Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks (open access)

Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks

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Date: March 15, 2013
Creator: Chen, M; Sun, Y; Fu, P; Carrigan, C R; Lu, Z & Tong, C H
Object Type: Article
System: The UNT Digital Library
A reduced graphene oxide/Co{sub 3}O{sub 4} composite for supercapacitor electrode (open access)

A reduced graphene oxide/Co{sub 3}O{sub 4} composite for supercapacitor electrode

20 nm sized Co{sub 3}O{sub 4} nanoparticles are in-situ grown on the chemically reduced graphene oxide (rGO) sheets to form a rGO-Co{sub 3}O{sub 4} composite during hydrothermal processing. The rGO-Co{sub 3}O{sub 4} composite is employed as the pseudocapacitor electrode in the 2 M KOH aqueous electrolyte solution. The rGOCo{sub 3}O{sub 4} composite electrode exhibits a specific capacitance of 472 F/g at a scan rate of 2 mV/s in a two-electrode cell. 82.6% of capacitance is retained when the scan rate increases to 100 mV/s. The rGOCo{sub 3}O{sub 4} composite electrode shows high rate capability and excellent long-term stability. It also exhibits high energy density at relatively high power density. The energy density reaches 39.0 Wh/kg at a power density of 8.3 kW/kg. The super performance of the composite electrode is attributed to the synergistic effects of small size and good redox activity of the Co{sub 3}O{sub 4} particles combined with high electronic conductivity of the rGO sheets.
Date: March 15, 2013
Creator: Xiang, Chengcheng; Li, Ming; Zhi, Mingjia; Manivannan, Ayyakkannu & Wu, Nianqiang
Object Type: Article
System: The UNT Digital Library
Western Kentucky University Research Foundation Biodiesel Project (open access)

Western Kentucky University Research Foundation Biodiesel Project

Petroleum-based liquid hydrocarbons is exclusively major energy source in the transportation sector. Thus, it is the major CO{sub 2} source which is the associated with greenhouse effect. In the United States alone, petroleum consumption in the transportation sector approaches 13.8 million barrels per day (Mbbl/d). It is corresponding to a release of 0.53 gigatons of carbon per year (GtC/yr), which accounts for approximate 7.6 % of the current global release of CO{sub 2} from all of the fossil fuel usage (7 GtC/yr). For the long term, the conventional petroleum production is predicted to peak in as little as the next 10 years to as high as the next 50 years. Negative environmental consequences, the frequently roaring petroleum prices, increasing petroleum utilization and concerns about competitive supplies of petroleum have driven dramatic interest in producing alternative transportation fuels, such as electricity-based, hydrogen-based and bio-based transportation alternative fuels. Use of either of electricity-based or hydrogen-based alternative energy in the transportation sector is currently laden with technical and economical challenges. The current energy density of commercial batteries is 175 Wh/kg of battery. At a storage pressure of 680 atm, the lower heating value (LHV) of H{sub 2} is 1.32 kWh/liter. In contrast, the …
Date: March 15, 2013
Creator: Pan, Wei-Ping & Cao, Yan
Object Type: Report
System: The UNT Digital Library
Real-time manifestation of strongly coupled spin and charge order parameters in stripe-ordered nickelates via time-resolved resonant x-ray diffraction (open access)

Real-time manifestation of strongly coupled spin and charge order parameters in stripe-ordered nickelates via time-resolved resonant x-ray diffraction

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Date: March 15, 2013
Creator: Chuang, Y. D.; Lee, W. S.; Kung, Y. F.; Sorini, A. P.; Moritz, B.; Moore, R. G. et al.
Object Type: Article
System: The UNT Digital Library
Disposal Systems Evaluation Framework DSEF Version 2.1 User's Manual (open access)

Disposal Systems Evaluation Framework DSEF Version 2.1 User's Manual

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Date: March 15, 2013
Creator: Greenberg, H. R.; Blink, J. A.; Sutton, M. & Wolery, T. J.
Object Type: Report
System: The UNT Digital Library
Evaluating greenhouse gas emissions from hydropower complexes on large rivers in Eastern Washington (open access)

Evaluating greenhouse gas emissions from hydropower complexes on large rivers in Eastern Washington

