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Second-generation pressurized fluidized bed combustion

Description: Under the sponsorship of the United States Department of Energy, Foster Wheeler Corporation is developing second-generation pressurized fluidized bed combustion (PFBC) power plant technology that will enable this type of plant to operate with net plant efficiencies in the range of 43 to 46 percent (based on the higher heating value of the coal), with a reduction in the cost of electricity of at least 20 percent. A three-phase program is under way. Its scope encompasses the conceptual design of a commercial plant through the process of gathering needed experimental test data to obtain design parameters.
Date: May 1, 1992
Creator: Wolowodiuk, W. & Robertson, A.
Partner: UNT Libraries Government Documents Department

Study of the combustion of low rank coal in a fluidized bed

Description: This report describes the results of preliminary combustion tests performed with Eagle Butte Coal in a bubbling, fluidized-bed combustion system. The system was designed for the combustion of low-rank coals and industrial wastes. The work, as proposed, was aimed at not only the evaluation of co-firing of waste material with coal, but also at developing modifications to first generation bubbling bed designs to improve the combustion performance during co-firing. However, the funding for the work was redirected and the combustion tests were suspended soon after the shakedown testing was completed. Consequently, this report describes the results of the tests completed prior to the redirection of the effort and funding. A total of 33 combustion tests were performed in a 6-inch diameter fluidized-bed combustor. Oxygen concentrations were measured at two points in the system; the vent line and at the interface between the fluid bed and the freeboard. These measurements provided a measure of the amount of conversion of coal within the fluidized bed compared to the conversion in the freeboard region. Typically, 75 to 80% of the conversion occurred within the bed. Several experiments were performed in which special bed internals were placed in the bed. The internals were designed to reduce bubble size in the bed thus increasing the surface area of the bubbles and hence promoting oxygen diffusion into the emulsion phase.
Date: September 1, 1991
Creator: Glaser, R. & Grimes, R. W.
Partner: UNT Libraries Government Documents Department

Pulsed atmospheric fluidized bed combustion. Quarterly technical progress report, October 1992--December 1992

Description: The Design and Engineering of most components in the Pulsed Atmospheric Fluidized Bed System was completed prior to September 1992. The components remaining to be designed at that time were: Aerovalves for the Pulse Combustor; Gas and coal injectors for the Pulse Combustor; Lines for PC tailpipes; Air plenum and inlet silencer; Refractory lined hot gas duct connecting outlet hot cyclone to boiler; Structure and platforms, and ladders around PAFBC vessel access and major equipment. Design work is currently in progress on all of the above components. Items 1, 2, 3 and 4 are 50% completed, and items 5 & 6 are 75% complete.
Date: January 1, 1993
Partner: UNT Libraries Government Documents Department

Pulsed Atmospheric Fluidized Bed Combustion. Technical Progress Report, July 1993--September 1993

Description: This quarterly report is broken down between design and the status of the fabrication work being performed. The design section is divided between the following sections: Site layout, foundation design, structural design, piping design, pulse combustor components, and electrical & instrumentation design. As reported in the last quarterly report the location area of the PAFBC in the Clemson Energy Facility was inspected with a view to finalize the layout of the PAFBC plant. Some adjustments were made to the layout to accommodate Clemson University`s requirements and the available space. The most important changes are that the boiler and economizer were relocated in the structure above ground level in order to reduce the size of the footprint of the plant. Figure 1 is the plan view of the current layout. Figures 2 through 6 present different elevation views of the layout. The design of foundations for the entire plant is currently being executed by Industra Engineers Inc. of Greenville, SC. The different weights of various equipment located close to each other precludes the provision of independent foundations for each piece of equipment. One monolithic foundation platform for the whole area proves to be more economical for the current layout. In this quarter the design of the plant structures was completed. The drawings were sent out for expert review and approval. The drawings at this stage present complete structural and platform layout requirements. Changes will be made to various structural members based on the structural review and then detailed drawings of joint design and fabrication cutting plans will be prepared and issued for fabrication.
Date: October 30, 1993
Partner: UNT Libraries Government Documents Department

Pulsed atmospheric fluidized bed combustion. Technical progress report, January--March 1994

