Immunology as a Metaphor for Computational ... - Napier University

Chapter 3. Immune Systems for Scheduling 88¢ Until a schedule is complete or cannot be further extended:– Select a recombination mechanism with probability p r for simplerecombination, p sr for somatic recombination and p a for singlejob addition– Calculate the set S of possible antibodies that can be added via thechosen mechanism– Choose an antibody at random from S– Extend the partial schedule using the chosen antibodyFigure 3.17: An algorithm for generating completed schedules from the antibody populationevolved used SCHED2 IS3. Single Job Addition — in order that a complete schedule can be built when theantibody population does not contain at least one instance of each of the j jobs,a single job can be selected from the subset S 3 of all jobs that do not occur inany of the antibodies. This is then added to the end of the partial schedule.The procedure for forming a schedule using these mechanisms is shown in figure3.17.3.12 Generating Test DataExperimental test-data was generated in a manner similar to that described in section3.6.1, using the same benchmark problem jb11. Ten test-scenarios were generatedby mutating the original arrival date for each job with probability p u 0¦ 2 to anotherrandom date, in the range (0,300). A satisfactory schedule was generated for each scenariousing the genetic algorithm described by [Fang et al., 1993]. From each schedule(which consists of the order and timing of processing of every operation on every machine)5 antigens can be generated, where each antigen corresponds to the sequence