Speckle Imaging Over Horizontal Paths (open access)

Speckle Imaging Over Horizontal Paths

Atmospheric aberrations reduce the resolution and contrast in surveillance images recorded over horizontal or slant paths. This paper describes our recent horizontal and slant path imaging experiments of extended scenes as well as the results obtained using speckle imaging. The experiments were performed with an 8-inch diameter telescope placed on either a rooftop or hillside and cover ranges of interest from 0.5 km up to 10 km. The scenery includes resolution targets, people, vehicles, and other structures. The improvement in image quality using speckle imaging is dramatic in many cases, and depends significantly upon the atmospheric conditions. We quantify resolution improvement through modulation transfer function measurement comparisons.
Date: May 21, 2002
Creator: Carrano, C J
Object Type: Article
System: The UNT Digital Library
Detailed spectroscopic analysis of SN 1987A: The distance to the LMC using the SEAM method (open access)

Detailed spectroscopic analysis of SN 1987A: The distance to the LMC using the SEAM method

Supernova 1987A remains the most well-studied supernova to date. Observations produced excellent broad-band photometric and spectroscopic coverage over a wide wavelength range at all epochs. We model the observed spectra from Day 1 to Day 81 using a hydrodynamical model. We show that good agreement can be obtained at times up to about 60 days, if we allow for extended nickel mixing. Later than about 60 days the observed Balmer lines become stronger than our models can reproduce. We show that this is likely due to a more complicated distribution of gamma-rays than we allow for in our spherically symmetric calculations. We present synthetic light curves in UBVRIJHK and a synthetic bolometric light curve. Using this broad baseline of detailed spectroscopic models we find a distance modulus mu = 18.5 +/- 0.2 using the SEAM method of determining distances to supernovae. We find that the explosion time agrees with that of the neutrino burst and is constrained at 68 percent confidence to within +/- 0.9 days. We argue that the weak Balmer lines of our detailed model calculations casts doubt on the accuracy of the purely photometric EPM method. We also suggest that Type IIP supernovae will be most useful …
Date: May 21, 2002
Creator: Mitchell, Robert C.; Baron, E.; Branch, David; Hauschildt, Peter H.; Nugent, Peter E.; Lundqvist, Peter et al.
Object Type: Article
System: The UNT Digital Library
Characterization of Spatial Variability of Hydrogeologic Properties for Unsaturated Flow in the Fractured Rocks at Yucca Mountain, Nevada (open access)

Characterization of Spatial Variability of Hydrogeologic Properties for Unsaturated Flow in the Fractured Rocks at Yucca Mountain, Nevada

The spatial variability of layer-scale hydrogeologic properties of the unsaturated zone (UZ) at Yucca Mountain, Nevada, is investigated using inverse modeling. The thick UZ is grouped into five hydrostratigraphic units and further into 35 hydrogeologic layers. For each layer, lateral variability is represented by the variations in calibrated values of layer-scale properties at different individual deep boreholes. In the calibration model, matrix and fracture properties are calibrated for the one-dimensional vertical column at each individual borehole using the ITOUGH2 code. The objective function is the summation of the weighted misfits between the ambient unsaturated flow (represented by measured state variables: water saturation, water potential, and pneumatic pressure) and the simulated one in the one-dimensional flow system. The objective function also includes the weighted misfits between the calibrated properties and their prior information. Layer-scale state variables and prior rock properties are obtained from their core-scale measurements. Because of limited data, the lateral variability of three most sensitive properties (matrix permeability, matrix of the van Genuchten characterization, and fracture permeability) is calibrated, while all other properties are fixed at their calibrated layer-averaged values. Considerable lateral variability of hydrogeologic properties is obtained. For example, the lateral variability of is two to three orders …
Date: May 21, 2002
Creator: Zhou, Quanlin; Bodvarsson, Gudmundur S.; Liu, Hui-Hai & Oldenburg, Curtis M.
Object Type: Article
System: The UNT Digital Library
Estimating subsurface topography from surface-to-borehole seismic studies at the Rye Patch Geothermal Reservoir (open access)

Estimating subsurface topography from surface-to-borehole seismic studies at the Rye Patch Geothermal Reservoir

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Date: May 21, 2002
Creator: Gritto, Roland; Daley, Thomas M. & Majer, Ernest L.
Object Type: Article
System: The UNT Digital Library
Process Options Description for Steam Reforming Flowsheet Model of INEEL Tank Farm Waste (open access)

