2,827 Matching Results

Results open in a new window/tab.

Double Gap Alfvén Eigenmodes: Revisiting Eigenmodes Interaction with the Alfvén Continuum (open access)

Double Gap Alfvén Eigenmodes: Revisiting Eigenmodes Interaction with the Alfvén Continuum

A new type of global shear Alfvén Eigenmode is found in tokamak plasmas where the mode localization is in the region intersecting the Alfvén continuum. The eigenmode is formed by the coupling of two solutions from two adjacent gaps (akin to potential wells) in the shear Alfvén continuum. For tokamak plasmas with reversed magnetic shear it is shown that the toroidiciy-induced solution tunnels through the continuum to match the ellipticity-induced Alfvén eigenmode (TAE and EAE, respectively) so that the resulting solution is continuous at the point of resonance with the continuum. The existence of these Double Gap Alfvén Eigenmodes (DGAEs) allows for potentially new ways of coupling edge fields to the plasma core in conditions where the core region is conventionally considered inaccessible. Implications include new approaches to heating and current drive in fusion plasmas as well as its possible use as core diagnostic in burning plasmas.
Date: December 1, 2005
Creator: Gorelenkov, N. N.
Object Type: Article
System: The UNT Digital Library
Leading by Example with Smart Energy Management (Fact Sheet) (open access)

Leading by Example with Smart Energy Management (Fact Sheet)

The Federal Energy Management Program facilitates the Federal Government?s implementation of sound, cost-effective energy management and investment practices to enhance the nation?s energy security and environmental stewardship. FEMP does this by focusing on the needs of its Federal customers, delivering an array of products grouped into project transaction services, applied technology services, and decision support services. This document outlines FEMP services and programs.
Date: December 1, 2008
Creator: unknown
Object Type: Report
System: The UNT Digital Library
SOFC Interconnect Work at NETL (open access)

SOFC Interconnect Work at NETL

None
Date: December 1, 2007
Creator: Jablonski, P. D. & Alman, D. E.
Object Type: Article
System: The UNT Digital Library
Lattice QCD workflows (open access)

Lattice QCD workflows

This paper discusses the application of existing workflow management systems to a real world science application (LQCD). Typical workflows and execution environment used in production are described. Requirements for the LQCD production system are discussed. The workflow management systems Askalon and Swift were tested by implementing the LQCD workflows and evaluated against the requirements. We report our findings and future work.
Date: December 1, 2008
Creator: Piccoli, Luciano; Kowalkowski, James B.; Simone, James N.; Sun, Xian-He; Jin, Hui; Holmgren, Donald J. et al.
Object Type: Article
System: The UNT Digital Library
ACRF Instrumentation Status: New, Current, and Future - November 2008 (open access)

ACRF Instrumentation Status: New, Current, and Future - November 2008

The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Climate Research Facility instrumentation status. The report is divided into the following five sections: (1) new instrumentation in the process of being acquired and deployed, (2) field campaigns, (3) existing instrumentation and progress on improvements or upgrades, (4) proposed future instrumentation, and (5) Small Business Innovation Research instrument development.
Date: December 1, 2008
Creator: Voyles, J. W.
Object Type: Report
System: The UNT Digital Library
Critical Infrastructure Protection Decision Support System Decision Model : Overview and Quick-Start User's Guide. (open access)

Critical Infrastructure Protection Decision Support System Decision Model : Overview and Quick-Start User's Guide.

The Critical Infrastructure Protection Decision Support System Decision Model (CIPDSS-DM) is a useful tool for comparing the effectiveness of alternative risk-mitigation strategies on the basis of CIPDSS consequence scenarios. The model is designed to assist analysts and policy makers in evaluating and selecting the most effective risk-mitigation strategies, as affected by the importance assigned to various impact measures and the likelihood of an incident. A typical CIPDSS-DM decision map plots the relative preference of alternative risk-mitigation options versus the annual probability of an undesired incident occurring once during the protective life of the investment, assumed to be 20 years. The model also enables other types of comparisons, including a decision map that isolates a selected impact variable and displays the relative preference for the options of interest--parameterized on the basis of the contribution of the isolated variable to total impact, as well as the likelihood of the incident. Satisfaction/regret analysis further assists the analyst or policy maker in evaluating the confidence with which one option can be selected over another.
Date: December 1, 2008
Creator: Samsa, M.; Van Kuiken, J.; Jusko, M. & Sciences, Decision and Information
Object Type: Report
System: The UNT Digital Library
Local Dynamic Reactive Power for Correction of System Voltage Problems (open access)

