Michael E. Goldsby

Simulation analysis of virtual geographic routing

Homeland defense applications will use large-scale ad-hoc networks of small devices. Routing is a crucial problem, for naive means do not scale well. Geographic routing (GR) (Karp 2000; Giordano, Stojmenovic, and Blazevic 2003) offers hope for scalability, under the assumption that every device knows its geographic coordinates, e.g., through GPS. This solution is unsuitable though when there is no easy means of establishing a devices physical location, indoors. To address this limitation we propose virtual geographic routing where we construct a virtual coordinate space and use GR within it. This paper describes VGR, compares the characteristics of paths VGR identifies with those that GR identifies, then presents theoretical and empirical evidence for its scalability.

A geographically distributed enterprise simulation system

Abstract Sandia National Laboratories has the role of system integrator in the US Department of Energy’s Nuclear Weapons Complex (NWC) and the responsibility for maintaining the nuclear stockpile. Maintenance is a complex task that involves a great number of geographically distributed functions, and a variety of analysis tools and models are used to plan operations, assess capabilities and guide political decisions. We are developing a framework for modeling the NWC unde interactive human control. The framework consists of a simulation system whose users and components are distributed across the entire United States. The purpose of the system is to support decisions about questions ranging from low-level operational matters involving only a sub-component of the complex to high-level policy issues requiring simulation of the entire complex. The system integrates multiple domain-specific legacy models and policy models and allows simulation at varying levels of detail. To provide such a framework, we have had to address a number of technical problems, whose solution is the focus of this paper. The three most fundamental problems are • to provide geographically distributed, synchronized human participation in the simulation; • to provide distributed ownership and security in such a way that the facility hosting a domain-specific model retains all rights to provide or deny a user access to its information; and • to integrate legacy models written in a variety of tools or languages and executed on different platforms. Key features of our approach are the use of the Java language and the coordination of the simulation through a new parallel discrete-event simulation system.

Multithreaded agent-based simulation

Multithreading can significantly increase the performance of large agent-based simulations on multicore systems, but agent-based software packages do not commonly offer adequate support for multithreading. This report describes alterations and additions made to the MASON agent-based simulation package that allow the application programmer to make use of multiple threads easily and without radical change to conventional agent-based programming style. The report confirms performance gains with the results of test runs.

Performance modeling of the IDES framework

The IDES project at Sandia National Laboratories is developing a large scale portable parallel simulator for use in stockpile stewardship. IDES will use the Breathing-Time-Buckets synchronization protocol; to support IDES development, this paper studies a performance model and describes performance experiments on expected work load and architectural parameters. A new parallel algorithm for terminating the window quickly is also described and analyzed.

Integrating software architectures for distributed simulations and simulation analysis communities.

The one-year Software Architecture LDRD (No.79819) was a cross-site effort between Sandia California and Sandia New Mexico. The purpose of this research was to further develop and demonstrate integrating software architecture frameworks for distributed simulation and distributed collaboration in the homeland security domain. The integrated frameworks were initially developed through the Weapons of Mass Destruction Decision Analysis Center (WMD-DAC), sited at SNL/CA, and the National Infrastructure Simulation & Analysis Center (NISAC), sited at SNL/NM. The primary deliverable was a demonstration of both a federation of distributed simulations and a federation of distributed collaborative simulation analysis communities in the context of the same integrated scenario, which was the release of smallpox in San Diego, California. To our knowledge this was the first time such a combination of federations under a single scenario has ever been demonstrated. A secondary deliverable was the creation of the standalone GroupMeld{trademark} collaboration client, which uses the GroupMeld{trademark} synchronous collaboration framework. In addition, a small pilot experiment that used both integrating frameworks allowed a greater range of crisis management options to be performed and evaluated than would have been possible without the use of the frameworks.

Smallpox over San Diego: Joint Real-Time Federations of Distributed Simulations and Simulation Users under a Common Scenario

A joint project between the California and New Mexico branches of Sandia National Laboratories has demonstrated the formation of joint real-time federations of both distributed simulations and distributed simulation users under a common scenario. Two software integration frameworks were used to achieve the real-time federations. The IDSim framework, developed by Georgia Tech University and Sandia National Laboratories, was used to create the real-time federation of distributed simulations, in this case the BioDAC WMD simulation and the N-ABLEtrade agent-based microeconomic simulation (more properly, because of the impact of hurricanes Katrina and Rita, an N-ABLEtrade emulator). The GroupMeldtrade multimedia synchronous collaboration framework, developed by Sandia, was used to create the real-time federation of simulation users and simulation analysis communities. The common scenario was the release of smallpox over San Diego, California, and the operating hypothesis was that the economy itself dampens the spread of a pathogen. In addition, a small pilot experiment using the joint federations allowed a greater range of crisis management options to be performed and evaluated than would have been possible without the use of the integration frameworks.

Robust message routing for mobile (wireless) ad hoc networks.

This report describes the results of research targeting improvements in the robustness of message transport in wireless ad hoc networks. The first section of the report provides an analysis of throughput and latency in the wireless medium access control (MAC) layer and relates the analysis to the commonly used 802.11 protocol. The second section describes enhancements made to several existing models of wireless MAC and ad hoc routing protocols; the models were used in support of the work described in the following section. The third section of the report presents a lightweight transport layer protocol that is superior to TCP for use in wireless networks. In addition, it introduces techniques that improve the performance of any ad hoc source routing protocol. The fourth section presents a novel, highly scalable ad hoc routing protocol that is based on geographic principles but requires no localization hardware.

Macro-System Model for Hydrogen Energy Systems Analysis in Transportation

The introduction of hydrogen as an energy carrier for light-duty vehicles involves concomitant technological development of an array of infrastructure elements, such as production, delivery, and dispensing, all associated with energy consumption and emission levels. To analyze these at a system level, the suite of corresponding models developed by the United States Department of Energy and involving several national laboratories is combined in one macro-system model (MSM). The MSM uses a federated simulation framework for consistent data transfer between the component models. The framework is built to suit cross-model as well as cross-platform data exchange and involves features of “over-the-net” computation. While the MSM can address numerous hydrogen systems analysis aspects, of particular interest is the optimal deployment scenario. Depending on user-defined geographic location and hydrogen demand curve parameters, the cost-optimal succession of production/delivery/dispensing pathways undergo significant changes (the most important of these being the transition between distributed and central H2 production with delivery). Some ‘tipping’ (break-even) points are identified.Copyright

Macro-system model: a federated object model for cross-cutting analysis of hydrogen production, delivery, consumption and associated emissions

The introduction of hydrogen as an energy carrier for light-duty vehicles involves concomitant technological progress in several directions, such as production, delivery, consumption and related emissions. To analyze each of these, a suite of corresponding models have been developed by the DOE, involving inputs from several national laboratories. The macro-system model is being developed as a cross-cutting analysis tool which combines a set of hydrogen technology analysis models. Within the macro-system model (MSM), federated simulation framework is used for consistent data transfer between the component models. The framework is built to suit cross-model as well as cross-platform data exchange and will involve features of ‘over-the-net’ computation.