14-MeV Neutron Generator Used as a Thermal Neutron Source (open access)

14-MeV Neutron Generator Used as a Thermal Neutron Source

One of the most important applications of the general purpose Monte Carlo N-Particle (MCNPS and MCNPX) codes is neutron shielding design. We employed this method to simulate the shield of a 14-MeV neutron generator used as a thermal neutron source providing an external thermal neutron beam for testing large area neutron detectors developed for diffraction studies in biology and also useful for national security applications. Nuclear reactors have been the main sources of neutrons used for scientific applications. In the past decade, however, a large number of reactors have been shut down, and the importance of other, smaller devices capable of providing neutrons for research has increased. At Brookhaven National Laboratory a moderated Am-Be neutron source with shielding is used for neutron detector testing. This source is relatively weak, but provides a constant flux of neutrons, even when not in use. The use of a 14 MeV energized neutron generator, with an order of magnitude higher neutron flux has been considered to replace the Am-Be source, but the higher fast neutron yield requires a more careful design of moderator and shielding. In the present paper we describe a proposed shielding configuration based on Monte Carlo calculations, and provide calculated neutron …
Date: August 10, 2008
Creator: Dioszegi, I.
Object Type: Article
System: The UNT Digital Library
275 C Downhole Microcomputer System (open access)

275 C Downhole Microcomputer System

An HC11 controller IC and along with serial SRAM and ROM support ICs chip set were developed to support a data acquisition and control for extreme temperature/harsh environment conditions greater than 275 C. The 68HC11 microprocessor is widely used in well logging tools for control, data acquisition, and signal processing applications and was the logical choice for a downhole controller. This extreme temperature version of the 68HC11 enables new high temperature designs and additionally allows 68HC11-based well logging tools and MWD tools to be upgraded for high temperature operation in deep gas reservoirs, The microcomputer chip consists of the microprocessor ALU, a small boot ROM, 4 kbyte data RAM, counter/timer unit, serial peripheral interface (SPI), asynchronous serial interface (SCI), and the A, B, C, and D parallel ports. The chip is code compatible with the single chip mode commercial 68HC11 except for the absence of the analog to digital converter system. To avoid mask programmed internal ROM, a boot program is used to load the microcomputer program from an external mask SPI ROM. A SPI RAM IC completes the chip set and allows data RAM to be added in 4 kbyte increments. The HC11 controller IC chip set is implemented …
Date: August 31, 2008
Creator: Hutchens, Chris & Soo, Hooi Miin
Object Type: Report
System: The UNT Digital Library
275 C Downhole Switched-Mode Power Supply (open access)

275 C Downhole Switched-Mode Power Supply

A vee-square (V2) control based controller IC is developed for a switch mode power supply capable of operating at extreme temperature/harsh environment conditions. A buck type regulator with silicon carbide power junction field effect transistors (JFET) as power devices is used to analyze the performance of controller. Special emphases are made on the analog sub-blocks--voltage reference, operational transconductance amplifier and comparator as individual building blocks. Transformer coupled gate drives and high temperature operable magnetic cores and capacitors are identified and tested for use in the design. Conventional ceramic chip packaging of ICs combined with lead carrier type mounting of passive filter components is introduced for hybrid packaging of the complete product. The developed SMPS is anticipated to support the operation of down-hole microcontrollers and other electronics devices that require low/medium power filtered dc inputs over an operating temperature of 275 C.
Date: August 31, 2008
Creator: Hutchens, Chris & Madhuravasal, Vijay
Object Type: Report
System: The UNT Digital Library
2005 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River (open access)