Local Dynamic Reactive Power for Correction of System Voltage Problems

Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors …
Date: December 1, 2008
Creator: Kueck, John D; Rizy, D Tom; Li, Fangxing; Xu, Yan; Li, Huijuan; Adhikari, Sarina et al.
Object Type: Report
System: The UNT Digital Library

Getting the Word Out: Diesel Exhaust Fluid (DEF) Locator, Mapping Tools, and Outreach Activities

Presentation covers diesel exhaust fluid resources on the Alternative Fuels and Advanced Vehicles Data Center.
Date: December 1, 2008
Creator: Brodt-Giles, Debbie
Object Type: Presentation
System: The UNT Digital Library
Observation of the Decay B+-(c) ---> J/psi pi+- and Measurement of the B+-(c) Mass (open access)

Observation of the Decay B+-(c) ---> J/psi pi+- and Measurement of the B+-(c) Mass

The B{sub c}{sup {+-}} meson is observed through the decay B{sub c}{sup {+-}} {yields} J/{psi} {pi}{sup {+-}}, in data corresponding to an integrated luminosity of 2.4 fb{sup -1} recorded by the CDF II detector at the Fermilab Tevatron. A signal of 108 {+-} 15 candidates is observed, with a significance that exceeds 8{sigma}. The mass of the B{sub c}{sup {+-}} meson is measured to be 6275.6 {+-} 2.9(stat.) {+-} 2.5(syst.) MeV/c{sup 2}.
Date: December 1, 2007
Creator: Aaltonen, T.
Object Type: Article
System: The UNT Digital Library
Status of FNAL SciBooNE experiment (open access)

Status of FNAL SciBooNE experiment

SciBooNE is a new experiment at FNAL which will make precision neutrino-nucleus cross section measurements in the one GeV region. These measurements are essential for the future neutrino oscillation experiments. We started data taking in the antineutrino mode on June 8, 2007, and collected 5.19 x 10{sup 19} protons on target (POT) before the accelerator shutdown in August. The first data from SciBooNE are reported in this article.
Date: December 1, 2007
Creator: Nakajima, Yasuhiro & U., /Kyoto
Object Type: Article
System: The UNT Digital Library
Catalytic diodes for micropower applications : verification of high energy conversion efficiency. (open access)

Catalytic diodes for micropower applications : verification of high energy conversion efficiency.

None
Date: December 1, 2007
Creator: Bogart, Katherine Huderle Andersen; Koleske, Daniel David; Creighton, James Randall; Cross, Karen Charlene & Heller, Edwin J.
Object Type: Report
System: The UNT Digital Library
Large-Scale Transport Model Uncertainty and Sensitivity Analysis: Distributed Sources in Complex Hydrogeologic Systems (open access)

Large-Scale Transport Model Uncertainty and Sensitivity Analysis: Distributed Sources in Complex Hydrogeologic Systems

The Underground Test Area (UGTA) Project of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office is in the process of assessing and developing regulatory decision options based on modeling predictions of contaminant transport from underground testing of nuclear weapons at the Nevada Test Site (NTS). The UGTA Project is attempting to develop an effective modeling strategy that addresses and quantifies multiple components of uncertainty including natural variability, parameter uncertainty, conceptual/model uncertainty, and decision uncertainty in translating model results into regulatory requirements. The modeling task presents multiple unique challenges to the hydrological sciences as a result of the complex fractured and faulted hydrostratigraphy, the distributed locations of sources, the suite of reactive and non-reactive radionuclides, and uncertainty in conceptual models. Characterization of the hydrogeologic system is difficult and expensive because of deep groundwater in the arid desert setting and the large spatial setting of the NTS. Therefore, conceptual model uncertainty is partially addressed through the development of multiple alternative conceptual models of the hydrostratigraphic framework and multiple alternative models of recharge and discharge. Uncertainty in boundary conditions is assessed through development of alternative groundwater fluxes through multiple simulations using the regional groundwater flow model. Calibration of alternative …
Date: December 1, 2007
Creator: Sig Drellack, Lance Prothro
Object Type: Article
System: The UNT Digital Library
P3 microengine development at Washington State University. (open access)

P3 microengine development at Washington State University.

