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A 3-D model of superfluid helium suitable for numerical analysis (open access)

A 3-D model of superfluid helium suitable for numerical analysis

The two-fluid description is a very successful phenomenological representation of the properties of Helium II. A 3-D model suitable for numerical analysis based on the Landau-Khalatnikov description of Helium II is proposed. In this paper we introduce a system of partial differential equations that is both complete and consistent as well as practical, to be used for a 3-D solution of the flow of Helium II. The development of a 3-D numerical model for Helium II is motivated by the need to validate experimental results obtained by observing the normal component velocity distribution in a Helium II thermal counter-flow using the Particle Image Velocimetry (PIV) technique.
Date: January 1, 2008
Creator: Darve, C.; U., /Fermilab /Northwestern; Patankar, N.A.; U., /Northwestern; Van Sciver, S.W. & Lab., /Natl. High Mag. Field
System: The UNT Digital Library
2007 Inorganic Reaction Mechanisms Gordon Research Conference-February 18-23 (open access)

2007 Inorganic Reaction Mechanisms Gordon Research Conference-February 18-23

This conference focuses on kinetic, mechanistic, and thermodynamic studies of reactions that play a role in fields as diverse as catalysis, energy, bioinorganic chemistry, green chemistry, organometallics, and activation of small molecules (oxygen, nitrogen, carbon monoxide, carbon dioxide, alkanes). Participants from universities, industry, and national laboratories present results and engage in discussions of pathways, intermediates, and outcome of various reactions of inorganic, organic, coordination, organometallic, and biological species. This knowledge is essential for rational development and design of novel reactions, compounds, and catalysts.
Date: January 1, 2008
Creator: Gray, Andreja Bakac Nancy Ryan
System: The UNT Digital Library
2007 Microbial Population Biology (July 22-26, 2007) (open access)

2007 Microbial Population Biology (July 22-26, 2007)

Microbial Population Biology covers a diverse range of cutting edge issues in the microbial sciences and beyond. Firmly founded in evolutionary biology and with a strongly integrative approach, past meetings have covered topics ranging from the dynamics and genetics of adaptation to the evolution of mutation rate, community ecology, evolutionary genomics, altruism, and epidemiology. This meeting is never dull: some of the most significant and contentious issues in biology have been thrashed out here. We anticipate the 2007 meeting being no exception. The final form of the 2007 meeting is yet to be decided, but the following topics are likely to be included: evolutionary emergence of infectious disease and antibiotic resistance, genetic architecture and implications for the evolution of microbial populations, ageing in bacteria, biogeography, evolution of symbioses, the role of microbes in ecosystem function, and ecological genomics.
Date: April 1, 2008
Creator: Dean, Anthony M. & Gray, Nancy Ryan
System: The UNT Digital Library
2007 Radiation & Climate GRC ( July 29-August 3, 2007) (open access)

2007 Radiation & Climate GRC ( July 29-August 3, 2007)

The theme of the fifth Gordon Research Conference on Radiation and Climate is 'Integrating multiscale measurements and models for key climate questions'. The meeting will feature lectures, posters, and discussion regarding these issues. The meeting will focus on insights from new types of satellite and in situ data and from new approaches to modeling processes in the climate system. The program on measurements will highlight syntheses of new satellite data on cloud, aerosols, and chemistry and syntheses of satellite and sub-orbital observations from field programs. The program on modeling will address both the evaluation of cloud-resolving and regional aerosol models using new types of measurements and the evidence for processes and physics missing from global models. The Conference will focus on two key climate questions. First, what factors govern the radiative interactions of clouds and aerosols with regional and global climate? Second, how well do we understand the interaction of radiation with land surfaces and with the cryosphere?
Date: June 1, 2008
Creator: Gray, William Collins Nancy Ryan
System: The UNT Digital Library
2007 Renewable Energy: Solar Fuels Gordon Research Conference - January 21-26 (open access)

