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Algebraic coarsening methods for linear and nonlinear PDE and systems

Description: In [l] Brandt describes a general approach for algebraic coarsening. Given fine-grid equations and a prescribed relaxation method, an approach is presented for defining both the coarse-grid variables and the coarse-grid equations corresponding to these variables. Although, these two tasks are not necessarily related (and, indeed, are often performed independently and with distinct techniques) in the approaches of [1] both revolve around the same underlying observation. To determine whether a given set of coarse-grid variables is appropriate it is suggested that one should employ compatible relaxation. This is a generalization of so-called F-relaxation (e.g., [2]). Suppose that the coarse-grid variables are defined as a subset of the fine-grid variables. Then, F-relaxation simply means relaxing only the F-variables (i.e., fine-grid variables that do not correspond to coarse-grid variables), while leaving the remaining fine-grid variables (C-variables) unchanged. The generalization of compatible relaxation is in allowing the coarse-grid variables to be defined differently, say as linear combinations of fine-grid variables, or even nondeterministically (see examples in [1]). For the present summary it suffices to consider the simple case. The central observation regarding the set of coarse-grid variables is the following [1]: Observation 1--A general measure for the quality of the set of coarse-grid variables is the convergence rate of compatible relaxation. The conclusion is that a necessary condition for efficient multigrid solution (e.g., with convergence rates independent of problem size) is that the compatible-relaxation convergence be bounded away from 1, independently of the number of variables. This is often a sufficient condition, provided that the coarse-grid equations are sufficiently accurate. Therefore, it is suggested in [1] that the convergence rate of compatible relaxation should be used as a criterion for choosing and evaluating the set of coarse-grid variables. Once a coarse grid is chosen for which compatible relaxation converges fast, it follows that ...
Date: November 6, 2000
Creator: McWilliams, J C
Partner: UNT Libraries Government Documents Department

ANALYSIS OF THE MAGNETIC FIELD MEASURED BY A ROTATING HALL PROBE IN A SOLENOID TO LOCATE ITS MAGNETIC AXIS.

Description: We have analyzed the motion of a Hall probe, which is rotated about an axis that is arbitrarily displaced and oriented with respect to the magnetic axis of a solenoid. We outline how the magnetic field measured by the rotating Hall probe can be calculated. We show how to compare theoretical results with actual measurements, to determine the displacement and orientation of the axis of rotation of the probe from the magnetic axis. If the center of rotation of the probe is known by surveying, the corresponding point on the magnetic axis of the solenoid can be located. This is applied to a solenoid that was built for BNL by Oxford Instruments.
Date: November 6, 2000
Creator: KPONOU,A.; PIKIN,A.; BEEBE,E. & ALESSI,J.
Partner: UNT Libraries Government Documents Department

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

Description: The purpose of this Analysis/Model (AMR) report is twofold. (1) The first is to present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the Probabilistic Volcanic Hazard Analysis (PVHA) (CRWMS M&O 1996). Conceptual models presented in the PVHA are summarized and extended in areas in which new information has been presented. Alternative conceptual models are discussed as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) The second purpose of the AMR is to present probability calculations based on PVHA outputs. Probability distributions are presented for the length and orientation of volcanic dikes within the repository footprint and for the number of eruptive centers located within the repository footprint (conditional on the dike intersecting the repository). The probability of intersection of a basaltic dike within the repository footprint was calculated in the AMR ''Characterize Framework for Igneous Activity at Yucca Mountain, Nevada'' (CRWMS M&O 2000g) based on the repository footprint known as the Enhanced Design Alternative [EDA II, Design B (CRWMS M&O 1999a; Wilkins and Heath 1999)]. Then, the ''Site Recommendation Design Baseline'' (CRWMS M&O 2000a) initiated a change in the repository design, which is described in the ''Site Recommendation Subsurface Layout'' (CRWMS M&O 2000b). Consequently, the probability of intersection of a basaltic dike within the repository footprint has also been calculated for the current repository footprint, which is called the 70,000 Metric Tons of Uranium (MTU) No-Backfill Layout (CRWMS M&O 2000b). The calculations for both footprints are presented in this AMR. In addition, the probability ...
Date: November 6, 2000
Creator: Perry, F. & Youngs, B.
Partner: UNT Libraries Government Documents Department

