0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1-eV)/GaInAs(0.7-eV) Four-Junction Solar Cell: Preprint (open access)

0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1-eV)/GaInAs(0.7-eV) Four-Junction Solar Cell: Preprint

We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga0.5In0.5P/GaAs/Ga0.75In0.25As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga0.75In0.25As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap GaxIn1-xAs fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the GaxIn1-xAs fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.
Date: May 1, 2006
Creator: Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W. & Kurtz, S. R.
Object Type: Article
System: The UNT Digital Library
100 Area and 300 Area Component of the RCBRA Fall 2005 Data Compilation (open access)

100 Area and 300 Area Component of the RCBRA Fall 2005 Data Compilation

The purpose of this report is to provide a brief description of the sampling approaches, a description of the samples collected, and the results for the Fall 2005 sampling event. This report presents the methods and results of the work to support the 100 Area and 300 Area Component of the River Corridor Baseline Risk Assessment.
Date: May 30, 2006
Creator: Queen, J.M.
Object Type: Report
System: The UNT Digital Library
2010 Census: Census Bureau Generally Follows Selected Leading Acquisition Planning Practices, but Continued Management Attention Is Needed to Help Ensure Success (open access)

2010 Census: Census Bureau Generally Follows Selected Leading Acquisition Planning Practices, but Continued Management Attention Is Needed to Help Ensure Success

A letter report issued by the Government Accountability Office with an abstract that begins "For the 2010 Census, the U.S. Census Bureau (Bureau) is making the most extensive use of contractors in its history to supply a number of mission-critical functions and technologies. Because of the critical role that contractors will play in the 2010 Census, GAO reviewed the Bureau's acquisition planning process. Specifically GAO's objectives were to (1) determine the status of the Bureau's major decennial contracts, and (2) evaluate the extent to which the Bureau is using selected leading practices to manage its acquisition planning for these contracts."
Date: May 18, 2006
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
21st Century Locomotive Technology: Quarterly Technical Status Report 13 DOE/AL68284-TSR13 (open access)

21st Century Locomotive Technology: Quarterly Technical Status Report 13 DOE/AL68284-TSR13

Upgrades and calibrations were performed on the single cylinder engine. Production of a baseline engine performance dataset has started using GE Evolution engine hardware, including the production unit pump fuel system. Long-term tests of battery cells energized at room temperature were performed. Hybrid energy storage capabilities were added to the fuel optimizer.
Date: May 9, 2006
Creator: Salasoo, Lembit & Topinka, Jennifer
Object Type: Report
System: The UNT Digital Library
S. 2557, “Oil and Gas Industry Antitrust Act of 2006”: Brief Legal Analysis (open access)

S. 2557, “Oil and Gas Industry Antitrust Act of 2006”: Brief Legal Analysis

This report analyzes ways to improve antitrust laws through S.557. These include, but are not limited to: mitigating regional shortages of oil petroleum and natural gas products, creating a federal task force to analyze information-sharing in the industry, and make U.S. antitrust laws applicable to the Organization of Petroleum Exporting Countries (OPEC).
Date: May 12, 2006
Creator: Rubin, Janice E.
Object Type: Report
System: The UNT Digital Library
30th Actinide Separations Conference, PNNL-SA-50126 (open access)

30th Actinide Separations Conference, PNNL-SA-50126

Program booklet for the 30th Actinide Separations Conference. Contains agenda and abstracts for 27 poster and 38 oral presentations to be made during the 3-day meeting, May 23-25, 2006.
Date: May 25, 2006
Creator: Delegard, Calvin H.
Object Type: Article
System: The UNT Digital Library
An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry (open access)

