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Modeling and Simulation of Long-Term Performance of Near-Surface Barriers (open access)

Modeling and Simulation of Long-Term Performance of Near-Surface Barriers

Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone’s back yard); most of these storage sites include a surface barrier (cap) to prevent migration of the waste due to infiltration of surface water. The design lifespan for such barriers ranges from 30 to 1000 years, depending on hazard and regulations. In light of historical performance, society needs a better basis for predicting barrier performance over long time periods and tools for optimizing maintenance of barriers while in service. We believe that, as in other industries, better understanding of the dynamics of barrier system degradation will enable improved barriers (cheaper, longer-lived, simpler, easier to maintain) and improved maintenance. We are focusing our research on earthen caps, especially those with evapo-transpiration and capillary breaks. Typical cap assessments treat the barrier’s structure as static prior to some defined lifetime. Environmental boundary conditions such as precipitation and temperature are treated as time dependent. However, other key elements …
Date: February 1, 2003
Creator: Piet, Steven James; Jacobson, Jacob Jordan; Soto, Rafael; Martian, Pete & Martineau, Richard Charles
System: The UNT Digital Library
Making Sustainable Decisions Using the KONVERGENCE Framework (open access)

Making Sustainable Decisions Using the KONVERGENCE Framework

Hundreds of contaminated facilities and sites must be cleaned up. “Cleanup” includes decommissioning, environmental restoration, and waste management. Cleanup can be complex, expensive, risky, and time-consuming. Decisions are often controversial, can stall or be blocked, and are sometimes re-done - some before implementation, some decades later. Making and keeping decisions with long time horizons involves special difficulties and requires new approaches, including: • New ways (mental model) to analyze and visualize the problem, • Awareness of the option to shift strategy or reframe from a single decision to an adaptable network of decisions, and • Improved tactical processes that account for several challenges. These include the following: • Stakeholder values are a more fundamental basis for decision making and keeping than “meeting regulations.” • Late-entry players and future generations will question decisions. • People may resist making “irreversible” decisions. • People need “compelling reasons” to take action in the face of uncertainties. Our project goal is to make cleanup decisions easier to make, implement, keep, and sustain. By sustainability, we mean decisions that work better over the entire time-period—from when a decision is made, through implementation, to its end point. That is, alternatives that can be kept “as is” or …
Date: February 1, 2003
Creator: Piet, Steven James; Gibson, Patrick Lavern; Joe, Jeffrey Clark; Kerr, Thomas A; Nitschke, Robert Leon & Dakins, Maxine Ellen
System: The UNT Digital Library
Equilibrium in heavy ion collisions (open access)

Equilibrium in heavy ion collisions

We discuss the question of equilibration in heavy ion collisions and how it can be addressed in experiment.
Date: February 1, 2003
Creator: Koch, Volker & Majumder, Abhijit
System: The UNT Digital Library
Testing, Modeling, and Monitoring to Enable Simpler, Cheaper, Longer-Lived Surface Caps (open access)

Testing, Modeling, and Monitoring to Enable Simpler, Cheaper, Longer-Lived Surface Caps

Society has and will continue to generate hazardous wastes whose risks must be managed. For exceptionally toxic, long-lived, and feared waste, the solution is deep burial, e.g., deep geological disposal at Yucca Mtn. For some waste, recycle or destruction/treatment is possible. The alternative for other wastes is storage at or near the ground level (in someone’s back yard); most of these storage sites include a surface barrier (cap) to prevent downward water migration. Some of the hazards will persist indefinitely. As society and regulators have demanded additional proof that caps are robust against more threats and for longer time periods, the caps have become increasingly complex and expensive. As in other industries, increased complexity will eventually increase the difficulty in estimating performance, in monitoring system/component performance, and in repairing or upgrading barriers as risks are managed. An approach leading to simpler, less expensive, longer-lived, more manageable caps is needed. Our project, which started in April 2002, aims to catalyze a Barrier Improvement Cycle (iterative learning and application) and thus enable Remediation System Performance Management (doing the right maintenance neither too early nor too late). The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions, …
Date: February 1, 2003
Creator: Piet, Steven James; Breckenridge, Robert Paul & Burns, Douglas Edward
System: The UNT Digital Library
Exciton dynamicsstudied via internal THz transitions (open access)

