High Rate Deposition of High Quality ZnO:Al by Filtered Cathodic Arc (open access)

High Rate Deposition of High Quality ZnO:Al by Filtered Cathodic Arc

High quality ZnO:Al (AZO) thin films were prepared on glass substrates by direct current filtered cathodic arc deposition. Substrate temperature was varied from room temperature to 425oC, and samples were grown with and without the assistance of low power oxygen plasma (75W). For each growth condition, at least 3 samples were grown to give a statistical look at the effect of the growth environment on the film properties and to explore the reproducibility of the technique. Growth rate was in the 100-400 nm/min range but was apparently random and could not be easily traced to the growth conditions explored. For optimized growth conditions, 300-600 nm AZO films had resistivities of 3-6 x 10-4 ?Omega cm, carrier concentrations in the range of 2-4 x 1020 cm3, Hall mobility as high as 55 cm2/Vs, and optical transmittance greater than 90percent. These films are also highly oriented with the c-axis perpendicular to the substrate and a surface roughness of 2-4 nm.
Date: November 18, 2010
Creator: Mendelsberg, Rueben J.; Lim, S.H.N.; Milliron, D.J. & Anders, Andre
Object Type: Article
System: The UNT Digital Library
Mechanism of Thermal Reversal of the (Fulvalene)tetracarbonyldiruthenium Photoisomerization: Toward Molecular Solar-Thermal Energy Storage (open access)

Mechanism of Thermal Reversal of the (Fulvalene)tetracarbonyldiruthenium Photoisomerization: Toward Molecular Solar-Thermal Energy Storage

In the currently intensifying quest to harness solar energy for the powering of our planet, most efforts are centered around photoinduced generic charge separation, such as in photovoltaics, water splitting, other small molecule activation, and biologically inspired photosynthetic systems. In contrast, direct collection of heat from sunlight has received much less diversified attention, its bulk devoted to the development of concentrating solar thermal power plants, in which mirrors are used to focus the sun beam on an appropriate heat transfer material. An attractive alternative strategy would be to trap solar energy in the form of chemical bonds, ideally through the photoconversion of a suitable molecule to a higher energy isomer, which, in turn, would release the stored energy by thermal reversal. Such a system would encompass the essential elements of a rechargeable heat battery, with its inherent advantages of storage, transportability, and use on demand. The underlying concept has been explored extensively with organic molecules (such as the norbornadiene-quadricyclane cycle), often in the context of developing photoswitches. On the other hand, organometallic complexes have remained relatively obscure in this capacity, despite a number of advantages, including expanded structural tunability and generally favorable electronic absorption regimes. A highly promising organometallic system …
Date: February 18, 2010
Creator: Kanai, Y; Srinivasan, V; Meier, S K; Vollhardt, K P & Grossman, J C
Object Type: Article
System: The UNT Digital Library
Photodetectors for Scintillator Proportionality Measurement (open access)

Photodetectors for Scintillator Proportionality Measurement

We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.
Date: October 18, 2010
Creator: Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine & Valentine, J. D.
Object Type: Article
System: The UNT Digital Library
MANGO – Modal Analysis for Grid Operation: A Method for Damping Improvement through Operating Point Adjustment (open access)

MANGO – Modal Analysis for Grid Operation: A Method for Damping Improvement through Operating Point Adjustment

Small signal stability problems are one of the major threats to grid stability and reliability in the U.S. power grid. An undamped mode can cause large-amplitude oscillations and may result in system breakups and large-scale blackouts. There have been several incidents of system-wide oscillations. Of those incidents, the most notable is the August 10, 1996 western system breakup, a result of undamped system-wide oscillations. Significant efforts have been devoted to monitoring system oscillatory behaviors from measurements in the past 20 years. The deployment of phasor measurement units (PMU) provides high-precision, time-synchronized data needed for detecting oscillation modes. Measurement-based modal analysis, also known as ModeMeter, uses real-time phasor measurements to identify system oscillation modes and their damping. Low damping indicates potential system stability issues. Modal analysis has been demonstrated with phasor measurements to have the capability of estimating system modes from both oscillation signals and ambient data. With more and more phasor measurements available and ModeMeter techniques maturing, there is yet a need for methods to bring modal analysis from monitoring to actions. The methods should be able to associate low damping with grid operating conditions, so operators or automated operation schemes can respond when low damping is observed. The work …
Date: October 18, 2010
Creator: Huang, Zhenyu; Zhou, Ning; Tuffner, Francis K.; Chen, Yousu; Trudnowski, Daniel J.; Diao, Ruisheng et al.
Object Type: Report
System: The UNT Digital Library
Evaluation of Large Volume SrI2(Eu) Scintillator Detectors (open access)