Process Options Description for Steam Reforming Flowsheet Model of INEEL Tank Farm Waste

Technical information is provided herein that is required for development of a steady-state process simulation of a baseline steam reforming treatment train for Tank Farm waste at the Idaho National Engineering and Environmental Laboratory (INEEL). This document supercedes INEEL/EXT-2001-173, produced in FY2001 to support simulation of the direct vitrification treatment train which was the previous process baseline. A process block flow diagram for steam reforming is provided, together with a list of unit operations which constitute the process. A detailed description of each unit operation is given which includes its purpose, principal phenomena present, expected pressure and temperature ranges, key chemical species in the inlet steam, and the proposed manner in which the unit operation is to be modeled in the steady state process simulation. Models for the unit operations may be mechanistic (based on first principles), empirical (based solely on pilot test data without extrapolation) , or by correlations (based on extrapolative or statistical schemes applied to pilot test data). Composition data for the expected process feed streams is provided.
Date: May 21, 2002
Creator: Taylor, D. D.; Barnes, C. M. & Nichols, T. T.
Object Type: Report
System: The UNT Digital Library
Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia (open access)

Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia

This report gives results on use of a minipermeameter on cores to study very finescale trends in permeability, and use of neural networks to predict permeability in logged, uncored wells.
Date: May 21, 2002
Creator: Ameri, S.; Aminian, K.; Avary, K. L.; Bilgesu, H. I.; Hohn, M. E.; McDowell, R. R. et al.
Object Type: Report
System: The UNT Digital Library
Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia (open access)

Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia

The purpose of this work was to establish relationships among permeability, geophysical and other data by integrating geologic, geophysical and engineering data into an interdisciplinary quantification of reservoir heterogeneity as it relates to production.
Date: May 21, 2002
Creator: Ameri, S.; Aminian, K.; Avary, K. L.; Bilgesu, H. I.; Hohn, M. E.; McDowell, R. R. et al.
Object Type: Report
System: The UNT Digital Library
Analysis of Site Response at U1A Hole at the Nevada Test Site From Weak Motion Readings (open access)

Analysis of Site Response at U1A Hole at the Nevada Test Site From Weak Motion Readings

We utilize weak motion recordings to evaluate the site response at the U1A hole, Nevada Test site to determine the effect on potential ground motion at the drift of the U1A hole 962 ft deep. We estimated the site response amplification of ground motion at the surface relative to the drift with the spectral ratio method. We utilized Fourier amplitude and absolute acceleration response spectra, and confined our study to frequencies of 0.5 to 25.0 Hz (.04 to 2.0 s periods). We identified 8 earthquakes in the area that were recorded at the bottom and top of the hole that were used for spectral ratios. We calculated the average and one standard deviation of ratios from all the events. Examining the data, we found that: (1) Fourier amplitude spectral ratios provided more detailed information on the site response than the absolute acceleration response that can be directly related to the effect of large earthquakes. (2) plots of the Fourier amplitude spectra for most of the recorded earthquakes show evidence for a spectral hole in the downhole recordings. This is due to downward reflected energy from the surface. This is not evident in absolute acceleration response records. (3) Fourier amplitude spectral …
Date: May 21, 2002
Creator: Hutchings, L & Furrey, L
Object Type: Report
System: The UNT Digital Library
The advanced computational testing and simulation toolkit (ACTS) (open access)

The advanced computational testing and simulation toolkit (ACTS)

During the past decades there has been a continuous growth in the number of physical and societal problems that have been successfully studied and solved by means of computational modeling and simulation. Distinctively, a number of these are important scientific problems ranging in scale from the atomic to the cosmic. For example, ionization is a phenomenon as ubiquitous in modern society as the glow of fluorescent lights and the etching on silicon computer chips; but it was not until 1999 that researchers finally achieved a complete numerical solution to the simplest example of ionization, the collision of a hydrogen atom with an electron. On the opposite scale, cosmologists have long wondered whether the expansion of the Universe, which began with the Big Bang, would ever reverse itself, ending the Universe in a Big Crunch. In 2000, analysis of new measurements of the cosmic microwave background radiation showed that the geometry of the Universe is flat, and thus the Universe will continue expanding forever. Both of these discoveries depended on high performance computer simulations that utilized computational tools included in the Advanced Computational Testing and Simulation (ACTS) Toolkit. The ACTS Toolkit is an umbrella project that brought together a number of …
Date: May 21, 2002
Creator: Drummond, L. A. & Marques, O. A.
Object Type: Article
System: The UNT Digital Library
Imaging of the Self-Excited Oscillation of Flow Past a Cavity During Generation of a Flow Tone (open access)

