won{gil park [won{gil park, j. math. anal. appl., 376 (1) (2011) 193{202] proved the hyers{ulam stability of the cauchy functional equation, the jensen functional equation and the quadraticfunctional equation in 2{banach spaces. one can easily see that all results of this paper are incorrect.hence the control functions in all theorems of this paper are not correct. in this paper, we correctthes...

in the present paper a solution of the generalizedquadratic functional equation$$f(kx+ y)+f(kx+sigma(y))=2k^{2}f(x)+2f(y),phantom{+} x,yin{e}$$ isgiven where $sigma$ is an involution of the normed space $e$ and$k$ is a fixed positive integer. furthermore we investigate thehyers-ulam-rassias stability of the functional equation. thehyers-ulam stability on unbounded domains is also studied.applic...

In this paper, we solve the quadratic $alpha$-functional equations $2f(x) + 2f(y) = f(x + y) + alpha^{-2}f(alpha(x-y)); (0.1)$ where $alpha$ is a fixed non-Archimedean number with $alpha^{-2}neq 3$. Using the fixed point method and the direct method, we prove the Hyers-Ulam stability of the quadratic $alpha$-functional equation (0.1) in non-Archimedean Banach spaces.

this paper addresses adaptive observer design problem for joint estimation of the states and unknown parameters for a class of nonlinear systems which satisfying one-sided lipschitz and quadratic inner bounded conditions. it’s shown that the stability of the proposed observer is related to finding solutions to a quadratic inequality consists of state and parameter errors. a coordinate transform...

In this paper, a nonlinear phase finite impulse response (FIR) filter is designed without imposing a desired phase response. The maximum passband group delay of the filter is minimized subject to a positivity constraint on the passband group delay response of the filter as well as a specification on the maximum absolute difference between the desired magnitude square response and the designed m...

We report 96 inequalities with common structure, all elementary to state but many not elementary to prove. If n is a positive integer, a = (a1,..., an) and b = (b1,..., bn) are arbitrary vectors in R(+)n=[0,infinity)n, and rho(mij) is the spectral radius of an n x n matrix with elements m(ij), then, for example: [equation: see text]. The second inequality is obtained from the first inequality b...

This paper is concerned with the stability of linear systems a time-varying delay. First, we derive new form constrained quadratic matrix inequality for reciprocally convex inequality. Second, an equivalent transform into inequality(LMI) derived. Third, upper bound time derivative Lyapunov Krasovskii functional(LKF), in matrix, obtained, and done to make it LMI. Finally, improvement shown throu...

Abstract: This paper is considered with the problem of robust absolute stability of neutral type Lur’e systems with mixed time-varying delays. By constructing an new augmented Lyapunov-Krasovskii functional and combining integral inequality with approach to estimate the derivative of the Lyapunov-Krasovskii functional, which estimated some integral terms by Wirtinger’s inequality, a matrix-base...