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小学“数概念”教学的联结性建构路径
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作者 于勇 《教学与管理》 北大核心 2024年第20期33-37,共5页
数学学习过程不是局限于某一知识点的封闭、点状、线性的学习过程,而是一个纵向重在立序、横向突出贯通、运用走向实践的联结过程。数学教学可通过联结数学史料,追溯本源;联结已有认知,深化理解;联结多元表征,推论内涵;联结认知断点,构... 数学学习过程不是局限于某一知识点的封闭、点状、线性的学习过程,而是一个纵向重在立序、横向突出贯通、运用走向实践的联结过程。数学教学可通过联结数学史料,追溯本源;联结已有认知,深化理解;联结多元表征,推论内涵;联结认知断点,构建体系等实践路径,对“数概念”实施联结性、生长性建构。 展开更多
关键词 “数概念” 数学史 认知经验 多元表征 知识断点 联结性建构
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Mobility and equilibrium stability analysis of pin-jointed mechanisms with equilibrium matrix SVD
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作者 LU Jin-yu LUO Yao-zhi LI Na 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第7期1091-1100,共10页
Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equil... Under certain load pattern, the geometrically indeterminate pin-jointed mechanisms will present certain shapes to keep static equalization. This paper proposes a matrix-based method to determine the mobility and equilibrium stability of mechanisms according to the effects of the external loads. The first and second variations of the potential energy function of mechanisms under conservative force field are analyzed. Based on the singular value decomposition (SVD) method, a new crite- rion for the mobility and equilibrium stability of mechanisms can be concluded by analyzing the equilibrium matrix. The mobility and stability of mechanisms can be classified by unified matrix formulae. A number of examples are given to demonstrate the proposed criterion. In the end, criteria are summarized in a table. 展开更多
关键词 Pin-jointed mechanisms Criteria for stability of equilibrium Criteria for mobility Potential energy function Equilibrium matrix. Singular value decomposition (SVD) method
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