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INTRODUCTION Since the phenomenon of piezoelectricity in natural crystals was discovered in 1880, it has been applied in many fields, such as smart structure, sensing devices and active control, because of its special properties. Combining electrical behavior with mechanical deformation is the special property which attracted great interest of researchers. Many models have been developed for studying piezoelec- tric effects. Dunn and Wienecke (1996) used Green’s functions for transverse… 相似文献
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The present study examined the effectiveness of three instructional treatments which had different combinations of mathematical elements regarding 2-dimensional (2-D) geometry and area measurement for developing 4th-grade children's understanding of the formulas for area measurement and their ability to solve area measurement problems. Participants were 120 fourth graders. The results showed that the enriched curriculum, involving the geometry motions and area measurement connections effectively facilitated children's mathematical judgments and explanations demanding high-level conceptual understanding. The instructional curricula accentuating only 2-D geometry or numerical calculations for area measurement did not exhibit such effectiveness. Interview data revealed that the geometric operations of superimposition, decomposition, re-composition as well as the concept of congruence were deemed essential by children for the conceptualization of the formulas for area measurement. 相似文献
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李荣玲 《临沧师范高等专科学校学报》2007,(4):88-90
化归思想贯穿于解析几何全部内容,是蕴涵在解析几何知识中的主要数学思想方法。文章拟从一节解析几何课为切入点对加强化归思想方法教学,用化归思想统领、整合教材内容作了一些尝试。 相似文献
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汉语中一些常用的学科名称词所表达的概念大部分是外来的,但其本身是否外来词,值得仔细研究。这些词包括数学、几何、物理、化学、逻辑学、经济学等。 相似文献
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The symplectic approach proposed and developed by Zhong et al. in 1990s for elasticity problems is a rational analytical method, in which ample experience is not needed as in the conventional semi-inverse method. In the symplectic space, elasticity problems can be solved using the method of separation of variables along with the eigenfunction expansion technique, as in traditional Fourier analysis. The eigensolutions include those corresponding to zero and nonzero eigenvalues. The latter group can be further divided into α-and β-sets. This paper reformulates the form of β-set eigensolutions to achieve the stability of numerical calculation, which is very important to obtain accurate results within the symplectic frame. An example is finally given and numerical results are compared and discussed. 相似文献
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利用辛几何构作了一个non-Cartesion认证码,计算了它的参数;当编码规则按等概率分布选取时,求出了模仿攻击和替换攻击成功的概率. 相似文献
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利用Galileo变换,建立了Galileo几何.讨论了Galileo平面几何中的距离,直线间的交角问题以及Galileo平面上三角形的一些性质. 相似文献
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射影几何是17世纪数学的最伟大的发现之一。可是与同时代兴起的其它学科相比,它的出现只不过是昙花一现:当笛沙格做出开创性的工作,它再也没有取得什么进展了,并且到这一世纪末,对它的研究已经消失。为什么射影几何在当时的历史背景下没有发展成一门独立的学科,本文对此力求做出一种科学的解释。 相似文献