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The Low-Frequency Radio Catalog of Flat Spectrum Sources
None
Date:
May 1, 2014
Creator:
Massaro, F.; Giroletti, M.; D'Abrusco, R.; Masetti, N.; Paggi, A.; Cowperthwaite, Philip S. et al.
Object Type:
Article
System:
The UNT Digital Library
Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments
The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the …
Date:
May 31, 2013
Creator:
Crone, Wendy; Cao, Guoping & Sridhara, Kumar
Object Type:
Report
System:
The UNT Digital Library
B0 Meson Decays to Rho0 K*0, F0 K*0, And Rho- K* , Including Higher K* Resonances
None
Date:
May 31, 2013
Creator:
Lee-Boehm, Corry Louise & U., /Harvard
Object Type:
Article
System:
The UNT Digital Library
CO{sub 2} Geologic Storage: Coupled Hydro-Chemo-Thermo-Mechanical Phenomena - From Pore-scale Processes to Macroscale Implications -
Global energy consumption will increase in the next decades and it is expected to largely rely on fossil fuels. The use of fossil fuels is intimately related to CO{sub 2} emissions and the potential for global warming. Geological CO{sub 2} storage aims to mitigate the global warming problem by sequestering CO{sub 2} underground. Coupled hydro-chemo-mechanical phenomena determine the successful operation and long term stability of CO{sub 2} geological storage. This research explores coupled phenomena, identifies different zones in the storage reservoir, and investigates their implications in CO{sub 2} geological storage. In particular, the research: Explores spatial patterns in mineral dissolution and precipitation (comprehensive mass balance formulation); experimentally determines the interfacial properties of water, mineral, and CO{sub 2} systems (including CO{sub 2}-water-surfactant mixtures to reduce the CO{sub 2}- water interfacial tension in view of enhanced sweep efficiency); analyzes the interaction between clay particles and CO{sub 2}, and the response of sediment layers to the presence of CO{sub 2} using specially designed experimental setups and complementary analyses; couples advective and diffusive mass transport of species, together with mineral dissolution to explore pore changes during advection of CO{sub 2}-dissolved water along a rock fracture; upscales results to a porous medium using pore network …
Date:
May 31, 2013
Creator:
Santamarina, J. Carlos
Object Type:
Report
System:
The UNT Digital Library
Corn Storage Protein - A Molecular Genetic Model
Corn is the highest yielding crop on earth and probably the most valuable agricultural product of the United States. Because it converts sun energy through photosynthesis into starch and proteins, we addressed energy savings by focusing on protein quality. People and animals require essential amino acids derived from the digestion of proteins. If proteins are relatively low in certain essential amino acids, the crop becomes nutritionally defective and has to be supplemented. Such deficiency affects meat and fish production and countries where corn is a staple. Because corn seed proteins have relatively low levels of lysine and methionine, a diet has to be supplemented with soybeans for the missing lysine and with chemically synthesized methionine. We therefore have studied genes expressed during maize seed development and their chromosomal organization. A critical technical requirement for the understanding of the molecular structure of genes and their positional information was DNA sequencing. Because of the length of sequences, DNA sequencing methods themselves were insufficient for this type of analysis. We therefore developed the so-called “DNA shotgun sequencing” strategy, where overlapping DNA fragments were sequenced in parallel and used to reconstruct large DNA molecules via overlaps. Our publications became the most frequently cited ones …
Date:
May 31, 2013
Creator:
Messing, Joachim
Object Type:
Report
System:
The UNT Digital Library
Efficient Regeneration of Physical and Chemical Solvents for CO{sub 2} Capture
The objective of this project was to evaluate the use of composite polymer membranes and porous membrane contactors to regenerate physical and chemical solvents for capture of carbon dioxide (CO{sub 2}) from synthesis gas or flue gas, with the goal of improving the energy efficiency of carbon capture. Both a chemical solvent (typical for a post-combustion capture of CO{sub 2} from flue gas) and a physical solvent (typical for pre- combustion capture of CO{sub 2} from syngas) were evaluated using two bench-scale test systems constructed for this project. For chemical solvents, polytetrafluoroethylene and polypropylene membranes were found to be able to strip CO{sub 2} from a monoethanolamine (MEA) solution with high selectivity without significant degradation of the material. As expected, the regeneration temperature was the most significant parameter affecting the CO{sub 2} flux through the membrane. Pore size was also found to be important, as pores larger than 5 microns lead to excessive pore wetting. For physical solvents, polydimethyl-siloxane (PDMS)-based membranes were found to have a higher CO{sub 2} permeability than polyvinylalcohol (PVOH) based membranes, while also minimizing solvent loss. Overall, however, the recovery of CO{sub 2} in these systems is low – less than 2% for both chemical and …
Date:
May 31, 2013
Creator:
Tande, Brian; Seames, Wayne & Benson, Steve
Object Type:
Report
System:
The UNT Digital Library
Fairbanks Geothermal Energy Project Final Report
The primary objective for the Fairbanks Geothermal Energy Project is to provide another source of base-load renewable energy in the Fairbanks North Star Borough (FNSB). To accomplish this, Chena Hot Springs Resort (Chena) drilled a re-injection well to 2700 feet and a production well to 2500 feet. The re-injection well allows a greater flow of water to directly replace the water removed from the warmest fractures in the geothermal reservoir. The new production will provide access to warmer temperature water in greater quantities.
