7,802 research outputs found

    Relevance of multiple-quasiparticle tunneling between edge states at \nu =p/(2np+1)

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    We present an explanation for the anomalous behavior in tunneling conductance and noise through a point contact between edge states in the Jain series ν=p/(2np+1)\nu=p/(2np+1), for extremely weak-backscattering and low temperatures [Y.C. Chung, M. Heiblum, and V. Umansky, Phys. Rev. Lett. {\bf{91}}, 216804 (2003)]. We consider edge states with neutral modes propagating at finite velocity, and we show that the activation of their dynamics causes the unexpected change in the temperature power-law of the conductance. Even more importantly, we demonstrate that multiple-quasiparticles tunneling at low energies becomes the most relevant process. This result will be used to explain the experimental data on current noise where tunneling particles have a charge that can reach pp times the single quasiparticle charge. In this paper we analyze the conductance and the shot noise to substantiate quantitatively the proposed scenario.Comment: 4 pages, 2 figure

    Global gyrokinetic simulations of ITG turbulence in the configuration space of the Wendelstein 7-X stellarator

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    We study the effect of turbulent transport in different magnetic configurations of the Weldenstein 7-X stellarator. In particular, we performed direct numerical simulations with the global gyrokinetic code GENE-3D, modeling the behavior of Ion Temperature Gradient turbulence in the Standard, High-Mirror, and Low-Mirror configurations of W7-X. We found that the Low-Mirror configuration produces more transport than both the High-Mirror and the Standard configurations. By comparison with radially local simulations, we have demonstrated the importance of performing global nonlinear simulations to predict the turbulent fluxes quantitatively

    Advanced composite materials in precision machine tools sector - Applications and perspectives

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    The most recent R&D activities and applications of advanced materials for designing and fabrication of light and damped structures of precision machine tools (MT), are here presented. These new solutions include carbon fibres reinforced polymers (CFRP), hybrid sandwiches and novel multifunctional smart structures

    Bringing global gyrokinetic turbulence simulations to the transport timescale using a multiscale approach

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    The vast separation dividing the characteristic times of energy confinement and turbulence in the core of toroidal plasmas makes first-principles prediction on long timescales extremely challenging. Here we report the demonstration of a multiple-timescale method that enables coupling global gyrokinetic simulations with a transport solver to calculate the evolution of the self-consistent temperature profile. This method, which exhibits resiliency to the intrinsic fluctuations arising in turbulence simulations, holds potential for integrating nonlocal gyrokinetic turbulence simulations into predictive, whole-device models.Comment: 7 pages, 3 figure

    Saving energy in aggressive intrusion detection through dynamic latency sensitivity recognition

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    In an always connected world, cyber-attacks and computer security breaches can produce significant financial damages as well as introduce new risks and menaces in everyday's life. As a consequence, more and more sophisticated packet screening/filtering solutions are deployed everywhere, typically on network border devices, in order to sanitize Internet traffic. Despite the obvious benefits associated to the proactive detection of security threats, these devices, by performing deep packet inspection and inline analysis, may both affect latency-sensitive traffic introducing non-negligible delays, and increase the energy demand at the network element level. Starting from these considerations, we present a selective routing and intrusion detection technique based on dynamic statistical analysis. Our technique separates latency-sensitive traffic from latency-insensitive one and adaptively organizes the intrusion detection activities over multiple nodes. This allows suppressing directly at the network ingress, when possible, all the undesired components of latency-insensitive traffic and distributing on the innermost nodes the security check for latency sensitive flows, prioritizing routing activities over security scanning ones. Our final goal is demonstrating that selective intrusion detection can result in significant energy savings without adversely affecting latency-sensitive traffic by introducing unacceptable processing delays. \ua9 2017 Elsevier Ltd

    Phonon distributions of a single bath mode coupled to a quantum dot

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    The properties of an unconventional, single mode phonon bath coupled to a quantum dot, are investigated within the rotating wave approximation. The electron current through the dot induces an out of equilibrium bath, with a phonon distribution qualitatively different from the thermal one. In selected transport regimes, such a distribution is characterized by a peculiar selective population of few phonon modes and can exhibit a sub-Poissonian behavior. It is shown that such a sub-Poissonian behavior is favored by a double occupancy of the dot. The crossover from a unequilibrated to a conventional thermal bath is explored, and the limitations of the rotating wave approximation are discussed.Comment: 21 Pages, 7 figures, to appear in New Journal of Physics - Focus on Quantum Dissipation in Unconventional Environment
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