155 Matching Results

Search Results

Applications of the 3-D Deterministic Transport Attila{reg_sign} for Core Safety Analysis

Description: An LDRD (Laboratory Directed Research and Development) project is ongoing at the Idaho National Engineering and Environmental Laboratory (INEEL) for applying the three-dimensional multi-group deterministic neutron transport code (Attila{reg_sign}) to criticality, flux and depletion calculations of the Advanced Test Reactor (ATR). This paper discusses the model development, capabilities of Attila, generation of the cross-section libraries, and comparisons to an ATR MCNP model and future.
Date: October 6, 2004
Creator: Lucas, D.S.; Gougar, D.; Roth, P.A.; Wareing, T.; Failla, G.; McGhee, J. et al.
Partner: UNT Libraries Government Documents Department

An Evaluation of Neutron Energy Spectrum Effects in Iron Based on Molecular Dynamics Displacement Cascade Simulations

Description: The results of molecular dynamics (MD) displacement cascade simulations in bcc iron have been used to obtain effective cross sections for two measures of primary damage production: (1) the number of surviving point defects expressed as a fraction of the displacements calculated using the standard secondary displacement model of Norgett, Robinson, and Torrens (NRT), and (2) the fraction of the surviving interstitials contained in clusters that formed during the cascade event. Primary knockon atom spectra for iron obtained from the SPECTER code have been used to weight these MD-based damage production cross sections in order to obtain spectrally-averaged values for several locations in commercial fission reactors and materials test reactors. An evaluation of these results indicates that neutron energy spectrum differences between the various enviromnents do not lead to significant differences between the average primary damage formation parameters. In particular, the defect production cross sections obtained for PWR and BWR neutron spectra were not significantly different. The variation of the defect production cross sections as a function of depth into the reactor pressure vessel wall is used as a sample application of the cross sections. A slight difference between the attenuation behavior of the PWR and BWR was noted; this difference could be explained by a subtle difference in the energy dependence of the neutron spectra. Overall, the simulations support the continued use of dpa as a damage correlation parameter.
Date: June 16, 1998
Creator: Stoller, R.E. & Greenwood, L.R.
Partner: UNT Libraries Government Documents Department

Modeling Manufacturing Processes to Mitigate Technological Risk

Description: An economic model is a tool for determining the justifiable cost of new sensors and subsystems with respect to value and operation. This process balances the R and D costs against the expense of maintaining current operations and allows for a method to calculate economic indices of performance that can be used as control points in deciding whether to continue development or suspend actions. The model can also be used as an integral part of an overall control loop utilizing real-time process data from the sensor groups to make production decisions (stop production and repair machine, continue and warn of anticipated problems, queue for repairs, etc.). This model has been successfully used and deployed in the CAFE Project. The economic model was one of seven (see Fig. 1) elements critical in developing an investment strategy. It has been successfully used in guiding the R and D activities on the CAFE Project, suspending activities on three new sensor technologies, and continuing development o f two others. The model has also been used to justify the development of a new prognostic approach for diagnosing machine health using COTS equipment and a new algorithmic approach. maintaining current operations and allows for a method to calculate economic indices of performance that can be used as control points in deciding whether to continue development or suspend actions. The model can also be used as an integral part of an overall control loop utilizing real-time process data from the sensor groups to make production decisions (stop production and repair machine, continue and warn of anticipated problems, queue for repairs, etc.).
Date: October 24, 1999
Creator: Allgood, G.O. & Manges, W.W.
Partner: UNT Libraries Government Documents Department

Microwave and Millimeter Wave Forward Modeling Results from the 2004 North Slope of Alaska Arctic Winter Radiometric Experiment

