Different and there may be multiple operations on

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Unformatted text preview: and there may be multiple operations on some machines. machines. Parallel processing vs. sequential processing: parallel Parallel parallel processing means that the machines are identical. processing Flow time of job i: Time elapsed from initiation of first job Flow Time until completion of job i. until Makespan: Flow time of the job completed last. Makespan Flow Tardiness: The positive difference between the Tardiness The completion time and the due date. completion Lateness: Difference between completion time and due Lateness Difference date (may be negative). Common Sequencing Rules Common FCFS. First Come First Served. Jobs processed in the order they come to the shop. in SPT. Shortest Processing Time. Jobs with the shortest processing time are scheduled first. EDD. Earliest Due Date. Jobs are sequenced according to their due dates. according CR. Critical Ratio. Compute the ratio of processing time of the job and remaining time until the due date. Schedule the job with the largest CR value next. largest 5 Example Job Number Processing Time 1 11 2 29 3 31 4 1 5 2 Due Time 61 45 31 33 32 Example Apply the following rules: Apply First come, first served First Shortest processing time (minimize mean flow time) Shortest Earliest due date (minimize maximum lateness) Earliest Critical Ratio Scheduling Critical 6 Sequencing for Single Machine Minimize mean flow time (SPT) Minimize Minimize maximum lateness (EDD) Minimize Minimize the number of tardy jobs (Moore’s algorithm) Precedence constraints (Lawler’s algorithm) Precedence Multiple Machine Sequencing Assume that several jobs must be processed on more than one machine. (e.g. n jjobs...
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This document was uploaded on 03/23/2014.

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