Water bodies, such as freshwater lakes, are known to be net emitters of carbon dioxide (CO2), and methane (CH4). In recent years, significant greenhouse gas (GHG) emissions from tropical, boreal, and mid-latitude reservoirs have been reported. At a time when hydropower is increasing worldwide, better understanding of seasonal and regional variation in GHG emissions is needed in order to develop a predictive understanding of such fluxes within man-made impoundments. We examined power-producing dam complexes within xeric temperate locations in the northwestern United States. Sampling environments on the Snake (Lower Monumental Dam Complex) and Columbia Rivers (Priest Rapids Dam Complex) included tributary, mainstem, embayment, forebay, and tailrace areas during winter and summer 2012. At each sampling location, GHG measurement pathways included surface gas flux, degassing as water passed through dams during power generation, ebullition within littoral embayments, and direct sampling of hyporheic pore-water. Measurements were also carried out in a free-flowing reach of the Columbia River to estimate unaltered conditions. Surface flux resulted in very low emissions, with reservoirs acting as a sink for CO2 (up to –262 mg m-2 d-1, which is within the range previously reported for similarly located reservoirs). Surface flux of methane remained below 1 mg CH4 …
Date: March 15, 2013
Creator: Arntzen, Evan V.; Miller, Benjamin L.; O'Toole, Amanda C.; Niehus, Sara E. & Richmond, Marshall C.
Object Type: Report
System: The UNT Digital Library
Determination of Large-Scale Cloud Ice Water Concentration by Combining Surface Radar and Satellite Data in Support of ARM SCM Activities (open access)

Determination of Large-Scale Cloud Ice Water Concentration by Combining Surface Radar and Satellite Data in Support of ARM SCM Activities

Single-column modeling (SCM) is one of the key elements of Atmospheric Radiation Measurement (ARM) research initiatives for the development and testing of various physical parameterizations to be used in general circulation models (GCMs). The data required for use with an SCM include observed vertical profiles of temperature, water vapor, and condensed water, as well as the large-scale vertical motion and tendencies of temperature, water vapor, and condensed water due to horizontal advection. Surface-based measurements operated at ARM sites and upper-air sounding networks supply most of the required variables for model inputs, but do not provide the horizontal advection term of condensed water. Since surface cloud radar and microwave radiometer observations at ARM sites are single-point measurements, they can provide the amount of condensed water at the location of observation sites, but not a horizontal distribution of condensed water contents. Consequently, observational data for the large-scale advection tendencies of condensed water have not been available to the ARM cloud modeling community based on surface observations alone. This lack of advection data of water condensate could cause large uncertainties in SCM simulations. Additionally, to evaluate GCMs’ cloud physical parameterization, we need to compare GCM results with observed cloud water amounts over a …
Date: March 15, 2013
Creator: Liu, Guosheng
Object Type: Report
System: The UNT Digital Library
Final Technical Report on Radioxenon Event Analysis (open access)

Final Technical Report on Radioxenon Event Analysis

This is a final deliverable report for the Advanced Spectral Analysis for Radioxenon project with a focus on radioxenon event categorization.
Date: March 15, 2013
Creator: Ely, James H.; Cooper, Matthew W.; Hayes, James C.; Heimbigner, Tom R.; McIntyre, Justin I. & Schrom, Brian T.
Object Type: Report
System: The UNT Digital Library
Test Plan to Evaluate the Relationship Among IAQ, Comfort, Moisture, and Ventilation in Humid Climates (open access)

Test Plan to Evaluate the Relationship Among IAQ, Comfort, Moisture, and Ventilation in Humid Climates

This experimental plan describes research being conducted by Pacific Northwest National Laboratory (PNNL), in coordinatation with Florida Solar Energy Center (FSEC), Florida HERO, and Lawrence Berkeley National Laboratory (LBNL) to evaluate the impact of ventilation rate on interior moisture levels, temperature distributions, and indoor air contaminant concentrations. Specifically, the research team will measure concentrations of indoor air contaminants, ventilation system flow rates, energy consumption, and temperature and relative humidity in ten homes in Gainesville, FL to characterize indoor pollutant levels and energy consumption associated with the observed ventilation rates. PNNL and FSEC have collaboratively prepared this experimental test plan, which describes background and context for the proposed study; the experimental design; specific monitoring points, including monitoring equipment, and sampling frequency; key research questions and the associated data analysis approach; experimental logistics, including schedule, milestones, and team member contact information; and clearly identifies the roles and responsibilities of each team in support of project objectives.
Date: March 15, 2013
Creator: Widder, Sarah H. & Martin, Eric
Object Type: Report
System: The UNT Digital Library
Spatially Resolved Study of Backscattering in the Quantum Spin Hall State (open access)

Spatially Resolved Study of Backscattering in the Quantum Spin Hall State

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Date: March 15, 2013
Creator: Konig, Markus; Baenninger, Matthias; /Stanford U., Phys. Dept. /SIMES, Stanford; Garcia, Andrei G.F.; /Stanford U., Phys. Dept.; Harjee, Nahid et al.
Object Type: Article
System: The UNT Digital Library