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112
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106
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15,323 Matching Results
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Direct Digital Phase Shift by DDS rf Source
None
Date:
April 13, 1993
Creator:
A., Pei
Object Type:
Report
System:
The UNT Digital Library
Numerically Controlled Phase Locked Loop Using Direct Digital Synthesizer
None
Date:
April 13, 1993
Creator:
A., Pei
Object Type:
Report
System:
The UNT Digital Library
Longitudinal coupling impedance measurements of a bellow at low frequencies
None
Date:
July 1, 1993
Creator:
A., Ratti
Object Type:
Report
System:
The UNT Digital Library
Fundamental studies of fusion plasmas
Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass absorption. Impurity modeling and Faraday screen design support has been provided for the ICRF community. In the area of core-ICRF physics, the kinetic theory of heating by applied ICRF waves has been extended to retain important geometrical effects relevant to modeling minority heated tokamak plasmas, thereby improving on the physics base that is standard in presently employed codes. Both the quasilinear theory of ion heating, and the plasma response function important in wave codes have been addressed. In separate studies, it has been shown that highly anisotropic minority heated plasmas can give rise to unstable field fluctuations in some situations. A completely separate series of studies have contributed to the understanding of tokamak confinement physics. Additionally, a diffraction formalism has been produced which will be …
Date:
April 27, 1993
Creator:
Aamodt, R. E.; Catto, P. J.; D'Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Object Type:
Report
System:
The UNT Digital Library
Fundamental studies of fusion plasmas. Annual performance report
Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass absorption. Impurity modeling and Faraday screen design support has been provided for the ICRF community. In the area of core-ICRF physics, the kinetic theory of heating by applied ICRF waves has been extended to retain important geometrical effects relevant to modeling minority heated tokamak plasmas, thereby improving on the physics base that is standard in presently employed codes. Both the quasilinear theory of ion heating, and the plasma response function important in wave codes have been addressed. In separate studies, it has been shown that highly anisotropic minority heated plasmas can give rise to unstable field fluctuations in some situations. A completely separate series of studies have contributed to the understanding of tokamak confinement physics. Additionally, a diffraction formalism has been produced which will be …
Date:
April 27, 1993
Creator:
Aamodt, R. E.; Catto, P. J.; D`Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Object Type:
Report
System:
The UNT Digital Library
Thomson scattering diagnostic analyses to determine the energetic particle distributions in TFTR
The research completed and in progress for the first period of this grant is reviewed. Specific scattering scenarios for TFTR and JET and ITER were studied. The Lodestar scattering code, SKATR, was upgraded to include anisotropic energetic ion distributions and an analytic diffraction formulation was completed. Research continues on JET studies and upgrading the code for JET and ITER relevant conditions.
Date:
February 12, 1993
Creator:
Aamodt, R. E.; Cheung, P. & Russell, D. A.
Object Type:
Report
System:
The UNT Digital Library
Thomson scattering diagnostic analyses to determine the energetic particle distributions in TFTR. Annual performance report
The research completed and in progress for the first period of this grant is reviewed. Specific scattering scenarios for TFTR and JET and ITER were studied. The Lodestar scattering code, SKATR, was upgraded to include anisotropic energetic ion distributions and an analytic diffraction formulation was completed. Research continues on JET studies and upgrading the code for JET and ITER relevant conditions.
Date:
February 12, 1993
Creator:
Aamodt, R. E.; Cheung, P. & Russell, D. A.
Object Type:
Report
System:
The UNT Digital Library
ICRF heating and current drive in TFTR supershot plasmas: Data analysis and interpretation of ICRF/edge interactions. Research Progress report
The relevance of rf-sheath-plasma interactions to ICRF operation in TFTR has been studied. Screen-screen and screen-limiter rf sheaths have been identified and analyzed for the old and new Bay M geometries on TFIR, including sheath voltages driven by both feeders and the central antenna conductor. Calculations have been carried out to determine the effects of ICRF on edge transport (profile flattening by E {times} B convection), impurity influx ({delta}Z{sub eff}) and edge electron heating (FS glow phenomena) as a function of edge plasma parameters, rf power and antenna phasing. It was found that many of the experimentally observed ICRF-edge plasma interactions on TFIR are consistent with the predictions of rf sheath theory.
Date:
September 22, 1993
Creator:
Aamodt, R. E.; D`Ippolito, D. A. & Myra, J. R.
