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3,878 Matching Results
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Adaptive anisotropic meshing for steady convection-dominated problems
Obtaining accurate solutions for convection–diffusion equations is challenging due to the presence of layers when convection dominates the diffusion. To solve this problem, we design an adaptive meshing algorithm which optimizes the alignment of anisotropic meshes with the numerical solution. Three main ingredients are used. First, the streamline upwind Petrov–Galerkin method is used to produce a stabilized solution. Second, an adapted metric tensor is computed from the approximate solution. Third, optimized anisotropic meshes are generated from the computed metric tensor by an anisotropic centroidal Voronoi tessellation algorithm. Our algorithm is tested on a variety of two-dimensional examples and the results shows that the algorithm is robust in detecting layers and efficient in avoiding non-physical oscillations in the numerical approximation.
Date:
January 1, 2009
Creator:
Nguyen, Hoa; Gunzburger, Max; Ju, Lili & Burkardt, John
Object Type:
Article
System:
The UNT Digital Library
Adaptive control in optical fibers
Adpative control in combination with ultrafast pulse shaping provides a compelling approach to defeat dispersion, distortion and harness nonlinear phenomena on the femtosecond timescale. Ultrafast pulses propagating in optical fibers generate a number of linear and nonlinear effects which affect the pulse during its travel. The main causes stem from the dependence of the index of refraction on frequency (given that short pulses have a large bandwidth) and from the so-called self-action effects which involve the dependence of the index of refraction on the pulse intensity (which is high given that the pulse energy is confined to a very short amount of time).
Date:
January 1, 2002
Creator:
Omenetto, F. G. (Fiorenzo G.)
Object Type:
Article
System:
The UNT Digital Library
Adaptive control of femtosecond pulse propagation in optical fibers
We present an adaptive control loop that synthesizes fs-pulses that are self-correcting for higher order nonlinear effects when launched in a conventional single-mode fiber, nearly preserving the initial (t{approx}200 fs) pulse duration.
Date:
January 1, 2001
Creator:
Omenetto, F. G. (Fiorenzo G.); Taylor, Antoinette J.,; Moores, M. D. (Mark D.) & Reitze, David H.
Object Type:
Article
System:
The UNT Digital Library
Adaptive Full-Spectrum Solar Energy Systems Cross-Cutting R&D on Adaptive Full-Spectrum Solar Energy Systems for More Efficient and Affordable Use of Solar Energy in Buildings and Hybrid Photobioreactors
This RD&D project is a three year team effort to develop a hybrid solar lighting (HSL) system that transports day light from a paraboloidal dish concentrator to a luminaire via a large core polymer fiber optic. The luminaire can be a device to distribute sunlight into a space for the production of algae or it can be a device that is a combination of day lighting and fluorescent lighting for office lighting. In this project, the sunlight is collected using a one-meter paraboloidal concentrator dish with two-axis tracking. The secondary mirror consists of eight planar-segmented mirrors that direct the visible part of the spectrum to eight fibers (receiver) and subsequently to eight luminaires. This results in about 8,200 lumens incident at each fiber tip. Each fiber can illuminate about 16.7 m{sup 2} (180 ft{sup 2}) of office space. The IR spectrum is directed to a thermophotovoltaic array to produce electricity. This report describes several investigations of various aspects of the system. Taken as a whole, they confirm significant progress towards the technical feasibility of this technology.
Date:
January 1, 2003
Creator:
Wood, Byard D. & Muhs, Jeff D.
