The 9977 General Purpose Fissile Package, A Replacement for the 6M Specification Package (open access)

The 9977 General Purpose Fissile Package, A Replacement for the 6M Specification Package

General Purpose Fissile Package is a robust, single containment package capable of transporting plutonium and uranium metals and oxides.
Date: January 13, 2006
Creator: Smith, Allen
Object Type: Report
System: The UNT Digital Library
An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry (open access)

An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry

One of the greatest societal challenges over the next decade is the production of cheap, renewable energy for the 10 billion people that inhabit the earth. This will require the development of various energy sources which will likely include fuels derived from methane, coal, and biomass and alternatives sources such as solar, wind and nuclear energy. One approach will be to synthesize gasoline and other fuels from simpler hydrocarbons such as CO derived from methane or other U.S. based sources such as coal. Syngas (CO and H{sub 2}) can be readily converted into higher molecular weight hydrocarbons through Fischer-Tropsch synthesis. Fischer-Tropsch (FT) synthesis involves the adsorption and the activation of CO and H{sub 2}, the subsequent propagation steps including hydrogenation and carbon-carbon coupling, followed by chain termination reactions. The current commercial catalysts are supported Co and Co-alloys particles. This project set out with the following objectives in mind: (1) understand the reaction mechanisms that control FT kinetics, (2) predict how the intrinsic metal-adsorbate bond affects the sequence of elementary steps in FT, (3) establish the effects of the reaction environment on catalytic activity and selectivity, (4) construct a first-principles based algorithm that can incorporate the detailed atomic surface structure and …
Date: September 11, 2006
Creator: Neurock, Matthew
Object Type: Report
System: The UNT Digital Library
An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry (open access)

An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry

One of the greatest societal challenges over the next decade is the production of cheap, renewable energy for the 10 billion people that inhabit the earth. This will require the development of various different energy sources potentially including fuels derived from methane, coal, and biomass and alternatives sources such as solar, wind and nuclear energy. One approach will be to synthesize gasoline and other fuels from simpler hydrocarbons such as CO derived from methane or other U.S. based sources such as coal. Syngas (CO and H{sub 2}) can be readily converted into higher molecular weight hydrocarbons through Fischer-Tropsch synthesis. Fischer-Tropsch synthesis involves the initiation or activation of CO and H{sub 2} bonds, the subsequent propagation steps including hydrogenation and carbon-carbon coupling, followed by chain termination reactions. Commercially viable catalysts include supported Co and Co-alloys. Over the first two years of this project we have used ab initio methods to determine the adsorption energies for all reactants, intermediates, and products along with the overall reaction energies and their corresponding activation barriers over the Co(0001) surface. Over the third year of the project we developed and advanced an ab initio-based kinetic Monte Carlo simulation code to simulate Fischer Tropsch synthesis. This report …
Date: May 7, 2006
Creator: Neurock, Matthew & Walthall, David A.
Object Type: Report
System: The UNT Digital Library
Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming (open access)

Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming

The atomic-scale processes that control the formation of carbon deposits on Ni catalysts in reforming applications are poorly understood. Ab initio Density Functional Theory calculations have been used to examine several key elementary steps in the complex network of chemical reactions that precedes carbon formation on practical catalysts. Attention has been focused on the disproportionation of CO. A comparative study of this reaction on flat and stepped crystal planes of Ni has provided the first direct evidence that surface carbon formation is driven by elementary reactions occurring at defect sites on Ni catalysts. The adsorption and diffusion of atomic H on several flat and stepped Ni surfaces has also been characterized experimentally.
Date: March 5, 2006
Creator: Sholl, David S.
Object Type: Report
System: The UNT Digital Library
Ability of the Confined Explosive Component Water Gap Test STANAG 4363 to Assess the Shock Sensitivity of MM-Scale Detonators (open access)

Ability of the Confined Explosive Component Water Gap Test STANAG 4363 to Assess the Shock Sensitivity of MM-Scale Detonators

