A numerical method for the evaluation of complex integrals

A numerical method for evaluating the complex integralI = frac{1}{2pij} oint frac{B(z)B(z^{-1})}{A(z)A(z^{-1})} frac{dz}{z}along the unit circle in a positive direction (whereAandBare polynomials with real coefficients), is presented in this paper. The method developed in this paper is shown to be obtainable as a FORTRAN program as well as a table form. The results achieved represent significant reduction of the computations compared to other existing methods.     

On the strictly positive realness of Schur interval functions

Necessary and sufficient conditions for strictly positive realness of discrete-time interval functions, which may be associated in parameter space by a multidimensional boxed domain, are provided. Positive realness of interval functions are studied, and both necessary and sufficient conditions are provided for such functions to be strictly positive real (SPR) in the presence of interval variations of the function's parameters corresponding to a Kharitonov-type box domain. The number of checking functions that have to be tested for SPR property in order to establish the interval SPR property grows with the order of the interval function. These tests give both necessary and sufficient conditions for SPR. The approach presented for interval functions does not require the checking of all the vertices for unit circle positive realness     

Strategy, the final frontier

All agree that every organisation needs a strategy. Every organisation claims to have one. Yet few agree as to its appearance, meaning and intention. Most definitions have one thing in common: that strategy is at the very root of an organisation. strategy is a set of choices about ways of dealing with the political, economic, social and technological environment, and which serve to guide and co-ordinate all the plans and actions that the organisation needs. The author discusses the theory and practice of business strategy with particular reference to European Gas Turbines. Strategic approaches and layered strategies are discussed     

On the stability of a general polynomial in the space of Markov parameters

Markov parameters and the associated stability criterion were first introduced for continuous-time real polynomials. Recently, robust stability of such polynomials was considered in Markov parameters space, where efficient robust stability tests were obtained based on the Markov theorem. This has motivated the authors to extend the above idea to more general types of polynomials, and develop Markov parameters and the associated stability criterion for complex continuous-time as well as real and complex discrete-time polynomials. Moreover, for each polynomial type, we present compact relations in order to recover the coefficients of a polynomial corresponding to a given set of Markov parameters. The stability results presented here may be useful for 1-D and 2-D filtering and control applications.     

On the strict- and wide-sense stability robustness of uncertain systems: application of a new frequency criterion

In this paper, we discuss a new frequency-domain graphical approach for robust stability of uncertain systems. This method is based on Mikhailov's criterion and it requires the plotting of only one Hodograph and evaluation of two boundary conditions. Moreover, this approach is extended to a more general robust stability sense, i.e., extended and wide-sense Hurwitz stability, which may be applied to a number of robustness problems such as positivity, nonnegativity, spectral analysis, and array processing.     

A general z-transform formula for sampled-data systems

In this paper a generalized formulation for the convolutionztransform is presented. The advent of this formulation could cover most of the sampled-data cases discussed in the literature. This includes nonsynchronized, cyclic rate, multirate, and nonsynchronized multirate sampling. Furthermore, the use of this formula lies in its applications to certain forms of nonlinear discrete analysis, as well as to time-varying cases. Each of the applications is singled out, and the proper references are cited.