Final exam - Chapter 14 Flashcards
Scheduling
Scheduling
refers to the assignment of start and completion times to particular jobs, people, or equipment.
•Sequencing
•Sequencing
refers to determining the order in which jobs or tasks are processed.
First come first server
Sequencing or Scheduling
Sequencing
Sequencing is used in what sector
service sector
What’s a good example that the teacher talked about for sequencing
Walmart line
Staff scheduling problem:
Staff scheduling problem:
Given minimum worker requirements for each day of the week, schedule employees so that each has two consecutive days off and all demand requirements are met.
Method:
2
Method:
- Locate the set of at least two consecutive days with the smallest requirements, circle the requirements for these days, & assign a worker to all days not circled.
- Subtract 1 from the requirement of each day not circled, removing existing circles, and repeat this process until all requirements are satisfied.
learn how to do slide 6 in chapter 14
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Difference between flow time and make span (test question)
flowtime - how much time it takes to make one unit
Make span - how much time it takes to make one batch
Lateness
Lateness is the difference between the completion time and the due date (either positive or negative).
Tardiness
Tardiness is the amount of time by which the completion time exceeds the due date. (Tardiness is defined as zero if the job is completed before the due date, and therefore no credit is given for completing a job early).
Lateness and tardiness measure
Lateness and tardiness measure performance related to customer-focused due-date criteria.
Two of the most popular sequencing rules for prioritizing jobs are:
Two of the most popular sequencing rules for prioritizing jobs are:
Shortest Processing Time (SPT)
Earliest Due Date (EDD)
Shortest Processing Time (SPT)
Shortest Processing Time (SPT)
With different processing times, SPT sequencing maximizes resource utilization and minimizes average flow time and WIP inventory.
Earliest Due Date (EDD)
Earliest Due Date (EDD)
Earliest Due Date (EDD), minimizes the maximum job tardiness and lateness.
Other Sequencing Rule
First come-first served (FCFS).
How do we use the shortest processing time?
- Whichever have the shortest processing time you are going to process that first
- you are ignoring due date information
- minimize flowe time and w/i/p
What is the problem with the shortest processing time
- the late processing time can be never completed since it takes too much time to process
- a lot of TARDINESS
Earliest due date:
you process whatever that is due first
what is the problem with the earliest due date
it may block the short processing time products from being processed
In a serial manufacturing process, a bottleneck workstation controls the output of the entire process. Thus, it is critical to schedule it efficiently.
- When processing times are relatively equal, first-come-first-served sequencing works well.
- With different processing times, SPT sequencing maximizes workstation utilization and minimizes average job flow time.
- Using Earliest Due Date (EDD), the maximum job tardiness and lateness are minimized.
learn slide 12 - 15 (math shit) test question
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Two-Resource Sequencing Problem (Johnson’s Rule)
- List the jobs and their processing times on Resources #1 and #2.
- Find the job with the shortest processing time (on either resource).
- If this time corresponds to Resource #1, sequence the job first; if it corresponds to Resource #2, sequence the job last.
- Repeat steps 2 and 3, using the next-shortest processing time and working inward from both ends of the sequence until all jobs have been scheduled
learn slide 17, 18 (math shit) test question
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