Month

Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement (open access)

Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement

A new code and methodology are introduced for solving the fully general relativistic magnetohydrodynamic (GRMHD) equations using time-explicit, finite-volume discretization. The code has options for solving the GRMHD equations using traditional artificial-viscosity (AV) or non-oscillatory central difference (NOCD) methods, or a new extended AV (eAV) scheme using artificial-viscosity together with a dual energy-flux-conserving formulation. The dual energy approach allows for accurate modeling of highly relativistic flows at boost factors well beyond what has been achieved to date by standard artificial viscosity methods. it provides the benefit of Godunov methods in capturing high Lorentz boosted flows but without complicated Riemann solvers, and the advantages of traditional artificial viscosity methods in their speed and flexibility. Additionally, the GRMHD equations are solved on an unstructured grid that supports local adaptive mesh refinement using a fully threated oct-tree (in three dimensions) network to traverse the grid hierarchy across levels and immediate neighbors. A number of tests are presented to demonstrate robustness of the numerical algorithms and adaptive mesh framework over a wide spectrum of problems, boosts, and astrophysical applications, including relativistic shock tubes, shock collisions, magnetosonic shocks, Alfven wave propagation, blast waves, magnetized Bondi flow, and the magneto-rotational instability in Kerr black hole spacetimes.
Date: May 6, 2005
Creator: Anninos, P; Fragile, P C & Salmonson, J D
Object Type: Article
System: The UNT Digital Library
Dijet event shapes as diagnostic tools (open access)

Dijet event shapes as diagnostic tools

Event shapes have long been used to extract information about hadronic final states and the properties of QCD, such as particle spin and the running coupling. Recently, a family of event shapes, the angularities, has been introduced that depends on a continuous parameter. This additional parameter-dependence further extends the versatility of event shapes. It provides a handle on nonperturbative power corrections, on non-global logarithms, and on the flow of color in the final state.
Date: May 6, 2005
Creator: Berger, Carola F.
Object Type: Article
System: The UNT Digital Library
Fuel Cell Demonstration Project - 200 kW - Phosphoric Acid Fuel Cell Power Plant Located at the National Transportation Research Center: FINAL REPORT (open access)

Fuel Cell Demonstration Project - 200 kW - Phosphoric Acid Fuel Cell Power Plant Located at the National Transportation Research Center: FINAL REPORT

Oak Ridge National Laboratory (ORNL) researches and develops distributed generation technology for the Department of Energy, Energy Efficiency and Renewable Energy Distributed Energy Program. This report describes installation and operation of one such distributed generation system, a United Technology Corporation fuel cell located at the National Transportation Research Center in Knoxville, Tennessee. Data collected from June 2003 to June of 2004, provides valuable insight regarding fuel cell-grid compatibility and the cost-benefit of the fuel cell operation. The NTRC fuel cell included a high-heat recovery option so that use of thermal energy improves project economics and improves system efficiency to 59% year round. During the year the fuel cell supplied a total of 834MWh to the NTRC and provided 300MBtu of hot water. Installation of the NTRC fuel cell was funded by the Distributed Energy Program with partial funding from the Department of Defense's Climate Change Fuel Cell Buy Down Program, administered by the National Energy Technology Laboratory. On-going operational expenses are funded by ORNL's utility budget and are paid from operational cost savings. Technical information and the benefit-cost of the fuel cell are both evaluated in this report and sister reports.
Date: May 6, 2005
Creator: Berry, JB
Object Type: Report
System: The UNT Digital Library
Neutron Source Strength Estimates from (a, n) Reactions in Binary Mixtures of Actinide Particles and Light Element Particles (open access)

Neutron Source Strength Estimates from (a, n) Reactions in Binary Mixtures of Actinide Particles and Light Element Particles

