Diagnostics for the Biased Electrode Experiment on NSTX (open access)

Diagnostics for the Biased Electrode Experiment on NSTX

A linear array of four small biased electrodes was installed in NSTX in an attempt to control the width of the scrape-off layer (SOL) by creating a strong local poloidal electric field. The set of electrodes were separated poloidally by a 1 cm gap between electrodes and were located slightly below the midplane of NSTX, 1 cm behind the RF antenna and oriented so that each electrode is facing approximately normal to the magnetic field. Each electrode can be independently biased to ±100 volts. Present power supplies limit the current on two electrodes to 30 amps the other two to 10 amps each. The effect of local biasing was measured with a set of Langmuir probes placed between the electrodes and another set extending radially outward from the electrodes, and also by the gas puff imaging diagnostic (GPI) located 1 m away along the magnetic field lines intersecting the electrodes. Two fast cameras were also aimed directly at the electrode array. The hardware and controls of the biasing experiment will be presented and the initial effects on local plasma parameters will be discussed.
Date: March 20, 2009
Creator: A.L. Roquemore, S.J. Zweben, C.E. Bush, R. Kaita, R. J. Marsalsa, and R.J. Maqueda
Object Type: Article
System: The UNT Digital Library
Chemometric Analysis of Nuclear Magnetic Resonance Spectroscopy Data (open access)

Chemometric Analysis of Nuclear Magnetic Resonance Spectroscopy Data

Chemometric analysis of nuclear magnetic resonance (NMR) spectroscopy has increased dramatically in recent years. A variety of different chemometric techniques have been applied to a wide range of problems in food, agricultural, medical, process and industrial systems. This article gives a brief review of chemometric analysis of NMR spectral data, including a summary of the types of mixtures and experiments analyzed with chemometric techniques. Common experimental problems encountered during the chemometric analysis of NMR data are also discussed.
Date: July 20, 2000
Creator: ALAM,TODD M. & ALAM,M. KATHLEEN
Object Type: Article
System: The UNT Digital Library
Land-Based Geologic Emplacement of Mercury Wastes (open access)

Land-Based Geologic Emplacement of Mercury Wastes

None
Date: July 20, 2000
Creator: ANDERSON,D. RICHARD
Object Type: Article
System: The UNT Digital Library
Conductivities and Seebeck Coefficients of Boron Carbides: ''Softening-Bipolaron'' Hopping (open access)

Conductivities and Seebeck Coefficients of Boron Carbides: ''Softening-Bipolaron'' Hopping

The most conspicuous feature of boron carbides' electronic transport properties is their having both high carrier densities and large Seebeck coefficients. The magnitudes and temperature dependencies of the Seebeck coefficients are consistent with large contributions from softening bipolarons: singlet bipolarons whose stabilization is significantly affected by their softening of local vibrations. Boron carbides' high carrier densities, small activation energies for hopping ({approx} 0.16 eV), and anomalously large Seebeck coefficients combine with their low, glass-like thermal conductivities to make them unexpectedly efficient high-temperature thermoelectrics.
Date: July 20, 2000
Creator: ASELAGE,TERRENCE L.; EMIN,DAVID JACOB & MCCREADY,STEVEN S.
Object Type: Article
System: The UNT Digital Library
Plasma-Enhanced SCR of NOx in Simulated Heavy-Duty Exhaust: Sulfur, Hydrocarbon, and Temperature Effects (open access)

Plasma-Enhanced SCR of NOx in Simulated Heavy-Duty Exhaust: Sulfur, Hydrocarbon, and Temperature Effects

None
Date: August 20, 2000
Creator: Aardahl, C. L.
Object Type: Article
System: The UNT Digital Library
An Extensible Business Process Approach for Managing Institutional Roles & Responsibilities ? A New Horizon for LLNL (open access)

An Extensible Business Process Approach for Managing Institutional Roles & Responsibilities ? A New Horizon for LLNL

None
Date: September 20, 2006
Creator: Aaron, C
Object Type: Article
System: The UNT Digital Library
Provably Secure Password-based Authentication in TLS (open access)

