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We consider the problem of joint angle and doppler estimation for Space-Time Adaptive Processing (STAP) airborne radar in non-gaussian clutter which is modeled as a complex symmetric alpha stable SαS process. We introduce a sign covariance estimate which has almost robust performance in heavy tailed noise [1]. The subspace estimate is calculated via the propagator method [2] to reduce the computational...
Both Discrete Cosine Transform (DCT) and Singular Value Decomposition (SVD) have been used as mathematical tools for embedding data into an image. In this paper, we present a new robust hybrid watermarking scheme based on DCT and SVD. After applying the DCT to the cover image, we map the DCT coefficients in a zig-zag order into four quadrants, and apply the SVD to each quadrant. These four quadrants...
The Dirty Paper Trellis Codes (DPTC) watermarking is a very efficient high capacity scheme. Nevertheless, it suffers of two drawbacks: its security weakness and its CPU computation complexity. In a previous work, we treat those drawbacks by proposing a more secure embedding space and a faster embedding technique. In the current paper, we study the robustness of the scheme with the use of a psychovisual...
Robust face segmentation and verification algorithms have been developed employing edge-based feature representations in the multiple resolution scheme. The face segmentation algorithm in our previous work [1] has shown the robustness against illumination, focus and scale variations. In addition to these features, a rotation-invariant scheme has been introduced in the present work. As a result, a...
This paper presents a robust seal imprint verification method with rotation invariance. The rotation invariant feature is represented by the absolute value of Fourier coefficients of log-polar image of seal imprint on circles with different radii. Firstly, the feature vector of a seal imprint is defined by the above absolute value of Fourier coefficients of the log-polar image. Secondly, the feature...
A framework for identification oriented robust controller design is developed. The model is identified from open-loop ilo-data and contains parametric uncertainties as well as an additive and norm-bounded error. The set of all robustly stabilising controllers, that additionally guarantee robust performance is characterised by a system of second order cones, which can be efficiently solved by interior...
This paper introduces a method to locate simultaneous leaks in a pipeline when only the inflow and outflow of the fluid are available. It is assumed that the fluid in the duct with fixed leaks positions can be described by an approximated finite dimensional model considering pressure at the end of the duct as control variables. This model is used to design a vector called residual pattern in steady...
The new approach of robust control systems synthesis, both linear, and nonlinear and non-stationary is offered. The control is carried out, providing the given phase constrains varied in acceptable limits, in view of constrains on its value and incompleteness of the information about functioning disturbances. The approach is based on introduction of auxiliary integral surfaces, on which the initial...
The problem of observer design for robust residual generation in nonlinear discrete-time systems is considered. The method is proposed to solve this problem involving nonlinear time-dependent transformation of state-space system model into strict feedback form. To make this transformation practicable, algebra of time-dependent functions is developed.
This paper considers the design of Transmit Pulse Shapes such that after transmission through a dispersive channel, the distorted pulse at the receiver fits in a prescribed template. The norm of the transmit pulse is minimized so as to reduce the effect of cross-talk at the receiver end. This design problem is formulated as a Quadratic Programming problem with affine functional inequality constraints...
An output feedback robust controller based on sliding modes and indirect adaptive control called Indirect Variable Structure Model Reference Adaptive Control (IVS-MRAC) was recently proposed for relative degree one LTI plants, suggesting to be globally asymptotically stable with superior transient behavior and disturbance rejection properties. In this paper, some remarkable simplifications are carried...
The paper describes a design methodology which allows dynamic and parametric modelling uncertainty to be treated simultaneously. It combines the advantages of H∞ control techniques with those provided by robust design methods based on a polytopic representation of parametric uncertainty. The proposed method uses the Q-parameterization of all solutions of the H∞ control problem in addition to the robust...
This paper addresses the problem of static output feedback synthesis and focuses on H2 optimisation. The bilinear problem of finding a control feedback gain K and a Lyapunov matrix P is shown to be equivalent to a BMI problem that involves slack variables and a state feedback gain. This BMI condition is a promising theoretical result that links the two state and output feedback questions in a unified...
This paper is concerned with the stability and control of linear systems with uncertain physical parameters. The case where the characteristic equations of the systems are polynomially dependent on uncertain parameters is studied. A new algorithm is presented for the calculation of stability margins in the parameter space in general / p-norms. The stability is defined with respect to a desired region...
This paper addresses the problem of stability robustness of minimum-phase nonlinear dynamical systems modeled with feedforward neural networks with bounded parametric uncertainties under IOF linearization. By means of an affine description of the feedforward neural network model which takes into account the parametric uncertainties, the Input-Output Feedback (IOF) linearization is performed and the...
In this paper, the regional pole placement is studied. An analysis of robustness with respect to unstructured uncertainty, being 2-norm bounded, for linear systems is discussed. A bound on the maximum allowable perturbation is proposed. Moreover, a useful parameterization of such bound, based on the structure of the gain matrix and on a novel formula for computing the eigenvectors of any real matrix,...
A new method is proposed for the solution of linear matrix inequalities over a finite horizon for linear discrete time varying systems with or without uncertainties. The method is used to solve a variety of problems beginning with the standard H∞ discrete-time bounded real lemma and extending through to robust H∞ general-filtering and output-feedback control design of uncertain systems. In the latter...
For both continuous and discrete-time cases, this paper presents a simple solution to the robust H∞ unbiased functional reduced order filtering problem via LMI methods in the presence of norm-bounded time-varying uncertainties. Necessary and sufficient conditions for the existence and the stability of the unbiased filter are given in the nominal case; the filter differs from that of 11] (only nominal...
In this paper, numerical optimisation in combination with a suitable parametrisation of all stable closed-loop systems is proposed as a tool for control structure selection. The key benefit is that the suitability of a control structure can be assessed without a priori information about the desired closed-loop behaviour or the controller structure. Thus, it constitutes an effective tool to explore...
This paper addresses robust H∞ static output feedback control problem for multimodel systems with time-varying normbounded uncertainties. Sufficient conditions for synthesis of a static output feedback controller are derived in terms of a set of linear matrix inequalities (LMIs). The effectiveness of the proposed design method is demonstrated by an example for the control of a multimodel constituted...
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