Otto Rösch

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We study the interaction of electrons with phonons in strongly correlated solids, having high-T(c) cuprates in mind. Using sum rules, we show that the apparent strength of this interaction strongly depends on the property studied. If the solid has a small fraction (doping) delta of charge carriers, the influence of the interaction on the phonon self-energy(More)
We present angle-resolved photoemission spectroscopy (ARPES) data on undoped La2CuO4, indicating polaronic coupling between bosons and charge carriers. Using a shell model, we calculate the electron-phonon coupling and find that it is strong enough to give self-trapped polarons. We develop an efficient method for calculating ARPES spectra in undoped(More)
We derive a t-J model with electron-phonon coupling from the three-band model, considering modulation of both hopping and Coulomb integrals by phonons. While the modulation of the hopping integrals dominates, the modulation of the Coulomb integrals cannot be neglected. The model explains the experimentally observed anomalous softening of the half-breathing(More)
Stabilizing controllers for non-linear input delay system of a lab helicopter are designed by first using a 3D search in the controller parameter space, the bounds of which are estimated by over-conservative controller parameters given by Lyapunov Razumikhin theory. Simulated Annealing and Genetic Algorithms are then used to find near-optimal controller(More)
In this paper, upper bounds for time-varying delays in the real-time control of a lab helicopter in the sense of practical stability analysis are derived. Sub-optimal controller parameters for this non-linear plant with a given maximum time-delay are calculated with the help of Lyapunov-Razumikhin method using LMIs (Linear Matrix Inequalities). These(More)
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