Fabrication and evaluation of transmissive multilayer optics for 8 keV x rays (open access)

Fabrication and evaluation of transmissive multilayer optics for 8 keV x rays

We have made and tested several sliced multilayer structures which can function as transmissive x-ray optical elements (diffraction gratings, zone plates, and phase gratings) at 8 keV. Our automated multilayer sputtering system is optimized to sputter layers of arbitrary thickness for very large total deposits at high deposition rates. Diffraction patterns produced by the multilayer devices closely match theoretical predictions. Such transmissive optics have the potential for wide application in high resolution microscope and spectrometer systems. 13 refs., 10 figs.
Date: January 21, 1988
Creator: Bionta, R. M.; Jankowski, Alan Frederic & Makowiecki, D. M.
System: The UNT Digital Library
DEVELOPMENT OF VADOSE-ZONE HYDRAULIC PARAMETER VALUES (open access)

DEVELOPMENT OF VADOSE-ZONE HYDRAULIC PARAMETER VALUES

Several approaches have been developed to establish a relation between the soil-moisture retention curve and readily available soil properties. Those relationships are referred to as pedotransfer functions. Described in this paper are the rationale, approach, and corroboration for use of a nonparametric pedotransfer function for the estimation of soil hydraulic-parameter values at the yucca Mountain area in Nevada for simulations of net infiltration. This approach, shown to be applicable for use at Yucca Mountain, is also applicable for use at the Hanford Site where the underlying data were collected.
Date: January 21, 2008
Creator: PM, ROGERS
System: The UNT Digital Library
Compiler-Enhanced Incremental Checkpointing for OpenMP Applications (open access)

Compiler-Enhanced Incremental Checkpointing for OpenMP Applications

As modern supercomputing systems reach the peta-flop performance range, they grow in both size and complexity. This makes them increasingly vulnerable to failures from a variety of causes. Checkpointing is a popular technique for tolerating such failures, enabling applications to periodically save their state and restart computation after a failure. Although a variety of automated system-level checkpointing solutions are currently available to HPC users, manual application-level checkpointing remains more popular due to its superior performance. This paper improves performance of automated checkpointing via a compiler analysis for incremental checkpointing. This analysis, which works with both sequential and OpenMP applications, reduces checkpoint sizes by as much as 80% and enables asynchronous checkpointing.
Date: January 21, 2008
Creator: Bronevetsky, Greg; Marques, Daniel; Pingali, Keshav; Rugina, Radu & McKee, Sally A.
System: The UNT Digital Library
TECHNOLOGY NEEDS AND STATUS ON CLOSURE OF DOE RADIOACTIVE WASTE TANK ANCILLARY SYSTEMS (open access)

TECHNOLOGY NEEDS AND STATUS ON CLOSURE OF DOE RADIOACTIVE WASTE TANK ANCILLARY SYSTEMS

This paper summarizes the current state of art of sampling, characterizing, retrieving, transferring and treating the incidental waste and stabilizing the void space in tank ancillary systems and the needs involved with closure of these systems. The overall effort for closing tank and ancillary systems is very large and is in the initial stages of being addressed in a systematic manner. It was recognized in doing this effort, that gaps in both technology and material application for characterization and removal of residual waste and closure of ancillary systems would be identified. Great efficiencies are to be gained by defining the technology need areas early in the closure process and providing recommendations for technical programs to improve the closure strategies. Therefore, this paper will not only summarize the state of closure of ancillary systems but also provide recommendations to address the technology gaps identified in this assessment.
Date: January 21, 2009
Creator: Burns, H; Sharon Marra, S & Christine Langton, C
System: The UNT Digital Library
Use of a Stochastic Model to Evaluate Uncertainty in a Performance Assessment at the Savannah River Site - 8120 (open access)

Use of a Stochastic Model to Evaluate Uncertainty in a Performance Assessment at the Savannah River Site - 8120