Date:
May 31, 2013
Creator:
Karl, Bernie
Object Type:
Report
System:
The UNT Digital Library
FINAL REPORT DE-FG02-07ER15894
One of the greatest technological hurdles to deployment of fuel cells relates to the sluggish activity, low durability and the high cost of the catalysts that are currently employed. For automotive PEM fuel cells to become commercially viable, the Pt-specific power density would need to be reduced to less than 0.2gPt/kW (at cell voltages >0.65 V). This would require the Pt loadings to be less than 0.15 mgPt/cm2MEA within the membrane electrode assembly. This could be achieved by enhancing the catalytic activity at the cathode, thus lowering its overpotential. Various different Pt-alloys have shown 2-4 times enhanced activities over Pt alone but still suffer some of the same durability issues as that of the pure Pt. There is a general loss of active Pt due to dissolution and sintering. While there have been a number of elegant fundamental experimental and theoretical studies on ideal single crystal Pt and Pt alloy surfaces which have helped to elucidate the factors that control the activity, there have been very few fundamental studies focused on the stability, reactivity and durability of well-defined Pt nanoparticles. We carried out ab initio density functional theory together with a novel double reference method that we developed to simulate …
Date:
May 31, 2013
Creator:
Neurock, Matthew
Object Type:
Report
System:
The UNT Digital Library
Improved Flow-Field Structures for Direct Methanol Fuel Cells
The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.
Date:
May 31, 2013
Creator:
Gurau, Bogdan
Object Type:
Report
System:
The UNT Digital Library
Measurement of the Inclusive Isolated Prompt Photon Cross-Section in $Pp$ Collisions at $\sqrt{s}=7$ TeV Using 35 Pb-1 of ATLAS Data
None
Date:
May 31, 2013
Creator:
Aad, Georges
Object Type:
Article
System:
The UNT Digital Library
Measurement of the Pseudorapidity and Transverse Momentum Dependence of the Elliptic Flow of Charged Particles in Lead-Lead Collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS Detector
None
Date:
May 31, 2013
Creator:
Aad, Georges
Object Type:
Article
System:
The UNT Digital Library
Meausrement of the Neutron Radius of {sup 208}Pb Through Parity Violation in Electron Scattering
In contrast to the nuclear charge densities, which have been accurately measured with electron scattering, the knowledge of neutron densities still lack precision. Previous model-dependent hadron experiments suggest the difference between the neutron radius, R{sub n}, of a heavy nucleus and the proton radius, R{sub p}, to be in the order of several percent. To accurately obtain the difference, R{sub n}-R{sub p}, which is essentially a neutron skin, the Jefferson Lab Lead ({sup 208}Pb) Radius Experiment (PREX) measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from {sup 208}Pb at an energy of 1.06 GeV and a scattering angle of 5{degrees}#14;. Since Z{sup 0} boson couples mainly to neutrons, this asymmetry provides a clean measurement of R{sub n} with respect to R{sub p}. PREX was conducted at the Jefferson lab experimental Hall A, from March to June 2010. The experiment collected a final data sample of 2x#2;10{sup 7} helicity-window quadruplets. The measured parity-violating electroweak asymmetry A{sub PV} = 0.656 {+-}#6; 0.060 (stat) {+-}#6; 0.014 (syst) ppm corresponds to a difference between the radii of the neutron and proton distributions, R{sub n}-R{sub p} = 0.33{sup +0.16}{sub -0.18} fm and provides the #12;first electroweak observation of the neutron skin …
Date:
May 31, 2013
Creator:
Saenboonruang, Kiadtisak
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Model-Based Subspace Detectors Constructed with SPECFEM3D
None
Date:
May 31, 2013
Creator:
Harris, D. B. & Rodgers, A. J.
