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15,324 Matching Results
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A Computational Model for Coal Transport and Combustion. Quarterly Technical Progress Report, December 1, 1992--February 28, 1993
In the period of December 1, 1992 to February 28, 1993, further progress was made in using the thermodynamically consistent, rate dependent model for turbulent two-phase flows analysis. The effect of particle Reynolds number on variations of the fluctuation kinetic energy with the solid volume fraction for the special case of a simple shear flow was analyzed. Additional results for the application of the kinetic model for rapid flows of granular materials, which includes frictional losses were obtained. The velocity profile for granular gravity flow down an inclined chute, including slip velocity at the wall were obtained, and the results were compared with the data of Drake and Shreve and Johnson et al. The computational model for rapid granular and two-phase flows in complex geometries was further developed. The discrete element scheme was used and the granular flow down a chute was analyzed. The results are compared with the experimental data model prediction of Savage, and the simulation results of Campbell and Brennen. The experimental monolayer simple shear flow device was modified to allow for shearing of 12 mm multi-color glass particles. The device was reassembled and made fully operational. Sample videos of the granular motions are obtained. Developing a …
Date:
May 1, 1993
Creator:
Ahmadi, Goodarz
Object Type:
Report
System:
The UNT Digital Library
A Computational Model for Coal Transport and Combustion. Quarterly Technical Progress Report, September 1, 1993--November 30, 1993
In the period of September 1, 1993 to November 30, 1993, further progress was made of the theoretical and computational modeling of turbulent two-phase flows, as well as granular flows. The effect of bumpy wall on flow of granular materials was also analyzed. The special case of Couette flow was studied. Further progress was made in the experimental study of mono-layer simple shear flow device. Preliminary data concerning the sharing of 12 mm multi-color glass particles are obtained. The preliminary experimental data show the expected variation. A detailed progress report for project review was also prepared which includes the recent development. The description of this report is given.
Date:
December 31, 1993
Creator:
Ahmadi, Goodarz
Object Type:
Report
System:
The UNT Digital Library
Angular response characterization of the Martin Marietta Energy Systems, Inc., personnel dosimeter
An evaluation of the Martin Marietta Energy Systems, Inc., personnel dosimeter to radiation incident from non-perpendicular angles was carried out to meet the Department of Energy Laboratory Accreditation Program (DOELAP) requirements. Dosimeters were exposed to six different radiation sources. For each source, dosimeters were rotated about their horizontal and vertical axes at seven different angles each. Raw readings were processed through the dose calculation algorithm used for routine personnel dosimetry to determine dose equivalent values. Dose equivalent responses relative to zero degree incident angle were found to be within {plus_minus} 20% for M150, K-59 and {sup 137}Cs photons when the incident angle was 60{degree} or less. For low-energy photon irradiations (M30 and K-16), responses for angles other than perpendicular incidence are generally unpredictable. Reasons include: (1) failure of dose calculation algorithm to identify the radiation field correctly due to unusual element ratios; and (2) at extreme angles ({plus_minus} 85{degree}), the dosimeter design (in relation to the irradiation geometry) becomes the limiting factor in producing reproducible results. Response to {sup 204}Tl beta particles decreases rapidly with increasing angle of incidence.
Date:
August 1, 1993
Creator:
Ahmed, A. B.; McMahan, K. L. & Colwell, D. S.
Object Type:
Report
System:
The UNT Digital Library
A [gamma][sub t]-jump scheme for the Brookhaven AGS
AGS beam losses at transition are now tolerable ([lt]5%), but as the present improvement plans are implemented and the intensity is increased, new mechanisms will become important and the losses will increase. This Note describes studies directed towards minimizing these losses. Werner Hardt has studied these losses at the CERN PS. In particular, he found that by sharply reducing the time spent going through transition he could reduce the losses. Hardt visited Brookhaven in early June, 1986, in order to help us better understand the AGS. As a result of work inspired by his visit, we now believe that intensities of [approximately]5x10[sup 13] circulating protons are attainable in the AGS without significant losses at transition.
