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Paradyn a parallel nonlinear, explicit, three-dimensional finite-element code for solid and structural mechanics user manual
ParaDyn is a parallel version of the DYNA3D computer program, a three-dimensional explicit finite-element program for analyzing the dynamic response of solids and structures. The ParaDyn program has been used as a production tool for over three years for analyzing problems which range in size from a few tens of thousands of elements to between one-million and ten-million elements. ParaDyn runs on parallel computers provided by the Department of Energy Accelerated Strategic Computing Initiative (ASCI) and the Department of Defense High Performance Computing and Modernization Program. Preprocessing and post-processing software utilities and tools are designed to facilitate the generation of partitioned domains for processors on a massively parallel computer and the visualization of both resultant data and boundary data generated in a parallel simulation. This manual provides a brief overview of the parallel implementation; describes techniques for running the ParaDyn program, tools and utilities; and provides examples of parallel simulations.
Date:
June 1, 2000
Creator:
Hoover, C G; DeGroot, A J & Sherwood, R J
Object Type:
Report
System:
The UNT Digital Library
Internal Voltage in a Conducting Closed Hollow Cylinder With an Attached End Plate Subjected to a Direct Lightning Strike
The interior voltage of a large metal can with thick walls struck directly by lightning was estimated using diffusion theory, aperture slot voltage theory, and experimental data. The hollow cylinder is closed at both ends. One end has a cap that is welded to the cylinder wall making a continuous electrical interface. The other end consists of a circular plate that is pressed into the cylinder wall and held under pressure with a threaded ring. From our experience with coupling measurements, this joint will be a weak link. It will allow more current to leak into the interior than from diffusion through the walls. Because the joint was designed for mechanical purposes, the electrical properties, such as continuity around the circumference, are not well controlled. Therefore, it is difficult to determine a single voltage attributed to this joint design with varying electrical characteristics. Instead, we will make a best effort of bounding the problem using both analytical calculations and data from tests of similar structures. The calculated internal cylinder voltage subjected to an extreme lightning strike from current diffusing through the wall is 19 volts. We estimate that the press-fit end plate will increase this voltage by a factor of …
Date:
June 1, 2000
Creator:
Ong, M. M. & Anderson, R. A.
Object Type:
Report
System:
The UNT Digital Library
Implicit Monte Carlo diffusion - an acceleration method for Monte Carlo time dependent radiative transfer simulations
We present a method for accelerating time dependent Monte Carlo radiative transfer calculations by using a discretization of the diffusion equation to calculate probabilities that are used to advance particles in regions with small mean free path. The method is demonstrated on problems with on 1 and 2 dimensional orthogonal grids. It results in decreases in run time of more than an order of magnitude on these problems, while producing answers with accuracy comparable to pure IMC simulations. We call the method Implicit Monte Carlo Diffusion, which we abbreviate IMD.
Date:
October 1, 2000
Creator:
Gentile, N. A.
Object Type:
Article
System:
The UNT Digital Library
Multiscale thermohydrologic model: addressing variability and uncertainty at Yucca Mountain
Performance assessment and design evaluation require a modeling tool that simultaneously accounts for processes occurring at a scale of a few tens of centimeters around individual waste packages and emplacement drifts, and also on behavior at the scale of the mountain. Many processes and features must be considered, including non-isothermal, multiphase-flow in rock of variable saturation and thermal radiation in open cavities. Also, given the nature of the fractured rock at Yucca Mountain, a dual-permeability approach is needed to represent permeability. A monolithic numerical model with all these features requires too large a computational cost to be an effective simulation tool, one that is used to examine sensitivity to key model assumptions and parameters. We have developed a multi-scale modeling approach that effectively simulates 3D discrete-heat-source, mountain-scale thermohydrologic behavior at Yucca Mountain and captures the natural variability of the site consistent with what we know from site characterization and waste-package-to-waste-package variability in heat output. We describe this approach and present results examining the role of infiltration flux, the most important natural-system parameter with respect to how thermohydrologic behavior influences the performance of the repository.
