Inferences on the Means of Two Log-Normal Distributions: A Computational Approach Test

In this article, we propose a novel approach for testing the equality of two log-normal populations using a computational approach test (CAT) that does not require explicit knowledge of the sampling distribution of the test statistic. Simulation studies demonstrate that the proposed approach can perform hypothesis testing with satisfying actual size even at small sample sizes. Overall, it is superior to other existing methods. Also, a CAT is proposed for testing about reliability of two log-normal populations when the means are the same. Simulations show that the actual size of this new approach is close to nominal level and better than the score test. At the end, the proposed methods are illustrated using two examples.     

疲劳裂纹扩展试验裂纹图像采集系统

针对目前金属疲劳裂纹扩展检测方法存在效率低、操作繁琐、精度不高，不能实现实时性等缺点，文章提出了基 于机器视觉的裂纹检测方法。根据金属疲劳裂纹扩展试验过程中裂纹图像的采集要求，设计了摄像头位置可自动调整 的疲劳裂纹图像采集系统，包括摄像头安装运动装置，裂纹图像采集装置以及摄像头运动控制系统。图像采集装置由高 分辨率黑白面阵CCD摄像头、光学镜头，光源照明装置和图像采集卡组成，前3者安装在摄像头支架上，与摄像头运动 装置相连。摄像头运动装置中的X，Y，，Z轴运动机构由步进电机带动滚珠导轨机构。在基于ARM技术的运动控制系统 的控制下摄像头可沿X，Y，，Z轴作高精度直线运动，实现和试件之间精确位置的调整。实验结果表明，所设计的系统可 采集到疲劳裂纹扩展试验过程中高清晰度、高分辨率的试件裂纹图像，满足下一步裂绞尺寸计算的要求；摄像头运动定 位精度可达到0. 02 mm，满足精确的系统聚焦、位置调整、跟踪采集的要求。     

Random effects regression mixtures for analyzing infant habituation

Random effects regression mixture models are a way to classify longitudinal data (or trajectories) having possibly varying lengths. The mixture structure of the traditional random effects regression mixture model arises through the distribution of the random regression coefficients, which is assumed to be a mixture of multivariate normals. An extension of this standard model is presented that accounts for various levels of heterogeneity among the trajectories, depending on their assumed error structure. A standard likelihood ratio test is presented for testing this error structure assumption. Full details of an expectation-conditional maximization algorithm for maximum likelihood estimation are also presented. This model is used to analyze data from an infant habituation experiment, where it is desirable to assess whether infants comprise different populations in terms of their habituation time.     

Tests for time series of counts based on the probability-generating function

We propose testing procedures for the hypothesis that a given set of discrete observations may be formulated as a particular time series of counts with a specific conditional law. The new test statistics incorporate the empirical probability-generating function computed from the observations. Special emphasis is given to the popular models of integer autoregression and Poisson autoregression. The asymptotic properties of the proposed test statistics are studied under the null hypothesis as well as under alternatives. A Monte Carlo power study on bootstrap versions of the new methods is included as well as real-data examples.     

《墨子》的修辞特点及其英译

《墨子》是先秦时期重要的思想典籍。在文学史上，《墨子》以其突出的逻辑性和语言质朴著称。拟对《墨子》的修辞特点及其英译进行初步比较分析，以期丰富《墨子》的翻译研究。     

英语口语教学刍议

英语口语技能是听、说、读、写四项基本语言技能中很重要的一种技能。要通过课堂教学提高学生口语能力 ,必须从教师、教学方法和学生三方面入手 ,即教师应组织和动员学生积极参与学习 ,采取循序渐进的教学方法 ,发挥学生的主观能动性。学生应有明确的学习目标和计划 ,积极配合老师 ,多说勤炼     

JOURNAL OF UNIVERSITY OF SHANGHAI FOR SCIENCE AND TECHNOLOGY 2002 Vol.24 No.1～4 Total Contents

在学习英语时,中西文化背景的差异,往往会给我们的阅读带来很大的困难。本文拟从词汇的文化内涵、历史典故和西方现代历史文化等三个方面来论述中西文化差异对篇章阅读的影响。     

正式英语的语言特征

正式英语是人们在辩论、演讲、写作和各种仪式等正式场合中使用的标准英语。掌握正式英语的语体风格、词汇色彩和语法结构 ,对英语学习者提高语言交际水平 ,增强英语语感大有裨益     

背诵在英语教学中的重要性

由于交际法的盛行,考试指挥棒的效应以及新的教学模式的出现,目前,我国外语教学对语言输入重视不够,背诵式输入几乎无立足之地。通过理论探索、实验测试和访谈等调查方式证实了背诵对学生写作和口语的提高有着显著的帮助,说明了背诵在中国英语教学应用的重要性,并就此提出,在运用西方教学新理论和现代教学手段时,不可忽视我国传统教学上的优势。