Object Type:
Report
System:
The UNT Digital Library
Adaptive management: a paradigm for remediation of public facilities
Public facility restoration planning traditionally focused on response to natural disasters and hazardous materials accidental releases. These plans now need to integrate response to terrorist actions. Therefore, plans must address a wide range of potential vulnerabilities. Similar types of broad remediation planning are needed for restoration of waste and hazardous material handling areas and facilities. There are strong similarities in damage results and remediation activities between unintentional and terrorist actions; however, the uncertainties associated with terrorist actions result in a re-evaluation of approaches to planning. Restoration of public facilities following a release of a hazardous material is inherently far more complex than in confined industrial settings and has many unique technical, economic, social, and political challenges. Therefore, they arguably involve a superset of drivers, concerns and public agencies compared to other restoration efforts. This superset of conditions increases complexity of interactions, reduces our knowledge of the initial conditions, and even condenses the timeline for restoration response. Therefore, evaluations of alternative restoration management approaches developed for responding to terrorist actions provide useful knowledge for large, complex waste management projects. Whereas present planning documents have substantial linearity in their organization, the 'adaptive management' paradigm provides a constructive parallel operations paradigm for restoration …
Date:
January 1, 2009
Creator:
Janecky, David R; Whicker, Jeffrey J & Doerr, Ted B
Object Type:
Article
System:
The UNT Digital Library
Adaptive Management and Planning Models for Cultural Resources in Oil & Gas Fields in New Mexico and Wyoming, Semi-Annual Progress Report: July 1 - December 31, 2003
This report contains a summary of activities of Gnomon, Inc. and five subcontractors that have taken place during the second six months (July 1, 2003-December 31, 2003) under the DOE-NETL cooperative agreement: ''Adaptive Management and Planning Models for Cultural Resources in Oil & Gas Fields in New Mexico and Wyoming'', DE-FC26-02NT15445. Although Gnomon and all five subcontractors completed tasks during these six months, most of the technical experimental work was conducted by the subcontractor, SRI Foundation (SRIF). SRIF created a sensitivity model for the Loco Hills area of southeastern New Mexico that rates areas as having a very good chance, a good chance, or a very poor chance of containing cultural resource sites. SRIF suggested that the results of the sensitivity model might influence possible changes in cultural resource management (CRM) practices in the Loco Hills area of southeastern New Mexico.
Date:
January 1, 2004
Creator:
Robinson, Peggy
Object Type:
Report
System:
The UNT Digital Library
Adaptive Management and Planning Models for Cultural Resources in Oil & Gas Fields in New Mexico and Wyoming, Semi-Annual Progress Report: July 1 - December 31, 2004
This report summarizes activities that have taken place in the last 6 months (July 2004-December 2004) under the DOE-NETL cooperative agreement ''Adaptive Management and Planning Models for Cultural Resources in Oil and Gas Fields, New Mexico and Wyoming'' DE-FC26-02NT15445. This project examines the practices and results of cultural resource investigation and management in two different oil and gas producing areas of the US: southeastern New Mexico and the Powder River Basin of Wyoming. The project evaluates how cultural resource investigations have been conducted in the past and considers how investigation and management could be pursued differently in the future. The study relies upon full database population for cultural resource inventories and resources and geomorphological studies. These are the basis for analysis of cultural resource occurrence, strategies for finding and evaluating cultural resources, and recommendations for future management practices. Activities can be summarized as occurring in either Wyoming or New Mexico.
Date:
January 1, 2005
Creator:
Robinson, Peggy
Object Type:
Report
System:
The UNT Digital Library
Adaptive Peircean decision aid project summary assessments.
This efforts objective was to identify and hybridize a suite of technologies enabling the development of predictive decision aids for use principally in combat environments but also in any complex information terrain. The technologies required included formal concept analysis for knowledge representation and information operations, Peircean reasoning to support hypothesis generation, Mill's's canons to begin defining information operators that support the first two technologies and co-evolutionary game theory to provide the environment/domain to assess predictions from the reasoning engines. The intended application domain is the IED problem because of its inherent evolutionary nature. While a fully functioning integrated algorithm was not achieved the hybridization and demonstration of the technologies was accomplished and demonstration of utility provided for a number of ancillary queries.
Date:
January 1, 2007
Creator:
Senglaub, Michael E.