Compilation and Integration of K Basin Sludge Particle Size Analysis Data

Description: This report consolidates and integrates all of the particle size analysis data generated during the Hanford K Basin sludge characterization campaigns. The provides the most representative particle size distribution curves for the various K Basin sludge types. Understanding the particle size distribution of the sludge is necessary to design sludge retrieval and processing systems and to address sludge transportation and storage safety issues due to the potential reactivity of sludge.
Date: November 6, 2000
Creator: Bredt, Paul R.; Tingey, Joel M. & Schmidt, Andrew J.
Partner: UNT Libraries Government Documents Department

Corrosion of breached aluminide fuel under potential repository conditions.

Description: Permanent disposal of spent nuclear fuel is proposed in a repository located in the volcanic tuff beds near Yucca Mountain, Nevada, and it is the responsibility of the National Spent Nuclear Fuel Program (NSNFP) to provide the Yucca Mountain Project (YMP) with information related to the release of fission products from the DOE-owned SNF resulting from SNF corrosion. Hydrologically unsaturated spent fuel tests (''drip'' tests) are designed to simulate and monitor the release of radionuclides from the spent fuel under potential exposure conditions in the repository. Of the priority fuels being tested under the NSNFP, the aluminum-based fuels are included because of their high relative volume and uranium enrichment. The Al fuel structure is composed of fissile and aluminum powders pressed and annealed between Al plates to form thin metallic plates. The most widely used fissile powder was the intermetallic compound aluminide UAl{sub x} (where x=2,3,4). As part of this testing program, preliminary corrosion tests using unirradiated UAl{sub x} were initiated to address experimental design, sampling, and analysis issues prior to conducting tests with spent fuels. However, during this program the decision was made by U.S. DOE to convert the aluminum-based fuels to safer enrichment levels by using the melt-dilute process at Savannah River. Nonetheless, the product ingot of the melt-dilute process resembles low enriched UAl{sub x} fuel and corrosion of the fuel is expected to be similar. This paper summarizes the preliminary testing results for the first year of the program and compares them to other corrosion testing results on aluminum fuels as well as other DOE fuel types.
Date: November 6, 2000
Creator: Kaminski, M. D. & Goldberg, M. M.
Partner: UNT Libraries Government Documents Department

Defense Acquisitions: Prices of Navy Aviation Spare Parts Have Increased

Description: A letter report issued by the General Accounting Office with an abstract that begins "For some time, there has been concern over the increases in the prices of weapon systems spare parts and the adverse impact higher prices have had on military readiness. Prices for aviation spare parts managed by the Navy increased at an annual rate of 12 percent from 1994 to 1999. Several factors have contributed to price increases. First, the cost of repairing an item has generally gone up over time. Second, the surcharge that is charged to customers has also increased over time. The Navy has tried to alleviate customer concerns about high surcharge rates by moving certain overhead costs from the surcharge to repair costs. But this approach simply moved the overhead costs instead of reducing them. Still, the Navy understands the need to control spare parts prices and plans to further investigate the underlying causes of the increases."
Date: November 6, 2000
Creator: United States. General Accounting Office.
Partner: UNT Libraries Government Documents Department

DESIGN ISSUES FOR THE RHIC EBIS.

Description: Promising results are currently being obtained on the BNL Electron Beam Test Stand (EBTS), which is a prototype for the Relativistic Heavy Ion Collider (RHIC) EBIS. Based on the present-results, a proposal has been made regarding the general design of the RHIC EBIS. During the next year experiments will be made to investigate physics issues and beam properties important to the detailed design of the RHIC EBIS. Below we have outlined some of the physics issues to be explored experimentally, beam diagnostics that will be employed, and hardware modifications that are desired to go from the prototype stage to the RHIC EBIS.
Date: November 6, 2000
Creator: BEEBE,E.; ALESSI,J.; KPONOU,A.; PIKIN,A.; PRELEC,K.; KUZNETZOV,G. et al.
Partner: UNT Libraries Government Documents Department

EBTS:DESIGN AND EXPERIMENTAL STUDY.