The Explosive Component Water Gap Test (ECWGT) has been validated to assess the shock sensitivity of lead and booster components having a diameter larger than 5 mm. Several countries have investigated by experiments and numerical simulations the effect of confinement on the go/no go threshold for Pentaerythritol Tetranitrate (PETN) pellets having a height and diameter of 3 mm, confined by a steel annulus of wall thickness 1-3.5 mm. Confinement of the PETN by a steel annulus of the same height of the pellet with 1-mm wall thickness makes the component more sensitive (larger gap). As the wall thickness is increased to 2-mm, the gap increases a lesser amount, but when the wall thickness is increased to 3.5-mm a decrease in sensitivity is observed (smaller gap). This decrease of the water gap has been reproduced experimentally. Recent numerical simulations using Ignition and Growth model [1] for the PETN Pellet have reproduced the experimental results for the steel confinement up to 2 mm thick [2]. The presence of a stronger re-shock following the first input shock from the water and focusing on the axis have been identified in the pellet due to the steel confinement. The double shock configuration is well-known to …
Date: February 10, 2006
Creator: Lefrancois, A. S.; Roeske, F.; Benterou, J.; Tarver, C. M.; Lee, R. S. & Hannah, B.
Object Type: Report
System: The UNT Digital Library
Absence of Rapid Proton Decay and Origin of Low-Energy Particlesand Yukawa Couplings (open access)

Absence of Rapid Proton Decay and Origin of Low-Energy Particlesand Yukawa Couplings

In string theory, massless particles often originate from a symmetry breaking of a large gauge symmetry G to its subgroup H. The absence of dimension-4 proton decay in supersymmetric theories suggests that ({bar D},L) are different from {bar H}({bar 5}) in their origins. In this article, we consider a possibility that they come from different irreducible components in g/h. Requiring that all the Yukawa coupling constants of quarks and leptons be generated from the super Yang-Mills interactions of G, we found in the context of Georgi-Glashow H = SU(5) unification that the minimal choice of G is E{sub 7} and E{sub 8} is the only alternative. This idea is systematically implemented in Heterotic String, M theory and F theory, confirming the absence of dimension 4 proton decay operators. Not only H = SU(5) but also G constrain operators of effective field theories, providing non-trivial information.
Date: January 1, 2006
Creator: Tatar, Radu & Watari, Taizan
Object Type: Article
System: The UNT Digital Library
Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam (open access)

Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam

Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron cloud density during the beam pulse.
Date: April 27, 2006
Creator: Kireeff Covo, Michel; Molvik, Arthur W.; Friedman, Alex; Vay, Jean-Luc; Seidl, Peter A.; Logan, Grant et al.
Object Type: Article
System: The UNT Digital Library
Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam (open access)

Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam

Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron cloud density during the beam pulse.
Date: May 18, 2006
Creator: Covo, M K; Molvik, A W; Friedman, A; Vay, J; Seidl, P A; Logan, B G et al.
Object Type: Article
System: The UNT Digital Library
Abstract Proceedings Signal and Imaging Sciences Workshop CASIS Workshop 2006 (open access)

Abstract Proceedings Signal and Imaging Sciences Workshop CASIS Workshop 2006

These abstracts cover the following topics: (1) Analysis of massive datasets; (2) Nondestructive evaluation; (3) Imaging methodology; (4) NIF optics inspection; (5) Model-based signal processing and estimation; and (6) Image processing and analysis.
Date: November 7, 2006
Creator: Roberts, R
Object Type: Article
System: The UNT Digital Library
An AC dipole for the Tevatron - Initial tests (open access)

An AC dipole for the Tevatron - Initial tests

None
Date: May 1, 2006
Creator: Miyamoto, Ryoichi; Kopp, Sacha; Jansson, Andreas & Syphers, Mike
Object Type: Article
System: The UNT Digital Library
AC field measurements of Fermilab Booster correctors using a rotating coil system (open access)

AC field measurements of Fermilab Booster correctors using a rotating coil system

The first prototype of a new corrector package for the Fermilab Booster Synchrotron is presently in production. This water-cooled package includes normal and skew dipole, quadrupole and sextupole elements to control orbit, tune and chromaticity of the beam over the full range of Booster energies (0.4-8 GeV). These correctors operate at the 15 Hz excitation cycle of the main synchrotron magnets, but must also make more rapid excursions, in some cases even switching polarity in approximately 1 ms at transition crossing. To measure the dynamic field changes during operation, a new method based on a relatively slow rotating coil system is proposed. The method pieces together the measured voltages from successive current cycles to reconstruct the field harmonics. This paper describes the method and presents initial field quality measurements from a Tevatron corrector.
Date: July 1, 2006
Creator: Velev, G. V.; DiMarco, J.; Harding, D. J.; Kashikhin, V.; Lamm, M.; Makulski, A. et al.
Object Type: Article
System: The UNT Digital Library
AC Transit Demos Three Prototype Fuel Cell Buses (open access)

AC Transit Demos Three Prototype Fuel Cell Buses

Fact sheet describes the study being conducted on fuel cell buses at AC Transit.
Date: May 1, 2006
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Accelerated aging of solid lubricants for the W76-1 TSL : effects of polymer outgassing. (open access)

Accelerated aging of solid lubricants for the W76-1 TSL : effects of polymer outgassing.

