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Seismicity Precursors of the M6.0 2004 Parkfield and M7.0 1989Loma Prieta Earthquakes

Description: The M6.0 2004 Parkfield and M7.0 1989 Loma Prietastrike-slip earthquakes on the San Andreas Fault (SAF) were preceded byseismicity peaks occurring several months prior to the main events.Earthquakes directly within the SAF zone were intentionally excluded fromthe analysis because they manifest stress-release processes rather thanstress accumulation. The observed increase in seismicity is interpretedas a signature of the increasing stress level in the surrounding crust,whereas the peaks and the subsequent decrease in seismicity areattributed to damage-induced softening processes. Furthermore, in bothcases there is a distinctive zone of low seismic activity that surroundsthe epicentral region in the pre-event period. The increase of seismicityin the crust surrounding a potential future event and the development ofa low-seismicity epicentral zone can be regarded as promising precursoryinformation that could help signal the arrival of large earthquakes. TheGutenberg-Richter relationship (GRR) should allow extrapolation ofseismicity changes down to seismic noise level magnitudes. Thishypothesis is verified by comparison of seismic noise at 80 Hz with theParkfield M4 1993-1994 series, where noise peaks 5 months before theseries to about twice the background level.
Date: March 9, 2006
Creator: Korneev, Valeri A.
Partner: UNT Libraries Government Documents Department

An Estimate of Energy Use in Laboratories, Cleanrooms, and Data Centers in New York

Description: Laboratories, cleanrooms and data centers are very energy-intensive. For example, laboratories are typically three to eight times as energy intensive as a typical office building, and a data center may be as much as 20-50 times as energy intensive as a typical office building. This technical note presents an estimate of the total energy use in laboratories, cleanrooms and data centers in New York. There is generally very limited data on energy use in the high tech sector, both at the national and state level. Since it was beyond the scope of this project to develop primary data through surveys, the analysis relied primarily on the use of proxy indicators and extrapolation from national data where available. The results for each building type are summarized below in table E-1 and figure E-1.
Date: October 1, 2008
Creator: Mathew, Paul
Partner: UNT Libraries Government Documents Department

Ecotoxicological effects extrapolation models

Description: One of the central problems of ecological risk assessment is modeling the relationship between test endpoints (numerical summaries of the results of toxicity tests) and assessment endpoints (formal expressions of the properties of the environment that are to be protected). For example, one may wish to estimate the reduction in species richness of fishes in a stream reach exposed to an effluent and have only a fathead minnow 96 hr LC50 as an effects metric. The problem is to extrapolate from what is known (the fathead minnow LC50) to what matters to the decision maker, the loss of fish species. Models used for this purpose may be termed Effects Extrapolation Models (EEMs) or Activity-Activity Relationships (AARs), by analogy to Structure-Activity Relationships (SARs). These models have been previously reviewed in Ch. 7 and 9 of and by an OECD workshop. This paper updates those reviews and attempts to further clarify the issues involved in the development and use of EEMs. Although there is some overlap, this paper does not repeat those reviews and the reader is referred to the previous reviews for a more complete historical perspective, and for treatment of additional extrapolation issues.
Date: September 1996
Creator: Suter, G. W., II
Partner: UNT Libraries Government Documents Department

Extrapolation of supersymmetry-breaking parameters to high energy scales

Description: The author studies how well one can extrapolate the values of supersymmetry-breaking parameters to very high energy scales using future data from the Large Hadron Collider and an e{sup +}e{sup -} linear collider. He considers tests of the unification of squark and slepton masses in supergravity-inspired models. In gauge-mediated supersymmetry breaking models, he assess the ability to measure the mass scales associated with supersymmetry breaking. He also shows that it is possible to get good constraints on a scalar cubic stop-stop-Higgs couplings near the high scale. Different assumptions with varying levels of optimism about the accuracy of input parameter measurements are made, and their impact on the extrapolated results is documented.
Date: November 7, 2002
Creator: Martin, Stephen P
Partner: UNT Libraries Government Documents Department

