A family of simultaneous zero finding methods

A class of iterative methods with arbitrary high order of convergence for the simultaneous approximation of multiple complex zeros is considered in this paper. A special attention is paid to the fourth order method and its modifications because of their good computational efficiency. The order of convergence of the presented methods is determined. Numerical examples are given.     

A pre- + post- + feedforward compensator design for zero placement

We demonstrate the design of a pre- + post- + feedforward compensator that places the transmission zeros of a stabilisable and detectable multi-input multi-output linear-time-invariant plant at arbitrary locations.     

Characterization of zero locations of polytopes of real polynomials

Given a stability region of a polytope of polynomials, the edge theorem can be used to verify certain root-clustering properties of the polytope. The authors consider the inverse problem; starting with a polytope of real polynomials, they present a result that allows the construction of the smallest set of regions in the complex plane which characterizes its zero location     

Time-domain identification of transmission zero locations of linear multivariable plants

In the case of asymptotically stable multivariable plants, the location in the complex plane of the transmission zeros is identified on the basis of the initial and ultimate time-domain behavior of the step-response matrix.     

Solving genus zero Diophantine equations over number fields

Let K be a number field and F(X,Y) an absolutely irreducible polynomial of K[X,Y] such that the algebraic curve defined by the equation F(X,Y)=0 is rational. In this paper we present practical algorithms for the determination of all solutions of the Diophantine equation F(X,Y)=0 in algebraic integers of K.     

Determining number of clusters and prototype locations via multi-scale clustering

In clustering algorithms, it is usually assumed that the number of clusters is known or given. In the absence of such a priori information, a procedure is needed to find an appropriate number of clusters. This paper presents a clustering algorithm that incorporates a mechanism for finding the appropriate number of clusters as well as the locations of cluster prototypes. This algorithm, called multi-scale clustering, is based on scale-space theory by considering that any prominent data structure ought to survive over many scales. The number of clusters as well as the locations of cluster prototypes are found in an objective manner by defining and using lifetime and drift speed clustering criteria. The outcome of this algorithm does not depend on the initial prototype locations that affect the outcome of many clustering algorithms. As an application of this algorithm, it is used to enhance the Hough transform technique.     

Plant zero structure and further order reduction of a singular H∞ controller

A new class of reduced‐order controllers is obtained for the H_∞ problem. The reduced‐order controller does not compromise the performance attained by the full‐order controller. Algorithms for deriving reduced‐order H_∞ controllers are presented in both continuous and discrete time. The reduction in order is related to unstable transmission zeros of the subsystem from disturbance inputs to measurement outputs. In the case where the subsystem has no infinite zeros, the resulting order of the H_∞ controller is lower than that of the existing reduced‐order H_∞ controller designs which are based on reduced‐order observer design. Furthermore, the mechanism of the controller order reduction is analysed on the basis of the two‐Riccati equation approach. The structure of the reduced‐order H_∞ controller is investigated. Copyright © 2002 John Wiley & Sons, Ltd.     

Improved lower bound on the number of balanced symmetric functions over GF(p)

The lower bound on the number of n-variable balanced symmetric functions over finite fields GF(p) presented by Cusick et al. in [T.W. Cusick, Y. Li, P. Staˇnicaˇ, Balanced symmetric functions over GF(p), IEEE Trans. Inform. Theory 54 (3) (2008) 1304-1307] is improved in this paper. An equivalent characterization is also presented for the general case.     

On the optimal choice of the electrode number and locations in body surface mapping

The problem of choosing the number and the thoracic locations of the leads needed for reconstructing body surface maps of heart potentials is considered. In a previous work (P. Barone, In "Computers in Cardiology" (K. L. Ripley, Ed.), pp. 491-494. IEEE Computer Soc. Press, Washington, DC, 1985) the problem was solved, provided that the user is able to give a threshold below which the information content of two leads is considered equal. In this paper a sensitivity analysis that can help the user in choosing the optimal threshold, or, equivalently, the optimal number of leads, is performed. The problem is reduced to the dynamic search of spanning forests of an undirected graph. An example using real data is also discussed.     

Linear-time string-matching using only a fixed number of local storage locations

We report a linear-time string-matching algorithm for a random-access machine without dynamic storage allocation. To do this, we tell how to adapt a cited algorithm to fill its dynamic storage needs by temporarily borrowing some of the space occupied by the input pattern. In automata-theoretic terms, we tell how to adapt the cited algorithm to run on a writing multihead finite automaton with a restricted writing alphabet.     

