We present a novel model-order reduction (MOR) method for linear time-invariant systems that preserves passivity and is thus suited structure-preserving MOR port-Hamiltonian (pH) systems. Our algorithm exploits the well-known spectral factorization of Popov function by solution Kalman–Yakubovich–Popov (KYP) inequality. It performs directly on factor inheriting original system’s sparsity enablin...

We show that an exact non-perturbative quantization of continuum gauge theory is provided by the Faddeev-Popov formula in Landau gauge, δ(∂ · A) det[−∂ · D(A)] exp[−S YM (A)], restricted to the region where the Faddeev-Popov operator is positive −∂ · D(A) > 0 (Gribov region). Although there are Gribov copies inside this region, they have no influence on expectation-values. The starting point of...

This note analyzes the stability robustness of a Maximum Entropy controller designed for a benchmark problem. Four robustness tests are used: small gain analysis, circle analysis, positive real analysis, and Popov analysis, each of which is guaranteed to give a less conservative result than the previous test. The analysis here is performed graphically although recent research has developed equi...

A possibility to greatly enhance frequencyconversion efficiency of stimulated Raman scattering is shown by making use of extraordinary properties of threewave mixing of ordinary and backward waves. Such processes are commonly attributed to negative-index plasmonic metamaterials. This work demonstrates the possibility to replace such metamaterials that are very challenging to engineer by readily...

The method of geodesic expansions is systematically explained. Based on the Haar measures of the group of geodesic expansions the semiclassical sum over immersed manifolds is constructed. Gauge fixing is performed via the Faddeev Popov method.