Simplified Design Criteria for Very High Temperature Applications in Generation IV Reactors (open access)

Simplified Design Criteria for Very High Temperature Applications in Generation IV Reactors

The goal of this activity is to provide simplified criteria which can be used in rapid feasibility assessments of the structural viability of very high temperature components in conceptual and early preliminary design phases for Generation IV reactors. The current criteria in ASME Code Section III, Subsection NH, hereafter referred to as NH, (and Code Case N-201 for core support structures) are difficult and require a complex deconstruction of finite element analysis results for their implementation. Further, and most important, times, temperatures and some materials of interest to the very high temperature Generation IV components are not covered by the current provisions of NH. Future revisions to NH are anticipated that will address very high temperature Generation IV components and materials requirements but, until that occurs interim guidance is required for design activities to proceed. These simplified criteria are for design guidance and are not necessarily in rigorous compliance with NH methodology. Rather, the objective is for criteria which address the early design needs of very high temperature Generation IV components and materials. The intent is to provide simplified but not overly conservative design methods. When more rigorous criteria and methods are incorporated in NH, the degree of conservatism should …
Date: December 15, 2004
Creator: McGreevy, TE
Object Type: Report
System: The UNT Digital Library
Smart Libraries: Best SQE Practices for Libraries with an Emphasis on Scientific Computing (open access)

Smart Libraries: Best SQE Practices for Libraries with an Emphasis on Scientific Computing

As scientific computing applications grow in complexity, more and more functionality is being packaged in independently developed libraries. Worse, as the computing environments in which these applications run grow in complexity, it gets easier to make mistakes in building, installing and using libraries as well as the applications that depend on them. Unfortunately, SQA standards so far developed focus primarily on applications, not libraries. We show that SQA standards for libraries differ from applications in many respects. We introduce and describe a variety of practices aimed at minimizing the likelihood of making mistakes in using libraries and at maximizing users' ability to diagnose and correct them when they occur. We introduce the term Smart Library to refer to a library that is developed with these basic principles in mind. We draw upon specific examples from existing products we believe incorporate smart features: MPI, a parallel message passing library, and HDF5 and SAF, both of which are parallel I/O libraries supporting scientific computing applications. We conclude with a narrative of some real-world experiences in using smart libraries with Ale3d, VisIt and SAF.
Date: December 15, 2004
Creator: Miller, M C; Reus, J F; Matzke, R P; Koziol, Q A & Cheng, A P
Object Type: Article
System: The UNT Digital Library
National Alliance for Clean Energy Incubators New Mexico Clean Energy Incubator (open access)

National Alliance for Clean Energy Incubators New Mexico Clean Energy Incubator

The National Alliance for Clean Energy Incubators was established by the National Renewable Energy Laboratory (NREL) to develop an emerging network of business incubators for entrepreneurs specializing in clean energy enterprises. The Alliance provides a broad range of business services to entrepreneurs in specific geographic locales across the U.S. and in diverse clean energy technology areas such as fuel cells, alternative fuels, power generation, and renewables, to name a few. Technology Ventures Corporation (TVC) participates in the Alliance from its corporate offices in Albuquerque, NM, and from its sites in Northern and Southern New Mexico, California, and Nevada. TVC reports on the results of its attempts to accelerate the growth and success of clean energy and energy efficiency companies through its array of business support services. During the period from September 2002 through September 2004, TVC describes contributions to the Alliance including the development of 28 clients and facilitating capital raises exceeding $35M.
Date: December 15, 2004
Creator: Roberts, Suzanne S.
Object Type: Report
System: The UNT Digital Library
Verification and Validation of MERCURY: A Modern, Monte Carlo Particle Transport Code (open access)

Verification and Validation of MERCURY: A Modern, Monte Carlo Particle Transport Code

None
Date: December 15, 2004
Creator: Procassini, R J; Cullen, D E; Greenman, G M & Hagmann, C A
Object Type: Article
System: The UNT Digital Library
Thermophysical Properties of Heat Resistant Shielding Material (open access)

