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Electromagnetic scattering by a two-dimensional inhomogeneity due to an oscillating magnetic dipole

Description: A numerical method of computing the electromagnetic response of two-dimensional earth models to an oscillating magnetic dipole is presented. The generalized electromagnetic variational integral is reduced to a sum of two-dimensional variational integrals by Fourier transformation. Discretization of each two-dimensional integral is carried out in terms of the secondary electric fields by using the finite element method. Following the variational principle, each harmonic integral is reduced to a set of simultaneous equations. From each set of electric field solutions obtained by solving the simultaneous equations, the secondary magnetic fields are computed numerically. After inversely Fourier transforming the secondary electric and magnetic fields, the total fields are finally obtained by adding the analytically calculated primary fields. Because of the systematically implied continuity of the electric field in the finite element solution, the given discontinuous conductivity is modified to a continuous one across internal boundaries. The quality of the solution for the horizontal magnetic dipole is found to be relatively poor compared to that for the vertical magnetic dipole. It is not possible to perform an absolute numerical check of the solution due to the lack of another independently developed solution against which it can be checked. As an alternative the solutions for two-dimensional models were compared to those for some elongated three-dimensional models whose cross sections correspond to the two-dimensional models. 23 figures, 1 table.
Date: September 1, 1978
Creator: Lee, K.H.
Partner: UNT Libraries Government Documents Department

Classification of Geothermal Resources - An engineering approach

Description: Geothermal resources have been classified into low, intermediate and high enthalpy resources by their reservoir temperatures. The temperature ranges used are arbitrary and there is not a general agreement. Geothermal resources should be classified by two independent thermodynamic properties of their fluids at the wellhead. They should reflect the fluids availability to do work. By setting the triple point of water as the sink condition, and normalising the fluids specific exergies by the maximum specific exergy of dry saturated steam, geothermal resources can be classified into high, medium, and low category resources by their specific exergy indices (SEI) of greater than 0.5, between 0.05 and 0.5, and less than 0.05. These correspond to geothermal fluids having exergies greater than that of dry saturated steam at 1 bar absolute, between saturated water and dry saturated steam at 1 bar absolute, and less than saturated water at 1 bar absolute respectively.
Date: January 24, 1996
Creator: Lee, K.C.
Partner: UNT Libraries Government Documents Department

Wilson loop instantons

Description: Wilson Loop symmetry breaking is considered on a spacetime of the form M/sub 4/ x K, where M/sub 4/ is a four dimensional spacetime and K is an internal space with non-trivial and finite fundamental group. We show in a simple model that the different vacua obtained by breaking a non-Abelian gauge group by Wilson loops are separated in the space of gauge potentials by a finite energy barrier. An interpolating gauge configuration between these vacua has been constructed and it has been shown to have minimum energy. Finally, some implications of this construction are discussed.
Date: June 1, 1987
Creator: Lee, K.; Holman, R. & Kolb, E.W.
Partner: UNT Libraries Government Documents Department

Sorption Characteristics of Aqueous Co(II) on Preformed Iron Ferrite Impregnated into Phenolsulphonic Formaldehyde Resin