Exciton dynamicsstudied via internal THz transitions

We employ a novel, ultrafast terahertz probe to investigatethe dynamical interplay of optically-induced excitons and unboundelectron-hole pairs in GaAs quantum wells. Resonant creation ofheavy-hole excitons induces a new low-energy oscillator linked totransitions between the internal exciton degrees of freedom. The timeresolved terahertz optical conductivity is found to be a probe wellsuited for studies of fundamental processes such as formation, relaxationand ionization of excitons.
Date: February 26, 2003
Creator: Kaindl, R. A.; Hagele, D.; Carnahan, M. A.; Lovenich, R. & Chemla, D. S.
System: The UNT Digital Library
'Mini'-Roadmapping - Ensuring Timely Sites' Cleanup / Closure by Resolving Science and Technology Issues (open access)

'Mini'-Roadmapping - Ensuring Timely Sites' Cleanup / Closure by Resolving Science and Technology Issues

Roadmapping is a powerful tool to manage technical risks and opportunities associated with complex problems. Roadmapping identifies technical capabilities required for both project- and program-level efforts and provides the basis for plans that ensure the necessary enabling activities will be done when needed. Roadmapping reveals where to focus further development of the path forward by evaluating uncertainties for levels of complexity, impacts, and/or the potential for large payback. Roadmaps can be customized to the application, a “graded approach” if you will. Some roadmaps are less detailed. We have called these less detailed, top-level roadmaps “mini-roadmaps”. These miniroadmaps are created to tie the needed enablers (e.g., technologies, decisions, etc.) to the functions. If it is found during the mini-roadmapping that areas of significant risk exist, then those can be roadmapped further to a lower level of detail. Otherwise, the mini-roadmap may be sufficient to manage the project / program risk. Applying a graded approach to the roadmapping can help keep the costs down. Experience has indicated that it is best to do mini-roadmapping first and then evaluate the risky areas to determine whether to further evaluate those areas. Roadmapping can be especially useful for programs / projects that have participants from …
Date: February 1, 2003
Creator: Luke, Dale & Murphy, James
System: The UNT Digital Library
A Source-to-Source Architecture for User-Defined Optimizations (open access)

A Source-to-Source Architecture for User-Defined Optimizations

The performance of object-oriented applications often suffers from the inefficient use of high-level abstractions provided by underlying libraries. Since these library abstractions are user-defined and not part of the programming language itself only limited information on their high-level semantics can be leveraged through program analysis by the compiler and thus most often no appropriate high-level optimizations are performed. In this paper we outline an approach based on source-to-source transformation to allow users to define optimizations which are not performed by the compiler they use. These techniques are intended to be as easy and intuitive as possible for potential users; i.e. for designers of object-oriented libraries, people most often only with basic compiler expertise.
Date: February 6, 2003
Creator: Schordan, M & Quinlan, D
System: The UNT Digital Library
Inversion of Synthetic Aperture Radar Interferograms for Sources of Production-Related Subsidence at the Dixie Valley Geothermal Field (open access)

Inversion of Synthetic Aperture Radar Interferograms for Sources of Production-Related Subsidence at the Dixie Valley Geothermal Field

We used synthetic aperture radar interferograms to image ground subsidence that occurred over the Dixie Valley geothermal field during different time intervals between 1992 and 1997. Linear elastic inversion of the subsidence that occurred between April, 1996 and March, 1997 revealed that the dominant sources of deformation during this time period were large changes in fluid volumes at shallow depths within the valley fill above the reservoir. The distributions of subsidence and subsurface volume change support a model in which reduction in pressure and volume of hot water discharging into the valley fill from localized upflow along the Stillwater range frontal fault is caused by drawdown within the upflow zone resulting from geothermal production. Our results also suggest that an additional source of fluid volume reduction in the shallow valley fill might be similar drawdown within piedmont fault zones. Shallow groundwater flow in the vicinity of the field appears to be controlled on the NW by a mapped fault and to the SW by a lineament of as yet unknown origin.
Date: February 7, 2003
Creator: Foxall, W & Vasco, D
System: The UNT Digital Library
12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Summary Discussion Sessions (open access)