Evaluation of Large Volume SrI2(Eu) Scintillator Detectors

There is an ever increasing demand for gamma-ray detectors which can achieve good energy resolution, high detection efficiency, and room-temperature operation. We are working to address each of these requirements through the development of large volume SrI{sub 2}(Eu) scintillator detectors. In this work, we have evaluated a variety of SrI{sub 2} crystals with volumes >10 cm{sup 3}. The goal of this research was to examine the causes of energy resolution degradation for larger detectors and to determine what can be done to mitigate these effects. Testing both packaged and unpackaged detectors, we have consistently achieved better resolution with the packaged detectors. Using a collimated gamma-ray source, it was determined that better energy resolution for the packaged detectors is correlated with better light collection uniformity. A number of packaged detectors were fabricated and tested and the best spectroscopic performance was achieved for a 3% Eu doped crystal with an energy resolution of 2.93% FWHM at 662keV. Simulations of SrI{sub 2}(Eu) crystals were also performed to better understand the light transport physics in scintillators and are reported. This study has important implications for the development of SrI{sub 2}(Eu) detectors for national security purposes.
Date: November 18, 2010
Creator: Sturm, B. W.; Cherepy, N. J.; Drury, O. B.; Thelin, P. A.; Fisher, S. E.; Magyar, A. F. et al.
Object Type: Article
System: The UNT Digital Library
In vitro High-Resolution Architecture and Structural Dynamics of Bacterial Systems (open access)

In vitro High-Resolution Architecture and Structural Dynamics of Bacterial Systems

None
Date: March 18, 2010
Creator: Malkin, A. J.; Plomp, M.; Leighton, T. J.; Vogelstein, B. & Holman, H.
Object Type: Article
System: The UNT Digital Library
100-B/C Target Analyte List Development for Soil (open access)

100-B/C Target Analyte List Development for Soil

This report documents the process used to identify source area target analytes in support of the 100-B/C remedial investigation/feasibility study addendum to DOE/RL-2008-46. This report also establishes the analyte exclusion criteria applicable for 100-B/C use and the analytical methods needed to analyze the target analytes.
Date: March 18, 2010
Creator: Ovink, R.W.
Object Type: Report
System: The UNT Digital Library
Phil Wallace and Theoretical Physics at McGill in the 1950's: A Personal Perspective (open access)

Phil Wallace and Theoretical Physics at McGill in the 1950's: A Personal Perspective

In 1946 Philip (Phil) Russell Wallace joined the Mathematics Department of McGill University as an Associate Professor of Applied Mathematics, apparently because A. H. S. Gillson, Dean of Arts and Science, wanted theoretical physicists to be in the Mathematics Department. He came with the dream of creating a theoretical physics group at McGill. By the spring of 1949, Phil was authorized to recruit two junior faculty in Mathematics. He hired Theodore (Ted) F. Morris from U. Toronto, who joined in September 1949, and me, who came in January 1950. The group had begun. Phil Wallace was born in Toronto in 1915 and grew up there. He entered the University of Toronto in 1933, earned a B.A. in mathematics in 1937, a M.A. in 1938, and a Ph.D. in applied mathematics in 1940 under Leopold Infeld. His Ph.D. thesis in general relativity was entitled 'On the relativistic equations of motion in electromagnetic theory.' In 1940 World War II had engulfed Europe and was having its effect on Canada, but the US was still at peace. L. J. Synge, Head of the Applied Mathematics Department at Toronto, told Wallace that people such as he would be needed in war work, but things …
Date: November 18, 2010
Creator: Jackson, John David
Object Type: Article
System: The UNT Digital Library
Room-temperature Formation of Hollow Cu2O Nanoparticles (open access)

