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Energy generation in convective shells of low mass, low metallicity stars (open access)

Energy generation in convective shells of low mass, low metallicity stars

We report on the non-negligible energy generation from the {sup 13}C neutron source and neutron capture reactions in low mass, low metallicity AGB stars. About 10{sup 4} L{sub {circle dot}} are generated within the thermal pulse convective shell by the combination of the {sup 13}C({alpha}, n){sup 16}O rate and the sum of the Y(Z,A)(n,{gamma})Y(Z,A + 1) reactions and beta decays. The inclusion of this energy source in an AGB thermal pulse evolution is shown to alter the evolution of the convective shell boundaries, and, hence, how the {sup 13}C is ingested into the convective shell. Also, the duration of the pulse itself is reduced by the additional energy input. The nucleosynthetic consequences are discussed for these evolutionary changes. 17 refs., 5 figs.
Date: November 10, 1989
Creator: Bazan, G. (Illinois Univ., Urbana, IL (USA). Dept. of Astronomy) & Lattanzio, J.C. (Lawrence Livermore National Lab., CA (USA))
System: The UNT Digital Library
Doppler-shifted resonance absorption by hot electrons (open access)

Doppler-shifted resonance absorption by hot electrons

When the large Doppler shifts of hot-electron-ring ECRH absorption are taken into account, the spatial location of the bulk of the energy absorption can be significantly shifted from the cold-plasma resonance region. The high parallel velocity electrons absorb most of the wave energy, thereby shielding the bulk of the electron distribution from the heating source. A simple one-dimensional model of this process has been formulated, based on a right-hand circularly polarized wave which is incident from the high-field side in the parallel direction. In this model, less than 1% of the electrons absorb more than 90% of the wave energy for the case of 30-keV maximum parallel electron energy, 28-GHz microwaves, and a 1-m magnetic field scale length. The effect should be included in power balance models and Fokker-Planck velocity distribution calculations. The Doppler shift also appears for a variety of ray-tracing code calculations in the MFTF-B thermal barrier region.
Date: November 10, 1981
Creator: Shearer, J.W.
System: The UNT Digital Library
A review of the properties of Nb3Sn and their variation with A15composition, morphology and strain state (open access)

A review of the properties of Nb3Sn and their variation with A15composition, morphology and strain state

None
Date: November 10, 2006
Creator: Godeke, Arno
System: The UNT Digital Library
NOVEL CATALYTIC EFFECTS OF FULLERENE FOR LIBH4 HYDROGEN UPTAKE AND RELEASE (open access)

NOVEL CATALYTIC EFFECTS OF FULLERENE FOR LIBH4 HYDROGEN UPTAKE AND RELEASE

Our recent novel finding, involving a synergistic experiment and first-principles theory, shows that carbon nanostructures can be used as catalysts for hydrogen uptake/release in aluminum based complex metal hydrides (sodium alanate) and also provides an unambiguous understanding of how the catalysts work. Here we show that the same concepts can be applied to boron based complex hydride such as lithium borohydride, LiBH{sub 4}. Taking into account electronegativity and curvature effect a fullerene-LiBH{sub 4} composite demonstrates catalytic properties with not only lowered hydrogen desorption temperatures, but regenerative rehydriding at relatively lower temperature of 350 C. This catalytic effect likely originates from interfering with the charge transfer from Li to the BH4 moiety, resulting in an ionic bond between Li{sup +} and BH{sub 4}{sup -}, and a covalent bond between B and H. Interaction of LiBH{sub 4} with an electronegative substrate such as carbon fullerene affects the ability of Li to donate its charge to BH{sub 4}, consequently weakening the B-H bond and causing hydrogen to desorb at lower temperatures as well as facilitating the absorption of H{sub 2} to reverse the dehydrogenation reaction. Degradation of cycling capacity is observed and is attributed to forming irreversible intermediates or diboranes.
Date: November 10, 2008
Creator: Wellons, M; Ragaiy Zidan, R & Polly Perseth, P
System: The UNT Digital Library
The Effect of Extending the Length of the Coupling Coils in a MuonIonization Cooling Channel (open access)

The Effect of Extending the Length of the Coupling Coils in a MuonIonization Cooling Channel

