Exam 14: Operations Scheduling and Sequencing

Gantt charts can show what jobs are ahead of schedule, behind schedule, and on schedule.

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?

Scheduling and sequencing methods used in manufacturing are more beneficial in low-contact, than high-contact, service processes.

Appointments systems often overbook to maximize revenue.

A tardiness measure can be either zero (0) or a positive number.

The chief disadvantage of the shortest processing time rule is

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

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

A restaurant needs the following number of wait staff to serve its evening guests. How many employees are needed so that each as two consecutive days off? Construct a work schedule for these employees.

Compare and contrast the advantages and disadvantages of the Shortest Processing Time (SPT) and the Earliest Due Date (EDD) sequencing rules.

For a single processor, a first-come, first-served (FCFS) rule minimizes the average flow time because customer waiting time will be minimized.

The time needed to process a given set of jobs is called

The EDD rule minimizes the maximum of jobs past due but doesn't perform well on average flow-time, WIP inventory or resource utilization.

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

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?

The numerical difference between the completion time and the due date is called

A company is faced with seven tasks that have to be processed through two work centers, work center I and then center II. Assume work center I works continuously and that they are using Johnson's rule. Work centers need not change over to new jobs at the same time. Data appears below in hours: a.What is the sequence of tasks? b.What is the time in hours to complete all the tasks in both work centers? c.What is the total idle time in hours for work center I? d.What is the total idle time in hours for work center II?

Differentiate between scheduling and sequencing.

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

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