In situ bioremediation for the Hanford carbon tetrachloride plume. Innovative technology summary report (open access)

In situ bioremediation for the Hanford carbon tetrachloride plume. Innovative technology summary report

The 200 Area at Hanford (also called the Central Plateau) contains approximately 817 waste sites, 44 facilities to be demolished, and billions of gallons of contaminated groundwater resulting from chemical processing plants and associated waste facilities (e.g., waste tanks). From 1955 to 1973, carbon tetrachloride, nitrate, and other materials were discharged to subsurface liquid waste disposal facilities in the 200 Area. As much as 600,000 kilograms of carbon tetrachloride may have entered the soil column and a portion of this has contaminated the underlying aquifer. In Situ Bioremediation for the Hanford Carbon Tetrachloride Plume (ISB), which is the term used in this report for an in situ treatment process using indigenous micro-organisms with a computer based Accelerated Bioremediation Design Tool (ABDT), remediates groundwater contaminated with volatile organic compounds (VOCs) and nitrates under anaerobic conditions. ISB involves the injection of nutrients into the groundwater and subsequent extraction and re-injection of the groundwater to provide nutrient distribution in the aquifer.
Date: April 1, 1999
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Developing the VirtualwindoW into a General Purpose Telepresence Interface (open access)

Developing the VirtualwindoW into a General Purpose Telepresence Interface

An important need while using robots or remotely operated equipment is the ability for the operator or an observer to easily and accurately perceive the operating environment. A classic problem in providing a complete representation of a work area is sensory overload or excessive complexity in the human–machine interface. In addition, remote operations often benefit from depth perception capability while viewing or manipulating objects. Thus, there is an on going effort within the robotic field to develop simplified telepresence interfaces. The Department of Energy’s Idaho National Engineering and Environmental Laboratory (INEEL) has been researching methods to generalize a human-machine interface for telepresence applications. Initial telepresence research conducted at the INEEL developed and implemented a concept called the VirtualwindoW. This system minimized the complexity of remote stereo viewing controls and provided the operator the “feel” of viewing the environment, including depth perception, in a natural setting. The VirtualwindoW has shown that the human-machine interface can be simplified while increasing operator performance. This paper deals with the continuing research and development of the VirtualwindoW to provide a generalized, reconfigurable system that easily utilizes commercially available components. The original system has now been expanded to include support for zoom lenses, camera blocks, wireless …
Date: April 1, 1999
Creator: Kinoshita, Robert Arthur; Anderson, Matthew Oley; Mckay, Mark D & Willis, Walter David
Object Type: Article
System: The UNT Digital Library
The Integration of an Electro-hydraulic Manipulator Arm into a Self-contained Mobile Delivery System (open access)

The Integration of an Electro-hydraulic Manipulator Arm into a Self-contained Mobile Delivery System

The Portable Articulated Arm Deployment System (PAADS) is a remotely controlled vehicle for delivering a tele-operated electro-hydraulic manipulator arm to a field deployable location. The self-contained system includes a boom vehicle with long reach capability, an electro-hydraulic manipulator arm, closed circuit television (CCTV) systems, and onboard tools. On board power systems consist of a self contained, propane fired 8 KW generator and an air compressor for pneumatic tools. The generator provides the power to run the air compressor as well as provide power to operate the 110 VAC auxiliary lighting system for the video cameras. The separate control console can be located up to 500 ft from the vehicle. PAADS is a fully integrated system, containing all equipment required to perform complex field operations. Hydraulic integration of the manipulator arm into the vehicle hydraulic drive system was necessary to eliminate the tether management of hoses, which extended vehicle operating range, minimized hydraulic pressure losses, and provided the opportunity to go to a radio frequency (RF) control system in the future, thereby eliminating the control cable. This paper presents the key decision points during system development. Emphasis is placed on ease of operator control and not on an intelligent machine approach. …
Date: April 1, 1999
Creator: Borland, Mark Wilson & Berry, Stephen Michael
Object Type: Article
System: The UNT Digital Library
In Situ Site Characterization Technologies Demonstrated at the INEEL in Decommissioning Projects (open access)

