Hydrogen Storage Properties of the Tetrahydrofuran Treated Magnesium (open access)

Hydrogen Storage Properties of the Tetrahydrofuran Treated Magnesium

The electronic structure, crystalline feature and morphology of the tetrahydrofuran (THF) treated magnesium, along with its hydriding and dehydriding properties have been investigated. The THF treated magnesium absorbs 6.3 wt per cent hydrogen at 723K and 3.5 MPa. After hydrogenation, in addition to the expected MgH2, a new less-stable hydride phase appears at 673K, but not at a lower temperature. Desorption produces 5.5 wt per cent hydrogen at 723K against a back pressure of 1.3 Pa after 20 cycles of hydriding-dehydriding. The THF treatment improves the kinetics of hydrogen absorption and desorption significantly. From 723K to 623K, the THF treated Mg demonstrates acceptable reaction rates. XPS studies show that tetrahydrofuran treatment causes the electronic energy state of the magnesium surface atoms to change, but the XRD studies show the crystal structure remains unchanged. Metallographic observation of the bulk hydrides of THF treated magnesium reveal they are poly-crystalline wi th the wide-spreading slip bands and twins within the crystals, indicating the phase transformation upon hydriding causes serious stress and distortion. It appears this microstructural deformation explains the much higher energy requirements (higher pressure and temperature) for magnesium hydrogenation than the simple lattice expansion that accompany hydrogen uptake for LaNi5 and FeTi.
Date: May 25, 2004
Creator: AU, MING
Object Type: Article
System: The UNT Digital Library
LSST data pipeline prototyping plans and strategy (open access)

LSST data pipeline prototyping plans and strategy

In this document we describe our approach and strategy for building the prototype for the image-stream analysis data pipeline. We start by describing the main research areas upon which we will be focusing; we then describe our plans on how to carry these research ideas to implement the data pipeline.
Date: May 27, 2004
Creator: Abdulla, G. M.; Brase, J.; Cook, K. & Miller, M.
Object Type: Report
System: The UNT Digital Library
Scientific Report (2002-2004) (open access)

Scientific Report (2002-2004)

OAK-B135 An overview of our work as well as two recent publications are contained in this scientific report. The work reported here revolves around the discovery of new coherent nonlinear kinetic waves in laser produced plasmas, we call KEEN waves (kinetic, electrostatic electron nonlinear waves), and optical mixing experiments on the Imega laser system at LLE with blue-green light for the exploration of ways to suppress parametric instabilities in long scale length, long pulsewidth laser-plasmas such as those which will be found on NIF or LMJ.
Date: May 11, 2004
Creator: Afeyan, Bedros
Object Type: Report
System: The UNT Digital Library
ORNL Cray X1 Evaluation Status Report (open access)

ORNL Cray X1 Evaluation Status Report

On August 15, 2002 the Department of Energy (DOE) selected the Center for Computational Sciences (CCS) at Oak Ridge National Laboratory (ORNL) to deploy a new scalable vector supercomputer architecture for solving important scientific problems in climate, fusion, biology, nanoscale materials and astrophysics. ''This program is one of the first steps in an initiative designed to provide U.S. scientists with the computational power that is essential to 21st century scientific leadership,'' said Dr. Raymond L. Orbach, director of the department's Office of Science. In FY03, CCS procured a 256-processor Cray X1 to evaluate the processors, memory subsystem, scalability of the architecture, software environment and to predict the expected sustained performance on key DOE applications codes. The results of the micro-benchmarks and kernel bench marks show the architecture of the Cray X1 to be exceptionally fast for most operations. The best results are shown on large problems, where it is not possible to fit the entire problem into the cache of the processors. These large problems are exactly the types of problems that are important for the DOE and ultra-scale simulation. Application performance is found to be markedly improved by this architecture: - Large-scale simulations of high-temperature superconductors run 25 times …
Date: May 1, 2004
Creator: Agarwal, P. K.; Alexander, R. A.; Apra, E.; Balay, S.; Bland, A. S.; Colgan, J. et al.
Object Type: Article
System: The UNT Digital Library
Development of a Novel Catalyst for NO Decomposition (open access)

