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[AIDS ARMS Network monthly service report] (open access)

[AIDS ARMS Network monthly service report]

A blank monthly service report prepared by the AIDS ARMS Network for the AIDS Resource Center, dated January 31, 1990.
Date: January 31, 1990
Creator: AIDS ARMS Network, Inc.
Object Type: Text
System: The UNT Digital Library
[Blank financial report form] (open access)

[Blank financial report form]

A blank financial statement form created by the AIDS ARMS Network, Inc. for the AIDS Resource Center for May 1990.
Date: May 31, 1990
Creator: AIDS ARMS Network, Inc.
Object Type: Text
System: The UNT Digital Library
[Notes to financial statements] (open access)

[Notes to financial statements]

A copy of some notes on AIDS ARMS Network's financial statements.
Date: August 31, 1991
Creator: AIDS ARMS Network, Inc.
Object Type: Text
System: The UNT Digital Library
Results from the Soviet-American gallium experiment (open access)

Results from the Soviet-American gallium experiment

A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory. The number of {sup 71}Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for {sup 71}Ge atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be 20 + 15/{minus}20 (stat) {plus_minus} 32 (syst) SNU, resulting in a limit of less than 79 SNU (90% CL). This is to be compared with 132 SNU predicted by the Standard Solar Model.
Date: December 31, 1991
Creator: Abazov, A. I.; Anosov, O. L.; Faizov, E. L.; Gavrin, V. N.; Kalikhov, A. V.; Knodel, T. V. et al.
Object Type: Report
System: The UNT Digital Library
An engineering and economic evaluation of the methane de-NOX{sup SM} technology (open access)

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
Development of novel copper-based sorbents for hot-gas cleanup. Technical report, September 1--November 30, 1991 (open access)

Development of novel copper-based sorbents for hot-gas cleanup. Technical report, September 1--November 30, 1991

The objective of this investigation is to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650{degree} to 850{degree}C (1200{degree}--1550{degree}F). To achieve this objective, several novel copper-based binary oxide sorbents will be prepared. Experimental tests will be conducted at ambient pressure to determine the stability, sulfidation capacity, regenerability, and sulfidation kinetics of the novel sorbents. Tests will also be conducted at high pressure for the determination of the sulfidation reactivity, regenerability, and durability of the sorbents. The attrition characteristics of the sorbents will also be determined.
Date: December 31, 1991
Creator: Abbasian, J.
Object Type: Report
System: The UNT Digital Library
Stabilization and/or regeneration of spent sorbents from coal gasification. Technical report, September 1--November 30, 1991 (open access)

Stabilization and/or regeneration of spent sorbents from coal gasification. Technical report, September 1--November 30, 1991

The objective of this investigation is to determine the effects of SO{sub 2} partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium-sulfate, while preventing the release of sulfur dioxide through undesirable side reactions during the stabilization step. An additional objective of this program is to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent limestone, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents will be reacted with oxygen at a variety of operating conditions under sufficient SO{sub 2} partial pressure to prevent release of sulfur from the solids during stabilization that reduces the overall sorbent utilization. Partially sulfided limestone will also be regenerated with water to produce calcium hydroxide and release sulfur as H{sub 2}S. The regenerated sorbent will be dewatered, dried and pelletized. The reactivity of the regenerated sorbent toward H{sub 2}S will also be determined. During this quarter sulfidation tests were conducted in a quartz fluidized-bed reactor in which the selected calcium-based sorbents were first calcined and then were reacted with hydrogen sulfide at ambient pressure …
Date: December 31, 1991
Creator: Abbasian, J.
Object Type: Report
System: The UNT Digital Library
Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, March 1--May 31, 1995 (open access)

Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, March 1--May 31, 1995

The objective of this study is to obtain data on the rates and the extent of sulfation reactions involving partially sulfided calcium-based sorbents, and oxygen as well as sulfur dioxide, at operating conditions closely simulating those prevailing in the second stage (combustor) of Advanced Two-Stage Pressurized Fluidized-Bed Combustors. In these systems the CO{sub 2} partial pressure generally exceeds the equilibrium value for calcium carbonate decomposition. Therefore, calcium sulfate is produced through the reactions between SO{sub 2} and calcium carbonate as well as the reaction between calcium sulfide and oxygen. To achieve this objective, the rates of reaction involving SO{sub 2} and oxygen, calcium sulfide and calcium carbonate will be determined by conducting tests in a pressurized thermogravimetric analyzer unit. The sulfate tests conducted during this quarter, focused on the determination of the rate of sulfation reaction involving partially sulfided half-calcined dolomite and oxygen. The test parameters included CO{sub 2} and O{sub 2} concentrations, reaction temperature and pressure, as well as the sorbent particle size. The results obtained during this quarter suggest that the rate of sulfation reaction involving partially sulfided half-calcined dolomite and oxygen is very fast at temperatures above 850 C which rapidly increases with increasing temperature, achieving more …
Date: December 31, 1995
Creator: Abbasian, J.
Object Type: Report
System: The UNT Digital Library
Stabilization and/or regeneration of spent sorbents from coal gasification. Final technical report, September 1, 1991--August 31, 1992 (open access)

Stabilization and/or regeneration of spent sorbents from coal gasification. Final technical report, September 1, 1991--August 31, 1992

The objective of this investigation was to determine the effects of SO{sub 2} partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium sulfate, while preventing the release of sulfur dioxide during the stabilization step. An additional objective of this study was to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent Ca-based sorbent, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents were reacted with oxygen and SO{sub 2} at various operating conditions and the extent of CaS and CaO conversion were determined. Partially sulfided dolomite was used in sulfidation/regeneration over several cycles and the regeneration efficiency and sorbent reactivity were determined after each cycle. The results of the stabilization tests show that partially sulfided Ca-based sorbents (both limestone and dolomite) can be sulfated at temperatures above 1500{degrees}F resulting in high CaS conversion without release of SO{sub 2} producing environmentally acceptable material for disposal in landfills. The results also indicate that spent dolomite can be regenerated in the SSRP process, in successive cycles, with high regeneration efficiency without loss …
Date: December 31, 1992
Creator: Abbasian, J.; Hill, A. H. & Wangerow, J. 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 (open access)

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
Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, September 1, 1991--August 31, 1992 (open access)

Development of novel copper-based sorbents for hot-gas cleanup. Final technical report, September 1, 1991--August 31, 1992

The objective of this investigation was to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650{degree} to 850{degree}C. To achieve this objective, several novel binary oxides of copper were systematically evaluated and ranked in terms of their high-temperature stability against reduction to metal, sulfidation reactivity, and regenerability. The sorbents studied included oxides of chromium, cerium, aluminum, magnesium, manganese, titanium, iron, and silicon. The results of initial testing indicated that mixed binary oxides of copper with chromium (CuCr{sub 2}O{sub 4}) and cerium (CuO{circle_dot}CeO{sub 2}) were the most promising sorbents for such high temperature gas cleanup applications. These two sorbents were further evaluated in cyclic sulfidation/regeneration tests in 10--15 cycles to determine the effect of operating conditions on their performance. The results of this investigation indicate that the two selected sorbents, copper-chromium and copper-cerium, are capable of removing H{sub 2}S from the hot fuel gas to very low levels (<10 ppmv) at temperatures as high as 850{degree}C with good sorbent regenerability in cyclic process. These sorbents should be further studied to achieve optimum sorbent composition for hot gas cleanup application.
Date: December 31, 1992
Creator: Abbasian, J.; Hill, A. H.; Wangerow, J. R.; Flytzani-Stephanopoulos, M.; Bo, Luhong; Patel, C. et al.
Object Type: Report
System: The UNT Digital Library
Advanced Low-Temperature Fluid Bed Sorbents (open access)