In Situ Site Characterization Technologies Demonstrated at the INEEL in Decommissioning Projects

The United States Department of Energy (DOE)continually seeks safer, more cost-effective, and better performing technologies for decontamination and decommissioning (D&D) of nuclear facilities. The Deactivation and Decommissioning Focus Area (DDFA) of the DOE Federal Energy Technology Center (FETC) sponsors Large Scale Demonstration and Deployment Projects (LSDDPs) which are conducted at various DOE sites. The Idaho National Engineering and Environmental Laboratory (INEEL) is one of the DOE sites for demonstration of these newa and improved technologies. The INEEL needs statement defines specific needs or problems for their D&D program. One of the needs identified at the INEEL was for new or improved site characterization technologies. A variety of in-situ site characterization technologies have been demonstrated through the INEEL LSDDP. These technologies provide a safer means of characterization, improved documentation, real-time information, improved D&D schedules, and reduction in costs and radiation exposures to workers. These technologies have provided vast improvements to the D&D site characterizations. Some of these technologies include: • The Global Positioning Radiometric Scanner System for large-area, surface gamma radiation surveys • Remote underwater characterization system• Identifying heavy metals in painted surfaces and determining the alloy composition in metallic material • In-Situ Object Counting System for free release • Real-time …
Date: April 1, 1999
Creator: Wright, Kelly Clyde; Meservey, Richard Harlan & Whitmill, Larry Joseph
Object Type: Article
System: The UNT Digital Library
Dissolution Studies With Pilot Plant and Actual INTEC Calcines (open access)

Dissolution Studies With Pilot Plant and Actual INTEC Calcines

The dissolution of Idaho Nuclear Technology and Engineering Center (INTEC) pilot plant calcines was examined to determine solubility of calcine matrix components in acidic media. Two representatives pilot plant calcine types were studied: Zirconia calcine and Zirconia/ Sodium calcine. Dissolution of these calcines was evaluated using lower initial concentrations of nitric acid than used in previous tests to decrease the [H+] concentration in the final solutions. Lower [H+] concentrations contribute to more favorable TRUEX/SREX solvent extraction flowsheet performance. Dissolution and analytical results were also obtained for radioactive calcines produced using high sodium feeds blended with non-radioactive A1(NO3)3 solutions to dilute the sodium concentration and prevent bed agglomeration during the calcination process. Dissolution tests indicated >95 wt. % of the initial calcine mass can be dissolved using the baseline dissolution procedure, with the exception that higher initial nitric acid concentrations are required. The higher initial acid concentration is required for stoichiometric dissolution of the oxides, primarily aluminum oxide. Statistically designed experiments using pilot plant calcine were performed to determine the effect of mixing rate on dissolution efficiency. Mixing rate was determined to provide minimal effects on wt. % dissolution. The acid/calcine ratio and temperature were the predominate variables affecting the wt. …
Date: April 1, 1999
Creator: Herbst, Ronald Scott & Garn, Troy Gerry
Object Type: Report
System: The UNT Digital Library
Options for Determining Equivalent MHTM (Metric Tons of Heavy Metal) for DOE High Level Waste (open access)

Options for Determining Equivalent MHTM (Metric Tons of Heavy Metal) for DOE High Level Waste

