There could be various explanations within a scenario for the supply chain to extend. For example, some emergency event could cause the closest supply depot to become inaccessible or a new supplier could be selected for the specific part which happens to be located farther away. There are different ways to overcome situation, such as increasing the maximum inventory level at the local warehouse or adopting a different part ordering strategy so that more than 7 parts are ordered at a time. If these cannot be changed, the part reliability can be improved so that less of these parts are needed in the first place. Of course, there are different costs and benefits associated with each decision, and these variables can be traded off based on the needs of the decision maker.
5. Conclusion
A simulation model environment called Virtual Environment for Operations and support Process Simulation (VE-OPS) is created to support future research in maintenance and logistics system design. It is developed using the SimPy package for the Python programming language, which is an object-oriented and open-source scripting platform. Class variables for simulation objects and processes are defined to simplify and to reduce the redundant efforts when modeling maintenance and logistics processes. The environment allows users to create and share models freely without the concern for licensing issues, and its flexibility allows for various aspects of maintenance and logistic systems to be studied.
Acknowledgements
The authors would like to thank Phil Fahringer, Heather Miller, and Anne Flannigan from Lockheed Martin Company for their support and expertise in the development of this tool and the reviewers for their comments to improve the paper.