The full equation set for this model follows:
FINAL TIME = 100
Units: Month
INITIAL TIME = 0
Units: Month
TIME STEP = 0.25
Units: Month
SAVEPER = TIME STEP
Units: Month
| Inventory = INTEG( |
| production-sales, |
| 300) |
Units: Frame
net hire rate = (target workforce-Workforce)/time to adjust workforce
Units: Person/Month
production = Workforce*productivity
Units: Frame/Month
productivity = 1
Units: Frame/Month/Person
sales = 100 + STEP(50,20)
Units: Frame/Month
target production = sales
Units: Frame/Month
target workforce = target production/productivity
Units: Person
time to adjust workforce = 3
Units: Month
| Workforce = INTEG( |
| net hire rate, |
| target workforce) |
Units: Person
Each equation is consistent with discussion during the initial conceptualization. The equation for sales has sales steady at 100 until time 20, when sales step up to, and thereafter remain at, 150. This input pattern is used to test that the system is indeed at an equilibrium, and then check the adjustment to a new operating condition. This step input pattern is the cleanest pattern available for looking at the internally generated dynamics of a system such as this. It allows you to observe how a single shock propagates through the system without further external disturbance.
The model is complete. A simulation is performed with the name WF1.
