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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
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
$1.2 Million in Savings Identified in Akzo Nobel Assessment: Plant-Wide Assessment Summary--Chemicals (Fact Sheet)
Summary of Akzo Nobel's plant-wide assessment to identify energy and cost saving opportunities at the corporation's Surface Chemistry plant in Morris, Illinois.
Date:
August 1, 2003
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
$1.2 Million in Savings Identified in Caraustar Assessment: Plant-Wide Assessment Summary--Forest Products (Fact Sheet)
Summary of Caraustars plant-wide assessment to identify energy and cost saving opportunities at the corporations recycled paperboard mill in Rittman, Ohio.
Date:
August 1, 2003
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
1.5-GeV FFAG Accelerator for the AGS Facility
N/A
Date:
February 1, 2004
Creator:
Ruggiero, A. G.; Blaskiewicz, M.; Courant, E.; Trbojevic, D.; Tsoupas, N. & Zhang, W.
Object Type:
Report
System:
The UNT Digital Library
$1.6 Million in Savings Identified in Anchor Assessment: Plant-Wide Assessment Summary--Glass (Fact Sheet)
Summary of Anchor Glass' plant-wide assessment to identify energy and cost saving opportunities at the corporation's facilities in Warner Robins, GA and Jacksonville, FL.
Date:
August 1, 2003
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
$1.6 Million in Savings Identified in Augusta Newsprint Assessment: Plant-Wide Assessment Summary--Forest Products (Fact Sheet)
Augusta Newsprint and its partners conducted a systematic plant-wide assessment (PWA) to identify energy- and cost-saving opportunities at the company's plant in Augusta, Georgia. The assessment team identified$1.6 million in potential annual savings.
Date:
August 1, 2003
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
1/6TH SCALE STRIP EFFLUENT FEED TANK-MIXING RESULTS USING MCU SOLVENT
The purpose of this task was to determine if mixing was an issue for the entrainment and dispersion of the Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU) solvent in the Defense Waste Processing Facility (DWPF) Strip Effluent Feed Tank (SEFT). The MCU strip effluent stream containing the Cs removed during salt processing will be transferred to the DWPF for immobilization in HLW glass. In lab-scale DWPF chemical process cell testing, mixing of the solvent in the dilute nitric acid solution proved problematic, and the Savannah River National Laboratory (SRNL) was requested to perform scaled SEFT mixing tests to evaluate whether the problem was symptomatic of the lab-scale set-up or of the solvent. The solvent levels tested were 228 and 235 ppm, which represented levels near the estimated DWPF solvent limit of 239 ppm in 0.001M HNO{sub 3} solution. The 239 ppm limit was calculated by Norato in X-CLC-S-00141. The general approach for the mixing investigation was to: (1) Investigate the use of fluorescent dyes to aid in observing the mixing behavior. Evaluate and compare the physical properties of the fluorescent dyed MCU solvents to the baseline Oak Ridge CSSX solvent. Based on the data, use the dyed MCU solvent …
Date:
February 1, 2006
Creator:
Hansen, E.
Object Type:
Report
System:
The UNT Digital Library
A 1 MEGAWATT POLYPHASE BOOST CONVERTER-MODULATOR FOR KLYSTRON PULSE APPLICATION
This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt-peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. A review of these design parameters and the first results of the performance characteristics will be presented.
Date:
June 1, 2001
Creator:
Reass, W. A.; Doss, J. D. & Gribble, R. F.
Object Type:
Article
System:
The UNT Digital Library
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
$2.9 Million in Savings Identified in Georgia-Pacific Assessment: Plant-Wide Assessment Study--Forest Products (Fact Sheet)
Summary of Georgia-Pacific Corporation's plant-wide assessment to identify energy and cost saving opportunities at the corporation's paper mill in Palatka, Florida.