Date:
April 23, 1993
Creator:
Ahrens, L.; Auerbach, E.; Hardt, W.; Raka, E.; Ratner, L. & Yamin, P.
Object Type:
Report
System:
The UNT Digital Library
A {gamma}{sub t}-jump scheme for the Brookhaven AGS
AGS beam losses at transition are now tolerable ({lt}5%), but as the present improvement plans are implemented and the intensity is increased, new mechanisms will become important and the losses will increase. This Note describes studies directed towards minimizing these losses. Werner Hardt has studied these losses at the CERN PS. In particular, he found that by sharply reducing the time spent going through transition he could reduce the losses. Hardt visited Brookhaven in early June, 1986, in order to help us better understand the AGS. As a result of work inspired by his visit, we now believe that intensities of {approximately}5x10{sup 13} circulating protons are attainable in the AGS without significant losses at transition.
Date:
April 23, 1993
Creator:
Ahrens, L.; Auerbach, E.; Hardt, W.; Raka, E.; Ratner, L. & Yamin, P.
Object Type:
Report
System:
The UNT Digital Library
Solidification modeling of a spiral casting to determine material fluidity
In casting, fluidity is the measure of the distance a metal can flow in a channel before being stopped by solidification. During mold filling, the metal loses heat to the surrounding mold, thereby cooling and becoming more viscous until the leading portion solidifies and no further flow is possible. A coupled heat-transfer and fluid-flow modeling of a spiral, involving the use of thermophysical properties to determine material fluidity, has been conducted. Fluidity experiments were performed by Caterpillar; several spiral test castings were poured. Simulations of these experiments utilized the Casting Process Simulator (CAPS) software developed at Argonne National Laboratory. Two types of two dimensional spiral geometries with different assumptions were considered: (1) a 2-D laterally stretched spiral and (2) a 3-D lateral spiral. Computed mold filling is in good agreement with experiment. Time required by metal/gas interface to attain specific positions in the spiral arm also compares favorably with the experiment. Influence of process variables, especially pour time, is discussed. CAPS software was used to investigate validity of dimensionality assumptions and to evaluate ability of CAPS to model fluidity adequately.
Date:
November 1, 1993
Creator:
Ahuja, S.; Domanus, H. M.; Schmitt, R. C.; Chuzhoy, L. & Grabel, J. V.
Object Type:
Article
System:
The UNT Digital Library
Dislocation Loops in Spinel Crystals Irradiated Successively With Deep and Shallow Ion Implants
This study examines the influence of microstructural defects on irradiation damage accumulation in the oxide spinel. Single crystals of the compound MgAl{sub 2}O{sub 4} with surface normal [111] were irradiated under cryogenic temperature (100K) either with 50 keV Ne ions (fluence 5.0 {times} 10{sup 12}/cm{sup 2}), 400 keV Ne ions (fluence 6.7 {times} 10{sup 13}/cm{sup 2}) or successively with 400 keV Ne ions followed by 50 keV Ne ions. The projected range of 50 keV Ne ions in spinel is {approximately}50 mn (``shallow``) while the projected range of 400 keV Ne ions is {approximately}500 mn (``deep``). Transmission electron microscopy (TEM) was used to examine dislocation loops/defect clusters formed by the implantation process. Measurements of the dislocation loop size were made using weak-beam imaging technique on cross-sectional TEM ion-implanted specimens. Defect clusters were observed in both deep and shallow implanted specimens, while dislocation loops were observed in the shallow implanted sample that was previously irradiated by 400 keV Ne ions. Cluster size was seen to increase for shallow implants in crystals irradiated with a deep implant (size {approximately}8.5 nm) as compared to crystals treated only to a shallow implant (size {approximately}3.1 nm).
Date:
December 31, 1993
Creator:
Ai, R. X.; Cooper, E. A.; Sickafus, K. E.; Nastasi, M.; Bordes, N. & Ewing, R. C.
