An agent-based tool for infrastructure interdependency policy analysis. (open access)

An agent-based tool for infrastructure interdependency policy analysis.

Complex Adaptive Systems (CAS) can be applied to investigate complex infrastructure interdependencies such as those between the electric power and natural gas markets. These markets are undergoing fundamental transformations including major changes in electric generator fuel sources. Electric generators that use natural gas as a fuel source are rapidly gaining market share. These generators introduce direct interdependency between the electric power and natural gas markets. These interdependencies have been investigated using the emergent behavior of CAS model agents within the Spot Market Agent Research Tool Version 2.0 Plus Natural Gas (SMART II+).
Date: December 14, 2000
Creator: North, M. J.
System: The UNT Digital Library
Fundamental studies of ceramic/metal interfacial reactions at elevated temperatures. (open access)

Fundamental studies of ceramic/metal interfacial reactions at elevated temperatures.

This work characterizes the interfaces resulting from exposing oxide and non-oxide ceramic substrates to zirconium metal and stainless steel-zirconium containing alloys. The ceramic/metal systems together were preheated at about 600 C and then the temperatures were increased to the test maximum temperature, which exceeded 1800 C, in an atmosphere of high purity argon. Metal samples were placed onto ceramic substrates, and the system was heated to elevated temperatures past the melting point of the metallic specimen. After a short stay at the peak temperature, the system was cooled to room temperature and examined. The chemical changes across the interface and other microstructural developments were analyzed with energy dispersive spectroscopy (EDS). This paper reports on the condition of the interfaces in the different systems studied and describes possible mechanisms influencing the microstructure.
Date: December 14, 2000
Creator: McDeavitt, S. M.; Billings, G. W. & Indacochea, J. E.
System: The UNT Digital Library
Microstructural characterization of halite inclusion in a glass-bonded ceramic waste form. (open access)

Microstructural characterization of halite inclusion in a glass-bonded ceramic waste form.

A glass-bonded ceramic waste form is being developed to immobilize radioactively contaminated chloride waste salts generated during the conditioning of spent sodium-bonded nuclear fuel for disposal. The waste salt is first mixed with zeolite A to occlude the salt into cavities in the zeolite structure. The salt-loaded zeolite is then mixed with a borosilicate glass and consolidated by hot isostatic pressing. During this process, the zeolite converts to the mineral sodalite, which retains most of the waste salt, and small amounts of halite are generated. Halite inclusions have been observed within micron- to submicron-sized pores that form within the glass phase in the vicinity of the sodalite/glass interface. These inclusions are important because they may contain small amounts of radionuclide contaminants (eg {sup 135}Cs and {sup 129}I),and may affect the corrosion behavior of the waste form. Optical microscopy, scanning electron microscopy, and transmission electron microscopy were used to characterize the chemical nature and distribution of halite inclusions in the waste form.
Date: December 14, 2000
Creator: Luo, J. S. & Ebert, W. L.
System: The UNT Digital Library
SMART II : the spot market agent research tool version 2.0. (open access)

SMART II : the spot market agent research tool version 2.0.

Argonne National Laboratory (ANL) has worked closely with Western Area Power Administration (Western) over many years to develop a variety of electric power marketing and transmission system models that are being used for ongoing system planning and operation as well as analytic studies. Western markets and delivers reliable, cost-based electric power from 56 power plants to millions of consumers in 15 states. The Spot Market Agent Research Tool Version 2.0 (SMART II) is an investigative system that partially implements some important components of several existing ANL linear programming models, including some used by Western. SMART II does not implement a complete model of the Western utility system but it does include several salient features of this network for exploratory purposes. SMART II uses a Swarm agent-based framework. SMART II agents model bulk electric power transaction dynamics with recognition for marginal costs as well as transmission and generation constraints. SMART II uses a sparse graph of nodes and links to model the electric power spot market. The nodes represent power generators and consumers with distinct marginal decision curves and varying investment capital as well individual learning parameters. The links represent transmission lines with individual capacities taken from a range of central …
Date: December 14, 2000
Creator: North, M. J. N.
System: The UNT Digital Library
Use of Uniformly Distributed Concentrated Sunlight for Highly Accelerated Testing of Coatings (open access)