Remark on the theoretical uncertainty in B0-Bbar0 Mixing

Description: The authors re-examine the theoretical uncertainty in the Standard Model expression for B{sup 0}-{bar B}{sup 0} mixing. They focus on lattice calculations of the ratio {xi}, needed to relate the oscillation frequency of B{sub s}{sup 0}-{bar B}{sub s}{sup 0} mixing to V{sub td}. They replace the usual linear chiral extrapolation with one that includes the logarithm that appears in chiral perturbation theory. We find a significant shift in the ratio {xi}, from the conventional 1.15 {+-} 0.05 to {xi} = 1.32 {+-} 0.10.
Date: September 19, 2002
Creator: Kronfeld, Sinead Ryan and Andreas
Partner: UNT Libraries Government Documents Department

The Vapor Pressure of 1-(2,2,3,3-Tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-prop anol

Description: The vapor pressure of the compound 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol was measured over the temperature range 62 to 92 C using a Knudsen effusion technique. This compound, known as Cs-7SB, is the modifier component in the caustic-side solvent extraction process solvent. The vapor pressure is related to temperature by the equation ln(p/Pa) = (32.202 {+-} 0.265) - (12154 {+-} 93)/T, where p is the pressure, expressed in pascals; Pa is the reference pressure of 1 pascal; and T is the temperature, expressed in degrees kelvin. The derived heat of vaporization is 101.1 {+-} 0.8{sup kJ{center_dot}mol{sup 1} at 351 K. Because the vapor pressures over the temperature range of 15 to 50 C were lower than the design capabilities of the Knudsen effusion apparatus, the vapor pressures at these temperature limits were obtained by extrapolation. The estimated values are 4.6 {+-} 0.3E-05 (3.5 {+-} 0.2E-07 mm Hg) and 4.5 {+-} 0.1E-03 Pa (3.4 {+-} 0.1E-05 mm Hg) for 15 C and 50 C, respectively.
Date: January 29, 2002
Creator: Steele, W.V.
Partner: UNT Libraries Government Documents Department


Description: Wave-equation migration methods can more accurately account for complex wave phenomena than ray-tracing-based Kirchhoff methods that are based on the high-frequency asymptotic approximation of waves. With steadily increasing speed of massively parallel computers, wave-equation migration methods are becoming more and more feasible and attractive for imaging complex 3D structures. We present an overview of several efficient and accurate wave-equation-based migration methods that we have recently developed. The methods are implemented in the frequency-space and frequency-wavenumber domains and hence they are called dual-domain methods. In the methods, we make use of different approximate solutions of the scalar-wave equation in heterogeneous media to recursively downward continue wavefields. The approximations used within each extrapolation interval include the Born, quasi-Born, and Rytov approximations. In one of our dual-domain methods, we use an optimized expansion of the square-root operator in the one-way wave equation to minimize the phase error for a given model. This leads to a globally optimized Fourier finite-difference method that is a hybrid split-step Fourier and finite-difference scheme. Migration examples demonstrate that our dual-domain migration methods provide more accurate images than those obtained using the split-step Fourier scheme. The Born-based, quasi-Born-based, and Rytov-based methods are suitable for imaging complex structures whose lateral variations are moderate, such as the Marmousi model. For this model, the computational cost of the Born-based method is almost the same as the split-step Fourier scheme, while other methods takes approximately 15-50% more computational time. The globally optimized Fourier finite-difference method significantly improves the accuracy of the split-step Fourier method for imaging structures having strong lateral velocity variations, such as the SEG/EAGE salt model, at an approximately 30% greater computational cost than the split-step Fourier method.
Date: December 1, 2000
Creator: HUANG, L. & FEHLER, M. C.
Partner: UNT Libraries Government Documents Department

