Algebraic sub-structuring for electromagnetic applications (open access)

Algebraic sub-structuring for electromagnetic applications

Algebraic sub-structuring refers to the process of applying matrix reordering and partitioning algorithms to divide a large sparse matrix into smaller submatrices from which a subset of spectral components are extracted and combined to form approximate solutions to the original problem. In this paper, we show that algebraic sub-structuring can be effectively used to solve generalized eigenvalue problems arising from the finite element analysis of an accelerator structure.
Date: September 14, 2004
Creator: Yang, Chao; Gao, Weiguo; Bai, Zhaojun; Li, Xiaoye; Lee, Lie-Quan; Husbands, Parry et al.
Object Type: Article
System: The UNT Digital Library
Advanced Technologies for Stripper Gas Well Enhancement (open access)

Advanced Technologies for Stripper Gas Well Enhancement

This report addresses a quarterly report about the advanced technologies of stripper gas well enhancement from July 1 to September 30, 2003
Date: July 14, 2004
Creator: MacDonald, Ronald J.
Object Type: Report
System: The UNT Digital Library
Solid-Matrix Luminescence Analysis and Coupling Solid-Matrix Luminescence with Separation Methodology (open access)

Solid-Matrix Luminescence Analysis and Coupling Solid-Matrix Luminescence with Separation Methodology

In this report, the major results and conclusions of the research over the last two years and five months is considered. The report discusses the mechanistic aspects of oxygen quenching of solid-matrix phosphorescence (SMP), mechanistic aspects of moisture quenching of SMP, interactions and methodology to investigate phosphors in glucose glasses, new methods for coating filter paper for solid-phase microextraction with solid-matrix fluorescence (SMF) and SMP detection, mechanistic consideration of the heavy-atom quenching of the SMF and the enhancement of SMP of benzo[a]pyrene-DNA adducts, and new developments in liquid-liquid-liquid microextraction.
Date: June 14, 2004
Creator: Hurtubise, Robert J.
Object Type: Report
System: The UNT Digital Library
In service design by simulations (open access)

In service design by simulations

Irradiation of materials by energetic particles (e.g. electrons, ions and neutrons) is associated with very high internal power dissipation, which can drive the underlying nano- and microstructure far from normal equilibrium conditions. One of the most unusual responses in this connection is the ability of the material's nano- and microstructure to self-assemble in well-organized, two- and three-dimensional periodic arrangements. We reviewed and assessed experimental evidence and theoretical models pertaining to the physical understanding of nano- and microstructure self-organization under irradiation conditions. Experimental observations on the formation of self-organized defect clusters, dislocation loops, voids and bubbles were presented and critically assessed. Implantation of metals with energetic helium results in remarkable self-assembled bubble super-lattices with wavelengths (super-lattice parameters) in the range of 5-8 nm. Ion and neutron irradiation produce a wide variety of self-assembled 3-D defect walls and void lattices, with wavelengths that can be tailored in the range of 10's to 100's of nanometers. Theoretical models aimed at explaining these observations were introduced, and a consistent description of many features is outlined. The primary focus of the most recent modeling efforts, which are based on stability theory and concepts of non-linear dynamics, was to determine criteria for the evolution and spatial …
Date: March 14, 2004
Creator: Ghoniem, Nasr H.
Object Type: Report
System: The UNT Digital Library
Reflection-Based Python-C++ Bindings (open access)

