关键词： 信息检索   参数学习   概率模型   遗传算法   适应函数  

摘要： 信息检索系统中的参数设定在很大程度上决定着系统的检索性能.参数的数据相关性和敏感性使得经验值往往不可靠.另一方面,由于在检索过程中缺乏当前查询的相关文档信息,因而不可能进行有指导的参数学习.因此,自动无指导的参数学习方法是极为必要和重要的.首先考察传统上根据经验值设定固定的系统参数的效果,结果表明其泛化能力差,效果不稳定且不可靠.其次,提出一种使用遗传算法进行动态参数学习的方法.在TREC11,TREC10和TREC9三组大规模Web标准测试数据集上进行了实验,数据集规模均超过10GB.实验结果表明,经过动态参数学习,系统性能总是能够接近甚至达到可能实现的最优性能.

关键词： 企业资源规划   供需链管理   笛卡尔乘积   二叉树  

摘要： 本文对数学算法在企业资源规划二次开发中的应用进行了研究。文章把计算上的需求和数学上模型结合起来进行了阐述，其中的笛卡尔乘积在处理数据的上有很深的指导和应用意义，同时在处理算法时，把系统的需求转化成分析文档，同时应用数学算法思想来优化数学与计算机的关系，在二叉树的处理上加以详细的公式推导来说明数学对于设计程序算法具有很强的指导意义，应用这二者可以很好地处理有关计算机数据库的优化操作，同时借用二叉树的理论可以很好地设计计算机算法，从而达到深刻理解数学算法与计算机理论的目的，进而把计算机与数学算法结合的理论用来指导ERP二次开发工作。

关键词： 供水管网   日用水量预测   管网水力计算   神经网络   蚂蚁算法  

摘要： 随着计算机技术的发展,供水管网建模技术在我国城市数字化系统和供水系统现代化管理中发挥着日益重要的作用.供水管网是供水系统中的重要组成部分,运行复杂且呈现出很强的动态性.基于水力学原理,应用现代计算机技术、通讯技术、管理科学和科学计算等技术建立的供水管网模型可实现对供水信息的收集、加工、储存、计算分析以辅助供水管理、生产调度、优化改扩建、水质控制等等.而供水管网模型应用的前提是较为准确用水量预测和供水管网水力计算.本文承担了国家十五重点科技攻关计划\"城市供水数字化系统研究\"专题,以绍兴供水管网系统为示范工程,对城市日用水量预测和供水管网水力计算的理论和实践进行了深入研究.日用水量预测模型的精度直接影响到供水管网模型的准确性.本文应用神经网络建立日用水量预测组合模型,确定2个隐含层的网络结构,分别采用BP法和蚂蚁算法(AA)对神经网络的权值进行训练,蚂蚁算法在神经网络权值训练上充分的表现出其全局搜索能力与运算速度快的特点,克服了BP易陷于局部极值等缺点,大大提高了神经网络的训练速度.应用在绍兴市日用水量预测中,对残差序列进行分析,表现出了良好的预测精度.本文分析和讨论了传统供水管网水力计算方法,介绍了当前供水管网水力计算的一些方法和步骤,在此基础之上,提出了采用拟牛顿法求解管网节点方程,并针对传统方法的不足,建立了采用蚂蚁算法求解管网节点方程的优化模型,把管网水力计算转化为一种寻优模型.对两类供水管网水力计算求解的方法——拟牛顿法及连续性空间蚂蚁算法进行了研究和探讨,在国内率先将连续性空间蚂蚁算法引入管网水力计算领域,结合拟牛顿法与连续性空间蚂蚁算法各自的优点,提出了供水管网水力计算的嫁接法并编制了相应的计算机程序.模拟管网水力计算数值试验以及实际供水管网模型水力计算的应用表明,嫁接法可显著提高供水管网水力计算求解的速度和质量.

