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What Do We Know About Ethanol and Alkylates as Pollutants? (open access)

What Do We Know About Ethanol and Alkylates as Pollutants?

Gov. Davis issued Executive Order D-5-99 in March 1999 calling for removal of methyl tertiary butyl ether (MTBE) from gasoline no later than December 31, 2002. The Executive Order required the California Air Board, State Water Resources Control Board (SWRCB) and Office of Environmental Health Hazard Assessment (OEHHA) to prepare an analysis of potential impacts and health risks that may be associated with the use of ethanol as a fuel oxygenate. The SWRCB contracted with the Lawrence Livermore National Laboratory (LLNL) to lead a team of researchers, including scientists from Clarkson University, University of Iowa, and University of California, Davis, in evaluating the potential ground and surface water impacts that may occur if ethanol is used to replace MTBE. These findings are reported in the document entitled Health and Environmental Assessment of the Use of Ethanol as a Fuel Oxygenate. This document has been peer reviewed and presented to the California Environmental Policy Council and may be viewed at: http://www-erd.llnl.gov/ethanol/. Ethanol used for fuels is made primarily from grains, but any feed stock containing sugar, starch, or cellulose can be fermented to ethanol. Ethanol contains 34.7% oxygen by weight. It is less dense than water, but infinitely soluble in water. …
Date: May 11, 2001
Creator: Rich, D W; Marchetti, A A; Buscheck, T & Layton, D W
System: The UNT Digital Library
Model Predictions of Chemically Controlled Slow Crack Growth with Application to Mechanical Effects in Geothermal Environments (open access)

Model Predictions of Chemically Controlled Slow Crack Growth with Application to Mechanical Effects in Geothermal Environments

Representative, simplified geothermal rock-fluid systems are investigated with a modeling approach to estimate how rock water interactions affect coupled properties related to mechanical stability and permeability improvement through fracturing. First, geochemical modeling is used to determine the evolution of fluid chemistry at temperatures up to 300 C when fluids are in contact with representative rocks of continental origin. Then, a kinetic crack growth model for quartz is used to predict growth rate for subcritical cracks in acidic and basic environments. The predicted growth rate is highly sensitive to temperature and pH in the ranges tested. At present, the model is limited to situations in which quartz controls the mechanical process of interest, such as well bore stability in silica cemented rocks and the opening of quartz filled veins to enhance permeability.
Date: April 11, 2001
Creator: Viani, B. E.
System: The UNT Digital Library
Forward-Inverse Adaptive Techniques for Reservoir Characterization and Simulation: Theory and Applications (open access)

Forward-Inverse Adaptive Techniques for Reservoir Characterization and Simulation: Theory and Applications

A novel approach called Forward-Inverse Adaptive Techniques (FIAT) for reservoir characterization is developed and applied to three representative exploration cases. Inverse modeling refers to the determination of the entire reservoir permeability under steady state single-phase flow regime, given only field permeability, pressure and production well measurements. FIAT solves the forward and inverse partial differential equations (PDEs) simultaneously by adding a regularization term and filtering pressure gradients. An implicit adaptive-grid, Galerkin, numerical scheme is used to numerically solve the set of PDEs subject to pressure and permeability boundary conditions. Three examples are presented. Results from all three cases demonstrate attainable and reasonably accurate solutions and, more importantly, provide insights into the consequences of data undersampling.
Date: June 11, 2001
Creator: Doss, S D; Ezzedine, S; Gelinas, R & Chawathe, A
System: The UNT Digital Library
Overview and Status of the Power Conditioning System for the National Ignition Facility (open access)

Overview and Status of the Power Conditioning System for the National Ignition Facility

