Current Status of NSA-DEVS

• Basic achievements:
  • definition of an abstract simulator
  • formal analysis and implementation of several standard examples
  • implementation of a real-world application
    • production line with several furnaces, lathes and grinders
    • 391 atomic, 88 coupled models, 5 hierarchical levels
• Tools:
  • graphical builder for coupled models
  • library of atomics containing
    • sources and sinks
    • math operations
    • logic operations and flipflops
    • QSS-based integrator
    • routing components
    • logistics components (e.g. queue, server)
    • statistical computations
• Handling of delays:
  • default values defined in library
    • input delays τ are set to τ_def = ε
    • infinitesimal transition delays τ_D are set to ε generally
    • τ_D = 2ε for components emiting output trains (e.g. queue, combine)
  • practical considerations
    • τ, τ_D may have to be adapted in complex models (1 of 479 in production line example)
    • delays can be used to enforce a special ordering of events
    • components for global output have large (small) delays to hide (show) infinitesimal changes