奇异Hamilton系统矩阵的精细积分法

常规位移有限元的结构振动方程是n个二阶常微分方程组.采用一般交分原理推导,将结构振动问题引入Hamiltoil体系,将得到2n个一阶常微分方程组.精细积分法宜于处理一阶方程,应用于线性定常结构动力问题求解,可以得到在数值上逼近精确解的结果.对于非齐次动力方程,当结构具有刚体位移时,系统矩阵将出现奇异.本文借鉴全元选大元高斯-约当法求解线性方程组的经验,提出全元选大元法求奇异矩阵零本征解的方法,该方法可以简便快速地寻求奇异矩阵零本征值对应的子空间.利用Hamiltoil体系已有研究成果及Hamilton系统的共轭辛正交归一关系,迅速将零本征值对应的子空间分离出来,通过投影排除奇异部分,然后用精细积分法求得问题的解.数值算例表明,该方法对Hamilton系统奇异问题,处理方便,计算量小,易于实现,同时保持了精细算法的优点.     

毛细管区带电泳法分析头孢菌素类药物的纯度

摘要：提出了以pH9.20的20mmol/L硼酸缓冲溶液、pH6.86的20mmol/L磷酸缓冲溶液和pH2.05的50mmol/L磷酸缓冲溶液作为背景电解质分析9种头孢菌素类抗生素药物纯度的毛细管区带电泳方法。用内部归一化法定量,方法简单快速。讨论了方法的优点和局限性。     

Radii of the bound states in 16N from the asymptotic normalization coefficients

The asymptotic normalization coefficients (ANCs) of the virtual decay ¹⁶N→¹⁵N+n are extracted from the ¹⁵N(⁷Li, ⁶Li)¹⁶N reaction populating the ground and first three excited states in ¹⁶N. The root-mean-square (rms) radii of the valence neutron in these four low-lying ¹⁶N states are then derived by using the ANCs. The probabilities of the valence neutron staying out of the core potentials are found to be 31%±8%, 58%±12%, 32%±8%, and 60%±12%. The present results support the conclusion that a one-neutron halo may be formed in the ¹⁶N first and third excited states, while the ground and second excited states do not have a one-neutron halo structure. However, the core excitation effect has a strong influence on the one-neutron halo structure of the ground and first excited states in ¹⁶N.     

测绘模拟静电场的等K0面分布及多用途T型数字电桥仪

介绍了用测量归一化等电势面来测绘模拟静电场的方法以及相应的测量仪器——多用途T型数字电桥仪。     

关系模式规范化的几个问题

本文讨论了关系数据库中实际数据依赖和用于规范化的函数依赖集之间的差异及过度规范化问题。研究了函数依赖集的闭包及Boyce-Codd范式的判定问题。提出了原子函数依赖集的概念,以此取代函数依赖集的闭包进行关系模式的规范化。并定义了一类对某NP-完全问题可解的实际问题。     

规格化对高斯消元法计算速度的影响

从计算原理和计算速度两个方面详细地分析比较规格化对求解线性方程组的高斯消元法在消元和回代过程中的影响,其中包括计算公式的变化、计算元素的计算次数、规格化元素的计算次数、计算所有元素所需的元素总数、对复数矩阵和实数矩阵的计算速度的影响等内容的比较,并对IEEE-57、-118、-300节点系统进行编程比较计算。计算结果表明,高斯消元法中规格化的计算虽极为简单,且对回代环节的影响不大,但可以大大提高前代环节的计算速度,从而大大提高求解线性方程组的计算速度,尤其是对复数矩阵。该结论同样适用于电力系统等各个工程领域用高斯消元方法求解线性方程组。更多还原     

Normalized Dynamic Characterization and Application of Multiple Heat Storage Materials Based on Standard Thermal Resistance北大核心CSCD

基于标准热阻和能量流法,推导出储热材料与换热流体的瞬态换热热阻,通过类比电路分析法,获得了储热-换热过程的瞬态热量流模型及动态响应时间常数。进一步引入节点温度,重新定义换热热阻,获得了储热与换热过程耦合的三阶电路瞬态热量流模型,求解得到了加热、储热和释热三类时间常数,可用于协同表征储热材料中储热与释热的快慢程度,从而实现了多类储热材料的归一化动态表征。通过数值模拟验证与应用对比分析,发现基于多时间常数的归一化动态模型用于表征储热材料的动态特性是可行的,可直接对不同换热、储热材料进行对比分析。案例分析发现与固体储热材料换热时,液态金属的动态换热能力优于熔融盐,而相比于水蒸气和CO₂,空气与陶瓷材料换热能更快达到稳态。     

特殊函数模积分的一个统一公式

以各类特殊函数与S turm-L iouv ille本征方程之间关系为基础,导出了一个计算各类特殊函数模积分的一个统一公式,这样不仅避免了过去要对不同的特殊函数分别用不同方法计算模的积分,而且使模的计算本身得到较大简化.     

Variable Resolution Bivariate Plots

Abstract

Scatterplots are the method of choice for displaying the distribution of points in two dimensions. They are used to discover patterns such as holes, outliers, modes, and association between the two variables. A common problem is overstriking—the overlap on the plotting surface of glyphs representing individual observations. Overstriking can create a misleading impression of the data distribution. The variable resolution bivariate plots (Varebi plots) proposed in this article deal with the problem of overstriking by mixing display of a density estimate and display of individual observations. The idea is to determine the display format by analyzing the actual amount of overstriking on the screen. Thus, the display format will depend on the sample size, the distribution of the observations, the size and shape of individual icons, and the size of the window. It may change automatically when the window is resized. Varebi plots reveal detail wherever possible, and show the overall trend when displaying detail is not feasible.     

On the intrinsic normalizations of the seminonholonomic complexesSN Gr(m, n, (m+1)(n−m)−ϱ). I

Some intrinsic normalizations of seminonholonomic complexes of then-dimensional projective space are considered. Vilnius University, Naugarduko 24, 2006 Vilnius, Lithuania. Translated from Lietuvos Matematikos Rinkinys, Vol. 39, No. 4, pp. 517–538, October–December, 1999. Translated by R. Lapinskas