Description: Industra has completed design of the structure which surrounds the fluidized bed. Details regarding their efforts are discussed below. Duke/Fluor Daniel has begun overall design review and will provide comments and recommendations early in the second quarter. Foundation and control room design are complete. Drawings have been submitted to Clemson University and bids have been requested from vendors. Structural design is complete and drawings have been submitted for bids. Industra has reviewed design of the bin structures and has provided recommendations for minor additions to them. Revisions have been made to the structure and are described.
Date: April 29, 1994
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, January 1, 1994--March 31, 1994

Description: Laboratory combustion tests conducted this quarter support the hypothesis that localized reducing conditions promote formation of agglomerates in the bed of fluidized bed boilers. These tests were designed to simulate localized reducing conditions found in commercial fluidized bed combustors. Localized reducing conditions may occur from either poor lateral bed mixing or oxygen-starved bed conditions due to the coal feed configuration. It was found-that agglomeration can occur at lower theoretical air values while operating temperatures are within the range of fluidized bed boilers. Cohesion of bed particles appears to take place very rapidly when theoretical air in the bed approaches 70%. These tests also indicate that bed temperature, pressure drop, oxygen and carbon dioxide concentrations are affected by agglomeration. Agglomeration appears to result in: (1) An increase in the frequency of pressure fluctuations (bed pressure drop). (2) An increase in the magnitude of pressure fluctuations (bed pressure drop.) (3) A possible decrease in bed pressure differential over time. In addition, there appears to be an increase in the amount of available oxygen and a decrease in CO{sub 2}. Agglomerates formed in the laboratory are being subjected to mineralogical analyses which will then be compared to similar analyses of agglomerates removed from commercial boilers.
Date: April 1, 1994
Creator: Brown, R. C.; Dawson, M. R. & Smeenk, J. L.
Partner: UNT Libraries Government Documents Department

Interpretation of pilot-scale, fluidized bed behavior using chaotic time series analysis

Description: In this paper, we apply conventional and chaotic time series analyses to the interpretation of pressure-drop measurements from a 250 kW, pilot-scale, bubbling fluidized bed combustor. Our results demonstrate that such analyses can be useful for discriminating different types of fluidization in a practical combustor and offer a basis for improving fluidized bed monitoring and control. A new comparative index that reflects the multivariate structure in pressure-drop measurements is proposed for detecting variations in the fluidized state. We also propose standards for acquiring fluidized bed pressure-drop measurements in pilot and commercial-scale facilities as well as three potential commercial uses. Recent findings regarding the effect of pressure tap location and design on the measured signal fidelity are discussed.
Date: June 1, 1993
Creator: Fuller, T. A.; Flynn, T. J.; Daw, C. S. & Halow, J. S.
Partner: UNT Libraries Government Documents Department

Market Assessment and Demonstration of Lignite FBC Ash Flowable Fill Applications

Description: Montana-Dakota Utilities (MDU) and Western Research Institute (WRI) have been developing flowable fill materials formulated using ash from the Montana-Dakota Utilities R. M. Heskett Station in Mandan, North Dakota. MDU and WRI have partnered with the U.S. Department of Energy (DOE) and the North Dakota Industrial Commission (NDIC) to further the development of these materials for lignite-fired fluidized-bed combustion (FBC) facilities. The MDU controlled density fill (CDF) appears to be a viable engineering material and environmentally safe. WRI is pursuing the commercialization of the technology under the trademark Ready-Fill{trademark}. The project objectives were to: (1) assess the market in the Bismarck-Mandan area; (2) evaluate the geotechnical properties and environmental compatibility; and (3) construct and monitor demonstrations of the various grades of flowable fill products in full-scale demonstrations. The scope of initial phase of work entailed the following: Task I--Assess Market for MDU Flowable Fill Products; Task II--Assess Geotechnical and Environmental Properties of MDU Flowable Fill Products; and Task III--Demonstrate and Monitor MDU Flowable Fill Products in Field-Scale Demonstrations. The results of these testing and demonstration activities proved the following: (1) The market assessment indicated that a market exists in the Bismarck-Mandan area for structural construction applications, such as sub-bases for residential and commercial businesses, and excavatable fill applications, such as gas line and utility trench filling. (2) The cost of the MDU flowable fill product must be lower than the current $35-$45/cubic yard price if it is to become a common construction material. Formulations using MDU ash and lower-cost sand alternatives offer that opportunity. An estimated market of 10,000 cubic yards of MDU flowable fill products could be realized if prices could be made competitive. (3) The geotechnical properties of the MDU ash-based flowable fill can be modified to meet the needs of a range of applications from structural fill ...
Date: September 30, 2003
Creator: Bland, Alan E.
Partner: UNT Libraries Government Documents Department

