AMRNodeElliptic user guide: On irregular problem domains (open access)

AMRNodeElliptic user guide: On irregular problem domains

This document describes an extension to the Chombo package [CGL+00] for solving elliptic equations using adaptive mesh refinement on multiple levels with node-centered data on non-rectangular domains. See the AMRNodeElliptic design document [McC02] for a description of the algorithms used. Chapter 2 describes the subroutines that the user must supply to describe the geometry and the operator. Chapter 3 describes the class NodeFArrayBox and functions that use this class to manipulate node-centered data. Interfaces for elliptic equation solvers are described in chapter 4. Some internal classes of the solvers are described in chapter 5. User interfaces for physical boundary conditions are described in chapter 6. The AMRNodeElliptic package requires that Chombo library be installed. See chapter 1 of the Chombo design document [CGL+00] for requirements and installation of Chombo.
Date: April 15, 2003
Creator: McCorquodale, Peter
Object Type: Report
System: The UNT Digital Library
AMRNodeElliptic user guide: On rectangular problem domains (open access)

AMRNodeElliptic user guide: On rectangular problem domains

This document describes an extension to the Chombo package [CGL+00] for solving elliptic equations using adaptive mesh refinement on multiple levels with node-centered data. See the AMRNodeElliptic design document [McC02] for a description of the algorithms used. Chapter 2 describes the class NodeFArrayBox and functions that use this class to manipulate node-centered data. Interfaces for elliptic equation solvers are described in chapter 3. Some internal classes of the solvers are described in chapter 4. User interfaces for physical boundary conditions are described in chapter 5. The AMRNodeElliptic package requires that Chombo library be installed. See chapter 1 of the Chombo design document [CGL+00] for requirements and installation of Chombo.
Date: April 15, 2003
Creator: McCorquodale, Peter
Object Type: Report
System: The UNT Digital Library
CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION (open access)

CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried …
Date: April 15, 2003
Creator: V.J. Fabry, Ph.D.
Object Type: Report
System: The UNT Digital Library
Data Package for Calendar Year 2002 RCRA Groundwater Monitoring Wells at Single-Shell Tank Waste Management Area TX-TY (open access)

Data Package for Calendar Year 2002 RCRA Groundwater Monitoring Wells at Single-Shell Tank Waste Management Area TX-TY

Two new RCRA groundwater monitoring wells were installed at the single-shell tank farm at Waste Management Area TX-TY in October and November 2002. This document provides the information on drilling and construction of these wells. Two new Resource Conservation and Recovery Act (RCRA) groundwater monitoring wells were installed at the single-shell tank farm Waste Management Area (WMA) TX-TY in October and November 2002 in fulfillment of Tri-Party Agreement (Ecology et al. 1998) Milestone M-24-00N. The well names are 299-W14-19 and 299-W15-44; the corresponding well numbers are C3957 and C3956, respectively. Well 299-W14-19 is located east of the central part of the TX Tank Farm and is a downgradient well filling a gap in the monitoring network between wells 299-W14-14 and 299-W14-6. Well 299-W15-44 is located at the southwest corner of the TX Tank Farm in an area where groundwater flow has been artificially altered toward the southwest by the 200-ZP-1 Operable Unit pump-and-treat system. The well is in the cone of depression of the 200-ZP-1 extraction wells and is downgradient of WMA TX-TY. The locations of all wells in the WMA TX-TY monitoring network are shown on Figure 1. The original assessment monitoring plan for WMA TX-TY was issued in …
Date: April 15, 2003
Creator: Horton, Duane G.
Object Type: Report
System: The UNT Digital Library
Density Prediction of Uranium-6 Niobium Ingots (open access)

Density Prediction of Uranium-6 Niobium Ingots

The densities of uranium-6 niobium (U-Nb) alloys have been compiled from a variety of literature sources such as Y-12 and Rocky Flats datasheets. We also took advantage of the 42 well-pedigreed, homogeneous baseline U-Nb alloys produced under the Enhanced Surveillance Program for density measurements. Even though U-Nb alloys undergo two-phase transitions as the Nb content varies from 0 wt. % to 8 wt %, the theoretical and measured densities vary linearly with Nb content. Therefore, the effect of Nb content on the density was modeled with a linear regression. From this linear regression, a homogeneous ingot of U-6 wt.% Nb would have a density of 17.382 {+-} 0.040 g/cc (95% CI). However, ingots produced at Y-12 are not homogeneous with respect to the Nb content. Therefore, using the 95% confidence intervals, the density of a Y-12 produced ingot would vary from 17.310 {+-} 0.043 g/cc at the center to 17.432 {+-} 0.039 g/cc at the edge. Ingots with larger Nb inhomogeneities will also have larger variances in the density.
Date: April 15, 2003
Creator: Teter, D. F.; Tubesing, P. K.; Thoma, D. J. & Peterson. E. J.
Object Type: Report
System: The UNT Digital Library
DEVELOPING STATE POLICIES SUPPORTIVE OF BIOENERGY DEVELOPMENT (open access)

