Physical effects of infrared quark eigenmodes in LQCD (open access)

Physical effects of infrared quark eigenmodes in LQCD

A truncated determinant algorithm is used to study the physical effects of the quark eigenmodes associated with eigenvalues below 300 MeV. This initial study focuses on coarse lattices (with O(a{sup 2}) improved gauge action), light internal quark masses and large physical volumes. Four bellweather full QCD processes are discussed: topological charge distributions, the eta prime propagator, string breaking as observed in the static energy and the rho decay into two pions.
Date: October 7, 1999
Creator: A. Duncan, E. Eichten and H. Thacker
Object Type: Article
System: The UNT Digital Library
Chamber and target technology development for inertial fusion energy (open access)

Chamber and target technology development for inertial fusion energy

Fusion chambers and high pulse-rate target systems for inertial fusion energy (IFE) must: regenerate chamber conditions suitable for target injection, laser propagation, and ignition at rates of 5 to 10 Hz; extract fusion energy at temperatures high enough for efficient conversion to electricity; breed tritium and fuel targets with minimum tritium inventory; manufacture targets at low cost; inject those targets with sufficient accuracy for high energy gain; assure adequate lifetime of the chamber and beam interface (final optics); minimize radioactive waste levels and annual volumes; and minimize radiation releases under normal operating and accident conditions. The primary goal of the US IFE program over the next four years (Phase I) is to develop the basis for a Proof-of-Performance-level driver and target chamber called the Integrated Research Experiment (IRE). The IRE will explore beam transport and focusing through prototypical chamber environment and will intercept surrogate targets at high pulse rep-rate. The IRE will not have enough driver energy to ignite targets, and it will be a non-nuclear facility. IRE options are being developed for both heavy ion and laser driven IFE. Fig. 1 shows that Phase I is prerequisite to an IRE, and the IRE plus NIF (Phase II) is prerequisite …
Date: April 7, 1999
Creator: Abdou, M.; Besenbruch, G.; Duke, J.; Forman, L.; Goodin, D.; Gulec, K. et al.
Object Type: Report
System: The UNT Digital Library
Electricity Restructuring Background: Public Utility Holding Company Act of 1935 (PUHCA) (open access)

Electricity Restructuring Background: Public Utility Holding Company Act of 1935 (PUHCA)

This report provides background information on PUHCA, including its history and impact. It also discusses how PUHCA reform fits into the current electric utility industry restructuring debate. This report will be updated as events warrant. For related information on electricity restructuring, see the CRS Electronic Briefing Book.
Date: January 7, 1999
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Discontinuous finite-element transport solutions in the thick diffusion limit in Cartesian geometry (open access)

Discontinuous finite-element transport solutions in the thick diffusion limit in Cartesian geometry

We analyze the behavior of discontinuous finite-element methods (DFEMs) for problems that contain diffusive regions. We find that in slab geometry most of these methods perform quite well, but that the same is not true in XY or XYZ geometry. In these geometries, we find that there are two distinct sets of DFEMS. Methods in one set produce unphysical solutions in diffusive regions; the other leading-order solutions that satisfy discretizations of the correct diffusion equation. We show that two simple properties of the finite-element weight functions are sufficient to guarantee that a DFEM belongs to the latter set. We show, however, that even these DFEMs suffer from several defects: their leading-order solutions are in general discontinuous, they satisfy diffusion discretizations that can be ill-behaved, and they may not be accurate given boundary layers that are not resolved by the spatial mesh. We discuss the practical significance of these defects, and we show that liberal modification of some DFEMs can eliminate the defects. We present numerical results from simple test problems; these fully agree with our analysis. 15 refs., 6 figs., 1 tab.
Date: January 7, 1991
Creator: Adams, M.L.
Object Type: Article
System: The UNT Digital Library
Even- and odd-parity finite-element transport solutions in the thick diffusion limit (open access)

