A novel synthesis of polyesters containing hexa-(tert-butylhydroquinone)cyclotriphosphazene (open access)

A novel synthesis of polyesters containing hexa-(tert-butylhydroquinone)cyclotriphosphazene

The majority of polyphosphazene material research has concentrated on the linear polymer configuration. However, this represents only one of three potential backbone configurations for phosphazenes. Linear polymers are formed either directly from phosphorus and nitrogen containing precursors or from the ring opening polymerization of hexachlorocyclotriphosphazene. Two other backbone structures can be formed from hexachlorocyclotriphosphazene cyclolinear and cyclomatrix. Cyclolinear are the least studied due to synthetic difficulty. Cyclomatrix polymers represent a more facile method for forming non-linear phosphazenes.
Date: March 26, 2000
Creator: Stewart, F. F.; Luther, T. A.; Harrup, M. K. & Lash, R. P.
System: The UNT Digital Library
High Luminosity Polarized Proton Collisions at RHIC (open access)

High Luminosity Polarized Proton Collisions at RHIC

The Brookhaven Relativistic Heavy Ion Collider (RHIC) provides the unique opportunity to collide polarized proton beams at a center-of-mass energy of up to 500 GeV and luminosities of up to 2 x 10{sup 32} cm{sup {minus}2} s{sup {minus}1}. Such high luminosity and high energy polarized proton collisions will open up the possibility of studying spin effects in hard processes. However, the acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. After successful operation of RHIC with gold beams polarized protons from the AGS have been successfully injected into RHIC and accelerated using a full Siberian snakes built from four superconducting helical dipoles. A new high energy proton polarimeter was also successfully commissioned. Operation with two snakes per RHIC ring is planned for next year.
Date: March 26, 2001
Creator: Roser, T.
System: The UNT Digital Library
Status Report on the Six-Month Study on High Energy Muon Colliders. (open access)

Status Report on the Six-Month Study on High Energy Muon Colliders.

The structure, study topics, straw-man muon collider parameter sets and technical challenges for ''Six-Month Study on High Energy Muon Colliders: Oct'00-Apr'0l'' have been summarized at one month from completion of the study. The extremely high constituent particle energies and luminosities of the parameter sets presented in table 1 continue to suggest that muon colliders could play a central role in exploring and extending the HEP energy frontier. The study has already resulted in encouraging progress in areas such as the final focus lattice design and cost-efficient acceleration.
Date: March 26, 2001
Creator: King, B. J.
System: The UNT Digital Library
Swelling of Uranium Alloys at High Exposures (open access)

Swelling of Uranium Alloys at High Exposures

This reports summarizes the results of postirradiation examinations of a series of unrestrained dilute uranium alloy specimens irradiated to exposures up to 13,000 MWD/T in NaK-containing stainless steel capsules.
Date: March 26, 2001
Creator: McDonell, W.R.
System: The UNT Digital Library
High spatial resolution grain orientation and strain mapping in thin films using polychromatic submicron X-ray diffraction (open access)

High spatial resolution grain orientation and strain mapping in thin films using polychromatic submicron X-ray diffraction

The availability of high brilliance synchrotron sources, coupled with recent progress in achromatic focusing optics and large area 2D detector technology, have allowed us to develop an X-ray synchrotron technique capable of mapping orientation and strain/stress in polycrystalline thin films with submicron spatial resolution. To demonstrate the capabilities of this instrument, we have employed it to study the microstructure of aluminum thin film structures at the granular and subgranular level. Owing to the relatively low absorption of X-rays in materials, this technique can be used to study passivated samples, an important advantage over most electron probes given the very different mechanical behavior of buried and unpassivated materials.
Date: March 26, 2002
Creator: Tamura, N.; MacDowell, A. A.; Celestre, R. S.; Padmore, H. A.; Valek, B. C.; Bravman, J. C. et al.
System: The UNT Digital Library
Materials for solid state lighting (open access)

