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A crystalline quark-hadron mixed phase in neutron stars (open access)

A crystalline quark-hadron mixed phase in neutron stars

The mixed phase of a substance undergoing a first order phase transition has entirely different behavior according as the substance has more than one conserved charge or only one, as in the text book examples. In the latter case the pressure and nature of the phases are constants throughout the coexistence phase. For systems with more than one conserved charge (or independent component) we prove two theorems: (1) The pressure and the nature of the phases in equilibrium change continuously as the proportion of the phases varies from one pure phase to the other. (2) If one of the conserved charges is the Coulomb force, an intermediate-range order will be created by the competition between Coulomb and surface interface energy. Their sum is minimized when the coexistence phase assumes a Coulomb lattice of one phase immersed in the other. The geometry will vary continuously as the proportion of phases. We illustrate the theorems for a simple description of the hadron to quark phase transition in neutron stars and find a crystalline phase many kilometers thick. However the theorems are general and pertain to chemical mixtures, nuclear systems, either static as in stars or dynamic as in collisions, and have possible …
Date: August 31, 1994
Creator: Glendenning, N. K.
System: The UNT Digital Library
A probabilistic risk assessment of the LLNL Plutonium facility`s evaluation basis fire operational accident (open access)

A probabilistic risk assessment of the LLNL Plutonium facility`s evaluation basis fire operational accident

The Lawrence Livermore National Laboratory (LLNL) Plutonium Facility conducts numerous involving plutonium to include device fabrication, development of fabrication techniques, metallurgy research, and laser isotope separation. A Safety Analysis Report (SAR) for the building 332 Plutonium Facility was completed rational safety and acceptable risk to employees, the public, government property, and the environment. This paper outlines the PRA analysis of the Evaluation Basis Fire (EDF) operational accident. The EBF postulates the worst-case programmatic impact event for the Plutonium Facility.
Date: August 31, 1994
Creator: Brumburgh, G.
System: The UNT Digital Library
Gyrokinetic and global fluid simulations of tokamak microturbulence and transport (open access)

Gyrokinetic and global fluid simulations of tokamak microturbulence and transport

Results are presented from the first systematic nonlinear kinetic simulation study of the swings and parameter dependences of toroidal ion-temperature-gradient (ITG) turbulence and transport, and from the first such study that includes sheared toroidal flows. Key results include the observation of clear gyroBohm scaling of the turbulent transport and of a surprisingly weak dependence of the transport on toroidal flow shear. Based on the simulation results, a parameterization of the transport is given that includes the dependence on all of the relevant physical parameters. The transition from local to nonlocal transport as a function of the profile scale length has been investigated using two-dimensional global fluid simulations of dissipative drift-wave turbulence. Local gyroBohm scaling is observed, except at very short profile scale lengths.
Date: August 30, 1994
Creator: Dimits, A. M.; Byers, J. A.; Williams, T. J.; Cohen, B. I.; Xu, W. Q.; Cohen, R. H. et al.
System: The UNT Digital Library
Meshes: The next generation (open access)

Meshes: The next generation

Building complex meshes for large-scale numerical simulations presents immense difficulties in exploiting high-performance computers. Industry and research leaders will describe the current state of the art for generating meshes for such large scientific problems. This will be followed by a panel and general audience discussion of the algorithmic and architectural issues surrounding the generation of meshes with10{sup 7} to 10{sup 9} grid points. (Note: The terms ``mesh`` and ``grid`` are used interchangeably in the literature.)
Date: August 29, 1994
Creator: Christon, M.; Hardin, D.; Compton, J. & Zosel, M.
System: The UNT Digital Library
Determination of the concentration and isotopic composition of uranium in environmental air filters (open access)

Determination of the concentration and isotopic composition of uranium in environmental air filters

