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Models come in many forms … - Building blueprint
- Virtual patient
- Artificial chess player
- Inductor specification
- Weather forecast
- Word processor reference manual
- Engine control strategy
- Sustainable development (e.g., Phoenix, AZ)
- Software Modeling (e.g, Unified Modeling Language)
- System Modeling (e.g., continuous and discrete time models)
Models exist for “anything” you can think of
A Definition of Model
“ A Model (M) for a system (S) and an Experiment (E) is anything to which E can be applied in order to answer questions about S ”, from M. Minsky, “Models, Minds, and Machines,” Proceedings of IFIP Congress, pp. 45-49, 1965.
- discrete time
- discrete event
- continuous
M&S Interoperability, Composability & Performance
- Fundamental Premise
- Modeling & Simulation are two distinct, yet complementary, activities. They provide the basis for building distributed simulation models.
- computation
- communication
- among multiple simulations
- both computational and communication efficiency issues underlie performance
Some Taxonomies of Model Types
Taxonomy I
Defense Modeling and Simulation Organization
http://www.dmso.mil
Taxonomy II
- Conceptual
- Declarative
- Functional
- Constraint
- Spatial
P. Fishwick, Simulation Model Design and Execution: Building Digital Worlds, 1995
- Live simulation: a simulation involving real people operating real systems
- Virtual simulation: a simulation involving real people operating simulated systems
- Constructive simulation: a simulation involving simulated people operating simulated systems
See https://learn.dau.mil/html/clc/Clc.jsp , CLE023
Taxonomy II
- Conceptual: defines a system at a very high level of abstraction
- Declarative: defines a system as a collection of states and their subsequent changes
- Functional: defines a system in terms of its functions and ways in which outputs are generated for some given input stimuli
- Constraint: defines a system as a set of states and their relationships in a constraint network
- Spatial: defines a system in terms of its geometry
- Multi-modeling: models that are composed of other models
Taxonomy II
- Conceptual
- Declarative
- Functional
- Constraint
- Spatial
Taxonomy III
- Source
- Data
- Generative
- Structure
G. Klir, 1985, Architecture of Systems Problem Solving, 1985
Taxonomy IV
- Observation
- I/O relation
- I/O function
- I/O system
- Coupled system
I/O: input/output
B. Zeigler, H. Praehofer, T. Kim, 2000 (ref. Textbook)
Taxonomy III- Source System: what variables to measure and how to observe them
- Data: data collected from a source system
- Generative: means to generate data in a data system
- Structure: components (at lower level) connected together to form a generative system
Taxonomy IV - I/O observation: inputs and outputs are observed over some period of time (trajectories)
- I/O relation: pairs of inputs and outputs matched one-to-one over some period of time
- I/O function: Each pair of input/output has an associated initial state
- I/O system: output trajectories are determined based on states alone or states and input trajectories.
- Coupled system: output trajectories are generated from interacting I/O systems and lower level coupled systems.
Simulation Based Acquisition
The High Level Architecture
Architecture calls for a federation of simulations (federates)
- High Level Architecture (HLA) specifies
- Ten Rules which define relationships among federation components
- An Object Model Template (OMT) which specifies the form in which simulation elements are described
- FOM – federation object model
- SOM – simulation object model
- An Interface Specification (IF) which describes the way simulations interact during operation
**
RTI must support the Rules, OMT and IF specifications
M&S Interoperability, Composability & Performance
- Fundamental Premise
- Modeling & Simulation are two distinct, yet complementary, activities. They provide the basis for building distributed simulation models.
- computation
- communication
- among multiple simulations
- both computational and communication efficiency issues underlie performance
- Interoperability:
- generic dynamic computer-based and non-computer-based systems
- support a wide range of models and simulations
- hierarchical construction
- Well-defined functionality & interfacing
- Real-time interoperability
- Support design, testing and operational needs
- Composability:
- synthesis of a collection of existing or new sub-systems in such a way that the resultant system behavior is the aggregation of sub-behaviors
- support a wide range of models and simulations
- Reuse
- model and simulation reuse
- centralized and distributed data and model repositories