Section 114(d) of the Nuclear Waste Policy Act of 1982, as amended (NWPA), limits the overall capacity of the first repository to 70,000 metric tons of heavy metal (MTHM). Current DOE policy is to allocate DOE spent fuel and high-level waste (HLW) at 10 percent of the total, or 7,000 MTHM. For planning purposes, 4,667 MTHM will be allocated for HLW. While the NWPA provides a technical basis for determining the MTHM equivalence of HLW, it does not address the significant technical differences between DOE HLW and commercial spent nuclear fuel (SNF). Although more than 170,000 MTHM of DOE fuel has been reprocessed to produce the inventory of HLW, the amount of radioactive waste generated per metric ton of DOE fuel is only a few percent of that in a metric ton of commercial fuel. This study compares the results of four methods for determining the MTHM equivalence of DOE HLW. These methods include (1) using the actual weight of heavy metal in reprocessed DOE fuel, (2) assuming the historical equivalence of 0.5 MTHM/canister of vitrified DOE HLW, (3) comparing the total radioactivity in DOE HLW to the radioactivity of commercial SNF, and (4) comparing the total radiotoxicity of DOE …
Date: April 1, 1999
Creator: Knecht, Dieter August; Valentine, James Henry; Luptak, Alan Jay; Staiger, Merle Daniel; Loo, Henry Hung Yiu & Wichmann, Thomas Leonard
Object Type: Report
System: The UNT Digital Library
RGUI 1.0, New Graphical User Interface for RELAP5-3D (open access)

RGUI 1.0, New Graphical User Interface for RELAP5-3D

With the advent of three-dimensional modeling in nuclear safety analysis codes, the need has arisen for a new display methodology. Currently, analysts either sort through voluminous numerical displays of data at points in a region, or view color coded interpretations of the data on a two-dimensional rendition of the plant. RGUI 1.0 provides 3D capability for displaying data. The 3D isometric hydrodynamic image is built automatically from the input deck without additional input from the user. Standard view change features allow the user to focus on only the important data. Familiar features that are standard to the nuclear industry, such as run, interact, and monitor, are included. RGUI 1.0 reduces the difficulty of analyzing complex three dimensional plants.
Date: April 1, 1999
Creator: Mesina, George Lee & Galbraith, James Andrew
Object Type: Article
System: The UNT Digital Library
Mobile Robotic Teams Applied to Precision Agriculture (open access)

Mobile Robotic Teams Applied to Precision Agriculture

The Idaho National Engineering and Environmental Laboratory (INEEL) and Utah State University’s Center for Self-Organizing and Intelligent Systems (CSOIS) have developed a team of autonomous robotic vehicles applicable to precision agriculture. A unique technique has been developed to plan, coordinate, and optimize missions in large structured environments for these autonomous vehicles in realtime. Two generic tasks are supported: 1) Driving to a precise location, and 2) Sweeping an area while activating on-board equipment. Sensor data and task achievement data is shared among the vehicles enabling them to cooperatively adapt to changing environmental, vehicle, and task conditions. This paper discusses the development of the autonomous robotic team, details of the mission-planning algorithm, and successful field demonstrations at the INEEL.
Date: April 1, 1999
Creator: Anderson, Matthew Oley; Kinoshita, Robert Arthur; Mckay, Mark D; Willis, Walter David; Gunderson, R.W. & Flann, N.S.
Object Type: Article
System: The UNT Digital Library
Remote Underwater Characterization System - Innovative Technology Summary Report (open access)

Remote Underwater Characterization System - Innovative Technology Summary Report

Characterization and inspection of water-cooled and moderated nuclear reactors and fuel storage pools requires equipment capable of operating underwater. Similarly, the deactivation and decommissioning of older nuclear facilities often requires the facility owner to accurately characterize underwater structures and equipment which may have been sitting idle for years. The underwater characterization equipment is often required to operate at depths exceeding 20 ft (6.1 m) and in relatively confined or congested spaces. The typical baseline approach has been the use of radiation detectors and underwater cameras mounted on long poles, or stationary cameras with pan and tilt features mounted on the sides of the underwater facility. There is a perceived need for an inexpensive, more mobile method of performing close-up inspection and radiation measurements in confined spaces underwater. The Remote Underwater Characterization System (RUCS) is a small, remotely operated submersible vehicle intended to serve multiple purposes in underwater nuclear operations. It is based on the commercially-available “Scallop” vehicle1, but has been modified by Department of Energy’s Robotics Technology Development Program to add auto-depth control, and vehicle orientation and depth monitoring at the operator control panel. The RUCS is designed to provide visual and gamma radiation characterization, even in confined or limited …
Date: April 1, 1999
Creator: Willis, Walter David
Object Type: Report
System: The UNT Digital Library
Enhanced Reductive Dechlorination of TCE in a Basalt Aquifer (open access)

