11,553 Matching Results

Search Results

A Theoretical Investigation of Mode-Locking Phenomena in Reversed Field Pinches

Description: OAK-B135 This paper investigates the formation and breakup of the ''slinky mode'' in an RFP using analytic techniques previously employed to examine mode locking phenomena in tokamaks. The slinky mode is a toroidally localized, coherent interference pattern in the magnetic field which co-rotates with the plasma at the reversal surface. This mode forms, as a result of the nonlinear coupling of multiple m = 1 core tearing modes, via a bifurcation which is similar to that by which toroidally coupled tearing modes lock together in a tokamak. The slinky mode breaks up via a second bifurcation which is similar to that by which toroidally coupled tearing modes in a tokamak unlock. However, the typical m = 1 mode amplitude below which slinky breakup is triggered is much smaller than that above which slinky formation occurs. Analytic expressions for the slinky formation and breakup thresholds are obtained in all regimes of physical interest. The locking of the slinky mode to a static error-field is also investigated analytically. Either the error-field arrests the rotation of the plasma at the reversal surface before the formation of the slinky mode, so that the mode subsequently forms as a non-rotating mode, or the slinky mode forms as a rotating mode and subsequently locks to the error-field. Analytic expressions for the locking and unlocking thresholds are obtained in all regimes of physical interest. The problems associated with a locked slinky mode can be alleviated by canceling out the accidentally produced error-field responsible for locking the slinky mode, using a deliberately created ''control'' error-field. Alternatively, the locking angle of the slinky mode can be swept toroidally by rotating the control field.
Date: April 7, 2004
Creator: Fitzpatrick, Richard
Partner: UNT Libraries Government Documents Department

Hindered Diffusion of Asphaltenes at Elevated Temperature and Pressure Progress Report

Description: During this time period, experiments were performed to study the diffusion controlled uptake of quinoline and a coal asphaltene into porous carbon catalyst pellets. Cyclohexane and toluene were used as solvents for quinoline and the coal asphaltene respectively. The experiments were performed at 27 C and 75 C, at a pressure of 250 psi (inert gas) for the quinoline/cyclohexane system. For the coal asphaltene/toluene system, experiments were performed at 27 C, also at a pressure of 250 psi. These experiments were performed in a 20 cm{sup 3} microautoclave, the use of which is advantageous since it is economical from both a chemical procurement and waste disposal standpoint due to the small quantities of solvents and catalysts used. A C++ program was written to simulate data using a mathematical model which incorporated both diffusional and adsorption mechanisms. The simulation results showed that the mathematical model satisfactorily fitted the adsorptive diffusion of quinoline and the coal asphaltene onto a porous activated carbon. For the quinoline/cyclohexane system, the adsorption constant decreased with an increase in temperature. The adsorption constant for the coal asphaltene/toluene system at 27 C was found to be much higher than that of the quinoline/cyclohexane system at the same temperature. Apparently the coal asphaltenes have a much greater affinity for the surface of the carbon catalyst than is evidenced by the quinoline molecule.
Date: October 7, 1999
Creator: Guin, James A. & Ramakrishnan, Ganesh
Partner: UNT Libraries Government Documents Department

Assessment of a chemical getter for scavenging tritium from an inert gas

Description: Results are presented of a study aimed at determining the feasibility of using chemical getter beds to scavenge tritium from inert gases. Two types of getter bed, fixed and fluidized, were considered, using cerium as the getter material. Mathematical-modeling results and capital-cost estimates indicate that not only is the gettering approach technically feasible, it could lead to considerable cost savings over catalytic oxidation, the tritium-removal method traditionally used.
Date: May 7, 1976
Creator: Maienschein, J. L.
Partner: UNT Libraries Government Documents Department

Meteorological data for SRI study of mesoscale weather effects by pilot plant

Description: The data required to estimate the probability of occurrence of initial meteorological conditions leading to an effect on the weather by the pilot solar thermal electric plant are discussed. No completely appropriate data summaries are available. Vertical atmospheric profiles are the most appropriate source of raw data for a statistical analysis, but these are not available from the pilot plant location either. The available stability data for the pilot plant site are presented. A procedure is outlined to obtain the required estimates of occurrence frequency if desired. However, it is recommended that more substantial effects be demonstrated with a physically realistic model before great effort is expended on data analysis.
Date: May 7, 1980
Partner: UNT Libraries Government Documents Department

