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A Self-Consistent Approach for Calculating the Effective Hydraulic Conductivity of a Bimodal, Heterogeneous Medium

Description: In this paper, we consider an approach for estimating the effective hydraulic conductivity of a 3D medium with a binary distribution of local hydraulic conductivities. The medium heterogeneity is represented by a combination of matrix medium conductivity with spatially distributed sets of inclusions. Estimation of effective conductivity is based on a self-consistent approach introduced by Shvidler (1985). The tensor of effective hydraulic conductivity is calculated numerically by using a simple system of equations for the main diagonal elements. Verification of the method is done by comparison with theoretical results for special cases and numerical results of Desbarats (1987) and our own numerical modeling. The method was applied to estimating the effective hydraulic conductivity of a 2D and 3D fractured porous medium. The medium heterogeneity is represented by a combination of matrix conductivity and a spatially distributed set of highly conductive fractures. The tensor of effective hydraulic conductivity is calculated for parallel- and random-oriented sets of fractures. The obtained effective conductivity values coincide with Romm's (1966) and Snow's (1969) theories for infinite fracture length. These values are also physically acceptable for the sparsely-fractured-medium case with low fracture spatial density and finite fracture length. Verification of the effective hydraulic conductivity obtained for a fractured porous medium is done by comparison with our own numerical modeling for a 3D case and with Malkovsky and Pek's (1995) results for a 2D case.
Date: January 2, 2004
Creator: Pozdniakov, Sergey & Tsang, Chin-Fu
Partner: UNT Libraries Government Documents Department

Coupled processes of fluid flow, solute transport, and geochemical reactions in reactive barriers

Description: A complex pattern of coupling between fluid flow and mass transport develops when heterogeneous reactions occur. For instance, dissolution and precipitation reactions can change a porous medium's physical properties, such as pore geometry and thus permeability. These changes influence fluid flow, which in turn impacts the composition of dissolved constituents and the solid phases, and the rate and direction of advective transport. Two-dimensional modeling studies using TOUGHREACT were conducted to investigate the coupling between flow and transport developed as a consequence of differences in density, dissolution precipitation, and medium heterogeneity. The model includes equilibrium reactions for aqueous species, kinetic reactions between the solid phases and aqueous constituents, and full coupling of porosity and permeability changes resulting from precipitation and dissolution reactions in porous media. In addition, a new permeability relationship is implemented in TOUGHREACT to examine the effects of geochemical reactions and density difference on plume migration in porous media. Generally, the evolutions in the concentrations of the aqueous phase are intimately related to the reaction-front dynamics. Plugging of the medium contributed to significant transients in patterns of flow and mass transport.
Date: January 2, 2004
Creator: Kim, Jeongkon; Schwartz, Franklin W.; Xu, Tianfu & Choi, Heechul, and Kim, In S.
Partner: UNT Libraries Government Documents Department

Visualization of microcrack anisotropy in granite affected by afault zone, using confocal laser scanning microscope

Description: Brittle deformation in granite can generate a fracture system with different patterns. Detailed fracture analyses at both macroscopic and microscopic scales, together with physical property data from a drill-core, are used to classify the effects of reverse fault deformation in four domains: (1) undeformed granite, (2) fractured granite with cataclastic seams, (3) fractured granite from the damage zone, and (4) foliated cataclasite from the core of the fault. Intact samples from two orthogonal directions, horizontal (H) and vertical (V), from the four domains indicate a developing fracture anisotropy toward the fault, which is highly developed in the damage zone. As a specific illustration of this phenomenon, resin impregnation, using a confocal laser scanning microscope (CLSM) technique is applied to visualize the fracture anisotropy developed in the Toki Granite, Japan. As a result, microcrack networks have been observed to develop in H sections and elongate open cracks in V sections, suggesting that flow pathways can be determined by deformation.
Date: January 2, 2004
Creator: Onishi, Celia T. & Shimizu, Ichiko
Partner: UNT Libraries Government Documents Department

Low-energy operation of the Livermore electron beam ion traps: Atomic spectroscopy of Si V, S VII, and Ar IX

Description: As part of a project to compile a comprehensive catalog of astrophysically relevant emission lines, we used the low-energy capability of the Lawrence Livermore electron beam ion traps to extend the spectroscopy of neon-like ions and the neighboring charge states to silicon, sulfur, and argon. They present wavelength data of Si V and demonstrate the effect of collisional deexcitation of electric dipole forbidden lines on the 2-3 L-shell spectra of Si V, S VII, and Ar IX.
Date: January 2, 2004
Creator: Lepson, J K & Beiersdorfer, P
Partner: UNT Libraries Government Documents Department

