Automatic domain decomposition on unstructured grids (DOUG)

This paper describes a parallel iterative solver for finite element discretisations of elliptic partial differential equations on 2D and 3D domains using unstructured grids. The discretisation of the PDE is assumed to be given in the form of element stiffness matrices and the solver is automatic in the sense that it requires minimal additional information about the PDE and the geometry of the domain. The solver parallelises matrix–vector operations required by iterative methods and provides parallel additive Schwarz preconditioners. Parallelisation is implemented through MPI. The paper contains numerical experiments showing almost optimal speedup on unstructured mesh problems on a range of four platforms and in addition gives illustrations of the use of the package to investigate several questions of current interest in the analysis of Schwarz methods. The package is available in public domain from the home page http://www.maths.bath.ac.uk/^∼mjh/. This revised version was published online in August 2006 with corrections to the Cover Date.     

软件开发中的海洋模型

提出了软件开发的海洋模型，讨论了如何将软件开发的一般模型与海洋模型相结合，给出了一个海洋模型实现的实例─—Ｈａｉｇａｎｇ系统．用ＳＯＫＭ／Ｌ语言对海洋模型进行了描述．     

A basic course on compiler principles

An attempt to devise a methodology of compiler design is described, and an outline is given for a possible course on this subject. The theoretical basis is formed by the concepts of phrase-structure language, finite-state- and stack-acceptor, and transducer. As their extension capable of processing context-dependent elements of languages, a so-called Table-Transducer is postulated, and it serves as the core-algorithm upon which compilers are based. The developed theory and method of compiler construction is applied to an example of a simple programming language.     

An on-line TDC-312 computer-controlled neutron diffractometer

The design and fabrication of an indigenous on-line computer controlled four-circle neutron diffractometer at the CIRUS reactor in Trombay are described. The diffractometer has an 18 in dia full-circle crystal-orienter which is sturdy enough to carry a cryostat. Three crystal orientation angles χ, φ and ω and the detector angle 2θ can be set to an accuracy of 0·01°. The four angle shafts are driven through precision worm-gears by SCR-controlled DC motors and their instantaneous positions sensed by optical digitizers. The diffractometer is interfaced to an ECIL TDC-312 computer system consisting of the CPU with 4K-memory, ASR-35 teletype, X-Y plotter and the digital input/output system (DIOS). The DIOS which operates under program control is a real-time peripheral device used to exchange information in digital form between the computer and the diffractometer. A software package consisting of over 40 useroriented teletype commands has been developed for on-line control and automatic data-acquisition.     

用Visual Basic编制物理实验数据处理及评价软件

本文主要给出了利用VB编制的“用牛顿环测量透镜曲率半径”的实验数据处理软件一种新方法。     

A Faster and Simpler Recursive Algorithm for the LAPACK Routine DGELS

We present new algorithms for computing the linear least squares solution to overdetermined linear systems and the minimum norm solution to underdetermined linear systems. For both problems, we consider the standard formulation min AX – B _F and the transposed formulation min A ^T X – B _F , i.e, four different problems in all. The functionality of our implementation corresponds to that of the LAPACK routine DGELS. The new implementation is significantly faster and simpler. It outperforms the LAPACK DGELS for all matrix sizes tested. The improvement is usually 50–100% and it is as high as 400%. The four different problems of DGELS are essentially reduced to two, by use of explicit transposition of A. By explicit transposition we avoid computing Householder transformations on vectors with large stride. The QR factorization of block columns of A is performed using a recursive level-3 algorithm. By interleaving updates of B with the factorization of A, we reduce the number of floating point operations performed for the linear least squares problem. By avoiding redundant computations in the update of B we reduce the work needed to compute the minimum norm solution. Finally, we outline fully recursive algorithms for the four problems of DGELS as well as for QR factorization.This revised version was published online in October 2005 with corrections to the Cover Date.     

一个不完全排错状态下的软件可靠性增长模型

在充分地考虑了软件排错过程特点的基础上,将现有的可靠性增长模型中“完全排错”的假设修改为“不完全排错”,使之更符合实际情况．通过将软件错误分为不同的两类来刻画,得到了一个软件可靠性增长模型,该模型含有两个参数,使用起来较为方便．     

基于软件体系结构的需求分析与设计

提出了一种新的软件系统分析和开发方法．把领域知识划分为３类,然后向软件系统进行多层映射．并以两个实例说明了这种分类和转换方法．