For many years, Lawrence Livermore National Laboratory has collected monthly air-particulate filter samples from a variety of environmental monitoring stations on and off site. Historically the concentration and isotopic composition of uranium collected on these filters was determined by isotope dilution using a {sup 233}U spike and thermal ionization mass spectrometry (TIMS). For samples containing as little as 10 nanograms of uranium, ICP-MS is now used to make these measurements to the required level of precision, about 5% in the measured 235/238 and 233/238. Unless particular care is taken to control bias in the mass filter, variable mass bias limits accuracy to a few percent. Measurements of the minor isotopes 236 (if present) and 234 are also possible and provide useful information for identifying the source of the uranium. The advantage of ICP-MS is in rapid analysis, {approximately}12 minutes of instrument time per sample.
Date: August 26, 1994
Creator: Russ, G. P., III & Bazan, J. M.
System: The UNT Digital Library
Wentzel-Bardeen singularity in coupled Luttinger liquids: Transport properties (open access)

Wentzel-Bardeen singularity in coupled Luttinger liquids: Transport properties

The recent progress on 1 D interacting electrons systems and their applications to study the transport properties of quasi one dimensional wires is reviewed. We focus on strongly correlated elections coupled to low energy acoustic phonons in one dimension. The exponents of various response functions are calculated, and their striking sensitivity to the Wentzel-Bardeen singularity is discussed. For the Hubbard model coupled to phonons the equivalent of a phase diagram is established. By increasing the filling factor towards half filling the WB singularity is approached. This in turn suppresses antiferromagnetic fluctuations and drives the system towards the superconducting regime, via a new intermediate (metallic) phase. The implications of this phenomenon on the transport properties of an ideal wire as well as the properties of a wire with weak or strong scattering are analyzed in a perturbative renormalization group calculation. This allows to recover the three regimes predicted from the divergence criteria of the response functions.
Date: August 26, 1994
Creator: Martin, T.
System: The UNT Digital Library
Magnetic excitations in a random exchange system Fe{sub x}Mn{sub 1-x}TiO{sub 3} (open access)

Magnetic excitations in a random exchange system Fe{sub x}Mn{sub 1-x}TiO{sub 3}

In order to examine the influence of exchange frustration on spin wave excitations, inelastic neutron scattering experiments have been performed on a random exchange system Fe{sub x}Mn{sub l-x}TiO{sub 3} with x = 0.00, 0.10, 0.25 and 0.33. For all three mixed systems, the magnetic excitation spectra consist of two components: a well-defined spin wave component and a broad damped component. The latter can be well fitted to a spectral weight function for a damped harmonic oscillator.
Date: August 24, 1994
Creator: Kawano, H.; Yoshizawa, H.; Nicklow, R. M. & Ito, A.
System: The UNT Digital Library
Multidimensional discretization of conservation laws for unstructured polyhedral grids (open access)

Multidimensional discretization of conservation laws for unstructured polyhedral grids

To the extent possible, a discretized system should satisfy the same conservation laws as the physical system. The author considers the conservation properties of a staggered-grid Lagrange formulation of the hydrodynamics equations (SGH) which is an extension of a ID scheme due to von Neumann and Richtmyer (VNR). The term staggered refers to spatial centering in which position, velocity, and kinetic energy are centered at nodes, while density, pressure, and internal energy are at cell centers. Traditional SGH formulations consider mass, volume, and momentum conservation, but tend to ignore conservation of total energy, conservation of angular momentum, and requirements for thermodynamic reversibility. The author shows that, once the mass and momentum discretizations have been specified, discretization for other quantities are dictated by the conservation laws and cannot be independently defined. The spatial discretization method employs a finite volume procedure that replaces differential operators with surface integrals. The method is appropriate for multidimensional formulations (1D, 2D, 3D) on unstructured grids formed from polygonal (2D) or polyhedral (3D) cells. Conservation equations can then be expressed in conservation form in which conserved currents are exchanged between control volumes. In addition to the surface integrals, the conservation equations include source terms derived from physical …
Date: August 22, 1994
Creator: Burton, D.E.
System: The UNT Digital Library
Unique microchannel plate process doubles MCPI resolution (open access)