The behavior of MoS{sub 2} lubricants intended for the W76-1 TSL was evaluated after 17 and 82 thermal cycles, each lasting seven days and including a low temperature of -35 C and a high temperature of 93 C, in a sealed container containing organic materials. The MoS{sub 2} was applied by tumbling with MoS{sub 2} powder and steel pins (harperized), or by spraying with a resin binder (AS Mix). Surface composition measurements indicated an uptake of carbon and silicon on the lubricant surfaces after aging. Oxidation of the MoS{sub 2} on harperized coupons, where enough MoS{sub 2} was present at the surface to result in significant Mo and S concentrations, was found to be minimal for the thermal cycles in an atmosphere of primarily nitrogen. Bare steel surfaces showed a reduction in friction for exposed coupons compared to control coupons stored in nitrogen, at least for the initial cycles of sliding until the adsorbed contaminants were worn away. Lubricated surfaces showed no more than a ten percent increase in steady-state friction coefficient after exposure. Initial coefficient of friction was up to 250 percent higher than steady-state for AS Mix films on H950 coupons after 82 thermal cycles. However, the friction …
Date: September 1, 2006
Creator: Dugger, Michael Thomas; Wallace, William O. & Huffman, Elizabeth M.
Object Type: Report
System: The UNT Digital Library
Accelerated Evolution of Conserved Noncoding Sequences in theHuman Genome (open access)

Accelerated Evolution of Conserved Noncoding Sequences in theHuman Genome

Genomic comparisons between human and distant, non-primatemammals are commonly used to identify cis-regulatory elements based onconstrained sequence evolution. However, these methods fail to detect"cryptic" functional elements, which are too weakly conserved amongmammals to distinguish from nonfunctional DNA. To address this problem,we explored the potential of deep intra-primate sequence comparisons. Wesequenced the orthologs of 558 kb of human genomic sequence, coveringmultiple loci involved in cholesterol homeostasis, in 6 nonhumanprimates. Our analysis identified 6 noncoding DNA elements displayingsignificant conservation among primates, but undetectable in more distantcomparisons. In vitro and in vivo tests revealed that at least three ofthese 6 elements have regulatory function. Notably, the mouse orthologsof these three functional human sequences had regulatory activity despitetheir lack of significant sequence conservation, indicating that they arecryptic ancestral cis-regulatory elements. These regulatory elementscould still be detected in a smaller set of three primate speciesincluding human, rhesus and marmoset. Since the human and rhesus genomesequences are already available, and the marmoset genome is activelybeing sequenced, the primate-specific conservation analysis describedhere can be applied in the near future on a whole-genome scale, tocomplement the annotation provided by more distant speciescomparisons.
Date: July 6, 2006
Creator: Prambhakar, Shyam; Noonan, James P.; Paabo, Svante & Rubin, EdwardM.
Object Type: Article
System: The UNT Digital Library
AN ACCELERATED RATE CALORIMETRY STUDY OF CAUSTIC-SIDE SOLVENT EXTRACTION SOLVENT WITHOUT EXTRACTANT (open access)

AN ACCELERATED RATE CALORIMETRY STUDY OF CAUSTIC-SIDE SOLVENT EXTRACTION SOLVENT WITHOUT EXTRACTANT

This study found that 4 - 48 part per thousand (ppth) of Caustic Side Solvent Extraction (CSSX) solvent without extractant in caustic salt solution at evaporator-relevant temperatures result in no process-significant energetic events. However, the data suggest a chemical reaction (possible decomposition) in the CSSX solvent near 140 C. This concentration of entrained solvent is believed to markedly exceed the amount of solvent that will pass from the Modular Caustic Side Solvent Unit (MCU) through the downstream Defense Waste Processing Facility and enter the evaporator through routine tank farm operations. The rate of pressure rise at 140 C differs appreciably - i.e., is reduced - for salt solution containing the organic from that of the same solution without solvent. This behavior is due to a reaction between the CSSX components and the salt solution simulant.
Date: March 7, 2006
Creator: Fondeur, F & Samuel Fink, S
Object Type: Report
System: The UNT Digital Library
Accelerating DSMC data extraction. (open access)

Accelerating DSMC data extraction.