Study of the State-of-the-Art of Instrumentation for Process Control and Safety in Large-Scale Coal Gasification, Liquefaction, and Fluidized-Bed Combustion Systems

Description: A study has been carried out to determine the state-of-the-art of instrumentation which is available for process control and safety in planned demonstration and commercial scale coal gasification, liquefaction, and fluidized-bed combustion systems. The study identified available instrumentation which will perform satisfactorily in these systems and pinpointed deficiencies for which instruments must be developed. The identified deficiencies fall into the same few categories for all processes considered. These categories are presented with associated physical parameters found in the various processes studied. Development of instruments to meet these deficiencies is recommended along with development of control valves and optimal control schemes in order to assure the possibility of automatic control of the large scale coal conversion and combustion systems.
Date: 1976
Creator: O'Fallon, N. M.; Beyerlein, R. A.; Managan, W. W.; Karplus, H. B. & Mulcahe, T. P.
Partner: UNT Libraries Government Documents Department

High-Tempepature Oxidation and Corrosion of Materials Program

Description: The objective of this program is to gain an understanding of the corrosion chemistry and materials behavior in high temperature environments. Of particular interest are the mechanisms of attack in environments containing more than one reactive species, for example sulfur and oxygen. Sulfur is a critical impurity in almost all energy sources and leads to accelerated, and often unacceptable rates of metal degradation. In addition, the competitive formation of potentially more than one phase as a reaction product is an important fundamental problem, and can only be truly understood if the underlying thermodynamic and transport properties of the systems, and their interrelation, are identified. Sulfur can appear in a number of forms. In entirely gaseous environments it can appear as H{sub Z}S when the oxidizing potential of the atmosphere is low, such as might exist in energy conversion systems, or as SO{sub 2}/SO{sub 3} at higher oxygen potentials, such as those produced by fuel combustion. It may also appear in sulfatic deposits, either as a solid, such as CaSO{sub 4} in fluidized bed combustion systems, as inorganic and organic sulfur compounds in coal char, or as a liquid alkali-metal sulfate in coal-ash, or turbine-blade deposits. This last year has been spent primarily in establishing the typical behavioral patterns of common materials in these types of environments, and identifying the common mechanisms. In addition, development of definitive models of alloy reactions with single oxidants has continued. The individual projects are described.
Date: March 1, 1980
Creator: Whittle, D. P.
Partner: UNT Libraries Government Documents Department

The role of pore structure on char reactivity. Quarterly progress report, April 1995--June 1995

Description: In order to examine the role of pore structure, studies will be conducted on coal chars in the electrodynamic balance. Larger particles will also be examined using a fluidized bed to examine diffusion control reactions, and soots will also be investigated to examine the role of meso-and micro-pores without macro-pore interference. These studies will allow a full range of particles sizes and temperatures to be investigated and eventually modelled.
Date: July 1, 1995
Creator: Sarofim, A. F.
Partner: UNT Libraries Government Documents Department

A new approach to studying pore evolution during char combustion at FBC conditions

Description: A new technique of studying pore structure evolution during fluidized bed combustion of char has been developed. Evolution of nitrogen oxides during char combustion have been found to be very sensitive towards changes in pore diffusivities. For a non-porous particle, nitric oxide is formed largely at the surface of the particle and diffuses out of the pores before it is destroyed. On the other hand, nitric oxide is formed and destroyed throughout a porous particle resulting in lower conversions of char nitrogen to NO. The instantaneous conversion of char nitrogen to NO is very sensitive towards changes in pore structure. N{sub 2}O which is formed by the reaction of NO with char nitrogen can also be used as an indicator for studying changes in pore diffusivity during combustion. Since ambient NO levels and pore diffusivity determine the diffusion of NO into or out of the particle, NO concentration within the particle affects the trends in the N{sub 2}O formation with changing carbon conversion. This effect is due to the changes in pore diffusivity and the pore diffusion length as the char particle burns. By fitting the model to the experimental data, mesopores were found to control the pore diffusivity of the reacting species, and, hence, the location of heterogeneous reactions occurring inside the pores.
Date: February 1, 1997
Creator: Goel, S. & Sarofim, A. F.
Partner: UNT Libraries Government Documents Department

