Browsing by Author "James, H.A."

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    64-bit architechtures and compute clusters for high performance simulations
    (Massey University, 2006) Hawick, K.A.; James, H.A.; Scogings, C.J.
    Simulation of large complex systems remains one of the most demanding of high performance computer systems both in terms of raw compute performance and efficient memory management. Recent availability of 64-bit architectures has opened up the possibilities of commodity computers accessing more than the 4 Gigabyte memory limit previously enforced by 32-bit addressing. We report on some performance measurements we have made on two 64-bit architectures and their consequences for some high performance simulations. We discuss performance of our codes for simulations of artificial life models; computational physics models of point particles on lattices; and with interacting clusters of particles. We have summarised pertinent features of these codes into benchmark kernels which we discuss in the context of wellknown benchmark kernels of the 32-bit era. We report on how these these findings were useful in the context of designing 64-bit compute clusters for high-performance simulations.
  • Thumbnail Image
    Item
    A framework and simulation engine for studying artificial life
    (Massey University, 2004) James, H.A.; Scogings, C.; Hawick, K.A.
    The area of computer-generated artificial life-forms is a relatively recent field of inter-disciplinary study that involves mathematical modelling, physical intuition and ideas from chemistry and biology and computational science. Although the attribution of “life” to non biological systems is still controversial, several groups agree that certain emergent properties can be ascribed to computer simulated systems that can be constructed to “live” in a simulated environment. In this paper we discuss some of the issues and infrastructure necessary to construct a simulation laboratory for the study of computer generated artificial life-forms. We review possible technologies and present some preliminary studies based around simple models.
  • Thumbnail Image
    Item
    Managing community membership information in a small-world grid
    (Massey University, 2005) Hawick, K.A.; James, H.A.
    As the Grid matures the problem of resource discovery across communities, where resources now include computational services, is becoming more critical. The number of resources available on a world-wide grid is set to grow exponentially in much the same way as the number of static web pages on the WWW. We observe that the world-wide resource discovery problem can be modelled as a slowly evolving very-large sparse-matrix where individual matrix elements represent nodes’ knowledge of one another. Blocks in the matrix arise where nodes offer more than one service. Blocking effects also arise in the identification of sub-communities in the Grid. The linear algebra community has long been aware of suitable representations of large, sparse matrices. However, matrices the size of the world-wide grid potentially number in the billions, making dense solutions completely intractable. Distributed nodes will not necessarily have the storage capacity to store the addresses of any significant percentage of the available resources. We discuss ways of modelling this problem in the regime of a slowly changing service base including phenomena such as percolating networks and small-world network effects.
  • Thumbnail Image
    Item
    Node importance ranking and scaling properties of some complex road networks
    (Massey University, 2007) Hawick, K.A.; James, H.A.
    The scaling and other quantifiable properties of a network have recently been proven valuable in understanding the robustness and vulnerability properties of various societal and infrastructural networks. In this paper we revisit the algorithms for computing various quantifiable properties of a planar road network and consider the algorithmic complexity and scalability in the light of recent technological advances. We compute properties for a sample of interesting trunk road networks and discuss their applicability in determining the relative importance or criticality to the whole network of a particular node. We discuss the implications of present and anticipated technological capabilities in calculating properties for anticipated network sizes in the light of 64-bit computer architectures and commodity parallel computing.
  • Thumbnail Image
    Item
    Simulating large random Boolean networks
    (Massey University, 2007) Hawick, K.A.; James, H.A.; Scogings, C.J.
    The Kauffman N-K, or random boolean network, model is an important tool for exploring the properties of large scale complex systems. There are computational challenges in simulating large networks with high connectivities. We describe some high-performance data structures and algorithms for implementing large-scale simulations of the random boolean network model using various storage types provided by the D programming language. We discuss the memory complexity of an optimised simulation code and present some measured properties of large networks.
  • Thumbnail Image
    Item
    Sparse cross-products of metadata in scientific simulation management
    (Massey University, 2005) James, H.A.; Hawick, K.A.
    Managing scientific data is by no means a trivial task even in a single site environment with a small number of researchers involved. We discuss some issues concerned with posing well-specified experiments in terms of parameters or instrument settings and the metadata framework that arises from doing so. We are particularly interested in parallel computer simulation experiments, where very large quantities of warehouse-able data are involved. We consider SQL databases and other framework technologies for manipulating experimental data. Our framework manages the the outputs from parallel runs that arise from large cross-products of parameter combinations. Considerable useful experiment planning and analysis can be done with the sparse metadata without fully expanding the parameter cross-products. Extra value can be obtained from simulation output that can subsequently be data-mined. We have particular interests in running large scale Monte-Carlo physics model simulations. Finding ourselves overwhelmed by the problems of managing data and compute ¿resources, we have built a prototype tool using Java and MySQL that addresses these issues. We use this example to discuss type-space management and other fundamental ideas for implementing a laboratory information management system.