Development of a Novel Catalyst for NO Decomposition

Air pollution arising from the emission of nitrogen oxides as a result of combustion taking place in boilers, furnaces and engines, has increasingly been recognized as a problem. New methods to remove NO{sub x} emissions significantly and economically must be developed. The current technology for post-combustion removal of NO is the selective catalytic reduction (SCR) of NO by ammonia or possibly by a hydrocarbon such as methane. The catalytic decomposition of NO to give N{sub 2} will be preferable to the SCR process because it will eliminate the costs and operating problems associated with the use of an external reducing species. The most promising decomposition catalysts are transition metal (especially copper)-exchanged zeolites, perovskites, and noble metals supported on metal oxides such as alumina, silica, and ceria. The main shortcoming of the noble metal reducible oxide (NMRO) catalysts is that they are prone to deactivation by oxygen. It has been reported that catalysts containing tin oxide show oxygen adsorption behavior that may involve hydroxyl groups attached to the tin oxide. This is different than that observed with other noble metal-metal oxide combinations, which have the oxygen adsorbing on the noble metal and subsequently spilling over to the metal oxide. This observation …
Date: May 1, 2004
Creator: Akyurtlu, Ates & Akyurtlu, Jale F.
Object Type: Report
System: The UNT Digital Library
Microchannel Cooled Edge Cladding to Establish an Adiabatic Boundary Condition in a Slab Laser (open access)

Microchannel Cooled Edge Cladding to Establish an Adiabatic Boundary Condition in a Slab Laser

The present invention provides an edge cladding for a slab laser, the edge cladding comprising a cooling channel system therein.
Date: May 18, 2004
Creator: Albrecht, Georg F.; Beach, Raymond J. & Solarz, Richard W.
Object Type: Text
System: The UNT Digital Library
Supernova/Acceleration Probe: A Satellite Experiment to Study the Nature of the Dark Energy (open access)

Supernova/Acceleration Probe: A Satellite Experiment to Study the Nature of the Dark Energy

The Supernova/Acceleration Probe (SNAP) is a proposed space-based experiment designed to study the dark energy and alternative explanations of the acceleration of the Universes expansion by performing a series of complementary systematics-controlled astrophysical measurements. We here describe a self-consistent reference mission design that can accomplish this goal with the two leading measurement approaches being the Type Ia supernova Hubble diagram and a wide-area weak gravitational lensing survey. This design has been optimized to first order and is now under study for further modification and optimization. A 2-m three-mirror anastigmat wide-field telescope feeds a focal plane consisting of a 0.7 square-degree imager tiled with equal areas of optical CCDs and near infrared sensors, and a high efficiency low-resolution integral field spectrograph. The instrumentation suite provides simultaneous discovery and light-curve measurements of supernovae and then can target individual objects for detailed spectral characterization. The SNAP mission will discover thousands of Type Ia supernovae out to z = 3 and will obtain high-signal-to-noise calibrated light-curves and spectra for a subset of > 2000 supernovae at redshifts between z = 0.1 and 1.7 in a northern field and in a southern field. A wide-field survey covering one thousand square degrees in both northern and …
Date: May 12, 2004
Creator: Aldering, G.; Althouse, W.; Amanullah, R.; Annis, J.; Astier, P.; Baltay, C. et al.
Object Type: Article
System: The UNT Digital Library
Radiation dose measurements of the insertion devices using radiachromic film dosimeters. (open access)

Radiation dose measurements of the insertion devices using radiachromic film dosimeters.

The Advanced Photon Source (APS) uses Nd-Fe-B permanent magnets in the insertion devices to produce x-rays for scientific research [1,2]. Earlier investigations have exhibited varying degrees of demagnetization of these magnets [3] due to irradiation from electron beams [4,5,6], {sup 60}Co {gamma}-rays [5], and high-energy neutrons [7,8]. Radiation-induced demagnetization has been observed in the APS insertion devices [9] and was first measured in December of 2001. Partial demagnetization has also been observed in insertion devices at the European Synchrotron Radiation Facility (ESRF) [4,6], where Nd-Fe-B permanent magnets are also used. Growing concern for the lifetime of APS insertion devices, as well as the permanent magnets that will be used in next-generation, high-power light sources, like the FEL [10,11], resulted from the partial demagnetization observations made at both facilities. This concern in relation to radiation-induced demagnetization spurred a long-term project to measure and analyze the absorbed doses received by the APS insertion devices. The project required a reliable photon high-dose dosimetry technique capable of measuring absorbed doses greater than 10{sup 6} rad, which was not readily available at the APS. Through a collaboration with the National Institute of Standards and Technology (NIST), one such technique using radiachromic films was considered, tested, …
Date: May 25, 2004
Creator: Alderman, J.; Semones, E. & Job, P. K.
Object Type: Report
System: The UNT Digital Library
Electron Line Broadening in Plasmas: Resolution of the Quantum vs. Semiclassical Calculations Puzzle (open access)

