Joseph E. Flaherty

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This thesisinvestigatesthe mappingproblem: assignthe tasksof a parallel program to the processorsof a parallel computer suchthat the execution time is minimized. First, a taxonomy of objective functions and heuristics usedto solvethe mapping problem is presented. Next, we develop a highly parallel heuristic mapping algorithm, called Cyclic Pairwise Exchange(More)
We analyze the spatial discretization errors associated with solutions of onedimensional hyperbolic conservation laws by discontinuous Galerkin methods in space. We show that the leading term of the spatial discretization error with piecewise polynomial approximations of degree p is proportional to a Radau polynomial of degree p+1 on each element. We also(More)
Abstract: We construct parallel finite element methods for the solution of hyperbolic conservation laws in one and two dimensions. Spatial discretization is performed by a discontinuous Galerkin finite element method using a basis of piecewise Legendre polynomials. Temporal discretization utilizes a Runge-Kutta method. Dissipative fluxes and projection(More)
Data partitioning and load balancing are important components of parallel computations. Many different partitioning strategies have been developed, with great effectiveness in parallel applications. But the load-balancing problem is not yet solved completely; new applications and architectures require new partitioning features. Existing algorithms must be(More)
The Zoltan dynamic load balancing library provides applications with a reusable object oriented interface to several load balancing techniques, including coordinate bisection, octree/space filling curve methods, and multilevel graph partitioners. We describe enhancements to Zoltan’s octree load balancing procedure and its distributed structures that improve(More)
Software tools for the solution of partial diierential equations using parallel adaptive nite element methods have been developed. We describe the design and implementation of the parallel mesh structures within an adaptive framework. The most fundamental concept is that of a hierarchical partition model used to distribute nite element meshes and associated(More)
Babu ska and Yu constructed a posteriori estimates for nite element dis-cretization errors of linear elliptic problems utilizing a dichotomy principal stating that the errors of odd-order approximations arise near element edges as mesh spacing decreases while those of even-order approximations arise in element interiors. We construct similar a posteriori(More)
A greater understanding of the rate at which emerging disease advances spatially has both ecological and applied significance. Analyzing the spread of vector-borne disease can be relatively complex when the vector's acquisition of a pathogen and subsequent transmission to a host occur in different life stages. A contemporary example is Lyme disease. A(More)
Fusarium verticillioides, a pathogen of maize, produces a class of mycotoxins called fumonisins in infected kernels. In this study, a candidate regulatory gene, ZFR1, was identified in an expressed sequence tag library enriched for transcripts expressed by F. verticillioides during fumonisin B(1) (FB(1)) biosynthesis. ZFR1 deletion mutants exhibited normal(More)