12,946 research outputs found

    Analog implementation of a robust control strategy for mechanical systems

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    An analog implementation of a control structure with disturbance identification for mechanical systems is presented. This control structure is based on a discontinuous observer that estimates the state and the disturbances in the plant, improving the robustness of the closed loop system which also displays a control input free from chattering. The control structure, built with operational amplifiers, is simple, showing good performance for stabilization, regulation, and tracking objectives. The performance of the circuit is compared with a digital implementation based on a real-time data acquisition card to control a simple pendulum. In addition, the circuit performance is illustrated on an industrial 2-DOF robot

    VVV High Proper Motion Survey

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    Here we present survey of proper motion stars towards the Galactic Bulge and an adjacent plane region base on VISTA-VVV data. The searching method based on cross-matching photometric Ks-band CASU catalogs. The most interesting discoveries are shown.Peer reviewe

    Long-term Stellar Variability in the Galactic Centre Region

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    © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.We report the detection of variable stars within a 11.5' x 11.5' region near the Galactic centre (GC) that includes the Arches and Quintuplet clusters, as revealed by the VISTA Variables in the Via Lactea (VVV) survey. There are 353 sources that show Ks-band variability, of which the large majority (81%) correspond to red giant stars, mostly in the asymptotic giant branch (AGB) phase. We analyze a population of 52 red giants with long-term trends that cannot be classified into the typical pulsating star categories. Distances and extinctions are calculated for 9 Mira variables, and we discuss the impact of the chosen extinction law on the derived distances. We also report the presence of 48 new identified young stellar object (YSO) candidates in the region.Peer reviewe

    Quantum Lightning Never Strikes the Same State Twice

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    Public key quantum money can be seen as a version of the quantum no-cloning theorem that holds even when the quantum states can be verified by the adversary. In this work, investigate quantum lightning, a formalization of "collision-free quantum money" defined by Lutomirski et al. [ICS'10], where no-cloning holds even when the adversary herself generates the quantum state to be cloned. We then study quantum money and quantum lightning, showing the following results: - We demonstrate the usefulness of quantum lightning by showing several potential applications, such as generating random strings with a proof of entropy, to completely decentralized cryptocurrency without a block-chain, where transactions is instant and local. - We give win-win results for quantum money/lightning, showing that either signatures/hash functions/commitment schemes meet very strong recently proposed notions of security, or they yield quantum money or lightning. - We construct quantum lightning under the assumed multi-collision resistance of random degree-2 systems of polynomials. - We show that instantiating the quantum money scheme of Aaronson and Christiano [STOC'12] with indistinguishability obfuscation that is secure against quantum computers yields a secure quantum money schem

    A strategy for implementing non-perturbative renormalisation of heavy-light four-quark operators in the static approximation

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    We discuss the renormalisation properties of the complete set of ΔB=2\Delta B = 2 four-quark operators with the heavy quark treated in the static approximation. We elucidate the role of heavy quark symmetry and other symmetry transformations in constraining their mixing under renormalisation. By employing the Schroedinger functional, a set of non-perturbative renormalisation conditions can be defined in terms of suitable correlation functions. As a first step in a fully non-perturbative determination of the scale-dependent renormalisation factors, we evaluate these conditions in lattice perturbation theory at one loop. Thereby we verify the expected mixing patterns and determine the anomalous dimensions of the operators at NLO in the Schroedinger functional scheme. Finally, by employing twisted-mass QCD it is shown how finite subtractions arising from explicit chiral symmetry breaking can be avoided completely.Comment: 41 pages, 6 figure

    Relativistic Hartree-Fock-Bogoliubov model for deformed nuclei

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    The relativistic Hartree-Fock-Bogoliubov model for axially deformed nuclei (RHFBz) is introduced. The model is based on an effective Lagrangian with density-dependent meson-nucleon couplings in the particle-hole channel, and the central part of the Gogny force is used in the pairing channel. The RHFBz quasiparticle equations are solved by expansion in the basis of a deformed harmonic oscillator. Illustrative RHFBz calculations are performed for carbon, neon, and magnesium isotopes. The effect of explicitly including the pion field is investigated for binding energies, deformation parameters, and charge radii and has an impact on the nuclei’s shape
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