选择逻辑函数的密码学性质

通过计算选择逻辑函数的Walsh循环谱和自相关函数，系统分析了选择逻辑函数的密码学性质。所得结论表明选择逻辑函数在变元个数较大的情况下具有理想的稳定性，能够抵抗最佳仿射（BAA）攻击，但是其“扩散”特性不够理想，在一定意义下不能有效地抗击差分攻击。讨论了与选择逻辑函数线性等价意义下满足严格雪崩准则或具有相关免疫性的逻辑函数构造问题。     

广Bent函数

利用了Bent函数构造了一类新的布尔函数——“广Bent函数”，并分析了广Bent函数的密码学性质，如平衡性、高的非线性度、稳定性等。还给出了广Bent函数仅在一个非零点不满足扩散准则的充要条件，并指出广Bent函数平衡且满足2n次扩散准则的充要条件，最后揭示了平衡且满足k次扩散准则的k 1元布尔函数的结构特征。     

满足k阶严格雪崩准则的多值逻辑函数的谱特征

给出了剩余类环Zm上逻辑函数的k阶严格雪崩准则(SAC)的概念, 用概率方法证明了m值逻辑函数满足高阶严格雪崩准则时一定满足低阶严格雪崩准则, 并借助Chrestenson谱给出了m值逻辑函数满足k阶严格雪崩准则的一个充分必要条件。     

密码函数的一类递归构造方法

首先利用递归的方法证明了结构形式更为一般的布尔函数的 Walsh谱分解式，然后利用这类布尔函数Walsh谱分解式，给出了密码学和编码学中具有重要应用价值的一些布尔函数，如弹性函数、Bent函数以及满足严格雪崩准则的布尔函数的构造方法。     

p值随机变量联合分布的分解式及其应用

给出了一般概率空间上n维p值(户为素数)随机变量的联合分布与其分量的任意非零线性和的分布之间的等量关系，并将之应用于与户值逻辑函数相应的p值随机变量的有关联合分布的分解,得到了p值逻辑函数和户值逻辑向量函数相关免疫性的等价条件及谱判别条件，揭示出p值逻辑函数、p值逻辑向量函数相关免疫性的若干等价条件的概率内在联系。     

布尔函数的Walsh谱的概率意义及其应用

本文揭示了布尔函数的Ｗａｌｓｈ谱的概率实质，对布尔函数的线性逼近的最佳意义作出了概率解释．并利用Ｗａｌｓｈ谱的概率意义进行了谱分析．考察了谱的运算性质。文中的方法和结论对密码设计和分析都是有用的。     

相关免疫布尔函数的一种构造方法

本文证明了布尔函数的谱分解定理，定义了布尔函数的谱（分解）特征向量，给出相应的充要条件，将全部Ｎ元相关免疫布尔函数的构造问题转化为线性方程组的求解问题，为相关免疫布尔函数的构造提供了新的方法。）满足，可求得符合要求的用上述方法我们通过人工计算确定出８６个符合要求的谱特征向量，注意到向量中各分量地位的对称性，并注意到定理４，我们得知全部４无相关免疫的非平凡布尔函数共２×３２４＝６４８个Ｎ＝４，ｍ＝２时，定理６中条件即从后面１１个方程可求得联系（Ⅱ）中的第５～１４个方和即知在（Ⅲ４）下ｂ１、ｂ２、ｂ３、ｂ４全为１（全为０平凡情况），在（Ⅲ４）下ｂ１、ｂ２、ｂ３、ｂ４中有３个取１、１个取０，由此可得全部４元至少２阶相关免疫的非平凡布尔函数所对应的谱特征向量如下：它们所对应的的布尔函数依次是（此结论与［１］ｐ１５５上结论相符），因而４元１阶相关免疫的布尔函数共有６４８－１０＝６３８个。一般情况下，在我们的方法里构造全部Ｎ元相关免疫布尔函数实质上是在定理６中“约束条件”（１）下去求２Ｎ－１个变元、Ｎ个方程的方程组（Ⅱ）所有解，构造全部Ｎ元至少ｍ（≥２）附相关免疫布尔函数实质上是在定理６中“约束条件，（１）下去解２Ｎ－     

对称布尔函数的代数免疫性

在流密码和分组密码的加密体制中,需要构作具有各种密码学性质的布尔函数,用来作为密钥,以抵抗已有的各种有效攻击方法。近年来,人们提出了代数攻击方法,为了抵抗这种攻击方式,构作代数免疫度很大的布尔函数,成为近五年来信息安全领域一个研究热点。本文综述布尔函数代数免疫性方面的重要问题和主要进展,其中包括中国学者在对称布尔函数代数免疫性的研究成果。     

密码学中的布尔函数研究综述

概述了目前密码学中布尔函数的研究现状和重要研究方向上的新成果，并对布尔函数的研究进行了展望，指出了一些重要的研究热点问题．     

环境激励下基于相关函数的脉冲响应函数重构

在白噪声激励下,结构响应的相关函数作为脉冲响应函数的近似可以进行模态参数辨识,但其物理意义始终缺乏明确解释;相比于脉冲响应函数,基于相关函数的辨识缺少了模态参与因子或者说质量信息,这也是工况模态分析(OMA)方法的主要缺陷。简要回顾了复模态下的自然激励技术原理,证明了白噪声激励下位移响应的相关函数等价于系统在特定初始条件下的自由响应,给出相应初始条件的计算方法;进一步提出了一种系统质量分布的辨识方法,并藉此重构得到系统脉冲响应函数。讨论了相关函数误差与信号时长及激励带宽之间的关系。通过仿真和试验验证了所得结论。     