Enhanced Reductive Dechlorination of TCE in a Basalt Aquifer

A field evaluation of enhanced reductive dechlorination of trichloroethene (TCE) in ground water has been in progress since November 1998 to determine whether in situ biodegradation can be significantly enhanced through the addition of an electron donor (lactate). An in situ treatment cell was established in the residual source area of a large TCE plume in a fractured basalt aquifer utilizing continuous ground water extraction approximately 150 meters downgradient of the injection location. After a 1-month tracer test and baseline sampling period, the pulsed injection of lactate was begun. Ground water samples were collected from 11 sampling points on a biweekly basis and in situ water quality parameters were recorded every 4 hours at two locations. Within 2 weeks after the initial lactate injection, dissolved oxygen and redox potential were observed to decrease substantially at all sampling locations within 40 m of the injection well. Decreases in nitrate and sulfate concentrations were also observed. Both quantitative in situ rate estimation methods and qualitative measures such as changes in redox conditions, decreases in chlorine number, and changes in biomass indicator parameters are being used throughout the test to evaluate the extent to which biodegradation of TCE is enhanced.
Date: April 1, 1999
Creator: Sorenson, Kent Soren; Peterson, Lance Nutting & Ely, R. L.
Object Type: Article
System: The UNT Digital Library
The VirtualwindoW: A Reconfigurable, Modular, Stereo Vision System (open access)

The VirtualwindoW: A Reconfigurable, Modular, Stereo Vision System

An important need while using unmanned vehicles is the ability for the remote operator or observer to easily and accurately perceive the operating environment. A classic problem in providing a complete representation of the remote work area is sensory overload or excessive complexity in the human-machine interface. In addition, remote operations often benefit from depth perception capability while viewing or manipulating objects. Thus, there is an on going effort within the remote and teleoperated robotic field to develop better human-machine interfaces. The Department of Energy's Idaho National Engineering and Environmental Laboratory (INEEL) has been researching methods to simplify the human-machine interface using atypical operator techniques. Initial telepresence research conducted at the INEEL developed and implemented a concept called the VirtualwindoW. This system minimized the complexity of remote stereo viewing controls and provided the operator the "feel" of viewing the environment, including depth perception, in a natural setting. The VirtualwindoW has shown that the human-machine interface can be simplified while increasing operator performance. This paper deals with the continuing research and development of the VirtualwindoW to provide a reconfigurable, modular system that easily utilizes commercially available off the shelf components. This adaptability is well suited to several aspects of unmanned vehicle …
Date: April 1, 1999
Creator: Kinoshita, Robert Arthur; Anderson, Matthew Oley; Mckay, Mark D & Willis, Walter David
Object Type: Article
System: The UNT Digital Library
The Hybrid Emulsion Detector for MINOS R&D Proposal (open access)

The Hybrid Emulsion Detector for MINOS R&D Proposal

The MINOS (Main Injector Neutrino Oscillation Search) experiment is designed to search for neutrino oscillations with a sensitivity significantly greater than has been achieved to date. The phenomenon of neutrino oscillations, whose existence has not been proven convincingly so far, allows neutrinos of one "flavor" (type) to slowly transform themselves into another flavor, and then back again to the original flavor, as they propagate through space or matter. The MINOS experiment is optimized to explore the region of neutrino oscillation "parameter space" suggested by previous investigations of atmospheric neutrinos: the Kamiokande, IMB, Super-Kamiokande and Soudan 2 experiments. The study of oscillations in this region with a neutrino beam from the Main Injector requires measurements of the beam after a very long flight path. This in turn requires an intense neutrino beam and a massive detector in order to have an adequate event rate at a great distance from the source. We propose to enhance significantly the physics capabilities of the MINOS experiment by the addition of a Hybrid Emulsion Detector at Soudan, capable of unambigous identification of the neutrino flavor. Recent developments in emulsion experiments make such a detector possible, although significant technological challenges must be overcome. We propose to …
Date: April 1, 1999
Creator: Adamson, P.; Alexandrov, K. V.; Allison, W. W.M.; Alner, G. J.; Ambats, I.; Anderson, B. et al.
Object Type: Report
System: The UNT Digital Library
AL-SX (H1616) Container Support: Out-gassing of Polyethylene and Polycarbonate Resins (open access)

