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11,791 Matching Results
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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
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
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
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
Performance of the CRID at SLD
This paper describes the performance of a large 4{pi} Cherenkov Ring Imaging Detector (CRID) in the SLD experiment at the SLC at SLAC. We compare the most recent SLD results with those obtained during the R&D period, discuss various design features, and highlight some specific lessons derived from three years of operation.
Date:
June 1, 1993
Creator:
Abe, K.; Antilogus, P. & Aston, D.
Object Type:
Report
System:
The UNT Digital Library
Results from the SLD barrel CRID detector
We report on operational experience with and experimental performance of the SLD barrel Cherenkov Ring Imaging Detector from the 1992 and 1993 physics runs. The liquid (C{sub 6}F{sub 14}) and gas (C{sub 5}F{sub 12}) radiator recirculation systems have performed well, and the drift gas supply system has operated successfully with TMAE for three years. Cherenkov rings have been observed from both the liquid and gas radiators. The number and angular resolution of Cherenkov photons have been measured, and found to be close to design specifications.
Date:
November 1, 1993
Creator:
Abe, K.; Antilogus, P. & Aston, D.
Object Type:
Article
System:
The UNT Digital Library
Scintillating glass fiber neutron sensors: 1, Production and optical characterization
The production and optical characterization of cerium-doped lithium silicate scintillating fibers used as thermal neutron detectors are discussed. The bulk glass continuing enriched {sup 6}Li is produced starting from high-purity commercial materials which are further purified at Pacific Northwest Laboratory (PNL). The fibers are drawn at PNL in a hot down-draw process. The fibers are coated with a silicone polymer that serves as both an optical cladding and a physical buffer coat. Optical characterization has included measurements of light output as a function of glass composition, optical attenuation lengths, and fluorescence lifetimes. Fibers have been prepared in our laboratory with as-drawn attenuation lengths (l/e distance) in excess of 2 meters over sub-meter distances.
Date:
October 1, 1993
Creator:
Abel, K. H.; Arthur, R. J. & Bliss, M.
Object Type:
Article
System:
The UNT Digital Library
Scintillating glass fiber neutron sensors: 2, Light transmission in scintillating fibers
The capture and transmission of light from an event through a scintillating fiber is somewhat different than in conventional optical waveguide applications. A theoretical all-ray model that depends on surface and bulk loss factors is developed for this transmission. The capture fraction can be significantly greater than that predicted on the basis of meridional rays alone and the gross loss is nonexponential for short distances (less than or of the order of one 1/e distance). The latter phenomenon occurs because high-angle and skew rays are more rapidly attenuated than meridional rays.
Date:
October 1, 1993
Creator:
Abel, K. H.; Arthur, R. J. & Bliss, M.
Object Type:
Article
System:
The UNT Digital Library
Scintillating glass fiber neutron sensors: 3, Photon economy in scintillating fibers
In an optical detector such as those constructed from scintillating glass fibers, the photons represent information. This study of the flow of information in a system of devices using PNL glass fibers was undertaken in order to resolve the conflict between expected and observed peak heights. This work concentrates on the number of photons produced and the fraction of photons trapped. It is found that the number of photons produced in bulk samples of the standard glass is about one-third that expected, based on published values; there is evidence that, in fiberized glass, this may be as small as one-fifth the expected value. Additionally, the fraction of trapped photons is found to be about three-fourths that expected because the glass has a smaller refractive index and the cladding a larger refractive index than published values in the spectral region of importance. These factors, taken together, are sufficient to resolve the conflict between the expected and observed peak heights. This analysis provides guidance for those who would use published materials properties to fabricate detectors in a new geometry where the materials properties may have been changed by the fabrication process.
Date:
October 1, 1993
Creator:
Abel, K. H.; Arthur, R. J. & Bliss, M.
Object Type:
Article
System:
The UNT Digital Library
Development of an electrochemical hydrogen separator
The EHS is an electrochemical hydrogen separator based on the uniquely reversible nature of hydrogen oxidation-reduction reactions in electrochemical systems. The principle and the hardware concept are shown in Figure 1. Hydrogen from the mixed gas stream is oxidized to H{sup +} ions, transported through a cation transport electrolyte membrane (matrix) under an applied electric field and discharged in a pure hydrogen state on the cathode. The cation transfer electrolyte membrane provides a barrier between the feed and product gases. The EHS design is an offshoot of phosphoric acid fuel cell development. Although any proton transfer electrolyte can be used, the phosphoric acid based system offers a unique advantage because its operating temperature of {approximately}200{degree}C makes it tolerant to trace CO and also closely matches the water-shift reactor exit gas temperature ({approximately}250{degree}C). Hydrogen-containing streams in coal gasification systems have large carbon monoxide contents. For efficient hydrogen recovery, most of the CO must be converted to hydrogen by the low temperature water-shift reaction (Figure 2). Advanced coal gasification and gas separation technologies offer an important pathway to the clean utilization of coal resources.
