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Fracture and fatigue resistance of Mo-Si-B alloys for ultrahigh-temperature structural applications (open access)

Fracture and fatigue resistance of Mo-Si-B alloys for ultrahigh-temperature structural applications

Fracture and fatigue-crack growth properties are examined for a series of Mo-Mo3Si-Mo5SiB2 containing alloys, which utilize a continuous a-Mo matrix to achieve unprecedented room-temperature fracture resistance (>20 MPaAm). Mechanistically, these properties are explained in terms of toughening by crack trapping and crack bridging by the more ductile a-Mo phase.
Date: August 29, 2003
Creator: Kruzic, J. J.; Schneibel, J. H. & Ritchie, R. O.
System: The UNT Digital Library
Stochastically generating tree diameter lists to populate forest stands based on the linkage variables, forest type and stand age. (open access)

Stochastically generating tree diameter lists to populate forest stands based on the linkage variables, forest type and stand age.

Forest inventory data were used to develop a stand-age-driven, stochastic predictor of unit-area, frequency-weighted lists of breast high tree diameters (DBH). The average of mean statistics from 40-simulation prediction sets of an independent 78-plot validation dataset differed from the observed validation means by 0.5 cm for DBH, and by 12 trees/h for density. The 40-simulation average of standard deviation, quartile range, maximum value and minimum value differed from the validation dataset, respectively, by 0.3, 1.3, 0.6 and 1.5 cm for DBH, and 10, 42, 29, and 54 trees/h for density. In addition, test statistics were also computed individually for each of the 40 single simulations of the 78-plot validation dataset. In all cases, the test statistics supported the null hypothesis of no difference between simulated and observed DBH lists. When power of these hypothesis test statistics was set to 80%, the calculated minimum detectable differences were still reasonably small at 2.7 cm for mean DBH and 90 trees/h for stocking. Also, the shape and dispersion of simulated mean-DBH/density scatter graphs were similar to the same scatter graph from the observed, validation dataset.
Date: August 31, 2003
Creator: Parresol, B. R. & Lloyd, F. T.
System: The UNT Digital Library
Regional cooperation in energy efficiency standard-setting and labeling in North America (open access)

Regional cooperation in energy efficiency standard-setting and labeling in North America

The North American Energy Working Group (NAEWG) was established in 2001 by the governments of Canada, Mexico, and the United States. The goals of NAEWG are to foster communication and cooperation on energy-related matters of common interest, and to enhance North American energy trade and interconnections consistent with the goal of sustainable development, for the benefit of all three countries. At its outset, NAEWG established teams to address different aspects of the energy sector. One, the Energy Efficiency Expert Group, undertook activity in three areas: (1) analyzing commonalities and differences in the test procedures of Canada, Mexico, and the United States, and identifying specific products for which the three countries might consider harmonization; (2) exploring possibilities for increased mutual recognition of laboratory test results; and (3) looking at possibilities for enhanced cooperation in the Energy Star voluntary endorsement labeling program. To support NAEWG's Expert Group on Energy Efficiency (NAEWG-EE), USDOE commissioned Lawrence Berkeley National Laboratory, representing the Collaborative Labeling and Appliance Standards Program (CLASP), to prepare a resource document comparing current standards, labels, and test procedure regulations in Canada, Mexico, and the United States. The resulting document identified 46 energy-using products for which at least one of the three countries …
Date: August 4, 2003
Creator: Wiel, Stephen & Van Wie McGrory, Laura
System: The UNT Digital Library
Selective Catalytic Reduction of Diesel Engine Nox Emissions Using Ethanol as a Reductant (open access)

Selective Catalytic Reduction of Diesel Engine Nox Emissions Using Ethanol as a Reductant

NOx emissions from a heavy-duty diesel engine were reduced by more than 90% and 80% utilizing a full-scale ethanol-SCR system for space velocities of 21000/h and 57000/h respectively. These results were achieved for catalyst temperatures between 360 and 400 C and for C1:NOx ratios of 4-6. The SCR process appears to rapidly convert ethanol to acetaldehyde, which subsequently slipped past the catalyst at appreciable levels at a space velocity of 57000/h. Ammonia and N2O were produced during conversion; the concentrations of each were higher for the low space velocity condition. However, the concentration of N2O did not exceed 10 ppm. In contrast to other catalyst technologies, NOx reduction appeared to be enhanced by initial catalyst aging, with the presumed mechanism being sulfate accumulation within the catalyst. A concept for utilizing ethanol (distilled from an E-diesel fuel) as the SCR reductant was demonstrated.
Date: August 24, 2003
Creator: Kass, M. D.; Thomas, J. F.; Lewis, S. A., Sr.; Storey, J. M.; Domingo, N. & Graves, R. L.
System: The UNT Digital Library
SCR SYSTEMS FOR HEAVY DUTY TRUCKS: PROGRESS TOWARDS MEETING EURO 4 EMISSION STANDARDS IN 2005 (open access)