In many direct simulation Monte Carlo (DSMC) simulations, the majority of computation time is consumed after the flowfield reaches a steady state. This situation occurs when the desired output quantities are small compared to the background fluctuations. For example, gas flows in many microelectromechanical systems (MEMS) have mean speeds more than two orders of magnitude smaller than the thermal speeds of the molecules themselves. The current solution to this problem is to collect sufficient samples to achieve the desired resolution. This can be an arduous process because the error is inversely proportional to the square root of the number of samples so we must, for example, quadruple the samples to cut the error in half. This work is intended to improve this situation by employing more advanced techniques, from fields other than solely statistics, for determining the output quantities. Our strategy centers on exploiting information neglected by current techniques, which collect moments in each cell without regard to one another, values in neighboring cells, nor their evolution in time. Unlike many previous acceleration techniques that modify the method itself, the techniques examined in this work strictly post-process so they may be applied to any DSMC code without affecting its fidelity …
Date: October 1, 2006
Creator: Gallis, Michail A. & Piekos, Edward Stanley
Object Type: Report
System: The UNT Digital Library
Accelerating Network Traffic Analytics Using Query-DrivenVisualization (open access)

Accelerating Network Traffic Analytics Using Query-DrivenVisualization

Realizing operational analytics solutions where large and complex data must be analyzed in a time-critical fashion entails integrating many different types of technology. This paper focuses on an interdisciplinary combination of scientific data management and visualization/analysis technologies targeted at reducing the time required for data filtering, querying, hypothesis testing and knowledge discovery in the domain of network connection data analysis. We show that use of compressed bitmap indexing can quickly answer queries in an interactive visual data analysis application, and compare its performance with two alternatives for serial and parallel filtering/querying on 2.5 billion records worth of network connection data collected over a period of 42 weeks. Our approach to visual network connection data exploration centers on two primary factors: interactive ad-hoc and multiresolution query formulation and execution over n dimensions and visual display of then-dimensional histogram results. This combination is applied in a case study to detect a distributed network scan and to then identify the set of remote hosts participating in the attack. Our approach is sufficiently general to be applied to a diverse set of data understanding problems as well as used in conjunction with a diverse set of analysis and visualization tools.
Date: July 29, 2006
Creator: Bethel, E. Wes; Campbell, Scott; Dart, Eli; Stockinger, Kurt & Wu,Kesheng
Object Type: Article
System: The UNT Digital Library
ACCELERATING POLARIZED PROTONS TO HIGH ENERGY. (open access)

ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.
Date: October 2, 2006
Creator: Bai, M.; Ahrens, L.; Alekseev, I. G.; Alessi, J.; Beebe-Wang, J.; Blaskiewicz, M. et al.
Object Type: Article
System: The UNT Digital Library
Accelerating PV Cost Effectiveness Through Systems Design, Engineering, and Quality Assurance: Phase I Annual Technical Report, 4 November 2004 - 3 November 2005 (open access)

Accelerating PV Cost Effectiveness Through Systems Design, Engineering, and Quality Assurance: Phase I Annual Technical Report, 4 November 2004 - 3 November 2005

During Phase I of this PV Manufacturing R&D subcontract, PowerLight Corporation has made significant progress toward the reduction of installed costs for commercial-scale, rooftop PV systems. PowerLight has worked to reduce operating costs by improving long-term reliability and performance through the development of more sophisticated tools used in system design and monitoring. Additionally, PowerLight has implemented design improvements with the goal of reducing cost while maintaining and/or improving product quality. As part of this effort, PowerLight also modified manufacturing and shipping processes to accommodate these design changes, streamline material flow, reduce cost, and decrease waste streams. During Phase II of this project, PowerLight plans to continue this work with the goal of reducing system cost and improving system performance.
Date: July 1, 2006
Creator: Botkin, J.
Object Type: Report
System: The UNT Digital Library
Acceleration of dormant storage effects to address the reliability of silicon surface micromachined Micro-Electro-Mechanical Systems (MEMS). (open access)

Acceleration of dormant storage effects to address the reliability of silicon surface micromachined Micro-Electro-Mechanical Systems (MEMS).

