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3-D Experimental Fracture Analysis at High Temperature (open access)

3-D Experimental Fracture Analysis at High Temperature

T*e, which is an elastic-plastic fracture parameter based on incremental theory of plasticity, was determined numerically and experimentally. The T*e integral of a tunneling crack in 2024-T3 aluminum, three point bend specimen was obtained through a hybrid analysis of moire interferometry and 3-D elastic-plastic finite element analysis. The results were verified by the good agreement between the experimentally and numerically determined T*e on the specimen surface.
Date: September 14, 2001
Creator: Jackson, John H. & Kobayashi, Albert S.
Object Type: Report
System: The UNT Digital Library
Accidental Contamination of Samples Used in Canadian Lynx Study Rendered the Study's Preliminary Conclusion Invalid (open access)

Accidental Contamination of Samples Used in Canadian Lynx Study Rendered the Study's Preliminary Conclusion Invalid

Correspondence issued by the General Accounting Office with an abstract that begins "This report discusses the validity of the results of a 1998 study of the Canadian lynx. The Forest Service contracted with Dr. John Weaver of the Wildlife Conservation Society in New York City to help survey the Canadian lynx in the Cascade Mountains of Washington and Oregon. In a March 1999 interim report, Dr. Weaver concluded that the Canadian lynx lives in some forests in Washington and Oregon. In March 2000, the Fish and Wildlife Service placed the lynx on its list of threatened species in the forested portions of 13 states, including Washington and Oregon. Issues have since been raised about whether the study's results were falsified. GAO found no evidence that the study was deliberately falsified."
Date: August 14, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Accuracy and reliability of China's energy statistics (open access)

Accuracy and reliability of China's energy statistics

Many observers have raised doubts about the accuracy and reliability of China's energy statistics, which show an unprecedented decline in recent years, while reported economic growth has remained strong. This paper explores the internal consistency of China's energy statistics from 1990 to 2000, coverage and reporting issues, and the state of the statistical reporting system. Available information suggests that, while energy statistics were probably relatively good in the early 1990s, their quality has declined since the mid-1990s. China's energy statistics should be treated as a starting point for analysis, and explicit judgments regarding ranges of uncertainty should accompany any conclusions.
Date: September 14, 2001
Creator: Sinton, Jonathan E.
Object Type: Article
System: The UNT Digital Library
Addendum to the 200 West Area Dust Mitigation Strategies: Treatment of the Dust Source Area (open access)

Addendum to the 200 West Area Dust Mitigation Strategies: Treatment of the Dust Source Area

This document describes the source area for the blowing dust encountered in the southwest portion of the 200 West Area. Strategies for short-term stabilization of the entire source area, short-term stabilization of a portion of the source area based on levels of respirable dust, and long-term stabilization of the entire source area are provided. An separate evaluation of aerosolized water as a means of reducing airborne dust is also provided.
Date: May 14, 2001
Creator: Becker, James M. & Sackschewsky, Michael R.
Object Type: Report
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.
Object Type: Article
System: The UNT Digital Library
Advanced High Resolution Seismic Imaging, Material Properties Estimation and Full Wavefield Inversion for the Shallow Subsurface (open access)

Advanced High Resolution Seismic Imaging, Material Properties Estimation and Full Wavefield Inversion for the Shallow Subsurface

Develop and test advanced near vertical to wide-angle seismic methods for structural imaging and material properties estimation of the shallow subsurface for environmental characterization efforts.
Date: June 14, 2001
Creator: Levander, A.; Zelt, C. A. & Symes, W. W.
Object Type: Report
System: The UNT Digital Library
Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Two-Year Results with Third-Generation Blowing Agents (open access)

Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Two-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 {minus}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 two years of a multi-year aging study. Preliminary comparisons of measured data with predictions of a mathematical aging model are presented.
Date: February 14, 2001
Creator: Wilkes, K. E.
Object Type: Article
System: The UNT Digital Library
AIDS in Africa (open access)

AIDS in Africa

Sub-Saharan Africa has been far more severely affected by AIDS than any other part of the world. The United Nations reports that 25.3 million adults and children are infected with the HIV virus in the region, which has about 10% of the world's population but more than 70% of the worldwide total of infected people. This report discusses this issue in detail, including the cause of the African AIDS epidemic, the social and economic consequences, response and treatment, and U.S. policy.
Date: May 14, 2001
Creator: Copson, Raymond W.
Object Type: Report
System: The UNT Digital Library
AIDS in Africa (open access)

