Robert W. Franceschini

Fidelity evaluation framework

While the modeling and simulation community commonly uses the word fidelity, there exists no clearly accepted definition or method of measuring fidelity. We make the following contributions. We present a new approach for measuring fidelity: the fidelity evaluation framework (FEF), that uses a referent, or a formal representation of reality that is intermediate between reality and the simulation. This foundation is advantageous because isolates subjectivity from the fidelity evaluation to well-defined framework components: development of the referent and assignment of weights to different referent components. We then provide the first example of the composition of a detailed referent and two models based on a real-world system with the FEF. We propose and illustrate three new methods of computing fidelity objectively within the FEF: category-based, model-based, and weight-based. This experiment proved that the FEF can provide meaningful and useful measurements of fidelity.

Considerations for selective-fidelity simulation

The concept of fidelity in a simulation model has become one of great contention among simulation researchers. While there is some agreement regarding the definition of fidelity in a model, there appears to be little accord about how the fidelity of a model might be measured - or even whether it is measurable at all. Because of the abstract nature of both reality and the representations of reality used for simulation systems, some argue that fidelity is also abstract in nature and can not be measured. Research conducted at IST, however, has yielded a method not only for measuring fidelity in a model, but also comparing the fidelity of different models to be used in a simulation. This ability to compare the fidelity of different models can be used in a practical manner to decide which models would be most appropriate for a new application. Further research at IST has explored the idea of using this ability to compare the fidelity of models to give a simulation system the ability to select the models that it should use based on outside factors such as the computational load on the system. This concept is called Selective-Fidelity Simulation, and is documented in this paper.

A multi threaded and resolution approach to simulated futures evaluation

As part of the DARPA Deep Green efforts, SAIC developed a multi-threaded and resolution approach to constructing and evaluating simulated futures to address the SimPath component. By making use of heuristically derived breakpoints in a provided plan, we can construct a series of possible futures that are grouped into what is referred to as the probabilistic fluent graph (PFG). Evaluation of the PFG is done through a multiple resolution and fidelity modeling system that applies computational resources to the areas of highest likelihood. In this paper, we describe the architecture, processing, and data structures needed to bring this concept to fruition.

Novel Hardware-Software Architecture for the Recursive Merge Filtering Algorithm

As reconfigurable devices move to the forefront of mainstream processing, the spectrum of application areas for such devices is also increasing. One such area is image processing. In this paper we present a novel hardware-software codesign architecture for the computation of the Discrete Wavelet Transform (DWT), based on a new Recursive Merge Filtering (RMF) algorithm. The architecture aims at reducing the overall data routing during the computation of the DWT. The method shows how data routing can be transformed into a series of index computations carried out on the reconfigurable device. The architecture applies hardware/software codesign principles for task division among the available processing resources and uses memory resources closer to the FPGA to avoid the main memory accesses and this reduces the processing time and access time. The paper also proposes ideas based on memory bank to further enhance the performance of the proposed architecture. The architecture is based on a dynamically reconfigurable device, the Xilinx XC6200 on the H.O.T Works Board used to carry out the data routing by a series of index computations. The complex computations are restricted to the main processor and the simple addition/subtraction tasks for data routing are based on the FPGA.

Status report on the integrated Eagle/BDS-D project

This paper reports the status of the Integrated Eagle/BDS-D project which is investigating the interoperation of constructive combat models and virtual battlefield simulations within a distributed interactive simulation framework. The network architecture, network protocol, system architecture, and computer software are described. The processes of disaggregation, aggregation, and pseudo-disaggregation are described. Finally, an overview of the demonstration of this system at the AirNet training facility in Ft. Rucker Alabama is provided.

Linking constructive and virtual simulation in distributed interactive simulation (DIS)

Existing Distributed Interactive Simulation (DIS) systems (which are a class of virtual simulations) are limited by computational power and network bandwidth in the number of vehicle platforms that can take part in a single battlefield simulation. One way to improve this limit is to integrate an aggregate constructive wargame into the DIS simulation; the constructive wargame supplies the context for a large-scale battle without adding significant computational load to the network. A critical idea in such an integration is that the events in the constructive simulation influence the events in the virtual battlefield and vice versa; this maintains the unity of the entire battlefield simulation. This paper is a tutorial on the problem of integrating constructive and virtual simulations. It describes constructive and virtual simulations, discusses motivations for integrating such simulations, and addresses general problems that must be solved by any constructive and virtual integration.