12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Summary Discussion Sessions

This report is a summary of the discussion sessions of the 12th Workshop on Crystalline Silicon Solar Cells and Processes. The theme of the workshop was"Fundamental R&D in c-Si: Enabling Progress in Solar-Electric Technology." This theme was chosen to reflect a concern that the current expansion in the PV energy production may redirect basic research efforts to production-oriented issues. The PV industry is installing added production capacity and new production lines that include the latest technologies. Once the technologies are selected, it is difficult to make changes. Consequently, a large expansion can stagnate the technologies and diminish interest in fundamental research. To prevent the fundamental R&D program from being overwhelmed by the desire to address immediate engineering issues, there is a need to establish topics of fundamental nature that can be pursued by the universities and the research institutions. Hence, one of the objectives of the workshop was to identify such areas for fundamental research.
Date: February 1, 2003
Creator: Sopori, B.; Swanson, D.; Sinton, R. & Tan, T.
System: The UNT Digital Library
Out-of-Core Compression and Decompression of Large n-Dimensional Scalar Fields (open access)

Out-of-Core Compression and Decompression of Large n-Dimensional Scalar Fields

We present a simple method for compressing very large and regularly sampled scalar fields. Our method is particularly attractive when the entire data set does not fit in memory and when the sampling rate is high relative to the feature size of the scalar field in all dimensions. Although we report results for R{sup 3} and R{sup 4} data sets, the proposed approach may be applied to higher dimensions. The method is based on the new Lorenzo predictor, introduced here, which estimates the value of the scalar field at each sample from the values at processed neighbors. The predicted values are exact when the n-dimensional scalar field is an implicit polynomial of degree n-1. Surprisingly, when the residuals (differences between the actual and predicted values) are encoded using arithmetic coding, the proposed method often outperforms wavelet compression in an L{infinity} sense. The proposed approach may be used both for lossy and lossless compression and is well suited for out-of-core compression and decompression, because a trivial implementation, which sweeps through the data set reading it once, requires maintaining only a small buffer in core memory, whose size barely exceeds a single n-1 dimensional slice of the data.
Date: February 3, 2003
Creator: Ibarria, L.; Lindstrom, P.; Rossignac, J. & Szymczak, A.
System: The UNT Digital Library
Coulomb Energy, Vortices, and Confinement (open access)

Coulomb Energy, Vortices, and Confinement

d on 25 Feb 2003 (v1), last revised 10 Apr 2003 (this version, v2))We estimate the Coulomb energy of static quarks from a Monte Carlo calculation of the correlator of timelike link variables in Coulomb gauge. We find, in agreement with Cucchieri and Zwanziger, that this energy grows linearly with distance at large quark separations. The corresponding string tension, however, is several times greater than the accepted asymptotic string tension, indicating that a state containing only static sources, with no constituent gluons, is not the lowest energy flux tube state. The Coulomb energy is also measured on thermalized lattices with center vortices removed by the de Forcrand-D'Elia procedure. We find that when vortices are removed, the Coulomb string tension vanishes.
Date: February 25, 2003
Creator: Greensite, J. & Olejnik, S.
System: The UNT Digital Library
Explicit Supersymmetry Breaking on Boundaries of Warped Extra Dimensions (open access)

Explicit Supersymmetry Breaking on Boundaries of Warped Extra Dimensions

Explicit supersymmetry breaking is studied in higher dimensional theories by having boundaries respect only a subgroup of the bulk symmetry. If the boundary symmetry is the maximal subgroup allowed by the boundary conditions imposed on the fields, then the symmetry can be consistently gauged; otherwise gauging leads to an inconsistent theory. In a warped fifth dimension, an explicit breaking of all bulk supersymmetries by the boundaries is found to be inconsistent with gauging; unlike the case of flat 5D, complete supersymmetry breaking by boundary conditions is not consistent with supergravity. Despite this result, the low energy effective theory resulting from boundary supersymmetry breaking becomes consistent in the limit where gravity decouples, and such models are explored in the hope that some way of successfully incorporating gravity can be found. A warped constrained standard model leads to a theory with one Higgs boson with mass expected close to the experimental limit. A unified theory in a warped fifth dimension is studied with boundary breaking of both SU(5) gauge symmetry and supersymmetry. The usual supersymmetric predictionfor gauge coupling unification holds even though the TeV spectrum is quite unlike the MSSM. Such a theory may unify matter and Higgs in the same SU(5) …
Date: February 25, 2003
Creator: Hall, Lawrence J.; Nomura, Yasunori; Okui, Takemichi & Oliver, Steven J.
System: The UNT Digital Library
Contamination Control During In Situ Jet Grouting for Application in a Buried Transuranic Waste Site (open access)