RF cavities are used to re-accelerate muons that have beencooled by absorbers that are in low beta regions of a muon ionizationcooling channel. A superconducting coupling magnet (or magnets) arearound or among the RF cavities of a muon ionization-cooling channel. Thefield from the magnet guides the muons so that they are kept within theiris of the RF cavities that are used to accelerate the muons. Thisreport compares the use of a single short coupling magnet with anextended coupling magnet that has one or more superconducting coils aspart of a muon-cooling channel of the same design as the muon ionizationcooling experiment (MICE). Whether the superconducting magnet is shortand thick or long and this affects the magnet stored energy and the peakfield in the winding. The magnetic field distribution also affects is themuon beam optics in the cooling cell of a muon coolingchannel.
Date: November 10, 2007
Creator: Green, Michael A.
System: The UNT Digital Library
Detailed Chemical Kinetic Modeling of Cyclohexane Oxidation (open access)

Detailed Chemical Kinetic Modeling of Cyclohexane Oxidation

A detailed chemical kinetic mechanism has been developed and used to study the oxidation of cyclohexane at both low and high temperatures. Reaction rate constant rules are developed for the low temperature combustion of cyclohexane. These rules can be used for in chemical kinetic mechanisms for other cycloalkanes. Since cyclohexane produces only one type of cyclohexyl radical, much of the low temperature chemistry of cyclohexane is described in terms of one potential energy diagram showing the reaction of cyclohexyl radical + O{sub 2} through five, six and seven membered ring transition states. The direct elimination of cyclohexene and HO{sub 2} from RO{sub 2} is included in the treatment using a modified rate constant of Cavallotti et al. Published and unpublished data from the Lille rapid compression machine, as well as jet-stirred reactor data are used to validate the mechanism. The effect of heat loss is included in the simulations, an improvement on previous studies on cyclohexane. Calculations indicated that the production of 1,2-epoxycyclohexane observed in the experiments can not be simulated based on the current understanding of low temperature chemistry. Possible 'alternative' H-atom isomerizations leading to different products from the parent O{sub 2}QOOH radical were included in the low temperature …
Date: November 10, 2006
Creator: Silke, E J; Pitz, W J; Westbrook, C K & Ribaucour, M
System: The UNT Digital Library
ATF experimental plans (open access)

ATF experimental plans

The Program is directed at better understanding and improvement of toroidal confinement through studies of: ..beta.. limit; 2nd stability region; low nu* transport; role of E-field; effects of magnetic configurations (externally controlled) on ..beta.. and transport; and issues critical to steady state operation (energy and particle handling, ICRF).
Date: November 10, 1987
Creator: Murakami, M.
System: The UNT Digital Library
Design considerations for a combined synchrotron-light source and heavy-ion storage ring Atomic Physics Facility (open access)

Design considerations for a combined synchrotron-light source and heavy-ion storage ring Atomic Physics Facility

An Atomic Physics Facility (APF) based on the combination of photons produced by a synchrotron light source with heavy ions in a storage ring will open the way to the study of ionic states of almost all elements. The design considerations for such a facility are discussed in terms of the use of synchrotron radiation for photoexcitation and ionization experiments. Design considerations for an APF are given in terms of the accelerator facilities presently available at BNL which include the National Synchrotron Light Source and Tandem Van de Graaff Laboratory. The results show that the concept is valid and therefore that implementation would result in entirely new capabilities for the study of multiply-ionized atoms.
Date: November 10, 1986
Creator: Jones, K. W.; Johnson, B. M.; Meron, M.; Lee, Y. Y.; Thieberger, P. & Thomlinson, W. C.
System: The UNT Digital Library
A streamlined method for chiral fermions on the lattice (open access)

A streamlined method for chiral fermions on the lattice

We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.
Date: November 10, 1992
Creator: Bodwin, G.T. (Argonne National Lab., IL (United States). High Energy Physics Div.) & Kovacs, E.V. (Fermi National Accelerator Lab., Batavia, IL (United States))
System: The UNT Digital Library
[Tyler Morning Telegraph 'Women's News', November 10, 1989] (open access)

[Tyler Morning Telegraph 'Women's News', November 10, 1989]

Photocopy of an article from the 'Women's News' section of the Tyler Morning Telegraph about Georgia Blaydes' art-inclusive curriculum. At the end it includes a mention of the grant from the Getty Center for Education in the Arts to UNT for the NTIEVA program.
Date: November 10, 1989
Creator: Tyler Morning Telegraph
System: The UNT Digital Library
Electric Field Enhanced Photoluminescence of CdTe Quantum Dots Encapsulated in Poly (N-Isopropylacrylamide) Nano-Spheres (open access)

