Three-Dimensional Analysis of Voids in AM60B Magnesium Tensile Bars Using Computed Tomography Imagery (open access)

Three-Dimensional Analysis of Voids in AM60B Magnesium Tensile Bars Using Computed Tomography Imagery

In an effort to increase automobile fuel efficiency as well as decrease the output of harmful greenhouse gases, the automotive industry has recently shown increased interest in cast light metals such as magnesium alloys in an effort to increase weight savings. Currently several magnesium alloys such as AZ91 and AM60B are being used in structural applications for automobiles. However, these magnesium alloys are not as well characterized as other commonly used structural metals such as aluminum. This dissertation presents a methodology to nondestructively quantify damage accumulation due to void behavior in three dimensions in die-cast magnesium AM60B tensile bars as a function of mechanical load. Computed tomography data was acquired after tensile bars were loaded up to and including failure, and analyzed to characterize void behavior as it relates to damage accumulation. Signal and image processing techniques were used along with a cluster labeling routine to nondestructively quantify damage parameters in three dimensions. Void analyses were performed including void volume distribution characterization, nearest neighbor distance calculations, shape parameters, and volumetric renderings of voids in the alloy. The processed CT data was used to generate input files for use in finite element simulations, both two- and three-dimensional. The void analyses revealed …
Date: May 1, 2001
Creator: Waters, A M
Object Type: Report
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
Object Type: Article
System: The UNT Digital Library
Transverse Coupling Impedance of the RHIC Abort Kicker (open access)

Transverse Coupling Impedance of the RHIC Abort Kicker

N/A
Date: May 1, 2001
Creator: H., Hahn & Davino, D.
Object Type: Report
System: The UNT Digital Library
Role of Electricity Markets and Market Design in Integrating Solar Generation: Solar Integration Series. 2 of 3 (Brochure) (open access)

Role of Electricity Markets and Market Design in Integrating Solar Generation: Solar Integration Series. 2 of 3 (Brochure)

The second out of a series of three fact sheets describing the role of electricity markets and market design in integrating solar generation.
Date: May 1, 2001
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Luminosity Upgrade Options for RHIC (open access)

Luminosity Upgrade Options for RHIC

N/A
Date: May 1, 2001
Creator: MacKay, W.
Object Type: Report
System: The UNT Digital Library
The Design and Analysis of Salmonid Tagging Studies in the Columbia Basin : Volume XVII : Effects of Ocean Covariates and Release Timing on First Ocean-Year Survival of Fall Chinook Salmon from Oregon and Washington Coastal Hatcheries. (open access)

The Design and Analysis of Salmonid Tagging Studies in the Columbia Basin : Volume XVII : Effects of Ocean Covariates and Release Timing on First Ocean-Year Survival of Fall Chinook Salmon from Oregon and Washington Coastal Hatcheries.

Effects of oceanographic conditions, as well as effects of release-timing and release-size, on first ocean-year survival of subyearling fall chinook salmon were investigated by analyzing CWT release and recovery data from Oregon and Washington coastal hatcheries. Age-class strength was estimated using a multinomial probability likelihood which estimated first-year survival as a proportional hazards regression against ocean and release covariates. Weight-at-release and release-month were found to significantly effect first year survival (p < 0.05) and ocean effects were therefore estimated after adjusting for weight-at-release. Negative survival trend was modeled for sea surface temperature (SST) during 11 months of the year over the study period (1970-1992). Statistically significant negative survival trends (p < 0.05) were found for SST during April, June, November and December. Strong pairwise correlations (r > 0.6) between SST in April/June, April/November and April/December suggest the significant relationships were due to one underlying process. At higher latitudes (45{sup o} and 48{sup o}N), summer upwelling (June-August) showed positive survival trend with survival and fall (September-November) downwelling showed positive trend with survival, indicating early fall transition improved survival. At 45{sup o} and 48{sup o}, during spring, alternating survival trends with upwelling were observed between March and May, with negative trend occurring …
Date: May 1, 2001
Creator: Burgess, Caitlin & Skalski, John R.
Object Type: Report
System: The UNT Digital Library
Monitoring and Evaluation of Smolt Migration in the Columbia Basin : Volume VII : Evaluation of the Compliance Testing Framework for RPA Improvement as Stated in the 2000 Federal Columbia River Power System (FCRPS) Biological Opinion. (open access)

Monitoring and Evaluation of Smolt Migration in the Columbia Basin : Volume VII : Evaluation of the Compliance Testing Framework for RPA Improvement as Stated in the 2000 Federal Columbia River Power System (FCRPS) Biological Opinion.

