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巧用二次曲面的切平面方程
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作者 刘长文 王道林 李全忠 《山东农业大学学报(自然科学版)》 CSCD 北大核心 2003年第3期416-418,共3页
本文利用二次曲面上任意一点P0 (x0 、y0 、z0 )处的切平面的统一方程 (用x0 x、y0 y、z0 z、12 (x0 y +xy0 )、12 (x0 z +xz0 )、12 (y0 z +yz0 )、12 (x0 +x)、12 (y0 +y)、12 (z0 +z)分别替换二次曲面方程中的x2 、y2 、z2 、xy、xz... 本文利用二次曲面上任意一点P0 (x0 、y0 、z0 )处的切平面的统一方程 (用x0 x、y0 y、z0 z、12 (x0 y +xy0 )、12 (x0 z +xz0 )、12 (y0 z +yz0 )、12 (x0 +x)、12 (y0 +y)、12 (z0 +z)分别替换二次曲面方程中的x2 、y2 、z2 、xy、xz、yz、x、y、z项 ) ,给出了切点面的方程 .从而使得与二次曲面的切平面相关的某些问题变得简单易解 ,在算例部分提出并解决了几个具有一定难度的问题。 展开更多
关键词 二次曲 切平方程 切点面 算例部分
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Two Theorems on Volume and Dihedral Angles of a n-dimensional Simplex
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作者 杨世国 《Chinese Quarterly Journal of Mathematics》 CSCD 1993年第2期87-93,共7页
In this gape, we obtain thorem I on volum of a n-dirmensional simplex and theorem 2 on dihedral angies of a simplex. Besides. We obtain Vasic inequality in E^n and its extension. The resultsin this paper contain and i... In this gape, we obtain thorem I on volum of a n-dirmensional simplex and theorem 2 on dihedral angies of a simplex. Besides. We obtain Vasic inequality in E^n and its extension. The resultsin this paper contain and improve the results in paper [1], [2], [3], [4]. 展开更多
关键词 SIMPLEX dihedral angle volume.
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Investigations of 3D Surface Roughness Characteristic's Accuracy
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作者 Maris Kumermanis Janis Rudzitis Anita Avisane 《Journal of Mechanics Engineering and Automation》 2013年第10期632-640,共9页
The existing surface roughness standards comprise only two dimensions. However, the real roughness of the surface is 3D (three-dimensional). Roughness parameters of the 3D surface are also important in analyzing the... The existing surface roughness standards comprise only two dimensions. However, the real roughness of the surface is 3D (three-dimensional). Roughness parameters of the 3D surface are also important in analyzing the mechanics of contact surfaces. Problems of mechanics of contact surfaces are related to accuracy of 3D surface roughness characteristic. One of the most important factors for 3D characteristics determination is the number of data points per x and y axes. With number of data points we understand its number in cut-off length. Number of data points have substantial influence on the accuracy of measurement results, measuring time and size of output data file (especially along the y-axis direction, where number of data points are number of parallel profiles). Number of data points must be optimal. Small number of data points lead to incorrect results and increase distribution amplitude, but too large number of data points do not enlarge range of fundamental information, but substantially increase measuring time. Therefore, we must find optimal number of data points per each surface processing method. 展开更多
关键词 Surface topography roughness assessment accuracy measurement instruction.
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