Description: The 2004 Arctic Winter Radiometric Experiment was conducted at the North Slope of Alaska (NSA) Atmospheric Radiation Measurement (ARM) Program field site near Barrow, Alaska from March 9 to April 9, 2004. The goals of the experiment were: to study the microwave and millimeter wave radiometric response to water vapor and clouds during cold and dry conditions; to obtain data for forward model studies at frequencies ranging from 22.235 to 400 GHz, to demonstrate new Environmental Technology Laboratory's (ETL) radiometric receiver and calibration technology and to compare both radiometric and in situ measurements of water vapor.
Date: March 18, 2005
Creator: Westwater, E. R.; Cimini, D.; Klein, M.; Leuski, V.; Mattioli, V.; Gasiewski, A. J. et al.
Partner: UNT Libraries Government Documents Department

Technologies Recently Available for Licensing - 1999

Description: An NREL Technology Transfer fact sheet describing four technologies that are available for licensing: steel weld weakness detection, cadmium telluride solar cell enhancement, HOMER model for choosing optimal electrical systems for remote areas, and inner-flame matrix burner.
Date: September 7, 1999
Creator: Brown, H. & Touryan, K.
Partner: UNT Libraries Government Documents Department

Optimization of processing and modeling issues for thin film solar cell devices: Final report, February 3, 1997--September 1, 1998

Description: This final report describes results achieved under a 20-month NREL subcontract to develop and understand thin-film solar cell technology associated to CuInSe{sub 2} and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE's long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development and improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to device structure and module encapsulation.
Date: February 28, 2000
Creator: Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Hegedus, S. S. & McCandless, B. E.
Partner: UNT Libraries Government Documents Department

Performance and Modeling of Amorphous Silicon Photovoltaics for Building-Integrated Applications (Preprint prepared for Solar 99)

Description: Amorphous silicon photovoltaic (PV) modules offer several advantages for building-integrated applications. The material can be deposited on glass or flexible substrates, which allows for products like roofing shingles and integrated PV/building glass. The material also has a uniform surface, which is ideal for many architectural applications. Amorphous silicon modules perform well in warm weather and have a small temperature coefficient for power. Depending on the building load, this may be beneficial when compared to crystalline systems. At the National Renewable Energy Laboratory, we are monitoring the performance of a triple-junction a-Si system. The system consists of 72 roofing shingles mounted directly to simulated roofing structures. This paper examines the performance of the building-integrated amorphous silicon PV system and applicability for covering residential loads. A simple model of system performance is also developed and is presented.
Date: June 7, 1998
Creator: Kroposki, B. & Hansen, R.
Partner: UNT Libraries Government Documents Department

2001 Joint ADVISOR/PSAT Vehicle Systems Modeling User's Conference Proceedings (CD)

Description: The 2001 Joint ADVISOR/PSAT Vehicle Systems Modeling User Conference provided an opportunity for engineers in the automotive industry and the research environment to share their experiences in vehicle systems modeling using ADVISOR and PSAT. ADVISOR and PSAT are vehicle systems modeling tools developed and supported by the National Renewable Energy Laboratory and Argonne National Laboratory respectively with the financial support of the US Department of Energy. During this conference peers presented the results of studies using the simulation tools and improvements that they have made or would like to see in the simulation tools. Focus areas of the presentations included Control Strategy, Model Validation, Optimization and Co-Simulation, Model Development, Applications, and Fuel Cell Vehicle Systems Analysis. Attendees were offered the opportunity to give feedback on future model development plans.
Date: August 1, 2001
Creator: Markel, T.
Partner: UNT Libraries Government Documents Department

