30,137 research outputs found

    The Marysville, Montana Geothermal Project

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    Drilling the first geothermal well in Montana presented many challenges, not only in securing materials and planning strategies for drilling the wildcat well but also in addressing the environmental, legal, and institutional issues raised by the request for permission to explore a resource which lacked legal definition. The Marysville Geothermal Project was to investigate a dry hot rock heat anomaly. The well was drilled to a total depth of 6790 feet and many fractured water bearing zones were encountered below 1800 feet

    Running-mass models of inflation, and their observational constraints

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    If the inflaton sector is described by softly broken supersymmetry, and the inflaton has unsuppressed couplings, the inflaton mass will run strongly with scale. Four types of model are possible. The prediction for the spectral index involves two parameters, while the COBE normalization involves a third, all of them calculable functions of the relevant masses and couplings. A crude estimate is made of the region of parameter space allowed by present observation.Comment: Latex file, 20 pages, 11 figures, uses epsf.sty. Comment on the observation of the spectral index scale dependence added; Fig. 3-6 improve

    Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy Conversion subsystems and components. Part 2: Primary heat input systems and heat exchangers

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    Primary heat input systems and heat exchangers were evaluated for advanced energy conversion systems. Results are presented and discussed

    Observational constraints on the spectral index of the cosmological curvature perturbation

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    We evaluate the observational constraints on the spectral index nn, in the context of the Λ\LambdaCDM hypothesis which represents the simplest viable cosmology. We first take nn to be practically scale-independent. Ignoring reionization, we find at a nominal 2-σ\sigma level n≃1.0±0.1n\simeq 1.0 \pm 0.1. If we make the more realisitic assumption that reionization occurs when a fraction f∌10−5f\sim 10^{-5} to 1 of the matter has collapsed, the 2-σ\sigma lower bound is unchanged while the 1-σ\sigma bound rises slightly. These constraints are compared with the prediction of various inflation models. Then we investigate the two-parameter scale-dependent spectral index, predicted by running-mass inflation models, and find that present data allow significant scale-dependence of nn, which occurs in a physically reasonable regime of parameter space.Comment: ReVTeX, 15 pages, 5 figures and 3 tables, uses epsf.sty Improved treatment of reionization and small bug fixed in the constant n case; more convenient parameterization and better treatment of the n dependence in the CMB anisotropy for the running mass case; conclusions basically unchanged; references adde

    Specific Heat of Ce(1-x)La(x)RhIn(5) in Zero and Applied Magnetic Field: A Very Rich Phase Diagram

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    Specific heat and magnetization results as a function of field on single- and poly-crystalline samples of Ce(1-x)La(x)RhIn(5) show 1.) a specific heat gamma of about 100 mJ/moleK^2 (in agreement with recent dHvA results of Alvers et al.); 2.) upturns at low temperatures in C/T and chi that fit a power law behavior ( Griffiths phase non-Fermi liquid behavior); 3.) a field induced anomaly in C/T as well as M vs H behavior in good agreement with the recent Griffiths phase theory of Castro Neto and Jones, where M~H at low field, M ~ H^lambda above a crossover field, C/T ~ T^(-1+lambda) at low field, and C/T ~ (H^(2+lambda/2)/T^(3-lambda/2))*exp(-mu(eff)H/T) above the same crossover field as determined in the magnetization and where lambda is independently determined from the temperature dependence of chi at low temperatures, chi ~ T^(-1+lambda) and low fields.Comment: 13 pages, 9 figures, to be published in Physical Review

    Some Aspects of Liquefaction Assessment of Duncan Dam

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    A comprehensive program of field, laboratory and analytical investigations was carried out to assess the potential for liquefaction of the foundation soils and seismic stability of Duncan Dam. Duncan Oam is located on Duncan River in southeastern British Columbia, Canada. The 39 m high zoned earthfill dam is founded on a thick sequence of sands, silts and gravels. The liquefaction studies were carried out in two phases between 1988 and 1992 to characterize in detail the engineering properties of the foundation soils; and to assess its potential for triggering liquefaction, and the post liquefaction stability and deformation of the dam using parameters based on two approaches; one a site specific laboratory based direct method (Lab.method) and the other an indirect method (Seed\u27s method) which is based on field penetration data and field experience during past earthquakes. This paper describes some advanced aspects of the field and laboratory investigations including laboratory testing of undisturbed soil samples obtained after freezing the ground insitu. The influence of confining stress (K0) and initial static shear stress (K0) on liquefaction were investigated and site specific correlations for K0 and K. are presented. The laboratory investigations indicate that the residual strengths of the liquefied sand is a function of initial consolidation stress

    In-orbit Vignetting Calibrations of XMM-Newton Telescopes

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    We describe measurements of the mirror vignetting in the XMM-Newton Observatory made in-orbit, using observations of SNR G21.5-09 and SNR 3C58 with the EPIC imaging cameras. The instrument features that complicate these measurements are briefly described. We show the spatial and energy dependences of measured vignetting, outlining assumptions made in deriving the eventual agreement between simulation and measurement. Alternate methods to confirm these are described, including an assessment of source elongation with off-axis angle, the surface brightness distribution of the diffuse X-ray background, and the consistency of Coma cluster emission at different position angles. A synthesis of these measurements leads to a change in the XMM calibration data base, for the optical axis of two of the three telescopes, by in excess of 1 arcminute. This has a small but measureable effect on the assumed spectral responses of the cameras for on-axis targets.Comment: Accepted by Experimental Astronomy. 26 pages, 18 figure

    Gowdy waves as a test-bed for constraint-preserving boundary conditions

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    Gowdy waves, one of the standard 'apples with apples' tests, is proposed as a test-bed for constraint-preserving boundary conditions in the non-linear regime. As an illustration, energy-constraint preservation is separately tested in the Z4 framework. Both algebraic conditions, derived from energy estimates, and derivative conditions, deduced from the constraint-propagation system, are considered. The numerical errors at the boundary are of the same order than those at the interior points.Comment: 5 pages, 1 figure. Contribution to the Spanish Relativity Meeting 200

    Pressure-induced superconductivity in the giant Rashba system BiTeI

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    At ambient pressure, BiTeI is the first material found to exhibit a giant Rashba splitting of the bulk electronic bands. At low pressures, BiTeI undergoes a transition from trivial insulator to topological insulator. At still higher pressures, two structural transitions are known to occur. We have carried out a series of electrical resistivity and AC magnetic susceptibility measurements on BiTeI at pressure up to ~40 GPa in an effort to characterize the properties of the high-pressure phases. A previous calculation found that the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that this structure is superconducting with Tc values as high as 6 K. AC magnetic susceptibility measurements support the bulk nature of the superconductivity. Using electronic structure and phonon calculations, we compute Tc and find that our data is consistent with phonon-mediated superconductivity.Comment: 7 pages, 7 figure
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