2005 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River

Pallid sturgeon, Scaphirhynchus albus, have declined throughout the Missouri River since dam construction and inception of the Bank Stabilization and Navigation Project in 1912. Their decline likely is due to the loss and degradation of their natural habitat as a result of changes in the river’s structure and function, as well as the pallid sturgeon’s inability to adapt to these changes. The U. S. Army Corps of Engineers has been working with state and federal agencies to develop and conduct a Pallid Sturgeon Monitoring and Assessment Program (Program), with the goal of recovering pallid sturgeon populations. The Program has organized the monitoring and assessment efforts into distinct geographic segments, with state and federal resource management agencies possessing primary responsibility for one or more segment. To date, the results from annual monitoring have been reported for individual Program segments. However, monitoring results have not been summarized or evaluated for larger spatial scales, encompassing more than one Program segment. This report describes a summary conducted by the Pacific Northwest National Laboratory (PNNL) that synthesizes the 2005 sampling year monitoring results from individual segments.
Date: August 12, 2008
Creator: Oldenburg, Eric W.; Hanrahan, Timothy P.; Harnish, Ryan A.; Bellgraph, Brian J.; Duncan, Joanne P. & Allwardt, Craig H.
Object Type: Report
System: The UNT Digital Library
2006 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River (open access)

2006 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River

Pallid sturgeon, Scaphirhynchus albus, have declined throughout the Missouri River since dam construction and inception of the Bank Stabilization and Navigation Project in 1912. Their decline likely is due to the loss and degradation of their natural habitat as a result of changes in the river’s structure and function, as well as the pallid sturgeon’s inability to adapt to these changes. The U. S. Army Corps of Engineers has been working with state and federal agencies to develop and conduct a Pallid Sturgeon Monitoring and Assessment Program (Program), with the goal of recovering pallid sturgeon populations. The Program has organized the monitoring and assessment efforts into distinct geographic segments, with state and federal resource management agencies possessing primary responsibility for one or more segment. To date, the results from annual monitoring have been reported for individual Program segments. However, monitoring results have not been summarized or evaluated for larger spatial scales, encompassing more than one Program segment. This report describes a summary conducted by the Pacific Northwest National Laboratory (PNNL) that synthesizes the 2006 sampling year monitoring results from individual segments.
Date: August 12, 2008
Creator: Oldenburg, Eric W.; Hanrahan, Timothy P.; Harnish, Ryan A.; Bellgraph, Brian J.; Duncan, Joanne P. & Allwardt, Craig H.
Object Type: Report
System: The UNT Digital Library
2006 Savannah River Site Annual Illness and Injury Surveillance Report (open access)

2006 Savannah River Site Annual Illness and Injury Surveillance Report

The U.S. Department of Energy’s (DOE) commitment to assuring the health and safety of its workers includes the conduct of illness and injury surveillance activities that provide an early warning system to detect health problems among workers. The Illness and Injury Surveillance Program monitors illnesses and health conditions that result in an absence, occupational injuries and illnesses, and disabilities and deaths among current workers.
Date: August 20, 2008
Creator: United States. Department of Energy. Office of Health, Safety, and Security.
Object Type: Report
System: The UNT Digital Library
2007 Molecular & Cellular Bioenergetics (June 17-22, 2007) (open access)

2007 Molecular & Cellular Bioenergetics (June 17-22, 2007)

This Report describes Molecular & Cellular Bioenergetics.
Date: August 20, 2008
Creator: Fevzi Daldal, Nancy Ryan Gray
Object Type: Article
System: The UNT Digital Library
Actinic EUV mask inspection beyond 0.25 NA (open access)

Actinic EUV mask inspection beyond 0.25 NA

Operating at EUV wavelengths, the SEMATECH Berkeley Actinic Inspection Tool (AIT) is a zoneplate microscope that provides high quality aerial image measurements in routine operations for SEMATECH member companies. We have upgraded the optical performance of the AIT to provide multiple image magnifications, and several inspection NA values up to 0.35 NA equivalent (0.0875 mask-side). We report on the improved imaging capabilities including resolution below 100-nm on the mask side (25 nm, 4x wafer equivalent). EUV reticles are intricate optical systems made from of several materials with wavelength-specific optical properties. The combined interactions of the substrate, multilayer-stack, buffer layer and absorber layer produce a reflected EUV optical field that is challenging to model accurately, and difficult to fully assess without actinic at-wavelength inspection. Understanding the aerial image from lithographic printing alone is complicated by photoresist properties. The AIT is now used to investigate mask issues such as amplitude and phase defect printability, pattern repair techniques, contamination, inspection damage, and mask architecture. The AIT has a 6{sup o} illumination angle, and high-resolution exposure times are typically 20 seconds per image. The AIT operates semi-automatically capturing through-focus imaging series with step sizes as small as 0.1 {micro}m (0.5-0.8 {micro}m are typical), and …
Date: August 6, 2008
Creator: Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno B.; Kemp, Charles D.; Huh, S. et al.
Object Type: Article
System: The UNT Digital Library
Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications (open access)

Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications

Active interrogation, a measurement technique which uses a radiation source to probe materials and generate unique signatures useful for characterizing those materials, is a powerful tool for assaying special nuclear material. The most commonly used technique for performing active interrogation is to use an electronic neutron generator as the probe radiation source. Exploiting the unique operating characteristics of these devices, including their monoenergetic neutron emissions and their ability to operate in pulsed modes, presents a number of options for performing prompt and delayed signature analyses using both photon and neutron sensors. A review of literature in this area shows multiple applications of the active neutron interrogation technique for performing nuclear nonproliferation measurements. Some examples include measuring the plutonium content of spent fuel, assaying plutonium residue in spent fuel hull claddings, assaying plutonium in aqueous fuel reprocessing process streams, and assaying nuclear fuel reprocessing facility waste streams to detect and quantify fissile material. This paper discusses the historical use of this technique and examines its context within the scope and challenges of next-generation nuclear fuel cycles and advanced concept nuclear fuel cycle facilities.
Date: August 1, 2008
Creator: Chichester, David L. & Seabury, Edward H.
Object Type: Article
System: The UNT Digital Library
An Adaptive Landscape Classification Procedure using Geoinformatics and Artificial Neural Networks (open access)

An Adaptive Landscape Classification Procedure using Geoinformatics and Artificial Neural Networks

The Adaptive Landscape Classification Procedure (ALCP), which links the advanced geospatial analysis capabilities of Geographic Information Systems (GISs) and Artificial Neural Networks (ANNs) and particularly Self-Organizing Maps (SOMs), is proposed as a method for establishing and reducing complex data relationships. Its adaptive and evolutionary capability is evaluated for situations where varying types of data can be combined to address different prediction and/or management needs such as hydrologic response, water quality, aquatic habitat, groundwater recharge, land use, instrumentation placement, and forecast scenarios. The research presented here documents and presents favorable results of a procedure that aims to be a powerful and flexible spatial data classifier that fuses the strengths of geoinformatics and the intelligence of SOMs to provide data patterns and spatial information for environmental managers and researchers. This research shows how evaluation and analysis of spatial and/or temporal patterns in the landscape can provide insight into complex ecological, hydrological, climatic, and other natural and anthropogenic-influenced processes. Certainly, environmental management and research within heterogeneous watersheds provide challenges for consistent evaluation and understanding of system functions. For instance, watersheds over a range of scales are likely to exhibit varying levels of diversity in their characteristics of climate, hydrology, physiography, ecology, and anthropogenic …
Date: August 1, 2008
Creator: Coleman, Andre M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Adsorption of water on O(2x2)/Ru(0001): thermal stability and inhibition of dissociation by H2O-O bonding (open access)

Adsorption of water on O(2x2)/Ru(0001): thermal stability and inhibition of dissociation by H2O-O bonding

The effect of preadsorbed oxygen on the subsequent adsorption and reactions of water on Ru(0001) has been studied using low temperature scanning tunneling microscopy and DFT calculations. Experiments were carried out for O coverages close to 0.25 ML. It was found that no dissociation of water takes place up to the desorption temperature of {approx}180-230 K. DFT calculations show that intact water on O(2x2)/Ru(0001) is {approx} 0.49 eV more stable than the dissociation products, H and OH, at their preferred fcc and top adsorption sites.
Date: August 1, 2008
Creator: Mugarza, Aitor; Shimizu, Tomoko; Cabrera-Sanfelix, Pepa; Sanchez-Portal, Daniel; Arnau, Andres & Salmeron, Miquel
Object Type: Article
System: The UNT Digital Library
Advanced, High-Reliability, System-Integrated 500kW PV Inverter Development: Final Subcontract Report, 29 September 2005 - 31 May 2008 (open access)

