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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
1-MeV-Electron Irradiation of GaInAsN Cells: Preprint (open access)

1-MeV-Electron Irradiation of GaInAsN Cells: Preprint

This conference paper describes the GaInAsN cells that are measured to retain 933% and 894% of their original efficiency after exposure to 5 X 1014 and 1 X 1015 cm-2 1-MeV electrons, respectively. The rate of degradation is not correlated with the performance at beginning of life (BOL). The depletion width remains essentially unchanged, increasing by< 1%. Temperature-coefficient data for GaInAsN cells are also presented. These numbers are used to project the efficiency of GaInAsN-containing multijunction cells. The GaInAsN junction is not currently predicted to increase the efficiencies of the multijunction cells. Nevertheless, GaInAsN-containing multijunction cell efficiencies are predicted to be comparable to those of the conventional structures, and even small improvements in the GaInAsN cell may lead to higher multijunction cell efficiencies, especially for high-radiation applications and when cell operating temperature is low.
Date: May 1, 2002
Creator: Kurtz, Sarah; King, R. R.; Edmondson, K. M.; Friedman, D. J. & Karam, N. H.
Object Type: Article
System: The UNT Digital Library
8 GeV H- ions: Transport and injection (open access)

8 GeV H- ions: Transport and injection

Fermilab is working on the design of an 8 GeV superconducting RF H{sup -} linac called the Proton Driver. The energy of H{sup -} beam will be an order of magnitude higher than the existing ones. This brings up a number of technical challenges to transport and injection of H{sup -} ions. This paper will focus on the subjects of stripping losses (including stripping by blackbody radiation, field and residual gas) and carbon foil stripping efficiency, along with a brief discussion on other issues such as Stark states lifetime of hydrogen atoms, single and multiple Coulomb scattering, foil heating and stress, radiation activation, collimation and jitter correction, etc.
Date: May 1, 2005
Creator: Chou, W.; Bryant, H.; Drozhdin, A.; Hill, C.; Kostin, M.; Macek, R. et al.
Object Type: Article
System: The UNT Digital Library
20% Wind Energy - Diversifying Our Energy Portfolio and Addressing Climate Change (Brochure) (open access)

20% Wind Energy - Diversifying Our Energy Portfolio and Addressing Climate Change (Brochure)

This brochure describes the R&D efforts needed for wind energy to meet 20% of the U.S. electrical demand by 2030. In May 2008, DOE published its report, 20% Wind Energy by 2030, which presents an in-depth analysis of the potential for wind energy in the United States and outlines a potential scenario to boost wind electric generation from its current production of 16.8 gigawatts (GW) to 304 GW by 2030. According to the report, achieving 20% wind energy by 2030 could help address climate change by reducing electric sector carbon dioxide (CO2) emissions by 825 million metric tons (20% of the electric utility sector CO2 emissions if no new wind is installed by 2030), and it will enhance our nation's energy security by diversifying our electricity portfolio as wind energy is an indigenous energy source with stable prices not subject to fuel volatility. According to the report, increasing our nation's wind generation could also boost local rural economies and contribute to significant growth in manufacturing and the industry supply chain. Rural economies will benefit from a substantial increase in land use payments, tax benefits and the number of well-paying jobs created by the wind energy manufacturing, construction, and maintenance industries. …
Date: May 1, 2008
Creator: unknown
Object Type: Report
System: The UNT Digital Library
53 MHz beam loading compensation for slip stacking in the Fermilab Main Injector (open access)

53 MHz beam loading compensation for slip stacking in the Fermilab Main Injector

Recently In-Phase and Quadrature (I&Q) was added to both the 53 MHz Feedback and Feedforward Beam Loading Compensation for Slip Stacking in the Fermilab Main Injector. With 53 MHz Feedback, we can now turn the 18 Radio Frequency (RF) Stations off down to below 100 V. In using I&Q on Feedforward, beam loading compensation to the beam on both the upper and lower frequencies of Slip Stacking can be applied as we slip the beam. I&Q theory will be discussed.
Date: May 1, 2005
Creator: Dey, J. & Kourbanis, I.
Object Type: Article
System: The UNT Digital Library
105-K Basin 1999 Debris Report (open access)