Date:
October 1, 2000
Creator:
Buscheck, T; Rosenberg, N D; Gansemer, J D & Sun, Y
Object Type:
Article
System:
The UNT Digital Library
Alternate Approach to the 239Pu(n,2n) Cross Section
Using existing experimental data for neutron-induced total, elastic, inelastic, reaction and fission cross sections, as well as results from nuclear model calculations and evaluations from nuclear reaction data libraries, we derived an estimate for the cross sections for the {sup 235}U(n,2n) and {sup 239}Pu(n,2n) reactions for the neutron energy range from threshold to approximately 12 MeV. In effect, our approach is based on subtracting the fission and inelastic cross sections from the total reaction cross section where the difference is expected to yield the (n,2n) cross section. In addition to this subtraction approach, a ratio method and a differential method have also been explored. For {sup 235}U(n,2n), as a test case, we arrive at a cross section consistent with previous measurements, and for {sup 239}Pu(n,2n) we obtain a peak value of 400 {+-} 60 mb for the incident neutron energy range of 10 {le} E{sub n} {le} 12 MeV.
Date:
September 1, 2000
Creator:
Anderson, J. D.; Bauer, R. W.; Becker, J. A.; Dietrich, F. S. & McNabb, D. P.
Object Type:
Report
System:
The UNT Digital Library
State Renewable Energy News -- Vol. 9, No. 2, Summer 2000 (Newsletter)
This newsletter is prepared for the NARUC Subcommittee on Renewable Energy to promote information sharing on state-level renewable electric activities. It is sponsored by the Office of Power Technologies of the U.S. Department of Energy.
Date:
July 1, 2000
Creator:
unknown
Object Type:
Journal/Magazine/Newsletter
System:
The UNT Digital Library
Fissile Materials Disposition Program Plutonium Immobilization Project Baseline Formulation
Since 1994 Lawrence Livermore National Laboratory (LLNL), with the help of several other laboratories and university groups, has been the lead laboratory for the Plutonium Immobilization Project (PIP). This involves, among other tasks, the development of a formulation and a fabrication process for a ceramic to be used in the immobilization of excess weapons-usable plutonium. This report reviews the history of the project as it relates to the development of the ceramic form. It describes the sample test plan for the pyrochlore-rich ceramic formulation that was selected, and it specifies the baseline formulation that has been adopted. It also presents compositional specifications (e.g. precursor compositions and mixing recipes) and other form and process specifications that are linked or potentially linked to the baseline formulation.
Date:
September 1, 2000
Creator:
Ebbinghaus, Bartley B.; Armantrout, Guy A.; Gray, Leonard; Herman, Connie C.; Shaw, Henry F. & Van Konynenburg, Richard A.
Object Type:
Report
System:
The UNT Digital Library
DARHT-II Downstream Beam Transport Beamline
This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-{micro}sec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is approximately 20-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 15 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and to the beam dumps. There are two high power beam dumps, which are designed to absorb 80-kJ per pulse during accelerator start-up and operation. Aspects of the mechanical design of these elements are presented.
Date:
August 1, 2000
Creator:
Westenskow, G A; Bertolini, L R; Duffy, P T & Paul, A C
Object Type:
Article
System:
The UNT Digital Library
An AFM investigation of the interaction of chiral amino acids with the {l_brace}104{r_brace} face of calcite
In biomineralized tissue, Nature often uses a single crystal system to form tools with widely varied form and functionality. To accomplish this, organisms have developed methods to deterministically modify and control crystal habit, commonly creating shapes with lower symmetry than is possessed by the pure crystal. In this paper we use atomic force microscopy to investigate the effect of chiral amino acids on calcite growth. We show that the atomic steps and resultant macroscopic shape exhibit a lower symmetry that reflects the chirality of the amino acid. We use this result to constrain the possible stereospecific binding sites. We argue that the change in morphology is not due to the incorporation of the amino acid, but rather that it acts like a surfactant changing the energetics of the interface. These results suggest that the conventional paradigm for understanding the geometrical and chemical aspects of biomineralization in terms of stereochemical recognition should be expanded to capture the energetic controls that determine the mechanisms of mineral modification by biomolecules.
Date:
October 1, 2000
Creator:
Orme, C A; Noy, A; McBride, M T & DeYoreo, J J
Object Type:
Article
System:
The UNT Digital Library
Optical specification -- Their Role in the National Ignition Facility
The National Ignition Facility (NIF) has completed its design phase and is well into construction. In this talk, we review the optic specification rationale, along with examples of particular specifications and measurements.