DEVELOPING STATE POLICIES SUPPORTIVE OF BIOENERGY DEVELOPMENT

Working within the context of the Southern States Biobased Alliance (SSBA) and with officials in each state, the Southern States Energy Board (SSEB) is identifying bioenergy-related policies and programs within each state to determine their impact on the development, deployment or use of bioenergy. In addition, SSEB will determine which policies have impacted industry's efforts to develop, deploy or use biobased technologies or products. As a result, SSEB will work with the Southern States Biobased Alliance to determine how policy changes might address any negative impacts or enhance positive impacts.
Date: April 15, 2003
Creator: Baskin, Kathryn
Object Type: Report
System: The UNT Digital Library
ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION (open access)

ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/2/2003 through 4/01/2003. As indicated in the list of accomplishments below we are progressing with long-term model scale bioreactor tests and are completing final preparations for pilot scale bioreactor testing. Specific results and accomplishments for the first quarter of 2003 are included.
Date: April 15, 2003
Creator: Kremer, Dr. Gregory; Bayless, David J.; Vis, Dr. Morgan; Prudich, Dr. Michael; Cooksey, Dr. Keith & Muhs, Dr. Jeff
Object Type: Report
System: The UNT Digital Library
Evaluation of Roof Bolting Requirements Based on In-Mine Bolter Drilling Progress Report (open access)

Evaluation of Roof Bolting Requirements Based on In-Mine Bolter Drilling Progress Report

Roof bolting is the most popular method for underground openings in the mining industry, especially in the bedded deposits such as coal, potash, salt etc. In fact, all U.S. underground coal mine entries are roof-bolted as required by law. However, roof falls still occur frequently in the roof bolted entries. The two possible reasons are: the lack of knowledge of and technology to detect the roof geological conditions in advance of mining, and lack of roof bolting design criteria for modern roof bolting systems. This research is to develop a method for predicting the roof geology and stability condition in real time during roof bolting operation. Based on such information, roof bolting design criteria for modern roof bolting systems will be developed for implementation in real time. More field tests have been performed. A trendline analysis method has been developed. This method would improve the accuracy in detecting the locations of fractures and in determining the rock strength.
Date: April 15, 2003
Creator: Peng, Syd S.
Object Type: Report
System: The UNT Digital Library
Flow Instabilities During Injection of CO2 into SalineAquifers (open access)

Flow Instabilities During Injection of CO2 into SalineAquifers

Injection of carbon dioxide (CO{sub 2}) into saline aquifers has been proposed as a means to reduce greenhouse gas emissions (geological carbon sequestration). The injection process can be classified as immiscible displacement of an aqueous phase by a less dense and less viscous gas phase. Under disposal conditions (supercritical CO{sub 2}) the viscosity of carbon dioxide can be less than the viscosity of the aqueous phase by a factor of 15. Because of the lower viscosity, the CO{sub 2} displacement front will have a tendency towards instability so that waves or rounded lobes of saturation may appear and grow into fingers that lead to enhanced dissolution, bypassing, and possibly poor sweep efficiency. This paper presents an analysis, through high-resolution numerical simulations, of the onset of instabilities (viscous fingering) during injection of CO{sub 2} into saline aquifers. We explore the influence of viscosity ratio, relative permeability functions, and capillary pressure on finger growth and spacing. In addition, we address the issues of finger triggering, convergence under grid refinement and boundary condition effects. Simulations were carried out on scalar machines, and on an IBM RS/6000 SP (a distributed-memory parallel computer with 6080 processors) with a parallelized version of TOUGH2.
Date: April 15, 2003
Creator: Garcia, Julio E. & Pruess, Karsten
Object Type: Article
System: The UNT Digital Library
G-Plus report to Owens Corning-thermal conductivity Measurements of Fiberglass (open access)

