Dynamic Scheduling Optimization Of Port Stacker-reclaimers Under The Mode Of "Port Before Factory"

With the vigorous development of the port-neighboring industry,China’s port industry is further exploring the new mode of "Port before Factory".Under this mode,the raw materials required for steel factory production are distributed to the boiler of the steel factory through the belt conveyor for subsequent production after being reclaimed and mixed at the port yard,which means the mode realizes the seamless connection between port’s logistics chain and steel factory’s production chain.And it also puts forward higher requirements for the port yard reclaiming operation:the operation involves the ratio of raw materials and the effectiveness of the stacker-reclaimer scheduling,its quality and efficiency directly affect the production of steel factory;in addition,due to the pull of the steel factory’s demand,the distribution of raw materials in the port becomes more frequent,which greatly increases the difficulty of the operation and the uncertainty of the production environment.Therefore,based on the characteristics of port production under the mode of "Port before Factory",this paper proposes a refined dynamic scheduling optimization method for stacker-reclaimers.Firstly,stockpiles are divided into several equal unit stockpiles,and an optimization model for stacker-reclaimer scheduling is established with the objective of minimizing the makespan.Secondly,according to the characteristics of the problem and the algorithm,the wolf pack algorithm is improved and the chaotic wolf pack algorithm is proposed.Then in order to compare their algorithm performance,both chaotic wolf pack algorithm and standard wolf pack algorithm are used to solve the miniature and large-scale problems.and static scheduling schemes under the two conditions are obtained.After that,dynamic scheduling optimization when machine failure is realized by adopting rescheduling mechanism driven by period and event.Finally,in order to ensure the stability of the model and scheduling system,the sensitivity analysis of the rescheduling period and the weight of unit pile is carried out.The results show that compared with the standard wolf swarm algorithm,the chaos wolf swarm algorithm proposed in this paper has a significant improvement in performance.And the scheduling optimization method proposed in this paper can adapt to the dynamic production environment and meet the practical requirements for "Port before Factory".