Reflection-Based Python-C++ Bindings

Python is a flexible, powerful, high-level language with excellent interactive and introspective capabilities and a very clean syntax. As such, it can be a very effective tool for driving physics analysis. Python is designed to be extensible in low-level C-like languages, and its use as a scientific steering language has become quite widespread. To this end, existing and custom-written C or C++ libraries are bound to the Python environment as so-called extension modules. A number of tools for easing the process of creating such bindings exist, such as SWIG and Boost. Python. Yet, the process still requires a considerable amount of effort and expertise. The C++ language has few built-in introspective capabilities, but tools such as LCGDict and CINT add this by providing so-called dictionaries: libraries that contain information about the names, entry points, argument types, etc. of other libraries. The reflection information from these dictionaries can be used for the creation of bindings and so the process can be fully automated, as dictionaries are already provided for many end-user libraries for other purposes, such as object persistency. PyLCGDict is a Python extension module that uses LCG dictionaries, as PyROOT uses CINT reflection information, to allow /cwPython users to access …
Date: October 14, 2004
Creator: Generowicz, Jacek; Lavrijsen, Wim T.L.P.; Marino, Massimo & Mato, Pere
Object Type: Article
System: The UNT Digital Library
Why we ventilate our houses - An historical look (open access)

Why we ventilate our houses - An historical look

The knowledge of how to ventilate buildings, and how much ventilation is necessary for human health and comfort, has evolved over centuries of trial and error. Humans and animals have developed successful solutions to the problems of regulating temperature and removing air pollutants through the use of ventilation. These solutions include ingenious construction methods, such as engineered passive ventilation (termite mounds and passive stacks), mechanical means (wing-powered, fans), and an evolving effort to identify problems and develop solutions. Ventilation can do more than help prevent building occupants from getting sick; it can provide an improved indoor environment. Codes and standards provide minimum legal requirements for ventilation, but the need for ventilation goes beyond code minima. In this paper we will look at indoor air pollutant sources over time, the evolution of ventilation strategies, current residential ventilation codes and standards (e.g., recently approved ASHRAE Standard 62.2), and briefly discuss ways in which we can go beyond the standards to optimize residential ventilation, reduce indoor air quality problems, and provide corresponding social and economic benefit.
Date: May 14, 2004
Creator: Matson, Nance E. & Sherman, Max H.
Object Type: Article
System: The UNT Digital Library
GAP Final Technical Report 12-14-04 (open access)

GAP Final Technical Report 12-14-04

The Genomics Annotation Platform (GAP) was designed to develop new tools for high throughput functional annotation and characterization of protein sequences and structures resulting from genomics and structural proteomics, benchmarking and application of those tools. Furthermore, this platform integrated the genomic scale sequence and structural analysis and prediction tools with the advanced structure prediction and bioinformatics environment of ICM. The development of GAP was primarily oriented towards the annotation of new biomolecular structures using both structural and sequence data. Even though the amount of protein X-ray crystal data is growing exponentially, the volume of sequence data is growing even more rapidly. This trend was exploited by leveraging the wealth of sequence data to provide functional annotation for protein structures. The additional information provided by GAP is expected to assist the majority of the commercial users of ICM, who are involved in drug discovery, in identifying promising drug targets as well in devising strategies for the rational design of therapeutics directed at the protein of interest. The GAP also provided valuable tools for biochemistry education, and structural genomics centers. In addition, GAP incorporates many novel prediction and analysis methods not available in other molecular modeling packages. This development led to signing …
Date: December 14, 2004
Creator: Andrew J. Bordner, PhD, Senior Research Scientist
Object Type: Report
System: The UNT Digital Library
Neptunium Solubility in the Near-Field Environment of A Proposed Yucca Mountain Repository (open access)

Neptunium Solubility in the Near-Field Environment of A Proposed Yucca Mountain Repository

For representing the source-term of a proposed repository at Yucca Mountain, NV, total system performance assessment models evaluate the disequilibrium degradation of the waste forms to capture a bounding rate for radionuclide source-term availability and use solubility constraints that are more representative of longer-term, equilibrium processes to limit radionuclide mass transport from the source-term. These solubility limits capture precipitation processes occurring either as the waste forms alter, or in the near-field environment as chemical conditions evolve. A number of alternative models for solubility controls on dissolved neptunium concentrations have been evaluated. These include idealized models based on precipitation of neptunium as separate oxide minerals and more complex considerations of trace amounts of neptunium being incorporated into the secondary uranyl phases from waste form alteration. Thermodynamic models for neptunium under oxidizing conditions indicate that tetravalent neptunium (NpO{sub 2}) solids are more stable relative to pentavalent (Np{sub 2}O{sub 5}) phases, and thereby set lower dissolved concentrations of neptunyl species. Data on solids and solutions from slow flow through (dripping) tests on spent fuel grains indicate that neptunium is tetravalent in the spent fuel and that over {approx}9 years the neptunium concentrations are near to or below calculated NpO{sub 2} solubility. The possibility …
Date: May 14, 2004
Creator: Sassani, D.C.
Object Type: Report
System: The UNT Digital Library
Detailed Measurements of Turbulent Rayleigh-Taylor Mixing at Large and Small Atwood Numbers (open access)

