An Efficient Microwave Power Source: Free-electron Laser Afterburner (open access)

An Efficient Microwave Power Source: Free-electron Laser Afterburner

A kind of microwave power source, called a free-electron laser afterburner (FEL afterburner) which consists of a free-electron laser buncher and a slow-wave output structure sharing a magnetic wiggler field with the buncher, is proposed. The buncher and the slow-wave structure can operate in either a travelling-wave state or a standing-wave state. In the buncher, the wiggler field together with the radiation field makes an electron beam bunched, and in the slow-wave structure the wiggler field keeps the beam bunched while the bunched beam interacts strongly with the slow-wave structure and so produces rf power. The bunching process comes from the free-electron laser mechanism and the generating process of rf power is in a slow-wave structure. A three-dimensional, time-dependent code is used to simulate a particular standing-wave FEL afterburner and it is shown that rf power of up to 1.57 GW can be obtained, at 17.12 GHz, from a l-kA, 5-MeV electron beam.
Date: March 4, 1993
Creator: Wang, C. & Sessler, Andrew M.
Object Type: Article
System: The UNT Digital Library
Errors when shock waves interact due to numerical shock width (open access)

Errors when shock waves interact due to numerical shock width

A simple test problem proposed by Noh, a strong shock reflecting from a rigid wall, demonstrates a generic problem with numerical shock capturing algorithms at boundaries that Noh called excess wall heating.'' We show that the same type of numerical error occurs in general when shock waves interact. The underlying cause is the non-uniform convergence to the hyperbolic solution of the inviscid limit of the solution to the PDEs with viscosity. The error can be understood from an analysis of the asymptotic solution. For a propagating shock, there is a difference in the total energy of the parabolic wave relative to the hyperbolic shock. Moreover, the relative energy depends on the strength of the shock. The error when shock waves interact is due to the difference in the relative energies between the incoming and outgoing shock waves. It is analogous to a phase shift in a scattering matrix. A conservative differencing scheme correctly describes the Hugoniot jump conditions for a steady propagating shock. Therefore, the error from the asymptotics occurs in the transient when the waves interact. The entropy error that occurs in the interaction region remains localized but does not dissipate. A scaling argument shows that as the viscosity …
Date: March 4, 1993
Creator: Menikoff, R.
Object Type: Article
System: The UNT Digital Library
Development of advanced NO[sub x] control concepts for coal-fired utility boilers (open access)

Development of advanced NO[sub x] control concepts for coal-fired utility boilers

The complete CombiNO[sub x], process has now been demonstrated at a level that is believed to be representative of a full-scale boiler in terms of mixing capabilities. A summary of the results is displayedin Figure 5-1. While firing Illinois Coal on the Reburn Tower, Advanced Reburning was capable of reducing NO[sub x], by 83 percent. The injection of methanol oxidized 50--58 percent of the existing NO to N0[sub 2]. Assuming that 85 percent of the newly formed N0[sub 2] can be scrubbed in a liquor modified wet-limestone scrubber, the CombiNO[sub x], process has been shown capable of reducing NO[sub 2], by 90--91 percent in a large pilot-scale coal-fired furnace. There is still uncertainty regarding the fate of the N0[sub 2] formed with methanol injection. Tests should be conducted to determine whether the reconversion is thermodynamic or catalytic, and what steps can be taken (such as quench rate) to prevent it from happening.
Date: March 4, 1993
Creator: Evans, A.; Pont, J. N.; England, G. & Seeker, W. R.
Object Type: Report
System: The UNT Digital Library
Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane (open access)

Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane

Amax R D will perform laboratory scale development of a promising, practical catalyst for the selective oxidation of methane to methanol. The primary component of this catalyst is vanadium-phosphate (VPO) which has shown good activity and selectivity in the partial oxidation of n-butane and propane but has not been studied in detail for methane oxidation. The goal of the project is to develop a catalyst which allows methane oxidation to methanol to be conducted at high conversion and selectivity. A low CH[sub 4]/O[sub 2] ratio will be employed with air as the source of oxygen. Temperatures below 600[degrees]C and pressures up to 20 atm are to be investigated. The use of steam in the feed gas will also be investigated. The catalyst development strategy will be to utilize promoters and supports to improve the activity and selectivity of the unmodified VPO catalyst. The catalyst testing reactor system was used to perform blank (empty) reactor runs over a wide range of temperatures, pressure, and flow rates. No methane conversion was observed at temperatures of 500[degrees]C or lower in any of the tests. At higher temperatures, significant methane conversion to carbon dioxide was observed. At 550[degrees]C, 300 psig, and the highest flow …
Date: March 4, 1993
Creator: McCormick, Robert L. & Jha, Mahesh C.
Object Type: Report
System: The UNT Digital Library
Methyl chloride via oxyhydrochlorination of methane (open access)

