Mahajan, S. M., & Asenjo, F. A. (2023). Parametric amplification of electromagnetic plasma waves in resonance with a dispersive background gravitational wave. Phys. Rev. E, 107(3), 035205.
Abstract: It is shown that a subluminal electromagnetic plasma wave, propagating in phase with a background subluminal gravitational wave in a dispersive medium, can undergo parametric amplification. For these phenomena to occur, the dispersive characteristics of the two waves must properly match. The response frequencies of the two waves (medium dependent) must lie within a definite and restrictive range. The combined dynamics is represented by a Whitaker-Hill equation, the quintessential model for parametric instabilities. The exponential growth of the electromagnetic wave is displayed at the resonance; the plasma wave grows at the expense of the background gravitational wave. Different physical scenarios, where the phenomenon can be possible, are discussed.
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Veliz-Tejo, A., Travieso-Torres, J. C., Peters, A. A., Mora, A., & Leiva-Silva, F. (2022). Normalized-Model Reference System for Parameter Estimation of Induction Motors. Energies, 15(13), 4542.
Abstract: This manuscript proposes a short tuning march algorithm to estimate induction motors (IM) electrical and mechanical parameters. It has two main novel proposals. First, it starts by presenting a normalized-model reference adaptive system (N-MRAS) that extends a recently proposed normalized model reference adaptive controller for parameter estimation of higher-order nonlinear systems, adding filtering. Second, it proposes persistent exciting (PE) rules for the input amplitude. This N-MRAS normalizes the information vector and identification adaptive law gains for a more straightforward tuning method, avoiding trial and error. Later, two N-MRAS designs consider estimating IM electrical and mechanical parameters. Finally, the proposed algorithm considers starting with a V/f speed control strategy, applying a persistently exciting voltage and frequency, and applying the two designed N-MRAS. Test bench experiments validate the efficacy of the proposed algorithm for a 10 HP IM.
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