Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data (open access)

Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data

We present a three-dimensional modeling study of gas flow inthe unsaturated fractured rock of Yucca Mountain. Our objective is toestimate large-scale fracture permeability, using the changes insubsurface pneumatic pressure in response to barometric pressure changesat the land surface. We incorporate the field-measured pneumatic datainto a multiphase flow model for describing the coupled processes ofliquid and gas flow under ambient geothermal conditions. Comparison offield-measured pneumatic data with model-predicted gas pressures is foundto be a powerful technique for estimating the fracture permeability ofthe unsaturated fractured rock, which is otherwise extremely difficult todetermine on the large scales of interest. In addition, this studydemonstrates that the multi-dimensional-flow effect on estimatedpermeability values is significant and should be included whendetermining fracture permeability in heterogeneous fracturedmedia.
Date: May 17, 2005
Creator: Wu, Yu-Shu; Zhang, Keni & Liu, Hui-Hai
Object Type: Article
System: The UNT Digital Library
Numerical Modeling Studies of The Dissolution-Diffusion-Convection ProcessDuring CO2 Storage in Saline Aquifers (open access)

Numerical Modeling Studies of The Dissolution-Diffusion-Convection ProcessDuring CO2 Storage in Saline Aquifers

For purposes of geologic storage, CO2 would be injected into saline formations at supercritical temperature and pressure conditions, and would form a separate phase that is immiscible with the aqueous phase (brine). At typical subsurface temperature and pressure conditions, supercritical CO2 (scCO2) has lower density than the aqueous phase and would experience an upward buoyancy force. Accordingly, the CO2 is expected to accumulate beneath the caprock at the top of the permeable interval, and could escape from the storage formation wherever (sub-)vertical pathways are available, such as fractures or faults through the caprock, or improperly abandoned wells. Over time, an increasing fraction of CO2 may dissolve in the aqueous phase, and eventually some of the aqueous CO2 may react with rock minerals to form poorly soluble carbonates. Dissolution into the aqueous phase and eventual sequestration as carbonates are highly desirable processes as they would increase permanence and security of storage. Dissolution of CO2 will establish phase equilibrium locally between the overlying CO2 plume and the aqueous phase beneath. If the aqueous phase were immobile, CO2 dissolution would be limited by the rate at which molecular diffusion can remove dissolved CO2 from the interface between CO2-rich and aqueous phases. This is …
Date: November 17, 2008
Creator: Pruess, Karsten & Zhang, Keni
Object Type: Report
System: The UNT Digital Library
SOFTWARE QUALITY ASSURANCE FOR EMERGENCY RESPONSE CONSEQUENCE ASSESSMENT MODELS AT DOE'S SAVANNAH RIVER SITE (open access)

SOFTWARE QUALITY ASSURANCE FOR EMERGENCY RESPONSE CONSEQUENCE ASSESSMENT MODELS AT DOE'S SAVANNAH RIVER SITE

The Savannah River National Laboratory's (SRNL) Atmospheric Technologies Group develops, maintains, and operates computer-based software applications for use in emergency response consequence assessment at DOE's Savannah River Site. These applications range from straightforward, stand-alone Gaussian dispersion models run with simple meteorological input to complex computational software systems with supporting scripts that simulate highly dynamic atmospheric processes. A software quality assurance program has been developed to ensure appropriate lifecycle management of these software applications. This program was designed to meet fully the overall structure and intent of SRNL's institutional software QA programs, yet remain sufficiently practical to achieve the necessary level of control in a cost-effective manner. A general overview of this program is described.
Date: December 17, 2007
Creator: Hunter, C
Object Type: Article
System: The UNT Digital Library
Counting constituents in molecular complexes by fluorescence photon antibunching (open access)

Counting constituents in molecular complexes by fluorescence photon antibunching

Modern single molecule fluorescence microscopy offers new, highly quantitative ways of studying the systems biology of cells while keeping the cells healthy and alive in their natural environment. In this context, a quantum optical technique, photon antibunching, has found a small niche in the continuously growing applications of single molecule techniques to small molecular complexes. Here, we review some of the most recent applications of photon antibunching in biophotonics, and we provide a guide for how to conduct photon antibunching experiments at the single molecule level by applying techniques borrowed from time-correlated single photon counting. We provide a number of new examples for applications of photon antibunching to the study of multichromophoric molecules and small molecular complexes.
Date: April 17, 2007
Creator: Fore, S; Laurence, T; Hollars, C & Huser, T
Object Type: Article
System: The UNT Digital Library
Stable SUSY breaking model with O(10) eV gravitino from combined D-term gauge mediation and U(1)' mediation (open access)

