关键词： breast cancer screening   tumor size   tumor growth rate   mathematical model   simulation  

摘要： This paper presents a mathematical algorithm that computes the sizes and growth rates of breast cancer detected in a hypothetical population that is screened for the disease. The algorithm works by simulating the outcomes of the hypothetical population twice, first without screening and then with screening. The simulation without screening relies on an underlying model of the natural history of the disease. The simulation with screening uses this natural history model to track the growth of breast tumors backwards in the time starting from the time they would have been detected without screening. The method of tracking tumor growth backward in time is different from methods that track tumor growth forward in time by starting from an estimated time of tumor onset. The screening algorithm combines the natural history model, the method tracking of tumor growth backward in time, the age group, the interval between screening exams, and the detection threshold of the screening exam to compute the joint distribution of tumor size and growth rate among screen-detected and interval patients. The algorithm also computes the sensitivity and leadtime distribution. It allows for arbitrary age groups, detection thresholds and screening intervals and may contribute to the design of future screening trials. (C) 2001 Published by Elsevier Science Inc.

关键词： 贝叶斯网络   参数估计   学习算法   数据处理   电子商务  

摘要： 本文论及了对 jie cheng等人提出的三阶段学习算法的一种改进方法 ,进而论及利用现有 BN模型、参数及新数据实现动态参数更新及在线学习的方法。并给出了仿真实验。

关键词： parallel algorithms   randomized algorithms   linear systems   maximum linear independent subset   matrix rank   structured matrices   Toeplitz matrices   displacement rank   output sensitive   bipartite matching  

摘要： This paper gives output-sensitive parallel algorithms whose performance depends on the output size and are significantly more efficient tall previous algorithms for problems with sufficiently small output size. Inputs are n x n matrices over a fixed ground field. Let P(n) and M(n) be the PRAM processor bounds for O(log n) time multiplication of two degree n polynomials, and n x n matrices, respectively. Let T(n) be the time bounds, using M(n) processors, for testing if an n x n matrix is nonsingular, and if so, computing its inverse. We compute the rank R of a matrix in randomized parallel time O(log n + T (R) log R) using nP(n) + M(R) processors (P(n) + RP(R) processors for constant displacement rank matrices, e.g., Toeplitz matrices). We find a maximum linearly independent subset (MLIS) of an n-set of n-dimensional vectors in time O(T(n)log n) using M(n) randomized processors and we also give output-sensitive algorithms for this problem. Applications include output-sensitive algorithms for finding: (i) a size R maximum matching in an n-vertex graph using time O(T(R) log n) and nP(n)/T(R) + RM(R) processors, and (ii) a maximum matching in an n-vertex bipartite graph, with vertex subsets of sizes n(1) less than or equal to n(2), using time O(T(n(1)) log n) and nP(n)/T(n(1)) + n(1) M(n(1)) processors. (C) 2001 Academic Press.

关键词： 数学模型   遗传算法   稳定域   优化   稳健性   自动控制系统  

摘要： 探讨用遗传算法对数学模型进行优化。考虑到控制系统稳健性的要求 ,用遗传算法寻找出控制系统最佳稳定域 ,实现控制系统数学模型的寻优。阐述了用遗传算法求解问题的步骤和参数的取值 ,并用仿真实验对优化结果进行了检验。结果表明 :在控制系统数学模型的优化中 ,遗传算法具有其他算法无可比拟的优越性。

关键词： 数学教学   培养   估算能力   学生   整数估算法   中间数估算法   个位数估算法   小学   自我估算法  

摘要： 对于学生回答问题、作业、考试中出现的不同类型的差错，教师批改后的讲评往往不能及时满足学生渴求知识的迫切欲望，延缓了信息反馈，实践证明，“自我估算”对培养学生估算的意识和能力，使他们能适时找出自己解题中的偏差，重新思考和演算，预防和减少差错的发生，提高解题正确率是至关重要的。“自我估算”主要有以下几种方法。

关键词： 数学模型   控制算法   动态数据交换   计算机控制系统  

摘要： 主要介绍了在现有计算机控制系统中 ,通过动态数据交换方式来实现大型数学模型及复杂控制算法。探讨了动态数学交换在工业控制系统中的应用及实现。并给出了该方法在几个典型控制系统中的应用实例。

关键词： 灰色理论   模糊数学   综合评价   集成算法  

摘要： 依据灰色理论和模糊数学 ,提出了一种新的从定性到定量转换的综合集成算法 ,它是由Delphi、AHP、灰色关联分析、模糊评判综合集成而成的 .文中介绍了它的原理 ,给出它的构成方法 。

关键词： mathematical programs with equilibrium constraints   linear complementarity   extreme point  

摘要： In this paper, we present a new extreme point algorithm to solve a mathematical program with linear complementarity constraints without requiring the upper level objective function of the problem to be concave. Furthermore, we introduce this extreme point algorithm into piecewise sequential quadratic programming (PSQP) algorithms. Numerical experiments show that the new algorithm is efficient in practice.

关键词： 操作系统   进程   调度算法   性能评价  

摘要： 通过建立调度算法的数学模型 。

关键词： Monte Carlo algorithms   Markov chain   resolvent MC (RMC) algorithm  

摘要： In this paper, we consider Monte Carlo (MC) algorithms based on the use of the resolvent matrix for solving linear algebraic problems. Estimates for the speedup and efficiency of the algorithms are presented. Some numerical examples performed on cluster of workstations using MPI are given. (C) 2001 IMACS. Published by Elsevier Science B.V. All rights reserved.