227,031 research outputs found

    Summary results of the DOE flywheel development effort

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    The technology and applications evaluation task focuses on defining performance and cost requirements for flywheels in the various areas of application. To date the DOE program has focused on automotive applications. The composite materials effort entails the testing of new commercial composites to determine their engineering properties. The rotor and containment development work uses data from these program elements to design and fabricate flywheels. The flywheels are then tested at the Oak Ridge Flywheel Evaluation Laboratory and their performance is evaluated to indicate possible areas for improvement. Once a rotor has been fully developed it is transferred to the private sector

    The baryon-decuplet in the chiral dynamics of Lambda-hyperons in nuclear matter

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    We study the long range part of the Λ\Lambda-hyperon optical potential in nuclei using Quantum Many Body techniques and flavor-SU(3) Chiral Lagrangians as starting point. More precisely, we study the contributions to the Λ\Lambda-hyperon optical potential due to the long-range two-pion exchange, with Σ\Sigma and Σ∗\Sigma^* baryons in the internal baryonic lines and considering Nh and Δ\Deltah excitations. We also consider the contribution to the spin-orbit potentials that comes out from these terms. Our results support a natural explanation of the smallness of the Λ\Lambda-nuclear spin-orbit interaction and shows the importance of the Σ∗\Sigma^* and Δ\Delta degrees of freedom for the hyperon-nucleus interactions.Comment: 8 pages, 5 figure

    Helical Magnetic Fields from Inflation

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    We analyze the generation of seed magnetic fields during de Sitter inflation considering a non-invariant conformal term in the electromagnetic Lagrangian of the form −14I(ϕ)FμνF~μν-\frac14 I(\phi) F_{\mu \nu} \widetilde{F}^{\mu \nu}, where I(ϕ)I(\phi) is a pseudoscalar function of a non-trivial background field ϕ\phi. In particular, we consider a toy model, that could be realized owing to the coupling between the photon and either a (tachyonic) massive pseudoscalar field and a massless pseudoscalar field non-minimally coupled to gravity, where II follows a simple power-law behavior I(k,η)=g/(−kη)βI(k,\eta) = g/(-k\eta)^{\beta} during inflation, while it is negligibly small subsequently. Here, gg is a positive dimensionless constant, kk the wavenumber, η\eta the conformal time, and β\beta a real positive number. We find that only when β=1\beta = 1 and 0.1≲g≲20.1 \lesssim g \lesssim 2 astrophysically interesting fields can be produced as excitation of the vacuum, and that they are maximally helical.Comment: 17 pages, 1 figure, subsection IIc and references added; accepted for publication in IJMP

    Fully ab initio atomization energy of benzene via W2 theory

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    The total atomization energy at absolute zero, (TAE0_0) of benzene, C6_6H6_6, was computed fully {\em ab initio} by means of W2h theory as 1306.6 kcal/mol, to be compared with the experimentally derived value 1305.7+/-0.7 kcal/mol. The computed result includes contributions from inner-shell correlation (7.1 kcal/mol), scalar relativistic effects (-1.0 kcal/mol), atomic spin-orbit splitting (-0.5 kcal/mol), and the anharmonic zero-point vibrational energy (62.1 kcal/mol). The largest-scale calculations involved are CCSD/cc-pV5Z and CCSD(T)/cc-pVQZ; basis set extrapolations account for 6.3 kcal/mol of the final result. Performance of more approximate methods has been analyzed. Our results suggest that, even for systems the size of benzene, chemically accurate molecular atomization energies can be obtained from fully first-principles calculations, without resorting to corrections or parameters derived from experiment.Comment: J. Chem. Phys., accepted. RevTeX, 12 page
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