满足k阶PC(l)的密码函数的新构造

该文基于线性分组码和双射函数,给出了满足七阶PC(l)的均衡相关免疫布尔函数新的构造方法。并据此进一步给出满足七阶PC(l)的(n,m,t)弹性函数的一般构造方法。此外,该文还揭示了这些函数的其它良好的密码学性质,如较高的非线性度、良好的代数次数、良好的构造计数等。     

均衡弹性函数的结构与弹性阶

弹性函数是相关免疫布尔函数的自然推广。本文讨论均衡弹性函数,得到以下结果:给出了均衡弹性函数的一种结构,并因此得到了由均衡(n,m,2t)弹性函数构造均衡(n+1,m,2t+1)弹性函数的非线性方法;证明了均衡线性函数的弹性阶等于对应线性分组码的码字最小重最减1,且弹性阶上确界常常能由非线性函数所达到。     

具有最大代数免疫度函数的研究

代数免疫度是私钥密码学中的重要概念。具有高代数免疫度的函数能抵抗新型攻击——代数攻击。CARLET Claude和FENG Keqin构造了具有最大代数免疫度的平衡函数及其线性等价函数,根据CARLET和FENG的构造,首先证明这类最大代数免疫度函数的数目,然后给出曹浩等人给出的定理6的简化证明,最后说明没有矩阵满足曹浩等人给出的定理7的条件（即不能用曹浩等人的方法构造具有最大代数免疫度的1阶弹性函数）．     

具有最优代数免疫阶的1阶弹性函数的构造

这里研究了两种二阶级联构造的密码学性质,发现对初始函数增加2个变元,构造方法I和Ⅱ都能使代数免疫阶增加1阶,同时分别获得高的非线性度和1阶弹性。通过选择置换s,构造I能迭代产生非线性度高的代数免疫最优的布尔函数。最后利用级联构造I和II给出了一种具有1阶弹性的代数免疫最优布尔函数的构造方法.     

次数最大的平衡相关免疫函数的构造

Maitre和Sarkar于1999年提出了一种递归构造n元平衡相关免疫布尔函数的方法。该文给出了一种新的递归构造方法，构造出非线性度很高的n元m阶n-m-1次的平衡相关免疫函数。与原构造方法相比，该文构造方法得到的函数性质相同，数量更大。     

(n+1,m,2t)均衡弹性函数的非线性构造方法

基于GF(2)n上(n,m,2t-1)均衡弹性函数,运用其对偶分布性质和各分量函数弹性阶的相关特性,得到了(n 1,m,2t)均衡弹性函数的非线性构造方法。这些方法使得自变量的维数与弹性阶同步增长,且函数的代数次数也相应增加,从而避免了线性构造的缺陷。     

素数元旋转对称弹性布尔函数的构造与计数

通过对素数元旋转对称弹性布尔函数特征矩阵的研究,给出了其特征矩阵的若干性质,得到了素数元旋转对称布尔函数为弹性函数的一个充要条件,由此完全决定了旋转对称弹性函数的构造以及这类函数的精确计数公式,最后还给出了所有的三元、五元、七元旋转对称弹性布尔函数的构造方案与精确计数。     

弹性函数的构造

本文讨论了弹性函数，研究了综在序列密码中的应用，给出了若干从已知弹性函数构造新的弹性函数的方法。     

优良布尔函数的混合禁忌搜索算法

为保障对称密码算法的安全性,其构成算法中所使用的布尔函数必须具有优良的密码学性质。结合禁忌搜索算法和爬山算法的优点,提出了一种新的优良布尔函数启发式生成算法——混合禁忌搜索算法。应用该算法,可以快速得到大量具有高非线性度、低自相关性、一阶弹性、最优代数次数、最优代数免疫度、最优（次优）抵抗快速代数攻击能力等的布尔函数。仿真结果表明,所提算法搜索能力强,运行速度快,且搜索出的布尔函数的密码学性质优于已知的优化算法的结果,也弥补了采用构造法构造布尔函数的一些缺陷。     

高非线性度布尔函数的构造

布尔函数的非线性度是衡量及其密码学意义的重要标志,而非线性度和其它密码学强度指标,如代数次数,扩散性,相关免疫性等存在着制约关系,本文研究了高非线性度布尔函数的构造,讨论非线性度和其它密码学准则之间的折关系,给出高非线性度,高代数次数,高非线性平衡相关免疫以及具有较好扩散性的高非线性度布尔函数的几种构造方法。     

The evaluation of “esaki integrals” and an approximate expression for the tunnel-diode characteristic

Fermi-Dirac-type integrals, involving a product of two density-of-states functions in the integrand, have been first considered by Esaki. Two series expressions, suitable for computation, have been derived for such integrals, appropriate for room temperature and low temperatures respectively. A simple analytical current-voltage characteristic for the tunnel diode has been obtained, which has approximately the same degree of validity as Esaki's original theory.     