SCR SYSTEMS FOR HEAVY DUTY TRUCKS: PROGRESS TOWARDS MEETING EURO 4 EMISSION STANDARDS IN 2005

Emissions of diesel engines contain some components, which support the generation of smog and which are classified hazardous. Exhaust gas aftertreatment is a powerful tool to reduce the NOx and Particulate emissions. The NOx-emission can be reduced by the SCR technology. SCR stands for Selective Catalytic Reduction. A reduction agent has to be injected into the exhaust upstream of a catalyst. On the catalyst the NOx is reduced to N2 (Nitrogen) and H2O (Water). This catalytic process was developed in Japan about 30 years ago to reduce the NOx emission of coal-fired power plants. The first reduction agent used was anhydrous ammonia (NH3). SCR technology was used with diesel engines starting mid of the 80s. First applications were stationary operating generator-sets. In 1991 a joint development between DaimlerChrysler, MAN, IVECO and Siemens was started to use SCR technology for the reduction of heavy duty trucks. Several fleet tests demonstrated the durability of the systems. To day, SCR technology is the most promising technology to fulfill the new European Regulations EURO 4 and EURO 5 being effective Oct. 2005 and Oct. 2008. The efficient NOx reduction of the catalyst allows an engine calibration for low fuel consumption. DaimlerChrysler decided to use …
Date: August 24, 2003
Creator: Frank, W; Huethwohl, G & Maurer, B
System: The UNT Digital Library
Simulation of a D-T neutron source for neutron scattering experiments (open access)

Simulation of a D-T neutron source for neutron scattering experiments

None
Date: August 12, 2003
Creator: Lou, T. P.; Ludewigt, B. A.; Vujic, J. L. & Leung, K. N.
System: The UNT Digital Library
Who should administer energy efficiency programs? (open access)

Who should administer energy efficiency programs?

The restructuring of the U.S. electricity industry created a crisis for ratepayer-funded energy-efficiency programs. This paper briefly describes the reasons for the crisis and some of its consequences. Then the paper focuses on issues related to program administration and discusses the relative merits of entities-utilities, state agencies, and non-profit corporations-that might be administrators. Four criteria are developed for choosing among program administration options: Compatibility with public policy goals, effectiveness of the incentive structure, ability to realize economies of scale and scope, and contribution to the development of an energy-efficiency infrastructure. We examine one region, the Pacific Northwest, and three states, New York, Vermont, and Connecticut, which have made successful transitions to new governance and/or administration structures. Attention is also given to California where large-scale energy-efficiency programs have continued to operate, despite the fact that many of the key governance/administration issues remain unresolved.We observe that no single administrative structure for energy-efficiency programs has yet emerged in the US that is clearly superior to all of the other alternatives. We conclude that this is not likely to happen soon for three reasons. First, policy environments differ significantly among the states. Second, the structure and regulation of the electric utility industry differs among …
Date: August 1, 2003
Creator: Blumstein, Carl; Goldman, Charles & Barbose, Galen
System: The UNT Digital Library
ENSURING THE AVAILABILITY AND RELIABILITY OF UREA DOSING FOR ON-ROAD AND NON-ROAD (open access)

ENSURING THE AVAILABILITY AND RELIABILITY OF UREA DOSING FOR ON-ROAD AND NON-ROAD

The purpose of this presentation is to address two important issues. The first issue is nationwide availability of urea. The second is assurance by the engine maker that the engine cannot operate without urea. In regard to the first issue, North American urea production can support SCR needs for the Heavy Duty truck industry. The existing distribution methods, pathways and technology could be utilized for urea supply with no new invention required. Urea usage and storage capacity on vehicles would support long distances between tank refills, as SCR could be initially rolled out with a limited infrastructure. The price of urea should be less than diesel fuel and urea SCR should have a fuel economy advantage over competing technologies. It can be in place by 2007. In regard to the second issue, sensor technology exists to monitor urea tank level and verify that the fluid in the tank is urea. NOx sensors are available to monitor tailpipe NOx, ensuring the entire SCR system is functioning properly, and inferring that urea is in the system. The monitoring system could be used to monitor compliance, record faults, and initiate enforcement actions as necessary. The monitoring system could initiate actions to encourage compliance.
Date: August 24, 2003
Creator: Barton, G & Lonsdale, B
System: The UNT Digital Library
Transient, Real-Time, Particulate Emission Measurements in Diesel Engines (open access)

