The Formation of Galaxies and Large-Scale Structure

Ostriker 9318185大挑战应用组竞赛为科学家和工程师组成的多学科团队提供了一种支持机制，以实现1993年财政年度高性能计算和通信(HPCC)计划的目标。理想的建议不仅提供了在以下方面取得重大进展的机会：(1)科学或工程中的一个基本问题，其解决办法可以通过应用高性能计算技术和资源来推进，或(2)促进这些进步的技术，而且科学和计算活动之间的重大相互作用，通常涉及数学、计算机或计算科学家，将对正在研究的特定科学或工程问题领域(S)或学科以外的高性能计算活动产生影响。该项目汇集了一个由天体物理学家、计算科学家和计算机科学家组成的平衡、临界质量的团队，以及美国国家科学基金会两个超级计算中心的技术资源，以集中力量解决目前物理科学中最令人兴奋和最基本的问题之一：宇宙中大尺度结构的起源是什么，星系是如何形成的？有丰富的观测数据，对物理定律和数学技术有足够的知识，需要了解宇宙结构的起源和演化。然而，由于这些系统固有的复杂性，以及模拟多个长度尺度的相互作用的困难，很难将理论与观测详细地对峙。然而，我们的大挑战应用小组(GCAG)成员在多尺度数值算法方面的最新进展以及它们在可伸缩并行超级计算机上的高效实现应该能够使研究人员克服这些限制。GCAG将探索使用：(I)不同的数值算法(基于网格、基于粒子和混合(网格+粒子))来求解控制膨胀宇宙中的气体、辐射、暗物质和重力的物理方程；(Ii)不同的适应策略(自适应网格细化、分层树)以实现能够在4-6个数量级上解析感兴趣的长度尺度的高效、多尺度解算器；(Iii)不同的编程模型(数据并行、SPMD、对象并行)，以在研究人员可用的不同并行体系结构(TMC的CM5、Intel Paragon、Cray T3D、Convex MPP)上以高效和便携的方式表达这些复杂的、自适应的算法；以及(Iv)新的软件技术(例如PC++)，以开发编译器、优化设计和性能分析工具，从而最有效地实施上述战略，以便揭示在本十年晚些时候为万亿次浮点运算系统构建可移植、可扩展的应用程序所需的各种计算和计算机科学问题。这个独特的数值实验室将允许研究人员将大尺度结构起源的理论与观测到的宇宙进行比较，丢弃错误的模型，并有望确定可行理论的元素。这场HPCC大挑战将是数据和UO极其密集的，将现有的硬件和软件系统和解决方案推向并超越它们的极限。调查人员将与匹兹堡和伊利诺伊州超级计算机中心的工作人员以及计算机供应商合作，开发实用而高效的策略，以存储、可视化和分析这一应用程序和其他HPCC应用程序使用的大量数字数据集。该奖项由高级项目研究机构以及天文学和计算机科学方面的NSF项目支持。

Ostriker 9318185 The Grand Challenge Application Groups competition provides one mechanism for the support of multidisciplinary teams of scientists and engineers to meet the goals of the High Performance Computing and Communications (HPCC) Initiative in Fiscal Year 1993. The ideal proposal provided not only the opportunity to achieve significant progress on (1) a fundamental problem in science or engineering whose solution could be advanced by applying high performance computing techniques and resources, or (2) enabling technologies which facilitate those advances, but also significant interactions between scientific and computational activities, usually involving mathematical, computer or computational scientist, that would have impact in high performance computational activities beyond the specific scientific or engineering problem area(s) or discipline being studied. This project brings together a balanced, critical mass team of astrophysicists, computational scientists and computer scientists, as well as the technical resources of two NSF supercomputing centers, to mount a focused attack on what is presently one of the most exciting and fundamental problems in the physical sciences: "What is the origin of large-scale structure in the universe and how do galaxies form?" There is abundant observational data sufficient knowledge of the physical laws and mathematical techniques required to understand the origin and evolution of cosmic structure. Yet, it is difficult to confront theory with observation in detail owing to the inherent complexity of these systems and the difficulty of simulating multiple length-scale interactions. However, recent developments in multiscale numerical algorithms by members of our Grand Challenge Application Group (GCAG) and their efficient implementation on scaleable parallel supercomputers should enable the investigators to overcome these limitations. The GCAG will explore the use of: (i) different numerical algorithms (grid-based, particle-based, and hybrid ( grid+particle) to solve the physical equations governing gas, radiation, dark matter and gravity in an expanding universe; (ii) different adaptation strategies (adaptive mesh refinement, hierarchical tree) to achieve efficient, multiscale solvers capable of resolving length scales of interest over 4-6 orders of magnitude; (iii) different programming models (data parallel, SPMD, object parallel) to express these complex, adaptive algorithms in an efficient and portable way on different parallel architectures (TMC's CM5, Intel PARAGON, Cray T3D, Convex MPP) available to the investigators; and (iv) new software technology (e.g. pC++) to develop compilers, optimization designs and performance analysis tools which allow the most efficient implementation of the above strategies in order to expose the various computational and computer science issues required to construct a portable, scaleable application for teraflop systems expected later in this decade. This unique numerical laboratory-will allow the investigators to compare theories of the origin of large-scale structure with the observed universe, to discard incorrect models and hopefully to determine the elements of a viable theory. This HPCC Grand Challenge will be extremely data and UO intensive, pushing current hardware and software systems and solutions to and beyond their limits. The investigators will work with staffs of the Pittsburgh and Illinois supercomputer centers as well as the computer vendors to develop practical and efficient strategies for the storage, visualization and analysis of massive numerical data sets of use to this and other HPCC applications. This award is being supported by the Advanced Projects Research Agency as well as NSF programs in astronomy and computer sciences.