纠错码方法在S-盒设计中的应用

S-盒是许多分组密码算法中唯一的非线性部件,它的密码强度决定了整个密码算法的安全强度。介绍了分组密码中S-盒的设计准则与构造方法,对S-盒设计中纠错码原理与方法进行讨论,最后给出了现代分组密码中广泛应用于S-盒设计的仿射逆函数所具有的密码特性,并证明了仿射逆函数在代数结构上存在分量函数的线性等价性。     

非线性闭环系统的虚拟参考反馈校正控制设计

针对闭环非线性系统中的控制器为一非线性函数的情况,采用虚拟参考反馈校正控制的设计原理,根据控制器的输入—输出观测数据构造一个基于输出数据的线性仿射函数。通过最小化逼近误差,利用系统辨识的参数估计方法求取线性仿射函数中可调参数权值,从而采用一个含可调参数权值的线性仿射形式来逼近原非线性控制器,通过对参数权值的调整使得逼近误差较小,并给出参数权值的凸优化求解过程。最后用仿真算例验证方法的有效性和可行性。     

采用级联仿射不变函数的快速平面形状识别(英文)

现有的基于小波变换的形状识别算法具有很高的计算复杂度,难以满足许多实时应用的要求。文中提出了基于级联仿射不变函数的快速形状识别算法,用于识别仿射变换下的含噪目标。利用目标轮廓的小波变换可以得到一组仿射不变函数,并进一步构造出级联仿射不变函数。为了保证级联仿射不变函数的平移不变性,预先对轮廓的起始点进行了有效配准。从而通过级联仿射不变函数的内积,方便地度量出目标形状的相似度。与现有基于小波的识别算法相比,所提出的算法具有很低的计算复杂度,其所需CPU时间仅为其它算法的1/7。实验结果验证了该算法的有效性和起始点配准的准确性。     

利用薄板样条函数实现非刚性图像匹配算法

提出了一种利用薄板样条函数实现非刚性图像匹配的新方法 .该方法是将图像表示成由特征点构成的特征点集 ,利用薄板样条 (TPS)能够将形变清楚地分解为仿射分量和非仿射分量的独特性质 ,应用TPS函数来表征特征点集之间的非刚性映射 ,并将TPS映射参数的求解嵌入到确定性退火技术的框架中 .首先提出基于TPS弯曲能的非刚性匹配的能量函数 ,然后采用确定性退火技术 ,迭代求解点集之间的匹配矩阵和映射参数 .与其它的非刚性匹配算法相比 ,该算法不仅保证了图像特征点之间的一一对应的双向约束 ,同时避免了陷入局部极小 ,而且具有较强的鲁棒性 .实验结果证实了所提算法的有效性和鲁棒性 .     

基于终点的用户均衡交通分配模型求解算法

用户均衡分配模型是更接近实际交通状态的分配模型,它是建立在出行者总选择起迄点间交通时间最短的路径作为出行路线的行为假设基础上的。分析基于终点的用户均衡交通分配模型,指出该模型与基于路径均衡配流模型是等价的,在选择美国BPR路阻函数后,模型可以转化为带线性约束的非线性规划问题,并给出模型的矩阵表示。对这类问题,采用简便实用的仿射尺度算法求解,给出算法的基本思想及详细的实现过程。仿真结果显示,所得最优解满足Wardrop第一准则,表明该算法是有效的,可用于大型路网的配流计算。     

基于宽线性迭代平均仿射LMS算法的DS-CDMA MAI抵消

基于宽线性处理可以改善线性多用户接收机的性能以及仿射和迭代平均可以加快算法收敛的思想,提出了一种宽线性迭代平均仿射LMS算法,分析了算法在均方意义下的收敛性,给出了算法稳定条件和失调公式,以及算法应用于码分多址系统多址干扰抵消的效果.     