Using the pre-2000 reach survival probabilities reported in the 2000 FCRPS Biological Opinion (BO) for three selected stocks: yearling and sub-yearling chinook and steelhead, power curves were constructed for each of the two statistical hypothesis tests suggested in the BO. These power calculation results were interpreted in terms of the ability of the statistical tests to correctly identify the true states of recovery (i.e., fail or succeed in fulfilling RPA expectations). The proposed one-sided tests have a moderate to low probability of correctly assessing the true status of the recovery by the years 2005 and 2008. The relatively poor odds of making the correct decision with the BO proposed Tests 1 and 2 suggest alternative decision rules need to be investigated and developed for assessing RPA compliance. Therefore, we propose to immediately examine alternative decision rules that might maximize the likelihood of correct decisions while minimizing the prospect of incorrect decisions. The Bayesian analysis will incorporate scientific/biological knowledge/expertise.
Date: May 1, 2001
Creator: Skalski, John R. & Ngouenet, Roger F.
Object Type: Report
System: The UNT Digital Library
Simulation of Tailrace Hydrodynamics Using Computational Fluid Dynamics Models (open access)

Simulation of Tailrace Hydrodynamics Using Computational Fluid Dynamics Models

This report investigates the feasibility of using computational fluid dynamics (CFD) tools to investigate hydrodynamic flow fields surrounding the tailrace zone below large hydraulic structures. Previous and ongoing studies using CFD tools to simulate gradually varied flow with multiple constituents and forebay/intake hydrodynamics have shown that CFD tools can provide valuable information for hydraulic and biological evaluation of fish passage near hydraulic structures. These studies however are incapable of simulating the rapidly varying flow fields that involving breakup of the free-surface, such as those through and below high flow outfalls and spillways. Although the use of CFD tools for these types of flow are still an active area of research, initial applications discussed in this report show that these tools are capable of simulating the primary features of these highly transient flow fields.
Date: May 1, 2001
Creator: Cook, Christopher B. & Richmond, Marshall C.
Object Type: Report
System: The UNT Digital Library
Evaluation of the Fish Passage Effectiveness of the Bonneville I Prototype Surface Collector using Three-Dimensional Ultrasonic Fish Tracking (open access)

Evaluation of the Fish Passage Effectiveness of the Bonneville I Prototype Surface Collector using Three-Dimensional Ultrasonic Fish Tracking

This report describes tests conducted at Bonneville Dam on the Columbia River in the spring of 2000 using three-dimensional acoustic telemetry and computational fluid dynamics hydraulic modeling to observe the response of outmigrating juvenile steelhead and yearling chinook to a prototype surface collector installed at the Powerhouse. The study described in this report was one of several conducted for the U.S. Army Corps of Engineers to prepare a decision document on which of two bypass methods: surface flow bypass or extended-length submersible bar screens to use to help smolts pass around Bonneville dams without going through the turbines.
Date: May 1, 2001
Creator: Faber, Derrek M.; Weiland, Mark A.; Moursund, Robert; Carlson, Thomas J.; Adams, Noah & Rhondorf, D.
Object Type: Report
System: The UNT Digital Library
Analytical Field Calculation of Helical Magnets with an Axially Symmetric Iron Yoke (open access)

Analytical Field Calculation of Helical Magnets with an Axially Symmetric Iron Yoke

N/A
Date: May 1, 2001
Creator: T., Tominaka; Okamura, M. & Katayama, T.
Object Type: Report
System: The UNT Digital Library
ESH&Q Liability Assessment Report of Treatment One (open access)

ESH&Q Liability Assessment Report of Treatment One

None
Date: May 1, 2001
Creator: Becker, William Joseph; Rohe, Rhonda Diane & Thomps
Object Type: Report
System: The UNT Digital Library
Energy Matters - May/June 2001 (Newsletter) (open access)

Energy Matters - May/June 2001 (Newsletter)

Bimonthly newsletter from DOE's Office of Industrial Technologies to promote the use of energy-efficient industrial systems.
Date: May 1, 2001
Creator: unknown
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library
Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites (open access)

Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites

This report documents experiments and analyses that have been done at the Idaho National Engineering and Environmental Laboratory (INEEL) to measure the steam chemical reactivity of two types of carbon fiber composites, NS31 and NB31, proposed for use at the divertor strike points in an ITER-like tokamak. These materials are 3D CFCs constituted by a NOVOLTEX preform and densified by pyrocarbon infiltration and heat treatment. NS31 differs from NB31 in that the final infiltration was done with liquid silicon to reduce the porosity and enhance the thermal conductivity of the CFC. Our approach in this work was twofold: (1) physical characterization measurements of the specimens and (2) measurements of the chemical reactivity of specimens exposed to steam.
Date: May 1, 2001
Creator: Anderl, Robert Andrew; Pawelko, Robert James & Smolik, Galen Richard
Object Type: Report
System: The UNT Digital Library
A Vortex Contactor for Carbon Dioxide Separations (open access)

A Vortex Contactor for Carbon Dioxide Separations

Many analysts identify carbon dioxide (CO2) capture and separation as a major roadblock in efforts to cost effectively mitigate greenhouse gas emissions via sequestration. An assessment 4 conducted by the International Energy Agency (IEA) Greenhouse Gas Research and Development Programme cited separation costs from $35 to $264 per tonne of CO2 avoided for a conventional coal fired power plant utilizing existing capture technologies. Because these costs equate to a greater than 40% increase in current power generation rates, it appears obvious that a significant improvement in CO2 separation technology is required if a negative impact on the world economy is to be avoided.
Date: May 1, 2001
Creator: Raterman, Kevin Thomas; Mc Kellar, Michael George; Turner, Terry Donald; Podgorney, Anna Kristine; Stacey, Douglas Edwin; Stokes, B. et al.
Object Type: Article
System: The UNT Digital Library
Requirements Analysis in the Value Methodology (open access)

Requirements Analysis in the Value Methodology

The Value Methodology (VM) study brings together a multidisciplinary team of people who own the problem and have the expertise to identify and solve it. With the varied backgrounds and experiences the team brings to the study, come different perspectives on the problem and the requirements of the project. A requirements analysis step can be added to the Information and Function Analysis Phases of a VM study to validate whether the functions being performed are required, either regulatory or customer prescribed. This paper will provide insight to the level of rigor applied to a requirements analysis step and give some examples of tools and techniques utilized to ease the management of the requirements and functions those requirements support for highly complex problems.
Date: May 1, 2001
Creator: Conner, Alison Marie
Object Type: Article
System: The UNT Digital Library
Midwest Transmission Workshop I Summary (open access)

Midwest Transmission Workshop I Summary

OAK-B135 The meeting was opened with a review of the purposes of the workshop: (1) Present and discuss key studies and assessments of transmission upgrades, additions and related issues for the upper Midwest, including work that addresses the full range of views on these topics; (2) Understand the various transmission issues in the upper Midwest and discuss options for addressing the issues; and (3) Identify the decision makers and entities that need to play an active role if transmission issues are to be resolved, and agree on next steps for engaging these individuals and organizations through education, outreach, and information dissemination.
Date: May 1, 2001
Creator: Bryan, Kevin
Object Type: Report
System: The UNT Digital Library
Fast methods for static Hamilton-Jacobi Partial Differential Equations (open access)

Fast methods for static Hamilton-Jacobi Partial Differential Equations

The authors develop a family of fast methods approximating the solution to a wide class of static Hamilton-Jacobi partial differential equations. These partial differential equations are considered in the context of control-theoretic and front-propagation problems. In general, to produce a numerical solution to such a problem, one has to solve a large system of coupled non-linear discretized equations. The techniques use partial information about the characteristic directions to de-couple the system. Previously known fast methods, available for isotropic problems, are discussed in detail. They introduce a family of new Ordered Upwinding Methods (OUM) for general (anisotropic) problems and prove convergence to the viscosity solution of the corresponding Hamilton-Jacobi partial differential equation. The hybrid methods introduced here are based on the analysis of the role played by anisotropy in the context of front propagation and optimal trajectory problems. The performance of the methods is analyzed and compared to that of several other numerical approaches to these problems. Computational experiments are performed using test problems from control theory, computational geometry and seismology.
Date: May 1, 2001
Creator: Vladimirsky, Alexander Boris
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Application of Chemically Accelerated Biotreatment to Reduce Risk in Oil-Impacted Soils Semi-Annual Report: November 2000-April 2001 (open access)

Application of Chemically Accelerated Biotreatment to Reduce Risk in Oil-Impacted Soils Semi-Annual Report: November 2000-April 2001

