A Viable Alternative to Resorting to Statistical Tables

It is shown in this article that, given the moments of a distribution, any percentage point can be accurately determined from an approximation of the corresponding density function in terms of the product of an appropriate baseline density and a polynomial adjustment. This approach, which is based on a moment-matching technique, is not only conceptually simple but easy to implement. As illustrated by several applications, the percentiles so obtained are in excellent agreement with the tabulated values. Whereas statistical tables, if at all available or accessible, can hardly ever cover all the potentially useful combinations of the parameters associated with a random quantity of interest, the proposed methodology has no such limitation.     

Estimating mixtures of normal distributions via empirical characteristic function

This paper uses the empirical characteristic function (ECF) procedure to estimate the parameters of mixtures of normal distributions. Since the characteristic function is uniformly bounded, the procedure gives estimates that are numerically stable. It is shown that, using Monte Carlo simulation, the finite sample properties of th ECF estimator are very good, even in the case where the popular maximum likelihood estimator fails to exist. An empirical application is illustrated using the monthl excess return of the Nyse value-weighted index.     

小型回转点云的配准研究

针对回转半径较大的小型回转点云配准时其回转特征不明显问题,提出一种先利用最小二乘法计算出点云的拟合平面并将所有点投影到该平面上,再利用滚球算法计算该二维点云数据的边界,并对边界点云进行3次B样条拟合,最后根据B样条曲线的变化特点,找出特征点,并利用特征点进行配准。对于回转半径较大且尺寸较小的回转点云,由 于其回转特性不是非常明显,因此完全依靠其回转特性进行配准,会有一定的难度,所以需要利用其他一些特征进行配准。最后通过三坐标扫描仪获取物体的外表面形状数据,然后进行配合验证,结果表明可以准确获取特征点。该方法可以有效地对小型点云进行配准。     

论《了不起的盖茨比》的"奇特化"艺术

菲茨杰拉德在其代表作《了不起的盖茨比》中对“奇特化”艺术手法的运用极为出色,主要表现为题材的奇特化、奇特化的场景和奇特化的叙述视角等几种形态,从而把一个平淡无奇的三角恋爱故事题材雕刻成了一部充满了被扭曲的浪漫情调的悲剧性作品。     

Mobilizing on Campus: Conservative Movements and Today’s College Students1

Social movement scholars have known for some time that students, and particularly college students, play an important role in modern social movements. Yet the full extent of conservative mobilizing, both today and in the past, is frequently overlooked. This article highlights the critical role college campuses have played in the rise of conservative movements in the United States over the last 40 years. In doing so, it develops a concept of transition points to help explain the mechanisms responsible for the longstanding finding that college students form an important core of many social movements. Transition points are marked by both changes in routines and changes in social network configuration. The utility of the transition point concept is explored through ethnographic and interview data from the American pro‐life movement.     

评析《全新版大学英语听说教程》

从2002年9月起,我校对全体新生试用了《全新版大学英语听说教程》,笔者通过对学生和教师的调查以及对教材的分析,指出其需要改进之处。     

Residuals and leverages in the linear mixed measurement error models

Residuals are frequently used to evaluate the validity of the assumptions of statistical models and may also be employed as tools for model selection. In this paper, we consider residuals and their limiting properties in the linear mixed measurement error models. Also, we develop types of residuals for these models and then review some of the residual analysis techniques. Further, by using the definition of generalized leverage, we derive generalized leverage matrices for identification of high-leverage points for these models. Finally, we analyse a real data set.     

基于FPGA的高频等精度频率计设计与实现

文章介绍了等精度频率计误差分析和实现原理,在Altera新一代FPGA/PLD开发软件QuartusⅡ 中运用硬件描述语言Verilog HDL编程,通过单片机控制EP1 C12Q240I7芯片实现等精度频率计的设计,频率计可通过分频测量800 MHZ～1 400 MHZ之间的高频信号频率,大大提高了测量精度,实验证明测量精度为0.000 03％以下.