基于多尺度自卷积归一化直方图的仿射不变量模式识别

 仿射不变量特征提取方法已成为计算机视觉研究的重点课题之一.本文提出一种归一化直方图算法,该算法基于多尺度自卷积变换中密度函数的概念,研究归一化密度函数的方法,构建了从目标图像中提取直方图仿射不变量特征提取算法,实现了基于多尺度自卷积归一化直方图的仿射不变量模式识别.仿真实验表明,本算法对一定范围内的噪声,局部遮挡,照度及视角变化具有良好的适应性,特别是在多种环境下,其识别率优于多尺度自卷积和基于多尺度自卷积的其它直方图算法.     

利用薄板样条函数实现非刚图像匹配算法

提出了一种利用薄板样条函数实现非刚性图像匹配的新方法，该方法是将图像表示成由特征点构成的特征点集，利用薄板样条（TPS）能够将形变清楚为仿射分量和非仿射分量的独特性质，应用TPS函数来表征特征点集之间的非刚性映射，然后采用确定性退火技术，迭代求解点集之间的匹配矩阵和映射参数，与其它的非刚性匹配算法相比，该算法不仅保证了图像特征点之间的一一对应的双向约束，同时避免了陷入局部极小，而且具有较强的鲁棒性，实验结果证实了所提算法的有效性和鲁棒性。     

简化仿射投影算法在回声抵消中的应用

针对通信中的回声抵消,介绍了一种简化的仿射投影算法,通过对仿射投影的简化,减小了算法复杂度,并对算法进行了鲁棒性设计,提高了算法的抗干扰能力和对近端语音的鲁棒性.仿真表明,算法在保持APA算法的收敛速度和信道跟踪能力的同时,具有较高的稳定性和可靠性.     

变步长自适应滤波算法的统一框架及其矢量扩展

针对大量的变步长自适应滤波算法,提出了一种采用约束最优化方法描述变步长自适应滤波算法的统一框架.在该框架下,不同算法的目标函数或决策变量不同.利用该框架,将非参数变步长归一化最小均方误差(NPVSS-NLMS)算法扩展到矢量空间,导出一种新的变步长仿射投影算法.理论分析与计算机仿真表明,该算法不仅能根据输出误差自适应调整步长,而且对强相关输入信号能够保持良好的收敛速度、很小的稳态误差和很快的跟踪速度.将该算法应用于回波抵消,其稳态误差比NPVSS-NLMS算法低近5dB.     

Family of fast linearly independent ternary arithmetic transforms

In this paper, the family of fast linearly independent ternary arithmetic (LITA) transforms, which possesses fast forward and inverse butterfly diagrams, has been identified. This family is recursively defined and has consistent formulas relating forward and inverse transform matrices. The LITA transforms, which require horizontal or vertical permutations to have fast transforms are also discussed. Computational costs of the calculation for presented transforms are also discussed and compared with multipolarity ternary arithmetic transform for ternary benchmark functions.     

The Impossibility of Basing One-Way Permutations on Central Cryptographic Primitives

We know that trapdoor permutations can be used to construct all kinds of basic cryptographic primitives, including trapdoor functions, public-key encryption, private information retrieval, oblivious transfer, key agreement, and those known to be equivalent to one-way functions such as digital signature, private-key encryption, bit commitment, pseudo-random generator and pseudo-random functions. On the other hand, trapdoor functions are not as powerful as trapdoor permutations, so the structural property of permutations seems to be something special that deserves a more careful study. In this paper we investigate the relationships between one-way permutations and all these basic cryptographic primitives. Following previous works, we focus on an important type of reductions called black-box reductions. We prove that no such reductions exist from one-way permutations to either trapdoor functions or private information retrieval. Together with previous results, all the relationships with one-way permutations have now been established, and we know that no such reductions exist from one-way permutations to any of these primitives except trapdoor permutations. This may have the following meaning, with respect to black-box reductions. We know that one-way permutations imply none of the primitives in "public cryptography," where additional properties are required on top of "one-wayness" \cite{IR89}, so permutations cannot be traded for any of these additional properties. On the other hand, we now know that none of these additional properties can be traded for permutations either. Thus, being a permutation seems to be something orthogonal to those additional properties on top of one-wayness. Like previous non-reducibility results, our proofs follow the oracle separation paradigm of Impagliazzo and Rudich.     