Unique microchannel plate process doubles MCPI resolution

Applying a dielectric layer to the output of a microchannel plate (MCP) has allowed the screen voltage of a sealed microchannel-plate intensifier tube (MCPI) to be raised to over 10 kV, producing a field strength of 36 kV/mm without any detectable field emission or breakdown of the MCP/screen gap. Tube resolution exceeded 16 lp/mm at 50% modulation. Breakdown is higher in a dielectric than in a vacuum. In a concept being patented by Gary Power, a few-{mu}m-thick layer of a dielectric was sputtered onto the output surface of an 18-mm MCP, which was incorporated into a tube under a contract for four tube starts. This process is applicable to any device incorporating a proximity-focused MCP and screen, including streak tubes and gated MCP x-ray imagers. Other improvements discussed include a patented use of a collimator for eliminating the electrons that are elastically scattered from the screen. This method also provides for further improvements in screen gap limited resolution to any desired degree by eliminating electrons with high transverse energy. This occurs at the expense of output brightness, which can be recovered through an appropriate increase in screen voltage.
Date: August 22, 1994
Creator: Thomas, S. & Power, G.
System: The UNT Digital Library
The influence of chemistry and microstructure on the fracture toughness of V-V{sub 3}Si in-situ composites (open access)

The influence of chemistry and microstructure on the fracture toughness of V-V{sub 3}Si in-situ composites

The room temperature fracture behavior is described for ductile-phase toughened V-V{sub 3}Si in-situ composites produced by arc melting (AM), cold-crucible induction melting (IM), and cold-crucible directional solidification (DS). Composites were produced containing a wide range of microstructures, interstitial impurity contents, and volume fractions of the ductile V-Si solid solution phase, denoted (V). The fracture toughness of these composites generally increases as the volume fraction of (V) increases. For a given volume fraction of (V), the fracture toughness increases with decreasing {open_quotes}effective{close_quotes} interstitial impurity content, [I]=[N]+1.3[O]+9[H]. In eutectic composites, as [I] decreases from 1400 ppm (AM) to 400 ppm (IM), the fracture toughness increases from 10 to 20 MPa {radical}m. The fracture toughness of the V-V{sub 3}Si composites is further correlated with the mechanical properties of the component phases, SEM observations of the fracture surface characteristics, and electron back-scattering pattern measurements of the fracture facet crystallography. These correlations are discussed with respect to conventional ductile phase {open_quotes}bridging{close_quotes} theories.
Date: August 19, 1994
Creator: Henshall, G. A.; Strum, M. J.; Bewlay, B. P. & Sutliff, J. A.
System: The UNT Digital Library
[Teen who pled homosexual assault defense certified to stand trial as adult] (open access)

[Teen who pled homosexual assault defense certified to stand trial as adult]

A document pertaining to a 16-year-old standing in trial as an adult for the murder of John Anthony Burwell.
Date: August 19, 1994
Creator: Stehle, Glenn
System: The UNT Digital Library
Detection of concealed mercury with thermal neutrons (open access)

Detection of concealed mercury with thermal neutrons

In the United States today, governments at all levels and the citizenry are paying increasing attention to the effects, both real and hypothetical, of industrial activity on the environment. Responsible modem industries, reflecting this heightened public and regulatory awareness, are either substituting benign materials for hazardous ones, or using hazardous materials only under carefully controlled conditions. In addition, present-day environmental consciousness dictates that we deal responsibly with legacy wastes. The decontamination and decommissioning (D&D) of facilities at which mercury was used or processed presents a variety of challenges. Elemental mercury is a liquid at room temperature and readily evaporates in air. In large mercury-laden buildings, droplets may evaporate from one area only to recondense in other cooler areas. The rate of evaporation is a function of humidity and temperature; consequently, different parts of a building may be sources or sinks of mercury at different times of the day or even the year. Additionally, although mercury oxidizes in air, the oxides decompose upon heating. Hence, oxides contained within pipes or equipment, may be decomposed when those pipes and equipment are cut with saws or torches. Furthermore, mercury seeps through the pores and cracks in concrete blocks and pads, and collects as …
Date: August 18, 1994
Creator: Bell, Z.W.
System: The UNT Digital Library
EGS4 in `94: A decade of enhancements (open access)