Combustion of municipal solid wastes with oil shale in a circulating fluidized bed. Quarterly report ending March 31, 1996

Description: This document contains a progress report for the Project Description of Grant No. DE-FG01-94CE15612, {open_quotes}Develop a Combustion of Municipal Solid Waste with Oil Shale in Circulating Fluidized Bed{close_quotes}, dated September 2, 1994. The Project Description lists and describes six tasks, four of which are complete, and two others nearing completion. A summary of progress on each task is presented in this report.
Date: April 1, 1996
Partner: UNT Libraries Government Documents Department

High volume-high value usage of flue gas desulfurization (FGD) by- products in underground mines. Quarterly report, April 1--June 30, 1996

Description: The target for the project has been shifted from filling, highwall mine adits to filling auger holes with FGD material to provide a stable highwall for automated highwall mining. As reported previously, this shift in emphasis is economically desirable and practical, as the filling operation is safer and permits access to ``locked in`` high quality coal behind existing auger holes. As also reported previously, the fill material was shifted from dry FGD materials to a Fluidized Bed Combustion fly ash from the Archer Daniel Midland No. 6 facility in Illinois. Previous reports have summarized the characterization of this material for the project. However, due mostly to economic concerns with prehydration and transport of the Archer Daniel Midland (ADM6) material, several new desulfurization by-products stored at the Costain facility in Allen, Kentucky were considered during, this quarter. At this stage of the project, the change in fill material required rapid assessment in much the same way an applied working project would demand quick evaluation. This change thus provided an opportunity to demonstrate a rapid assessment of material suitability. The results described below were obtained in a short time frame, and with the exception of characterizing the long term swell and durability of the products, the rapid assessment was a success. No rapid assessment methodology for long term behavior has been developed at this time. The mineralogical characteristics of the two Costain materials will not be summarized in detail here. Unlike the ADM6 ash, the spray dryer and FBC materials currently under review do not include the large percentages of free lime (CaO) that was shown to cause high mixing temperatures in the nonprehydrated ADM6 product. This absence of free lime in the raw by-products is immediately evident when mixing with water, as no significant heating of the mixture is observed.
Date: December 31, 1996
Partner: UNT Libraries Government Documents Department

Design and Initial Development of Monolithic Cross-Flow Ceramic Hot-Gas Filters

Description: Advanced, coal-fueled, power generation systems utilizing pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycle (IGCC) technologies are currently being developed for high-efficiency, low emissions, and low-cost power generation. In spite of the advantages of these promising technologies, the severe operating environment often leads to material degradation and loss of performance in the barrier filters used for particle entrapment. To address this problem, LoTEC Inc., and Oak Ridge National Laboratory are jointly designing and developing a monolithic cross-flow ceramic hot-gas filter. The filter concept involves a truly monolithic cross-flow design that is resistant to delamination, can be easily fabricated, and offers flexibility of geometry and material make-up. During Phase I of the program, a thermo-mechanical analysis was performed to determine how a cross-flow filter would respond both thermally and mechanically to a series of thermal and mechanical loads. The cross-flow filter mold was designed accordingly, and the materials selection was narrowed down to Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24} (CS-50) and 2Al{sub 2}O{sub 3}-3SiO{sub 2} (mullite). A fabrication process was developed using gelcasting technology and monolithic cross-flow filters were fabricated. The program focuses on obtaining optimum filter permeability and testing the corrosion resistance of the candidate materials.
Date: June 6, 1999
Creator: Barra, C.; Limaye, S.; Stinton, D.P. & Vaubert, V.M.
Partner: UNT Libraries Government Documents Department