A significant effort has recently been initiated to address probabilistic issues within radiological Performance Assessments (PA's) conducted at the Savannah River Site (SRS). This effort is considered to be part of a continual process, as is the program of PA analysis and maintenance across the Department of Energy (DOE) complex. At SRS, findings in the initial probabilistic analysis of the Slit Trenches in the E-Area PA were built upon and improved in the later development of the probabilistic model for the F-Area Tank Farm. Within the PA studies conducted at SRS, the initial effort of the uncertainty analyses was focused on the Slit Trenches as part of the E-Area PA. Specifically, a probabilistic model was developed for Slit Trench 5 within the E-Area. This model was utilized in deterministic mode to compare its results against the 2- and 3-D model results of the deterministic models. Then, utilizing the PDFs, the model was used to perform multiple realizations and produce probabilistic results. Later, a second probabilistic sensitivity and uncertainty analysis was undertaken for the F-Area Tank Farm PA. This effort is currently underway. Many improvements were made in how the flow and transport processes were incorporated within this model.
Date: January 21, 2008
Creator: Hiergesell, R. A. & Taylor, G. A.
System: The UNT Digital Library
Kinetic theory of radiation effects (open access)

Kinetic theory of radiation effects

To help achieve the quantitative and mechanistic understanding of these processes, the kinetic theory of radiation effects has been developed in the DOE basic energy sciences radiation effects and fusion reactor materials programs, as well as in corresponding efforts in other countries. This discipline grapples with a very wide range of phenomena and draws on numerous sub-fields of theory such as defect physics, diffusion, elasticity, chemical reaction rates, phase transformations and thermodynamics. The theory is cast in a mathematical framework of continuum dynamics. Issues particularly relevant to the present inquiry can be viewed from the standpoints of applications of the theory and areas requiring further progress.
Date: January 21, 1987
Creator: Mansur, L.K.
System: The UNT Digital Library
Near-infrared Adaptive Optics Imaging of the Satellites and Individual Rings of Uranus from the W.M. Keck Observatory (open access)

Near-infrared Adaptive Optics Imaging of the Satellites and Individual Rings of Uranus from the W.M. Keck Observatory

None
Date: January 21, 2004
Creator: Gibbard, S G; de Pater, I & Hammel, H B
System: The UNT Digital Library
An Integrated Universal Collapsar Gamma-ray Burst Model (open access)

An Integrated Universal Collapsar Gamma-ray Burst Model

Starting with two assumptions: (1) gamma-ray bursts originate from stellar death phenomena or so called ''collapsars'' and (2) that these bursts are quasi-universal, whereby the majority of the observed variation is due to our perspective of the jet, an integrated gamma-ray burst model is proposed. It is found that several of the key correlations in the data can be naturally explained with this simple picture and another possible correlation is predicted.
Date: January 21, 2004
Creator: Salmonson, J D
System: The UNT Digital Library
Feature Subset Selection, Class Separability, and Genetic Algorithms (open access)

Feature Subset Selection, Class Separability, and Genetic Algorithms

The performance of classification algorithms in machine learning is affected by the features used to describe the labeled examples presented to the inducers. Therefore, the problem of feature subset selection has received considerable attention. Genetic approaches to this problem usually follow the wrapper approach: treat the inducer as a black box that is used to evaluate candidate feature subsets. The evaluations might take a considerable time and the traditional approach might be unpractical for large data sets. This paper describes a hybrid of a simple genetic algorithm and a method based on class separability applied to the selection of feature subsets for classification problems. The proposed hybrid was compared against each of its components and two other feature selection wrappers that are used widely. The objective of this paper is to determine if the proposed hybrid presents advantages over the other methods in terms of accuracy or speed in this problem. The experiments used a Naive Bayes classifier and public-domain and artificial data sets. The experiments suggest that the hybrid usually finds compact feature subsets that give the most accurate results, while beating the execution time of the other wrappers.
Date: January 21, 2004
Creator: Cantu-Paz, E
System: The UNT Digital Library
Open Midplane Dipole Design for Lhc Ir Upgrade. (open access)

Open Midplane Dipole Design for Lhc Ir Upgrade.

