Scheduling of manufacturing systems based on extreme value theory and genetic algorithms

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.Includes bibliographical references (p. 143-154).by Velusamy Subramaniam.Ph.D

Internal transport control in pot plant production

Drawing up internal transport schedules in pot plant production is a very complex task. Scheduling internal transport at the operational level and providing control on a day-to-day or even hour-to-hour basis in particular requires a new approach. A hierarchical planning approach based on Anthony's framework was presented in this study to decompose the internal transport planning problem of pot plant nurseries into three planning levels with differentiating characteristics: strategic, tactical and operational planning.Emphasis was put on the operational planning level within the constraints of the tactical and strategic planning level. A discrete transport simulation model TRANSIM was designed and developed to analyse and evaluate the rules of thumb on internal transport used by growers in everyday life. The operational planning problem with respect to internal transport was divided into three sub-problems that deal with planning the work sequence, internal transport sequence and parking positions. Four local search methods - Simulated Annealing (SA), Genetic Algorithm (GA), Tabu Search (TS) and Random Search (RS) - were described and applied to generate good internal transport sequences in combination with a chosen parking method.The performance results of the local search methods applied to real-scale test cases show that Simulated Annealing is the most effective and efficient method of finding good internal transport sequences in combination with a relatively simple parking method.This thesis is also available as publication No. 99-03, ISBN 90-5406-175-8 of the DLO-Institute of Agricultural and Environmental Engineering (IMAG-DLO), P.O. Box 43, NL-6700 AA, Wageningen, The Netherlands</p