高性能并行计算在航空航天CFD数值模拟中的应用

本文介绍了高性能并行计算在CFD数值模拟中的应用。CFD高性能并行计算可扩大求解规模,加快求解速度,是CFD实现高效计算的必然发展趋势。本文通过"数值风洞"的概念分析了CFD高性能计算的应用前景及对高性能计算的需求。通过某乘波飞行器前体并行算例对8～256CPU的CFD大规模并行效率和加速比进行了分析,并将CFD并行计算应用于高温热化学非平衡的返回舱数值计算中。     

大位移井悬链线轨道设计的新计算模型

通过对数学上悬链线解析式的基本变换和参数代换,推导和建立了一种新的大位移井悬链线轨道设计与计算模型,通过算例将使用 新模型计算的结果与国外类似软件计算的结果进行了对比分析,验证了应用新模型进行数据计算的准确性。新模型消除了双曲函数。简化了 计算机处理的复杂度,方便了技术人员的理解和使用。分析了应用新模型进行计算机处理的时间复杂度和空间复杂度。其计算复杂度明显低 于目前普遍采用的数学模型。     

Framework for formulation and analysis of parallel computation structures

This paper gives a systematic methodology for the formulation of parallel computation structures and algorithms. The fundamental definition of a computation structure is a graph where each node is the binding of an action to a data object and the arcs are the dependency relationships between the unit computations executed at the nodes. The structure of the graph is determined by the selection of elements for the model of computation in which the graph is expressed. An abstract machine is created by defining the resources including for example instruction sets for the processors, which realize the conceptual elements of the model of parallel computations. An algorithm is a mapping of the computation graph to the abstract machine and a program which traverses the mapped graph to execute the computation. The methodology proceeds by describing parallel computations on successively more fully specified abstract machines. A model of parallel computation is selected and an abstract machine implementing the model of computation is defined. Specification of increasingly resolved abstract machines is structured by both increasing the span of elements from the model of computation represented in the machine and be increasing the level of detail resolved for each element.     

Polyvariant mixed computation for analyzer programs

Summary A polyvariant mixed computation algorithm for low-level non-structured programs is presented. A subclass of so called analyser programs has been chosen for which all partial computation that becomes possible during mixed computation is defined over a finite domain of nonsuspended variables. This not only provides termination of mixed computation but allows also to embody in the residual program a control structure encoded in the data.     

Xeon Phi平台上基于模板优化的3D-GVF场计算加速

3D梯度向量流场（3D GVF field）广泛应用于多种3D图像分析算法中,其计算需要多次迭代,计算量大,如何提高其计算速度具有重要的研究意义。面向Intel Xeon Phi众核集成架构,首次进行了3D GVF场计算的加速优化。首先,挖掘3D图像像素点间存在的天然并行性,发挥众核架构优势,尝试线程级并行（多核）和数据级并行（SIMD）。其次,3D GVF场的计算过程是一种典型的3D 7点模板运算,结合Xeon Phi架构的L2 缓存规格,提出一种高效的数据分块策略,充分挖掘数据的时/空局部性,有效缓解模板计算引起的缓存缺失,提升了计算性能。实验结果表明,引入模板优化技术能显著提升3D GVF场的计算速度,在图像维度为5123时,所提方法在57核Xeon Phi平台上的性能相比在2.6GHz 8核16线程的Intel Xeon E5 2670 CPU上的性能,加速比可达2.77。     

关于认知演化计算分支领域的研究简报(II)

科学地认知演化计算分支领域对演化计算的研究与发展具有重要的意义.对演化计算分支领域发展的主线、特点和内在规律进行了回顾与总结,从科学哲学的角度阐述了如何对演化计算分支领域进行科学认知,并概要介绍了演化计算方法论研究的主要进展,讨论了演化计算方法论研究进展对计算机科学与技术学科未来发展可能产生的影响.     

