Distributed Planning and Control for Teams of Cooperating Mobile Robots (open access)

Distributed Planning and Control for Teams of Cooperating Mobile Robots

This CRADA project involved the cooperative research of investigators in ORNL's Center for Engineering Science Advanced Research (CESAR) with researchers at Caterpillar, Inc. The subject of the research was the development of cooperative control strategies for autonomous vehicles performing applications of interest to Caterpillar customers. The project involved three Phases of research, conducted over the time period of November 1998 through December 2001. This project led to the successful development of several technologies and demonstrations in realistic simulation that illustrated the effectiveness of the control approaches for distributed planning and cooperation in multi-robot teams.
Date: June 15, 2004
Creator: Parker, L. E.
Object Type: Report
System: The UNT Digital Library
Characterizing two-phase flow relative permeabilities in chemicalflooding using a pore-scale network model (open access)

Characterizing two-phase flow relative permeabilities in chemicalflooding using a pore-scale network model

A dynamic pore-scale network model is presented for investigating the effects of interfacial tension and oil-water viscosity on relative permeability during chemical flooding. This model takes into account both viscous and capillary forces in analyzing the impact of chemical properties on flow behavior or displacement configuration, as opposed to the conventional or invasion percolation algorithm which incorporates capillary pressure only. The study results indicate that both water and oil relative-permeability curves are dependent strongly on interfacial tension as well as an oil-water viscosity ratio. In particular, water and oil relative-permeability curves are both found to shift upward as interfacial tension is reduced, and they both tend to become linear versus saturation once interfacial tension is at low values. In addition, the oil-water viscosity ratio appears to have only a small effect under conditions of high interfacial tension. When the interfacial tension is low, however, water relative permeability decreases more rapidly (with the increase in the aqueous-phase viscosity) than oil relative permeability. The breakthrough saturation of the aqueous phase during chemical flooding tends to decrease with the reduction of interfacial tension and may also be affected by the oil-water viscosity ratio.
Date: March 15, 2004
Creator: Liu, Qingjie; Shen, Pingping & Wu, Yu-Shu
Object Type: Report
System: The UNT Digital Library
Simplified Design Criteria for Very High Temperature Applications in Generation IV Reactors (open access)

Simplified Design Criteria for Very High Temperature Applications in Generation IV Reactors

The goal of this activity is to provide simplified criteria which can be used in rapid feasibility assessments of the structural viability of very high temperature components in conceptual and early preliminary design phases for Generation IV reactors. The current criteria in ASME Code Section III, Subsection NH, hereafter referred to as NH, (and Code Case N-201 for core support structures) are difficult and require a complex deconstruction of finite element analysis results for their implementation. Further, and most important, times, temperatures and some materials of interest to the very high temperature Generation IV components are not covered by the current provisions of NH. Future revisions to NH are anticipated that will address very high temperature Generation IV components and materials requirements but, until that occurs interim guidance is required for design activities to proceed. These simplified criteria are for design guidance and are not necessarily in rigorous compliance with NH methodology. Rather, the objective is for criteria which address the early design needs of very high temperature Generation IV components and materials. The intent is to provide simplified but not overly conservative design methods. When more rigorous criteria and methods are incorporated in NH, the degree of conservatism should …
Date: December 15, 2004
Creator: McGreevy, TE
Object Type: Report
System: The UNT Digital Library
Deformation behavior of ion-irradiated polyimide (open access)

Deformation behavior of ion-irradiated polyimide

None
Date: March 15, 2004
Creator: Kucheyev, S O; Felter, T E; Anthamatten, M & Bradby, J E
Object Type: Article
System: The UNT Digital Library
Smart Libraries: Best SQE Practices for Libraries with an Emphasis on Scientific Computing (open access)

Smart Libraries: Best SQE Practices for Libraries with an Emphasis on Scientific Computing