Room-temperature Formation of Hollow Cu2O Nanoparticles

Monodisperse Cu and Cu2O nanoparticles (NPs) are synthesized using tetradecylphosphonic acid as a capping agent. Dispersing the NPs in chloroform and hexane at room temperature results in the formation of hollow Cu2O NPs and Cu@Cu2O core/shell NPs, respectively. The monodisperse Cu2O NPs are used to fabricate hybrid solar cells with efficiency of 0.14percent under AM 1.5 and 1 Sun illumination.
Date: January 18, 2010
Creator: Hung, Ling-I; Tsung, Chia-Kuang; Huang, Wenyu & Yang, Peidong
Object Type: Article
System: The UNT Digital Library
Assessing Equivalent Viscous Damping Using Piping System Test Results (open access)

Assessing Equivalent Viscous Damping Using Piping System Test Results

The specification of damping for nuclear piping systems subject to seismic-induced motions has been the subject of many studies and much controversy. Damping estimation based on test data can be influenced by numerous factors, consequently leading to considerable scatter in damping estimates in the literature. At present, nuclear industry recommendations and nuclear regulatory guidance are not consistent on the treatment of damping for analysis of nuclear piping systems. Therefore, there is still a need to develop a more complete and consistent technical basis for specification of appropriate damping values for use in design and analysis. This paper summarizes the results of recent damping studies conducted at Brookhaven National Laboratory.
Date: July 18, 2010
Creator: Nie, J. & Morante, R.
Object Type: Article
System: The UNT Digital Library
REGULATORY ISSUES ASSOCIATED WITH SHIPMENT OF SMALL QUANTITIES OF RADIOACTIVE MATERIAL (open access)

REGULATORY ISSUES ASSOCIATED WITH SHIPMENT OF SMALL QUANTITIES OF RADIOACTIVE MATERIAL

None
Date: February 18, 2010
Creator: Smith, A.; Abramczyk, G. & Nathan, S.
Object Type: Article
System: The UNT Digital Library
Water Research Consortium U.S. Department of Energy Grant Award Number DE-FG02-05ER64132 Final Technical Report For Period Beginning: 15 September 2005 And Ending: 31 December 2009 Report Date: 16 March 2010 (open access)

Water Research Consortium U.S. Department of Energy Grant Award Number DE-FG02-05ER64132 Final Technical Report For Period Beginning: 15 September 2005 And Ending: 31 December 2009 Report Date: 16 March 2010

This report summarizes the activities of the INRA Water Research Consortium (IWRC) for the period beginning September 15, 2005 and ending December 16, 2010. This report compares accomplishments to project objectives, documents the activities associated with this project, and lists products developed during the course of the project. The Water Resources Research Needs Assessment team received funding from the Inland Northwest Research Alliance Water Resources Steering Committee to facilitate a structured needs assessment process that could provide a basis for future targeted research efforts to improve regional water resources management in the Inland Northwest region. The original INRA proposal specifically mentions the need to conduct a detailed assessment of the information and research needs of policy makers and water user groups during a period of increasing competition for scarce water supplies. A particular focus of this assessment would be to understand what types of research might facilitate water resource management during periods of drought. The specific goals of the Needs Assessment project were to: (1) Quickly ascertain the perceptions of diverse stakeholders in this region; (2) Condense this complex information into a format that can be shared with the INRA scientific panel, and (3) Develop of a realistic set of …
Date: March 18, 2010
Creator: Billingsley, Steven R.
Object Type: Report
System: The UNT Digital Library
SYNTHESIS AND CHARACTERIZATION OF PROTON CONDUCTORS (open access)