An Ab Initio Approach Towards Engineering Fischer-Tropsch Surface Chemistry

One of the greatest societal challenges over the next decade is the production of cheap, renewable energy for the 10 billion people that inhabit the earth. This will require the development of various different energy sources potentially including fuels derived from methane, coal, and biomass and alternatives sources such as solar, wind and nuclear energy. One approach will be to synthesize gasoline and other fuels from simpler hydrocarbons such as CO derived from methane or other U.S. based sources such as coal. Syngas (CO and H{sub 2}) can be readily converted into higher molecular weight hydrocarbons through Fischer-Tropsch synthesis. Fischer-Tropsch synthesis involves the initiation or activation of CO and H{sub 2} bonds, the subsequent propagation steps including hydrogenation and carbon-carbon coupling, followed by chain termination reactions. Commercially viable catalysts include supported Co and Co-alloys. Over the first two years of this project we have used ab initio methods to determine the adsorption energies for all reactants, intermediates, and products along with the overall reaction energies and their corresponding activation barriers over the Co(0001) surface. Over the third year of the project we developed and advanced an ab initio-based kinetic Monte Carlo simulation code to simulate Fischer Tropsch synthesis. This report …
Date: May 7, 2006
Creator: Neurock, Matthew & Walthall, David A.
Object Type: Report
System: The UNT Digital Library
Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam (open access)

Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam

Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron cloud density during the beam pulse.
Date: May 18, 2006
Creator: Covo, M K; Molvik, A W; Friedman, A; Vay, J; Seidl, P A; Logan, B G et al.
Object Type: Article
System: The UNT Digital Library
An AC dipole for the Tevatron - Initial tests (open access)

An AC dipole for the Tevatron - Initial tests

None
Date: May 1, 2006
Creator: Miyamoto, Ryoichi; Kopp, Sacha; Jansson, Andreas & Syphers, Mike
Object Type: Article
System: The UNT Digital Library
AC Transit Demos Three Prototype Fuel Cell Buses (open access)

AC Transit Demos Three Prototype Fuel Cell Buses

Fact sheet describes the study being conducted on fuel cell buses at AC Transit.
Date: May 1, 2006
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Accurate Method for Forward and Reverse Bias Curve Fitting of TPV I-V Data (open access)

Accurate Method for Forward and Reverse Bias Curve Fitting of TPV I-V Data

None
Date: May 11, 2006
Creator: Danielson, L. & Depoy, D.
Object Type: Report
System: The UNT Digital Library
Accurate phylogenetic classification of DNA fragments based onsequence composition (open access)

Accurate phylogenetic classification of DNA fragments based onsequence composition

Metagenome studies have retrieved vast amounts of sequenceout of a variety of environments, leading to novel discoveries and greatinsights into the uncultured microbial world. Except for very simplecommunities, diversity makes sequence assembly and analysis a verychallenging problem. To understand the structure a 5 nd function ofmicrobial communities, a taxonomic characterization of the obtainedsequence fragments is highly desirable, yet currently limited mostly tothose sequences that contain phylogenetic marker genes. We show that forclades at the rank of domain down to genus, sequence composition allowsthe very accurate phylogenetic 10 characterization of genomic sequence.We developed a composition-based classifier, PhyloPythia, for de novophylogenetic sequence characterization and have trained it on adata setof 340 genomes. By extensive evaluation experiments we show that themethodis accurate across all taxonomic ranks considered, even forsequences that originate fromnovel organisms and are as short as 1kb.Application to two metagenome datasets 15 obtained from samples ofphosphorus-removing sludge showed that the method allows the accurateclassification at genus level of most sequence fragments from thedominant populations, while at the same time correctly characterizingeven larger parts of the samples at higher taxonomic levels.
Date: May 1, 2006
Creator: McHardy, Alice C.; Garcia Martin, Hector; Tsirigos, Aristotelis; Hugenholtz, Philip & Rigoutsos, Isidore
Object Type: Article
System: The UNT Digital Library

Adhesion and Thin-Film Module Reliability

None
Date: May 1, 2006
Creator: McMahon, T. J. & Jorgensen, G. J.
Object Type: Presentation
System: The UNT Digital Library
Adhesion and Thin-Film Module Reliability: Preprint (open access)

Adhesion and Thin-Film Module Reliability: Preprint

Among the infrequently measured but essential properties for thin-film (T-F) module reliability are the interlayer adhesion and cohesion within a layer. These can be cell contact layers to glass, contact layers to the semiconductor, encapsulant to cell, glass, or backsheet, etc. We use an Instron mechanical testing unit to measure peel strengths at 90{sup o} or 180{sup o} and, in some cases, a scratch and tape pull test to evaluate inter-cell layer adhesion strengths. We present peel strength data for test specimens laminated from the three T-F technologies, before and after damp heat, and in one instance at elevated temperatures. On laminated T-F cell samples, failure can occur uniformly at any one of the many interfaces, or non-uniformly across the peel area at more than one interface. Some peel strengths are << 1 N/mm. This is far below the normal Instron mechanical testing unit Instron mechanical testing unit; glass interface values of >10 N/mm. We measure a wide range of adhesion strengths and suggest that adhesion measured under higher temperature and relative humidity conditions is more relevant for module reliability.
Date: May 1, 2006
Creator: McMahon, T. J. & Jorgensen, G. J.
Object Type: Article
System: The UNT Digital Library
Advanced CIDI Emission Control System Development (open access)