Thermophysical Properties of Heat Resistant Shielding Material

This project was aimed at determining thermal conductivity, specific heat and thermal expansion of a heat resistant shielding material for neutron absorption applications. These data are critical in predicting the structural integrity of the shielding under thermal cycling and mechanical load. The measurements of thermal conductivity and specific heat were conducted in air at five different temperatures (-31 F, 73.4 F, 140 F, 212 F and 302 F). The transient plane source (TPS) method was used in the tests. Thermal expansion tests were conducted using push rod dilatometry over the continuous range from -40 F (-40 C) to 302 F (150 C).
Date: December 15, 2004
Creator: Porter, W.D.
Object Type: Report
System: The UNT Digital Library
2003 Toxic Chemical Release Inventory Report for the Emergency Planning and Community Right-to-Know Act of 1986, Title III, Section 313 (open access)

2003 Toxic Chemical Release Inventory Report for the Emergency Planning and Community Right-to-Know Act of 1986, Title III, Section 313

None
Date: December 15, 2004
Creator: Stockton, M.
Object Type: Report
System: The UNT Digital Library
Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study (open access)

Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reactions and in particular, ammonia synthesis in order to identify reaction intermediates and the influence of adsorbates on the surface during reaction conditions. The adsorption of gases N{sub 2}, H{sub 2}, O{sub 2} and NH{sub 3} that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH{sub 2} ({approx}3325 cm{sup -1}) and NH ({approx}3235 cm{sup -1}) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180{sup o} between the resonant and non-resonant second …
Date: December 15, 2004
Creator: Westerberg, Staffan Per Gustav
Object Type: Thesis or Dissertation
System: The UNT Digital Library
A Cavity Ring-Down Spectroscopy Mercury Continuous Emission Monitor (open access)

A Cavity Ring-Down Spectroscopy Mercury Continuous Emission Monitor

The Sensor Research & Development Corporation (SRD) has undertaken the development of a Continuous Emissions Monitor (CEM) for mercury based on the technique of Cavity Ring-Down Spectroscopy (CRD). The project involved building an instrument for the detection of trace levels of mercury in the flue gas emissions from coal-fired power plants. The project has occurred over two phases. The first phase concentrated on the development of the ringdown cavity and the actual detection of mercury. The second phase dealt with the construction and integration of the sampling system, used to carry the sample from the flue stack to the CRD cavity, into the overall CRD instrument. The project incorporated a Pulsed Alexandrite Laser (PAL) system from Light Age Incorporated as the source to produce the desired narrow band 254 nm ultra-violet (UV) radiation. This laser system was seeded with a diode laser to bring the linewidth of the output beam from about 150 GHz to less than 60 MHz for the fundamental beam. Through a variety of non-linear optics the 761 nm fundamental beam is converted into the 254 nm beam needed for mercury detection. Detection of the mercury transition was verified by the identification of the characteristic natural isotopic …
Date: December 15, 2004
Creator: Carter, Christopher C.
Object Type: Report
System: The UNT Digital Library
Ultrasonic Concentration in a Line-Driven Cylindrical Tube (open access)

Ultrasonic Concentration in a Line-Driven Cylindrical Tube

The fractionation of particles from their suspending fluid or noninvasive micromanipulation of particles in suspension has many applications ranging from the recovery of valuable reagents from process flows to the fabrication of microelectromechanical devices. Techniques based on size, density, solubility, or electromagnetic properties exist for fulfilling these needs, but many particles have traits that preclude their use such as small size, neutral buoyancy, or uniform electromagnetic characteristics. While separation by those techniques may not be possible, often compressibility differences exist between the particle and fluid that would allow fractionation by acoustic forces. The potential of acoustic separation is known, but due to inherent difficulties in achieving and maintaining accurate alignment of the transduction system, it is rarely utilized. The objective of this project is to investigate the use of structural excitation as a potentially efficient concentration/fractionation method for particles in suspension. It is demonstrated that structural excitation of a cylindrically symmetric cavity, such as a tube, allows non-invasive, fast, and low power concentration of particles suspended in a fluid. The inherent symmetry of the system eliminates the need for careful alignment inherent in current acoustic concentration devices. Structural excitation distributes the acoustic field throughout the volume of the cavity, which …
Date: December 15, 2004
Creator: Goddard, G.R.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Effects of Elevated CO2 on Root Dynamics and Root Function in a Mojave Desert Ecosystem (open access)