Lignite Fuel Enhancement Progress Report

Description: The Design Team continued to conference this quarter. Their primary task during this timeframe was to finalize the dryer design based on information learned from the NDIC Pilot work and detailed design discussions at Barr offices in August. Heyl-Patterson was tasked with incorporating all comments and drafting drawings. They submitted a preliminary proposal which spawned detailed discussions about tube bundle, air locks, and fire suppression systems. The type of fire protection specified dictated the final structural arrangement. Three meetings were spent discussing the pro's and con's of suppression vs. ventilation systems. In the end, the dryer and bucket elevator will have suppression systems and the remaining equipment will be explosion vented. This is in agreement with GRE's current insurer, FM Global. Three inlet airlocks were reduced to two and four outlets were reduced to three. The inlet plenum was subdivided for greater flexibility and sparging air added in the outlet plenum. It was also decided to use bundles with varied material, diameter, and tube & fin spacing. This will be completed in an effort to identify for us which configuration has the best heat transfer characteristics using coal as the fluidizing medium. The dryer will also be delivered in four pieces. This will allow for installation through the current access door on the Air Heater deck. The Input/Output list and functional description was completed and forwarded to Honeywell to finalize controls. Major pieces of equipment received this quarter were the Bucket Elevator, Liewell Screen, conveyors, and Motor Control Center. ICI completed removal of the wall separating Silo 28 from the dryer area; handrail and grating between the two areas has also been removed. They relocated a blowdown line. They moved an Air Heater basket access hatch.
Date: February 7, 2005
Creator: Bullinger, Charles
Partner: UNT Libraries Government Documents Department

Lignite Fuel Enhancement Progress Report

Description: This 3rd quarterly Technical Progress Report for the Lignite Fuel Enhancement Project summarizes activities from January 1st through March 31st of 2005. It also summarizes the subsequent purchasing activity and final dryer/process design.
Date: June 7, 2005
Creator: Bullinger, Charles
Partner: UNT Libraries Government Documents Department


Description: This 4th quarterly Technical Progress Report for the Lignite Fuel Enhancement Project summarizes activities from April 1st through June 30th of 2005. It also summarizes the subsequent purchasing activity and dryer/process construction.
Date: July 7, 2005
Creator: Bullinger, Charles
Partner: UNT Libraries Government Documents Department

[News Clip: Elephant walk]

Description: B-roll video footage from the KXAS-TV/NBC station in Fort Worth, Texas, to accompany a news story.
Date: August 7, 1981, 12:00 p.m.
Creator: KXAS-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Clip: Capital fire]

Description: B-roll video footage from the KXAS-TV/NBC station in Fort Worth, Texas, to accompany a news story.
Date: February 7, 1983, 5:00 p.m.
Creator: KXAS-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

Full-Scale Testing of Enhanced Mercury Control Technologies for Wet FGD Systems: Final Report

Description: Wet flue gas desulfurization (wet FGD) systems are currently installed on about 25% of the coal-fired utility generating capacity in the U.S., representing about 15% of the number of coal-fired units. Depending on the effect of operating parameters such as mercury content of the coal, form of mercury (elemental or oxidized) in the flue gas, scrubber spray tower configuration, liquid-to-gas ratio, and slurry chemistry, FGD systems can provide cost-effective, near-term mercury emissions control options with a proven history of commercial operation. For boilers already equipped with FGD systems, the incremental cost of any vapor phase mercury removal achieved is minimal. To be widely accepted and implemented, technical approaches that improve mercury removal performance for wet FGD systems should also have low incremental costs and have little or no impact on operation and SO{sub 2} removal performance. The ultimate goal of the Full-scale Testing of Enhanced Mercury Control for Wet FGD Systems Program was to commercialize methods for the control of mercury in coal-fired electric utility systems equipped with wet flue gas desulfurization (wet FGD). The program was funded by the U.S. Department of Energy's National Energy Technology Laboratory, the Ohio Coal Development Office within the Ohio Department of Development, and Babcock & Wilcox. Host sites and associated support were provided by Michigan South Central Power Agency (MSCPA) and Cinergy. Field-testing was completed at two commercial coal-fired utilities with wet FGD systems: (1) MSCPA's 55 MW{sub e} Endicott Station and (2) Cinergy's 1300 MW{sub e} Zimmer Station. Testing was conducted at these two locations because of the large differences in size and wet scrubber chemistry. Endicott employs a limestone, forced oxidation (LSFO) wet FGD system, whereas Zimmer uses Thiosorbic{reg_sign} Lime (magnesium enhanced lime) and ex situ oxidation. Both locations burn Ohio bituminous coal.
Date: May 7, 2003
Creator: McDonald, D. K.; Amrhein, G. T.; Kudlac, G. A. & Yurchison, D. Madden
Partner: UNT Libraries Government Documents Department