Water-Level Monitoring Plan for the Hanford Groundwater Monitoring Project

Description: This document presents the water-level monitoring plan for the Hanford Groundwater Monitoring Project, conducted by the Pacific Northwest National Laboratory (PNNL). Water-level monitoring of the groundwater system beneath the Hanford Site is performed to fulfill the requirements of various state and federal regulations, orders, and agreements. The primary objective of this monitoring is to determine groundwater flow rates and directions. To meet this and other objectives, water-levels are measured annually in monitoring wells completed within the unconfined aquifer system, the upper basalt-confined aquifer system, and in the lower basalt-confined aquifers for surveillance monitoring. At regulated waste units, water levels are taken monthly, quarterly, semi-annually, or annually, depending on the hydrogeologic conditions and regulatory status of a given site. The techniques used to collect water-level data are described in this document along with the factors that affect the quality of the data and the strategies employed by the project to minimize error in the measurement and interpretation of water levels. Well networks are presented for monitoring the unconfined aquifer system, the upper basalt-confined aquifer system, and the lower basalt-confined aquifers, all at a regional scale (surveillance monitoring), as well as the local-scale well networks for each of the regulated waste units studied by this project (regulated-unit monitoring). The criteria used to select wells for water-table monitoring are discussed. It is observed that poor well coverage for surveillance water-table monitoring exists south and west of the 200-West Area, south of the 100-F Area, and east of B Pond and the Treated Effluent Disposal Facility (TEDF). This poor coverage results from a lack of wells suitable for water-table monitoring, and causes uncertainty in representation of the regional water-table in these areas. These deficiencies are regional in scale and apply to regions outside of the operational areas, so these deficiencies do not in anyway ...
Date: September 30, 1999
Creator: Newcomer, D.R.; McDonald, J.P. & Chamness, M.A.
Partner: UNT Libraries Government Documents Department

Qualification of a Method to Calculate the Irrecoverable Pressure Loss in High Reynolds Number Piping Systems

Description: High Reynolds number test data has recently been reported for both single and multiple piping elbow design configurations at earlier ASME Fluid Engineering Division conferences. The data of these studies ranged up to a Reynolds number of 42 x 10[sup]6 which is significantly greater than that used to establish design correlations before the data was available. Many of the accepted design correlations, based on the lower Reynolds number data, date back as much as fifty years. The new data shows that these earlier correlations are extremely conservative for high Reynolds number applications. Based on the recent high Reynolds number information a new recommended method has been developed for calculating irrecoverable pressure loses in piping systems for design considerations such as establishing pump sizing requirements. This paper describes the recommended design approach and additional testing that has been performed as part of the qualification of the method. This qualification testing determined the irrecoverable pressure loss of a piping configuration that would typify a limiting piping section in a complicated piping network, i.e., multiple, tightly coupled, out-of-plane elbows in series under high Reynolds number flow conditions. The overall pressure loss measurements were then compared to predictions, which used the new methodology to assure that conservative estimates for the pressure loss (of the type used for pump sizing) were obtained. The recommended design methodology, the qualification testing and the comparison between the predictions and the test data are presented. A major conclusion of this study is that the recommended method for calculating irrecoverable pressure loss in piping systems is conservative yet significantly lower than predicted by early design correlations that were based on the extrapolation of low Reynolds number test data.
Date: September 1, 2002
Creator: Sigg, K. C. & Coffield, R. D.
Partner: UNT Libraries Government Documents Department


