Consumable Resources

ProcessModel resources are always returned after use, so they are not the way to model something that gets consumed, like raw materials or stock that is used up.

To model a consumable, use an Inventory node instead. An inventory holds a quantity that is drawn down as it is used and topped up by arrivals or reorders. A resource models a reusable server (a person or machine); an inventory models a depleting supply.

LegacyHow this worked in the previous version

Modeling consumable resources such as money, energy, water, etc. Useful for modeling the consumption and replenishment of a resource.

Suggested Technique

• Create a variable to represent the consumable resource (see Variables).
• When an activity, storage, or routing uses a consumable resource, decrement the variable’s value using the DEC statement in the Action logic.
• When the resource is replenished in the model, increment the variable’s value using the INC statement in the appropriate Action logic.

Example: A hydro-electric power plant wants to track its usage of water, a consumable resource. Power Request (the entity flowing through the model) has an attribute called BTU indicating the energy level required to produce the needed power. The Steam activity uses 1,000 gallons of water for every BTU, and the Recycle activity restores about 70% of the water back into the system. The question is, how many gallons are not recovered.

TO DO: Create a variable called v_Water. Enter the Action logic as shown above for the appropriate activity.