Even- and odd-parity finite-element transport solutions in the thick diffusion limit

We analyze the behavior of odd-parity continuous finite-element methods (CFEMs) for problems that contain diffusive regions. We find that each of these method produces a solution that, to leading order inside diffusive regions, satisfies a discretization of the diffusion equation. We find further that these leading-order solutions satisfy boundary conditions that can lead to large errors in the interior solution. We recognize, however, that we can combine an odd-purity CFEM solution and an even-parity CFEM solution and obtain a solution that satisfies very accurate boundary conditions. Our analysis holds in three-dimensional Cartesian geometry, with an arbitrary spatial grid. We give numerical results from slab-geometry; these invariably agree with the predictions of the analysis. Finally, we introduce a rapidly-convergent diffusion-synthetic acceleration scheme for the odd-parity CFEMs, which we believe is new. 18 refs., 3 figs.
Date: January 7, 1991
Creator: Adams, M.L.
Object Type: Article
System: The UNT Digital Library
Experimental Investigation of In Situ Cleanable HEPA Filters (open access)

Experimental Investigation of In Situ Cleanable HEPA Filters

For the past several years studies have been conducted to investigate the use of innovative, alternative approaches to conventional disposable high efficiency particulate air filters.
Date: January 7, 1999
Creator: Adamson, D.J.
Object Type: Report
System: The UNT Digital Library
Raman Spectroscopy Characterization of amorphous carbon coatings for computer hard disks (open access)

Raman Spectroscopy Characterization of amorphous carbon coatings for computer hard disks

Amorphous carbon films are used as protective coatings on magnetic media to protect the magnetic layer from wear and abrasion caused by the read/write head during hard disk drive start-up and operation. A key requirement in increasing the storage capacity and reliability of hard-disk drives is improving the performance of these coatings. This cooperative agreement used optical characterization techniques developed at LBNL to study thin-film hard disk media produced by Seagate Technology, major US hard drive manufacturer. The chief scientific goal was relating quantitatively the results of the optical characterization to the underlying chemical structure of the overcoat. In a collaboration with Seagate, LBNL, and Cambridge University, optical and electron-based characterization were used to evaluate the chemical structure of overcoats. The sp3 fraction of the sputtered amorphous carbon films was measured quantitatively for the first time and related to the optical spectroscopy results. This work and other selected aspects of the research performed under the agreement were presented at technical meetings and published in the open literature. The chief technical goal was designing manufacturing processes for the protective carbon overcoat for use in new generations of Seagate disk drives. To this end, joint research carried out under this agreement enabled …
Date: May 7, 1998
Creator: Ager, Joel W., III
Object Type: Report
System: The UNT Digital Library
Fuel-flexible partial oxidation reforming of hydrocarbons for automotive applications. (open access)

Fuel-flexible partial oxidation reforming of hydrocarbons for automotive applications.

Micro-reactor tests indicate that our partial oxidation catalyst is fuel-flexible and can reform conventional (gasoline and diesel) and alternative (ethanol, methanol, natural gas) fuels to hydrogen rich product gases with high hydrogen selectivity. Alcohols are reformed at lower temperatures (< 600 C) while alkanes and unsaturated hydrocarbons require slightly higher temperatures. Cyclic hydrocarbons and aromatics have also been reformed at relatively low temperatures, however, a different mechanism appears to be responsible for their reforming. Complex fuels like gasoline and diesel, which are mixtures of a broad range of hydrocarbons, require temperatures of > 700 C for maximum hydrogen production.
Date: June 7, 1999
Creator: Ahmed, S.; Carter, J. D.; Kopasz, J. P.; Krumpelt, M. & Wilkenhoener, R.
Object Type: Article
System: The UNT Digital Library
Partial Oxidation Fuel Reforming for Automotive Power Systems (open access)