Description: This study describes the impact of lighting management systems that dynamically control lights in accordance with the needs of occupants. Various control strategies are described: scheduling, tuning, lumen depreciation, and daylighting. From initial experimental results, the energy savings provided by each of the above strategies are estimated to be 26, 12, 14, and 15%, respectively. Based upon a cost of $0.05-0.10 per kWh for electric energy and a 2-, 3-, or 4-yr payback, target costs for a simple and a sophisticated lighting management system are found to be $0.24 and 1.89 per ft{sup 2}, respectively, for a cost-effective investment. A growth model, based upon an extrapolation of the increase in building stock since 1975, indicates that the commercial and industrial (C and I) building stock will grow from 40 x 10{sup 9} ft{sup 2} in 1980 to about 67 x 10{sup 9} ft{sup 2} by the year 2000. Even with the use of more efficient lighting components, the energy required for this additional C and I stock will be 307 x 10{sup 9} kWh, an increase of only 13 x 10{sup 9} kWh above current use. The specified information is used to analyze the economic impacts that using these systems will have on the lighting industry, end users, utility companies, and the nation's economy. A $1 - 4 x 10{sup 9} annual lighting control industry can be generated, creating many jobs. The estimated return on investment (ROI) for controls for end users would be between 19 and 38%. Utilities will be able to make smaller additions to capacity and invest less capital at 7-10% ROI. Finally, the annual energy savings, up to $3.4 x 10{sup 9} for end users and about $5 x 10{sup 9} for utilities, representing unneeded generating capacity, will be available to capitalize other areas of the ...
Date: September 1, 1982
Creator: Verderber, R.R. & Rubinstein, F.
Partner: UNT Libraries Government Documents Department

Field verification program for small wind turbines

Description: In 1999 Windward Engineering (Windward) was awarded a Cooperative Agreement under the Field Verification Program with the Department of Energy (DOE) to install two Whisper H40 wind turbines, one at the NREL National Wind Technology Center (NWTC) and one at a test site near Spanish Fork, Utah. After installation, the turbine at the NWTC was to be operated, maintained, and monitored by NREL while the turbine in Spanish Fork was to be administered by Windward. Under this award DOE and Windward defined the primary objectives of the project as follows: (1) Determine and demonstrate the reliability and energy production of a furling wind turbine at a site where furling will be a very frequent event and extreme gusts can be expected during the duration of the tests. (2) Make engineering measurements and conduct limited computer modeling of the furling behavior to improve the industry understanding of the mechanics and nature of furling. We believe the project has achieved these objectives. The turbine has operated for approximately three and a half years. We have collected detailed engineering data approximately 75 percent of that time. Some of these data were used in an ADAMS model validation that highlighted the accuracies and inaccuracies of the computer modeling for a passively furling wind turbine. We also presented three papers at the American Wind Energy Association (AWEA) Windpower conferences in 2001, 2002, and 2003. These papers addressed the following three topics: (a) general overview of the project [1], (b) furling operation during extreme wind events [2], and (c) extrapolation of extreme (design) loads [3]. We believe these papers have given new insight into the mechanics and nature of furling and have set the stage for future research. In this final report we will highlight some of the more interesting aspects of the project as well ...
Date: November 30, 2003
Creator: Windward Engineering, LLC
Partner: UNT Libraries Government Documents Department

Secondary Electron Yield Measurements of Fermilab?s Main Injector Vacuum Vessel

Description: We discuss the progress made on a new installation in Fermilab's Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.
Date: May 1, 2012
Creator: Scott, D.J.; Capista, D.; Duel, K.L.; Zwaska, R.M.; /Fermilab; Greenwald, S. et al.
Partner: UNT Libraries Government Documents Department

Chemistry of the heaviest elements--one atom at a time

Description: In keeping with the goal of the Viewpoint series of the Journal of Chemical Education, this article gives a 75-year perspective of the chemistry of the heaviest elements, including a 50-year retrospective view of past developments, a summary of current research achievements and applications, and some predictions about exciting, new developments that might be envisioned within the next 25 years. A historical perspective of the importance of chemical separations in the discoveries of the transuranium elements from neptunium (Z=93) through mendelevium (Z=101) is given. The development of techniques for studying the chemical properties of mendelevium and still heavier elements on the basis of measuring the radioactive decay of a single atom (''atom-at-a-time'' chemistry) and combining the results of many separate experiments is reviewed. The influence of relativistic effects (expected to increase as Z{sup 2}) on chemical properties is discussed. The results from recent atom-at-a-time studies of the chemistry of the heaviest elements through seaborgium (Z=106) are summarized and show that their properties cannot be readily predicted based on simple extrapolation from the properties of their lighter homologues in the periodic table. The prospects for extending chemical studies to still heavier elements than seaborgium are considered and appear promising.
Date: January 1, 2000
Creator: Hoffman, Darleane C. & Lee, Diana M.
Partner: UNT Libraries Government Documents Department