Use of Uniformly Distributed Concentrated Sunlight for Highly Accelerated Testing of Coatings

NREL has developed a new ultraviolet (UV) light concentrator that allows material samples to be subjected to uniform intensity levels of 50-100X solar UV at closely controlled sample exposure temperatures. In collaboration with industry, representative coating systems have been exposed without introducing unrealistic degradation mechanisms. Furthermore, correlations have been derived between these highly accelerated test conditions and results obtained at 1-2 suns. Such information is used to predict the degradation of materials in real-world applications. These predictions are compared with measured in-service performance losses to validate the approach. This allows valuable information to be obtained in greatly reduced timeframes, which can provide tremendous competitive advantage in the commercial marketplace.
Date: December 14, 2000
Creator: Jorgensen, G.; Bingham, C.; King, D.; Lewandowski, A.; Netter, J.; Terwilliger, K. et al.
System: The UNT Digital Library
Alpha-decay radiation damage study of a glass-bonded sodalite ceramic waste form. (open access)

Alpha-decay radiation damage study of a glass-bonded sodalite ceramic waste form.

None
Date: December 14, 2001
Creator: Frank, S. M.; Barber, T. L.; DiSanto, T.; Goff, K. M.; Johnson, S. G.; Jue, J.-F. et al.
System: The UNT Digital Library
SMART II+ : the spot market agent research tool version 2.0 plus natural gas. (open access)

SMART II+ : the spot market agent research tool version 2.0 plus natural gas.

Complex Adaptive Systems (CAS) can be applied to investigate complex infrastructure interdependencies including those between the electric power and natural gas markets. The electric power and natural gas markets are undergoing fundamental transformations. These transformations include major changes in electric generator fuel sources. Electric generators that use natural gas as a fuel source are rapidly gaining market share. Electric generators using natural gas introduce direct interdependency between the electric power and natural gas markets. The interdependencies between the electric power and natural gas markets introduced by these generators can be investigated using the emergent behavior of CAS model agents.
Date: December 14, 2000
Creator: North, M. J. N.
System: The UNT Digital Library
Stochastic algorithms for the analysis of numerical flame simulations (open access)

Stochastic algorithms for the analysis of numerical flame simulations

Recent progress in simulation methodologies and new, high-performance parallel architectures have made it is possible to perform detailed simulations of multidimensional combustion phenomena using comprehensive kinetics mechanisms. However, as simulation complexity increases, it becomes increasingly difficult to extract detailed quantitative information about the flame from the numerical solution, particularly regarding the details of chemical processes. In this paper we present a new diagnostic tool for analysis of numerical simulations of combustion phenomena. Our approach is based on recasting an Eulerian flow solution in a Lagrangian frame. Unlike a conventional Lagrangian viewpoint in which we follow the evolution of a volume of the fluid, we instead follow specific chemical elements, e.g., carbon, nitrogen, etc., as they move through the system. From this perspective an ''atom'' is part of some molecule that is transported through the domain by advection and diffusion. Reactions ca use the atom to shift from one species to another with the subsequent transport given by the movement of the new species. We represent these processes using a stochastic particle formulation that treats advection deterministically and models diffusion as a suitable random-walk process. Within this probabilistic framework, reactions can be viewed as a Markov process transforming molecule to molecule …
Date: December 14, 2001
Creator: Bell, John B.; Day, Marcus S.; Grcar, Joseph F. & Lijewski, Michael J.
System: The UNT Digital Library
Detailed modeling and laser-induced fluorescence imaging of nitric oxide in a NH(i)-seeded non-premixed methane/air flame (open access)