AL-SX (H1616) Container Support: Out-gassing of Polyethylene and Polycarbonate Resins

Out-gassing tests were carried out on samples of polyethylene and polycarbonate packaging components used within the AL-SX (H1616) shipping container and compared to known samples of high and low density polyethylene and polycarbonate. Polyethylene is used to fabricate the shipping container overpack for the MC3007A/MC4059 and 1X-Acorn; LEXAN{reg_sign} polycarbonate (General Electric) is used to fabricate the lid of the Protective Container utilized to package the MC4213/MC4240 and MC4524 for shipment in the AL-SX (H1616). Pressure was monitored up to about 650 F and all the samples showed similar increases in pressure which were only slightly above those measured for control runs using no resin sample. None of the polymer samples showed out-gassing behavior that would lead to excessive pressure increases in the H1616 within that temperature range.
Date: April 1, 1999
Creator: Story, G.Cook & Domeier, Leon Seibel and Linda
Object Type: Report
System: The UNT Digital Library
An Annotated Reference Guide to the Finite-Element Interface Specification Version 1.0 (open access)

An Annotated Reference Guide to the Finite-Element Interface Specification Version 1.0

The Finite-Element Interface (FEI) specification provides a layered abstraction that permits finite-element analysis codes to utilize various linear-algebra solution packages with minimal concern for the internal details of the solver modules. Alternatively, this interface can be viewed as a way for solver developers to provide solution services to finite-element clients without having to embed finite-element abstractions within their solver libraries. The purpose of this document is to provide some level of documentation between the bare interface specification itself, which consists only of C/C++ header files, and the full documentation suite that supports the interface definition by providing considerable detail as to its design and implementation. This document primarily provides the ''how'' of calling the interface member functions, so that programmers can readily learn how to utilize the interface implementation without having to consider all the details contained in the interface's definition, design, and motivation. The interface specification is presented three times in this document, each time with an increasing level of detail. The first presentation provides a general overview of the calling sequence, in order to acquaint the programmer with a basic introduction to how the interface is used to ''train'' the underlying solver software on the particular finite-element problem …
Date: April 1, 1999
Creator: Williams, Alan B.; Otero, Ivan J.; Mish, Kyran D.; Tayor, Lee M. & Clay, Robert L.
Object Type: Report
System: The UNT Digital Library
Microseismicity survey of the El Hoyo-Monte Galan geothermal region in Nicaragua (open access)

Microseismicity survey of the El Hoyo-Monte Galan geothermal region in Nicaragua

The project's objective is to use conceptual and mathematical models of geothermal fields as a basis for interpreting multiple datasets of geophysical data and for improving geothermal exploration techniques. The objective of this effort is to collect and interpret microseismicity data. The technical objectives are: plan and carry out a joint seismic deployment in Nicaragua, recording microseismicity activity at magnitude 1.5 or less; analyze microseismicity data to define possible fracture zones/geothermal conduits; determine the velocity and possibly the attenuation structure in the El Hoyo-Monte Calan area; and work with the staff of the Trans-Pacific Geothermal Company to evaluate existing geological and geophysical data.
Date: April 1, 1999
Creator: Hutchings, L; Kasamayer, P & Smith, A T
Object Type: Report
System: The UNT Digital Library
Laboratory Evaluation of In Situ Chemical Oxidation for Groundwater Remediation, Test Area North, Operable Unit 1-07B, Idaho National Engineering and Environmental Laboratory, Volume Two, Appendices C, D, and E (open access)