Electrical conductivity of fluid oxygen at high pressures

Description: Electrical conductivities of fluid oxygen were measured between 30 and 80 GPa at a few 1000 K. These conditions were achieved with a reverberating shock wave technique. The measured conductivities were several orders of magnitude lower than measured previously on the single shock Hugoniot because of lower temperatures achieved under shock reverberation. Extrapolation of these data suggests that the minimum metallic conductivity of a metal will be reached near 100 GPa.
Date: August 20, 1999
Creator: Bastea, M; Mitchell, A C & Nellis, W J
Partner: UNT Libraries Government Documents Department

Filamentation and Forward Brillouin Scatter of Entire Smoothed and Aberrated Laser Beams

Description: Laser-plasma interactions are sensitive to both the fine-scale speckle and the larger scale envelope intensity of the beam. For some time, simulations have been done on volumes taken from part of the laser beam cross-section, and the results from multiple simulations extrapolated to predict the behavior of the entire beam. However, extrapolation could very well miss effects of the larger scale structure on the fine-scale. The only definitive method is to simulate the entire beam. These very large calculations have been infeasible until recently, but they are now possible on massively parallel computers. Whole beam simulations show the dramatic difference in the propagation and break up of smoothed and aberrated beams.
Date: October 29, 1999
Creator: Still, C.H.; Berger, R.L.; Langdon, A.B.; Hinkel, D.E. & Williams, E.A.
Partner: UNT Libraries Government Documents Department

Spectrum Fatigue Lifetime and Residual Strength for Fiberglass Laminates

Description: This report addresses the effects of spectrum loading on lifetime and residual strength of a typical fiberglass laminate configuration used in wind turbine blade construction. Over 1100 tests have been run on laboratory specimens under a variety of load sequences. Repeated block loading at two or more load levels, either tensile-tensile, compressive-compressive, or reversing, as well as more random standard spectra have been studied. Data have been obtained for residual strength at various stages of the lifetime. Several lifetime prediction theories have been applied to the results. The repeated block loading data show lifetimes that are usually shorter than predicted by the most widely used linear damage accumulation theory, Miner's sum. Actual lifetimes are in the range of 10 to 20 percent of predicted lifetime in many cases. Linear and nonlinear residual strength models tend to fit the data better than Miner's sum, with the nonlinear providing a better fit of the two. Direct tests of residual strength at various fractions of the lifetime are consistent with the residual strength models. Load sequencing effects are found to be insignificant. The more a spectrum deviates from constant amplitude, the more sensitive predictions are to the damage law used. The nonlinear model provided improved correlation with test data for a modified standard wind turbine spectrum. When a single, relatively high load cycle was removed, all models provided similar, though somewhat non-conservative correlation with the experimental results. Predictions for the full spectrum, including tensile and compressive loads were slightly non-conservative relative to the experimental data, and accurately captured the trend with varying maximum load. The nonlinear residual strength based prediction with a power law S-N curve extrapolation provided the best fit to the data in most cases. The selection of the constant amplitude fatigue regression model becomes important at the lower stress, higher ...
Date: March 1, 2002
Partner: UNT Libraries Government Documents Department


Description: The ELOISATRON Project is a proton-proton collider at very high energy and very large luminosity. The main goal is to determine the ultimate performance that is possible to achieve with reasonable extrapolation of the present accelerator technology. A complete study and design of the collider requires that several steps of investigations are undertaken. The authors count five of such steps as outlined in the report.
Date: November 4, 1996
Creator: RUGGIERO,A.G.
Partner: UNT Libraries Government Documents Department