Detailed Measurements of Turbulent Rayleigh-Taylor Mixing at Large and Small Atwood Numbers

This project has two major tasks: Task 1. The construction of a new air/helium facility to collect detailed measurements of Rayleigh-Taylor (RT) mixing at high Atwood number, and the distribution of these data to LLNL, LANL, and Alliance members for code validation and design purposes. Task 2. The collection of initial condition data from the new Air/Helium facility, for use with validation of RT simulation codes at LLNL and LANL. Also, studies of multi-layer mixing with the existing water channel facility. Over the last twelve (12) months there has been excellent progress, detailed in this report, with both tasks. As of December 10, 2004, the air/helium facility is now complete and extensive testing and validation of diagnostics has been performed. Currently experiments with air/helium up to Atwood numbers of 0.25 (the maximum is 0.75, but the highest Reynolds numbers are at 0.25) are being performed. The progress matches the project plan, as does the budget, and we expect this to continue for 2005. With interest expressed from LLNL we have continued with initial condition studies using the water channel. This work has also progressed well, with one of the graduate Research Assistants (Mr. Nick Mueschke) visiting LLNL the past two …
Date: December 14, 2004
Creator: Malcolm J. Andrews, Ph.D.
Object Type: Report
System: The UNT Digital Library
Comment on ''Thermal Behavior of Polarized Pd/D Electrodes Prepared by Co-Deposition'' (open access)

Comment on ''Thermal Behavior of Polarized Pd/D Electrodes Prepared by Co-Deposition''

This paper presents the basics of this model, including what physical conditions could produce a calibration constant shift and what might cause those conditions to arise. The new evidences are discussed and it is shown that the possibility of at-the-electrode recombination cannot be eliminated, in fact prior photographic evidence is shown to be reasonable evidence of this phenomenon. Thus in the absence of definitive data, the conclusion that apparent excess heat arises from a nuclear cause is premature. If the apparent excess heat signal is not representative of a true heat source, but is instead an equipment/method malfunction, integrating the signal is of no value. This paper proposes that is the situation, and will therefore focus on examining the phenomenon of apparent excess enthalpy (sometimes called excess heat). Not addressed will be the myriad of other purported evidences of nuclear reactions. The apparent excess heat claims form the largest block of claims for a nuclear FPHE cause, and the correlation of apparent excess heat with apparent nuclear ash detection is often cited as evidence of the nuclear nature of the FPHE. But confidence in the validity of the apparent excess heat signal is of critical importance in validating a nuclear …
Date: July 14, 2004
Creator: SHANAHAN, KIRKL.
Object Type: Article
System: The UNT Digital Library
Reducing the Detection Limit for Tetraphenylborate in Tank 50H Waste (open access)

