NUMERICAL LOCALIZATION OF ELECTROMAGNETIC IMPERFECTIONS FROM A PERTURBATION FORMULA IN THREE DIMENSIONS

This work deals with the numerical localization of small electromagnetic inhomogeneities. The underlying inverse problem considers, in a three-dimensional bounded domain, the time-harmonic Maxwell equations formulated in electric field. Typically, the domain contains a finite number of unknown inhomogeneities of small volume and the inverse problem attempts to localize these inhomogeneities from a finite number of boundary measurements. Our localization approach is based on a recent framework that uses an asymptotic expansion for the perturbations in the tangential boundary trace of the curl of the electric field. We present three numerical localization procedures resulting from the combination of this asymptotic expansion with each of the following inversion algorithms： the Current Projection method, the MUltiple Signal Classification （MUSIC） algorithm, and an Inverse Fourier method. We perform a numerical study of the asymptotic expansion and compare the numerical results obtained from the three localization procedures in different settings.     

PKI域间互操作性研究

Internet作为电子商务和数字通信的基础平台面临着很多安全威胁.PKI技术为安全电子交易提供了保障.电子商务中.在不同的PKI域之间需要实现互操作.本文提出了一种不使用交叉证书的情况下连接多个独立的PKI域的新方法.该方法是将多个PKl域整合成一个PKI域来实现PKl域之间的互操作.本文采用形式化的方法来描述合并过程.     

符号和数值混合计算

符号计算和数值计算是两种不同的解决科学和技术发展中问题的计算方法.符号计算可以得到问题精确的完备解,但是计算量大且表达形式往往十分庞大;数值计算可以快速地处理很多实际应用中的问题,但是一般只能得到近似的局部解.特别地,数值计算处理病态问题时,收敛往往较慢且容易出错.着重介绍了符号计算和数值计算之间的密切联系,以及如何运用这两大领域的最新研究成果,探索和开发符号和数值混合计算算法和软件,使之兼备符号计算的完备化和数值计算的高效性.     

基于多维名义模型的加权似然估计方法(英文)

The Monte Carlo study evaluates the relative accuracy of Warm's (1989) weighted likelihood estimate (WLE) compared to the maximum likelihood estimate (MLE) using the nominal response model. And the results indicate that WLE was more accurate than MLE.     

检验两个部分线性模型中非参函数相等

We propose the test statistic to check whether the nonparametric func-tions in two partially linear models are equality or not in this paper. We estimate the nonparametric function both in null hypothesis and the alternative by the local linear method, where we ignore the parametric components, and then estimate the parameters by the two stage method. The test statistic is derived, and it is shown to be asymptotically normal under the null hypothesis.     

类比法求解抽象函数问题

类比是根据两类不同事物之间具有某些类似性，推测其中一类事物具有与另一类事物类似（或相同）的性质的思维方法．类比思想是中学数学学习的逻辑思维方式。它既是一种推理方法，同时也是一种学习方法．抽象函数是一类没有给出具体解析式的函数。在探讨抽象函数的有关性质时。由于函数的不具体性。往往显得很盲目，无从下手。因而思维受阻，经常会出现盲点，     

求解随机微分方程的二级Milstein方法(英文)

In this paper we discuss two-stage Miistein methods for solving Ito stochastic differential equations （SDEs）. Six fully explicit methods （TSM 1 -- TSM 6） are given in this paper. Their order of strong convergence is proved. The stability properties and numerical results show the effectiveness of these methods in the pathwise approximation of Ito SDEs.     

Fuzzy格的同余中理想及其W-中理想

本文研究了Fuzzy格的中理想所对应的同余关系问题.利用同余类的方法,得到了中理想与其同态像所对应的同余关系的联系,两个中理想的交与其对应的同余关系交的联系,并证明了Fuzzy格的中理想为W-中理想的一个充分必要条件.     

基于RM型通用门ULM3的对称函数综合

阐述了基本RM型对称函数的定义和性质，给出了任意”变量对称函数在n-1变量基本RM型对称函数完备集中展开系数的计算公式，在此基础上，提出了基于RM型三变量通用逻辑门ULM3的变量数为奇数或偶数的对称函数综合方法，实例验证了上述方法的有效性．