Advanced, High-Reliability, System-Integrated 500kW PV Inverter Development: Final Subcontract Report, 29 September 2005 - 31 May 2008

Xantrex Technology accomplished subcontract goals of reducing parts cost, weight, and size of its 500-kW inverter by 25% compared to state-of-the-art PV inverters, while extending reliability by 25%.
Date: August 1, 2008
Creator: West, R.
Object Type: Report
System: The UNT Digital Library
Advanced Vehicles Group: Center for Transportation Technologies and Systems (open access)

Advanced Vehicles Group: Center for Transportation Technologies and Systems

Describes R&D in advanced vehicle systems and components (e.g., batteries) by NREL's Advanced Vehicles Group.
Date: August 1, 2008
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Advancing the state of the art in materials accountancy through Safeguards Performance Modeling. (open access)

Advancing the state of the art in materials accountancy through Safeguards Performance Modeling.

None
Date: August 1, 2008
Creator: Ricker, Neil Lawrence (University of Washington, Seattle, WA) & Cipiti, Benjamin B.
Object Type: Report
System: The UNT Digital Library
Amec Geomatrix/Ara Groundwater Remediaiton Trip Report (open access)

Amec Geomatrix/Ara Groundwater Remediaiton Trip Report

City of Rialto, Well No.3 Demonstration System Integration Project, and Baldwin Park Operable Unit, Baldwin Park, California. The groundwater remediation contractors are AMEC Geomatrix and ARA. The sites were visited on July 22, 2008. Fluor Hanford and the U.S. Department of Energy are currently looking at a variety of alternatives to capture carbon tetrachloride, nitrates, and other COCs from 200-ZP-l groundwater. A few of the more important objectives of our visits were to: (1) Evaluate the treatment systems being used by AMEC Geomatrix to address VOCs, perchlorate, NDMA, 1,4,-Dioxane, and 1,2,3 TCP in a drinking water source; (2) Evaluate how effective these treatment methods have been; (3) Determine the types of problems they have encountered with these treatment systems and how they addressed these problems; (4) Determine the types of secondary wastes being generated by the system; (5) Determine how clean of an operation these companies run; and (6) Determine if the site is worth being visited by DOE-RL at a later date.
Date: August 7, 2008
Creator: Simmons, S. A.; Hodgson, K. M. & Byrnes, M. E.
Object Type: Report
System: The UNT Digital Library
Analysis of the Hydrologic Response Associated With Shutdown and Restart of the 200-ZP-1 WMA T Tank Farm Pump-and-Treat System (open access)

Analysis of the Hydrologic Response Associated With Shutdown and Restart of the 200-ZP-1 WMA T Tank Farm Pump-and-Treat System

This report examines possible hydrologic effects of pump-and-treat remediation actions and provides a detailed analysis of water-level measurements for selected 200-ZP-1 T Tank Farm pump-and-treat system monitor wells during a recent shutdown (May 1, 2008) and restart activity (June 4, 2008) involving extraction well 299-W11-46. Specifically, this report 1) applies to recently developed methods for removing barometric pressure fluctuations from well water-level measurements to enhance the detection of pump-and-treat system effects at selected monitor wells, 2) analyzes the barometric-corrected well water-level responses to determine large-scale hydraulic properties, and 3) assesses characteristics and conditions that influence hydrologic responses (both laterally and vertically) associated with pump-and-treat systems. The general findings presented in this report have universal application for unconfined and confined aquifer systems.
Date: August 8, 2008
Creator: Spane, Frank A.
Object Type: Report
System: The UNT Digital Library
Analysis of voltage spikes in superconducting Nb3Sn magnets (open access)