Object Type:
Report
System:
The UNT Digital Library
Drawdown behavior of gravity drainage wells
An analytical solution for drawdown in gravity drainage wells is developed. The free-surface flow is viewed as incompressible, and anisotropy effects are included. The well is a line source well, and the reservoir is infinitely large. The model is valid for small drawdowns. The uniform wellbore potential inner boundary condition is modelled using the proper Green`s function. The discontinuity at the wellbore is solved by introducing a finite skin radius, and the formulation produces a seepage face. The calculated wellbore flux distribution and wellbore pressures are in fair agreement with results obtained using a numerical gravity drainage simulator. Three distinct flow periods are observed. The wellbore storage period is caused by the moving liquid level, and the duration is short. During the long intermediate flow period, the wellbore pressure is nearly constant. In this period the free surface moves downwards, and the liquid is produced mainly by vertical drainage. At long times the semilog straight line appears. The confined liquid solutions by Theis (1935) and van Everdingen and Hurst (1949) may be used during the pseudoradial flow period if the flowrate is low. New type curves are presented that yield both vertical and horizontal permeabilities.
Date:
October 1, 1993
Creator:
Aasen, J. A. & Ramey, H. J. Jr.
Object Type:
Report
System:
The UNT Digital Library
BIGFLOW: A numerical code for simulating flow in variably saturated, heterogeneous geologic media. Theory and user`s manaual, Version 1.1
This report documents BIGFLOW 1.1, a numerical code for simulating flow in variably saturated heterogeneous geologic media. It contains the underlying mathematical and numerical models, test problems, benchmarks, and applications of the BIGFLOW code. The BIGFLOW software package is composed of a simulation and an interactive data processing code (DATAFLOW). The simulation code solves linear and nonlinear porous media flow equations based on Darcy`s law, appropriately generalized to account for 3D, deterministic, or random heterogeneity. A modified Picard Scheme is used for linearizing unsaturated flow equations, and preconditioned iterative methods are used for solving the resulting matrix systems. The data processor (DATAFLOW) allows interactive data entry, manipulation, and analysis of 3D datasets. The report contains analyses of computational performance carried out using Cray-2 and Cray-Y/MP8 supercomputers. Benchmark tests include comparisons with other independently developed codes, such as PORFLOW and CMVSFS, and with analytical or semi-analytical solutions.
Date:
June 1, 1993
Creator:
Ababou, R. & Bagtzoglou, A. C.
Object Type:
Report
System:
The UNT Digital Library
D{O} results on searches for the top quark
We have performed a search for creation of the top quark in p{bar p} collisions at {radical}s = 1.8 GeV at Tevatron, Fermilab. t{bar t} production followed by top decay to W + b quark is assumed. We have searched for the decay channels with both W`s decaying leptonically, and with one W decay to an electron and the other to quarks. A preliminary report on the status of one interesting event is presented. By combining the results from the ee and e{mu} channels a lower top mass limit of 99 GeV on the 95% confidence level is obtained.
Date:
September 1, 1993
Creator:
Abachi, S.
Object Type:
Article
System:
The UNT Digital Library
Analysis of neon soft x-ray spectra from short-pulse laser-produced plasmas
We report preliminary results from the analysis of streaked soft x-ray neon spectra obtained from the interaction of a picosecond Nd:glass laser with a gas jet target. In these experiments streaked spectra show prompt harmonic emission followed by longer time duration soft x-ray line emission. The majority of the line emission observed was found to originate from Li- and Be-like Ne and the major transitions in the observed spectra have been identified. Li-like emission lines were observed to decay faster in time than Be-like transitions, suggesting that recombination is taking place. Line ratios of n=4-2 and n=3-2 transitions supported the view that these lines were optically thin and thick, respectively. The time history of Li-like Ne 2p-4d and 2p-3d lines is in good agreement with a simple adiabatic expansion model coupled to a time dependent collisional-radiative code. Further x-ray spectroscopic analysis is underway which is aimed at diagnosing plasma conditions and assessing the potential of this recombining neon plasma as a quasi-steady-state recombination x-ray laser medium.
Date:
April 1, 1993
Creator:
Abare, A. C.; Keane, C. J.; Crane, J. K.; DaSilva, L. B.; Lee, R. W.; Perry, M. D. et al.
Object Type:
Article
System:
The UNT Digital Library
An engineering and economic evaluation of the methane de-NOX{sup SM} technology
The Institute of Gas Technology (IGT) and Ogden Martin Systems, Inc. (OMS) are conducting joint engineering and economic evaluation of IGT`s METHANE de-NOX{sup SM} technology for its application to new, as well as retrofit, municipal waste combustors (MWCs). It is anticipated that this new technology offers a technically and economically attractive alternative to existing selective noncatalytic reduction (SNCR) systems for new facilities, as well as in retrofit applications. Consequently, IGT and OMS are considering pursuing a long-term demonstration of this technology on an OMS MWC. The METHANE de-NOX approach was developed based on extensive full-scale MWC infurnace characterization and pilot-scale testing using simulated combustion products. The approach involves injection of natural gas, together with recirculated flue gases (for mixing), above the grate to provide oxygen-deficient combustion conditions that promote the destruction of NO{sub x} precursors, as well as NO{sub x}. Extensive pilot-scale testing, using both simulated combustion products and actual municipal waste (MW), showed that significant NO{sub x} reduction could be achieved. The results were used to define the key operating parameters for a field evaluation of the process. A full-scale METHANE de-NOX system was designed and retrofitted to a 100-ton/day Riley/Takuma mass burn system at the Olmsted County Waste-to-Energy …
Date:
December 31, 1993
Creator:
Abbasi, H. A.; Khinkis, M. J. & Scherrer, R.
