Résultats récents sur la théorie des formes quadratiques
The paper is devoted to the problem of robust stability of positive continuous-time linear systems with delays with structured perturbations of state matrices. Simple necessary and sufficient conditions for robust stability in the general case and in the case of systems with a linear uncertainty structure in two sub-cases: (i) a unity rank uncertainty structure and (ii) nonnegative perturbation matrices are established. The problems are illustrated with numerical examples.
An matrix with nonnegative entries is called row stochastic if the sum of entries on every row of is 1. Let be the set of all real matrices. For , we say that is row Hadamard majorized by (denoted by if there exists an row stochastic matrix such that , where is the Hadamard product (entrywise product) of matrices . In this paper, we consider the concept of row Hadamard majorization as a relation on and characterize the structure of all linear operators preserving (or...