Methyl chloride via oxyhydrochlorination of methane

Work to develop a highly selective methyl chloride synthesis catalyst continued, but no stable catalyst with >80% selectivity at 20% methane exists yet. Effort was made on finalizing the pre- engineering scope definition of the Process Demonstration Unit. Natural gas purification, reactor, reactor effluent and MeCl purification, and anhydrous HCl recovery are discussed.
Date: March 4, 1993
Creator: Naasz, B.
Object Type: Report
System: The UNT Digital Library
Development of advanced NO{sub x} control concepts for coal-fired utility boilers. Quarterly technical progress report No. 8, July 1, 1992--September 30, 1992 (open access)

Development of advanced NO{sub x} control concepts for coal-fired utility boilers. Quarterly technical progress report No. 8, July 1, 1992--September 30, 1992

The complete CombiNO{sub x}, process has now been demonstrated at a level that is believed to be representative of a full-scale boiler in terms of mixing capabilities. A summary of the results is displayed in Figure 5-1. While firing Illinois Coal on the Reburn Tower, Advanced Reburning was capable of reducing NO{sub x}, by 83 percent. The injection of methanol oxidized 50--58 percent of the existing NO to N0{sub 2}. Assuming that 85 percent of the newly formed N0{sub 2} can be scrubbed in a liquor modified wet-limestone scrubber, the CombiNO{sub x}, process has been shown capable of reducing NO{sub 2}, by 90--91 percent in a large pilot-scale coal-fired furnace. There is still uncertainty regarding the fate of the N0{sub 2} formed with methanol injection. Tests should be conducted to determine whether the reconversion is thermodynamic or catalytic, and what steps can be taken (such as quench rate) to prevent it from happening.
Date: March 4, 1993
Creator: Evans, A.; Pont, J. N.; England, G. & Seeker, W. R.
Object Type: Report
System: The UNT Digital Library
Methyl chloride via oxyhydrochlorination of methane. Final quarterly technical report, July 1, 1992--September 30, 1992 (open access)

Methyl chloride via oxyhydrochlorination of methane. Final quarterly technical report, July 1, 1992--September 30, 1992

Work to develop a highly selective methyl chloride synthesis catalyst continued, but no stable catalyst with >80% selectivity at 20% methane exists yet. Effort was made on finalizing the pre- engineering scope definition of the Process Demonstration Unit. Natural gas purification, reactor, reactor effluent and MeCl purification, and anhydrous HCl recovery are discussed.
Date: March 4, 1993
Creator: Naasz, B.
Object Type: Report
System: The UNT Digital Library
Human cDNA mapping using fluorescence in situ hybridization. Progress report, April 1, 1992--December 31, 1992 (open access)

Human cDNA mapping using fluorescence in situ hybridization. Progress report, April 1, 1992--December 31, 1992

Genetic mapping is approached using the techniques of high resolution fluorescence in situ hybridization (FISH). This technology and the results of its application are designed to rapidly generate whole genome as tool box of expressed sequence to speed the identification of human disease genes. The results of this study are intended to dovetail with and to link the results of existing technologies for creating backbone YAC and genetic maps. In the first eight months, this approach generated 60--80% of the expressed sequence map, the remainder expected to be derived through more long-term, labor-intensive, regional chromosomal gene searches or sequencing. The laboratory has made significant progress in the set-up phase, in mapping fetal and adult brain and other cDNAs, in testing a model system for directly linking genetic and physical maps using FISH with small fragments, in setting up a database, and in establishing the validity and throughput of the system.
Date: March 4, 1993
Creator: Korenberg, J. R.
Object Type: Report
System: The UNT Digital Library
Errors when shock waves interact due to numerical shock width (open access)