Effects of Elevated CO2 on Root Dynamics and Root Function in a Mojave Desert Ecosystem

None
Date: December 15, 2004
Creator: Nowak, Roberts
Object Type: Report
System: The UNT Digital Library
Strategies for Detecting Hidden Geothermal Systems by Near-Surface Gas Monitoring (open access)

Strategies for Detecting Hidden Geothermal Systems by Near-Surface Gas Monitoring

''Hidden'' geothermal systems are those systems above which hydrothermal surface features (e.g., hot springs, fumaroles, elevated ground temperatures, hydrothermal alteration) are lacking. Emissions of moderate to low solubility gases (e.g., CO2, CH4, He) may be one of the primary near-surface signals from these systems. Detection of anomalous gas emissions related to hidden geothermal systems may therefore be an important tool to discover new geothermal resources. This study investigates the potential for CO2 detection and monitoring in the subsurface and above ground in the near-surface environment to serve as a tool to discover hidden geothermal systems. We focus the investigation on CO2 due to (1) its abundance in geothermal systems, (2) its moderate solubility in water, and (3) the wide range of technologies available to monitor CO2 in the near-surface environment. However, monitoring in the near-surface environment for CO2 derived from hidden geothermal reservoirs is complicated by the large variation in CO2 fluxes and concentrations arising from natural biological and hydrologic processes. In the near-surface environment, the flow and transport of CO2 at high concentrations will be controlled by its high density, low viscosity, and high solubility in water relative to air. Numerical simulations of CO2 migration show that CO2 concentrations …
Date: December 15, 2004
Creator: Lewicki, Jennifer L. & Oldenburg, Curtis M.
Object Type: Report
System: The UNT Digital Library
Comparative metagenomics of microbial communities (open access)

Comparative metagenomics of microbial communities

The predicted proteins encoded in DNA isolated from environmental microbial community samples reveal habitat-specific metabolic demands.
Date: December 15, 2004
Creator: Tringe, Susannah Green; von Mering, Christian; Kobayashi, Arthur; Salamov, Asaf A.; Chen, Kevin; Chang, Hwai W. et al.
Object Type: Article
System: The UNT Digital Library
Port and Harbor Security (open access)

Port and Harbor Security

Port and Harbor Security is a daunting task to which optics and photonics offers significant solutions. We are pleased to report that the 2005 Defense and Security Symposium (DSS, Orlando, FL) will include reports on active and passive photonic systems operating from both airborne and subsurface platforms. In addition to imaging techniques, there are various photonic applications, such as total internal reflection fluorescence (TIRF), which can be used to ''sniff'' for traces of explosives or contaminants in marine. These non-imaging technologies are beyond the scope of this article, but will also be represented at DSS 2005. We encourage colleagues to join our technical group to help us to make our ports and harbors safer and more secure.
Date: December 15, 2004
Creator: Saito, T.; Guthmuller, H. & DeWeert, M.
Object Type: Article
System: The UNT Digital Library
A Final Focus Model for Heavy Ion Fusion Driver System Codes (open access)

A Final Focus Model for Heavy Ion Fusion Driver System Codes

The need to reach high temperatures in an inertial fusion energy (IFE) target (or a target for the study of High Energy Density Physics, HEDP) requires the ability to focus ion beams down to a small spot. System models indicate that within the accelerator, the beam radius will be of order centimeters, whereas at the final focal spot on the target, a beam radius of order millimeters is required, so radial compression factors of order ten are required. The IFE target gain (and hence the overall cost of electricity) and the HEDP target temperature are sensitive functions of the final spot radius on target. Because of this sensitivity, careful attention needs to be paid to the spot radius calculation. We review our current understanding of the elements that enter into a systems model (such as emittance growth from chromatic, geometric, and non-linear space charge forces) for the final focus based on a quadrupolar magnet system.
Date: December 15, 2004
Creator: Barnard, J. J.; Bangerter, R. O.; Henestroza, E.; Kaganovich, I. D.; Logan, B. G.; Meier, W. R. et al.
Object Type: Article
System: The UNT Digital Library
Spreading of Viscous Liquids at High Temperature: Silicate Glasseson Molybdenum (open access)