Laboratory Evaluation of In Situ Chemical Oxidation for Groundwater Remediation, Test Area North, Operable Unit 1-07B, Idaho National Engineering and Environmental Laboratory, Volume Two, Appendices C, D, and E

These appendices support the results and discussion of the laboratory work performed to evaluate the feasibility of in situ chemical oxidation for Idaho National Environmental and Engineering Laboratory's (INEEL) Test Area North (TAN) which is contained in ORNL/TM-1371 l/Vol. This volume contains Appendices C-E. Appendix C is a compilation of all recorded data and mathematical calculations made to interpret the data. For the Task 3 and Task 4 work, the spreadsheet column definitions are included immediately before the actual spreadsheet pages and are listed as ''Sample Calculations/Column Definitions'' in the table of contents. Appendix D includes the chronological order in which the experiments were conducted and the final project costs through October 1998. Appendix E is a compilation of the monthly progress reports submitted to INEEL during the course of the project.
Date: April 1, 1999
Creator: Cline, S. R.; Denton, D. L.; Giaquinto, J. M.; McCracken, M. K. & Starr, R. C.
Object Type: Report
System: The UNT Digital Library
Hindered Diffusion of Asphaltenes at Elevated Temperature and Pressure Progress Report (open access)

Hindered Diffusion of Asphaltenes at Elevated Temperature and Pressure Progress Report

During this time period, we performed experiments to examine the effects of solvent composition on the diffusion controlled uptake of quinoline into alumina catalyst pellets. Of particular interest was the effect of solvent aromaticity on the diffusive uptake process. The uptake experiments were performed at a temperature of 300 C for the adsorptive diffusion of quinoline in a solvent mixture of mineral oil and 1-methyl naphthalene onto alumina catalyst pellets. These experiments were conducted in a 40 cm{sup 3} microautoclave, the use of which is more economical from both a purchasing and waste disposal standpoint due to the small quantities of solvents and catalysts utilized, and is also significantly safer at the higher temperatures. In order to study the effect of aromaticity of the solvent on the hindered diffusion-adsorption process, the experiments were performed at different volume fractions of 1-methyl naphthalene. Detailed calculations were made to estimate the effects of aromaticity, i. e., as reflected by the percentage of 1-methyl naphthalene in the solvent, on the diffusive properties of the solute. Model simulation results were then performed which showed that the mathematical model incorporating diffusion and adsorption mechanisms satisfactorily fitted the adsorptive diffusion of quinoline onto the alumina catalyst at …
Date: April 1, 1999
Creator: Guin, James A. & Vadlamani, Surya
Object Type: Report
System: The UNT Digital Library
Laboratory Evaluation of In Situ Chemical Oxidation for Groundwater Remediation, Test Area North, Operable Unit 1-07B, Idaho National Engineering and Environmental Laboratory, Volume One - Main Text and Appendices A and B (open access)

Laboratory Evaluation of In Situ Chemical Oxidation for Groundwater Remediation, Test Area North, Operable Unit 1-07B, Idaho National Engineering and Environmental Laboratory, Volume One - Main Text and Appendices A and B

The laboratory investigation was performed to evaluate the feasibility of utilizing in situ chemical oxidation for remediating the secondary source of groundwater contaminants at the Idaho National Engineering and Environmental Laboratory (INEEL) Test Area North (TAN) Site. The study involved trichloroethene (TCE) contaminated media (groundwater, soil, and sludge) from TAN. The effectiveness of the selected oxidant, potassium permanganate (KMn0(sub4)), was evaluated at multiple oxidant and contaminant concentrations. Experiments were performed to determine the oxidant demand of each medium and the rate of TCE oxidation. The experiments were performed under highly controlled conditions (gas-tight reactors, constant 12C temperature). Multiple parameter were monitored over time including MN0(sub 4) and TCE concentrations and pH.
Date: April 1, 1999
Creator: Cline, S. R.; Denton, D. L.; Giaquinto, J. M.; McCracken, M. K. & Starr, R. C.
Object Type: Report
System: The UNT Digital Library
Remote Underwater Characterization System - Innovative Technology Summary Report (open access)

