CRAY mini manual. Revision D

This document briefly describes the use of the CRAY supercomputers that are an integral part of the Supercomputing Network Subsystem of the Central Scientific Computing Complex at LaRC. Features of the CRAY supercomputers are covered, including: FORTRAN, C, PASCAL, architectures of the CRAY-2 and CRAY Y-MP, the CRAY UNICOS environment, batch job submittal, debugging, performance analysis, parallel processing, utilities unique to CRAY, and documentation. The document is intended for all CRAY users as a ready reference to frequently asked questions and to more detailed information contained in the vendor manuals. It is appropriate for both the novice and the experienced user

Parallel computing for the finite element method

A finite element method is presented to compute time harmonic microwave fields in three dimensional configurations. Nodal-based finite elements have been coupled with an absorbing boundary condition to solve open boundary problems. This paper describes how the modeling of large devices has been made possible using parallel computation, New algorithms are then proposed to implement this formulation on a cluster of workstations (10 DEC ALPHA 300X) and on a CRAY C98. Analysis of the computation efficiency is performed using simple problems. The electromagnetic scattering of a plane wave by a perfect electric conducting airplane is finally given as example

Development of learning objectives for neurology in a veterinary curriculum: Part II: Postgraduates

Background: Specialization in veterinary medicine in Europe is organized through the Colleges of the European Board of Veterinary Specialization. To inform updating of the curriculum for residents of the European College of Veterinary Neurology (ECVN) job analysis was used. Defining job competencies of diploma holders in veterinary neurology can be used as references for curriculum design of resident training. With the support of the diplomates of the ECVN and the members of the European Society of Veterinary Neurology (ESVN) a mixed-method research, including a qualitative search of objectives and quantitative ranking with 149 Likert scale questions and 48 free text questions in 9 categories in a survey was conducted. In addition, opinions of different groups were subjected to statistical analysis and the result compared. Results: A return rate of 62% (n = 213/341) was achieved. Of the competencies identified by the Delphi process, 75% objectives were expected to attain expert level; 24% attain advanced level; 1% entry level. In addition, the exercise described the 11 highly ranked competencies, the 3 most frequently seen diseases of the central and peripheral nervous systems and the most frequently used immunosuppressive, antiepileptic and chemotherapeutic drugs. Conclusion: The outcomes of this “Delphi job analysis” provide a powerful tool to align the curriculum for ECVN resident training and can be adapted to the required job competencies, based on expectations. The expectation is that for majority of these competencies diplomates should attain an expert level. Besides knowledge and clinical skills, residents and diplomates are expected to demonstrate high standards in teaching and communication. The results of this study will help to create a European curriculum for postgraduate education in veterinary neurology

Parallel numerical methods for large-scale DAE systems

For plantwide dynamic simulation in chemical process industry, parallel numerical methods using a divide and conquer strategy are considered. An approach for the numerical solution of initial value problems for large systems of differential algebraic equations (DAEs) arising from industrial applications and its realization on parallel computers with shared memory is discussed. The system is partitioned into blocks and then it is extended appropriately, such that block-structured Newton-type methods can be applied which enable the application of relaxation techniques. This approach has gained considerable speedup factors for the dynamic simulation of various large-scale distillation plants, covering systems with up to 60 000 equations

Parallel iteration of the extended backward differentiation formulas

The extended backward differentiation formulas (EBDFs) and their modified form (MEBDF) were proposed by Cash in the 1980s for solving initial-value problems (IVPs) for stiff systems of ordinary differential equations (ODEs). In a recent performance evaluation of various IVP solvers, including a variable-step-variable-order implementation of the MEBDF method by Cash, it turned out that the MEBDF code often performs more efficiently than codes like RADAU5, DASSL and VODE. This motivated us to look at possible parallel implementations of the MEBDF method. Each MEBDF step essentially consists of successively solving three nonlinear systems by means of modified Newton iteration using the same Jacobian matrix. In a direct implementation of the MEBDF method on a parallel computer system, the only scope for (coarse grain) parallelism consists of a number of parallel vector updates. However, all forward-backward substitutions and all righthand side evaluations have to be done in sequence. In this paper, our starting point is the original (unmodified) EBDF method. As a consequence, two different Jacobian matrices are involved in the modified Newton method, but on a parallel computer system, the effective Jacobian-evaluation and the LU-decomposition costs are not increased. Furthermore, we consider the simultaneous solution, rather than the successive solution, of the three nonlinear systems, so that in each iteration the forward-backward substitutions and the righthand side evaluations can be done concurrently. A mutual comparison of the performance of the parallel EBDF approach and the MEBDF approach shows that we can expect a speedup factor of about 2 on 3 processors

Optimization of Supercomputer Use on EADS II System

The main objective of this research was to optimize supercomputer use to achieve better throughput and utilization of supercomputers and to help facilitate the movement of non-supercomputing (inappropriate for supercomputer) codes to mid-range systems for better use of Government resources at Marshall Space Flight Center (MSFC). This work involved the survey of architectures available on EADS II and monitoring customer (user) applications running on a CRAY T90 system

APPLICATION OF EXPLICITLY CORRELATED GAUSSIANFUNCTIONS TO LARGE SCALE CALCULATIONS ONSMALL ATOMS AND MOLECULES

Exponentially Correlated Gaussian wave functions are applied to variational calculations of thetotal electronic energy of several a few-electron atomic and molecular systems. It is shown thatthis powerful approach enables to obtain extremely accurate results not only for two-electronsystems but also for three- and four-electron atoms and molecules.Pozna

Numerische Lösung großer strukturierter DAE-Systeme der chemischen Prozeßsimulation

Parallelizable numerical methods for solving large scale DAE systems are developed at the level of differential, nonlinear and linear equations. For this the subsystem-wise structure of the DAE systems based on unit-oriented modelling is explored. Partitionings are used to parallelize waveform relaxation and structured Newton methods. Initial values are computed with a modified Newton method. To solve large sparse systems of linear equations a special Gaussian elimination method is used. The algorithms were implemented on a CRAY C90 vector computer, as well as on both, moderately parallel CRAY J90 vector computers and massively parallel CRAY T3D machines. The methods were tested using several real life examples