J.C. Becceneri, S. Stephany, H.F. de Campos Velho, A.J. Silva Neto (2006): Solution of the Inverse Problem of Radiative Properties Estimation with Particle Swarm Optimization Techniques, Inverse Problems in Engineering Seminar (IPES), July 26-27, Iowa State University, USA.

Abstract: Inverse radiative transfer problems have several relevant applications, in different areas such as environmental sciences, engineering and medicine. Some outstanding examples are parameter and function estimation for global climate models, hydrologic optics and medical tomography. When formulated implicitly inverse problems are usually written as optimization problems. Several heuristics that mimic natural behaviors have been proposed for the solution of optimization problems. In particular some of the most recent algorithms, classified within the field of swarm intelligence, are based on the observation of social insects like bees, ants, etc. In the last decade of the past century the particle swarm optimization (PSO) techniques were introduced for the continuous optimization problem, based on the analogy of bird and fish school behavior. Here we present an implementation of the PSO techniques for the solution of the inverse radiative transfer problem of radiative properties estimation. In this approach it is required the solution of the direct radiative transfer problem which is modeled by the linear version of the Boltzmann equation. For that purpose we use a discrete ordinates method combined with the finite difference method. Some general strategies are proposed and discussed for the PSO implementation for the estimation of the optical thickness, single scattering albedo, and diffuse reflectivities in a one dimensional plane-parallel participating medium. Test case results demonstrate the feasibility of the use of the proposed methodology.