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Origin of Scale-Dependent Dispersivity and Its Implications For Miscible Gas Flooding

Description: Dispersive mixing has an important impact on the effectiveness of miscible floods. Simulations routinely assume Fickian dispersion, yet it is well established that dispersivity depends on the scale of measurement. This is one of the main reasons that a satisfactory method for design of field-scale miscible displacement processes is still not available. The main objective of this project was to improve the understanding of the fundamental mechanisms of dispersion and mixing, particularly at the … more
Date: September 30, 2008
Creator: Bryant, Steven; Johns, Russ; Lake, Larry & Harmon, Thomas
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Novel Class of High-TC Ferromagnetic Semiconductors

Description: We have grown single crystals of novel ruthenates (Sr,Ba)(Fe,Co){sub 2+x}Ru{sub 4-x}O{sub 11} that exhibit long-range ferromagnetic order well above room temperature, accompanied by narrow-gap semiconducting properties that include a large anomalous Hall conductance, low resistivity, high carrier concentration and low coercive field, which are properties well suited to spintronic applications. X-ray diffraction, EDX, neutron diffraction and x-ray absorption measurements on single crystals firml… more
Date: May 30, 2008
Creator: Shlyk, L. V.; Kryukov, S. A.; De Long, L. E.; Schupp-Niewa, B.; Niewa, R.; Lynn, J. W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Mechanistic Treatment of the Dominant Soil Nitrogen Cycling Processes: Model Development, Testing, and Application

Description: The development and initial application of a mechanistic model (TOUGHREACT-N) designed to characterize soil nitrogen (N) cycling and losses are described. The model couples advective and diffusive nutrient transport, multiple microbial biomass dynamics, and equilibrium and kinetic chemical reactions. TOUGHREACT-N was calibrated and tested against field measurements to assess pathways of N loss as either gas emission or solute leachate following fertilization and irrigation in a Central Valley, … more
Date: May 1, 2008
Creator: Riley, William; Maggi, F.; Gu, C.; Riley, W. J.; Hornberger, G. M.; Venterea, R. T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Use of a dynamic simulation model to understand nitrogen cycling in the middle Rio Grande, NM.

Description: Water quality often limits the potential uses of scarce water resources in semiarid and arid regions. To best manage water quality one must understand the sources and sinks of both solutes and water to the river system. Nutrient concentration patterns can identify source and sink locations, but cannot always determine biotic processes that affect nutrient concentrations. Modeling tools can provide insight into these large-scale processes. To address questions about large-scale nitrogen removal … more
Date: August 1, 2008
Creator: Meixner, Tom (University of Arizona, Tucson, AZ); Tidwell, Vincent Carroll; Oelsner, Gretchen (University of Arizona, Tucson, AZ); Brooks, Paul (University of Arizona, Tucson, AZ) & Roach, Jesse D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Timescales of spherulite crystallization in obsidian inferred from water concentration profiles

Description: We determined the kinetics of spherulite growth in obsidians from Krafla volcano, Iceland. We measured water concentration profiles around spherulites in obsidian by synchrotron Fourier transform infrared spectroscopy. The distribution of OH? groups surrounding spherulites decreases exponentially away from the spherulite-glass border, reflecting expulsion of water during crystallization of an anhydrous paragenesis (plagioclase + SiO2 + clinopyroxene + magnetite). This pattern is controlled by a… more
Date: June 25, 2008
Creator: Castro, Jonathan M.; Beck, Pierre; Tuffen, Hugh; Nichols, Alexander R.L.; Dingwell, Donald B. & Martin, Michael C
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Evolution, Interaction, and Intrinsic Properties of Dislocations in Intermetallics: Anisotropic 3D Dislocation Dynamics Approach

Description: The generation, motion, and interaction of dislocations play key roles during the plastic deformation process of crystalline solids. 3D Dislocation Dynamics has been employed as a mesoscale simulation algorithm to investigate the collective and cooperative behavior of dislocations. Most current research on 3D Dislocation Dynamics is based on the solutions available in the framework of classical isotropic elasticity. However, due to some degree of elastic anisotropy in almost all crystalline sol… more
Date: August 18, 2008
Creator: Chen, Qian
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Role of Nucleation and Growth in Two-Phase Microstructure Formation

Description: During the directional solidification of peritectic alloys, a rich variety of two-phase microstructures develop, and the selection process of a specific microstructure is complicated due to the following two considerations. (1) In contrast to many single phase and eutectic microstructures that grow under steady state conditions, two-phase microstructures in a peritectic system often evolve under non-steady-state conditions that can lead to oscillatory microstructures, and (2) the microstructure… more
Date: May 1, 2008
Creator: Shin, Jong Ho
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Continuous time random walk analysis of solute transport in fractured porous media

Description: The objective of this work is to discuss solute transport phenomena in fractured porous media, where the macroscopic transport of contaminants in the highly permeable interconnected fractures can be strongly affected by solute exchange with the porous rock matrix. We are interested in a wide range of rock types, with matrix hydraulic conductivities varying from almost impermeable (e.g., granites) to somewhat permeable (e.g., porous sandstones). In the first case, molecular diffusion is the only… more
Date: June 1, 2008
Creator: Cortis, Andrea; Cortis, Andrea & Birkholzer, Jens
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Development of Hydrologic Characterization Technology of Fault Zones