Object Type:
Report
System:
The UNT Digital Library
Stabilization of spent sorbents from coal gasification. Final technical report, September 1, 1992--August 31, 1993
The objective of this investigation was to determine the rates of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite were reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor. The effect of external diffusion was eliminated by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents were analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. The results of sulfation tests indicate that the rate of reaction increases with increasing temperature, increasing oxygen partial pressure, and decreasing sorbent particle size. The rate of the sulfation reaction can be described by a diffuse interface model where both chemical reaction and intraparticle diffusion control the reaction rate. The kinetic model of the sulfation reaction was used to determine the requirements for the reactor system, i.e., reactor size and operating conditions, for successful stabilization of sulfide-containing solid wastes from gasification of high sulfur …
Date:
December 31, 1993
Creator:
Abbasian, J.; Hill, A. H.; Rue, D. M. & Wangerow, J. R.
Object Type:
Report
System:
The UNT Digital Library
Stabilization of spent sorbents from coal gasification. Technical report, December 1, 1992--February 28, 1993
The objective of this investigation is to determine the kinetics of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite are reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor, where external diffusion limitations are avoided by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents are analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. Samples of the partially sulfided dolomite were reacted with oxygen in the fluidized-bed rector at different operating conditions. The test parameters included the effects of solid residence time, oxygen concentration, and reaction temperature. The reacted solids were analyzed to determine the extent of CaS conversion to CaSO{sub 4}. The results of the tests conducted so far in the project indicate that the extent of conversion increase with increasing oxygen concentration and the solid residence time. The rate of reaction appears to be very sensitive to …
Date:
May 1, 1993
Creator:
Abbasian, J.; Hill, A. H.; Wangerow, J. R. & Banerjee, D. D.
Object Type:
Report
System:
The UNT Digital Library
Issues related to EM management of DOE spent nuclear fuel
This document is a summary of the important issues involved in managing spent nuclear fuel (SNF) owned by the Department of Energy (DOE). Issues related to civilian SNF activities are not discussed. DOE-owned SNF is stored primarily at the Hanford Site, Idaho National Engineering Laboratory (INEL), Savannah River Site (SRS), Oak Ridge National Laboratory (ORNL), and West Valley Demonstration Project. Smaller quantities of SNF are stored at Brookhaven National Laboratory, Sandia National Laboratories, and Los Alamos National Laboratory (LANL). There is a wide variety of fuel types, including both low and high enrichment fuels from weapons production, DOE reactors, research and development programs, naval programs, and universities. Most fuel is stored in pools associated with reactor or reprocessing facilities. Smaller quantities are in dry storage. Physical conditions of the fuel range from excellent to poor or severely damaged. An issue is defined as an important question that must be answered or decision that must be made on a topic or subject relevant to achieving the complimentary objectives of (a) storing SNF in compliance with applicable regulations and orders until it can be disposed, and (b) safely disposing of DOE`s SNF. The purpose of this document is to define the issues; …
Date:
July 1993
Creator:
Abbott, D. G.; Abashian, M. S.; Chakraborti, S.; Roberson, K. & Meloin, J. M.
Object Type:
Report
System:
The UNT Digital Library
New technologies for item monitoring
This report responds to the Department of Energy`s request that Sandia National Laboratories compare existing technologies against several advanced technologies as they apply to DOE needs to monitor the movement of material, weapons, or personnel for safety and security programs. The authors describe several material control systems, discuss their technologies, suggest possible applications, discuss assets and limitations, and project costs for each system. The following systems are described: WATCH system (Wireless Alarm Transmission of Container Handling); Tag system (an electrostatic proximity sensor); PANTRAK system (Personnel And Material Tracking); VRIS (Vault Remote Inventory System); VSIS (Vault Safety and Inventory System); AIMS (Authenticated Item Monitoring System); EIVS (Experimental Inventory Verification System); Metrox system (canister monitoring system); TCATS (Target Cueing And Tracking System); LGVSS (Light Grid Vault Surveillance System); CSS (Container Safeguards System); SAMMS (Security Alarm and Material Monitoring System); FOIDS (Fiber Optic Intelligence & Detection System); GRADS (Graded Radiation Detection System); and PINPAL (Physical Inventory Pallet).
