Exam 14: Operations Scheduling and Sequencing

The following five jobs, along with their processing time and due dates, are given below. a.Use the Shortest Processing Time Rule (SPT) and determine the average flow-time for the five jobs b.Use the Earliest Due Date Rule (EDD) and determine the average lateness and tardiness.

A movie theater requires the following minimum number of employees, each of which is required to have two consecutive days off. How many employees are needed so that each as two consecutive days off? Construct a work schedule for these employees.

In practice, whenever processing times of a set of jobs are about equal, managers typically use a first-come, first-serve rule.

A print shop has four jobs that have to be processed through their only five-color press.They usually use the first-come first-served method of scheduling jobs.However, the customers are waiting in the lobby for these jobs so the shop wants to minimize the average waiting time.They are going to use the shortest processing time rule to do so.Processing times for each job are as follows (assume this is the arrival order): Job A, 30 minutes; Job B, 17 minutes; Job C, 12 minutes; Job D, 39 minutes. a.In what order should the four jobs be done using the shortest processing time rule? b.What is the average waiting (flow) time for all jobs using the shortest processing time rule? c.What is the averaging waiting (flow) time using their usual first-come first-served rule?

If the highest priority is to minimize the average job lateness, then the jobs sequence should begin with those jobs requiring

Scheduling refers to determining the order in which jobs or tasks are processed.

Two examples of process-focused performance measures for sequencing rules are flow time and lateness.

A requirement of Johnson's two-resource sequencing rule is

Sequencing is not as much of a concern when several activities use a common resource.

A new surgical facility called Cut & Sew is opening in neighborhoods throughout the United States.They are job shops that handle a variety of outpatient surgical procedures.Their process is set up so that one doctor cuts and the other sews.They have five patients to sequence for tomorrow.Since the weather forecast is for a cool and sunny day, they would also like to play golf tomorrow.They want to sequence their patients with the objective of minimizing the time from the beginning of the first job until the finish of that job.The patients and estimated times are as follows: Sequence the patients using Johnson's Method, state the schedule for each operation, and determine the minimum makespan.

The shortest processing time rule and earliest due date rule will always provide the same sequence.

Indirectly, appointments reduce the cost of providing a service because the service provider is idle less each workday.

The time to rest and travel between games for baseball umpire crews is an important factor in developing their schedule.

Johnson's sequencing rule is used to sequence

Which of the following is not a consideration when designing an appointment system?

A lateness measure can only be 0 or a positive number.

At the end of each month, a research and development team writes status reports for the projects worked on during the month.The team leaders, Andrew and Julie, submit the reports to the R&D director on the first Monday of each month.It is late Friday evening and to their surprise, they have discovered that the month ends on Sunday and the reports are due on Monday morning.They have decided to come to work early Saturday morning, so they can finish the reports before Monday morning.They split the work as follows: Andrew will write and edit the reports while Julie collates data and draws all the necessary graphs.Assume that Julie starts her work on a report as soon as Andrew is finished with it and that Andrew works continuously.Times for the reports (in hours) are as follows: a.What is the order of the projects using Johnson's rule? b.How many hours will it take them to finish all the reports? c.How many hours is Andrew idle? d.How many hours is Julie idle?

Tardiness measures the amount of time by which the completion time exceeds the due date.

An airplane repair facility has a contract to repair cargo aircraft for a regional airline.There are 62 planes in the airline company's fleet of planes.Because of the punishing workload, the planes require a considerable amount of maintenance.The repair facility is trying to determine how to schedule the needed repairs.They want to compare the shortest processing time rule and the first-come first-served rule.Currently, the following planes need repair and are in the repair facility (data given is in order of plane arrival, only one plane is worked on at a time and the shop is open 24 hours a day, 7 days a week). a.In what order should the planes be repaired using the shortest processing time rule (use first letter of plane)? b.What is the average time (in hours) in the shop using the shortest processing time rule? c.What is the average time (in hours) in the shop using the first?come first?served rule?

High flow times reduce WIP inventory.