Provably Secure Password-based Authentication in TLS

In this paper, we show how to design an efficient, provably secure password-based authenticated key exchange mechanism specifically for the TLS (Transport Layer Security) protocol. The goal is to provide a technique that allows users to employ (short) passwords to securely identify themselves to servers. As our main contribution, we describe a new password-based technique for user authentication in TLS, called Simple Open Key Exchange (SOKE). Loosely speaking, the SOKE ciphersuites are unauthenticated Diffie-Hellman ciphersuites in which the client's Diffie-Hellman ephemeral public value is encrypted using a simple mask generation function. The mask is simply a constant value raised to the power of (a hash of) the password.The SOKE ciphersuites, in advantage over previous pass-word-based authentication ciphersuites for TLS, combine the following features. First, SOKE has formal security arguments; the proof of security based on the computational Diffie-Hellman assumption is in the random oracle model, and holds for concurrent executions and for arbitrarily large password dictionaries. Second, SOKE is computationally efficient; in particular, it only needs operations in a sufficiently large prime-order subgroup for its Diffie-Hellman computations (no safe primes). Third, SOKE provides good protocol flexibility because the user identity and password are only required once a SOKE ciphersuite has …
Date: December 20, 2005
Creator: Abdalla, Michel; Emmanuel, Bresson; Chevassut, Olivier; Moeller,Bodo & Pointcheval, David
Object Type: Article
System: The UNT Digital Library
Electric Reliability: Options for Electric Transmission Infrastructure Improvements (open access)

Electric Reliability: Options for Electric Transmission Infrastructure Improvements

The electric utility industry is inherently capital intensive. At the same time, the industry must operate under a changing and sometimes unpredictable regulatory system at both the federal and state level. The Energy Policy Act of 2005 has set in place government activities intended to relieve congestion on the transmission system. Several factors have contributed to the lack of new transmission capacity; these are outlined within this report. This report also discusses earlier pieces of energy legislation.
Date: September 20, 2006
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Electric Reliability: Options for Electric Transmission Infrastructure Improvements (open access)

Electric Reliability: Options for Electric Transmission Infrastructure Improvements

The electric utility industry is inherently capital intensive. At the same time, the industry must operate under a changing and sometimes unpredictable regulatory system at both the federal and state level. The Energy Policy Act of 2005 has set in place government activities intended to relieve congestion on the transmission system. Several factors have contributed to the lack of new transmission capacity; these are outlined within this report. This report also discusses earlier pieces of energy legislation.
Date: September 20, 2006
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Electric Reliability: Options for Electric Transmission Infrastructure Improvements (open access)

Electric Reliability: Options for Electric Transmission Infrastructure Improvements

The electric utility industry is inherently capital intensive. At the same time, the industry must operate under a changing and sometimes unpredictable regulatory system at both the federal and state level. The Energy Policy Act of 2005 has set in place government activities intended to relieve congestion on the transmission system. Several factors have contributed to the lack of new transmission capacity; these are outlined within this report. This report also discusses earlier pieces of energy legislation.
Date: September 20, 2006
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Government Activities to Protect the Electric Grid (open access)

Government Activities to Protect the Electric Grid

This report provides a description of initiatives within the Federal Energy Regulatory Commission and the Departments of Energy, Homeland Security, and Defense to protect the physical transmission infrastructure.
Date: October 20, 2004
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Government Activities to Protect the Electric Grid (open access)

Government Activities to Protect the Electric Grid

This report provides a description of initiatives within the Federal Energy Regulatory Commission and the Departments of Energy, Homeland Security, and Defense to protect the physical transmission infrastructure.
Date: December 20, 2004
Creator: Abel, Amy
Object Type: Report
System: The UNT Digital Library
Using the Antenna Effect as a Spectroscopic Tool; Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [EuIII(3,4,3-LI(1,2-HOPO))]- (open access)

Using the Antenna Effect as a Spectroscopic Tool; Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [EuIII(3,4,3-LI(1,2-HOPO))]-