关键词： 数学形态学   储粮害虫   边缘检测  

摘要： 对储粮害虫进行实时监测是非常必要的,其中基于图像识别的检测是目前研究较多的一种方法。本文简述了数学形态学方法,对数学形态学在粮虫图像处理边缘检测中的应用进行了研究。计算表明,该方法较好地解决了粮虫图像的去噪和边缘检测问题。

关键词： LMS算法   数学模型   信干噪比   输出   矩阵理论   波束形成   抗噪性能   干扰信号   仿真结果   仿真验证   一致性  

摘要： 通过对LMS算法的分析及运用矩阵理论,得出了LMS算法波束形成干扰数学模型,并假设信号与干扰互不相关时,得出了输出信干噪比数学模型。在此基础上,进一步分析了算法在无干扰信号时(只有噪声)的抗噪性能,在有干扰时得出了干扰较小和较大时,算法对干扰起的作用是完全不同的这一结论。通过数学仿真验证了仿真结果与理论分析的一致性。

关键词： algorithms   design   theory   performance   formal derivation   libraries   linear algebra   high-performance computing  

摘要： In this article we present a systematic approach to the derivation of families of high-performance algorithms for a large set of frequently encountered dense linear algebra operations. As part of the derivation a constructive proof of the correctness of the algorithm is generated. The article is structured so that it can be used as a tutorial for novices. However, the method has been shown to yield new high-performance algorithms for well-studied linear algebra operations and should also be of interest, to those who wish to produce. best-in-class high-performance codes.

关键词： algorithms   design   theory   performance   application program interfaces   formal derivation   linear algebra   high-performance libraries  

摘要： In this article, we present a number of Application Program Interfaces (APIs) for coding linear algebra algorithms. On the surface, these APIs, for the MATLAB M-script and C programming languages appear to be simple, almost trivial,. extensions of those languages. Yet with them, the task of programming and maintaining families of algorithms for a broad spectrum of linear algebra operations is greatly simplified. In combination with our Formal Linear Algebra Method Environment (FLAME) approach to deriving such families of algorithms, dozens of algorithms for a single linear algebra operation can be derived, verified to be correct, implemented, and tested, often in a matter of minutes per algorithm. Since the algorithms are expressed in code much like they are explained in a classroom setting, these APIs become not just a tool for implementing libraries, but also a valuable tool for teaching the algorithms that are incorporated in the libraries. In combination with an extension of the Parallel Linear Algebra Package (PLAPACK) API, the approach presents a migratory path from algorithm to MATLAB implementation to high-performance sequential implementation to parallel implementation. Finally, the APIs are being used, to create a repository of algorithms and implementations for linear algebra operations, the FLAME Interface REpository (FIRE), which already features hundreds of algorithms,for dozens of commonly encountered linear algebra operations.

关键词： D-modules   solution functor   stratification   Grobner bases  

摘要： Let M be a holonomic D-module on C-n. We give an algorithm to stratify C-n such that on all strata X each restriction (derived inverse image) module H-i (rho(X),C-n(M)) is a connection. For regular holonomic modules this stratifies the solution complex RHom(***) (M-an,O-an) of sheaves of (higher) holomorphic solutions of M. We also give an algorithm to compute the dimensions of the cohomology modules of the solution complex over all strata. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： Invariant algebraic curve   linear algebra   symbolic computations  

摘要： Given a system of two autonomous ordinary differential equations whose right-hand sides are polynomials, it is very hard to tell if any nonsingular trajectories of the system are contained in algebraic curves. We present an effective method of deciding whether a given system has an invariant algebraic curve of a given degree. The method also allows the construction of examples of polynomial systems with invariant algebraic curves of a given degree. We present the first known example of a degree 6 algebraic saddle-loop for polynomial system of degree 2, which has been found using the described method. We also present some new examples of invariant algebraic curves of degrees 4 and 5 with an interesting geometry. [ABSTRACT FROM AUTHOR]

关键词： global roundings   discrepancy  

摘要： We discuss the problem of computing all the integer sequences obtained by rounding an input sequence of n real numbers such that the discrepancy between the input sequence and each output binary sequence is less than one. The problem arises in the design of digital halftoning methods in computer graphics. We show that the number of such roundings is at most n + 1 if we consider the discrepancy with respect to the set of all subintervals, and give an efficient algorithm to report all of them. Then, we give an optimal method to construct a compact graph to represent the set of global roundings satisfying a weaker discrepancy condition. (C) 2004 Elsevier B.V. All rights reserved.