Fraction-free matrix factors: new forms for LU and QR factors

Gaussian elimination and LU factoring have been greatly studied from the algorithmic point of view, but much less from the point view of the best output format. In this paper, we give new output formats for fraction free LU factoring and for QR factoring. The formats and the algorithms used to obtain them are valid for any matrix system in which the entries are taken from an integral domain, not just for integer matrix systems. After discussing the new output format of LU factoring, the complexity analysis for the fraction free algorithm and fraction free output is given. Our new output format contains smaller entries than previously suggested forms, and it avoids the gcd computations required by some other partially fraction free computations. As applications of our fraction free algorithm and format, we demonstrate how to construct a fraction free QR factorization and how to solve linear systems within a given domain.     

A Comparison of Free BDDs and Transformed BDDs

Ordered binary decision diagrams (OBDDs) introduced by Bryant (IEEE Trans. on Computers, Vol. 35, pp. 677–691, 1986) have found a lot of applications in verification and CAD. Their use is limited if the OBDD size of the considered functions is too large. Therefore, a variety of generalized BDD models has been presented, among them FBDDs (free BDDs) and TBDDs (transformed BDDs). Here the quite tight relations between these models are revealed and their advantages and disadvantages are discussed.     

（RbCl）108离子簇均相成核的分子动力学研究

分子动力学模拟测得熔融（RbCl)108离子簇在300K至600K温度时凝固的成核速率大于10^35m^-3s^-1,用均相成核的经典理论加以分析,估算得氯化铷离子簇的固液界面自由能σalT^1.4,用Grunasy提出的扩散界面理论加以分析,估算得扩展界面厚度约为0．195nm,σalT^0.97,2个理论在实验温度范围内没有明显判别,且均能较好地分子动力学模型的结果,但预测的较高温度下的成核速率有比较显著区别,因此进一步地研究将有助于鉴别它们。     

FLASK-SG: A program to compute chemical equilibria in metamorphic petrology

Chemical equilibrium calculation program for metamorphic petrology, FLASK-SG, was written for Unix variants (Linux, IRIX, Tru64 UNIX). It is also ported to Windows 95/98. The user specifies a temperature, pressure, and substance amounts (in moles of any chemical formula in C–H–O–Si–Al–Ti–Fe–Mn–Mg–Ca–Na–K system) to this program, then it calculates the stable mineral assemblage, mineral amounts, and gas composition under the given conditions using Gibbs free energy minimization method with the Holland and Powell (1990) data set. Searching algorithm for the stable mineral assemblage is the Metropolis Monte Carlo method. The coding language is C++, and experimental object oriented programming style is adopted to make the main program part as a class library. Model-dependent functions such as fugacity coefficients and activities are implemented as virtual methods of the “systems” class, so they can be easily changed as methods of inherited class from the “systems” class. These characteristics are aimed for a future “simulation kit”.     

Pseudo-transient continuation-based variable relaxation solver in nonlinear magnetohydrodynamic simulations

Efficient and robust Variable Relaxation Solver, based on pseudo-transient continuation, is developed to solve nonlinear anisotropic thermal conduction arising from fusion plasma simulations. By adding first- and/or second-order artificial time derivatives to the system, this type of method advances the resulting time-dependent nonlinear PDEs to steady state, which is the solution to be sought. In this process, only the stiffness matrix itself is involved so that the numerical complexity and errors can be greatly reduced. In fact, this work is an extension of integrating efficient linear elliptic solvers for fusion simulation on Cray X1E. Two schemes are derived in this work, first- and second-order variable relaxations. Four factors are observed to be critical for efficiency and preservation of solution's symmetric structure arising from periodic boundary condition: refining meshes in different coordinate directions, initializing nonlinear process, varying time steps in both temporal and spatial directions, and accurately generating nonlinear stiffness matrix. First finer mesh scale should be taken in strong transport direction; next the system is carefully initialized by the solution with linear conductivity; third, time step and relaxation factor are vertex-based varied and optimized at each time step; finally, the nonlinear stiffness matrix is updated by just scaling corresponding linear one with the vector generated from nonlinear thermal conductivity.     

中原经济区建设与河南高职教育发展方式研究

面对中原经济区建设的现状,河南高职教育也应紧跟时代步伐,切实转变发展方式,坚持重质量、重内涵,增强政府的主导作用、优化专业结构、创新办学模式,实现高职教育的健康、协调、持续发展,从而为中原经济区建设提供强有力的人才支撑。     

基于多媒体网络的综合英语多元互动教学模式研究

互动在语言教学中由来已久,随着多媒体网络技术的迅猛发展,多元互动教学模式的可行性和优越性日益凸显出来。本文详细阐述了多元互动教学模式在综合英语教学中的建构,着重探讨了基于多媒体网络的综合英语多元互动的教学实践,旨在探讨如何通过有效的教学互动以达到优化教学效果的目的。     

对石油钻井队正职干部的考核工作初探

科学考核和评价干部,是激励干部创先争优,推进企业绩效持续提升、不断跨越的有效途径,是加强干部队伍建设的基础性工作。胜利油田渤海钻井一公司党委对井队正职的分类量化考核进行大胆探索,制定了《钻井队正职干部综合考评规定(暂行)》,建立健全了井队正职干部能上能下的岗位管理机制,形成创先争优的良好氛围,推进"人才强企"战略实现跨越式发展。     

防空杀伤区拟合算法设计

为了给防空武器系统的使用提供更加有力的依据,在防空仿真系统的基础上,针对典型防空杀伤区的空间特性,设计了一种等间隔连续分割然后拟合求杀伤区的算法.算法先对防空理论杀伤区空间区域进行分割划分,求得一系列离散点,根据仿真系统得到的仿真数据计算这些离散点的杀伤概率,根据给定杀伤概率的要求拟合杀伤区.通过多次的仿真实验结果表明了算法的正确性和合理性,在防空杀伤区的计算上有一定的可行性.