While widely used in bioassays, the spectrofluorimetric method described here uses the antenna effect as a tool to probe the thermodynamic parameters of ligands that sensitize lanthanide luminescence. The Eu3+ coordination chemistry, solution thermodynamic stability and photophysical properties of the spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) are reported. The complex [EuIII(3,4,3-LI(1,2-HOPO))]- luminesces with a long lifetime (805 mu s) and a quantum yield of 7.0percent in aqueous solution, at pH 7.4. These remarkable optical properties were exploited to determine the high (and proton-independent) stability of the complex (log beta 110 = 20.2(2)) and to define the influence of the ligand scaffold on the stability and photophysical properties.
Date: November 20, 2009
Creator: Abergel, Rebecca J.; D'Aleo, Anthony; Ng Pak Leung, Clara; Shuh, David & Raymond, Kenneth
Object Type: Article
System: The UNT Digital Library
Influence of EGR on Component Durability (open access)

Influence of EGR on Component Durability

None
Date: August 20, 2000
Creator: Abi-Akar, Hind
Object Type: Article
System: The UNT Digital Library
Characterization of oxidation products on a ZrFe{sub 2}-type laves intermetallic exposed to 200{degree}C steam. (open access)

Characterization of oxidation products on a ZrFe{sub 2}-type laves intermetallic exposed to 200{degree}C steam.

The release of radioactive elements from the stainless steel-15 wt% zirconium (SS-15Zr) metal waste form will be governed by the corrosion behavior of ZrFe{sub 2}-type intermetallics phases present in the alloy. In this article, oxidation products that formed on a ZrFe{sub 2}-type intermetallic sample exposed to 200 C steam were characterized by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The data revealed two oxide layers on the sample surface: an outer crystalline iron-oxide layer and an inner amorphous zirconium-rich layer believed to be zirconium oxide. Thermodynamic considerations indicate that the zirconium-rich layer formed first. The iron-oxide layer appears to have resulted from the diffusion of iron through the zirconium-rich layer to the oxide-vapor interface.
Date: November 20, 2000
Creator: Abraham, D. P.; Dietz, N. & Finnegan, N.
Object Type: Article
System: The UNT Digital Library
Stochastic Boundary, Diffusion, Emittance Growth and Lifetime calculation for the RHIC e-lens (open access)

Stochastic Boundary, Diffusion, Emittance Growth and Lifetime calculation for the RHIC e-lens

To compensate the large tune shift and tune spread generated by the head-on beam-beam interactions in polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), a low energy electron beam with proper Gaussian transverse profiles was proposed to collide head-on with the proton beam. In this article, using a modified version of SixTrack [1], we investigate stability of the single particle in the presence of head-on beam-beam compensation. The Lyapunov exponent and action diffusion are calculated and compared between the cases without and with beam-beam compensation for two different working points and various bunch intensities. Using the action diffusion results the emittance growth rate and lifetime of the proton beam is also estimated for the different scenarios.
Date: January 20, 2009
Creator: Abreu,N.P.; Fischer, W.; Luo, Y. & Robert-Demolaize, G.
Object Type: Report
System: The UNT Digital Library
Spatial Analysis of Emissions Sources for HCCI Combustion at Low Loads Using a Multi-Zone Model (open access)

Spatial Analysis of Emissions Sources for HCCI Combustion at Low Loads Using a Multi-Zone Model

We have conducted a detailed numerical analysis of HCCI engine operation at low loads to investigate the sources of HC and CO emissions and the associated combustion inefficiencies. Engine performance and emissions are evaluated as fueling is reduced from typical HCCI conditions, with an equivalence ratio f = 0.26 to very low loads (f = 0.04). Calculations are conducted using a segregated multi-zone methodology and a detailed chemical kinetic mechanism for iso-octane with 859 chemical species. The computational results agree very well with recent experimental results. Pressure traces, heat release rates, burn duration, combustion efficiency and emissions of hydrocarbon, oxygenated hydrocarbon, and carbon monoxide are generally well predicted for the whole range of equivalence ratios. The computational model also shows where the pollutants originate within the combustion chamber, thereby explaining the changes in the HC and CO emissions as a function of equivalence ratio. The results of this paper contribute to the understanding of the high emission behavior of HCCI engines at low equivalence ratios and are important for characterizing this previously little explored, yet important range of operation.
Date: February 20, 2004
Creator: Aceves, S. M.; Flowers, D. L.; Espinosa-Loza, F.; Martinez-Frias, J.; Dec, J. E.; Sjoberg, M. et al.
Object Type: Article
System: The UNT Digital Library
Numerical and Experimental Studies of HCCI combustion (open access)