As scientific computing applications grow in complexity, more and more functionality is being packaged in independently developed libraries. Worse, as the computing environments in which these applications run grow in complexity, it gets easier to make mistakes in building, installing and using libraries as well as the applications that depend on them. Unfortunately, SQA standards so far developed focus primarily on applications, not libraries. We show that SQA standards for libraries differ from applications in many respects. We introduce and describe a variety of practices aimed at minimizing the likelihood of making mistakes in using libraries and at maximizing users' ability to diagnose and correct them when they occur. We introduce the term Smart Library to refer to a library that is developed with these basic principles in mind. We draw upon specific examples from existing products we believe incorporate smart features: MPI, a parallel message passing library, and HDF5 and SAF, both of which are parallel I/O libraries supporting scientific computing applications. We conclude with a narrative of some real-world experiences in using smart libraries with Ale3d, VisIt and SAF.
Date: December 15, 2004
Creator: Miller, M C; Reus, J F; Matzke, R P; Koziol, Q A & Cheng, A P
Object Type: Article
System: The UNT Digital Library
Polar On-Line Acquisition Relay and Transmission System (POLARATS) (open access)

Polar On-Line Acquisition Relay and Transmission System (POLARATS)

POLARATS (Polar On-Line Acquisition Relay And Transmission System) is being developed by YAHSGS LLC (YAHSGS) and Oak Ridge National Laboratory (ORNL) to provide remote, unattended monitoring of environmental parameters under harsh environmental conditions. In particular, instrumental design and engineering is oriented towards protection of human health in the Arctic, and with the additional goal of advancing Arctic education and research. POLARATS will obtain and transmit environmental data from hardened monitoring devices deployed in locations important to understanding atmospheric and aquatic pollutant migration as it is biomagnified in Arctic food chains. An Internet- and personal computer (PC)-based educational module will provide real time sensor data, on-line educational content, and will be integrated with workbooks and textbooks for use in middle and high school science programs. The educational elements of POLARATS include an Internet-based educational module that will instruct students in the use of the data and how those data fit into changing Arctic environments and food chains. POLARATS will: (1) Enable students, members of the community, and scientific researchers to monitor local environmental conditions in real time over the Internet; and (2) Provide additional educational benefits through integration with middle- and high-school science curricula. Information will be relayed from POLARATS devices …
Date: July 15, 2004
Creator: Yuracko, K.
Object Type: Report
System: The UNT Digital Library
ESTIMATES FOR RELEASE OF RADIONUCLIDES FROM POTENTIALLY CONTAMINATED CONCRETE AT THE HADDAM NECK NUCLEAR PLANT. (open access)

ESTIMATES FOR RELEASE OF RADIONUCLIDES FROM POTENTIALLY CONTAMINATED CONCRETE AT THE HADDAM NECK NUCLEAR PLANT.

Decommissioning of the Haddam Neck Nuclear Power Plant operated by Connecticut Yankee is in progress. Figure 1 shows a schematic of the Containment Building and Spent Fuel Pool (SFP) Building. Consideration is being given to leaving some subsurface concrete from the Containment, Spent Fuel and certain other buildings in place following NRC license termination. Characterization data of most of these structures show small amounts of residual contamination. The In-Core Sump area of the Containment Building has shown elevated levels of tritium, Co-60, Fe-55, and Eu-152 and lesser quantities of other radionuclides due to neutron activation of the concrete in this area. This analysis is provided to determine levels of residual contamination that will not cause releases to the groundwater in excess of the acceptable dose limits. The objective is to calculate a conservative relationship between the radionuclide concentration of subsurface concrete and the maximum groundwater concentration (pCi/L) for the concrete that may remain following license termination at Connecticut Yankee.
Date: September 15, 2004
Creator: SULLIVAN, T.
Object Type: Report
System: The UNT Digital Library
Evolution of the Regional Coda Methodology (open access)

