A Reference-Dependent Regret Model for Deterministic Trade-off Studies (open access)

A Reference-Dependent Regret Model for Deterministic Trade-off Studies

Today's typical multi-criteria decision analysis is based on classical expected utility theory that assumes a mythical ''Rational Individual'' immune to psychological influences such as anticipated regret. It is therefore in conflict with rational individuals who trade-off some benefits and forgo the alternative with the highest total classical utility for a more balanced alternative in order to reduce their levels of anticipated regret. This paper focuses on decision making under certainty. It presents a reference-dependent regret model (RDRM) in which the level of regret that an individual experiences depends on the absolute values rather than the differences of the utilities of the chosen and forgone alternatives. The RDRM best choice may differ from the conventional linear additive utility model, the analytic hierarchy process, and the regret theory of Bell and Loomes and Sugden. Examples are presented that indicate that RDRM is the better predictive descriptor for decision making under certainty. RDRM satisfies transitivity of the alternatives under pairwise comparisons and models rank reversal consistent with observed reasonable choices under dynamic or distinct situations. Like regret theory, the RDRM utilities of all the alternatives under consideration are interrelated. For complex trade-off studies regret is incorporated as an element of a cost-utility-regret analysis …
Date: February 25, 2005
Creator: Kujawski, Edouard
System: The UNT Digital Library
Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids (open access)

Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids

Recent studies suggest that mineral dissolution/precipitation and clay swelling effects could have a major impact on the performance of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs. A major concern is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths. A Pitzer ionic interaction model has been introduced into the publicly available TOUGHREACT code for solving non-isothermal multi-phase reactive geochemical transport problems under conditions of high ionic strength, expected in typical HDR and HFR systems. To explore chemically-induced effects of fluid circulation in these systems, we examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance. We performed a number of coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua). Results obtained with the Pitzer activity coefficient model were compared with those using an extended Debye-Hueckel equation. Our simulations show that non-ideal activity effects can be significant even at modest ionic strength, and can have major impacts on permeability evolution in injection-production systems. Alteration of injection water chemistry, for example by dilution with fresh water, can greatly alter precipitation and dissolution effects, and can offer a powerful …
Date: February 9, 2005
Creator: Xu, Tianfu; Zhang, Guoxiang & Pruess, Karsten
System: The UNT Digital Library
Glass Durability Modeling, Activated Complex Theory (ACT) (open access)

Glass Durability Modeling, Activated Complex Theory (ACT)

The most important requirement for high-level waste glass acceptance for disposal in a geological repository is the chemical durability, expressed as a glass dissolution rate. During the early stages of glass dissolution in near static conditions that represent a repository disposal environment, a gel layer resembling a membrane forms on the glass surface through which ions exchange between the glass and the leachant. The hydrated gel layer exhibits acid/base properties which are manifested as the pH dependence of the thickness and nature of the gel layer. The gel layer has been found to age into either clay mineral assemblages or zeolite mineral assemblages. The formation of one phase preferentially over the other has been experimentally related to changes in the pH of the leachant and related to the relative amounts of Al{sup +3} and Fe{sup +3} in a glass. The formation of clay mineral assemblages on the leached glass surface layers ,lower pH and Fe{sup +3} rich glasses, causes the dissolution rate to slow to a long-term steady state rate. The formation of zeolite mineral assemblages ,higher pH and Al{sup +3} rich glasses, on leached glass surface layers causes the dissolution rate to increase and return to the initial high …
Date: February 4, 2005
Creator: CAROL, JANTZEN
System: The UNT Digital Library
A nonlocal, ab initio model of dissociative electron attachment and vibrational excitation of NO (open access)

A nonlocal, ab initio model of dissociative electron attachment and vibrational excitation of NO

We present the results of an ab initio study of elastic scattering and vibrational excitation of NO by electron impact in the low-energy (0-2 eV) region where the cross sections are dominated by resonance contributions. The 3Sigma-, 1Delta and 1Sigma+ NO- resonance lifetimes are taken from our earlier study [Phys. Rev. A 69, 062711 (2004)], but the resonance energies used here are obtained from new configuration-interaction studies. Here we employ a more elaborate nonlocal treatment of the nuclear dynamics, which is found to remedy the principal deficiencies of the local complex potential model we employed in our earlier study, and gives cross sections in better agreement with the most recent experiments. We also present cross sections for dissociative electron attachment to NO leading to groundstate products. The calculations show that, while the peak cross sections starting from NO in its ground vibrational state are very small, the cross sections are extremely sensitive to vibrational excitation of the target and should be readily observable for target NO molecules excited to v = 10 and above.
Date: February 1, 2005
Creator: Trevisan, Cynthia S.; Houfek, Karel; Zhang, Zhiyong; Orel, Ann E.; McCurdy, C. William & Rescigno, Thomas N.
System: The UNT Digital Library
Front Surface Tandem Filters using Sapphire (Al2O3) Substrates for Spectral Control in thermophotovoltaic Energy Conversion Systems (open access)