Description: Through an extensive literature survey we find that there is very limited amount of work on fault zone hydrology, particularly in the field using borehole testing. The common elements of a fault include a core, and damage zones. The core usually acts as a barrier to the flow across it, whereas the damage zone controls the flow either parallel to the strike or dip of a fault. In most of cases the damage zone isthe one that is controlling the flow in the fault zone and the surroundings. The perme… more
Date: March 31, 2008
Creator: Karasaki, Kenzi; Onishi, Tiemi & Wu, Yu-Shu
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Research and Development Concerning Coalbed Natural Gas

Description: The Powder River Basin in northeastern Wyoming is one of the most active areas of coalbed natural gas (CBNG) development in the western United States. This resource provides clean energy but raises environmental concerns. Primary among these is the disposal of water that is co-produced with the gas during depressurization of the coal seam. Beginning with a few producing wells in Wyoming's Powder River Basin (PRB) in 1987, CBNG well numbers in this area increased to over 13,600 in 2004, with pro… more
Date: September 30, 2008
Creator: Ruckelshaus, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Modeling the diffusion of Na+ in compacted water-saturated Na-bentonite as a function of pore water ionic strength

Description: Assessments of bentonite barrier performance in waste management scenarios require an accurate description of the diffusion of water and solutes through the barrier. A two-compartment macropore/nanopore model (on which smectite interlayer nanopores are treated as a distinct compartment of the overall pore space) was applied to describe the diffusion of {sup 22}Na{sup +} in compacted, water-saturated Na-bentonites and then compared with the well-known surface diffusion model. The two-compartment… more
Date: August 15, 2008
Creator: Bourg, I.C.; Sposito, G. & Bourg, A.C.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A sequential partly iterative approach for multicomponent reactive transport with CORE2D

Description: CORE{sup 2D} V4 is a finite element code for modeling partly or fully saturated water flow, heat transport and multicomponent reactive solute transport under both local chemical equilibrium and kinetic conditions. It can handle coupled microbial processes and geochemical reactions such as acid-base, aqueous complexation, redox, mineral dissolution/precipitation, gas dissolution/exsolution, ion exchange, sorption via linear and nonlinear isotherms, sorption via surface complexation. Hydraulic pa… more
Date: November 1, 2008
Creator: Samper, J.; Xu, T. & Yang, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Lattice Boltzmann simulation of solute transport in heterogeneous porous media with conduits to estimate macroscopic continuous time random walk model parameters

Description: Lattice Boltzmann models simulate solute transport in porous media traversed by conduits. Resulting solute breakthrough curves are fitted with Continuous Time Random Walk models. Porous media are simulated by damping flow inertia and, when the damping is large enough, a Darcy's Law solution instead of the Navier-Stokes solution normally provided by the lattice Boltzmann model is obtained. Anisotropic dispersion is incorporated using a direction-dependent relaxation time. Our particular interest… more
Date: October 20, 2008
Creator: Anwar, S.; Cortis, A. & Sukop, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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An Innovative System for the Efficient and Effective Treatment of Non-Traditional Waters for Reuse in Thermoelectric Power Generation

Description: This study assessed opportunities for improving water quality associated with coal-fired power generation including the use of non-traditional waters for cooling, innovative technology for recovering and reusing water within power plants, novel approaches for the removal of trace inorganic compounds from ash pond effluents, and novel approaches for removing biocides from cooling tower blowdown. This research evaluated specifically designed pilot-scale constructed wetland systems for treatment o… more
Date: August 31, 2008
Creator: Rodgers, John & Castle, James
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico

Description: Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubilit… more
Date: October 1, 2008
Creator: Birkle, P.; Pruess, K.; Xu, T.; Figueroa, R.A. Hernandez; Lopez, M. Diaz & Lopez, E. Contreras
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Multiphase flow and multicomponent reactive transport model of the ventilation experiment in Opalinus clay

Description: During the construction and operational phases of a high-level radioactive waste (HLW) repository constructed in a clay formation, ventilation of underground drifts will cause desaturation and oxidation of the rock. The Ventilation Experiment (VE) was performed in a 1.3 m diameter unlined horizontal microtunnel on Opalinus clay at Mont Terri underground research laboratory in Switzerland to evaluate the impact of desaturation on rock properties. A multiphase flow and reactive transport model of… more
Date: October 15, 2008
Creator: Zheng, L.; Samper, J.; Montenegro, L. & Major, J.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

K-1435 Wastewater Treatment System for the Toxic Substances Control Act Incinerator Wastewater at the East Tennessee Technology Park, Oak Ridge, TN

Description: This paper discusses the design and performance of a wastewater treatment system installed to support the operation of a hazardous waste incinerator. The Oak Ridge Toxic Substances Control Act Incinerator (TSCAI), located at the East Tennessee Technology Park (ETTP), is designed and permitted to treat Resource ConservatioN and Recovery Act (RCRA) wastes including characteristic and listed wastes and polychlorinated biphenyl (PCB)-contaminated mixed waste. the incinerator process generates acidi… more
Date: February 24, 2008
Creator: M.D., Swientoniewski
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Elements of fractal generalization of dual-porosity model for solute transport in unsaturated fractured rocks

Description: In this study, new elements were developed to generalize the dual-porosity model for moisture infiltration on and solute transport in unsaturated rocks, taking into account fractal aspects of the percolation process. Random advection was considered as a basic mechanism of solute transport in self-similar fracture systems. In addition to spatial variations in the infiltration velocity field, temporal fluctuations were also taken into account. The rock matrix, a low-permeability component of the … more
Date: September 1, 2008
Creator: Bolshov, L.; Kondratenko, P.; Matveev, L. & Pruess, K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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