Determining parameters of a sample by X-ray scattering applying an extended genetic algorithm with truncated use of the mutation operator

摘要

A method of determining parameters of a sample by X-ray scattering comprising the steps ofa) exposing the sample to X-rays and measuring scattered X-ray intensity;b) generating a parameterised model of the sample which is used for numerical simulation of scattered X-ray intensity on the basis of a physical scattering theory;c) comparing the experimental and simulated X-ray scattering data to generate an error value;d) modifying the parameters of the model by means of a genetic algorithm involving an amount of individuals each with an equal number N of encoded parameters forming a generation and applying the genetic operators of "selection", "crossover" and "mutation" used for composing successive generations of evolving individuals, is characterised in that after a given number k of successive generations the genetic operator of "mutation" is no longer applied in evolution of further generations. The inventive method improves the genetic algorithm such that it can approximate the true sample parameters faster and with a higher accuracy.