Asymmetric injection of cathodic arc plasma into a macroparticlefilter (open access)

Asymmetric injection of cathodic arc plasma into a macroparticlefilter

The cathodic arc plasmas produced by cathode spots usuallyinclude macroparticles, which is undesirable for many applications. Acommon way of removing macroparticles is to use curved solenoid filterswhich guide the plasma from the source to the substrate. In this work, anarc source with relatively small cathode is used, limiting the possiblelocations of plasma production. The relative position of cathodic arcsource and macroparticle filtered was systematically varied and thefiltered plasma current was recorded. It was found that axis-symmetricplasma injection leads to maximum throughput only if an anode aperturewas used, which limited the plasma to near-axis flow by scraping offplasma at larger angles to the axis. When the anode aperture was removed,more plasma could enter the filter. In this case, maximum filtered ioncurrent was achieved when the plasma was injected off-axis, namely offsetin the direction where the filter is curved. Such behavior wasanticipated because the plasma column in the filter is known to beshifted by ExB and centrifugal drift as well as by non-axis-symmetriccomponents of the magnetic field in the filter entrance and exit plane.The data have implications for plasma transport variations caused bydifferent spot locations on cathodes that are not small compared to thefilter cross section.
Date: February 11, 2004
Creator: Anders, Andre & MacGill, Robert A.
Object Type: Article
System: The UNT Digital Library
Speckle Imaging of Titan at 2 microns: Surface Albedo, Haze Optical Depth, and Tropospheric Clouds 1996-1998 (open access)

Speckle Imaging of Titan at 2 microns: Surface Albedo, Haze Optical Depth, and Tropospheric Clouds 1996-1998

We present results from 14 nights of observations of Titan in 1996-1998 using near-infrared (centered at 2.1 microns) speckle imaging at the 10-meter W.M. Keck Telescope. The observations have a spatial resolution of 0.06 arcseconds. We detect bright clouds on three days in October 1998, with a brightness about 0.5% of the brightness of Titan. Using a 16-stream radiative transfer model (DISORT) to model the central equatorial longitude of each image, we construct a suite of surface albedo models parameterized by the optical depth of Titan's hydrocarbon haze layer. From this we conclude that Titan's equatorial surface albedo has plausible values in the range of 0-0.20. Titan's minimum haze optical depth cannot be constrained from this modeling, but an upper limit of 0.3 at this wavelength range is found. More accurate determination of Titan's surface albedo and haze optical depth, especially at higher latitudes, will require a model that fully considers the 3-dimensional nature of Titan's atmosphere.
Date: February 11, 2004
Creator: Gibbard, S. G.; Gavel, D.; Ghez, A. M.; de Pater, I.; Max, C. E.; Young, E. F. et al.
Object Type: Article
System: The UNT Digital Library
ENHANCED RECOVERY UTILIZING VARIABLE FREQUENCY DRIVES AND A DISTRIBUTED POWER SYSTEM TECHNICAL PROGRESS REPORT (open access)

ENHANCED RECOVERY UTILIZING VARIABLE FREQUENCY DRIVES AND A DISTRIBUTED POWER SYSTEM TECHNICAL PROGRESS REPORT

This report describes the progress made during first six months of the project entitled ''Enhanced Recovery Utilizing Variable Frequency Drives and a Distributed Power System''. During this period, project plan, demonstration plan and project schedule were developed, equipment was ordered and baseline data was collected.
Date: February 11, 2004
Creator: Peden, Randy & Shah, Sanjiv
Object Type: Report
System: The UNT Digital Library
Evaluation of Proposed New LLW Disposal Activity Disposal of No Dose/Low Dose Scrap Metal in Slit Trenches (open access)

Evaluation of Proposed New LLW Disposal Activity Disposal of No Dose/Low Dose Scrap Metal in Slit Trenches

Activated metal is a special waste that requires evaluation for disposal. Contaminants in the activated metal will leach more slowly than will contaminants in generic waste. There is an inventory of activated scrap metal in the 105-L Disassembly Basin. Approximately 1,600 ft3 of the material is characterized as ''No Dose/Low Dose'' and consists mainly of activated aluminum and aluminum alloy pieces and parts and no stainless steel with a dose rate less than 200 mR per hr. Contaminants in the activated metal will leach more slowly than will contaminants in generic waste. The change in the leach rate will affect analyses for the groundwater pathway and intruder scenarios. For this evaluation, the slower leach rate from the activated metal waste will be neglected for the groundwater pathway, which is conservative because the higher leach rate used tends to produce higher groundwater concentrations and lower inventory limits. For this evaluation, the leach rate was set to zero for intruder scenarios, which is conservative for the inadvertent intruder because a slower leach rate will result in higher levels of radionuclides in the waste zone. The evaluation concludes that the existing limits are applicable to the disposal of No Dose/Low Dose activated scrap …
Date: February 11, 2004
Creator: Cook, J. R.
Object Type: Report
System: The UNT Digital Library
UZ Flow Models and Submodels (open access)