105-K Basin 1999 Debris Report

The purpose of this report is to describe the quantities, character, and management (e.g., segregation and management after removal) of 105-K Basins debris managed in calendar year 1999.
Date: May 1, 2000
Creator: WATSON, D.J.
Object Type: Report
System: The UNT Digital Library
A 201 MHz RF cavity design with non-stressed pre-curved Be windows for muon cooling channels (open access)

A 201 MHz RF cavity design with non-stressed pre-curved Be windows for muon cooling channels

We present a 201-MHz RF cavity design for muon cooling channels with non-stressed and pre-curved Be foils to terminate the beam apertures. The Be foils are necessary to improve the cavity shunt impedance with large beam apertures needed for accommodating large transverse size muon beams. Be is a low-Z material with good electrical and thermal properties. It presents an almost transparent window to muon beams, but terminates the RF cavity electro-magnetically. Previous designs use pre-stressed flat Be foils in order to keep cavity from detuning resulted from RF heating on the window surface. Be foils are expensive, and it is difficult to make them under desired tension. An alternative design is to use precurved and non-stressed Be foils where the buckling direction is known, and frequency shifts can be properly predicted. We will present mechanical simulations on the Be foils in this paper.
Date: May 1, 2003
Creator: Li, Derun; Ladran, A.; Staples, J.; Virostek, S.; Zisman, M.; Lau, W. et al.
Object Type: Article
System: The UNT Digital Library
15th Street News (Midwest City, Okla.), Vol. 38, No. 26, Ed. 1 Friday, May 1, 2009 (open access)

15th Street News (Midwest City, Okla.), Vol. 38, No. 26, Ed. 1 Friday, May 1, 2009

Newspaper from Rose State College in Midwest City, Oklahoma that includes national, local, and campus news along with advertising.
Date: May 1, 2009
Creator: Price, Racheal
Object Type: Newspaper
System: The Gateway to Oklahoma History
1991-2005 National Solar Radiation Database (open access)

1991-2005 National Solar Radiation Database

This fact sheet provides an overview of the purpose, benefit, and features of the newly updated National Solar Radiation Database.
Date: May 1, 2007
Creator: Wilcox, S.
Object Type: Report
System: The UNT Digital Library
2001 NSLS Activity Report (National Synchrotron Light Source). (open access)

2001 NSLS Activity Report (National Synchrotron Light Source).

This describes the advertising of cover page of 2001 NSLS Activity Report (National Synchrotron Light Source).
Date: May 1, 2002
Creator: Corwin, M. A.
Object Type: Report
System: The UNT Digital Library
2001 NSLS Activity Report (National Synchrotron Light Source) (open access)

2001 NSLS Activity Report (National Synchrotron Light Source)

The year 2001 has been another highly productive year at the NSLS, with over 2500 users, including 720 first time users, conducting nearly 1200 experiments in fields ranging from the life, materials, chemical, and environmental sciences to applied science and technology. An impressive array of highlights from this scientific activity is included in this Activity Report. They include the first demonstration of a direct structural probe of the superconducting ground state in the cuprates by utilizing anomalous soft x-ray resonance effects to selectively enhance the scattering from doped holes. Another highly significant result was the determination of the structure of the potassium channel membrane protein. This is especially significant as it provides insight into how the channel functions and how it selects a particular kind of ion. In the nanoscience area, small angle x-ray scattering measurements played an essential role in determining that preferential sequestering of tailored metal nanocrystals into a self-assembled lamellar diblock copolymer can produce high quality metallodielectric photonic bandgap structures, demonstrating the potential of these nanocomposites for photonic crystal engineering. The infrared microscopy program continued to yield noteworthy results, including an important study that characterized the types and abundances of organic materials in contaminated and uncontaminated sediments …
Date: May 1, 2002
Creator: Corwin, M. A.
Object Type: Report
System: The UNT Digital Library