Date:
September 1, 1993
Creator:
Abens, S.; Fruchtman, J. & Kush, A.
Object Type:
Article
System:
The UNT Digital Library
Thermal phase behavior of metal surfaces: X-ray scattering studies of Pt(001)
Recent highlights of the results of x-ray scattering studies of the structure and phase behavior of smooth and vicinal Pt(001) surfaces are reviewed.
Date:
November 1, 1993
Creator:
Abernathy, D. L.; Mochrie, S. G. J.; Yoon, M.; Gibbs, D.; Gruebel, G.; Watson, G. M. et al.
Object Type:
Article
System:
The UNT Digital Library
Catalog of Abilene Christian University, 1992-1994
Undergraduate catalog describes the governance, history, course offerings, and campus life of Abilene Christian University in Abilene, Texas.
Date:
June 1, 1993
Creator:
Abilene Christian University
Object Type:
Book
System:
The Portal to Texas History
The role of catalyst precursor anions in coal gasification. Fifth quarterly report
The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a demineralized North Dakota lignite (PSOC 1482) with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. Demineralization of the coal has been completed. In the past quarter, the effects of chloride anion on the surface charge properties of the demineralized coal has been studied using calcium or potassium chlorides. Like the compounds investigated previously, increasing anion concentrations produce less negative charge on the coal surface through the interaction of calcium or potassium ions with the surface. To date, Fourier transform infrared studied aimed at an understanding of the interaction between the metal ions (Ca{sup 2+} or {sup K+}) and the coal surface oxygen functionality has not been very informative, most probably due to the high infrared absorption by coal. For this reason, we have procured a resin, …
Date:
April 1, 1993
Creator:
Abotsi, G. M. K.
Object Type:
Report
System:
The UNT Digital Library
The role of catalyst precursor anions in coal gasification. Seventh quarterly report, April--June 1993
This project investigates the roles of various aqueous soluble catalyst precursor anions, specifically acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}) and carbonate (CO{sub 3}{sup 2{minus}}) anions on the surface electrical properties of coal and seeks to understand the effects of these anions on the adsorption, dispersion and activities of calcium and potassium. In order to investigate the effects of lower anion concentration on calcium or potassium adsorption, aqueous solutions containing 10{sup {minus}3} mol/L of each anion and calcium or potassium were agitated with the acid-leached coal following previously described procedure. Chemical analysis for calcium or potassium shows that metal uptake is substantially reduced compared to metal adsorption from solutions containing higher (10{sup {minus}1} mol/L) anion, and hence metal, concentration. FT-IR studies on the unloaded and the calcium or potassium (using Ca(NO{sub 3}){sub 2} or KNO{sub 3}) exchanged coals gave similar spectra. The remarkable similarity in the spectra for the calcium or potassium loaded coals supports our earlier suggestion that the adsorption mechanism was similar for both metals. Based on zeta potential and adsorption data reported earlier, metal uptake is prodominantly controlled by electrostatic attraction between calcium or potassium ions and the negatively …
Date:
September 1, 1993
Creator:
Abotsi, G. M. K.
Object Type:
Report
System:
The UNT Digital Library
The role of catalyst precursor anions in coal gasification. Sixth quarterly report
This project seeks to understand the roles of various aqueous soluble catalyst precursor anions, specifically acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2}{sup {minus}}) and carbonate (CO{sub 3}{sup 2}{sup {minus}}) anions on the surface electrical properties of coal and to ascertain the effects of the surface charge on the adsorption, dispersion and activities of calcium and potassium. In the foregoing quarter, the effects of nitrate anion on the surface electrochemistry of the demineralized samples of the coal (North Dakota lignite, PSOC 1482) has been conducted using calcium or potassium nitrates. Demineralization increased the negative surface charge density on the coal compared to that on the original unleached sample. However, addition of Ca(NO{sub 3})2 or KNO{sub 3} reduced the negative charge density, the effect is more pronounced with increase in the precursor concentration due to the adsorption of the metal ion onto the coal surface. These results were confirmed by metal adsorption studies, as reported in a previous report. Surface area measurements using nitrogen adsorption and the BET equation shows a 50% reduction in the surface area compared to that of the original coal. This phenomenon is attributed, primarily, to the removal of finely …
Date:
July 1, 1993
Creator:
Abotsi, G. M. K.
Object Type:
Report
System:
The UNT Digital Library