Resource Type

Nonlinear ion-cyclotron waves in mirror machines. Paper IAEA-CN-38/S-1 (open access)

Nonlinear ion-cyclotron waves in mirror machines. Paper IAEA-CN-38/S-1

Experimental results on ion-cyclotron waves observed in the 2XIIB mirror machine are reviewed, and relevant theoretical work is discussed. The work reported generally substantiates the quasilinear diffusion model of mirror-plasma confinement, but also suggests alternatives. The end-loss current required by theory of the drift-cyclotron loss-cone (DCLC) instability agrees with measurements of this current. The experiment indicates that an increased ratio of plasma radius to ion gyroradius improves plasma confinement. However, measurements sometimes show a second ion-cyclotron mode, which is not the DCLC mode. Theoretical work on loss-cone instabilities has concentrated on linear, quasilinear, and fully nonlinear models of increased sophistication and experimental applicability.
Date: May 22, 1980
Creator: Cohen, B. I.; Smith, G. R. & Berk, H. L.
System: The UNT Digital Library
Plasma confinement experiments in the TMX tandem mirror. Paper IAEA-CN-38/F-1 (open access)

Plasma confinement experiments in the TMX tandem mirror. Paper IAEA-CN-38/F-1

Results from the new Tandem Mirror Experiment (TMX) are described. Tandem-mirror density and potential profiles are produced using end-plug neutral-beam injection and central-cell gas-fueling. TMX parameters are near those predicted theoretically. The end-plug electron temperature is higher than in the comparably sized single-mirror 2XIIB. Axial confinement of the finite-beta central-cell plasma is improved by the end plugs by as much as a factor of 9. In TMX, end-plug microinstability limits central-cell confinement in agreement with theory.
Date: May 22, 1980
Creator: Simonen, T. C.; Anderson, C. A. & Casper, T. A.
System: The UNT Digital Library
Harmonic generation of ion waves due to Brillouin backscattering (open access)

Harmonic generation of ion waves due to Brillouin backscattering

We report results of simulations of stimulated Brillouin backscatter in which we see the second spatial harmonic of the ion density fluctuation and compare with linear, fluid theory. We also describe examples of the competition between Raman and Brillouin backscatter. 21 refs., 3 figs.
Date: May 22, 1985
Creator: Estabrook, K.; Kruer, W. L. & Haines, M. G.
System: The UNT Digital Library
Theory of field-reversed mirrors and field-reversed plasma-gun experiments. Paper IAEA-CN-38/R-2 (open access)

Theory of field-reversed mirrors and field-reversed plasma-gun experiments. Paper IAEA-CN-38/R-2

Experimental and theoretical studies of field reversal in a mirror machine are reported. Plasma-gun experiments demonstrate that reversed-field plasma layers are formed. Low energy plasma flowing behind the initially produced plasma front prevents tearing of the layer from the gun muzzle. MHD simulation shows that tearing can be obtained by impeding the slow plasma flow with a plasma divider. It is demonstrated theoretically that a field-reversed mirror imbedded in a multipole field can be sustained in steady state with neutral-beam injection even in the absence of impurities. MHD stability analysis shows that growth rates of elongated reversed-field theta-pinch configurations decrease with axial extension, which indicates the importance of including finite Larmor radius in the analysis. Tilting-mode criteria are dramatically improved by proper shaping, and a problimak shape is proposed. Tearing mode stability of reversed-field theta-pinches is greatly enhanced by flux exclusion. Self-consistent, 1-1/2-dimensional transport codes have been developed, and initial results are presented.
Date: May 22, 1980
Creator: Anderson, D.V.; Auerbach, S.P. & Berk, H.L.
System: The UNT Digital Library
Nutrient-Deprivation Autophagy Factor-1 (NAF-1): Biochemical Properties of a Novel Cellular Target for Anti-Diabetic Drugs (open access)

Nutrient-Deprivation Autophagy Factor-1 (NAF-1): Biochemical Properties of a Novel Cellular Target for Anti-Diabetic Drugs

Article on nutrient-deprivation autophagy factor-1 (NAF-1) and biochemical properties of a novel cellular target for anti-diabetic drugs.
Date: December 11, 2012
Creator: Tamir, Sagi; Zuris, John A.; Agranat, Lily; Lipper, Colin H.; Conlan, Andrea R.; Michaeli, Dorit et al.
System: The UNT Digital Library
Nutrient-Deprivation Autophagy Factor-1 (NAF-1): Biochemical Properties of a Novel Cellular Target for Anti-Diabetic Drugs (open access)