Hydrodynamic Simulation of the Columbia River, Hanford Reach, 1940--2004

Description: Many hydrological and biological problems in the Columbia River corridor through the Hanford Site require estimates of river stage (water surface elevation) or river flow and velocity. Systematic collection of river stage data at locations in the Hanford Reach began in 1991, but many environmental projects need river stage information at unmeasured locations or over longer time periods. The Modular Aquatic Simulation System 1D (MASS1), a one-dimensional, unsteady hydrodynamic and water quality model, was used to simulate the Columbia River from Priest Rapids Dam to McNary Dam from 1940 to 2004, providing estimates of water surface elevation, volumetric flow rate, and flow velocity at 161 locations on the Hanford Reach. The primary input data were bathymetric/topographic cross sections of the Columbia River channel, flow rates at Priest Rapids Dam, and stage at McNary Dam. Other inputs included Yakima River and Snake River inflows. Available flow data at a gaging station just below Priest Rapids Dam was mean daily flow from 1940 to 1986 and hourly thereafter. McNary dam was completed in 1957, and hourly stage data are available beginning in 1975. MASS1 was run at an hourly timestep and calibrated and tested using 1991--2004 river stage data from six Hanford Reach locations (areas 100B, 100N, 100D, 100H, 100F, and 300). Manning's roughness coefficient in the Reach above each river recorder location was adjusted using an automated genetic algorithm and gradient search technique in three separate calibrations, corresponding to different data subsets, with minimization of mean absolute error as the objective. The primary calibration was based on 1999, a representative year, and included all locations. The first alternative calibration also used all locations but was limited in time to a high-flow period during spring and early summer of 1997. The second alternative calibration was based on 1999 and included only 300 ...
Date: June 15, 2005
Creator: Waichler, Scott R.; Perkins, William A. & Richmond, Marshall C.
Partner: UNT Libraries Government Documents Department

Electroabsorption and transport measurements and modeling in amorphous-silicon-based solar cells: Phase I technical progress report, 24 March 1998--23 March 1999

Description: This report describes work done by the Syracuse University during Phase 1 of this subcontract. Researchers performed work in the following areas: (1) In ``Electroabsorption measurements and built-in potentials in a-Si:H-based solar cells and devices'', researchers obtained an estimate of Vbi = 1.17 V in cells with a-SiGe:H absorber layers from United Solar Systems Corp. (2) In ``Solar cell modeling employing the AMPS computer program'', researchers began operating a simple AMPS modeling site and explored the effect of conduction bandtail width on Voc computed analytical approximations and the AMPS program. The quantitative differences between the two procedures are discussed. (3) In ``Drift mobility measurements in a-Si:H made with high hydrogen dilution'', researchers measured electron and hole mobilities in several n/i/Ni (semitransparent) cells from Pennsylvania State University with a-Si absorber layers made under maximal hydrogen dilution and found a modest increase in hole mobility in these materials compared to conventional a-Si:H. (4) In ``Electroabsorption spectroscopy in solar cells'', researchers discovered and interpreted an infrared absorption band near 1.0 eV, which they believe is caused by dopants and defects at the n/i interface of cells, and which also has interesting implications for the nature of electroabsorption and for the doping mechanism in n-type material.
Date: December 17, 1999
Creator: Schiff, E. A.; Lyou, J.; Kopidakis, N.; Rao, P. & Yuan, Q.
Partner: UNT Libraries Government Documents Department

Modeling, testing and economic analysis of a wind-electric battery charging station

Description: Battery charging systems are very important in many developing countries where rural families cannot afford a solar-battery home system or other electricity options, but they can afford to own a battery (in some cases more than one battery) and can pay for it to be charged on a regular basis. Because the typical households that use batteries are located far from the grid, small wind battery charging stations can be a cost-competitive options for charging batteries. However, the technical aspects of charging numerous 12-volt batteries on one DC bus with a small permanent magnet alternator wind turbine suggest that a special battery charging station be developed. NREL conducted research on two different types of wind battery charging stations: a system that uses one charge controller for the entire DC bus and charges batteries in parallel strings of four batteries each, and one that uses individual charge controllers for each battery. The authors present test results for both system configurations. In addition, modeling results of steady-state time series simulations of both systems are compared. Although the system with the single charge controller for the entire bus is less expensive, it results in less efficient battery charging. The authors also include in the paper a discussion of control strategies to improve system performance and an economic comparison of the two alternative system architectures.
Date: July 1, 1998
Creator: Gevorgian, V.; Corbus, D.A.; Drouilhet, S.; Holz, R. & Thomas, K.E.
Partner: UNT Libraries Government Documents Department