The National Ignition Facility (NIF) Power Conditioning System (PCS) is a modular capacitive energy storage system that provides over 34 kilojoules of energy to each of the nearly 8000 flashlamps in the NIF laser. Up to 400 megajoules of energy can be stored in the NIF PCS system, discharged through spark gaps and delivered to the flashlamps through a coaxial transmission line system requiring nearly 100 miles of high-voltage cable. The NIF PCS has been under development for nearly 4 years. During this time, the system was developed and designed by Sandia National Laboratory in Albuquerque, NM (SNLA) in conjunction with Lawrence Livermore National Laboratory (LLNL). Extensive reliability testing was performed at SNLA on the First Article NIF Test Module (FANTM) test facility and design improvements were implemented based on FANTM test results, leading to the final design presently undergoing system reliability testing at LLNL. Low-cost energy-storage capacitors, charging power supplies, and reliable, fault-tolerant components were developed through partnerships with numerous contractors. Extensive reliability and fault testing of components has also been performed. This paper will provide an overview of the many efforts that have culminated in the final design of the NIF PCS. The PCS system design will be …
Date: September 11, 2001
Creator: Newton, M A; Fulkerson, E S; Hulsey, S D; Kamm, R E; Pendleton, D L; Petersen, D E et al.
System: The UNT Digital Library
12th International Workshop on Plant Membrane Biology (open access)

12th International Workshop on Plant Membrane Biology

This report is on 12th International Workshop on Plant Membrane Biology
Date: August 11, 2001
Creator: Spalding, Edgar P.
System: The UNT Digital Library
Effect of catalyst structure on oxidative dehydrogenation of ethane and propane on alumina-supported vanadia (open access)

Effect of catalyst structure on oxidative dehydrogenation of ethane and propane on alumina-supported vanadia

The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm2) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominantly as isolated monovanadate species below {approx}2.3 V/nm2. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm2) along with increasing amounts of V2O5 crystallites at surface densities above 7.0 V/nm2. The rate constant for oxidative dehydrogenation (k1) and its ratio with alkane and alkene combustion (k2/k1 and k3/k1, respectively) were compared for both alkane reactants as a function of vanadia surface density. Propene formation rates (per V-atom) are {approx}8 times higher than ethene formation rates at a given reaction temperature, but the apparent ODH activation energies (E1) are similar for the two reactants and relatively insensitive to vanadia surface density. Ethene and propene formation rates (per V-atom) are strongly influenced by vanadia surface density and reach a maximum value at intermediate surface densities ({approx}8 V/nm2). The ratio of k2/k1 depends weakly on reaction temperature, indicating that activation energies for alkane combustion and ODH reactions are similar. The ratio of k2/k1 is independent of surface density for ethane, but increase slightly with vanadia surface …
Date: September 11, 2001
Creator: Argyle, Morris D.; Chen, Kaidong; Bell, Alexis T. & Iglesia, Enrique
System: The UNT Digital Library
Revisiting the 'Buy versus Build' Decision for Publicly Owned Utilities in California Considering Wind and Geothermal Resources (open access)

Revisiting the 'Buy versus Build' Decision for Publicly Owned Utilities in California Considering Wind and Geothermal Resources

The last two decades have seen a dramatic increase in the market share of independent, nonutility generators (NUGs) relative to traditional, utility-owned generation assets. Accordingly, the ''buy versus build'' decision facing utilities--i.e., whether a utility should sign a power purchase agreement (PPA) with a NUG, or develop and own the generation capacity itself--has gained prominence in the industry. Very little of this debate, however, has focused specifically on publicly owned electric utilities, and with few exceptions, renewable sources of supply have received similarly scant attention. Contrary to historical treatment, however, the buy versus build debate is quite relevant to publicly owned utilities and renewables because publicly owned utilities are able to take advantage of some renewable energy incentives only in a ''buy'' situation, while others accrue only in a ''build'' situation. In particular, possible economic advantages of public utility ownership include: (1) the tax-free status of publicly owned utilities and the availability of low-cost debt, and (2) the renewable energy production incentive (REPI) available only to publicly owned utilities. Possible economic advantages to entering into a PPA with a NUG include: (1) the availability of federal tax credits and accelerated depreciation schedules for certain forms of NUG-owned renewable energy, and …
Date: December 11, 2001
Creator: Bolinger, Mark; Wiser, Ryan & Golove, William
System: The UNT Digital Library
Design of the superconducting section of the SPL Linac at CERN (open access)