Advanced Low-Temperature Fluid Bed Sorbents

This paper discusses the results obtained in an ongoing study geared towards developing advanced mixed-metal oxide sorbents for desulfurization of coal-derived fuel gases in the temperature range of 350 to 550{degrees}C. The paper focuses on the study related to the development of durable sorbents suitable for fluidized-bed application and addresses thermodynamic considerations, sulfidation kinetics, regenerability, and the physical and chemical characteristics of a number of novel sorbents.
Date: December 31, 1996
Creator: Abbasian, J.; Slimane, R. B. & Wangerow, J. R.
Object Type: Article
System: The UNT Digital Library
Development of regenerable copper-based sorbents for hot gas cleanup. Technical report, September 1, 1995--November 30, 1995 (open access)

Development of regenerable copper-based sorbents for hot gas cleanup. Technical report, September 1, 1995--November 30, 1995

The overall objective of this study is to determine the effectiveness of the copper-chromite sorbent (developed in previous ICCI-funded projects) for longer duration application under optimum conditions in the temperature range of 550{degrees}-650{degrees}C to minimize sorbent reduction and degradation during the cyclic process. To achieve this objective, several formulations of copper chromite sorbents are prepared. These sorbent formulations are screened for their desulfurization and regeneration capability at predetermined temperatures and gas residence times. The durability of the best sorbent formulation identified in the screening tests is evaluated in ``long-term`` durability tests conducted at the optimum operating conditions. This includes testing the sorbent in pellet and granular forms in packed- and fluidized-bed reactors. During this quarter, twenty one copper chromite-based sorbent formulations were prepared. Two sorbent formulations that have acceptable crush strength, designated as CuCr-10 and CuCr-21, were tested over 5 and 6 cycles respectively. The results indicate that both sorbents are reactive toward H{sub 2}S at 650{degrees}C and that the reactivity of the sorbents are relatively constant over the first 5 to 6 cycles. The H{sub 2}S prebreakthrough concentrations were generally about 20 to 30 ppm, making them suitable for IGCC application.
Date: December 31, 1995
Creator: Abbasian, J.; Slimane, R.B. & Hill, A.H.
Object Type: Report
System: The UNT Digital Library
Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, September 1--November 30, 1994 (open access)

Sulfur removal in advanced two stage pressurized fluidized bed combustion. Technical report, September 1--November 30, 1994

The objective of this study is to obtain data on the rates and the extent of sulfation reactions involving partially sulfided calcium-based sorbents, and oxygen as well as sulfur dioxide, at operating conditions closely simulating those prevailing in the second stage (combustor) of Advanced Two-Stage Pressurized Fluidized-Bed Combustors (PFBC). In these systems the CO{sub 2} partial pressure generally exceeds the equilibrium value for calcium carbonate decomposition. Therefore, calcium sulfate is produced through the reactions between SO{sub 2} and calcium carbonate as well as the reaction between calcium sulfide and oxygen. To achieve this objective, the rates of reaction involving SO{sub 2} and oxygen (gaseous reactant); and calcium sulfide and calcium carbonate (solid reactants), will be determined by conducting tests in a pressurized thermogravimetric analyzer (HPTGA) unit. The effects of sorbent type, sorbent particle size, reactor temperature and pressure; and O{sub 2} as well as SO{sub 2} partial pressures on the sulfation reactions rate will be determined. During this quarter, samples of the selected limestone and dolomite were sulfided in the fluidized-bed reactor. These tests were conducted in both calcining and non-calcining operating conditions to produce partially-sulfided sorbents containing calcium oxide and calcium carbonate, respectively. These samples which represent the carbonizer …
Date: December 31, 1994
Creator: Abbasian, Javad; Hill, Andy; Wangerow, James R. & Honea, Franklin I.
Object Type: Report
System: The UNT Digital Library
Stabilization of spent sorbents from coal-based power generation processes. Technical report, September 1, 1995--November 30,1995 (open access)

