Technology for the United States Navy and Marine Corps, 2000-2035: Becoming a 21st-Century Force Volume 9: Modeling and Simulation (1997) / Chapter Skim
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6 Creating and Improving Intellectual and Technoligical Infrastructure for M&S Key Technical Problems Requiring Investment
6 Creating and Improving Intellectual and Technoligical Infrastructure for M&S Key Technical Problems Requiring Investment
Pages 70-90
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From page 70... ...
HIERARCHICALLY INTEGRATED FAMILIES OF MODELS The first subject involves integrated families of models. (See also Appendix E.)
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From page 71... ...
Highresolution models, for example, often predicted attrition and movement rates that greatly exceeded observed reality presumably because they were not yet sufficiently complete to reflect many of the delays and other frictional effects that occur in real military operations.] Also, the high-resolution models often did not address key features of the problem.
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From page 72... ...
Returning to the attrition example, if we know from historical evidence (and common sense) that attrition is self-limiting because commanders will not tolerate excessive attrition, then someone building a high-resolution model may need to design in corresponding decision rules that could be calibrated against macroscopic information on behaviors (which might be different for different nations' commanders and forces)
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From page 73... ...
For other discussions of multiresolution modeling issues, see articles by Davis and Hillestad in the edited collection of the Military Operations Research Society (MORS) by Bracken et al.
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From page 74... ...
As a result, the high-resolution simulations focused on, for example, company- or battalion-level combat. The result was that the simulated battles occurred to some extent in a vacuum, without representing the lengthy, complicated preparations and maneuvers that typically precede the battles, much less the associated frictional complications.
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From page 75... ...
The RAND Strategy Assessment System (RSAS) of the late 1980s included theaterlevel and even political-level decision models employing a variety of methods that included adaptive scripts (akin to real-world branched war plans)
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From page 76... ...
' questions" by logic programming methods to embed knowledge that allows the simulation to find initial conditions sufficient to meet specified end states have been discussed and pursued by RAND's Jeff Rothenberg and colleagues (see Mattock et al., 1995~. Also, there may be a revival ahead of defense economics dependent less on simulations than on simpler spreadsheet-level models, cost data, and decision support tools.
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From page 77... ...
~ IT'S '' ~ ~ '~;77 Historically, there has been very little reuse of simulation components, and little interoperability among simulations, especially across simulation categories M&S INFRASTRUCTURE Rationale The next subject requiring major technical effort is infrastructure. The panel cannot do justice to this subject here (see also Appendix F)
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From page 78... ...
· The simulation layer, which executes venous models to generate the over Collaboration Layer _ Exploratory Analysis and Search Layer Scenario Layer _ Mo | Simulation Layer Network Layer l Computing Platform Layer l FIGURE 6.4 Layered architecture for M&S.
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From page 79... ...
HLA is concerned with simulation modularity, interoperability, and component reuse by means of a consistent conceptual approach, domain-independent infrastructure components, and a repository of previously developed simulation modules. All substantive representations of real-world phenomena are maintained inside the simulation components.
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From page 80... ...
, and it requires that every simulation that is a candidate for inclusion in a federation must maintain its own simulation object model using the OMT format. In essence, the process of forming a federation consists of a negotiation regarding the various simulation object models, resulting in decisions about which parts of the various simulation object models will be combined to form the overall federation object model.
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From page 81... ...
Although the HLA makes extensive use of object-oriented representations to describe the interactions among federates, it does not require that any federate use object-orient programming languages or representations internally. Finally, the HLA envisions that federates and their object models will be catalogued in resource repositories where they can be browsed and selected as candidates for reuse in new federations.
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From page 82... ...
The architecture is inherently broader and more flexible than the distributed interactive simulation (DIS) standards, where many of the advocates of simulation interoperability have historically congregated.
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From page 83... ...
The commonly used BASIC language with its interactiveness and relatively simple syntax has long been popular for programming by nonexperts. A variety of specialized high-level languages have proved quite powerful to students in science and engineering and to professionals.ll 1lExamples here include SIMSCRIPT_ and MODSIM_ simulation languages, the systems dynamics language iThink_, and, much less well known, the RAND-ABEL language_ used to develop the RAND Strategy Assessment System.
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From page 84... ...
This might be done by e-mail, video conferencing phone calls, or a broadcast query to the relevant subset of Web users. Making complex models comprehensible remains a frontier challenge, and many workers have labored valiantly only to produce simulations understandable only to themselves.
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From page 85... ...
One indication of this is the growing interest in industry-developed methodologies and tools for object-oriented modeling, not just object-oriented programming.~2 Some of these tools are now being used in the JWARS program, for example. They are especially significant because building "explanation capabilities" often depends critically on the clarity and structure of the underlying model design.
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From page 86... ...
. In fact, the visionary technical infrastructure being promoted by OSD's Defense Modeling and Simulation Office (DMSO)
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From page 87... ...
. · Explanation capabilities linking simulated behavior to situations, parameter values, rules and algorithms, and underlying conceptual models.
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From page 88... ...
This said, even analysts often find themselves using more cumbersome models than are truly suitable for their purposes. For example, they may use a complex campaign model to examine tradeoffs among deep-strike weapon systems being assessed for their ability to halt advancing armies.
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From page 89... ...
These programs should be organized so as to assure close ties to operational and doctrinal-development communities, and to relevant training and exercise efforts that could be mined as a source of empirical knowledge (e.g., as suggested in Figure 6.5, which would exploit emerging capabilities for distributed interactive simulation) .~4 This is a nontrivial and potentially controversial suggestion, since the long-standing tradition has been to avoid and even prohibit extensive data collection for use beyond those being trained.
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From page 90... ...
It is plausible, for example, that cellularautomata models could help illuminate behaviors of dispersed forces with varying command-control concepts ranging from centralized top-down control to decentralized control based on mission orders. To its great credit, the Marine Corps is currently exploring such possibilities, opting to accept some "hype and smoke" in the realm of controversial complex-system research in exchange for new perspectives and tools useful in doctrinal innovation.
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