Detailed modeling and laser-induced fluorescence imaging of nitric oxide in a NH(i)-seeded non-premixed methane/air flame

In this paper we study the formation of NO in laminar, nitrogen diluted methane diffusion flames that are seeded with ammonia in the fuel stream. We have performed numerical simulations with detailed chemistry as well as laser-induced fluorescence imaging measurements for a range of ammonia injection rates. For comparison with the experimental data, synthetic LIF images are calculated based on the numerical data accounting for temperature and fluorescence quenching effects. We demonstrate good agreement between measurements and computations. The LIF corrections inferred from the simulation are then used to calculate absolute NO mole fractions from the measured signal.The NO formation in both doped and undoped flames occurs in the flame sheet. In the undoped flame, four different mechanisms including thermal and prompt NO appear to contribute to NO formation. As the NH3 seeding level increases, fuel-NO becomes the dominant mechanism and N2 shifts from being a net reactant to being a net product. Nitric oxide in the undoped flame as well as in the core region of the doped flames are underpredicted by the model; we attribute this mainly to inaccuracies in the NO recycling chemistry on the fuel-rich side of the flame sheet.
Date: December 14, 2001
Creator: Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Bessler, Wolfgang G.; Schulz, Christof; Glarborg, Peter et al.
System: The UNT Digital Library
Sum-frequency spectroscopic studies of ice interfaces (open access)

Sum-frequency spectroscopic studies of ice interfaces

None
Date: December 14, 2001
Creator: Wei, Xing; Miranda, Paulo B.; Zhang, Chun & Shen, Y.R.
System: The UNT Digital Library
Numerical simulation of premixed turbulent methane combustion (open access)

Numerical simulation of premixed turbulent methane combustion

In this paper we study the behavior of a premixed turbulent methane flame in three dimensions using numerical simulation. The simulations are performed using an adaptive time-dependent low Mach number combustion algorithm based on a second-order projection formulation that conserves both species mass and total enthalpy. The species and enthalpy equations are treated using an operator-split approach that incorporates stiff integration techniques for modeling detailed chemical kinetics. The methodology also incorporates a mixture model for differential diffusion. For the simulations presented here, methane chemistry and transport are modeled using the DRM-19 (19-species, 84-reaction) mechanism derived from the GRIMech-1.2 mechanism along with its associated thermodynamics and transport databases. We consider a lean flame with equivalence ratio 0.8 for two different levels of turbulent intensity. For each case we examine the basic structure of the flame including turbulent flame speed and flame surface area. The results indicate that flame wrinkling is the dominant factor leading to the increased turbulent flame speed. Joint probability distributions are computed to establish a correlation between heat release and curvature. We also investigate the effect of turbulent flame interaction on the flame chemistry. We identify specific flame intermediates that are sensitive to turbulence and explore various correlations …
Date: December 14, 2001
Creator: Bell, John B.; Day, Marcus S. & Grcar, Joseph F.
System: The UNT Digital Library
An nth-order, Gaussian Energy Distribution Model for Sintering (open access)

An nth-order, Gaussian Energy Distribution Model for Sintering

Although it is well known that the rate of sintering is governed by deceleratory kinetics, it is often difficult to fit power-law and nth-order reaction models over broad time-temperature ranges. This work shows that a phenomenological model combining a reaction order with an activation energy distribution can correlate surface area as a function of sintering time and temperature over a greater range of those variables. Qualitatively, the activation energy distribution accounts the dependence of free energy on particle size and material defects, while the reaction order accounts for geometric factors such as a distribution of diffusion lengths. The model is demonstrated for sintering of hydroxyapatite using data of Bailliez and Nzihou (Chem. Eng. J. 98 (2004), 141-152).
Date: December 14, 2004
Creator: Burnham, A K
System: The UNT Digital Library
Mechanical Property Data for Fiberboard (open access)