Stabilization of spent sorbents from coal-based power generation processes. Technical report, September 1, 1995--November 30,1995

The overall objective of this study is to determine the effect of implementation of the new and more stringent EPA Protocol Test Method involving sulfide containing waste, on the suitability of the oxidized spent sorbents from gasification of of high sulfur coals for disposal in landfills, and to determine the optimum operating conditions in a ``final`` hydrolysis stage for conversion of the residual calcium sulfide in these wastes to materials that are suitable for disposal in landfills. An additional objective is to study the effect of ash on the regeneration and ash-sorbent separation steps in the Spent Sorbent Regeneration Process (SSRP). To achieve these objectives, a large set of oxidized samples of sulfided calcium-based sorbents (produced in earlier ICCI-funded programs) as well as oxidized samples of gasifier discharge (containing ash and spent sorbent) are tested according to the new EPA test protocol. Samples of the oxidized spent sorbents that do not pass the EPA procedure are reacted with water and carbon dioxide to convert the residual calcium sulfide to calcium carbonate. During this quarter, samples of oxidized sulfided calcium-based sorbents, including untreated calcium sulfide-containing feed materials, were analyzed using both weak acid and more stringent strong acid tests. Preliminary analysis …
Date: December 31, 1995
Creator: Abbassian, J. & Hill, A.H.
Object Type: Report
System: The UNT Digital Library
[Letter from Julie Abel to D. Jack Davis and R. William McCarter, August 13, 1997] (open access)

[Letter from Julie Abel to D. Jack Davis and R. William McCarter, August 13, 1997]

A letter from Julie Abel to D. Jack Davis and R. William McCarter about informing Davis and McCarter of their approved two grants to the North Texas Institute for Educators on the Visual Arts from The Getty Center for Education on the Arts.
Date: August 31, 1997
Creator: Abel, Julie
Object Type: Letter
System: The UNT Digital Library
[RE: Kennedy Center's ARTSEDGE] (open access)

[RE: Kennedy Center's ARTSEDGE]

Photocopy of a letter from Julie Abel,Program Associate, Getty Center for Education in the Arts, to the Regional Institute Directors. The letter is in regards to the John F. Kennedy Center for the Performing Arts requesting information on "promising programs, multi-media, resources and award programs" to be made available on ARTSEDGE. ArtsEdge, the center's National Arts and Education Information Network. Attached to the email is a document in regards to The Kennedy's Centers program.
Date: August 31, 1991
Creator: Abel, Julie
Object Type: Letter
System: The UNT Digital Library
The role of catalyst precursor anions in coal gasification. Eighth quarterly report, [July--September 1993] (open access)

The role of catalyst precursor anions in coal gasification. Eighth quarterly report, [July--September 1993]

This project investigates the roles of various aqueous soluble catalyst precursor anions, specifically acetate, chloride, nitrate, sulfate, and carbonate 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. The effects of the various anions on coal char gasification is currently under investigation. The influence of acetate, chloride and nitrate ions, when using the corresponding potassium compounds, are discussed in this report. The thermograms for the char preparation in nitrogen show that rapid devolatilization of moisture and other volatile materials occurs in the first 30 min. The rate of weight loss decreases significantly thereafter up to about 70 min. when char preparation was complete. Introduction of carbon dioxide after this time resulted in only a small amount of carbon gasification of the unloaded, demineralized coal. However, the chars containing the acetate, chloride or nitrate of potassium gave reactivities of 24.8, 30.4 or 24.3 %wt., respectively. The catalysts were ion-exchanged with the salt solutions and the corresponding potassium content were 2.9, 2.6 and 2.3 %wt. The higher reactivities of the catalyzed chars compared to the unloaded char correlates the high degree of demineralization and …
Date: December 31, 1993
Creator: Abotsi, G. M. K.
Object Type: Report
System: The UNT Digital Library
The role of catalyst precursor anions in coal gasification. Fourth quarterly report (open access)