Partial Oxidation Fuel Reforming for Automotive Power Systems

For widespread use of fuel cells to power automobiles in the near future, it is necessary to convert gasoline or other transportation fuels to hydrogen on-board the vehicle. Partial oxidation reforming is particularly suited to this application as it eliminates the need for heat exchange at high temperatures. Such reformers offer rapid start and good dynamic performance. Lowering the temperature of the partial oxidation process, which requires the development of a suitable catalyst, can increase the reforming efficiency. Catalytic partial oxidation (or autothermal) reformers and non-catalytic partial oxidation reformers developed by various organizations are presently undergoing testing and demonstration. This paper summarizes the process chemistries as well as recent test data from several different reformers operating on gasoline, methanol, and other fuels.
Date: September 7, 1999
Creator: Ahmed, S.; Chalk, S.; Krumpelt, M.; Kumar, R. & Milliken, J.
Object Type: Article
System: The UNT Digital Library
Decontamination and dismantlement of Plant 7 at Fernald (open access)

Decontamination and dismantlement of Plant 7 at Fernald

Decontamination and dismantlement (D&D) tasks have been successfully completed on Plant 7 at the Fernald Environmental Management Project. The seven story facility was radiologically, chemically, and biologically contaminated. The work involved the D&D work beginning with safe shutdown and gross decontamination, and ended with removal of the structural steel. A series of lessons learned were gained which include use of explosives, bidding tactics, safe shutdown, building decontamination and lockdown, use of seam climbers, etc.
Date: November 7, 1994
Creator: Albertin, M.; Borgman, T. & Zebick, B.
Object Type: Article
System: The UNT Digital Library
Increased oil production and reserves from improved completion techniques in the Bluebell Field, Unita Basin, Utah. Quarterly technical progress report, January 1, 1995--March 31, 1995 (open access)

Increased oil production and reserves from improved completion techniques in the Bluebell Field, Unita Basin, Utah. Quarterly technical progress report, January 1, 1995--March 31, 1995

This project aspires to increase the productivity and reserves in the Uinta Basin by demonstration of improved completion techniques. Subsurface studies were performed this period.
Date: April 7, 1995
Creator: Allison, M. L.
Object Type: Report
System: The UNT Digital Library
Iron-Phosphate Ceramics for Solidification of Mixed Low-Level Waste (open access)

Iron-Phosphate Ceramics for Solidification of Mixed Low-Level Waste

A method of immobilizing mixed low-level waste is provided which uses low cost materials and has a relatively long hardening period. The method includes: forming a mixture of iron oxide powders having ratios, in mass %, of FeO: Fe{sub 2}O{sub 3}: Fe{sub 3}O{sub 4} equal to 25-40: 40-10: 35-50, or weighing a definite amount of magnitite powder. Metallurgical cinder can also be used as the source of iron oxides. A solution of the orthophosphoric acid, or a solution of the orthophosphoric acid and ferric oxide, is formed and a powder phase of low-level waste and the mixture of iron oxide powders or cinder (or magnetite powder) is also formed. The acid solution is mixed with the powder phase to form a slurry with the ratio of components (mass %) of waste: iron oxide powders or magnitite: acid solution = 30-60: 15-10: 55-30. The slurry is blended to form a homogeneous mixture which is cured at room temperature to form the final product.
Date: August 7, 1998
Creator: Aloy, Albert S.; Kovarskaya, Elena N.; Koltsova, Tatiana I.; Macheret, Yevgeny; Medvedev, Pavel G. & Todd, Terry
Object Type: Patent
System: The UNT Digital Library
Neutron interrogation to identify chemical elements with an ion-tube neutron source (INS) (open access)

Neutron interrogation to identify chemical elements with an ion-tube neutron source (INS)

A non-destructive analysis technique using a portable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The broad range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should lead to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers.
Date: April 7, 1994
Creator: Alvarez, R. A.; Dougan, A. D.; Rowland, M. R. & Wang, T. F.
Object Type: Article
System: The UNT Digital Library
Issues Related to the Provision of Housing and Utilities to Employees (open access)

