1,844 research outputs found

    Nonlinear dynamics in superlattices driven by high frequency ac-fields

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    We investigate the dynamical processes taking place in nanodevices driven by high-frequency electromagnetic fields. We want to elucidate the role of different mechanisms that could lead to loss of quantum coherence. Our results show how the dephasing effects of disorder that destroy after some periods coherent oscillations, such as Rabi oscillations, can be overestimated if we do not consider the electron-electron interactions that can reduce dramatically the decoherence effects of the structural imperfections. Experimental conditions for the observation of the predicted effects are discussed.Comment: REVTEX (8 pages) and 4 figures (Postscript

    Neon seeding effects on two JET high performance baseline plasmas

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    Neon seeding effects on two JET high performance baseline plasmas

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    Are the Secrecy Order Compensation Provisions of the Patent Act Constitutional Under the Fifth Amendment?

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    The secrecy order provisions of the Patent Act\u27 raise a number of issues under the U.S. Constitution. The primary focus of this note is on the Fifth Amendment issues raised by the Invention Secrecy Act

    An active learning pipeline for surrogate models of gyrokinetic turbulence

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    Digital twinning of a tokamak device requires fast system state inference. Physics-based computational models that predict future states are often too slow to be actionable, and thus undesirable for offline scenario planning. These tasks may be performed faster if the physics-based model is replaced by a neural network-based surrogate. Obtaining the labels to train the surrogate can be computationally expensive, additionally, some inputs may result in trivial outputs. Here we propose a two-stage active learning pipeline for digital twinning of gyrokinetic turbulence in the core of tokamak fusion plasmas. Our pipeline leverages an uncertainty-based acquisition function which greatly outperforms random acquisition and leads to a reduction of 99.6% in the amount of input-output mappings needed from the physical model without compromising on performance.</p

    An active learning pipeline for surrogate models of gyrokinetic turbulence

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