The role of catalyst precursor anions in coal gasification. Fourth 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 (CI{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. In the past quarter, the effects of (CH{sub 3}COO{sup {minus}}), CI{sup {minus}}, (NO{sub 3}{sup {minus}}), (CO{sub 3}{sup 2{minus}}) or (CO{sub 3}{sup 2{minus}}) on the surface charge properties of the coal has been initiated using the calcium salts of these anions. Like the corresponding potassium compounds investigated previously, increasing anion concentrations produce less negative charge on the coal surface through the interaction of calcium ions with the surface. This was confirmed by metal adsorption and chemical analysis of the filtered coal particles. The extent of metal adsorption was strongly dependent on the catalyst precursor. For potassium, maximum metal uptake from solution was obtained using potassium carbonate, followed by potassium acetate, while the …
Date: December 31, 1992
Creator: Abotsi, G. M. K.
Object Type: Report
System: The UNT Digital Library
A novel approach to highly dispersing catalytic materials in coal for gasification. Eighth quarterly report, July 1, 1991--September 30, 1991 (open access)

A novel approach to highly dispersing catalytic materials in coal for gasification. Eighth quarterly report, July 1, 1991--September 30, 1991

This project seeks to develop a technique, based on coal surface properties, for highly dispersing catalysts in coal for gasification and to investigate the potential of using potassium carbonate and calcium acetate mixtures as catalyst for coal gasification. The lower cost and high catalytic activity of the latter compound will produce economic benefits by reducing the amount of K{sub 2}CO{sub 3} required for high coal char activities. The effects of potassium impregnation conditions (pH and coal surface charge) on the reactivities, in carbon dioxide, of chars derived from demineralized lignite, subbituminous and bituminous coals have been determined. Impregnation of the acid-leached coal with potassium from strongly acidic solutions resulted in initial slow char reactivity which progressively increased with reaction time. Higher reactivities were obtained for catalyst (potassium) loaded at pH 6 or 10. The dependence of char gasification rates on catalyst addition pH increased in the order: pH 6 {approximately} pH 10 {much_gt} pH 1.
Date: December 31, 1991
Creator: Abotsi, G. M. K. & Bota, K. B.
Object Type: Report
System: The UNT Digital Library
Surface modified coals for enhanced catalyst dispersion and liquefaction. Quarterly report, 1996 (open access)

Surface modified coals for enhanced catalyst dispersion and liquefaction. Quarterly report, 1996

The aim of this work is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants onto coal. The application of surfactants to coal beneficiation and coal-water slurry preparation is well known. However, the effects of surfactants on catalyst loading and dispersion prior to coal conversion processes have not been investigated. The current work is focused on the influence of the cationic surfactant dodecyl dimethyl ethyl ammonium bromide (DDAB) and sodium dodecyl sulfate (SDS, anionic) on the surface properties of a bituminous coal and its molybdenum and iron uptake from solution. In the previous report, it was shown that molybdenum loading onto the coal was enhanced by preadsorption of DDAB. The optimum concentration of this surfactant for effective adsorption of molybdenum at the natural pH of the coal slurry has been determined to be in the 0.1 to 0.25 M range. Preadsorption of SDS onto the coal was found to increase the uptake of iron by the coal; iron loading increased with increase in the concentration of the catalyst precursor. This observation is attributed to the increase in the negative surface charge properties of the coal with increase in the concentration of the surfactant. The …
Date: December 31, 1996
Creator: Abotsi, G.M.K.
Object Type: Report
System: The UNT Digital Library
A novel approach to highly dispersing catalytic materials in coal for gasification. Second quarterly report, January 1, 1990--March 31, 1990 (open access)