Materials for solid state lighting

Dramatic improvement in the efficiency of inorganic and organic light emitting diodes (LEDs and OLEDs) within the last decade has made these devices viable future energy efficient replacements for current light sources. However, both technologies must overcome major technical barriers, requiring significant advances in material science, before this goal can be achieved. Attention will be given to each technology associated with the following major areas of material research: (1) material synthesis, (2) process development, (3) device and defect physics, and (4) packaging. The discussion on material synthesis will emphasize the need for further development of component materials, including substrates and electrodes, necessary for improving device performance. The process technology associated with the LEDs and OLEDs is very different, but in both cases it is one factor limiting device performance. Improvements in process control and methodology are expected to lead to additional benefits of higher yield, greater reliability and lower costs. Since reliability and performance are critical to these devices, an understanding of the basic physics of the devices and device failure mechanisms is necessary to effectively improve the product. The discussion will highlight some of the more basic material science problems remaining to be solved. In addition, consideration will be …
Date: March 26, 2002
Creator: Johnson, S.G. & Simmons, J.A.
System: The UNT Digital Library
Analyzing water/wastewater infrastructure interdependencies. (open access)

Analyzing water/wastewater infrastructure interdependencies.

This paper describes four general categories of infrastructure interdependencies (physical, cyber, geographic, and logical) as they apply to the water/wastewater infrastructure, and provides an overview of one of the analytic approaches and tools used by Argonne National Laboratory to evaluate interdependencies. Also discussed are the dimensions of infrastructure interdependency that create spatial, temporal, and system representation complexities that make analyzing the water/wastewater infrastructure particularly challenging. An analytical model developed to incorporate the impacts of interdependencies on infrastructure repair times is briefly addressed.
Date: March 26, 2002
Creator: Gillette, J. L.; Fisher, R. E.; Peerenboom, J. P. & Whitfield, R. G.
System: The UNT Digital Library
Dynamic effects in fragmentation reactions. (open access)

Dynamic effects in fragmentation reactions.

Fragmentation reactions offer a useful tool to study the spectroscopy of halo nuclei, but the large extent of the halo wave function makes the reaction theory more difficult. The simple reaction models based on the eikonal approximation for the nuclear interaction or first-order perturbation theory for the Coulomb interaction have systematic errors that they investigate here, comparing to the predictions of complete dynamical calculations. They find that stripping probabilities are underpredicted by the eikonal model, leading to extracted spectroscopy strengths that are two large. In contrast, the Coulomb excitation is overpredicted by the simple theory. They attribute this to a screening effect, as is well known in the Barkas effect on stopping powers. The errors decrease with beam energy as E{sub beam}{sup -1}, and are not significant at beam energies above 50 MeV/u. At lower beam energies, the effects should be taken into account when extracting quantitative spectroscopic strengths.
Date: March 26, 2002
Creator: Bertsch, G. F. & Esbensen, H.
System: The UNT Digital Library
MESQUITE design : issues in the development of a mesh quality improvement toolkit. (open access)

MESQUITE design : issues in the development of a mesh quality improvement toolkit.

Poor mesh quality is known to adversely affect both solution efficiency and accuracy. There has been considerable research on a wide variety of mesh improvement algorithms, but the impact of these algorithms on applications has been limited because they are typically embedded in particular meshing software packages. To rectify this situation, they are developing a stand-alone mesh quality improvement toolkit called MESQUITE. In this paper, the authors describe the motivation, goals, and design of MESQUITE and give some computational results using the underlying algorithms that show the benefit of such a package.
Date: March 26, 2002
Creator: Freitag, L.; Leurent, T.; Knupp, P. & Melander, D.
System: The UNT Digital Library
Creating interoperable meshing and discretization software : the terascale simulation tools and technology center. (open access)

Creating interoperable meshing and discretization software : the terascale simulation tools and technology center.