Date:
March 1, 2000
Creator:
Lawson, J K; Aikens, D M; Wang, D Y & Williams, W H
Object Type:
Article
System:
The UNT Digital Library
Determination of Reactive Surface Area of Melt Glass
A comprehensive investigation of natural and manmade silicate glasses, and nuclear melt glass was undertaken in order to derive an estimate of glass reactive surface area. Reactive surface area is needed to model release rates of radionuclides from nuclear melt glass in the subsurface. Because of the limited availability of nuclear melt glasses, natural volcanic glass samples were collected which had similar textures and compositions as those of melt glass. A flow-through reactor was used to measure the reactive surface area of the analog glasses in the presence of simplified NTS site ground waters. A measure of the physical surface area of these glasses was obtained using the BET gas-adsorption method. The studies on analog glasses were supplemented by measurement of the surface areas of pieces of actual melt glass using the BET method. The variability of the results reflect the sample preparation and measurement techniques used, as well as textural heterogeneity inherent to these samples. Based on measurements of analog and actual samples, it is recommended that the hydraulic source term calculations employ a range of 0.001 to 0.01 m{sup 2}/g for the reactive surface area of nuclear melt glass.
Date:
October 1, 2000
Creator:
Bourcier,W. L.; Roberts, S.; Smith, D. K.; Hulsey, S.; Newton,L.; Sawvel, A. et al.
Object Type:
Report
System:
The UNT Digital Library
Experimental Determination of Contaminant Metal Mobility as a Function of Temperature, Time and Solution Chemistry
During the FY96-FY99 funding cycle we examined the uptake of aqueous strontium onto goethite, kaolinite, and amorphous silica surfaces as a function of pH, total strontium, and temperature. Our overall goal was to produce a mechanistic sorption model that can be used in reaction-transport calculations to predict the mobility and attenuation of radioactive strontium ({sup 90}Sr)in the environment. Our approach was to combine structural information derived from EXAFS analysis together with macroscopic uptake data and surface complexation models to clarify the physical and chemical structure of sorbed complexes. We chose to study these solids because of the prevalence of clays and iron hydroxides in natural systems, and because silica colloids probably form beneath leaking tanks at Hanford as caustic waste is neutralized. We have published the spectroscopic work in two papers in the Journal of Colloid and Interface Science [1, 2], and will soon submit at third manuscript to Geochemical Transactions [3] combining the sorption and spectroscopic data with a mechanistic complexation model. Early in the study we learned that strontium sorption was independent of temperature (25 to 80 C). All subsequent work was conducted at room temperature.
Date:
March 1, 2000
Creator:
Carroll, S A & O'Day, P A
Object Type:
Article
System:
The UNT Digital Library
New Mid-IR Lasers Based on Rare-Earth-Doped Sulfide and Chloride Materials
Applications in remote-sensing and military countermeasures have driven a need for compact, solid-state mid-IR lasers. Due to multi-phonon quenching, non-traditional hosts are needed to extend current solid-state, room-temperature lasing capabilities beyond {approx} 4 {micro}m. Traditional oxide and fluoride hosts have effective phonon energies in the neighborhood of 1000 cm{sup -1} and 500 cm{sup -1}, respectively. These phonons can effectively quench radiation above 2 and 4 {micro}m, respectively. Materials with lower effective phonon energies such as sulfides and chlorides are the logical candidates for mid-IR (4-10 {micro}m) operation. In this report, laser action is demonstrated in two such hosts, CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}. The CaGa{sub 2}S{sub 4}:Dy{sup 3+} laser operating at 4.3 {micro}m represents the first sulfide laser operating beyond 2 {micro}m. The KPb{sub 2}Cl{sub 5}:Dy{sup 3+} laser operating at 2.4 {micro}m represents the first operation of a chloride-host laser in ambient conditions. Laser action is also reported for CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 2.4 {micro}m, CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 1.4 {micro}m, and KPb{sub 2}Cl{sub 5}:Nd{sup 3+} at 1.06 {micro}m. Both host materials have been fully characterized, including lifetimes, absorption and emission cross sections, radiative branching ratios, and radiative quantum efficiencies. Radiative branching ratios and radiative quantum …
Date:
September 1, 2000
Creator:
Nostrand, M
Object Type:
Report
System:
The UNT Digital Library
Debt and Development in Poor Countries:Rethinking Policy Responses
This report discusses how debts fits into the broader development picture including, defining the circumstances that lead to heavy indebtedness, drawing specific lessons from the Latin American and African cases, and evaluating the success and failure of earlier debt policy responses.
