Introduction
- Discrete-event modeling:
- many commercial modeling/simulation environments
available
- wide range of components
- helpful tools
- model behaviour sometimes unexpected
- documentation not sufficient
- behaviour of components not defined
completely
- precise definitions are essential
- DEVS formalisms:
- precise mathematical description of Discrete-EVent
Systems
- single components (atomic models)
- hierarchical system of components (coupled
models)
- exact behaviour of models (simulator)
- PDEVS (Parallel DEVS)
- widely used
- has problems with reusable Mealy components
- RPDEVS (Revised PDEVS)
- direct description of Mealy components
- has problems with chains of concurrent
events
- NSA-DEVS (Non-Standard Analysis DEVS)
- uses Mealy description from RPDEVS
- adds infinitesimal delays to cope with
concurrent events
- has shown to work in many examples
- free Matlab implementation of simulator and
component library