Object Type:
Article
System:
The UNT Digital Library
Discussion of stress tensor nonuniqueness with application to nonuniform, particulate systems
The indeterminacy of the mechanical stress tensor has been noted in several developments of expressions for stress in a system of particles. It is generally agreed that physical quantities related to the stress tensor must be insensitive to this nonuniqueness, but there is no definitive prescription for insuring it. Kroener`s tensor decomposition theorem is applied to the mechanical stress tensor {sup {sigma}}{sub ij} to show that its complete determination requires specification of its ``incompatibility,`` {epsilon}{sub ijk} {epsilon}{sub lmn} {sup {partial_derivative}}{sub j} {sup {partial_derivative}}{sub m} {sup {sigma}}{sub kn}, in addition to its divergence, which is obtained from the momentum conservation relation. For a particulate system, stress tensor incompatibility is shown to vanish to recover the correct expression for macroscopically observable traction. This result removes concern about nonuniqueness without requiring equilibrium or arbitrarily-defined force lines.
Date:
June 1, 1993
Creator:
Aidun, J. B.
Object Type:
Article
System:
The UNT Digital Library
Discussion of stress tensor nonuniqueness with application to nonuniform, particulate systems
The indeterminacy of the mechanical stress tensor has been noted in several developments of expressions for stress in a system of particles. It is generally agreed that physical quantities related to the stress tensor must be insensitive to this nonuniqueness, but there is no definitive prescription for insuring it. Kroener's tensor decomposition theorem is applied to the mechanical stress tensor [sup [sigma]][sub ij] to show that its complete determination requires specification of its incompatibility,'' [epsilon][sub ijk] [epsilon][sub lmn] [sup [partial derivative]][sub j] [sup [partial derivative]][sub m] [sup [sigma]][sub kn], in addition to its divergence, which is obtained from the momentum conservation relation. For a particulate system, stress tensor incompatibility is shown to vanish to recover the correct expression for macroscopically observable traction. This result removes concern about nonuniqueness without requiring equilibrium or arbitrarily-defined force lines.
Date:
January 1, 1993
Creator:
Aidun, J.B.
Object Type:
Article
System:
The UNT Digital Library
Shear wave measurements in shock-induced, high-pressure phases
Structural phase transformations under shock loading are of considerable interest for understanding the response of solids under nonhydrostatic stresses and at high strain-rates. Examining shock-induced transformations from continuum level measurements is fundamentally constrained by the inability to directly identify microscopic processes, and also by the limited number of material properties that can be directly measured. ne latter limitation can be reduced by measuring both shear and compression waves using Lagrangian gauges in combined, compression and shear loading. The shear wave serves as an important, real-time probe of the shocked state and unloading response. Using results from a recent study of CaCO[sub 3], the unique information obtained from the shear wave speed and the detailed structure of the shear wave are shown to be useful for distinguishing the effects of phase transformations from yielding, as well as in characterizing the high-pressure phases and the yielding process under shock loading.
Date:
January 1, 1993
Creator:
Aidun, J.B.
Object Type:
Article
System:
The UNT Digital Library
Shear Wave Measurements in Shock-Induced, High-Pressure Phases
Structural phase transformations under shock loading are of considerable interest for understanding the response of solids under nonhydrostatic stresses and at high strain-rates. Examining shock-induced transformations from continuum level measurements is fundamentally constrained by the inability to directly identify microscopic processes, and also by the limited number of material properties that can be directly measured. ne latter limitation can be reduced by measuring both shear and compression waves using Lagrangian gauges in combined, compression and shear loading. The shear wave serves as an important, real-time probe of the shocked state and unloading response. Using results from a recent study of CaCO{sub 3}, the unique information obtained from the shear wave speed and the detailed structure of the shear wave are shown to be useful for distinguishing the effects of phase transformations from yielding, as well as in characterizing the high-pressure phases and the yielding process under shock loading.
Date:
July 1, 1993
Creator:
Aidun, John B.