Stable SUSY breaking model with O(10) eV gravitino from combined D-term gauge mediation and U(1)' mediation

We show a calculable example of stable supersymmetry (SUSY) breaking modelswith O(10) eV gravitino mass based on the combination of D-term gauge mediationand U(1)' mediation. A potential problem of the negative mass squared for theSUSY standard model (SSM) sfermions in the D-term gauge mediation is solvedby the contribution from the U(1)' mediation. On the other hand, the splittingbetween the SSM gauginos and sfermions in the U(1)' mediation iscircumvented bythe contributions from the D-term gauge mediation. Since the U(1)' mediation doesnot introduce any new SUSY vacua, we achieve a completely stable model underthermal effects. Our model, therefore, has no cosmological difficulty.
Date: December 17, 2007
Creator: Nakayama, Yu & Nakayama, Yu
Object Type: Article
System: The UNT Digital Library
Test Plan: Sludge Treatment Project Corrosion Process Chemistry Follow-on Testing (open access)

Test Plan: Sludge Treatment Project Corrosion Process Chemistry Follow-on Testing

This test plan was prepared by the Pacific Northwest National Laboratory (PNNL) under contract with Fluor Hanford (FH). The test plan describes the scope and conditions to be used to perform laboratory-scale testing of the Sludge Treatment Project (STP) hydrothermal treatment of K Basin sludge. The STP, managed for the U. S. Department of Energy (DOE) by FH, was created to design and operate a process to eliminate uranium metal from the sludge prior to packaging for Waste Isolation Pilot Plant (WIPP) by using high temperature liquid water to accelerate the reaction, produce uranium dioxide from the uranium metal, and safely discharge the hydrogen. The proposed testing builds on the approach and laboratory test findings for both K Basin sludge and simulated sludge garnered during prior testing from September 2006 to March 2007. The outlined testing in this plan is designed to yield further understanding of the nature of the chemical reactions, the effects of compositional and process variations and the effectiveness of various strategies to mitigate the observed high shear strength phenomenon observed during the prior testing. These tests are designed to provide process validation and refinement vs. process development and design input. The expected outcome is to establish …
Date: August 17, 2007
Creator: Delegard, Calvin H.; Schmidt, Andrew J. & Poloski, Adam P.
Object Type: Report
System: The UNT Digital Library
A Lattice with Larger Momentum Compaction for the NLC Main Damping Rings (open access)

A Lattice with Larger Momentum Compaction for the NLC Main Damping Rings

Previous lattice designs for the Next Linear Collider Main Damping Rings [1] have met the specifications for equilibrium emittance, damping rate and dynamic aperture. Concerns about the effects of the damping wiggler on the beam dynamics [2] led to the aim of reducing the total length of the wiggler to a minimum consistent with the required damping rate, so high-field dipoles were used to provide a significant energy loss in the arcs. However, recent work has shown that the wiggler effects may not be as bad as previously feared. Furthermore, other studies have suggested the need for an increased momentum compaction (by roughly a factor of four) to raise the thresholds of various collective effects. We have therefore developed a new lattice design in which we increase the momentum compaction by reducing the field strength in the arc dipoles, compensating the loss in damping rate by increasing the length of the wiggler. The new lattice again meets the specifications for emittance, damping rate and dynamic aperture, while having the benefit of significantly higher thresholds for a number of instabilities.
Date: March 17, 2008
Creator: Woodley, M.; Raubenheimer, Tor O.; Wu, J.; Wolski, A. & /SLAC /LBL, Berkeley
Object Type: Article
System: The UNT Digital Library
Thermal Neutron Capture Cross Sections of the PalladiumIsotopes (open access)