Evolution of the Regional Coda Methodology

For the past decade Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), have been developing and testing a stable, regional coda magnitude methodology for the determination of magnitude and yield. The motivation behind this research was to take advantage of the averaging nature of coda waves in support of monitoring small seismic events from a sparse regional seismic network (e.g., International Monitoring System (IMS) network). The methodology as described in Mayeda et al., (2003) has been successfully applied in a variety of tectonic settings where the assumption of a 1-D, radially symmetric path correction was sufficient. In general, this resulted in inter-station amplitude scatter that was 3-to-4 times smaller than the traditional approach using direct S, Lg and surface waves (0.02< f <8.0-Hz). However, in more laterally complex regions there is a need to extend this approach to account for smaller scale 2-D variations in structure, especially at frequencies above {approx}1-Hz. Recently, Phillips et al., (2003) have applied a 2-D approach to data in central Asia by assuming that the coda envelope amplitude could be idealized as if it were a direct wave. They performed a tomography to invert for Q along the path and through the …
Date: July 15, 2004
Creator: Mayeda, K; Philips, W; Malagnini, L & Dreger, D
Object Type: Article
System: The UNT Digital Library
X-ray Spectropolarimetry of high temperature and high density plasma supported by LLNL Electron Beam Ion Trap Experiments (open access)

X-ray Spectropolarimetry of high temperature and high density plasma supported by LLNL Electron Beam Ion Trap Experiments

Plasma polarization spectroscopy work done by our group since the 3rd US-Japan PPS Workshop is overviewed. Theoretically, the polarization dependence on various electron distribution functions for He-like, Ne-like, and Ni-like x-ray transitions for a wide range of Z has been investigated. In particular, this study was focused on the polarization dependence for monoenergetic and steep electron distribution functions. The diagnostically important spectral lines and features of K-, L-, and M-shell ions were identified which can be used in x-ray spectropolarimetry of plasma. Importance of polarization-sensitive LLNL Electron Beam Ion Trap data is emphasized. The results of the UNR polarization-sensitive Ti and Mo x-pinch experiments are discussed.
Date: March 15, 2004
Creator: Shlyaptseva, A S; Kantsyrev, V L; Ouart, N D; Fedin, D A; Neill, P; Harris, C et al.
Object Type: Article
System: The UNT Digital Library
The Evaluated Gamma-Ray Activation File (EGAF) (open access)

The Evaluated Gamma-Ray Activation File (EGAF)

None
Date: September 15, 2004
Creator: Firestone, R. B.; Molnar, G. L.; Revay, Z.; Belgya, T.; McNabb, D. P. & Sleaford, B.
Object Type: Article
System: The UNT Digital Library
Axisymmetric Tandem Mirrors: Stabilization and Confinement Studies (open access)

Axisymmetric Tandem Mirrors: Stabilization and Confinement Studies

The 'Kinetic Stabilizer' has been proposed as a means of MHD stabilizing an axisymmetric tandem mirror system. The K-S concept is based on theoretical studies by Ryutov, confirmed experimentally in the Gas Dynamic Trap experiment in Novosibirsk. In the K-S beams of ions are directed into the end of an 'expander' region outside the outer mirror of a tandem mirror. These ions, slowed, stagnated, and reflected as they move up the magnetic gradient, produce a low-density stabilizing plasma. At the Lawrence Livermore National Laboratory we have been conducting theoretical and computational studies of the K-S Tandem Mirror. These studies have employed a low-beta code written especially to analyze the beam injection/stabilization process, and a new code SYMTRAN (by Hua and Fowler) that solves the coupled radial and axial particle and energy transport in a K-S TM. Also, a 'legacy' MHD stability code, FLORA, has been upgraded and employed to benchmark the injection/stabilization code and to extend its results to high beta values. The FLORA code studies so far have confirmed the effectiveness of the K-S in stabilizing high-beta (40%) plasmas with stabilizer plasmas the peak pressures of which are several orders of magnitude smaller than those of the confined plasma. …
Date: July 15, 2004
Creator: Post, R F; Fowler, T K; Bulmer, R; Byers, J; Hua, D & Tung, L
Object Type: Article
System: The UNT Digital Library
Statistical Methods and Tools for Uxo Characterization (SERDP Final Technical Report) (open access)

Statistical Methods and Tools for Uxo Characterization (SERDP Final Technical Report)