The cumulative distribution of package dose rates, based on the 18 batches of historical PuO{sub 2} particle size distributions, is shown in Fig. 6 for ''Hanford 10-13% Pu-240'' plutonium. The calculated dose rates for all batches range from about 50 mrem/h to about 2,200 mrem/h, with over 50% of the batches being less than the 200 mrem/h limit for public transportation. A more refined analysis would show that almost all of the batches would be less than 200 mrem/h, but some could exceed this limit as seen by the distribution shape. Without detailed characterization of the BeO particle size distribution, additional analysis would not remove the uncertainty in these calculations. Because the actual amount of beryllium contamination is likely to be much less than 500 g, the dose rates would be expected to be much lower than those shown here. Based on the particle size distribution analysis of the 18 batches analyzed, it is also likely that most of the 3013 cans to be loaded in the 9975 Package will have dose rates that are less than the 200 mrem/h limit for the package surface. However, extra care will be required in performing, and verifying, the dose rate measurements at …
Date: May 6, 2005
Creator: Boles, J. L.; Hafner, R. S. & Fischer, L. E.
Object Type: Article
System: The UNT Digital Library
New Technologies for Standoff Assessment of Radiological Contamination (open access)

New Technologies for Standoff Assessment of Radiological Contamination

Technologies to rapidly quantify surface activity with minimal worker contact would dramatically decrease the radiation dose a radiation worker receives in assessment and cleanup operations, while obtaining a clear image of exactly where dispersed contamination is located. LLNL efforts in the development of the Photochromic Radiation Dosimeter and the Imaging Assessment System will be described. Initial use of these technologies in decontamination and decommissioning of contaminated facilities demonstrates several significant advantages over standard techniques such as survey meters and swipes.
Date: May 6, 2005
Creator: Cherepy, Nerine; Stevens, Charles; Wurtz, Ronald; Sanner, Robert; Frank, Michael; Tillotson, Thomas et al.
Object Type: Article
System: The UNT Digital Library
Quantum Monte Carlo using a Stochastic Poisson Solver (open access)

Quantum Monte Carlo using a Stochastic Poisson Solver

Quantum Monte Carlo (QMC) is an extremely powerful method to treat many-body systems. Usually quantum Monte Carlo has been applied in cases where the interaction potential has a simple analytic form, like the 1/r Coulomb potential. However, in a complicated environment as in a semiconductor heterostructure, the evaluation of the interaction itself becomes a non-trivial problem. Obtaining the potential from any grid-based finite-difference method, for every walker and every step is unfeasible. We demonstrate an alternative approach of solving the Poisson equation by a classical Monte Carlo within the overall quantum Monte Carlo scheme. We have developed a modified ''Walk On Spheres'' algorithm using Green's function techniques, which can efficiently account for the interaction energy of walker configurations, typical of quantum Monte Carlo algorithms. This stochastically obtained potential can be easily incorporated within popular quantum Monte Carlo techniques like variational Monte Carlo (VMC) or diffusion Monte Carlo (DMC). We demonstrate the validity of this method by studying a simple problem, the polarization of a helium atom in the electric field of an infinite capacitor.
Date: May 6, 2005
Creator: Das, D; Martin, R M & Kalos, M H
Object Type: Article
System: The UNT Digital Library
[Letter from Peter DeFazio, Earl Blumenauer, Darlene Hooley, and David Wu to Anthony Principi  - May 6, 2005] (open access)

[Letter from Peter DeFazio, Earl Blumenauer, Darlene Hooley, and David Wu to Anthony Principi - May 6, 2005]

Letter from Representatives Peter DeFazio, Earl Blumenauer, Darlene Hooley, and David Wu concerning Oregon's military installations.
Date: May 6, 2005
Creator: DeFazio, Peter, 1947-; Blumenauer, Earl; Hooley, Darlene & Wu, David
Object Type: Letter
System: The UNT Digital Library
Reactor Safety Planning for Prometheus Project, for Naval Reactors Information (open access)