Rapid thermal cycling of metal-supported solid oxide fuel cellmembranes

Description: Solid oxide fuel cell (SOFC) membranes were developed in which zirconia-based electrolyte thin films were supported by a composite metal/ceramic electrode, and were subjected to rapid thermal cycling between 200 and 800 C. The effects of this cycling on membrane performance were evaluated. The membranes, not yet optimized for performance, showed a peak power density of 350mW/cm2at 900 C in laboratory-sized SOFCs that was not affected by the thermal cycling. This resistance to cycling degradation is attributed to the close matching of thermal expansion coefficient of the cermet support electrode with that of the zirconia electrolyte.
Date: January 2, 2004
Creator: Matus, Yuriy B.; De Jonghe, Lutgard C.; Jacobson, Craig P. & Visco, Steven J.
Partner: UNT Libraries Government Documents Department

Border Security and Unmanned Aerial Vehicles

Description: The use of Unmanned Aerial Vehicles (UAVs) to improve border security is a technique that has garnered congressional attention. This report examines the strengths and limitations of deploying UAVs along the borders and related issues for Congress. This report is not intended to provide in-depth information regarding technical or military capabilities of UAVs, but to discuss their application at the border.
Date: January 2, 2004
Creator: Blazakis, Jason
Partner: UNT Libraries Government Documents Department

COLAs for Military Retirees: Summary of Congressional and Executive Branch Action, 1982-2003 (FY1983-FY2004)

Description: The Omnibus Reconciliation Act of 1982 (which applied to FY1983 budget issues) suspended previously existing permanent law pertaining to cost-of-living adjustments(COLAs) for federal civilian and military retirees, and changed the COLA calculation formulas to postpone and/or reduce future COLAs for military retirees during 1983-1985 (FY1984-FY1986).This report examines executive and congressional COLA-related initiatives associated with each of the fiscal year budgeting processes from calendar year 1982 (FY1983) through calendar year 2000 (FY2001).
Date: January 2, 2004
Creator: Goldich, Robert L.
Partner: UNT Libraries Government Documents Department

Comparison of Wide-Bandgap Semiconductors for Power Electronics Applications

Description: Recent developmental advances have allowed silicon (Si) semiconductor technology to approach the theoretical limits of the Si material; however, power device requirements for many applications are at a point that the present Si-based power devices cannot handle. The requirements include higher blocking voltages, switching frequencies, efficiency, and reliability. To overcome these limitations, new semiconductor materials for power device applications are needed. For high power requirements, wide-bandgap semiconductors like silicon carbide (SiC), gallium nitride (GaN), and diamond, with their superior electrical properties, are likely candidates to replace Si in the near future. This report compares wide-bandgap semiconductors with respect to their promise and applicability for power applications and predicts the future of power device semiconductor materials.
Date: January 2, 2004
Creator: Ozpineci, B.
Partner: UNT Libraries Government Documents Department

Discussion about the tingtou, a musical instrument

Description: Elders from various villages who are experts in traditional songs and dance, including Beshot Tholung of Thamlapokpi, Bunghon Suungnem of Leingangching, Shangwar Dilbung of Khuibung, and Beshot Khular of Phaidaam discuss the tingtou, a bamboo mouthpiece musical instrument that one can use to compose any song or play any of their known songs. It is also mentioned that this particular musical instrument is given by men to woo the women they love.
Date: January 2, 2004
Creator: Tholung, Daniel
Partner: UNT College of Information

Discussion of dance steps [kardaam]

Description: Elders who are experts in traditional songs and dance, including Beshot Tholung of Thamlapokpi, Bunghon Suungnem of Leingangching, Shangwar Dilbung of Khuibung, and Beshot Khullar of Phaidaam, give instructions to the dancers on the dance steps [kardaam] in the Charangching Khullen village.
Date: January 2, 2004
Creator: Tholung, Daniel
Partner: UNT College of Information

Discussion of Cheldep, the Lamkang hero

Description: Elders Beshot Tholung of Thamlapokpo, Bunghon Suungnem of Leingangching, Shangwar Dilbung of Khuibung, Daniel Tholung of Thamlakhuren, and Beshot Khullar and Sankhil Belun of Phaidaam discuss Cheldep, the Lamkang hero. Cheldep is a young man who was brought by Shenoi. As for Shenoi we are not so sure, but he was arrested during the war they heard. Sankhils claimed the “Yamluung”, a musical instrument, as their property. But later the Dilbungs claimed it as Vangkhiin who is the owner of the musical instrument. They discuss about a Dilbung man who was lost during the war.
Date: January 2, 2004
Creator: Tholung, Daniel
Partner: UNT College of Information

Discussion about Umpii Doon K’Kaat

Description: Bunghon Suungnem of Leingangching, Shangwar of Khuibung, Beshot Tholung of Thamlapokpi, and unknown women discuss Tlingkhup, is the son Sinthling Arkoi Chapa named Rengpu is the young guy belonging to a Sankhil clan who shot at the Umpii Doon. Today when one takes a name for strength they take the name of Rengtlung. They also discuss the sound of the bird called “Vakpa ke Kuk” and how it originated. A lady shares about her grandparents who were caught by the Kukis they are still there.
Date: January 2, 2004
Creator: Tholung, Daniel
Partner: UNT College of Information