Exam 14: Short-Term Scheduling

A practitioner of family medicine begins her day with five patients needing urgent care. She does a very brief assessment of what each patient appears to need and estimates the time required of each. None of the cases is life-threatening, and so she determines to take the five in the order that they arrived at the clinic. The processing-time data for these patients, in the order they arrived, are: Patient A, 50 minutes; Patient B, 10 minutes; Patient C, 40 minutes; Patient D, 30 minutes; and Patient E, 15 minutes. (a) If it is now 8:00 a.m., at what time will the doctor be finished with all five of these emergencies? (b) How much time will the five patients have collectively spent waiting? (c) How much less time would have been spent waiting if the doctor had taken the patients according to shortest processing time?

Five jobs are waiting for processing through two work centers. Their processing time (in minutes) at each work center is contained in the table below. Each job requires work center Alpha before work center Beta. According to Johnson's rule, what is the optimum sequence of jobs and the minimum time for completion of all jobs?

Forward scheduling is the scheduling of:

The jobs listed below need to be completed. Assume that it is now day 140. If the jobs are sequenced according to the shortest processing time rule, what is the lateness of job A?

Bob Dresser operates a major appliance warranty service center. His operation has two check stations that are required at the end of every repair task performed by his appliance repair staff. These are the Functionality Review (FR) and the Overall Scan (OS). The FR must be performed successfully before the OS is begun. On Friday morning, six repair jobs are completed, awaiting these two inspection activities. Processing times are given in minutes. (a) What is the optimal sequence of jobs for the objective of minimizing the total flow time? (b) Show your work, and document the sequence. (c) Chart the solution to this problem. (d) What jobs are being processed at time period 90? (e) What is the total flow time of this problem?

In manufacturing scheduling, physical inventories of goods can buffer variations in demand, but service scheduling normally lacks that buffer because services are generally consumed at the same time they are delivered.

What is input-output control?

What does Johnson's rule do?

Identify some scheduling optimization systems that are used at retail stores. Describe what these systems do.

Machines A, B, C, and D have been in use for several years, while machine E is new. The following table provides data on the value of production of each job when performed on a specific machine. (a) Determine the set of assignments that maximizes production value. (b) What is the total production value of your assignments? (c) Which machine should be retired (i.e., gets no assignment)?

Given the following chart of jobs assigned with Johnson's rule, suppose that all the jobs (A, B, C, etc) could be evenly divided into two tasks (such as A1 and A2, B1 and B2, etc). Suppose job B is divided into jobs B1 and B2, each with a body work time of 4.5 hours and a paint time of 2 hours. How much is makespan reduced by this splitting of B?

Which of the following is NOT required to be known in order to schedule process-focused facilities?

With forward scheduling, jobs are scheduled as late as possible within the time allowed by the customer due dates.

Short-term schedules are prepared:

Use Johnson's rule to determine the optimal sequencing for the five jobs to be processed on two machines in a fixed order (Machine 1 before Machine 2). The processing times are given in the table below. (a) What is the optimal sequence? (b) What is the total flow time for this sequence?

The ________ is a special class of linear programming models that involves assigning tasks or jobs to resources.

Which of the following is NOT a key direct benefit from effective internal or external scheduling?

Sequencing (or dispatching):

________ uses computerized short-term scheduling to overcome the disadvantages of rule-based systems by providing the user with interactive computing and graphical output.

What is a method of input-output control that uses a system of cards to limit the amount of work at a work center and also to control lead time and monitor backlog?