一类非奇异线性方程组的快速解法

通过对非奇异系数矩阵A的Jacobi分裂,利用Jacobi收敛的条件,把系数矩阵的逆通过级数的形式表示,从而找到了一条快速解决一类非奇异线性方程组的方法,即当系数矩阵A的Jacobi收敛时,使得线性方程组的解x=A-1b=D-1b,或者x=A-1b=1s b。最后给出三个例子,以说明这种方法的快速有效性。     

A Critical Look into the Beuk Standard-Setting Method

One commonly used compromise standard-setting method is the Beuk (1984) method. A key assumption of the Beuk method is that the emphasis given to the pass rate and the percent correct ratings should be proportional to the extent that the panelists agree on their ratings. However, whether the slope of Beuk line reflects the emphasis that panelists believe should be assigned to the pass rate and the percentage correct ratings has not be fully tested. In this article, I evaluate this critical assumption of the Beuk method by asking panelists to assign importance weights to their percentage correct and pass rate judgments. I show that in several cases that the emphasis suggested by the Beuk slope is noticeably different from what one would expect and is inconsistent with importance weight ratings. I also suggest two ways that the importance weights can be used to calculate alternate cut scores, and I show that one of the ways of calculating cut scores using the importance weights leads to larger potential differences in cut score estimates. I suggest that practitioners should consider collecting importance weights when the Beuk method is used for determining cut scores.     

定向图的谱半径的一个上界

利用定向图的邻接矩阵的特性,得到了定向图的邻接谱的谱半径的一个可达上界.设D为n阶的定向图,则其邻接谱的谱半径ρ(D)≤n2-1.当n为奇数时,上式取得等号当且仅当D为n2-1出度正则(入度正则);当n为偶数时,不等式严格成立.     

分子结构光谱分析与波谱解析课程的教改及实践

叙述了我校分子结构解析课程教改及实践体会 ,取得了初步成效 .     

草莓果与叶中色素的提取方法和性质研究

以草莓果与叶为原料 ,提取红色素与绿色素 ,并对色素理化性质进行了研究 .结果表明 :酸性乙醇溶液提取红色素效果最佳 ;加入Zn2 +或Cu2 +的 75 %乙醇溶液提取绿色素效果最佳 ;红色素水溶性好、绿色素酯溶性好 ;两色素耐光性、耐热性均好 ;柠檬酸、维生素C、蔗糖、碳酸氢钠等食品添加剂对两色素无不良影响     

土钉墙技术在坡、残积土边坡支护中的应用

结合工程实例，阐述了坡、残积土层中边坡土钉墙支护的设计与施工要点，并针对施工过程中出现的特殊情况，提出相应的解决方案与处理措施。     

Spectral Characterizations of Veronese Surface in S^4

In this paper,we prove that the Veronese surface can be determined by the 1-spectrum of the Laplace operator.     

2-氯甲基-5-芳基-1，3，4-噁二唑的合成及光谱分析

合成6个2一氯甲基-5-芳基-1,3,4-噁二唑,化合物的结构经。HNMR、FT—IR、MS表征．光谱分析表明：在260—279nm出现最大紫外一可见吸收峰;在DMF溶液中,334—362nm出现最大荧光发射峰,是一类紫色发光材料．     

浅谈分光光度法标准曲线斜率的控制

应用尤登双样图对分光光度法进行标准曲线斜率的控制，能简单直观地了解数据质量，看出测点的准确度和精密度，可用同心圆确定测点所代表的标准曲线的斜率是否可接受．     

喷锚支护在高层建筑深基坑支护中的应用

高层建筑深基坑开挖过程中边坡稳定不容易保证,喷锚支护体系是将锚杆与滑裂面以外土体连成一个整体,再通过外拉系统与深基坑边坡组成一个整体受力体,承受主动土压力,利用土层的锚固力,维持被锚固体(边坡)的稳定,从而使得开挖的基坑获得广阔的空间。