Analysis of Random Number Generators Using Monte Carlo Simulation

Revisions are almost entirely in the introduction and conclusion. Results are unchanged, however the comments and recommendations on different generators were changed, and more references were added.Comment: Email: [email protected] 16 pages, Latex with 1 postscript figure. NPAC technical report SCCS-52

JAPARA - A Java parallel random number generator library for high-performance computing

Copyright © 2004 IEEERandom number generators are one of the most common numerical library functions used in scientific applications. The standard random number generator provided within Java is fine for most purposes, however it does not adequately meet the needs of large-scale scientific applications, such as Monte Carlo simulations. Previous work has addressed some of these problems by extending the standard Random API in Java and providing an implementation that includes a choice of several different generator algorithms. One issue that was not addressed in this work was concurrency. Implementations of the standard Java random number generator use synchronized methods to support the use of the generator across multiple Java threads, however this is a sequential bottleneck for parallel applications. Here we present a proposal for further extending the standard API to support parallel generation of random number streams, which we have implemented in JAPARA, a Java Parallel Random Number Generator Library for high-performance computing.P. D. Coddington, A. J. Newel

Project for the analysis of technology transfer Annual report, 1969

Technology utilization of NASA programs and other research and development programs in Federal Government - project analysis results of technology transfe

Nonequilibrium effects of anisotropic compression applied to vortex lattices in Bose-Einstein condensates

We have studied the dynamics of large vortex lattices in a dilute-gas Bose-Einstein condensate. While undisturbed lattices have a regular hexagonal structure, large-amplitude quadrupolar shape oscillations of the condensate are shown to induce a wealth of nonequilibrium lattice dynamics. When exciting an m = -2 mode, we observe shifting of lattice planes, changes of lattice structure, and sheet-like structures in which individual vortices appear to have merged. Excitation of an m = +2 mode dissolves the regular lattice, leading to randomly arranged but still strictly parallel vortex lines.Comment: 5 pages, 6 figure

Compilation of XSLT into dataflow graphs for web service composition

Copyright © 2006 IEEEOur current research into programming models for parallel Web services composition is targeted at providing mechanisms for obtaining higher throughput for large scale compute and data intensive programs that delegate part of their computation to services, and making it easier to develop such applications. The ability to invoke multiple service calls at one time on different machines enables different portions of the program to be executed concurrently. We are addressing this through an implementation of an existing functional language, XSLT. Our implementation uses a dataflow execution model, and includes a compiler to build dataflow graphs from XSLT source code. This paper describes the execution model used to obtain parallelism and compose Web services, as well as the compilation process used to create the dataflow graphs. Our aim with this paper is to present the design of our system and demonstrate that XSLT provides a suitable model for distributed execution and parallel composition of Web services.Peter M. Kelly, Paul D. Coddington, and Andrew L. Wendelbor

Distributed, parallel web service orchestration using XSLT

©2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.GridXSLT is an implementation of the XSLT programming language designed for distributed web service orchestration. Based on the functional semantics of the language, it compiles programs into dataflow graphs which can be efficiently executed across a collection of machines in a cluster or grid environment. Calls to web services can be made using the standard function call semantics provided by the language, and occur in parallel using the dataflow model of computation. The programmer is not required to explicitly specify the parallelism, as the details of how programs are scheduled and executed in a distributed environment are abstracted away by the run-time engine. XSLT provides a higher level programming model than many other approaches to web services composition; we explore its use here as a means of easing the task of orchestrating the interactions between services. In addition to the normal XSLT syntax, our system also supports programs written in XSLiTe, an alternative syntax we have developed which uses more concise representations of language constructs, increasing the ease of development, and bringing code readability closer to that of traditional programming languages. Our goal is to ease the construction of applications based on web services composition, such as those used in eScience and other fields in which service oriented architectures are prominent.Peter M. Kelly, Paul D. Coddington, Andrew L. Wendelbor

An environment for workflow applications on wide-area distributed systems

©2001 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Workflow techniques are emerging as an important approach for the specification and management of complex processing tasks. This approach is especially powerful for utilising distributed data and processing resources in widely-distributed heterogeneous systems. We describe our DISCWorld distributed workflow environment for composing complex processing chains, which are specified as a directed acyclic graph of operators. Users of our system can formulate processing chains using either graphical or scripting tools. We have deployed our system for image processing applications and decision support systems. We describe the technologies we have developed to enable the execution of these processing chains across wide-area computing systems. In particular, we present our Distributed Job Placement Language (based on XML) and various Java interface approaches we have developed for implementing the workflow metaphor. We outline a number of key issues for implementing a high-performance, reliable, distributed workflow management system.James, H.A.; Hawick, K.A.; Coddington, P.D

Bridging the gap between the semantic web and existing network services

©2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.This paper presents an overview of a mechanism for bridging the gaps between the Semantic Web data and services, and existing network-based services that are not semantically-annotated or do not meet the requirements of Semantic Web-based applications. The Semantic Web is a relatively new set of technologies that mutually interoperate well but often require mediation, translation or wrapping to interoperate with existing network-based services. Seen as an extension of network-based services and the WWW, the Semantic Web constitutes an expanding system that can require significant effort to integrate and develop services while still providing seamless service to users. New components in a system must interoperate with the existing components and their use of protocols and shared data must be structurally and semantically equivalent. The new system must continue to meet the original system requirements as well as providing the new features or facilities. We propose a new model of network services using a knowledge-based approach that defines services and their data in terms of an ontology that can be shared with other components.Nickolas J. G. Falkner, Paul D. Coddington, Andrew L. Wendelbor

Optimising performance in network-based information systems: Virtual organisations and customised views

©2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Network-based information systems use well-defined standards to ensure interoperability and also have a tightly coupled relationship between their internal data representation and the external network representation. Virtual organisations (VOs), where members share a problem-solving purpose rather than a location-based or formal organisation, constitute an environment where user requirements may not be met by these standards. A virtual organisation has no formal body to manage change requests for these standards so the user requirements cannot be met. We show how the decoupling of the internal and external representations, through the use of ontologies, can enhance the operation of these systems by enabling flexibility and extensibility. We illustrate this by demonstrating a system that implements and enhances the Domain Name System, a global network-based information system. Migrating an existing system to a decoupled, knowledge-driven system is neither simple nor effortless but can provide significant benefits.Nickolas J. G. Falkner, Paul D. Coddington, Andrew L. Wendelbor