Description: Experimental study of the BNL Electron Beam Test Stand (EBTS), which is a prototype of the Relativistic Heavy Ion Collider (RHIC) Electron Beam Ion Source (EBIS), is currently underway. The basic physics and engineering aspects of a high current EBIS implemented in EBTS are outlined and construction of its main systems is presented. Efficient transmission of a 10 A electron beam through the ion trap has been achieved. Experimental results on generation of multiply charged ions with both continuous gas and external ion injection confirm stable operation of the ion trap.
Date: November 6, 2000
Creator: PIKIN,A.; ALESSI,J.; BEEBE,E.; KPONOU,A.; PRELEC,K.; KUZNETSOV,G. et al.
Partner: UNT Libraries Government Documents Department

The Effect of Neutron and Gamma Ray Cross Talk Between Plastic Scintillating Detectors

Description: In this paper a method is developed, using higher order statistics, to identify the type and degree of neutron and gamma ray cross talk between detectors that are placed in proximity to one another. A set of measurements was performed using the Nuclear Materials Identification System (NMIS) to acquire the time-dependent bicovariance of the pulses in fast plastic scintillating detectors. These signatures were analyzed to infer the degree and type of false coincidences (cross talk) in relation to true coincidences.
Date: November 6, 2000
Creator: Pozzi, S.A.
Partner: UNT Libraries Government Documents Department

Form CJ-7, Parole Data Survey: 2000

Description: Blank parole data survey containing a series of questions related to the parole population in a particular location, with instructions for filling out the survey.
Date: November 6, 2000
Creator: United States. Bureau of Justice Statistics.
Partner: UNT Libraries Government Documents Department

Form CJ-8, Probation Data Survey: 2000

Description: Blank probation data survey containing a series of questions related to the probationary population in a particular location, with instructions for filling out the survey.
Date: November 6, 2000
Creator: United States. Bureau of Justice Statistics.
Partner: UNT Libraries Government Documents Department

INVESTIGATION OF A PLASMA MODE IN EBTS.

Description: A plasma related mode has been identified when EBTS operated with long trap length. The mode frequency scaling showed monotonic increased with confinement time. Initial scaling qualitatively suggested the mode to an electron beam driven ion cyclotron instability. However, a more quantitative evaluation is indicative of a drift mode. Nevertheless, the possibility of a structure mode, though unlikely, can not be completely excluded. The process of proper instability identification and stabilization is described.
Date: November 6, 2000
Creator: HERSHCOVITCH,A.
Partner: UNT Libraries Government Documents Department

Limiting the Accidental Pressure Drop in NIF Beam Tubes

Description: This report summarizes the use of a one-dimensional model of a time-dependent compressible flow condition to validate the results from a more sophisticated three-dimensional model. The flow conditions consist of the sudden decompression of a pressurized tube joined to an evacuated sphere, where the tube also has a leak to external atmosphere that is triggered open at a given pressure difference below sea-level pressure. This flow model is used to calculate conditions in a NIF beam tube if an internal vacuum barrier fails, and to calculate how the size and timing of an opening to external atmosphere changes tube pressure. Decompression of a NIF beam tube is a potential safety hazard since the tube could collapse if the tube pressure is reduced below the buckling limit. To prevent this from occurring, each pressurized section includes a rupture panel which is designed to open to external atmosphere at a given pressure difference. The inrush of external atmosphere through the rupture panel fills both the tube and the vacuum drawing on it, and in this way the pressure drop in the tube is quickly limited and reversed. In summary, the results from the 1D model indicate that the 3-D calculations are accurate and reasonable.
Date: November 6, 2000
Creator: Garcia, M
Partner: UNT Libraries Government Documents Department

PROPOSAL FOR AN EBIS BASED RHIC PREINJECTOR.