Mechanical Property Data for Fiberboard

The 9975 shipping package incorporates a cane fiberboard overpack for thermal insulation and impact resistance. Mechanical properties (tensile and compressive behavior) have been measured on cane fiberboard and a similar wood-based product following short-term conditioning in several temperature/humidity environments. Both products show similar trends, and vary in behavior with material orientation, temperature and humidity. A memory effect is also seen in that original strength values are only partially recovered following exposure to a degrading environment and return to ambient conditions.
Date: December 14, 2004
Creator: WILLIAM, daugherty
System: The UNT Digital Library
Molecular uranates - laser synthesis of uranium oxide anions in the gas phase (open access)

Molecular uranates - laser synthesis of uranium oxide anions in the gas phase

Laser ablation of solid UO{sub 3} or (NH{sub 4}){sub 2}U{sub 2}O{sub 7} yielded in the gas phase molecular uranium oxide anions with compositions ranging from [UO{sub n}]{sup -} (n = 2-4) to [U{sub 14}O{sub n}]{sup -} (n = 32-35), as detected by Fourier transform ion cyclotron resonance mass spectrometry. The cluster series [U{sub x}O{sub 3x}]{sup -} for x {le} 6 and various [U{sub x}O{sub 3x-y}]{sup -}, in which y increased with increasing x, could be identified. A few anions with H atoms were also present, and their abundance increased when hydrated UO{sub 3} was used in place of anhydrous UO{sub 3}. Collision-induced dissociation experiments with some of the lower m/z cluster anions supported extended structures in which neutral UO{sub 3} constitutes the building block. Cationic uranium oxide clusters [U{sub x}O{sub n}]{sup +} (x = 2-9; n = 3-24) could also be produced and are briefly discussed. Common trends in the O/U ratios for both negative and positive clusters could be unveiled.
Date: December 14, 2009
Creator: Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio & Gibson, John K
System: The UNT Digital Library
Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities (open access)

Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities

Published B and V fluxes from nearby Type Ia supernova are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B{sub max} and B{sub BV}. Their difference varies systematically with decline rate {Delta}m{sub 15} in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B{sub max} itself. A Hubble fit to the average of B{sub max} and B{sub BV} requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 {+-} 0.24, well below the coefficient R{sub B} {approx} 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B{sub max} and B{sub BV} exhibit mutual rms intrinsic variation equal to 0.074 {+-} 0.019 mag, of which at least an …
Date: December 14, 2005
Creator: Wang, Lifan; Strovink, Mark; Conley, Alexander; Goldhaber,Gerson; Kowalski, Marek; Perlmutter, Saul et al.
System: The UNT Digital Library
19-electron intermediates in the Ligand Substitution of CpW(CO)3with a Lewis Base (open access)

19-electron intermediates in the Ligand Substitution of CpW(CO)3with a Lewis Base

Odd electron species are important intermediates in organometallic chemistry, participating in a variety of catalytic and electron-transfer reactions which produce stable even-electron products. While electron deficient 17-electron (17e) radicals have been well characterized, the possible existence of short-lived 19-electron (19e) radicals has been a subject of continuing investigation. 19e radicals have been postulated as intermediates in the photochemical ligand substitution and disproportionation reactions of organometallic dimers containing a single metal-metal bond, yet the reactions of these intermediates on diffusion-limited time scales (ns-{micro}s) have never been directly observed. This study resolves the 19e dynamics in the ligand substitution of 17e radicals CpW(CO){sub 3}{sup {sm_bullet}} (Cp = C{sub 5}H{sub 5}) with the Lewis base P(OMe){sub 3}, providing the first complete description 19e reactivity.
Date: December 14, 2005
Creator: Cahoon, James F.; Kling, Matthias F.; Sawyer, Karma R.; Frei,Heinz & Harris, Charles B.
System: The UNT Digital Library
Status of GLAST, the Gamma-ray Large-area Space Telescope (open access)