Transient, Real-Time, Particulate Emission Measurements in Diesel Engines

This paper reports our efforts to develop an instrument, TG-1, to measure particulate emissions from diesel engines in real-time. TG-1 while based on laser-induced incandescence allows measurements at 10 Hz on typical engine exhausts. Using such an instrument, measurements were performed in the exhaust of a 1.7L Mercedes Benz engine coupled to a low inertia dynamometer. Comparative measurements performed under engine steady state conditions showed the instrument to agree within {+-}12% of measurements performed with an SMPS. Moreover, the instrument had far better time response and time resolution than a TEOM{reg_sign} 1105. Also, TG-1 appears to surpass the shortcomings of the TEOM instrument, i.e., of yielding negative values under certain engine conditions and, being sensitive to external vibration.
Date: August 24, 2003
Creator: Gupta, S.; Shih, J.; Hillman, G.; Sekar, R.; Graze, R.; Shimpi, S. et al.
System: The UNT Digital Library
Progress Toward Fully Noninductive, High Beta Discharges in Diii-D (open access)

Progress Toward Fully Noninductive, High Beta Discharges in Diii-D

OAK-B135 Advanced Tokamak (AT) research in DIII-D focuses on developing a scientific basis for steady-state, high performance operation. For optimal performance, these experiments routinely operate with {beta} above the n = 1 no-wall limit, enabled by active feed-back control. The ideal wall {beta} limit is optimized by modifying the plasma shape, current and pressure profile. Present DIII-D AT experiments operate with f{sub BS} {approx} 50%-60%, with a long-term goal of {approx} 90%. Additional current is provided by neutral beam and electron cyclotron current drive, the latter being localized well away from the magnetic axis ({rho} {approx} 0.4-0.5). Guided by integrated modeling, recent experiments have produced discharges with {beta} {approx} 3%, {beta}{sub N} {approx} 3, f{sub BS} {approx} 55% and noninductive fraction f{sub NI} {approx} 90%. Additional control is anticipated using fast wave current drive to control the central current density.
Date: August 1, 2003
Creator: Greenfield, C. M.; Ferron, J. R.; Murakami, M.; Wade, M. R.; Budny, R. V.; Burrell, K. H. et al.
System: The UNT Digital Library
LUX - A Recirculating Linac-Based Ultrafast X-Ray Source (open access)

LUX - A Recirculating Linac-Based Ultrafast X-Ray Source

We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV range, and is followed by four passes through a 700 MeV recirculating linac. Ultrafast hard x-ray pulses are obtained by a combination of electron bunch manipulation, transverse temporal correlation of the electrons, and x-ray pulse compression. EUV and soft x-ray pulses as short as 10 fs are generated in a harmonic-cascade free electron laser scheme.
Date: August 1, 2003
Creator: Corlett, J. N.; Barletta, W. A.; DeSantis, S.; Doolittle, L.; Fawley, W. M.; Green, M. A. et al.
System: The UNT Digital Library
Observation of Microwave Induced Zero-Conductance State in Corbino Rings of a Two-Dimensional Electron System (open access)

Observation of Microwave Induced Zero-Conductance State in Corbino Rings of a Two-Dimensional Electron System

Using Corbino samples they have observed oscillatory dc conductance in a high-mobility two-dimensional electron system when it is subjected to crossed microwave and magnetic fields. At the strongest of the oscillation minima the conductance is found to be vanishingly small, indicating a macroscopic insulating state associated with this minimum. With increasing voltage bias, a crossover from Ohmic to electron-heating regime is observed.
Date: August 29, 2003
Creator: Yang, C. L.; Pfeiffer, M. A.; Knuttila, T. A.; Du, R. R.; Pfeiffer,, L. N. & West, K. W.
System: The UNT Digital Library
USE OF A DIESEL FUEL PROCESSOR FOR RAPID AND EFFICIENT REGENERATION OF SINGLE LEG NOX ADSORBER SYSTEMS (open access)