The Strategic Environmental Research and Development Program (SERDP) issued a statement of need for FY01 titled Statistical Sampling for Unexploded Ordnance (UXO) Site Characterization that solicited proposals to develop statistically valid sampling protocols for cost-effective, practical, and reliable investigation of sites contaminated with UXO; protocols that could be validated through subsequent field demonstrations. The SERDP goal was the development of a sampling strategy for which a fraction of the site is initially surveyed by geophysical detectors to confidently identify clean areas and subsections (target areas, TAs) that had elevated densities of anomalous geophysical detector readings that could indicate the presence of UXO. More detailed surveys could then be conducted to search the identified TAs for UXO. SERDP funded three projects: those proposed by the Pacific Northwest National Laboratory (PNNL) (SERDP Project No. UXO 1199), Sandia National Laboratory (SNL), and Oak Ridge National Laboratory (ORNL). The projects were closely coordinated to minimize duplication of effort and facilitate use of shared algorithms where feasible. This final report for PNNL Project 1199 describes the methods developed by PNNL to address SERDP's statement-of-need for the development of statistically-based geophysical survey methods for sites where 100% surveys are unattainable or cost prohibitive.
Date: November 15, 2004
Creator: Pulsipher, Brent A.; Gilbert, Richard O.; Wilson, John E.; Hassig, Nancy L.; Carlson, Deborah K.; O'Brien, Robert F. et al.
Object Type: Report
System: The UNT Digital Library
Simulation of Regional Explosion S-Phases (SIRES) Project (open access)

Simulation of Regional Explosion S-Phases (SIRES) Project

Generation of S-waves from explosion sources continues to be an intriguing area of seismological research. Empirical studies document a general decrease in regional S-phase amplitudes (compared to P-phases) for explosions sources. Although decreased S-phase amplitude for explosive (compressional) sources is intuitive, a comprehensive physical understanding of the many mechanisms that contribute to S-phase excitation does not currently exist. Despite the success of many regional discriminant and magnitude methods that rely on decreased S-phase amplitude for explosion sources, instances remain where explosions produce anomalous S-phases amplitudes that confound regional methods. Scattering of the Rg phase is forwarded in several studies as an important mechanism for the generation of explosion S-waves. In this study we construct a 3-dimensional model of the Nevada Test Site (NTS) and the surrounding region. Extensive databases of geologic information, including existing 3-dimensional models developed under past and ongoing NTS programs, are used in the construction of a local model. The detailed local model is merged into a regional model that extends several hundred kilometers from the NTS. In addition to deterministic geologic structure and topography we introduce stochastic variability along geologic contacts and within geologic units. Model roughness made possible by the stochastic perturbations enhances scattering, allowing …
Date: July 15, 2004
Creator: Myers, S; Preston, L; Larsen, S; Smith, K & Wlater, W
Object Type: Article
System: The UNT Digital Library
Development of NSTX Particle Control Techniques (open access)

Development of NSTX Particle Control Techniques

NSTX High Harmonic Fast Wave (HHFW) current drive discharges will require density control for acceptable efficiency. We have compared boronization on hot and cold surfaces, varying helium glow discharge conditioning (HeGDC) durations, and brief morning boronization with between discharge boronization for improving density control. Access to Ohmic H-modes was enabled by boronization on hot surfaces, however, the duration of the effectiveness of hot and cold boronization was comparable. A 15 min HeGDC between discharges was needed for reproducible L-H transitions. Brief morning boronization followed by a comparable duration of applied HeGDC restored and enhanced good conditions. Additional short boronizations between discharges did not improve plasma performance (reduced recycling, reduced impurity luminosities, earlier L-H transitions, longer plasma current flattops, higher stored energies) if conditions were already good. Between discharge boronization requires increases in the duty cycle due to the need for additional HeGDC to remove co-deposited D{sub 2}.
Date: June 15, 2004
Creator: Kugel, H; Maingi, R; Bell, M; Gates, D; Hill, K; LeBlanc, B et al.
Object Type: Article
System: The UNT Digital Library
Large Eddy Simulation of an URBAN 2000 Experiment with Various Time-Dependent Forcing (open access)

Large Eddy Simulation of an URBAN 2000 Experiment with Various Time-Dependent Forcing

