30,137 research outputs found
The Marysville, Montana Geothermal Project
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
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
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
We evaluate the observational constraints on the spectral index , in the
context of the CDM hypothesis which represents the simplest viable
cosmology. We first take to be practically scale-independent. Ignoring
reionization, we find at a nominal 2- level . If
we make the more realisitic assumption that reionization occurs when a fraction
to 1 of the matter has collapsed, the 2- lower bound is
unchanged while the 1- 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 , 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
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
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
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
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
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
- âŠ