UZ Flow Models and Submodels

The purpose of this Model Report is to document the unsaturated zone (UZ) fluid flow and tracer transport models and submodels as well as the flow fields generated utilizing the UZ Flow and Transport Model of Yucca Mountain (UZ Model), Nevada. This work was planned in ''Technical Work Plan (TWP) for: Performance Assessment Unsaturated Zone'' (BSC 2002 [160819], Section 1.10, Work Package AUZM06). The UZ Model has revised, updated, and enhanced the previous UZ Flow Model REV 00 ICN 01 (BSC 2001 [158726]) by incorporation of the conceptual repository design with new grids, recalibration of property sets, and more comprehensive validation effort. The flow fields describe fracture-fracture, matrix-matrix, and fracture-matrix liquid flow rates and their spatial distributions as well as moisture conditions in the UZ system. These 3-D UZ flow fields are used directly by Performance Assessment (PA). The model and submodels evaluate important hydrogeologic processes in the UZ as well as geochemistry and geothermal conditions. These provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic conditions. In addition, this Model Report supports several PA activities, including abstractions, particle-tracking transport simulations, and the …
Date: February 11, 2004
Creator: Dixon, P.
Object Type: Report
System: The UNT Digital Library
Job scheduling in a heterogenous grid environment (open access)

Job scheduling in a heterogenous grid environment

Computational grids have the potential for solving large-scale scientific problems using heterogeneous and geographically distributed resources. However, a number of major technical hurdles must be overcome before this potential can be realized. One problem that is critical to effective utilization of computational grids is the efficient scheduling of jobs. This work addresses this problem by describing and evaluating a grid scheduling architecture and three job migration algorithms. The architecture is scalable and does not assume control of local site resources. The job migration policies use the availability and performance of computer systems, the network bandwidth available between systems, and the volume of input and output data associated with each job. An extensive performance comparison is presented using real workloads from leading computational centers. The results, based on several key metrics, demonstrate that the performance of our distributed migration algorithms is significantly greater than that of a local scheduling framework and comparable to a non-scalable global scheduling approach.
Date: February 11, 2004
Creator: Oliker, Leonid; Biswas, Rupak; Shan, Hongzhang & Smith, Warren
Object Type: Report
System: The UNT Digital Library
FEMIS Installation Guide v1.5.3 SR1 Addendum to the FEMIS System Administration Guide v1.5.3 (open access)

FEMIS Installation Guide v1.5.3 SR1 Addendum to the FEMIS System Administration Guide v1.5.3

FEMIS v1.5.3 SR1 includes updates to Section 2.0, FEMIS UNIX Installation, for the FEMIS Installation Guide.
Date: February 11, 2004
Creator: Homer, Brian J.; Carter, Richard J.; Dunkle, Julie R.; Johnson, Sharon M. & Wood, Blanche M.
Object Type: Text
System: The UNT Digital Library
Simulation Analysis of Inspections of International Travelers at Los Angeles International Airport for US-VISIT (open access)

Simulation Analysis of Inspections of International Travelers at Los Angeles International Airport for US-VISIT

The United States Visitor and Immigrant Status Indicator Technology Program (US-VISIT) will deploy biometric and other systems to identify and track foreign nationals entering and exiting the U.S. Evaluation of the large number of possible policy options and technical configurations for implementation of US-VISIT requires validated system analyses with appropriate tools that can address the requirements of this new program and its processes. Early identification of performance issues and capability gaps will prove critical to the success of the program.
Date: February 11, 2004
Creator: Edmunds, T.; Sholl, P.; Yao, Y.; Gansemer, J.; Cantwell, E.; Prosnitz, D. et al.
Object Type: Report
System: The UNT Digital Library
Rapporteurs' Report (open access)

Rapporteurs' Report

This Third FSC workshop focused on, ''Understanding the factors that influence public perception and confidence in the area of radioactive waste management...'' The workshop was held in Finland in close cooperation with Finnish stakeholders. This was most appropriate because of the recent successes in achieving positive decisions at the municipal, governmental, and Parliamentary levels, allowing the Finnish high-level radioactive waste repository program to proceed, including the identification of a proposed site. The workshop objective was to gain insight in answering the question, ''How did this political and societal decision come about?''
Date: February 11, 2004
Creator: Isaacs, T H
Object Type: Article
System: The UNT Digital Library
Modeling and characterization of recompressed damaged materials (open access)