Design of the superconducting section of the SPL Linac at CERN

In order to set up a powerful proton source for a future Neutrino Factory, increasing at the same time the flux of protons available for new and existing facilities, CERN is studying a 2.2 GeV superconducting H- linac for 4 MW beam power, called SPL. The superconducting part of this linac covers the energy range from 120 MeV to 2.2 GeV. Three sections made of 352 MHz cavities with nominal beta of 0.52, 0.7 and 0.8 bring the beam energy up to 1 GeV. From this energy, superconducting cavities from LEP or beta 0.8 cavities can be used up to the final energy of 2.2 GeV. This paper covers the optimization for the superconducting part, the beam dynamics design principles, the matching between sections, and the results of multiparticle simulations with up to 50 million particles. To demonstrate the stability of the design, matched and mismatched input beams are used.
Date: June 11, 2001
Creator: Gerigk, F.; Vretenar, M. & Ryne, Robert D.
System: The UNT Digital Library
Friction and wear performance of low-friction carbon coatings under oil lubrication. (open access)

Friction and wear performance of low-friction carbon coatings under oil lubrication.

Amorphous carbon coatings with very low friction properties were recently developed at Argonne National Laboratory. These coatings have shown good promise in mitigating excessive wear and scuffing problems associated with low-lubricity diesel fuels. To reduce the negative effect of sulfur and other lubricant additives in poisoning the after-treatment catalyst, a lubricant formulation with a low level of sulfur may be needed. Exclusion of proven sulfur-containing extreme pressure (EP) and antiwear additives from oils will require other measures to ensure durability of critical lubricated components. The low-friction carbon coating has the potential for such applications. In the present study, we evaluated the friction and wear attributes of three variations of the coating under a boundary lubrication regime. Tests were conducted with both synthetic and mineral oil lubricants using a ball-on-flat contact configuration in reciprocating sliding. Although the three variations of the coating provided modest reductions in friction coefficient, they all reduced wear substantially compared to an uncoated surface. The degradation mode of oxidative wear on the uncoated surface was replaced by a polishing wear mode on the coated surfaces.
Date: December 11, 2001
Creator: Kovalchenko, A.; Ajayi, O. O.; Erdemir, A. & Fenske, G. R.
System: The UNT Digital Library
Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates (open access)

Distribution of Chromium Contamination and Microbial Activity in Soil Aggregates

None
Date: July 11, 2001
Creator: Tokunaga, Tetsu K.; Wan, Jiamin; Hazen, Terry C.; Schwartz, Egbert; Firestone, Mary K.; Sutton, Stephen R. et al.
System: The UNT Digital Library
Fracture and fatigue behavior at ambient and elevated temperatures of alumina bonded with copper/niobium/copper interlayers (open access)

Fracture and fatigue behavior at ambient and elevated temperatures of alumina bonded with copper/niobium/copper interlayers

None
Date: February 11, 2001
Creator: Kruzic, J. J.; Marks, R. A.; Yoshiya, M.; Glaeser, A. M.; Cannon, R. M. & Ritchie, R. O.
System: The UNT Digital Library
Pd/Cu site interchange in UCu{sub 5-x}Pd{sub x} (open access)

Pd/Cu site interchange in UCu{sub 5-x}Pd{sub x}

Although Pd/Cu site interchange in the non-Fermi liquid (NFL) material UCu{sub 4}Pd has been observed, the relationship between this disorder and the NFL behavior remains unclear. In order to better compare to the UCu{sub 5-x}Pd{sub x} phase diagram, they report results from Pd K edge x-ray absorption fine structure (XAFS) experiments on this series (x = 0.3-1.5) that determine the fraction of Pd atoms on the nominally Cu (16e) sites, s. They find that for these unannealed samples, s is at least 17% for all the samples measured, even for x < 1.0, although it does climb monotonically beyond its minimum at x = 0.7. These data are compared to changes in the lattice parameter as a function of x.
Date: July 11, 2001
Creator: Booth, C. H.; Bauer, E. D.; Maple, M. B.; Chau, R. & Kwei, G. H.
System: The UNT Digital Library
Harold Johnston Festschrift (open access)

Harold Johnston Festschrift

None
Date: January 11, 2001
Creator: Johnston, Harold
System: The UNT Digital Library
Strategies for Cost-Effective Carbon Reductions: A Sensitivity Analysis of Alternative Scenarios (open access)