R0-代数(NM-代数)的布尔MP滤子与布尔MP理想

在R0-代数中引入布尔MP滤子与布尔MP理想的概念,给出其若干充要条件,研究了它们与素滤子、极大MP滤子的关系。通过反例指出了关于超MP滤了的一个错误结论,给出超MP滤子的一个充分必要条件。在此基础上研究了R0-代数的结构,用布尔MP滤子与布尔MP理想刻画了二部R0-代数、强二部R0-代数的特征。     

Z_4~n上完全非线性函数的存在性和构造

给出了剩余类环Z4上的逻辑函数-4值逻辑函数是完全非线性函数的两个条件,引入了布尔函数中"类Bent函数"的概念,并用其构造了自变量个数是偶数的一类4值完全非线性函数,给出了1元4值完全非线性函数不存在性的一个简单证明。     

基于滞后型系统理论的半主动悬架控制系统稳定性分析

为了研究时滞对于半主动悬架系统稳定性的影响,建立含时滞的二自由度半主动悬架模型,依据滞后型系统稳定性理论运用改进的全时滞稳定代数判据推导出满足系统全时滞稳定的充要条件,得到可控阻尼的取值范围。针对不符合全时滞稳定条件的半主动悬架参数,提出运用稳定性切换点分析法求取实际所需的稳定性切换点及其稳定性区间。通过时域仿真发现在全时滞稳定情况下时滞的产生并非会导致悬架性能的恶化。在非全时滞稳定的情况下,随着时滞的增加悬架性能不断下降并在超过稳定性切换点时发生剧烈恶化。     

Some comments on the dynamic properties of anisotropic and strongly anisotropic pre-stressed elastic solids

The effect of pre-stress on the propagation of small amplitude waves in an incompressible, transversely isotropic elastic solid is discussed in respect of the most general appropriate strain energy function. A simple set of sufficient conditions is noted which ensures that two real wave speeds exist for all directions of propagation. In the case of bi-axial primary deformations, and for propagation within each principal plane of the homogeneous primary deformation, the propagation condition is factorised and conditions which are both necessary and sufficient to ensure the existence of two real wave speeds are established. The paper also includes some graphical illustrations of the associated slowness and wave surfaces and discussion of the strongly anisotropic case, for which the extensional modulus along the preferred fibre direction is much larger than other material parameters.     

Crack onset and propagation at fibre–matrix elastic interfaces under biaxial loading using finite fracture mechanics

A new fracture criterion able to predict crack onset and propagation at interfaces between solids is formulated, implemented in a computational code and applied to a particular problem in composites on a microscale. More specifically, this criterion is used to study the debond onset and propagation in mixed mode in the case of a single fibre subjected to a biaxial remote loading. The fracture criterion formulation is based on the Linear Elastic-(Perfectly) Brittle Interface Model (LEBIM) combined with a Finite Fracture Mechanics (FFM) approach, where the stress and energy criteria are suitably coupled. Each of these criteria is a necessary but not sufficient condition for crack onset and propagation. Two empirical mixed-mode fracture criteria are considered and tested: the interface fracture toughness law by Hutchinson and Suo and the quadratic stress criterion. The FFM + LEBIM approach developed offers an adequate characterization of the interface stiffness in contrast to the too restrictive, original LEBIM formulation.     

类差分平衡函数的性质及其应用

定义了布尔函数的类差分和类差分平衡函数，研究了类差分平衡函数的密码学性质以及构造方法。作为类差分平衡函数的应用， 给出了Z24上逻辑函数是完全非线性函数的充要条件，并在首先分析得到所有四元类差分平衡函数的基础上，编程搜索出Z24上所有的完全非线性函数。     

Effect of yield surface vertex on failure of ductile materials

This paper is concerned with the lengthening of a solid rod or tubular specimen along the principal axis about which it is being twisted, this aspect of the elastic-plastic deformation of a material being referred to as the Poynting-Swift effect. The Swift effect is the counterpart in the plastic range of deformation to the Poynting effect in the elastic range of deformation. Central to any study of the Swift effect is the problem of identifying an appropriate yield criterion. A generalised isotropic yield criterion is formulated in such a way that it can be applied to materials which satisfy the von Mises yield criterion, or some modified, but continuously difierentiable form of it, and to materials which satisfy a piece-wise continuous yield condition such as the Tresca yield criterion. The choice of the constitutive equation describing the purely elastic deformation behaviour determines the initial yield function. In this context, the constitutive equation of a simple elastic material is only compatible with von Mises yield criterion, a conclusion which applies also to classical infinitesimal theory. An attempt is made to generalise the constitutive equation of a simple elastic material to give a constitutive equation which is compatible with the proposed generalised isotropic yield criterion. This approach introduces an additional term into the constitutive equation which is quadratic in the stress. The two loading coefficients associated with the stress loading function are assumed to be deriveable from the generalised isotropic yield criterion which is now assumed to hold over the entire range of deformation, and in this context is referred to as the stress intensity function. It is a matter of observation that the proposed constitutive equation describes the total, post-yield, elastic-plastic response to simple loading. Consideration is given to the application of the Poynting-Swift effect to the failure of ductile materials using the proposed constitutive equation.     

Some results on permutation polynomials over finite fields

This paper deals with two questions concerning permutation polynomials in several variables. Lidl and Niederreiter have considered the problem of when a sum of permutation polynomials in disjoint sets of variables is itself a permutation polynomial, and in the case of prime fields have shown that it is necessary and sufficient that at least one summand be a permutation polynomial. They also showed that in the case of non-prime fields this condition is not necessary. In this paper, a necessary and sufficient condition is obtained for the general case which specialises to the previous result for prime fields. The second part extends a criterion of Niederreiter for permutation polynomials over prime fields to any finite field.