The overall program objective is to develop and evaluate integrated biological/physical/chemical co-treatment strategies for the remediation of wastes associated with the exploration and production of fossil energy. The specific objectives of this project are: chemical accelerated biotreatment (CAB) technology development for enhanced site remediation, application of the risk based analyses to define and support the rationale for environmental acceptable endpoints (EAE) for exploration and production wastes, and evaluate both the technological technologies in conjugation for effective remediation of hydrocarbon contaminated soils from E&P sites in the USA.
Date: May 1, 2001
Creator: Paterek, J. R.; Bogan, W. W.; Lahner, L. M.; Trbovic, V. & Korach, E.
Object Type: Report
System: The UNT Digital Library
A physically-based abrasive wear model for composite materials (open access)

A physically-based abrasive wear model for composite materials

A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.
Date: May 1, 2001
Creator: Lee, Gun Y.; Dharan, C. K. H. & Ritchie, Robert O.
Object Type: Article
System: The UNT Digital Library
Proceedings of National Avian-Wind Power Planning Meeting IV (open access)

Proceedings of National Avian-Wind Power Planning Meeting IV

OAK-B135 The purpose of the fourth meeting was to (1) share research and update research conducted on avian wind interactions (2) identify questions and issues related to the research results, (3) develop conclusions about some avian/wind power issues, and (4) identify questions and issues for future avian research.
Date: May 1, 2001
Creator: Subcommittee, NWCC Avian
Object Type: Article
System: The UNT Digital Library
Research on electric utility regulatory and policy matters relating to state and federal jurisdiction. Final report for period September 1, 1994 - February 28, 2001 (open access)

Research on electric utility regulatory and policy matters relating to state and federal jurisdiction. Final report for period September 1, 1994 - February 28, 2001

The projects funded by the above referenced grant, are based on the October 1992 proposal to the FERC, which outlined the need for closer dialogue between Federal and State energy officials. The project is designed to assist State commissioners in responding to outreach initiatives that were already forthcoming from the FERC and to further develop and refine proposals that were still outstanding.
Date: May 1, 2001
Creator: Spahn, Andrew & Dwyer, Alix
Object Type: Report
System: The UNT Digital Library
Assessment of the Fusion Energy Sciences Program. Final Report (open access)

Assessment of the Fusion Energy Sciences Program. Final Report

An assessment of the Office of Fusion Energy Sciences (OFES) program with guidance for future program strategy. The overall objective of this study is to prepare an independent assessment of the scientific quality of the Office of Fusion Energy Sciences program at the Department of Energy. The Fusion Science Assessment Committee (FuSAC) has been appointed to conduct this study.
Date: May 1, 2001
Creator: unknown
Object Type: Report
System: The UNT Digital Library
The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique (open access)

The Development of Layered Photonic Band Gap Structures Using a Micro-Transfer Molding Technique

Photonic band gap (PBG) crystals are periodic dielectric structures that manipulate electromagnetic radiation in a manner similar to semiconductor devices manipulating electrons. Whereas a semiconductor material exhibits an electronic band gap in which electrons cannot exist, similarly, a photonic crystal containing a photonic band gap does not allow the propagation of specific frequencies of electromagnetic radiation. This phenomenon results from the destructive Bragg diffraction interference that a wave propagating at a specific frequency will experience because of the periodic change in dielectric permitivity. This gives rise to a variety of optical applications for improving the efficiency and effectiveness of opto-electronic devices. These applications are reviewed later. Several methods are currently used to fabricate photonic crystals, which are also discussed in detail. This research involves a layer-by-layer micro-transfer molding ({mu}TM) and stacking method to create three-dimensional FCC structures of epoxy or titania. The structures, once reduced significantly in size can be infiltrated with an organic gain media and stacked on a semiconductor to improve the efficiency of an electronically pumped light-emitting diode. Photonic band gap structures have been proven to effectively create a band gap for certain frequencies of electro-magnetic radiation in the microwave and near-infrared ranges. The objective of this …
Date: May 1, 2001
Creator: Sutherland, Kevin Jerome
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214 (open access)

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

Thermodynamics has been studied systematically for the high temperature cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4-{delta}}, La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H{parallel}c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T{sub c}, magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T{sub c0} vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La{sub 2-x}Sr{sub x}CuO{sub 4} (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T{sub c}. …
Date: May 1, 2001
Creator: Huh, Yung Moo
Object Type: Thesis or Dissertation
System: The UNT Digital Library