Spreading of Viscous Liquids at High Temperature: Silicate Glasseson Molybdenum

The spreading of Si-Ca-Al-Ti-O glasses on molybdenum has been investigated. By controlling the oxygen activity in the furnace, spreading can take place under reactive or non-reactive conditions. As the nucleation of the reaction product under reactive conditions is slow in comparison to the spreading kinetics, in both cases the glass front moves on the metal surface with similar spreading velocities. Spreading can be described using a molecular dynamics model where the main contribution to the wetting activation energy comes from the viscous interactions in the liquid. Enhanced interfacial diffusions in low-oxygen activities (reactive cases) form triple-line ridges that can pin the wetting front and cause a stick-slip motion.
Date: December 15, 2004
Creator: Lopez-Esteban, Sonia; Saiz, Eduardo; Moya, Jose S. & Tomsia,Antoni P.
Object Type: Article
System: The UNT Digital Library
Higher order nuclear organization in growth arrest of humanmammary epithelial cells: A novel role for telomere-associated proteinTIN2 (open access)

Higher order nuclear organization in growth arrest of humanmammary epithelial cells: A novel role for telomere-associated proteinTIN2

Nuclear organization, such as the formation of specific nuclear subdomains, is generally thought to be involved in the control of cellular phenotype; however, there are relatively few specific examples of how mammalian nuclei organize during radical changes in phenotype, such as those which occur during differentiation and growth arrest. Using human mammary epithelial cells (HMECs) in which growth arrest is essential for morphological differentiation, we show that the arrest of cell proliferation is accompanied by a reorganization of the telomere-associated protein, TIN2, into one to three large nuclear subdomains. The large TIN2 domains do not contain telomeres and occur concomitant with the continued presence of TIN2 at telomeres. The TIN2 domains were sensitive to DNAse, but not RNAse, occurred frequently, but not exclusively near nucleoli, and overlapped often with dense domains containing heterochromatin protein l{gamma}. Expression of truncated forms of TIN2 simultaneously prevented the formation of TIN2 domains and relaxed the stringent morphogenesis-induced growth arrest in HMECs. Our findings reveal a novel extra-telomeric organization of TIN2 associated with the control of cell proliferation and identify TIN2 as an important regulator of mammary epithelial differentiation.
Date: December 15, 2004
Creator: Kaminker, Patrick; Plachot, Cedric; Kim, Sahn-Ho; Chung, Peter; Crippen, Danielle; Petersen, Ole W. et al.
Object Type: Article
System: The UNT Digital Library
Completing Pre-Pilot Tasks To Scale Up Biomass Fractionation Pretreatment Apparatus From Batch To Continuous (open access)

Completing Pre-Pilot Tasks To Scale Up Biomass Fractionation Pretreatment Apparatus From Batch To Continuous

PureVision Technology, Inc. (PureVision) was the recipient of a $200,000 Invention and Innovations (I&I) grant from the U. S. Department of Energy (DOE) to complete prepilot tasks in order to scale up its patented biomass fractionation pretreatment apparatus from batch to continuous processing. The initial goal of the I&I program, as detailed in PureVision's original application to the DOE, was to develop the design criteria to build a small continuous biomass fractionation pilot apparatus utilizing a retrofitted extruder with a novel screw configuration to create multiple reaction zones, separated by dynamic plugs within the reaction chamber that support the continuous counter-flow of liquids and solids at elevated temperature and pressure. Although the ultimate results of this 27-month I&I program exceeded the initial expectations, some of the originally planned tasks were not completed due to a modification of direction in the program. PureVision achieved its primary milestone by establishing the design criteria for a continuous process development unit (PDU). In addition, PureVision was able to complete the procurement, assembly, and initiate shake down of the PDU at Western Research Institute (WRI) in Laramie, WY during August 2003 to February 2004. During the month of March 2004, PureVision and WRI performed initial …
Date: December 15, 2004
Creator: Wingerson, Dick
Object Type: Report
System: The UNT Digital Library
Probing structural heterogeneities and conformational fluctuations of biopolymers (open access)