Strategies for Cost-Effective Carbon Reductions: A Sensitivity Analysis of Alternative Scenarios

Analyses of alternative futures often present results for a limited set of scenarios, with little if any sensitivity analysis to identify the factors affecting the scenario results. This approach creates an artificial impression of certainty associated with the scenarios considered, and inhibits understanding of the underlying forces. This paper summarizes the economic and carbon savings sensitivity analysis completed for the Scenarios for a Clean Energy Future study (IWG, 2000). Its 19 sensitivity cases provide insight into the costs and carbon-reduction impacts of a carbon permit trading system, demand-side efficiency programs, and supply-side policies. Impacts under different natural gas and oil price trajectories are also examined. The results provide compelling evidence that policy opportunities exist to reduce carbon emissions and save society money.
Date: July 11, 2001
Creator: Gumerman, Etan; Koomey, Jonathan G. & Brown, Marilyn
System: The UNT Digital Library
Analytical laboratory quality audits (open access)

Analytical laboratory quality audits

Analytical Laboratory Quality Audits are designed to improve laboratory performance. The success of the audit, as for many activities, is based on adequate preparation, precise performance, well documented and insightful reporting, and productive follow-up. Adequate preparation starts with definition of the purpose, scope, and authority for the audit and the primary standards against which the laboratory quality program will be tested. The scope and technical processes involved lead to determining the needed audit team resources. Contact is made with the auditee and a formal audit plan is developed, approved and sent to the auditee laboratory management. Review of the auditee's quality manual, key procedures and historical information during preparation leads to better checklist development and more efficient and effective use of the limited time for data gathering during the audit itself. The audit begins with the opening meeting that sets the stage for the interactions between the audit team and the laboratory staff. Arrangements are worked out for the necessary interviews and examination of processes and records. The information developed during the audit is recorded on the checklists. Laboratory management is kept informed of issues during the audit so there are no surprises at the closing meeting. The audit report …
Date: June 11, 2001
Creator: Kelley, William D.
System: The UNT Digital Library
Quality Control, Testing, and Deployment Results in the NIF ICCS (open access)

Quality Control, Testing, and Deployment Results in the NIF ICCS

The strategy used to develop the NIF Integrated Computer Control System (ICCS) calls for incremental cycles of construction and formal test to deliver a total of 1 million lines of code. Each incremental release takes four to six months to implement specific functionality and culminates when offline tests conducted in the ICCS Integration and Test Facility verify functional, performance, and interface requirements. Tests are then repeated on line to confirm integrated operation in dedicated laser laboratories or ultimately in the NIF. Test incidents along with other change requests are recorded and tracked to closure by the software change control board (SCCB). Annual independent audits advise management on software process improvements. Extensive experience has been gained by integrating controls in the prototype laser preamplifier laboratory. The control system installed in the preamplifier lab contains five of the ten planned supervisory subsystems and seven of sixteen planned front-end processors (FEPs). Beam alignment, timing, diagnosis and laser pulse amplification up to 20 joules was tested through an automated series of shots. Other laboratories have provided integrated testing of six additional FEPs. Process measurements including earned-value, product size, and defect densities provide software project controls and generate confidence that the control system will be …
Date: October 11, 2001
Creator: Woodruff, J P; Casavant, D; Cline, B D & Gorvad, M R
System: The UNT Digital Library
Kinetic Electron Closures for Electromagnetic Simulation of Drift and Shear-Alfven Waves (II) (open access)

Kinetic Electron Closures for Electromagnetic Simulation of Drift and Shear-Alfven Waves (II)