Contamination Control During In Situ Jet Grouting for Application in a Buried Transuranic Waste Site

Engineers at the Idaho National Engineering and Environmental Laboratory (INEEL) have developed means of contamination control associated with jet-grouting buried radioactive mixed waste sites. Finely divided plutonium/americium oxide particulate can escape as the drill stem of the jet-grouting apparatus exits a waste deposit in preparation for insertion in another injection hole. In studying various options for controlling this potential contamination, engineers found that an elaborate glovebox/drill string shroud system prevents contaminants from spreading. Researchers jet-grouted a pit with nonradioactive tracers to simulate the movement of plutonium fines during an actual application. Data from the testing indicate that the grout immobilizes the tracer material by locking it up in particles large enough to resist aerosolization.
Date: February 1, 2003
Creator: Loomis, Guy George & Jessmore, James Joseph
System: The UNT Digital Library
Hydrogen Gas Generation Model for Fuel Based Remote Handled TRU Waste Stored at INEEL (open access)

Hydrogen Gas Generation Model for Fuel Based Remote Handled TRU Waste Stored at INEEL

The Idaho National Environmental and Engineering Laboratory (INEEL) initiated efforts to calculate the hydrogen gas generation in remote-handled transuranic (RH-TRU) containers in order to evaluate continued storage of unvented RH-TRU containers in vaults and to identify any potential problems during retrieval and aboveground storage. A computer code is developed to calculate the hydrogen concentration in the stored RH-TRU waste drums for known configuration, waste matrix, and radionuclide inventories as a function of time.
Date: February 1, 2003
Creator: Khericha, Soli T.; Bhatt, Rajiv N. & Liekhus, Kevin
System: The UNT Digital Library
Radiological Characterization Methodology of INEEL Stored RH-TRU Waste from ANL-E (open access)

Radiological Characterization Methodology of INEEL Stored RH-TRU Waste from ANL-E

An Acceptable Knowledge (AK)-based radiological characterization methodology is being developed for RH TRU waste generated from ANL-E hot cell operations performed on fuel elements irradiated in the EBR-II reactor. The methodology relies on AK for composition of the fresh fuel elements, their irradiation history, and the waste generation and collection processes. Radiological characterization of the waste involves the estimates of the quantities of significant fission products and transuranic isotopes in the waste. Methods based on reactor and physics principles are used to achieve these estimates. Because of the availability of AK and the robustness of the calculation methods, the AK-based characterization methodology offers a superior alternative to traditional waste assay techniques. Using this methodology, it is shown that the radiological parameters of a test batch of ANL-E waste is well within the proposed WIPP Waste Acceptance Criteria limits.
Date: February 1, 2003
Creator: Bhatt, Rajiv N.
System: The UNT Digital Library
Microtopography for Ductile Fracture Process Characterization - Part 1: Theory and Methodology (open access)

Microtopography for Ductile Fracture Process Characterization - Part 1: Theory and Methodology

The mechanics of ductile fracture is receiving increased focus as the importance of integrity of structures constructed from ductile materials is increasing. The non-linear, irreversible mechanical response of ductile materials makes generalized models of ductile cracking very difficult to develop. Therefore, research and testing of ductile fracture have taken a path leading to deformation-based parameters such as crack tip opening displacement (CTOD) and crack tip opening angle (CTOA). Constrained by conventional test techniques and instrumentation, physical values (e.g. crack mouth opening displacement, CMOD, and CTOA angles) are measured on the test specimen exterior and a single through-thickness "average" interior value is inferred. Because of three-dimensional issues such as crack curvature, constraint variation, and material inhomogeneity, inference of average parameter values may introduce errors. The microtopography methodology described here measures and maps three-dimensional fracture surfaces. The analyses of these data provide direct extraction of the parameters of interest at any location within the specimen interior, and at any desired increment of crack opening or extension. A single test specimen can provide all necessary information for the analysis of a particular material and geometry combination.
Date: February 1, 2003
Creator: Lloyd, Wilson Randolph
System: The UNT Digital Library
INEEL Lead Recycling in a Moratorium Environment (open access)