2005 DOE Hydrogen Program Review: Hydrogen Codes and Standards

A PowerPoint presentation given as part of the 2005 Hydrogen Program Review, May 24, 2005, in Washington, D.C.
Date: May 1, 2005
Creator: Ohi, J.
Object Type: Presentation
System: The UNT Digital Library
2005 Research Briefs : Materials and Process Sciences Center. (open access)

2005 Research Briefs : Materials and Process Sciences Center.

This report is the latest in a continuing series that highlights the recent technical accomplishments associated with the work being performed within the Materials and Process Sciences Center. Our research and development activities primarily address the materials-engineering needs of Sandia's Nuclear-Weapons (NW) program. In addition, we have significant efforts that support programs managed by the other laboratory business units. Our wide range of activities occurs within six thematic areas: Materials Aging and Reliability, Scientifically Engineered Materials, Materials Processing, Materials Characterization, Materials for Microsystems, and Materials Modeling and Simulation. We believe these highlights collectively demonstrate the importance that a strong materials-science base has on the ultimate success of the NW program and the overall DOE technology portfolio.
Date: May 1, 2005
Creator: Cieslak, Michael J.
Object Type: Report
System: The UNT Digital Library
2005 Solar Decathlon (open access)

2005 Solar Decathlon

The 2005 Solar Decathlon Brochure is a multipurpose document that provides a broad overview of the Decathlon's background, purpose, scope, the student participants, as well as the successes from the 2002 competition and the excitement and energy surrounding the event.
Date: May 1, 2004
Creator: unknown
Object Type: Text
System: The UNT Digital Library
2006 B100 Quality Survey Results: Milestone Report (open access)

2006 B100 Quality Survey Results: Milestone Report

In 2006, the National Renewable Energy Laboratory conducted a nationwide quality survey of pure biodiesel (B100) intended to be used as a blendstock. The study collected random samples throughout the United States and analyzed them for quality against the current and proposed ASTM D6751 fuel quality specifications.
Date: May 1, 2007
Creator: Alleman, T. L.; McCormick, R. L. & Deutch, S.
Object Type: Report
System: The UNT Digital Library
2008 NWFSC Tidal Freshwater Genetics Results (open access)

2008 NWFSC Tidal Freshwater Genetics Results

Genetic Analysis of Juvenile Chinook Salmon for inclusion in 'Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008. Annual Report to Bonneville Power Administration, Contract DE-AC05-76RL01830.'
Date: May 1, 2009
Creator: Teel, David
Object Type: Text
System: The UNT Digital Library
The 3He Supply Problem (open access)

The 3He Supply Problem

One of the main uses for 3He is in gas proportional counters for neutron detection. Radiation portal monitors deployed for homeland security and non-proliferation use such detectors. Other uses of 3He are for research detectors, commercial instruments, well logging detectors, dilution refrigerators, for targets or cooling in nuclear research, and for basic research in condensed matter physics. The US supply of 3He comes almost entirely from the decay of tritium used in nuclear weapons by the US and Russia. A few other countries contribute a small amount to the world’s 3He supply. Due to the large increase in use of 3He for homeland security, the supply has dwindled, and can no longer meet the demand. This white paper reviews the problems of supply, utilization, and alternatives.
Date: May 1, 2009
Creator: Kouzes, Richard T.
Object Type: Report
System: The UNT Digital Library
81st Texas Legislature, House Concurrent Resolution, House Bill 172 (open access)

81st Texas Legislature, House Concurrent Resolution, House Bill 172

Concurrent resolution introduced by the Texas House of Representatives and Senate relating to congratulating Michelle Jackson on her selection as the 2009 Cherry Blossom Princess for the State of Texas.
Date: May 1, 2009
Creator: Texas. Legislature. House of Representatives.
Object Type: Legislative Document
System: The Portal to Texas History
ab initio Solubility Prediction of Non-Electrolytes in Ternary Solvents Using a Combination of Jouyban-Acree and Abraham Models (open access)

ab initio Solubility Prediction of Non-Electrolytes in Ternary Solvents Using a Combination of Jouyban-Acree and Abraham Models

