Application of the Bayes’ theory to the failure rate evaluation of electrical apparatus

The Weibull distribution has been widely used in reliability fields. A mixed Weibull distribution represents a popu- lation that consists of several Weibull subpopulations. In this paper, a new approach which combines the least-squares method with Bayes’ theorem, takes advantage of the parameter estimation for single Weibull distribution is developed to estimate the pa- rameters of each subpopulation. The estimates given by this paper also satisfy the maximum likelihood equation. The estimates of the failure rate of the mixed Weibull population are given. An actual test data is computed by using the proposed method. The Kolmogorov-Smirnov goodness-of-fit test turns out that the proposed method yields more accurate result.     

基于行处理的SAGE算法在PET图像重建中的应用

运用基于行处理(RA)的"单块"投影子集法改进了空间交替广义期望最大(SAGE)算法的收敛性. 新的RA-SAGE算法以正交单投影序列的方式对投影数据进行处理, 以减少投影间的相关性, 达到加速收敛的效果. 此外, 在迭代搜索同时, 新算法结合了超松弛变量, 使其能快速接近全局最大似然解. 实验中, 运用RA-SAGE与SAGE对正电子发射断层(PET)进行了重建. 结果表明,RA-SAGE收敛性能比SAGE优越, 且重建图像质量较高.     

CM模式的项目管理研究

CM模式是20世纪80年代开始在国际上出现的一种新的项目管理模式。对CM模式和传统的管理模式进行了比较；研究了CM模式的特点，提出了工程项目中应用CM模式的关键问题和解决方法。     

从听课评估向教师自我反思模式的转化

以听课评估教师的传统作法已逐显其弊端，本文提出应以“自我反思实践”为指导，促使教师贯彻学生参与，活动方式和信息输出三项最大化原则，从而达到提高教学质量，完善教师评估体系的目的。     

Examining Normality in Incomplete Data Sets: A Note on a Multiple Testing Approach

A multiple testing procedure for examining the assumption of normality that is often made in analyses of incomplete data sets is outlined. The method is concerned with testing normality within each missingness pattern and arriving at an overall statement about normality using the available data. The approach is readily applied in empirical research with missing data using the popular software Mplus, Stata, and R. The procedure can be used to ascertain a main assumption underlying frequent applications of maximum likelihood in incomplete data modeling with continuous outcomes. The discussed approach is illustrated with numerical examples.     

求非负矩阵最大特征值的一种平滑算法

推广了文[1]的结果，给出了非负矩阵最大特征值的一种平滑算法。     

离散型随机变量常见分布列中的极值

讨论了分布函数p(ξ=k)=p(k)的极值问题,并给出了一种求离散型分布列函数极值的一种简便算法--比值法.     

Influence of Zeotropic Mixtures'''' Temperature Gliding on the Performance of Heat Transfer in Condenser or Evaporator

Many zeotropic refrigerant mixtures are proposed as alternatives to some chlorofluorocar-bons (CFCs) and hydrochlorofluorocarbons ( HCFCs). An advantage of zeotropic mixtures is the possibility of reduction in entropy generation by matching the temperature glidings of refrigerant and heat-transfer fluid in both condenser and evaporator. Zeotropic mixtures are compared with pure re-frigerants to evaluate their exergetic losses. On the other hand, the special phenomena which result from temperature gliding are proved by experiments. A simple equation is obtained, to evaluate dif-ferent zeotropic mixtures' exergetic losses. The maximum flow rate of heat-transfer fluids is found in order that refrigerants phase change can be completed. Lastly, some examples of zeotropic mix-tures ( R407C, R405A and R414B) are given, and their exergetic losses and maximum flow rate of heat-transfer fluids in condenser are forecasted.     

理财目标与企业生命周期

企业理财目标是在一定历史条件下,财务主体进行理财实践活动所希望达到的预期结果,也是解决企业财务管理的根本方向.它反映并体现出企业经理阶层的经营哲学和管理理念.但企业的理财目标并不是一成不变的.企业生命周期不同阶段的特点和管理目标对企业理财目标的确立具有重要的影响.     

先验概率对最大似然法提取土地利用现状信息精度的影响

最大似然分类法是提取土地利用现状信息时常用的一种遥感分类技术,但研究者分类前无法确切知道各类别的先验概率,因此先验概率是最大似然分类法的主要难点之一.该文从理论上分析了先验概率对最大似然分类法分类结果生产者精度、使用者精度、总精度和kappa指数的影响,提出运用循环迭代法来消除先验概率对最大似然分类法分类结果的影响,并指出了循环迭代法能够进行的条件.最后以郑州市为例进行了实证研究.研究表明:运用循环迭代法进行最大似然法分类保证了错分损失最小,可提高遥感影像总分类精度,但对不同分布面积的类别的分类精度影响不一样:对于分布面积大于平均值的类别,一般会提高其生产者精度,但会使使用者精度降低,使得分类面积大于实际面积;分布面积小于平均值的类别,一般会提高其使用者精度,但会使生产者精度降低,使得分类面积小于实际面积.