IE434 Scheduling
HOMEWORK # 2
Due Date: 20 May 2011
Name of the Student:
Number of the Student:
Question 1
The Foundry Company has the following information on five jobs waiting to
be processed in the molding work center. Processing can start
immediately.
Job
1
2
3
4
5
Remaining
Processing Time
(days)
3
9
18
12
7
Due Date (days
from now)
6
12
11
8
8
Remaining
Number of
Operations
3
7
2
5
4
a) If the “Slack per Number of Remaining Operations”
(S/RO) priority sequencing rule is used;
i. What will be the sequence of the jobs?
ii. What is the average job lateness (in days) of the
sequence?
iii. What is the average number of jobs in the molding work
center using the S/RO sequence?
b) If the “Shortest Process Time” (SPT) priority sequencing
rule is used;
iv. What will be the sequence of the jobs?
v. What is the average job lateness (in days) of the
sequence?
vi. What is the average number of jobs in the molding work
center using the SPT sequence?
(c) Which of the two priority sequencing rules would you prefer for
the subject set of jobs at the molding work center? Write your
comments.
T.Cengizhan Pamir
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IE434 Scheduling
Question 2
Assume that we have 4 machines and 6 jobs for which the processing
times (in terms of hrs) are given as follows;
Jobs
Mach 1
Mach 2
Job 1
Job 2
Job 3
Job 4
Job 5
Job 6
2
7
6
11
4
4
3
5
7
4
6
2
Mach 3 Mach 4
4
4
12
14
8
3
9
10
5
8
3
5
All of these 6 jobs, which are available at the start of the schedule, have
identical routings and they pass through the 4 machines in the same
order. Their setup times are independent. Find the schedule which
minimizes the make-span required to process all these jobs (Show all
steps leading to the final solution). Which sequence would you select and
why?
T.Cengizhan Pamir
Page 2 / 2