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The Analysis of Thin Wires Using Higher-Order Elements and Basis Functions (open access)

The Analysis of Thin Wires Using Higher-Order Elements and Basis Functions

Thin wire analysis was applied to curved wire segments in [1], but a special procedure was needed to evaluate the self and near-self terms. The procedure involved associating the singular behavior with a straight segment tangent to the curved source segment, permitting use of algorithms for straight wires. Recently, a procedure that avoids the singularity extraction for straight wires was presented in [2-4]. In this paper, the approach in [4] is applied to curved (or higher-order) wires using a procedure similar to that used in [1] for singularity extraction. Here, the straight tangent segment is used to determine the quadrature rules to be used on the curved segment. The result is a formulation that allows for a general mixture of higher-order basis functions [5] and higher-order wire segments.
Date: January 23, 2006
Creator: Champagne, N. J.; Wilton, D. R. & Rockway, J. W.
System: The UNT Digital Library
The National Center for Biomedical Ontology: Advancing Biomedicinethrough Structured Organization of Scientific Knowledge (open access)

The National Center for Biomedical Ontology: Advancing Biomedicinethrough Structured Organization of Scientific Knowledge

The National Center for Biomedical Ontology (http://bioontology.org) is a consortium that comprises leading informaticians, biologists, clinicians, and ontologists funded by the NIH Roadmap to develop innovative technology and methods that allow scientists to record, manage, and disseminate biomedical information and knowledge in machine-processable form. The goals of the Center are: (1) to help unify the divergent and isolated efforts in ontology development by promoting high quality open-source, standards-based tools to create, manage, and use ontologies, (2) to create new software tools so that scientists can use ontologies to annotate and analyze biomedical data, (3) to provide a national resource for the ongoing evaluation, integration, and evolution of biomedical ontologies and associated tools and theories in the context of driving biomedical projects (DBPs), and (4) to disseminate the tools and resources of the Center and to identify, evaluate, and communicate best practices of ontology development to the biomedical community. The Center is working toward these objectives by providing tools to develop ontologies and to annotate experimental data, and by developing resources to integrate and relate existing ontologies as well as by creating repositories of biomedical data that are annotated using those ontologies. The Center is providing training workshops in ontology design, …
Date: January 23, 2006
Creator: Rubin, Daniel L.; Lewis, Suzanna E.; Mungall, Chris J.; Misra,Sima; Westerfield, Monte; Ashburner, Michael et al.
System: The UNT Digital Library
Introduction to special section on Hydrologic Synthesis (open access)

Introduction to special section on Hydrologic Synthesis

The Hydrological Synthesis special section presentssynthesis topics that have the potential to revolutionize hydrologicalsciences in a manner needed to meet critical water challenges that we nowface. The special section also highlights topics that are important andexciting enough to compel researchers to engage in collaborativesynthesis activities. This introductory paper provides a brief overviewof nine papers that are included in this special section, which discussthe synthesis of tools, data, concepts, theories, or approaches acrossdisciplines and scales. The wide range of topics that are exploredinclude groundwater quality, river restoration, water management,nitrogen cycling, and Earth surface dynamics. Collectively, the specialsection papers illustrate that the challenge to deal effectively withcomplex water problems is not purely a scientific, technological, orsocioeconomic one; it is instead a complex, 21st century problem thatrequires coordinated synthesis.
Date: January 23, 2006
Creator: Hubbard, Susan
System: The UNT Digital Library
Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa (open access)

Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa

We investigated the valence and spin state of iron in an Al-bearing ferromagnesian silicate perovskite sample, (Mg{sub 0.88}Fe{sub 0.09})(Si{sub 0.94}Al{sub 0.10})O{sub 3}, at 300 K and up to 100 GPa, using diamond-anvil cells and synchrotron Moessbauer spectroscopy techniques. Under elevated pressures, our Moessbauer time spectra are sufficiently fitted by a ''three-doublet'' model, which assumes two ferrous (Fe{sup 2+}) iron types and one ferric (Fe{sup 3+}) iron type with distinct hyperfine parameters. At pressures above 20 GPa, the fraction of the ferric iron, Fe{sup 3+}/{Sigma}Fe, is about 75% and remains unchanged to the highest pressure, indicating a fixed valence state of iron within this pressure range. Between 20 and 100 GPa, the quadruple splittings of all three iron types do not change with pressure, while the isomer shift between the Fe{sup 3+} types and the Fe{sup 2+} type increases continuously with increasing pressure. In conjunction with previous x-ray emission data on the same sample, the unchanging quadruple splittings and increasing isomer shift suggest that Fe{sup 2+} undergoes a broad spin crossover towards the low-spin state at 100 GPa, while Fe{sup 3+} remains in the high-spin state. The essentially constant quadruple splittings of Fe{sup 2+} can also be taken as an indication …
Date: January 23, 2006
Creator: Li, J.; Sturhahn, W.; Jackson, J.; Struzhkin, V. V.; Lin, J. F.; Zhao, J. et al.
System: The UNT Digital Library
GIFFT: A Fast Solver for Modeling Sources in a Metamaterial Environment of Finite Size (open access)