Modeling utility-scale wind power plants, part 1: Economics

Description: As the worldwide use of wind turbine generators continues to increase in utility-scale applications, it will become increasingly important to assess the economic and reliability impact of these intermittent resources. Although the utility industry in the United States appears to be moving towards a restructured environment, basic economic and reliability issues will continue to be relevant to companies involved with electricity generation. This paper is the first of two that address modeling approaches and results obtained in several case studies and research projects at the National Renewable Energy Laboratory (NREL). This first paper addresses the basic economic issues associated with electricity production from several generators that include large-scale wind power plants. An important part of this discussion is the role of unit commitment and economic dispatch in production-cost models. This paper includes overviews and comparisons of the prevalent production-cost modeling met hods, including several case studies applied to a variety of electric utilities. The second paper discusses various methods of assessing capacity credit and results from several reliability-based studies performed at NREL.
Date: June 29, 2000
Creator: Milligan, M.
Partner: UNT Libraries Government Documents Department

Device physics of thin-film polycrystalline cells and modules: Phase 1 annual report: February 1998--January 1999

Description: This report describes work done by Colorado State University (CSU) during Phase 1 of this subcontract. CSU researchers continued to make basic measurements on CI(G)S and CdTe solar cells fabricated at different labs, to quantitatively deduce the loss mechanisms in these cells, and to make appropriate comparisons that illuminate where progress is being made. Cells evaluated included the new record CIGS cell, CIS cells made with and without CdS, and those made by electrodeposition and electroless growth from solution. Work on the role of impurities focused on sodium in CIS. Cells with varying amounts of sodium added during CIS deposition were fabricated at NREL using four types of substrates. The best performance was achieved with 10{sup {minus}2}--10{sup {minus}1} at% sodium, and the relative merits of proposed mechanisms for the sodium effect were compared. Researchers also worked on the construction and testing of a fine-focused laser-beam apparatus to measure local variations in polycrystalline cell performance. A 1{micro}m spot was achieved, spatial reproducibility in one and two dimensions is less than 1 {micro}m, and photocurrent is reliably measured when the 1{micro}m spot is reduced as low as 1-sun in intensity. In elevated-temperature stress tests, typical CdTe cells held at 100 C under illumination and normal resistive loads for extended periods of time were generally very stable; but those held under reverse or large forward bias and those contacted using larger amounts of copper were somewhat less stable. CdTe cell modeling produced reasonable fits to experimental data, including variations in back-contact barriers. A major challenge being addressed is the photovoltaic response of a single simple-geometry crystallite with realistic grain boundaries.
Date: December 21, 1999
Creator: Sites, J. R.
Partner: UNT Libraries Government Documents Department

HVAC BESTEST: A Procedure for Testing the Ability of Whole-Building Energy Simulation Programs to Model Space Conditioning Equipment: Preprint

Description: Validation of Building Energy Simulation Programs consists of a combination of empirical validation, analytical verification, and comparative analysis techniques (Judkoff 1988). An analytical verification and comparative diagnostic procedure was developed to test the ability of whole-building simulation programs to model the performance of unitary space-cooling equipment that is typically modeled using manufacturer design data presented as empirically derived performance maps. Field trials of the method were conducted by researchers from nations participating in the International Energy Agency (IEA) Solar Heating and Cooling (SHC) Programme Task 22, using a number of detailed hourly simulation programs from Europe and the United States, including: CA-SIS, CLIM2000, PROMETHEUS, TRNSYS-TUD, and two versions of DOE-2.1E. Analytical solutions were also developed for the test cases.
Date: July 3, 2001
Creator: Neymark, J,; Judkoff, R.; Knabe, G.; Le, H.-T.; Durig, M.; Glass, A. et al.
Partner: UNT Libraries Government Documents Department