Nutrient-Deprivation Autophagy Factor-1 (NAF-1): Biochemical Properties of a Novel Cellular Target for Anti-Diabetic Drugs

Article on nutrient-deprivation autophagy factor-1 (NAF-1) and biochemical properties of a novel cellular target for anti-diabetic drugs.
Date: December 11, 2012
Creator: Tamir, Sagi; Zuris, John A.; Agranat, Lily; Lipper, Colin H.; Conlan, Andrea R.; Michaeli, Dorit et al.
System: The UNT Digital Library
Sulfidation of Cadmium at the Nanoscale (open access)

Sulfidation of Cadmium at the Nanoscale

We investigate the evolution of structures that result when spherical Cd nanoparticles of a few hundred nanometers in diameter react with dissolved molecular sulfur species in solution to form hollow CdS. Over a wide range of temperatures and concentrations, we find that rapid Cd diffusion through the growing CdS shell localizes the reaction front at the outermost CdS/S interface, leading to hollow particles when all the Cd is consumed. When we examine partially reacted particles, we find that this system differs significantly from others in which the nanoscale Kirkendall effect has been used to create hollow particles. In previously reported systems, partial reaction creates a hollow particle with a spherically symmetric metal core connected to the outer shell by filaments. In contrast, here we obtain a lower symmetry structure, in which the unreacted metal core and the coalesced vacancies separate into two distinct spherical caps, minimizing the metal/void interface. This pattern of void coalescence is likely to occur in situations where the metal/vacancy self-diffusivities in the core are greater than the diffusivity of the cations through the shell.
Date: May 22, 2008
Creator: Cabot, Andreu; Smith, Rachel; Yin, Yadong; Zheng, Haimei; Reinhard, Bjorn; Liu, Haitao et al.
System: The UNT Digital Library
ECLOUD in PS2, PS+, SPS+: AN UPDATE (open access)

ECLOUD in PS2, PS+, SPS+: AN UPDATE

We present an update of our results for the electron-cloud build-up for several upgrades proposed for the LHC injectors. Specifically, we have re-examined our published results for the ecloud heat load [1] from the perspective of numerical convergence of the simulations vis-a-vis the integration time step {Delta}t. We repeated most of the simulations with ever smaller values of {Delta}t until we reached stable results, indicating numerical convergence; this was achieved at 200-500 slices per bunch, depending on the particular case. In all cases examined, the simulated heat load decreases monotonically, until the limit is reached, as {Delta}t decreases in the range explored, hence the stable results are more favorable vis-a-vis the heat load than the previous ones. This is particularly true for a bunch spacing t{sub b} = 25 ns.
Date: May 22, 2007
Creator: Furman, M. A.
System: The UNT Digital Library
Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell Model (open access)

Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell Model

We propose an importance truncation scheme for the no-core shell model, which enables converged calculations for nuclei well beyond the p-shell. It is based on an a priori measure for the importance of individual basis states constructed by means of many-body perturbation theory. Only the physically relevant states of the no-core model space are considered, which leads to a dramatic reduction of the basis dimension. We analyze the validity and efficiency of this truncation scheme using different realistic nucleon-nucleon interactions and compare to conventional no-core shell model calculations for {sup 4}He and {sup 16}O. Then, we present the first converged calculations for the ground state of {sup 40}Ca within no-core model spaces including up to 16{h_bar}{Omega}-excitations using realistic low-momentum interactions. The scheme is universal and can be easily applied to other quantum many-body problems.
Date: May 22, 2007
Creator: Roth, R & Navratil, P
System: The UNT Digital Library
Particle Simulation of Coulomb Collisions: Comparing the Methods of Takizuka & Abe and Nanbu (open access)

Particle Simulation of Coulomb Collisions: Comparing the Methods of Takizuka & Abe and Nanbu

The interactions of charged particles in a plasma are in a plasma is governed by the long-range Coulomb collision. We compare two widely used Monte Carlo models for Coulomb collisions. One was developed by Takizuka and Abe in 1977, the other was developed by Nanbu in 1997. We perform deterministic and stochastic error analysis with respect to particle number and time step. The two models produce similar stochastic errors, but Nanbu's model gives smaller time step errors. Error comparisons between these two methods are presented.
Date: May 22, 2007
Creator: Wang, C.; Lin, T.; Caflisch, R.; Cohen, B. & Dimits, A.
System: The UNT Digital Library
Global Cooling: Effect of Urban Albedo on Global Temperature (open access)