面向同构多核处理器的节能任务调度方法

对于运行在同构多核处理器上的周期性硬实时任务,设计了一个基于动态电压调节的节能调度方法。该方法首先将计算任务按照周期数降序排序并基于计算任务调度长度最短的原则安排任务映射。然后将各个处理核上具有最小通讯时间的计算任务设置为最后执行的计算任务而其它计算任务顺序保持不变。在初始映射中所有计算任务都被分配最高频率的情况下,每个处理核上的计算任务在执行时间扩展过程中确定最佳的计算任务顺序。基于 Intel PXA270的功耗模型,以几个随机任务集作实验。结果表明提出的方法能够有效地降低多核处理器的能量。     

Transcending Turing Computability

It has been argued that neural networks and other forms of analog computation may transcend the limits of Turing-machine computation; proofs have been offered on both sides, subject to differing assumptions. In this article I argue that the important comparisons between the two models of computation are not so much mathematical as epistemological. The Turing-machine model makes assumptions about information representation and processing that are badly matched to the realities of natural computation (information representation and processing in or inspired by natural systems). This points to the need for new models of computation addressing issues orthogonal to those that have occupied the traditional theory of computation.     

关于认知演化计算分支领域的研究简报(I)

科学地认知演化计算分支领域,对演化计算的研究与发展具有重要的意义.对演化计算分支领域发展的主线、特点和内在规律进行了回顾与总结,从科学哲学的角度阐述了如何对演化计算分支领域进行科学认知,并概要介绍了演化计算方法论研究的主要进展,讨论了演化计算方法论研究进展对计算机科学与技术学科未来发展可能产生的影响.     

面向对象有限元并行计算框架PANDA的并行机制

为实现面向对象有限元并行计算框架PANDA对高性能计算的支持,分别从并行计算流程、区域分解、分区信息和通信封装等部分设计PANDA框架在并行计算方面的数据结构.在计算流程中建立区域分解和并行求解器的配合协作方式,进而描述进行区域分割的3种网格剖分方法;对分区边界单元和节点信息的组织以及对并行通信操作的封装使复杂的并行通...     

基于MatLab的海量数据处理方法

MatLab是MathWorks公司推出的一种科学计算软件,在使用MatLab进行数据处理过程中,常常会用到循环语句逐点处理数据,当数据量巨大时,经常会出现耗时长久的情况。将循环运算转换为矩阵运算,充分利用MatLab高效率的矩阵运算特点,可以缩短数据处理时间。通过一个算例分析了创建大容量矩阵的方法：如扩大内存空间、采用短字节数值数据类型等。算例运行结果表明,通过分配更多的内存空间进行大容量矩阵运算,可以显著缩短数据处理的时间,从而实现空间换时间的目的。     

The Explanatory Role of Computation in Cognitive Science

Which notion of computation (if any) is essential for explaining cognition? Five answers to this question are discussed in the paper. (1) The classicist answer: symbolic (digital) computation is required for explaining cognition; (2) The broad digital computationalist answer: digital computation broadly construed is required for explaining cognition; (3) The connectionist answer: sub-symbolic computation is required for explaining cognition; (4) The computational neuroscientist answer: neural computation (that, strictly, is neither digital nor analogue) is required for explaining cognition; (5) The extreme dynamicist answer: computation is not required for explaining cognition. The first four answers are only accurate to a first approximation. But the ??devil?? is in the details. The last answer cashes in on the parenthetical ??if any?? in the question above. The classicist argues that cognition is symbolic computation. But digital computationalism need not be equated with classicism. Indeed, computationalism can, in principle, range from digital (and analogue) computationalism through (the weaker thesis of) generic computationalism to (the even weaker thesis of) digital (or analogue) pancomputationalism. Connectionism, which has traditionally been criticised by classicists for being non-computational, can be plausibly construed as being either analogue or digital computationalism (depending on the type of connectionist networks used). Computational neuroscience invokes the notion of neural computation that may (possibly) be interpreted as a sui generis type of computation. The extreme dynamicist argues that the time has come for a post-computational cognitive science. This paper is an attempt to shed some light on this debate by examining various conceptions and misconceptions of (particularly digital) computation.     

Explicit formulation of multibody dynamics based on principle of dynamical balance and its parallelization

Efficient computation of dynamics parameters is one of the important issues in simulation and control of the multibody systems as these systems become more complex. Recent advances in computer architecture are toward multiple core systems rather than high-speed single core systems. Therefore, parallel computation algorithms for dynamics parameters should be designed to improve the performance on these multicore architectures. In this paper, a new dynamics computation algorithm is derived using the principle of dynamical balance, which provides explicit computation of dynamic parameters. This new algorithm has the structure to which parallel computation can be easily applicable. Parallel computation methods are then applied so that we can exploit the structure of the proposed dynamics computation algorithm based on the principle of dynamical balance. The parallel algorithm is designed based on task and data-parallelism. The performance of the proposed algorithm is verified on robots with various topologies. The improved speed of parallel computation is demonstrated through these experiments.     