Immiscibility in the Nickel Ferrite-Zinc Ferrite Spinel Binary

Description: Immiscibility in the trevorite (NiFe{sub 2}O{sub 4}) - franklinite (ZnFe{sub 2}O{sub 4}) spinel binary is investigated by reacting 1:1:2 molar ratio mixtures of NiO, ZnO and Fe{sub 2}O{sub 3} in a molten salt solvent at temperatures in the range 400-1000 C. Single phase stability is demonstrated down to about 730 C (the estimated consolute solution temperature, T{sub cs}). A miscibility gap/solvus exists below Tcs. The solvus becomes increasingly asymmetric at lower temperatures and extrapolates to n - values = 0.15, 0.8 at 300 C. A thermodynamic analysis, which accounts for changes in configurational and magnetic ordering entropies during cation mixing, predicts solvus phase compositions at room temperature in reasonable agreement with those determined by extrapolation of experimental results. The delay between disappearance of magnetic ordering above T{sub C} = 590 C (for NiFe{sub 2}O{sub 4}) and disappearance of a miscibility gap at T{sub cs} is explained by the persistence of long-range ordering correlations in a quasi-paramagnetic region above T{sub C}.
Date: June 21, 2006
Creator: Ziemniak, SE; Gaddipati, AR; Sander, PC & Rice, SB
Partner: UNT Libraries Government Documents Department

First Principles Calculations of Electrochemically Controlled Hydrogen Mobility and Uptake at the Ni(111)H2O Interface

Description: The binding of hydrogen on Ni(111) in the presence of an water is considered using both a bilayer and a saturated model of the solvent environment. The presence of a water bilayer did not change the binding energies or geometry of hydrogen on the Ni(111) compared to adsorption in ultra-high vacuum. Using the saturated model (four bilayers over the surface) we also monitored the change in hydrogen binding as a function of electrochemical potential. Binding energies for hydrogen at the hcp and octahedral sites shifted endothermically as the potential was made more anodic, indicating that reductive partial charge transfer occurs. Binding at the tetrahedral site was found to be partially oxidizing. Calculation of vibrational modes allowed the extrapolation of ab initio results to ambient and elevated temperatures. Surface Pourbaix diagrams were constructed illustrating the stability of various phases on the Ni(111) surface as a function of pH and potential.
Date: November 14, 2005
Creator: Taylor, C; Kelly, R & Neurock, M
Partner: UNT Libraries Government Documents Department

Assessing Sources of Stress to Aquatic Ecosystems: Using Biomarkers and Bioindicators to Characterize Exodure-Response Profiles of Anthropogenic Activities

Description: Establishing causal relationships between sources of environmental stressors and aquatic ecosystem health if difficult because of the many biotic and abiotic factors which can influence or modify responses of biological systems to stress, the orders of magnitude involved in extrapolation over both spatial and temporal scales, and compensatory mechanisms such as density-dependent responses that operate in populations. To address the problem of establishing causality between stressors and effects on aquatic systems, a diagnostic approach, based on exposure-response profiles for various anthropogenic activities, was developed to help identify sources of stress responsible for effects on aquatic systems at ecological significant levels of biological organization (individual, population, community). To generate these exposure-effects profiles, biomarkers of exposure were plotted against bioindicators of corresponding effects for several major anthropogenic activities including petrochemical , pulp and paper, domestic sewage, mining operations, land-development activities, and agricultural activities. Biomarkers of exposure to environmental stressors varied depending on the type of anthropogenic activity involved. Bioindicator effects, however, including histopathological lesions, bioenergetic status, individual growth, reproductive impairment, and community-level responses were similar among many of the major anthropogenic activities. This approach is valuable to help identify and diagnose sources of stressors in environments impacted by multiple stressors. By identifying the types and sources of environmental stressors, aquatic ecosystems can be more effectively protected and managed to maintain acceptable levels of environmental quality and ecosystem fitness.
Date: March 29, 1999
Creator: Adams, S.M.
Partner: UNT Libraries Government Documents Department

