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12,143 Matching Results
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An experimental study of VBR video over various ATM switch architectures
One of the most important components of an Asynchronous Transfer Mode (ATM) network is the switch. Switch design is not a part of the ATM standards so vendors use a wide variety of techniques to build their switches. In this paper, the authors present experimental results of switching and multiplexing real-time Variable Bit Rate (VBR) video traffic (JPEG, MPEG-1, and MPEG-2) through two different ATM switch architectures. Real-time VBR traffic, such as digital video, is particularly interesting due to its high demands in terms of bandwidth, real-time delivery and processing requirements. The experiments show that the fastest switches, i.e., lowest latencies, do not necessarily perform better when transmitting VBR video. The impact of the high speed network components; characteristics, such as switch fabric architecture, buffering strategies, and higher layer transport protocols (i.e., UDP, TCP/IP), are illustrated through the experimental results.
Date:
December 31, 1997
Creator:
Tsang, R.P.; Hsieh, J. & Du, D.H.C.
Object Type:
Article
System:
The UNT Digital Library
Exploratory Study of Irradiation, Annealing, and Reirradiation Effects on American and Russian Reactor Pressure Vessel Steels
One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVS) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available to allow for verification models of reirradiation embrittlement or for the development of a reliable predictive methodology. This is especially true in the case of fracture toughness data. Under the U.S.-Russia Joint Coordinating Committee for Civilian Nuclear Reactor Safety (JCCCNRS), Working Group 3 on Radiation Embrittlement, Structural Integrity, and Life Extension of Reactor Vessels and Supports agreed to conduct a comparative study of annealing and reirradiation effects on RPV steels. The working group agreed that each side would irradiate, anneal, reirradiate (if feasible), and test two materials of the other; so far, only charpy impact and tensile specimens have been included. Oak Ridge National Laboratory (ornl) conducted such a program (irradiation and annealing) with two weld metals representative of VVER-440 AND VVER-1000 RPVS, while the Russian Research Center-Kurchatov Institute (RRC-KI) conducted a program (irradiation,annealing, reirradiation, and reannealing) with Heavy-Section Steel …
Date:
December 31, 1997
Creator:
Chernobaeva, A. A.; Kryukov, A. M.; Nikolaev, Y. A. & Korolev, Y. N.
Object Type:
Article
System:
The UNT Digital Library
F-Element ion chelation in highly basic media. Annual progress report, October 1, 1996--July 1, 1997
'The specific fundamental chemical objectives of this project are to: (1) study the chemical speciation of Sr and Ln ions in basic media formed in aqueous solutions with and without classical chelation agents (e.g., EDTA, polyphosphates, and organic carboxylates); (2) prepare pyridine N-oxide phosphonate and phosphonoacetate chelators of the types 1--3 and characterize their ionization properties by titrimetric techniques; (3) study the interactions of 5--7 with soluble oxide-hydroxide metallate species and higher molecular weight sols, gels and precipitates containing Sr and Ln ions, as time permits, interactions with oxide-hydroxide metallates of U, Th, Ba, Al and Fe will also be studied; (4) study the interactions of newly designed phosphonate ligands with oxide-hydroxide metallate species; (5) transfer the fundamental coordination chemistry revealed here to research groups at LANL and PNNL that will utilize the results to improve tank waste treatment protocols.'
Date:
December 31, 1997
Creator:
Paine, R. T.
Object Type:
Report
System:
The UNT Digital Library
Fabrication and testing of long length high-{Tc} composite conductors. Final report
Presently some methods of HTS-conductors processing are under study in the authors laboratory. ``Powder-in-tube`` (PIT), ``Jelly-roll``, electrophorethis are among them. PIT process has developed predominantly both in a view of the achieved J{sub c} values Bi-2223 phase was used as a core material for these tapes. Since the main purpose of the task order was to enhance the development of long length high temperature superconductor tapes, the authors have considered reasonable to lay the perfection idea of the PIT process step by step or tape by tape. To realize it they have assumed, keeping stable the basic scheme of PIT process, to vary some technological parameters which are as follows: (1) type of initial powder; (2) sheath material; (3) tape construction (filaments number, cross section e.a.); and (4) processing regimes. This report covers the fabrication process and characteristics of the produced conductors.
Date:
December 31, 1997
Creator:
Fisher, L.M.
Object Type:
Report
System:
The UNT Digital Library
Failure Modes and Causes for Swing and Lift Type Check Valves.
