A recursive formula for the correlations of Walsh functions

The correlation function of two Walsh functions appears in image processing, signal multiplexing, detection and spectral analysis using Walsh functions. Though Walsh functions are two-valued, their correlation functions are real-valued and rather difficult to evaluate. A recursive formula is developed in this paper to evaluate the correlation functions. Some other properties of the correlation function are also discussed.     

A fuzzy linear programming model for the optimization of multi-stage supply chain networks with triangular and trapezoidal membership functions

Supply chain management (SCM) is concerned with a complex business relations network that contains interrelationships between various entities, such as suppliers, manufacturers, distribution centers and customers. SCM integrates these entities and manages their interrelationships through the use of information technology to meet customer expectations (i.e., higher product variety and quality, lower costs and faster responses) effectively along the entire value chain. Thus, one of the vital issues in supply chain management is the design of the value chain network. In this paper, a fuzzy linear programming model for the optimization of the multi-stage supply chain model with triangular and trapezoidal membership functions is presented. The model determines the fuzzy capacities of the facilities (plants or distribution centers (DCs)) and the design of the network configuration with a minimum total cost. The total cost involves the shipping cost from suppliers; transportation costs between plants and DCs; distribution costs between DCs and customer zones; and opportunity costs from not having the material at the right time. The developed model is solved by a professional software package (LINDO), and the computational results are discussed.     

一种基于Haar小波和归一化的鲁棒零水印算法

应用小波变换和改进的几何归一化方法,提出一种强鲁棒图像零水印算法.该算法首先利用一种改进的几何归一化方法将原始图像化为标准图像,然后对标准图像利用Haar小波进行多级小波分解,最后根据高层的中高频小波系数的正负极性构造零水印.对算法性能进行测试的结果表明,算法对噪声、滤波、有损压缩等常规信号处理具有强鲁棒性,对旋转、缩放、平移、剪切等几何攻击也具有较好的鲁棒性.     

Walsh series approach to lumped and distributed system identification

This paper considers the problem of identifying the parameters of dynamic systems from input-output records. Both lumped-parameter and distributed-parameter systems, deterministic and stochastic, are studied. The approach adopted is that of expanding the system variables in Walsh series. The key point is an operational matrix P which relates the coefficient matrix Г of the Walsh series of a given function with the coefficient matrix of its first derivative. Using this operational matrix P one overcomes the necessity to use differentiated data, a fact that usually is avoided either by integration of the data or by using discrete-time models. Actually, the original differential input-output model is converted to a linear algebraic (or regression) model convenient for a direct (or a least squares) solution. A feature of the method is that it permits the identification of unknown initial conditions simultaneously with the parameter identification. The results are first derived for single-input single-output systems and then are extended to multi-input multi-output systems. The case of non-constant parameters is treated by assuming polynomial forms. Some results are also included concerning the identification of state-space and integral equation models. The theory is supported by two examples, which give an idea of how effective the method is expected to be in the real practice.     

Distribution and density functions of probability of error over slowly fading channels with diversity combining

In this letter, the distribution and density functions of the probability of error for Rayleigh and Rician fading channels with L-fold diversity are derived and plotted for various values of mean signal energy-to-noise ratio.     

Drawing a spark from darkness: John Walsh and electric fish

John Walsh's research on electric fish, carried out between 1772 and 1775, proved fundamental for demonstrating that electricity might be involved in animal physiology, and, moreover, in favouring a period of great progress in both the physiology and physics of electrical phenomena. However, Walsh is hardly known to modern neuroscientists and is largely neglected by science historians also. One of the reasons for this neglect is that he never published his 'crucial experiment', that is the production of a spark from a discharge of the electric eel.     

Walsh Operational Matrices for Fractional Calculus and Their Application to Distributed Systems

The Walsh operational matrix for performing integration and solving state equations is generalized to fractional calculus for investigating distributed systems. A new set of orthogonal functions is derived from Walsh functions. By using the new functions, the generalized Walsh operational matrices corresponding to √s, √(s²+ 1), e^-s and e^-√s etc. are established. Several distributed parameter problems are solved by the new approach.     

基于游程统计和Walsh谱能量分布的调色板图像隐写分析

提出一种基于游程统计和Walsh谱能量分布的调色板图像隐写分析方法,利用调色板颜色的奇偶值(parity value,P值)构造P值图像,通过游程统计和Walsh变换提取出46维特征,并用校准技术削弱载体图像差异对分析统计量的干扰.实验表明,该方法适用于EzStego、分量和以及最佳奇偶隐写等调色板图像隐写算法,比奇异颜色分析准确.     