Status of GLAST, the Gamma-ray Large-area Space Telescope

GLAST is a satellite-based observatory consisting of the Large-Area Telescope (LAT), a modular 4 x 4-tower pair-conversion telescope with a field-of-view greater than 2 steradians, capable of measuring gamma-ray energies in the range 20 MeV to 300 GeV, and the GLAST Burst Monitor (GBM), a set of NaI and BGO detectors covering 8 steradians and sensitive to photons with energies between 10 keV and 25 MeV, allowing for correlative observations of transient events. The observatory is currently being constructed and is scheduled to be launched in August 2007.
Date: December 14, 2005
Creator: Rochester, L.
System: The UNT Digital Library
Probing the Universal Randall-Sundrum Model at the ILC (open access)

Probing the Universal Randall-Sundrum Model at the ILC

The Randall-Sundrum model with all Standard Model (SM) fields in the bulk, including the Higgs, can be probed by precision measurements at the ILC. In particular, the couplings of the Higgs to the gauge bosons of the SM can be determined with high accuracy at the ILC. Here we examine the deviations in these couplings from their SM values within the framework of the Universal Randall-Sundrum Model (URSM) as well as the corresponding couplings of the first Higgs Kaluza-Klein excitation.
Date: December 14, 2005
Creator: Davoudiasl, H.; Lillie, B. & Rizzo, T. G.
System: The UNT Digital Library
FERMI@Elettra: A Seeded Harmonic Cascade FEL for EUV and Soft X-Rays (open access)

FERMI@Elettra: A Seeded Harmonic Cascade FEL for EUV and Soft X-Rays

We describe the machine layout and major performance parameters for the FERMI FEL project funded for construction at Sincrotrone Trieste, Italy, within the next five years. The project will be the first user facility based on seeded harmonic cascade FEL's, providing controlled, high peak-power pulses. With a high-brightness rf photocathode gun, and using the existing 1.2 GeV S-band linac, the facility will provide tunable output over a range from {approx}100 nm to {approx}10 nm, with pulse duration from 40 fs to {approx} 1ps, peak power {approx}GW, and with fully variable output polarization. Initially, two FEL cascades are planned; a single-stage harmonic generation to operate > 40 nm, and a two-stage cascade operating from {approx}40 nm to {approx}10 nm or shorter wavelength. The output is spatially and temporally coherent, with peak power in the GW range. Lasers provide modulation to the electron beam, as well as driving the photocathode and other systems, and the facility will integrate laser systems with the accelerator infrastructure, including a state-of-the-art optical timing system providing synchronization of rf signals, lasers, and x-ray pulses. Major systems and overall facility layout are described, and key performance parameters summarized.
Date: December 14, 2005
Creator: Bocchetta, C. J.; Bulfone, D.; Craievich, P.; Danailov, M. B.; D'Auria, G.; De Ninno, G. et al.
System: The UNT Digital Library
Measurement of Neutron Energy Spectra behind Shielding of a 120 GeV/c Hadron Facility (open access)

Measurement of Neutron Energy Spectra behind Shielding of a 120 GeV/c Hadron Facility

Neutron energy spectra were measured behind the lateral shield of the CERF (CERN-EU High Energy Reference Field) facility at CERN with a 120 GeV/c positive hadron beam (mainly a mixture of protons and pions) on a cylindrical copper target (7-cm diameter by 50-cm long). NE213 organic liquid scintillator (12.7-cm diameter by 12.7-cm long) was located at various longitudinal positions behind shields of 80- and 160-cm thick concrete and 40-cm thick iron. Neutron energy spectra in the energy range between 12 MeV and 380 MeV were obtained by unfolding the measured pulse height spectra with the detector response functions which have been experimentally verified in the neutron energy range up to 380 MeV in separate experiments. The corresponding MARS15 Monte Carlo simulations generally gave good agreements with the experimental energy spectra.
Date: December 14, 2005
Creator: Nakao, N.; Rokni, S. H.; Vincke, H.; Khater, Hesham; Prinz, A. A.; Taniguchi, S. et al.
System: The UNT Digital Library
Ion charge state fluctuations in vacuum arcs (open access)