Simultaneous closed-loop tuning of cascade controllers based directly on set-point step-response data

This study presents a novel closed-loop tuning method for cascade control systems, in which both primary and secondary controllers are tuned simultaneously by directly using set-point step-response data without resorting to process models. The tuning method can be applied on-line to improve the performance of existing underperforming cascade controllers by retuning controller parameters, using routine operating data. The goal of the proposed design is to obtain the parameters of two proportional-integral-derivative (PID)-type controllers, so that the resulting inner and outer loops behave as similarly as possible to the appropriately specified reference models. The tuning rule and optimization problem related to the proposed design are derived. Based on the rationale behind cascade control, the secondary controller is designed based on disturbance rejection to quickly attenuate disturbances. The primary controller is designed to accurately account for the inner-loop dynamics, without requiring an additional test. In addition, robustness considerations are included in the proposed tuning method, which enable the designer to explicitly address the trade-off between performance and robustness for inner and outer loops independently. Simulation examples show that the proposed method exhibits superior control performance compared with the previous (model-based) tuning methods, confirming the effectiveness of this novel tuning method for cascade control systems.     

Sorting-Based Calculation of Zeros and Extrema of Functions as Applied to Search and Recognition. II

A stable address sorting and an extrema localization condition based on it are applied for approximate calculation of complex roots of polynomials and zeros of derivatives of functions of one variable. This method is used to localize extrema in discrete numerical sequences, to identify chains of repeating figures, and, on the basis of all this, to search for and recognize patterns presented as numerical arrays.     

利用局部极值点特性的多聚焦图像快速融合

目的：多聚焦图像融合技术一个关键问题是如何准确地判断待融合图像的清晰度。本文提出了基于归一化结构极值点数目的清晰度判断准则。方法：本文基于图像的局部极值点特性,定义了归一化结构极值点数目这个指标作为清晰度判断准则,同时还给出了利用该准则和融合决策矩阵快速估计技术的多聚焦图像快速融合方法。结果：利用本文提出的清晰度判断准则和融合方法,实验表明上述问题得到了很好的解决。结论：本文提出了一个新的图像清晰度判断准则,该准则判断准确率高,且对脉冲噪声有好的鲁棒性。通过与传统融合方法对两组实验图像融合结果的主客观比较表明,该方法的融合速度和效果比现有多聚焦图像融合方法有明显提高。     

具有零动态仿射非线性系统控制Lyapunov函数的构造

研究具有零动态仿射非线性系统控制Lyapunov函数的构造问题.提出通过求解一个Lyapunov方程获得可线性化部分的二次型控制Lyapunov函数.由可线性部分的控制Lyapunov函数和零动态部分的Lyapunov函数,通过构造一个正定函数,得到了整个系统的控制Lyapunov函数,且设计了可半全局镇定整个闭环系统的控制律.仿真实例说明了所提出方法的有效性.     

Further results on structural assignment of linear systems via sensor selection

The problem of assigning structural properties of a linear system through sensor selection is, for a given pair (A,B), to find an output pair (C,D) such that the resulting system (A,B,C,D) has the pre-specified structural properties, such as the finite and infinite zero structures and the invertibility properties. In this paper, by introducing the notion of infinite zero assignable sets for the pair (A,B), we establish necessary and sufficient conditions for the assignability of a given set of infinite zeros and a set of structural properties which includes the left invertibility property. In establishing these conditions, we develop a numerical algorithm for the construction of the required (C,D).     

桁架结构振动的主动模糊控制中主动杆数目与位置优化

研究了采用自适应模糊控制器抑制桁架结构振动时的主动杆数目与位置优化问题.通过定义输入能量相关矩阵优化了主动杆的数目.基于主动杆的控制能量配置准则,给出了主动杆优化配置的模型.研究基于整数编码的遗传算法用于大型离散体中的作动器组合优化问题.最后针对挠性空间智能桁架结构的振动控制仿真,使用基于整数编码的遗传算法(GAs)优化主动杆位置.结果表明对于采用自适应模糊控制律的离散体结构振动控制是行之有效的.     

Nonlinear inferential multi-rate control of Kappa number at multiple locations in a continuous pulp digester

The continuous pulp digester represents a large-scale, distributed parameter system. Control of the spatial profile of degree of cooking, characterized by the Kappa number, rather than its endpoint value can effectively control properties that are dependent on the history of cooking. However, profile control of such large-scale distributed parameter systems throws up new challenges in estimation and control. We design a nonlinear model predictive controller using a multi-rate extended Kalman filter to infer and control discrete points along the Kappa number profile. Both, the plant and controller models are based on first principles. The design is tested for significant mismatches in parameters, initial state errors, and stochastic disturbances in the entering wood composition.     

Interpolation with constraint on frequency region and systems & control application

This paper elaborates on a bitangential interpolation problem with a norm constraint of the interpolant on a given frequency region (and on its generalization), and proves that it admits a solution. A motivation from systems & control for the problem is given, and the solution is applied for construction of a stabilizing control for one-block plants such that the closed-loop transfer matrix is norm-constrained on the frequency region. Illustrative numerical examples are given.     

雪崩布尔函数的构造方法及个数估计

研究了满足严格雪崩准则布尔函数的性质,证明了雪崩布尔函数的汉明重量只能为偶数,并且得到了雪崩布尔函数的汉明重量之集,给出了不同汉明重量的雪崩布尔函数的构造方法。改进了雪崩布尔函数个数的下界。