AIDS in Africa

Sub-Saharan Africa has been far more severely affected by AIDS than any other part of the world. The United Nations reports that 25.3 million adults and children are infected with the HIV virus in the region, which has about 10% of the world's population but more than 70% of the worldwide total of infected people. This report discusses this issue in detail, including the cause of the African AIDS epidemic, the social and economic consequences, response and treatment, and U.S. policy.
Date: December 14, 2001
Creator: Copson, Raymond W.
Object Type: Report
System: The UNT Digital Library
Alpha-decay radiation damage study of a glass-bonded sodalite ceramic waste form. (open access)

Alpha-decay radiation damage study of a glass-bonded sodalite ceramic waste form.

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Date: December 14, 2001
Creator: Frank, S. M.; Barber, T. L.; DiSanto, T.; Goff, K. M.; Johnson, S. G.; Jue, J.-F. et al.
Object Type: Article
System: The UNT Digital Library
Alpha-null defocus: An optimum defocus condition with relevance for focal-series reconstruction (open access)

Alpha-null defocus: An optimum defocus condition with relevance for focal-series reconstruction

Two optimum defocus conditions are used in high-resolution transmission electron microscopy. Scherzer defocus produces an image of the specimen ''projected potential'' to the resolution of the microscope, and Lichte defocus minimizes dispersion. A third optimum defocus is best for focal-series reconstruction; alpha-null defocus maximizes transfer of high-frequency diffracted beam amplitudes into the microscope image. Beam transfer is confined by incident-beam convergence to a Gaussian ''packet'' of defocus values centered on the alpha-null defocus. For a diffracted beam hkl, with a spatial frequency of u, the envelope for incident beam convergence has null damping effect when defocus is set to -Cs. (wavelength.u)**2. On either side of this alpha-null defocus value, the damping effect of incident-beam convergence reduces diffracted-beam transfer. The position of alpha-null defocus for any spatial frequency depends only on the value of Cs, but defocus-packet width around the alpha-null defocus depends only on the convergence semi-angle. Under NCEM OAM (one-Angstrom microscope) conditions, a [110] diamond image with the correct 0.89A spacing appears when the Si (004) alpha-null defocus is selected. The alpha-null defocus should be included as the (furthest underfocus) limit for all high-resolution focal series reconstruction.
Date: February 14, 2001
Creator: O'Keefe, Michael A.
Object Type: Article
System: The UNT Digital Library
AMRH and High Energy Reinicke Problem (open access)

AMRH and High Energy Reinicke Problem

The authors describe AMRH results on a version of the Reinicke problem specified by the V and V group of LLNL's A-Div. The simulation models a point explosion with heat conduction. The problem specification requires that the heat conduction be replaced with diffusive radiation transport. The matter and radiation energy densities are tightly coupled.
Date: May 14, 2001
Creator: Shestakov, A I & Greenough, J A
Object Type: Report
System: The UNT Digital Library
Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS (open access)

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS

Combustion chamber deposits (CCDs) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components [1]. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recent advances in MS have opened new possibilities for analysis of CCDs. Here we report initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.
Date: June 14, 2001
Creator: Reynolds, J G; Shields, S J & Roos, J W
Object Type: Article
System: The UNT Digital Library
Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS (open access)

Analysis of Combustion Chamber Deposits by ESI-TOF-MS and MALDI-TOF-MS

Combustion chamber deposits (CCD) in internal combustion engines have been studied by various techniques to understand the relationship of performance degradation with deposit quantity and structure. XPS, XAS, NMR, and elemental analysis have offered insight into the bulk structure of C, H, N, O and metal components. MS has offered some information about compound structure, but results are limited due to the insolubility and complexity of the materials. Recently, we have reported on the metal structure by XPS and XAS of several deposits from a GM 3800 engine generated using a standard fuel and one that contains low levels of the gasoline anti-knock additive, MMT. Here we report the initial findings on the carbon structure of these deposits determined by ESI-TOF-MS and MADLI-TOF-MS.
Date: June 14, 2001
Creator: Reynolds, J G; Shields, S J & Roos, J W
Object Type: Article
System: The UNT Digital Library
Andean Regional Initiative (ARI): FY2002 Assistance for Colombia and Neighbors (open access)