The proposed luminosity upgrade of the Large Hadron Collider (LHC), now under construction, will bring a large increase in the number of secondary particles from p-p collisions at the interaction point (IP). Energy deposition will be so large that the lifetime and quench performance of interaction region (IR) magnets may be significantly reduced if conventional designs are used. Moreover, the cryogenic capacity of the LHC will have to be significantly increased as the energy deposition load on the interaction region (IR) magnets by itself will exhaust the present capacity. We propose an alternate open midplane dipole design concept for the dipole-first optics that mitigates these issues. The proposed design takes advantage of the fact that most of the energy is deposited in the midplane region. The coil midplane region is kept free of superconductor, support structure and other material. Initial energy deposition calculations show that the increase in temperature remains within the quench tolerance of the superconducting coils. In addition, most of the energy is deposited in a relatively warm region where the heat removal is economical. We present the basic concept and preliminary design that includes several innovations.
Date: January 21, 2004
Creator: Gupta, R.; Anerella, M.; Harrison, M.; Schmalzle, J. & Mokhov, N.
System: The UNT Digital Library
Fundamentals of wetting and bonding between ceramics and metals (open access)

Fundamentals of wetting and bonding between ceramics and metals

The conditions and the reactions that lead to the realization of chemical equilibrium at interfaces and thus to chemical bonding is discussed with specific attention to the platinum/glass and gold/glass systems. Wetting of the solid by the liquid and formation of an interface are part of the problem. Sessile drop experiments and their interpretation are included. 10 figs, 12 refs. (GHT)
Date: January 21, 1977
Creator: Pask, J. A.
System: The UNT Digital Library
The Mercury Laser Advances Laser Technology for Power Generation (open access)

The Mercury Laser Advances Laser Technology for Power Generation

The National Ignition Facility (NIF) at Lawrence Livermore Laboratory is on target to demonstrate 'breakeven' - creating as much fusion-energy output as laser-energy input. NIF will compress a tiny sphere of hydrogen isotopes with 1.8 MJ of laser light in a 20-ns pulse, packing the isotopes so tightly that they fuse together, producing helium nuclei and releasing energy in the form of energetic particles. The achievement of breakeven will culminate an enormous effort by thousands of scientists and engineers, not only at Livermore but around the world, during the past several decades. But what about the day after NIF achieves breakeven? NIF is a world-class engineering research facility, but if laser fusion is ever to generate power for civilian consumption, the laser will have to deliver pulses nearly 100,000 times faster than NIF - a rate of perhaps 10 shots per second as opposed to NIF's several shots a day. The Mercury laser (named after the Roman messenger god) is intended to lead the way to a 10-shots-per-second, electrically-efficient, driver laser for commercial laser fusion. While the Mercury laser will generate only a small fraction of the peak power of NIF (1/30,000), Mercury operates at higher average power. The design …
Date: January 21, 2009
Creator: Ebbers, C A; Caird, J & Moses, E
System: The UNT Digital Library
Systematic Scale-Setting to All Orders: The Principle of Maximum Conformality and Commensurate Scale Relations (open access)

Systematic Scale-Setting to All Orders: The Principle of Maximum Conformality and Commensurate Scale Relations

None
Date: January 21, 2014
Creator: Brodsky, Stanley J.; Mojaza, Matin & Wu, Xing-Gang
System: The UNT Digital Library
2011 RENEWABLE ENERGY: SOLAR FUELS GORDON RESEARCH CONFERENCE (open access)