ScalaTrace: Tracing, Analysis and Modeling of HPC Codes at Scale

Description: Characterizing the communication behavior of large-scale applications is a difficult and costly task due to code/system complexity and their long execution times. An alternative to running actual codes is to gather their communication traces and then replay them, which facilitates application tuning and future procurements. While past approaches lacked lossless scalable trace collection, we contribute an approach that provides orders of magnitude smaller, if not near constant-size, communication traces regardless of the number of nodes while preserving structural information. We introduce intra- and inter-node compression techniques of MPI events, we develop a scheme to preserve time and causality of communication events, and we present results of our implementation for BlueGene/L. Given this novel capability, we discuss its impact on communication tuning and on trace extrapolation. To the best of our knowledge, such a concise representation of MPI traces in a scalable manner combined with time-preserving deterministic MPI call replay are without any precedence.
Date: March 31, 2010
Creator: Mueller, F; Wu, X; Schulz, M; de Supinski, B & Gamblin, T
Partner: UNT Libraries Government Documents Department


Description: A271 CHARACTERISTICS OF THE H-MODE PEDESTAL AND EXTRAPOLATION TO ITER. The peeling-ballooning mode model for edge stability along with a model for the H-mode transport barrier width is used as an approach to estimating the H-mode pedestal conditions in ITER. Scalings of the barrier width based on ion-orbit loss, neutral penetration, and turbulence suppression are examined and empirical scalings of the barrier width are presented. An empirical scaling for the pedestal {beta} is derived based on ideas from stability and the empirical width scaling. The impact of the stability model and other factors on ELM size is discussed.
Date: November 1, 2002
Partner: UNT Libraries Government Documents Department


Description: Lean flame extinction limits of binary fuel mixtures of methane (CH{sub 4}), propane (C{sub 3}H{sub 8}), and ethane (C{sub 2}H{sub 6}) were measured using a twin-flame counter-flow burner. Experiments were conducted to generate an extinction equivalence ratio vs. global stretch rate plot and an extrapolation method was used to calculate the equivalence ratio corresponding to an experimentally unattainable zero-stretch condition. The foregoing gases were selected because they are the primary constitutes of natural gas, which is the primary focus of the present study. To validate the experimental setup and methodology, the flame extinction limit of pure fuels at zero stretch conditions were also estimated and compared with published values. The lean flame extinction limits of methane (f{sub ext} = 4.6%) and propane (f{sub ext} = 2.25%) flames measured in the present study agreed with the values reported in the literature. It was observed that the flame extinction limit of fuel blends have a polynomial relation with the concentration of component fuels in the mixture. This behavior contradicts with the commonly used linear Le Chatelier's approximation. The experimentally determined polynomial relations between the flame extinction limits of fuel blends (i.e. methane-propane and methane-ethane) and methane concentration are as follows: (1) Methane-Propane--%f{sub ext} = (1.05 x 10{sup -9}) f{sup 5}-(1.3644 x 10{sup -7}) f{sup 4}+(6.40299 x 10{sup -6}) f{sup 3}-(1.2108459 x 10{sup -4}) f{sup 2}+(2.87305329 x 10{sup -3}) f+2.2483; (2) Methane-Ethane--%f{sub ext} = (2.1 x 10{sup -9})f{sup 5}-(3.5752 x 10{sup -7}) f{sup 4}+(2.095425 x 10{sup -5}) f{sup 3}-(5.037353 x 10{sup -4}) f{sup 2} + 6.08980409 f + 2.8923. Where f{sub ext} is the extinction limits of methane-propane and methane-ethane fuel blends, and f is the concentration (% volume) of methane in the fuel mixture. The relations were obtained by fitting fifth order curve (polynomial regression) to experimentally measured extinction limits at different ...
Date: February 1, 2005
Creator: Choudhuri, Ahsan R.
Partner: UNT Libraries Government Documents Department