Andean Regional Initiative (ARI): FY2002 Assistance for Colombia and Neighbors

This report discusses the Andean Regional Initiative (ARI), implemented by the Bush Administration in 2001 to provide economic and counter-narcotics assistance for Colombia and regional neighbors. The report discusses the goals of the ARI, as well as related appropriations.
Date: December 14, 2001
Creator: Storrs, K. Larry & Serafino, Nina M.
Object Type: Report
System: The UNT Digital Library
Applying Agreed-Upon Procedures: House Interparliamentary Groups (open access)

Applying Agreed-Upon Procedures: House Interparliamentary Groups

Correspondence issued by the General Accounting Office with an abstract that begins "To assist the Committee on International Relations evaluate the extent to which five House Interparliamentary Groups' schedules of receipts, disbursements, and fund balance for 2000 and 1999 appropriately reflected the cash receipts and disbursements and fund balance for those years, GAO reviewed documentation supporting each group's recorded receipt and disbursement transactions and related fund balances for evidence that the transactions were properly authorized and recorded. The schedules, prepared by the treasurer of each group, present for 2000 and 1999 the opening fund balance, total receipts, and disbursements by category, and ending fund balance, on a cash basis, for each of the five groups. GAO also recalculated and compared the recalculated amounts to the reported amounts in each group's 2000 and 1999 schedule."
Date: August 14, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Atomic Scale Structure of Ultrathin Magnetic Multilayers and Correlation with Resistance and Giant Magnetoresistance and Spin-Dependent Tunneling (open access)

Atomic Scale Structure of Ultrathin Magnetic Multilayers and Correlation with Resistance and Giant Magnetoresistance and Spin-Dependent Tunneling

ORNL's advanced characterization capabilities were used to determine the physical and chemical structure of magnetic multilayer films intended for application in non-volatile magnetic random access memory devices and as magnetic sensors. ORNL modeling capabilities were used to incorporate this information into a first-principles based tool that can be used to model the magnetic and transport properties of these films. This modeling capability should be useful for understanding and optimizing novel magnetoelectronic devices.
Date: February 14, 2001
Creator: Butler, W. H.
Object Type: Report
System: The UNT Digital Library
Attention Disorder Drugs: Few Incidents of Diversion or Abuse Identified By Schools (open access)

Attention Disorder Drugs: Few Incidents of Diversion or Abuse Identified By Schools

A letter report issued by the General Accounting Office with an abstract that begins "Children diagnosed with attention deficit disorders are often treated with stimulant medications, such as Ritalin or Adderall. These drugs are controlled substances under federal law because of their high potential for abuse. Many of these stimulant drugs must be taken several times a day to be effective, so children need medication during the school day. Concern has arisen that the increasing use of these medications in school might provide additional opportunities for drug abuse. No data exists on the extent to which attention disorder drugs have been diverted or abused at school, or the extent to which state laws or regulations guide local school officials in safely administering these drugs. Middle and high school principals reported little diversion or abuse of attention disorder drugs. For the first seven to nine months of school year 2000-2001, about eight percent of principals in public middle and high schools reported that attention disorder drugs had been diverted or abused at their school. Most of the principals reported that school officials administer attention disorder medications, with about two percent of the school's students on average being administered attention disorder drugs …
Date: September 14, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Aviation Competition: Regional Jet Service Yet to Reach Many Small Communities (open access)

Aviation Competition: Regional Jet Service Yet to Reach Many Small Communities

A letter report issued by the General Accounting Office with an abstract that begins "The increasing numbers of regional jets (RJ) in operation have provided U.S. air carriers with opportunities to serve new and existing markets. With predominantly 50-seat aircraft, the carriers have initiated service to many large and medium-large communities but have provided less service to smaller communities. Service to small communities--to which the airlines now mostly operate turboprop aircraft--continues to be an important concern, because of the uncertainty about whether those markets may generate enough passenger traffic and revenue to be financially viable to sustain RJ operations. Eventually, smaller RJs may let carriers serve those smaller communities economically. Other questions also emerge about the impact of how the carriers will use their RJs. For example, the airlines could restrict capacity in a market by reducing service with larger mainline jets but increasing the number of RJ flights in a way that may inhibit entry by new competitors, allowing the airlines to charge fares higher than might exist in a more competitive market. Additionally, the growth in RJs has clearly contributed to an increasing problem with congestion, particularly in some locations like New York's LaGuardia Airport. But how the …
Date: February 14, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Aviation Safety: FAA and DOD Response to Similar Safety Concerns (open access)