Analysis of voltage spikes in superconducting Nb3Sn magnets

Fermi National Accelerator Laboratory has been developing a new generation of superconducting accelerator magnets based on Niobium Tin (Nb{sub 3}Sn). The performance of these magnets is influenced by thermo-magnetic instabilities, known as flux jumps, which can lead to premature trips of the quench detection system due to large voltage transients or quenches at low current. In an effort to better characterize and understand these instabilities, a system for capturing fast voltage transients was developed and used in recent tests of R&D model magnets. A new automated voltage spike analysis program was developed for the analysis of large amount of voltage-spike data. We report results from the analysis of large statistics data samples for short model magnets that were constructed using MJR and RRP strands having different sub-element size and structure. We then assess the implications for quench protection of Nb{sub 3}Sn magnets.
Date: August 1, 2008
Creator: Rahimzadeh-Kalaleh, S.; Ambrosio, G.; Chlachidze, G.; Donnelly, C. & Tartaglia, M.
Object Type: Article
System: The UNT Digital Library
Analytical Method for the Detection of Ozone Depleting Chemicals (ODC) in Commercial Products Using a Gas Chromatograph with an Electron Capture Detector (GC-ECD) (open access)

Analytical Method for the Detection of Ozone Depleting Chemicals (ODC) in Commercial Products Using a Gas Chromatograph with an Electron Capture Detector (GC-ECD)

This document describes an analytical procedure that was developed for the trace level detection of residual ozone depleting chemicals (ODC) associated with the manufacture of selected commercial products. To ensure the United States meets it obligation under the Montreal Protocol, Congress enacted legislation in 1989 to impose an excise tax on electronic goods imported into the United States that were produced with banned chemicals. This procedure was developed to technically determine if residual ODC chemicals could be detected on electronic circuit boards. The analytical method utilizes a “purge and trap” technique followed by gas chromatography with electron capture detection to capture and analyze the volatile chemicals associated with the matrix. The method describes the procedure, the hardware, operating conditions, calibration, and quality control measures in sufficient detail to allow the capability to be replicated. This document corresponds to internal Standard Operating Procedure (SOP) EFL-130A, Rev 4.
Date: August 1, 2008
Creator: Lee, Richard N.; Dockendorff, Brian P. & Wright, Bob W.
Object Type: Report
System: The UNT Digital Library
Analytical models for total dose ionization effects in MOS devices. (open access)

Analytical models for total dose ionization effects in MOS devices.

MOS devices are susceptible to damage by ionizing radiation due to charge buildup in gate, field and SOI buried oxides. Under positive bias holes created in the gate oxide will transport to the Si / SiO{sub 2} interface creating oxide-trapped charge. As a result of hole transport and trapping, hydrogen is liberated in the oxide which can create interface-trapped charge. The trapped charge will affect the threshold voltage and degrade the channel mobility. Neutralization of oxidetrapped charge by electron tunneling from the silicon and by thermal emission can take place over long periods of time. Neutralization of interface-trapped charge is not observed at room temperature. Analytical models are developed that account for the principal effects of total dose in MOS devices under different gate bias. The intent is to obtain closed-form solutions that can be used in circuit simulation. Expressions are derived for the aging effects of very low dose rate radiation over long time periods.
Date: August 1, 2008
Creator: Campbell, Phillip Montgomery & Bogdan, Carolyn W.
Object Type: Report
System: The UNT Digital Library
Anisotropic Hexagonal Boron Nitride Nanomaterials - Synthesis and Applications (open access)

Anisotropic Hexagonal Boron Nitride Nanomaterials - Synthesis and Applications

Boron nitride (BN) is a synthetic binary compound located between III and V group elements in the Periodic Table. However, its properties, in terms of polymorphism and mechanical characteristics, are rather close to those of carbon compared with other III-V compounds, such as gallium nitride. BN crystallizes into a layered or a tetrahedrally linked structure, like those of graphite and diamond, respectively, depending on the conditions of its preparation, especially the pressure applied. Such correspondence between BN and carbon readily can be understood from their isoelectronic structures [1, 2]. On the other hand, in contrast to graphite, layered BN is transparent and is an insulator. This material has attracted great interest because, similar to carbon, it exists in various polymorphic forms exhibiting very different properties; however, these forms do not correspond strictly to those of carbon. Crystallographically, BN is classified into four polymorphic forms: Hexagonal BN (h-BN) (Figure 1(b)); rhombohedral BN (r-BN); cubic BN (c-BN); and wurtzite BN (w-BN). BN does not occur in nature. In 1842, Balmain [3] obtained BN as a reaction product between molten boric oxide and potassium cyanide under atmospheric pressure. Thereafter, many methods for its synthesis were reported. h-BN and r-BN are formed under ambient …
Date: August 1, 2008
Creator: Han,W.Q.
Object Type: Book
System: The UNT Digital Library
Anode Interactions with Coal Gas Contaminants (open access)