2011 RENEWABLE ENERGY: SOLAR FUELS GORDON RESEARCH CONFERENCE

The conference will present and discuss current science that underlies solar fuels production, and will focus on direct production pathways for production. Thus, recent advances in design and understanding of molecular systems and materials for light capture and conversion of relevance for solar fuels will be discussed. An important set of topics will be homogeneous, heterogeneous and biological catalysts for the multi-electron processes of water oxidation, hydrogen production and carbon dioxide reduction to useful fuels. Also, progress towards integrated and scalable systems will be presented. Attached is a copy of the formal schedule and speaker program and the poster program.
Date: January 21, 2011
Creator: Hupp, Joseph
System: The UNT Digital Library
Mapping Diffuse Seismicity Using Empirical Matched Field Processing Techniques (open access)

Mapping Diffuse Seismicity Using Empirical Matched Field Processing Techniques

The objective of this project is to detect and locate more microearthquakes using the empirical matched field processing (MFP) method than can be detected using only conventional earthquake detection techniques. We propose that empirical MFP can complement existing catalogs and techniques. We test our method on continuous seismic data collected at the Salton Sea Geothermal Field during November 2009 and January 2010. In the Southern California Earthquake Data Center (SCEDC) earthquake catalog, 619 events were identified in our study area during this time frame and our MFP technique identified 1094 events. Therefore, we believe that the empirical MFP method combined with conventional methods significantly improves the network detection ability in an efficient matter.
Date: January 21, 2011
Creator: Wang, J; Templeton, D C & Harris, D B
System: The UNT Digital Library
AUTOMATING GROUNDWATER SAMPLING AT HANFORD THE NEXT STEP (open access)

AUTOMATING GROUNDWATER SAMPLING AT HANFORD THE NEXT STEP

Historically, the groundwater monitoring activities at the Department of Energy's Hanford Site in southeastern Washington State have been very "people intensive." Approximately 1500 wells are sampled each year by field personnel or "samplers." These individuals have been issued pre-printed forms showing information about the well(s) for a particular sampling evolution. This information is taken from 2 official electronic databases: the Hanford Well information System (HWIS) and the Hanford Environmental Information System (HEIS). The samplers used these hardcopy forms to document the groundwater samples and well water-levels. After recording the entries in the field, the samplers turned the forms in at the end of the day and other personnel posted the collected information onto a spreadsheet that was then printed and included in a log book. The log book was then used to make manual entries of the new information into the software application(s) for the HEIS and HWIS databases. A pilot project for automating this extremely tedious process was lauched in 2008. Initially, the automation was focused on water-level measurements. Now, the effort is being extended to automate the meta-data associated with collecting groundwater samples. The project allowed electronic forms produced in the field by samplers to be used in …
Date: January 21, 2010
Creator: CW, CONNELL; SF, CONLEY; RD, HILDEBRAND; DE, CUNNINGHAM; R_D_Doug_Hildebrand@rl.gov & DeVon_E_Cunningham@rl.gov
System: The UNT Digital Library
Evidence for the incorporation of lead into barite from waste rock pile materials (open access)

Evidence for the incorporation of lead into barite from waste rock pile materials

Because Pb is one of the most toxic elements and is found as a major contaminant in mining environments, this study aims to identify the distribution of this element in host phases issued from the alteration of mine wastes. The sampling location was a former mine near Oakland, California (USA). This mine was once a source of sulfide minerals from which sulfuric acid was made. The material discussed in this paper was collected in iron hardpans that were formed within the waste rock pile resulting from the excavation work. In most contaminated environments (soils, mine waste), secondary metal-bearing phases arising from alteration processes are usually fine-grained (from 10 {micro}m to less than 1 {micro}m) and highly heterogeneous, requiring the use of micron-scale techniques. We performed micro-Raman spectroscopy, microscanning X-ray diffraction (SXRD), and microextended X-ray near edge spectroscopy (XANES) to determine the relationships between Pb and a Ba/Fe-rich host phase. Micro-Raman spectroscopy suggests that Pb is preferentially incorporated into barite rather than goethite. Results from micro-Raman experiments show the high sensitivity of this analytical tool to the incorporation of Pb into barite by being especially sensitive to the variations of the S-O bond and showing the characteristic bands due to the …
Date: January 21, 2008
Creator: COURTIN-NOMADE, ALEXANDRA; SOUBRAND-COLIN, MARILYNE; MARCUS, MATTHEW A. & FAKRA, SIRINE .C
System: The UNT Digital Library
Nuclear Reactions of Arsenic with 190 Mev Deuterons (open access)

