Simulation and OR (Operations Research) in combination for practical optimization
Prof Dr. N.M. van Dijk - University of Amsterdam / INCONTROL Simulation Solutions

Should we pool capacities or not?

This is a question that one can regularly be confronted with in operations and service management.

A question that exists at the level of individual queues such as for counters in a post office or bank, of agents within call centres, of check-in desks at airports, of physicians pooling within hospitals up to the level of virtualizing call centres, of regionally allocating waiting lists or of configuring administrative processes.

• A question that seems too simple to ask (for the simple case of parallel queues).
• A question that (even for this simple case) violates analytical tractability.
• A question which necessarily requires a combination of queuing (as OR discipline) and simulation (as evaluative tool).

A question thus for which simulation, at all levels, is an indispensable tool. Nevertheless, a question for which simulation still requires further steps for ‘optimization’. Following the theme of whether to pool or not, we will show that a combined approach (SimOR) of state-of-the-art Simulation (techniques and tools) and classical Operations Research methods (queuing, linear programming and scheduling) can be exploited mutually beneficial.

First, an example of parallel queues will be provided that shows the necessary combination of queuing and simulation. Next, the mutual benefits of both queuing and simulation will be highlighted.
Finally, the SimOR approach will be illustrated for:

• Call centres,
• Checking in at airports
• Blood platelet production
• Train scheduling

To pool or not, with its diverse applications, is just one question for which this SimOR approach can be most fruitful if not necessary for ‘practical optimization’.