2-D Simulations of Drainage Winds and Diffusion Compared to Observations (open access)

2-D Simulations of Drainage Winds and Diffusion Compared to Observations

A vertically integrated dynamical drainage flow model is developed from conservation equations for momentum and mass in a terrain-following coordinate system. Wind fields from the dynamical model drive a Monte Carlo transport and diffusion model. The model needs only topographic data, an Eulerian or Lagrangian time scale and a surface drag coefficient for input data, and can be started with a motionless atmosphere. Model wind and diffusion predictions are compared to observations from the rugged Geysers CA area. Model winds generally agree with observed surface winds, and in some cases may give better estimates of area-averaged flow than point observations. Tracer gas concentration contours agree qualitatively with observed contours, and point predictions of maximum concentrations were correctly predicted to within factors of 2 to 10. Standard statistical tests of model skill showed that the accuracy of the predictions varied significantly from canyon to canyon in the Geysers are a. Model wind predictions are also compared to observations from the Savannah River Plant of SC which has gently rolling terrain. The model correctly simulated the slower development of drainage winds and slower deepening of the drainage layer in the Savannah River Valley, relative to the Geysers CA simulations. The SC simulations …
Date: May 29, 2001
Creator: Garrett, A. J.
System: The UNT Digital Library
2001 Gordon Research Conference on MYOGENESIS (open access)

2001 Gordon Research Conference on MYOGENESIS

The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.
Date: May 4, 2001
Creator: unknown
System: The UNT Digital Library
Adaptive Position and Orientation Regulation for the Camera-in-hand Problem (open access)

Adaptive Position and Orientation Regulation for the Camera-in-hand Problem

None
Date: May 31, 2001
Creator: Setlur, P
System: The UNT Digital Library
Advanced Aerodynamic Devices to Improve the Performance, Economics, Handling, and Safety of Heavy Vehicles (open access)

Advanced Aerodynamic Devices to Improve the Performance, Economics, Handling, and Safety of Heavy Vehicles

Research is being conducted at the Georgia Tech Research Institute (GTRI) to develop advanced aerodynamic devices to improve the performance, economics, stability, handling and safety of operation of Heavy Vehicles by using previously-developed and flight-tested pneumatic (blown) aircraft technology. Recent wind-tunnel investigations of a generic Heavy Vehicle model with blowing slots on both the leading and trailing edges of the trailer have been conducted under contract to the DOE Office of Heavy Vehicle Technologies. These experimental results show overall aerodynamic drag reductions on the Pneumatic Heavy Vehicle of 50% using only 1 psig blowing pressure in the plenums, and over 80% drag reductions if additional blowing air were available. Additionally, an increase in drag force for braking was confirmed by blowing different slots. Lift coefficient was increased for rolling resistance reduction by blowing only the top slot, while downforce was produced for traction increase by blowing only the bottom. Also, side force and yawing moment were generated on either side of the vehicle, and directional stability was restored by blowing the appropriate side slot. These experimental results and the predicted full-scale payoffs are presented in this paper, as is a discussion of additional applications to conventional commercial autos, buses, motor …
Date: May 14, 2001
Creator: Englar, Robert J.
System: The UNT Digital Library
Aggregation and metal ion extraction properties of novel, silicon-substituted alkylenediphosphonic acids. (open access)

Aggregation and metal ion extraction properties of novel, silicon-substituted alkylenediphosphonic acids.

In conjunction with efforts to develop novel actinide extractants exhibiting solubility in supercritical carbon dioxide, the effect of adding silicon-based functionalities to diphosphonic acids has been investigated. Specifically, a series of silyl-substituted diphosphonic acids has been prepared and characterized, and their aggregation and metal ion extraction properties compared with alkyl-substituted diphosphonic acids, reagents previously demonstrated to be effective extractants of actinides from acidic aqueous media into various organic solvents. In addition, the influence of the number of methylene groups bridging the phosphorus atoms of the diphosphonic acids on their extraction behavior has been investigated. Variations in the extraction behavior of the compounds arising from differences in the number of bridging methylene groups have been shown to be attributable to a combination of factors, in particular, the aggregation state of the ligand, the size of the chelate rings formed upon complexation, the basicity of the phosphoryl group and the relative acidities of the ligands.
Date: May 10, 2001
Creator: McAlister, D. R.; Dietz, M. L.; Chiarizia, R. & Herlinger, A. W.
System: The UNT Digital Library
Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Three-Year Results with Third-Generation Blowing Agents (open access)

Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Three-Year Results with Third-Generation Blowing Agents

Laboratory data are presented on the effect of constant-temperature aging on the apparent thermal conductivity of polyurethane foam insulation for refrigerators and freezers. The foam specimens were blown with HCFC-141b and with three of its potential replacements--HFC-134a, HFC-245fa, and cyclopentane. Specimens were aged at constant temperatures of 90 F, 40 F, and -10 F. Thermal conductivity measurements were made on two types of specimens: full-thickness simulated refrigerator panels containing foam enclosed between solid plastic sheets, and thin slices of core foam cut from similar panels. Results are presented for the first three years of a multi-year aging study. Preliminary comparisons of measured data with predictions of a mathematical aging model are presented.
Date: May 29, 2001
Creator: Wilkes, K. E.
System: The UNT Digital Library
An Algorithm for Projecting Points onto a Patched CAD Model (open access)

An Algorithm for Projecting Points onto a Patched CAD Model

We are interested in building structured overlapping grids for geometries defined by computer-aided-design (CAD) packages. Geometric information defining the boundary surfaces of a computation domain is often provided in the form of a collection of possibly hundreds of trimmed patches. The first step in building an overlapping volume grid on such a geometry is to build overlapping surface grids. A surface grid is typically built using hyperbolic grid generation; starting from a curve on the surface, a grid is grown by marching over the surface. A given hyperbolic grid will typically cover many of the underlying CAD surface patches. The fundamental operation needed for building surface grids is that of projecting a point in space onto the closest point on the CAD surface. We describe an fast algorithm for performing this projection, it will make use of a fairly coarse global triangulation of the CAD geometry. We describe how to build this global triangulation by first determining the connectivity of the CAD surface patches. This step is necessary since it often the case that the CAD description will contain no information specifying how a given patch connects to other neighboring patches. Determining the connectivity is difficult since the surface patches …
Date: May 29, 2001
Creator: Henshaw, W D
System: The UNT Digital Library
ANALOG QUANTUM NEURON FOR FUNCTIONS APPROXIMATION (open access)

ANALOG QUANTUM NEURON FOR FUNCTIONS APPROXIMATION

We describe a system able to perform universal stochastic approximations of continuous multivariable functions in both neuron-like and quantum manner. The implementation of this model in the form of multi-barrier multiple-silt system has been earlier proposed. For the simplified waveguide variant of this model it is proved, that the system can approximate any continuous function of many variables. This theorem is also applied to the 2-input quantum neural model analogical to the schemes developed for quantum control.
Date: May 1, 2001
Creator: EZHOV, A.; KHROMOV, A. & BERMAN, G.
System: The UNT Digital Library
ANALYSIS OF DATA FROM THE LEDA WIRE SCANNER/HALO SCRAPER (open access)

ANALYSIS OF DATA FROM THE LEDA WIRE SCANNER/HALO SCRAPER

A new diagnostic has been designed and commissioned that measures the profile of the beam in the halo channel of the Low Energy Demonstration Accelerator at the Los Alamos National Laboratory. This paper describes the algorithms written to analyze the data from that diagnostic, a combined wire scanner and halo scraper. These algorithms determine the safe insertions limit of the scrapers, spatially differentiate the scraper signal, amalgamate the wire scanner data with the differentiated scraper data, determine when both the core and combined distributions rise above the noise floor, and compute the moments of the combined distribution. Results of applying the algorithms to data acquired during experiments matching the beam into the halo channel are presented.
Date: May 1, 2001
Creator: KAMPERSCHROER, J.; O'HARA, J. & A, ET
System: The UNT Digital Library
An Analysis of Gas Pressure Forming of Superplastic AL 5083 Alloy (open access)