2007 Renewable Energy: Solar Fuels Gordon Research Conference - January 21-26

This Gordon Research Conference seeks to brings together chemists, physicists, materials scientists and biologists to address perhaps the outstanding technical problem of the 21st Century - the efficient, and ultimately economical, storage of energy from carbon-neutral sources. Such an advance would deliver a renewable, environmentally benign energy source for the future. A great technological challenge facing our global future is energy. The generation of energy, the security of its supply, and the environmental consequences of its use are among the world's foremost geopolitical concerns. Fossil fuels - coal, natural gas, and petroleum - supply approximately 90% of the energy consumed today by industrialized nations. An increase in energy supply is vitally needed to bring electric power to the 25% of the world's population that lacks it, to support the industrialization of developing nations, and to sustain economic growth in developed countries. On the geopolitical front, insuring an adequate energy supply is a major security issue for the world, and its importance will grow in proportion to the singular dependence on oil as a primary energy source. Yet, the current approach to energy supply, that of increased fossil fuel exploration coupled with energy conservation, is not scaleable to meet future demands. …
Date: February 1, 2008
Creator: Nocera, Daniel G.
System: The UNT Digital Library
A 2D Benchmark for the Verification of the PEBBED Code (open access)

A 2D Benchmark for the Verification of the PEBBED Code

A new benchmarking concept is presented for verifying the PEBBED 3D multigroup finite difference/nodal diffusion code with application to pebble bed modular reactors (PBMRs). The key idea is to perform convergence acceleration, also called extrapolation to zero discretization, of a basic finite difference numerical algorithm to give extremely high accuracy. The method is first demonstrated on a 1D cylindrical shell and then on an r,8 wedge where the order of the second order finite difference scheme is confirmed to four places.
Date: September 1, 2008
Creator: Ganapol, Barry D.; Gougar, Hans A. & Ougouag, A. O.
System: The UNT Digital Library
3D CFD Electrochemical and Heat Transfer Model of an Integrated-Planar Solid Oxide Electrolysis Cells (open access)

3D CFD Electrochemical and Heat Transfer Model of an Integrated-Planar Solid Oxide Electrolysis Cells

A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in a new novel integrated planar porous-tube supported solid oxide electrolysis cell (SOEC). The model is of several integrated planar cells attached to a ceramic support tube. This design is being evaluated with modeling at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean per-cell area-specific-resistance (ASR) values decrease with increasing current density. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, cathode and anode exchange current density, and contact resistance from the base case are presented. Contour plots …
Date: October 1, 2008
Creator: Hawkes, Grant & O'Brien, James E.
System: The UNT Digital Library
4th Generation ECR Ion Sources (open access)

4th Generation ECR Ion Sources

The concepts and technical challenges related to developing a 4th generation ECR ion source with an RF frequency greater than 40 GHz and magnetic confinement fields greater than twice Becr will be explored in this paper. Based on the semi-empirical frequency scaling of ECR plasma density with the square of operating frequency, there should be significant gains in performance over current 3rd generation ECR ion sources, which operate at RF frequencies between 20 and 30 GHz. While the 3rd generation ECR ion sources use NbTi superconducting solenoid and sextupole coils, the new sources will need to use different superconducting materials such as Nb3Sn to reach the required magnetic confinement, which scales linearly with RF frequency. Additional technical challenges include increased bremsstrahlung production, which may increase faster than the plasma density, bremsstrahlung heating of the cold mass and the availability of high power continuous wave microwave sources at these frequencies. With each generation of ECR ion sources, there are new challenges to be mastered, but the potential for higher performance and reduced cost of the associated accelerator continue to make this a promising avenue for development.
Date: December 1, 2008
Creator: Lyneis, Claude M.; Leitner, D.; Todd, D.S.; Sabbi, G.; Prestemon, S.; Caspi, S. et al.
System: The UNT Digital Library
7th Annual Systems Biology Symposium: Systems Biology and Engineering (open access)

