Optimization Models Andalgorithms For Unloading Scheduling Of The Export Coal Terminals

Port enterprises handling production scheduling are both engineering andtechnical challenges, but also some complex academic issues. In order to improveport productivity, many scholars at home and abroad have been exploring methods tosolve such problems. A mathematical model about unloading optimization schedulingproblem with the goal of least time of the trains in port, is established successfullybased on the handling production process of the output coal terminals in this paper, inwhich the optimization algorithm and solved scheduling problems are also studied.The main results are as follows:This paper analyzing the various factors associated with unloading scheduling ofthe output coal terminal, uncovered some features of the unloading schedulingincluding complicated information, variable scheduling system, diverse alternativeprocesses, the solution with large amount of information. Through further study onthe unloading scheduling constraint relations, the mathematical equations of fourconstraint relations including uniqueness of reality job, its nature, yards and process,is established and that with the optimization goal, the least time of trains in port, amixed integer programming mathematical model of unloading scheduling is built, ofwhich the accuracy and engineering applicability is verified by practical casesapplication.In view of the fact that the mathematical model of unloading scheduling is aNP-Hard problem, in this paper, on the base of our in-depth study of the portproduction scheduling process, proposed a hierarchical primary-secondary compositealgorithm: a heuristic searching algorithm for the train-reaching events and heuristicsearching algorithm for the dumper-idling events. Based on the trains-reaching-planin the next period, the algorithm firstly solved the trains’ operating plan with theformer algorithm, and then corrected the plan using the later algorithm, finally abetter scheduling plan. And the application of this algorithm on one of the domesticcoal terminals worked well.To seek a better algorithm, a design of genetic algorithm based on the class coded and a new method of encoding and decoding of the individual for theuniqueness of unloading scheduling is proposed, constructing a fitness function moreapplicable to the actual unloading scheduling jobs. By experiments, a more practicaland reliable mixed termination condition of two termination rules is obtained. Thegenetic algorithm had been applied for the same domestic coal terminal, and achievedbetter results than the heuristic algorithm.Through the specific case and a large number of experiments, the comparativeanalysis of the two algorithms show that the genetic algorithm is more quality andmore flexibility, despite that the genetic algorithm is more time-consuming, whichcan be remedied by some effective measures. Thus, compared to heuristic algorithm,the genetic algorithm is more suitable for the actual production of coal terminal.