Probing structural heterogeneities and conformational fluctuations of biopolymers

We study protein and nucleic acid structure and dynamics using single-molecule fluorescence resonance energy transfer measurements with alternating-laser excitation. Freely diffusing molecules are sorted into subpopulations based on stoichiometry, detecting donor and acceptor coincidence for periods over 100 {micro}s-1 ms. Faster (< 100 {micro}s) fluctuating distance distributions are studied within these subpopulations using time-resolved single photon counting measurements. We find that short double-stranded DNA (dsDNA) is more flexible than expected from persistence lengths measured on long dsDNA. We find that the electrostatic portion of the persistence length of single-stranded poly-dT varies as the ionic strength (I) to the -1/2 power (I{sup -1/2}). Lastly, we find that the unfolded protein Chymotrypsin Inhibitor 2 (CI2) is unstructured at high denaturant. However, in the presence of folded CI2 (at lower denaturant), unfolded CI2 is more compact and displays larger distance fluctuations, possibly due to unsuccessful attempts to cross the folding barrier.
Date: December 15, 2004
Creator: Laurence, T.; Kong, X.; Jaeger, M. & Weiss, S.
Object Type: Article
System: The UNT Digital Library
Stress Measurements in Shock-Loaded PBX 9501 with Embedded Longitudinal and Lateral Piezoresistive Ytterbium Gauges (open access)

Stress Measurements in Shock-Loaded PBX 9501 with Embedded Longitudinal and Lateral Piezoresistive Ytterbium Gauges

A series of light gas gun impact experiments were performed with piezoresistive ytterbium (Yb) gauges in longitudinal and lateral orientations embedded in the plastic bonded explosive PBX 9501. These experiments were performed to evaluate the feasibility of using this method to measure lateral stresses and shear strength dynamically in PBX 9501. Ytterbium was chosen as a gauge material based on its high piezoresistance changes at low stress levels. Experiments were performed at longitudinal impact stresses of approximately 0.6 GPa, which is above the yield point of Yb, near the dynamic yield point of PBX 9501, at a level that is comparable with other impact data, and relevant to several multidimensional safety tests. Results show that PBX 9501 does maintain strength throughout compression. Because of poor reproducibility observed in the experiments presented, it appears unlikely that stress extraction from these gauge results would yield an estimate of shear strength at this impact stress with acceptable error.
Date: December 15, 2004
Creator: Hooks, Daniel E.; Dick, Jerry J. & Martinez, A. Richard
Object Type: Report
System: The UNT Digital Library
GROWTH, SURFACE CHARACTERIZATION, AND REACTIVITY OF TIO2 ANATASE FILMS-EPSCOR (open access)

GROWTH, SURFACE CHARACTERIZATION, AND REACTIVITY OF TIO2 ANATASE FILMS-EPSCOR

TiO2 is as promising photocatalyst for environmental degradation of organic compounds and solar energy conversion. Commercial titania is a mixture of rutile and anatase phases, and, for as of yet unknown reasons, anatase is the photocatalytically more active form. In contrast to rutile, atomic-scale information on well-characterized anatase surfaces and their chemical properties was virtually absent at the beginning of this project. We have performed surface science investigations of anatase with the goal to understand, and ultimately control, the surface chemistry underlying its diverse applications. We have of (1) characterized all main crystallographic surface orientations of anatase, namely the (101), (100), (001), and (103) surfaces (2) have investigated the influence of surface imperfections such as defects and steps; (3) have investigated the influence of dopants on epitaxial (001) anatase films; and (3) have investigated the chemical and adsorption and reaction processes of simple molecules (water and methanol) on anatase surfaces. The experiments were performed in collaboration with Pacific Northwest National Laboratory (PNNL) using a variety of complementary surface science techniques. They have lead to a thorough characterization of this model system and have provided a more complete understanding of TiO2, which could possibly lead to improved efficiency in of photocatalytic …
Date: December 15, 2004
Creator: Diebold, Ulrike
Object Type: Report
System: The UNT Digital Library