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734 Matching Results
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Navy Littoral Combat Ship (LCS) Program: Background and Issues for Congress
This report provides background information and potential issues for Congress on the Littoral Combat Ship (LCS), a relatively inexpensive Navy surface combatant equipped with modular "plug-and-fight" mission packages for countering mines, small boats, and diesel-electric submarines, particularly in littoral (i.e., near-shore) waters.
Date:
June 25, 2014
Creator:
O'Rourke, Ronald
Object Type:
Report
System:
The UNT Digital Library
Multiyear Procurement (MYP) and Block Buy Contracting in Defense Acquisition: Background and Issues for Congress
This report provides background information and issues for Congress on multiyear procurement (MYP) and block buy contracting (BBC), which are special contracting mechanisms that Congress permits the Department of Defense (DOD) to use for a limited number of defense acquisition programs. Compared to the standard or default approach of annual contracting, MYP and BBC have the potential for reducing weapon procurement costs by several percent.
Date:
June 25, 2014
Creator:
O'Rourke, Ronald & Schwartz, Moshe
Object Type:
Report
System:
The UNT Digital Library
Tobacco Price Support: An Overview of the Program
About 94 percent of U.S. tobacco production is flue-cured and burley (cigarette tobacco types). These crops are particularly important to the agriculture of North Carolina and Kentucky. The federal tobacco price support program is designed to support and stabilize prices for farmers.
Date:
June 25, 2004
Creator:
Womach, Jasper
Object Type:
Report
System:
The UNT Digital Library
Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard
The Energy Independence and Security Act of 2007 (EISA) significantly expanded the renewable fuel standard (RFS) established in the Energy Policy Act of 2005. EISA requires an increasing amount of the 36 billion gallons of renewable fuel by 2022 mandate be met with "advanced biofuels." This report defines the classification "biofuels," discusses the ongoing debate regarding several aspects of biofuels endeavors, and discusses related legislative efforts on climate change policy and low-carbon fuel standards.
Date:
June 25, 2009
Creator:
Yacobucci, Brent D. & Bracmort, Kelsi S.
Object Type:
Report
System:
The UNT Digital Library
Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.
Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic liquids containing octylpyridinium cations are very good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. Such liquids containing a disulfide functional group are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.
Date:
June 25, 2007
Creator:
Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz & Prausnitz, John M.
Object Type:
Article
System:
The UNT Digital Library
Design and Performance of the Matching Beamline Between the Bnl Ebis and an Rfq.
A part of a new EBIS-based heavy ion preinjector, the low energy beam transport (LEBT) section between the high current EBIS and the RFQ is a challenging design, because it must serve many functions. In addition to the requirement to provide an efficient matching between the EBIS and the RFQ, this line must serve as a fast ''switchyard'', allowing singly charged ions from external sources to be transported into the EBIS trap region, and extracted, highly charged ions to be deflected to off-axis diagnostics (time-of-flight or emittance). The space charge of the 5-10 mA extracted heavy ion beam is a major consideration in the design, and the space charge force varies for different ion beams having Q/m from 1-0.16. The line includes electrostatic lenses, spherical and parallel-plate deflectors, magnetic solenoid, and diagnostics for measuring current, charge state distributions, emittance, and profile. A prototype of this beamline has been built, and results of tests are presented.
Date:
June 25, 2007
Creator:
Alessi, J.; Beebe, E.; Brodowski, J.; Kponou, A.; Okamura, M.; Pikin, A. et al.
Object Type:
Article
System:
The UNT Digital Library
Heavy ion fusion science research for high energy density physics and fusion applications
During the past two years, the U.S. heavy ion fusion science program has made significant experimental and theoretical progress in simultaneous transverse and longitudinal beam compression, ion-beam-driven warm dense matter targets, high brightness beam transport, advanced theory and numerical simulations, and heavy ion target designs for fusion. First experiments combining radial and longitudinal compression of intense ion beams propagating through background plasma resulted in on-axis beam densities increased by 700X at the focal plane. With further improvements planned in 2007, these results will enable initial ion beam target experiments in warm dense matter to begin next year at LBNL. We are assessing how these new techniques apply to low-cost modular fusion drivers and higher-gain direct-drive targets for inertial fusion energy.