Errors when shock waves interact due to numerical shock width

A simple test problem proposed by Noh, a strong shock reflecting from a rigid wall, demonstrates a generic problem with numerical shock capturing algorithms at boundaries that Noh called ``excess wall heating.`` We show that the same type of numerical error occurs in general when shock waves interact. The underlying cause is the non-uniform convergence to the hyperbolic solution of the inviscid limit of the solution to the PDEs with viscosity. The error can be understood from an analysis of the asymptotic solution. For a propagating shock, there is a difference in the total energy of the parabolic wave relative to the hyperbolic shock. Moreover, the relative energy depends on the strength of the shock. The error when shock waves interact is due to the difference in the relative energies between the incoming and outgoing shock waves. It is analogous to a phase shift in a scattering matrix. A conservative differencing scheme correctly describes the Hugoniot jump conditions for a steady propagating shock. Therefore, the error from the asymptotics occurs in the transient when the waves interact. The entropy error that occurs in the interaction region remains localized but does not dissipate. A scaling argument shows that as the viscosity …
Date: March 4, 1993
Creator: Menikoff, R.
Object Type: Article
System: The UNT Digital Library
Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly technical progress report No. 1, October--December 1992 (open access)

Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly technical progress report No. 1, October--December 1992

Amax R&D will perform laboratory scale development of a promising, practical catalyst for the selective oxidation of methane to methanol. The primary component of this catalyst is vanadium-phosphate (VPO) which has shown good activity and selectivity in the partial oxidation of n-butane and propane but has not been studied in detail for methane oxidation. The goal of the project is to develop a catalyst which allows methane oxidation to methanol to be conducted at high conversion and selectivity. A low CH{sub 4}/O{sub 2} ratio will be employed with air as the source of oxygen. Temperatures below 600{degrees}C and pressures up to 20 atm are to be investigated. The use of steam in the feed gas will also be investigated. The catalyst development strategy will be to utilize promoters and supports to improve the activity and selectivity of the unmodified VPO catalyst. The catalyst testing reactor system was used to perform blank (empty) reactor runs over a wide range of temperatures, pressure, and flow rates. No methane conversion was observed at temperatures of 500{degrees}C or lower in any of the tests. At higher temperatures, significant methane conversion to carbon dioxide was observed. At 550{degrees}C, 300 psig, and the highest flow rate …
Date: March 4, 1993
Creator: McCormick, Robert L. & Jha, Mahesh C.
Object Type: Report
System: The UNT Digital Library
Human cDNA mapping using fluorescence in situ hybridization (open access)

Human cDNA mapping using fluorescence in situ hybridization

Genetic mapping is approached using the techniques of high resolution fluorescence in situ hybridization (FISH). This technology and the results of its application are designed to rapidly generate whole genome as tool box of expressed sequence to speed the identification of human disease genes. The results of this study are intended to dovetail with and to link the results of existing technologies for creating backbone YAC and genetic maps. In the first eight months, this approach generated 60--80% of the expressed sequence map, the remainder expected to be derived through more long-term, labor-intensive, regional chromosomal gene searches or sequencing. The laboratory has made significant progress in the set-up phase, in mapping fetal and adult brain and other cDNAs, in testing a model system for directly linking genetic and physical maps using FISH with small fragments, in setting up a database, and in establishing the validity and throughput of the system.
Date: March 4, 1993
Creator: Korenberg, J.R.
Object Type: Report
System: The UNT Digital Library
Technology development for cobalt F-T catalysts (open access)

Technology development for cobalt F-T catalysts

A computer search of both the open and the patent literature was conducted in order to ascertain the current state of cobalt-based catalyst technology for F-T synthesis. Two series of literature searches were conducted, one dealing specifically with cobalt catalysts for F-T synthesis and the other focusing on the preparation and/or characterization of supported cobalt catalysts including those not used for F-T synthesis. An initial screening of the literature was carried out by examining the 942 abstracts obtained from these searches. The main objective of this initial screening was the selection of the most pertinent publications for this work. out of the 230 patent references obtained from the computer search, about 90 were found to be directly related the preparation of cobalt catalysts and their use in FT synthesis. Copies of patents (78 patents) not available within the group have been ordered but not yet received. Based on a preliminary analysis,of the abstracts of the most pertinent patents a distribution among the various patent assignees is given in Table 1. As can be seen in Table 1, most of the patents for Co FT catalysts have been assigned to very few companies, the first four, i.e. Exxon, Shell, Gulf, and …
Date: March 4, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library