An Analysis of Gas Pressure Forming of Superplastic AL 5083 Alloy

Al 5083 disks of a superplastic forming grade were gas-pressure formed to hemispheres and cones at constant forming pressures with and without back pressure. The forming operation was performed using an in-house designed and built biaxial forming apparatus. The temporal change of dome heights of the hemispheres and cones were measured for the different forming and back pressures applied. The flow stresses and strain rates developed at the top of the dome during the forming step were shown to closely follow the flow stress-strain rate relationship obtained from the strain rate change tests performed at the same temperature using uniaxial tensile samples.
Date: May 4, 2001
Creator: Syn, C K; O'Brien, M J; Lesuer, D R & Sherby, O D
System: The UNT Digital Library
Analysis of Statically Indeterminate Tie-Down Systems (open access)

Analysis of Statically Indeterminate Tie-Down Systems

The purpose of this analysis is to propose and qualify a design of the tie-down system for the High Level Waste (HLW) pump/agitator transport container.
Date: May 30, 2001
Creator: Wu, T.
System: The UNT Digital Library
Antinucleus productions at RHIC (open access)

Antinucleus productions at RHIC

Light antinuclei may be formed in relativistic heavy ion collisions via final state coalescence of antinucleons. The yields of antinuclei are sensitive to primordial antinucleon production, the volume of the system at kinetic freeze-out, and space-momentum correlations among antinucleons at freeze-out. We report here preliminary STAR results on {bar d} and {bar {sup 3}He} production in 130A GeV Au+Au collisions. These results are examined in a coalescence framework to elucidate the space-time structure of the antinucleon source.
Date: May 1, 2001
Creator: Hardtke, D.
System: The UNT Digital Library
Are Topological Charge Fluctuations in QCD Instanton Dominated? (open access)

Are Topological Charge Fluctuations in QCD Instanton Dominated?

We consider a recent proposal by Horvath et al. to address the question whether topological charge fluctuations in QCD are instanton dominated via the response of fermions using lattice fermions with exact chiral symmetry, the overlap fermions. Considering several volumes and lattice spacings we find strong evidence for chirality of a finite density of low-lying eigenvectors of the overlap-Dirac operator in the regions where these modes are peaked. This result suggests instanton dominance of topological charge fluctuations in quenched QCD.
Date: May 1, 2001
Creator: Edwards, Robert G. & Heller, Urs M.
System: The UNT Digital Library
Army Solid State Laser Program: Design, Operation, and Mission Analysis for a Heat-Capacity Laser (open access)

Army Solid State Laser Program: Design, Operation, and Mission Analysis for a Heat-Capacity Laser

Solid-state lasers have held great promise for the generation of high-average-power, high-quality output beams for a number of decades. However, the inherent difficulty of scaling the active solid-state gain media while continuing to provide efficient cooling has limited demonstrated powers to <5kW. Even at the maximum demonstrated average powers, the output is most often delivered as continuous wave (CW) or as small energy pulses at high pulse repetition frequency (PRF) and the beam divergence is typically >10X the diffraction limit. Challenges posed by optical distortions and depolarization arising from internal temperature gradients in the gain medium of a continuously cooled system are only increased for laser designs that would attempt to deliver the high average power in the form of high energy pulses (>25J) from a single coherent optical aperture. Although demonstrated phase-locking of multiple laser apertures may hold significant promise for the future scaling of solid-state laser systems,1 the continuing need for additional technical development and innovation coupled with the anticipated complexity of these systems effectively limits this approach for near-term multi-kW laser operation outside of a laboratory setting. We have developed and demonstrated a new operational mode for solid-state laser systems in which the cooling of the gain …
Date: May 18, 2001
Creator: Dane, C. B.; Flath, L.; Rotter, M.; Fochs, S.; Brase, J. & Bretney, K.
System: The UNT Digital Library
The ASCI PSE Milepost: Run-Time Systems Performance Tests (open access)

The ASCI PSE Milepost: Run-Time Systems Performance Tests

The Accelerated Strategic Computing Initiative (ASCI) Problem Solving Environment (PSE) consists of the tools and libraries needed for the development of ASCI simulation codes on ASCI machines. The recently completed ASCI PSE Milepost demonstrated that this software environment is available and functional at the scale used for application mileposts on ASCI White. As part of the PSE Milepost, we performed extensive performance testing of several critical run-time based systems. In this paper, we present microbenchmark results that compare the MPI [5], Pthreads and OpenMP [7, 8] implementations on ASCI White and ASCI Blue Pacific. Our results demonstrate that these run-time systems on White have improved sufficiently to accommodate the machine's approximately four-fold increase in processing capability over Blue Pacific.
Date: May 7, 2001
Creator: de Supinski, B R
System: The UNT Digital Library
Bayesian Spectroscopy and Target Tracking (open access)