Front Surface Tandem Filters using Sapphire (Al2O3) Substrates for Spectral Control in thermophotovoltaic Energy Conversion Systems

None
Date: February 28, 2005
Creator: Rahmlow, T. D., Jr.; Lazo-Wasem, J.; Gratrix, E.; Fourspring, P. & DePoy, D.
System: The UNT Digital Library
RHEOLOGICAL PROPERTIES OF SAVANNAH RIVER SITE (srs) RADIOACTIVE HIGH LEVEL WASTES AND MELTER FEEDS FOR SLUDGE BATCH 2 (open access)

RHEOLOGICAL PROPERTIES OF SAVANNAH RIVER SITE (srs) RADIOACTIVE HIGH LEVEL WASTES AND MELTER FEEDS FOR SLUDGE BATCH 2

The Savannah River Site, SRS, is currently pursuing an aggressive program to empty its High Level Waste, HLW, tanks and immobilize its radioactive waste into a durable borosilicate glass in the Defense Waste Processing Facility, DWPF. To create a batch of feed for the DWPF, several tanks of sludge slurry are combined into one of the million gallon, i.e. 3.79E06 liters, feed tanks for DWPF. A batch of feed nominally consists of 500,000 gallons, i.e. 1.89E06 liters. After a batch of feed is prepared, a portion of the batch, 26,500 liters, is transferred to DWPF. This batch is then chemically adjusted in the Chemical Processing Cell, CPC, prior to being fed to the melter to make the final product; canisters filled with glass. During the processing of the third batch, or Sludge Batch 2, of feed through the DWPF CPC, pumping and transfer problems were noted. These problems hindered the processing of the feed through the CPC, and thus impacted canister production in DWPF. In order to investigate the root cause of these problems, data were collected and evaluated for possible trends. One trend noted was the relationship between the pH, solids loading concentration, and temperature of the feed. As …
Date: February 15, 2005
Creator: TERRI, FELLINGER
System: The UNT Digital Library
Dry Air Oxidation of Commercial Spent Nuclear Fuel (open access)

Dry Air Oxidation of Commercial Spent Nuclear Fuel

None
Date: February 8, 2005
Creator: Hanson, B.
System: The UNT Digital Library
High Current Ion Sources and Injectors for Heavy Ion Fusion (open access)

High Current Ion Sources and Injectors for Heavy Ion Fusion

Heavy ion beam driven inertial fusion requires short ion beam pulses with high current and high brightness. Depending on the beam current and the number of beams in the driver system, the injector can use a large diameter surface ionization source or merge an array of small beamlets from a plasma source. In this paper, we review the scaling laws that govern the injector design and the various ion source options including the contact ionizer, the aluminosilicate source, the multicusp plasma source, and the MEVVA source.
Date: February 15, 2005
Creator: Kwan, Joe W.
System: The UNT Digital Library
Estimating Energy and Water Losses in Residential Hot Water Distribution Systems (open access)

Estimating Energy and Water Losses in Residential Hot Water Distribution Systems

Residential single family building practice currently ignores the losses of energy and water caused by the poor design of hot water systems. These losses include; the waste of water while waiting for hot water to get to the point of use; the wasted heat as water cools down in the distribution system after a draw; and the energy needed to reheat water that was already heated once before. Average losses of water are estimated to be 6.35 gallons (24.0 L) per day. (This is water that is rundown the drain without being used while waiting for hot water.) The amount of wasted hot water has been calculated to be 10.9 gallons (41.3L) per day. (This is water that was heated, but either is not used or issued after it has cooled off.) A check on the reasonableness of this estimate is made by showing that total residential hot water use averages about 52.6 gallons (199 L) per day. This indicates about 20 percent of average daily hot water is wasted.
Date: February 26, 2005
Creator: Lutz, James
System: The UNT Digital Library
Neutron Transmission and Capture Measurements and Resonance Parameter Analysis of Neodymium from 1eV to 500 eV (open access)

Neutron Transmission and Capture Measurements and Resonance Parameter Analysis of Neodymium from 1eV to 500 eV

None
Date: February 11, 2005
Creator: Barry, DP; Trbovich, MJ; Danon, Y; Block, RC & Slovacek, RE
System: The UNT Digital Library
Aging and Gene Expression in the Primate Brain (open access)