SYNTHESIS AND CHARACTERIZATION OF PROTON CONDUCTORS

The morphological and electrical properties of yttrium (Y) and indium (In) doped barium cerate perovskites of the form BaIn{sub 0.3-x}Y{sub x}Ce{sub 0.7}O{sub 3-{delta}} (with x=0-0.3) prepared by a modified Pechini method were investigated as potential high temperature proton conductors with improved chemical stability. The sinterability increased with the increase of In-doping, and the perovskite phase was found in the BaIn{sub 0.3-x}Y{sub x}Ce{sub 0.7}O{sub 3-{delta}} solid solutions over the range 0 {le} x {le} 0.3. The conductivities decreased (from x to x, insert quantitative values) while the tolerance to wet CO{sub 2} improved for BaIn{sub 0.3-x}Y{sub x}Ce{sub 0.7}O{sub 3-{delta}} samples with an increase of In-doping.
Date: February 18, 2010
Creator: Brinkman, K.
Object Type: Article
System: The UNT Digital Library
Final Report [Regulated mRNA Decay in Arabidopsis: A global analysis of differential control by hormones and the circadian clock] (open access)

Final Report [Regulated mRNA Decay in Arabidopsis: A global analysis of differential control by hormones and the circadian clock]

The long-term goal of this research was to better understand the influence of mRNA stability on gene regulation, particularly in response to hormones and the circadian clock. The primary aim of this project was to examine this using DNA microarrays, small RNA analysis and other approaches. We accomplished these objectives, although we were only able to detect small changes in mRNA stability in response to these stimuli. However, the work also contributed to a major breakthrough allowing the identification of small RNAs on a genomic scale in eukaryotes. Moreover, the project prompted us to develop a new way to analyze mRNA decay genome wide. Thus, the research was hugely successful beyond our objectives.
Date: March 18, 2010
Creator: Green, Pamela J.
Object Type: Report
System: The UNT Digital Library
Simulations of NSTX with a Liquid Lithium Divertor Module (open access)

Simulations of NSTX with a Liquid Lithium Divertor Module

A strategy to develop self-consistent simulations of the behavior of lithium in the Liquid Lithium Divertor (LLD) module to be installed in NSTX is described. In this initial stage of the plan, the UEDGE edge plasma transport code is used to simulate an existing NSTX shot, with UEDGE's transport coefficients set using midplane and divertor diagnostic data. The LLD is incorporated into the simulations as a reduction in the recycling coefficient over the outer divertor. Heat transfer calculations performed using the resulting heat flux profiles provide preliminary estimates on operating limits for the LLD as well as input data for subsequent steps in the LLD modeling effort.
Date: February 18, 2010
Creator: D.P. Stotler, R. Maingi, L.E. Zakharov, H.W. Kugel, A. Yu. Pigarov, T.D. Rognlien, and V.A. Soukhanovskii
Object Type: Report
System: The UNT Digital Library
Development of a 10 picosecond time-of-flight Counter (open access)

Development of a 10 picosecond time-of-flight Counter

This Advanced Detector Research proposal presented a plan to develop an extremely fast time-of-flight detector for measuring the arrival time of beam protons scattered at small angles in high energy hadron colliders, such as the Large Hadron Collider (LHC). The proposed detectors employ a gas or quartz Cerenkov radiator which produce light when a proton passes through them, coupled to a micro-channel plate photomultiplier tube (MCP-PMT) that converts the light to an electrical pulse. The very small jitter of the pulse time provided by the MCP-PMT, combined with downstream electronics that accurately measure the pulse time results in a time-of-flight measurement of unprecedented accuracy. This ADR proposal was extremely successful, culminating in the development of a 10 ps resolution time-of-flight system, about an order of magnitude better than any time-of-flight system previously deployed at a collider experiment. The primary areas of advance were the usage of new radiator geometries providing fast detector signals, using multiple measurements to obtain a superior system resolution, and development of an electronics readout system tuned to maintain the excellent timing afforded by the detector. Test beam and laser tests have improved the knowledge of MCP-PMT’s and enabled the evaluation of the new detector concepts. In …
Date: March 18, 2010
Creator: Brandt, Andrew G
Object Type: Report
System: The UNT Digital Library
Extended Simulations of Graphene Growth with Updated Rate Coefficients (open access)

