Refined frequency estimates for stability domains of synchronization systems

n this paper we examine stability of Lur’e-type systems arising as a feedback superpositions infinite-dimensional linear blocks, described by integrodifferential Volterra equations, and periodic nonlinearities. Such have multiple equilibria, so traditional methods investigation, defined for with single equilibrium are no good here. In the Popov method priori integral indices is combined two special techniques: Leonov’s nonlocal reduction Bakaev-Guzh procedure. As result new frequency–algebraic criteria established, yielding tightened estimates domains in space system’s parameters.