Aging and Gene Expression in the Primate Brain

It is well established that gene expression levels in many organisms change during the aging process, and the advent of DNA microarrays has allowed genome-wide patterns of transcriptional changes associated with aging to be studied in both model organisms and various human tissues. Understanding the effects of aging on gene expression in the human brain is of particular interest, because of its relation to both normal and pathological neurodegeneration. Here we show that human cerebral cortex, human cerebellum, and chimpanzee cortex each undergo different patterns of age-related gene expression alterations. In humans, many more genes undergo consistent expression changes in the cortex than in the cerebellum; in chimpanzees, many genes change expression with age in cortex, but the pattern of changes in expression bears almost no resemblance to that of human cortex. These results demonstrate the diversity of aging patterns present within the human brain, as well as how rapidly genome-wide patterns of aging can evolve between species; they may also have implications for the oxidative free radical theory of aging, and help to improve our understanding of human neurodegenerative diseases.
Date: February 18, 2005
Creator: Fraser, Hunter B.; Khaitovich, Philipp; Plotkin, Joshua B.; Paabo, Svante & Eisen, Michael B.
System: The UNT Digital Library
Pyramidal Defects in GaN:Mg Grown with Ga Polarity (open access)

Pyramidal Defects in GaN:Mg Grown with Ga Polarity

Transmission electron microscopy (TEM) studies show formation of different types of Mg-rich defects in GaN. Types of defects strongly depend on crystal growth polarity. For bulk crystals grown with N-polarity, the planar defects are distributed at equal distances (20 unit cells of GaN). For growth with Ga-polarity (for both bulk and MOCVD grown crystals) a different type of defects have been found. These defects are three-dimensional Mg-rich hexagonal pyramids (or trapezoids) with their base on the (0001) plane and six walls formed on 1123 planes. The defects appear in [1120] and [1100] cross-section TEM micrographs as triangular and trapezoidal with sides inclined at 43 and 47 degrees to the base depending on the above observation directions, respectively. The dimension of these pyramids varies depending on growth method (50-1000 Angstrom), but the angle between the base and their sides remain the same. The direction from the tip of the pyramid to its base (and from the shorter to the longer base for trapezoidal defects) is along the Ga to N matrix bond direction. Analysis of the reconstructed exit wave phase image from the pyramid side indicates a shift of Ga atomic column positions from the matrix to the N position within …
Date: February 15, 2005
Creator: Liliental-Weber, Zuzanna; Tomaszewicz, Tomasz; Zakharov, Dmitri & O'Keefe, Michael A.
System: The UNT Digital Library
Numerical Computation of Diffusion on a Surface (open access)

Numerical Computation of Diffusion on a Surface

We present a numerical method for computing diffusive transport on a surface derived from image data. Our underlying discretization method uses a Cartesian grid embedded boundary method for computing the volume transport in region consisting of all points a small distance from the surface. We obtain a representation of this region from image data using a front propagation computation based on level set methods for solving the Hamilton-Jacobi and eikonal equations. We demonstrate that the method is second-order accurate in space and time, and is capable of computing solutions on complex surface geometries obtained from image data of cells.
Date: February 24, 2005
Creator: Schwartz, Peter; Adalsteinsson, David; Colella, Phillip; Arkin, Adam Paul & Onsum, Matthew
System: The UNT Digital Library
Beryllium Sampling and Analysis Within the DOE Complex and Opportunities for Standardization (open access)

Beryllium Sampling and Analysis Within the DOE Complex and Opportunities for Standardization

Since the U. S. Department of Energy published the DOE Beryllium Rule, 10 CFR 850, in 1999, DOE sites have been required to measure beryllium on air filters and wipes for worker protection and for release of materials from beryllium-controlled areas. Measurements in the nanogram range on a filter or wipe are typically required. Industrial hygiene laboratories have applied methods from various analytical compendia, and a number of issues have emerged with sampling and analysis practices. As a result, a committee of analytical chemists, industrial hygienists, and laboratory managers was formed in November 2003 to address the issues. The committee developed a baseline questionnaire and distributed it to DOE sites and other agencies in the U.S. and U.K. The results of the questionnaire are presented in this paper. These results confirmed that a wide variety of practices were in use in the areas of sampling, sample preparation, and analysis. Additionally, although these laboratories are generally accredited by the American Industrial Hygiene Association there are inconsistencies in performance among accredited labs. As a result, there are significant opportunities for development of standard methods that could improve consistency. The current availabilities and needs for standard methods are further discussed in a companion …
Date: February 7, 2005
Creator: MICHAEL, BRISSON
System: The UNT Digital Library
Reoxidation of Bioreduced Uranium Under Reducing Conditions (open access)