Object Type:
Report
System:
The UNT Digital Library
Adaptive Restoration of Airborne Daedalus AADS1268 ATM Thermal Data
To incorporate the georegistration and restoration processes into airborne data processing in support of U.S. Department of Energy's nuclear emergency response task, we developed an adaptive restoration filter for airborne Daedalus AADS1268 ATM thermal data based on the Wiener filtering theory. Preliminary assessment shows that this filter enhances the detectability of small weak thermal anomalies in AADS1268 thermal images.
Date:
January 1, 2002
Creator:
Yuan, D.; Doak, E.; Guss, P. & Will, A.
Object Type:
Article
System:
The UNT Digital Library
Adaptively Improving Long Distance Network Transfers With Logistics
Long distance data movement is an essential activity of modern computing. However, the congestion control mechanisms in the Internet’s Transmission Control Protocol (TCP) severely limit the bandwidth achieved by long distance data transfers. The throughput of such transfers can be improved by applying the logistical technique of breaking a single long distance transfer into multiple shorter transfers. This technique can result in signifi cantly improved throughput while still respecting the shared nature of the Internet by not attempting to circumvent the TCP congestion controls. This technique has been incorporated into an algorithm which attempts to dynamically schedule transfers for optimal throughput. The algorithm couples graph techniques with real-time latency and bandwidth measurements to discover the best path and adaptively respond to network dynamics. The algorithm shows improvements in speed and fl exibility over standard data transfer methods such as FTP. Specifi c transfers tests performed between Oak Ridge National Laboratory and a destination in Sunnyvale, CA show throughput increases by a factor of two.
Date:
January 1, 2007
Creator:
LaBissoniere, David & Roche, Kenneth
Object Type:
Article
System:
The UNT Digital Library
Addressing a Nuclear Information Gap
This report talks about Addressing a nuclear information gap
Date:
January 1, 2008
Creator:
Sailor, William C
Object Type:
Article
System:
The UNT Digital Library
Adjustable Speed Pumping Applications: Industrial Technologies Program (ITP) Pumping Systems Tip Sheet #11
This two-page tip sheet provides practical tips on application of Adjustable Speed Drives in industrial settings.
Date:
January 1, 2007
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
ADPF spoke cavity cryomodule concept
The Accelerator Driven Test Facility (ADTF) is being developed as a reactor concepts test bed for transmutation of nuclear waste. A 13.3 mA continuous-wave (CW) proton beam will be accelerated to 600 MeV and impinged on a spallation target. The subsequent neutron shower is used to create a nuclear reaction within a subcritical assembly of waste material that reduces the waste half-life from the order of 10{sup 5} years to 10{sup 2} years. Additionally, significant energy is produced that can be used to generate electrical power. The ADTF proton accelerator consists of room-temperature (RT) structures that accelerate the beam to 6.7-MeV and superconducting (SC) elements that boost the beam's energy to 600-MeV. Traditional SC elliptical cavities experience structural difficulties at low energies due to their geometry. Therefore, stiff-structured SC spoke cavities have been adopted for the energy range between 6.7 and 109 MeV. Elliptical cavities are used at the higher energies. This paper describes a multi-spoke-cavity cryomodule concept for ADTF.
Date:
January 1, 2001
Creator:
Kelley, J. P. (John Patrick); Roybal, P. L. (Phillip L.); La Fave, R. P. (Richard P.); Waynert, J. A. (Joseph A.); Schrage, D. L. (Dale L.); Schmierer, E. N. (Eric N.) et al.