Electric Field Enhanced Photoluminescence of CdTe Quantum Dots Encapsulated in Poly (N-Isopropylacrylamide) Nano-Spheres

This article shows an electric field dependent collapse of the poly(N-isopropylacramide) nanospheres and employs the electric field dependence as a means to adjust the photoluminescence process of the quantum dots in a hybrid material.
Date: November 10, 2008
Creator: Garner, Brett W.; Cai, Tong; Hu, Zhibing & Neogi, Arup
System: The UNT Digital Library
Response of rocks to large stresses. [Model for predicting response of ductile and brittle rocks to impact loading] (open access)

Response of rocks to large stresses. [Model for predicting response of ductile and brittle rocks to impact loading]

To predict the dimensions and characteristics of impact- and explosion-induced craters, one must know the equation of state of the rocks in which the crater is formed. Recent experimental data shed light upon inelastic processes that influence the stress/strain behavior of rocks. We examine these data with a view to developing models that could be used in predicting cratering phenomena. New data is presented on the volume behavior of two dissimilar rocks subjected to tensile stresses.
Date: November 10, 1976
Creator: Schock, R. N.
System: The UNT Digital Library
C.A.S.I.S. Workshop 2003 Abstract Proceedings (open access)

C.A.S.I.S. Workshop 2003 Abstract Proceedings

Thirty five years ago, while in the neutron cross section group led by Robert Howerton at LLNL, the concept of reconstructing a three dimensional spatial distribution from its projections onto two dimensional planes was tackled by some of us using three now well known methods: simple back projection, Fourier projection theorem methods and iterative least squares algebraic reconstruction. The method of iterative least squares reconstruction was implemented on patient data in the early 1970s using photons from radionuclides detected by the Anger Camera. The method useful for computed tomography was modified to include the attenuation of the photons from an unknown source through an unknown attenuation distribution (a problem thought to be intractable until 1974). These methods along with a multitude of other methods developed by my small group of Ronald Huesman, Grant Gullberg, William Greenberg and Stephen Derenzo were prepared as a library with examples in FORTRAN, RECLBL. Those codes were found useful for computed tomography, geophysical problems and plasma confinement research topics in addition to their use in Nuclear Medicine. The codes were used even in the early days of magnetic resonance imaging when back projection of filtered projection data were used before the incorporation of phase encoding …
Date: November 10, 2003
Creator: Azevedo, S
System: The UNT Digital Library
A CHRONOLOGICAL FRAMEWORK FOR THE HOLOCENE VEGETATIONAL HISTORY OF CENTRAL MINNESOTA: THE STEEL LAKE POLLEN RECORD (open access)

A CHRONOLOGICAL FRAMEWORK FOR THE HOLOCENE VEGETATIONAL HISTORY OF CENTRAL MINNESOTA: THE STEEL LAKE POLLEN RECORD

Paleorecords from Minnesota and adjacent areas have often been used to evaluate large-scale climatic processes in the mid-continent of North America. However, most of these records are compromised by chronological flaws, making problematic any comparisons with climatic interpretations based on other records (e.g., GISP2 in Greenland). We report here a high-resolution pollen record with a secure chronology constrained by 26 {sup 14}C dates on terrestrial macrofossils from Steel Lake, central Minnesota. About 11,200 years ago (calibrated yr BP) the late-glacial Picea forest near Steel Lake was succeeded abruptly by Pinus banksiana and/or resinosa. The Pinus forest began to open 9.4 ka cal BP with the expansion of prairie taxa, and a pine parkland or savanna prevailed until about 8 ka cal BP, when Quercus replaced Pinus to become the dominant tree in the prairie areas for 4500 years. The close chronological control permits the correlation of key vegetational changes with those at other reliably dated sites in the eastern Dakotas and in Minnesota, suggesting that the abrupt decline of the spruce forest was time-transgressive from southwest to northeast during 2000 years, and that the development of prairie was time-transgressive in the same direction over 2600 years. Correlation of key pollen …
Date: November 10, 2003
Creator: Wright, H E; Stefanova, I; Tian, J; Brown, T A & Hu, F S
System: The UNT Digital Library
Effect on scattering of complex morphology of DKDP bulk damage sites (open access)