The authors present an overview of the technical objectives of the Terascale Simulation Tools and Technologies center. The primary goal of this multi-institution collaboration is to develop technologies that enable application scientists to easily use multiple mesh and discretization strategies within a single simulation on terascale computers. The discussion focuses on the efforts to create interoperable mesh generation tools, high-order discretization techniques, and adaptive meshing strategies.
Date: March 26, 2002
Creator: Brown, D.; Freitag, L. & Glimm, J.
System: The UNT Digital Library
Active control for turbulent premixed flame simulations (open access)

Active control for turbulent premixed flame simulations

Many turbulent premixed flames of practical interest are statistically stationary. They occur in combustors that have anchoring mechanisms to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity that is prohibitive for detailed computational studies of turbulent flame dynamics. As a result, typical detailed simulations are performed in simplified model configurations such as decaying isotropic turbulence or inflowing turbulence. In these configurations, the turbulence seen by the flame either decays or, in the latter case, increases as the flame accelerates toward the turbulent inflow. This limits the duration of the eddy evolutions experienced by the flame at a given level of turbulent intensity, so that statistically valid observations cannot be made. In this paper, we apply a feedback control to computationally stabilize an otherwise unstable turbulent premixed flame in two dimensions. For the simulations, we specify turbulent in flow conditions and dynamically adjust the integrated fueling rate to control the mean location of the flame in the domain. We outline the numerical procedure, and illustrate the behavior of the control algorithm. We use the simulations to study the propagation and the local chemical variability of turbulent flame chemistry.
Date: March 26, 2004
Creator: Bell, John B.; Day, Marcus S.; Grcar, Joseph F. & Lijewski, Michael J.
System: The UNT Digital Library
Reconstruction of mechanically recorded sound by image processing (open access)

Reconstruction of mechanically recorded sound by image processing

Audio information stored in the undulations of grooves in a medium such as a phonograph record may be reconstructed, with no or minimal contact, by measuring the groove shape using precision metrology methods and digital image processing. The effects of damage, wear, and contamination may be compensated, in many cases, through image processing and analysis methods. The speed and data handling capacity of available computing hardware make this approach practical. Various aspects of this approach are discussed. A feasibility test is reported which used a general purpose optical metrology system to study a 50 year old 78 r.p.m. phonograph record. Comparisons are presented with stylus playback of the record and with a digitally re-mastered version of the original magnetic recording. A more extensive implementation of this approach, with dedicated hardware and software, is considered.
Date: March 26, 2003
Creator: Fadeyev, Vitaliy & Haber, Carl
System: The UNT Digital Library
The Mercury Laser System-A scaleable average-power laser for fusion and beyond (open access)

The Mercury Laser System-A scaleable average-power laser for fusion and beyond

Nestled in a valley between the whitecaps of the Pacific and the snowcapped crests of the Sierra Nevada, Lawrence Livermore National Laboratory (LLNL) is home to the nearly complete National Ignition Facility (NIF). The purpose of NIF is to create a miniature star-on demand. An enormous amount of laser light energy (1.8 MJ in a pulse that is 20 ns in duration) will be focused into a small gold cylinder approximately the size of a pencil eraser. Centered in the gold cylinder (or hohlraum) will be a nearly perfect sphere filled with a complex mixture of hydrogen gas isotopes that is similar to the atmosphere of our Sun. During experiments, the laser light will hit the inside of the gold cylinder, heating the metal until it emits X-rays (similar to how your electric stove coil emits visible red light when heated). The X-rays will be used to compress the hydrogen-like gas with such pressure that the gas atoms will combine or 'fuse' together, producing the next heavier element (helium) and releasing energy in the form of energetic particles. 2010 will mark the first credible attempt at this world-changing event: the achievement of fusion energy 'break-even' on Earth using NIF, the …
Date: March 26, 2008
Creator: Ebbers, C A & Moses, E I
System: The UNT Digital Library
Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties (open access)

Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties

The feasibility to coat large SNF/HLW containers with a structurally amorphous material (SAM) was demonstrated on sub-scale models fabricated from Type 316L stainless steel. The sub-scale model were coated with SAM 1651 material using kerosene high velocity oxygen fuel (HVOF) torch to thicknesses ranging from 1 mm to 2 mm. The process parameters such as standoff distance, oxygen flow, and kerosene flow, were optimized in order to improve the corrosion properties of the coatings. Testing in an electrochemical cell and long-term exposure to a salt spray environment were used to guide the selection of process parameters.
Date: March 26, 2008
Creator: Beardsley, M B
System: The UNT Digital Library
Wear Resistant Amorphous and Nanocomposite Coatings (open access)