Object Type:
Article
System:
The UNT Digital Library
ADVANCED CEMENTS FOR GEOTHERMAL WELLS
Using the conventional well cements consisting of the calcium silicate hydrates (CaO-SiO{sub 2}-H{sub 2}O system) and calcium aluminum silicate hydrates (CaO-Al{sub 2}O{sub 3}-SiO{sub 2}-H{sub 2}O system) for the integrity of geothermal wells, the serious concern confronting the cementing industries was their poor performance in mechanically supporting the metallic well casing pipes and in mitigating the pipe's corrosion in very harsh geothermal reservoirs. These difficulties are particularly acute in two geological regions: One is the deep hot downhole area ({approx} 1700 m depth at temperatures of {approx} 320 C) that contains hyper saline water with high concentrations of CO{sub 2} (> 40,000 ppm) in conjunction with {approx} 100 ppm H{sub 2}S at a mild acid of pH {approx} 5.0; the other is the upper well region between the well's surface and {approx} 1000 m depth at temperatures up to 200 C. The specific environment of the latter region is characterized by highly concentrated H{sub 2}SO{sub 4} (pH < 1.5) brine containing at least 5000 ppm CO{sub 2}. When these conventional cements are emplaced in these harsh environments, their major shortcoming is their susceptibility to reactions with hot CO{sub 2} and H{sub 2}SO4, thereby causing their deterioration brought about by CO{sub 2}-catalyzed …
Date:
January 1, 2007
Creator:
SUGAMA,T.
Object Type:
Report
System:
The UNT Digital Library
Advanced characterization of twins using automated EBSD
This poster describes resuns obtained using an automated, crystallographically-based technique for twin identification. The technique is based on the automated EBSD. The key features of the analysis are identification of potential twin boundaries by their misorientation character, identification of the distinct boundary planes among the symmetrically equiwlent candidates. and validation of these boundaries through comparison with the boundary and twin plane traces in the sample cross section. Results on the application of this technique to deformation twins in zirconium are analyzed for the effect of twin type and amount and sense of uniaxial deformation. The accumulation of strain tends to increase the misorientation deviation at least to the degree of the trace deviation compared with recrystalllzation twins in nickel.
Date:
January 1, 2002
Creator:
Wright, S. I. (Stuart I.); Bingert, J. F. (John F.); Mason, T. A. (Thomas A.) & Larsen, Ryan J.
Object Type:
Article
System:
The UNT Digital Library
Advanced characterization of twins using automated electron backscatter diffraction
This paper describes results obtained using an automated, crystallographically-based technique for twin identification. The technique is based on the automated collection of spatially specific orientation measurements by electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM). The key features of the analysis are identification of potential twin boundaries by their misorientation character, identification of the distinct boundary planes among the symmetrically equivalent candidates, and validation of these boundaries through comparison with the boundary and twin plane traces in the sample cross section. Results on the application of this technique to deformation twins in zirconium are analyzed for the effect of twin type and amount and sense of uniaxial deformation. The accumulation of strain tends to increase the misorientation deviation at least to the degree of the trace deviation compared with recrystallization twins in nickel. In addition to the results on characterizing the twin character, results on extending the twin analysis to automated identification of parent and daughter material for structures exhibiting twin deformation are reported as well.
Date:
January 1, 2002
Creator:
Wright, S. I. (Stuart I.); Bingert, J. F. (John F.); Mason, T. A. (Thomas A.) & Larson, R. J. (Ryan J.)
Object Type:
Article
System:
The UNT Digital Library
ADVANCED CO2 CYCLE POWER GENERATION
Research is being conducted under United States Department of Energy (DOE) Contract DE-FC26-02NT41621 to develop a conceptual design and determine the performance characteristics of a new IGCC plant configuration that facilitates CO{sub 2} removal for sequestration. This new configuration will be designed to achieve CO{sub 2} sequestration without the need for water gas shifting and CO{sub 2} separation, and may eliminate the need for a separate sequestration compressor. This research introduces a novel concept of using CO{sub 2} as a working fluid for an advanced coal gasification based power generation system, where it generates power with high system efficiency while concentrating CO{sub 2} for sequestration. This project supports the DOE research objective of development of concepts for the capture and storage of CO{sub 2}.
Date:
January 1, 2004
Creator:
Nehrozoglu, A.