Date:
December 1, 1993
Creator:
Abbott, J. A. & Waddoups, I. G.
Object Type:
Report
System:
The UNT Digital Library
Comparison of a constraint directed search to a genetic algorithm in a scheduling application
Scheduling plutonium containers for blending is a time-intensive operation. Several constraints must be taken into account; including the number of containers in a dissolver run, the size of each dissolver run, and the size and target purity of the blended mixture formed from these runs. Two types of algorithms have been used to solve this problem: a constraint directed search and a genetic algorithm. This paper discusses the implementation of these two different approaches to the problem and the strengths and weaknesses of each algorithm.
Date:
April 1, 1993
Creator:
Abbott, L.
Object Type:
Article
System:
The UNT Digital Library
A nonlinear dynamic model of a once-through, helical-coil steam generator
A dynamic model of a once-through, helical-coil steam generator is presented. The model simulates the advanced liquid metal reactor superheated cycle steam generator with a four-region, moving-boundary, drift-flux model. The model is described by a set of nonlinear differential equations derived from the fundamental equations of conversation of mass, energy, and momentum. Sample results of steady-state and transient calculations are presented.
Date:
July 1, 1993
Creator:
Abdalla, M. A.
Object Type:
Report
System:
The UNT Digital Library
Multiphoton physics with x-rays: Two photon K-shell ionization of chlorine
A calculation of the two X-ray K-shell photoionization cross section of chlorine will be presented and the feasibility of an experiment will be discussed.
Date:
January 1, 1993
Creator:
Abdallah, J.; Collins, L. A.; Csanak, G.; Kyrala, G. A. & Schappert, G. T.
Object Type:
Article
System:
The UNT Digital Library
Multiphoton physics with x-rays: Two photon K-shell ionization of chlorine
A calculation of the two X-ray K-shell photoionization cross section of chlorine will be presented and the feasibility of an experiment will be discussed.
Date:
April 1, 1993
Creator:
Abdallah, J.; Collins, L. A.; Csanak, G.; Kyrala, G. A. & Schappert, G. T.
Object Type:
Article
System:
The UNT Digital Library
Superconducting magnet design for Fixed-Field Alternating-Gradient (FFAG) accelerator
The FFAG accelerator requires static fields that increase with radius along the accelerator midplane according to B = B{sub 0} (R/R{sub 0}){sup 13.4}. The field is generated by equally spaced magnets around the circumference and varies from a maximum of 4.1 T to a minimum of {minus}1.9 T. The general coil design employs cryostable magnets wound with aluminum stabilized superconductor. Each magnet has resistive pole face windings outside of the cryostat to allow for field fine tuning after construction. A set of iron-free coil windings generate the required field distribution.
Date:
November 1, 1993
Creator:
Abdelsalam, M. & Kustom, R.
Object Type:
Article
System:
The UNT Digital Library
Analytical steam injection model for layered systems
Screening, evaluation and optimization of the steam flooding process in homogeneous reservoirs can be performed by using simple analytical predictive models. In the absence of any analytical model for layered reservoirs, at present, only numerical simulators can be used. And these are expensive. In this study, an analytical model has been developed considering two isolated layers of differing permeabilities. The principle of equal flow potential is applied across the two layers. Gajdica`s (1990) single layer linear steam drive model is extended for the layered system. The formulation accounts for variation of heat loss area in the higher permeability layer, and the development of a hot liquid zone in the lower permeability layer. These calculations also account for effects of viscosity, density, fractional flow curves and pressure drops in the hot liquid zone. Steam injection rate variations in the layers are represented by time weighted average rates. For steam zone calculations, Yortsos and Gavalas`s (1981) upper bound method is used with a correction factor. The results of the model are compared with a numerical simulator. Comparable oil and water flow rates, and breakthrough times were achieved for 100 cp oil. Results with 10 cp and 1000 cp oils indicate the need …
Date:
August 1, 1993
Creator:
Abdual-Razzaq; Brigham, W. E. & Castanier, L. M.
Object Type:
Report
System:
The UNT Digital Library
Computer simulation on the linear and nonlinear propagation of the electromagnetic waves in the dielectric media
In this Letter, we first present a new computer simulation model developed to study the propagation of electromagnetic waves in a dielectric medium in the linear and nonlinear regimes. The model is constructed by combining a microscopic model used in the semi-classical approximation for the dielectric media and the particle model developed for the plasma simulations. The model was then used for studying linear and nonlinear wave propagation in the dielectric medium such as an optical fiber. It is shown that the model may be useful for studying nonlinear wave propagation and harmonics generation in the nonlinear dielectric media.
Date:
August 1993
Creator:
Abe, H. & Okuda, H.
Object Type:
Report
System:
The UNT Digital Library