Reactor Safety Planning for Prometheus Project, for Naval Reactors Information

The purpose of this letter is to submit to Naval Reactors the initial plan for the Prometheus project Reactor Safety work. The Prometheus project is currently developing plans for cold physics experiments and reactor prototype tests. These tests and facilities may require safety analysis and siting support. In addition to the ground facilities, the flight reactor units will require unique analyses to evaluate the risk to the public from normal operations and credible accident conditions. This letter outlines major safety documents that will be submitted with estimated deliverable dates. Included in this planning is the reactor servicing documentation and shipping analysis that will be submitted to Naval Reactors.
Date: May 6, 2005
Creator: Delmolino, P.
Object Type: Report
System: The UNT Digital Library
China-U.S. Relations: Current Issues and Implications for U.S. Policy (open access)

China-U.S. Relations: Current Issues and Implications for U.S. Policy

The bilateral relationship between the U.S. and the People's Republic of China (PRC) is vitally important, touching on a wide range of areas including, among others, economic policy, security, foreign relations, and human rights. This report addresses relevant policy questions in current U.S.-China relations, discusses trends and key legislation in the current Congress, and provides a chronology of developments and high-level exchanges.
Date: May 6, 2005
Creator: Dumbaugh, Kerry
Object Type: Report
System: The UNT Digital Library
The Effect of Solution Annealing on the Microstructural Behavior of Alloy 22 Welds (open access)

The Effect of Solution Annealing on the Microstructural Behavior of Alloy 22 Welds

Multi-pass gas tungsten arc welds of Alloy 22 were subjected to solution annealing durations of 20 minutes, 24 hours, 72 hours and 1 week at temperatures of 1075, 1121, 1200, and 1300 C. The specimens were studied in cross section by secondary electron microscopy to determine the effect of solution annealing on tetrahedrally close packed (TCP) precipitate stability. Electron backscatter diffraction mapping was also performed on all of the specimens to determine the recrystallization behavior of the welds. It was found that complete TCP precipitate dissolution occurs after solution annealing at 1075 C and 1121 C for 24 hours, and at 1200 C and 1300 C for durations of 20 minutes. Regions of most rapid recrystallization were correlated to the regions of lowest solute content and highest residual tensile stresses. Texture analysis indicated that while the columnar dendrites originally present in the weld grew with a <001> orientation in the transverse direction (opposite the heat flow direction), the recrystallized grains adopt a <101> orientation in the transverse direction when recrystallization and TCP phase dissolution occur simultaneously.
Date: May 6, 2005
Creator: El-Dasher, B S; Edgecumbe, T S & Torres, S G
Object Type: Article
System: The UNT Digital Library
Desiccant-Based Combined Systems: Integrated Active Desiccant Rooftop Hybrid System Development and Testing Final Report- Phase 4 (open access)

Desiccant-Based Combined Systems: Integrated Active Desiccant Rooftop Hybrid System Development and Testing Final Report- Phase 4

This report summarizes the results of a research and development (R&D) program to design and optimize an active desiccant-vapor compression hybrid rooftop system. The primary objective was to combine the strengths of both technologies to produce a compact, high-performing, energy-efficient system that could accommodate any percentage of outdoor air and deliver essentially any required combination of temperature and humidity, or sensible heat ratio (SHR). In doing so, such a product would address the significant challenges imposed on the performance capabilities of conventional packaged rooftop equipment by standards 62 and 90.1 of the American Society of Heating, Refrigerating and Air-Conditioning Engineers. The body of work completed as part of this program built upon previous R&D efforts supported by the U.S. Department of Energy and summarized by the Phase 3b report ''Active Desiccant Dehumidification Module Integration with Rooftop Packaged HVAC Units'' (Fischer and Sand 2002), in addition to Fischer, Hallstrom, and Sand 2000; Fischer 2000; and Fischer and Sand 2004. All initial design objectives established for this development program were successfully achieved. The performance flexibility desired was accomplished by a down-sized active desiccant wheel that processes only a portion of the supply airflow, which is pre-conditioned by a novel vapor compression cycle. …
Date: May 6, 2005
Creator: Fischer, J
Object Type: Report
System: The UNT Digital Library
Wireless Sensors and Networks for Advanced Energy Management (open access)