Wear Resistant Amorphous and Nanocomposite Coatings

Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.
Date: March 26, 2008
Creator: Racek, O.
System: The UNT Digital Library
Energy Amplification and Beam Bunching in a Pulse Line IonAccelerator (open access)

Energy Amplification and Beam Bunching in a Pulse Line IonAccelerator

None
Date: March 26, 2006
Creator: Roy, Prabir K.; Waldron, William L.; Yu, Simon S.; Coleman,Joshua E.; Henestroza, Enrique; Grote, David P. et al.
System: The UNT Digital Library
Quarkonia Correlators and Spectral Functions From Lattice Qcd. (open access)

Quarkonia Correlators and Spectral Functions From Lattice Qcd.

None
Date: March 26, 2006
Creator: Petreczky, P.
System: The UNT Digital Library
SAFETY INSTRUMENTED FUNCTIONS AS CRITICALITY DEFENSES (open access)

SAFETY INSTRUMENTED FUNCTIONS AS CRITICALITY DEFENSES

The objective of this paper is to share the SRS methodology for identifying the reliability requirements and documenting the expected performance of Safety Instrumented Functions (SIFs) used as criticality defenses. Nuclear Criticality SIFs are comprised of sensors, logic solvers, and final control elements, which may be either automatic or manual, to detect a process hazard and respond to prevent a criticality. The Savannah River Site (SRS) has invoked the chemical process industry safety standard (ANSI/ISA 84.00.01) for the design of safety significant instrumented systems. The ISA standard provides a graded approach to design based on the amount of risk reduction that is required of an SIF. SRS is embarking on application of this standard to nuclear criticality defenses, thus integrating criticality safety requirements with verifiable design methodology. Per the DOE G 421.1-1 discussion of the double contingency principle, guidance for a single contingency barrier includes, ''The estimated probability that the control will fail (when called upon for protection) is not greater than 1 in 100 demands''. The application of this standard to nuclear criticality SIFs will provide clear requirements in terms of safety availability and testing to assure that the instrumented criticality system as designed, installed, and maintained will meet …
Date: March 26, 2007
Creator: Suttinger, L & William Hearn, W
System: The UNT Digital Library
Cosmological Constraints From SDSS MaxBCG Cluster Abundances (open access)

Cosmological Constraints From SDSS MaxBCG Cluster Abundances

We perform a maximum likelihood analysis of the cluster abundance measured in the SDSS using the maxBCG cluster finding algorithm. Our analysis is aimed at constraining the power spectrum normalization {sigma}{sub 8}, and assumes flat cosmologies with a scale invariant spectrum, massless neutrinos, and CMB and supernova priors {Omega}{sub m}h{sup 2} = 0.128 {+-} 0.01 and h = 0.72 {+-} 0.05 respectively. Following the method described in the companion paper Rozo et al. (2007), we derive {sigma}{sub 8} = 0.92 {+-} 0.10 (1{sigma}) after marginalizing over all major systematic uncertainties. We place strong lower limits on the normalization, {sigma}{sub 8} > 0.76 (95% CL) (> 0.68 at 99% CL). We also find that our analysis favors relatively low values for the slope of the Halo Occupation Distribution (HOD), {alpha} = 0.83 {+-} 0.06. The uncertainties of these determinations will substantially improve upon completion of an ongoing campaign to estimate dynamical, weak lensing, and X-ray cluster masses in the SDSS maxBCG cluster sample.
Date: March 26, 2007
Creator: Rozo, Eduardo; Wechsler, Risa H.; Koester, Benjamin P.; McKay, Timothy A.; Evrard, August E.; Johnston, David et al.
System: The UNT Digital Library
Development of Hfe Sections of Dg-1145. (open access)

Development of Hfe Sections of Dg-1145.

