Hadamard不等式的几种新证明

本利用几何算术不等式，矩阵的分解，行列式的性质给出Hadamard不等式几种新颖，简洁的证明。     

《几何画板》教学实例

利用《几何画板》可以绘制动态直观的立体图形 ,通过图表的动静结合的交互演示 ,可以使枯燥生硬的图形变得生动形象 ,吸引学生的注意与兴趣 ,帮助学生实现从平面图形向立体图形 ,从二维平面向三维空间的过渡 ,培养学生的空间想象力 .本文通过用《几何画板》制作空间图形旋转时的直观图的教学实例 ,说明《几何画板》对优化教学环境 ,提高教学质量的促进作用 .1　旋转正棱柱的制作 (以正三棱柱为例) (如图 1 )1 )作一水平线段ＯＸ ,并在其上取一点Ｍ ,以图 1Ｏ为圆心 ,Ｍ、Ｘ分别为圆周上的点作小圆ｂ和大圆ａ ,过Ｏ作ＯＸ的垂线交大圆于点Ｐ …     

一道解析几何题的多种解法

解析几何是用代数方法研究几何问题的数学分支，其中的题目可涉及到函数，三角，不等式等各种数学知识，这就决定了一个解析几何问题可能有多种不同的解法。解析几何的一题多解可以提高思维的灵活性，拓展人的思路，进而可以提高解决数学综合问题的能力。下面就以一道解析几何题给出几种不同的解法。     

Experimental Study of Effect of Medium Boundary on Light Distribution in Tissue Phantoms

An experimental method for investigating the effect of medium boundary on distributions of light in the biological tissue phantom intralipid is presented. Measurements of distributions of light in intralipid-10% suspensions at 633 nm are described, in which a narrow collimated beam is incident on the surface of the phantoms and into the different depths inside of the phantoms. The experimental results show that the effect of the boundary of the medium on the curves geometry of light distributions is trivial, but the effect on intensity of scattering light is obvious, the maximal relative change of the energy fluence reaches 53.8% and the position of the peak of the energy fluence curve has a shift of 1.1 mm in the reverse direction of incident light for the phantom with albedo a=0.998, and the effect of the boundary is decreased with the increase of the absorption coefficients of tissue phantoms. The experimental results were analysed by the diffusion theory. These studies will be helpful for further understandings of the relation between the boundary of biological tissue and the distribution of light in tissue.     

在几何和参数上表示同一条曲线的两条有理NURBS曲线的权与控制顶点之间的关系

The paper discusses the relationship between weights and control vertices of two rational NURBS curves of degree two or three with all weights larger than zero when they represent the same curve parametrically and geometrically, and gives sufficient and necessary conditions for coincidence of two rational NURBS curves in non-degeneracy case.     

李群,拓扑与微分几何

该文介绍严志达院士的若干工作，以庆贺他的八十寿辰．     

横向放大率法确定复合光学系统的基点

介绍了应用测量横向放大率确定两薄透镜组成的复合光学系统基点的方法。由于采用线阵光电耦合器件（CCD）测量物经光学系统成像的横向放大率，提高了测量精度。