Page 694 - ExtendSim User Guide

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668 Analysis
Optimization
Place an Optimizer block (Value library) in a convenient place in the model.
Optimizer block added at lower left of MyOptimizer model
You will be adding most variables to the Opti- mizer block by doing a clone-drop.
To get an idea of what it looks like without any entries, open the Optimizer’s dialog.
As seen to the right, the Optimize block’s Objectives tab has two sections:
• AVariablestableforenteringvariables and specifying their limits
• AnEquationpaneforenteringtheobjec- tive function.
Close the Optimizer’s dialog.
Determining the form of the function
The Optimizer block will try to reach a goal
by changing the values of model variables
based on an equation that measures how close
the goal is. The first step is to lay out the form of the objective function. This helps clarify what will be optimized and which factors affect that goal. In most cases, you want to minimize a cost or maximize a profit.
This model tries to maximize the beverage stand’s profit. The factors that affect profit are: • Beveragecosts($1perdrinkplus$1,000pertank)
• The revenue for each drink sold ($2.50 per drink)
• Apenaltyorreductioninprofitifyourunoutofdrinkstosell($100perminute)
Using this information, the form for the objective function is:
MaxProfit = $2.50*#sold - #deliveries*($1000 + #drinks*$1.00) - time empty * $100
Adding variables to the Optimizer
The form for the objective function is the basis for the cost equation that you will enter in the Optimizer’s dialog. Before you do that, you need to obtain the necessary model variables
Objectives tab in Optimizer block
How To
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