Thermal Neutron Capture Cross Sections of the PalladiumIsotopes

Precise gamma-ray thermal neutron capture cross sectionshave been measured at the Budapest Reactor for all elements withZ=1-83,92 except for He and Pm. These measurements and additional datafrom the literature been compiled to generate the Evaluated Gamma-rayActivation File (EGAF), which is disseminated by LBNL and the IAEA. Thesedata are nearly complete for most isotopes with Z<20 so the totalradiative thermal neutron capture cross sections can be determineddirectly from the decay scheme. For light isotopes agreement with therecommended values is generally satisfactory although large discrepanciesexist for 11B, 12,13C, 15N, 28,30Si, 34S, 37Cl, and 40,41K. Neutroncapture decay data for heavier isotopes are typically incomplete due tothe contribution of unresolved continuum transitions so only partialradiative thermal neutron capture cross sections can be determined. Thecontribution of the continuum to theneutron capture decay scheme arisesfrom a large number of unresolved levels and transitions and can becalculated by assuming that the fluctuations in level densities andtransition probabilities are statistical. We have calculated thecontinuum contribution to neutron capture decay for the palladiumisotopes with the Monte Carlo code DICEBOX. These calculations werenormalized to the experimental cross sections deexciting low excitationlevels to determine the total radiative thermal neutron capture crosssection. The resulting palladium cross sections values were determinedwith a precision …
Date: July 17, 2006
Creator: Firestone, R.B.; Krticka, M.; McNabb, D.P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T. et al.
Object Type: Article
System: The UNT Digital Library
Fragmentation Cross Sections of 290 and 400 MeV/nucleon 12C Beamson Elemental Targets (open access)

Fragmentation Cross Sections of 290 and 400 MeV/nucleon 12C Beamson Elemental Targets

Charge-changing and fragment production cross sections at 0circ have been obtained for interactions of 290 MeV/nucleon and 400MeV/nucleon carbon beams with C, CH2, Al, Cu, Sn, and Pb targets. Thesebeams are relevant to cancer therapy, space radiation, and the productionof radioactive beams. We compare to previously published results using Cand CH2 targets at similar beam energies. Due to ambiguities arising fromthe presence of multiple fragments on many events, previous publicationshave reported only cross sections for B and Be fragments. In this work wehave extracted cross sections for all fragment species, using dataobtained at three distinct values of angular acceptance, supplemented bydata taken with the detector stack placed off the beam axis. A simulationof the experiment with the PHITS Monte Carlo code shows fair agreementwith the data obtained with the large acceptance detectors, but agreementis poor at small acceptance. The measured cross sections are alsocompared to the predictions of the one-dimensional cross section modelsEPAX2 and NUCFRG2; the latter is presently used in NASA's space radiationtransport calculations. Though PHITS and NUCFRG2 reproduce thecharge-changing cross sections with reasonable accuracy, none of themodels is able to accurately predict the fragment cross sections for allfragment species and target materials.
Date: March 17, 2007
Creator: Zeitlin, C.; Guetersloh, S.; Heilbronn, L.; Miller, J.; Fukumura,A.; Iwata, Y. et al.
Object Type: Article
System: The UNT Digital Library
A fast algorithm for three-dimensional interpretations ofsingle-well electromagnetic data (open access)

A fast algorithm for three-dimensional interpretations ofsingle-well electromagnetic data

An efficient inversion algorithm has been developed forthree-dimensional (3D) interpretations for single-hole electromagnetic(EM) logging data based on a modified extended Born approximation (MEBA)scheme. The single-hole data was collected at an oil field undergoing CO2injection in southern California using a tool, Geo-BILT, developed byElectromagnetic Instruments, Inc (EMI). The tool is equipped with amulti-component source, and an array of multi-component receivers atdifferent separations. The inversion result provides a reasonableelectrical conductivity image to a distance of 10 m from the well, andillustrates several zones with lateral conductivity variations that couldnot be resolved with traditional induction logging tools. The computercost of the inversion processes can be further reduced using a trivialmulti-grid methodology.
Date: September 17, 2004
Creator: Tseng, Hung-Wen & Lee, Ki Ha
Object Type: Report
System: The UNT Digital Library

High-Efficiency Solar Cells for Large-Scale Electricity Generation & Design Considerations for the Related Optics

The photovoltaic industry has been growing exponentially at an average rate of about 35%/year since 1979. Recently, multijunction concentrator cell efficiencies have surpassed 40%. Combined with concentrating optics, these can be used for electricity generation.
Date: September 17, 2007
Creator: Kurtz, S.; Olson, J.; Geisz, J.; Friedman, D.; McMahon, W.; Ptak, A. et al.
Object Type: Presentation
System: The UNT Digital Library
Efficient computation of matched solutions of the KV envelope equations for periodic focusing lattices. (open access)

Efficient computation of matched solutions of the KV envelope equations for periodic focusing lattices.