Atmospheric Pressure Chemical Vapor Deposition of CdTe for High-Efficiency Thin-Film PV Devices; Annual Report, 26 January 1998-25 January 1999

Description: ITN's 3-year project, titled ''Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High-Efficiency Thin-Film Photovoltaic (PV) Devices,'' has the overall objectives of improving thin-film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16%-efficient CdTe PV films, i.e., close-spaced sublimation, but employs forced convection rather than diffusion as a mechanism of mass transport. Tasks of the APCVD program center on demonstrating APCVD of CdTe films, discovering fundamental mass-transport parameters, applying established engineering principles to the deposition of CdTe films, and verifying reactor design principles that could be used to design high-throughput, high-yield manufacturing equipment. Additional tasks relate to improved device measurement and characterization procedures that can lead to a more fundamental understanding of CdTe PV device operation, and ultimately, to higher device conversion efficiency and greater stability. Specifically, under the APCVD program, device analysis goes beyond conventional one-dimensional device characterization and analysis toward two-dimension measurements and modeling. Accomplishments of the first year of the APCVD subcontract include: selection of the Stagnant Flow Reactor design concept for the APCVD reactor, development of a detailed reactor design, performance of detailed numerical calculations simulating reactor performance, fabrication and installation of an APCVD reactor, performance of dry runs to verify reactor performance, performance of one-dimensional modeling of CdTe PV device performance, and development of a detailed plan for quantification of grain-boundary effects in polycrystalline CdTe devices.
Date: September 30, 1999
Creator: Meyers, P. V.; Kee, R.; Wolden, C.; Raja, L.; Kaydanov, V.; Ohno, T. et al.
Partner: UNT Libraries Government Documents Department

Atmospheric pressure chemical vapor deposition of CdTe for high efficiency thin film PV devices: Annual subcontract report, 26 January 1999--25 January 2000

Description: ITN's three year project Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices has the overall objectives of improving thin film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16% efficient CdTe PV films, i.e., close spaced sublimation, but employs forced convection rather than diffusion as a mechanism of mass transport. Tasks of the APCVD program center on demonstration of APCVD of CdTe films, discovery of fundamental mass transport parameters, application of established engineering principles to the deposition of CdTe films, and verification of reactor design principles which could be used to design high throughput, high yield manufacturing equipment. Additional tasks relate to improved device measurement and characterization procedures that can lead to a more fundamental understanding of CdTe PV device operation and ultimately to higher device conversion efficiency and greater stability. Under the APCVD program, device analysis goes beyond conventional one-dimensional device characterization and analysis toward two dimension measurements and modeling. Accomplishments of the second year of the APCVD subcontract include: deposition of the first APCVD CdTe; identification of deficiencies in the first generation APCVD reactor; design, fabrication and testing of a ``simplified'' APCVD reactor; deposition of the first dense, adherent APCVD CdTe films; fabrication of the first APCVD CdTe PV device; modeling effects of CdSTe and SnOx layers; and electrical modeling of grain boundaries.
Date: May 30, 2000
Creator: Meyers, P. V.; Kee, R.; Wolden, C.; Kestner, J.; Raja, L.; Kaydanov, V. et al.
Partner: UNT Libraries Government Documents Department

Modeling, Analysis and Simulation of Multiscale Preferential Flow - 8/05-8/10 - Final Report

Description: The research agenda of this project are: (1) Modeling of preferential transport from mesoscale to macroscale; (2) Modeling of fast flow in narrow fractures in porous media; (3) Pseudo-parabolic Models of Dynamic Capillary Pressure; (4) Adaptive computational upscaling of flow with inertia from porescale to mesoscale; (5) Adaptive modeling of nonlinear coupled systems; and (6) Adaptive modeling and a-posteriori estimators for coupled systems with heterogeneous data.
Date: July 3, 2012
Creator: Showalter, Ralph & Peszynska, Malgorzata
Partner: UNT Libraries Government Documents Department