Numerical and Experimental Studies of HCCI combustion

None
Date: August 20, 2000
Creator: Aceves, Salvador M.
Object Type: Article
System: The UNT Digital Library
The Impact of humidity above stratiform clouds on indirect aerosol climate forcing (open access)

The Impact of humidity above stratiform clouds on indirect aerosol climate forcing

Some of the global warming effect of anthropogenic greenhouse gases is offset by increased solar reflection from clouds with smaller droplets that form on increased numbers of cloud condensation nuclei in polluted air. The global magnitude of the resulting indirect aerosol climate forcing is estimated to be comparable (and opposed) to the anthropogenic carbon dioxide forcing, but estimates are highly uncertain because of complexities in characterizing the physical process that determine global aerosol and cloud populations and their interactions. Beyond reflecting sunlight more effectively, smaller droplets are less efficient at producing precipitation, and decreased precipitation is expected to result in increased cloud water and cloud cover, further increasing the indirect forcing. Yet polluted marine boundary-layer clouds are not generally observed to hold more water. Here we use model simulations of stratocumulus clouds to show that suppression of precipitation from increased droplet concentrations leads to increased cloud water only when sufficient precipitation reaches the surface, a condition favored when the overlying air is moist. Otherwise, aerosol induced suppression of precipitation enhances entrainment of overlying dry air, thereby reducing cloud water and diminishing the indirect climate forcing.
Date: December 20, 2004
Creator: Ackerman, A. S.; Kirkpatrick, M. P.; Stevens, D. E. & Toon, O. B.
Object Type: Article
System: The UNT Digital Library
Education Vouchers: Constitutional Issues and Cases (open access)

Education Vouchers: Constitutional Issues and Cases

This report details the constitutional standards that currently apply to indirect school aid programs and summarizes all of the pertinent Supreme Court decisions, with particular attention to Zelman. It also summarizes the pending case of Davey v. Locke and other recent and ongoing state and lower federal court cases concerning vouchers.
Date: May 20, 2003
Creator: Ackerman, David M.
Object Type: Report
System: The UNT Digital Library
Public Aid and Faith-Based Organizations (Charitable Choice): Background and Selected Legal Issues (open access)

Public Aid and Faith-Based Organizations (Charitable Choice): Background and Selected Legal Issues

None
Date: February 20, 2002
Creator: Ackerman, David M.
Object Type: Report
System: The UNT Digital Library
Search for b0(s) --> mu+ mu- and b0(d) --> mu+ mu- decays in p anti-p collisions at s**(1/2) = 1.96 tev (open access)

Search for b0(s) --> mu+ mu- and b0(d) --> mu+ mu- decays in p anti-p collisions at s**(1/2) = 1.96 tev

The authors report on a search for B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays in p{bar p} collisions at {radical}s = 1.96 TeV using 171 pb{sup -1} of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the Standard Model. One event survives all the selection requirements, consistent with the background expectation. They derive branching ratio limits of {Beta}(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 5.8 x 10{sup -7} and {Beta}(B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 1.5 x 10{sup -7} at 90% confidence level.
Date: March 20, 2004
Creator: Acosta, D.
Object Type: Report
System: The UNT Digital Library
Rapidity and centrality dependence of proton and anti-proton production from 197Au+197Au collisions at {radical}(s{sub NN}) = 130 GeV (open access)

Rapidity and centrality dependence of proton and anti-proton production from 197Au+197Au collisions at {radical}(s{sub NN}) = 130 GeV

We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y| < 0.5 and 0.35 < p{sub t} < 1.00 GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y| < 0.5. Comparisons of our data with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.
Date: June 20, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type: Article
System: The UNT Digital Library