Imaging of the Self-Excited Oscillation of Flow Past a Cavity During Generation of a Flow Tone

Flow through a pipeline-cavity system can give rise to pronounced flow tones, even when the inflow boundary layer is fully turbulent. Such tones arise from the coupling between the inherent instability of the shear flow past the cavity and a resonant acoustic mode of the system. A technique of high-image-density particle image velocimetry is employed in conjunction with a special test section, which allows effective laser illumination and digital acquisition of patterns of particle images. This approach leads to patterns of velocity, vorticity, streamline topology and hydrodynamic contributions to the acoustic power integral. Comparison of global, instantaneous images with time- and phase-averaged representations provides insight into the small-scale and large-scale concentrations of vorticity, and their consequences on the topological features of Streamline patterns, as well as the streamwise and transverse projections of the hydrodynamic contribution to the acoustic power integral. Furthermore, these global approaches allow the definition of effective wavelengths and phase speeds of the vortical structures, which can lead to guidance for physical models of the dimensionless frequency of oscillation.
Date: May 21, 2002
Creator: Geveci, M.; Oshkai, P.; Rockwell, D.; Lin, J. C. & Pollack, M.
Object Type: Report
System: The UNT Digital Library
K-corrections and extinction corrections for Type Ia supernovae (open access)

K-corrections and extinction corrections for Type Ia supernovae

The measurement of the cosmological parameters from Type Ia supernovae hinges on our ability to compare nearby and distant supernovae accurately. Here we present an advance on a method for performing generalized K-corrections for Type Ia supernovae which allows us to compare these objects from the UV to near-IR over the redshift range 0 < z < 2. We discuss the errors currently associated with this method and how future data can improve upon it significantly. We also examine the effects of reddening on the K-corrections and the light curves of Type Ia supernovae. Finally, we provide a few examples of how these techniques affect our current understanding of a sample of both nearby and distant supernovae.
Date: May 21, 2002
Creator: Nugent, Peter; Kim, Alex & Perlmutter, Saul
Object Type: Article
System: The UNT Digital Library
Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia (open access)

Reservoir Characterization of Upper Devonian Gordon Sandstone, Jacksonburg, Stringtown Oil Field, Northwestern West Virginia

This report gives results of efforts to determine electrofacies from logs; measure permeability in outcrop to study very fine-scale trends; find the correlation between permeability measured by the minipermeameter and in core plugs, define porosity-permeability flow units; and run the BOAST III reservoir simulator using the flow units defined for the Gordon reservoir.
Date: May 21, 2002
Creator: Ameri, S.; Aminian, K.; Avary, K. L.; Bilgesu, H. I.; Hohn, M. E.; McDowell, R. R. et al.
Object Type: Report
System: The UNT Digital Library
Electron cloud effects in intense, ion beam linacs theory and experimental planning for heavy-ion fusion (open access)

Electron cloud effects in intense, ion beam linacs theory and experimental planning for heavy-ion fusion

Heavy-ion accelerators for HIF will operate at high aperture-fill factors with high beam current and long pulses. This will lead to beam ions impacting walls: liberating gas molecules and secondary electrons. Without special preparation a large fractional electron population ({approx}&gt;1%) is predicted in the High-Current Experiment (HCX), but wall conditioning and other mitigation techniques should result in substantial reduction. Theory and particle-in-cell simulations suggest that electrons, from ionization of residual and desorbed gas and secondary electrons from vacuum walls, will be radially trapped in the {approx}4 kV ion beam potential. Trapped electrons can modify the beam space charge, vacuum pressure, ion transport dynamics, and halo generation, and can potentially cause ion-electron instabilities. Within quadrupole (and dipole) magnets, the longitudinal electron flow is limited to drift velocities (E x B and {del}B) and the electron density can vary azimuthally, radially, and longitudinally. These variations can cause centroid misalignment, emittance growth and halo growth. Diagnostics are being developed to measure the energy and flux of electrons and gas evolved from walls, and the net charge and gas density within magnetic quadrupoles, as well as the their effect on the ion beam.
Date: May 21, 2002
Creator: Molvik, A.W.; Cohen, R.H.; Lund, S.M.; Bieniosek, F.M.; Lee, E.P.; Prost, L.R. et al.
Object Type: Article
System: The UNT Digital Library