Date:
June 25, 2007
Creator:
Logan, B. G.; Bieniosek, F. M.; Barnard, J. J.; Cohen, R. H.; Coleman, J. E.; Davidson, R. C. et al.
Object Type:
Article
System:
The UNT Digital Library
Vibration Measurements to Study the Effect of Cryogen Flow in Superconducting Quadrupole.
The conceptual design of compact superconducting magnets for the International Linear Collider final focus is presently under development. A primary concern in using superconducting quadrupoles is the potential for inducing additional vibrations from cryogenic operation. We have employed a Laser Doppler Vibrometer system to measure the vibrations in a spare RHIC quadrupole magnet under cryogenic conditions. Some preliminary results of these studies were limited in resolution due to a rather large motion of the laser head as well as the magnet. As a first step towards improving the measurement quality, a new set up was used that reduces the motion of the laser holder. The improved setup is described, and vibration spectra measured at cryogenic temperatures, both with and without helium flow, are presented.
Date:
June 25, 2007
Creator:
He, P.; Anerella, M.; Aydin, S.; Ganetis, G.; Harrison, M.; Jain, A. et al.
Object Type:
Article
System:
The UNT Digital Library
Thermal-fluid and electrochemical modeling and performance study of a planar solid oxide electrolysis cell : analysis on SOEC resistances, size, and inlet flow conditions.
Argonne National Laboratory and Idaho National Laboratory researchers are analyzing the electrochemical and thermal-fluid behavior of solid oxide electrolysis cells (SOECs) for high temperature steam electrolysis using computational fluid dynamics (CFD) techniques. The major challenges facing commercialization of steam electrolysis technology are related to efficiency, cost, and durability of the SOECs. The goal of this effort is to guide the design and optimization of performance for high temperature electrolysis (HTE) systems. An SOEC module developed by FLUENT Inc. as part of their general CFD code was used for the SOEC analysis by INL. ANL has developed an independent SOEC model that combines the governing electrochemical mechanisms based on first principals to the heat transfer and fluid dynamics in the operation of SOECs. The ANL model was embedded into the commercial STAR-CD CFD software, and is being used for the analysis of SOECs by ANL. The FY06 analysis performed by ANL and reported here covered the influence of electrochemical properties, SOEC component resistances and their contributing factors, SOEC size and inlet flow conditions, and SOEC flow configurations on the efficiency and expected durability of these systems. Some of the important findings from the ANL analysis are: (1) Increasing the inlet mass …
Date:
June 25, 2008
Creator:
Yildiz, B.; Smith, J. & Sofu, T.
Object Type:
Report
System:
The UNT Digital Library
Isotopic mass-dependence of noble gas diffusion coefficients inwater
Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D prop m-beta with beta<0.2, whichrefutes the kinetic theory model underlying all currentapplications.
Date:
June 25, 2007
Creator:
Bourg, I.C. & Sposito, G.
Object Type:
Article
System:
The UNT Digital Library
NOBLE METAL CHEMISTRY AND HYDROGEN GENERATION DURING SIMULATED DWPF MELTER FEED PREPARATION
Simulations of the Defense Waste Processing Facility (DWPF) Chemical Processing Cell vessels were performed with the primary purpose of producing melter feeds for the beaded frit program plus obtaining samples of simulated slurries containing high concentrations of noble metals for off-site analytical studies for the hydrogen program. Eight pairs of 22-L simulations were performed of the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles. These sixteen simulations did not contain mercury. Six pairs were trimmed with a single noble metal (Ag, Pd, Rh, or Ru). One pair had all four noble metals, and one pair had no noble metals. One supporting 4-L simulation was completed with Ru and Hg. Several other 4-L supporting tests with mercury have not yet been performed. This report covers the calculations performed on SRNL analytical and process data related to the noble metals and hydrogen generation. It was originally envisioned as a supporting document for the off-site analytical studies. Significant new findings were made, and many previous hypotheses and findings were given additional support as summarized below. The timing of hydrogen generation events was reproduced very well within each of the eight pairs of runs, e.g. the onset of hydrogen, peak …
Date:
June 25, 2008
Creator:
Koopman, D
Object Type:
Report
System:
The UNT Digital Library
End-to-End Simulations for the Ebis Preinjector.
