8,278 research outputs found

    Geological and geothermal investigations for HCMM-derived data

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    An attempt was made to match HCMM- and U2HCMR-derived temperature data over two test sites of very local size to similar data collected in the field at nearly the same times. Results indicate that HCMM investigations using resolutions cells of 500 m or so are best conducted with areally-extensive sites, rather than point observations. The excellent quality day-VIS imagery is particularly useful for lineament studies, as is the DELTA-T imagery. Attempts to register the ground observed temperatures (even for 0.5 sq mile targets) were unsuccessful due to excessive pixel-to-pixel noise on the HCMM data. Several computer models were explored and related to thermal parameter value changes with observed data. Unless quite complex models, with many parameters which can be observed (perhaps not even measured (perhaps not even measured) only under remote sensing conditions (e.g., roughness, wind shear, etc) are used, the model outputs do not match the observed data. Empirical relationship may be most readily studied

    Further Experiments on Creep-Rupture Life Under Cyclic Environmental Conditions

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    An increase in beam size from 10 by 20 mm to 2 by 2 inches increased the mean time to failure at a load level of 70% of modulus of rupture of specimens subjected to moisture content cycling by more than one order of magnitude. The effect of temperature cycling appears to depend on moisture content. The results indicate that the present load duration factor for wood is adequate under normal conditions, but that adjustments are needed when loaded members are small or when there are severe cyclic changes in ambient conditions

    Prediction of Creep in Plywood Part I. Prediction Models for Creep in Plywood

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    Three models for predicting creep in plywood from measured constituent properties were formulated using phenomenological linear viscoelastic theory. The three models represent a one-dimensional, quasi-elastic solution, a two-dimensional, quasi-elastic solution, and a two-dimensional, viscoelastic solution. In part II of this study, the models will be used to compute the principal components of the two-dimensional creep compliance tensor for plywood and will show that predictions of creep behavior based on all three solutions give similar results. The most accurate prediction of parallel and perpendicular creep was made with the one-dimensional model

    Oxygen isotopes implanted in the LDEF spacecraft

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    Secondary ion mass spectrometry was used to study oxygen implanted in the surface of copper from the Long Duration Exposure Facility (LDEF). Oxidation that occurred in orbit shows a characteristic oxygen isotope composition, depleted in O-18. The measured depletion is comparable to the predicted depletion (45 percent) based on a model of the gravitational separation of the oxygen isotopes. The anomalous oxygen was contained within 10nm of the surface. Tray E10 was calculated to have received 5.14 x 10(exp 21) atoms of oxygen cm(sup -2) during the LDEF mission and so there is sufficient anomalous implanted oxygen present in the surface to obtain a reliable isotopic profile

    Geological and geothermal data use investigations for application Explorer mission-A (heat capacity mapping mission)

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    There are no author-identified significant results in this report

    Geological and geothermal data use investigations for application explorer mission-A, heat capacity mapping mission

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    There are no author-identified significant results in this report

    Clean catalytic combustor program

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    A combustor program was conducted to evolve and to identify the technology needed for, and to establish the credibility of, using combustors with catalytic reactors in modern high-pressure-ratio aircraft turbine engines. Two selected catalytic combustor concepts were designed, fabricated, and evaluated. The combustors were sized for use in the NASA/General Electric Energy Efficient Engine (E3). One of the combustor designs was a basic parallel-staged double-annular combustor. The second design was also a parallel-staged combustor but employed reverse flow cannular catalytic reactors. Subcomponent tests of fuel injection systems and of catalytic reactors for use in the combustion system were also conducted. Very low-level pollutant emissions and excellent combustor performance were achieved. However, it was obvious from these tests that extensive development of fuel/air preparation systems and considerable advancement in the steady-state operating temperature capability of catalytic reactor materials will be required prior to the consideration of catalytic combustion systems for use in high-pressure-ratio aircraft turbine engines

    A platinum chloro (fluoroaryl)phosphine complex

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    trans-Dichloro bis[ tris(peritafluorophenyl)phosphine ]platinum(II), [PtCl_2{P(C_6F_5)_3}_2], M_r = 1330.29, triclinic, Pl, ɑ = 9.536 (4), b = 11.221 (2), c = 11.613 (1)Å, ɑ = 62.55 (1), β = 65.81 (2), y = 73.05 (2)º, V = 997.8 (4) Å^3, Z = 1, D_x = 2.21 g cm^(-3), λ(Mo Kɑ)= 0.71073 A, μ = 39.27 cm^(-1), F(000) = 628, room temperature, R = 0.034 for 3497 reflections with F_o^2 > 0. The molecule is centrosymmetric, with Pt-Cl distance 2.304 (2) and Pt-P 2.280 (1) Å, and P-Pt-Cl angle 94.8 (1)°. The C-P distances average 1.824 (4)Å, slightly longer than normal, and the pentafluoro-phenyl groups all have small [116.3 (3)º] angles at the c atom bonded to P

    High fidelity quantum memory via dynamical decoupling: theory and experiment

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    Quantum information processing requires overcoming decoherence---the loss of "quantumness" due to the inevitable interaction between the quantum system and its environment. One approach towards a solution is quantum dynamical decoupling---a method employing strong and frequent pulses applied to the qubits. Here we report on the first experimental test of the concatenated dynamical decoupling (CDD) scheme, which invokes recursively constructed pulse sequences. Using nuclear magnetic resonance, we demonstrate a near order of magnitude improvement in the decay time of stored quantum states. In conjunction with recent results on high fidelity quantum gates using CDD, our results suggest that quantum dynamical decoupling should be used as a first layer of defense against decoherence in quantum information processing implementations, and can be a stand-alone solution in the right parameter regime.Comment: 6 pages, 3 figures. Published version. This paper was initially entitled "Quantum gates via concatenated dynamical decoupling: theory and experiment", by Jacob R. West, Daniel A. Lidar, Bryan H. Fong, Mark F. Gyure, Xinhua Peng, and Dieter Suter. That original version split into two papers: http://arxiv.org/abs/1012.3433 (theory only) and the current pape

    Structure of trimethylplatinum(IV) with a tripod ligand

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    [1(η^5)-Cyclopentadienyl]-tris-µ-(dimethyl-phosphito-1κP:2κO)(trimethyl-2κ^3C)cobaltplatinum, [CoPt(C_2H_6O_3P)_3(C_5H_5)(CH_3)_3], M_r = 691.35, triclinic, P1, a = 9.106(3), b = 14.803(3), c = 15.147(3) Å, α = 112.95(2), β = 103.68(2), γ = 95.10(2)°, V = 1788.9(9) Å^3, Z = 3, D_x = 1.93 g cm^(-3), λ(Mo Kα) = 0.71073 Å, µ = 68.69 cm^(-1), F(000) = 1014, room temperature, R = 0.038 for 4620 reflections with F_o^2 > 3σ(F_o^2). The trimethylplatinum(IV) completes octahedral coordination by bonding to three O atoms of the tripod-shaped methoxy Kläui ligand. There are two independent molecules in the cell, one disordered about a center of symmetry. The ordered molecule has normal bond distances and angles; Pt-C = 2.001 (11) and Pt-O = 2.173(5) Å. Many distances in the disordered molecule are uncertain, particularly in the areas of the Cp C atoms and the CH_3 groups, which overlap in the two orientations
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