7th Annual Systems Biology Symposium: Systems Biology and Engineering

Systems biology recognizes the complex multi-scale organization of biological systems, from molecules to ecosystems. The International Symposium on Systems Biology has been hosted by the Institute for Systems Biology in Seattle, Washington, since 2002. The annual two-day event gathers the most influential researchers transforming biology into an integrative discipline investingating complex systems. Engineering and application of new technology is a central element of systems biology. Genome-scale, or very small-scale, biological questions drive the enigneering of new technologies, which enable new modes of experimentation and computational analysis, leading to new biological insights and questions. Concepts and analytical methods in engineering are now finding direct applications in biology. Therefore, the 2008 Symposium, funded in partnership with the Department of Energy, featured global leaders in "Systems Biology and Engineering."
Date: April 1, 2008
Creator: Galitski, Timothy P.
System: The UNT Digital Library
ab initio Solubility Prediction of Non-Electrolytes in Ternary Solvents Using a Combination of Jouyban-Acree and Abraham Models (open access)

ab initio Solubility Prediction of Non-Electrolytes in Ternary Solvents Using a Combination of Jouyban-Acree and Abraham Models

Article on the ab initio solubility prediction of non-electrolytes in ternary solvents using a combination of Jouyban-Acree and Abraham models.
Date: May 1, 2008
Creator: Jouyban, Abolghasem; Khoubnasabjafari, Maryam; Hamidi, Ali A. & Acree, William E. (William Eugene)
System: The UNT Digital Library
Above- and below-ground biomass accumulation, production, and distribution of sweetgum and loblolly pine grown with irrigation and fertilization. (open access)

Above- and below-ground biomass accumulation, production, and distribution of sweetgum and loblolly pine grown with irrigation and fertilization.

Abstract: Increased forest productivity has been obtained by improving resource availability through water and nutrient amendments. However, more stress-tolerant species that have robust site requirements do not respond consistently to irrigation. An important factor contributing to robust site requirements may be the distribution of biomass belowground, yet available information is limited. We examined the accumulation and distribution of above- and below-ground biomass in sweetgum (Liqrridambar sfyrac$lua L.) and loblolly pine (Pinus taeda L.) stands receiving irrigation and fertilization. Mean annual aboveground production after 4 years ranged from 2.4 to 5.1 ~g.ha-'.year' for sweetgum and from 5.0 to 6.9 ~g.ha-l.year-l for pine. Sweetgum responded positively to irrigation and fertilization with an additive response to irrigation + fertilization. Pine only responded to fertilization. Sweetgum root mass fraction (RME)in creased with fertilization at 2 years and decreased with fertilization at 4 years. There were no detectable treatment differences in loblolly pine RMF. Development explained from 67% to 98% of variation in shoot versus root allometry for ephemeral and perennial tissues, fertilization explained no more than 5% of the variation in for either species, and irrigation did not explain any. We conclude that shifts in allocation from roots to shoots do not explain nutrient-induced …
Date: April 1, 2008
Creator: Coyle, David, R.; Coleman, Mark, D. & Aubrey, Doug, P.
System: The UNT Digital Library
Abstract: Air, Thermal and Water Management for PEM Fuel Cell Systems (open access)

Abstract: Air, Thermal and Water Management for PEM Fuel Cell Systems

PEM fuel cells are excellent candidates for transportation applications due to their high efficiencies. PEM fuel cell Balance of Plant (BOP) components, such as air, thermal, and water management sub-systems, can have a significant effect on the overall system performance, but have traditionally not been addressed in research and development efforts. Recognizing this, the U.S. Department of Energy and Honeywell International Inc. are funding an effort that emphasizes the integration and optimization of air, thermal and water management sub-systems. This effort is one of the major elements to assist the fuel cell system developers and original equipment manufacturers to achieve the goal of an affordable and efficient power system for transportation applications. Past work consisted of: (1) Analysis, design, and fabrication of a motor driven turbocompressor. (2) A systematic trade study to select the most promising water and thermal management systems from five different concepts (absorbent wheel humidifier, gas to gas membrane humidifier, porous metal foam humidifier, cathode recycle compressor, and water injection pump.) This presentation will discuss progress made in the research and development of air, water and thermal management sub-systems for PEM fuel cell systems in transportation applications. More specifically, the presentation will discuss: (1) Progress of the …
Date: October 1, 2008
Creator: Mirza, Mark K. Gee Zia
System: The UNT Digital Library
Accelerated Stress Testing and Diagnostic Analysis of Degradation in CdTe Solar Cells (open access)

Accelerated Stress Testing and Diagnostic Analysis of Degradation in CdTe Solar Cells