A new iterative method is developed to numerically calculate the periodic, matched beam envelope solution of the coupled Kapchinskij-Vladimirskij (KV) equations describing the transverse evolution of a beam in a periodic, linear focusing lattice of arbitrary complexity. Implementation of the method is straightforward. It is highly convergent and can be applied to all usual parameterizations of the matched envelope solutions. The method is applicable to all classes of linear focusing lattices without skew couplings, and also applies to parameters where the matched beam envelope is strongly unstable. Example applications are presented for periodic solenoidal and quadrupole focusing lattices. Convergence properties are summarized over a wide range of system parameters.
Date: January 17, 2006
Creator: Lund, S M; Chilton, S H & Lee, E P
Object Type: Article
System: The UNT Digital Library
Modeling geologic storage of carbon dioxide: Comparison of non-hysteretic and hysteretic characteristic curves (open access)

Modeling geologic storage of carbon dioxide: Comparison of non-hysteretic and hysteretic characteristic curves

Numerical models of geologic storage of carbon dioxide (CO2)in brine-bearing formations use characteristic curves to represent theinteractions of non-wetting-phase CO2 and wetting-phase brine. When aproblem includes both injection of CO2 (a drainage process) and itssubsequent post-injection evolution (a combination of drainage andwetting), hysteretic characteristic curves are required to correctlycapture the behavior of the CO2 plume. In the hysteretic formulation,capillary pressure and relative permeability depend not only on thecurrent grid-block saturation, but also on the history of the saturationin the grid block. For a problem that involves only drainage or onlywetting, a non-hysteretic formulation, in which capillary pressure andrelative permeability depend only on the current value of the grid-blocksaturation, is adequate. For the hysteretic formulation to be robustcomputationally, care must be taken to ensure the differentiability ofthe characteristic curves both within and beyond the turning-pointsaturations where transitions between branches of the curves occur. Twoexample problems involving geologic CO2 storage are simulated withTOUGH2, a multiphase, multicomponent code for flow and transport codethrough geological media. Both non-hysteretic and hysteretic formulationsare used, to illustrate the applicability and limitations ofnon-hysteretic methods.The first application considers leakage of CO2from the storage formation to the ground surface, while the secondexamines the role of heterogeneity within the storageformation.
Date: July 17, 2006
Creator: Doughty, Christine
Object Type: Article
System: The UNT Digital Library
Physics design of a cold neutron source for KIPT neutron source facility. (open access)

Physics design of a cold neutron source for KIPT neutron source facility.

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. It is based on the use of an electron accelerator driven subcritical (ADS) facility with low enriched uranium fuel, using the existing electron accelerators at KIPT of Ukraine [1]. The neutron source of the subcritical assembly is generated from the interaction of 100-KW electron beam, which has a uniform spatial distribution and the electron energy in the range of 100 to 200 MeV, with a natural uranium target [2]. The main functions of the facility are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron beam experiments and material studies are also included. Over the past two-three decades, structures with characteristic lengths of 100 {angstrom} and correspondingly smaller vibrational energies have become increasingly important for both science and technology [3]. The characteristic dimensions of the microstructures can be well matched by neutrons with longer vibrational wavelength and lower energy. In the accelerator-driven subcritical facility, most of the neutrons are generated from fission reactions with energy in the MeV range. They are slowed down to the …
Date: February 17, 2009
Creator: Zhong, Z.; Gohar, Y. & Kellogg, R.
Object Type: Report
System: The UNT Digital Library
PERTURBATION-THEORY RULES FOR COMPUTING THE SELF-ENERGY OPERATOR IN QUANTUM STATISTICAL MECHANICS (open access)