There is a pressing need for miniaturized power systems for a variety of applications requiring a long life in the field of operations. Such power systems are required to be capable of providing power for months to years of operation, which all but eliminates battery technologies and technologies that bring their own fuel systems (except for nuclear fuel systems, which have their own drawbacks) due to constraints of having the all of the chemical fuel necessary for the entire life of the operational run available at the starting point of the operation. Alternatively, harvesting energy directly from the local environment obviates this need for bringing along all of the fuel necessary for operation. Instead, locally available energy, either in the form of chemical, thermal, light, or motion can be harvested and converted into electrical energy for use in sensor applications. The work from this LDRD is focused on developing a thermal engine that can take scavenged thermal gradients and convert them into direct electrical energy. The converter system is a MEMS based external combustion engine that uses a modified Stirling cycle to generate mechanical work on a piezoelectric generator. This piezoelectric generator then produced an AC voltage and current that …
Date: December 1, 2004
Creator: Whalen, Scott (Washington State University, Pullman, WA) & Apblett, Christopher Alan
Object Type: Report
System: The UNT Digital Library
Approximate analytical solutions for continuously focused beamsand single-species plasmas in thermal equilibrium (open access)

Approximate analytical solutions for continuously focused beamsand single-species plasmas in thermal equilibrium

None
Date: December 1, 2008
Creator: Startsev, Edward A. & Lund, Steven M.
Object Type: Article
System: The UNT Digital Library
Heavy Flavor Measurements at RHIC in the Near Future (open access)

Heavy Flavor Measurements at RHIC in the Near Future

We discuss the recent results on open charm measurements at RHIC. The heavy flavor upgrade program for both PHENIX and STAR experiments are briefly discussed. The completion of the program will yield important information on light flavor thermalization of the partonic matter created in high-energy nuclear collisions at RHIC. A new era of RHIC is ahead of us with the progress of the upgrade program.
Date: December 1, 2006
Creator: Xu, Nu
Object Type: Article
System: The UNT Digital Library
Analysis of Protein-RNA and Protein-Peptide Interactions in Equine Infectious Anemia (open access)

Analysis of Protein-RNA and Protein-Peptide Interactions in Equine Infectious Anemia

Macromolecular interactions are essential for virtually all cellular functions including signal transduction processes, metabolic processes, regulation of gene expression and immune responses. This dissertation focuses on the characterization of two important macromolecular interactions involved in the relationship between Equine Infectious Anemia Virus (EIAV) and its host cell in horse: (1) the interaction between the EIAV Rev protein and its binding site, the Rev-responsive element (RRE) and (2) interactions between equine MHC class I molecules and epitope peptides derived from EIAV proteins. EIAV, one of the most divergent members of the lentivirus family, has a single-stranded RNA genome and carries several regulatory and structural proteins within its viral particle. Rev is an essential EIAV regulatory encoded protein that interacts with the viral RRE, a specific binding site in the viral mRNA. Using a combination of experimental and computational methods, the interactions between EIAV Rev and RRE were characterized in detail. EIAV Rev was shown to have a bipartite RNA binding domain contain two arginine rich motifs (ARMs). The RRE secondary structure was determined and specific structural motifs that act as cis-regulatory elements for EIAV Rev-RRE interaction were identified. Interestingly, a structural motif located in the high affinity Rev binding site is …
Date: December 1, 2007
Creator: Lee, Jae-Hyung
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Final report : compliant thermo-mechanical MEMS actuators, LDRD #52553. (open access)

Final report : compliant thermo-mechanical MEMS actuators, LDRD #52553.