Anode Interactions with Coal Gas Contaminants

This report describes efforts to characterize the interactions nickel anodes with phosphorus in coal gas using three different button cell configurations to emphasize particular degradation modes. Important parameters addressed included contaminant concentration, temperature, reaction time, fuel utilization, and current density. In addition, coupon tests in flow-through and flow-by arrangements were conducted to complement cell tests. The studies have involved extensive electrochemical testing using both dc and ac methods. Post-test analyses to determine the composition and extent of nickel modification are particularly important to understanding reactions that have occurred. This report also provides a thermodynamic assessment of contaminant reactions with nickel in a coal gas environment with regard to alteration phase formation. Contaminants addressed were phosphorus, arsenic, sulfur, selenium, and antimony. Phosphorus was found to interact strongly with nickel and result in extensive alteration phase formation, consistent with expectations based on thermodynamic properties. Even in button cell tests where the fuel utilization was low, phosphorus was found to be nearly completely captured by the nickel anode. For anode-supported cells, an important degradation mode involved loss of electronic percolation, the result of nickel phosphide formation, grain growth, and inducement of micro-fractures within the anode support. Even with excessive anode support conversion, electrochemical …
Date: August 13, 2008
Creator: Marina, Olga A.; Coffey, Greg W.; Coyle, Christopher A.; Nguyen, Carolyn D.; Thomsen, Edwin C. & Pederson, Larry R.
Object Type: Report
System: The UNT Digital Library
The Anti-B ---> D* l anti-nu form factor at zero recoil from three-flavor lattice QCD: A Model independent determination of |V(cb)| (open access)

The Anti-B ---> D* l anti-nu form factor at zero recoil from three-flavor lattice QCD: A Model independent determination of |V(cb)|

None
Date: August 1, 2008
Creator: Bernard, C.; DeTar, C.; Di Pierro, M.; El-Khadra, A. X.; Evans, R. T.; Freeland, E. D. et al.
Object Type: Article
System: The UNT Digital Library
Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data (open access)

Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data

Our work combines and extends techniques from high-performance scientific data management and visualization to enable scientific researchers to gain insight from extremely large, complex, time-varying laser wakefield particle accelerator simulation data. We extend histogram-based parallel coordinates for use in visual information display as well as an interface for guiding and performing data mining operations, which are based upon multi-dimensional and temporal thresholding and data subsetting operations. To achieve very high performance on parallel computing platforms, we leverage FastBit, a state-of-the-art index/query technology, to accelerate data mining and multi-dimensional histogram computation. We show how these techniques are used in practice by scientific researchers to identify, visualize and analyze a particle beam in a large, time-varying dataset.
Date: August 28, 2008
Creator: Rubel, Oliver; Prabhat, Mr.; Wu, Kesheng; Childs, Hank; Meredith, Jeremy; Geddes, Cameron G.R. et al.
Object Type: Article
System: The UNT Digital Library

Application of Proteomics and Lipid Studies in Environmental Biotechnology

The overview of changes in protein levels or states in response to a growth condition, stress, mutation or metabolic engineering is invaluable in understanding the physiology of a microbial system. The lipid profile of the cell is similarly a valuable diagnostic of the cellular response and health, especially in context of survival in a fluctuating environment. To obtain comprehensive cellular models, post-transcriptional cell wide surveys at the levels of proteins and lipids are required. Both these fields have been greatly bolstered by the development of high throughput methods using mass spectrometry. Multiple strategies now exist for the identification of proteins, and numerous workflows to quantify protein abundance have also been developed. Cellular profiling such as these allows us to assess the potential of a microbial system for environmental applications such as bioremediation and bio-energy.
Date: August 12, 2008
Creator: Mukhopadhyay, Aindrila
Object Type: Presentation
System: The UNT Digital Library