The EBIS Project at Brookhaven National Laboratory is in the second year of a four-year project. It will replace the Tandem Van de Graaff accelerators with an Electron Beam Ion Source, an RFQ, and one IH Linac cavity, as the heavy ion preinjector for the Relativistic Heavy Ion Collider (RHIC), and for the NASA Space Radiation Laboratory (NSRL). The preinjector will provide all ions species, He to U, (Q/m >0.16) at 2 MeV/amu at a repetition rate of 5 Hz, pulse length of 10-40 {micro}s, and intensities of {approx}2.0 mA. End-to-end simulations (from EBIS to the Booster injection) as well as error sensitivity studies will be presented and physics issues will be discussed.
Date:
June 25, 2007
Creator:
Raparia, D.; Alessi, J.; Kponou, A.; Pikin, A.; Ritter, J.; Minaev, S. et al.
Object Type:
Article
System:
The UNT Digital Library
Optical Faraday Cup for Heavy Ion Beams
We have been using alumina scintillators for imaging beams in heavy-ion beam fusion experiments in 2 to 4 transverse dimensions [1]. The scintillator has a limited lifetime under bombardment by the heavy ion beams. As a possible replacement for the scintillator, we are studying the technique of imaging the beam on a gas cloud. A gas cloud for imaging the beam may be created on a solid hole plate placed in the path of the beam, or by a localized gas jet. It is possible to image the beam using certain fast-quenching optical lines that closely follow beam current density and are independent of gas density. We describe this technique and show preliminary experimental data. This approach has promise to be a new fast beam current diagnostic on a nanosecond time scale.
Date:
June 25, 2007
Creator:
Bieniosek, Frank; Bieniosek, F. M.; Eylon, S.; Roy, P. K. & Yu, S. S.
Object Type:
Article
System:
The UNT Digital Library
Plasma Lens for Us Based Super Neutrino Beam at Either Fnal or Bnl.
The plasma lens concept is examined as an alternative to focusing horns and solenoids for a neutrino beam facility. The concept is based on a combined high-current lens/target configuration. Current is fed at an electrode located downstream from the beginning of the target where pion capturing is needed. The current is carried by plasma outside the target. A second plasma lens section, with an additional current feed, follows the target. The plasma is immersed in a relatively small solenoidal magnetic field to facilitate its current profile shaping to optimize pion capture. Simulations of the not yet fully optimized configuration yielded a 25% higher neutrino flux at a detector situated at 3 km from the target than the horn system for the entire energy spectrum and a factor of 2.47 higher flux for neutrinos with energy larger than 3 GeV. A major advantage of plasma lenses is in background reduction. In anti-neutrino operation, neutrino background is reduced by a factor of close to 3 for the whole spectrum, and for and for energy larger than 3 GeV, neutrino background is reduced by a factor of 3.6. Plasma lenses have additional advantages: larger axial currents, high signal purity: minimal neutrino background in …
Date:
June 25, 2007
Creator:
Hershcovitch, A.; Weng, W.; Diwan, M.; Gallardo, J.; Kirk, H.; Johnson, B. et al.
Object Type:
Article
System:
The UNT Digital Library
Numerical Study of Coulomb Scattering Effects on Electron Beamfrom a Nano-Tip
Nano-tips with high acceleration gradient around the emission surface have been proposed to generate high brightness beams. However, due to the small size of the tip, the charge density near the tip is very high even for a small number of electrons. The stochastic Coulomb scattering near the tip can degrade the beam quality and cause extra emittance growth and energy spread. In the paper, we present a numerical study of these effects using a direct relativistic N-body model. We found that emittance growth and energy spread, due to Coulomb scattering, can be significantly enhanced with respect to mean-field space-charge calculations.
Date:
June 25, 2007
Creator:
Qiang, Ji; Corlett, John N.; Lidia, Steven M.; Padmore, HowardA.; Wan, Weishi; Zholent, Andrew A. et al.