Effect on scattering of complex morphology of DKDP bulk damage sites

Bulk damage sites in frequency conversion crystals scatter and/or absorb laser light leading to interference and downstream intensification .We find that laser induced bulk damage sites in DKDP exhibit a 'shell' of structurally and/or chemically modified material surrounding a central core as indicated by SEM and optical micrographs and micro Raman spectral maps. We hypothesize that the modified material has been shock wave densified and estimate the amount of densification and its effect on scattering. A simple model indicates that densification of several percent is likely and that the scattering cross section may be larger than the geometric area of the inner core by an order of magnitude.
Date: November 10, 2004
Creator: Carr, C W; Feit, M D; Muyco, J J & Rubenchik, A M
System: The UNT Digital Library
Correlation of Laser-Induced Damage to Phase Objects in Bulk Fused Silica (open access)

Correlation of Laser-Induced Damage to Phase Objects in Bulk Fused Silica

The Optical Sciences Laser (OSL) Upgrade facility, described in last year's proceedings, is a kJ-class, large aperture (100cm{sup 2}) laser system that can accommodate prototype optical components for large-scale inertial confinement fusion lasers. High-energy operation of such lasers is often limited by damage to the optical components. Recent experiments on the OSL Upgrade facility using fused silica components at 4 J/cm{sup 2} (351-nm, 3-ns) have created output surface and bulk damage sites that have been correlated to phase objects in the bulk of the material. Optical Path Difference (OPD) measurements of the phase defects indicate the probability of laser-induced damage is strongly dependent on OPD.
Date: November 10, 2004
Creator: Nostrand, M. C.; Cerjan, C. J.; Johnson, M. A.; Suratwala, T. I.; Weiland, T. L.; Sell, W. D. et al.
System: The UNT Digital Library
"Burst-like" Characteristics of the delta/alpha-prime Phase Transformation in Pu-Ga Alloys (open access)

"Burst-like" Characteristics of the delta/alpha-prime Phase Transformation in Pu-Ga Alloys

The {delta} to {alpha}' phase transformation in Pu-Ga alloys is intriguing for both scientific and technological reasons. On cooling, the ductile fcc d-phase transforms martensitically to the brittle monoclinic {alpha}'-phase at approximately -120 C (depending on composition). This exothermic transformation involves a 20% volume contraction and a significant increase in resistivity. The reversion of {alpha}' to {delta} involves a large temperature hysteresis beginning just above room temperature. In an attempt to better understand the underlying thermodynamics and kinetics responsible for these unusual features, we examined the {delta}/{alpha}' transformations in a 0.6 wt% Pu-Ga alloy using differential scanning calorimetry (DSC) and resistometry. Both techniques indicate that the martensite start temperature is -120 C and the austenite start temperature is 35 C. The heat of transformation is approximately 3 kJ/mole. During the {alpha}' {yields} {delta} reversion, ''spikes'' and ''steps'' are observed in DSC and resistometry scans, respectively. These spikes and steps are periodic, and their periodicity with respect to temperature does not vary with heating rate. With an appropriate annealing cycle, including a ''rest'' at room temperature, these spikes and steps can be reproduced through many thermal cycles of a single sample.
Date: November 10, 2003
Creator: Blobaum, K; Krenn, C; Haslam, J; Wall, M & Schwartz, A
System: The UNT Digital Library
Data Access Performance Through Parallelization and Vectored Access: Some Results (open access)

Data Access Performance Through Parallelization and Vectored Access: Some Results

High Energy Physics data processing and analysis applications typically deal with the problem of accessing and processing data at high speed. Recent studies, development and test work have shown that the latencies due to data access can often be hidden by parallelizing them with the data processing, thus giving the ability to have applications which process remote data with a high level of efficiency. Techniques and algorithms able to reach this result have been implemented in the client side of the Scalla/xrootd system, and in this contribution we describe the results of some tests done in order to compare their performance and characteristics. These techniques, if used together with multiple streams data access, can also be effective in allowing to efficiently and transparently deal with data repositories accessible via a Wide Area Network.
Date: November 10, 2011
Creator: Furano, Fabrizio & Hanushevsky, Andrew
System: The UNT Digital Library
Extra Dimensions: 3D and Time in PDF Documentation (open access)

