Sub- and ultraharmonic (SUH) ultrasound contrast imaging is an alternative modality to the second harmonic imaging, since, in specific conditions it could produce high quality echographic images. This modality enables the contrast enhancement of echographic images by using SUH present in the contrast agent response but absent from the nonperfused tissue. For a better access to the components ge...

A novel recursive algorithm for identification of Hammerstein structures is developed. The linear and nonlinear parameters are separated and estimated recursively in a parallel manner, but each updating algorithm employs the estimation produced by the other at the previous time instant. Hence, it is termed the Alternately Recursive Least Square (ARLS) algorithm.When compared with Recursive Leas...

Rationalized Haar functions are developed to approximate the solution of the nonlinear Volterra–Fredholm–Hammerstein integral equations. The properties of rationalized Haar functions are first presented. These properties together with the Newton–Cotes nodes and Newton–Cotes integration method are then utilized to reduce the solution of Volterra–Fredholm–Hammerstein integral equations to the sol...

Abstract: In this paper, a Sinc-collocation method based on the double exponential transformation for solving Fredholm and Volterra Hammerstein integral equations is presented. Some properties of the Sinc-collocation method required for our subsequent development are given and utilized to reduce the computation of solution of the Hammerstein integral equations to some algebraic equations. Numer...

The paper presents a procedure for identification continuous-time Hammerstein systems. To improve the representation of the nonlinear functions, the set of basis functions is iteratively refined. It is possible to identify the dominant nonlinearities, applying a singular value decomposition to the input matrix. In our approach, the linear dynamic subsystem is described by a transfer function of...

In this paper a new system identification algorithm is introduced for Hammerstein systems based on observational input/output data. The nonlinear static function in the Hammerstein system is modelled using a non-uniform rational B-spline (NURB) neural network. The proposed system identification algorithm for this NURB network based Hammerstein system consists of two successive stages. First the...

The identification difficulties for a dual-rate Hammerstein system lie in two aspects. First, the identification model of the system contains the products of the parameters of the nonlinear block and the linear block, and a standard least squares method cannot be directly applied to the model; second, the traditional single-rate discrete-time Hammerstein model cannot be used as the identificati...

This article studies the subspace identification methods (SIMs) for Hammerstein systems with major focus on a rank constraint and the related dimension problem. We analyse the effects of the rank constraint on the three steps of a unifying framework for SIMs: the rank constraint has no effect on the first two steps, but does so on the third step. If the rank constraint is ignored, as in the exi...

In this paper, a new nonlinear discrete-time PID is proposed to control Hammerstein model. This model is composed by a static nonlinearity gain associated to a linear dynamic subsystem. Nonlinear polynomial structures are used to identify and to control this class of systems. The determination of parameters is based on the use of RLS algorithm. A coupled two-tank process is given to illustrate ...

Derived from the idea of stochastic approximation, recursive algorithms to identify a Hammerstein system are presented. Two of them recover the characteristic of the nonlinear memoryless subsystem while the third one estimates the impulse response of the linear dynamic part. The a priori information about both subsystems is nonparametric. Consistency in quadratic mean is shown and the convergen...