Object Type:
Article
System:
The UNT Digital Library
Electroweak physics at the Tevatron collider
Preliminary results on electroweak physics from the 1992--1993 run with the CDF and D0 detectors at the Tevatron collider are presented. New measurements of the ratio of the W and Z production cross sections times the branching fractions for subsequent decay into leptons are shown. The W width, {Gamma}(W), and a limit on the top-quark mass independent of decay mode are extracted. The status of a measurement of the charge asymmetry of electrons from W decay is given. Also shown are a study of diboson (W{gamma}, Z{gamma} and WZ) production and a search for a new neutral gauge boson (Z{prime}).
Date:
August 1, 1993
Creator:
Aihara, H.
Object Type:
Article
System:
The UNT Digital Library
MEG studies of human vision: Retinotopic organization of V1
A primary goal of noninvasive studies of human vision is to identify and characterize multiple visual areas in the human brain analogous to those identified in studies of nonhuman primates. By combining functional MEG measurements with images of individual anatomy derived from MRI, the authors hope to determine the location and arrangement of multiple visual areas in human cortex and to probe their functional significance. The authors have identified several different visual areas thus far which appear to be topographically organized. This paper focuses on the retinotopic characterization of the primary visual area (V1) in humans.
Date:
December 31, 1993
Creator:
Aine, C.; George, J.; Ranken, D.; Best, E.; Tiee, W.; Vigil, V. et al.
Object Type:
Article
System:
The UNT Digital Library
Integrated estimation of commercial sector end-use load shapes and energy use intensities in the PG&E service area
This project represents a unique research effort to address the commercial sector end-use energy forecasting data needs of the Pacific Gas and Electric Company (PG&E) and the California Energy Commission (CEC). The object of the project was to develop an updated set of commercial sector end-use energy use intensity (EUI) data that has been fully reconciled with measured data. The research was conducted in two stages. First, we developed reconciled electricity end-use EUIs and load shapes for each of the 11 building types in the inland and coastal regions of the PG&E service territory using information collected in 1986. Second, we developed procedures to translate these results into a consistent set of commercial sector forecasting model inputs recognizing the separate modeling conventions used by PG&E and CEC. EUIs have been developed for: II commercial building types; up to 10 end uses; up to 3 fuel types; 2 and 5 subservice territory forecasting regions (as specified by the PG&E and CEC forecasting models, respectively); and up to 2 distinct vintages corresponding to the period prior to and immediately following the adoption of the first generation of California building and equipment standards. For the electricity end uses, 36 sets of daily load …
Date:
December 1, 1993
Creator:
Akbari, H.; Eto, J.; Konopacki, S.; Afzal, A.; Heinemeier, K. & Rainer, L.
Object Type:
Report
System:
The UNT Digital Library
Measured commercial load shapes and energy-use intensities and validation of the LBL end-use disaggregation algorithm
The Southern California Edison Company (SCE) has conducted an extensive metering project in which electricity end use in 53 commercial buildings in Southern California has been measured. The building types monitored include offices, retail stores, groceries, restaurants, and warehouses. One year (June 1989 through May 1990) of the SCE measured hourly end-use data are reviewed in this report. Annual whole-building and end-use energy use intensities (EUIs) and monthly load shapes (LSs) have been calculated for the different building types based on the monitored data. This report compares the monitored buildings' EUIs and LSs to EUIs and LSs determined using whole-building load data and the End-Use Disaggregation Algorithm (EDA). Two sets of EDA determined EUIs and LSs are compared to the monitored data values. The data sets represent: (1) average buildings in the SCE service territory and (2) specific buildings that were monitored.
Date:
January 1, 1993
Creator:
Akbari, H.; Rainer, L.; Heinemeier, K.; Huang, J. & Franconi, E.
Object Type:
Report
System:
The UNT Digital Library
Measured commercial load shapes and energy-use intensities and validation of the LBL end-use disaggregation algorithm. Final report
The Southern California Edison Company (SCE) has conducted an extensive metering project in which electricity end use in 53 commercial buildings in Southern California has been measured. The building types monitored include offices, retail stores, groceries, restaurants, and warehouses. One year (June 1989 through May 1990) of the SCE measured hourly end-use data are reviewed in this report. Annual whole-building and end-use energy use intensities (EUIs) and monthly load shapes (LSs) have been calculated for the different building types based on the monitored data. This report compares the monitored buildings` EUIs and LSs to EUIs and LSs determined using whole-building load data and the End-Use Disaggregation Algorithm (EDA). Two sets of EDA determined EUIs and LSs are compared to the monitored data values. The data sets represent: (1) average buildings in the SCE service territory and (2) specific buildings that were monitored.