EGS4 in `94: A decade of enhancements

This paper presents an overview of the developments made to the EGS4 code over the past decade. This code is a Monte Carlo code developed to study electron-photon transport properties. It is widely used, in particular in the medical physics field, it has been updated, expanded, benchmarked, and applied to a wide array of problems. The paper covers precursors to this code, a basic snapshop of its physics and calculation methods, and an overview of how it has been expanded during the past decade.
Date: August 18, 1994
Creator: Nelson, W. R.; Bielajew, A. F.; Rogers, D. W. O. & Hirayama, H.
System: The UNT Digital Library
Estimation of monetary values of air pollutant emissions in various US areas (open access)

Estimation of monetary values of air pollutant emissions in various US areas

Two general methods of estimating monetary values of air pollutants are presented in this paper. The damage estimate method directly estimated, air pollutant by simulating air quality, identifying health and other welfare impacts damage values and valuing the identified impacts of air pollution, and valuing the identified impacts. Although the method is theoretically sound, many assumptions are involved in each of its estimation steps, and uncertainty exists in each step. The control cost estimate method estimates the marginal emission control cost, which represents the opportunity cost offset by emission reductions from some given control measures. Studies conducted to estimate emission values in US regions used either the damage estimate method or the control cost estimate method. Taking emission values estimated for some US air basins, this paper establishes regression relationships between emission values and total population and air pollutant concentrations. On the basis of the established relationships, both damage-based and control-cost-based emission values are estimated for 17 major US urban areas.
Date: August 17, 1994
Creator: Wang, M. Q. & Santini, D. J.
System: The UNT Digital Library
TPX magnet system status (open access)

TPX magnet system status

None
Date: August 17, 1994
Creator: Bulmer, R. H.; Chaplin, M. R. & Lang, D. D.
System: The UNT Digital Library
Design of the readout IC for the CDF SVX-II silicon strip detector (open access)

Design of the readout IC for the CDF SVX-II silicon strip detector

Future colliding beam runs at Fermi National Accelerator Laboratory will involve bunch spacings of protons and antiprotons at 132 ns intervals. Due to finite processing time, a pipelined architecture is needed to store events until a trigger decision can reach the detector. A single ported pipeline design has been implemented in a 1.2 micron rad soft CMOS technology and partially tested. Results are presented of the performance of that design. The chip supports a level 1 accept rate of 5 kHz. Because high statistics B physics experiments will require level 1 accept rates of 50 kHz, a new dual ported pipeline device has been proposed which would make the readout virtually deadtimeless for trigger rates approaching 50 kHz. The operation of the proposed deadtimeless device is explained.
Date: August 16, 1994
Creator: Huffman, B. T.
System: The UNT Digital Library
Statement by Dr. Kathleen C. Bailey before the Senate Armed Services Committee (open access)

Statement by Dr. Kathleen C. Bailey before the Senate Armed Services Committee

This paper presents the personal views of the author on the subject of the proposed Chemical Weapons Convention (CWC). She addresses here concerns about the national security issues which could result from ratification of this convention. She argues the convention alone is not likely to curtail production or availability of such items on the world market because of the relatively low cost. The treaty could thus put the country in a position less likely to protect itself, or adequately deal with such a threat.
Date: August 16, 1994
Creator: Bailey, K. C.
System: The UNT Digital Library
Purpose and methods of a Pollution Prevention Awareness Program (open access)

Purpose and methods of a Pollution Prevention Awareness Program

The purpose of the Pollution Prevention Awareness Program (PPAP), which is required by DOE Order 5400.1, is to foster the philosophy that prevention is superior to remediation. The goal of the program is to incorporate pollution prevention into the decision-making process at every level throughout the organization. The objectives are to instill awareness, disseminate information, provide training and rewards for identifying the true source or cause of wastes, and encourage employee participation in solving environmental issues and preventing pollution. PPAP at the Oak Ridge Y-12 Plant was created several years ago and continues to grow. We believe that we have implemented several unique methods of communicating environmental awareness to promote a more active work force in identifying ways of reducing pollution.
Date: August 15, 1994
Creator: Flowers, P. A.; Irwin, E. F. & Poligone, S. E.
System: The UNT Digital Library
Transformation behavior in Al{sub 2}O{sub 3}-ZrO{sub 2} ceramic composites (open access)

