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  1. 1. Distributed Supply Chain Simulation <ul><li>Gan Boon Ping </li></ul><ul><li>Manufacturing Planning and Scheduling Group </li></ul>
  2. 2. Agenda <ul><li>Overview </li></ul><ul><li>Technological Challenges </li></ul><ul><li>Collaboration Project </li></ul><ul><li>Conclusions </li></ul>
  3. 3. Supply Chain Management <ul><li>Covers the planning and management of materials and information, from the manufacturer through the distributors to the customer </li></ul>Synchronised material flow  excellence in operations Visibility, fast information flow  collaborative planning RM Supplier RM Supplier RM Supplier Factory Factory Ware house Ware house Ware house Factory Factory Distri butor Distri butor Customer Customer Customer
  4. 4. Supply Chain Simulation <ul><li>Simulation of supply chains can help in the optimization process by evaluating the impact of alternative policies </li></ul><ul><li>To answer operational or tactical questions </li></ul><ul><li>The result is: How execution would be? </li></ul>
  5. 5. Typical Characteristics of a Supply Chain <ul><li>Involve multiple companies that are geographically distributed </li></ul><ul><li>Companies do not belong to the same enterprise </li></ul>
  6. 6. Enabling Technology - Distributed Simulation Users at different plants interact independently with tool as usual for model building and execution Internet <ul><li>In the background, the system </li></ul><ul><li>initiates remote model </li></ul><ul><li>send/receive interactions through Internet </li></ul><ul><li>compiles results together </li></ul>High Level Architecture
  7. 7. High Level Architecture <ul><li>A standard that defines rules and interface specification for interoperability of simulation models </li></ul><ul><li>Adopted as IEEE (1516) and OMG standard </li></ul><ul><li>Defense Modeling and Simulation Office (DMSO) provides free download of the High Level Architecture implementation </li></ul>
  8. 8. High Level Architecture Interface Run-Time Infrastructure (RTI) Federation Management Declaration Management Object Management Ownership Management Time Management Data Distribution Management Passive Viewers Simulations Simulation Surrogates FED FOM HLA Rules (Federates) HLA Rules (Federations) SOM SOM SOM SOM SOM SOM SOM SOM SOM
  9. 9. Technological Challenges <ul><li>Security </li></ul><ul><li>Synchronization </li></ul><ul><li>Simultaneous Scenarios Evaluations </li></ul><ul><li>Fault Tolerance </li></ul>
  10. 10. Security <ul><li>Data shielding </li></ul><ul><ul><li>Crucial in supply chain as companies are not willing to share sensitive data </li></ul></ul><ul><li>Authentication </li></ul><ul><ul><li>Verify the identity of federates joining the simulation is a genuine one </li></ul></ul>
  11. 11. Data Shielding Assembly & Test Distribution Centre WaferFab Assembly & Test Model Distribution Centre Model WaferFab Model Scheduling System A Scheduling System B Supply Chain Planner HLA-RTI Internet <ul><li>Data can be shielded: </li></ul><ul><li>Details of local execution models do not have to be disclosed to other supply chain members </li></ul>Material flow Customers Information flow
  12. 12. Data Shielding <ul><li>Unable to shield/share data from/with a subset of federates as data published will be available for subscription by all federates </li></ul>Runtime Infrastructure Federate a1 Federate a2 Federate b1 Federate b2
  13. 13. Data Shielding Architecture Hierarchical High Level Architecture Runtime Infrastructure A Runtime Infrastructure B Federate a1 Federate a2 Gateway Federate a Federate b1 Federate b2 Gateway Federate b RTI Gateway
  14. 14. Authentication Authentication Server DBMS Browser Web services Web services Web services Initiate Simulation Verify user Identity Invoke Federates (presented as Web Services)
  15. 15. Synchronization <ul><li>Among simulated systems </li></ul><ul><ul><li>synchronize simulation time of federates </li></ul></ul><ul><li>Between simulated systems and real systems </li></ul><ul><ul><li>synchronize simulation time and real time </li></ul></ul>