Date:
August 1, 2003
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
2-pi Photoproduction from CLAS and CB-ELSA - The Search for Missing Resonances
2-pi-photoproduction is one of the promising reactions to search for baryon resonances that have been predicted but have not yet been observed. The gamma-rho --> rho-pi{sup 0}-pi{sup 0}(CB-ELSA) and the gamma-rho --> rho-pi{sup +}-pi{sup -} (CLAS) data show interesting resonance structures. A partial wave analysis (PWA) has to be done to determine which baryon resonances contribute what their quantum numbers and their relative couplings to the different accessible rho-2-pi-channels and to the photon are. First preliminary PWA-results on the lowest energy rho-pi{sup 0}-pi{sup 0} data (sq rt s<1.8 GeV)look very promising. From an extension of this analysis to higher energies combining the rho-pi{sup 0}-pi{sup 0} and the rho-pi{sup +}-pi{sup -}-data, one can expect; interesting results on resonances decaying into Delta-pi, N-rho, N(pi-pi)s, N*-pi, and Delta*-pi.
Date:
October 1, 2003
Creator:
Thoma, Ulrike
Object Type:
Article
System:
The UNT Digital Library
$3.5 Million in Savings Identified in Appleton Assessment: Plant-Wide Assessment Summary--Forest Products (Fact Sheet)
Summary of Appleton Paper, Inc.'s plant-wide assessment to identify energy and cost saving opportunities at the corporation's paper mill in West Carrollton, Ohio.
Date:
August 1, 2003
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
$3.6 Million in Savings Identified in AMCAST Assessment (Revised)
Summary of AMCAST Industrial Corporation's plant-wide assessment to identify energy and cost saving opportunities at the corporation's facility in Wapakoneta, Ohio.
Date:
August 1, 2004
Creator:
unknown
Object Type:
Text
System:
The UNT Digital Library
3.9 GHz superconducting accelerating 9-cell cavity vertical test results
The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve the beam performance of the FLASH (TTF/DESY) facility [1]. In the frame of a collaborative agreement, Fermilab will provide DESY with a cryomodule containing a string of four cavities. In addition, a second cryomodule with one cavity will be fabricated for installation in the Fermilab photo-injector, which will be upgraded for the ILC accelerator test facility. The first 9-cell Nb cavities were tested in a vertical setup and they didn't reach the designed accelerating gradient [2]. The main problem was a multipactor in the HOM couplers, which lead to overheating and quenching of the HOM couplers. New HOM couplers with improved design are integrated in the next 9-cell cavities. In this paper we present all results of the vertical tests.
Date:
June 1, 2007
Creator:
Khabiboulline, Timergali; Cooper, Charles; Dhanaraj, Nandhini; Edwards, Helen; Foley, Mike; Harms, Elvin et al.
Object Type:
Article
System:
The UNT Digital Library
3.9 GHz superconducting accelerating 9-cell cavity vertical test results
None
Date:
June 1, 2007
Creator:
Khabiboulline, Timergali; Cooper, Charles; Dhanaraj, Nandhini; Edwards, Helen; Foley, Mike; Harms, Elvin et al.
Object Type:
Article
System:
The UNT Digital Library
3-D Cavern Enlargement Analyses
Three-dimensional finite element analyses simulate the mechanical response of enlarging existing caverns at the Strategic Petroleum Reserve (SPR). The caverns are located in Gulf Coast salt domes and are enlarged by leaching during oil drawdowns as fresh water is injected to displace the crude oil from the caverns. The current criteria adopted by the SPR limits cavern usage to 5 drawdowns (leaches). As a base case, 5 leaches were modeled over a 25 year period to roughly double the volume of a 19 cavern field. Thirteen additional leaches where then simulated until caverns approached coalescence. The cavern field approximated the geometries and geologic properties found at the West Hackberry site. This enabled comparisons are data collected over nearly 20 years to analysis predictions. The analyses closely predicted the measured surface subsidence and cavern closure rates as inferred from historic well head pressures. This provided the necessary assurance that the model displacements, strains, and stresses are accurate. However, the cavern field has not yet experienced the large scale drawdowns being simulated. Should they occur in the future, code predictions should be validated with actual field behavior at that time. The simulations were performed using JAS3D, a three dimensional finite element analysis …
Date:
March 1, 2002
Creator:
EHGARTNER, BRIAN L. & SOBOLIK, STEVEN R.