Issues Related to the Provision of Housing and Utilities to Employees

Summary report describing issues with providing housing and utilities to state employees. This includes situations in which employees receive free, state-subsidized housing and utilities; live in state-owned properties for a nominal monthly rate; or receive monthly cash payments in lieu of in-kind housing benefits; and in which employees receive some form of educational assistance from their employing agencies
Date: April 7, 1997
Creator: Alwin, Lawrence F.
Object Type: Report
System: The Portal to Texas History
Neutrons and the crystal ball experiments. (open access)

Neutrons and the crystal ball experiments.

The Crystal Ball detector, as originally constructed, consisted of a set of 672 optically-isolated NaI crystals, forming an approximately spherical shell and each crystal viewed by a photomultiplier, a charged-particle tracker within the NaI shell, and two endcaps to cover angles close to two colliding beams. The detector geometry subtends a solid angle of about 93% of 4{pi} st (20{degree} {le} {theta} {le} 160{degree} and 0{degree} {le} {phi} {le} 360{degree}) from the center. The Crystal Ball detector was used for two long series of experiments at the e{sup +}e{sup {minus}} colliding beam accelerators SPEAR [1, 2, 3, 4] at SLAC and DORIS [5, 6, 7, 8] at DESY. A new set of measurements using the Crystal Ball detector is planned at the Brookhaven National Laboratory Alternating Gradient Synchrotrons (BNL AGS). These new experiments will use the 672 NaI crystals from the original detector, but neither the tracker nor endcaps. The ''Crystal Ball'' in this note will refer only to the set of NaI crystals. Initially, the reactions to be studied will include {pi}{sup {minus}}p{r_arrow} neutrals with pion beam momenta {approximately}400-750 MeV/c and K{sup {minus}} p{r_arrow} neutrals with kaon beam momenta {approximately}600-750 MeV/c. Each of these reactions will include a neutron …
Date: November 7, 1997
Creator: Alyer, J.; Grosnick, D.; Koetke, D.; Manweiler, R.; Spinka, H. & Stanislaus, S.
Object Type: Report
System: The UNT Digital Library
Terfenol: A study of the phase equilibrium diagram and the solidification process (open access)

Terfenol: A study of the phase equilibrium diagram and the solidification process

Terfenol is a rare earth-iron alloy that was first developed at the Naval Ordinance Laboratory because of its rare magnetostrictive properties. Terfenol is composed of terbium and dysprosium combined with iron in a composition Tb{sub x}Dy{sub 1{minus}x}Fe{sub 2}, where x{approximately}0.3. The objective of this work was to determine the growth characteristics of Terfenol and its dependence on solidification rate, temperature gradient, and stoichiometry. Specific goals of this work were to verify the phase equilibria that is currently accepted for the systems DyFe{sub 2} and TbFe{sub 2}, and establish the phase equilibria near the composition Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2}; establish that Terfenol grows directly from the liquid and that the reaction is occurring under metastable conditions; evaluate whether or not Terfenol can be grown under plane front conditions with a new radiofrequency float zone apparatus, and; determine whether or not <111> seeded crystals can be grown and <111> single crystals produced by elimination of dendrites employing growth methods capable of achieving high gradient/solidification rate ratios.
Date: December 7, 1993
Creator: Anderson, M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
EFFECTS OF MINERALOGY AND CATION-EXCHANGE CAPACITY ON LIGHIUM SORPTION TO YUCCA MOUNTAIN TUFFS. (open access)

EFFECTS OF MINERALOGY AND CATION-EXCHANGE CAPACITY ON LIGHIUM SORPTION TO YUCCA MOUNTAIN TUFFS.

