Unstructured Mesh Connectivity in Unstructured Mapping (open access)

Unstructured Mesh Connectivity in Unstructured Mapping

The connectivity interface for UnstructuredMapping has been rewritten to provide a more thorough interface to the mesh. This new design also resembles the TSTT mesh query interface. While data is still stored in array form, indexed by integers, the interface provides iterators through the mesh entities and adjacencies. This document describes the additions to the UnstructuredMapping class as well as the definition and use of the UnstructuredMappingIterator and UnstructuredMappingAdjacencyIterator classes.
Date: October 22, 2002
Creator: Chand, K
Object Type: Text
System: The UNT Digital Library
Results of active well coincidence counter cross-calibration measurements at Argonne National Laboratory-West. (open access)

Results of active well coincidence counter cross-calibration measurements at Argonne National Laboratory-West.

Nondestructive Assay (NDA) of Nuclear Materials (NM) is a common tool used by inspectors involved in Material Protection, Control and Accounting (MPC&A) programs, both domestically and internationally. NDA is generally used to quantify the properties of NM, usually by determining the mass or enrichment of materials such as U-235 or Pu-240. For the NDA of Highly Enriched Uranium (HEU) metal, powder or scrap samples, Active Well Coincidence Counter (AWCC) NDA systems are routinely used. These systems bombard samples with neutrons, inducing fission events. The fissile mass of the sample is determined based upon the number of coincidence neutrons detected. To obtain accurate quantitative measurements using AWCC systems it is necessary to calibrate the instruments using physical standards representative of the unknown sample to be measured. During international inspections it is both expensive and difficult to obtain the large number of physical standards necessary to accurately assay the wide range of NM present at multiple sites. To address this issue, a cross-calibration method has been developed by Los Alamos National Laboratory (LANL) allowing the transfer of calibration parameters measured to field inspection systems without the need for physical standards. Argonne National Laboratory-West (ANLW) routinely uses AWCC systems as part of its …
Date: October 22, 2002
Creator: Jensen, B. A.; Sanders, J.; Wenz, T. & R., Buchheit.
Object Type: Report
System: The UNT Digital Library
Impact of random numbers on parallel Monte Carlo application (open access)

Impact of random numbers on parallel Monte Carlo application

A number of graduate students are involved at various level of research in this project. We investigate the basic issues in materials using Monte Carlo simulations with specific interest in heterogeneous materials. Attempts have been made to seek collaborations with the DOE laboratories. Specific details are given.
Date: October 22, 2002
Creator: Pandey, Ras B.
Object Type: Report
System: The UNT Digital Library
Evaluation of Corrosion Failure in Tractor-Trailer Brake System (open access)

Evaluation of Corrosion Failure in Tractor-Trailer Brake System

As reported to ORNL, concomitant with the introduction of different deicing and anti-icing compounds, there was an increase in the brake failure rate of tractor-trailer trucks. A forensic evaluation of a failed brake system was performed. Optical and scanning electron microscopic evaluation showed corrosion to be mostly confined to the brake table/lining interface. The corrosion is non-uniform as is to be expected for plain carbon steel in chloride environments. This initial analysis found no evidence for the chlorides of calcium and magnesium, which are the newly introduced deicing and antiicing compounds and are less soluble in water than the identified chlorides of sodium and potassium, in the scale. The result could be as a result of non-exposure of the examined brake table to calcium and magnesium chloride. The mechanisms for the increased failure rate are postulated as being an increased rate of corrosion due to positive shifts in the corrosion potential, and an increased amount of corrosion due to an increased ''time of wetness'' that results from the presence of hygroscopic salts. Laboratory scale evaluation of the corrosion of plain carbon steel in simulated deicing and anti-icing solutions need to be performed to determine corrosion rates and morphological development of …
Date: October 22, 2002
Creator: Wilson, DF
Object Type: Report
System: The UNT Digital Library
Aerial Image Microscopes for the Inspection of Defects in EUV Masks (open access)

Aerial Image Microscopes for the Inspection of Defects in EUV Masks

The high volume inspection equipment currently available to support development of EUV blanks is non-actinic. The same is anticipated for patterned EUV mask inspection. Once potential defects are identified and located by such non-actinic inspection techniques, it is essential to have instrumentation to perform detailed characterization, and if repairs are performed, re-evaluation. The ultimate metric for the acceptance or rejection of a mask due to a defect, is the wafer level impact. Thus measuring the aerial image for the site under question is required. An EUV Aerial Image Microscope (''AIM'') similar to the current AIM tools for 248nm and 193nm exposure wavelength is the natural solution for this task. Due to the complicated manufacturing process of EUV blanks, AIM measurements might also be beneficial to accurately assessing the severity of a blank defect. This is an additional application for an EUV AIM as compared to today's use In recognition of the critical role of an EUV AIM for the successful implementation of EUV blank and mask supply, International SEMATECH initiated this design study with the purpose to define the technical requirements for accurately simulating EUV scanner performance, demonstrating the feasibility to meet these requirements and to explore various technical approaches …
Date: October 22, 2002
Creator: Barty, A.; Taylor, J. S.; Hudyma, R.; Spiller, E.; Sweeney, D. W.; Shelden, G. et al.
Object Type: Article
System: The UNT Digital Library
A Markov Chain Monte Carlo Based Method for System Identification (open access)

