线性同余发生器的分析

文章研究了线性同余序列参数的生成方法，并给出了具体的求乘数算法。     

一种新的谱随机有限元方法

提出了一种新的谱随机有限元分析方法——递推求解方法。讨论了已有的几种随机场的谱展式，提出将随机结构的随机响应表示成非正交多项式混沌展式，并证明了这个展式的收敛性。在此基础上将随机微分方程表示成了和摄动法类似的一系列确定的递推方程，这些递推方程可用确定性有限元方法求解。该方法比在正交多项式混沌基上投影并取期望的方法更简洁实用，更适合大规模有限元的求解。该方法同样能解决有较大随机涨落的力学问题。     

Multi-degree reduction of NURBS curves based on their explicit matrix representation and polynomial approximation theory

NURBS curve is one of the most commonly used tools in CAD systems and geometric modeling for its various specialties, which means that its shape is locally adjustable as well as its continuity order, and it can represent a conic curve precisely. But how to do degree reduction of NURBS curves in a fast and efficient way still remains a puzzling problem. By applying the theory of the best uniform approximation of Chebyshev polynomials and the explicit matrix representation of NURBS curves, this paper gives the necessary and sufficient condition for degree reducible NURBS curves in an explicit form. And a new way of doing degree reduction of NURBS curves is also presented, including the multi-degree reduction of a NURBS curve on each knot span and the multi-degree reduction of a whole NURBS curve. This method is easy to carry out, and only involves simple calculations. It provides a new way of doing degree reduction of NURBS curves, which can be widely used in computer graphics and industrial design.     

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。     

改进的基于义原同现频率的汉语词义排歧方法

针对传统的基于义原同现频率的汉语词义排歧方法存在“盲目性”的不足,本文根据《知网》中对概念定义的描述,分别计算多义词的每个义项与特征词的第一独立义原、其他独立义原、关系义原、符号义原之间的相关系数;最后通过比较多义词的每个义项与特征词之间的相关系数来决定多义词的义项。经过实验验证,该方法进一步提高了词义排歧的效果。     

基于OSPF的ASON路由的一种加密方案

自动交换光网络(ASON)控制协议采用通用多协议标签交换(GMPLS)控制协议族,其路由部分主要为开放式最短路径优先(OSPF)协议.文章分析了OSPF协议加密措施存在的安全隐患,并对现有的加密方案进行了改进.针对OSPF协议的安全模式,提出了一种可以应用于ASON中路由技术的新的安全性方案.基于数论算法,实现S盒动态调整,通过动态产生的子密钥,在迭代过程中对分组进行加密.     

关于模p的原根及逆的差的混合均值

研究模p的原根及其逆的差的渐近性质.利用广义Bernoulli数、Gauss和及Dirichlet L-函数的均值定理,得出Cochrane和与广义的Kloosterman和的一些混合均值公式.     

Reconstructing a Flavodoxin Oxidoreductase with Early Amino Acids

Primitive proteins are proposed to have utilized organic cofactors more frequently than transition metals in redox reactions. Thus, an experimental validation on whether a protein constituted solely by early amino acids and an organic cofactor can perform electron transfer activity is an urgent challenge. In this paper, by substituting “late amino acids (C, F, M, T, W, and Y)” with “early amino acids (A, L, and V)” in a flavodoxin, we constructed a flavodoxin mutant and evaluated its characteristic properties. The major results showed that: (1) The flavodoxin mutant has structural characteristics similar to wild-type protein; (2) Although the semiquinone and hydroquinone flavodoxin mutants possess lower stability than the corresponding form of wild-type flavodoxin, the redox potential of double electron reduction E_m,7 (fld) reached −360 mV, indicating that the flavodoxin mutant constituted solely by early amino acids can exert effective electron transfer activity.