Remote Underwater Characterization System - Innovative Technology Summary Report

Characterization and inspection of water-cooled and moderated nuclear reactors and fuel storage pools requires equipment capable of operating underwater. Similarly, the deactivation and decommissioning of older nuclear facilities often requires the facility owner to accurately characterize underwater structures and equipment which may have been sitting idle for years. The Remote Underwater Characterization System (RUCS) is a small, remotely operated submersible vehicle intended to serve multiple purposes in underwater nuclear operations. It is based on the commercially-available �Scallop� vehicle 1 , but has been modified by the Department of Energy�s Robotics Technology Development Program to add auto-depth control, and vehicle orientation and depth monitoring at the operator control panel. The RUCS is designed to provide visual and gamma radiation characterization, even in confined or limited access areas. It was demonstrated in August 1998 at the Idaho National Engineering and Environmental Laboratory (INEEL) as part of the INEEL Large Scale Demonstration and Deployment Project. During the demonstration it was compared in a "head-to-head� fashion with the baseline characterization technology. This paper summarizes the results of the demonstration and lessons learned; comparing and contrasting both technologies in the areas of cost, visual characterization, radiological characterization, and overall operations.
Date: April 1, 1999
Creator: Willis, W. D.
Object Type: Article
System: The UNT Digital Library
Oxidative weathering chemical migration under variably saturated conditions and supergene copper enrichment (open access)

Oxidative weathering chemical migration under variably saturated conditions and supergene copper enrichment

Transport of oxygen gas from the land surface through an unsaturated zone has a strong influence on oxidative weathering processes. Oxidation of sulfide minerals such as pyrite (FeS{sub 2}), one of the most common naturally occurring minerals, is the primary source of acid drainage from mines and waste rock piles. Here we present a detailed numerical model of supergene copper enrichment that involves the oxidative weathering of pyrite (FeS{sub 2}) and chalcopyrite (CuFeS{sub 2}), and acidification that causes mobilization of metals in the unsaturated zone, with subsequent formation of enriched ore deposits of chalcocite (CuS) and covellite (Cu{sub 2}S) in the reducing conditions below the water table. We examine and identify some significant conceptual and computational issues regarding the oxidative weathering processes through the modeling tool. The dissolution of gaseous oxygen induced by the oxidation reduces oxygen partial pressure, as well as the total pressure of the gas phase. As a result, the gas flow is modified, then the liquid phase flow. Results indicate that this reaction effect on the fluid flow may not be important under ambient conditions, and gas diffusion can be a more important mechanism for oxygen supply than gas or liquid advection. Acidification, mobilization of metals, …
Date: April 1, 1999
Creator: Xu, Tianfu; Pruess, K. & Brimhall, G.
Object Type: Report
System: The UNT Digital Library
Advanced Concepts for High-Power VCSELS and 2-Dimensional VCSEL Arrays (open access)

Advanced Concepts for High-Power VCSELS and 2-Dimensional VCSEL Arrays

We have developed high power vertical cavity surface emitting lasers (VCSELS) for multimode or single mode operation. We have characterized new cavity designs for individual lasers and 2-dimensional VCSEL arrays to maximize output power. Using broad area high power VCSELS under pulsed excitation, we have demonstrated the triggering of a photoconductive semiconductor switch (PCSS) with a VCSEL. We also have developed designs for high output power in a single mode. The first approach is to engineer the oxide aperture profile to influence the optical confinement and thus modal properties. A second approach focuses on "leaky-mode" concepts using lateral modification of the cavity resonance to provide the lateral refractive index difference. To this end, we have developed a regrowth process to fabricate single-mode VCSELS. The overall objective of this work was to develop high-power single-mode or multimode sources appropriate for many applications leveraging the many inherent advantages of VCSELS.
Date: April 1, 1999
Creator: Allerman, A. A.; Choquette, Kent D.; Chow, W. W.; Geib, K. M.; Hadley, R.; Hou, H. Q. et al.
Object Type: Report
System: The UNT Digital Library
ISIS++Reference Guide (Iterative Scalable Implicit Solver in C++) Version 1.1 (open access)