Electron Line Broadening in Plasmas: Resolution of the Quantum vs. Semiclassical Calculations Puzzle

Puzzling discrepancies between on the one hand quantum mechanical (QM) electron impact calculations of isolated ion lines and on the other hand experimental data and nonperturbative semiclassical (SC) calculations are reviewed. The origin of these discrepancies was a standard line-broadening literature estimate of the wavefunction extent. The nonperturbative semiclassical calculations are further improved by dropping the long-range approximation and allowing penetrating collisions. This results in excellent agreement with fully quantal calculations for the case of the BIII 2s-2p line. On the other hand the standard perturbative semiclassical method is inadequate even in this particular example, where perturbation theory is valid. Further, the assumption of neglecting the back-reaction in semiclassical calculations is examined.
Date: May 11, 2004
Creator: Alexiou, S & Lee, R
Object Type: Article
System: The UNT Digital Library
Smart Screening System (S3) In Taconite Processing (open access)

Smart Screening System (S3) In Taconite Processing

The conventional vibrating machines used in processing plants have had undesirable high noise and vibration levels. They also have had unsatisfactorily low screening efficiency, high energy consumption, high maintenance cost, low productivity, and poor worker safety. These conventional vibrating machines have been used in most every processing plant. Most of the current material separation technology uses heavy and inefficient electric motors with an unbalance rotating mass to generate the shaking. In addition to being excessively noisy, inefficient, and high-maintenance, these vibrating machines are often the bottleneck in the entire process. Furthermore, these motors, along with the vibrating machines and supporting structure, shake other machines and structures in the vicinity. The latter increases maintenance costs while reducing worker health and safety. The conventional vibrating fine screens at taconite processing plants have had the same problems as those listed above. This has resulted in lower screening efficiency, higher energy and maintenance cost, and lower productivity and workers safety concerns. The focus of this work is on the design of a high performance screening machine suitable for taconite processing plants. SmartScreens{trademark} technology uses miniaturized motors, based on smart materials, to generate the shaking. The underlying technologies are Energy Flow Control{trademark} and Vibration Control …
Date: May 1, 2004
Creator: Allaei, Daryoush; Mohammed, Asim Syed & Tarnowski, David
Object Type: Report
System: The UNT Digital Library
Vestibule and Cask Preparation Mechanical Handling Calculation (open access)

Vestibule and Cask Preparation Mechanical Handling Calculation

The scope of this document is to develop the size, operational envelopes, and major requirements of the equipment to be used in the vestibule, cask preparation area, and the crane maintenance area of the Fuel Handling Facility. This calculation is intended to support the License Application (LA) submittal of December 2004, in accordance with the directive given by DOE correspondence received on the 27th of January 2004 entitled: ''Authorization for Bechtel SAIC Company L.L.C. to Include a Bare Fuel Handling Facility and Increased Aging Capacity in the License Application, Contract Number DE-AC28-01R W12101'' (Ref. 167124). This correspondence was appended by further correspondence received on the 19th of February 2004 entitled: ''Technical Direction to Bechtel SAIC Company L.L. C. for Surface Facility Improvements, Contract Number DE-AC28-01R W12101; TDL No. 04-024'' (Ref. 16875 1). These documents give the authorization for a Fuel Handling Facility to be included in the baseline. The limitations of this preliminary calculation lie within the assumptions of section 5 , as this calculation is part of an evolutionary design process.
Date: May 26, 2004
Creator: Ambre, N.
Object Type: Report
System: The UNT Digital Library
New Heterogeneous Catalysts for the Selective Reduction of NOx under Lean Conditions. Final Report (open access)

New Heterogeneous Catalysts for the Selective Reduction of NOx under Lean Conditions. Final Report