The Transient Regeneration in the Patchy Cleaning of Rigid Gas Filters--Comparison of Modeling to Experiment

Description: The experimental investigations performed within the scope of the present contribution are carried out in a lab scale filter test rig, which is built according to German VDI guideline 3926. The filter coupon (15 cm diameter) under investigation is mounted parallel to the crude gas channel which enables cross flow filtration as experienced in filter housings. Besides the photometric concentration monitor and the control device, an optical measuring system is mounted on the filter test rig opposite the filter coupon. This measuring system enables the full-field in situ measurement of the dust cake height distribution on the surface of the filter medium. From these measurements, we obtain the overall frequency of regeneration as well as the local frequencies of regeneration and the patch size distribution, as discussed later. In addition, we investigate the influence of the regeneration behavior on the filtration performance (time dependence of filtration cycle times and residual pressure drop) of the filter medium.
Date: September 19, 2002
Creator: Ferer, M.V.; Dittler, A.; Kasper, G. & Smith, D.H.
Partner: UNT Libraries Government Documents Department

The use of streambed temperatures to estimate transmission losses on an experimental channel.

Description: Quantifying channel transmission losses in arid environments is important for a variety of reasons, from engineering design of flood control structures to evaluating recharge. To quantify the losses in an alluvial channel, an experiment was performed on a 2-km reach of an alluvial fan located on the Nevada Test Site. The channel was subjected to three separate flow events. Transmission losses were estimated using standard discharge monitoring and subsurface temperature modeling approach. Four stations were equipped to continuously monitor stage, temperature, and water content. Streambed temperatures measured at 0, 30, 50 and 100 cm depths were used to calibrate VS2DH, a two-dimensional, variably saturated flow model. Average losses based on the difference in flow between each station indicate that 21 percent, 27 percent, and 53 percent of the flow was reduced downgradient of the source. Results from the temperature monitoring identified locations with large thermal gradients, suggesting a conduction-dominated heat transfer on streambed sediments where caliche-cemented surfaces were present. Transmission losses at the lowermost segment corresponded to the smallest thermal gradient, suggesting an advection-dominated heat transfer. Losses predicted by VS2DH are within an order of magnitude of the estimated losses based on discharge measurements. The differences in losses are a result of the spatial extent to which the modeling results are applied and lateral subsurface flow.
Date: October 18, 2001
Creator: Naranjo, Ramon C.; Young, Michael H.; Niswonger, Richard; Miller, Julianne J. & French, Richard H.
Partner: UNT Libraries Government Documents Department

Modeling of Glass Making Processes for Improved Efficiency

Description: The overall goal of this project was to develop a high-temperature melt properties database with sufficient reliability to allow mathematical modeling of glass melting and forming processes for improved product quality, improved efficiency and lessened environmental impact. It was initiated by the United States glass industry through the NSF Industry/University Center for Glass Research (CGR) at Alfred University [1]. Because of their important commercial value, six different types/families of glass were studied: container, float, fiberglass (E- and wool-types), low-expansion borosilicate, and color TV panel glasses. CGR member companies supplied production-quality glass from all six families upon which we measured, as a function of temperature in the molten state, density, surface tension, viscosity, electrical resistivity, infrared transmittance (to determine high temperature radiative conductivity), non-Newtonian flow behavior, and oxygen partial pres sure. With CGR cost sharing, we also studied gas solubility and diffusivity in each of these glasses. Because knowledge of the compositional dependencies of melt viscosity and electrical resistivity are extremely important for glass melting furnace design and operation, these properties were studied more fully. Composition variations were statistically designed for all six types/families of glass. About 140 different glasses were then melted on a laboratory scale and their viscosity and electrical resistivity measured as a function of temperature. The measurements were completed in February 2003 and are reported on here. The next steps will be (1) to statistically analyze the compositional dependencies of viscosity and electrical resistivity and develop composition-property response surfaces, (2) submit all the data to CGR member companies to evaluate the usefulness in their models, and (3) publish the results in technical journals and most likely in book form.
Date: March 31, 2003
Creator: III, Thomas P. Seward
Partner: UNT Libraries Government Documents Department