G-Plus report to Owens Corning-thermal conductivity Measurements of Fiberglass

Fiberglass made by Owens Corning is being used in noise reduction of automobile exhaust system. Specifically, the glass fibers are packed inside the muffler to achieve the desired acoustic effect. A secondary benefit of the fibers is to serve as a thermal insulation. Because of this insulating property, the glass fibers can serve to reduce the temperature of the muffler shell. This in turn reduces the need for heat shields around mufflers and reduces the amount of exterior temperature accelerated corrosion of the muffler shell, especially in the winter ''salt belts'' where large amounts of salt are placed on highways to minimize the safety impact of snow and ice. In addition, for some applications the use of the fiberglass could allow the use of lighter weight carbon based polymer composite materials in place of steel for muffler shells. However, in order to properly design exhaust systems without heat shields or to take advantage of new materials, the thermal conductivity of the fiberglass material at operating temperatures (for some applications above 750 C) must be known. We selected two types of Owens Corning glass fibers, 17 {micro}m and 24 {micro}m in diameter, for this study. There are some room temperature thermal …
Date: April 15, 2003
Creator: Wang, H
Object Type: Report
System: The UNT Digital Library
Observation of THz emission from a laser-plasma accelerated electron bunch crossing a plasma-vacuum boundary (open access)

Observation of THz emission from a laser-plasma accelerated electron bunch crossing a plasma-vacuum boundary

Coherent radiation in the 0.3 - 3 THz range has been generated from femto second electron bunches at a plasma-vacuum boundary via transition radiation. The bunches produced by a laser-plasma accelerator contained 1.5 nC of charge. The THz energy per pulse within a limited 30 mrad collection angle was 3.5 nJ and scaled quadratically with bunch charge, consistent with coherent emission. Modeling indicates that this broadband source produces about 0.3 muJ per pulse within a 100 mrad angle, and that increasing the transverse plasma size and electron beam energy could provide more than 100 muj/pulse.
Date: April 15, 2003
Creator: Leemans, W. P.; Geddes, C. G. R.; Faure, J.; Toth, Cs.; van Tilborg, J.; Schroeder, C. B. et al.
Object Type: Article
System: The UNT Digital Library
Prediction of Failure Due to Thermal Aging, Corrosion and Environmental Fracture in Amorphous and Titanium Alloys (open access)

Prediction of Failure Due to Thermal Aging, Corrosion and Environmental Fracture in Amorphous and Titanium Alloys

DARPA is exploring a number of advanced materials for military applications, including amorphous metals and titanium-based alloys. Equipment made from these materials can undergo degradation due to thermal aging, uniform corrosion, pitting, crevice corrosion, denting, stress corrosion cracking, corrosion fatigue, hydrogen induced cracking and microbial influenced corrosion. Amorphous alloys have exceptional resistance to corrosion, due in part to the absence of grain boundaries, but can undergo crystallization and other phase instabilities during heating and welding. Titanium alloys are extremely corrosion resistant due to the formation of a tenacious passive film of titanium oxide, but is prone to hydrogen absorption in crevices, and hydrogen induced cracking after hydrogen absorption. Accurate predictions of equipment reliability, necessary for strategic planning, requires integrated models that account for all relevant modes of attack, and that can make probabilistic predictions. Once developed, model parameters must be determined experimentally, and the validity of models must be established through careful laboratory and field tests. Such validation testing requires state-of-the-art surface analytical techniques, as well as electrochemical and fracture mechanics tests. The interaction between those processes that perturb the local environment on a surface and those that alter metallurgical condition must be integrated in predictive models. The material and …
Date: April 15, 2003
Creator: Farmer, J C
Object Type: Report
System: The UNT Digital Library
Risk Reduction With a Fuzzy Expert Exploration Tool (open access)