The primary goal of this study was to ascertain the presence and types of mechanisms affecting CdS/CdTe device stability in the temperature range of 60 to 120 ..deg..C. It should be noted that the results presented were specific to cells made using the specific growth conditions described.
Date: November 1, 2008
Creator: Albin, D. S.
System: The UNT Digital Library
Accelerated UV Test Methods for Encapsulants of Photovoltaic Modules: Preprint (open access)

Accelerated UV Test Methods for Encapsulants of Photovoltaic Modules: Preprint

This paper asserts that materials used for PV encapsulation must be evaluated for their ability to transmit light and to maintain mechanical integrity for extended periods of time under long term UV exposure.
Date: May 1, 2008
Creator: Kempe, M. D.
System: The UNT Digital Library
Accelerators and the Accelerator Community (open access)

Accelerators and the Accelerator Community

In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.
Date: June 1, 2008
Creator: Malamud, Ernest & Sessler, Andrew
System: The UNT Digital Library
ACCURACY OF CO2 SENSORS (open access)

ACCURACY OF CO2 SENSORS

Are the carbon dioxide (CO2) sensors in your demand controlled ventilation systems sufficiently accurate? The data from these sensors are used to automatically modulate minimum rates of outdoor air ventilation. The goal is to keep ventilation rates at or above design requirements while adjusting the ventilation rate with changes in occupancy in order to save energy. Studies of energy savings from demand controlled ventilation and of the relationship of indoor CO2 concentrations with health and work performance provide a strong rationale for use of indoor CO2 data to control minimum ventilation rates1-7. However, this strategy will only be effective if, in practice, the CO2 sensors have a reasonable accuracy. The objective of this study was; therefore, to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. This article provides a summary of study methods and findings ? additional details are available in a paper in the proceedings of the ASHRAE IAQ?2007 Conference8.
Date: October 1, 2008
Creator: Fisk, William J.; Faulkner, David & Sullivan, Douglas P.
System: The UNT Digital Library
Achieving the Benefits of Safeguards by Design (open access)

Achieving the Benefits of Safeguards by Design

The overarching driver for developing a formalized process to achieve safeguards by design is to support the global growth of nuclear power while reducing ‘nuclear security’ risks. This paper discusses an institutional approach to the design process for a nuclear facility, for designing proliferation resistance, international safeguards and U.S. national safeguards and security into new nuclear facilities. In the United States, the need exists to develop a simple, concise, formalized, and integrated approach for incorporating international safeguards and other non-proliferation considerations into the facility design process. An effective and efficient design process is one which clearly defines the functional requirements at the beginning of the project and provides for the execution of the project to achieve a reasonable balance among competing objectives in a cost effective manner. Safeguards by Design is defined as “the integration of international and national safeguards, physical security and non-proliferation features as full and equal partners in the design process of a nuclear energy system or facility,” with the objective to achieve facilities that are intrinsically more robust while being less expensive to safeguard and protect. This Safeguards by Design process has been developed such that it: • Provides improved safeguards, security, and stronger proliferation barriers, …
Date: July 1, 2008
Creator: Bjornard, Trond; Bean, Robert; Hebditch, David; Morgan, Jim; Meppen, Bruce; DeMuth, Scott et al.
System: The UNT Digital Library
Action-Oriented Benchmarking: Using the CEUS Database to Benchmark Commercial Buildings in California (open access)

Action-Oriented Benchmarking: Using the CEUS Database to Benchmark Commercial Buildings in California

The 2006 Commercial End Use Survey (CEUS) database developed by the California Energy Commission is a far richer source of energy end-use data for non-residential buildings than has previously been available and opens the possibility of creating new and more powerful energy benchmarking processes and tools. In this article--Part 2 of a two-part series--we describe the methodology and selected results from an action-oriented benchmarking approach using the new CEUS database. This approach goes beyond whole-building energy benchmarking to more advanced end-use and component-level benchmarking that enables users to identify and prioritize specific energy efficiency opportunities - an improvement on benchmarking tools typically in use today.
Date: February 1, 2008
Creator: Mathew, Paul; Mills, Evan; Bourassa, Norman & Brook, Martha
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.
System: The UNT Digital Library
Adaptive Projection Subspace Dimension for the Thick-Restart Lanczos Method (open access)