Capture of toxic metals by vaious sorbents during fluidized bed coal combustion

Description: This study investigated the potential of employing suitable sorbents to capture trace metallic substances during fluidized bed coal combustion. The objectives of the study were to demonstrate the capture process, identify effective sorbents, and characterize the capture efficiency. Experiments were carried out in a 25.4 mm (1 ``) quartz fluidized bed coal combustor enclosed in an electric furnace. In an experiment, a coal sample from the DOE Coal Sample Bank or the Illinois Basin Coal Sample Bank was burned in the bed with a sorbent under various combustion conditions and the amount of metal capture by the sorbent was determined. The metals involved in the study were arsenic, cadmium, lead, mercury and selenium, and the sorbents tested included bauxite, zeolite and lime. The combustion conditions examined included bed temperature, particle size, fluidization velocity (percent excess air), and sorbent bed height. In addition to the experimental investigations, potential metal-sorbent reactions were also identified through performing chemical equilibrium analyses based on the minimization of system free energy.
Date: December 31, 1995
Creator: Ho, T.C.; Ghebremeskel, A. & Hopper, J.R.
Partner: UNT Libraries Government Documents Department

Filter Component Assessment

Description: Advanced particulate filtration systems are currently being developed at Westinghouse for use in both coal-fired Integrated Gasification Combined Cycle (IGCC) and Pressurized Fluidized Bed Combustion (PFBC) systems. To date, Westinghouse has demonstrated 5855 hours of successful operation of first generation monolithic filter elements in PFBC applications when ash bridging or process thermal transient excursions are avoided. Alternate advanced monolithic and second generation fiber reinforced, filament wound and vacuum infiltrated filters are also being developed which are considered to have enhanced high temperature creep resistance, improved fracture toughness, or enhanced thermal shock characteristics, respectively. Mechanical and component fabrication improvements, as well as degradation mechanisms for each filter element have been identified by Westinghouse during exposure to simulated PFBC operating conditions and alkali-containing steam/air environments. Additional effort is currently being focused on determining the stability of the advanced monolithic high temperature creep resistant clay bonded silicon carbide (SiC) materials, alumina/mullite, and chemically vapor infiltrated (CVI) SiC materials during operation in the Westinghouse Advanced Particulate Filtration (W-APF) system at Foster Wheeler`s pressurized circulating fluidized-bed combustion (PCFBC) test facility in Karhula, Finland. Select advanced filter materials are being defined for additional long-term exposure in integrated gasification combined cycle (IGCC) gas streams. The results of these efforts are summarized in this paper. 6 refs., 7 figs., 11 tabs.
Date: December 31, 1996
Creator: Alvin, M.A.; Lippert, T.E.; Diaz, E.S. & Smeltzer, E.E.
Partner: UNT Libraries Government Documents Department

OPTIMIZATION OF ADVANCED FILTER SYSTEMS

Description: Reliable, maintainable and cost effective hot gas particulate filter technology is critical to the successful commercialization of advanced, coal-fired power generation technologies, such as IGCC and PFBC. In pilot plant testing, the operating reliability of hot gas particulate filters have been periodically compromised by process issues, such as process upsets and difficult ash cake behavior (ash bridging and sintering), and by design issues, such as cantilevered filter elements damaged by ash bridging, or excessively close packing of filtering surfaces resulting in unacceptable pressure drop or filtering surface plugging. This test experience has focused the issues and has helped to define advanced hot gas filter design concepts that offer higher reliability. Westinghouse has identified two advanced ceramic barrier filter concepts that are configured to minimize the possibility of ash bridge formation and to be robust against ash bridges should they occur. The ''inverted candle filter system'' uses arrays of thin-walled, ceramic candle-type filter elements with inside-surface filtering, and contains the filter elements in metal enclosures for complete separation from ash bridges. The ''sheet filter system'' uses ceramic, flat plate filter elements supported from vertical pipe-header arrays that provide geometry that avoids the buildup of ash bridges and allows free fall of the back-pulse released filter cake. The Optimization of Advanced Filter Systems program is being conducted to evaluate these two advanced designs and to ultimately demonstrate one of the concepts in pilot scale. In the Base Contract program, the subject of this report, Westinghouse has developed conceptual designs of the two advanced ceramic barrier filter systems to assess their performance, availability and cost potential, and to identify technical issues that may hinder the commercialization of the technologies. A plan for the Option I, bench-scale test program has also been developed based on the issues identified. The two advanced barrier filter systems ...
Date: April 30, 1998
Creator: Newby, R.A.; Bruck, G.J.; Alvin, M.A. & Lippert, T.E.
Partner: UNT Libraries Government Documents Department