Hyper filter-fluorescer spectrometer for x rays above 120 keV

Description: An apparatus utilizing filter-fluorescer combinations is provided to measure short bursts of high fluence x-rays above 120 keV energy, where there are no practical absorption edges available for conventional filter-fluorescer techniques. The absorption edge of the prefilter is chosen to be less than that of the fluorescer, i.e., E/sub PRF/ < E/sub F/, contrary to the prior art technique E/sub PRF/ > E/sub F/. In this way, the response function is virtually zero between E/sub PRF/ and E/sub F/ and well defined and enhanced in an energy band of less than 1000 keV above the 120 keV energy.
Date: July 7, 1981
Creator: Wang, C.L.
Partner: UNT Libraries Government Documents Department

Development of Continuous Solvent Extraction Processes for Coal Derived Carbon Products Quarterly Report: October-December 2005

Description: The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. The largest applications are those which support metals smelting, such as anodes for aluminum smelting and electrodes for arc furnaces. Other carbon products include materials used in creating fuels for the Direct Carbon Fuel Cell, metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, efforts have focused on the development of carbon electrodes for Direct Carbon Fuel Cells (DCFC), and on carbon foam composites used in ballistic armor, as well as the hydrotreatment of solvents used in the basic solvent extraction process. A major goal is the production of 1500 pounds of binder pitch, corresponding to about 3000 pounds of hydrotreated solvent.
Date: March 7, 2006
Creator: Kennel, Elliot B.; Berg, Quentin C.; Carpenter, Stephen P.; Dadyburjor, Dady; Hissam, Jason C.; Katakdaunde, Manoj et al.
Partner: UNT Libraries Government Documents Department

Seepage into an Underground Opening Constructed in Unsaturated Fractured Rock Under Evaporative Conditions

Description: Liquid-release tests, performed in boreholes above an underground opening constructed in unsaturated fractured rock, are used in this study to evaluate seepage into a waste emplacement drift. Evidence for the existence of a capillary barrier at the ceiling of the drift is presented, based on field observations (including spreading of the wetting front across the ceiling and water movement up fractures exposed in the ceiling before seepage begins). The capillary barrier mechanism has the potential to divert water around the opening, resulting in no seepage when the percolation flux is at or below the seepage threshold flux. Liquid-release tests are used to demonstrate that a seepage threshold exists and to measure the magnitude of the seepage threshold flux for three test zones that seeped. The seepage data are interpreted using analytical techniques to estimate the test-specific strength of the rock capillary forces ({alpha}{sup -1}) that prevent water from seeping into the drift. Evaporation increases the seepage threshold flux making it more difficult for water to seep into the drift and producing artificially inflated {alpha}{sup -1} values. With adjustments for evaporation, the minimum test-specific threshold is 1,600 mm/yr with a corresponding {alpha}{sup -1} of 0.027 m.
Date: June 7, 2001
Creator: Trautz, R. C. & Wang, Joseph S. Y.
Partner: UNT Libraries Government Documents Department

Downhole Power Generation and Wireless Communications for Intelligent Completions Applications

Description: Tubel Tech has been working with the DoE Rocky Mountain test center to create a CRADA which will allow Tubel Tech to test its wireless gauge in a well at the test center. The CRADA agreement should be completed by the next quarter and Tubel Tech expects to perform the final test on this project during the next quarter as well. The wireless gauge has not been modified or upgraded during this report period.
Date: November 7, 2005
Creator: Tubel, Paul
Partner: UNT Libraries Government Documents Department