Object Type:
Article
System:
The UNT Digital Library
Performance of capillary discharge guided laser plasma wakefieldaccelerator
A GeV-class laser-driven plasma-based wakefield acceleratorhas been realized at the Lawrence Berkeley National Laboratory (LBNL).The device consists of the 40TW high repetition rate Ti:sapphire LOASISlaser system at LBNL and a gas-filled capillary discharge waveguidedeveloped at Oxford University. The operation of the capillary dischargeguided laser plasma wakefield accelerator with a capillaryof 225 mu mdiameter and 33 mm in length was analyzed in detail. The input intensitydependence suggests that excessive self-injection causes increased beamloading leading to broadband lower energy electron beam generation. Thetrigger versus laser arrival timing dependence suggests that the plasmachannel parameters can be tuned to reduce beam divergence.
Date:
June 25, 2007
Creator:
Nakamura, Kei; Esarey, Eric; Geddes, Cameron G. R.; Gonsalves, Anthony J.; Leemans, Wim P.; Panasenko, Dmitriy et al.
Object Type:
Article
System:
The UNT Digital Library
Physicochemical properties and toxicities of hydrophobicpiperidinium and pyrrolidinium ionic liquids
Some properties are reported for hydrophobic ionic liquids (IL) containing 1-methyl-1-propyl pyrrolidinium [MPPyrro]{sup +}, 1-methyl-1-butyl pyrrolidinium [MBPyrro]{sup +}, 1-methyl-1-propyl piperidinium [MPPip]{sup +}, 1-methyl-1-butyl piperidinium [MBPip]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPyrro]{sup +} and 1-methyl-1-octylpiperidinium [MOPip]{sup +} cations. These liquids provide new alternatives to pyridinium and imidazolium ILs. High thermal stability of an ionic liquid increases safety in applications like rechargeable lithium-ion batteries and other electrochemical devices. Thermal properties, ionic conductivities, viscosities, and mutual solubilities with water are reported. In addition, toxicities of selected ionic liquids have been measured using a human cancer cell-line. The ILs studied here are sparingly soluble in water but hygroscopic. We show some structure-property relationships that may help to design green solvents for specific applications. While ionic liquids are claimed to be environmentally-benign solvents, as yet few data have been published to support these claims.
Date:
June 25, 2007
Creator:
Salminen, Justin; Papaiconomou, Nicolas; Kumar, R. Anand; Lee,Jong-Min; Kerr, John; Newman, John et al.
Object Type:
Article
System:
The UNT Digital Library
TOWARDS 100% POLARIZATION IN THE OPTICALLY-PUMPED POLARIZED ION SOURCE.
The depolarization factors in the multi-step spin-transfer polarization technique and basic limitations on maximum polarization in the OPPIS (Optically-Pumped Polarized H{sup -} Ion Source) are discussed. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86-90%. This contributed to increasing polarization in the AGS and RHIC to 65-70%.
Date:
June 25, 2007
Creator:
ZELENSKI,A.; ALESSI, J.; KOKHANOVSKI, S.; KPONOU, A.; RITTER, B.J. & ZUBETS, V.
Object Type:
Article
System:
The UNT Digital Library
Longitudinal Single-Bunch Instability in the ILC Damping Rings: Estimate of Current Threshold
Characterization of single-bunch instabilities in the International Linear Collider (ILC) damping rings (DRs) has been indicated as a high-priority activity toward completion of an engineering design. In this paper we report on a first estimate ofthe current thresholds for the instability using numerical and analytical models of the wake potentials associated with the various machine components. The numerical models were derived (upon appropriate scaling) from designs of the correspondingcomponents installed in existing machines. The current thresholds for instabilities were determined by numerical solution of the Vlasov equation for the longitudinal dynamics. For the DR baseline lattice as of Feb. 2007 we find the critical current forinstability to be safely above the design specifications leaving room for further optimization of the choice of the momentum compaction.
Date:
June 25, 2008
Creator:
Venturini, Marco & Venturini, Marco
Object Type:
Report
System:
The UNT Digital Library
Thermal Emittance Measurement Design for Diamond Secondary Emission
Thermal emittance is a very important characteristic of cathodes. A carefully designed method of measuring the thermal emittance of secondary emission from diamond is presented. Comparison of possible schemes is carried out by simulation, and the most accessible and accurate method and values are chosen. Systematic errors can be controlled and maintained at small values, and are carefully evaluated. Aberration and limitations of all equipment are taken into account.