None
Date: May 7, 1998
Creator: Anghel, I.; Turnin, H. J.; Reimus, P. W. & Carey, J. W.
Object Type: Report
System: The UNT Digital Library
Working Group 7.1 on environmental transport, US-USSR Joint Coordinating Committee on Civilian Nuclear Reactor Safety. Progress report update (open access)

Working Group 7.1 on environmental transport, US-USSR Joint Coordinating Committee on Civilian Nuclear Reactor Safety. Progress report update

This report contains brief summaries of the status of projects of the Environmental Transport Group of the US-USSR Joint Coordinating Committee of Civilian Nuclear Reactor Safety. Projects reported on include: Management and Administration; Atmospheric Transport; Resuspension; External Dose; Terrestrial Food Chains; Aquatic Food Chains; Hydrological Transport; and Intercalibration
Date: September 7, 1991
Creator: Anspaugh, L. R. & Hendrickson, S. M.
Object Type: Report
System: The UNT Digital Library
IMAP: A complete Ion Micro-Analysis Package for the nuclear microprobe (open access)

IMAP: A complete Ion Micro-Analysis Package for the nuclear microprobe

Microprobe techniques using scanned, focused MeV ions are routinely used in Livermore for materials characterization. Comprehensive data analysis with these techniques is accomplished with the computer software package IMAP, for Ion Micro-Analysis Package. IMAP consists of a set of command language procedures for data processing and quantitative spectral analysis. Deconvolution of the data is achieved by spawning sub-processes within IMAP which execute analysis codes for each specific microprobe technique. IMAP is structured to rapidly analyze individual spectra or multi-dimensional data blocks which classify individual events by the two scanning dimensions, the energy of the detected radiation and, when necessary, one sample rotation dimension. Several examples are presented to demonstrate the utility of the package.
Date: June 7, 1993
Creator: Antolak, A. J.; Hildner, M. L.; Morse, D. H. & Bench, G. S.
Object Type: Article
System: The UNT Digital Library
Oxygen electrode reaction in molten carbonate fuel cells (open access)

Oxygen electrode reaction in molten carbonate fuel cells

Molten carbonate fuel cell system is a leading candidate for the utility power generation because of its high efficiency for fuel to AC power conversion, capability for an internal reforming, and a very low environmental impact. However, the performance of the molten carbonate fuel cell is limited by the oxygen reduction reaction and the cell life time is limited by the stability of the cathode material. An elucidation of oxygen reduction reaction in molten alkali carbonate is essential because overpotential losses in the molten carbonate fuel cell are considerably greater at the oxygen cathode than at the fuel anode. Oxygen reduction on a fully-immersed gold electrode in a lithium carbonate melt was investigated by electrochemical impedance spectroscopy and cyclic voltammetry to determine electrode kinetic and mass transfer parameters. The dependences of electrode kinetic and mass transfer parameters on gas composition and temperature were examined to determine the reaction orders and the activation energies. The results showed that oxygen reduction in a pure lithium carbonate melt occurs via the peroxide mechanism. A mass transfer parameter, D{sub O}{sup 1/2}C{sub O}, estimated by the cyclic voltammetry concurred with that calculated by the EIS technique. The temperature dependence of the exchange current density and …
Date: July 7, 1992
Creator: Appleby, A. J. & White, R. E.
Object Type: Report
System: The UNT Digital Library
Oxygen electrode reaction in molten carbonate fuel cells. Final report, September 15, 1987--September 14, 1990 (open access)

Oxygen electrode reaction in molten carbonate fuel cells. Final report, September 15, 1987--September 14, 1990