An electromagnetic hybrid scheme (fluid electrons and gyrokinetic ions) is elaborated in example calculations and extended to toroidal geometry. The scheme includes a kinetic electron closure valid for {beta}{sub e} > m{sub e}/m{sub i} ({beta}{sub e} is the ratio of the plasma electron pressure to the magnetic field energy density). The new scheme incorporates partially linearized ({delta}f) drift-kinetic electrons whose pressure and number density moments are used to close the fluid momentum equation for the electron fluid (Ohm's law). The test cases used are small-amplitude kinetic shear-Alfven waves with electron Landau damping, the ion-temperature-gradient instability, and the collisionless drift instability (universal mode) in an unsheared slab as a function of the plasma {beta}{sub e}. Attention is given to resolution and convergence issues in simulations of turbulent steady states.
Date: October 11, 2001
Creator: Cohen, B. I.; Dimits, A. M.; Nevins, W. M.; Chen, Y. & Parker, S.
System: The UNT Digital Library
Visualization and Integrated Data Mining of Disparate Information (open access)

Visualization and Integrated Data Mining of Disparate Information

The volumes and diversity of information in the discovery, development, and business processes within the chemical and life sciences industries require new approaches for analysis. Traditional list- or spreadsheet-based methods are easily overwhelmed by large amounts of data. Furthermore, generating strong hypotheses and, just as importantly, ruling out weak ones, requires integration across different experimental and informational sources. We have developed a framework for this integration, including common conceptual data models for multiple data types and linked visualizations that provide an overview of the entire data set, a measure of how each data record is related to every other record, and an assessment of the associations within the data set.
Date: May 11, 2001
Creator: Saffer, Jeffrey D.; Albright, Cory L.; Calapristi, Augustin J.; Chen, Guang; Crow, Vernon L.; Decker, Scott D. et al.
System: The UNT Digital Library
Initial Reaction Steps in the Condensed-Phase Decomposition of Propellants (open access)

Initial Reaction Steps in the Condensed-Phase Decomposition of Propellants

Understanding the reaction mechanisms for the decomposition of energetic materials in the condensed phase is critical to our development of detailed kinetic models of propellant combustion. To date, the reaction mechanisms in the condensed phase have been represented by global, reactions. The detailed elementary reactions subsequent to the initial NO{sub 2} bond scissioning are not known. Using quantum chemical calculations, we have investigated the possible early steps in the decomposition of energetic materials that can occur in the condensed phase. We have used methylnitrate, methylnitramine, and nitroethane as prototypes for O-NO{sub 2}, N-NO{sub 2} and C-NO{sub 2} nitro compounds. We find the energetic radicals formed from the initial NO{sub 2} bond scissioning can be converted to unsaturated non-radical intermediates as an alternative to the unzipping of the energetic radical. We propose a new, prompt oxidation mechanism in which the trapped HONO can add back onto the energetic molecule. This produces oxidation products in the condensed phase that normally would not be produced until much later in the flame. We have shown that this prompt oxidation mechanism is a general feature of both nitramines and nitrate esters. The resulting HONO formed by the H-atom abstraction will be strongly influenced by the …
Date: December 11, 2001
Creator: Melius, C F & Piqueras, M C
System: The UNT Digital Library
Satiated Relative Permeability of Variable-Aperture Fractures (open access)

Satiated Relative Permeability of Variable-Aperture Fractures

The relative permeability of a variable-aperture fracture under satiated conditions (wetting phase spans the fracture, non-wetting phase is completely entrapped) is controlled by the distribution of the entrapped phase within the fracture plane. We use simulations to investigate the combined influence of capillary forces and aperture variability on satiated relative permeability and demonstrate the effectiveness of a dimensionless perturbation curvature number (C') for predicting entrapped-phase structure. C' combines the relative influence of in-plane and out-of-plane interface curvature and the aperture coefficient of variation ({sigma}{sub a}/<a>) on local capillary forces. Results suggest that C' provides a single parameter that can be used to estimate satiated relative permeability.
Date: December 11, 2001
Creator: Detwiler, R. L.; Glass, R. J.; Rajaram, H. & Nicholl, M. J.
System: The UNT Digital Library
Developing a Process for Commercial Silica Production from Geothermal Brines (open access)