Object Type:
Article
System:
The UNT Digital Library
Numerical Modeling of Geomechanical Processes Related to CO{sub 2} Injection within Generic Reservoirs
In this project generic anticline structures have been used for numerical modeling analyses to study the influence of geometrical parameters, fluid flow boundary conditions, in situ stress regime and inter-bedding friction coefficient on geomechanical risks such as fracture reactivation and fracture generation. The resulting stress states for these structures are also used to determine safe drilling directions and a methodology for wellbore trajection optimization is developed that is applicable for non-Andersonian stress states. The results of the fluid flow simulation show that the type of fluid flow boundary condition is of utmost importance and has significant impact on all injection related parameters. It is recommended that further research is conducted to establish a method to quantify the fluid flow boundary conditions for injection applications. The results of the geomechanical simulation show that in situ stress regime is a crucial, if not the most important, factor determining geomechanical risks. For extension and strike slip stress regimes anticline structures should be favored over horizontally layered basin as they feature higher ΔP{sub c} magnitudes. If sedimentary basins are tectonically relaxed and their state of stress is characterized by the uni-axial strain model the basin is in exact frictional equilibrium and fluids should not …
Date:
May 31, 2013
Creator:
Eckert, Andreas
Object Type:
Report
System:
The UNT Digital Library
Recovery Act: Multi-Objective Optimization Approaches for the Design of Carbon Geological Sequestration Systems
The main objective of this project is to provide training opportunities for two graduate students in order to improve the human capital and skills required for implementing and deploying carbon capture and sequestration (CCS) technologies. The graduate student effort will be geared towards the formulation and implementation of an integrated simulation-optimization framework to provide a rigorous scientific support to the design CCS systems that, for any given site: (a) maximize the amount of carbon storage; (b) minimize the total cost associated with the CCS project; (c) minimize the risk of CO2 upward leakage from injected formations. The framework will stem from a combination of data obtained from geophysical investigations, a multiphase flow model, and a stochastic multi-objective optimization algorithm. The methodology will rely on a geostatistical approach to generate ensembles of scenarios of the parameters that are expected to have large sensitivities and uncertainties on the model response and thus on the risk assessment, in particular the permeability properties of the injected formation and its cap rock. The safety theme will be addressed quantitatively by including the risk of CO2 upward leakage from the injected formations as one the objectives that should be minimized in the optimization problem. The research …
Date:
May 31, 2013
Creator:
Bau, Domenico
Object Type:
Report
System:
The UNT Digital Library
Review of Exotic Hadrons
None
Date:
May 31, 2013
Creator:
Renga, Francesco
Object Type:
Article
System:
The UNT Digital Library
Rock Physics of Geologic Carbon Sequestration/Storage
This report covers the results of developing the rock physics theory of the effects of CO{sub 2} injection and storage in a host reservoir on the rock�s elastic properties and the resulting seismic signatures (reflections) observed during sequestration and storage. Specific topics addressed are: (a) how the elastic properties and attenuation vary versus CO{sub 2} saturation in the reservoir during injection and subsequent distribution of CO{sub 2} in the reservoir; (b) what are the combined effects of saturation and pore pressure on the elastic properties; and (c) what are the combined effects of saturation and rock fabric alteration on the elastic properties. The main new results are (a) development and application of the capillary pressure equilibrium theory to forecasting the elastic properties as a function of CO{sub 2} saturation; (b) a new method of applying this theory to well data; and (c) combining this theory with other effects of CO{sub 2} injection on the rock frame, including the effects of pore pressure and rock fabric alteration. An important result is translating these elastic changes into synthetic seismic responses, specifically, the amplitude-versus-offset (AVO) response depending on saturation as well as reservoir and seal type. As planned, three graduate students participated in …
Date:
May 31, 2013
Creator:
Dvorkin, Jack & Mavko, Gary
Object Type:
Report
System:
The UNT Digital Library
The Role of Lattice Coupling in Establishing Electronic and Magnetic Properties in Quasi-One-Dimensional Cuprates
None
Date:
May 31, 2013
Creator:
Lee, W. S.; Johnston, S.; Moritz, B.; Lee, J.; Yi, M.; Zhou, K. J. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for the Inclusive B to D Gamma Decay at BaBar
None
Date:
May 31, 2013
Creator:
Bard, Deborah & U., /Edinburgh
Object Type:
Article
System:
The UNT Digital Library
Supplemental Immobilization Cast Stone Technology Development and Waste Form Qualification Testing Plan
The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the 56 million gallons of radioactive waste stored in 177 underground tanks at the Hanford Site. The WTP includes a pretreatment facility to separate the wastes into high-level waste (HLW) and low-activity waste (LAW) fractions for vitrification and disposal. The LAW will be converted to glass for final disposal at the Integrated Disposal Facility (IDF). The pretreatment facility will have the capacity to separate all of the tank wastes into the HLW and LAW fractions, and the HLW Vitrification Facility will have the capacity to vitrify all of the HLW. However, a second immobilization facility will be needed for the expected volume of LAW requiring immobilization. A number of alternatives, including Cast Stone—a cementitious waste form—are being considered to provide the additional LAW immobilization capacity.
Date:
May 31, 2013
Creator:
Westsik, Joseph H.; Serne, R. Jeffrey; Pierce, Eric M.; Cozzi, Alex; Chung, Chul-Woo & Swanberg, David J.
Object Type:
Report
System:
The UNT Digital Library
Training and Research on Probabilistic Hydro-Thermo-Mechanical Modeling of Carbon Dioxide Geological Sequestration in Fractured Porous Rocks
Colorado School of Mines conducted research and training in the development and validation of an advanced CO{sub 2} GS (Geological Sequestration) probabilistic simulation and risk assessment model. CO{sub 2} GS simulation and risk assessment is used to develop advanced numerical simulation models of the subsurface to forecast CO2 behavior and transport; optimize site operational practices; ensure site safety; and refine site monitoring, verification, and accounting efforts. As simulation models are refined with new data, the uncertainty surrounding the identified risks decrease, thereby providing more accurate risk assessment. The models considered the full coupling of multiple physical processes (geomechanical and fluid flow) and describe the effects of stochastic hydro-mechanical (H-M) parameters on the modeling of CO{sub 2} flow and transport in fractured porous rocks. Graduate students were involved in the development and validation of the model that can be used to predict the fate, movement, and storage of CO{sub 2} in subsurface formations, and to evaluate the risk of potential leakage to the atmosphere and underground aquifers. The main major contributions from the project include the development of: 1) an improved procedure to rigorously couple the simulations of hydro-thermomechanical (H-M) processes involved in CO{sub 2} GS; 2) models for the hydro-mechanical …
Date:
May 31, 2013
Creator:
Gutierrez, Marte
Object Type:
Report
System:
The UNT Digital Library
The 2D 'Shock-Jet' Problem
None
Date:
May 30, 2013
Creator:
Morgan, B E
Object Type:
Report
System:
The UNT Digital Library
The Application Of Mid-Ranging Control To Improve Thermal Disturbance Rejection for Cryogenic THD/DT Layering At The National Ignition Facility
None
Date:
May 30, 2013
Creator:
Dayton, M & Haid, B
Object Type:
Article
System:
The UNT Digital Library
Final Report---Next-Generation Solvers for Mixed-Integer Nonlinear Programs: Structure, Search, and Implementation
The mathematical modeling of systems often requires the use of both nonlinear and discrete components. Problems involving both discrete and nonlinear components are known as mixed-integer nonlinear programs (MINLPs) and are among the most challenging computational optimization problems. This research project added to the understanding of this area by making a number of fundamental advances. First, the work demonstrated many novel, strong, tractable relaxations designed to deal with non-convexities arising in mathematical formulation. Second, the research implemented the ideas in software that is available to the public. Finally, the work demonstrated the importance of these ideas on practical applications and disseminated the work through scholarly journals, survey publications, and conference presentations.
Date:
May 30, 2013
Creator:
Linderoth, Jeff T. & Luedtke, James R.
Object Type:
Report
System:
The UNT Digital Library