Advanced CIDI Emission Control System Development

Ford Motor Company, with ExxonMobil and FEV, participated in the Department of Energy's (DOE) Ultra-Clean Transportation Fuels Program with the goal to develop an innovative emission control system for light-duty diesel vehicles. The focus on diesel engine emissions was a direct result of the improved volumetric fuel economy (up to 50%) and lower CO2 emissions (up to 25%) over comparable gasoline engines shown in Europe. Selective Catalytic Reduction (SCR) with aqueous urea as the NOx reductant and a Catalyzed Diesel Particulate Filter (CDPF) were chosen as the primary emission control system components. The program expected to demonstrate more than 90% durable reduction in particulate matter (PM) and NOx emissions on a light-duty truck application, based on the FTP-75 drive cycle. Very low sulfur diesel fuel (<15 ppm-wt) enabled lower PM emissions, reduced fuel economy penalty due to the emission control system and improved long-term system durability. Significant progress was made toward a durable system to meet Tier 2 Bin 5 emission standards on a 6000 lbs light-duty truck. A 40% reduction in engine-out NOx emissions was achieved with a mid-size prototype diesel engine through engine recalibration and increased exhaust gas recirculation. Use of a rapid warm-up strategy and urea SCR …
Date: May 31, 2006
Creator: Lambert, Christine
Object Type: Report
System: The UNT Digital Library

Advanced Fuel Cell Membranes Based on Heteropolyacids

Develop the methodology for the fabrication of 3D cross-linked, hydrocarbon-based membranes using immobilized heteropolyacids (HPAs) as the proton conducting moiety.
Date: May 18, 2006
Creator: Turner, J. A.; Pern, F. F. J.; Herring, A. M. & Dec, S. F.
Object Type: Presentation
System: The UNT Digital Library
Advanced Wind Turbine Program Next Generation Turbine Development Project: June 17, 1997--April 30, 2005 (open access)

Advanced Wind Turbine Program Next Generation Turbine Development Project: June 17, 1997--April 30, 2005

This document reports the technical results of the Next Generation Turbine Development Project conducted by GE Wind Energy LLC. This project is jointly funded by GE and the U.S. Department of Energy's National Renewable Energy Laboratory.The goal of this project is for DOE to assist the U.S. wind industry in exploring new concepts and applications of cutting-edge technology in pursuit of the specific objective of developing a wind turbine that can generate electricity at a levelized cost of energy of $0.025/kWh at sites with an average wind speed of 15 mph (at 10 m height).
Date: May 1, 2006
Creator: GE Wind Energy, LLC
Object Type: Report
System: The UNT Digital Library
Afghanistan: Elections, Constitution, and Government (open access)

Afghanistan: Elections, Constitution, and Government

In 2004 and 2005, Afghanistan adopted a permanent constitution and elected a president and a parliament. The parliament is emerging as a significant force in Afghan politics, as shown in debates over a new cabinet and the 2006 budget. See CRS Report RL30588, Afghanistan: Post-War Governance, Security, and U.S. Policy, by Kenneth Katzman.
Date: May 25, 2006
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Afghanistan: Elections, Constitution, and Government (open access)

Afghanistan: Elections, Constitution, and Government

In 2004 and 2005, Afghanistan adopted a permanent constitution and elected a president and a parliament. The parliament is emerging as a significant force in Afghan politics, as shown in debate over a new cabinet proposed in March 2006. However, insurgent violence continues to threaten Afghan stability. See CRS Report RL30588, Afghanistan: Post-War Governance, Security, and U.S. Policy, by Kenneth Katzman.
Date: May 1, 2006
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Afghanistan: Post-War Governance, Security, and U.S. Policy (open access)

