EXACT P‐VALUES FOR DISCRETE MODELS OBTAINED BY ESTIMATION AND MAXIMIZATION

In constructing exact tests from discrete data, one must deal with the possible dependence of the P‐value on nuisance parameter(s) ψ as well as the discreteness of the sample space. A classical but heavy‐handed approach is to maximize over ψ. We prove what has previously been understood informally, namely that maximization produces the unique and smallest possible P‐value subject to the ordering induced by the underlying test statistic and test validity. On the other hand, allowing for the worst case will be more attractive when the P‐value is less dependent on ψ. We investigate the extent to which estimating ψ under the null reduces this dependence. An approach somewhere between full maximization and estimation is partial maximization, with appropriate penalty, as introduced by Berger & Boos (1994, P values maximized over a confidence set for the nuisance parameter. J. Amer. Statist. Assoc. 89 , 1012–1016). It is argued that estimation followed by maximization is an attractive, but computationally more demanding, alternative to partial maximization. We illustrate the ideas on a range of low‐dimensional but important examples for which the alternative methods can be investigated completely numerically.     

粉煤灰对高强混凝土性能的影响

在泵送混凝土中掺入适量的粉煤灰,特别是与减水剂复合使用时,不仅经济效益显著,而且能改善混凝土的性能.研究了粉煤灰高强混凝土中粉煤灰的细度、掺量对混凝土流动性、可泵性及强度的影响,最后给出了煤灰在高强混凝土中的最优掺量,可为工程应用借鉴.     

Semiparametric Mixtures of Generalized Exponential Families

Abstract.  A semiparametric mixture model is characterized by a non-parametric mixing distribution Q (with respect to a parameter θ ) and a structural parameter β common to all components. Much of the literature on mixture models has focused on fixing β and estimating Q . However, this can lead to inconsistent estimation of both Q and the order of the model m . Creating a framework for consistent estimation remains an open problem and is the focus of this article. We formulate a class of generalized exponential family (GEF) models and establish sufficient conditions for the identifiability of finite mixtures formed from a GEF along with sufficient conditions for a nesting structure. Finite identifiability and nesting structure lead to the central result that semiparametric maximum likelihood estimation of Q and β fails. However, consistent estimation is possible if we restrict the class of mixing distributions and employ an information-theoretic approach. This article provides a foundation for inference in semiparametric mixture models, in which GEFs and their structural properties play an instrumental role.     

具有时滞的通有连续时间神经网络的指数稳定性

研究了具有时滞的通有连续时间神经网络的稳定性问题;利用常数变易法并结合不等式分析技巧,获得了具有时滞的通有连续时间神经网络的平衡点全局指数稳定和全局k-指数稳定的判别准则;推广了文献［1］的主要结果。     

大城市住房价格影响因素的动态分析

本文以状态空间的可变参数模型为分析视角,对1998-2010年南京市住房价格变动的影响因素进行实证分析。在多变量分析框架下,根据Kalman滤波法,运用样本空间为13年的时间序列数据对参数进行连续地估计,并对其波动进行了阶段性动态分析。实证结果显示:从空间状态模型来看,市场环境的改变,如城市地区生产总值、城镇居民可支配收入、房地产开发投资额、金融机构存款余额、利率的变化、预期的转变等,住房销售价格都会通过供给与需求的后续调整来得到表现。最后,本文针对实证分析结果提出了若干建议。     

早期在华传教士"独厚儒学"原因初探

受文艺复兴和宗教改革的影响和怀着对中华悠久文明的敬仰,以及出于发展自身、与新教抗衡之目的,以意大利耶稣会会士利玛窦为代表的基督教士在明末清初来华传教。在传教期间,他们基于传教现实和教义融合的考虑,“借儒宣教”、“独厚儒学”,成功地促成了中西哲学思想的一次大融合。他们的传教策略与在传统儒学接触中所采取的承认、包容和尊重态度对于我们今天的中西方文化交流有巨大的启示作用。     

"五行配五"的文化含义及其科学价值

“五行配五”是中国古代文化的重要组成部分,也是中国古代哲学思想的基础与精髓,“五行配五”文化的基本含义及其科学价值已渗透到中国古代文化的天文、历法、人的思维模式、礼数、医学、音乐等各个领域,对中国古代文化的发展有着极其重要的影响,并有极其重要的科学价值。     

工艺参数对防眩板注射残余应力的影响分析

残余应力会导致注塑制品出现应力痕、应力开裂,翘曲变形和后变形等问题,进而影响制品寿命,光学性能,电学性能和物理性能等。以防眩板为模型,利用Moldflow 软件采用有限元方法,系统分析了模具温度、熔体温度、注射速率、保压压力及玻璃纤维含量对残余应力的影响。结果表明,随注射速率和模具温度的增加残余应力增加,随保压压力、玻璃纤维含量和熔体温度的增加残余应力减小,但各因素对残余应力的影响并不一样,按其敏感程度依次是熔体温度、玻璃纤维含量、保压压力、注射速率及模具温度。     

Performance of some new Liu parameters for the linear regression model

Abstract

This article introduces some Liu parameters in the linear regression model based on the work of Shukur, Månsson, and Sjölander. These methods of estimating the Liu parameter d increase the efficiency of Liu estimator. The comparison of proposed Liu parameters and available methods has done using Monte Carlo simulation and a real data set where the mean squared error, mean absolute error and interval estimation are considered as performance criterions. The simulation study shows that under certain conditions the proposed Liu parameters perform quite well as compared to the ordinary least squares estimator and other existing Liu parameters.     

CBN刀精车GCr15轴承钢的试验研究

本文利用正交试验法,通过用ＣＢＮ刀对ＧＣｒ１５轴承钢精车切削试验并对试验数据进行了多元线性处理,得出了在此切削条件下的切削用量三因素与刀具耐用度的Ｔａｙｌｏｒ公式,为解决难加工材料ＧＣｒ１５轴承钢的精车及实际生产提供了经验。