  16. 16. Among Simulated Systems
  17. 17. Among Simulated Systems F1 F2 Event list: 2 5 41 53 Event list: 6 9 27 39 Future Affect The Past! 41 9 27 28
  18. 18. Between Simulated and Real Systems S2 S1 Real System Simulated System Simulated System Case 1 t 3  t 2 : M2 can be processed at S2 once it is received M1 triggers M3 Case 2 t 3 < t 2 : S2 can only process M2 after it processes M3 M1 @ t 1 M2 @ t 2 M3 @ t 3
  19. 19. Simultaneous Scenarios Evaluation <ul><li>A running simulation is cloned dynamically at decision points in order to explore different execution paths </li></ul><ul><li>The advantages of cloning are: </li></ul><ul><ul><li>it avoids restarting the simulation for each alternative path </li></ul></ul><ul><ul><li>it improves efficiency by sharing common computations between alternative paths </li></ul></ul><ul><ul><li>alternative paths may be executed in parallel </li></ul></ul>
  20. 20. Cloning Architecture Run Time Infrastructure (RTI) Simulation Executive Cloning Layer Simulation Application Cloning Database RTIambassador FederateAmbassador
  21. 21. Cloning Mechanisms <ul><li>Replicate the entire simulation at a decision point </li></ul><ul><ul><li>This allows sharing of the computation before the decision point, but no sharing is possible after cloning </li></ul></ul><ul><li>Replicate the simulation incrementally </li></ul><ul><ul><li>This allows common computations to be shared before and after the decision point </li></ul></ul>
  22. 22. Interactive Control <ul><li>The Interactive Control will allow the user to: </li></ul><ul><ul><li>Insert decision points and new execution paths </li></ul></ul><ul><ul><li>Monitor the values of simulation variables </li></ul></ul><ul><ul><ul><li>this can be: on demand, sampled continuously, or when some condition is satisfied </li></ul></ul></ul><ul><ul><li>Modify the variables of the current execution path </li></ul></ul><ul><ul><li>Roll back to an earlier simulated time and re-execute from previous decision points </li></ul></ul><ul><ul><ul><li>this requires replicating the state at a decision point </li></ul></ul></ul><ul><ul><li>Prune an execution path when its results show the outcome is not a useful scenario to consider </li></ul></ul>
  23. 23. Fault Tolerance <ul><li>Cloning and Fault Tolerance </li></ul><ul><ul><li>Take advantage of cloning to provide fault tolerance in a distributed simulation </li></ul></ul><ul><ul><li>By saving the state at decision points, it is possible to roll back to a decision point in the event of failure </li></ul></ul><ul><ul><li>Migration of replicated clones and data to other machines is also possible </li></ul></ul><ul><ul><li>Redundancy can also be provided by executing the same path on different machines </li></ul></ul>
  24. 24. A Joint Project Gintic Institute of Manufacturing Technology School of Computer Engineering Nanyang Technological University
  25. 25. Semiconductor Supply Chain Model A&T Wafer Fab Warehouses Distribution Centers End Customers Information flow Material flow Business Center
  26. 26. Summary <ul><li>Compatible simulation models can be “plug-and-simulate” for supply chain optimization  reusability </li></ul><ul><li>No geographical barrier to implement collaborative supply chain optimization </li></ul><ul><li>Ability to shield companies’ sensitive data encourages collaborative supply chain optimization </li></ul><ul><li>Robustness of the technology is crucial to its adoption by the industry </li></ul>
  27. 27. Summary <ul><li>Simultaneous scenarios evaluation increases productivity of using a simulation as a tool for what-if analysis </li></ul>
  28. 28. Questions?
  29. 29. Project Team
  30. 30. Hierarchical High Level Architecture <ul><li>Selective data sharing/shielding </li></ul><ul><li>Scalable distributed simulation </li></ul><ul><li>Cross talking of different HLA implementations </li></ul><ul><li>Consideration of topological information in synchronization </li></ul>