Description: A series of stepwise procedures to prepare a new organic-inorganic composite magnetic resin with phenolsulphonicformaldehyde and freshly formed iron ferrite was established, based upon wet-and-neutralization method for synthesizing iron ferrite and pearl-polymerization method for synthesizing rigid bead-type composite resin. The composite resin prepared by the above method shows stably high removal efficiency (maximally over 3.1 meq./gresin) to Co(II) species from wastewater in a wide range of solution pH. The wide range of applicable solution pH (i.e. pH 4.09 to 10.32) implies that the composite resin overcomes the limitations of the conventional ferrite process that is practically applicable only to alkaline conditions. It has been found that both ion exchange (by the organic resin constituent) and surface adsorption (by the inorganic adsorbent constituent) are major reaction mechanisms for removing Co(II) from wastewater, but surface precipitation results in the high sorption capacity to Co(II) beyond normal ion exchange capacity of the phenolsulphonic-formaldehyde resin. Standard enthalpy change derived from van't Hoff equation is 32.0 kJ{center_dot}mol-1 conforming to the typical range for chemisorption or ion exchange. In a wide range of equilibrium Co(II) concentration, the overall isotherm is qualitatively explained by the generalized adsorption isotherm concept proposed by McKinley. At the experimental conditions where the composite resin shows equivalent selectivity to Co(II) and other competing reagents (i.e. EDTA and Na), the ratios of Co(II) to other chemicals turn out to be 2:1 and 1:221, respectively. In addition, the selectivity of the PSF-F to Co(II) species is very high (about 72% of Co(II)-removal efficiency) even when the molar ratio of Co(II) to Ca(II) is 1:30. It is anticipated that the composite resin can also be used for column-operation with process-control by applying external magnetic field, since the rigid bead-type composite resin shows magnetic-susceptibility due to its paramagnetic inorganic constituent (i.e. iron ferrite).
Date: February 26, 2002
Creator: Lee, K. J. & Kim, Y. K.
Partner: UNT Libraries Government Documents Department

Progress report on pre-test calculations for the large block test

Description: The U.S. Department of Energy`s (DOE) Yucca Mountain Site Characterization Project (YMP) is investigating the suitability of the Topopah Spring tuff in the thick vadose zone at Yucca Mountain, Nevada, as a host rock for permanent disposal of high-level radioactive waste. As part of the YMP, a group of field tests, referred to as the Large Block Test (LBT), will be conducted on a large electrically heated block of Topopah Spring tuff, isolated at Fran Ridge, Nevada Test Site. The block, which will be 3 x 3 m in horizontal dimensions and 4.5 m in height, will be heated by electrical heaters. The goals of the LBT axe to gain information on the coupled thermal-mechanical-hydrological-chemical processes active in the near-field environment of a repository; to provide field data for testing and calibrating models; and to help the development of measurement systems and techniques. This progress report presents results of on-going numerical modeling calculations carried out in support of the LBT design. An equivalent continuum model with an upper boundary temperature of 60{degrees}C was used to simulate the hydrothermal response of the block to heating over a one-year period. The total heating power was started at 1500 W and later reduced to maintain an approximately uniform temperature of 138-140{degrees}C. For a homogeneous bulk permeability case, the results show the formation of a distinct dry-out zone in and around the heater plane, and well-developed condensation zones above and below the heater plane. For a heterogeneous permeability distribution, the condensation zone above the heater plane was not well developed. This difference in results suggests that water saturation changes might be sensitive to changes in bulk permeability distribution. Rock temperatures were almost unaffected by permeability distribution. Heat flow was dominated by conduction. No liquid flow through the top of the block was predicted.
Date: January 20, 1995
Creator: Lee, K.H.
Partner: UNT Libraries Government Documents Department

Analysis of vadose zone tritium transport from an underground storage tank release using numerical modeling and geostatistics

Description: Numerical and geostatistical analyses show that the artificial smoothing effect of kriging removes high permeability flow paths from hydrogeologic data sets, reducing simulated contaminant transport rates in heterogeneous vadose zone systems. therefore, kriging alone is not recommended for estimating the spatial distribution of soil hydraulic properties for contaminant transport analysis at vadose zone sites. Vadose zone transport if modeled more effectively by combining kriging with stochastic simulation to better represent the high degree of spatial variability usually found in the hydraulic properties of field soils. However, kriging is a viable technique for estimating the initial mass distribution of contaminants in the subsurface.
Date: September 1, 1997
Creator: Lee, K.H.
Partner: UNT Libraries Government Documents Department