GIFFT: A Fast Solver for Modeling Sources in a Metamaterial Environment of Finite Size

Due to the recent explosion of interest in studying the electromagnetic behavior of large (truncated) periodic structures such as phased arrays, frequency-selective surfaces, and metamaterials, there has been a renewed interest in efficiently modeling such structures. Since straightforward numerical analyses of large, finite structures (i.e., explicitly meshing and computing interactions between all mesh elements of the entire structure) involve significant memory storage and computation times, much effort is currently being expended on developing techniques that minimize the high demand on computer resources. One such technique that belongs to the class of fast solvers for large periodic structures is the GIFFT algorithm (Green's function interpolation and FFT), which is first discussed in [1]. This method is a modification of the adaptive integral method (AIM) [2], a technique based on the projection of subdomain basis functions onto a rectangular grid. Like the methods presented in [3]-[4], the GIFFT algorithm is an extension of the AIM method in that it uses basis-function projections onto a rectangular grid through Lagrange interpolating polynomials. The use of a rectangular grid results in a matrix-vector product that is convolutional in form and can thus be evaluated using FFTs. Although our method differs from [3]-[6] in various respects, …
Date: January 23, 2006
Creator: Capolino, F; Basilio, L; Fasenfest, B J & Wilton, D R
System: The UNT Digital Library
New Applications of Gamma Spectroscopy: Characterization Tools for D&D Process Development, Inventory Reduction Planning & Shipping, Safety Analysis & Facility Management During the Heavy Element Facility Risk Reduction Program (open access)

New Applications of Gamma Spectroscopy: Characterization Tools for D&D Process Development, Inventory Reduction Planning & Shipping, Safety Analysis & Facility Management During the Heavy Element Facility Risk Reduction Program

Novel applications of gamma ray spectroscopy for D&D process development, inventory reduction, safety analysis and facility management are discussed in this paper. These applications of gamma spectroscopy were developed and implemented during the Risk Reduction Program (RPP) to successfully downgrade the Heavy Element Facility (B251) at Lawrence Livermore National Laboratory (LLNL) from a Category II Nuclear Facility to a Radiological Facility. Non-destructive assay in general, gamma spectroscopy in particular, were found to be important tools in project management, work planning, and work control (''Expect the unexpected and confirm the expected''), minimizing worker dose, and resulted in significant safety improvements and operational efficiencies. Inventory reduction activities utilized gamma spectroscopy to identify and confirm isotopics of legacy inventory, ingrowth of daughter products and the presence of process impurities; quantify inventory; prioritize work activities for project management; and to supply information to satisfy shipper/receiver documentation requirements. D&D activities utilize in-situ gamma spectroscopy to identify and confirm isotopics of legacy contamination; quantify contamination levels and monitor the progress of decontamination efforts; and determine the point of diminishing returns in decontaminating enclosures and glove boxes containing high specific activity isotopes such as {sup 244}Cm and {sup 238}Pu. In-situ gamma spectroscopy provided quantitative comparisons of several …
Date: January 23, 2006
Creator: Mitchell, M.; Anderson, B.; Gray, L.; Vellinger, R.; West, M.; Gaylord, R. et al.
System: The UNT Digital Library
PROGRESS & CHALLENGES IN CLEANUP OF HANFORDS TANK WASTES (open access)

PROGRESS & CHALLENGES IN CLEANUP OF HANFORDS TANK WASTES

The River Protection Project (RPP), which is managed by the Department of Energy (DOE) Office of River Protection (ORP), is highly complex from technical, regulatory, legal, political, and logistical perspectives and is the largest ongoing environmental cleanup project in the world. Over the past three years, ORP has made significant advances in its planning and execution of the cleanup of the Hartford tank wastes. The 149 single-shell tanks (SSTs), 28 double-shell tanks (DSTs), and 60 miscellaneous underground storage tanks (MUSTs) at Hanford contain approximately 200,000 m{sup 3} (53 million gallons) of mixed radioactive wastes, some of which dates back to the first days of the Manhattan Project. The plan for treating and disposing of the waste stored in large underground tanks is to: (1) retrieve the waste, (2) treat the waste to separate it into high-level (sludge) and low-activity (supernatant) fractions, (3) remove key radionuclides (e.g., Cs-137, Sr-90, actinides) from the low-activity fraction to the maximum extent technically and economically practical, (4) immobilize both the high-level and low-activity waste fractions by vitrification, (5) interim store the high-level waste fraction for ultimate disposal off-site at the federal HLW repository, (6) dispose the low-activity fraction on-site in the Integrated Disposal Facility (IDF), …
Date: January 23, 2006
Creator: HEWITT, W.M. & SCHEPENS, R.
System: The UNT Digital Library