Developing a Process for Commercial Silica Production from Geothermal Brines

Useful mineral by-products can be produced from geothermal brines. Although silica has many commercial uses, problems remain in producing a marketable product. We are conducting laboratory and modeling studies aimed at optimizing for rubber additive use, the properties of silica precipitates from Salton Sea and Coso-like geothermal fluids, Our goal is to develop a robust technique for producing silicas that have desirable physical and chemical properties for commercial use, while developing a generic understanding of silica precipitation that will allow extraction to be extended to additional fluid types, and to be easily modified to produce new types of marketable silica. Our experiments start with an acidified geothermal fluid similar to those treated by pH modification technology. Silica precipitation is induced by adding base and/or adding Mg or Ca salts to affect the nature of the precipitate. For the analog Salton Sea fluids, adding base alone caused silica to precipitate fairly rapidly. To date, we have characterized precipitates from experiments in which the final pH varied from 4 to 8, where NaOH and Na{sub 2}C0{sub 3} were added as bases, and CaCl{sub 2} and MgCl{sub 2} were added as salts. SEM photos of the silica precipitates from the Salton Sea and …
Date: April 11, 2001
Creator: Bourcier, W; Martin, S; Viani, B & Bruton, C
System: The UNT Digital Library
Analysis of Forcing, Response, and Feedbacks in a Paleoclimate Modeling Experiment (open access)

Analysis of Forcing, Response, and Feedbacks in a Paleoclimate Modeling Experiment

It is often argued that paleoclimate studies are necessary to determine whether climate models and their predictions of future climate change can be trusted. An overall measure of the sensitivity of global mean surface temperature to a given radiative perturbation is provided by the global climate sensitivity parameter. In climate model experiments, this parameter appears to be moderately independent of the cause of the perturbation [see, for example, Hansen et al. (1997) and Hewitt and Mitchell (1997)], but it may differ from one model to the next by as much as a factor of three (IPCC, 1995). Moreover, there are some scientists who claim that all models are much more sensitive than the climate system itself (Lindzen, 1997). Thus it would be valuable to determine which models (if any) are consistent with the paleoclimate record and what factors are responsible for model differences in sensitivity. In an analysis of the Paleoclimate Modeling Intercomparison Project (PMIP) simulations of the Last Glacial Maximum (LGM) of 21,000 years ago, we have calculated how the ''forcing'' and feedbacks determine the climatic response. In the PMIP context, the ice sheet distribution is prescribed and the resulting increase in planetary albedo is the most important ''forcing'' …
Date: April 11, 2001
Creator: Taylor, K E; Hewitt, C D; Braconnot, P; Broccoli, A J; Doutriaux, C & Mitchell, J F B
System: The UNT Digital Library
Particle Simulations of DARHT-II Transport System (open access)

Particle Simulations of DARHT-II Transport System

The DARHT-II beam line utilizes a fast stripline kicker to temporally chop a high current electron beam from a single induction LINAC and deliver multiple temporal electron beam pulses to an x-ray converter target. High beam quality needs to be maintained throughout the transport line from the end of the accelerator through the final focus lens to the x-ray converter target to produce a high quality radiographic image. Issues that will affect beam quality such as spot size and emittance at the converter target include dynamic effects associated with the stripline kicker as well as emittance growth due to the nonlinear forces associated with the kicker and various focusing elements in the transport line. In addition, dynamic effects associated with transverse resistive wall instability as well as gas focusing will affect the beam transport. A particle-in-cell code is utilized to evaluate beam transport in the downstream transport line in DARHT-II. External focusing forces are included utilizing either analytic expressions or field maps. Models for wakefields from the beam kicker, transverse resistive wall instability, and gas focusing are included in the simulation to provide a more complete picture of beam transport in DARHT-II. From these simulations, for various initial beam loads …
Date: June 11, 2001
Creator: Poole, B. & Chen, Y. J.
System: The UNT Digital Library
First Measurements of Pion Correlations by the PHENIX Experiment (open access)

First Measurements of Pion Correlations by the PHENIX Experiment

First identical-pion correlations measured at RHIC energies by PHENIX are presented. Two analyses with separate detectors, systematics, and statistics provide consistent results. The resulting HBT radii are moderately larger than those measured at lower energies. The k{sub t} dependence of the Bertsch-Pratt HBT radii is also similar to previous measures and is consistent with the conjecture of an expanding source.
Date: April 11, 2001
Creator: Johnson, S. C.
System: The UNT Digital Library