13,094 research outputs found
Evaluation of commercial utility of ERTS-A imagery in structural reconnaissance for minerals and petroleum
Five areas in North America (North Slope-Alaska, Superior Province-Canada, Williston Basin-Montana, Colorado and New Mexico-West Texas) are being studied for discernibility of geological evidence on ERTS-1 imagery, Evidence mapped is compared with known mineral/hydrocarbon accumulations to determine the value of the imagery in commercial exploration programs. Evaluation has proceeded in the New Mexico-West Texas area while awaiting imagery in the other areas. To date, results have been better than expected. Clearly discernible structural lineaments in New Mexico-West Texas are evident on the photographs. Comparison of this evidence with known major mining localities in New Mexico indicates a clear pattern of coincidence between the lineaments and mining localities. In West Texas, lineament and geomorphological evidence obtainable from the photographs define the petroleum-productive Central Basin Platform. Based on evaluation results in the New Mexico-West Texas area and on cursory results in the other four areas of North America, ERTS-1 imagery will be extremely valuable in defining the regional and local structure in any commercial exploration program
ERTS-1 imagery use in reconnaissance prospecting: Evaluation of commercial utility of ERTS-1 imagery in structural reconnaissance for minerals and petroleum
The author has identified the following significant results. This study was performed to investigate applications of ERTS-1 imagery in commercial reconnaissance for mineral and hydrocarbon resources. ERTS-1 imagery collected over five areas in North America (Montana; Colorado; New Mexico-West Texas; Superior Province, Canada; and North Slope, Alaska) has been analyzed for data content including linears, lineaments, and curvilinear anomalies. Locations of these features were mapped and compared with known locations of mineral and hydrocarbon accumulations. Results were analyzed in the context of a simple-shear, block-coupling model. Data analyses have resulted in detection of new lineaments, some of which may be continental in extent, detection of many curvilinear patterns not generally seen on aerial photos, strong evidence of continental regmatic fracture patterns, and realization that geological features can be explained in terms of a simple-shear, block-coupling model. The conculsions are that ERTS-1 imagery is of great value in photogeologic/geomorphic interpretations of regional features, and the simple-shear, block-coupling model provides a means of relating data from ERTS imagery to structures that have controlled emplacement of ore deposits and hydrocarbon accumulations, thus providing a basis for a new approach for reconnaissance for mineral, uranium, gas, and oil deposits and structures
Bayes-X: a Bayesian inference tool for the analysis of X-ray observations of galaxy clusters
We present the first public release of our Bayesian inference tool, Bayes-X,
for the analysis of X-ray observations of galaxy clusters. We illustrate the
use of Bayes-X by analysing a set of four simulated clusters at z=0.2-0.9 as
they would be observed by a Chandra-like X-ray observatory. In both the
simulations and the analysis pipeline we assume that the dark matter density
follows a spherically-symmetric Navarro, Frenk and White (NFW) profile and that
the gas pressure is described by a generalised NFW (GNFW) profile. We then
perform four sets of analyses. By numerically exploring the joint probability
distribution of the cluster parameters given simulated Chandra-like data, we
show that the model and analysis technique can robustly return the simulated
cluster input quantities, constrain the cluster physical parameters and reveal
the degeneracies among the model parameters and cluster physical parameters. We
then analyse Chandra data on the nearby cluster, A262, and derive the cluster
physical profiles. To illustrate the performance of the Bayesian model
selection, we also carried out analyses assuming an Einasto profile for the
matter density and calculated the Bayes factor. The results of the model
selection analyses for the simulated data favour the NFW model as expected.
However, we find that the Einasto profile is preferred in the analysis of A262.
The Bayes-X software, which is implemented in Fortran 90, is available at
http://www.mrao.cam.ac.uk/facilities/software/bayesx/.Comment: 22 pages, 11 figure
Homogeneous variational problems: a minicourse
A Finsler geometry may be understood as a homogeneous variational problem,
where the Finsler function is the Lagrangian. The extremals in Finsler geometry
are curves, but in more general variational problems we might consider extremal
submanifolds of dimension . In this minicourse we discuss these problems
from a geometric point of view.Comment: This paper is a written-up version of the major part of a minicourse
given at the sixth Bilateral Workshop on Differential Geometry and its
Applications, held in Ostrava in May 201
An Empirically Based Calculation of the Extragalactic Infrared Background
Using the excellent observed correlations among various infrared wavebands
with 12 and 60 micron luminosities, we calculate the 2-300 micron spectra of
galaxies as a function of luminosity. We then use 12 micron and 60 micron
galaxy luminosity functions derived from IRAS data, together with recent data
on the redshift evolution of galaxy emissivity, to derive a new, empirically
based IR background spectrum from stellar and dust emission in galaxies. Our
best estimate for the IR background is of order 2-3 nW/m^2/sr with a peak
around 200 microns reaching 6-8 nW/m^2/sr. Our empirically derived background
spectrum is fairly flat in the mid-IR, as opposed to spectra based on modeling
with discrete temperatures which exhibit a "valley" in the mid-IR. We also
derive a conservative lower limit to the IR background which is more than a
factor of 2 lower than our derived flux.Comment: 14 pages AASTeX, 2 .ps figures, the Astrophysical Journal, in pres
ERTS-1 imagery use in reconnaissance prospecting: Evaluation of commercial utility of ERTS-1 imagery in structural reconnaissance for minerals and petroleum
The author has identified the following significant results. Five areas in North America (North Slope-Alaska, Superior Province-Canada, Williston Basin-Montana, Colorado, and New Mexico-West Texas) are being studied for discernibility of geological evidence on ERTS-1 imagery. Evidence mapped is compared with known mineral/hydrocarbon accumulations to determine the value of the imagery in commercial exploration programs. Evaluation has proceeded in the New Mexico-Texas area, and to date, results have been better than expected. Clearly discernible structural lineaments in this area are evident on the photographs. Comparison of this evidence with known major mining localities in New Mexico indicates a clear pattern of coincidence between the lineaments and mining localities. In West Texas, lineament and geomorphological evidence obtainable from the photographs define the petroleum-productive Central Basin Platform. Based on evaluation of results in the New Mexico-West Texas area and on cursory results in the other four areas of North America, it is concluded that ERTS-1 imagery will be extremely valuable in defining the regional and local structure in any commercial exploration program
Intergalactic Photon Spectra from the Far IR to the UV Lyman Limit for and the Optical Depth of the Universe to High Energy Gamma-Rays
We calculate the intergalactic photon density as a function of both energy
and redshift for 0 < z < 6 for photon energies from .003 eV to the Lyman limit
cutoff at 13.6 eV in a Lambda-CDM universe with and
. Our galaxy evolution model gives results which are
consistent with Spitzer deep number counts and the spectral energy distribution
of the extragalactic background radiation. We use our photon density results to
extend previous work on the absorption of high energy gamma-rays in
intergalactic space owing to interactions with low energy photons and the 2.7 K
cosmic background radiation. We calculate the optical depth of the universe,
tau, for gamma-rays having energies from 4 GeV to 100 TeV emitted by sources at
redshifts from ~0 to 5. We also give an analytic fit with numerical
coefficients for approximating . As an example of the
application of our results, we calculate the absorbed spectrum of the blazar
PKS 2155-304 at z = 0.117 and compare it with the spectrum observed by the
H.E.S.S. air Cherenkov gamma-ray telescope array.Comment: final version to be published in Ap
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