The original goal of this program was the identification and design of new noble-metal-based catalysts for the selective catalytic reduction of nitric oxide by hydrocarbons under excess oxygen (i.e., ''lean'') conditions (HC-SCR). Work conducted in the first funding cycle of this award (i.e., 1997-2000) was successful in allowing us to develop an understanding of the fundamental surface chemistry taking place during the adsorption and reaction of nitrogen oxides and propylene on the surface of supported noble metal catalysts. Both experimental results collected in our own group as well as molecular simulation results published by Professor Neurock suggested that in order to improve the performance of the Pt catalysts--in terms of the nitrogen selectivity and the temperature window of operation-- it was necessary to introduce a second metal. However, synthesizing such catalysts with the metals of interest (i.e., Pt-Au, Pt-Ru, Pt-Rh, etc.) with some degree of control of the structure and composition of the resulting supported metal particles is in itself a research challenge. Consequently, the bulk of our efforts during the second funding cycle of this award (covered by this report) was shifted to the use of organometallic cluster precursors for the synthesis on novel bimetallic catalysts. During this time …
Date: May 31, 2004
Creator: Amiridis, M. D.
Object Type: Report
System: The UNT Digital Library
Effects of Radiative Recombination and Photon Recycling on Minority Carrier Lifetime in Epitaxial GaINAsSb Lattice-matched to GaSb (open access)

Effects of Radiative Recombination and Photon Recycling on Minority Carrier Lifetime in Epitaxial GaINAsSb Lattice-matched to GaSb

None
Date: May 11, 2004
Creator: Anikeev, S.; Donetsky, D.; Belenky, G.; Luryl, S.; Wang, C. A.; Shiau, D. A. et al.
Object Type: Report
System: The UNT Digital Library
Driving Mechanism of SOL Plasma Flow and Effects on the Divertor Performance in JT-60U (open access)

Driving Mechanism of SOL Plasma Flow and Effects on the Divertor Performance in JT-60U

None
Date: May 17, 2004
Creator: Asakura, N.; Takenaga, H.; Sakurai, S.; Porter, G.; Rognlien, T.; Rensink, M. et al.
Object Type: Article
System: The UNT Digital Library
Research in Hydrogen Passivation of Defects and Impurities in Silicon: Final Subcontract Report, 2 May 2000--2 July 2003 (open access)

Research in Hydrogen Passivation of Defects and Impurities in Silicon: Final Subcontract Report, 2 May 2000--2 July 2003

Our work consists of hydrogenating silicon (Si) samples by different methods such as low-energy implantation, electron cyclotron resonance (ECR) plasma, and thermal diffusion. The samples will be provided through NREL. The experimental work carried out at Penn State involves the study of hydrogen interaction with defects, trapping, migration, and formation of complexes. The principal vehicle for the latter study will be ion implantation, and the intent is to understand mechanisms of defect passivation and activation by hydrogen. The theoretical studies will consist of the calculation of the structure and parameters related to hydrogen diffusion and interactions of hydrogen with transition metal impurities in silicon. Experimental studies will involve measurements of hydrogen and hydrogen-impurity complexes, and diffusion properties of various species of hydrogen in Si. The experimental work at Penn State includes introduction of hydrogen in a variety of photovoltaic Si by ECR plasma, low-energy ion implantation, and thermal diffusion. The specific tasks will be the evaluation of hydrogen interaction with defects engineered by ion implantation; defect passivation, activation, and migration in hydrogenated Si under thermal anneal; and electrical activity of hydrogen-impurity complexes. Electrical characterization will entail I-V and C-V measurements, spreading resistance, and deep-level transient spectroscopy.
Date: May 1, 2004
Creator: Ashok, S.
Object Type: Report
System: The UNT Digital Library
The CMS forward calorimeter prototype design studies and Omega(c)0 search at E781 experiment at Fermilab (open access)

The CMS forward calorimeter prototype design studies and Omega(c)0 search at E781 experiment at Fermilab

In the fit part, the Compact Muon Solenoid (CMS) forward calorimeter design studies are presented. The forward calorimeter consists of quartz fibers embedded in a steel absorber. Radiation damage studies of the quartz fiber and the absorber as well as the results of the first pre-production prototype PPP-I are presented. In the second part, the {Omega}{sub c}{sup 0}search studies at the SELEX (E781) experiment at FermiLab are presented. 107 {+-} 22 {Omega}{sub c}{sup 0} events are observed in three decay modes. The relative branching ratio ({Omega}{sub c}{sup 0} {yields} {Omega}{sup -}{pi}{sup -}{pi}{sup +}{pi}{sup +})/{Beta}({Omega}{sub c}{sup 0} {yields} {Omega}{sup -}{pi}{sup +}) is measured as 2.00 {+-} 0.45(stat) {+-} 0.32(sys).
Date: May 1, 2004
Creator: Ayan, Ahmet Sedat
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Impact of Uranium Levels ON Sludge Batch 2 Simulant Processing (open access)