Bayesian Spectroscopy and Target Tracking

Statistical analysis gives a paradigm for detection and tracking of weak-signature sources that are moving among a network of detectors. The detector platforms compute and exchange information with near-neighbors in the form of Bayesian probabilities for possible sources. This can shown to be an optimal scheme for the use of detector information and communication resources. Here, we apply that paradigm to the detection and discrimination of radiation sources using multi-channel gamma-ray spectra. We present algorithms for the reduction of detector data to probability estimates and the fusion of estimates among multiple detectors. A primary result is the development of a goodness-of-fit metric, similar to {chi}{sup 2}, for template matching that is statistically valid for spectral channels with low expected counts. Discrimination of a target source from other false sources and detection of imprecisely known spectra are the main applications considered. We use simulated NaI spectral data to demonstrate the Bayesian algorithm compare it to other techniques. Results of simulations of a network of spectrometers are presented, showing its capability to distinguish intended targets from nuisance sources.
Date: May 1, 2001
Creator: Cunningham, C
System: The UNT Digital Library
Beam Charge Asymmetry Monitors for Low Intensity Continuous Electron Beam (open access)

Beam Charge Asymmetry Monitors for Low Intensity Continuous Electron Beam

Experimental Hall B at Jefferson Lab typically operates with CW electron beam currents in the range of 1 - 10 nA. This low beam current coupled with a 30 Hz flip rate of the beam helicity required the development of new devices to measure and monitor the beam charge asymmetry. We have developed four independent devices with sufficient bandwidth for readout at 30 Hz rate: a synchrotron light monitor (SLM), two backward optical transition radiation monitors (OTR) and a Faraday Cup. Photomultipliers operating in current mode provided the readout of the light from the SLM and the OTRs, while high bandwidth electronics provided the readout from the Faraday cup. Using {approximately}6 helicity pairs, we measured the beam charge asymmetry to a statistically accuracy which is better than 0.05%. We present the results from the successful operation of these devices during the fall 2000 physics program. The reliability and the bandwidth of the devices allowed us to control the gain on the source laser by means of a feedback loop.
Date: May 1, 2001
Creator: Denard, Jean-Claude; Freyberger, Arne P. & Sharabian, Youri
System: The UNT Digital Library
Boundary Conditions for Dislocation Dynamics Simulations and Stage 0 of BCC Metals at Low Temperature (open access)

Boundary Conditions for Dislocation Dynamics Simulations and Stage 0 of BCC Metals at Low Temperature

In order to study the dislocation density evolution of body centered cubic (bcc) crystals at low temperature by dislocation dynamics (DD) simulations, we investigated carefully three different boundary conditions (BC) for DD, i.e., the quasi-free surface BC, the flux-balanced BC, and the periodic BC. The latter two BCs can account for the dislocation loss from the boundary of the finite simulation box. PBC can also eliminate the influence of surfaces and improve the line connectivity. We have found that the PBC provides a convenient and effective boundary condition for DD simulations and have applied it to the study of dislocation density evolution of bcc metals during stage 0 deformation at low temperature.
Date: May 1, 2001
Creator: Tang, M & Kubin, L P
System: The UNT Digital Library
Busch's theorem for mappings (open access)

Busch's theorem for mappings

For rotation-invariant Hamiltonian systems, canonical angular momentum is conserved. In beam optics, this statement is known as Busch's theorem. This theorem can be generalized to symplectic mappings; two generalizations are presented in this paper. The first one states that a group of rotation-invariant mappings is identical to a group of the angular-momentum preserving mappings, assuming both of them symplectic and linear. The second generalization of Busch's theorem claims that for any beam which rotation symmetry happened to be preserved, an absolute value of the angular momentum of any particle from this beam is preserved as well; the linear symplectic mapping does not have to be rotation-invariant here.
Date: May 29, 2001
Creator: Burov, A.
System: The UNT Digital Library
CALCULATING ACCURATE SHUFFLER COUNT RATES WITH APPLICATIONS (open access)