USE OF A DIESEL FUEL PROCESSOR FOR RAPID AND EFFICIENT REGENERATION OF SINGLE LEG NOX ADSORBER SYSTEMS

Lean NOx adsorber systems are one of the primary candidate technologies for the control of NOx from diesel engines to meet the 2007-2010 US emissions regulations, which require a 90% reduction of NOx from the 2004 regulations. Several of the technical challenges facing this technology are regeneration at low exhaust temperatures and the efficient use of diesel fuel to minimize fuel penalty. A diesel processor system has been developed and tested in a single leg NOx adsorber configuration on a diesel engine test stand. During NOx adsorber regeneration, this fuel processor system performs reduces the exhaust O2 level to zero and efficiently processes the diesel fuel to H2 and CO. Combined with a Nox adsorber catalyst, this system has demonstrated NOx reduction above 90%, regeneration of the NOx adsorber H2/CO pulses as short as 1 second and fuel penalties in the 3 to 4% range at 50% load. This fuel processor system can also be used to provide the desulfation cycle required with sulfur containing fuels as well as providing thermal management for PM filter regeneration.
Date: August 24, 2003
Creator: Betta, R; Cizeron, J; Sheridan, D & Davis, T
System: The UNT Digital Library
QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION (open access)

QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are …
Date: August 1, 2003
Creator: West, W. P.; Burrell, K. H.; Degrassie, J. S.; Doyle, E. J.; Greenfield, C. M.; Lasnier, C. J. et al.
System: The UNT Digital Library
Non-thermal plasma based technologies for the after-treatment of automotive exhaust particulates and marine diesel exhaust NOx (open access)

Non-thermal plasma based technologies for the after-treatment of automotive exhaust particulates and marine diesel exhaust NOx

The trend in environmental legislation is such that primary engine modifications will not be sufficient to meet all future emissions requirements and exhaust aftertreatment technologies will need to be employed. One potential solution that is well placed to meet those requirements is non-thermal plasma technology. This paper will describe our work with some of our partners in the development of a plasma based diesel particulate filter (DPF) and plasma assisted catalytic reduction (PACR) for NOx removal. This paper describes the development of non-thermal plasma technology for the aftertreatment of particulates from a passenger car engine and NOx from a marine diesel exhaust application.
Date: August 24, 2003
Creator: McAdams, R.; Beech, P.; Gillespie, R.; Guy, C.; Jones, S.; Liddell, T. et al.
System: The UNT Digital Library
Historical background: Why is it important to improve automated particle selection methods? (open access)

Historical background: Why is it important to improve automated particle selection methods?

A current trend in single-particle electron microscopy is to compute three-dimensional reconstructions with ever-increasing numbers of particles in the data sets. Since manual--or even semi-automated--selection of particles represents a major bottleneck when the data set exceeds several thousand particles, there is growing interest in developing automatic methods for selecting images of individual particles. Except in special cases, however, it has proven difficult to achieve the degree of efficiency and reliability that would make fully automated particle selection a useful tool. The simplest methods such as cross correlation (i.e., matched filtering) do not perform well enough to be used for fully automated particle selection. Geometric properties (area, perimeter-to-area ratio, etc.) and the integrated ''mass'' of candidate particles are additional factors that could improve automated particle selection if suitable methods of contouring particles could be developed. Another suggestion is that data be always collected as pairs of images, the first taken at low defocus (to capture information at the highest possible resolution) and the second at very high defocus (to improve the visibility of the particle). Finally, it is emphasized that well-annotated, open-access data sets need to be established in order to encourage the further development and validation of methods for automated …
Date: August 14, 2003
Creator: Glaeser, Robert M.
System: The UNT Digital Library
Multiphase Reactive Transport modeling of Stable Isotope Fractionation of Infiltrating Unsaturated Zone Pore Water and Vapor Using TOUGHREACT (open access)

Multiphase Reactive Transport modeling of Stable Isotope Fractionation of Infiltrating Unsaturated Zone Pore Water and Vapor Using TOUGHREACT