Thermal actuators have proven to be a robust actuation method in surface-micromachined MEMS processes. Their higher output force and lower input voltage make them an attractive alternative to more traditional electrostatic actuation methods. A predictive model of thermal actuator behavior has been developed and validated that can be used as a design tool to customize the performance of an actuator to a specific application. This tool has also been used to better understand thermal actuator reliability by comparing the maximum actuator temperature to the measured lifetime. Modeling thermal actuator behavior requires the use of two sequentially coupled models, the first to predict the temperature increase of the actuator due to the applied current and the second to model the mechanical response of the structure due to the increase in temperature. These two models have been developed using Matlab for the thermal response and ANSYS for the structural response. Both models have been shown to agree well with experimental data. In a parallel effort, the reliability and failure mechanisms of thermal actuators have been studied. Their response to electrical overstress and electrostatic discharge has been measured and a study has been performed to determine actuator lifetime at various temperatures and operating …
Date: December 1, 2004
Creator: Walraven, Jeremy Allen; Baker, Michael Sean; Headley, Thomas Jeffrey & Plass, Richard Anton
Object Type: Report
System: The UNT Digital Library
Using Drell-Yan to probe the underlying event in Run II at Collider Detector at Fermilab (CDF) (open access)

Using Drell-Yan to probe the underlying event in Run II at Collider Detector at Fermilab (CDF)

We study the behavior of charged particles produced in association with Drell-Yan lepton-pairs in the region of the Z-boson in proton-antiproton collisions at 1.96 TeV. We use the direction of the Z-boson in each event to define 'toward', 'away', and 'transverse' regions. For Drell-Yan production (excluding the leptons) both the 'toward' and 'transverse' regions are very sensitive to the 'underlying event', which is defined as everything except the two hard scattered components. The data are corrected to the particle level and are then compared with several PYTHIA models (with multiple parton interactions) and HERWIG (without multiple parton interactions) at the particle level (i.e. generator level). The data are also compared with a previous analysis on the behavior of the 'underlying event' in high transverse momentum jet production. The goal is to produce data that can be used by the theorists to tune and improve the QCD Monte-Carlo models of the 'underlying event' that are used to simulate hadron-hadron collisions.
Date: December 1, 2008
Creator: Kar, Deepak
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Monitoring and Evaluation of Smolt Migration in the Columbia Basin : Volume XV : Evaluation of the 2007 Predictions of the Run-Timing of Wild and Hatchery-Reared Salmon and Steelhead Smolts to Rock Island, Lower Granite, McNary, John Day, and Bonneville Dams using Program RealTime. (open access)

Monitoring and Evaluation of Smolt Migration in the Columbia Basin : Volume XV : Evaluation of the 2007 Predictions of the Run-Timing of Wild and Hatchery-Reared Salmon and Steelhead Smolts to Rock Island, Lower Granite, McNary, John Day, and Bonneville Dams using Program RealTime.

Program RealTime provided monitoring and forecasting of the 2007 inseason outmigrations via the internet for 26 PIT-tagged stocks of wild ESU Chinook salmon and steelhead to Lower Granite and/or McNary dams, one PIT-tagged hatchery-reared ESU of sockeye salmon to Lower Granite Dam, one PIT-tagged wild stock of sockeye salmon to McNary Dam, and 20 passage-indexed runs-at-large, five each to Rock Island, McNary, John Day, and Bonneville dams. Nineteen stocks are of wild yearling Chinook salmon which were captured, PIT-tagged, and released at sites above Lower Granite Dam in 2007 and have at least one year's historical migration data previous to the 2007 migration. These stocks originate in 19 tributaries of the Salmon, Grande Ronde and Clearwater Rivers, all tributaries to the Snake River, and are subsequently detected through tag identification and monitored at Lower Granite Dam. Seven wild PIT-tagged runs-at-large of Snake or Upper Columbia River ESU salmon and steelhead were monitored at McNary Dam. Three wild PIT-tagged runs-at-large were monitored at Lower Granite Dam, consisting of the yearling and subyearling Chinook salmon and the steelhead runs. The hatchery-reared PIT-tagged sockeye salmon stock from Redfish Lake was monitored outmigrating through Lower Granite Dam. Passage-indexed stocks (stocks monitored by FPC passage …
Date: December 1, 2008
Creator: Griswold, Jim; Townsend, Richard L. & Skalski, John R.
Object Type: Report
System: The UNT Digital Library
Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents (open access)

Experimental Validation of Stratified Flow Phenomena, Graphite Oxidation, and Mitigation Strategies of Air Ingress Accidents