Date:
January 1, 1993
Creator:
Akbari, H.; Rainer, L.; Heinemeier, K.; Huang, J. & Franconi, E.
Object Type:
Report
System:
The UNT Digital Library
Measurement of spin motions in a storage ring outside the stable polarization direction
Polarized, stored beams are becoming a more and more important tool in nuclear and high energy physics. In order to measure the beam polarization in a storage ring the polarization vector of the stored beams has to aim, revolution for revolution, over a period of seconds to minutes, into the same, so-called ``stable`` direction. In this paper measurements at the Indiana University cooler ring (IUCF) are described in which for the first time in a storage ring oscillations of the polarization vector around this stable direction have been measured. The existence and the dynamics of such oscillations are, for instance, important for a new proposed technique for polarizing stored hadron beams.
Date:
June 1, 1993
Creator:
Akchurin, N.; Badano, L. & Bravar, A.
Object Type:
Report
System:
The UNT Digital Library
Static ultra-high pressure study of lanthanide and actinide metals using a diamond-anvil cell
Structural phase transformation in lanthanides and actinides were investigated as a function of pressure up to 300 GPa at room temperature. Except in Ce and Pr, no large volume changes were noticed for these metals as thy went through several phase changes. The appearance of a bct ultra-high pressure phase in Ce, Sm, Th, and possibly in Np, raises the possibility that the ultimate high pressure structure for the 4f and 5f metals may be the bct structure. On the other hand, it is also possible that this is a precursor to another close-packed structure at even higher pressure.
Date:
June 30, 1993
Creator:
Akella, J.; Smith, G. S. & Weir, S. T.
Object Type:
Article
System:
The UNT Digital Library
Characterization of gas-aerosol interaction kinetics using morphology dependent stimulated Raman scattering. 1992 Annual summary
This study is aimed at characterizing the influence of aerosol surface structure on the kinetics of gas-aerosol interactions. Changes in gas phase chemical reaction rates as a function of exposure to a specific aerosol are measured with aerosols having different surface properties due to the composition and/or temperature of the material making up the aerosol. The kinetic data generated can be used directly in atmospheric modeling calculations. The surface structure of the aerosol is using morphology-dependent enhancement of simulated Raman scattering (MDSRS). Detailed dynamics of gas-aerosol interactions can be obtained by correlating the change in the reaction rate with change in surface structure and by monitoring the change in aerosol surface structure during, the course of the reaction. This dynamics information can be used to generate kinetic data for systems which are similar in nature to those studied, but are not amenable to laboratory investigation. We show here that increased MDSRS sensitivity is achieved by using an excitation laser source that has a narrow linewidth and we have been able to detect sulfate anion concentrations much lower than previously reported. We have shown that the linewidth of the MDSRS mode excited in a droplet is limited by the laser linewidth. …
Date:
January 30, 1993
Creator:
Aker, P. M.
Object Type:
Report
System:
The UNT Digital Library
Characterization of gas-aerosol interaction kinetics using morphology dependent stimulated Raman scattering
This study is aimed at characterizing the influence of aerosol surface structure on the kinetics of gas-aerosol interactions. Changes in gas phase chemical reaction rates as a function of exposure to a specific aerosol are measured with aerosols having different surface properties due to the composition and/or temperature of the material making up the aerosol. The kinetic data generated can be used directly in atmospheric modeling calculations. The surface structure of the aerosol is using morphology-dependent enhancement of simulated Raman scattering (MDSRS). Detailed dynamics of gas-aerosol interactions can be obtained by correlating the change in the reaction rate with change in surface structure and by monitoring the change in aerosol surface structure during, the course of the reaction. This dynamics information can be used to generate kinetic data for systems which are similar in nature to those studied, but are not amenable to laboratory investigation. We show here that increased MDSRS sensitivity is achieved by using an excitation laser source that has a narrow linewidth and we have been able to detect sulfate anion concentrations much lower than previously reported. We have shown that the linewidth of the MDSRS mode excited in a droplet is limited by the laser linewidth. …
Date:
January 30, 1993
Creator:
Aker, P.M.