高效安全向量计算及其推广

安全多方计算是密码学的一个重要研究方向,也是目前国际密码学界的研究热点.因为许多实际问题都可以用向量来描述,研究向量的保密计算具有重要的理论与实际意义.目前,关于向量保密计算问题大多是在整数集上进行研究,关于有理数向量问题的研究很少.在此主要研究有理数域上向量的安全多方计算问题,包括向量点积、向量相等、向量优势等问题,设计了安全高效的计算协议,扩大了向量保密计算的应用范围.对这些协议的安全性分析和效率分析表明,它们在安全性和效率方面与现有协议相比具有明显优势.并且利用所设计的协议解决了一些新的向量问题和计算几何问题.     

网格计算的研究与探讨

网格是一个基础体系结构,它耦合了:计算机、软件和数据库,通过局域网/广域网,形成一个统一的集成资源。网格计算(Grid Computing)指的是独立的用户组在高速网络上动态地共享计算机资源,形成对用户透明的超级计算环境,以满足不断变化的计算需求。本文介绍了网格计算结构、基本功能、网络的项目及体系结构,并对国内外著名的网格计算理论和应用作介绍,分析了目前网格计算研究的现状和发展前景。     

Models of computation for reactive control of autonomous mobile robots

The paper studies computation models for tasks performed by autonomous mobile robots. Such tasks can be accomplished by reactive control algorithms. Reactive control systems can be described using different models of computation which have as distinguishing feature the abstraction level of time. Thus, three computation models are defined: the untimed model, the synchronous model and the timed model. It is shown that the clocked-synchronous model of computation is more appropriate for describing the controller for a parallel parking task.     

自然计算研究进展

随着量子计算、DNA计算、免疫计算、进化计算和神经计算等新型计算机制的兴起,传统的计算正扩展为自然计算,因为这些新计算机制的产生都由自然系统启发而来.为了发展和应用自然计算技术,总结了自然计算的发展简史.然后,提出了计算机、自动控制等系统的两种体系结构,分析了自然计算的新特征,包括自然法则、交叉性、革命性和复杂性,并给出了自然计算的复杂性分析定理.改进了自然计算的映射模型,提出了自然计算的算法流程.最后,探讨了自然计算的研究意义和应用.总之,自然计算是活跃的重要研究方向,定会推动许多学科的发展.     

量子计算进展与展望*

评述量子计算的历史、研究现状以及进一步发展的方向.着重论述量子算法的机理,对已知量子算法特征进行总结分析;归纳量子计算与经典智能计算的结合模式,比较其与传统智能计算的异同.在总结量子计算存在问题的基础上,探讨了今后的研究方向.     

人工生命与人工生命计算

论文从人工生命的角度定义了人工生命计算的概念,提出了人工生命计算的一般框架。人工生命计算是一种以人工生命为形式、研究人工生命的信息表达和处理机制,提取相应的计算模型,嵌入相应的计算方法模拟自然界生物进化过程与信息处理机制来求解与优化问题的智能计算方法。同时对人工生命计算的理论基础包括遗传算法、人工神经网络、自动机理论、L-系统、智能体和多智能体系统和计算生态学等进行了概述;并对两种典型的人工生命计算方法进行了初步的研究。最后说明了人工生命计算的特点及目前的应用领域。人工生命计算具有非常显著的特点和优点,在科学和工程的诸多实际应用领域具有广泛的应用前景。     

并行计算在高超声速流场数值模拟中的应用

采用计算流体力学方法,对高超声速流场进行了多区并行计算研究。基于MPI消息传递库采用Fortran语言编制了CFD并行计算程序,对NS方程采用AUSMPW+格式和LU-SGS方法求解。针对流场采用多区剖分,将每一个子区分配给相应节点进行计算。每一迭代步,相邻子区域间交换边界数据。计算表明,本文所建立的程序和方法是可行的,能够进一步延伸到大规模并行计算和工程应用中。