Article on the ab initio solubility prediction of non-electrolytes in ternary solvents using a combination of Jouyban-Acree and Abraham models.
Date: May 1, 2008
Creator: Jouyban, Abolghasem; Khoubnasabjafari, Maryam; Hamidi, Ali A. & Acree, William E. (William Eugene)
Object Type: Article
System: The UNT Digital Library
Absolute intensities of the vacuum ultraviolet spectra in oxide etch plasma processing discharges (open access)

Absolute intensities of the vacuum ultraviolet spectra in oxide etch plasma processing discharges

In this paper, the authors report the absolute intensities of ultraviolet light between 4.9 eV and 24 eV ( 250 nm to 50 mn ) striking a silicon wafer in a number of oxide-etch processing discharges. The emphasis is on photons with energies greater than 8.8 eV, which have enough energy to damage SiO{sub 2}. These discharges were in an inductively-driven Gaseous Electronics Conference reference cell which had been modified to more closely resemble commercial etching tools. Comparisons of measurements made through a side port in the cell and through a hole in the wafer indicate that the VUV light in these discharges is strongly trapped. For the pure halocarbon gases examined in these experiments (C{sub 2}F{sub 6}, CHF{sub 3}, C{sub 4}F{sub 8}), the fluxes of VUV photons to the wafer varied from 1 x 10{sup 15} to 3 x 10{sup 15} photons/cm{sup 2} sec or equivalently from 1.5 to 5 mW/cm{sup 2}. These measurements imply that 0.1% to 0.3% of the rf source power to these discharges ends up hitting the wafer as VUV photons for the typical 20 mT, 200 W rf discharges. For typical ashing discharges containing pure oxygen, the VUV intensities are slightly higher--about 8 mW/cm{sup …
Date: May 1, 2000
Creator: Woodworth, Joseph R.; Riley, Merle E.; Amatucci, Vincent A.; Hamilton, Thomas W. & Aragon, Ben P.
Object Type: Article
System: The UNT Digital Library
An Abstract Description Approach to the Discovery and Classification of Bioinformatics Web Sources (open access)

An Abstract Description Approach to the Discovery and Classification of Bioinformatics Web Sources

The World Wide Web provides an incredible resource to genomics researchers in the form of dynamic data sources--e.g. BLAST sequence homology search interfaces. The growth rate of these sources outpaces the speed at which they can be manually classified, meaning that the available data is not being utilized to its full potential. Existing research has not addressed the problems of automatically locating, classifying, and integrating classes of bioinformatics data sources. This paper presents an overview of a system for finding classes of bioinformatics data sources and integrating them behind a unified interface. We examine an approach to classifying these sources automatically that relies on an abstract description format: the service class description. This format allows a domain expert to describe the important features of an entire class of services without tying that description to any particular Web source. We present the features of this description format in the context of BLAST sources to show how the service class description relates to Web sources that are being described. We then show how a service class description can be used to classify an arbitrary Web source to determine if that source is an instance of the described service. To validate the effectiveness …
Date: May 1, 2003
Creator: Rocco, D & Critchlow, T J
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
Accelerated Stress Testing of Thin-Film Modules with SnO2:F Transparent Conductors (open access)

Accelerated Stress Testing of Thin-Film Modules with SnO2:F Transparent Conductors

This paper reviews a testing program conducted at NREL for the past two years that applied voltage, water vapor, and light stresses to thin-film photovoltaic (PV) modules with SnO2:F transparent conducting oxides (TCOs) deposited on soda-lime glass superstrates. Electrochemical corrosion at the glass-TCO interface was observed to result in delamination of the thin-film layers. Experimental testing was directed toward accelerating the corrosion and understanding the nature of the resulting damage.
Date: May 1, 2003
Creator: Osterwald, C. R.; McMahon, T. J.; del Cueto, J. A.; Adelstein, J. & Puett, J.
Object Type: Article
System: The UNT Digital Library