionally graded (FG) beams. The volume fractions of metal and ceramic are assumed to be distributed through a beam thickness by the sigmoid-law distribution (S-FGM), and the symmetric power function (SP-FGM). These functions have smooth variation of properties across the boundary rather tha...