A simplified approach to the evaluation of EMW propagationcharacteristics in rain and melting snow

Electromagnetic propagation characteristics in rain and melting snow are calculated by treating these media as artificial dielectrics. Computed values of attenuation and phase shift in rain, obtained by this approach, are compared with those derived by using Mie scattering theory over a frequency range of 1-1000 GHz and for rain rates up to 100 mm/h. Very close agreement is generally obtained over these entire ranges. Melting snow is treated in the same manner, where comparison is possible these results tend to agree well with the available, but rather limited, published data. Attenuation and phase shift are calculated as a function of the degree of melting of the snow particles. Subject to assumptions relating the degree of melting to depth in the melting layer, average values of attenuation and phase shift are computed as functions of frequency. The attenuation values compare well with those derived from an empirical formula over the range of its validity     

Bayesian Confidence Limits for the Reliability of Mixed Exponential and Distribution-Free Cascade Subsystems

The problem treated here is the theoretical one of deriving exact Bayesian confidence intervals for the reliability of a system consisting of some independent cascade subsystems with exponential failure probability density functions (pdf) mixed with other independent cascade subsystems whose failure pdf's are unknown. The Mellin integral transform is used to derive the posterior pdf of the system reliability. The posterior cumulative distribution function (cdf) is then obtained in the usual manner by integrating the pdf, which serves the dual purpose of yielding system reliability confidence limits while at the same time providing a check on the derived pdf. A computer program written in Fortran IV is operational. It utilizes multiprecision to obtain the posterior pdf to any desired degree of accuracy in both functional and tabular form. The posterior cdf is tabulated at any desired increments to any required degree of accuracy.     

Wavelet functions to estimate velocity in spatiotemporal signals

This paper establishes a framework to estimate velocity from spatiotemporal signals using the wavelet transform and multiresolution techniques. Initial theory is derived with the assumption that the spatiotemporal signal can be represented by a polynomial of order M. Wavelet functions are derived for polynomials of different degree from which the velocity can be estimated as the ratio of two of the four components of a two dimensional (2-D) wavelet transform of the signal. We have characterized two classes of wavelet and scaling functions: one with nonuniform support and another with symmetry and uniform support. For a wavelet function of order M, the velocity estimates are exact if the signal can be represented by a polynomial of the same order or less. In many cases, the velocity error is very low, even when there is no match. We also present the error estimates for three different signals: a polynomial of degree four, a sinusoid (polynomial of degree infinity), and a function with analytical value for the velocity. The paper also demonstrates how error in the velocity estimates can be reduced by using multiresolution techniques. Even though results are presented using one-dimensional (1-D) signals, the extension to higher dimensions (images) is straightforward and uses the same wavelet functions derived in this paper     

Algebraic immunity for cryptographically significant Boolean functions: analysis and construction

Recently, algebraic attacks have received a lot of attention in the cryptographic literature. It has been observed that a Boolean function f used as a cryptographic primitive, and interpreted as a multivariate polynomial over F/sub 2/, should not have low degree multiples obtained by multiplication with low degree nonzero functions. In this paper, we show that a Boolean function having low nonlinearity is (also) weak against algebraic attacks, and we extend this result to higher order nonlinearities. Next, we present enumeration results on linearly independent annihilators. We also study certain classes of highly nonlinear resilient Boolean functions for their algebraic immunity. We identify that functions having low-degree subfunctions are weak in terms of algebraic immunity, and we analyze some existing constructions from this viewpoint. Further, we present a construction method to generate Boolean functions on n variables with highest possible algebraic immunity /spl lceil/n/2/spl rceil/ (this construction, first presented at the 2005 Workshop on Fast Software Encryption (FSE 2005), has been the first one producing such functions). These functions are obtained through a doubly indexed recursive relation. We calculate their Hamming weights and deduce their nonlinearities; we show that they have very high algebraic degrees. We express them as the sums of two functions which can be obtained from simple symmetric functions by a transformation which can be implemented with an algorithm whose complexity is linear in the number of variables. We deduce a very fast way of computing the output to these functions, given their input.     

Transitional multiple-pole transfer functions for active-filter design

A new class of all-pole transfer functions for the design of RC active filters is described. The transfer functions of these filters, which can be referred to as transitional Mucromaf-Mucroer filters, are of higher degree than the previously described transitional Butterworth-Cheby?shev filters satisfying the same specifications, but provide much lower values of the critical pole Q-factor.     

Approximating Functions From Sampled Fourier Data Using Spline Pseudofilters

Recently, new polynomial approximation formulas were proposed for the reconstruction of compactly supported piecewise smooth functions from Fourier data. Formulas for zero and first degree polynomials were presented. For higher degree approximations, polynomial formulas become extremely complicated to be handled. In this paper we solve this problem by introducing spline approximations. The new approach can be used in the same way as the polynomial one but producing computable formulas for any degree of approximation in Fourier reconstruction. We present general error estimates and numerical experiments.     

Further results on a series representation related to the sampling theorem

During the period 1968–1971 there were several papers dealing with a class of series representations for stochastic processes on an infinite time interval. In a special case, these series reduce to the sampling theorem for bandlimited functions. The present paper continues the study of these series. Series representations of functions are studied, but most of the results should extend to stochastic processes. Sufficient conditions for convergence of the series are given and a bound on the truncation error of the series is obtained. A Kullback-Leibler measure of the interdependence of the coefficients in the series is found. Some partial results are obtained on the degree to which the coefficients depend on measurements which are localized in time. Some additional special properties of the coefficients associated with bandlimited functions are also discussed.     

Motoman机器人的运动学建模及基于BP网络的IKP研究

建立了Motoman六自由度机器人运动学模型，在该模型的基础上提出了两种解决机器人逆解问题的方法。第一种方法是利用机器人自由度分布的特点推导出一种新的解析解，该法推导过程和解的表达式都非常简单．易于遥操作机器人的仿真和控制。第二种方法利用6个相同结构的BP网络和正解模型直接实现从工作空间到关节空间的非线性映射，避免了解析法中的多解问题，计算结果表明，该法计算精度较高且计算速度快。本文方法可以直接运用到具有相同自由度分布的机器人上。