Prediction of Corrosion of Alloys in Mixed-Solvent Environments

Description: Corrosion is much less predictable in organic or mixed-solvent environments than in aqueous process environments. As a result, US chemical companies face greater uncertainty when selecting process equipment materials to manufacture chemical products using organic or mixed solvents than when the process environments are only aqueous. Chemical companies handle this uncertainty by overdesigning the equipment (wasting money and energy), rather than by accepting increased risks of corrosion failure (personnel hazards and environmental releases). Therefore, it is important to develop simulation tools that would help the chemical process industries to understand and predict corrosion and to develop mitigation measures. To create such tools, we have developed models that predict (1) the chemical composition, speciation, phase equilibria, component activities and transport properties of the bulk (aqueous, nonaqueous or mixed) phase that is in contact with the metal; (2) the phase equilibria and component activities of the alloy phase(s) that may be subject to corrosion and (3) the interfacial phenomena that are responsible for corrosion at the metal/solution or passive film/solution interface. During the course of this project, we have completed the following: (1) Development of thermodynamic modules for calculating the activities of alloy components; (2) Development of software that generates stability diagrams for alloys in aqueous systems; these diagrams make it possible to predict the tendency of metals to corrode; (3) Development and extensive verification of a model for calculating speciation, phase equilibria and thermodynamic properties of mixed-solvent electrolyte systems; (4) Integration of the software for generating stability diagrams with the mixed-solvent electrolyte model, which makes it possible to generate stability diagrams for nonaqueous or mixed-solvent systems; (5) Development of a model for predicting diffusion coefficients in mixed-solvent electrolyte systems; (6) Development of fundamentals of a detailed kinetic model of general corrosion, which includes a detailed treatment of local chemistry changes near ...
Date: June 5, 2003
Creator: A. Anderko, P. Wang, R. D. Young, D. P. Riemer, P. McKenzie and M. M. Lencka (OLI Systems Inc.) & Laboratory), S. S. Babu and P. Angelini (Oak Ridge National
Partner: UNT Libraries Government Documents Department

A Search for Periodic and Quasi-Periodic Patterns in Select Proxy Data with a Goal to Understanding Temperature Variation

Description: In this work over 200 temperature proxy data sets have been analyzed to determine if periodic and or quasi-periodic patterns exist in the data sets. References to the journal articles where data are recorded are provided. Chapter 1 serves an introduction to the problem of temperature determination in providing information on how various proxy data sources are derived. Examples are given of the techniques followed in producing proxy data that predict temperature for each method used. In chapter 2 temperature proxy data spanning the last 4000 years, from 2,000 BCE to 2,000 CE, are analyzed to determine if overarching patterns exist in proxy data sets. An average of over 100 proxy data sets was used to produce Figure 4. An overview of the data shows that several “peaks” can be identified. The data were then subjected to analysis using a series of frequency modulated cosine waves. This analysis led to a function that can be expressed by equation 3. The literature was examined to determine what mathematical models had been published to fit the experimental proxy data for temperature. A number of attempts have been made to fit data from limited data sets with some degree of success. Some other papers have used a sinusoidal function to best fit the changes in the temperature. After consideration of many published papers and reviewing long time streams of proxy data that appeared to have sine wave patterns, a new model was proposed for trial. As the patterns observed showed “almost” repeating sine cycles, a frequency modulated sine wave was chosen to obtain a best fit function. Although other papers have used a sinusoidal function to best fit the changes in the temperature, the “best fit” was limited. Thus, it was decided that a frequency modulated sine wave may be a better model ...
Date: May 2016
Creator: Otto, James
Partner: UNT Libraries