Modeling and characterization of recompressed damaged materials

Experiments have been performed to explore conditions under which spall damage is recompressed with the ultimate goal of developing a predictive model. Spall is introduced through traditional gas gun techniques or with laser ablation. Recompression techniques producing a uniaxial stress state, such as a Hopkinson bar, do not create sufficient confinement to close the porosity. Higher stress triaxialities achieved through a gas gun or laser recompression can close the spall. Characterization of the recompressed samples by optical metallography and electron microscopy reveal a narrow, highly deformed process zone. At the higher pressures achieved in the gas gun, little evidence of spall remains other than differentially etched features in the optical micrographs. With the very high strain rates achieved with laser techniques there is jetting from voids and other signs of turbulent metal flow. Simulations of spall and recompression on micromechanical models containing a single void suggest that it might be possible to represent the recompression using models similar to those employed for void growth. Calculations using multiple, randomly distributed voids are needed to determine if such models will yield the proper behavior for more realistic microstructures.
Date: February 11, 2004
Creator: Becker, R.; Cazamias, J. U.; Kalantar, D. H.; LeBlanc, M. M. & Springer, H. K.
Object Type: Report
System: The UNT Digital Library
CREME: Cis-Regulatory Module Explorer for the Human Genome (open access)

CREME: Cis-Regulatory Module Explorer for the Human Genome

The binding of transcription factors to specific regulatory sequence elements is a primary mechanism for controlling gene transcription. Eukaryotic genes are often regulated by several transcription factors, whose binding sites are tightly clustered and form cis-regulatory modules. In this paper we present a web-server, CREME, for identifying and visualizing cis-regulatory modules in the promoter regions of a given set of potentially co-regulated genes. CREME relies on a database of putative transcription factor binding sites that have been annotated across the human genome using a library of position weight matrices and evolutionary conservation with the mouse and rat genomes. A search algorithm is applied to this dataset to identify combinations of transcription factors whose binding sites tend to co-occur in close proximity in the promoter regions of the input gene set. The identified cis-regulatory modules are statistically scored and significant combinations are reported and graphically visualized. Our web-server is available at http://creme.dcode.org/.
Date: February 11, 2004
Creator: Loots, G G; Sharan, R; Ovcharenko, I & Ben-Hur, A
Object Type: Article
System: The UNT Digital Library
Metastability and Delta-Phase Retention in Plutonium Alloys Final Report of LDRD Project 01-ERD-029 (open access)

Metastability and Delta-Phase Retention in Plutonium Alloys Final Report of LDRD Project 01-ERD-029

The {delta} to {alpha}' phase transformation in Pu-Ga alloys is intriguing for both scientific and technological reasons. On cooling, the ductile fcc {delta}-phase transforms martensitically to the brittle monoclinic {alpha}'-phase at approximately -120 C (depending on composition). This exothermic transformation involves a 20% volume contraction and a significant increase in resistivity. The reversion of {alpha}' to {delta} involves a large temperature hysteresis beginning just above room temperature. In an attempt to better understand the underlying thermodynamics and kinetics responsible for these unusual features, we have investigated the {delta} {leftrightarrow} {alpha}' phase transformations in a Pu-0.6 wt% Ga alloy using a combination of experimental and modeling techniques.
Date: February 11, 2004
Creator: Wong, J; Schwartz, A J; Blobaum, K M; Krenn, C R; Wall, M A; Wolfer, W G et al.
Object Type: Report
System: The UNT Digital Library
Bovine Enterovirus Type 2. Complete Genomic Sequence and Molecular Modeling of a Reference Strain and a Wild Type Isolate from Endemically Infected US Cattle. (open access)

Bovine Enterovirus Type 2. Complete Genomic Sequence and Molecular Modeling of a Reference Strain and a Wild Type Isolate from Endemically Infected US Cattle.

