Page 155 - Data Science Algorithms in a Week

Simulation Optimization Using a Hybrid Scheme … 139

This stabilization policy has been reached using the maximum production capacity of
5,600 units/week as shown in Figure 6. This is due to the constraint in manpower in the
lenses manufacturing department.

Testing for Policy Robustness

To test the stabilization policy it is generated a sudden change in the customer order
rate in week 10. The values for the new EPs are shown in Table 3.

Table 3. Parameter values for the stabilization policy

Percentage change in New EP for Preforms New EP for Presses New EP for Finished
customer order rate WIP Level (Units) WIP Level (Units) Goods Inventory (Units)
-15% 8377 13178 3045
-10% 8789 13691 3256
-5% 8828 13739 3275
+10% 8828 13739 3275

The customer order rate is increased or decreased to new levels calculated as a
percentage of its initial value. This is displayed in Figure 7. Moreover, Figures 8, 9 and
10 depict the robust behavior of the Preforms WIP Level, Presses WIP Level, and
Finished Goods Inventory variables to the changes in customer orders.

6,000
6,000
6,000
6,000

4,000
4,000
4,000
4,000
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (week)
Customer Order Rate:-15%
Customer Order Rate:-10%
Customer Order Rate:-5%
Customer Order Rate:+10%

Figure 7. Changes in customer orders to test policy robustness.