PERTURBATION-THEORY RULES FOR COMPUTING THE SELF-ENERGY OPERATOR IN QUANTUM STATISTICAL MECHANICS

Highly convenient rules are given for the general term in the time-independent perturbation-theory expansion for the self-energy operator of quantum statistical mechanics. The rules are derived by starting from the usual formalism involving time-dependent Green's functions. The well-known formulas for thermodynamic quantities in terms of the self-energy operator are included for completeness.
Date: December 17, 1962
Creator: Baym, Gordon & Sessler, Andrew M.
Object Type: Article
System: The UNT Digital Library
Metrologies for the Phase Characterization of Attosecond (open access)

Metrologies for the Phase Characterization of Attosecond

EUV optics play a key role in attosecond science since only with higher photon energies is it possible to achieve the wide spectral bandwidth required for ultrashort pulses. Multilayer EUV mirrors have been proposed and are being developed to temporally shape (compress) attosecond pulses. To fully characterize a multilayer optic for pulse applications requires not only knowledge of the reflectivity, as a function of photon energy, but also the reflected phase of the mirror. This work develops the metrologies to determine the reflected phase of an EUV multilayer mirror using the photoelectric effect. The proposed method allows one to determine the optic's impulse response and hence its pulse characteristics.
Date: January 17, 2008
Creator: CXRO
Object Type: Article
System: The UNT Digital Library
Precipitation Protocol Optimization for Trace Amounts of DNA (open access)

Precipitation Protocol Optimization for Trace Amounts of DNA

None
Date: August 17, 2007
Creator: Wheeler, E; Erler, A & Seiler, A
Object Type: Report
System: The UNT Digital Library
Development of Room-temperature CdMnTe Gamma-ray Detectors (open access)

Development of Room-temperature CdMnTe Gamma-ray Detectors

CdMnTe materials have wide bandgap, high resistivity, fair electron-transport properties, and good compositional uniformity. All these features make CdMnTe a good candidate for low cost, high-resolution room-temperature gamma-ray detector. Using several techniques available at BNL, we are characterizing CdMnTe as a material for gamma-ray detectors. The consequent improvements in growth, fabrication, and manufacturing techniques for CdMnTe potentially yield a suitable material for sensing devices with lower production costs. Success of this research has the possibility of generating high impact to nuclear nonproliferation with the goal of offering inexpensive highly sensitive gamma spectrometers.
Date: June 17, 2008
Creator: Bolotnikov, A.
Object Type: Article
System: The UNT Digital Library
Lawrence Livermore National Laboratory Pre-project Rare Plant and Wildlife Surveys For the Pit 7 Drainage Diversion and Groundwater Extraction and Treatment Facility (open access)

Lawrence Livermore National Laboratory Pre-project Rare Plant and Wildlife Surveys For the Pit 7 Drainage Diversion and Groundwater Extraction and Treatment Facility

In January 2007, the Department of Energy (DOE) released the final Environmental Assessment for the Proposed Environmental Remediation at the Lawrence Livermore National Laboratory (LLNL) Site 300 Pit 7 Complex. At the same time, the Department of Toxic Substances Control (DTSC) released the final Negative Declaration and Initial Study covering the Pit 7 remediation. No substantial adverse effect on wildlife species of concern was anticipated from the project. However, it was proposed that wildlife surveys should be conducted prior to construction because species locations and breeding areas could potentially change by the time construction activities began. Although no known populations of rare or endangered/threatened plant species were known to occur within the project impact area at the time these documents were released, rare plants listed by the California Native Plant Society had been observed in the vicinity. As such, both DOE and DTSC proposed that plant surveys would be undertaken at the appropriate time of year to determine if rare plants would be impacted by project construction. This document provides the results of wildlife and rare plant surveys taken prior to the start of construction at the Pit 7 Complex.
Date: July 17, 2007
Creator: Paterson, L & Woollett, J
Object Type: Report
System: The UNT Digital Library
Verification Test Suite (VERTS) For Rail Gun Applications using ALE3D: 2-D Hydrodynamics & Thermal Cases (open access)

Verification Test Suite (VERTS) For Rail Gun Applications using ALE3D: 2-D Hydrodynamics & Thermal Cases

