Stochastic fracture mechanics using polynomial chaos

Crack propagation in metals has long been recognized as a stochastic process. As a consequence, crack propagation rates have been modeled as random variables or as random processes of the continuous. On the other hand, polynomial chaos is a known powerful tool to represent general second order random variables or processes. Hence, it is natural to use polynomial chaos to represent random crack propagation data: nevertheless, no such application has been found in the published literature. In the present article, the large replicate experimental results of Virkler et al. and Ghonem and Dore are used to illustrate how polynomial chaos can be used to obtain accurate representations of random crack propagation data. Hermite polynomials indexed in stationary Gaussian stochastic processes are used to represent the logarithm of crack propagation rates as a function of the logarithm of stress intensity factor ranges. As a result, crack propagation rates become log-normally distributed, as observed from experimental data. The Karhunen–Loève expansion is used to represent the Gaussian process in the polynomial chaos basis. The analytical polynomial chaos representations derived herein are shown to be very accurate, and can be employed in predicting the reliability of structural components subject to fatigue.     

小波分析中一类滤波器的构造

通过对多分辨分析性质的讨论,提出了使用数值方法修正初始滤波器得到紧支集正交滤波器的方法。可以针对任何紧支集滤波器进行迭代,自动得到消失矩更高、质量更优的滤波器。基于Legendre多项式,构造一组平移正交系,在得到初始滤波器后进行修正,获得消失矩为2的滤波器。与db3小波进行处理一维信号和二维信号的对比检测,实验证明该滤波器在图像边缘处理中有效。     

基于Laguerre多项式的电力机车谐波电流估计

提出利用Laguerre多项式的逼近函数进行电力机车谐波电流估计。根据机车不同的运行方式建立机车模型,通过随机变量矩的合成求出机车电流的k阶原点矩,利用Laguerre多项式展开拟合其概率密度函数PDF(ProbabilityDensityFunction)。根据机车谐波电流与负荷电流的比例关系,求得谐波电流的95%概率估计值。最后,对SS1型机车产生的谐波电流进行估计,证明了该方法的有效性。     

南北朝至隋唐时期佛教寺院经楼、钟楼布局变化初探

在佛教寺院中的经楼与钟楼是早期佛寺的重要布局要素之一.但是,由于中国早期佛教考古发掘资料的缺乏,我们尚不知道其具体布局情况如何.因此,该文基于南北朝至隋唐时期的有关佛教文献记载,以及敦煌莫高窟佛寺壁画和韩日早期佛寺遗址资料,南北朝至隋唐时期佛寺中的经楼与钟楼布局变化进行整理分析,得到如下结论：由南北朝至隋唐时期,在佛寺布局中的经楼与钟楼,由佛殿后边至佛殿前边、由中心院落以外至中心院落以内迁移,但其左右位置却无定制.     

消失模工艺在艺术品铸造中的应用

阐述了消失模铸造艺术品工艺特点，并详细描述消失模铸造工艺品实例——铜钟整个消失模铸造工艺过程。展示了中大型工艺品采用消失模铸造的优越性。     

Zernike多项式拟合方法及应用

由于Zernike多项式的各项与光学像差有相应的对应关系,用Zernike多项式对镜面面形数据进行处理的方法已经广泛应用于工程项目、光学系统设计软件和干涉检查等.用Zernike多项式作为光学和结构分析程序间的接口工具是非常方便和成熟的.本文阐述了Zernike多项式及其拟合方法和应用流程,并应用它作为数据接口工具实现了光机热各分析模块间的数据转换,并在某空间相机系统集成分析中得到应用.     

State controllability computation technique for linear time‐varying systems by using Taylor series approximation

This article presents a technique to determine the controllability Grammian matrix (CGM) for linear time‐varying systems by using truncated Taylor polynomial vector and the operational matrix of integration. An important property of this algorithm is that it starts by integrating the Lyapunov differential matrix equation in terms of the CGM. However, the algorithm does not use the mathematical integration processes actually, but uses the truncated Taylor polynomial vector and the operational matrix of integration. Thus, the problem is reduced to solving a linear set of algebraic equations with constant coefficients consisting of the Taylor polynomial constant coefficients of each of the CGM elements. Numerical results and error curves are given to illustrate the improvements achieved by the proposed algorithm. Copyright © 2008 John Wiley & Sons, Ltd.     

Fast blind estimation algorithm for Hamming codes parameters

An algorithm is proposed for fast blindly estimating the length, the starting point and the parity-check matrix of the hamming code. First, an intercepted matrix is built by the data received, and by exploiting an assumed number of parity-check digits and the assumed starting point of the hamming code. Then, a parity-check matrix is obtained by the assumed primitive polynomial, and when all its row-vectors are dual codes of the intercepted matrix, the hamming code parameters could be estimated. Moreover, a theoretical analysis of the proposed algorithm is made. Simulation results verify the good performance of the proposed method.     

无线电铃控制系统的设计与实现

给出了一套无线电铃控制系统的方案，该方案实现了对传统打铃系统的改进，解决了传统的自动打铃设备无法实现打铃时间的完全统一的缺点。     

非线性判别函数的基于MDL标准的勒让德多项式构造法

1.引言在模式识别中,分类决策问题是最基础也是最重要的内容,所谓分类决策就是根据被识别对象特征的观察值将其分到某个类别中去,其基本作法是在样本训练集基础上确定某个判决规则(即样本特征空间的一个函数,也称为判别函数或分类器),使按这种判决规则对被识别对象进行分类所造成的错误率最小或引起的损失最小。当样本分布是正态分布时,从最小错误率来说二次分类器是最优分类器。此外,作为一种特殊情况,如果这些分布有相同的协方差矩阵,那么线性分类器就是最优的。然而这些假定在很多实际问题中并不成立,因此线性或二次分类器对