The design of S-boxes by simulated annealing

Substitution boxes (S-boxes) are important components in many modern-day symmetric key ciphers. Their study has attracted a great deal of attention over many years. The emergence of a variety of cryptosystem attacks has shown that substitutions must be designed with great care. Some general criteria such as high non-linearity and low autocorrelation have been proposed (providing some protection against attacks such as linear cryptanalysis and differential cryptanalysis). The design of appropriate S-boxes is a difficult task; several criteria must be traded off and the design space is huge. There has been little application of evolutionary search to the development of S-boxes. In this paper we show how a cost function that has found excellent single-out put Boolean functions can be generalised to provide improved results for small S-boxes. John A. Clark: He is Professor of Critical Systems at the University of York, where he leads the software testing, security and cryptography work. Much of this has been concerned with the application of meta-heuristic search. Jeremy L. Jacob: He has a BSc. in Mathematics from the University of Hull, England, M.Sc. and D. Phil. in Computation from the University of Oxford, England and now works for the Univerity of York. His research interests include modelling secure systems and software engineering practices for secure systems. Susan Stepney: She is Professor of computer Science at the University of York, and leads the Non-Standard Computation research group there. She is a member of the ACM, Fellow of the British Computer Society, and moderator of the UKCRC Grand Challenge in Non-Classical Computation. Her main research interests include novel applications of nature-inspired computation, modelling self-organising complex systems and designing and reasoning about emergent properties.     

Feistel结构的8比特轻量化S盒

轻量化S盒作为轻量级对称密码算法的混淆部件,是设计轻量级对称密码算法的关键.提出一种新的8比特轻量化S盒设计方法,其单轮逻辑运算仅涉及4个单比特逻辑与运算和4个单比特逻辑异或运算,迭代4轮后密码性质可达到差分均匀度为16、非线性度为96.与目前已有轻量化S盒设计方法相比,新的8比特轻量化S盒设计方法在硬件实现资源小的同...     

高精度数据驱动型TDC在高能物理实验中应用的研究

目前国际国内高能物理方面时间数字转换的发展趋势是使用集成的、高精度、多次击中型TDC,数据驱动型TDC(Data Driven TDC)是其中的热点.研究高性能TDC的具体指标以及改进的方法对高能物理实验中的应用具有指导作用.我们对北京谱仪(BESⅢ)中考虑使用的一种新型高精度TDC进行了测量研究.本文介绍了我们为此建立的测量平台,和对该TDC进行非线性、分辨率、双脉冲分辨等测量的手段和结果,探讨了对其进行甚高精度(24.4 ps)修正的方法,给出了修正的效果.     

机械设计中的非线性动力学和动态设计一些问题

分析了机械系统中非线性动力学的主要特点和动态设计的一些问题,论述了它与振动学科中其他分支学科的关系,提出了一些有兴趣的前沿新课题：包括机械主传动系统中的扭转振动,机构运动弹性动力学,机械结构强度问题、高速机构动态设计方法学等,这些总是不仅有重要的实用价值,而且是非线性动力学与动态设计方法的新发展。     

Improved system identification method for Hammerstein-Wiener processes

We propose a new system identification method for Hammerstein-Wiener processes, in which an input static nonlinear block, a linear dynamic block, and an output static nonlinear block are connected in a series. The proposed method can estimate the model parameters in a very simple way without solving the full-dimensional nonlinear optimization problem by activating the process with a specially designed test signal, composed of a relay feedback signal, a binary signal and a multi-step signal. The proposed method analytically identifies the output nonlinear static function and the input nonlinear static function from the relay signal and the multi-step signal, respectively. The linear dynamic subsystem is identified from the relay feedback signal and the binary signal with existing well-established linear system identification methods. We demonstrate with a simple example that the proposed method can be successfully applied to identify the Hammerstein-Wiener-type nonlinear process.     

PV3型轴向柱塞泵的仿真及其非线性特征的研究

本文对轴向柱塞泵的非线性特征进行了深入的分析与研究,给出了准确完整的数学描述。而且数字仿真的方法,进行了改进,使其能够适用于非线性模型尤其非连续模型的仿真,从而为今后通过数字仿真对变量泵的各种非线性控制器的优化设计打下了良好的基础。     

Bouc-Wen滞回模型的直接表示形式及其工程应用

Bouc-Wen模型广泛用于描述工程结构中的非线性滞回特性,然而该模型中的滞回恢复力与相对位移变形量的关系以微分形式给出,不能直接迭代滞回模型到系统运动控制方程, 从而增加了解析法分析系统动力响应的难度.文中提出采用直接表示形式代替Bouc-Wen的微分模型,在弱非线性情况下,假定滞回恢复力可以表示为相对变形位移的指数形式,并进一步用泰勒展开的方法表示为简单的多项式形式.通过实例分析,验证多项式直接表示模型的可行性,其中二阶近似形式比一阶近似形式更为接近微分模型.将该直接表示模型应用于单自由度振动系统中,发现系统的动力响应和采用微分模型的响应基本吻合,其中具有软特性的系统响应尤为接近.     

分光镜对外差激光干涉仪非线性的影响

外差干涉仪的非线性误差不仅由激光源的椭圆偏振态或者非正交线偏振态引起,也由非理想的光学器件引起,其中分光镜是一个重要的误差源。除了通常熟知的偏振漏光,还分析偏振分光镜中可能存在的另一个误差,即偏振分光的正交性,介绍这种误差和其他各种原因(包括激光源的椭圆偏振态或者非正交线偏振态)对外差干涉仪非线性误差的影响,给出检测和区分两类不同频率混叠误差的方法。通过试验证实,偏振分光镜的漏光误差对外差干涉仪非线性的影响通常是可以被忽略不计的。试验研究还发现,与传统的理论假设相反,非偏振分光镜比偏振分光镜对外差干涉仪的非线性误差有着更严重的影响。     

有限元线法求解非线性模型问题——Ⅰ.薄膜大挠度

本研究将新近发展起来的有限元线法应用于非线性问题,分析求解了若干具有代表性的模型问题,探讨了统一的求解模式及相应的处理手段。作为这一系列工作的首例,本文将该法应用于薄膜大挠度这一几何非线性模型问题,对任意形状的薄膜作了理论公式推导,通过对几种典型形状薄膜的具体数值计算,揭示了该类问题存在极限变形状态这一重要特性。数值算例的精确性与可靠性以及求解的高效性表明,本法是求解这类几何非线性问题的高效能的方法。     

关于高度非线性平衡布尔函数的构造

本文利用Ｗａｌｓｈ谱分析了文献「１」中所构造的布尔函数的非线性度；证明了Ｆ＾２ｋ２上不存在满足２ｋ－１次扩散准则的平衡布尔函数。