INEEL Lead Recycling in a Moratorium Environment

Since 1999, the Idaho National Engineering and Environmental Laboratory (INEEL) Lead Project successfully recycled over 700,000 pounds of excess INEEL lead to the private sector. On February 14, 2000, the Secretary of Energy, Bill Richardson, formalized the January 12, 2000, moratorium on recycling radioactive scrap metal that prevented the unrestricted release of recycled scrap metals to the private sector. This moratorium created significant problems for the INEEL lead recycling program and associated plans; however, through the cooperative efforts of the INEEL and Idaho State University as well as innovative planning and creative thinking the recycling issues were resolved. This collaboration has recycled over 160,000 pounds of excess lead to Idaho State University with a cost savings of over $.5M.
Date: February 1, 2003
Creator: Kooda, Kevin Evan; Mc Cray, Casey William; Aitken, Darren William & Galloway, Kelly
System: The UNT Digital Library
International Benchmarking and Conference on Women in Physics (open access)

International Benchmarking and Conference on Women in Physics

International benchmarking and conference on women in physics.
Date: February 5, 2003
Creator: Franz, Judy R.
System: The UNT Digital Library
Hard processes in hadron-nucleus and nucleus-nucleusinteractions (open access)

Hard processes in hadron-nucleus and nucleus-nucleusinteractions

None
Date: February 20, 2003
Creator: Satz (Ed.), H. & Wang (Ed.), X.-N.
System: The UNT Digital Library
Digging for Treasure - Unique Fate and Transport Study (open access)

Digging for Treasure - Unique Fate and Transport Study

In 1970, scientists at the National Bureau of Standards (NBS), now called the National Institute of Standards and Testing (NIST), implemented the most ambitious and comprehensive long-term corrosion behavior test for stainless steels in soil environments. This study had historic significance since the NBS 1957 landmark corrosion textbook compiled by Romanoff did not include stainless steels, and this 1970 research set forth to complete the missing body of knowledge. To conduct the test, NIST scientists buried 6,324 coupons from stainless steel types, specialty alloys, composite configurations, multiple material forms, and treatment conditions at six distinctive soil-type sites throughout the country. Between 1971 and 1980, four sets of coupons were removed from the six sites to establish 1-year, 2-year, 4-year, and 8- year corrosion rates data sets for different soil environments. The fifth and last set of coupons (approximately 200 at each site) remains undisturbed after 32-years, providing a virtual buried treasure of material and subsurface scientific data. These buried coupons and the surrounding soils represent an analog to the condition of buried waste and containers. Heretofore, the samples were simply pulled from the soil, measured for mass loss and the corrosion rate determined while the subsurface/fate and transport information was …
Date: February 1, 2003
Creator: Zirker, Larry; Adler-Flitton, M. K. & Beitel, G. A.
System: The UNT Digital Library
Real-Time Soils Characterization and Analyses Systems Used at Ohio Closure Sites (open access)

Real-Time Soils Characterization and Analyses Systems Used at Ohio Closure Sites

The Idaho National Engineering and Environmental Laboratory (INEEL) and the Fernald Environmental Management Project (FEMP) have jointly developed a field-deployed analytical system to rapidly scan, characterize, and analyze surface soil contamination. The basic system consists of a sodium iodide (NaI) spectrometer and global positioning system (GPS) hardware. This hardware can be deployed from any of four different platforms depending on the scope of the survey at hand. These platforms range from a large tractor-based unit (the RTRAK) used to survey large, relatively flat areas to a hand-pushed unit where maneuverability is important, to an excavator mounted system used to scan pits and trenches. The mobile sodium iodide concept was initially developed by the FEMP to provide pre-screening analyses for soils contaminated with uranium, thorium, and radium. The initial study is documented in the RTRAK Applicability Study and provides analyses supporting the field usage of the concept. The RTRAK system produced data that required several days of post-processing and analyses to generate an estimation of field coverage and activity levels. The INEEL has provided integrated engineering, computer hardware and software support to greatly streamline the data acquisition and analysis process to the point where real-time activity and coverage maps are available …
Date: February 1, 2003
Creator: Roybal, Lyle Gene; Carpenter, Michael Vance; Giles, John Robert; Hartwell, John Kelvin & Danahy, R.
System: The UNT Digital Library
Microtopography for Ductile Fracture Process Characterization - Part 2: Application for CTOA Analysis (open access)