Second progress report on pre-test calculations for the large block test

Description: The US Department of Energy`s (DOE) Yucca Mountain Site Characterization Project (YMP) is investigating the suitability of the Topopah Spring tuff in the thick vadose zone at Yucca Mountain, Nevada, as a host rock for permanent disposal of high-level radioactive waste. As part of the YMP, a group of field tests, called the Large Block Test (LBT), will be conducted on a large electrically heated block of Topopah Spring tuff. The block will be heated by electrical heaters. The goals of the LBT are to gain information on the coupled thermal-mechanical-hydrological-chemical processes that will be active in the near-field environment of a repository; to provide field data for testing and calibrating models; and to help in the development of measurement systems and techniques. In this second progress report, we present results of the final set of numerical modeling calculations performed in support of the LBT design. The results include block temperatures and heat fluxes across the surfaces. The results are applied primarily to the design of guard heaters to enforce adiabatic conditions along the block walls. Conduction-only runs are adequate to estimate the thermal behavior of the system, because earlier calculations showed that heat transfer in the block is expected to be dominated by conduction. In addition, conduction-only runs can be made at substantially shorter execution times than full hydrothermal runs. We also run a two-dimensional, hydrothermal, discrete fracture model, with 200-{mu}m vertical fractures parallel to the heaters and occurring at a uniform spacing of 30 cm. The results show the development of distinct dryout and recondensation zones. The dryout zones are thickest at the fractures and thinnest in the matrix midway between the fractures.
Date: November 15, 1995
Creator: Lee, K.H.
Partner: UNT Libraries Government Documents Department

Multifrequency crosshole EM imaging for reservoir characterization. FY 1994 annual report

Description: Electrical conductivity of sedimentary rocks is controlled by the porosity, hydraulic permeability, temperature, saturation, and the pore fluid conductivity. These rock parameters play important roles in the development and production of hydrocarbon (petroleum and natural gas) resources. For these reasons, resistivity well logs have long been used by geologists and reservoir engineers in petroleum industries to map variations in pore fluid, to distinguish between rock types, and to determine completion intervals in wells. Reservoir simulation and process monitoring rely heavily on the physical characteristics of the reservoir model. Over a period of three years (1991-1993) there was an initial phase of crosshole EM technique development via an informal partnership between LLNL and LBL. Researchers developed field instrumentation to apply to oil field for monitoring EOR thermal processes. Specifically, a prototype single-frequency instrumentation was developed and with this system we have conducted field surveys in four separate locations. Theory and software were developed to interpret these data by providing subsurface images of the electrical conductivity. In spite of our initial success in developing practical EM techniques, we still had severe instrumentation limitations and shortcomings in interpretation for other than simple structures. The field equipment was designed to work only at a single frequency at a time and the transmitter must be opened to change frequencies. The equipment was also significantly noiser at higher frequencies. For high-resolution applications we need to take full advantage of the resolution inherent in the data. The development of a high-resolution subsurface conductivity imaging methods would have benefits far beyond the petroleum application. Such techniques would be very useful in environmental applications, mineral and geothermal exploration and for civil engineering applications.
Date: June 1, 1995
Creator: Lee, K.H.
Partner: UNT Libraries Government Documents Department

Choice of steel for the ISABELLE magnet tubes

Description: It is concluded that the low temperature ductility of cast duplex stainless steels can be reduced by high ferrite content, excessive amounts of nitrogen or strong carbide forming elements, and lack of heat treatment particularly at higher ferrite levels. While all samples investigated, with the exception of No. 14 (non-heat treated 12% delta), had mechanical properties more than adequate for the intended service, it was felt advisable to modify the specifications for the tube steels. The requirement is for CF8 as per ASTM specification number A743 with the following modifications: nitrogen content must not exceed 0.08%; niobium content must not exceed 0.1% and total of all carbide formers (Nb, Ti, V, W) must not exceed 0.2%; ferrite content of the casting, as determined from the heat chemistry using the DeLong diagram, must not exceed 10%. A743 already calls for suitable solution heat treatment.
Date: January 1, 1979
Creator: Dew-Hughes, D. & Lee, K.S.
Partner: UNT Libraries Government Documents Department

