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open access

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

Description: The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large vo… more
Date: June 25, 2008
Creator: Burt, Scott R & Burt, Scott R.
Partner: UNT Libraries Government Documents Department
open access

Nuclear Decay Schemes of Some of the Isotopes of Tantalum (Master's Thesis)

Description: This report discusses a nuclear spectroscopic study of the radiations resulting from the electron capture decay of Ta-176, Ta-177, and Ta-178, analyzing data of nuclear decay schemes.
Date: January 25, 1956
Creator: Felber, Frank Frederick, Jr.
Partner: UNT Libraries Government Documents Department
open access

Optimization of Operating Parameters for Minimum Mechanical Specific Energy in Drilling

Description: Efficiency in drilling is measured by Mechanical Specific Energy (MSE). MSE is the measure of the amount of energy input required to remove a unit volume of rock, expressed in units of energy input divided by volume removed. It can be expressed mathematically in terms of controllable parameters; Weight on Bit, Torque, Rate of Penetration, and RPM. It is well documented that minimizing MSE by optimizing controllable factors results in maximum Rate of Penetration. Current methods for computing MS… more
Date: May 25, 2011
Creator: Hamrick, Todd
Partner: UNT Libraries Government Documents Department
open access

Superconducting High Resolution Fast-Neutron Spectrometers

Description: Superconducting high resolution fast-neutron calorimetric spectrometers based on {sup 6}LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, {alpha}) reactions with fast neutrons in {sup 6}Li and {sup 10}B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition re… more
Date: May 25, 2006
Creator: Hau, I D
Partner: UNT Libraries Government Documents Department
open access

Measurement of the single top production cross section in proton-antiproton collisions at 1.96 TeV

Description: This thesis describes a search for singly produced top quarks via an electroweak vertex in head-on proton-antiproton collisions at a center of mass energy of √s = 1.96 TeV. The analysis uses a total of 2.3 fb<sup>-1</sup> of data collected with the D0 detector at Fermilab, corresponding to two different run periods of the Tevatron collider. Two channels contribute to single top quark production at the Tevatron, the s-channel and the t-channel. In the s-channel, a virtual W boson is produced fro… more
Date: March 25, 2010
Creator: Tanasijczuk, Andres Jorge
Partner: UNT Libraries Government Documents Department
open access

The VRFurnace: A Virtual Reality Application for Energy System Data Analysis

Description: The VRFurnace is a unique VR application designed to analyze a complete coal-combustion CFD model of a power plant furnace. Although other applications have been created that analyze furnace performance, no other has included the added complications of particle tracking and the reactions associated with coal combustion. Currently the VRFurnace is a versatile analysis tool. Data translators have been written to allow data from most of the major commercial CFD software packages as well as standar… more
Date: June 25, 2001
Creator: Johnson, Peter Eric
Partner: UNT Libraries Government Documents Department
open access

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

Description: Thermodynamics has been studied systematically for the high temperature cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4-{delta}}, La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H {parallel} c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensi… more
Date: June 25, 2001
Creator: Finnemore, Douglas K.
Partner: UNT Libraries Government Documents Department
open access

Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

Description: Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, the author introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-thro… more
Date: May 25, 2001
Creator: Su, Hui
Partner: UNT Libraries Government Documents Department
open access

Evaluation of the {sup 4}I{sub 11/2} terminal level lifetime for several neodymium-doped laser crystals and glasses

Description: All models of lasing action require knowledge of the physical parameters involved, of which many can be measured or estimated. The value of the terminal level lifetime is an important parameter in modeling many high power laser systems since the terminal level lifetime can have a substantial impact on the extraction efficiency of the system. However, the values of the terminal level lifetimes for a number of important laser materials such as ND:YAG and ND:YLF are not well known. The terminal le… more
Date: April 25, 1995
Creator: Bibeau, C.
Partner: UNT Libraries Government Documents Department
open access

A Comparison of "Total Dust" and Inhalable Personal Sampling for Beryllium Exposure.

Description: In 2009, the American Conference of Governmental Industrial Hygienists (ACGIH) reduced the Beryllium (Be) 8-hr Time Weighted Average Threshold Limit Value (TLV-TWA) from 2.0 {micro}g/m{sup 3} to 0.05 {micro}g/m{sup 3} with an inhalable 'I' designation in accordance with ACGIH's particle size-selective criterion for inhalable mass. Currently, per the Department of Energy (DOE) requirements, the Lawrence Livermore National Laboratory (LLNL) is following the Occupational Health and Safety Administ… more
Date: April 25, 2012
Creator: Carter, C. M.
Partner: UNT Libraries Government Documents Department
open access

Much Ado about Microbunching: Coherent Bunching in High Brightness Electron Beams

Description: The push to provide ever brighter coherent radiation sources has led to the creation of correspondingly bright electron beams. With billions of electrons packed into normalized emittances (phase space) below one micron, collective effects may dominate both the preservation and use of such ultra-bright beams. An important class of collective effects is due to density modulations within the bunch, or microbunching. Microbunching may be deleterious, as in the case of the Microbunching Instability … more
Date: May 25, 2012
Creator: Ratner, Daniel & /SLAC, /Stanford U.
Partner: UNT Libraries Government Documents Department
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