Particulate Control Device (PCD) Testing at the Power Systems Development Facility, Wilsonville, Alabama

Description: One of the U.S. Department of Energy`s (DOE`s) objectives overseen by the Morgantown Energy Technology Center (METC) is to test systems and components for advanced coal-based power generation systems, including integrated gasification combined cycle (IGCC), pressurized fluidized-bed combustion (PFBC), and integrated gasification/fuel cell (IGFC) systems. Stringent particulate requirements for fuel gas for both combustion turbines and fuel cells that are integral to these systems. Particulates erode and chemically attack the blade surfaces in turbines, and cause blinding of the electrodes in fuel cells. Filtration of the hot, high-pressure, gasified coal is required to protect these units. Filtration can be accomplished by first cooling the gas, but the system efficiency is reduced. High-temperature, high-pressure, particulate control devices (PCDs) need to be developed to achieve high efficiency and to extend the lifetime of downstream components to acceptable levels. Demonstration of practical high-temperature PCDs is crucial to the evolution of advanced, high-efficiency, coal-based power generation systems. The intent at the Power Systems Development Facility (PSDF) is to establish a flexible test facility that can be used to (1) develop advanced power system components, such as high-temperature, high-pressure PCDs; (2) evaluate advanced power system configurations and (3) assess the integration and control issues of these advanced power systems.
Date: December 1, 1995
Creator: Longanbach, J.R.
Partner: UNT Libraries Government Documents Department

Iterative prediction of chaotic time series using a recurrent neural network. Quarterly progress report, January 1, 1995--March 31, 1995

Description: Chaotic systems are known for their unpredictability due to their sensitive dependence on initial conditions. When only time series measurements from such systems are available, neural network based models are preferred due to their simplicity, availability, and robustness. However, the type of neural network used should be capable of modeling the highly non-linear behavior and the multi- attractor nature of such systems. In this paper we use a special type of recurrent neural network called the ``Dynamic System Imitator (DSI)``, that has been proven to be capable of modeling very complex dynamic behaviors. The DSI is a fully recurrent neural network that is specially designed to model a wide variety of dynamic systems. The prediction method presented in this paper is based upon predicting one step ahead in the time series, and using that predicted value to iteratively predict the following steps. This method was applied to chaotic time series generated from the logistic, Henon, and the cubic equations, in addition to experimental pressure drop time series measured from a Fluidized Bed Reactor (FBR), which is known to exhibit chaotic behavior. The time behavior and state space attractor of the actual and network synthetic chaotic time series were analyzed and compared. The correlation dimension and the Kolmogorov entropy for both the original and network synthetic data were computed. They were found to resemble each other, confirming the success of the DSI based chaotic system modeling.
Date: March 31, 1996
Creator: Bodruzzaman, M. & Essawy, M.A.
Partner: UNT Libraries Government Documents Department

Investigation of heat transfer and combustion in the advanced Fluidized Bed Combustor (FBC). Technical progress report No. 9 [October 1, 1995--December 31, 1995]

Description: This technical report summarizes the research performed and progress achieved during the period of October 1, 1995 to December 31, 1995. The measurements of gas flow in the advanced FBC test chamber (10 in. I.D.) was continued to better understand and utilize the fluid dynamics of gas and particle flows in the advanced FBC. Measurements showed that the gas flow field in the test chamber is characterized by strongly swirling flow in tangential direction and developing flow in axial and radial directions. In addition, multiple secondary air injection caused significant effects on gas flow in the freeboard of the test chamber. Numerical simulation of typical gas flow patterns in the freeboard was conducted using a computational fluid dynamics (CFD) code, FLUENT. The axial velocities resulting from theoretical prediction were smaller than the tested results. However, the predicted radial velocities at the exit zone of the test chamber were greater than that of the tested results. The calculated results showed the non-isotropic structure with vigorous fluctuating in axial and radial directions. Generally speaking, the predictions of the theoretical calculation agreed with the experimental results. The measurements of gas and particle flows will be continued under different test conditions. In addition, the numerical simulation on gas and particle flows will be continued, which will be compared with the experimental results.
Date: January 1, 1996
Creator: Lee, Seong W.
Partner: UNT Libraries Government Documents Department