Object Type:
Report
System:
The UNT Digital Library
Gamma-ray optical counterpart search experiment (GROCSE)
The requirements of a gamma-ray burst optical counterpart detector are reviewed. By taking advantage of real-time notification of bursts, new instruments can make sensitive searches while the gamma-ray transient is still in progress. A wide field of view camera at Livermore National Laboratories has recently been adapted for detecting GRB optical counterparts to a limiting magnitude of 8. A more sensitive camera, capable of reaching m{sub upsilon} = 14, is under development.
Date:
December 15, 1993
Creator:
Akerlof, C.; Fatuzzo, M.; Lee, B.; Bionta, R.; Ledebuhr, A.; Park, H. S. et al.
Object Type:
Article
System:
The UNT Digital Library
Characterization of explosive devices in luggage: Initial results of the ART-IIC test series
Characteristics and damage associated with exploded luggage aboard aircraft are presented in this paper. Plastic-sided suitcases filled with typical travel possessions were exploded inside the fuselage of decomissioned B-52 aircraft. Multilayered shield panels, mounted to one side of the fuselage, served to protect the aircraft body and flight system components from both the blast wave and exploded fragments. The resulting damage produced by the explosions was characterized and the absorbing characteristics of the shielding were evaluated. In addition, the energy of the luggage fragments was estimated.
Date:
December 31, 1993
Creator:
Akerman, M. A.; Kass, M. D. & Clough, B. T.
Object Type:
Article
System:
The UNT Digital Library
Test plan for Digface Chemical and Radiation Assay System
The Digface Chemical and Radiation Assay System (CRAS) Project will develop a sensor using Prompt Gamma Neutron Activation Analysis (PGNAA) that can detect the present of hazardous chemicals and radioactive materials. The CRAS is being designed for in situ assay of closed drums and contaminated soils for gamma-ray emitting radionuclides and hazardous elements. The CRAS is based upon the use of {sup 252}Cf PGNAA with a germanium gamma-ray spectrometer as the analyzer. Tasks being performed include determining detection limits for a number of hazardous chemicals and assessing matrix and transmission effects through soil. Initial analyses suggest that the technique is applicable to a number of hazardous materials such as trichloroethane and carbon tetrachloride.
Date:
July 1993
Creator:
Akers, D. W.
Object Type:
Report
System:
The UNT Digital Library
Fischer-tropsch synthesis in supercritical fluids. Quarterly technical progress report, April 1, 1993--June 30, 1993
We have completed modifications of the Taylor Dispersion Apparatus so that propane can be used as a solvent. Problems were encountered initially compressing propane to the necessary pressures because of cavitation in the liquid pump. This problem was overcome by placing a check valve in the line after the pump and pressures of 2500 psi have been achieved. The system has been pressure tested by using a soap solution on exposed joints and performing a mass balance (leak test). The mass balance was made by reading the volumetric flow rate of liquid in the syringe pump and converting this to expected gas flow rate. The liquid was then vaporized and a dry gas meter measured the amount of gas at the exit of the apparatus. The expected and measured gas flow rates were in excellent agreement, indicating that there are no significant leaks in the system. Presently, we are having problems with the use of UV detection for the dim using compounds. The detector is successfully auto-zeroing with a blank cell and with Co{sub 2}. With the use of instrument grade propane, however, the detector is unable to auto-zero because of absorption of unknown impurity. We believe this problem is …
Date:
July 29, 1993
Creator:
Akgerman, A. & Bukur, D. B.
Object Type:
Report
System:
The UNT Digital Library