Production Scheduling Nahmias, Chapter 8 ( D t lj l i ) (sv ...

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Moore’s Example Start with EDD schedule Job Time Done Due Tardy 2 2 2 6 0 5 5 7 8 0 3 3 10 9 1 4 4 14 11 3 1 6 20 18 2 Job 3 is first late job. Job 5 is longest of jobs 2,5,3. Moore’s Example Job Time Done Due Tardy 2 2 2 6 0 3 3 5 9 0 4 4 9 11 0 1 6 15 18 0 5 5 20 8 12 Average Flow = 51 / 5 = 10.2 Average tardiness = 12 / 5 = 2.4 Number tardy = 1 Max. Tardy =12 4
Results for Two Machines in Sequence • Johnsons Algorithm (Johnson 1954) • Given a set of jobs that must go through a sequence of two machines hi Johnsons J h Algorithm Al ith yields i ld the th sequence with ith minimum makespan – Makespan is sequence dependent. 1. Sort the times of the jobs on the two machines in two lists. 2. Find the shortest time in either list and remove job from both lists. � If time came from first list, place job in first available position. �� If time came from second list, list place job in last available position in sequence. 3. Repeat until lists are exhausted. � The resulting sequence will minimize the makespan. Data: Example: Johnsons Algorithm Job Time on M1 Time on M2 1 4 9 2 3 7 6 10 5 p Solution Illustrated in a Gantt Chart Machine 1 1 2 3 Johnsons Algorithm: � Final Sequence: 1-2-3 � Makespan: 28 Machine 2 1 2 3 Time 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Short task on M1 to “load up” quickly. Short task on M2 to “clear out” quickly. 9 10 5
Page 1 and 2: . Production Scheduling Nahmias, Ch
Page 3: Results for a Single Machine… •
Page 7 and 8: Dispatching Rules and Problems •
Page 9 and 10: A Sequencing Example (I) • Proble
Page 11 and 12: A Sequencing Example (V) • Config

Production Scheduling Nahmias, Chapter 8 ( D t lj l i ) (sv ...

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