Molten carbonate fuel cell system is a leading candidate for the utility power generation because of its high efficiency for fuel to AC power conversion, capability for an internal reforming, and a very low environmental impact. However, the performance of the molten carbonate fuel cell is limited by the oxygen reduction reaction and the cell life time is limited by the stability of the cathode material. An elucidation of oxygen reduction reaction in molten alkali carbonate is essential because overpotential losses in the molten carbonate fuel cell are considerably greater at the oxygen cathode than at the fuel anode. Oxygen reduction on a fully-immersed gold electrode in a lithium carbonate melt was investigated by electrochemical impedance spectroscopy and cyclic voltammetry to determine electrode kinetic and mass transfer parameters. The dependences of electrode kinetic and mass transfer parameters on gas composition and temperature were examined to determine the reaction orders and the activation energies. The results showed that oxygen reduction in a pure lithium carbonate melt occurs via the peroxide mechanism. A mass transfer parameter, D{sub O}{sup 1/2}C{sub O}, estimated by the cyclic voltammetry concurred with that calculated by the EIS technique. The temperature dependence of the exchange current density and …
Date: July 7, 1992
Creator: Appleby, A. J. & White, R. E.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
A miniature inexpensive, oxygen sensing element (open access)

A miniature inexpensive, oxygen sensing element

An exhaustive study was conducted to determine the feasibility of Nernst-type oxygen sensors based on ceramics containing Bi{sub 2}O{sub 3}. The basic sensor design consisted of a ceramic sensing module sealed into a metal tube. The module accommodated an internal heater and thermocouple. Thermal-expansion-matched metals, adhesives, and seals were researched and developed, consistent with sequential firings during sensor assembly. Significant effort was devoted to heater design/testing and to materials' compatibility with Pt electrodes. A systematic approach was taken to develop all sensor components which led to several design modifications. Prototype sensors were constructed and exhaustively tested. It is concluded that development of Nerst-type oxygen sensors based on Bi{sub 2}O{sub 3} will require much further effort and application of specialized technologies. However, during the course of this 3-year program much progress was reported in the literature on amperometric-type oxygen sensors, and a minor effort was devoted here to this type of sensor based on Bi{sub 2}O{sub 3}. These studies were made on Bi{sub 2}O{sub 3}-based ceramic samples in a multilayer-capacitor-type geometry and amperometric-type oxygen sensing was demonstrated at very low temperatures ({approximately} 160{degree}C). A central advantage here is that these types of sensors can be mass-produced very inexpensively ({approximately} 20--50 cents …
Date: October 7, 1991
Creator: Arenz, R. W.
Object Type: Report
System: The UNT Digital Library
Modeling A.C. Electronic Transport through a Two-Dimensional Quantum Point Contact (open access)

Modeling A.C. Electronic Transport through a Two-Dimensional Quantum Point Contact

We present the results on the a.c. transport of electrons moving through a two-dimensional (2D) semiconductor quantum point contact (QPC). We concentrate our attention on the characteristic properties of the high frequency admittance ({omega}{approximately}0 - 50 GHz), and on the oscillations of the admittance in the vicinity of the separatrix (when a channel opens or closes), in presence of the relaxation effects. The experimental verification of such oscillations in the admittance would be a strong confirmation of the semi-classical approach to the a.c. transport in a QPC, in the separatrix region.
Date: December 7, 1998
Creator: Aronov, I. E.; Beletskii, N. N.; Berman, G. P.; Campbell, D. K.; Doolen, G. D. & Dudiy, S. V.
Object Type: Article
System: The UNT Digital Library
Magnetospheric structure of rotation powered pulsars (open access)

Magnetospheric structure of rotation powered pulsars

I survey recent theoretical work on the structure of the magnetospheres of rotation powered pulsars, within the observational constraints set by their observed spindown, their ability to power synchrotron nebulae and their ability to produce beamed collective radio emission, while putting only a small fraction of their energy into incoherent X- and gamma radiation. I find no single theory has yet given a consistent description of the magnetosphere, but I conclude that models based on a dense outflow of pairs from the polar caps, permeated by a lower density flow of heavy ions, are the most promising avenue for future research. 106 refs., 4 figs., 2 tabs.
Date: January 7, 1991
Creator: Arons, J. (California Univ., Berkeley, CA (USA) California Univ., Livermore, CA (USA). Inst. of Geophysics and Planetary Physics)
Object Type: Article
System: The UNT Digital Library