Reoxidation of Bioreduced Uranium Under Reducing Conditions

Uranium mining and processing for nuclear weapons and fuel have left thousands of sites with toxic levels of this actinide in soil and ground water. An emerging strategy for remediating such environments involves using organic carbon to promote microbially-mediated reduction and precipitation of insoluble U(IV) minerals. Although previous U bioreduction studies have shown promising results, they were of short duration (up to a few months). Our longer-term (20 months) laboratory study using historically contaminated sediment has alarmingly shown that microbial reduction of U was transient even under reducing (methanogenic) conditions. Uranium was reductively immobilized during the first 100 days, but later (150 to 600 days) reoxidized and mobilized, although a microbial community capable of reducing U(VI) remained through the end of the experiment. The formation of Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} complexes (caused by the elevated carbonate concentration from microbial respiration and presence of calcium) drove the U(IV)/U(VI) reduction potential to much more reducing conditions. Fe(III) and Mn(IV) were found to be likely terminal electron acceptors (TEAs) for U reoxidation. Thus, U remediation by organic carbon based reductive precipitation is not sustainable in calcareous, neutral to alkaline soils and ground waters.
Date: February 5, 2005
Creator: Wan, Jiamin; Tokunaga, Tetsu K.; Larson, Joern; Zheng, Zuoping; Brodie, Eoin; Wang, Zheming et al.
System: The UNT Digital Library
CP VIOLATION HIGHLIGHTS: CIRCA 2005 (open access)

CP VIOLATION HIGHLIGHTS: CIRCA 2005

Recent highlights in CP violation phenomena, are reviewed. B-factory results imply that, CP-violation phase in the CKM matrix is the dominant contributor to the observed CP violation in K and B-physics. Deviations from the predictions of the CKM-paradigm due to beyond the Standard Model CP-odd phase are likely to be a small perturbation. Therefore, large data sample of clean B's will be needed. Precise determination of the unitarity triangle, along with time dependent CP in penguin dominated hadronic and radiative modes are discussed. Null tests in B, K and top-physics and separate determination of the K-unitarity triangle are also emphasized.
Date: February 27, 2005
Creator: A., SONI
System: The UNT Digital Library
Distinguishing multiple chemotaxis Y protein conformations with laser-polarized 129Xe NMR (open access)

Distinguishing multiple chemotaxis Y protein conformations with laser-polarized 129Xe NMR

The chemical shift of the {sup 129}Xe NMR signal has been shown to be extremely sensitive to the local environment around the atom and has been used to follow processes such as ligand binding by bacterial periplasmic binding proteins (Rubin et al. 2000; Lowery et al. 2004). Here we show that the {sup 129}Xe shift can sense more subtle changes: magnesium binding, BeF{sub 3}{sup -} activation, and peptide binding by the E. coli chemotaxis Y protein. {sup 1}H-{sup 15}N correlation spectroscopy and x-ray crystallography were used to identify two xenon-binding cavities in CheY that are primarily responsible for the shift changes. One site is near the active site, and the other is near the peptide binding site.
Date: February 1, 2005
Creator: Lowery, Thomas J.; Doucleff, Michealeen; Ruiz, E. Janette; Rubin, Seth M.; Pines, Alexander & Wemmer, David E.
System: The UNT Digital Library
Yield Stress Reduction of Radioactive Waste Slurries by Addition of Surfactants (open access)

Yield Stress Reduction of Radioactive Waste Slurries by Addition of Surfactants

The Savannah River Site (SRS) and Hanford site are in the process of stabilizing millions of gallons of radioactive waste slurries remaining from production of nuclear materials for the Department of Energy (DOE). The Defense Waste Processing Facility (DWPF) at SRS is currently vitrifying the waste in borosilicate glass while the facilities at the Hanford site are in the design/construction phase. Both processes utilize slurry-fed joule heated melters to vitrify the waste slurries. The rheological properties of the waste slurries limit the total solids content that can be processed by the remote equipment during the pretreatment and melter feed processes. The use of a surface active agent, or surfactant, to increase the solids loading that can be fed to the melters would increase melt rate by reducing the heat load on the melter required to evaporate the water in the feed. The waste slurries are non-Newtonian fluids with rheological properties that were modeled using the Bingham Plastic mod el (this model is typically used by SRNL when studying the DWPF process1).The results illustrate that altering the surface chemistry of the particulates in the waste slurries can lead to a reduction in the yield stress. Dolapix CE64 is an effective surfactant …
Date: February 8, 2005
Creator: MICHAEL, STONE
System: The UNT Digital Library
Review of Wilson Data and Synthesis Tests (open access)

