Advanced Modeling
Jose Zuniga
Discussion Problem
This week, we are discussing some advanced modeling techniques. Which of these techniques do you believe you will use in your final project?
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Assignment Problems
Kelton Chapter 9 problem 2
Problem 9.5.2
Modify Model 9-1 to support preemption of the Doctor resource for Urgent patients. In particular. if all doctors are busy when an Urgent patient arrives, the Urgent patient should preempt a doctor from One of the Other non-Urgent patients. Compare the results of the models. Would you advise that the emergency department make the corresponding change in the real system?
Initial Setup
The Interrupt step may be used to model resource preemption scenarios, allowing model logic to interrupt a process delay activity that is using a resource, in order to release the resource for a higher priority activity. This approach allows very flexible preemption capability with precise control over which entities are preempted and how the preempted entities are subsequently processed. To interrupt a token at a Server, Combiner or Separator, simply specify ObjectName.OnEnteredProcessing as the Process Name property of the Interrupt step.
The InterruptingServerWithMultipleCapacity.spfx Simbit file was used as an example. First a patient priority of \(2\) for Urgent and \(1\) for all others (since only Urgent patients are preempted) was entered in each entity’s Routing Logic > Initial Priority property field. Then, for each resource’s add-on “processing’” process under the Processes tab before the Assign steps (after the Seize steps):
- Added a Decide step with:
- Name of
IfServerAvailable. - Condition or Probability of
Doctor.Capacity.Remaining > 0.
- Name of
- Added an Interrupt step with:
- Name of
LowerPriorityJob. - Process Name of:
ExamRooms.OnEnteredProcessingfor Exam Rooms.TraumaRooms.OnEnteredProcessingfor Trauma Rooms.TreatmentRooms.OnEnteredProcessingfor Treatment Rooms.
- Selection Rule of
Smallest Value First. - Value Expression of
Candidate.Entity.Priority. - Filter Expression of
(Candidate.Entity.Priority+.2) < Entity.Priority.
- Name of
| Exam Rooms | Trauma Rooms | Treatment Rooms |
|---|---|---|
 |
 |
 |
Compare Results
| No Patient Preemption |
|---|
 |
| Urgent Patient Preemption |
|---|
 |
The simulation indicates that allowing Urgent patients to preempt doctors from non-urgent patients decreases Total Cost (TC) and increases Satisfaction for all patient categories. It is advisable for the Hospital to make the corresponding change in the real system.
References
https://www.simio.com/products/OptQuest.php
Simio and Simulation: Modeling, Analysis, Applications 3d Ed. by W. David Kelton, Jeffrey S. Smith and David T. Sturrock with Simio software.
Discrete-Event Systems Simulation, 5th Edition (2010), by Jerry Banks, John S. Carlson, Barry L. Nelson,and David M. Nicol.