Risk Reduction With a Fuzzy Expert Exploration Tool

Incomplete or sparse information on types of data such as geologic or formation characteristics introduces a high level of risk for oil exploration and development projects. ''Expert'' systems developed and used in several disciplines and industries have demonstrated beneficial results. A state-of-the-art exploration ''expert'' tool, relying on a computerized database and computer maps generated by neural networks, is being developed through the use of ''fuzzy'' logic, a relatively new mathematical treatment of imprecise or non-explicit parameters and values. Oil prospecting risk can be reduced with the use of a properly developed and validated ''Fuzzy Expert Exploration (FEE) Tool.'' This FEE Tool can be beneficial in many regions of the U.S. by enabling risk reduction in oil and gas prospecting as well as decreased prospecting and development costs. In the 1998-1999 oil industry environment, many smaller exploration companies lacked the resources of a pool of expert exploration personnel. Downsizing, low oil prices, and scarcity of exploration funds have also affected larger companies, and will, with time, affect the end users of oil industry products in the U.S. as reserves are depleted. The pool of experts is much reduced today. The FEE Tool will benefit a diverse group in the U.S., leading …
Date: April 15, 2003
Creator: Balch, Robert
Object Type: Report
System: The UNT Digital Library
Scientific Basis for Monitored Natural Attenuation and Enhanced Passive Remediation for Chlorinated Solvents - DOE Alternative Project for Technology Acceleration Implementation Plan (open access)

Scientific Basis for Monitored Natural Attenuation and Enhanced Passive Remediation for Chlorinated Solvents - DOE Alternative Project for Technology Acceleration Implementation Plan

The overall Monitored Natural Attenuation and Enhanced Passive Remediation (MNA/EPR) Technology Alternative Project is narrowly focused, providing the scientific and policy support to facilitate implementing appropriate passive cleanup and cost effective monitoring strategies leading to responsible completion of active remediation activities at high risk DOE waste sites. MNA/EPR describe natural processes that mitigate exposure and risk and that are self-sustaining once implemented or require minimal adjustments to maintain functionality. The overall MNA/EPR project effort will be performed as a collaboration between DOE science and operations organizations at the target sites along with regulatory agencies, stakeholders, industry, and universities, as identified in the approved Alternative Project Plan. This plan describes the project initiation activities, individual roles and responsibilities, milestones, and budget for the project. A primary product of this project will be a collaboratively developed MNA/EPR protocol that will facilitate widespread use and acceptance. This technical protocol will be developed in collaboration with regulator agencies as input for regulation updates and guidance documents, as appropriate. This plan describes the project initiation activities, individual roles and responsibilities, milestones, and budget for the project.
Date: April 15, 2003
Creator: Vangelas, K.
Object Type: Report
System: The UNT Digital Library
Specimen charging on thin films with one conducting layer:Discussion of physical principles (open access)

Specimen charging on thin films with one conducting layer:Discussion of physical principles

While the most familiar consequences of specimen charging in transmission electron microscopy can be eliminated by evaporating a thin conducting film (such as a carbon film) onto an insulating specimen, or by preparing samples directly on such a conducting film to begin with, a more subtle charging effect still remains. We argue here that specimen charging is in this case likely to produce a dipole sheet rather than a layer of positive charge at the surface of the specimen. A simple model of the factors that control the kinetics of specimen charging, and its neutralization, is discussed as a guide for experiments that attempt to minimize the amount of specimen charging. Believable estimates of the electrostatic forces and the electron optical disturbances that are likely to occur suggest that specimen bending and warping may have the biggest impact on degrading the image quality at high resolution. Electron optical effects are likely to be negligible except in the case of a specimen that is tilted to high angle. A model is proposed to explain how both the mechanical and electron-optical effects of forming a dipole layer would have much greater impact on the image resolution in a direction perpendicular to the …
Date: April 15, 2003
Creator: Glaeser, Robert M. & Downing, Kenneth H.
Object Type: Article
System: The UNT Digital Library
Spectroscopic and Microscopic Characterization of Contaminant Uptake and Retention by Carbonates in the Soil and Vadose Zone (open access)

Spectroscopic and Microscopic Characterization of Contaminant Uptake and Retention by Carbonates in the Soil and Vadose Zone

The research focus of this previous EMSP grant was assessment of the role that carbonate minerals play in the uptake and sequestration of metal and radionuclide contaminants in soils and the vadose zone for conditions relevant to the Hanford Site and other sites in the DOE Complex. The project was a collaboration among researchers at SUNY-Stony Brook and EMSL/PNNL. Carbonates, particularly calcite, are present in the Hanford subsurface as grain coatings, disseminated particles, and dense caliche layers. Calcite is also predicted to be forming beneath leaking tanks. A range of metal and radionuclide species that pose risks at Hanford and othe DOE istes were considered, including u(VI), Cr(CV), Cs, Pb(II), and selected lanthanides (as models for trivalent actinides). Batch sorption and co-precipitation experiments of these metals with pre-equilibrated calcite and selected uptake experiments on natural caliche formed the basis to determine the mechanisms of metal/radionuclide binding and to assess the effect on the stability of the sorbed species and the potential for remobilization. Our results provide ne information that can benefit DOE clean-up methodology and potentially provide new approaches for uptake of selected heavy metals
Date: April 15, 2003
Creator: Reeder, Richard J.; Fisher, Nicholas S.; Hess, Wayne P. & Beck, Kenneth M.
Object Type: Report
System: The UNT Digital Library
SYSTEM FOR DETECTION AND CONTROL OF DEPOSITION IN KRAFT CHEMICAL RECOVERY BOILERS AND MONITORING GLASS FURNACES (open access)