Reducing the Detection Limit for Tetraphenylborate in Tank 50H Waste

SRTC personnel are developing a technique that can determine the concentration of tetraphenylborate (TPB) at 300 grams in 100,000 gallons of salt solution (0.8 mg/L) in the presence of0.378 Ci/gal of Cs-137. The current High Performance Liquid Chromatography (HPLC) method of analysis can determine the TPB concentration at 5 mg/L and higher. The limit of quantitation was lowered by modification of the sample preparation steps. The HPLC sample preparation method currently used requires neutralization of the tank waste sample followed by extraction with acetonitrile. This method dilutes the tank waste sample 6.5 to 1 increasing the limit of quantitation. The method described in this report concentrates the sample two-fold lowering the limit of quantitation from 5 mg/L to 0.25mg/L. Researchers used solvent extraction of undiluted tank waste to isolate, and concentrate (two-fold) samples of tank supernate and Plant Inhibited Water (PIW) that simulated tank supernate at the cesium level of approximately 0.3 Ci/gal. The 137Cs content in the tank supernate measured 0.65 Ci/gal prior to a two-fold dilution with PIW. The concentration of the TPB was determined by HPLC on a reversed-phase HPLC column using methanol, acetonitrile, and buffered water as the mobile phase. Important Findings: The 0.8 mg/L quantitation …
Date: July 14, 2004
Creator: White, Thomas L.
Object Type: Report
System: The UNT Digital Library
Mechanical Property Data for Fiberboard (open access)

Mechanical Property Data for Fiberboard

The 9975 shipping package incorporates a cane fiberboard overpack for thermal insulation and impact resistance. Mechanical properties (tensile and compressive behavior) have been measured on cane fiberboard and a similar wood-based product following short-term conditioning in several temperature/humidity environments. Both products show similar trends, and vary in behavior with material orientation, temperature and humidity. A memory effect is also seen in that original strength values are only partially recovered following exposure to a degrading environment and return to ambient conditions.
Date: December 14, 2004
Creator: WILLIAM, daugherty
Object Type: Article
System: The UNT Digital Library
Record of Technical Change for CAU 5 Landfills, Nevada Test Site, Nevada (open access)

Record of Technical Change for CAU 5 Landfills, Nevada Test Site, Nevada

Record of Technical Change for Corrective Action Plan for Corrective Action Unit 5: Landfills, Nevada Test Site, Nevada (DOE/NV--986, July 2004).
Date: December 14, 2004
Creator: U.S. Department of Energy, National Nuclear Security Administration, Nevada Site Office
Object Type: Report
System: The UNT Digital Library
Diffusive separation of noble gases and noble gas abundance patterns in sedimentary rocks (open access)

Diffusive separation of noble gases and noble gas abundance patterns in sedimentary rocks

The mechanisms responsible for noble gas concentrations, abundance patterns, and strong retentivity in sedimentary lithologies remain poorly explained. Diffusion-controlled fractionation of noble gases is modeled and examined as an explanation for the absolute and relative abundances of noble gases observed in sediments. Since the physical properties of the noble gases are strong functions of atomic mass, the individual diffusion coefficients, adsorption coefficients and atomic radii combine to impede heavy noble gas (Xe) diffusion relative to light noble gas (Ne) diffusion. Filling of lithic grains/half-spaces by diffusive processes thus produces Ne enrichments in the early and middle stages of the filling process with F(Ne) values similar to that observed in volcanic glasses. Emptying lithic grains/half-spaces produces a Xe-enriched residual in the late (but not final) stages of the process producing F(Xe) values similar to that observed in shales. 'Exotic but unexceptional' shales that exhibit both F(Ne) and F(Xe) enrichments can be produced by incomplete emptying followed by incomplete filling. This mechanism is consistent with literature reported noble gas abundance patterns but may still require a separate mechanism for strong retention. A system of labyrinths-with-constrictions and/or C-, Si-nanotubes when combined with simple adsorption can result in stronger diffusive separation and non-steady-state enrichments …
Date: June 14, 2004
Creator: Torgersen, T.; Kennedy, B.M. & van Soest, M.C.
Object Type: Article
System: The UNT Digital Library
Modeling Three-Dimensional Groundwater Flow and Advective Contaminant Transport at a Heterogeneous Mountainous Site in Support of Remediation Strategy (open access)

Modeling Three-Dimensional Groundwater Flow and Advective Contaminant Transport at a Heterogeneous Mountainous Site in Support of Remediation Strategy