Prior to the recent work performed by Oak Ridge National Laboratory (ORNL)relative to nuclear industry check valve performance, no information was readily available regarding the failure characteristics of check valves based on valve type (e.g., swing check, lift check). Although it had been recognized by component experts that the two most significant factors in determining check valve performance were valve design (i.e., type) and operating conditions, no industry data was available relative to the former. In cooperation with the Nuclear Industry Check Valve Group (NIC), ORNL has reviewed and analyzed check valve failures from the Institute of Nuclear Power Operations` (INPOs`) Nuclear Plant Reliability Database System (NPRDS) according to several parameters,including valve type. Since the valve type identification is not inherently included within the NPRDS engineering record for each component, ORNL had to rely upon input from NIC, valve manufacturers, and catalogs to supply the missing information. As a result of this effort, approximately 77% of the check valve failures occurring during the 1991-1996 study period and nearly 62% of the overall installed population were identified according to type. This data provided the basis to perform previously unavailable cross-correlations between parameters such as valve type versus failure mode and failure …
Date:
December 31, 1997
Creator:
McElhaney, K. L.
Object Type:
Article
System:
The UNT Digital Library
FB-line neutron multiplicity counter operation manual
This manual describes the design features, performance, and operating characteristics for the FB-Line Neutron Multiplicity counter (FBLNMC). The FBLNMC counts neutron multiplicities to quantitatively assay plutonium in many forms, including impure scrap and waste. Monte Carlo neutronic calculations were used to design the high-efficiency (57%) detector that has 113 {sup 3}He tubes in a high-density polyethylene body. The new derandomizer circuit is included in the design to reduce deadtime. The FBLNMC can be applied to plutonium masses in the range from a few tens of grams to 5 kg; both conventional coincidence counting and multiplicity counting can be used as appropriate. This manual gives the performance data and preliminary calibration parameters for the FBLNMC.
Date:
December 31, 1997
Creator:
Langner, D. G.; Sweet, M. R.; Salazar, S. D. & Kroncke, K. E.
Object Type:
Report
System:
The UNT Digital Library
Field experience with a new performance characterization procedure for photovoltaic arrays
As photovoltaic systems become larger and more numerous, improved methods are needed for testing and modeling their performance. Test methods that successfully separate the interacting, time-of-day dependent influences of solar irradiance, operating temperature, solar spectrum, and solar angle-of-incidence have now been developed. These test methods have resulted in a new array performance model that is reasonably simple, yet accurately predicts performance for all operating conditions. This paper describes the new model, outdoor tests required to implement it, results of field tests for five arrays of different technologies, and the evolution of the model into a numerical tool for designing and sizing photovoltaic arrays based on annual energy production.
Date:
December 31, 1997
Creator:
King, David L.; Kratochvil, Jay A. & Boyson, William E.
Object Type:
Article
System:
The UNT Digital Library
Field test results of the physical solvent N-Formyl morpholine for gas treating applications
The Institute of Gas Technology (IGT) is developing gas processing technology that will reduce gas processing costs for current production and allow subquality gas to be economically produced that would have been otherwise, not produced. The experimental program has primarily focused on the evaluation of N-Formyl Morpholine (NFM) as a physical solvent for the cost-effective upgrading of subquality natural gas to pipeline quality. The selection of NFM for this program was based on previous work conducted by IGT in the selective removal of hydrogen sulfide, and carbon dioxide from coal gasifier effluents. That work showed that the use of NFM resulted in a significant cost advantage over 107 other solvents for that application. The project approach for the development of NFM process has been divided into following main categories: obtain vapor-liquid equilibrium, physical properties and additional published literature data; obtain mass-transfer coefficients using 2 inch absorber/stripper apparatus and calculate equation of state parameters and binary interaction parameters using VLE data; develop a gas processing model using Aspen Plus simulation program and evaluate economic advantages of the NFM process compared to commercial physical solvent; and design a pilot plant skid mounted field test unit and conduct field test experiments.
Date:
December 31, 1997
Creator:
Palla, N. & Lee, A.L.
Object Type:
Article
System:
The UNT Digital Library
Fifth national stakeholder workshop summary report
On April 9--11, 1997, the Department of Energy`s Office of Worker and Community Transition convened its fifth National Stakeholder Workshop. The workshop addressed a wide range of work force restructuring and community transition issues critical to the future success of the Department. Two important elements of the meeting were: (1) reviewing progress made on the challenges identified during the March 1996f stakeholder`s meeting in Atlanta, Georgia; and (2) identifying areas that needed priority attention during the early months of the second Clinton Administration. The format of the Workshop included several plenary sessions and a number of small group discussion sessions. The small group sessions focused on topics related to labor issues, work force restructuring, work force planning, community transition, and employee concerns. The sessions provided a wide range of views on worker and community transition issues. The workshop included presentations on the following topics: Welcome and introductions; Opening remarks; Community reuse organizations: recent accomplishments; Privatization: policy, practice and potential pitfalls; Department of Energy`s integrated training initiatives; Congressional perspective on work force restructuring; and, Privatization and the Ten Year Plan.
