Bunch-Kaufman factorization for real symmetric indefinite banded matrices

The Bunch-Kaufman algorithm for factoring symmetric indefinite matrices was rejected for banded matrices because it destroys the banded structure of the matrix. Herein, it is shown that for a subclass of real symmetric matrices which arise in solving the generalized eigenvalue problem using Lanczos's method, the Bunch-Kaufman algorithm does not result in major destruction of the bandwidth. Space time complexities of the algorithm are given and used to show that the Bunch-Kaufman algorithm is a significant improvement over LU factorization

The use of Lanczos's method to solve the large generalized symmetric definite eigenvalue problem

The generalized eigenvalue problem, Kx = Lambda Mx, is of significant practical importance, especially in structural enginering where it arises as the vibration and buckling problem. A new algorithm, LANZ, based on Lanczos's method is developed. LANZ uses a technique called dynamic shifting to improve the efficiency and reliability of the Lanczos algorithm. A new algorithm for solving the tridiagonal matrices that arise when using Lanczos's method is described. A modification of Parlett and Scott's selective orthogonalization algorithm is proposed. Results from an implementation of LANZ on a Convex C-220 show it to be superior to a subspace iteration code

A language comparison for scientific computing on MIMD architectures

Choleski's method for solving banded symmetric, positive definite systems is implemented on a multiprocessor computer using three FORTRAN based parallel programming languages, the Force, PISCES and Concurrent FORTRAN. The capabilities of the language for expressing parallelism and their user friendliness are discussed, including readability of the code, debugging assistance offered, and expressiveness of the languages. The performance of the different implementations is compared. It is argued that PISCES, using the Force for medium-grained parallelism, is the appropriate choice for programming Choleski's method on the multiprocessor computer, Flex/32

1993 Clinic Yearbook

The Clinic is the yearbook of the Sidney Kimmel Medical College (formerly Jefferson Medical College) at Thomas Jefferson University

Evidence for Possible Late Paleozoic Alleghenian Deformation Structures in the Devonian Rocks of Erie County, Ohio, USA

Partially exposed bedrock beneath Pleistocene glacial till in Erie County (north-central Ohio) displays unusual structural deformation in the Devonian Berea Sandstone, Bedford Shale, and Ohio Shale. These folded and faulted units are exposed in creeks as anticlines and synclines. Past studies of this area proposed Pleistocene ice movement and soft-sediment deformation during the Late Paleozoic as the deformation mechanisms, but these hypotheses cannot explain the extent of layer displacement or the contradiction between the southwest travel direction of the ice sheet and the structural sense of motion on the folded units. A new interpretation using field data and constructing geologic profiles explains the development of these structures. This study investigated 17 anticlines that trend in different directions. Four of these anticlines are tightly folded with steep or overturned flanks and thrust-faulted Ohio Shale in their cores. Structural analysis of these folds shows that the incompetent shaly units of the Plum Brook–Ohio–Bedford and competent Berea Sandstone were folded above the Delaware–Niagara carbonates as a result of the compressional stress during the Late Paleozoic. Development of these tight or overturned folds, and change in trend of the anticlines, is caused by unusual stratigraphic thickness variations in the Berea and Bedford units. Preserved and undeformed fine sedimentary structures, and sharply faulted beds, in the Berea and Bedford indicate that soft-sediment deformation was not the cause of the regional structural deformation. Finally, the absence of physical features of glacially deformed bedrock demonstrates that Pleistocene glacial ice shove was not the cause of deformed bedrock units in the study area

The impact of oxalate ions on barium sulfate crystallization

In this manuscript we investigate the impact of oxalate ions on the crystallization of barium sulfate. The organic anion, oxalate, was found to inhibit both nucleation and growth according to atomic force microscopy measurements and dynamic light scattering data. Raman confocal imaging was used to try and determine how the oxalate interacts with the barium sulfate surface. It was found that barium oxalate is only seen at very high oxalate concentrations. At lower concentrations no direct evidence for the presence of oxalate was observed, however, the most probable mode of action for oxalate is via adsorption onto the barium sulfate surface including into key kink or step sites, impacting growth

VETA x ray data acquisition and control system

We describe the X-ray Data Acquisition and Control System (XDACS) used together with the X-ray Detection System (XDS) to characterize the X-ray image during testing of the AXAF P1/H1 mirror pair at the MSFC X-ray Calibration Facility. A variety of X-ray data were acquired, analyzed and archived during the testing including: mirror alignment, encircled energy, effective area, point spread function, system housekeeping and proportional counter window uniformity data. The system architecture is presented with emphasis placed on key features that include a layered UNIX tool approach, dedicated subsystem controllers, real-time X-window displays, flexibility in combining tools, network connectivity and system extensibility. The VETA test data archive is also described