Ion charge state fluctuations in vacuum arcs

Ion charge state distributions of cathodic vacuum arcs have been investigated using a modified time-of-flight method. Experiments have been done in double gate and burst gate mode, allowing us to study both systematic and stochastic changes of ion charge state distributions with a time resolution down to 100 ns. In the double gate method, two ion charge spectra are recorded with a well-defined time between measurements. The elements Mg, Bi, and Cu were selected for tests, representing metals of very different properties. For all elements it was found that large stochastic changes occur even at the limit of resolution. This is in agreement with fast changing arc properties observed elsewhere. Correlation of results for short times between measurements was found but it is argued that this is due to velocity mixing rather than due to cathode processes. The burst mode of time-of-flight measurements revealed the systematic time evolution of ion charge states within a single arc discharge, as opposed to previous measurements that relied on data averaged over many pulses. The technique shows the decay of the mean ion charge state as well as the level of material-dependent fluctuations.
Date: December 14, 2004
Creator: Anders, Andre; Fukuda, Kentaro & Yushkov, Georgy Yu
System: The UNT Digital Library
Recent Measurements of sin2beta at BaBar (open access)

Recent Measurements of sin2beta at BaBar

The angle {beta} is the most accurately measured quantity that determines the Unitarity Triangle. In this article I review the various measurements of this angle performed by the BaBar Collaboration, and discuss their implications in the search for new physics.
Date: December 14, 2005
Creator: Sciolla, Gabriella
System: The UNT Digital Library
Beam-Loading Compensation for Super B-Factories (open access)

Beam-Loading Compensation for Super B-Factories

Super B-factory designs under consideration expect to reach luminosities in the 10{sup 35}-10{sup 36} range. The dramatic luminosity increase relative to the existing B-factories is achieved, in part, by raising the beam currents stored in the electron and positron rings. For such machines to succeed it is necessary to consider in the RF system design not only the gap voltage and beam power, but also the beam loading effects. The main effects are the synchronous phase transients due to the uneven ring filling patterns and the longitudinal coupled-bunch instabilities driven by the fundamental impedance of the RF cavities. A systematic approach to predicting such effects and for optimizing the RF system design will be presented. Existing as well as promising new techniques for reducing the effects of heavy beam loading will be described and illustrated with examples from the PEP-II and the KEKB.
Date: December 14, 2005
Creator: Teytelman, D.
System: The UNT Digital Library
Nitrogen Doping and Thermal Stability in HfSiOxNy Studied by Photoemission and X-ray Absorption Spectroscopy (open access)

Nitrogen Doping and Thermal Stability in HfSiOxNy Studied by Photoemission and X-ray Absorption Spectroscopy

We have investigated nitrogen-doping effects into HfSiO{sub x} films on Si and their thermal stability using synchrotron-radiation photoemission and x-ray absorption spectroscopy. N 1s core-level photoemission and N K-edge absorption spectra have revealed that chemical-bonding states of N-Si{sub 3-x}O{sub x} and interstitial N{sub 2}-gas-like features are clearly observed in as-grown HfSiO{sub x}N{sub y} film and they decrease upon ultrahigh vacuum (UHV) annealing due to a thermal instability, which can be related to the device performance. Annealing-temperature dependence in Hf 4f and Si 2p photoemission spectra suggests that the Hf-silicidation temperature is effectively increased by nitrogen doping into the HfSiO{sub x} although the interfacial SiO{sub 2} layer is selectively reduced. No change in valence-band spectra upon UHV annealing suggests that crystallization of the HfSiO{sub x}N{sub y} films is also hindered by nitrogen doping into the HfSiO{sub x}.
Date: December 14, 2005
Creator: Toyoda, Satoshi; Okabayashi, Jun; Takahashi, Haruhiko; Oshima, Masaharu; U., /Tokyo; Lee, Dong-Ick et al.
System: The UNT Digital Library