A calibrated groundwater flow model for a contaminated site can provide substantial information for assessing and improving hydraulic measures implemented for remediation. A three-dimensional transient groundwater flow model was developed for a contaminated mountainous site, at which interim corrective measures were initiated to limit further spreading of contaminants. This flow model accounts for complex geologic units that vary considerably in thickness, slope, and hydrogeologic properties, as well as large seasonal fluctuations of the groundwater table and flow rates. Other significant factors are local recharge from leaking underground storm drains and recharge from steep uphill areas. The zonation method was employed to account for the clustering of high and low hydraulic conductivities measured in a geologic unit. A composite model was used to represent the bulk effect of thin layers of relatively high hydraulic conductivity found within bedrock of otherwise low conductivity. The inverse simulator ITOUGH2 was used to calibrate the model for the distribution of rock properties. The model was initially calibrated using data collected between 1994 and 1996. To check the validity of the model, it was subsequently applied to predicting groundwater level fluctuation and groundwater flux between 1996 and 1998. Comparison of simulated and measured data demonstrated that …
Date: January 14, 2004
Creator: Zhou, Quanlin; Birkholzer, Jens T.; Javandel, Iraj & Jordan, Preston D.
Object Type: Article
System: The UNT Digital Library
Development of an Inspection Platform and a Suite of Sensors for Assessing Corrosion and Mechanical Damage on Unpiggable Transmission Mains Quarterly Report (open access)

Development of an Inspection Platform and a Suite of Sensors for Assessing Corrosion and Mechanical Damage on Unpiggable Transmission Mains Quarterly Report

This development program is a joint effort among the Northeast Gas Association (formerly New York Gas Group), Foster-Miller, Inc., and the US Department of Energy (DOE) through the National Energy Technology Laboratory (NETL). The total cost of the project is $772,525, with the National Energy Technology Laboratory of the US Department of Energy contributing $572,525, and the Northeast Gas Association contributing $200,000. The present report summarizes the accomplishments of the project during its fourth three-month period (from July 2003 through September 2003). The efforts of the project focused during this period in completing the assessment of the tether technology, which is intended to be used as the means of communication between robot and operator, in designing the MFL sensor module, in completing the kinematic studies, and in initiating tractor design. In addition, work on the ovality sensor progressed significantly, while work on system integration was initiated focusing at this point in time on module coupling. Results to date indicate that the robotic system under design will be able to meet most of the design specifications initially specified. Earlier concerns regarding the portability of the system are shown to be a non-issue, with new more detailed analysis showing that from a …
Date: January 14, 2004
Creator: Vradis, George C. & Leary, Bill
Object Type: Report
System: The UNT Digital Library
Continuum Mechanical and Computational Aspects of Material Behavior (open access)

Continuum Mechanical and Computational Aspects of Material Behavior

The authors develop a theory for uniaxial nematic elastomers with variable asphericity. As an application of the theory, they consider the time-independent, isochoric radial expansion of a right circular cylinder. Numerical solutions to the resulting differential equation are obtained for a range of radial expansions. For all expansions considered, there exists an isotropic core of material surrounding the cylinder axis where the asphericity vanishes and in which the polymeric chains are shaped as spherical coils. This region, corresponding to a disclination of strength + 1 along the axis, is bounded by a narrow transition layer across which the asphericity increases rapidly and attains a non-trivial positive value. The material thereby becomes anisotropic away from the disclination so that the polymeric chains are shaped as ellipsoidal coils of revolution prolate about cylinder radius. In accordance with the area of steeply changing asphericity between isotropic and anisotropic regimes, a marked drop in the free-energy density is observed. The boundary of the disclination core is associated with the location of this energy drop. For realistic choices of material parameters, this criterion yields a core on the order of 10{sup -2} {micro}m, which coincides with observations in conventional liquid-crystal melts. Also occurring at the …
Date: March 14, 2004
Creator: Fried, Eliot & Gurtin, Morton E.
Object Type: Report
System: The UNT Digital Library
Agricultural and Environmental Input Parameters for the Biosphere Model (open access)

