A Cray T3D performance study

We carry out a performance study using the Cray T3D parallel supercomputer to illustrate some important features of this machine. Timing experiments show the speed of various basic operations while more complicated operations give some measure of its parallel performance

Conference on iterative methods for large linear systems

This conference is dedicated to providing an overview of the state of the art in the use of iterative methods for solving sparse linear systems with an eye to contributions of the past, present and future. The emphasis is on identifying current and future research directions in the mainstream of modern scientific computing. Recently, the use of iterative methods for solving linear systems has experienced a resurgence of activity as scientists attach extremely complicated three-dimensional problems using vector and parallel supercomputers. Many research advances in the development of iterative methods for high-speed computers over the past forty years are reviewed, as well as focusing on current research

Stationary second-degree iterative methods and recurrences

The basic theory of stationary second-degree iterative methods is presented from the point of view of recurrences. Recurrences are encountered in the development of expressions for the spectral radii and for various norms associated with linear stationary iterative methods. We show that many of these recurrences are special cases of a single general recurrence and that its closed-form solution leads to these expressions. Citations are given showing where the expressions occur in the theory of iterative methods

Linear stationary second-degree methods for the solution of large linear systems

The optimum linear stationary second-degree iterative method for solving linear systems of equations is not as good in general as the optimum semi-iterative method. However, for a suitable choice of parameters, the rate of convergence of the stationary method is very nearly as good as that of the semi-iterative method. The authors present a straightforward determination of these optimum parameter values and the asymptotic rate of convergence

Basic linear algebra subprograms for FORTRAN usage. [BLAS, in FORTRAN and assembly language for IBM 360/67, CDC 6600 and 7600, and Univac 1108]

A package of 38 low-level subprograms for many of the basic operations of numerical linear algebra is presented. The package is intended to be used with FORTRAN. The operations in the package are dot products, elementary vector operations, Givens transformations, vector copy and swap, vector norms, vector scaling, and the indices of components of largest magnitude. The subprograms and a test driver are available in portable FORTRAN. Versions of the subprograms are also provided in assembly language for the IBM 360/67, the CDC 6600 and CDC 7600, and the Univac 1108

Plume–slab interaction: The Samoa–Tonga system

Mantle plume behavior near subducting plates is still poorly understood and in fact varies significantly from the classical hotspot model. We investigate using 3D laboratory models how subduction-driven flow relates to the deformation and dispersal of a nearby plume. Results show slab-driven flow severely distorts plume-driven flow, entraining and passively advecting plume material despite its thermal buoyancy. Downdip sinking of the slab initially stalls vertical plume ascent while the combination of downdip and rollback sinking motions redistribute material throughout the system. As a consequence of the subduction-induced flow, surface expressions differ significantly from traditional plume expectations. Variations in slab sinking style and plume position lead to a range in head and conduit melting signatures, as well as migrating hotspots. For the Samoa–Tonga system, model predictions are consistent with proposed entrainment of plume material around the subducting plate

Combining thermoelastic and stress function to evaluate individual stresses around a near-edge hole

Individual stresses are determined on and near the edge of a hole which is located below a concentrated edge-load in an approximate half-plane. Experimental thermoelastic data are combined with an Airy’s stress function. Coefficients of the stress function are evaluated from the recorded TSA data and the traction-free conditions on the hole boundary are satisfied by imposing srr = trq = 0 on the edge of the hole for all values of the angle q. This advantageously enables one to reduce the number of coefficients in the stress function series. The method simultaneously smoothes the measured input data, satisfies the traction-free boundary conditions and evaluates individual stresses on, and in the neighborhood of, the edge of the hole

Natural phenomena hazards evaluation of equipment and piping of Gaseous Diffusion Plant Uranium Enrichment Facility

In support of the Gaseous Diffusion Plant Safety Analysis Report Upgrade program (GDP SARUP), a natural phenomena hazards evaluation was performed for the main process equipment and piping in the uranium enrichment buildings at Paducah and Portsmouth gaseous diffusion plants. In order to reduce the cost of rigorous analyses, the evaluation methodology utilized a graded approach based on an experience data base collected by SQUG/EPRI that contains information on the performance of industrial equipment and piping during past earthquakes. This method consisted of a screening walkthrough of the facility in combination with the use of engineering judgment and simple calculations. By using these screenings combined with evaluations that contain decreasing conservatism, reductions in the time and cost of the analyses were significant. A team of experienced seismic engineers who were trained in the use of the DOE SQUG/EPRI Walkdown Screening Material was essential to the success of this natural phenomena hazards evaluation