Date:
December 31, 1997
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Fifth SIAM conference on geometric design 97: Final program and abstracts. Final technical report
The meeting was divided into the following sessions: (1) CAD/CAM; (2) Curve/Surface Design; (3) Geometric Algorithms; (4) Multiresolution Methods; (5) Robotics; (6) Solid Modeling; and (7) Visualization. This report contains the abstracts of papers presented at the meeting. Proceding the conference there was a short course entitled ``Wavelets for Geometric Modeling and Computer Graphics``.
Date:
December 31, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Final performance report for Project JEM
Project JEM (Jarvis Enhancement of Males) is a pre-college program directed toward stimulating disadvantaged, talented African American males in grades four, five, and six to attend college and major in mathematics, science, computer science, or related technical areas needed by the US Department of Energy. Twenty young African American male students were recruited from Gladewater Independent School District (ISD), Longview ISD, Hawkins ISD, Tyler ISD, Winona ISD and big Sandy ISD. Students enrolled in the program range from ages 10 to 13 and are in grades four, five and six. Student participants in the 1997 Project JEM Program attended Saturday Academy sessions and a four week intensive, summer residential program. The information here provides a synopsis of the activities which were conducted through each program component.
Date:
December 31, 1997
Creator:
McKinney, M.J. & Jenkins, S.
Object Type:
Report
System:
The UNT Digital Library
Fine-scale oscillatory banding in otoliths from arctic charr (Salveninus alpinus) and pike (Esox lucius)
Transmission electron microscopy of otoliths from the inner ear of arctic charr and pike has revealed the presence of fine banding on the scale of several nanometers. The thickness of the bands was observed to vary in different portions of the sample, and some areas were not banded. EDS analysis could not detect chemical differences within the bands, but electron diffraction showed that the crystallographic orientation of the bands is related by a lattice mismatch. Previously, banding on the scale of 50 to 100 microns was observed by SEM in otoliths from arctic charr and was attributed to seasonal variations in growth. The fine-scale banding observed in this study, however, is unlikely to represent a daily variation. Electron diffraction from the pike samples shows that the material is composed of CaCO{sub 3} having the both the vaterite and aragonite structure, and hydrous CaCO{sub 3} was also observed. The large-scale banding previously identified by SEM was not observed in the TEM despite attempts to intersect the boundaries of the micron-sized layers. The interaction of the electron beam with the sample material was investigated by conducting several electron-irradiation experiments. The electron beam was observed to interact strongly with the sample and caused …
Date:
December 31, 1997
Creator:
Meldrum, A. & Halden, N. M.
Object Type:
Article
System:
The UNT Digital Library
First-principles exchange interactions between ferro and antiferromagnetic films: Co on NiMn, a case study
Heisenberg exchange parameters at the interface of antiferromagnetic NiMn with ferromagnetic Co are calculated from first-principles. The authors use a layer version of the Korringa-Kohn-Rostocker multiple scattering approach and an expression, which is based on the expansion of the band energy, to calculate the exchange parameters from the underlying electronic structure. For bulk systems, the parameter sets yield Curie temperatures that are in good agreement with experimental values. In the interface region, the inter-layer interactions in NiMn change significantly compared to the bulk while the intra-layer interactions are almost unchanged.
Date:
December 31, 1997
Creator:
Schulthess, T. C. & Butler, W. H.
Object Type:
Article
System:
The UNT Digital Library
Fluid Dynamics of Pressurized, Entrained Coal Gasifiers
Pressurized, entrained gasification is a promising new technology for the clean and efficient combustion of coal. Its principle is to operate a coal gasifier at a high inlet gas velocity to increase the inflow of reactants, and at an elevated pressure to raise the overall efficiency of the process. Unfortunately, because of the extraordinary difficulties involved in performing measurements in hot, pressurized, high-velocity pilot plants, its fluid dynamics are largely unknown. Thus the designer cannot predict with certainty crucial phenomena like erosion, heat transfer and solid capture. In this context, we are conducting a study of the fluid dynamics of Pressurized Entrained Coal Gasifiers (PECGs). The idea is to simulate the flows in generic industrial PECGs using dimensional similitude. To this end, we employ a unique entrained gas-solid flow facility with the flexibility to recycle -rather than discard- gases other than air. By matching five dimensionless parameters, suspensions in mixtures of helium, carbon dioxide and sulfur hexafluoride simulate the effects of pressure and scale-up on the fluid dynamics of PECGS. Because it operates under cold, atmospheric conditions, the laboratory facility is ideal for detailed measurements. These activities are conducted with Air Products & Chemicals, Inc., which is a member of …
Date:
December 31, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Fossil fuel conversion -- Measurement and modeling. Topical report, September 14, 1993--June 30, 1997
Progress is described on the following tasks: Fixed-bed devolatilization processes; Fixed-bed combustion and gasification processes; Physical processes in transport reactors; Chemical processes in transport reactors; Advanced fixed-bed model development and evaluation; Advanced two-dimensional transport reactor model development and evaluation; Modeling of gas phase combustion; Modeling of fluidized bed systems; Advanced fixed-bed code application and implementation; Advanced two-dimensional transport gasification code applications and implementation; Modeling of fluidized-bed system applications and implementation; and Applications of ACERC combustion and gasification codes and AFR diagnostic capabilities to systems of interest to METC.