Review of Wilson Data and Synthesis Tests

None
Date: February 8, 2005
Creator: Friese, J.
System: The UNT Digital Library
2005 Electrochemistry Gordon Conference (open access)

2005 Electrochemistry Gordon Conference

This report is on Electrochemistry for Gordon Conference
Date: February 20, 2005
Creator: Buttry, Daniel
System: The UNT Digital Library
Actinide Thermodynamics at Higher Temperatures (open access)

Actinide Thermodynamics at Higher Temperatures

This report is about the Actinide Thermodynamics at Higher Temperatures
Date: February 9, 2005
Creator: Friese, J.
System: The UNT Digital Library
Local Climate Sensitivity of the Three Gorges Dam (open access)

Local Climate Sensitivity of the Three Gorges Dam

Two simulations, control and land use change, were performed for an eight week period (2 April-16 May 1990) to determine the net sensitivity of the local climate around the Three Gorges Dam. The analysis indicates that the large reservoir acts as a potential evaporating surface that decreases the surface temperature, cools the lower atmosphere, decreasing upward motion, and increasing sinking air mass. Such sinking results in low level moisture divergence, decreasing cloudiness, and increasing net downward radiation, which increases the surface temperature. However, results indicate that evaporative cooling dominates radiative warming in this initial study. The strong evaporation also supplies moisture to the atmosphere, suggesting an increase in precipitation, but the sinking moist air diverges away from the TGD region with no net change in precipitation. This numerical study represents an initial methodology for quantification of the impact of the Three Gorges Dam on the local climate and a more comprehensive, fine-scale set of multi-season simulations with additional observational data is needed for a more complete analysis.
Date: February 18, 2005
Creator: Miller, Norman L.; Jin, Jiming & Tsang, Chin-Fu
System: The UNT Digital Library
EVALUATION OF WETTING AGENTS TO MITIGATE DUSTING WHEN TRANSFERRING DRY GLASS FORMER CHEMICALS (open access)

EVALUATION OF WETTING AGENTS TO MITIGATE DUSTING WHEN TRANSFERRING DRY GLASS FORMER CHEMICALS

Plant design support for the US Department of Energy (DOE) River Protection Project (RPP) - Waste Treatment Plant (WTP) required pilot scale testing of the High Level Waste (HLW) glass former chemical (GFC) delivery system. A pilot facility was assembled at the Clemson Environmental Technology Laboratory (CETL) under the direction of the Savannah River National Laboratory (SRNL). Tests were performed using a representative HLW GFC blend to determine the behavior of the dry chemicals when transported through a chute and discharged into the enclosed head space of an agitated tank. The use of chute purge air, injected upstream of the point where the GFCs were added to the chute, was investigated. The pilot scale testing showed purge air was effective in reducing GFC holdup in the chute and that when the GFCs were discharged into the tank head space, dusting was evident during all transport conditions. This dusting lead to additional bench scale and laboratory scale tests that showed the addition of wetting agents to HLW and Low Activity Waste (LAW) GFC blends effectively mitigated dusting at the bench and pilot scales.
Date: February 7, 2005
Creator: TIMOTHY, JONES
System: The UNT Digital Library
Resolution Quality and Atom Positions in Sub-Angstrom Electron Microscopy (open access)

Resolution Quality and Atom Positions in Sub-Angstrom Electron Microscopy

Ability to determine whether an image peak represents one single atom or several depends on resolution of the HR-(S)TEM. Rayleigh's resolution criterion, an accepted standard in optics, was derived as a means for judging when two image intensity peaks from two sources of light (stars) are distinguishable from a single source. Atom spacings closer than the Rayleigh limit have been resolved in HR-TEM, suggesting that it may be useful to consider other limits, such as the Sparrow resolution criterion. From the viewpoint of the materials scientist, it is important to be able to use the image to determine whether an image feature represents one or more atoms (resolution), and where the atoms (or atom columns) are positioned relative to one another (resolution quality). When atoms and the corresponding image peaks are separated by more than the Rayleigh limit of the HR-(S)TEM, it is possible to adjust imaging parameters so that relative peak positions in the image correspond to relative atom positions in the specimen. When atoms are closer than the Rayleigh limit, we must find the relationship of the peak position to the atom position by peak fitting or, if we have a suitable model, by image simulation. Our Rayleigh-Sparrow …
Date: February 15, 2005
Creator: O'Keefe, Michael A.; Allard, Lawrence F. & Blom, Douglas A.
System: The UNT Digital Library