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A Parallel Multigrid Method for the Finite Element Analysis of Mechanical Contact (open access)

A Parallel Multigrid Method for the Finite Element Analysis of Mechanical Contact

A geometrical multigrid method for solving the linearized matrix equations arising from node-on-face three-dimensional finite element contact is described. The development of an efficient implementation of this combination that minimizes both the memory requirements and the computational cost requires careful construction and storage of the portion of the coarse mesh stiffness matrices that are associated with the contact stiffness on the fine mesh. The multigrid contact algorithm is parallelized in a manner suitable for distributed memory architectures: results are presented that demonstrates the scheme's scalability. The solution of a large contact problem derived from an analysis of the factory joints present in the Space Shuttle reusable solid rocket motor demonstrates the usefulness of the general approach.
Date: March 21, 2002
Creator: Hales, J. D. & Parsons, I. D.
System: The UNT Digital Library
Delineation of Fast Flow Paths in Porous Media Using Noble Gas Tracers (open access)

Delineation of Fast Flow Paths in Porous Media Using Noble Gas Tracers

Isotopically enriched xenon isotopes are ideal for tracking the flow of relatively large volumes of groundwater. Dissolved noble gas tracers behave conservatively in the saturated zone, pose no health risk to drinking water supplies, and can be used with a large dynamic range. Different Xe isotopes can be used simultaneously at multiple recharge sources in a single experiment. Results from a tracer experiment at a California water district suggests that a small fraction of tracer moved from the recharge ponds through the thick, unconfined, coarse-grained alluvial aquifer to high capacity production wells at a horizontal velocity of 6 m/day. In contrast, mean water residence times indicate that the average rate of transport is 0.5 to 1 m/day.
Date: March 21, 2002
Creator: Hudson, G. B. & Moran, J. E.
System: The UNT Digital Library
Patterns and Controls of Temporal Variation in CO2 Sequestration and Loss in Arctic Ecosystems (open access)

Patterns and Controls of Temporal Variation in CO2 Sequestration and Loss in Arctic Ecosystems

Determine seasonal and interannual patterns of net ecosystem CO2 flux from wet coastal and moist tussock tundra.
Date: March 21, 2002
Creator: Oechel, Walter C.
System: The UNT Digital Library
Prohibiting Television Advertising of Alcoholic Beverages: A Constitutional Analysis (open access)

Prohibiting Television Advertising of Alcoholic Beverages: A Constitutional Analysis

None
Date: March 21, 2002
Creator: unknown
System: The UNT Digital Library
F-22 Raptor Aircraft Program (open access)

F-22 Raptor Aircraft Program

None
Date: March 21, 2002
Creator: Bolkcom, Christopher
System: The UNT Digital Library
Remote Operation of the Fermilab/NICADD Photoinjector (open access)

Remote Operation of the Fermilab/NICADD Photoinjector

The recognition that a new major HEP facility must receive international support and that its execution would benefit from worldwide interaction from design through operation has given rise to the term Global Accelerator Network (GAN). A welcome consequence has been a more permissive attitude toward remote operation of existing facilities.For roughly thirty years, the computer has been the principal operator interface to the beam,and, through the development of the Internet, the operator can be literally anywhere. In this note, the authors describe their approach to enabling a sufficient degree of operation of the photoinjector from afar in order to carry out investigations in beam physics. The goal was to do so on a time scale of a few months and at minimal cost. At this writing, remote shifts are routinely scheduled involving DESY and LBL, limited in frequency only by the requests of the collaborators and by the need for time to interpret the data.
Date: March 21, 2002
Creator: al., Nikolai Barov et
System: The UNT Digital Library
Status of the low-energy Linac 200-MHz rf stations (open access)

Status of the low-energy Linac 200-MHz rf stations

This report describes the present status of the five low-energy Linac 200-MHz RF stations with regard to availability and reliability of major components. An attempt has been made to describe possible solutions (or non-solutions) and to indicate some of the complexity and interplay between those solutions. For the problem at hand, the discontinuance of this one particular tube, an acceptable solution plan must be identified and designed in detail in the near future. As explained herein, the time scale for implementing a solution is five years; beyond that time there is considerable risk of finding ourselves with a non-maintainable Linac and no High Energy Physics program at Fermilab.
Date: March 21, 2002
Creator: al., Charles W. Schmidt et
System: The UNT Digital Library
Superfund and Brownfields in the 107th Congress (open access)

Superfund and Brownfields in the 107th Congress

None
Date: March 21, 2002
Creator: Reisch, Mark
System: The UNT Digital Library
South Korea-U.S. Economic Relations: Cooperation, Friction, and Future Prospects (open access)

South Korea-U.S. Economic Relations: Cooperation, Friction, and Future Prospects

None
Date: March 21, 2002
Creator: Manyin, Mark E.
System: The UNT Digital Library
Energy Efficiency: Budget, Oil Conservation, and Electricity Conservation Issues (open access)

Energy Efficiency: Budget, Oil Conservation, and Electricity Conservation Issues

In the 108th Congress, debate over energy efficiency programs has focused on budget, oil, natural gas, and electricity issues, and provisions in the omnibus energy policy bill, S. 2095, H.R. 6, and S. 14/S. 1149. The Bush Administration’s FY2005 budget request for the Department of Energy’s (DOE’s) Energy Efficiency Program sought $875.9 million, including $543.9 for R&D and $332.0 million for grants. In the first session, the omnibus energy bill (H.R. 6) had several significant tax and regulatory measures for energy efficiency. It did not pass the Senate due to concerns about cost and an MTBE “safe harbor” provision.
Date: March 21, 2002
Creator: Sissine, Fred
System: The UNT Digital Library
Campaign Financing (open access)

Campaign Financing

This is one report in the series of reports that discuss the campaign finance practices and related issues. Concerns over financing federal elections have become a seemingly perennial aspect of our political system, centered on the enduring issues of high campaign costs and reliance on interest groups for needed campaign funds. The report talks about the today’s paramount issues such as perceived loopholes in current law and the longstanding issues: overall costs, funding sources, and competition.
Date: March 21, 2002
Creator: Cantor, Joseph E.
System: The UNT Digital Library
The Middle East Peace Talks (open access)

The Middle East Peace Talks

None
Date: March 21, 2002
Creator: Migdalovitz, Carol
System: The UNT Digital Library