Date:
June 25, 2007
Creator:
Wu, Q.; Ben-Zvi, Ilan; Burrill, A.; Chang, X.; Kayran, D.; Rao, T. et al.
Object Type:
Article
System:
The UNT Digital Library
ICD Complex Operations and Maintenance Plan
This Operations and Maintenance (O&M) Plan describes how the Idaho National Laboratory (INL) conducts operations, winterization, and startup of the Idaho CERCLA Disposal Facility (ICDF) Complex. The ICDF Complex is the centralized INL facility responsible for the receipt, storage, treatment (as necessary), and disposal of INL Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) remediation waste.
Date:
June 25, 2007
Creator:
Gibson, P. L.
Object Type:
Report
System:
The UNT Digital Library
SUPERCONDUCTING MAGNET NEEDS FOR THE ILC.
The ILC Reference Design Report was completed early in February 2007. The Magnet Systems Group was formed to translate magnetic field requirements into magnet designs and cost estimates for the Reference Design. As presently configured, the lLC will have more than 13,000 magnetic elements of which more than 2300 will be based on superconducting technology. This paper will describe the major superconducting magnet needs for the ILC as presently determined by the Area Systems Groups, responsible for beam line design, working with the Magnet Systems Group. The superconducting magnet components include Main Linac quadrupoles, Positron Source undulators, Damping Ring wigglers, a complex array of Final Focus superconducting elements in the Beam Delivery System, and large superconducting solenoids in the e{sup +} and e{sup -} Sources, and the Ring to Main Linac lines.
Date:
June 25, 2007
Creator:
PARKER, B.; TOMPKINS, J. C.; KASHIKHIN, V. I.; PALMER, M. A. & CLARKE, J. A.
Object Type:
Article
System:
The UNT Digital Library
Colliding pulse injection experiments in non-collinear geometryfor controlled laser plasma wakefield acceleration of electrons
An optical injection scheme for a laser-plasma basedaccelerator which employs a non-collinear counter-propagating laser beamto push background electrons in the focusing and acceleration phase viaponderomotive beat with the trailing part of the wakefield driver pulseis discussed. Preliminary experiments were performed using a drive beamof a_0 = 2.6 and colliding beam of a_1 = 0.8 both focused on the middleof a 200 mu m slit jet backed with 20 bar, which provided ~; 260 mu mlong gas plume. The enhancement in the total charge by the collidingpulse was observed with sharp dependence on the delay time of thecolliding beam. Enhancement of the neutron yield was also measured, whichsuggests a generation of electrons above 10 MeV.
Date:
June 25, 2007
Creator:
Toth, Carl B.; Esarey, Eric H.; Geddes, Cameron G.R.; Leemans,Wim P.; Nakamura, Kei; Panasenko, Dmitriy et al.
Object Type:
Article
System:
The UNT Digital Library
THE SUPERCONDUCTION MAGNETS OF THE ILC BEAM DELIVERY SYSTEM.
The ILC Reference Design Report was completed early in February 2007. The Magnet Systems Group was formed to translate magnetic field requirements into magnet designs and cost estimates for the Reference Design. As presently configured, the ILC will have more than 13,000 magnetic elements of which more than 2300 will be based on superconducting technology. This paper will describe the major superconducting magnet needs for the ILC as presently determined by the Area Systems Groups, responsible for beam line design, working with the Magnet Systems Group. The superconducting magnet components include Main Linac quadrupoles, Positron Source undulators, Damping Ring wigglers, a complex array of Final Focus superconducting elements in the Beam Delivery System, and large superconducting solenoids in the e{sup +} and e{sup -} Sources, and the Ring to Main Linac lines.
Date:
June 25, 2007
Creator:
PARKER,B.; ANEREELA, M.; ESCALLIE, J.; HE, P.; JAIN, A.; MARONE, A. et al.
Object Type:
Article
System:
The UNT Digital Library