Hydrogen induced crack growth in Grade-12 titanium

Description: Internal hydrogen induced crack growth rates were measured in Grade-12 titanium which is a candidate material for high-level nuclear waste containers. As-received and hydrogen charged samples (5 ppM to 330 ppM hydrogen) were used for slow crack growth measurements at constant loads using a Krak Gauge. The testing temperature ranged from room temperature to 148/sup 0/C. The crack growth kinetics under low to moderate loads are linear, but this linear rate is interrupted by discrete fast crack jump segments with parabolic or cubic type kinetics. These fast jump segments are thought to be associated with the passage of the crack front through the alpha-beta interface phase or with the initial loading sequence. By measuring striation spacings on the fracture surface, most crack growth rates observed are found to be in stage II. The striations are considered to be associated with hydride fracture. The crack path is either transgranular in the alpha phase or interfacial in the alpha phase adjacent to the beta phase. For transgranular growth, crack growth rates are constant and slower than those for interfacial growth which is associated with fast crack growth through a high hydrogen concentration region. Most stage II crack growth rates depend slightly on the stress intensity suggesting the contribution of plastic tearing process to stage II kinetics. The activation energies for crack growth are much lower than the activation energy of hydrogen diffusion through the alpha phase, implying that hydrogen is transported along dislocations, grain boundaries or interfaces. When the temperature is increased, the crack velocity first reaches a maximum and then decreases at higher temperatures. These temperature effects come from lower hydrogen concentration trapped at dislocations or from slower hydride nucleation kinetics, both at higher temperatures.
Date: January 1, 1984
Creator: Ahn, T.M. & Lee, K.S.
Partner: UNT Libraries Government Documents Department

2-1/2-dimensional numerical solution for the electromagnetic scattering using a hybrid technique

Description: The use of the electromagnetic method for geothermal reservoir exploration and delineation was studied. A number of techniques were developed to provide high quality field data. The remaining problem of interpreting these data in regions of complex geologic structure was overcome by the development of a numerical solution based on the hybrid technique, making use of both the finite element and the integral equation techniques. The major improvement is in the computing speed. (ACR)
Date: March 1, 1983
Creator: Lee, K.H. & Morrison, H.F.
Partner: UNT Libraries Government Documents Department

Explosive double salts and preparation. [Patent application]

Description: A new composition of matter has been discovered which is an explosive addition compound of ammonium nitrate (AN) and diethylenetriamine trinitrate (DETN) in a 50:50 molar ratio. the compound is stable over extended periods of time only at temperatures higher than 46/sup 0/C, decomposing to a fine-grained eutectic mixture (which is also believed to be new) of AN and DETN at temperatures lower than 46/sup 0/C. The compound of the invention has an x-ray density of 1.61 g/cm/sup 3/, explodes to form essentially only gaseous products, has higher detonation properties (i.e., detonation velocity and pressure) than those of any mechanical mixture having the same density and composition as the compound of the invention, is a quite insensitive explosive material, can be cast at temperatures attainable by high pressure steam, and is prepared from inexpensive ingredients. Methods of preparing the compound and the fine-grained eutectic composition of the invention are given.
Date: February 3, 1982
Creator: Cady, H.H. & Lee, K.Y.
Partner: UNT Libraries Government Documents Department

A SOLUTION FOR TM-MODE PLANE WAVES INCIDENT ON A TWO-DIMENSIONAL INHOMOGENEITY

Description: A solution for the electromagnetic fields scattered from a two-dimensional inhomogeneity in a conducting half space has been obtained for an incident TM mode plane wave; the magnetic field is polarized parallel to the strike of the inhomogeneity. The approach has been to determine the scattering currents within the inhomogeneity using an integral equation for the electric fields. This solution is similar in concept to earlier studies of TE mode scattering from two-dimensional inhomogeneities, and it completes the analysis of the scattering of arbitrary plane waves using the integral equation approach. For simple bodies in the earth integral equation solution offers significant computational advantages over alternate finite element or finite difference methods of solution.
Date: March 1, 1980
Creator: Lee, K.H. & Morrision, H.F.
Partner: UNT Libraries Government Documents Department