The US Department of Energy is performing research and development (R&D) that focuses on key phenomena that are important during challenging scenarios that may occur in the Next Generation Nuclear Plant (NGNP) Program / GEN-IV Very High Temperature Reactor (VHTR). Phenomena identification and ranking studies (PIRT) to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Schultz et al., 2006). Consequently, the development of advanced air ingress-related models and verification and validation (V&V) are very high priority for the NGNP program. Following a loss of coolant and system depressurization, air will enter the core through the break. Air ingress leads to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heat-up of the bottom reflector and the reactor core and will cause the release of fission products eventually. The potential collapse of the bottom reflector because of burn-off and the release of CO lead to serious safety problems. For estimation of the proper safety margin we need experimental data and tools, including accurate multi-dimensional thermal-hydraulic and reactor physics models, a burn-off model, and a fracture model. We also need to develop effective strategies to mitigate the effects of …
Date: December 1, 2008
Creator: Oh, Chang Ho; Kim, Eung Soo; No, Hee Cheon & Cho, Nam Zin
Object Type: Report
System: The UNT Digital Library
Head-Tail Modes for Strong Space Charge (open access)

Head-Tail Modes for Strong Space Charge

Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.
Date: December 1, 2008
Creator: Burov, Alexey
Object Type: Article
System: The UNT Digital Library
Effects of Overhangs on the Performance of ElectrochromicWindows (open access)

Effects of Overhangs on the Performance of ElectrochromicWindows

None
Date: December 1, 2005
Creator: Tavil, Aslihan & Lee, Eleanor S.
Object Type: Article
System: The UNT Digital Library
The Milky Way as a Kiloparsec-Scale Axionscope (open access)

The Milky Way as a Kiloparsec-Scale Axionscope

Very high energy gamma-rays are expected to be absorbed by the extragalactic background light over cosmological distances via the process of electron-positron pair production. Recent observations of cosmologically distant gamma-ray emitters by ground based gamma-ray telescopes have, however, revealed a surprising degree of transparency of the universe to very high energy photons. One possible mechanism to explain this observation is the oscillation between photons and axion-like-particles (ALPs). Here we explore this possibility further, focusing on photon-ALP conversion in the magnetic fields in and around gamma-ray sources and in the magnetic field of the Milky Way, where some fraction of the ALP flux is converted back into photons. We show that this mechanism can be efficient in allowed regions of the ALP parameter space, as well as in typical configurations of the Galactic Magnetic Field. As case examples, we consider the spectrum observed from two HESS sources: 1ES1101-232 at redshift z = 0.186 and H 2356-309 at z = 0.165. We also discuss features of this scenario which could be used to distinguish it from standard or other exotic models.
Date: December 1, 2007
Creator: Simet, Melanie; Hooper, Dan & Serpico, Pasquale D.
Object Type: Article
System: The UNT Digital Library
Demonstration of Mer-Cure Technology for Enhanced Mercury Control: Final Report (open access)

Demonstration of Mer-Cure Technology for Enhanced Mercury Control: Final Report

Alstom Power Inc. has completed a DOE/NETL-sponsored program (under DOE Cooperative Agreement No. De-FC26-07NT42776) to demonstrate Mer-Cure{trademark}, one of Alstom's mercury control technologies for coal-fired boilers. The Mer-Cure{trademark}system utilizes a small amount of Mer-Clean{trademark} sorbent that is injected into the flue gas stream for oxidation and adsorption of gaseous mercury. Mer-Clean{trademark} sorbents are carbon-based and prepared with chemical additives that promote oxidation and capture of mercury. The Mer-Cure{trademark} system is unique in that the sorbent is injected into an environment where the mercury capture kinetics is accelerated. The full-scale demonstration program originally included test campaigns at two host sites: LCRA's 480-MW{sub e} Fayette Unit No.3 and Reliant Energy's 190-MW{sub e} Shawville Unit No.3. The only demonstration tests actually done were the short-term tests at LCRA due to budget constraints. This report gives a summary of the demonstration testing at Fayette Unit No.3. The goals for this Mercury Round 3 program, established by DOE/NETL under the original solicitation, were to reduce the uncontrolled mercury emissions by 90% at a cost significantly less than 50% of the previous target of $60,000/lb mercury removed. The results indicated that Mer-Cure{trademark} technology could achieve mercury removal of 90% based on uncontrolled stack emissions. The estimated …
Date: December 1, 2008
Creator: Marion, John; O'Neill, Dave; Taugher, Kevin; Kang, Shin; Johnson, Mark; Pargac, Gerald et al.
Object Type: Report
System: The UNT Digital Library