Impact of Uranium Levels ON Sludge Batch 2 Simulant Processing

The Defense Waste Processing Facility began processing Sludge Batch 2 (SB2) in December of 2001. Since the introduction of the first SRAT batch of SB2, processing issues have been observed in the Sludge Receipt and Adjustment Tank, Slurry Mix Evaporator Melter Feed Tank and the melter. These issues coincided with the start of Batch 209, the first full batch from SB2a5. The issues involved the ability to transfer process slurries and feed the melter, difficulty maintaining heat transfer in the SME, and degradation of the operation of the melter. One of the primary differences between Sludge Batch 2 and the previous Sludge Batches is the increased content of uranium. The Savannah River National Laboratory was requested by DWPF via Technical Task Request HLW/DWPF TTR-02-0035 to determine if the processing issues are related to the elevated levels of uranium in SB21. The work reported here is intended to address only a portion of TTR-0035, specifically the impact of uranium on Sludge Batch 2. This work is governed by a Task Technical and Quality Assurance Plan 2 and an Analytical Study Plan 3. SRNL conducted small-scale tests designed to determine the effect of different levels of uranium on sludge processing at the …
Date: May 1, 2004
Creator: BANNOCHIE, CHRISTOPHERJ.
Object Type: Report
System: The UNT Digital Library
High Level Waste Lag Storage and Feed Blending (open access)

High Level Waste Lag Storage and Feed Blending

SRTC performed small-scale tests to determine the behavior associated with blending streams in the High-level Waste (HLW) Lag Storage and Feed Blending Process System for the Hanford Waste Treatment and Immobilization Plant (WTP). The work reported here was planned and designed in response to the test specification. The Office of River Protection Hanford Waste Treatment and Immobilization Plant consists of three primary facilities: a Pretreatment Facility and two facilities for low-activity and high-level waste vitrification. The Pretreatment Facility contains unit operations which receive waste feed from the Hanford Tank Farms and separate it into two treated waste streams: a low-activity, liquid waste stream stripped of most solids and radioisotopes (processed through the Low-Activity Waste Vitrification Facility) and a high-level waste slurry containing most of the solids and radioisotopes (processed through the High-Level Waste Vitrification Facility). Blending of the later solids a nd radioisotopes streams and their resulting properties is the subject of this report. These mixtures are shown to be unreactive and pumpable by using statistically designed combinations of nonradioactive simulants for the process streams. Properties of the mixtures are also predicted numerically (with the Environmental Simulation Program) and compared with the experimental results. The results did not reveal any …
Date: May 10, 2004
Creator: BARNES, M.J.
Object Type: Report
System: The UNT Digital Library
Gas Turbine Reheat Using in Situ Combustion: Final Report, Draft (open access)

Gas Turbine Reheat Using in Situ Combustion: Final Report, Draft

In situ reheat is an alternative to traditional gas turbine reheat design in which fuel is fed through airfoils rather than in a bulky discrete combustor separating HP and LP turbines. The goals are to achieve increased power output and/or efficiency without higher emissions. In this program the scientific basis for achieving burnout with low emissions has been explored. In Task 1, Blade Path Aerodynamics, design options were evaluated using CFD in terms of burnout, increase of power output, and possible hot streaking. It was concluded that Vane 1 injection in a conventional 4-stage turbine was preferred. Vane 2 injection after vane 1 injection was possible, but of marginal benefit. In Task 2, Combustion and Emissions, detailed chemical kinetics modeling, validated by Task 3, Sub-Scale Testing, experiments, resulted in the same conclusions, with the added conclusion that some increase in emissions was expected. In Task 4, Conceptual Design and Development Plan, Siemens Westinghouse power cycle analysis software was used to evaluate alternative in situ reheat design options. Only single stage reheat, via vane 1, was found to have merit, consistent with prior Tasks. Unifying the results of all the tasks, a conceptual design for single stage reheat utilizing 24 holes, …
Date: May 17, 2004
Creator: Bachovchin, D. M.; Lippert, T. E.; Newby, R. A. & Cizmas, P. G. A.
Object Type: Report
System: The UNT Digital Library
Estimation of Particle Flux and Remineralization Rate from Radioactive Disequilibrium (open access)