Qualification of microsystems for weapon applications is critically dependent on our ability to build confidence in their performance, by predicting the evolution of their behavior over time in the stockpile. The objective of this work was to accelerate aging mechanisms operative in surface micromachined silicon microelectromechanical systems (MEMS) with contacting surfaces that are stored for many years prior to use, to determine the effects of aging on reliability, and relate those effects to changes in the behavior of interfaces. Hence the main focus was on 'dormant' storage effects on the reliability of devices having mechanical contacts, the first time they must move. A large number ({approx}1000) of modules containing prototype devices and diagnostic structures were packaged using the best available processes for simple electromechanical devices. The packaging processes evolved during the project to better protect surfaces from exposure to contaminants and water vapor. Packages were subjected to accelerated aging and stress tests to explore dormancy and operational environment effects on reliability and performance. Functional tests and quantitative measurements of adhesion and friction demonstrated that the main failure mechanism during dormant storage is change in adhesion and friction, precipitated by loss of the fluorinated monolayer applied after fabrication. The data indicate …
Date: June 1, 2006
Creator: Cox, James V.; Candelaria, Sam A.; Dugger, Michael Thomas; Duesterhaus, Michelle Ann; Tanner, Danelle Mary; Timpe, Shannon J. et al.
Object Type: Report
System: The UNT Digital Library
Acceleration of Polarized Protons in the AGS With Two Helical Partial Snakes. (open access)

Acceleration of Polarized Protons in the AGS With Two Helical Partial Snakes.

Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.
Date: June 26, 2006
Creator: Huang, H.; Ahrens, L. A.; Bai, M.; Bravar, A.; Brown, K.; Courant, E. D. et al.
Object Type: Article
System: The UNT Digital Library
ACCELERATION PHYSICS CODE WEB REPOSITORY. (open access)

ACCELERATION PHYSICS CODE WEB REPOSITORY.

In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this repository, illustrate its usage, and discuss our future plans, with emphasis on code benchmarking.
Date: June 26, 2006
Creator: WEI, J.
Object Type: Article
System: The UNT Digital Library
Accelerator and Ion Beam Tradeoffs for Studies of Warm DenseMatter (open access)

Accelerator and Ion Beam Tradeoffs for Studies of Warm DenseMatter

One approach for heating a target to ''Warm Dense Matter'' conditions (similar, for example, to the interiors of giant planets or certain stages in inertial confinement fusion targets), is to use intense ion beams as the heating source (see refs.[6] and [7] and references therein for motivation and accelerator concepts). By consideration of ion beam phase-space constraints, both at the injector, and at the final focus, and consideration of simple equations of state and relations for ion stopping, approximate conditions at the target foil may be calculated. Thus, target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We connect some of these basic parameters to help search the extensive parameter space including ion mass, ion energy, total charge in beam pulse, beam emittance, target thickness and density.
Date: January 30, 2006
Creator: Barnard, J. J.; Briggs, R. J.; Callahan, D. A.; Davidson, R. C.; Friedman, A.; Grisham, L. et al.
Object Type: Article
System: The UNT Digital Library
Accelerator-Driven Neutron Source for Cargo Screening (open access)

Accelerator-Driven Neutron Source for Cargo Screening

Advanced neutron interrogation systems for the screening ofsea-land cargo containers for shielded special nuclear materials (SNM)require a high-yield neutron source to achieve the desired detectionprobability, false alarm rate, and throughput. An accelerator-drivenneutron source is described that produces a forward directed beam ofhigh-energy (up to 8.5 MeV) neutrons utilizing the D(d,n)3He reaction atdeuteron beam energies of up to 6 MeV. The key components of the neutronsource are a high-current RFQ accelerator and an innovative neutronproduction target. A microwave-driven deuteron source is coupled to anelectrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1meter-long, 200 MHz RFQ. The RFQ is based on an unusual beam dynamicsdesign and is capable of operating at a duty factor that produces morethan 1.2 mA timeaverage beam current. The beam is transported to a2-atmosphere deuterium gas target with a specially-designed, thinentrance window. A high-frequency dipole magnet is used to spread thebeam over the long dimension of the 4 by 35 cm target window. The sourcewill be capable of delivering a neutron flux of ~;2 x 107 n/(cm2 x s) tothe center of a sea-land cargo container and is expected t o satisfy therequirements for full testing and demonstration of advanced neutroninterrogation techniques based on …
Date: November 15, 2006
Creator: Ludewigt, B. A.; Bleuel, D. L.; Hoff, M. D.; Kwan, J. W.; Li, D.; Ratti, A. et al.
Object Type: Article
System: The UNT Digital Library