Extra Dimensions: 3D and Time in PDF Documentation

High energy physics is replete with multi-dimensional information which is often poorly represented by the two dimensions of presentation slides and print media. Past efforts to disseminate such information to a wider audience have failed for a number of reasons, including a lack of standards which are easy to implement and have broad support. Adobe's Portable Document Format (PDF) has in recent years become the de facto standard for secure, dependable electronic information exchange. It has done so by creating an open format, providing support for multiple platforms and being reliable and extensible. By providing support for the ECMA standard Universal 3D (U3D) file format in its free Adobe Reader software, Adobe has made it easy to distribute and interact with 3D content. By providing support for scripting and animation, temporal data can also be easily distributed to a wide audience. In this talk, we present examples of HEP applications which take advantage of this functionality. We demonstrate how 3D detector elements can be documented, using either CAD drawings or other sources such as GEANT visualizations as input. Using this technique, higher dimensional data, such as LEGO plots or time-dependent information can be included in PDF files. In principle, a …
Date: November 10, 2011
Creator: Graf, Norman A.
System: The UNT Digital Library
Lepton Universality, |V(Us)| and Search for Second Class Current in Tau Decays (open access)

Lepton Universality, |V(Us)| and Search for Second Class Current in Tau Decays

Several hundred million {tau} decays have been studied with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Recent results on Charged Current Lepton Universality and two independent measurements of |V{sub us}| using {tau}{sup -} {yields} e{sup -}{bar {nu}}{sub e}{nu}{sub {tau}}, {mu}{sup -}{bar {nu}}{sub {mu}}{nu}{sub {tau}}, {pi}{sup -}{nu}{sub {tau}}, K{sup -} {nu}{sub {tau}} and K{sub S}{sup 0}{pi}{sup -} {nu}{sub {tau}} decays, and a search for Second Class Current in {tau}{sup -} {yields} {pi}{sup -} {omega}{nu}{sub {tau}} decays are presented, where the charge conjugate decay modes are also implied.
Date: November 10, 2011
Creator: Banerjee, Swagato
System: The UNT Digital Library
Statistical Analysis of Baseline Load Models for Non-Residential Buildings (open access)

Statistical Analysis of Baseline Load Models for Non-Residential Buildings

Policymakers are encouraging the development of standardized and consistent methods to quantify the electric load impacts of demand response programs. For load impacts, an essential part of the analysis is the estimation of the baseline load profile. In this paper, we present a statistical evaluation of the performance of several different models used to calculate baselines for commercial buildings participating in a demand response program in California. In our approach, we use the model to estimate baseline loads for a large set of proxy event days for which the actual load data are also available. Measures of the accuracy and bias of different models, the importance of weather effects, and the effect of applying morning adjustment factors (which use data from the day of the event to adjust the estimated baseline) are presented. Our results suggest that (1) the accuracy of baseline load models can be improved substantially by applying a morning adjustment, (2) the characterization of building loads by variability and weather sensitivity is a useful indicator of which types of baseline models will perform well, and (3) models that incorporate temperature either improve the accuracy of the model fit or do not change it.
Date: November 10, 2008
Creator: Coughlin, Katie; Piette, Mary Ann; Goldman, Charles & Kiliccote, Sila
System: The UNT Digital Library
Computer networks in the physical sciences (open access)

Computer networks in the physical sciences

None
Date: November 10, 1976
Creator: Austin, D. M.
System: The UNT Digital Library
BWR Anticipated Transients Without Scram Leading to Instability (open access)

BWR Anticipated Transients Without Scram Leading to Instability

Anticipated transients without scram (ATWS) in aboiling water reactor (BWR) were simulated in order to understand reactor response and determine the effectiveness of automatic and operator actions to mitigate this beyond-design-basis accident. The events of interest herein are initiated by a turbine trip when the reactor is operating in the expanded operating domainMELLLA+ [maximum extended load line limit plus]. In these events the reactor may initially be at up to 120% of the original licensed thermal power (OLTP) and at flow rates as low as 80% of rated.For these (and similar) ATWS events the concern isthat when the reactor power decreases in response to a dual recirculation pump trip, the core will become unstable and large amplitude oscillations will begin. The occurrence of these power oscillations, if left unmitigated, may result in fuel damage, and the amplitude of the poweroscillations may hamper the effectiveness of the injection of dissolved neutron absorber through the standby liquid control system (SLCS).
Date: November 10, 2013
Creator: Cheng, Lap-Yan; Baek, Joo-Seok; Cuadra, Arantxa; Aronson, Arnold; Diamond, David & Yarsky, Peter
System: The UNT Digital Library
Minimal Simple de Sitter Solutions (open access)

Minimal Simple de Sitter Solutions

None
Date: November 10, 2011
Creator: Haque, Sheikh Shajidul; Shiu, Gary; Underwood, Bret & Van Riet, Thomas
System: The UNT Digital Library