9,550 research outputs found

    Creating temperature dependent Ni-MH battery models for low power mobile devices

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    In this paper the methodology and the results of creating temperature dependent battery models for ambient intelligence applications is presented. First the measurement technology and the model generation process is presented in details, and then the characteristic features of the models are discussed.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

    Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines

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    Single trajectories of magnetic line motion indicate the persistence of a central protected plasma core, surrounded by a chaotic shell enclosed in a double-sided transport barrier : the latter is identified as being composed of two Cantori located on two successive "most-noble" numbers values of the perturbed safety factor, and forming an internal transport barrier (ITB). Magnetic lines which succeed to escape across this barrier begin to wander in a wide chaotic sea extending up to a very robust barrier (as long as L<1) which is identified mathematically as a robust KAM surface at the plasma edge. In this case the motion is shown to be intermittent, with long stages of pseudo-trapping in the chaotic shell, or of sticking around island remnants, as expected for a continuous time random walk.Comment: TEX file, 84 pages including 32 color figures. Higher quality figures can be seen on the PDF file at http://membres.lycos.fr/fusionbfr/JHM/Tokamap/JSP.pd

    Scalar mesons in a linear sigma model with (axial-)vector mesons

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    The structure of the scalar mesons has been a subject of debate for many decades. In this work we look for qˉq\bar{q}q states among the physical resonances using an extended Linear Sigma Model that contains scalar, pseudoscalar, vector, and axial-vector mesons both in the non-strange and strange sectors. We perform global fits of meson masses, decay widths and amplitudes in order to ascertain whether the scalar qˉq\bar{q}q states are below or above 1 GeV. We find the scalar states above 1 GeV to be preferred as qˉq\bar{q}q states.Comment: 6 pages, 1 figure, To appear in the proceedings of the XII. Hadron Physics Conference, Bento Goncalves, Brasil, April, 22 - 27, 201

    Elastic alpha-scattering of 112Sn and 124Sn at astrophysically relevant energies

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    The cross sections for the elastic scattering reactions {112,124}Sn(a,a){112,124}Sn at energies above and below the Coulomb barrier are presented and compared to predictions for global alpha-nucleus potentials. The high precision of the new data allows a study of the global alpha-nucleus potentials at both the proton and neutron-rich sides of an isotopic chain. In addition, local alpha-nucleus potentials have been extracted for both nuclei, and used to reproduce elastic scattering data at higher energies. Predictions from the capture cross section of the reaction 112Sn(a,g)116Te at astrophysically relevant energies are presented and compared to experimental data.Comment: 20 pages, 10 figures, accepted for publication in Phys. Rev.

    Sequential Symbolic Regression with Genetic Programming

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    This chapter describes the Sequential Symbolic Regression (SSR) method, a new strategy for function approximation in symbolic regression. The SSR method is inspired by the sequential covering strategy from machine learning, but instead of sequentially reducing the size of the problem being solved, it sequentially transforms the original problem into potentially simpler problems. This transformation is performed according to the semantic distances between the desired and obtained outputs and a geometric semantic operator. The rationale behind SSR is that, after generating a suboptimal function f via symbolic regression, the output errors can be approximated by another function in a subsequent iteration. The method was tested in eight polynomial functions, and compared with canonical genetic programming (GP) and geometric semantic genetic programming (SGP). Results showed that SSR significantly outperforms SGP and presents no statistical difference to GP. More importantly, they show the potential of the proposed strategy: an effective way of applying geometric semantic operators to combine different (partial) solutions, avoiding the exponential growth problem arising from the use of these operators

    Total reaction cross sections from elastic alpha-nucleus scattering angular distributions around the Coulomb barrier

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    The total reaction cross section σreac\sigma_{\rm{reac}} is a valuable measure for the prediction of α\alpha-induced reaction cross sections within the statistical model and for the comparison of scattering of tightly bound projectiles to weakly bound and exotic projectiles. Here we provide the total reaction cross sections σreac\sigma_{\rm{reac}} derived from our previously published angular distributions of α\alpha-elastic scattering on 89^{89}Y, 92^{92}Mo, 112,124^{112,124}Sn, and 144^{144}Sm at energies around the Coulomb barrier.Comment: 4 pages, 2 figures, Phys. Rev. C, accepted as Brief Repor

    Generalized Killing equations and Taub-NUT spinning space

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    The generalized Killing equations for the configuration space of spinning particles (spinning space) are analysed. Simple solutions of the homogeneous part of these equations are expressed in terms of Killing-Yano tensors. The general results are applied to the case of the four-dimensional euclidean Taub-NUT manifold.Comment: 10 pages, late

    High precision 89^{89}Y(α\alpha,α\alpha)89^{89}Y scattering at low energies

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    Elastic scattering cross sections of the 89^{89}Y(α\alpha,α\alpha)89^{89}Y reaction have been measured at energies Ec.m._{c.m.} = 15.51 and 18.63 MeV. The high precision data for the semi-magic N=50N = 50 nucleus 89^{89}Y are used to derive a local potential and to evaluate the predictions of global and regional α\alpha-nucleus potentials. The variation of the elastic alpha scattering cross sections along the N=50N = 50 isotonic chain is investigated by a study of the ratios of angular distributions for 89^{89}Y(α\alpha,α\alpha)89^{89}Y and 92^{92}Mo(α\alpha,α\alpha)92^{92}Mo at Ec.m._{c.m.} \approx 15.51 and 18.63 MeV. This ratio is a very sensitive probe at energies close to the Coulomb barrier, where scattering data alone is usually not enough to characterize the different potentials. Furthermore, α\alpha-cluster states in 93^{93}Nb = 89^{89}Y \otimes α\alpha are investigated

    Investigation of alpha-nuclear potential families from elastic scattering experiments

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    In this work we present the continuation of the reported analysis [1] of the experimentally measured angular distributions of the reaction Cd-106(alpha, alpha)Cd-106 at several different energies around the Coulomb barrier. The difficulties that arise in the study of Cd-106-alpha-nuclear potential and the so called Family Problem are addressed
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