Nuclear Reactions of Arsenic with 190 Mev Deuterons

Isotopes formed in the bombardment of {sub 33}As{sup 75} with 190 Mev deuterons range in atomic number up to 24 (or more) mass units lighter than As{sup 75}. Identification of these isotopes was based on chemical behavior and half-life determination. Relative yields have been calculated and show that 80% of the observed reactions produce isotopes within 8 mass units of As{sup 75}. Three new isotopes have been observed: 9.5 d. Se{sup 72} (K), 44 m, Se{sup 71} ({beta}{sup +}), and 52 m, As{sup 71} ({beta}{sup +}).
Date: January 21, 1948
Creator: Hopkins Jr, H.H. & Cunningham, B.B.
System: The UNT Digital Library
Conceptual Schematic Geologic Cross-Sections of the Geysers Steam Field (open access)

Conceptual Schematic Geologic Cross-Sections of the Geysers Steam Field

While formerly studied in terms of ancient Franciscan stratigraphy, The Geysers Steam Field now offers new views and interpretations on the deeper structure and importance of the lithocap, main metagraywacke, and felsic intrusive basement units with respect to the huge fractured reservoir. The Big Sulphur Creek enhanced tectonic disruption area provides the best situation for shallow felsite injection, shallow reservoir top, metasomatism transformation, and profound fracture permeability. Steam cells commonly extend to great depths and laterally drop off sharply, with relatively flat lateral continuance in some resource areas. Injectate ponding may offer a third fluid interface for reservoir steam reserves. A possible boiled down residuum of complex evaporates and hematite has been viewed in one area of the field where the reservoir (proper) bottom was encountered. Such a deposit may exist along all reservoir cell(s) bottoms, where in numerous cases the reservoir proper has been seen to pass into a somewhat mysterious ultra-superheated reservoir.
Date: January 21, 1986
Creator: Hebein, Jeffrey J.
System: The UNT Digital Library
Power Potential of Geothermal Wells Related to Reservoir Temperature (open access)

Power Potential of Geothermal Wells Related to Reservoir Temperature

Abstract: For equal flows of hot water wells, the electric power which can be generated increases with feed water temperature. However, high temperature wells discharge greater flows than that of lower temperature wells of similar permeability, with the result of enhanced power potential. In fact, where fluids are exploited utilizing two-stage flash, these factors combine to give a power potential which is proportional to the cube of the feed water temperature in degrees celsius. Hence a feed of 315 C would generate twice the power of that of water at 250 C for wells of good permeability and where the reservoir exists under conditions of boiling point with depth. Higher temperature water (exceeding 300 C) has, however, a commensurate higher tendency to mineral deposition in reinjection water lines and this disposes design to single-stage flash with slightly reduced power, compared with the two-stage alternative.
Date: January 21, 1986
Creator: James, Russell
System: The UNT Digital Library
Preliminary Studies of Two-Phase Effects on Pressure Transient Data (open access)

