太阳黑子活动周期特征的小波自相关分析

太阳黑子数是描述太阳活动水平的主要指标,太阳活动直接影响日地环境.依据前人对太阳黑子数的观测资料,采用小波分析和自相关相结合的方法,分析了1770-1869年的太阳黑子数年均值,得出了太阳黑子存在11-12年周期的结论;用该算法对噪声的鲁棒性进行了验证;结果表明该方法对研究太阳活动规律乃至天体规律是有效的.     

Economic design of autoregressive moving average control chart using genetic algorithms

When designing control charts, it is usually assumed that the observations from the process at different time points are independent. However, this assumption may not be true for some production processes, e.g., the continuous chemical processes. The presence of autocorrelation in the process data can result in significant effect on the statistical performance of control charts. Jiang, Tsui, and Woodall (2000) developed a control chart, called the autoregressive moving average (ARMA) control chart, which has been shown suitable for monitoring a series of autocorrelated data. In the present paper, we develop the economic design of ARMA control chart to determine the optimal values of the test and chart parameters of the chart such that the expected total cost per hour is minimized. An illustrative example is provided and the genetic algorithm is applied to obtain the optimal solution of the economic design. A sensitivity analysis shows that the expected total cost associated with the control chart operation is positively affected by the occurrence frequency of the assignable cause, the time required to discover the assignable cause or to correct the process, and the quality cost per hour while producing in control or out of control, and is negatively influenced by the shift magnitude in process mean.     

Multi-objective optimisation of bijective s-boxes

In this paper we investigate the heuristic construction of bijective s-boxes that satisfy a wide range of cryptographic criteria including algebraic complexity, high nonlinearity, low autocorrelation and have none of the known weaknesses including linear structures, fixed points or linear redundancy. We demonstrate that the power mappings can be evolved (by iterated mutation operators alone) to generate bijective s-boxes with the best known tradeoffs among the considered criteria. The s-boxes found are suitable for use directly in modern encryption algorithms. Joanne Fuller, Ph.D.: She is a research associate at the Information Security Institute of Queensland University of Technology in Brisbane, Australia. She received her Ph.D. from out in 2004. William Millan, Ph.D.: He is a postdoctoral research fellow at the Information Security Institute of Queensland University of Technology in Brisbane, Australia. He pioneered the use of Evolutionary Computation techniques to develop new cryptographic primitives, notably new Boolean functions and S-boxes for block and stream ciphers, and has published many papers in this area. Ed Dawson, Ph.D.: He is the Director of the Information Security Institute of Queensland University of Technology in Brisbane, Australia. He has published more than 200 papers in Crypto conferences and Journals. He has served as Program Committee Member for more than 50 International Conferences in Cryptology and Network Security. He is currently a member of the Board of Directors of International Association for Cryptologic Research (IACR).     

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.     

基于SystemView的扩频码设计与性能评估

扩频系统的抗干扰、保密、多址、捕获与跟踪等都与扩频码的性能密切相关，因此扩频码设计与评估成为各类扩频系统的核心技术。由于伪码设计的纷繁复杂性，使得利用计算机实现扩频码的生成和性能评估成为必由之路。本文从扩频码的基本要求入手，总结了扩频码中常用的脚序列和Gold序列的特点，并基于SystemView平台编制了脚序列和Gold序列的生成程序及相关性、平衡性等性能评估程序，提供了所有程序的System View模型。仿真结果验证了本文方法的正确性和可行性，对工程技术人员有较大的参考价值。     

Reducing error in neural network time series forecasting

Neural network time series forecasting error comprises autocorrelation error, due to an imperfect model, and random noise, inherent in the data. Both problems are addressed here, the first using a two stage training, growth-network neuron: the autocorrelation error (ACE) neuron. The second is considered as a post-processing noise filtering problem. These techniques are applied in forecasting the sunspot time series, with comparison of stochastic, BFGS and conjugate gradient solvers.     

PCS颗粒测量技术中软件相关方法的研究

数字相关是PCS颗粒测量技术中的一个关键环节，自相关函数的估计质量直接影响颗粒测量的结果。自相关函数的估计可以通过硬件或软件方法得到。在软件数字相关方法中，利用相关计算时可以得到全部的采样数据这一与硬件相关所不同的特点，能去除采样数据中的均值，并在分析偏差的基础上，采用无偏估计，可有效地提高信噪比，从而获得更好的相关估计值。     

Distributed Sea Clutter Denoising Algorithm Based on Variational Mode Decomposition

In order to improve the detection accuracy of chaotic small signal prediction models under the background of sea clutter, a distributed sea clutter denoising algorithm is proposed, on the basis of variational modal decomposition (VMD). The sea clutter signal is decomposed into variational modal functions (VMF) with different center bandwidths by means of VMD. By analyzing the autocorrelation characteristics of the decomposed signal, we perform instantaneous half-period (IHP) and wavelet threshold denoising processing on the high-frequency and low-frequency components respectively, and regain the sea clutter signals. Based on LSSVM sea clutter prediction model, this research compares and analyzes the denoising effects of VMD. Experiment results show that, the RMSE after denoising is reduced by two orders of magnitude, approximating 0.00034, with an apparently better denoising effect, compared with the root mean square error (RMSE) of the prediction before denoising.     

Approximate mean waiting time in a GI/D/1 queue with autocorrelated times to failures

In this paper, we study process completion time and propose an accurate approximation for the mean waiting time in queues with servers experiencing autocorrelated times to failure, which include only busy periods from a repair completion until the next failure. To do this, we employ a three-parameter renewal approximation that represents the stream of autocorrelated times to failure. The approximation gives rise to a renewal interruption process with two-state Hyper-exponential (H2) times to failure. Then we compute the mean waiting time exactly in a queue experiencing H2 times to failure when the job arrival process is Poisson. This model provides an approximation for the mean waiting time of the original queue having an autocorrelated disruption process. We also propose an accurate approximation for queues with renewal job arrival processes when the server interruption process is general.