- n jobs 1 machine case
- Priority rules
- Comparative measures
- Flow shop case
Scheduling -- determine the timing and order of operations to optimize the use of resources to meet production requirements
n jobs 1 machine case
Priority rules (pg.590)
- First Come First Serve (FCFS)
- Shortest Processing Time (SPT)
- Earliest Due Date (EDD)
- Slack Time Remaining (STR) = time remaining before due date - remaining processing time
- The shortest STR goes first
- Critical Ratio (CR) = Time remaining before due date/Remaining processing time
- The smallest CR goes first
Comparison of priority rules
Average Completion time/Mean flow time =(Total processing time + total waiting time)/Number of jobs Average lateness = total late days/number of jobs
Example
Given:
A
20
30
10
1.5
B
30
50
20
1.7
C
10
25
15
2.5
D
16
80
64
5.0
E
18
60
42
3.3
Comparing the priority rules
Exercises
Pg. 607 Problem 5, 13
Flow shop scheduling
n jobs two machines: all jobs require the same sequence/order in visiting the machines
Johnson's rule
If the shortest time is for the first machine, do the job first If the shortest time is for the second machine, do the job last
Example
Job sequence: B à E à D à C à A
Gantt Chart representation
Exercises
Pg. 606 Problem 3, 9, 12, 14
https://www.uky.edu/~dsianita/300/schedule.html#flowshop