Under the sponsorship of the U.S. DOE and DHS, we have developed a Computational Fluid Dynamics (CFD) model for simulating airflow and dispersion of chemical/biological agents released in the urban environment. Our model, FEM3MP, is based on solving the three-dimensional, time-dependent, incompressible Navier-Stokes equations on massively parallel computer platforms. The numerical algorithm uses the finite element method for accurate representation of complex building shapes and variable terrain, together with a semi-implicit projection method and modern iterative solvers for efficient time integration (Gresho and Chan, 1998). Physical processes treated in our code include turbulence modeling via the RANS (Reynolds Averaged Navier-Stokes) and LES (Large Eddy Simulation) approaches, atmospheric stability, aerosols, UV radiation decay, surface energy budget, and vegetative canopies, etc.
Date: June 15, 2004
Creator: Chan, Stevens T. & Leach, Martin J.
Object Type: Article
System: The UNT Digital Library
Sacramento River Striped Bass Migration History Determined by Otolith Sr/Ca Ratio (open access)

Sacramento River Striped Bass Migration History Determined by Otolith Sr/Ca Ratio

None
Date: July 15, 2004
Creator: Ostrach, D J; Phillis, C C; Weber, P K; Ingram, B L & Zinkl, J G
Object Type: Article
System: The UNT Digital Library
Heavy Meson Production at a Low-Energy Photon Collider (open access)

Heavy Meson Production at a Low-Energy Photon Collider

A low-energy {gamma}{gamma} collider has been discussed in the context of a testbed for a {gamma}{gamma} interaction region at the Next Linear Collider(NLC). We consider the production of heavy mesons at such a testbed using Compton-backscattered photons and demonstrate that their production rivals or exceeds those by BELLE, BABAR or LEP where they are produced indirectly via virtual {gamma}{gamma} luminosities.
Date: April 15, 2004
Creator: Asztalos, S
Object Type: Article
System: The UNT Digital Library
Progress Report on the Laboratory Testing of the Bulk Vitrification Cast Refractory (open access)

Progress Report on the Laboratory Testing of the Bulk Vitrification Cast Refractory

The Hanford Site in southeastern Washington State has been used extensively to produce nuclear materials for the U. S. strategic defense arsenal by the U. S. Department of Energy (DOE). A large inventory of radioactive and mixed waste has accumulated in 177 single- and double-shell tanks. Liquid waste recovered from the tanks will be pre-treated to separate the low-activity fraction from the high-level and transuranic wastes. Currently, the DOE Office of River Protection (ORP) is evaluating several options for immobilization of low-activity tank wastes for eventual disposal in a shallow subsurface facility at the Hanford Site. A significant portion of the waste will be converted into immobilized low-activity waste (ILAW) glass with a conventional Joule-heated ceramic melter. In addition to ILAW glass, supplemental treatment technologies are under consideration by the DOE to treat a portion of the low activity waste. The reason for using this alternative treatment technology is to accelerate the overall cleanup mission at the Hanford site. The ORP selected Bulk Vitrification (BV) for further development and testing. Work in FY03 on engineered and large scale tests of the BV process suggested that approximately 0.3 to as much as 3 wt% of the waste stream 99Tc inventory would …
Date: November 15, 2004
Creator: Pierce, Eric M.; McGrail, B PETER.; Bagaasen, Larry M.; Wellman, Dawn M.; Crum, J V.; Geiszler, Keith N. et al.
Object Type: Report
System: The UNT Digital Library
Edward Teller's Scientific Life (open access)

Edward Teller's Scientific Life

Edward Teller was one of the great physicists of the twentieth century. His career began just after the key ideas of the quantum revolution of the 1920's were completed, opening vast areas of physics and chemistry to detailed understanding. Thus, his early work in theoretical physics focused on applying the new quantum theory to the understanding of diverse phenomena. These topics included chemical physics, diamagnetism, and nuclear physics. Later, he made key contributions to statistical mechanics, surface physics, solid state, and plasma physics. In many cases, the ideas in these papers are still rich with important ramifications.
Date: April 15, 2004
Creator: Libby, S B & Weiss, M S
Object Type: Article
System: The UNT Digital Library
Accessing High Pressure States Relevant to Core Conditions in the Giant Planets (open access)