Date:
December 31, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Fourth SIAM conference on mathematical and computational issues in the geosciences: Final program and abstracts
The conference focused on computational and modeling issues in the geosciences. Of the geosciences, problems associated with phenomena occurring in the earth`s subsurface were best represented. Topics in this area included petroleum recovery, ground water contamination and remediation, seismic imaging, parameter estimation, upscaling, geostatistical heterogeneity, reservoir and aquifer characterization, optimal well placement and pumping strategies, and geochemistry. Additional sessions were devoted to the atmosphere, surface water and oceans. The central mathematical themes included computational algorithms and numerical analysis, parallel computing, mathematical analysis of partial differential equations, statistical and stochastic methods, optimization, inversion, homogenization and renormalization. The problem areas discussed at this conference are of considerable national importance, with the increasing importance of environmental issues, global change, remediation of waste sites, declining domestic energy sources and an increasing reliance on producing the most out of established oil reservoirs.
Date:
December 31, 1997
Creator:
unknown
Object Type:
Article
System:
The UNT Digital Library
Fractal Analysis of Fracture Systems: Topical report, September 3, 1996
A fractal analysis of outcrop fracture patterns was undertaken in the Valley and Ridge study area. Use of pavement style investigations such as those conducted by Barton and Hsieh (1989) was not a feasible form of analysis in either Appalachian study areas. Large exposures of bedding plane surfaces are limited, particularly at the Plateau site; hence, fracture studies were concentrated in the Middle and Elkhorn Mountain areas of the Valley and Ridge. The area is complexly deformed, which presented difficulty in the design of a controlled experiment. While bedding plane exposures were found, it was not possible to find comparable exposures of the same lithologic unit in the different structural areas represented at the site. In such instances, therefore, lithologic factors could not be separated from structural factors in the interpretation of variations in fractal dimension. Comparisons of fractal behavior in a common lithologic interval were possible to some extent using one-dimensional analysis of bed-normal fracture plane intersections. However, even in this case, the distribution of exposure was the limiting factor.
Date:
December 31, 1997
Creator:
Wilson, T.
Object Type:
Report
System:
The UNT Digital Library
Framework on an On-Line Regulations Expert Permit Server
This is a cooperative project between the Oil and Gas Compact Commission (OIGCC) and the oil and gas industry to use computerized communication technology as a means of providing information from state agencies. A major effort is the development of a framework for an on-line regulatory compliance and permit server system. Other aspects included provide feedback to state regulatory agencies with recommendations suggesting where procedures or regulations could be simplified or streamlined, identifying overlapping regulations, and surveying the needs of the IOGCC states in the area of emerging issues where sharing of regulatory procedures among the states might be useful.
Date:
December 31, 1997
Creator:
Hansen, Christine
Object Type:
Report
System:
The UNT Digital Library
Frontiers of Nuclear Structure
Current developments in nuclear structure at the `limits` are discussed. The studies of nuclear behavior at extreme conditions provide us with invaluable information about the nature of the nuclear interaction and nucleonic correlations at various energy-distance scales. In this talk frontiers of nuclear structure are briefly reviewed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.
Date:
December 31, 1997
Creator:
Nazarewicz, Witold
Object Type:
Article
System:
The UNT Digital Library
Fuel cells for transportation program: FY1997 national laboratory annual report
The Department of Energy (DOE) Fuel Cells for Transportation Program is structured to effectively implement the research and development (R and D) required for highly efficient, low or zero emission fuel cell power systems to be a viable replacement for the internal combustion engine in automobiles. The Program is part of the Partnership for a New Generation of Vehicles (PNGV), a government-industry initiative aimed at development of an 80 mile-per-gallon vehicle. This Annual Report summarizes the technical accomplishments of the laboratories during 1997. Participants include: Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), Pacific Northwest National Laboratory (PNNL), and the National Renewable Energy Laboratory (NREL). During 1997, the laboratory R and D included one project on solid oxide fuel cells; this project has since been terminated to focus Department resources on PEM fuel cells. The technical component of this report is divided into five key areas: fuel cell stack research and development; fuel processing; fuel cell modeling, testing, and evaluation; direct methanol PEM fuel cells; and solid oxide fuel cells.
