Question

Johnson Bellman rule states that:
a) If the smallest processing time occurs under the first machine, do that job last,
b) If the smallest processing time occurs under the first
c) machine, do that job first,
If the smallest processing time occurs under the second machine, do that job first,
d) If the smallest processing time occurs under the second machine keep the
processing pending.​

Answer 1

Answer:

In operations research, Johnson's rule is a method of scheduling jobs in two work centers. Its primary objective is to find an optimal sequence of jobs to reduce makespan (the total amount of time it takes to complete all jobs). It also reduces the amount of idle time between the two work center

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Answer 2

b) If the smallest processing time occurs under the first machine, do that job first.

Explanation:

The job with the shortest processing time for the first process should be executed first, and the job with the shortest processing time for the second process should be executed last.

The goals of Johnson's rule are:

• Minimize processing time to chain a workgroup on two workstations.

• Minimize total machine downtime.

• To minimize the flow time from the start of the first job to the end of the last job.

For the technique to be used, several conditions must be met:

• The working time (including setup and processing) must be known in advance and constant for each job at each work center.

• The duration of the task must be independent of the sequence of the work.

• All jobs must follow the same two-set job sequence.

• Task priority is not used.

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