1,765 research outputs found
The technology utilization process - An overview
Technology utilization process, and NASA programs for transferring technology and disseminating information on product developmen
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Assessing impacts to groundwater from CO2-flooding of SACROC and Claytonville oil fields in West Texas
Comparison of groundwater above two Permian Basin oil fields (SACROC Unit and
Claytonville Field) near Snyder, Texas should allow us to assess potential impacts of 30 years of
CO2-injection. CO2-flooding for enhanced oil recovery (EOR) has been active at SACROC in
Scurry County since 1972. Approximately 13.5 million tons per year (MtCO2/yr) are injected
with withdrawal/recycling amounting to ~7MtCO2/yr. It is estimated that the site has accumulated
more than 55MtCO2; however, no rigorous investigation of overlying groundwater has
demonstrated that CO2 is trapped in the subsurface. Mineralogy of reservoir rocks at the
Claytonville field in southwestern Fisher County is similar to SACROC. CO2-EOR is scheduled
to begin at Claytonville Field in Fisher County in early 2007. Here we have the opportunity to
characterize groundwater prior to CO2-injection and establish baseline conditions at Claytonville.
Methods of this study will include: (1) examination of existing analyses of saline to fresh
water samples collected within an eight-county area encompassing SACROC and Claytonville,
(2) additional groundwater sampling for analysis of general chemistry plus field-measured pH,
alkalinity, and temperature, stable isotopic ratios of hydrogen (D/H), oxygen (18O/16O), and
carbon (13C/12C), and (3) geochemical equilibrium and flowpath modeling. Existing groundwater
data are available from previous BEG studies, Texas Water Development Board, Kinder Morgan
CO2 Company, and the U. S. Geological Survey. By examining these data we will identify
regional groundwater variability and focus additional sampling efforts. The objective of this study
is to look for potential impacts to shallow groundwater from deep CO2-injection. In the absence
of conduit flow from depth, we don’t expect to see impacts to shallow groundwater, but
methodology to demonstrate this to regulators needs to be established.
This work is a subset of the Southwest Regional Partnership on Carbon Sequestration
Phase 2studies funded by the Department of Energy (DOE) in cooperation with industry and
government partners.Bureau of Economic Geolog
Global Existence and Regularity for the 3D Stochastic Primitive Equations of the Ocean and Atmosphere with Multiplicative White Noise
The Primitive Equations are a basic model in the study of large scale Oceanic
and Atmospheric dynamics. These systems form the analytical core of the most
advanced General Circulation Models. For this reason and due to their
challenging nonlinear and anisotropic structure the Primitive Equations have
recently received considerable attention from the mathematical community.
In view of the complex multi-scale nature of the earth's climate system, many
uncertainties appear that should be accounted for in the basic dynamical models
of atmospheric and oceanic processes. In the climate community stochastic
methods have come into extensive use in this connection. For this reason there
has appeared a need to further develop the foundations of nonlinear stochastic
partial differential equations in connection with the Primitive Equations and
more generally.
In this work we study a stochastic version of the Primitive Equations. We
establish the global existence of strong, pathwise solutions for these
equations in dimension 3 for the case of a nonlinear multiplicative noise. The
proof makes use of anisotropic estimates, estimates on the
pressure and stopping time arguments.Comment: To appear in Nonlinearit
On Unique Ergodicity in Nonlinear Stochastic Partial Differential Equations
© 2016 Springer Science+Business Media New YorkWe illustrate how the notion of asymptotic coupling provides a flexible and intuitive framework for proving the uniqueness of invariant measures for a variety of stochastic partial differential equations whose deterministic counterpart possesses a finite number of determining modes. Examples exhibiting parabolic and hyperbolic structure are studied in detail. In the later situation we also present a simple framework for establishing the existence of invariant measures when the usual approach relying on the Krylov–Bogolyubov procedure and compactness fails
Spatial analysis and mapping of malaria risk in Malawi using point-referenced prevalence of infection data
BACKGROUND: Current malaria control initiatives aim at reducing malaria burden by half by the year 2010. Effective control requires evidence-based utilisation of resources. Characterizing spatial patterns of risk, through maps, is an important tool to guide control programmes. To this end an analysis was carried out to predict and map malaria risk in Malawi using empirical data with the aim of identifying areas where greatest effort should be focussed. METHODS: Point-referenced prevalence of infection data for children aged 1–10 years were collected from published and grey literature and geo-referenced. The model-based geostatistical methods were applied to analyze and predict malaria risk in areas where data were not observed. Topographical and climatic covariates were added in the model for risk assessment and improved prediction. A Bayesian approach was used for model fitting and prediction. RESULTS: Bivariate models showed a significant association of malaria risk with elevation, annual maximum temperature, rainfall and potential evapotranspiration (PET). However in the prediction model, the spatial distribution of malaria risk was associated with elevation, and marginally with maximum temperature and PET. The resulting map broadly agreed with expert opinion about the variation of risk in the country, and further showed marked variation even at local level. High risk areas were in the low-lying lake shore regions, while low risk was along the highlands in the country. CONCLUSION: The map provided an initial description of the geographic variation of malaria risk in Malawi, and might help in the choice and design of interventions, which is crucial for reducing the burden of malaria in Malawi
Enhancement of the Binding Energy of Charged Excitons in Disordered Quantum Wires
Negatively and positively charged excitons are identified in the
spatially-resolved photoluminescence spectra of quantum wires. We demonstrate
that charged excitons are weakly localized in disordered quantum wires. As a
consequence, the enhancement of the "binding energy" of a charged exciton is
caused, for a significant part, by the recoil energy transferred to the
remaining charged carrier during its radiative recombination. We discover that
the Coulomb correlation energy is not the sole origin of the "binding energy",
in contrast to charged excitons confined in quantum dots.Comment: 4 Fig
Structured matrices, continued fractions, and root localization of polynomials
We give a detailed account of various connections between several classes of
objects: Hankel, Hurwitz, Toeplitz, Vandermonde and other structured matrices,
Stietjes and Jacobi-type continued fractions, Cauchy indices, moment problems,
total positivity, and root localization of univariate polynomials. Along with a
survey of many classical facts, we provide a number of new results.Comment: 79 pages; new material added to the Introductio
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