For the licensing of the current fleet of commercial nuclear power plants (NPPs), the Nuclear Regulatory Commission (NRC) used two key documents, NUREG-0800 and Regulatory Guide (RG) 1.70. RG 1.70 provided guidance to applicants on the contents needed in their Safety Analysis Reports (SARs) submitted as part of their application to construct or operate an NPP. NUREG-0800, the NRC Standard Review Plan (SRP), provides guidance to the NRR staff reviewers on performing their safety reviews of these applications. As part of the preparation for a new wave of improved NPP designs the NRC is in the process of updating the SRP and is also developing a new RG designated as draft RG or DG-1145, ''Combined License Applications for Nuclear Power Plants (LWR Edition).'' This will eventually become RG 1.206 and will take the place of RG 1.70. This will provide guidance for combined license (COL) applicants, as well as for other 10CFR Part 52 variations that are permitted.
Date: March 26, 2007
Creator: Higgins, J. C.; Ohara, J. M. & Bongarra, J.
System: The UNT Digital Library
On the speed of gravity and the nu/c corrections to the Shapirotime delay (open access)

On the speed of gravity and the nu/c corrections to the Shapirotime delay

I compute the v/c correction to the gravitational time delayfor light passing by a massive object moving with speed v, and I finddisagreement with previously published results. It is also argued thatthe speed of gravity formula that was recently used in the conjunction ofJupiter and quasar J0842+1845 is frame dependent.
Date: March 26, 2003
Creator: Samuel, Stuart
System: The UNT Digital Library
LATTICE SIMULATIONS OF THE THERMODYNAMICS OF STRONGLY INTERACTING ELEMENTARY PARTICLES AND THE EXPLORATION OF NEW PHASES OF MATTER IN RELATIVISTIC HEAVY ION COLLISIONS. (open access)

LATTICE SIMULATIONS OF THE THERMODYNAMICS OF STRONGLY INTERACTING ELEMENTARY PARTICLES AND THE EXPLORATION OF NEW PHASES OF MATTER IN RELATIVISTIC HEAVY ION COLLISIONS.

At high temperatures or densities matter formed by strongly interacting elementary particles (hadronic matter) is expected to undergo a transition to a new form of matter--the quark gluon plasma--in which elementary particles (quarks and gluons) are no longer confined inside hadrons but are free to propagate in a thermal medium much larger in extent than the typical size of a hadron. The transition to this new form of matter as well as properties of the plasma phase are studied in large scale numerical calculations based on the theory of strong interactions--Quantum Chromo Dynamics (QCD). Experimentally properties of hot and dense elementary particle matter are studied in relativistic heavy ion collisions such as those currently performed at the relativistic heavy ion collider (RHIC) at BNL. We review here recent results from studies of thermodynamic properties of strongly interacting elementary particle matter performed on Teraflops-Computer. We present results on the QCD equation of state and discuss the status of studies of the phase diagram at non-vanishing baryon number density.
Date: March 26, 2006
Creator: Karsch, F.
System: The UNT Digital Library
Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites (open access)

Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential …
Date: March 26, 2007
Creator: Newsome G, Snead L, Hinoki T, Katoh Y, Peters D
System: The UNT Digital Library
Optically-Selected Cluster Catalogs As a Precision Cosmology Tool (open access)

Optically-Selected Cluster Catalogs As a Precision Cosmology Tool

We introduce a framework for describing the halo selection function of optical cluster finders. We treat the problem as being separable into a term that describes the intrinsic galaxy content of a halo (the Halo Occupation Distribution, or HOD) and a term that captures the effects of projection and selection by the particular cluster finding algorithm. Using mock galaxy catalogs tuned to reproduce the luminosity dependent correlation function and the empirical color-density relation measured in the SDSS, we characterize the maxBCG algorithm applied by Koester et al. to the SDSS galaxy catalog. We define and calibrate measures of completeness and purity for this algorithm, and demonstrate successful recovery of the underlying cosmology and HOD when applied to the mock catalogs. We identify principal components--combinations of cosmology and HOD parameters--that are recovered by survey counts as a function of richness, and demonstrate that percent-level accuracies are possible in the first two components, if the selection function can be understood to {approx} 15% accuracy.
Date: March 26, 2007
Creator: Rozo, Eduardo; /Ohio State U. /Chicago U. /KICP, Chicago; Wechsler, Risa H.; /KICP, Chicago /KIPAC, Menlo Park; Koester, Benjamin P.; /Michigan U. /Chicago U., Astron. Astrophys. Ctr. et al.
System: The UNT Digital Library