Temperature dependent energy-dispersive X-ray diffraction and magnetic study of Fe/Al interface

In situ temperature dependent energy-dispersive structural and magnetic study of electron beam evaporated Fe/Al multilayer sample (MLS) has been investigated. The structural studies show the formation of an intermixed FeAl transition layer of a few nanometers thick at the interface during deposition, which on annealing at 300 °C transforms to B2FeAl intermetallic phase. Magnetization decreases with increase in temperature and drops to minimum above 300 °C due to increase in anti-ferromagnetic interlayer coupling and formation of nonmagnetic FeAl phase at the interface. The Curie temperature (T_c) is found to be 288 °C and is much less than that of bulk bcc Fe.     

时间序列散斑干涉技术研究及应用

当用相干激光照射在一个连续位移或变形的漫射物体表面时,在与参考光形成干涉的接收面上即产生一随时间变化的散斑干涉场通过对这一干涉场的时间域进行分析,可实现时变位移场的定量检测本文介绍了基本时间序列散斑干涉场的扫描相位方法和时间序列相位法的相位函数解调原理,探讨了它们的计量特性,并将其用于火箭固体燃料性能的检测.     

Exact Misclassification Probabilities for Plug-In Normal Quadratic Discriminant Functions: II. The Heterogeneous Case

We consider the problem of discriminating between two independent multivariate normal populations, N_p(μ₁, Σ₁) and N_p(μ₂, Σ₂), having distinct mean vectors μ₁ and μ₂ and distinct covariance matrices Σ₁ and Σ₂. The parameters μ₁, μ₂, Σ₁, and Σ₂ are unknown and are estimated by means of independent random training samples from each population. We derive a stochastic representation for the exact distribution of the “plug-in” quadratic discriminant function for classifying a new observation between the two populations. The stochastic representation involves only the classical standard normal, chi-square, and F distributions and is easily implemented for simulation purposes. Using Monte Carlo simulation of the stochastic representation we provide applications to the estimation of misclassification probabilities for the well-known iris data studied by Fisher (Ann. Eugen.7 (1936), 179–188); a data set on corporate financial ratios provided by Johnson and Wichern (Applied Multivariate Statistical Analysis, 4th ed., Prentice–Hall, Englewood Cliffs, NJ, 1998); and a data set analyzed by Reaven and Miller (Diabetologia16 (1979), 17–24) in a classification of diabetic status.     

ZYA系统的拉曼光谱研究

测试了６０ｗｔ％ＺｒＯ２（２．２５ｍｏｌ％Ｙ２Ｏ３）－４０ｗｔ％αＡｌ２Ｏ３（ＺＹＡ）粉末样品受高压前后的拉曼光谱，并由此证明了四方相ＺｒＯ２陶瓷基质的相变增韧机制。     

SBN:Cr晶体的光折变四波混频相位共轭特性实验研究

从实验上研究了同成分SBN:Cr晶体在He-Ne激光照射下的四波混频相位共轭特性.首先测量了在不同泵浦光与信号光光强比m及不同光束夹角2θ的情况下,晶体的四波混频相位共轭反射率R随泵浦光强比p的变化关系.其次测量了泵浦光束与信号光束耦合方向对SBN:Cr晶体的四波混频相位共轭特性的影响,并就两种不同掺杂浓度的晶体样品进行了对比,所得实验结果与理论分析基本一致.最后,利用SBN:Cr晶体四波混频相位共轭特性进行了图象畸变消除实验.     

三维热传导型半导体器件瞬态模拟问题的Crank-Nicolson差分-流线扩散有限元法及其数值分析

本文研究三维热传导型半导体器件瞬态模拟问题的数值方法.针对数学模型中各方程不同的特点,分别提出不同的有限元格式.特别针对浓度方程组是对流为主扩散问题的特点,使用Crank-Nicolson差分-流线扩散计算格式,提高了数值解的稳定性.得到的L2误差估计关于空间剖分步长是拟最优的,关于时间步长具有二阶精度.     

Abstract estimates of the rate of convergence for optimal control problems

A method for solving optimal control problems with general elliptic operators is presented and analyzed. Especially, estimates of the rate of convergence for the control problems with the proposed approach are derived independently of the underlying approximation method. Some numerical experiments with the proposed method are included.     

关于刚体转动惯量测定的计时方法研究

本文给出了在刚体转动惯量的测定中测定时间的计时装置，减小了计量时间所带来的误差。     

非线性对流扩散方程沿特征线的多步有限体积元格式

对于二维非线性对流扩散方程构造了沿特征线方向的多步有限体积元格式．关于空间采用二次有限体积元方法离散，关于时间采用多步法进行离散，获得了O(Δt^2 h^2)形式的误差估计．本文最后给出的数值算例表明了方法的有效性．     

An immersed finite element space and its approximation capability

This article discusses an immersed finite element (IFE) space introduced for solving a second‐order elliptic boundary value problem with discontinuous coefficients (interface problem). The IFE space is nonconforming and its partition can be independent of the interface. The error estimates for the interpolation of a function in the usual Sobolev space indicate that this IFE space has an approximation capability similar to that of the standard conforming linear finite element space based on body‐fit partitions. Numerical examples of the related finite element method based on this IFE space are provided. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 338–367, 2004