The basic VNS concept is enriched by embedding a Sequential VND along with two shaking steps and a set of neighbourhood
schemes to achieve a vigorous diversification during the search process. Moreover, a series of local search routines at two levels of the skeleton of the VNS are used to intensify the search. The merit of the two-level strategy is that it ensures a speedy and continuous balanced intensification and diversification by employing two shaking steps. The Pseudo code is presented in Fig. 5.