Durrmeyer-Bézier算子收敛阶的新估计

运用概率型算子的概率性质,由Boj anic-Cheng的分解法,研究了有界变差函数f 的 Durrmeyer-Bézier算子收敛阶的精确估计。其研究对于Bézier型算子逼近的研究工作,以及提高运用Bézier法的计算机辅助设计几何造型精度的估计有重要意义。     

一类5阶常微分方程特征值的估计

考虑一类常微分方程的特征值的估计,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。     

高校扩招使得个体就业状况更糟糕吗?

基于高校扩招前后大学生群体的比较,人们普遍认为扩招后大学生的就业状况变差了。我们在认同这一观点的基础上,着重考察了另外一个问题:在教育扩张的背景下,如果个体读大学与假设他不读大学相比,就业状况会如何?利用扩招前后两个年份的全国性人口调查数据,采用描述性统计和基于倾向分匹配估计的方法对此进行了分析。主要结论是:高校扩招后大学毕业生相对于高中毕业生在就业上仍旧延续了优势地位,并且没有明显的变化,现实中观察到的扩招后大学生失业率的上升更多的是由于个体能力和家庭背景等因素造成的,高校扩招在其中仅起到微弱的作用。其政策含义是,就业政策应更加关注低学历人群的就业和就业保障,我国初中后教育规模的进一步扩张仍具有现实基础。     

计算机自适应考试系统研究

本文结合专家经验确定法和项目反应理论,设计出一种简明、实用的计算机自适应考试系统的试题难度确定方法,同时重点分析计算机自适应考试系统的测试起点、终点选择,选题策略和能力值估计方法。最后列举了一个自适应测试的步骤实例。本系统能够根据不同能力被试者随机选择试题项目,减少了测试长度,与传统在线考试系统相比提高了考试效率。     

Evaluation of treatment effect estimates in single‐case experimental research: comparison of twelve overlap methods and visual analysis

The purpose of this study was to compare 12 commonly‐used nonoverlap methods with each other and with the results of visual analysis. Data were obtained from 25 studies focused on embedded instruction and schema‐based instruction and included a total of 101 graphs. Treatment effect estimates using 12 nonoverlap methods were calculated for each graph by hand or using an online calculator. Five experts conducted visual analysis of each graph. Results showed that strong agreements existed between visual analysis and PND, Tau_NOVLAP and Tau‐U when raw data were analysed, and PND, PNCD and PEM‐T when categorised data were analysed. Of the 12 methods investigated, PND had the highest agreement rate with visual analysis, followed by PEM‐T, PAND, PNCD, IRD, NAP and Tau_NOVLAP. Overall, visual analysis appeared to be more conservative, as most nonoverlap methods overestimated the treatment effect. Additional research is needed to replicate and potentially validate the findings of this study.     

Evaluating population estimates in the United States: Counting the population between the censuses

Population estimates play an important role in shaping public policy and research. Librarians as well as users need to be proficient in evaluating the limitations of the statistic. This article provides a brief history of population estimates as well as a discussion of general principles for evaluating and understanding population estimates.     

The Mathematics of Estimation: Possibilities for Interdisciplinary Pedagogy and Social Consciousness

The purpose of this article is to report on the importance of providing pre-service and in-service teachers with experience and specific training in critical thinking skills. The essential concepts in elementary mathematics curricula can be augmented to include and cultivate critical thinking skills that have tremendous ramifications for future leaders and for those who move on to more technical training. A sample problem, along with pre-service teacher responses, is used here to show the necessity and importance of this kind of training as the responses show clear evidence of a certain naivete on the part of these college level students. The responses do show evidence of budding social conscience in the students, but the level of expertise in critical thinking is not at all sophisticated. We discuss and explore the implications of our approach.     

强激光场下NH3分子波包演化和粒子数布居研究

计算了质量加权坐标系下NH3分子基态、激发态和离子基态势能面,研究了基态波包演化情况以及波包在基态激发态之间布居情况．通过研究证实了NH3分子存在拉伸振动,同时发现基态、激发态粒子数布居存在拉比振荡现象．     

膜振动一致椭圆型问题的加权特征值上界估计

考虑膜振动一致椭圆型问题的加权特征值上界估计,利用试验函数、分部积分法、Rayleigh定理以及不等式估计等方法,建立了用前n个特征值来估计第n＋1个特征值的上界估计,其估计系数与区域度量无关．这个结果在力学和物理学中有着广泛的应用．     

孙子“庙算”思想溯源

从中国传统文化继承与创新的角度,追溯了孙子"庙算"思想的理论源头,论述了"庙算"理论与八卦、《周易》之间的内在逻辑关系。通过比较,阐述了孙子"庙算"体系的理论贡献和"庙算"要素的科学内涵以及古人从"占卜"到"庙算"的历史发展轨迹,从而进一步揭示了孙子"庙算"思想的历史地位和时代价值。