带有三点边值问题的分数阶微分方程解的存在唯一性

运用Leray-Schauder抉择定理和Banach压缩映射原理研究了分数阶微分方程三点边值问题解的存在唯一性,给出该问题存在唯一解的充分条件,推广已有的某些结果.     

潜艇追踪问题研究

随着科学技术的发展和反潜作战能力的不断提高,如何做到迅速有效地进行潜艇追踪并将其击中是人们越来越关注的问题。本文针对潜艇追踪问题,首先,对其进行了深入分析并建立了微分方程模型;接着,提出了多种模型求解方法,重点介绍了解析法、欧拉方法和龙格-库塔公式法;然后,利用了MATLAB软件对各种求解方法进行了具体求解,并建立了优化模型来选择和确定最优的求解方法;最后,对潜艇追踪进行了动态模拟演示,使其更直观、生动地观察其运行状态。     

Second language learners' performance in mathematics: Disentangling the effects of academic language features

Several studies have shown that the linguistic complexity of items in achievement tests may cause performance disadvantages for second language learners. However, the relative contributions of specific features of linguistic complexity to this disadvantage are largely unclear. Based on the theoretical concept of academic language, we used data from a state-wide test in mathematics for third graders in Berlin, Germany, to determine the interrelationships among several academic language features of test items and their relative effects on differential item functioning (DIF) against second language learners. Academic language features were significantly correlated with each other and with DIF. While we found text length, general academic vocabulary, and number of noun phrases to be unique predictors of DIF, substantial proportions of the variance in DIF were explained by confounded combinations of several academic language features. Specialised mathematical vocabulary was neither related to DIF nor to the other academic language features.     

平面上拟线性偏微分方程组弱解的有界性

本文假定通常的椭圆条件仅在无穷远处成立,证明了平面上一类二阶拟线性偏微分方程组弱解是有界的。     

Computation of one-dimensional consolidation of double layered ground using differential quadrature method

The authors give the solution to the problem of one-dimensional consolidation of double-layered ground with the use of the differential quadrature method. Case studies showed that the computational results for pore-water pressure in soil layer agreed with those of analytical solution; and that in the computational results for the interface of soil layer also agreed with those of the analytical solution except for the small discrepancies during shortly after the start of computation. The advantages of the solution presented in this paper are that compared with the analytical solution, it avoids the cumbersome work in solving the transcendental equation for eigenvalues, and in the case of the Laplace transform solution, it can resolve the precision problem in the numerical solution of long time inverse Laplace transform. Because of the matrix form of the solution in this paper, it is convenient for formulating computational program for engineering practice. The formulas for calculating double-layered ground consolidation may be easily extended to the case of multi-layered soils. Project (No. RC9609) supported by the Zhejiang Provincial Natural Science Foundation of China     

高阶中立型泛函微分方程的非振动解

本文考察方程(x(t)+c(t)x(t-d))~(n)-f(t,x(g_1(t)),…,x(g_m(t))=0的非振动解。首先,在-1相似文献   

Identification of differential item functioning by race and ethnicity in the Childhood Trauma Questionnaire

BackgroundThe accurate assessment of childhood maltreatment (CM) is important in medical and mental health settings given its association to adverse psychological and physical outcomes. Reliable and valid assessment of CM is also of critical importance to research. Due to the potential of measurement bias when comparing CM across racial and ethnic groups, invariant measurement is an important psychometric property of such screening tools.ObjectiveIn this study, differential item function (DIF) by race and ethnicity was tested. Uniform DIF refers to the influence of bias on scores across all levels of childhood maltreatment, and non-uniform DIF refers to bias in favor of one group.MethodParticipants were N=1,319 women and men (M_age=36.77, SD_age=10.37) who completed the Child Trauma Questionnaire-Short Form; 42.7% were women, 57.3% were male; 58.9% were White-American, 22.1% Black-American, and 8.0% as other; 26.3% were Hispanic.ResultsUsing empirical thresholds, non-uniform DIF was identified in five items by race, and no items by ethnicity.ConclusionsUniform DIF is less problematic given that mathematical corrections can be made to adjust scores for DIF. However, non-uniform DIF can usually only be corrected by removing the DIF items from the scale. Further methodological research is needed to minimize measurement bias to effectively assess racially diverse populations.     

微分法在一类特殊常数项级数求和中的应用

本文介绍了一种通过构造幂级数求解常数项级数和的方法。该方法运用逐项微分法将幂级数的收敛和函数转化为相应的常系数线性微分方程,求出微分方程的通解从而得到相应常数项级数之和。并给出了相应的定理和例题来说明这一方法。     

《常微分方程》双语教学实践与问卷调查分析

从课程、学生、教材的选择及课程考核结果,介绍了《常微分方程》双语教学的实践情况。结合调查问卷,详细分析了双语教学过程中出现的问题,并给出了相应的对策。最后,从学生、教师及网络教学服务平台建设等方面给出了一些建议。     

浅谈《微分几何》课程的教与学

根据高等教育必须充分体现＂以应用为目的,以必需够用为度＂的原则,结合自己对微分几何课程的教学实践,从教师教和学生学两方面进行探讨,并提出了具体的教学方法及学生的学习方法,通过本文的论述希望能为教师及学生学习微分几何提供一些参考。