55,948 research outputs found

    Vacuum deposition apparatus Patent

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    Describing apparatus used in vacuum deposition of thin film inductive windings for spacecraft microcircuitr

    Evaporant source for vapor deposition Patent

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    Spatter proof evaporant source design for use in vacuum deposition of solid thin films on substrate

    Accelerated Overlap Fermions

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    Numerical evaluation of the overlap Dirac operator is difficult since it contains the sign function ϵ(Hw)\epsilon(H_w) of the Hermitian Wilson-Dirac operator HwH_w with a negative mass term. The problems are due to HwH_w having very small eigenvalues on the equilibrium background configurations generated in current day Monte Carlo simulations. Since these are a consequence of the lattice discretisation and do not occur in the continuum version of the operator, we investigate in this paper to what extent the numerical evaluation of the overlap can be accelerated by making the Wilson-Dirac operator more continuum-like. Specifically, we study the effect of including the clover term in the Wilson-Dirac operator and smearing the link variables in the irrelevant terms. In doing so, we have obtained a factor of two speedup by moving from the Wilson action to a FLIC (Fat Link Irrelevant Clover) action as the overlap kernel.Comment: 15 pages, 6 figures; V2 contains major revision of the introduction and motivation sections. Conclusion and results unchanged v2.1: formatting chang

    Possible Suppression of Resonant Signals for Split-UED by Mixing at the LHC?

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    The mixing of the imaginary parts of the transition amplitudes of nearby resonances via the breakdown of the Breit-Wigner approximation has been shown to lead to potentially large modifications in the signal rates for new physics at colliders. In the case of suppression, this effect may be significant enough to lead to some new physics signatures being initially missed in searches at, e.g., the LHC. Here we explore the influence of this `width mixing' on the production of the nearly degenerate, level-2 Kaluza-Klein (KK) neutral gauge bosons present in Split-UED. We demonstrate that in this particular case large cross section modifications in the resonance region are necessarily absent and explain why this is so based on the group theoretical structure of the SM.Comment: 10 pages, 2 figures; discussion and references adde

    Strong electron correlations in cobalt valence tautomers

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    We have examined cobalt based valence tautomer molecules such as Co(SQ)2_2(phen) using density functional theory (DFT) and variational configuration interaction (VCI) approaches based upon a model Hamiltonian. Our DFT results extend earlier work by finding a reduced total energy gap (order 0.6 eV) between high temperature and low temperature states when we fully relax the coordinates (relative to experimental ones). Futhermore we demonstrate that the charge transfer picture based upon formal valence arguments succeeds qualitatively while failing quantitatively due to strong covalency between the Co 3dd orbitals and ligand pp orbitals. With the VCI approach, we argue that the high temperature, high spin phase is strongly mixed valent, with about 30 % admixture of Co(III) into the predominantly Co(II) ground state. We confirm this mixed valence through a fit to the XANES spectra. Moreover, the strong electron correlations of the mixed valent phase provide an energy lowering of about 0.2-0.3 eV of the high temperature phase relative to the low temperature one. Finally, we use the domain model to account for the extraordinarily large entropy and enthalpy values associated with the transition.Comment: 10 pages, 4 figures, submitted to J. Chem. Phy

    Evidence for parallel elongated structures in the mesosphere

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    The physical cause of partial reflection from the mesosphere is of interest. Data are presented from an image-forming radar at Brighton, Colorado, that suggest that some of the radar scattering is caused by parallel elongated structures lying almost directly overhead. Possible physical sources for such structures include gravity waves and roll vortices

    Parameters for Twisted Representations

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    The study of Hermitian forms on a real reductive group GG gives rise, in the unequal rank case, to a new class of Kazhdan-Lusztig-Vogan polynomials. These are associated with an outer automorphism δ\delta of GG, and are related to representations of the extended group . These polynomials were defined geometrically by Lusztig and Vogan in "Quasisplit Hecke Algebras and Symmetric Spaces", Duke Math. J. 163 (2014), 983--1034. In order to use their results to compute the polynomials, one needs to describe explicitly the extension of representations to the extended group. This paper analyzes these extensions, and thereby gives a complete algorithm for computing the polynomials. This algorithm is being implemented in the Atlas of Lie Groups and Representations software

    Finite element for rotor/stator interactive forces in general engine dynamic simulation. Part 1: Development of bearing damper element

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    A general purpose squeeze-film damper interactive force element was developed, coded into a software package (module) and debugged. This software package was applied to nonliner dynamic analyses of some simple rotor systems. Results for pressure distributions show that the long bearing (end sealed) is a stronger bearing as compared to the short bearing as expected. Results of the nonlinear dynamic analysis, using a four degree of freedom simulation model, showed that the orbit of the rotating shaft increases nonlinearity to fill the bearing clearance as the unbalanced weight increases

    Experimental data on the single spin asymmetry and their interpretations by the chromo-magnetic string model

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    An attempt is made to interpret the various existing experimental data on the single spin asymmetries in inclusive pion production by the polarized proton and antiproton beams. As the basis of analysis the chromo-magnetic string model is used. A whole measured kinematic region is covered. The successes and fails of such approach are outlined. The possible improvements of model are discussed.Comment: 17 pages, 3 figure

    The load-carrying and thermal characteristics of flat conductor cable

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    The load-carrying and thermal characteristics of flat conductor cable and round wire cables have been investigated with all conductors in each cable under varying loads in air and vacuum environments. The test procedure is described and results are presented in graphic form. Derating factors for both round wire and flat conductor cable are established for operation in a vacuum environment. Rating factors are established for flat conductor cable for use with round wire loading tables. The results of these tests show that single layer flat conductor size, or that the voltage drop across flat conductor cable will be lower than that of round cable under the same load
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