ISIS++Reference Guide (Iterative Scalable Implicit Solver in C++) Version 1.1

ISIS++ (Iterative Scalable Implicit Solver in C++) Version 1.1 is a portable, object-oriented framework for solving sparse linear systems of equations. It includes a collection of Krylov solution methods and preconditioners, as well as both uni-processor (serial) and multi-processor (scalable) matrix and vector classes. Though it was developed to solve systems of equations originating from large-scale, 3-D, finite element analyses, it has application in many other fields. This document supersedes the ISIS++ V1.0 Reference Guide, defines the V1. 1 interface specification, and includes the necessary instructions for building and running ISIS++ v 1.1 on Unix platforms. The interface is presented in annotated header format, along with background on design and implementation considerations. A finite difference modeling example problem is included to demonstrate the overall setup and use.
Date: April 1, 1999
Creator: Williams, Alan B.; Allan, Benjamin A.; Mish, Kyran D. & Clay, Robert L.
Object Type: Report
System: The UNT Digital Library
Genetic algorithms and their use in Geophysical Problems (open access)

Genetic algorithms and their use in Geophysical Problems

Genetic algorithms (GAs), global optimization methods that mimic Darwinian evolution are well suited to the nonlinear inverse problems of geophysics. A standard genetic algorithm selects the best or ''fittest'' models from a ''population'' and then applies operators such as crossover and mutation in order to combine the most successful characteristics of each model and produce fitter models. More sophisticated operators have been developed, but the standard GA usually provides a robust and efficient search. Although the choice of parameter settings such as crossover and mutation rate may depend largely on the type of problem being solved, numerous results show that certain parameter settings produce optimal performance for a wide range of problems and difficulties. In particular, a low (about half of the inverse of the population size) mutation rate is crucial for optimal results, but the choice of crossover method and rate do not seem to affect performance appreciably. Optimal efficiency is usually achieved with smaller (< 50) populations. Lastly, tournament selection appears to be the best choice of selection methods due to its simplicity and its autoscaling properties. However, if a proportional selection method is used such as roulette wheel selection, fitness scaling is a necessity, and a high …
Date: April 1, 1999
Creator: Parker, Paul B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Developing the VirtualwindoW into a General Purpose Telepresence Interface (open access)

Developing the VirtualwindoW into a General Purpose Telepresence Interface

An important need while using robots or remotely operated equipment is the ability for the operator or an observer to easily and accurately perceive the operating environment. A classic problem in providing a complete representation of a work area is sensory overload or excessive complexity in the human�machine interface. In addition, remote operations often benefit from depth perception capability while viewing or manipulating objects. Thus, there is an on going effort within the robotic field to develop simplified telepresence interfaces. The Department of Energy�s Idaho National Engineering and Environmental Laboratory (INEEL) has been researching methods to generalize a human-machine interface for telepresence applications. Initial telepresence research conducted at the INEEL developed and implemented a concept called the VirtualwindoW. This system minimized the complexity of remote stereo viewing controls and provided the operator the �feel� of viewing the environment, including depth perception, in a natural setting. The VirtualwindoW has shown that the human-machine interface can be simplified while increasing operator performance. This paper deals with the continuing research and development of the VirtualwindoW to provide a generalized, reconfigurable system that easily utilizes commercially available components. The original system has now been expanded to include support for zoom lenses, camera blocks, wireless …
Date: April 1, 1999
Creator: McKay, M.D.; Anderson, M.O.; Kinoshita, R.A. & Willis, W.D.
Object Type: Article
System: The UNT Digital Library