Extended Simulations of Graphene Growth with Updated Rate Coefficients

New simulations of graphene growth in flame environments are presented. The simulations employ a kinetic Monte Carlo (KMC) algorithm coupled to molecular mechanics (MM) geometry optimization to track individual graphenic species as they evolve. Focus is given to incorporation of five-member rings and resulting curvature and edge defects. The model code has been re-written to be more computationally efficient enabling a larger set of simulations to be run, decreasing stochastic fluctuations in the averaged results. The model also includes updated rate coefficients for graphene edge reactions recently published in the literature. The new simulations are compared to results from the previous model as well as to hydrogen to carbon ratios recorded in experiment and calculated with alternate models.
Date: March 18, 2010
Creator: Whitesides, R.; You, X. & Frenklach, M.
Object Type: Article
System: The UNT Digital Library
TRISO-Fuel Element Performance Modeling for the Hybrid LIFE Engine with Pu Fuel Blanket (open access)

TRISO-Fuel Element Performance Modeling for the Hybrid LIFE Engine with Pu Fuel Blanket

A TRISO-coated fuel thermo-mechanical performance study is performed for the hybrid LIFE engine to test the viability of TRISO particles to achieve ultra-high burnup of a weapons-grade Pu blanket. Our methodology includes full elastic anisotropy, time and temperature varying material properties for all TRISO layers, and a procedure to remap the elastic solutions in order to achieve fast fluences up to 30 x 10{sup 25} n {center_dot} m{sup -2} (E > 0.18 MeV). In order to model fast fluences in the range of {approx} 7 {approx} 30 x 10{sup 25} n {center_dot} m{sup -2}, for which no data exist, careful scalings and extrapolations of the known TRISO material properties are carried out under a number of potential scenarios. A number of findings can be extracted from our study. First, failure of the internal pyrolytic carbon (PyC) layer occurs within the first two months of operation. Then, the particles behave as BISO-coated particles, with the internal pressure being withstood directly by the SiC layer. Later, after 1.6 years, the remaining PyC crumbles due to void swelling and the fuel particle becomes a single-SiC-layer particle. Unrestrained by the PyC layers, and at the temperatures and fluences in the LIFE engine, the SiC …
Date: February 18, 2010
Creator: DeMange, P.; Marian, J.; Caro, M. & Caro, A.
Object Type: Article
System: The UNT Digital Library
Material Design, Selection, and Manufacturing Methods for System Sustainment (open access)

Material Design, Selection, and Manufacturing Methods for System Sustainment

This paper describes a material selection and validation process proven to be successful for manufacturing high-reliability long-life product. The National Secure Manufacturing Center business unit of the Kansas City Plant (herein called KCP) designs and manufactures complex electrical and mechanical components used in extreme environments. The material manufacturing heritage is founded in the systems design to manufacturing practices that support the U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA). Material Engineers at KCP work with the systems designers to recommend materials, develop test methods, perform analytical analysis of test data, define cradle to grave needs, present final selection and fielding. The KCP material engineers typically will maintain cost control by utilizing commercial products when possible, but have the resources and to develop and produce unique formulations as necessary. This approach is currently being used to mature technologies to manufacture materials with improved characteristics using nano-composite filler materials that will enhance system design and production. For some products the engineers plan and carry out science-based life-cycle material surveillance processes. Recent examples of the approach include refurbished manufacturing of the high voltage power supplies for cockpit displays in operational aircraft; dry film lubricant application to improve bearing life for guided munitions …
Date: February 18, 2010
Creator: David Sowder, Jim Lula, Curtis Marshall
Object Type: Article
System: The UNT Digital Library
Demonstrating Structural Adequacy of Nuclear Power Plant Containment Structures for Beyond Design-Basis Pressure Loadings (open access)

Demonstrating Structural Adequacy of Nuclear Power Plant Containment Structures for Beyond Design-Basis Pressure Loadings