One-way permutations on elliptic curves

In recent years one-way functions have been shown to have important applications in cryptography, especially one-way functions that are also permutations. But even with the generality of this research, no function is known to be one-way and the few specific permutations believed to be one-way are all invertible in subexponential time. Elliptic curves offer new permutations that appear to require exponential time for inversion. The permutations are essentially generalizations of discrete exponentiation that rely on newly demonstrated correspondences between elements of elliptic curves and the integers.Support for this research was provided in part by the National Science Foundation under Contract Number MCS-8006938. A preliminary version appeared as part of an MIT Ph.D. thesis [16]. Part of this work was done while the author was visiting Rochester Institute of Technology.     

Multifold Euclidean geometry codes

This paper presents a class of majority-logic decodable codes whose structure is based on the structural properties of Euclidean geometries (EG) and codes that are invariant under the affine group of permutations. This new class of codes contains the ordinary EG codes and some generalized EG codes as subclasses. One subclass of new codes is particularly interesting: they are the most efficient majority-logic decodable codes that have been constructed.     

Practical methods for rapid and accurate computation ofinterferometric spectra for remote sensing applications

The apodization of an interferogram corresponds to a linear transformation in spectral space between unapodized and apodized radiances. Many apodization functions have well-behaved numerical inverse transformations, and we show an analytic inverse for the Hamming apodization function. The inverse transformation has many practical uses for remote sensing applications and can also be used theoretically to show the equivalence between unapodized spectra and properly apodized spectra. The inverse transformation, which is a representation of the discrete convolution theorem, can be used to readily convert computed apodized spectra to spectra computed for other symmetric apodization functions (including unapodized), which may have poorer characteristics with regard to calculating channel-transmittance parameters or radiances. We also show a quantitative method for comparing apodization functions of different mathematical forms     

Finding Quadratic Schedules for Affine Recurrence Equations Via Nonsmooth Optimization

Frequently, affine recurrence equations can be scheduled more efficiently by quadratic scheduling functions than by linear scheduling functions. In this paper, the problem of finding optimal quadratic schedules for affine recurrence equations is formulated as a convex nonsmooth programming problem. In particular, sufficient constraints for causality are used generalizing Lamport's condition. In this way, the presented problem formulation becomes independent of the problem size. The research tool AQUAD is described implementing this problem formulation. Several nontrivial examples demonstrate that AQUAD can be effectively used to calculate quadratic schedules for affine recurrence equations. Finally, it is shown how array processors can be synthesized from affine recurrence equations which are scheduled by quadratic functions with a singular Hessian matrix.     

An upper bound onk/nfor affine-invariant codes with fixedd/n(Corresp.)

An upper bound on the transmission ratiok/nfor binary cyclic codes whose extended codes are invariant under the affine group of permutations, is presented. As a consequence, the transmission ratiok/nof any affine-invariant code with a fixedd(minimum weight)/nis shown to approach zero as the code length n increases. This is an extension of the Lin and Weldon result for primitive BCH codes.     

The q-ary image of some qm-ary cyclic codes: permutationgroup and soft-decision decoding

Using a particular construction of generator matrices of the q-ary image of q^m-ary cyclic codes, it is proved that some of these codes are invariant under the action of particular permutation groups. The equivalence of such codes with some two-dimensional (2-D) Abelian codes and cyclic codes is deduced from this property. These permutations are also used in the area of the soft-decision decoding of some expanded Reed-Solomon (RS) codes to improve the performance of generalized minimum-distance decoding     

对一个正形置换构造方法的修正及其计数结果的改进

证明利用邢育森等人提出的一种由,n-2元正形置换直接构造,n元正形置换的迭代构造方法构造的多输出函数并不是正形置换,指出了该构造方法存在的问题.通过对该方法构造的多输出函数的输出重新进行定义,对该方法进行了修正,并基于修正方法给出了正形置换的新的计数下界.