A verification test suite has been assessed with primary focus on low reynolds number flow of liquid metals. This is representative of the interface between the armature and rail in gun applications. The computational multiphysics framework, ALE3D, is used. The main objective of the current study is to provide guidance and gain confidence in the results obtained with ALE3D. A verification test suite based on 2-D cases is proposed and includes the lid-driven cavity and the Couette flow are investigated. The hydro and thermal fields are assumed to be steady and laminar in nature. Results are compared with analytical solutions and previously published data. Mesh resolution studies are performed along with various models for the equation of state.
Date: April 17, 2008
Creator: Najjar, F M; Solberg, J & White, D
Object Type: Report
System: The UNT Digital Library
On Sub-linear Convergence for Linearly Degenerate Waves in Capturing Schemes (open access)

On Sub-linear Convergence for Linearly Degenerate Waves in Capturing Schemes

A common attribute of capturing schemes used to find approximate solutions to the Euler equations is a sub-linear rate of convergence with respect to mesh resolution. Purely nonlinear jumps, such as shock waves produce a first-order convergence rate, but linearly degenerate discontinuous waves, where present, produce sub-linear convergence rates which eventually dominate the global rate of convergence. The classical explanation for this phenomenon investigates the behavior of the exact solution to the numerical method in combination with the finite error terms, often referred to as the modified equation. For a first-order method, the modified equation produces the hyperbolic evolution equation with second-order diffusive terms. In the frame of reference of the traveling wave, the solution of a discontinuous wave consists of a diffusive layer that grows with a rate of t{sup 1/2}, yielding a convergence rate of 1/2. Self-similar heuristics for higher order discretizations produce a growth rate for the layer thickness of {Delta}t{sup 1/(p+1)} which yields an estimate for the convergence rate as p/(p+1) where p is the order of the discretization. In this paper we show that this estimated convergence rate can be derived with greater rigor for both dissipative and dispersive forms of the discrete error. In …
Date: March 17, 2008
Creator: Banks, J W; Aslam, T & Rider, W J
Object Type: Article
System: The UNT Digital Library
Novel Method for Growing Te-Inclusion-Free CZT (open access)

Novel Method for Growing Te-Inclusion-Free CZT

The authors propose a new method for growth of detector-grade CdZnTe (CZT) with reduced concentration and sizes of Te inclusions. The method is designed to impede the formation of Te-rich inclusions in crystals due to the use of new CZT growth method and a unique ampoule design.
Date: June 17, 2008
Creator: Bolotnikov, A.
Object Type: Article
System: The UNT Digital Library
Investigation of the Quantrum Structure of Surfaces with Far UV Excitation Spectrosscopies (open access)

Investigation of the Quantrum Structure of Surfaces with Far UV Excitation Spectrosscopies

Clean surfaces and those with adsorbates have been investigated to obtain electronic and atomic structure data. The various modes of synchrotron radiation (SR) photoemission spectroscopy (PES) have been performed mostly beam line 7.0.1 at the Advanced Light Source (ALS) in Berkeley, CA and some at the Synchrotron Radiation Center (SRC) in Madison, WI. These were done on silicon, carbon, and group III nitrides.
Date: October 17, 2008
Creator: Lapeyre, Gerlad
Object Type: Report
System: The UNT Digital Library
A Parallel Code for Lifetime Simulations in Hadron Storage Rings in the Presence of Parasitic Beam-Beam Interactions (open access)

A Parallel Code for Lifetime Simulations in Hadron Storage Rings in the Presence of Parasitic Beam-Beam Interactions

The usual approach to predict particle loss in storage rings in the presence of nonlinearities consists in the determination of the dynamic aperture of the machine. This method, however, will not directly predict the lifetimes of beams. We have developed a code which can, by parallelization and careful speed optimization, predict lifetimes in the presence of 100 parasitic beam-beam crossings by tracking &gt; 10{sup 10} particles-turns. An application of this code to the anti-proton lifetime in the Tevatron at injection is discussed.
Date: March 17, 2008
Creator: Kabel, A. C.; Cai, Y.; Erdelyi, B.; Sen, T. & Xiao, M.
Object Type: Article
System: The UNT Digital Library