A novel approach to highly dispersing catalytic materials in coal for gasification. Second quarterly report, January 1, 1990--March 31, 1990

This project seeks to develop a technique, based on coal surface properties, for highly dispersing catalysts in coal for gasification and to investigate the potential of using potassium carbonate and calcium acetate mixtures as catalysts for coal gasification. The work is focused on the elucidation of coal-catalyst precursor interactions in solution and the variables which control the adsorption and dispersion of coal gasification metal catalysts. In order to optimize coal-metal ion interactions and hence maximize catalyst activity, the study examines the surface electrochemistry of a lignite, a subbituminous, and a bituminous coals and their demineralized and oxidized derivatives prior to loading with the catalytic materials. The surface electrical properties of the coals are investigated with the aid of electrophoresis, while the effects of the surface charge on the adsorption of K{sup +} and Ca{sup 2+} are studied by agitating the coals with aqueous solutions of potassium and calcium. Zeta potential studies show that the surfaces of the lignite are negatively charged between about pH2 to 11, the negative charge density increasing with increase in pH. Highly alkaline media promoted calcium adsorption due to high negative charge on the coal, while calcium uptake was inhibited in strongly acidic solutions.
Date: December 31, 1990
Creator: Abotsi, M. K. & Bota, K. B.
Object Type: Report
System: The UNT Digital Library
The Nimrod computational workbench: a case study in desktop metacomputing (open access)

The Nimrod computational workbench: a case study in desktop metacomputing

The coordinated use of geographically distributed computers, or metacomputing, can in principle provide more accessible and cost- effective supercomputing than conventional high-performance systems. However, we lack evidence that metacomputing systems can be made easily usable, or that there exist large numbers of applications able to exploit metacomputing resources. In this paper, we present work that addresses both these concerns. The basis for this work is a system called Nimrod that provides a desktop problem-solving environment for parametric experiments. We describe how Nimrod has been extended to support the scheduling of computational resources located in a wide-area environment, and report on an experiment in which Nimrod was used to schedule a large parametric study across the Australian Internet. The experiment provided both new scientific results and insights into Nimrod capabilities. We relate the results of this experiment to lessons learned from the I-WAY distributed computing experiment, and draw conclusions as to how Nimrod and I-WAY- like computing environments should be developed to support desktop metacomputing.
Date: December 31, 1996
Creator: Abramson, D.; Sosic, R.; Foster, I.; Giddy, J.; Lewis, A. & White, N.
Object Type: Article
System: The UNT Digital Library
Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst. Technical progress reports No. 7 and 8, April 1, 1991--September 30, 1991 (open access)

Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst. Technical progress reports No. 7 and 8, April 1, 1991--September 30, 1991

The objective of this contract is to examine the relationship between catalytic properties and the function of cobalt Fischer-Tropsch catalysts and to apply this fundamental knowledge to the development of a stable cobalt-based catalyst with a low methane-plus-ethane selectivity for use in slurry reactors. An experimental cobalt catalyst 585R2723 was tested three times in the fixed-bed reactor. The objective of the tests was to identify suitable testing conditions for screening catalyst. The {alpha}-alumina was determined to be a suitable diluent medium for controlling the catalyst bed temperature close to the inlet temperature. With 13 g of catalyst and 155 g of diluent, the catalyst maximum temperature were within 2{degree}C from the inlet temperatures. As a result of this work, 210{degree}C and 21 atm were shown to result in low methane selectivity and were used as initial conditions in the catalyst screening test. Ethane, which along with methane is undesirable, is typically produced with low selectivity and follows the same trend as methane. Other work reported here indicated that methane selectivity increases with increasing temperature but is not excessively high at 230{degree}C. Consequently, the catalyst screening test should include an evaluation of the catalyst performance at 230{degree}C. During Run 67, the …
Date: December 31, 1991
Creator: Abrevaya, H.
Object Type: Report
System: The UNT Digital Library