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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.compeleceng.2009.02.005 Byline: Youcef Ferdi Keywords: 1/f-Noise; Fractional order integral; Impulse invariance method; Signal modeling Abstract: This paper presents a simple and efficient method for the design of recursive digital fractional order integrator when the order of integration is a real number between 0 and 1. The proposed method is based on the impulse invariance method. First the initial value theorem is used for the selection of the initial value of the impulse response and then any of the well-established signal modeling techniques can be employed for the parameterization of the discrete impulse response by pole-zero models. For a given model order, the approximation accuracy greatly depends on the initial value selected. Illustrative examples are presented to demonstrate the effectiveness and usefulness of the proposed method. Author Affiliation: LRES Laboratory, Department of Electrical Engineering, University of Skikda, BP. 26, Route d'El-HadaA[R]ek, 21000, Skikda, Algeria Article History: Received 1 April 2007; Revised 7 January 2009; Accepted 10 February 2009

This paper presents a new procedure for generating 1/f[beta] noise sequences by filtering Gaussian white noise through a recursive filter approximating a discrete-time fractional order integrator. Power series expansion and deterministic signal modeling techniques were combined to determine a rational transfer function to approximate the ideal discrete fractional transfer function resulting from Al-Alaoui's rule raised to the power of the fractional order of integration. The proposed approach is computationally more efficient and more accurate than infinite impulse response truncation. Numerical results are provided to demonstrate the performance of the proposed method. Index Terms--Al-Alaoui's rule, fractional order integrator (FOI), power series expansion, Prony's method, Shanks' method, signal modeling, 1/f noise.

In this paper, an improved stable digital rational approximation of the fractional-order operator $$s^\alpha ,\alpha \in \,R$$ is developed. First, a novel efficient second-order digital differentiator is derived from the transfer function of the digital integrator proposed by Tseng. Then, the fractional power of the new s-to-z transform is expanded using power series expansion (PSE)-signal-modeling technique to obtain stable rational approximation of $$s^\alpha $$ . Simulation results show that the proposed rational approximation has better frequency characteristics in almost the whole frequency range than that of existing first-order s-to-z transforms based approximations for different values of the fractional-order $$\alpha $$ . This paper also shows the benefit of using PSE-signal-modeling approach with first- or second-order mapping functions over PSE-truncation approach that is used in recent works for rational approximation of the operator $$s^\alpha $$ , and highlights the major disadvantage of the latter approach that leads to undesirable rational models with complex conjugate poles and zeros. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes an approximate method for synthesizing sequences of statistically self-similar processes and analyses its performance to generate sample sequences with this statistical property. The method is based upon approximating the infinite dimensional difference equation which describes the FARIMA(0,α,0) model by a finite dimensional difference equation. The parameters estimation for parameterizing the binomial coefficients is performed by using deterministic signal modeling techniques. The three techniques considered are: Prony, Steiglitz MacBride, and Shaw methods. In addition to allow considerable savings in memory requirements and great reduction in computation time, the performance analysis results show that the generated sequences are statistically self-similar in the sense that the estimated Hurst parameter is very close to that imposed in the sequence generator. [Copyright &y& Elsevier]

The security of speech encryption systems is the major concern in different applications. In this paper, a new scheme to enhance the security of an FFT transform based speech encryption system is developed The main contribution of this paper is to enhance the security of encrypted speech using sixteen different permutations to encrypt each sixteen frames.. This scheme will increase the key space considerably. [ABSTRACT FROM AUTHOR]