Accessing High Pressure States Relevant to Core Conditions in the Giant Planets

We have designed an experimental technique to use on the National Ignition Facility (NIF) laser to achieve very high pressure (P{sub max} > 10 Mbar = 1000 GPa), dense states of matter at moderate temperatures (kT < 0.5 eV = 6000 K), relevant to the core conditions of the giant planets. A discussion of the conditions in the interiors of the giant planets is given, and an experimental design that can approach those conditions is described.
Date: April 15, 2004
Creator: Remington, B. A.; Cavallo, R. M.; Edwards, M. J.; Ho, D. D.; Lorenz, K. T.; Lorenzana, H. E. et al.
Object Type: Article
System: The UNT Digital Library
Vacuum Technology (open access)

Vacuum Technology

The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in …
Date: October 15, 2004
Creator: Biltoft, P. J.
Object Type: Book
System: The UNT Digital Library
Programmed Cell Death During Female Gametophyte Development (open access)

Programmed Cell Death During Female Gametophyte Development

Endosperm is a storage tissue in the angiosperm seed that is important both biologically and agriculturally. Endosperm is biologically important because it provides nutrients to the embryo during seed development and agriculturally important because it is a significant source of food, feed, and industrial raw materials. Approximately two-thirds of human calories are derived from endosperm, either directly or indirectly through animal feed. Furthermore, endosperm is used as a raw material for numerous industrial products including ethanol. A major event in endosperm development is the transition between the syncytial phase, during which the endosperm nuclei undergo many rounds of mitosis without cytokinesis, and the cellularized phase, during which cell walls form around the endosperm nuclei. Understanding how the syncytial-cellular transition is regulated is agriculturally important because it influences seed size, seed sink strength, and grain weight. However, the molecular processes controlling this transition are not understood. This project led to the identification of the AGL62 gene that regulates the syncytial-cellular transition during endosperm development. AGL62 is expressed during the syncytial phase and suppresses endosperm cellularization during this period. AGL62 most likely does so by suppressing the expression of genes required for cellularization. At the end of the syncytial phase, the FIS …
Date: September 15, 2004
Creator: Drews, Gary, N.
Object Type: Report
System: The UNT Digital Library
Thermal Damage on LX-04 Mock Material and Gas Permeability Assessment (open access)

Thermal Damage on LX-04 Mock Material and Gas Permeability Assessment

RM-04-BR, a mock material for the plastic-bonded HMX-based explosive LX-04, is characterized after being thermally damaged at 140 C and 190 C. We measured the following material properties before and after the thermal experiments: sample volume, density, sound speed, and gas permeability in the material. Thermal treatment of the mock material leads to de-coloring and insignificant weight loss. Sample expanded, resulting in density reductions of 1.0% to 2.5% at 140 C and 190 C, respectively. Permeability in the mock samples was found to increase from 10{sup -15} to 10{sup -16} m{sup 2}, as the porosity increased. The permeability measurements are well represented by the Blake-Kozeny equation for laminar flow through porous media. The results are similar to the gas permeability in PBX-9501 obtained by other researchers.
Date: November 15, 2004
Creator: Hsu, P C; Dehaven, M; McClelland, M & Maienschein, J
Object Type: Article
System: The UNT Digital Library
Methanol Steam Reformer on a Silicon Wafer (open access)

Methanol Steam Reformer on a Silicon Wafer

A study of the reforming rates, heat transfer and flow through a methanol reforming catalytic microreactor fabricated on a silicon wafer are presented. Comparison of computed and measured conversion efficiencies are shown to be favorable. Concepts for insulating the reactor while maintaining small overall size and starting operation from ambient temperature are analyzed.
Date: April 15, 2004
Creator: Park, H; Malen, J; Piggott, T; Morse, J; Sopchak, D; Greif, R et al.
Object Type: Article
System: The UNT Digital Library