Numerical simulations of transport and isotope fractionation provide a method to quantitatively interpret vadose zone pore water stable isotope depth profiles based on soil properties, climatic conditions, and infiltration. We incorporate the temperature-dependent equilibration of stable isotopic species between water and water vapor, and their differing diffusive transport properties into the thermodynamic database of the reactive transport code TOUGHREACT. These simulations are used to illustrate the evolution of stable isotope profiles in semiarid regions where recharge during wet seasons disturbs the drying profile traditionally associated with vadose zone pore waters. Alternating wet and dry seasons lead to annual fluctuations in moisture content, capillary pressure, and stable isotope compositions in the vadose zone. Periodic infiltration models capture the effects of seasonal increases in precipitation and predict stable isotope profiles that are distinct from those observed under drying (zero infiltration) conditions. After infiltration, evaporation causes a shift to higher 18O and D values, which are preserved in the deeper pore waters. The magnitude of the isotopic composition shift preserved in deep vadose zone pore waters varies inversely with the rate of infiltration.
Date: August 28, 2003
Creator: Singleton, Michael J.; Sonnenthal, Eric L.; Conrad, Mark E. & DePaolo, Donald J.
System: The UNT Digital Library
POTENTIAL THERMOELECTRIC APPLICATIONS IN DIESEL VEHICLES (open access)

POTENTIAL THERMOELECTRIC APPLICATIONS IN DIESEL VEHICLES

Novel thermodynamic cycles developed by BSST provide improvements by factors of approximately 2 in cooling, heating and power generation efficiency of solid-state thermoelectric systems. The currently available BSST technology is being evaluated in automotive development programs for important new applications. Thermoelectric materials are likely to become available that further increase performance by a comparable factor. These major advancements should allow the use of thermoelectric systems in new applications that have the prospect of contributing to emissions reduction, fuel economy, and improved user comfort. Potential applications of thermoelectrics in diesel vehicles are identified and discussed. As a case in point, the history and status of the Climate Controlled Seat (CCS) system from Amerigon, the parent of BSST, is presented. CCS is the most successful and highest production volume thermoelectric system in vehicles today. As a second example, the results of recent analyses on electric power generation from vehicle waste heat are discussed. Conclusions are drawn as to the practicality of waste power generation systems that incorporate BSST's thermodynamic cycle and advanced thermoelectric materials.
Date: August 24, 2003
Creator: Crane, D
System: The UNT Digital Library
Oxidative Mineralization and Characterization of Polyvinyl Alcohol Solutions for Wastewater Treatment (open access)

Oxidative Mineralization and Characterization of Polyvinyl Alcohol Solutions for Wastewater Treatment

Photochemical and ultrasonic treatment of polyvinyl alcohol (PVA), derived from PVA fabric material, with hydrogen peroxide was evaluated as a primary method for PVA mineralization into simpler organic molecules. PVA-based waste streams have been found to be compatible with nuclear process wastewater treatment facilities only when solubilized PVA is more than 90 percent mineralized with hydrogen peroxide. No undesirable solid particles are formed with other nuclear process liquid waste when they are mixed, pH adjusted, evaporated and blended with this type of oxidized PVA waste streams. The presence of oxidized PVA in a typical nuclear process wastewater has been found to have no detrimental effect on the efficiency of ion exchange resins, inorganic, and precipitation agents used for the removal of radionuclides from nuclear waste streams. The disappearance of PVA solution in hydrogen peroxide with ultrasonic/ ultraviolet irradiation treatment was characterized by pseudo-first-order reaction kinetics. Radioactive waste contaminated PVA fabric can be solubilized and mineralized to produce processible liquid waste, hence, no bulky solid waste disposal cost can be incurred and the radionuclides can be effectively recovered. Therefore, PVA fabric materials can be considered as an effective substitute for cellulose fabrics that are currently used in radioactive waste decontamination processes.
Date: August 7, 2003
Creator: Oji, L.N.
System: The UNT Digital Library
DEVELOPMENT IN THE DIII-D TOKAMAK OF HYBRID OPERATION SCENARIOS FOR BURNING PLASMA EXPERIMENTS (open access)