ABSTRACT Demonstrating the structural integrity of U.S. nuclear power plant (NPP) containment structures, for beyond design-basis internal pressure loadings, is necessary to satisfy Nuclear Regulatory Commission (NRC) requirements and performance goals. This paper discusses methods for demonstrating the structural adequacy of the containment for beyond design-basis pressure loadings. Three distinct evaluations are addressed: (1) estimating the ultimate pressure capacity of the containment structure (10 CFR 50 and US NRC Standard Review Plan, Section 3.8) ; (2) demonstrating the structural adequacy of the containment subjected to pressure loadings associated with combustible gas generation (10 CFR 52 and 10 CFR 50); and (3) demonstrating the containment structural integrity for severe accidents (10 CFR 52 as well as SECY 90-016, SECY 93-087, and related NRC staff requirements memoranda (SRMs)). The paper describes the technical basis for specific aspects of the methods presented. It also presents examples of past issues identified in licensing activities related to these evaluations.
Date: July 18, 2010
Creator: Braverman, J. I. & Morante, R.
Object Type: Article
System: The UNT Digital Library

Research Needs in Wind Energy

This presentation discusses the challenges and opportunities of wind energy.
Date: November 18, 2010
Creator: Schreck, S.
Object Type: Presentation
System: The UNT Digital Library

Technoeconomic Analysis of Biomethane Production from Biogas and Pipeline Delivery

This presentation summarizes "A Technoeconomic Analysis of Biomethane Production from Biogas and Pipeline Delivery".
Date: October 18, 2010
Creator: Jalalzadeh-Azar, A.
Object Type: Presentation
System: The UNT Digital Library
On the Correct Application of the 100-40-40 Rule for Combining Responses Due to three Directions of Earthquake Loading (open access)

On the Correct Application of the 100-40-40 Rule for Combining Responses Due to three Directions of Earthquake Loading

The 100-40-40 rule is often used with the response spectrum analysis method to determine the maximum seismic responses from structural responses resulting from the three spatial earthquake components. This rule has been referenced in several recent Design Certification applications of nuclear power plants, and appears to be gaining in popularity. However, this rule is described differently in ASCE 4-98 and Regulatory Guide 1.92, consequently causing confusion on correct implementation of this rule in practice. The square root of the sum of the squares method is another acceptable spatial combination method and was used to justify the adequacy of the 100-40-40 rule during the development of the Regulatory Guide 1.92. The 100-40-40 rule, when applied correctly, is almost always conservative compared to the SRSS method, and is only slightly unconservative in rare cases. The purpose of this paper is to describe in detail the proper application of the 100-40-40 rule, as prescribed in ASCE 4-98 and in Regulatory Guide 1.92, and to clarify the confusion caused by the two different formats of this rule.
Date: July 18, 2010
Creator: Nie, J.; Morante, R.; Miranda, M. & Braverman, J.
Object Type: Article
System: The UNT Digital Library
Comparison of Ambient Radon Concentrations in Air in the Northern Mojave Desert from Continuous and Integrating Instruments (open access)

Comparison of Ambient Radon Concentrations in Air in the Northern Mojave Desert from Continuous and Integrating Instruments

As part of a program to characterize and baseline environmental parameters, ambient radon-222 (Rn) monitoring was conducted in the rural community of Amargosa Valley, NV, the closest community to Yucca Mountain. Passive integrating and continuous Rn monitoring instruments were deployed adjacent to the Community Environmental Monitoring Program (CEMP) station in Amargosa Valley. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated Rn measurements, verified the meteorological data collected by the continuous Rn monitoring instrument, and for provided instrumentation for evaluating the relationships between meteorological conditions and Rn concentrations. Hourly Rn concentrations in air measured by the continuous Rn monitoring instrument (AlphaGUARD®) were compared to the average hourly values for the integrating Rn measurements (E-PERM®) by dividing the total Rn measurements by the number of hours the instruments were deployed. The results of the comparison indicated that average hourly ambient Rn concentrations as measured by both methods ranged from 0.2 to 0.4 pico-curies per liter of air. Ambient Rn values for the AlphaGUARD exhibited diurnal variations. When Rn concentrations were compared with measurements of temperature (T), barometric pressure, and relative humidity, the correlation (inversely) was highest with T, albeit weakly.
Date: May 18, 2010
Creator: Shafer, David S.; McGraw, David; Karr, Lynn H.; McCurdy, Greg; Kluesner, Tammy L.; Gray, Karen J. et al.
Object Type: Report
System: The UNT Digital Library