Agricultural and Environmental Input Parameters for the Biosphere Model

This analysis is one of 10 technical reports that support the Environmental Radiation Model for Yucca Mountain Nevada (ERMYN) (i.e., the biosphere model). It documents development of agricultural and environmental input parameters for the biosphere model, and supports the use of the model to develop biosphere dose conversion factors (BDCFs). The biosphere model is one of a series of process models supporting the total system performance assessment (TSPA) for the repository at Yucca Mountain. The ERMYN provides the TSPA with the capability to perform dose assessments. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows the interrelationships between the major activities and their products (the analysis and model reports) that were planned in ''Technical Work Plan for Biosphere Modeling and Expert Support'' (BSC 2004 [DIRS 169573]). The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes the ERMYN and its input parameters.
Date: September 14, 2004
Creator: Rasmuson, K. & Rautenstrauch, K.
Object Type: Report
System: The UNT Digital Library
Mechanical Assessment of the Waste Package Subject to Vibratory Motion (open access)

Mechanical Assessment of the Waste Package Subject to Vibratory Motion

The purpose of this document is to provide an integrated overview of the calculation reports that define the response of the waste package and its internals to vibratory ground motion. The calculation reports for waste package response to vibratory ground motion are identified in Table 1-1. Three key calculation reports describe the potential for mechanical damage to the waste package, fuel assemblies, and cladding from a seismic event. Three supporting documents have also been published to investigate sensitivity of damage to various assumptions for the calculations. While these individual reports present information on a specific aspect of waste package and cladding response, they do not describe the interrelationship between the various calculations and the relationship of this information to the seismic scenario class for Total System Performance Assessment-License Application (TSPA-LA). This report is designed to fill this gap by providing an overview of the waste package structural response calculations.
Date: October 14, 2004
Creator: Gross, M.
Object Type: Report
System: The UNT Digital Library
Fuel cycle methods : first-order spherical harmonics formulations capable of treating low density regions. (open access)

Fuel cycle methods : first-order spherical harmonics formulations capable of treating low density regions.

In this report we present an approach to deal with a problem encountered in different type of systems and specific configurations: the treatment of low density regions. This is the case of gas cooled reactors, voided configurations (evaluations of associated reactivity coefficients), beam region of external source driven systems, etc. The approach is to form the nodal response matrix using the first-order form of the transport equation, for then the cross section no longer appears in the denominator, as in the case of the standard formulation of the VARIANT code. Two different formulations are presented: the differential and integral ones. After applications to different difficult benchmark problems, it was concluded that the new formulations can treat low density regions.
Date: January 14, 2004
Creator: Smith, M. A.; Palmiotti, G. & Lewis, E. E.
Object Type: Report
System: The UNT Digital Library
FY03 DNAPL Characterization of the A-14 Outfall (open access)

FY03 DNAPL Characterization of the A-14 Outfall

Residual dense non-aqueous phase liquid (DNAPL) contamination continues to be one of the most challenging remediation and characterization problems at SRS and sites around the world. Chlorinated solvents were usually released as DNAPLs to/the subsurface where they move in an unstable fashion driven by gravitational and,capillary forces. They are often retained in small discrete blobs in fine grain materials in the vadose zone and contaminate ground water by slow continuous release through dissolution and diffusion. Locating these small sources is a difficult but crucial part of remediating a contaminated site. Several methods have been developed to locate subsurface DNAPL but nearly all are intrusive and can only identify DNAPL in close proximity to the access hole. Minimally invasive geophysical methods to locate residual DNAPL have been proposed and developed but few methods are capable of the spatial resolution required. Complex resistivity measurements sensitive to DNAPL (perchloroethylene) interactions with clay (smectite) have recently been shown to have promise in laboratory experiments. Based on these laboratory results, field tests of the complex resistivity technique were performed at the A-014 outfall.
Date: January 14, 2004
Creator: Riha, BD
Object Type: Report
System: The UNT Digital Library
User's guide, version 1 RESRAD-BIOTA : a tool for implementing a graded approach to biota dose evaluation. (open access)

User's guide, version 1 RESRAD-BIOTA : a tool for implementing a graded approach to biota dose evaluation.

