skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Final Report - Subcontract B623760

Abstract

During my visit to LLNL during July 17{27, 2017, I worked on linear system solvers. The two level hierarchical solver that initiated our study was developed to solve linear systems arising from hp adaptive finite element calculations, and is implemented in the PLTMG software package, version 12. This preconditioner typically requires 3-20% of the space used by the stiffness matrix for higher order elements. It has multigrid like convergence rates for a wide variety of PDEs (self-adjoint positive de nite elliptic equations, convection dominated convection-diffusion equations, and highly indefinite Helmholtz equations, among others). The convergence rate is not independent of the polynomial degree p as p ! 1, but but remains strong for p 9, which is the highest polynomial degree allowed in PLTMG, due to limitations of the numerical quadrature rules implemented in the software package. A more complete description of the method and some numerical experiments illustrating its effectiveness appear in. Like traditional geometric multilevel methods, this scheme relies on knowledge of the underlying finite element space in order to construct the smoother and the coarse grid correction.

Authors:
 [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1410786
Report Number(s):
LLNL-SR-742143
DOE Contract Number:
AC52-07NA27344
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING

Citation Formats

Bank, R. Final Report - Subcontract B623760. United States: N. p., 2017. Web. doi:10.2172/1410786.
Bank, R. Final Report - Subcontract B623760. United States. doi:10.2172/1410786.
Bank, R. 2017. "Final Report - Subcontract B623760". United States. doi:10.2172/1410786. https://www.osti.gov/servlets/purl/1410786.
@article{osti_1410786,
title = {Final Report - Subcontract B623760},
author = {Bank, R.},
abstractNote = {During my visit to LLNL during July 17{27, 2017, I worked on linear system solvers. The two level hierarchical solver that initiated our study was developed to solve linear systems arising from hp adaptive finite element calculations, and is implemented in the PLTMG software package, version 12. This preconditioner typically requires 3-20% of the space used by the stiffness matrix for higher order elements. It has multigrid like convergence rates for a wide variety of PDEs (self-adjoint positive de nite elliptic equations, convection dominated convection-diffusion equations, and highly indefinite Helmholtz equations, among others). The convergence rate is not independent of the polynomial degree p as p ! 1, but but remains strong for p 9, which is the highest polynomial degree allowed in PLTMG, due to limitations of the numerical quadrature rules implemented in the software package. A more complete description of the method and some numerical experiments illustrating its effectiveness appear in. Like traditional geometric multilevel methods, this scheme relies on knowledge of the underlying finite element space in order to construct the smoother and the coarse grid correction.},
doi = {10.2172/1410786},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Technical Report:

Save / Share:
  • The Fuller Company conducted tests to determine the feasibility of conveying Kerr-McGee ash concentrate (KMAC) by two different methods: a Fuller-Kinyon pump conveying system and a blowtank pneumatic transport system. The Fuller-Kinyon tests showed that a 1500-ft/min conveying velocity satisfied a wide range of KMAC flow conditions. No conveying problems occurred in either system at temperatures below 550/sup 0/F at this velocity. Also, no appreciable KMAC attrition was noted. Thus, technically, either system can convey KMAC satisfactorily. Additional studies conducted independently by GKT to compare the economics and on-stream reliability of both methods showed that the Fuller-Kinyon pump is moremore » reliable and has a lower total cost than the blowtank system. Based on these results, ICRC included the Fuller-Kinyon pump conveying system in its Baseline Design for the SRC-I Demonstration Plant. 6 references, 15 figures, 9 tables.« less
  • Currently, interior permanent magnet (IPM) motors with rare-earth (RE) magnets are almost universally used for hybrid and electric vehicles (EVs) because of their superior properties, particularly power density. However, there is now a distinct possibility of limited supply or very high cost of RE magnets that could make IPM motors unavailable or too expensive. Because development of electric motors is a critical part of the U.S. Department of Energy (DOE) Advanced Power Electronics and Motors activity, DOE needs to determine which options should be investigated and what barriers should be addressed. Therefore, in order to provide a basis for decidingmore » which research topics should be pursued, an assessment of various motor technologies was conducted to determine which, if any, is potentially capable of meeting FreedomCAR 2015 and 2020 targets. Highest priority was given to IPM, surface mounted permanent magnet (SPM), induction, and switched reluctance (SR) motors. Also of interest, but with lesser emphasis, were wheel motors, multiple-rotor motors, motors with external excitation, and several others that emerged from the assessment. Cost and power density (from a design perspective, the power density criterion translates to torque density) are emerging as the two most important properties of motors for traction drives in hybrid and EVs, although efficiency and specific power also are very important. The primary approach for this assessment involved interviews with original equipment manufacturers (OEMs), their suppliers, and other technical experts. For each technology, the following issues were discussed: (1) The current state-of-the-art performance and cost; (2) Recent trends in the technology; (3) Inherent characteristics of the motor - which ones limit the ability of the technology to meet the targets and which ones aid in meeting the target; (4) What research and development (R&D) would be needed to meet the targets; and (5) The potential for the technology to meet the targets. The interviews were supplemented with information from past Oak Ridge National Laboratory (ORNL) reports, previous assessments that were conducted in 2004, and literature on magnet technology. The results of the assessment validated the DOE strategy involving three parallel paths: (1) there is enough of a possibility that RE magnets will continue to be available, either from sources outside China or from increased production in China, that development of IPM motors using RE magnets should be continued with emphasis on meeting the cost target. (2) yet the possibility that RE magnets may become unavailable or too expensive justifies efforts to develop innovative designs for permanent magnet (PM) motors that do not use RE magnets. Possible other magnets that may be substituted for RE magnets include samarium-cobalt (Sm-Co), Alnico, and ferrites. Alternatively, efforts to develop motors that do not use PMs but offer attributes similar to IPM motors also are encouraged. (3) New magnet materials using new alloys or processing techniques that would be less expensive or have comparable or superior properties to existing materials should be developed if possible. IPM motors are by far the most popular choice for hybrid and EVs because of their high power density, specific power, and constant power-speed ratio (CPSR). Performance of these motors is optimized when the strongest possible magnets - i.e., RE neodymium-iron-boron (NdFeB) magnets - are used.« less
  • This report describes work performed during the past year by The University of Toledo photovoltaics group. Researchers continued to develop rf sputtering for CdS/CdTe thin-film solar cells and to optimize the post-deposition process steps to match the characteristics of the sputtering process. During the fourth phase of the present contract, we focused on determining factors that limit the efficiency in our ''all-sputtered'' thin-film CdTe solar cells on soda-lime glass. These issues include controlling CdS/CdTe interdiffusion, understanding the properties of the CdS{sub x}Te{sub 1-x} alloy, optimizing process conditions for CdCl{sub 2} treatments, manipulating the influence of ion bombardment during rf sputtering,more » and understanding the role of copper in quenching photoluminescence and carrier lifetimes in CdTe. To better understand the important CdS/CdTe interdiffusion process, we have continued our collaboration with the University at Buffalo and Brookhaven National Synchrotron Light Source in measurements using grazing-incidence X-rays. Interdiffusion results in the formation of the ternary alloy material CdS{sub x}Te{sub 1-x} at or near the heterojunction, where its properties are critical to the operation of the solar cell. We have placed significant effort on characterizing this alloy, an effort begun in the last phase. A complete set of films spanning the alloy range, prepared by pulsed-laser deposition, has now been characterized by wavelength dispersive X-ray spectroscopy and optical absorption at NREL; by Raman scattering, X-ray diffraction, and electrical measurements in our lab; and by spectroscopic ellipsometry at Brooklyn College. We continued to participate in cooperative activity with the CdTe National Team. We prepared a series of depositions on borosilicate glass substrates having doped SnO{sub 2} layers coated with TiO{sub 2} (prepared by the University of South Florida and Harvard) and similar substrates having a resistive SnO{sub 2} layer on the doped tin oxide (fabricated by Golden Photon). The Golden Photon high-resistivity SnO{sub 2} structure yielded excellent cell performance.« less
  • The National Ignition Facility (NIF), a 1.8 MJ, 192 laser beam facility, will have anticipated fusion yields of up to 20 MJ from D-T pellets encased in a gold hohlraum target. The energy emitted from the target in the form of x rays, neutrons, target debris kinetic energy, and target shrapnel will be contained in a 5 m. radius spherical target chamber. Various diagnostics will be stationed around the target at varying distances from the target. During each shot, the target will emit x rays that will vaporize nearby target facing surfaces including those of the diagnostics, the target positioner,more » and other chamber structures. This ablated vapor will be transported throughout the chamber, and will eventually condense and deposit on surfaces in the chamber, including the final optics debris shields. The research at the University of California at Berkeley relates primarily to the NIF chamber dynamics. The key design issues are the ablation of the chamber structures, transport of the vapor through the chamber and the condensation or deposition processes of those vaporized materials. An understanding of these processes is essential in developing a concept for protecting the final optics debris shields from an excessive coating (> 10 {Angstrom}) of target debris and ablated material, thereby prolonging their lifetime between change- outs. At Berkeley, we have studied the physical issues of the ablation process and the effects of varying materials, the condensation process of the vaporized material, and design schemes that can lower the threat posed to the debris shields by these processes. In addition to the work described briefly above, we performed extensive analysis of the target-chamber thermal response to in- chamber CO{sub 2} Cleaning and of work performed to model the behavior of silica vapor. The work completed this year has been published in several papers and a dissertation [1-6]. This report provides a summary of the work completed this year, as well as copies fo presentation materials that have not been published elsewhere. In particular, the Appendix contains copies of presentations made on CO{sub 2} cleaning that are not available elsewhere.« less