科学知识图谱的发展历程

 科学知识图谱是显示科学知识的发展进程与结构关系的一种图形,是科学计量学具有前景的研究方向。本章从引文分析和信息可视化角度介绍了科学知识图谱发展的历程,并分别介绍了传统的科学知识图谱类型和现代的三维构型图谱、多维尺度分析图谱、社会网络分析图谱、自组织映射图谱以及寻求路径图谱及其相应的原理。其研究进展表明,无论是对于科学技术研究,还是对于企业技术创新,科学知识图谱都是一种有效的知识管理工具。     

Optimum and suboptimum methods for permuting a matrix into bordered triangular form

In this paper we consider the problem of permuting a large sparse n×n matrix into an optimum bordered triangular form using nonsymmetric permutations. By making use of the degree switching operations in the digraph of the matrix and minimum essential set of the digraph we present a formal solution to the problem. Next we present an algorithm for finding a minimal essential set for a strongly connected digraph using the structural properties of the digraph. We also present an algorithm for permuting a n×n matrix into a near optimum bordered triangular form by making use of output set assignment concepts. Examples are given to illustrate our algorithms.     

引文分析领域前沿与演化知识图谱

 本文拟对引文分析这个领域运用可视化工具来做一个清晰的描绘。以“citation analysis” 为检索词在SCI和SSCI中联合检索到 1974 - 2006年期间747篇文献,23487条引文。对这些数据进行引文分析、聚类分析、多维尺度分析、社会网络分析,利用SPSS、NETDRAW、CITESPACE等可视化软件,绘制了引文分析领域前沿与演化的多张图谱,反映出引文分析领域的发展趋势和重要人物,展现了引文分析领域的知识结构关系与演进规律。     

Block-pulse functions method of the inverse laplace transform for irrational and transcendental transfer functions

A new direct method of the block-pulse functions technique of the inverse Laplace transform for irrational and transcendental transfer functions is presented. It is shown that the existing indirect method can be used equivalently with the new one. Two illustrative examples are given.     

Special functions of circuits and systems

The polynomial solutions of the equation fy″ + gy′ + λy = 0 are obtained and classified for f, g, and λ certain second-degree, first-degree, and zero-degree polynomials, respectively. Applications are given illustrating the use of these polynomials in the construction of amplitude functions and system functions and in tree counting. In particular, all-pole and rational filter functions are considered which include as special cases the Chebyshev, Butterworth, elliptic, Bessel, and various transitional filter functions.     

Adaptive resilient containment control for nonlower triangular multiagent systems with time-varying delay and sensor faults

This paper investigates the adaptive resilient containment control for nonlinear multiagent systems (MASs) with time-varying delay, unmodeled dynamics and sensor faults. To solve the coupling problem of unknown state delays and sensor faults in a nonlower triangular structure, we develop an effective method by using a new lemma and the Lyapunov-Krasovskii functional. Then, to reduce the negative impact of unknown sensor faults, a novel adaptive resilient containment control method is designed based on a distributed sliding-mode estimator, which can effectively improve the transient performance of the MASs. Moreover, by using a dynamic signal, the problem of unmodeled dynamics is solved. The proposed control scheme can not only drive all followers suffering from sensor faults to converge to the convex hull formed by the leaders but also relatively reduce the undesired chattering phenomenon. Finally, a comparative simulation example is given to illustrate the effectiveness of the proposed strategy.     

Stabilized generation of precise triangular waves,square waves and trapezoidal waves in three phases

A new three-dimensional compact oscillator model for generating three phases of triangular waves and square waves (and also trapezoidal waves) is developed by considering carefully a recently suggested model for the precise quadrature generation of similar waves in two phases. The properties of the solution of the new model equations are investigated and they suggest that the oscillator should possess applications for the design of relatively simple electronic three phase triangular and square wave generators. “Software” applications of the model and its employment for power systems simulations are also discussed briefly.     

改进的一致性哈希算法及应用

针对分布式入侵检测中的数据分割问题,给出一种改进的一致性哈希算法。该算法针对采集的数据包,通过TCP流重组建立TCP数据链,保证数据流的完整性;再通过结点的分组对一致性哈希算法进行改进,并实现组间和组内的数据分配,减少虚拟结点数量;对结点的负载均衡检测和调整策略,改善了系统的负载均衡性。仿真测试结果表明该算法具有较好的负载均衡性。     

Improved equalization and joint iterative detection

Intersymbol interference (ISI) degrades the bit error rate (BER) performance of sequential detectors such as maximum likelihood sequence detection (MLSD) and the maximum a posteriori (MAP) algorithm due to minimum distance reduction. This paper describes a novel rotation method that can increase the minimum distance and results in significant improvement in the BER performance for binary PSK and 4QAM systems when operating over severe ISI channels. Simulation results show that this method can improve the BER performance of systems employing MLSD and MAP turbo equalization by up to 4.6 dB compared to existing approaches including known precoding schemes.