42,284 research outputs found

    View factor computer program (VIEW)

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    Existing view factor program, RAVFAC, was modified to accept NASTRAN and/or RAVFAC surface descriptions. Output formatting was altered to produce view factor matrices which could be directly input to NASTRAN

    Gauge dependence of calculations in relativistic Coulomb excitation

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    Before a quantum-mechanical calculation involving electromagnetic interactions is performed, a choice must be made of the gauge to be used in expressing the potentials. If the calculation is done exactly, the observable results it predicts will be independent of the choice of gauge. However, in most practical calculations approximations are made, which can destroy the gauge invariance of the predictions. We compare here the results of coupled-channel time-dependent relativistic Coulomb excitation calculations, as performed in either Lorentz or Coulomb gauges. We find significant differences when the bombarding energy per nucleon is ≥\geq 2 GeV, which indicates that the common practice of relying completely on the Lorentz gauge can be dangerous.Comment: 23 pages, 3 figure

    Rutherford scattering with radiation damping

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    We study the effect of radiation damping on the classical scattering of charged particles. Using a perturbation method based on the Runge-Lenz vector, we calculate radiative corrections to the Rutherford cross section, and the corresponding energy and angular momentum losses.Comment: Latex, 11 pages, 4 eps figure

    Imaging X-ray spectrometer

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    An X-ray spectrometer for providing imaging and energy resolution of an X-ray source is described. This spectrometer is comprised of a thick silicon wafer having an embedded matrix or grid of aluminum completely through the wafer fabricated, for example, by thermal migration. The aluminum matrix defines the walls of a rectangular array of silicon X-ray detector cells or pixels. A thermally diffused aluminum electrode is also formed centrally through each of the silicon cells with biasing means being connected to the aluminum cell walls and causes lateral charge carrier depletion between the cell walls so that incident X-ray energy causes a photoelectric reaction within the silicon producing collectible charge carriers in the form of electrons which are collected and used for imaging

    Coulomb Excitation of Multi-Phonon Levels of the Giant Dipole Resonance

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    A closed expression is obtained for the cross-section for Coulomb excitation of levels of the giant dipole resonance of given angular momentum and phonon number. Applications are made to the Goldhaber-Teller and Steinwedel-Jensen descriptions of the resonance, at non-relativistic and relativistic bombarding energies.Comment: 16 pages, 5 figure

    Optical alignment system Patent

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    Electro-optical/computer system for aligning large structural members and maintaining correct positio

    Arkansas Cotton Variety Test 2003

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    The primary aim of the Arkansas Cotton Variety Test is to provide unbiased data regarding the agronomic performance of cotton varieties and advanced breeding lines in the major cotton-growing areas of Arkansas. This information helps seed dealers establish marketing strategies and assists producers in choosing varieties to plant. In this way, the annual test facilitates the inclusion of new, improved genetic material in Arkansas cotton production

    Cooperativity and Stability in a Langevin Model of Protein Folding

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    We present two simplified models of protein dynamics based on Langevin's equation of motion in a viscous medium. We explore the effect of the potential energy function's symmetry on the kinetics and thermodynamics of simulated folding. We find that an isotropic potential energy function produces, at best, a modest degree of cooperativity. In contrast, a suitable anisotropic potential energy function delivers strong cooperativity.Comment: 45 pages, 16 figures, 2 tables. LaTeX. Submitted to the Journal of Chemical Physic

    Many-body effects on the capacitance of multilayers made from strongly correlated materials

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    Recent work by Kopp and Mannhart on novel electronic systems formed at oxide interfaces has shown interesting effects on the capacitances of these devices. We employ inhomogeneous dynamical mean-field theory to calculate the capacitance of multilayered nanostructures. These multilayered nanostructures are composed of semi-infinite metallic leads coupled via a strongly correlated dielectric barrier region. The barrier region can be adjusted from a metallic regime to a Mott insulator through adjusting the interaction strength. We examine the effects of varying the barrier width, temperature, potential difference, screening length, and chemical potential. We find that the interaction strength has a relatively strong effect on the capacitance, while the potential and temperature show weaker dependence.Comment: 19 pages, 7 figures, REVTe

    On a q-analogue of the multiple gamma functions

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    A qq-analogue of the multiple gamma functions is introduced, and is shown to satisfy the generalized Bohr-Morellup theorem. Furthermore we give some expressions of these function.Comment: 8 pages, AMS-Late
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