Wireless Sensors and Networks for Advanced Energy Management

Numerous national studies and working groups have identified low-cost, very low-power wireless sensors and networks as a critical enabling technology for increasing energy efficiency, reducing waste, and optimizing processes. Research areas for developing such sensor and network platforms include microsensor arrays, ultra-low power electronics and signal conditioning, data/control transceivers, and robust wireless networks. A review of some of the research in the following areas will be discussed: (1) Low-cost, flexible multi-sensor array platforms (CO{sub 2}, NO{sub x}, CO, humidity, NH{sub 3}, O{sub 2}, occupancy, etc.) that enable energy and emission reductions in applications such as buildings and manufacturing; (2) Modeling investments (energy usage and savings to drive capital investment decisions) and estimated uptime improvements through pervasive gathering of equipment and process health data and its effects on energy; (3) Robust, self-configuring wireless sensor networks for energy management; and (4) Quality-of-service for secure and reliable data transmission from widely distributed sensors. Wireless communications is poised to support technical innovations in the industrial community, with widespread use of wireless sensors forecasted to improve manufacturing production and energy efficiency and reduce emissions. Progress being made in wireless system components, as described in this paper, is helping bring these projected improvements to reality.
Date: May 6, 2005
Creator: Hardy, J. E.
Object Type: Report
System: The UNT Digital Library
Microfluidic gas flow profiling using remote detection NMR (open access)

Microfluidic gas flow profiling using remote detection NMR

Miniaturized fluid handling devices have recently attracted considerable interest in many areas of science1. Such microfluidic chips perform a variety of functions, ranging from analysis of biological macromolecules2,3 to catalysis of reactions and sensing in the gas phase4,5. To enable precise fluid handling, accurate knowledge of the flow properties within these devices is important. Due to low Reynolds numbers, laminar flow is usually assumed. However, either by design or unintentionally, the flow characteristic in small channels is often altered, for example by surface interactions, viscous and diffusional effects, or electrical potentials. Therefore, its prediction is not always straight-forward6-8. Currently, most microfluidic flow measurements rely on optical detection of markers9,10, requiring the injection of tracers and transparent devices. Here, we show profiles of microfluidic gas flow in capillaries and chip devices obtained by NMR in the remote detection modality11,12. Through the transient measurement of dispersion13, NMR is well adaptable for non-invasive, yet sensitive determination of the flow field and provides a novel and potentially more powerful tool to profile flow in capillaries and miniaturized flow devices.
Date: May 6, 2005
Creator: Hilty, Christian; McDonnell, Erin; Granwehr, Josef; Pierce,Kimberly; Han, Song-I Han & Pines, Alexander
Object Type: Article
System: The UNT Digital Library
Corona and Motor Voltage Interim Report (open access)

Corona and Motor Voltage Interim Report

It has been suggested that to meet the FreedomCAR objectives for cost, size, weight, efficiency, and reliability higher buss voltages be utilized in HEV and FC automotive applications. The reasoning is that since electric power is equal to the product of voltage and current for a given power a higher voltage and lower current would result in smaller cable and inverter switching components. Consequently, the system can be lighter and smaller. On the other hand, higher voltages are known to require better and thicker electrical insulation that reduce the available slot area for motor windings. One cause of slow insulation breakdown is corona that gradually erodes the insulation and shortens the life expectancy of the motor. This study reports on the results of a study on corona initiating voltages for mush-wound and bobbin-wound stators. A unique testing method is illustrated.
Date: May 6, 2005
Creator: Hsu, J.S.
Object Type: Report
System: The UNT Digital Library
PEP-II: An Asymmetric B Factory Based on PEP (open access)