Object Type:
Report
System:
The UNT Digital Library
Advanced Combustion Systems for Next Generation Gas Turbines
Next generation turbine power plants will require high efficiency gas turbines with higher pressure ratios and turbine inlet temperatures than currently available. These increases in gas turbine cycle conditions will tend to increase NOx emissions. As the desire for higher efficiency drives pressure ratios and turbine inlet temperatures ever higher, gas turbines equipped with both lean premixed combustors and selective catalytic reduction after treatment eventually will be unable to meet the new emission goals of sub-3 ppm NOx. New gas turbine combustors are needed with lower emissions than the current state-of-the-art lean premixed combustors. In this program an advanced combustion system for the next generation of gas turbines is being developed with the goal of reducing combustor NOx emissions by 50% below the state-of-the-art. Dry Low NOx (DLN) technology is the current leader in NOx emission technology, guaranteeing 9 ppm NOx emissions for heavy duty F class gas turbines. This development program is directed at exploring advanced concepts which hold promise for meeting the low emissions targets. The trapped vortex combustor is an advanced concept in combustor design. It has been studied widely for aircraft engine applications because it has demonstrated the ability to maintain a stable flame over a …
Date:
January 1, 2006
Creator:
Haynes, Joel; Janssen, Jonathan; Russell, Craig & Huffman, Marcus
Object Type:
Report
System:
The UNT Digital Library
ADVANCED DIRECT LIQUEFACTION CONCEPTS FOR PETC GENERIC UNITS
The results of Laboratory and Bench-Scale experiments and supporting technical and economic assessments conducted under DOE Contract No. DE-AC22-91PC91040 is reported for the period October 1, 1999 to December 31, 1999. This contract is with the University of kentucky Research Foundation, which supports work with the University of Kentucky Center for Applied Energy Researc, CONSOL, Inc., LDP Associates, and Hydrocarbon Technologies, Inc. This work involves the introduction into the basic two-stage liquefaction process several novel concepts, which include dispersed lower-cost catalysts, coal cleaning by oil agglomeration, and distillate hydrotreating and dewaxing. This project has been modified to include an investigation into the production of value added materials from coal using liquefaction based technologies.
Date:
January 1, 2000
Creator:
Berkovich, Adam J.
Object Type:
Report
System:
The UNT Digital Library
ADVANCED DIRECT LIQUEFACTION CONCEPTS FOR PETC GENERIC UNITS
The results of Laboratory and Bench-Scale experiments and supporting technical and economic assessments conducted under DOE Contract No. DE-AC22-91PC91040 are reported for the period October 1, 2000 to December 31, 2000. This work involves the introduction into the basic two-stage liquefaction process several novel concepts, which include dispersed lower-cost catalysts, coal cleaning by oil agglomeration, and distillate hydrotreating and dewaxing. This project has been modified to include an investigation into the production of value added materials from coal using low-severity liquefaction based technologies.
Date:
January 1, 2001
Creator:
Berkovich, Adam J.
Object Type:
Report
System:
The UNT Digital Library
ADVANCED FLUE GAS CONDITIONING AS A RETROFIT UPGRADE TO ENHANCE PM COLLECTION FROM COAL-FIRED ELECTRIC UTILITY BOILERS
The U.S. Department of Energy and ADA Environmental Solutions are engaged in a project to develop commercial flue gas conditioning additives. The objective is to develop conditioning agents that can help improve particulate control performance of smaller or under-sized electrostatic precipitators on utility coal-fired boilers. The new chemicals will be used to control both the electrical resistivity and the adhesion or cohesivity of the fly ash. There is a need to provide cost-effective and safer alternatives to traditional flue gas conditioning with SO{sub 3} and ammonia. During this reporting quarter, installation of a flue gas conditioning system was completed at PacifiCorp Jim Bridger Power Plant. Performance testing was underway. Results will be detailed in the next quarterly and subsequent technical summary reports. Also in this quarter, discussions were initiated with a prospective long-term candidate plant. This plant fires a bituminous coal and has opacity performance issues related to fly ash re-entrainment. Ammonia conditioning has been proposed here, but there is interest in liquid additives as a safer alternative.