None
Date: February 11, 2004
Creator: Zhou, C E; Zemla, A; Goens, S D; Botero, S & Perdue, M L
Object Type: Article
System: The UNT Digital Library
FEMIS System Administration Guide v1.5.3 SR1 Addendum to the FEMIS Installatiion Guide v1.5.3 (open access)

FEMIS System Administration Guide v1.5.3 SR1 Addendum to the FEMIS Installatiion Guide v1.5.3

FEMIS v1.5.3 SR1 includes updates to Section 8.0, FEMIS GIS Database, for the v1.5.3 FEMIS System Administration Guide.
Date: February 11, 2004
Creator: Stephan, Alex J.; Loveall, Robert M.; Dunkle, Julie R.; Johnson, Sharon M. & Wood, Blanche M.
Object Type: Text
System: The UNT Digital Library
SPEIR: A Ge Compton Camera (open access)

SPEIR: A Ge Compton Camera

The SPEctroscopic Imager for {gamma}-Rays (SPEIR) is a new concept of a compact {gamma}-ray imaging system of high efficiency and spectroscopic resolution with a 4-{pi} field-of-view. The system behind this concept employs double-sided segmented planar Ge detectors accompanied by the use of list-mode photon reconstruction methods to create a sensitive, compact Compton scatter camera.
Date: February 11, 2004
Creator: Mihailescu, L; Vetter, K M; Burks, M T; Hull, E L & Craig, W W
Object Type: Report
System: The UNT Digital Library
Radiation Detection Field Test at the Federal Express (FedEx) Air Cargo Facility at Denver International Airport (DIA) (open access)

Radiation Detection Field Test at the Federal Express (FedEx) Air Cargo Facility at Denver International Airport (DIA)

Lawrence Livermore National Laboratory (LLNL) recently conducted a field-test of radiation detection and identification equipment at the air cargo facility of Federal Express (FedEx) located at Denver International Airport (DIA) over a period of two weeks. Comprehensive background measurements were performed and were analyzed, and a trial strategy for detection and identification of parcels displaying radioactivity was implemented to aid in future development of a comprehensive protection plan. The purpose of this project was threefold: {sm_bullet} Quantify background radiation environments at an air cargo facility. {sm_bullet} Quantify and identify ''nuisance'' alarms. {sm_bullet} Evaluate the performance of various isotope identifiers deployed in an operational environment (in this case, the operational environment included the biggest blizzard in over 90 years!).
Date: February 11, 2004
Creator: Weirup, D.; Waters, A.; Hall, H.; Dougan, A.; Trombino, D.; Mattesich, G. et al.
Object Type: Article
System: The UNT Digital Library
Atomic scale structure of the 5-fold surface of an AlPdMn quasicrystal: A quantitative X-Ray photoelectron diffraction analysis (open access)

Atomic scale structure of the 5-fold surface of an AlPdMn quasicrystal: A quantitative X-Ray photoelectron diffraction analysis

The atomic scale structure of the 5-fold symmetric surface of an AlPdMn quasicrystal is investigated quantitatively by comparing x-ray photoelectron diffraction (XPD) simulations to experiment. The observed 5-fold symmetry of the diffraction patterns indicates that the surface is quasicrystalline with no hint of a reconstruction from the bulk structure. In analyzing the experimental data, many possible bulk terminations have been tested. Those few that fit best to the data have in common that they contain an Al-rich surface layer followed by a dense mixed Al/Pd/Mn layer. These best terminations, while not identical to each other, are suggested to form terraces coexisting on a real surface. Structural relaxations of the quasicrystal surface are also analyzed: mixing several best-fit terminations gives average best-fit interlayer spacing changes of Dd12 = -0.057 Angstrom, Dd24 = +0.159 Angstrom. These results are in good agreement with a prior structure determination by LEED on a sample that was prepared in a different manner.
Date: February 11, 2004
Creator: Zheng, Jin-Cheng; Huan, C. H. A.; Wee, A. T. S.; Van Hove, M. A.; Fadley, C. S.; Shi, F. J. et al.
Object Type: Article
System: The UNT Digital Library
Macro and Micro Remote Viewing of Objects in Sealed Gloveboxes (open access)

Macro and Micro Remote Viewing of Objects in Sealed Gloveboxes

The Savannah River Site uses sophisticated glovebox facilities to process and analyze material that is radiologically contaminated or that must be protected from contamination by atmospheric gases. The analysis can be visual, non destructive measurement, or destructive measurement, and allows for the gathering of information that would otherwise not be obtainable. Macro and Micro systems that cover a range of 2X to 400X magnifications with a robust system compatible with the harsh glovebox environment were installed. Remote video inspection systems were developed and deployed in Savannah River Site glovebox facilities that provide high quality or mega-pixel quality remote views, for remote inspections. The specialized video systems that are the subject of this report exhibited specialized field application of remote video/viewing techniques by expanding remote viewing to high and very high quality viewing in gloveboxes. This technological enhancement will allow the gathering of precision information that is otherwise not available.
Date: February 11, 2004
Creator: Heckendorn, F.M.
Object Type: Article
System: The UNT Digital Library