Article by: Bernie Zeigler (zeigler@ece.arizona.edu )
While widely applied, existing modeling and simulation (M&S) tools are, in the main, oriented toward particular applications and fail to bridge complex multidisciplinary problems. A primary goal of the recently approved Arizona Center for Integrative Modeling and Simulation (ACIMS) is to advance the integrative capability of so that it can make the enormous computing power on the horizon applicable to emerging problems requiring multidisciplinary solutions. For example, research in Information Technology, and specifically in eCommerce and network-Centric warfare, must focus on the integrated design and implementation of hardware and software at all levels of technology and application. M&S is fast becoming the primary approach to provide the virtual environments in which such systems can be developed and tested before actually being cast into silicon chips or program code. However, in order for this potential to be brought to full realization, ACIMS believes that major advances in the theory and methodology of M&S are needed. A second goal of ACIMS is to widely disseminate the fruits of its research and to deepen the pool of trained M&S professionals. It will seek to develop new approaches to education and training in the fundamental concepts and computer tools at all educational levels including retraining of workers.
A quarter of a century has elapsed since the first efforts were undertaken to establish a system-theory based framework for M&S to help bring some coherence and unity to the field. The intervening period has seen many advances in the field, but the need for a widely accepted framework and theoretical foundation is even more necessary today. As a consequence of the growing specialization of knowledge there is even more fragmentation in the field now than ever. This is not to deny significant progress in the technology dimension. Development of simulations and their executions have been made easier and faster by riding piggyback on the technology advances in software and hardware. However, fundamental issues such as model credibility (e.g., validation, verification and model family consistency) and interoperation (e.g., repositories, reuse of components, and resolution matching) have received much less attention. These issues moved to the front and center for the defense community under the impetus of the High Level Architecture (HLA) standard and the Federation Development and Execution Process (FEDEP).
In response to these imperatives, ACIMS will develop a focused program of research and education that interweaves both basic cross-cutting and applied domain-specific elements.
Some areas of basic research in which ACIMS will focus include:
- Modeling Abstractions and Their Interrelationships. Mathematical systems theory provides two main, and orthogonal, aspects: Levels of system specification are the levels at which we can describe how systems behave and the mechanisms that make them work the way they do. Systems specification formalisms are the types of modeling styles, such continuous or discrete, that modelers can use to build system models. The DEVS (Discrete Event Systems Specification) is an increasingly accepted formalism to develop simulation models that are execution efficient, are amenable to syntactic and semantic analysis, and can accurately represent traditional continuous and discrete time models.
- Simulation Model Ownership. Intellectual properties including simulation models are increasingly being treated as commodities worthy of protection. Formal “model ownership” concepts and their corresponding realizations are necessary for enabling model reusability, composability, and distributed simulation throughout the lifetime of simulation models. Model ownership transcends existing capabilities such as the HLA ownership management services which recognizes the importance of data ownership and supports, for example, the mechanics to ensure only one simulation model is allowed to publish data at any given time. Having in place well-grounded model ownership concepts and methods within a generic modeling environment, we can get a step closer to overcoming one of the major impediments facing collaborative model development and distributed simulation execution.
- DEVS Standardization. DEVS is a prime candidate to provide the simulation model representation standard for Simulation Based Acquisition of the future. As a mathematical formalism with well defined concepts of coupling of components, hierarchical, modular construction, DEVS offers a sound basis for interoperable simulation model development that is, in principle, independent of various programming languages and hardware platforms. However while, implementations of DEVS agree on the underlying mathematical formalism they are not necessarily interoperable due to different computer representations. The objective of DEVS standardization is to develop a computer processable representation that supports common understanding, sharing and interoperability of DEVS implementations. Computer processable forms include all forms of simulation and real-time execution as well as various forms of syntactic and semantic analysis. The relation to other applicable standards such as HLA, CORBA and XML will be considered as well as the simulation interoperability of DEVS with non-DEVS simulations.
These areas will be woven together as needed to support application domain challenges such as - Next Generation VHDL. Hardware description languages are indispensable for computer and digital design, currently representing a total industry and defense investment of over $1B. However, restriction to digital abstractions threaten the future viability of computer design involving mixed analog and digital processing needed in silicon chips that promise to fuel the explosive growth in wireless devices and in vehicle electronics. Such a next-generation VHDL will be based on a new, fundamental principle – the accuracy of the analog subsystem representation is preserved by mapping such components into a uniform digital framework using the recently developed DEVS-based formal methods for efficient, accurate continuous system representation.
- Collaborative Co-Design of Distributed Computing Systems: Increasingly, due to constraints such as time to market, cost, performance, and maintenance, it has become necessary to consider distributed system design not purely from separate software or hardware perspective. Instead a co-design framework is needed in which to gain a unified perspective on network hardware (routers, switches), middleware (CORBA-like services) and application object-oriented software. With continued growth in distributed systems, and increased reliance on end-to-end use of simulation models, providing collaborative distributed co-design capabilities is one key to the realization of Simulation-Based Acquisition. Distributed interactive mission training systems is an example area which can potentially benefit from a M&S framework capable of representing simultaneously continuous and discrete dynamics, along with the communication and computational environment, to enable the required high performance, security and reliability.
- Emerging distributed, networked organizations (business, military, academic, etc) are continually executing multiple M&S-based decision processes at various strategic, tactical and operational levels. The phases and associated data needs for such M&S-based decision processes give us criteria for what data is needed, timeliness requirements and their level of resolution. We can use our understanding of M&S-based time-situated decision processes to develop design approaches to scalable network infrastructures that assure that the right information reaches the right decision makers at the right times.
In the educational area, ACIMS will participate in the current initiatives to make M&S into a recognized discipline. These include efforts to formulate requirements for certification of M&S professionals, develop course and programs for undergraduate and graduate degrees in M&S, and delivery of continuing education for M&S professionals through seminars and tutorials (e.g., the tutorial on the DEVS model/simulation composition framework at the upcoming SIW.)
The Center’s budget will be derived from research grants and contracts, training programs, as well as the participation of government and industrial partners. A joint research and education alliance between the UA and the U.S. Army Information Systems Engineering Command, Ft. Huachuca, AZ, will provide a funding base for the first five years. Other government, industry, and Department of Defense modeling and simulation research program are currently in place.
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