This Interagency Steering Committee on Radiation Standards (ISCORS) Technical Report provides a User's Guide for the RESRAD-BIOTA code. The RESRAD-BIOTA code is a tool for implementing a graded approach to biota dose evaluation. The RESRAD-BIOTA code was principally sponsored and developed by the U.S. Department of Energy (DOE), with support from the U.S. Environmental Protection Agency (EPA) and the U.S. Nuclear Regulatory Commission (NRC), through the informal interagency Ecological Radiological Work Group (ECORAD-WG). The work group was led by DOE and coordinated under the oversight of ISCORS. The RESRAD-BIOTA code provides a complete spectrum of biota dose evaluation capabilities, from methods for general screening, to comprehensive receptor-specific dose estimation. The code was designed to be consistent with and provide a tool for implementing the DOE ''Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota'' (DOE voluntary consensus Technical Standard DOE-STD-1153-2002), and to provide advanced analysis capabilities in a manner that will support the anticipated needs of DOE and other agencies. These advanced analysis capabilities were generally developed through a consensus-based process among the participating agency representatives of the ECORAD-WG.
Date: January 14, 2004
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Investigation of the Rayleigh-Taylor and Richtmyer-Meshkov instabilities (open access)

Investigation of the Rayleigh-Taylor and Richtmyer-Meshkov instabilities

Some of the major difficulties encountered in the effort to achieve nuclear fusion by means of inertial confinement arise from the unstable behavior of the interface between the shell material and the nuclear fuel which develops upon implosion of the shell by direct or indirect laser drive. The fluid flows that develop (termed the Rayleigh-Taylor (RT) and the Richtmyer-Meshkov (RM) instabilities) cause the gassified shell material to mix with the nuclear fuel, causing a reduction in energy yield or no ignition altogether. The present research program addresses the Rayleigh-Taylor and the Richtmyer-Meshkov instabilities with extensive laboratory and computational experiments. In the past year, three new activities have been initiated: a new shock tube experiment, involving the impulsive acceleration of a test gas-filled soap bubble, diagnosed with planar Mie scattering or planar induced fluorescence; a Rayleigh-Taylor experiment based on the use of a magnetorheological (MR) fluid to fix the initial shape of the interface between the MR fluid and water; and a series of computer calculations using the Raptor code (made available by Lawrence Livermore National Laboratory) to design and simulate the shock tube experiments.
Date: January 14, 2004
Creator: Bonazza, Riccardo; Anderson, Mark & Smith, Leslie
Object Type: Report
System: The UNT Digital Library
Engineering Spectral Control Using Front Surface Filters for Maximum TPV Energy Conversion System Performance (open access)

Engineering Spectral Control Using Front Surface Filters for Maximum TPV Energy Conversion System Performance

Energy conversion efficiencies of better than 23% have been demonstrated for small scale tests of a few thermophotovoltaic (TPV) cells using front surface, tandem filters [1, 2]. The engineering challenge is to build this level of efficiency into arrays of cells that provide useful levels of energy. Variations in cell and filter performance will degrade TPV array performance. Repeated fabrication runs of several filters each provide an initial quantification of the fabrication variation for front surface, tandem filters for TPV spectral control. For three performance statistics, within-run variation was measured to be 0.7-1.4 percent, and run-to-run variation was measured to be 0.5-3.2 percent. Fabrication runs using a mask have been shown to reduce variation across interference filters from as high as 8-10 percent to less than 1.5 percent. Finally, several system design and assembly approaches are described to further reduce variation.
Date: October 14, 2004
Creator: Rahmlow, T. D., Jr.; Lazo-Wasem, J.; Gratrix, E.; Azarkevich, J.; Brown, E.; DePoy, D. et al.
Object Type: Article
System: The UNT Digital Library