Circle and Popov Criterion for Output Feedback Stabilization of Uncertain Systems

In this paper, we address the problem of output feedback stabilization for a class of uncertain dynamical systems. An asymptotically stabilizing controller is proposed under the assumption that the nominal system is absolutely stable

Zeros of polynomials orthogonal with respect to a signed weight

AbstractIn this paper we consider the monic polynomial sequence (Pnα,q(x)) that is orthogonal on [−1,1] with respect to the weight function x2q+1(1−x2)α(1−x),α>−1,q∈N; we obtain the coefficients of the tree-term recurrence relation(TTRR) by using a different method from the one derived in Atia et al. (2002) [2]; we prove that the interlacing property does not hold properly for (Pnα,q(x)); and we also prove that, if xn,nα+i,q+j is the largest zero of Pnα+i,q+j(x), x2n−2j,2n−2jα+j,q+j<x2n−2i,2n−2iα+i,q+i,0≤i<j≤n−1

Magnetic field induced control of breather dynamics in a single plaquette of Josephson junctions

We present a theoretical study of inhomogeneous dynamic (resistive) states in a single plaquette consisting of three Josephson junctions. Resonant interactions of such a breather state with electromagnetic oscillations manifest themselves by resonant current steps and voltage jumps in the current-voltage characteristics. An externally applied magnetic field leads to a variation of the relative shift between the Josephson current oscillations of two resistive junctions. By making use of the rotation wave approximation analysis and direct numerical simulations we show that this effect allows to effectively control the breather instabilities, e. g. to increase (decrease) the height of the resonant steps and to suppress the voltage jumps in the current-voltage characteristics.Comment: 4 pages, 3 figure

Revised structural phase diagram of (Ba0.7Ca0.3TiO3)-(BaZr0.2Ti0.8O3)

The temperature-composition phase diagram of barium calcium titanate zirconate (x(Ba0.7Ca0.3TiO3)(1-x)(BaZr0.2Ti0.8O3); BCTZ) has been reinvestigated using high-resolution synchrotron x-ray powder diffraction. Contrary to previous reports of an unusual rhombohedral-tetragonal phase transition in this system, we have observed an intermediate orthorhombic phase, isostructural to that present in the parent phase, BaTiO3, and we identify the previously assigned T-R transition as a T-O transition. We also observe the O-R transition coalescing with the previously observed triple point, forming a phase convergence region. The implication of the orthorhombic phase in reconciling the exceptional piezoelectric properties with the surrounding phase diagram is discussed

The Kalman condition for the boundary controllability of coupled parabolic systems. Bounds on biorthogonal families to complex matrix exponentials

International audienceThis paper is devoted to prove the controllability to trajectories of a system of $n$ one-dimensional parabolic equations when the control is exerted on a part of the boundary by means of $m$ controls. We give a general \textit{Kalman condition} (necessary and sufficient) and also present a construction and sharp estimates of a biothorgonal family in L^{2}(0,T; \C) to $\{ t^{j}e^{-\Lambda_{k}t}\}$.Cet article a pour but de démontrer la contrôlabilité des trajectoires d’un système de $n$ équations paraboliques en une dimension d’espace par $m$ contrôles exercés sur une partie du bord. On obtient une condition de Kalman (nécessaire et suffisante). La démonstration passe par la construction dans L^{2}(0,T; \C) d’une famille biorthogonale de la suite $\{ t^{j}e^{-\Lambda_{k}t}\}$ et par une estimation de la norme de ses éléments

Kink propagation in a two-dimensional curved Josephson junction

We consider the propagation of sine-Gordon kinks in a planar curved strip as a model of nonlinear wave propagation in curved wave guides. The homogeneous Neumann transverse boundary conditions, in the curvilinear coordinates, allow to assume a homogeneous kink solution. Using a simple collective variable approach based on the kink coordinate, we show that curved regions act as potential barriers for the wave and determine the threshold velocity for the kink to cross. The analysis is confirmed by numerical solution of the 2D sine-Gordon equation.Comment: 8 pages, 4 figures (2 in color

Adsorptive removal of Methylene Blue, from aqueous solution using Tea Waste as a Low-Cost indigenous biosorbent: Mechanism of Adsorption, Equilibrium Study, Kinetics and Isotherms

For the current investigation, extracted Tea-Waste has been employed without activation for Methylene Blue removing in aqueous media. The experiment has been operated under batch conditions. The impact of a variety of significant factors affecting adsorption process, of which, adsorbent particle size, adsorbent/adsorbate shaking time, adsorbent dose, pH medium as well as the adsorbate initial concentration on Methylene Blue removing were investigated for optimization of the process according to the One Factor At a Time approach. The laboratory results revealing that this process is both spontaneously occurring and feasible. It has been demonstrated that maximal removing percentage (R) of 78.92% was obtained at a maximal experimental adsorption capacity (Qm,exp) of 7.892 mg.g-1. Methylene Blue adsorptive to Tea-Waste was according to the (S-class) isotherm. The Pseudo-Second-Order Kinetic Model agrees perfectly with results, with an adsorption capacity calculated (Qe,cal) of 7.194 mg.g-1. Also, we can affirm a best fitting adsorptive process through Langmuir's isothermal model, this confirms an adsorptive effect occurring in homogeneous area of Tea-Waste. Maximum calculated adsorption capacity (Qm,cal) defined by using Langmuir's has proven up to 14.085 mg.g-1. Consequently, the research suggests that Tea-Waste is a highly interesting option for efficiently treating real wastewater polluted by Methylene Blue