Aviation Safety: FAA and DOD Response to Similar Safety Concerns

A letter report issued by the General Accounting Office with an abstract that begins "The informal and formal networks used by the Federal Aviation Administration (FAA) and the military services to exchange critical aviation safety information have proven useful. However, because recent and expected retirements threaten to erode informal networks, additional formal channels of communication are needed to ensure that common safety risks are identified and addressed in a systematic and timely manner. This includes the exchange of information on how FAA and the military services have addressed particular aviation safety concerns. Existing gaps in the formal processes used by FAA and the military services to exchange information could allow for communication lapses and delays in getting critical safety information to the right parties in a timely manner, potentially resulting in the loss of lives and aircraft."
Date: December 14, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Bilingual Education: Four Overlapping Programs Could Be Consolidated (open access)

Bilingual Education: Four Overlapping Programs Could Be Consolidated

A letter report issued by the General Accounting Office with an abstract that begins "In fiscal year 2000, the federal government funded four bilingual education programs--Program Development and Implementation Grants, Program Enhancement Projects, Comprehensive School Grants, and Systemwide Improvement Grants--that award grants to school districts to serve children with limited English proficiency. This report reviews (1) how similar the performance goals and measures, eligibility criteria, and allowable services are among the four bilingual education programs; (2) to what extent the different kinds of grants were made to the same types of schools or school districts and were used to provide the same services; (3) what is known about these programs' effectiveness; and (4) whether these programs can be better coordinated or if opportunities exist for program coordination and cost savings. GAO found that all four federal bilingual education programs share the same performance goals and measures, use similar eligibility criteria, and allow for similar uses of program funds. In fiscal year 2000, the four bilingual programs made grants to school districts that shared some characteristics and provided similar services; however, individual schools typically did not receive funding from more than one program. The services provided with program funds are similar, …
Date: May 14, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Burundi: The Peace Process and U.S. Policy (open access)

Burundi: The Peace Process and U.S. Policy

This report is about Burundi, specifically the peace process and U.S. policy
Date: May 14, 2001
Creator: Dagne, Ted
Object Type: Report
System: The UNT Digital Library
Caribbean Basin Interim Trade Program: CBI/NAFTA Parity (open access)

Caribbean Basin Interim Trade Program: CBI/NAFTA Parity

The entry into force, on January 1, 1994, of the North American Free Trade Agreement (NAFTA) has eliminated the advantage that the beneficiaries of the Caribbean Basin Economic Recovery Act (CBERA) and related provisions of the Caribbean Basin Initiative (CBI) had enjoyed in trade with the United States relative to Mexico, and gave Mexico an increasingly significant competitive edge over the CBERA countries. The scheduled further implementation of the NAFTA would have resulted in a substantial advantage to Mexico over the CBERA countries and vitiate in part the purpose of the CBERA.
Date: November 14, 2001
Creator: Pregelj, Vladimir N.
Object Type: Report
System: The UNT Digital Library
A Cartesian grid embedded boundary method for the heat equation on irregular domains (open access)

A Cartesian grid embedded boundary method for the heat equation on irregular domains

We present an algorithm for solving the heat equation on irregular time-dependent domains. It is based on the Cartesian grid embedded boundary algorithm of Johansen and Colella (J. Comput. Phys. 147(2):60--85) for discretizing Poisson's equation, combined with a second-order accurate discretization of the time derivative. This leads to a method that is second-order accurate in space and time. For the case where the boundary is moving, we convert the moving-boundary problem to a sequence of fixed-boundary problems, combined with an extrapolation procedure to initialize values that are uncovered as the boundary moves. We find that, in the moving boundary case, the use of Crank--Nicolson time discretization is unstable, requiring us to use the L{sub 0}-stable implicit Runge--Kutta method of Twizell, Gumel, and Arigu.
Date: March 14, 2001
Creator: McCorquodale, Peter; Colella, Phillip & Johansen, Hans
Object Type: Article
System: The UNT Digital Library