“…Other stochastic methods are based on the so‐called closure technique, which consists of a truncation of the cumulant series expansion of the response characteristic function (CF) at
th term
3 . A popular class, on which many proposed literature methods are based, is the family of perturbation methods
4‐6 . This method is mainly based on a Taylor series expansion in terms of a set of zero‐mean random variables (RVs), where different levels of accuracy can be obtained by truncating the series at different terms.…”