Implicit two-fluid simulation of electron transport in a plasma erosion opening switch

Description: The two-dimensional implicit code ANTHEM is used to model electron transport in Plasma Opening Switches. We look at low density (approx.4 x 10/sup 12/cm/sup -3/) switches at initial plasma temperatures as low as 5 eV. Two-fluid modeling (ions and electrons with inertia) and implicit determination of the fields is employed to allow time steps well in excess of the inverse plasma period, and cell sizes much larger than a Debye length - with the avoidance of the finite grid anomalous plasma heating characteristic of particle codes. Features indicative of both erosion and E > B plasma drift are manifest in the simulations.
Date: January 1, 1986
Creator: Mason, R.J.; Wallace, J.M. & Lee, K.
Partner: UNT Libraries Government Documents Department

A Study on the Tritium Behavior in the Rice Plant after a Short-Term Exposure of HTO

Description: In many Asian countries including Korea, rice is a very important food crop. Its grain is consumed by humans and its straw is used to feed animals. In Korea, there are four CANDU type reactors that release relatively large amounts of tritium into the environment. Since 1997, KAERI (Korea Atomic Energy Research Institute) has carried out the experimental studies to obtain domestic data on various parameters concerning the direct contamination of plant. In this study, the behavior of tritium in the rice plant is predicted and compared with the measurement performed at KAERI. Using the conceptual model of the soil-plant-atmosphere tritiated water transport system which was suggested by Charles E. Murphy, tritium concentrations in the soil and in leaves to time were derived. If the effect of tritium concentration in the soil is considered, the tritium concentration in leaves is described as a double exponential model. On the other hand if the tritium concentration in the soil is disregarded, the tritium concentration in leaves is described by a single exponential term as other models (e.g. Belot's or STAR-H3 model). Also concentration of organically bound tritium in the seed is predicted and compared with measurements. The results can be used to predict the tritium concentration in the rice plant at a field around the site and the ingestion dose following the release of tritium to the environment.
Date: February 26, 2002
Creator: Yook, D.-S.; Lee, K. J. & Choi, Y-H.
Partner: UNT Libraries Government Documents Department

Air-injection field tests to determine the effect of a heat cycle on the permeability of welded tuff

Description: As part of a series of prototype tests conducted in preparation for site characterization of the potential nuclear-waste repository site at Yucca Mountain, Nevada, air-injection tests were conducted in the welded tuffs in G-Tunnel at the Nevada Test Site. The objectives were to characterize the permeability of the highly fractured tuff around a horizontal heater emplacement borehole, and to determine the effect of a heating and cooling cycle on the rock-mass permeability. Air was injected into packed-off intervals along the heater borehole. The bulk permeability of the rock adjacent to the test interval and the aperture of fractures intersecting the interval were computed from the air-flow rate, temperature, and pressure at steady state. The bulk permeability of intervals along with borehole varied from a minimum of 0.08 D to a maximum of over 144 D and the equivalent parallel-plate apertures of fractures intersecting the borehole varied from 70 to 589 {mu}m. Higher permeabilities seemed to correlate spatially with the mapped fractures. The rock was then heated for a period of 6.5 months with an electrical-resistive heater installed in the borehole. After heating, the rock was allowed to cool down to the ambient temperature. The highest borehole wall temperature measured was 242{degree}C. Air injection tests were repeated following the heating and cooling cycle, and the results showed significant increases in bulk permeability ranging from 10 to 1830% along the borehole. 8 ref., 6 figs., 3 tabs.
Date: October 1, 1991
Creator: Lee, K.H. & Ueng, Tzou-Shin
Partner: UNT Libraries Government Documents Department