Description: A proposed new heavy ion preinjector for RHIC is described. The progress made at BNL on the development of an Electron Beam Ion Source (EBIS) has increased our confidence that one can build a preinjector meeting RHIC requirements using an EBIS producing intermediate charge state heavy ions. A new RFQ and Linac will be required to accelerate beams from this source to an energy sufficient for injection into the AGS Booster. These are both straightforward devices, very similar to ones already in operation at other laboratories. Injection into the Booster will occur at the same location as the existing heavy ion injection from the Tandem Van de Graaff.
Date: November 6, 2000
Creator: ALESSI,J.G.; BEEBE,E.; KPONOU,A.; PIKIN,A.; PRELEC,K.; RAPARIA,D. et al.
Partner: UNT Libraries Government Documents Department

Reactive spreading in ceramic/metal systems

Description: Reactive spreading, in which a chemically active element is added to promote wetting of noble metals on nonmetallic materials, is evaluated mechanistically. Theories for the energetics and kinetics of the steps involved in spreading are outlined to permit comparison to the steps in the compound formation that typically accompanies reactive wetting. These include: fluid flow, active metal adsorption, including nonequilibrium effects, and triple line ridging. They can all be faster than compound nucleation under certain conditions. This analysis plus assessment of recently reported experiments on metal/ceramic systems lead to a focus on those conditions under which spreading proceeds ahead of the actual formation of a new phase at the interface. This scenario may be more typical than commonly believed, and perhaps is the most effective situation leading to enhanced spreading. A rationale for the slow spreading rates plus the pervasive variability and hysteresis observed during high temperature wetting also emerges.
Date: November 6, 2000
Creator: Saiz, Eduardo; Cannon, Rowland M. & Tomsia, Antoni P.
Partner: UNT Libraries Government Documents Department

A Reduced Order, One Dimensional Model of Joint Response

Description: As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.
Date: November 6, 2000
Creator: DOHNER,JEFFREY L.
Partner: UNT Libraries Government Documents Department

Renewables for Sustainable Village Power

Description: This paper describes the efforts of NREL's Renewables for Sustainable Village Power team to match renewable energy technologies with rural energy needs in the international market. The paper describes the team's activities, updates the lessons learned, and proposes an integrated approach as a model for rural electrification with renewables.
Date: November 6, 2000
Creator: Flowers, L.; Baring-Gould, I.; Bianchi, J.; Corbus, D.; Drouilhet, S.; Elliott, D. et al.
Partner: UNT Libraries Government Documents Department

Research on parallel adaptive finite element methods

Description: In this project we studied several fundamental issues arising in the parallel adaptive solution of linear and nonlinear elliptic and parabolic PDEs using multilevel algorithms. We focused our attention on a new approach described in the paper ''A New Paradigm for Parallel Adaptive Mesh Refinement'' by Bank and Hoist. The new approach requires almost no communication to solve an elliptic equation in parallel, and therefore has the potential to scale much more efficiently on massively parallel computers than do more traditional algorithms. The algorithm described in the Bank and Hoist paper has an inherently multilevel structure, in that a sequence of problems on a refinement hierarchy of meshes is solved during the course of the calculation. In particular, the algorithm has three main components: (1) We solve a small problem on a coarse mesh, and use a posteriori error estimates to partition the mesh. (2) Each processor is provided the complete coarse mesh and instructed to solve the entire problem, but with its adaptive refinement largely limited to its own assigned mesh partition. (3) A final mesh is computed using the union of the refined partitions provided by each processor. The mesh is regularized into a global conformal mesh, and a final solution is computed using a standard overlapping domain decomposition method or a parallel multigrid method. In certain circumstances the third step can be avoided, leading to an algorithm with no communication beyond that required to synchronize the processors at the beginning of the calculation. We looked at the algorithm closely during the LLNL project in Summer 1999, and we examined algorithms for performing the third step of the algorithm efficiently on massively parallel computers, including parallel multilevel methods and mortar element methods. One result of the summer work at LLNL was a scheme for producing a global conforming ...
Date: November 6, 2000
Creator: Holst, M
Partner: UNT Libraries Government Documents Department

RHIC status and requirements

Description: Construction of the Brookhaven Relativistic Heavy Ion Collider (RHIC) was officially completed last year and commissioning has begun. RHIC is the first hadron accelerator and collider consisting of two independent rings. It is designed to operate over a wide range of beam energies and with particle species ranging from polarized protons to heavy ions. An overview of the status of commissioning and operation with gold is given and requirements for possible new ion sources are discussed.
Date: November 6, 2000
Creator: Roser, T.
Partner: UNT Libraries Government Documents Department