Computation Section
Process Flow Optimization
 Products Only

Selecting this option produces a linear programming model with variables for the number of each product to produce. It computes the optimum product mix. The objective is to maximize operating profit. The Linear Model dialog for the model is presented as below. The data is for the example problem given earlier.

The name of the model is Project_LP1. It cannot be changed. The goal is to maximize the objective. The number of variables is the number of products, three in this case. The number of constraints is the number of resources, four in this case. These numbers may be increased so that other variables and constraints can be added to the model, but they must not be decreased.

The various model features are controlled by the radial buttons and check boxes. The easiest way is simply to accept the options as given, but it should be possible to change the others without altering the model. The model can also be changed with the Change button on the model worksheet.

  The figure below shows the model constructed with the first model option. The data for the model is derived directly from the data on the Project Worksheet. We have labeled the sources of the data on the figure. After creation the model is immediately solved. The solution shown is the optimum product mix for the example. In addition to the optimum product mix, the system bottlenecks can be found by identifying the tight constraints. The bottlenecks for the example are the capacity of the Run-in resource and the markets for products B and C.
The optimum sales quantities are transferred to the Sales column on the Project worksheet. The numbers in the column are linked by formulas to the Project LP1 worksheet, and the column is colored yellow. When features of the LP model are changed and the model resolved, the solution is reflected in the sales column. The user can change numbers in the sales column, but the automatic links to the Project LP1 worksheet are lost.


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Operations Management / Industrial Engineering
by Paul A. Jensen
Copyright 2004 - All rights reserved

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