Global Cooling: Effect of Urban Albedo on Global Temperature

In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). The roof and the pavement albedo can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60%. We estimate U.S. potential savings in excess of $1 billion (B) per year in net annual energy bills. Increasing albedo of urban surfaces can reduce the summertime urban temperature and improve the urban air quality. Increasing the urban albedo has the added benefit of reflecting more of the incoming global solar radiation and countering the effect of global warming. We estimate that increasing albedo of urban areas by 0.1 results in an increase of 3 x 10{sup -4} in Earth albedo. Using a simple global model, the change in air temperature in lowest 1.8 km of the atmosphere is estimated at 0.01K. Modelers predict a warming of about 3K in the next 60 years (0.05K/year). Change of 0.1 in urban albedo will result in 0.01K global cooling, a delay of {approx}0.2 years in …
Date: May 22, 2007
Creator: Akbari, Hashem; Menon, Surabi & Rosenfeld, Arthur
System: The UNT Digital Library
Enantioselective Intramolecular Hydroarylation of Alkenes via Directed C-H Bond Activation (open access)

Enantioselective Intramolecular Hydroarylation of Alkenes via Directed C-H Bond Activation

Highly enantioselective catalytic intramolecular ortho-alkylation of aromatic imines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using [RhCl(coe){sub 2}]{sub 2} and chiral phosphoramidite ligands. Cyclization of substrates containing 1,1- and 1,2-disubstituted as well as trisubstituted alkenes were achieved with enantioselectivities >90% ee for each substrate class. Cyclization of substrates with Z-alkene isomers proceeded much more efficiently than substrates with E-alkene isomers. This further enabled the highly stereoselective intramolecular alkylation of certain substrates containing Z/E-alkene mixtures via a Rh-catalyzed alkene isomerization with preferential cyclization of the Z-isomer.
Date: May 22, 2008
Creator: Harada, Hitoshi; Thalji, Reema; Bergman, Robert & Ellman, Jonathan
System: The UNT Digital Library
Software Design of a General Purpose Data Acquisition and Control Executive (open access)

Software Design of a General Purpose Data Acquisition and Control Executive

The software design of an executive which performs general purpose data acquisition, monitoring, and control is presented. The executive runs on a memory-based mini or micro-computer and communicates with a disk-based computer where data analysis and display are done. The executive design stresses reliability and versatility, and has yielded software which can provide control and monitoring for widely different hardware systems. Applications of this software on two major fusion energy experiments at Lawrence Livermore National Laboratory will be described.
Date: May 22, 1981
Creator: Labiak, W. G. & Minor, E. G.
System: The UNT Digital Library
A test of Newton's Law of Gravity using the BREN Tower, Nevada (open access)

A test of Newton's Law of Gravity using the BREN Tower, Nevada

We predicted gravity values on a tower by upward continuing an extensive set of surface data in order to test the 1/r/sup 2/ dependence of Newton's Law of Universal Gravitation. We measured gravity at 12 heights up to 454 m on a tower at the Nevada Test Site, and at 91 locations on the surface of the earth within 2.5 kilometers of the tower. These data have been combined with 60,000 surface gravity measurements within 300 kilometers of the tower and have been used to predict the gravitational field on the tower via a solution of Laplace's equation. A discrepancy between the observed gravity values and the prediction could suggest a breakdown of Newtonian Gravity, but we observe none. Our preliminary results are consistent with the Newtonian hypothesis to within 93 +- 95 ..mu..gals at the top of the tower, a result which conflicts with the previously reported 500 ..mu..gal non-Newtonian signal seen at 562 meters above the earth. 24 refs., 2 figs.
Date: May 22, 1989
Creator: Kasameyer, P.; Thomas, J.; Fackler, O.; Mugge, M.; Kammeraad, J.; Millett, M. et al.
System: The UNT Digital Library
The. tau. one-prong problem and recent measurements by the HRS (High Resolution Spectrometer) collaboration (open access)

The. tau. one-prong problem and recent measurements by the HRS (High Resolution Spectrometer) collaboration

We summarize recent measurements by the HRS collaboration of the topological branching fractions, the production cross section, the lifetime, and the rate into electrons of the {tau} lepton. An inconsistency with theoretical expectations persists at the level of two standard deviations. 11 refs., 2 figs., 4 tabs.
Date: May 22, 1989
Creator: Repond, J.
System: The UNT Digital Library
Integral decay-heat measurements and comparisons to ENDF/B--IV and V (open access)