SYSTEM FOR DETECTION AND CONTROL OF DEPOSITION IN KRAFT CHEMICAL RECOVERY BOILERS AND MONITORING GLASS FURNACES

Combustion Specialists, Inc. has just completed a project designed to develop the capability to monitor and control the formation of deposits on the outside of boiler tubes inside an operating kraft recovery furnace. This project, which was carried out in the period from April 1, 2001 to January 31, 2003, was funded by the Department of Energy's Inventions and Innovations program. The primary objectives of the project included the development and demonstration of the ability to produce clear images of deposits throughout the convective sections of operating recovery boilers using newly developed infrared imaging technology, to demonstrate the automated detection and quantification of these deposits using custom designed image processing software developed as part of the project, and to demonstrate the feasibility of all technical elements required for a commercial ''smart'' sootblowing control system based on direct feedback from automated imaging of deposits in real-time. All of the individual tasks have been completed and all objectives have been substantially achieved. Imaging of deposits throughout the convective sections of several recovery boilers has been demonstrated, a design for a combined sootblower/deposit inspection probe has been developed and a detailed heat transfer analysis carried out to demonstrate the feasibility of this design, …
Date: April 15, 2003
Creator: Ariessohn, Dr. Peter
Object Type: Report
System: The UNT Digital Library
Two-dimensional computational fluid dynamics and conduction simulations of heat transfer in window frames with internal cavities - Part 1: Cavities only (open access)

Two-dimensional computational fluid dynamics and conduction simulations of heat transfer in window frames with internal cavities - Part 1: Cavities only

Accurately analyzing heat transfer in window frame cavities is essential for developing and characterizing the performance of highly insulating window products. Window frame thermal performance strongly influences overall product thermal performance because framing materials generally perform much more poorly than glazing materials. This paper uses Computational Fluid Dynamics (CFD) modeling to assess the accuracy of the simplified frame cavity conduction/convection models presented in ISO 15099 and used in software for rating and labeling window products. (We do not address radiation heat-transfer effects.) We examine three representative complex cavity cross-section profiles with varying dimensions and aspect ratios. Our results support the ISO 15099 rule that complex cavities with small throats should be subdivided; however, our data suggest that cavities with throats smaller than seven millimeters (mm) should be subdivided, in contrast to the ISO 15099 rule, which places the break point at five mm. The agreement between CFD modeling results and the results of the simplified models is moderate. The differences in results may be a result of the underlying ISO correlations being based on studies where cavity height/length (H/L) aspect ratios were smaller than 0.5 and greater than five (with linear interpolation assumed in between). The results presented here are …
Date: April 15, 2003
Creator: Gustavsen, Arild; Kohler, Christian; Arasteh, Dariush & Curcija, Dragan
Object Type: Article
System: The UNT Digital Library
Unreviewed Disposal Question Evaluation: Backfill Soil Compaction Requirements (open access)

Unreviewed Disposal Question Evaluation: Backfill Soil Compaction Requirements

One intent of DOE Order 435.1 (USDOE 1999a ), as expressed in the performance assessment/composite analysis guidance (USDOE 1999c), is to ensure that proposed changes in wasteforms, containers, radionuclide inventories, facility design, and operations are reviewed to ensure that the assumptions, results, and conclusions of the DOE approved performance assessment (PA) (WSRC 2000), and composite analysis (CA) (WSRC 1997), as well as any Special analyses (SA) that might have been performed, remain valid (i.e., that the proposed change is bounded by the PA and CA) and the changes are within the bounds of the Disposal Authorization Statement (USDOE 1999b). The goal is to provide flexibility in day-to-day operation and to require those issues with a significant impact on the PA's conclusions, and therefore the projected compliance with performance objectives/measures, to be identified and brought to the proper level of attention. It should be noted that the term performance measure is used t o describe site specific adaptations of the DOE Order 435.1 Performance Objectives and requirements (e.g., performance measures such as applying drinking water standards to the groundwater impacts assessment). The intent of this document is to provide an evaluation of the issues identified within Problem Identification Report (PIR) number …
Date: April 15, 2003
Creator: Phifer, M. A.
Object Type: Report
System: The UNT Digital Library
UTILIZATION OF PHOSWICH DETECTORS FOR SIMULTANEOUS, MULTIPLE RADIATION DETECTION (open access)