Transformation behavior in Al{sub 2}O{sub 3}-ZrO{sub 2} ceramic composites

Neutron powder diffraction was used to investigate the tetragonal to monoclinic transformation of ZrO{sub 2} in a A1{sub 2}O{sub 3}-ZrO{sub 2} ceramic composite containing 40 vol % tetragonal ZrO{sub 2}. The neutron diffraction data were analyzed using the Rietveld refinement technique, which allowed to determine the extent of the transformation as a function of temperature. The onset transformation temperature determined for this sample was 130 K. Below this temperature, the fraction of the monoclinic phase continued to increase to about 9 vol % at 80 K and remained constant for temperatures below 80 K. The calculated thermal expansion, using the refined lattice parameters, was found in excellent agreement with dilatometry data, confirming that the sharp increase in the thermal expansion upon cooling resulted from the tetragonal to monoclinic phase transformation in ZrO{sub 2}.
Date: August 15, 1994
Creator: Wang, X. L.; Fernandez-Baca, J. A.; Hubbard, C. R.; Alexander, K. B. & Becher, P. F.
System: The UNT Digital Library
Higher-order Lipatov kernels and the QCD Pomeron (open access)

Higher-order Lipatov kernels and the QCD Pomeron

Three closely related topics are covered. The derivation of O(g{sup 4}) Lipatov kernels in pure glue QCD. The significance of quarks for the physical Pomeron in QCD. The possible inter-relation of Pomeron dynamics with Electroweak symmetry breaking.
Date: August 12, 1994
Creator: White, A. R.
System: The UNT Digital Library
Use of the AIC with the EM algorithm: A demonstration of a probability model selection technique (open access)

Use of the AIC with the EM algorithm: A demonstration of a probability model selection technique

The problem of discriminating between two potential probability models, a Gaussian distribution and a mixture of Gaussian distributions, is considered. The focus of interest is a case where the models are potentially non-nested and the parameters of the mixture model are estimated through the EM algorithm. The AIC, which is frequently used as a criterion for discriminating between non-nested models, is modified to work with the EM algorithm and is shown to provide a model selection tool for this situation. A particular problem involving an infinite mixture distribution known as Middleton`s Class A model is used to demonstrate the effectiveness and limitations of this method. The problem involves a probability model for underwater noise due to distant shipping.
Date: August 12, 1994
Creator: Glosup, J. G. & Axelrod, M. C.
System: The UNT Digital Library
[Article from The Post Signal, August 11, 1994] (open access)

[Article from The Post Signal, August 11, 1994]

An article titled 'Local art program in fifth year' that was written for The Post-Signal newspaper. The article covers the NTIEVA program within Pilot Point's school district and how it has been implemented over the past five years.
Date: August 11, 1994
Creator: The Post-Signal
System: The UNT Digital Library
[The Post-Signal, August 11, 1994] (open access)

[The Post-Signal, August 11, 1994]

A clipping of articles from the 'Back-to-School' section of the newspaper The Post-Signal. The main article lists out the several programs in operation within the Pilot Point Elementary School, including the new UNT NTIEVA program funded by the Getty Foundation.
Date: August 11, 1994
Creator: The Post-Signal
System: The UNT Digital Library
[Press Release: ASPIRIN MAY INHIBIT HIV, RESEARCHERS SAY] (open access)

[Press Release: ASPIRIN MAY INHIBIT HIV, RESEARCHERS SAY]

Memo detailing the results of a study that found that asprin may inhibit HIV and prevent it from developing into AIDS.
Date: August 11, 1994
Creator: Reuters Limited
System: The UNT Digital Library