The two polymorphs of N-DNAT, a high nitrogen molecule

Description: A novel azo triazole molecule was prepared. Based on X-ray crystallography data, this molecule, 1,1{prime}-dinitro-3,3{prime}-azo-1,2,4-triazole (N-DNAT) exists in two forms. The yellow color polymorph has a crystal density of 1.701 g/cm{sup 3}, while the density of the orange crystal is 1.831 g/cm{sup 3}. Data from specific impulse (Isp) calculation indicates that N-DNAT is a potential candidate for propellant applications.
Date: September 1995
Creator: Lee, K. Y. & Chan, M.
Partner: UNT Libraries Government Documents Department

Field air injection tests to determine the effect of a heat cycle on the permeability of welded tuff

Description: As part of a series of prototype tests conducted in preparation for site characterization at Yucca Mountain, air-injection tests were conducted in the welded tuffs in G-Tunnel at the Nevada Test Site. The objectives were to characterize the permeability of the highly fractured tuff around a horizontal heater emplacement borehole, and to determine the effect of a heating and cooling cycle on the rock-mass permeability. Air was injected into packed-off intervals along the heater borehole. The bulk permeability of the rock adjacent to the test interval was computed from the air-flow rate, temperature, and pressure at steady state. The permeability varied from a minimum of 0.08 D to a maximum of over 144 D. Higher permeabilities seemed to correlate spatially with the mapped fractures. The rock was then heated for a period of 6.5 months with an electrical-resistive heater installed in the borehole. After heating, the rock was allowed to cool down to the ambient temperature. the highest borehole wall temperature measured was 242{degrees}C. Air injection tests were repeated following the heating and cooling cycle, and the results showed significant increases in bulk permeability ranging from 10 to 1830% along the borehole.
Date: October 1, 1991
Creator: Lee, K.H. & Ueng, Tzou-Shin
Partner: UNT Libraries Government Documents Department

Catalogue of magnetotelluric apparent resistivity pseudo-sections over two-dimensional models

Description: As part of the program on geothermal exploration technique evaluation and development, the magnetotelluric method was evaluated in a Basin and Range environment (Beyer et al., 1976). One developement from this effort is an improved two-dimensional magnetotelluric resistivity computer algorithm, called TEM, capable of calculating the transverse electric (TE) and transverse magnetic (TM) soundings over an arbitrary two-dimensional body. Using this program a series of magnetotelluric pseudosections was generated over a set of two-dimensional models which in a gross sense typify structure and resistivities of northern Nevada. This catalogue may be used for qualitative evaluation of existing MT data or for planning future surveys.
Date: August 1, 1978
Creator: Lee, K.H.; Labson, V.; Wilt, M. & Goldstein, N.
Partner: UNT Libraries Government Documents Department

Measurements of electrical conductivity for characterizing and monitoring nuclear waste repositories

Description: The detection of major fractures is one topic of this study but another equally important problem is to develop quantitative relationships between large scale resistivity and fracture systems in rock. There has been very little work done on this central issue. Empirical relations between resistivity and porosity have been derived on the basis of laboratory samples or from well logging, but there are no comparable 'laws' for rock masses with major fracture or joint patterns. Hydrologic models for such rocks have been recently been derived but the corresponding resistivity models have not been attempted. Resistivity due to fracture distributions with preferred orientation could be determined with such models, as could quantitative interpretation of changes as fracture aperature varies with load. This study is not only important for the assessment of a repository site, but has far ranging implications in reservoir studies for oil, gas, and geothermal resources. The electrical conductivity can be measured in two ways. Current can be injected into the ground through pairs of electrodes and corresponding voltage drops can be measured in the vicinity with other pairs of electrodes. The electrical conductivity can also be measured inductively. Instead of injecting current into the ground as described in the dc resistivity method, currents can be induced to flow by a changing magnetic field. In these inductive or electromagnetic (em) methods the interpretation depends both on transmitter-receiver geometry and frequency of operation. In principle the interpretation should be more definitive than with the dc resistivity methods. Rigorous confirmation of this statement in inhomogeneous media awaits the development of generalized inversion techniques for em methods.
Date: November 1, 1986
Creator: Morrison, H.F.; Becker, A. & Lee, K.H.
Partner: UNT Libraries Government Documents Department