高职“CAD／CAM”教学改革的探讨

根据高职数控技术及应用专业CAD／CAM课程的特点，结合我交几年来的教学改革，系统地介绍了该课程在课程体系，教学方法，实践教学等方面的改革措施及所取得的阶段性成果。     

Student Mobility in Multilevel Growth Modeling: A Multiple Membership Piecewise Growth Model

This study proposes a new model, termed the multiple membership piecewise growth model (MM-PGM), to handle individual mobility across clusters frequently encountered in longitudinal studies, especially in educational research wherein some students could attend multiple schools during the course of the study. A real data set containing some students who switched elementary schools was used to demonstrate and explain the MM-PGM. Parameter and model fit differences were compared between the MM-PGM and two other techniques for handling student mobility: the first school-PGM, which only used school membership at the first measurement occasion, and the delete-PGM, which removed mobile students from the analysis. Results indicated that the three approaches of handling mobile students led to different conclusions about the impact of school-level predictors of growth parameters and the school-level variability in the growth rates. Furthermore, deleting mobile students altered the impact of student-level predictors compared to the other two approaches.     

Enhancing arithmetic in pre-schoolers with comparison or number line estimation training: Does it matter?

Children's intuitive understanding of number, i.e. number sense, is associated with individual differences in mathematics achievement. To investigate the causal association between number sense, traditionally assessed with comparison or number line estimation tasks, and mathematics achievement, often assessed with an arithmetic test, an intervention study was conducted that aimed at training either comparison or number line estimation skills. We contrasted a comparison and number line estimation training. By doing so, we wanted to address the question which intervention had the largest effect on arithmetic. In addition, such a direct comparison between comparison and number line estimation trainings would allow us to get more insight in the association between both tasks. Participants were 151 five-year-olds that were randomly allocated to either an experimental condition (i.e. comparison or number line estimation) or one of the two control conditions (i.e., active control condition and empty control condition) in a pretest-posttest design measuring number knowledge, (non-)symbolic comparison and number line estimation and arithmetic. The results showed that both comparison and number line estimation trainings had a positive effect on arithmetic. However, the absence of transfer effects from one task to another, also suggested that comparison and number line estimation rely on different mechanisms and probably influence arithmetic through different mechanisms.     

Teaching and Learning Number Sense – An Intervention Study of Fifth Grade Students in Taiwan

Two classes (one experimental and one control) in a public elementary school located in southern Taiwan participated in this study. Number sense activities were conducted in the experimental class as supplementary teaching materials, while the control class followed the standard mathematics curriculum. Data indicate that there are statistically significant differences between pretest and posttest (pretest and retention-test) scores for the experimental and control classes at the 0.01 level. The scores for the experimental class increased 44% after instruction (the mean score went from 12.35 to 17.81), while the scores for the control class increased only 10% after instruction (the mean score went from 11.29 to 12.42). Compared to the control class, the experimental class made much more progress on number sense tests. Results indicate that students in the teaching class (not including the students in the low level) advanced in their use of number sense strategies when responding to interview questions. The data demonstrate that the teaching of number sense activities, executed in the experimental class, is effective in developing children's number sense. Furthermore, the results of retention demonstrate that the students' learning was meaningful and significant.     

标准贯入试验检测水泥搅拌桩质量评定标准讨论

通过对工程实例成果的分析,提出了运用标准贯入试验检测水泥搅拌桩质量评定标准的改进方法。     

From electromagnetic bandgap to left-handed metamaterials： modelling and applications

INTRODUCTION Electromagnetic crystal structures (ECSs) offer the opportunity to control and manipulate electro- magnetic wave propagation as a result of their being formed from small-scale periodic geometric struc- tures. This detailed microscopic configuration can be designed to cause the material (macroscopically) to exhibit either effective permittivity or permeability that is negative over a finite frequency range. This modifies the dispersion relation of electromagnetic waves and a …     

六阶常微分方程的特征值的上界估计

考虑六阶常微分方程的特征值的上界估计，利用分部积分、Rayleigh定理和不等式估计等方法，获得了用前n个特征值来估计第n 1个特征值的上界的不等式，其估计系数与区间的几何度量无关，其结果在物理学和力学等领域中应用广泛。     

New results on disturbance zeros of invertible linear multivariable systems

A new results concerning the definitions of disturbance zeros via the concept of minimal order system inverses is presented in this paper. These definitions are then used to develop a new computation algorithm for locating the positions of the ‘disturbance blocking zeros’ in linear multivariable systems. Assignment of disturbance blocking zeros at desired locations in the complex plane plays an important role in rejection of all measurable or un-measurable disturbances, which may affect at the outputs in steady state. Numerical examples are given to illustrate the main results of this paper.     

阶的估计在计算极限中的应用

本文通过对阶的估计的讨论,给出了计算极限的一种方法。     

随机截断时生存函数的核估计

在有截断发生时,构造了生成函数的一种核估计,并对其收敛性及收敛速度问题进行了讨论。