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This paper compares the convergence behavior of two popular iterative methods for solving systems of linear equations: the s-step restarted minimal residual method (commonly implemented by algorithms such as GMRES(s)), and (s?1)-degree polynomial preconditioning. It is known that for normal matrices, and in particular for symmetric positive deenite(More)
New parallel computers are emerging, but developing efficient scientific code for them remains difficult. A scientist must manage not only the science-domain complexity but also the performance-optimization complexity. HERCULES is a code transformation system designed to help the scientist to separate the two concerns, which improves code maintenance, and(More)
A synthetic medium containing 9 g/l sucrose was hydrolyzed in a novel hybrid reactor. A minimum hydraulic retention time (HRT) of 9.9 h, with a gas production rate of 1.07 m3/m3·d, was obtained without continuous neutralization. A viable anaerobic cell count of 109 organisms/ml was obtained in the reactor fluid. The results showed that both pH and(More)
Fifty-two aerobic and facultative anaerobic and 57 anaerobic bacterial isolates were obtained from an acidogenic phase digestion system. These isolates were characterized and the similarities between the different strains were calculated using Sokal and Michener's similarity coefficient. The aerobic and facultative anaerobic strains clustered in two major(More)
The solution of nonsymmetric systems of linear equations continues to be a diicult problem. A main algorithm for solving nonsymmetric problems is restarted GMRES. The algorithm is based on restarting full GMRES every s iterations, for some integer s>0. This paper considers the impact of the restart frequency s on the convergence and work requirements of the(More)
We present simulations of blood and cancer cell separation in complex microfluidic channels with subcellular resolution, demonstrating unprecedented time to solution, performing at 65.5% of the available 39.4 PetaInstructions/s in the 18, 688 nodes of the Titan supercomputer. These simulations outperform by one to three orders of magnitude the current(More)