PEP-II: An Asymmetric B Factory Based on PEP

An asymmetric B Factory to be installed in the PEP tunnel has been under study at SLAC, LBL, and LLNL for several years [1-4]. A mature design for a 9 GeV x 3.1 GeV electron-positron collider with a design luminosity of 3 x 10{sup 33} cm{sup -2}s{sup -1} is presented. Solutions now exist for all the technical problems, including issues related to high currents (e.g., beam instabilities, feedback systems, vacuum chamber design, lifetime degradation, and radiation power dissipation in the interaction region) and those related to different energies of the beams (e.g., beam separation, beam-beam interaction, and detector requirements). The status of this project, which is being proposed for funding in FY 1993, is discussed.
Date: May 6, 2005
Creator: Hutton, A & Zisman, M
Object Type: Article
System: The UNT Digital Library
Outsourcing and Insourcing Jobs in the U.S. Economy: An Overview of Evidence Based on Foreign Investment Data (open access)

Outsourcing and Insourcing Jobs in the U.S. Economy: An Overview of Evidence Based on Foreign Investment Data

None
Date: May 6, 2005
Creator: Jackson, James K.
Object Type: Report
System: The UNT Digital Library
Frequency Regulation Basics and Trends (open access)

Frequency Regulation Basics and Trends

The electric power system must address two unique requirements: the need to maintain a near real-time balance between generation and load, and the need to adjust generation (or load) to manage power flows through individual transmission facilities. These requirements are not new: vertically integrated utilities have been meeting them for a century as a normal part of conducting business. With restructuring, however, the services needed to meet these requirements, now called ''ancillary services'', are being more clearly defined. Ancillary services are those functions performed by the equipment and people that generate, control, and transmit electricity in support of the basic services of generating capacity, energy supply, and power delivery. The Federal Energy Regulatory Commission (FERC) has defined such services as those ''necessary to support the transmission of electric power from seller to purchaser given the obligations of control areas and transmitting utilities within those control areas to maintain reliable operations of the interconnected transmission system''. This statement recognizes the importance of ancillary services for both bulk-power reliability and support of commercial transactions. Balancing generation and load instantaneously and continuously is difficult because loads and generators are constantly fluctuating. Minute-to-minute load variability results from the random turning on and off of …
Date: May 6, 2005
Creator: Kirby, Brendan J.
Object Type: Report
System: The UNT Digital Library
Spinning Reserve from Pump Load: A Technical Findings Report to the California Department of Water Resources (open access)

Spinning Reserve from Pump Load: A Technical Findings Report to the California Department of Water Resources

The Oak Ridge National Laboratory (ORNL), at the request of the California Energy Commission and the U.S. Department of Energy, is investigating opportunities for electrical load to provide the ancillary service of spinning reserve to the electric grid. The load would provide this service by stopping for a short time when there is a contingency on the grid such as a transmission line or generator outage. There is a possibility that a significant portion of the California Independent System Operator's (CAISO's) spinning reserve requirement could be supplied from the California Department of Water Resources (CDWR) pumping load. Spinning reserve has never been supplied from load before, and rule changes would be needed to allow it. In this report, we are presenting technical findings on the possibility of supplying spinning reserve from pumping system load. In parallel, we are pursuing the needed rule changes with the North American Electric Reliability Council (NERC), the Federal Energy Regulatory Commission (FERC), the Western Electricity Coordinating Council (WECC), and the CAISO. NERC and FERC have agreed that they have no prohibition against supplying spinning reserve from load. The WECC Minimum Operability Reliability Criteria working group has agreed that the concept should be considered, and they …
Date: May 6, 2005
Creator: Kirby, Brendan J. & Kueck, John D.
Object Type: Report
System: The UNT Digital Library
Gun Legislation in the 109th Congress (open access)

Gun Legislation in the 109th Congress

Congress continues to debate the efficacy and constitutionality of federal regulation of firearms and ammunition. It is a contentious debate, with strong advocates for and against the further federal regulation of firearms.
Date: May 6, 2005
Creator: Krouse, William J.
Object Type: Report
System: The UNT Digital Library
Measurement Practices for Reliability and Power Quality (open access)