DEVELOPMENT IN THE DIII-D TOKAMAK OF HYBRID OPERATION SCENARIOS FOR BURNING PLASMA EXPERIMENTS

OAK-B135 The basic parameters of proposed burning plasma experiments such as ITER and FIRE have been chosen based on analysis of multi-machine databases of confinement, stability, and divertor operation. given these specifications, it is of interest to run discharges in present-day machines such as DIII-D to verify the design basis and evaluate the margin available to achieve the mission goals. it is especially important to operate discharges which are stationary with respect to the current relaxation time scale ({tau}{sub R}) since it is well-known that higher performance can be achieved transiently. Attention has been focused on validating the baseline scenario for diverted machines--ELMing H-mode discharges with q{sub 95} = 3 with sawteeth. However, there is also interest in the ITER program to assess the feasibility of operating the tokamak in a mode to maximize the neutron fluence for the purpose of testing the design of various components critical to the nuclear fuel cycle and energy conversion systems in a fusion power plant. It was originally envisioned that these discharges would be intermediate between an inductive burn (baseline) scenario and a fully noninductive (steady state) scenario; therefore, this type of discharge has become known as a hybrid scenario. In the course …
Date: August 1, 2003
Creator: LUCE,TC; WADE,MR; FERRON,JR; HYATT,AW; POLITZER,PA & SIPS,ACC
System: The UNT Digital Library
D0 data handling operational experience (open access)

D0 data handling operational experience

We report on the production experience of the D0 experiment at the Fermilab Tevatron, using the SAM data handling system with a variety of computing hardware configurations, batch systems, and mass storage strategies. We have stored more than 300 TB of data in the Fermilab Enstore mass storage system. We deliver data through this system at an average rate of more than 2 TB/day to analysis programs, with a substantial multiplication factor in the consumed data through intelligent cache management. We handle more than 1.7 Million files in this system and provide data delivery to user jobs at Fermilab on four types of systems: a reconstruction farm, a large SMP system, a Linux batch cluster, and a Linux desktop cluster. In addition, we import simulation data generated at 6 sites worldwide, and deliver data to jobs at many more sites. We describe the scope of the data handling deployment worldwide, the operational experience with this system, and the feedback of that experience.
Date: August 11, 2003
Creator: al., Lee Lueking et
System: The UNT Digital Library
Phase motion of the scalar {pi}{pi} amplitudes in D{sup +}, D{sub s}{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decays (open access)

Phase motion of the scalar {pi}{pi} amplitudes in D{sup +}, D{sub s}{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decays

We make a direct and model-independent measurement of the low {pi}{sup +} {pi}{sup -} mass phase motion in the D{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decay. Our preliminary results show a strong phase variation, compatible with the isoscalar {sigma}(500) meson. This result confirms our previous result [1] where we found evidence for the existence of this scalar particle using full Dalitz-plot analysis. We apply the Amplitude Difference (AD) method [2] to the same Fermilab E791 data sample used in the preceding analysis. We also give an example of how we extract the phase motion of the scalar amplitude, looking at the f{sub 0}(980) in D{sub s}{sup +} {yields} {pi}{sup -} {pi}{sup +}{pi}{sup +} decay.
Date: August 13, 2003
Creator: Bediaga, Ignacio
System: The UNT Digital Library
Systematic uncertainties on Delta m2 from neutrino physics, using calorimetric energy reconstruction (open access)

Systematic uncertainties on Delta m2 from neutrino physics, using calorimetric energy reconstruction

This report describes how uncertainties in neutrino interactions, particularly at neutrino energies of a few GeV, can contribute to uncertainties in measurements of neutrino oscillation parameters for experiments using calorimetric devices. Uncertainties studied include those on final state multiplicities, cross sections, electron-hadron calorimeter differences, and nuclear rescattering.
Date: August 13, 2003
Creator: Harris, Deborah A.
System: The UNT Digital Library
Uncertainty Reduction and Characterization of Complex Environmental Fate and Transport Models: An Empirical Bayesian Framework Incorporating the Stochastic Response Surface Method (open access)

Uncertainty Reduction and Characterization of Complex Environmental Fate and Transport Models: An Empirical Bayesian Framework Incorporating the Stochastic Response Surface Method

In this work, a computationally efficient Bayesian framework for the reduction and characterization of parametric uncertainty in computationally demanding environmental 3-D numerical models has been developed. The framework is based on the combined application of the Stochastic Response Surface Method (SRSM, which generates accurate and computationally efficient statistically equivalent reduced models) and the Markov Chain Monte Carlo method. The application selected to demonstrate this framework involves steady state groundwater flow at the U.S. Department of Energy Savannah River Site General Separations Area, modeled using the Subsurface Flow And Contaminant Transport (FACT) code. Input parameter uncertainty, based initially on expert opinion, was found to decrease in all variables of the posterior distribution. The joint posterior distribution obtained was then further used for the final uncertainty analysis of the stream baseflows and well location hydraulic head values.
Date: August 7, 2003
Creator: Flach, G. P.
System: The UNT Digital Library