1,366 research outputs found

    Reply to Comment on "Quantum dense key distribution"

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    In this Reply we propose a modified security proof of the Quantum Dense Key Distribution protocol detecting also the eavesdropping attack proposed by Wojcik in his Comment.Comment: To appear on PRA with minor change

    Spanning avalanches in the three-dimensional Gaussian Random Field Ising Model with metastable dynamics: field dependence and geometrical properties

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    Spanning avalanches in the 3D Gaussian Random Field Ising Model (3D-GRFIM) with metastable dynamics at T=0 have been studied. Statistical analysis of the field values for which avalanches occur has enabled a Finite-Size Scaling (FSS) study of the avalanche density to be performed. Furthermore, direct measurement of the geometrical properties of the avalanches has confirmed an earlier hypothesis that several kinds of spanning avalanches with two different fractal dimensions coexist at the critical point. We finally compare the phase diagram of the 3D-GRFIM with metastable dynamics with the same model in equilibrium at T=0.Comment: 16 pages, 17 figure

    Nontrivial dependence of dielectric stiffness and SHG on dc bias in relaxors and dipole glasses

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    Dielectric permittivity and Second Harmonic Generation (SHG) studies in the field-cooled mode show a linear dependence of dielectric stiffness (inverse dielectric permittivity) on dc bias in PMN-PT crystals and SHG intensity in KTaO3_{3}:Li at small Li concentrations. We explain this unusual result in the framework of a theory of transverse, hydrodynamic-type, instability of local polarization.Comment: 5 figure

    A simple test for the existence of two accretion modes in Active Galactic Nuclei

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    By analogy to the different accretion states observed in black-hole X-ray binaries (BHXBs), it appears plausible that accretion disks in active galactic nuclei (AGN) undergo a state transition between a radiatively efficient and inefficient accretion flow. If the radiative efficiency changes at some critical accretion rate, there will be a change in the distribution of black hole masses and bolometric luminosities at the corresponding transition luminosity. To test this prediction, I consider the joint distribution of AGN black hole masses and bolometric luminosities for a sample taken from the literature. The small number of objects with low Eddington-scaled accretion rates mdot < 0.01 and black hole masses Mbh < 10^9 Msun constitutes tentative evidence for the existence of such a transition in AGN. Selection effects, in particular those associated with flux-limited samples, systematically exclude objects in particular regions of the black hole mass-luminosity plane. Therefore, they require particular attention in the analysis of distributions of black hole mass, bolometric luminosity, and derived quantities like the accretion rate. I suggest further observational tests of the BHXB-AGN unification scheme which are based on the jet domination of the energy output of BHXBs in the hard state, and on the possible equivalence of BHXB in the very high (or "steep power-law") state showing ejections and efficiently accreting quasars and radio galaxies with powerful radio jets.Comment: Accepted by ApJ; 14 pages, 4 figures, uses emulateap

    Self-supervised pre-training of CNNs for flatness defect classification in the steelworks industry

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    Classification of surface defects in the steelworks industry plays a significant role in guaranteeing the quality of the products. From an industrial point of view, a serious concern is represented by the hot-rolled products shape defects and particularly those concerning the strip flatness. Flatness defects are typically divided into four sub-classes depending on which part of the strip is affected and the corresponding shape. In the context of this research, the primary objective is evaluating the improvements of exploiting the self-supervised learning paradigm for defects classification, taking advantage of unlabelled, real, steel strip flatness maps. Different pre-training methods are compared, as well as architectures, taking advantage of well-established neural subnetworks, such as Residual and Inception modules. A systematic approach in evaluating the different performances guarantees a formal verification of the self-supervised pre-training paradigms evaluated hereafter. In particular, pre-training neural networks with the EgoMotion meta-algorithm shows classification improvements over the AutoEncoder technique, which in turn is better performing than a Glorot weight initialization. © 2020, Universitas Ahmad Dahlan. All rights reserved

    nonlinear model predictive control strategy for steam turbine rotor stress

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    Abstract The paper proposes a Nonlinear Model Predictive Control strategy for the control of steam turbines rotor thermal stresses, which exploits the approximation of the turbine rotor as an infinite cylinder subjected to external convection. The Nonlinear Model Predictive Control allows optimizing the control strategy in the long term, by significantly reducing the machine start-up time during the power up ramp. This study proposes two different control strategies: the former one is based on the control of the Heat Transfer Coefficient, correlated to the inlet valve stroke. The latter one is based on the control of Heat Transfer Coefficient and the boiler steam temperature reference. Both strategies achieve good results in shortening the start-up time. The overall approach is validated and currently under development on Programmable Logic Controller platforms to the aim of code optimization

    Effects of two plant oil-based products on the mortality of red palm weevil and morpho-physiological characteristics of palm

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    The red palm weevil (RPW), Rhynchophorous ferrugineus Oliver (Coleoptera: Curculionidae), is an economically important, tissue-boring pest of date palm in many parts of the world. The aim of the work was to investigate the effects of two plant oil-based products (BRK6 and BRK9) on the mortality of RPW (Exp. 1) and morpho-physiological characteristics of palm (Exp. 2). Laboratory experiments showed that the two mixture of oils BRK6 and BRK9 showed larvicide and adulticide properties. These properties were more pronounced on BRK9 than BRK6. The lethal concentration for 50% of individuals (LC50) calculated by probit, of BRK6 was 0.22% (for the 90% of individuals LC90 = 0.34) while for BRK9 the calculated LC50 was 0.10% (LC90 = 0.66). These data show that a smaller amount of BRK9 oil was required to induce the 50% of mortality of RPW larvae. As regards to the adults, BRK9 and BRK6 were effective only at the highest concentration (2 and 5%, respectively). Finally, injection of BRK9 into the palm trunk showed to promote chlorophyll content and photosynthesis of leaves thanks to a good translocation of zinc

    A flowsheet-based model approach to reduce water consumption and improve water networks management in the steel sector

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    Resource consumption is an important topic for steelmaking industry, which is spending significant efforts to reduce its environmental impact and improve its competitiveness. Water is largely exploited in steelworks for indirect and direct cooling, specific surface treatment, and fumes washing and cooling. It is already reused and recycled after restoring its quality through treatments for temperature and/or pollutant reduction. However, sometimes water networks are not optimized due to outdated water treatments, lack of continuous monitoring, and water network management strategies often based on experience without automation. In recent years, new water treatments, simulation, and optimization tools are becoming available, together with a stronger awareness of the importance of online parameters monitoring. Therefore, improvement of water cleaning, reuse, recycling, and consequent reduction of impact related to water exploitation are potentially achievable. The introduction of innovative treatments must be tested before their implementation in steel plants and the exploration of their behavior in different operating conditions is fundamental. The presented work addresses this topic through the application of several models of operational units, developed in OpenModelica environment and aggregated into a plant simulator. The simulator was used in different case studies related to an Italian plant to assess the impact of new filtering technology for reducing suspended solids on the analyzed water networks and test the effects of different operating configurations on the treatment efficiency. The introduction of new filtration technology leads to environmental and economic advantages due to freshwater intake reduction and water management improvemen
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