41,940 research outputs found

    Surface-material maps of Viking landing sites on Mars

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    Researchers mapped the surface materials at the Viking landing sites on Mars to gain a better understanding of the materials and rock populations at the sites and to provide information for future exploration. The maps extent to about 9 m in front of each lander and are about 15 m wide - an area comparable to the area of a pixel in high resolution Viking Orbiter images. The maps are divided into the near and far fields. Data for the near fields are from 1/10 scale maps, umpublished maps, and lander images. Data for the far fields are from 1/20 scale contour maps, contoured lander camera mosaics, and lander images. Rocks are located on these maps using stereometric measurements and the contour maps. Frequency size distribution of rocks and the responses of soil-like materials to erosion by engine exhausts during landings are discussed

    Arrays of Josephson junctions in an environment with vanishing impedance

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    The Hamiltonian operator for an unbiased array of Josephson junctions with gate voltages is constructed when only Cooper pair tunnelling and charging effects are taken into account. The supercurrent through the system and the pumped current induced by changing the gate voltages periodically are discussed with an emphasis on the inaccuracies in the Cooper pair pumping. Renormalisation of the Hamiltonian operator is used in order to reliably parametrise the effects due to inhomogeneity in the array and non-ideal gating sequences. The relatively simple model yields an explicit, testable prediction based on three experimentally motivated and determinable parameters.Comment: 13 pages, 9 figures, uses RevTeX and epsfig, Revised version, Better readability and some new result

    The quantum metrology triangle and the re-definition of the SI ampere and kilogram; Analysis of a reduced set of observational equations

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    We have developed a set of seven observational equations that include all of the physics necessary to relate the most important of the fundamental constants to the definitions of the SI kilogram and ampere. We have used these to determine the influence of alternative definitions being considered for the SI kilogram and ampere on the uncertainty of three of the fundamental constants (h, e and mu). We have also reviewed the experimental evidence for the exactness of the quantum metrology triangle resulting from experiments combining the quantum Hall effect, the Josephson effects and single-electron tunnelling.Comment: 16 pages, 3 figures & 5 table

    Properties of nonaqueous electrolytes First quarterly report, 20 Jun. - 19 Sep. 1966

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    Solvent purification and water content determined by gas chromatography for nonaqueous electrolyte

    Properties of nonaqueous electrolytes Quarterly report, 20 Sep. - 19 Dec. 1966

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    Vapor phase chromatographic analysis of dimethyl formamide, and physical properties of electrolytes containing lithium chloride and/or aluminum chlorid

    A Non-Crossing Approximation for the Study of Intersite Correlations

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    We develop a Non-Crossing Approximation (NCA) for the effective cluster problem of the recently developed Dynamical Cluster Approximation (DCA). The DCA technique includes short-ranged correlations by mapping the lattice problem onto a self-consistently embedded periodic cluster of size NcN_c. It is a fully causal and systematic approximation to the full lattice problem, with corrections O(1/Nc){\cal{O}}(1/N_c) in two dimensions. The NCA we develop is a systematic approximation with corrections O(1/Nc3){\cal{O}}(1/N_c^3). The method will be discussed in detail and results for the one-particle properties of the Hubbard model are shown. Near half filling, the spectra display pronounced features including a pseudogap and non-Fermi-liquid behavior due to short-ranged antiferromagnetic correlations.Comment: 12 pages, 11 figures, EPJB styl

    Properties of nonaqueous electrolytes Quarterly report, 20 Dec. 1966 - 19 Mar. 1967

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    Properties of nonaqueous electrolytes - preparation of electrolytes, nuclear magnetic resonance structural studies, and physical property determination
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