Microtopography for Ductile Fracture Process Characterization - Part 2: Application for CTOA Analysis

The crack tip opening angle (CTOA) is seeing increased use to characterize fracture in so-called "low constraint" geometries, such as thin sheet aerospace structures and thin-walled pipes. With this increase in application comes a need to more fully understand and measure actual CTOA behavior. CTOA is a measure of the material response during ductile fracture, a "crack tip response function". In some range of crack extension following growth initiation, a constant value of CTOA is often assumed. However, many questions concerning the use of CTOA as a material response-characterizing parameter remain. For example, when is CTOA truly constant? What three-dimensional effects may be involved (even in thin sheet material)? What are the effects of crack tunneling on general CTOA behavior? How do laboratory specimen measurements of CTOA compare to actual structural behavior? Measurements of CTOA on the outer surface of test specimens reveal little about threedimensional effects in the specimen interior, and the actual measurements themselves are frequently difficult. The Idaho National Engineering and Environmental Laboratory (INEEL) use their microtopography system to collect data from the actual fracture surfaces following a test. Analyses of these data provide full three-dimensional CTOA distributions, at any amount of crack extension. The analysis is …
Date: February 1, 2003
Creator: Lloyd, Wilson Randolph & McClintock, F. A.
System: The UNT Digital Library
Finding Text Information in the Ocean of Electronic Documents (open access)

Finding Text Information in the Ocean of Electronic Documents

Information management in natural resources has become an overwhelming task. A massive amount of electronic documents and data is now available for creating informed decisions. The problem is finding the relevant information to support the decision-making process. Determining gaps in knowledge in order to propose new studies or to determine which proposals to fund for maximum potential is a time-consuming and difficult task. Additionally, available data stores are increasing in complexity; they now may include not only text and numerical data, but also images, sounds, and video recordings. Information visualization specialists at Pacific Northwest National Laboratory (PNNL) have software tools for exploring electronic data stores and for discovering and exploiting relationships within data sets. These provide capabilities for unstructured text explorations, the use of data signatures (a compact format for the essence of a set of scientific data) for visualization (Wong et al 2000), visualizations for multiple query results (Havre et al. 2001), and others (http://www.pnl.gov/infoviz ). We will focus on IN-SPIRE, a MS Windows vision of PNNL’s SPIRE (Spatial Paradigm for Information Retrieval and Exploration). IN-SPIRE was developed to assist information analysts find and discover information in huge masses of text documents.
Date: February 5, 2003
Creator: Medvick, Patricia A. & Calapristi, Augustin J.
System: The UNT Digital Library
An in situ transmission electron microscopy study of the thermalstability of near-surface microstructures induced by deep rolling andlaser-shock peening (open access)

An in situ transmission electron microscopy study of the thermalstability of near-surface microstructures induced by deep rolling andlaser-shock peening

Mechanical surface treatments are known to be effective at improving the fatigue resistance of metallic alloys at elevated temperatures ({approx}550-600 C), even though the near-surface compressive residual stress fields have been annealed out. We have investigated the thermal stability of near-surface microstructures induced by deep rolling and laser-shock peening in an austentic stainless steel (AISI 304) and a titanium alloy (Ti-6Al-4V) using in situ hot-stage transmission electron microscopy. It is found that the improvements in fatigue resistance at elevated temperature are related to the high-temperature stability of the work-hardened near-surface microstructure in each case.
Date: February 24, 2003
Creator: Altenberger, I.; Stach, E. A.; Liu, G. Y.; Nalla, R. K. & Ritchie, R. O.
System: The UNT Digital Library