分形理论及其在薄膜微结构研究中的应用     

吕建国  蔡琪  宋学萍  孙兆奇 《安徽教育学院学报》2007,25(3):24-27

介绍分形的基本概念以及几种常用的计算简单分形维数的方法,用分形研究Au-MgF2纳米金属介质复合薄膜中Au颗粒和半连续Ag膜中Ag小岛的分布规律。结果表明:复合薄膜中Au颗粒的分形维数随Au含量的增加由1.5516逐渐增大到1.7671,表明金属介质复合薄膜中Au颗粒的平均尺寸随着Au含量的增加而增大;半连续Ag膜中Ag小岛的分形维数随厚度的增加从1.4051增大到1.7428,说明半连续Ag膜的覆盖率随着其厚度的增加而增大。这一结果与实验结果一致,因此分形可以用来定量表征薄膜显微结构的演化规律。  相似文献   

分形模拟粗糙面绘图分析     

王备战  韩运侠  郑爱贞 《洛阳师范学院学报》2006,25(5):49-50

基于二维带限维尔斯特拉斯分形函数衍变建立的模拟粗糙面模型,通过计算机绘图模拟,验证了该模型能很好的模拟实际粗糙面.结论对于使用该模型进一步研究海平面,大气湍流等实际粗糙面的电磁波的传播、散射提供了佐证.  相似文献   

基于核心素养培养的数学课堂教学策略探析     

黄宝华 《成才之路》2020,(5):60-61

教师要以数学核心素养内涵及本质为出发点,以创新式教学策略引领学生自主探究思维,帮助学生梳理解题思路,吸收并建构科学化、系统化的数学知识体系,让学生在条分缕析中夯实数学能力。基于核心素养培养的数学课堂教学策略有:以趣促学,巧妙调动数学思维;情景设问,深化运算实践意识;直观导入,丰富空间维度。  相似文献   

分形与计算机模拟     

翟俊海  王学英 《保定师专学报》2001,14(2):42-44

给出了分形的有关概念，以Koch分形工线为例介绍了用计算机模拟分形图形的方法，给出了画Koch分形的函数代码。  相似文献   

Probability Density Function Method for Observing Reconstructed Attractor Structure   总被引：1，自引：0，他引：1  

陆宏伟  陈亚珠卫青 《上海大学学报(英文版)》2004,8(1):75-79

Probability density function (PDF) method is proposed for analysing the structure of the reconstructed attractor in computing the correlation dimensions of RR intervals of ten normal old men. PDF contains important information about the spatial distribution of the phase points in the reconstructed attractor. To the best of our knowledge, it is the first time that the PDF method is put forward for the analysis of the reconstructed attractor structure. Numerical simulations demonstrate that the cardiac systems of healthy old men are about 6 - 6.5 dimensional complex dynamical systems. It is found that PDF is not symmetrically distributed when time delay is small, while PDF satisfies Gaussian distribution when time delay is big enough. A cluster effect mechanism is presented to explain this phenomenon. By studying the shape of PDFs, that the roles played by time delay are more important than embedding dimension in the reconstruction is clearly indicated. Results have demonstrated that the PDF method represents a promising numerical approach for the observation of the reconstructed attractor structure and may provide more information and new diagnostic potential of the analyzed cardiac system.  相似文献   

An Onto-Semiotic Analysis of Combinatorial Problems and the Solving Processes by University Students     

Juan?D.?GodinoEmail author  Carmen?Batanero  Rafael?Roa 《Educational Studies in Mathematics》2005,60(1):3-36

In this paper we describe an ontological and semiotic model for mathematical knowledge, using elementary combinatorics as an example. We then apply this model to analyze the solving process of some combinatorial problems by students with high mathematical training, and show its utility in providing a semiotic explanation for the difficulty of combinatorial reasoning. We finally analyze the implications of the theoretical model and type of analysis presented for mathematics education research and practice.  相似文献   

时间和环境因素对LOM原型件尺寸精度和质量的影响     

张连洪  李华友 《天津大学学报(英文版)》2001,7(3):214-216

为考察 L OM原型件尺寸稳定性 ,研究了时间和环境因素对其尺寸精度和质量变化的影响效果 .结果表明 ,LOM原型件尺寸和质量呈增加趋势 ,其主要原因是成型后的弹性恢复和吸湿 ,且主要表征为 Z(高度 )方向的尺寸增长 .原型件结构的自约束性可有效减小 Z向尺寸增长  相似文献   

Referential perspective and instruction: A study on teacher-student interaction and text remembering     

Santamaría  Andrés  de la Mata  Manuel L. 《Instructional Science》2002,30(2):129-152

The aim of this paper is to study the role ofteacher-student interaction, in the acquisitionof text comprehension and memory skills from asocio-cultural approach. In our view, one ofthe most important areas of neglect in cognitive research in this field is the interactional nature of that development. We intend to establish the way in which teacher-student interaction and, specially, the use of some specific semiotic means mayfacilitate the acquisition and internalizationof general strategies for understanding andremembering expository texts. The role ofreferential perspective (Wertsch, 1989) in theinternalization of complex text study actionsis analysed.The task was to study three expository textsthat were similar in their structure. Thecontent of the texts was analysed in terms ofidea-units (Meyer, 1984). Each text was formedby idea-units from three different levels: mainideas, secondary ideas and details. A categorysystem for the analysis of study and recall ofthe text is developed. In the study phase theanalysis proceeded in two steps: study actionsand text ideas. In the recall phase, two types ofindexes (number of ideas and degree ofclustering) were considered. For the analysisof instructional actions, both the nature ofinstruction and referential perspective wasrecorded.  相似文献   

幂等距阵的对角化问题     

谢宁波  宋兴军 《齐齐哈尔师范高等专科学校学报》2002,21(3):23-24

本对幂等距阵的对角化给出两种证明，并利用距阵的秩来求线性变换的核和像的维数。  相似文献   

试析符号学的对话性     

王艳 《连云港职业技术学院学报》2006,19(3):49-52

符号学研究不应固守那种静态的、独白式的思维方式和研究方法,而应加强“对话”意识,重视一切形态的符号意指活动和具体的、开放的意指过程,以及此过程中主体的自我对话认知和主体与主体之间的对话认知,只有这样才能深入了解符号的运作规律。  相似文献