Date:
January 1, 2002
Creator:
Baldrey, Kenneth E.
Object Type:
Report
System:
The UNT Digital Library
ADVANCED FLUE GAS CONDITIONING AS A RETROFIT UPGRADE TO ENHANCE PM COLLECTION FROM COAL-FIRED ELECTRIC UTILITY BOILERS
The U.S. Department of Energy and ADA Environmental Solutions are engaged in a project to develop commercial flue gas conditioning additives. The objective is to develop conditioning agents that can help improve particulate control performance of smaller or under-sized electrostatic precipitators on utility coal-fired boilers. The new chemicals will be used to control both the electrical resistivity and the adhesion or cohesivity of the fly ash. There is a need to provide cost-effective and safer alternatives to traditional flue gas conditioning with SO{sub 3} and ammonia. During this reporting quarter, installation of a liquid flue gas conditioning system was completed at the American Electric Power Conesville Plant, Unit 3. This plant fires a bituminous coal and has opacity and particulate emissions performance issues related to fly ash re-entrainment. Two cohesivity-specific additive formulations, ADA-44C and ADA-51, will be evaluated. In addition, ammonia conditioning will also be compared.
Date:
January 1, 2003
Creator:
Baldrey, Kenneth E.
Object Type:
Report
System:
The UNT Digital Library
ADVANCED FLUE GAS CONDITIONING AS A RETROFIT UPGRADE TO ENHANCE PM COLLECTION FROM COAL-FIRED ELECTRIC UTILITY BOILERS
The U.S. Department of Energy and ADA Environmental Solutions has begun a project to develop commercial flue gas conditioning additives. The objective is to develop conditioning agents that can help improve particulate control performance of smaller or under-sized electrostatic precipitators on utility coal-fired boilers. The new chemicals will be used to control both the electrical resistivity and the adhesion or cohesivity of the flyash. There is a need to provide cost-effective and safer alternatives to traditional flue gas conditioning with SO{sub 3} and ammonia. During the third reporting quarter, the electrostatic tensiometer for laboratory determination of flyash cohesivity was completed. Modifications were made to this method to improve repeatability. In addition, a new multi-cell laboratory flyash resistivity furnace was completed. Also during this quarter an agreement was reached for the initial field trial of the new additives at the City of Ames, Iowa Municipal Power Plant.
Date:
January 1, 2001
Creator:
Baldrey, Kenneth E.
Object Type:
Report
System:
The UNT Digital Library
Advanced Fuel Cycle Economic Analysis of Symbiotic Light-Water Reactor and Fast Burner Reactor Systems
The Advanced Fuel Cycle Economic Analysis of Symbiotic Light-Water Reactor and Fast Burner Reactor Systems, prepared to support the U.S. Advanced Fuel Cycle Initiative (AFCI) systems analysis, provides a technology-oriented baseline system cost comparison between the open fuel cycle and closed fuel cycle systems. The intent is to understand their overall cost trends, cost sensitivities, and trade-offs. This analysis also improves the AFCI Program’s understanding of the cost drivers that will determine nuclear power’s cost competitiveness vis-a-vis other baseload generation systems. The common reactor-related costs consist of capital, operating, and decontamination and decommissioning costs. Fuel cycle costs include front-end (pre-irradiation) and back-end (post-iradiation) costs, as well as costs specifically associated with fuel recycling. This analysis reveals that there are large cost uncertainties associated with all the fuel cycle strategies, and that overall systems (reactor plus fuel cycle) using a closed fuel cycle are about 10% more expensive in terms of electricity generation cost than open cycle systems. The study concludes that further U.S. and joint international-based design studies are needed to reduce the cost uncertainties with respect to fast reactor, fuel separation and fabrication, and waste disposition. The results of this work can help provide insight to the cost-related factors …
Date:
January 1, 2009
Creator:
Shropshire, D. E.
Object Type:
Report
System:
The UNT Digital Library