41,748 research outputs found

    New method for critical failure prediction of complex systems

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    Rigorous analytical technique, called criticality determination methodology /or CD technique/ determines the probability that a given complex system will successfully achieve stated objectives. The CD technique identifies critical elements of the system by a failure mode and effects analysis

    The incidence of mid-infrared excesses in G and K giants

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    Using photometric data from the 2MASS and GLIMPSE catalogues, I investigate the incidence of mid-infrared excesses (~10 microns) of G and K stars of luminosity class III. In order to obtain a large sample size, stars are selected using a near-IR colour-magnitude diagram. Sources which are candidates for showing mid-IR excess are carefully examined and modelled to determined whether they are likely to be G/K giants. It is found that mid-IR excesses are present at a level of (1.8 +/- 0.4) x 10^-3. While the origin of these excesses remains uncertain, it is plausible that they arise from debris discs around these stars. I note that the measured incidence is consistent with a scenario in which dust lifetimes in debris discs are determined by Poynting-Robertson drag rather than by collisions.Comment: Accepted for publication in MNRAS. 13 pages, 5 figures, 2 tables (1 landscape table

    Small Energy Scale for Mixed-Valent Uranium Materials

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    We investigate a two-channel Anderson impurity model with a 5f15f^1 magnetic and a 5f25f^2 quadrupolar ground doublet, and a 5f25f^2 excited triplet. Using the numerical renormalization group method, we find a crossover to a non-Fermi liquid state below a temperature T∗T^* varying as the 5f25f^2 triplet-doublet splitting to the 7/2 power. To within numerical accuracy, the non-linear magnetic susceptibility and the 5f15f^1 contribution to the linear susceptibility are given by universal one-parameter scaling functions. These results may explain UBe13_{13} as mixed valent with a small crossover scale T∗T^*.Comment: 4 pages, 3 figures, REVTeX, to appear in Phys. Rev. Let

    On alpha stable distribution of wind driven water surface wave slope

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    We propose a new formulation of the probability distribution function of wind driven water surface slope with an α\alpha-stable distribution probability. The mathematical formulation of the probability distribution function is given under an integral formulation. Application to represent the probability of time slope data from laboratory experiments is carried out with satisfactory results. We compare also the α\alpha-stable model of the water surface slopes with the Gram-Charlier development and the non-Gaussian model of Liu et al\cite{Liu}. Discussions and conclusions are conducted on the basis of the data fit results and the model analysis comparison.Comment: final version of the manuscript: 25 page

    The bosonic Kondo effect

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    The Kondo effect is associated with the formation of a many-body ground state that contains a quantum-mechanical entanglement between a (localized) fermion and the free fermions. We show that a bosonic version of the Kondo effect can occur in degenerate atomic Fermi gases near the Feshbach resonance. We also discuss how this bosonic Kondo effect can be observed experimentally.Comment: 4 pages, 2 figures, some references added, some removed. More comments adde
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