Date:
March 1, 2000
Creator:
Hornbeck, J. F.
Object Type:
Report
System:
The UNT Digital Library
Livermore Site Southeast Corner VOC Source Study-B419/511 Area
A passive soil gas study was conducted in the Building 419/511 (B419/511) area to screen for volatile organic compound (VOC) source locations in June 2000. Results of this study are presented with the most recent ground water contaminant plume maps, as well as the historic surface vapor analysis and soil contamination maps. Limited analytical data exists for the area directly north and west of B419. Because of extensive VOCs in ground water directly under the north end of B419, it is important to determine if the contaminant plume migrated to that location or if it originated from activities at B419. The results of this and previous investigations will aid in defining (1) the source(s) of contamination, (2) the placement and management of future remediation wells, and (3) remediation strategies. A brief description of the building's function and contamination summary is presented in Section 1.1. Section 1.2 presents the methodology used for the passive soil gas study. Section 1.3 is a discussion of the passive soil gas study and the hydrogeologic analysis. Concluding remarks and recommendations for future source investigations and remediation designs are found in Section 1.4.
Date:
June 1, 2000
Creator:
Krauter, P A; Maley, M P; Aarons, G F & Gregory, S
Object Type:
Report
System:
The UNT Digital Library
Early-time observations of gamma-ray burst error boxes with the Livermore optical transient imaging system
Despite the enormous wealth of gamma-ray burst (GRB) data collected over the past several years the physical mechanism which causes these extremely powerful phenomena is still unknown. Simultaneous and early time optical observations of GRBs will likely make an great contribution t o our understanding. LOTIS is a robotic wide field-of-view telescope dedicated to the search for prompt and early-time optical afterglows from gamma-ray bursts. LOTIS began routine operations in October 1996 and since that time has responded to over 145 gamma-ray burst triggers. Although LOTIS has not yet detected prompt optical emission from a GRB its upper limits have provided constraints on the theoretical emission mechanisms. Super-LOTIS, also a robotic wide field-of-view telescope, can detect emission 100 times fainter than LOTIS is capable of detecting. Routine observations from Steward Observatory's Kitt Peak Station will begin in the immediate future. During engineering test runs under bright skies from the grounds of Lawrence Livermore National Laboratory Super-LOTIS provided its first upper limits on the early-time optical afterglow of GRBs. This dissertation provides a summary of the results from LOTIS and Super-LOTIS through the time of writing. Plans for future studies with both systems are also presented.
Date:
August 1, 2000
Creator:
Williams, G. G.
Object Type:
Report
System:
The UNT Digital Library
Demonstration of jackhammer incorporating depleted uranium
The United States Government currently has an abundance of depleted uranium (DU). This surplus of about 1 billion pounds is the result of an enrichment process using gaseous diffusion to produce enriched and depleted uranium. The enriched uranium has been used primarily for either nuclear weapons for the military or nuclear fuel for the commercial power industry. Most of the depleted uranium remains at the enrichment process plants in the form of depleted uranium hexafluoride (DUF{sub 6}). The Department of Energy (DOE) recently began a study to identify possible commercial applications for the surplus material. One of these potential applications is to use the DU in high-density strikers/hammers in pneumatically driven tools, such as jack hammers and piledrivers to improve their impulse performance. The use of DU could potentially increase tunneling velocity and excavation into target materials with improved efficiency. This report describes the efforts undertaken to analyze the particulars of using DU in two specific striking applications: the jackhammer and chipper tool.
Date:
April 1, 2000
Creator:
Fischer, L E; Hoard, R W; Carter, D L; Saculla, M D & Wilson, G V
Object Type:
Report
System:
The UNT Digital Library
Molecular dynamics simulation of cascade damage in gold
High-energy cascades have been simulated in gold using molecular dynamics with a modified embedded atom method potential. The results show that both vacancy and interstitial clusters form with high probability as a result of intracascade processes. The formation of clusters has been interpreted in terms of the high pressures generated in the core of the cascade during the early stages. We provide evidence that correlation between interstitial and vacancy clustering exists.