Afghanistan: Post-War Governance, Security, and U.S. Policy

Afghanistan's planned political transition was completed with the convening of a parliament in December 2005, but insurgent threats to Afghanistan's government persist and are even growing in some southern provinces. A new constitution was adopted in January 2004, and successful presidential elections were held on October 9, 2004, followed by parliamentary elections on September 18, 2005. Afghan citizens are enjoying new personal freedoms that were forbidden under the Taliban. Women are participating in economic and political life; however, the insurgency led by remnants of the former Taliban regime has conducted numerous lethal attacks since mid-2005, narcotics trafficking is rampant, and independent militias remain through the country. U.S. stabilization measures focus on strengthening the central government and its security forces while combating insurgents.
Date: May 4, 2006
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Afghanistan: Post-War Governance, Security, and U.S. Policy (open access)

Afghanistan: Post-War Governance, Security, and U.S. Policy

The United States and its allies are helping Afghanistan emerging from more than 22 years of warfare, although substantial risk to Afghan stability remains. Before the U.S. military campaign against the orthodox Islamist Taliban movement began on October 7, 2001, Afghanistan had been mired in conflict since the Soviet invasion of Afghanistan in 1979. The defeat of the Taliban has enabled the United States and its coalition partners to send forces throughout Afghanistan to search for Taliban and Al Qaeda fighters and leaders that remain at large, including Osama bin Laden. As the war against remaining Al Qaeda and Taliban elements winds down, the United States is shifting its military focus toward stabilizing the interim government, including training a new Afghan national army, and supporting the international security force (ISAF) that is helping the new government provide security.
Date: May 4, 2006
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Afghanistan: Post-War Governance, Security, and U.S. Policy (open access)

Afghanistan: Post-War Governance, Security, and U.S. Policy

The United States and its allies are helping Afghanistan emerging from more than 22 years of warfare, although substantial risk to Afghan stability remains. Before the U.S. military campaign against the orthodox Islamist Taliban movement began on October 7, 2001, Afghanistan had been mired in conflict since the Soviet invasion of Afghanistan in 1979. The defeat of the Taliban has enabled the United States and its coalition partners to send forces throughout Afghanistan to search for Taliban and Al Qaeda fighters and leaders that remain at large, including Osama bin Laden. As the war against remaining Al Qaeda and Taliban elements winds down, the United States is shifting its military focus toward stabilizing the interim government, including training a new Afghan national army, and supporting the international security force (ISAF) that is helping the new government provide security.
Date: May 4, 2006
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
AGC-1 Irradiation Experiment Test Plan (open access)

AGC-1 Irradiation Experiment Test Plan

The Advanced Graphite Capsule (AGC) irradiation test program supports the acquisition of irradiated graphite performance data to assist in the selection of the technology to be used for the VHTR. Six irradiations are planned to investigate compressive creep in graphite subjected to a neutron field and obtain irradiated mechanical properties of vibrationally molded, extruded, and iso-molded graphites for comparison. The experiments will be conducted at three temperatures: 600, 900, and 1200°C. At each temperature, two different capsules will be irradiated to different fluence levels, the first from 0.5 to 4 dpa and the second from 4 to 7 dpa. AGC-1 is the first of the six capsules designed for ATR and will focus on the prismatic fluence range.
Date: May 1, 2006
Creator: Bratton, R. L.
Object Type: Report
System: The UNT Digital Library
Agricultural Disaster Assistance (open access)

Agricultural Disaster Assistance

The U.S. Department of Agriculture (USDA) offers several permanently authorized programs to help farmers recover financially from a natural disaster, including federal crop insurance, the noninsured assistance program, and emergency disaster loans. Since 1988, Congress regularly has made supplemental financial assistance available to farmers and ranchers, primarily in the form of crop disaster payments and emergency livestock assistance. The Senate-passed version of a pending FY2006 supplemental appropriations bill (H.R. 4939) contains an adopted committee amendment that would provide an estimated additional $3.9 billion in various forms of farm assistance, including payments for major crop and livestock losses caused by any 2005 disaster, such as the drought in portions of the Midwest and Hurricanes Katrina and Rita in the Gulf.
Date: May 8, 2006
Creator: Chite, Ralph M.
Object Type: Report
System: The UNT Digital Library