A Markov Chain Monte Carlo Based Method for System Identification

This paper describes a novel methodology for the identification of mechanical systems and structures from vibration response measurements. It combines prior information, observational data and predictive finite element models to produce configurations and system parameter values that are most consistent with the available data and model. Bayesian inference and a Metropolis simulation algorithm form the basis for this approach. The resulting process enables the estimation of distributions of both individual parameters and system-wide states. Attractive features of this approach include its ability to: (1) provide quantitative measures of the uncertainty of a generated estimate; (2) function effectively when exposed to degraded conditions including: noisy data, incomplete data sets and model misspecification; (3) allow alternative estimates to be produced and compared, and (4) incrementally update initial estimates and analysis as more data becomes available. A series of test cases based on a simple fixed-free cantilever beam is presented. These results demonstrate that the algorithm is able to identify the system, based on the stiffness matrix, given applied force and resultant nodal displacements. Moreover, it effectively identifies locations on the beam where damage (represented by a change in elastic modulus) was specified.
Date: October 22, 2002
Creator: Glaser, R. E.; Lee, C. L.; Nitao, J. J. & Hanley, W. G.
Object Type: Article
System: The UNT Digital Library
Connectivity in Random Grain Boundary Networks (open access)

Connectivity in Random Grain Boundary Networks

Mechanical properties of FCC metals and alloys can be improved by exercising control over the population of grain boundary types in the microstructure. The existing studies also suggest that such properties tend to have percolative mechanisms that depend on the topology of the grain boundary network. With the emergence of SEM-based automated electron backscatter diffraction (EBSD), statistically significant datasets of interface crystallography can be analyzed in a routine manner, giving new insight into the topology and percolative properties of grain boundary networks. In this work, we review advanced analysis techniques for EBSD datasets to quantify microstructures in terms of grain boundary character and triple junction distributions, as well as detailed percolation-theory based cluster analysis.
Date: October 22, 2002
Creator: Kumar, M; Schuh, C A & King, W E
Object Type: Article
System: The UNT Digital Library
ELECTRONS IN NONPOLAR LIQUIDS. (open access)

ELECTRONS IN NONPOLAR LIQUIDS.

Excess electrons can be introduced into liquids by absorption of high energy radiation, by photoionization, or by photoinjection from metal surfaces. The electron's chemical and physical properties can then be measured, but this requires that the electrons remain free. That is, the liquid must be sufficiently free of electron attaching impurities for these studies. The drift mobility as well as other transport properties of the electron are discussed here as well as electron reactions, free-ion yields and energy levels, Ionization processes typically produce electrons with excess kinetic energy. In liquids during thermalization, where this excess energy is lost to bath molecules, the electrons travel some distance from their geminate positive ions. In general the electrons at this point are still within the coulombic field of their geminate ions and a large fraction of the electrons recombine. However, some electrons escape recombination and the yield that escapes to become free electrons and ions is termed G{sub fi}. Reported values of G{sub fi} for molecular liquids range from 0.05 to 1.1 per 100 eV of energy absorbed. The reasons for this 20-fold range of yields are discussed here.
Date: October 22, 2002
Creator: Holroyd, R. A.
Object Type: Book
System: The UNT Digital Library
Conceptual design study of Nb3Sn low-beta quadrupoles for 2nd generation LHC IRs (open access)

Conceptual design study of Nb3Sn low-beta quadrupoles for 2nd generation LHC IRs

Conceptual designs of 90-mm aperture high-gradient quadrupoles based on the Nb{sub 3}Sn superconductor, are being developed at Fermilab for possible 2nd generation IRs with the similar optics as in the current low-beta insertions. Magnet designs and results of magnetic, mechanical, thermal and quench protection analysis for these magnets are presented and discussed.
Date: October 22, 2002
Creator: al., Alexander V Zlobin et
Object Type: Article
System: The UNT Digital Library
BROOKHAVEN NATIONAL LABORATORY WILDLIFE MANAGEMENT PLAN. (open access)

BROOKHAVEN NATIONAL LABORATORY WILDLIFE MANAGEMENT PLAN.

The purpose of the Wildlife Management Plan (WMP) is to promote stewardship of the natural resources found at the Brookhaven National Laboratory (BNL), and to integrate their protection with pursuit of the Laboratory's mission.
Date: October 22, 2002
Creator: NAIDU,J.R.
Object Type: Report
System: The UNT Digital Library
Modeling of Capillary Discharge Plasma for X-Ray Lasers, XUV Lithography and Other Applications (open access)

Modeling of Capillary Discharge Plasma for X-Ray Lasers, XUV Lithography and Other Applications

It is long ago recognized that Z-pinches represent very natural medium for x-ray lasers (XRL) due to its favorable geometry and achievable high densities and temperatures. They also are very efficient x-ray sources. One of their variants, the capillary discharges, attracted attention of plasma physics researchers for almost two decades. It has been used for hot dense plasma formation and x-ray lasers[1,2], for transportation of laser beams and XUV radiation generation in x-ray lithography[3,4], for basic Z-pinch research and some others. The combination of efficiency, simplicity and low cost of capillary electrical discharges allowed to scale capillary x-ray lasers to table-top dimensions. In this paper we show the modeling results for next, 3-4 times shorter wavelength x-ray lasers. As an efficient x-ray source of line and continuum radiation it can be used for many practically important application in science and technology. In particular, the capillary discharge can appear as powerful potential candidate for emerging XUV microlithography. We present here the results of numerical modeling of spectra and density of Xe EUV source which involved plasma heating and dynamics, detailed atomic kinetics and radiation transport and material ablation physics.
Date: October 22, 2002
Creator: Shlyaptsev, V. N.; Dunn, J.; Moon, S. J.; Fournier, K. B.; Osterheld, A. L.; Rocca, J. J. et al.
Object Type: Article
System: The UNT Digital Library