推力波箔轴承的理论分析和试验研究

本文对半径比为0.3、0.5和0.7三种尺寸的推力波箔轴承进行了理论计算。并对其中的二种进行了参数优化。计算结果绘成了便于设计应用的图线,并对设计图线各参数间的关系作了讨论。文中还介绍了该类轴承的试验装置和试验方法,给出了一组试验数据。并将理论结果与试验结果作了比较。最后用实例说明了设计图线的使用方法。     

基于Mathematica求解时滞方程

结合具体的例子,主要介绍了运用Mathematica7求解时滞微分方程的方法,以及如何通过软件探讨时滞方程数值解对初始函数的敏感性与由于时滞的增加引起解的变化.     

A Cautionary Note on Beta Families of Distributions and the Aliases Within

In this note, we examine the four parameter beta family of distributions in the context of the beta-normal and beta-logistic distributions. In the process, we highlight the concept of numerical and limiting alias distributions, which in turn relate to numerical instabilities in the numerical maximum likelihood fitting routines for these families of distributions. We conjecture that the numerical issues pertaining to fitting these multiparameter distributions may be more widespread than has originally been reported across several families of distributions.     

三种离散型随机变量k阶中心矩递推计算方法

构造一类特殊多项式及级数,由此推导了二项分布,泊松分布及几何分布Ｋ阶中心矩的递推计算公式,得到了这几个公式的统一形式。     

Kernel-based global MLE of partial linear random effects models for longitudinal data

Random effects models have been playing a critical role for modelling longitudinal data. However, there are little studies on the kernel-based maximum likelihood method for semiparametric random effects models. In this paper, based on kernel and likelihood methods, we propose a pooled global maximum likelihood method for the partial linear random effects models. The pooled global maximum likelihood method employs the local approximations of the nonparametric function at a group of grid points simultaneously, instead of one point. Gaussian quadrature is used to approximate the integration of likelihood with respect to random effects. The asymptotic properties of the proposed estimators are rigorously studied. Simulation studies are conducted to demonstrate the performance of the proposed approach. We also apply the proposed method to analyse correlated medical costs in the Medical Expenditure Panel Survey data set.     

Generalized Estimating Equations to Binary Probit Model

Inference in generalized linear mixed models with multivariate random effects is often made cumbersome by the high-dimensional intractable integrals involved in the marginal likelihood. This article presents an inferential methodology based on the generalized estimating equations for the probit latent traits models. This method belonging to the broad class of semi parametric approaches involves marginal joint moments of order 1 and 2, which has analytical expression. The different results are illustrated with a simulation study.     

一维六方准晶中正方形孔边双裂纹的反平面问题

本文通过引入合适的保角映射函数,充分利用复变函数方法和解析函数理论,研究一维六方准晶中正方形孔边两不对称裂纹的反平面问题。在孔周及裂纹面为自由表面的假设下,结合数值保角映射函数和复变函数中的Cauchy积分公式,得到声子场和相位子场耦合作用下复势函数的近似解,并且给出裂纹尖端应力强度因子和能量释放率的显示表达式。数值算例讨论裂纹长度和正方形边长对场强度因子的影响规律。     

黄土泥岩接触面滑坡工程防护的数值模拟

以晋陕蒙接壤区黄土泥岩接触地带滑坡为工程研究背景,分析研究黄土泥岩接触面滑坡的工程防护。通过室内试验确定了黄土的基本物理力学参数。利用FLAC2D数值软件,对地区常见的挡墙和锚索工程防护措施,针对坡脚为15°和25°的滑坡模型进行了工程防护的数值模拟,对比其防护效果,并给出工程建议。     

浅论数值线性代数课程的教学改革

数值线性代数是一门介绍科学计算核心理论和基本方法的数学课程。根据数值线性代数课程和当前学生的特点,从教学内容、教学方法、考核形式三方面对该课程的教学改革进行了初步探讨与研究。