Date:
December 31, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
The Functional Genomics Initiative at Oak Ridge National Laboratory
The Functional Genomics Initiative at the Oak Ridge National Laboratory integrates outstanding capabilities in mouse genetics, bioinformatics, and instrumentation. The 50 year investment by the DOE in mouse genetics/mutagenesis has created a one-of-a-kind resource for generating mutations and understanding their biological consequences. It is generally accepted that, through the mouse as a surrogate for human biology, we will come to understand the function of human genes. In addition to this world class program in mammalian genetics, ORNL has also been a world leader in developing bioinformatics tools for the analysis, management and visualization of genomic data. Combining this expertise with new instrumentation technologies will provide a unique capability to understand the consequences of mutations in the mouse at both the organism and molecular levels. The goal of the Functional Genomics Initiative is to develop the technology and methodology necessary to understand gene function on a genomic scale and apply these technologies to megabase regions of the human genome. The effort is scoped so as to create an effective and powerful resource for functional genomics. ORNL is partnering with the Joint Genome Institute and other large scale sequencing centers to sequence several multimegabase regions of both human and mouse genomic DNA, …
Date:
December 31, 1997
Creator:
Johnson, Dabney; Justice, Monica; Beattle, Ken; Buchanan, Michelle; Ramsey, Michael; Ramsey, Rose et al.
Object Type:
Article
System:
The UNT Digital Library
The Future of the National Laboratories
The policy debate that has surrounded the national laboratories of the Department of Energy since the end of the Cold War has been very confusing. Initially, with the passage of the National Competitiveness Technology Transfer Act of 1989, the laboratories were encouraged to form cooperative arrangements with industry to maintain their technology base and give a boost for U.S. industrial competitiveness. But in the 104th Congress, technology transfer programs were severely constrained.
Date:
December 31, 1997
Creator:
Hartley, D.
Object Type:
Article
System:
The UNT Digital Library
Galvanneal Thermometry with a Thermographic Phosphor System
The accurate determination of temperature of galvanneal sheet emerging from a zinc bath is a challenging process measurement. The line moves at high speeds, up to 900 feet per minute, and the emissivity varies widely as it moves through the radio-frequency (RF) induction heating ovens and subsequently cools. This presents a great source of error if the pyrometric approach is used since the accuracy is sensitive to emissivity variation. This problem has been circumvented by an approach described here which uses a thermally sensitive phosphor technique for temperature measurement. For this, a small amount of a phosphor material is deposited on the liquid surface of the sheet. When the small layer of phosphor moves to the measurement station, it is illuminated by a short laser pulse which produces fluorescence from the material. The time dependence of the fluorescence indicates the temperature. Introduction of the microgram quantities of material has been shown to have no detrimental impact on product quality! This presentation describes a phosphor-based system for measuring temperature on a galvanneal manufacturing line. To date, measurements with an accuracy of +/- 5 deg F have been made at National Steel=s Midwest facility. This effort is a part of the Advanced …
Date:
December 31, 1997
Creator:
Manges, W.W., Allison, S.W.
Object Type:
Article
System:
The UNT Digital Library
Geohydrology and evapotranspiration at Franklin Lake playa, Inyo County, California
Franklin Lake playa is one of the principal discharge areas of the Furnace Creek Ranch-Alkali Flat ground-water-flow system in southern Nevada and adjacent California. Yucca Mountain, Nevada, located within this flow system, is being evaluated by the US Department of Energy to determine its suitability as a potential site for a high-level nuclear-waste repository. To assist the U.S. Department of Energy with its evaluation of the Yucca Mountain site, the US Geological Survey developed a parameter-estimation model of the Furnace Creek Ranch-Alkali Flat ground-water-flow system. Results from sensitivity analyses made using the parameter-estimation model indicated that simulated rates of evapotranspiration at Franklin Lake playa had the largest effect on the calculation of transmissivity values at Yucca Mountain of all the model-boundary conditions and, therefore, that evapotranspiration required careful definition.
Date:
December 31, 1997
Creator:
Czarnecki, J. B.
Object Type:
Report
System:
The UNT Digital Library