Preliminary Studies of Two-Phase Effects on Pressure Transient Data

Presently, there are few methods available for analyzing pressure transient data from two-phase reservoirs. Methods published in the oil and gas literature (Earlougher, 1977) have been adapted for analyzing data from geothermal reservoirs, assuming a uniform initial steam saturation. However, it is well known that two-phase conditions often prevail only in parts of the reservoir, primarily in the top portion, and that vapor saturations are not uniform. Thus, there is a need to examine the pressure behavior during well tests considering more realistic conditions. Two-phase effects are important in pressure transient analysis because the mobility of two-phase mixtures can differ significantly from that of single-phase fluids. Also, the compressibility of two-phase mixtures is orders of magnitude higher than for single-phase liquid and vapor (Grant and Sorey, 1979). In this paper we perform scoping calculations on the effects of two-phase zones on well pressure transients. Three different cases are considered (Figure 1). The first is that of a fully two-phase system (e.g. Krafla, Iceland; Stefansson, 1981). This problem has been studied by various authors, including Moench and Atkinson (1977, 1978), Grant (1978), Garg (1978, 1980), Grant and Sorey (1979), and Aydelotte (1980). Some of the complexities of this type of system …
Date: January 21, 1986
Creator: Cox, B. Lee & Bodvarsson, Gudmundur S.
System: The UNT Digital Library
Pressure-Temperature-Spinner Survey in a Well at the Geysers (open access)

Pressure-Temperature-Spinner Survey in a Well at the Geysers

This paper presents results from a flowing pressure-temperature-spinner log run in a well drilled by GEO Operator Corporation (GEOOC) at The Geysers. Analysis and interpretation of the log data are also presented. The data indicated superheated steam with a temperature of 600 F (316 C) and an enthalpy of 1316 BTU/lbm (725 cal/gm) entered the wellbore below 8000 feet (2438 meters). This temperature and enthalpy is much higher than most Geysers steam wells which produce steam at or below 475 F (246 C) and 1240 BTU/lbm (683 CALIgm). The high temperature and enthalpy are even more puzzling since static pressure and temperature measurements conducted with Kuster type instruments six months later, indicate a ''normal'' vapor-dominated system existing at 475 F (246 C) and 500 psia (35 Kg/cm{sup 2}). Conceptual reservoir models which can explain these unusual thermodynamic conditions are presented.
Date: January 21, 1986
Creator: Drenick, Andy
System: The UNT Digital Library
Cooling of the Wairakei Reservoir During Production (open access)

Cooling of the Wairakei Reservoir During Production

After nearly 30 years of power generation, parts of the present production area at Wairakei are near the end of their economic life due to local cooling. To the west of the present production area there remains a large volume of high temperature resource whose deep liquid temperatures have not changed from those measured during the 1960's. Power generation can be maintained for many more years by producing from this high temperature resource.
Date: January 21, 1986
Creator: Bixley, Paul F.
System: The UNT Digital Library
Enhancement of Steam Phase Relative Permeability Due to Phase Transformation Effects in Porous Media (open access)

Enhancement of Steam Phase Relative Permeability Due to Phase Transformation Effects in Porous Media

An experimental study of two-phase concurrent flow of steam and water conducted (Verma et al., 1985) and a set of relative permeability curves was obtained. These curves were compared with semi-empirical results (Brooks and Corey, 1964) and experimental results obtained by other investigators (Johnson et al., 1959, and Osoba et al., 1951) for two-phase, two-component flow (oil/gas; gas/water; gas/oil). It was found that while the wetting phase relative permeabilities were in good agreement, the relative permeability for the steam phase was considerably higher than the relative permeabilities of the non-wetting phase (oil in oil/water and non-condensing gas in gas/oil or gas/water) in two-component systems (Figs. 1 and 2). This enhancement of steam relative permeability is attributed to phase transformation effects at the pore level in flow channels. There are two separate mechanisms by which phase transformation affected relative permeability CUTVBS (1) phase transformation in converging-diverging flow channels with hydrophilic walls can cause an enhancement of steam phase relative permeability; and (2) phase transformation along the interface of a stagnant phase and the phase flowing around it controls the irreducible phase saturation of the stagnant phase (Verma, 1986). A pore level model was considered to study the first mechanism. In this …
Date: January 21, 1986
Creator: Verma, A. & Pruess, K.
System: The UNT Digital Library