James F. Leathrum

Verification of IEEE Compliant Subtractive Division Algorithms

A parameterized definition of subtractive floating point division algorithms is presented and verified using PVS. The general algorithm is proven to satisfy a formal definition of an IEEE standard for floating point arithmetic. The utility of the general specification is illustrated using a number of different instances of the general algorithm.

Scalable implementations of multipole-accelerated algorithms for molecular dynamics

We consider efficient, scalable solutions to the long-range force computation problem in molecular dynamics (MD) simulation. Straightforward implementation of a solver for the time-consuming Coulomb force yields O(N/sup 2/) runtime for N atoms in a system; this quadratic complexity limits the size of systems that can be simulated. Exclusion of interactions beyond a certain cutoff radius reduces runtime but also negatively impacts simulation accuracy. By using algorithms based on the multipole expansion of the potential due to groups of charged particles, the work permits high-accuracy simulations which include all pair interactions (i.e. no truncation) at a runtime cost which grows linearly with the size of the system. The algorithms are parallelizable on a range of platforms; we concentrate on the Kendall Square KSR-1. We present results from four variants of the multipole-accelerated algorithms on systems of up to a million particles on up to 32 processors.<<ETX>>

An Object-Oriented Architecture for the Simulation of Networks of Cargo Terminal Operations:

A new object-oriented architecture to simulate a network of cargo terminals is presented. The architecture simulates the complete flow of military cargo at an entity level, from multiple U.S.-based installations to a set of destinations within a theater of operations located anywhere in the world. The architecture deals with resource and infrastructure allocations and competition within each terminal in the network, as well as between the terminals, to identify conflicts that may arise. The architecture is a hierarchical, nodal model moving individual pieces of cargo through a network of cargo terminals, and within an individual cargo terminal through a network of physical processing areas. The architecture is capable of simulating cargo terminals around the world under various scenario conditions. It is impractical and expensive to conduct actual exercises to study the efficiency of a deployment. Simulating this process provides a viable alternative for testing these strategies and for evaluating technologies. It also enables an analysis of the simulation results for improved efficiency and throughput within the confines of resources and infrastructure availability. The new architecture is described as well as an example case study to demonstrate the capabilities of the architecture. The architecture focuses on resources and infrastructure within a cargo terminal, and on transportation resources between cargo terminals.

Question model for intelligent questioning systems in engineering education

This paper describes the development of a question model to be used with an intelligent questioning system. The purpose of the intelligent questioning system is to improve the educational process in engineering courses by allowing students to learn more in less time, to understand more deeply, and to enjoy their learning experience. Key elements of this system are a question model and an adaptive question management system that uses a hierarchical knowledge map to direct the learning process based on the students degree of understanding of individual or grouped concepts. Although there are several online computer-based questioning systems, they typically have no built-in help, no guidance if questions are answered incorrectly, no method for selecting questions based on the students needs, and no comprehensive monitoring of a students progress through a knowledge map not only of the course but also of the curriculum.

Modeling and simulation techniques for maritime security

Generalized techniques for modeling and simulating maritime security measures at cargo seaports are presented. The security problem is first partitioned into proactive and reactive approaches. Proactive approaches attempt to avoid disruptive events through security measures such as cargo inspection. Reactive approaches react to disruptive events, including cleanup and operational recovery. Two modeling techniques, programmatic process flows and programmatic events are presented and applied to the Port Simulation Model (PORTSIM). Programmatic process flows support rapid development of alternative processes for modeling port activities, allowing easy introduction of new processes such as container inspections. Programmatic events support injecting the behavior of disruptive events by modifying available port infrastructure, resources, and process times to reflect the result of an event and the recovery process. The application of these approaches is demonstrated using PORTSIM applied to two hypothetical studies. First, a proactive study is presented studying the operational and economic impact of various levels of container inspection. Second, a reactive study is presented evaluating the relative impact of a disruption to berthing and staging activities.

A simulation architecture to support intratheater sealift operations

A new architecture for simulating intratheater sealift operations is presented. Intratheater sealift operations refer to new strategies proposed for quickly deploying a military force to a theater of war when major seaports are not available. In this strategy, a self-deployable force is transported to a sea-based intermediate staging base (SISB) by conventional cargo transport ships. The SISB is a world-class seaport generally located within 800 miles of the theater of war. At the SISB, cargo is transferred to a new ship platform called the theater support vessel (TSV). TSVs are to be designed to access very small ports located at or near the theater of war. Simulation provides an efficient and cost-effective method for testing these strategies and for evaluating the required new logistics technologies. Should intratheater sealift operations prove viable, the simulation also provides a means to plan and rehearse an exercise. The new simulation architecture is described and example simulation case studies are conducted to demonstrate the capabilities and potential benefits of the approach.

Modeling the impact of security and disaster response on cargo operations

While significant effort has been expended on the analysis of new security technologies and policies at ports of entry, the effort has focused on the effectiveness of the security, not on the impact of security on commercial operations. This paper addresses the requirements to model the impact of security measures on port operations, using an existing port simulation. The goal of the simulation is to assess different strategies from an economic viewpoint. To contrast different strategies, we need to be able to rapidly prototype the strategies in an existing operational model. Both proactive and reactive security measures are addressed, as well as responses to natural disasters. The modeling techniques required to rapidly incorporate new security strategies into the simulation are identified. Then these capabilities are demonstrated using the Port Simulation (PORTSIM) tool.

A successful EAC-ABET accredited undergraduate program in modeling and simulation engineering (M&SE)

The first undergraduate degree program in modeling and simulation engineering recently was implemented at Old Dominion University. The program awards the Bachelor of Science Degree in Modeling and Simulation Engineering and was designed to meet the ABET accreditation requirements for general engineering programs. This paper describes the design and implementation of a continuous improvement process for the program. The department mission statement and the program educational objectives are presented. The student outcomes are stated and an assessment process for evaluating student achievement is described. Finally, the continuous improvement process for the program is presented. Recommendations from the initial ABET accreditation visit are summarized.

A multi-use architecture for technology-based delivery of curricula

This paper describes the approach taken to prepare Old Dominion Universitys undergraduate computer engineering curriculum for technology based delivery. Old Dominion University is one of the largest deliverers of engineering technology undergraduate programs via its TELETECHNET delivery system. Based on the positive experiences gained, it will now begin preparations for the delivery of undergraduate engineering programs. The approach is based on the concept that technology can be used not only for the delivery of instruction, but also for delivering student learning. To accomplish this, the curriculum content must be organized into learning modules. Learning modules are defined as the smallest elements of material that, if broken down further, would lose meaning. Each module is characterized by attributes. These include the following: (1) a specific precedence relationship with every other module in the curriculum; and (2) specific learning results associated with each.

Modelling heterogeneous processor scheduling for real-time systems

Abstract A new model is presented to describe data-flow algorithms implemented in a multiprocessing system. Called the resource/data flow graph (RDFG), the model explicitly represents cyclo-static processor schedules as circuits of processor arcs that reflect the order that processors execute graph nodes. The model also allows the guarantee of meeting hard real-time deadlines. When unfolded, the model identifies statistically the processor schedule. The model therefore is useful for determining the throughput and latency of systems with heterogeneous processors. The applicability of the model is demonstrated using a space surveillance algorithm.