Object Type:
Report
System:
The UNT Digital Library
3-D DETERMINISTIC TRANSPORT METHODS RESEARCH AT LANL UNDER ASCI
None
Date:
January 1, 2000
Creator:
Morel, J.
Object Type:
Article
System:
The UNT Digital Library
A 3-D Model of Signaling and Transport Pathways in Epithelial Cells
A 3-dimensional computer model was developed to simulate the spatial and chemical evolution of calcium ions inside an array of human epithelial kidney cells. This is a prototype model, intended to develop a methodology to incorporate much more complex interactions of metabolic and other processes within many types of cells and lead to increased ability to predict cellular responses to disease as well as to chemical and biological warfare situations. Preliminary tests of the model are described.
Date:
April 1, 2005
Creator:
Quong, Andrew A. & Westbrook, Charles K.
Object Type:
Report
System:
The UNT Digital Library
A 3-D model of superfluid helium suitable for numerical analysis
The two-fluid description is a very successful phenomenological representation of the properties of Helium II. A 3-D model suitable for numerical analysis based on the Landau-Khalatnikov description of Helium II is proposed. In this paper we introduce a system of partial differential equations that is both complete and consistent as well as practical, to be used for a 3-D solution of the flow of Helium II. The development of a 3-D numerical model for Helium II is motivated by the need to validate experimental results obtained by observing the normal component velocity distribution in a Helium II thermal counter-flow using the Particle Image Velocimetry (PIV) technique.
Date:
January 1, 2008
Creator:
Darve, C.; U., /Fermilab /Northwestern; Patankar, N.A.; U., /Northwestern; Van Sciver, S.W. & Lab., /Natl. High Mag. Field
Object Type:
Article
System:
The UNT Digital Library
A 3-D ray-trace model for an AMR code on distributed processors
Distributed memory AMR codes provide a special challenge for laser ray-trace modeling. For RAGE we follow the energy-carrying rays through each cell, checking for crossings which require collection a new cell index (1 of 9 in 2D). Density gradients for ray deflections can be calculated 'on the fly.' Substantial excursions must be made from the legacy PIC particle area-weighting approach, but this serves as a useful 1st step. Similarly, IDL now offers a quick graphical rendering, while ENSIGHT graphics beautifully captures the 3D light refraction and deposition.
Date:
January 1, 2002
Creator:
Mason, R. J. (Rodney J.)
Object Type:
Article
System:
The UNT Digital Library
A 3-D SAR approach to IFSAR processing
Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super-resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.
Date:
March 1, 2000
Creator:
Doerry, Armin W. & Bickel, Doug L.
Object Type:
Article
System:
The UNT Digital Library
3-D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface
Gian Fradelizio, a Rice Ph.D. student has completed reprocessing the 3D seismic reflection data acquired at Hill AFB through post-stack depth migration for comparison to the traveltime and waveform tomography results. Zelt, Levander, Fradelizio, and 5 others spent a week at Hill AFB in September 2005, acquiring an elastic wave data set along 2 profiles. We used 60 3-component Galperin mounted 40 Hz geophones recorded by 3 GEOMETRICS Stratavision systems. The seismic source employed was a sledgehammer used to generate transverse, and radial, and vertical point source data. Data processing has begun at Rice to generate S-wave reflection and refraction images. We also acquired surface wave and ground penetrating rada data to complement the elastic wave dataset.
Date:
June 1, 2005
Creator:
Levander, Alan R.
Object Type:
Report
System:
The UNT Digital Library
3-D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface
Under ER63662, 3-D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface, we have completed a number of subprojects associated with the Hill Air Force Base (HAFB) high resolution 3-D reflection/tomography dataset.
Date:
December 1, 2004
Creator:
Levander, Alan R.
Object Type:
Report
System:
The UNT Digital Library
3-D SIMULATION FOR ASSESSMENT OF TRANSPARENT WEAPON DISASSEMBLY OPERATIONS
None
Date:
September 1, 2000
Creator:
JACKSON, J. W.
Object Type:
Article
System:
The UNT Digital Library