UTILIZATION OF PHOSWICH DETECTORS FOR SIMULTANEOUS, MULTIPLE RADIATION DETECTION

A phoswich radiation detector is comprised of a phosphor sandwich in which several different phosphors are viewed by a common photomultiplier. By selecting the appropriate phosphors, this system can be used to simultaneously measure multiple radiation types (alpha, beta, gamma and/or neutron) with a single detector. Differentiation between the signals from the different phosphors is accomplished using digital pulse shape discrimination techniques. This method has been shown to result in accurate discrimination with highly reliable and versatile digital systems. This system also requires minimal component count (i.e. only the detector and a computer for signal processing). A variety of detectors of this type have been built and tested including: (1) a triple phoswich system for alpha/beta/gamma swipe counting, (2) two well-type detectors for measuring low levels of low energy photons in the presence of a high energy background, (3) a large area detector for measuring beta contamination in the presence of a photon background, (4) another large area detector for measuring low energy photons from radioactive elements such as uranium in the presence of a photon background. An annular geometry, triple phoswich system optimized for measuring alpha/beta/gamma radiation in liquid waste processing streams is currently being designed.
Date: April 15, 2003
Creator: Miller, William H. & Leon, Manuel Diaz de
Object Type: Article
System: The UNT Digital Library
Vadose Zone Transport Field Study FY 2003 Test Plan (open access)

Vadose Zone Transport Field Study FY 2003 Test Plan

Conceptual models have been identified as one of the sources of uncertainty in the interpretation and prediction of contaminant migration through the vadose zone at Hanford. Current conceptual models are limited partly because they often do not account for the random heterogeneity that occurs under the extremes of very nonlinear flow behavior typical of the Hanford vadose zone. Over the last two years significant progress has been made in characterizing physical heterogeneity and in the development of techniques for incorporating this heterogeneity into predictive and inverse models for field-scale subsurface flow. One of the remaining pieces of the puzzle is the impact of heterogeneity on the distribution of reactive contaminants. Reactive transport occurs over a wide range of spatial and temporal scales. However, the manner in which the various subsurface physical and chemical processes interact to influence transport is not very well understood. Hydrogeologic characterization and model analysis, however, have traditionally focused on measurement of physical properties and predicting the effects of variability in these properties on flow and transport. As a result, the role of geochemical heterogeneity on solute transport has remained largely unexplored. This project will use a combination of geophysical and soil physics techniques to investigate the …
Date: April 15, 2003
Creator: Ward, Anderson L. & Gee, Glendon W.
Object Type: Report
System: The UNT Digital Library
Wetting and strength issues at Al/alpha-alumina interfaces (open access)

Wetting and strength issues at Al/alpha-alumina interfaces

The wetting behavior and strength at aluminum/alumina interfaces has been an active subject of research. Al/alumina applications include ceramic-metal composites and several applications for electronic industries. In this paper the interface strength and microstructure of Al/alpha-alumina was investigated. We discovered that in a solid-state joining, the strength of the joint increases with increasing joining temperature. In a liquid-state joining, the strength of the joint gradually decreases due to the formation of unbonded areas. The strength, sigma sub b, is expressed by the following equation as a function of unbonded area, A: sigma sub b = 2.22 A + 143 (70 percent {le} A {le} 100 percent). The highest strength reached 400 MPa when the interface was formed at around the melting temperature of aluminum. An aluminum layer close to the interface became a single crystal when it was bonded to a sapphire. The following crystallographic orientation relationship is established: (1{bar 1}1){sub Al}//(001){sub {alpha}}-Al{sub 2} O{sub 3}, (110){sub Al}//<100>{sub {alpha}}-Al{sub 2}O{sub 3}. Amorphous alumina islands were formed at the interface. In the amorphous alumina, gamma-alumina nanocrystals grew from the sapphire, with the same orientation relationship to sapphire as above.
Date: April 15, 2003
Creator: Saiz, Eduardo; Tomsia, Antoni P. & Suganuma, Katsuaki
Object Type: Article
System: The UNT Digital Library