Integral decay-heat measurements and comparisons to ENDF/B--IV and V

Results from recent integral decay-power experiments are presented and compared with summation calculations. The experiments include the decay power following thermal fission of /sup 233/U, /sup 235/U, and /sup 239/Pu. The summation calculations use ENDF/B-IV decay data and yields from Versions IV and V. Limited comparisons of experimental ..beta.. and ..gamma.. spectra with summation calculations using ENDF/B-IV are included. Generalized least-squares methods are applied to the recent /sup 235/U and /sup 239/Pu decay-power experiments and summation calculations to arrive at evaluated values and uncertainties. Results for /sup 235/U imply uncertainties less than 2% (1 sigma) for the ''infinite'' exposure case for all cooling times greater than 10 seconds. The uncertainties for /sup 239/Pu are larger. Accurate analytical representations of the decay power are presented for /sup 235/,/sup 238/U, and /sup 239/Pu for use in light-water reactors and as the nominal values in the new ANS 5.1 Draft Standard (1978). Comparisons of the nominal values with ENDF/B-IV and the 1973 ANS Draft Standard in current use are included. Gas content, important to decay-heat experiments, and absorption effects on decay power are reviewed. 37 figures, 8 tables.
Date: May 22, 1978
Creator: England, T. R.; Schenter, R. E. & Schmittroth, F.
System: The UNT Digital Library
Quality assurance in environmental monitoring at the Lawrence Livermore Laboratory (open access)

Quality assurance in environmental monitoring at the Lawrence Livermore Laboratory

The quality assurance program for environmental monitoring that has been developed at the Lawrence Livermore Laboratory (LLL) consists of procedure documentation, replicate field-sample analysis, and participation in intercomparison measurements. Sampling, analytical, data processing, and record keeping procedures are described. A replicate-sample collection schedule has been established for all media sampled at LLL. At present, blind-spiked samples are not utilized. Flow rates of air samplers are verified at monthly intervals using a portable, field calibration unit. Intercomparison measurements are made on samples supplied by the Quality Assurance Branch of the Environmental Protection Agency-Environmental Monitoring and Support Laboratory and the Department of Energy-Environmental Measurements Laboratory. Replicate sampling currently accounts for approximately 8% of both the total samples collected and the analyses performed. Including standard, in-house, quality-control checks, and the intercomparison measurements, it is estimated that during 1978 quality assurance will represent about 15% of the total environmental-monitoring effort at LLL.
Date: May 22, 1978
Creator: Lindeken, C. L.; White, J. H. & Silver, W. J.
System: The UNT Digital Library
['UNT professor offers expertise of Barnes collection', May 22, 1994] (open access)

['UNT professor offers expertise of Barnes collection', May 22, 1994]

An article from the newspaper the Denton Record-Chronicle written by Tim Leenerts. The piece discusses the lectures given by Dr. R. William McCarter on the Barnes collection, which was being shown at the Kimbell Art Museum in Fort Worth.
Date: May 22, 1994
Creator: Leenerts, Tim
System: The UNT Digital Library
Physics goals and signatures at the SSC (open access)

Physics goals and signatures at the SSC

The physics goals of the SSC are presented and the capabilities of the SSC to achieve them are assessed. New gauge bosons, electroweak symmetry breaking, supersymmetry, and quark substructure are the primary targets for particle physics research and the SSC is the most effective means to find them. 2 refs., 4 figs.
Date: May 22, 1990
Creator: Cahn, R.N.
System: The UNT Digital Library
Basic criticality relations for gas core design (open access)

Basic criticality relations for gas core design

Minimum critical fissile concentrations are calculated for U-233, U-235, Pu-239, and Am-242m mixed homogeneously with hydrogen at temperatures to 15,000K. Minimum critical masses of the same mixtures in a 1000 liter sphere are also calculated. It is shown that propellent efficiencies of a gas core fizzler engine using Am-242m as fuel would exceed those in a solid core engine as small as 1000L operating at 100 atmospheres pressure. The same would be true for Pu-239 and possibly U-233 at pressures of 1000 atm. or at larger volumes.
Date: May 22, 1992
Creator: Tanner, J. E.
System: The UNT Digital Library
Geobotanical Remote Sensing for Geothermal Exploration (open access)

Geobotanical Remote Sensing for Geothermal Exploration

This paper presents a plan for increasing the mapped resource base for geothermal exploration in the Western US. We plan to image large areas in the western US with recently developed high resolution hyperspectral geobotanical remote sensing tools. The proposed imaging systems have the ability to map visible faults, surface effluents, historical signatures, and discover subtle hidden faults and hidden thermal systems. Large regions can be imaged at reasonable costs. The technique of geobotanical remote sensing for geothermal signatures is based on recent successes in mapping faults and effluents the Long Valley Caldera and Mammoth Mountain in California.
Date: May 22, 2001
Creator: Pickles, W. L.; Kasameyer, P. W.; Martini, B. A.; Potts, D. C. & Silver, E. A.
System: The UNT Digital Library
Certification Testing and Demonstration of Insulated Pressure Vessels for Vehicular Hydrogen Storage (open access)