Adaptive Projection Subspace Dimension for the Thick-Restart Lanczos Method

The Thick-Restart Lanczos (TRLan) method is an effective method for solving large-scale Hermitian eigenvalue problems. However, its performance strongly depends on the dimension of the projection subspace. In this paper, we propose an objective function to quantify the effectiveness of a chosen subspace dimension, and then introduce an adaptive scheme to dynamically adjust the dimension at each restart. An open-source software package, nu-TRLan, which implements the TRLan method with this adaptive projection subspace dimension is available in the public domain. The numerical results of synthetic eigenvalue problems are presented to demonstrate that nu-TRLan achieves speedups of between 0.9 and 5.1 over the static method using a default subspace dimension. To demonstrate the effectiveness of nu-TRLan in a real application, we apply it to the electronic structure calculations of quantum dots. We show that nu-TRLan can achieve speedups of greater than 1.69 over the state-of-the-art eigensolver for this application, which is based on the Conjugate Gradient method with a powerful preconditioner.
Date: October 1, 2008
Creator: Yamazaki, Ichitaro; Bai, Zhaojun; Simon, Horst; Wang, Lin-Wang & Wu, K.
System: The UNT Digital Library
Addressing a Nuclear Information Gap (open access)

Addressing a Nuclear Information Gap

This report talks about Addressing a nuclear information gap
Date: January 1, 2008
Creator: Sailor, William C
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
System: The UNT Digital Library
Advanced Assay Systems for Radionuclide Contamination in Soils (open access)

Advanced Assay Systems for Radionuclide Contamination in Soils

Through the support of the Department of Energy (DOE) Office of Environmental Management (EM) Technical Assistance Program, the Idaho National Laboratory (INL) has developed and deployed a suite of systems that rapidly scan, characterize, and analyze surface soil contamination. The INL systems integrate detector systems with data acquisition and synthesis software and with global positioning technology to provide a real-time, user-friendly field deployable turn-key system. INL real-time systems are designed to characterize surface soil contamination using methodologies set forth in the Multi-Agency Radiation Surveys and Site Investigation Manual (MARSSIM). MARSSIM provides guidance for planning, implementing, and evaluating environmental and facility radiological surveys conducted to demonstrate compliance with a dose or risk-based regulation and provides real-time information that is immediately available to field technicians and project management personnel. This paper discusses the history of the development of these systems and describes some of the more recent examples and their applications.
Date: February 1, 2008
Creator: Giles, J. R.; Roybal, L. G.; Carpenter, M. V.; Oertel, C. P. & Roach, J. A.
System: The UNT Digital Library
Advanced Modeling of Cold Crucible Induction Melting for Process Control and Optimization (open access)

Advanced Modeling of Cold Crucible Induction Melting for Process Control and Optimization

The Idaho National Laboratory (INL) and the St. Petersburg Electrotechnical University “LETI” (ETU) have collaborated on development and validation of an advanced numerical model of the cold crucible induction melting (CCIM) process. This work was conducted in support of the Department of Energy (DOE) Office of Environmental Management Technology and Engineering (EM-20) International Program. The model predicts quasi-steady state temperature distributions, convection cell configurations, and flow field velocities for a fully established melt of low conductivity non-magnetic materials at high frequency operations. The INL/ETU ANSYS© finite element model is unique in that it has been developed specifically for processing borosilicate glass (BSG) and other glass melts. Specifically, it accounts for the temperature dependency of key material properties, some of which change by orders of magnitude within the temperature ranges experienced (temperature differences of 500oC are common) in CCIM processing of glass, including density, viscosity, thermal conductivity, specific heat, and electrical resistivity. These values, and their responses to temperature changes, are keys to understanding the melt characteristics. Because the model has been validated, it provides the capability to conduct parametric studies to understand operational sensitivities and geometry effects. Additionally, the model can be used to indirectly determine difficult to measure material …
Date: February 1, 2008
Creator: Roach, J. A.; Lopukh, D. B.; Martynov, A. P.; Polevodov, B. S. & Chepluk, S. I.
System: The UNT Digital Library