Some optics alternatives for the FFS

Description: The evolution of the SLC Final Focus System (FFS) has been discussed in the SLC Red Books and various collider notes. Bulos and Brown and Murray were able to achieve small ..beta..'s with large l/sub 1/'s (the distance between the IP and the effective field boundary of the first quad). However, all current solutions which are compatible with the known constraints of the total path length, aperture and spot size require high gradient, superconducting quads. Such quads cannot be expected to provide very good inherent field quality (i.e., without correction windings) but can be expected to be comparatively expensive to build and operate simply. The purpose of this note is to present a more general solution for the FFS telescope which is compatible with the known constraints of detectors, magnet types, available space and the ingoing and outgoing phase space expectations. While a number of different solutions were found, the ones presented provide comparable performance, simpler operation and lower costs. The gradients are sufficiently low to allow the use of conventional electromagnets, intrinsic or cryostable superconducting or rare earth permanent (REP) magnets or any arbitary combination of all of these magnet types. 8 references, 9 figures, 1 table.
Date: March 7, 1984
Creator: Spencer, J.E.
Partner: UNT Libraries Government Documents Department

Spatial averaging algorithms for ultrasonic inspection of austenitic stainless steel welds

Description: Interpretation of ultrasonic inspection data from stainless steel welds is difficult because the signal-to-noise ratio is very low. The three main reasons for this are the granular structure of the weld, the high attenuation of stainless steel, and electronic noise. Averaging in time at the same position in space reduces electronic noise, but does not reduce ultrasonic noise from grain boundary scattering. Averaging wave-forms from different spatial positions helps reduce grain noise, but desired signals can destructively interfere if they shift in time. If the defect geometry is known, the ultrasonic waveforms can be shifted before averaging, ensuring signal reinforcement. The simplest geometry results in a linear time shift. An averaging algorithm has been developed which finds the optimum shift. This algorithm computes the averaged, or composite waveform as a function of the time shift. The optimum occurs when signals from a reflector become aligned in time, producing a large amplitude composite waveform. This algorithm works very well, but requires significant computer time and storage. This paper discusses this linear shift averaging algorithm, and considers an implementation using frequency domain techniques. Also, data from several weld defects are presented and analyzed.
Date: April 7, 1980
Creator: Horn, J. E.; Cooper, C.S. & Michaels, T.E.
Partner: UNT Libraries Government Documents Department

Effect of Temperature and Electrolyte Composition on the Susceptibility of Alloy 22 to Localized Corrosion

Description: The study of the electrochemical behavior of Alloy 22 has been carried out in various concentrated environments using different sample configurations. Comparisons were made between the electrochemical behaviors of Alloy 22 in concentrated chloride solutions, and in concentrated chloride solutions with nitrate ions (NO{sub 3}{sup -}). In other experiments, the effect of fluoride ions (F{sup -}) was investigated. These comparative studies were performed at various temperatures. The rate of corrosion was found to increase with increase in temperature. The presence of nitrate ions reduced corrosion attack on Alloy 22. F{sup -} was found to be more benign to Alloy 22 compared with chloride ions (Cl{sup -}). However a combination of F{sup -} and Cl{sup -} was found to initiate deeper crevices compared with the only Cl{sup -} in the electrolyte.
Date: October 7, 2002
Creator: Day, S.D.; Evans, K.J. & Ilevbare, G.O.
Partner: UNT Libraries Government Documents Department

Theoretical and observational review of results on nova explosions occurring on ONeMg white dwarfs

Description: The nova outburst is the second most violent explosion that occurs in a galaxy. This review presents the recent observational and theoretical studies that have demonstrated that there exist two classes of nova outburst. One type of nova occurs on a CO white dwarf and the other type of nova occurs on an ONeMg white dwarf. The second class of outbursts are much more violent and occur much more frequently then the first class of outbursts. Hydrodynamic simulations of both kinds of outbursts are in excellent agreement with the observations. 51 refs.
Date: July 7, 1986
Creator: Starrfield, S.
Partner: UNT Libraries Government Documents Department