CALCULATING ACCURATE SHUFFLER COUNT RATES WITH APPLICATIONS

Shufflers are used to assay uranium and other fissile elements in bulk and waste quantities. They normally require physical calibration standards to achieve the most-accurate results, but such standards are generally rare and expensive, so inappropriate standards are often used out of necessity. This paper reports on a new technique that has been developed to calculate accurate count rates, in effect simulating physical standards with rapid and inexpensive calculations. The technique has been benchmarked on existing oxide and metallic standards, used to study a variety of conditions for which standards do not exist, and applied to inventory items needing verification measurements even though appropriate physical standards do not exist.
Date: May 1, 2001
Creator: RINARD, P. M.
System: The UNT Digital Library
Capacity investigation of brine-bearing sands of the Fwwm formation for geologic sequestration of CO{sub 2} (open access)

Capacity investigation of brine-bearing sands of the Fwwm formation for geologic sequestration of CO{sub 2}

The capacity of fluvial brine-bearing formations to sequester CO{sub 2} is investigated using numerical simulations of CO{sub 2} injection and storage. Capacity is defined as the volume fraction of the subsurface available for CO{sub 2} storage and is conceptualized as a product of factors that account for two-phase flow and transport processes, formation geometry, formation heterogeneity, and formation porosity. The space and time domains used to define capacity must be chosen with care to obtain meaningful results, especially when comparing different authors' work. Physical factors that impact capacity include permeability anisotropy and relative permeability to CO{sub 2}, brine/CO{sub 2} density and viscosity ratios, the shape of the trapping structure, formation porosity and the presence of low-permeability layering.
Date: May 1, 2001
Creator: Doughty, Christine; Pruess, Karsten; Benson, Sally M.; Hovorka, Susan D.; Knox, Paul R. & Green, Christopher T.
System: The UNT Digital Library
Cerro Grande Fire- From Wildfire Modeling Through the Fire Aftermath (open access)

Cerro Grande Fire- From Wildfire Modeling Through the Fire Aftermath

The Cerro Grande Fire developed from a prescibed burn by the National Park Service at Bandelier National Monument near Los Alamos, New Mexico. When the burn went out of control and became a wildfire, i attracted worldwide attention because it threateed the birthplace of the atomic bomb, Los Alamos National Laboratory (LANL)
Date: May 1, 2001
Creator: Rudell, T. & Gille, R.
System: The UNT Digital Library
Characterization of free-standing hydride vapor phase epitaxy GaN (open access)

Characterization of free-standing hydride vapor phase epitaxy GaN

None
Date: May 22, 2001
Creator: Jasinski, J.; Swider, W.; Liliental-Weber, Z.; Visconti, P.; Jones, K. M.; Reschchikov, M. A. et al.
System: The UNT Digital Library
The China Motor Systems Energy Conservation Program: A major national initiative to reduce motor system energy use in China (open access)

The China Motor Systems Energy Conservation Program: A major national initiative to reduce motor system energy use in China

Electric motor systems are widely used in China to power fans, pumps, blowers, air compressors, refrigeration compressors, conveyers, machinery, and many other types of equipment. Overall, electric motor systems consume more than 600 billion kWh annually, accounting for more than 50 percent of China's electricity use. There are large opportunities to improve the efficiency of motor systems. Electric motors in China are approximately 2-4 percent less efficient on average than motors in the U.S. and Canada. Fans and pumps in China are approximately 3-5 percent less efficient than in developed countries. Even more importantly, motors, fans, pumps, air compressors and other motor-driven equipment are frequently applied with little attention to system efficiency. More optimized design, including appropriate sizing and use of speed control strategies, can reduce energy use by 20 percent or more in many applications. Unfortunately, few Chinese enterprises use or even know about these energy-saving practices. Opportunities for motor system improvements are probably greater in China than in the U.S. In order to begin capturing these savings, China is establishing a China Motor Systems Energy Conservation Program. Elements of this program include work to develop minimum efficiency standards for motors, a voluntary ''green motor'' labeling program for high-efficiency …
Date: May 31, 2001
Creator: Nadel, Steven; Wang, Wanxing; Liu, Peter & McKane, Aimee T.
System: The UNT Digital Library