Estimation of Particle Flux and Remineralization Rate from Radioactive Disequilibrium

Reactive radionuclides, such as the thorium isotopes, show measurable deficiencies in the oceanic water column because of their removal by chemical scavenging due to the particle flux. Measurement of the deficiency, coupled with measurement of the radionuclide concentration in particles, allows a determination of the effective particle sinking velocity. Results to date suggest that the effective particle sinking velocity is remarkably invariant with depth. This leads to the tentative suggestion that POC concentration profiles may, to a good approximation, be used directly to determine length scales for the remineralization of sinking organic matter. Further measurements are in progress to test this idea and to evaluate its limitations. Knowledge of the remineralization length scale is essential to an evaluation of the efficiency of the biological pump as a means for deep sequestering of carbon in the ocean.
Date: May 24, 2004
Creator: Bacon, Michael P. & Francois, Roger
Object Type: Report
System: The UNT Digital Library
Laser Heated High Density Fluids Probed by Coherent Anti-Stokes Raman Spectroscopy (open access)

Laser Heated High Density Fluids Probed by Coherent Anti-Stokes Raman Spectroscopy

We describe an integrated experimental method of Coherent Antistoke Raman Spectroscopy (CARS), laser-heating and diamond-anvil cell (DAC) technologies probing molecular vibrations of transparent molecular fluids at the pressure-temperature conditions of energetic detonation and Giant planetary interiors. In this method, we use a microfabricated metal toroid to conductively heat a surrounding transparent sample in a DAC, using a CW Nd:YLF laser. The laser is operated at a TEM{sub 01*} mode to match the shape of the toroid and thus produces a uniform heating area. The CARS probe utilizes two pulsed lasers with similar cavity lengths: a commercial narrow-band mode-locked Q-switched Nd:YAG laser and a home-built broadband dye laser. A strong CARS signal is then produced from the sample in the central region of laser-heated metal toroid where the two laser pulses spatially and temporally coincide. In this paper, we will demonstrate that this technique is capable of producing high quality vibrational spectra from nitrogen fluid above 2000 K and 13 GPa, where the application of spontaneous Raman spectroscopy is limited because of intense thermal radiation.
Date: May 19, 2004
Creator: Baer, B J & Yoo, C
Object Type: Article
System: The UNT Digital Library
An efficient parallel termination detection algorithm (open access)

An efficient parallel termination detection algorithm

Information local to any one processor is insufficient to monitor the overall progress of most distributed computations. Typically, a second distributed computation for detecting termination of the main computation is necessary. In order to be a useful computational tool, the termination detection routine must operate concurrently with the main computation, adding minimal overhead, and it must promptly and correctly detect termination when it occurs. In this paper, we present a new algorithm for detecting the termination of a parallel computation on distributed-memory MIMD computers that satisfies all of those criteria. A variety of termination detection algorithms have been devised. Of these, the algorithm presented by Sinha, Kale, and Ramkumar (henceforth, the SKR algorithm) is unique in its ability to adapt to the load conditions of the system on which it runs, thereby minimizing the impact of termination detection on performance. Because their algorithm also detects termination quickly, we consider it to be the most efficient practical algorithm presently available. The termination detection algorithm presented here was developed for use in the PMESC programming library for distributed-memory MIMD computers. Like the SKR algorithm, our algorithm adapts to system loads and imposes little overhead. Also like the SKR algorithm, ours is tree-based, …
Date: May 27, 2004
Creator: Baker, A H; Crivelli, S & Jessup, E R
Object Type: Article
System: The UNT Digital Library
On improving linear solver performance: a block variant of GMRES (open access)

On improving linear solver performance: a block variant of GMRES

The increasing gap between processor performance and memory access time warrants the re-examination of data movement in iterative linear solver algorithms. For this reason, we explore and establish the feasibility of modifying a standard iterative linear solver algorithm in a manner that reduces the movement of data through memory. In particular, we present an alternative to the restarted GMRES algorithm for solving a single right-hand side linear system Ax = b based on solving the block linear system AX = B. Algorithm performance, i.e. time to solution, is improved by using the matrix A in operations on groups of vectors. Experimental results demonstrate the importance of implementation choices on data movement as well as the effectiveness of the new method on a variety of problems from different application areas.
Date: May 10, 2004
Creator: Baker, A H; Dennis, J M & Jessup, E R
Object Type: Article
System: The UNT Digital Library