Measurement Practices for Reliability and Power Quality

This report provides a distribution reliability measurement ''toolkit'' that is intended to be an asset to regulators, utilities and power users. The metrics and standards discussed range from simple reliability, to power quality, to the new blend of reliability and power quality analysis that is now developing. This report was sponsored by the Office of Electric Transmission and Distribution, U.S. Department of Energy (DOE). Inconsistencies presently exist in commonly agreed-upon practices for measuring the reliability of the distribution systems. However, efforts are being made by a number of organizations to develop solutions. In addition, there is growing interest in methods or standards for measuring power quality, and in defining power quality levels that are acceptable to various industries or user groups. The problems and solutions vary widely among geographic areas and among large investor-owned utilities, rural cooperatives, and municipal utilities; but there is still a great degree of commonality. Industry organizations such as the National Rural Electric Cooperative Association (NRECA), the Electric Power Research Institute (EPRI), the American Public Power Association (APPA), and the Institute of Electrical and Electronics Engineers (IEEE) have made tremendous strides in preparing self-assessment templates, optimization guides, diagnostic techniques, and better definitions of reliability and power …
Date: May 6, 2005
Creator: Kueck, JD
Object Type: Report
System: The UNT Digital Library
West Coast and Alaska Oil Exports (open access)

West Coast and Alaska Oil Exports

None
Date: May 6, 2005
Creator: Kumins, Larry
Object Type: Report
System: The UNT Digital Library
Tropical Intraseasonal Variability in 14 IPCC AR4 Climate Models Part I: Convective Signals (open access)

Tropical Intraseasonal Variability in 14 IPCC AR4 Climate Models Part I: Convective Signals

This study evaluates the tropical intraseasonal variability, especially the fidelity of Madden-Julian Oscillation (MJO) simulations, in 14 coupled general circulation models (GCMs) participating in the Inter-governmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). Eight years of daily precipitation from each model's 20th century climate simulation are analyzed and compared with daily satellite retrieved precipitation. Space-time spectral analysis is used to obtain the variance and phase speed of dominant convectively coupled equatorial waves, including the MJO, Kelvin, equatorial Rossby (ER), mixed Rossby-gravity (MRG), and eastward inertio-gravity (EIG) and westward inertio-gravity (WIG) waves. The variance and propagation of the MJO, defined as the eastward wavenumbers 1-6, 30-70 day mode, are examined in detail. The results show that current state-of-the-art GCMs still have significant problems and display a wide range of skill in simulating the tropical intraseasonal variability. The total intraseasonal (2-128 day) variance of precipitation is too weak in most of the models. About half of the models have signals of convectively coupled equatorial waves, with Kelvin and MRG-EIG waves especially prominent. However, the variances are generally too weak for all wave modes except the EIG wave, and the phase speeds are generally too fast, being scaled to excessively deep …
Date: May 6, 2005
Creator: Lin, J.; Kiladis, G. N.; Mapes, B. E.; Weickmann, K. M.; Sperber, K. R.; Lin, W. et al.
Object Type: Article
System: The UNT Digital Library
ELECTROMAGNETIC SIMULATIONS OF HELICAL-BASED ION ACCELERATION STRUCTURES (open access)

ELECTROMAGNETIC SIMULATIONS OF HELICAL-BASED ION ACCELERATION STRUCTURES

Helix structures have been proposed [1] for accelerating low energy ion beams using MV/m fields in order to increase the coupling efficiency of the pulsed power system and to tailor the electromagnetic wave propagation speed with the particle beam speed as the beam gains energy. Calculations presented here show the electromagnetic field as it propagates along the helix structure, field stresses around the helix structure (for voltage breakdown determination), optimizations to the helix and driving pulsed power waveform, and simulations showing test particles interacting with the simulated time varying fields.
Date: May 6, 2005
Creator: Nelson, S D; Caporaso, G; Friedman, A; Poole, B R; Briggs, R & Waldron, W
Object Type: Article
System: The UNT Digital Library
North Korea's Nuclear Weapons Program (open access)

North Korea's Nuclear Weapons Program

None
Date: May 6, 2005
Creator: Niksch, Larry A.
Object Type: Report
System: The UNT Digital Library