Certification Testing and Demonstration of Insulated Pressure Vessels for Vehicular Hydrogen Storage

Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen or ambient-temperature compressed hydrogen. This flexibility results in multiple advantages with respect to compressed hydrogen tanks or low-pressure liquid hydrogen tanks. Our work is directed at verifying that commercially available aluminum-lined, fiber-wrapped pressure vessels can be safely used to store liquid hydrogen. A series of tests have been conducted, and the results indicate that no significant vessel damage has resulted from cryogenic operation. Future activities include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for certification of insulated pressure vessels.
Date: May 22, 2002
Creator: Aceves, S. M.; Martinez-Frias, J. & Espinosa-Loza, F.
System: The UNT Digital Library
Heavy Quarkonium Production at LHC through W Boson Decays (open access)

Heavy Quarkonium Production at LHC through W Boson Decays

The production of the heavy (c{bar c})-quarkonium, (c{bar b})-quarkonium, and (b{bar b})-quarkonium states [({bar Q}') quarkonium for short], via the W{sup +} semi-inclusive decays, has been systematically studied within the framework of the nonrelativistic QCD. In addition to the two color-singlet S-wave states, we also discuss the production of the four color-singlet P-wave states |(Q{bar Q}')({sup 1}P{sub 1}){sub 1}> and |(Q{bar Q}')({sup 3}P{sub J}){sub 1}> [with J = (0,1,2)] together with the two color-octet components |(Q{bar Q}')({sup 1}S{sub 0}){sub 8}> and |(Q{bar Q}')({sup 3}S{sub 1}){sub 8}>. Improved trace technology is adopted to derive the simplified analytic expressions at the amplitude level, which shall be useful for dealing with the following cascade decay channels. At the LHC with the luminosity L {proportional_to} 10{sup 34} cm{sup -2} s{sup -1} and the center-of-mass energy {radical}S = 14 TeV, sizable heavy-quarkonium events can be produced through the W{sup +} boson decays; i.e., 2.57 x 10{sup 6} {eta}{sub c}, 2.65 x 10{sup 6} J/{Psi}, and 2.40 x 10{sup 6} P-wave charmonium events per year can be obtained, and 1.01 x 10{sup 5} B{sub c}, 9.11 x 10{sup 4} B*{sub c}, and 3.16 x 10{sup 4} P-wave (c{bar b})-quarkonium events per year can be obtained. Main …
Date: May 22, 2012
Creator: Liao, Qi-Li; U., /Chongqing; Wu, Xing-Gang; /SLAC, /Chongqing U.; Jiang, Jun; Yang, Zhi et al.
System: The UNT Digital Library
RADIOLOGICAL SURVEY STATION DEVELOPMENT FOR THE PIT DISASSEMBLY AND CONVERSION PROJECT (open access)

RADIOLOGICAL SURVEY STATION DEVELOPMENT FOR THE PIT DISASSEMBLY AND CONVERSION PROJECT

The Savannah River National Laboratory (SRNL) has developed prototype equipment to demonstrate remote surveying of Inner and Outer DOE Standard 3013 containers for fixed and transferable contamination in accordance with DOE Standard 3013 and 10 CFR 835 Appendix B. When fully developed the equipment will be part of a larger suite of equipment used to package material in accordance with DOE Standard 3013 at the Pit Disassembly and Conversion Project slated for installation at the Savannah River Site. The prototype system consists of a small six-axis industrial robot with an end effector consisting of a force sensor, vacuum gripper and a three fingered pneumatic gripper. The work cell also contains two alpha survey instruments, swipes, swipe dispenser, and other ancillary equipment. An external controller interfaces with the robot controller, survey instruments and other ancillary equipment to control the overall process. SRNL is developing automated equipment for the Pit Disassembly and Conversion (PDC) Project that is slated for the Savannah River Site (SRS). The equipment being developed is automated packaging equipment for packaging plutonium bearing materials in accordance with DOE-STD-3013-2004. The subject of this paper is the development of a prototype Radiological Survey Station (RSS). Other automated equipment being developed for …
Date: May 22, 2011
Creator: Dalmaso, M.; Gibbs, K. & Gregory, D.
System: The UNT Digital Library