Date:
February 1, 2000
Creator:
Alonso, E.; Caturla, M. J.; Tang, M.; Huang, H. & Diaz de la Rubia, T
Object Type:
Article
System:
The UNT Digital Library
Conductor Development for High Field Dipole Magnets
Historically, improvements in dipole magnet performance have been paced by improvements in the superconductor available for use in these magnets. The critical conductor performance parameters for dipole magnets include current density, piece length, effective filament size, and cost. Each of these parameters is important for efficient, cost effective dipoles, with critical current density being perhaps the most important. Several promising magnet designs for the next hadron collider or a muon collider require fields of 12 T or higber, i.e. beyond the reach of NbTi. The conductor options include Nb{sub 3}Sn, Nb{sub 3}Al, or the high temperature superconductors. Although these conductors have the potential to provide the combination of performance and cost required, none of them have been developed sufficiently at this point to satisfy all the requirements. This paper will review the status of each class of advanced conductor and discuss the remaining problems that require solutions before these new conductors can be considered as practical. In particular, the plans for a new program to develop Nb{sub 3}Sn and Nb{sub 3}Al conductors for high energy physics applications will be presented. Also, the development of a multikiloamp Bi-2212 cable for dipole magnet applications will be reported.
Date:
March 1, 2000
Creator:
Scanlan, R. M.; Dietderich, D. R. & Higley, H. C.
Object Type:
Article
System:
The UNT Digital Library
Large Scale Computational Problems in Numerical Optimization
Our work under this support broadly falls into five categories: automatic differentiation, sparsity, constraints, parallel computation, and applications. Automatic Differentiation (AD): We developed strong practical methods for computing sparse Jacobian and Hessian matrices which arise frequently in large scale optimization problems [10,35]. In addition, we developed a novel view of "structure" in applied problems along with AD techniques that allowed for the efficient application of sparse AD techniques to dense, but structured, problems. Our AD work included development of freely available MATLAB AD software. Sparsity: We developed new effective and practical techniques for exploiting sparsity when solving a variety of optimization problems. These problems include: bound constrained problems, robust regression problems, the null space problem, and sparse orthogonal factorization. Our sparsity work included development of freely available and published software [38,39]. Constraints: Effectively handling constraints in large scale optimization remains a challenge. We developed a number of new approaches to constrained problems with emphasis on trust region methodologies. Parallel Computation: Our work included the development of specifically parallel techniques for the linear algebra tasks underpinning optimization algorithms. Our work contributed to the nonlinear least-squares problem, nonlinear equations, triangular systems, orthogonalization, and linear programming. Applications: Our optimization work is broadly applicable …
Date:
July 1, 2000
Creator:
coleman, thomas f.
Object Type:
Report
System:
The UNT Digital Library
Coupling Matrices in AGS with different types of partial snakes
N/A
Date:
November 1, 2000
Creator:
D., Courant E.
Object Type:
Report
System:
The UNT Digital Library
Spin Tracking with Real Siberian Snakes in RHIC
N/A
Date:
March 1, 2000
Creator:
Xiao, M. & Katayama, T.
Object Type:
Report
System:
The UNT Digital Library
Persistence and transport potential of chemicals in a multimedia environment
Persistence in the environment and potential for long-range transport are related since time in the environment is required for transport. A persistent chemical will travel longer distances than a reactive chemical that shares similar chemical properties. Scheringer (1997) has demonstrated the correlation between persistence and transport distance for different organic chemicals. However, this correlation is not sufficiently robust to predict one property from the other. Specific chemicals that are persistent mayor may not exhibit long-range transport potential. Persistence and long-range transport also present different societal concerns. Persistence concerns relate to the undesired possibility that chemicals produced and used now may somehow negatively affect future generations. Long-range transport concerns relate to the undesired presence of chemicals in areas where these compounds have not been used. Environmental policy decisions can be based on either or both considerations depending on the aim of the regulatory program. In this chapter, definitions and methods for quantifying persistence and transport potential of organic chemicals are proposed which will assist in the development of sound regulatory frameworks.
Date:
February 1, 2000
Creator:
van de Meent, D.; McKone, T.E.; Parkerton, T.; Matthies, M.; Scheringer, M.; Wania, F. et al.
Object Type:
Book
System:
The UNT Digital Library
The RCMS dipole aperture and beam pipe
N/A
Date:
January 1, 2000
Creator:
S., Peggs; Meng, W.; Roser, T.; Tsoupas, N. & Tuozzolo, J.
Object Type:
Report
System:
The UNT Digital Library