ESTIMATION OF SIZE DISTRIBUTION IN CONCENTRATED PARTICLE SYSTEMS FROM LIGHT SCATTERING MEASUREMENTS

FRONTINI, GLORIA L, OTERO, FERNANDO, MESSINEO, G. , ELIÇABE, G.

Miami, La Florida , EEUU

Simposio; Inverse Problems, Design and Optimization Symposium; 2007

State University of Florida

We consider the estimation of the Particle Size Distribution (PSD) of concentrated particle systems with low contrast between paticles and solvent from Light Scattering (LS) measurements. We follow Pedersen’s monodisperse approximation[1], in which an effective particle volume fraction is used to take into account interference between particles. This parameter must be determined simultaneously with the PSD to characterize the system. To solve the inverse problem we first assume that the PSD is described by a log-normal function. We apply the Levenwerg-Marquard algorithm for the nonlinear parameter estimation. We also approach the free-form case following the scheme given in [2], where Tikhonov’s regularization method is used to estimate the PSD, simultaneously with a non-linear least squares optimization used to estimate the effective parameter. The solutions obtained from the analysis of simulated measurements showed that a-priori knowledge of the distribution form improves the quality of the estimation, but the problem can be solved properly when actual PSD form is not known.