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Energy efficiency improvement and cost saving opportunities forpetroleum refineries

Description: The petroleum refining industry in the United States is the largest in the world, providing inputs to virtually any economic sector,including the transport sector and the chemical industry. The industry operates 146 refineries (as of January 2004) around the country,employing over 65,000 employees. The refining industry produces a mix of products with a total value exceeding $151 billion. Refineries spend typically 50 percent of cash operating costs (i.e., excluding capital costs and depreciation) on energy, making energy a major cost factor and also an important opportunity for cost reduction. Energy use is also a major source of emissions in the refinery industry making energy efficiency improvement an attractive opportunity to reduce emissions and operating costs. Voluntary government programs aim to assist industry to improve competitiveness through increased energy efficiency and reduced environmental impact. ENERGY STAR (R), a voluntary program managed by the U.S. Environmental Protection Agency, stresses the need for strong and strategic corporate energy management programs. ENERGY STAR provides energy management tools and strategies for successful corporate energy management programs. This Energy Guide describes research conducted to support ENERGY STAR and its work with the petroleum refining industry.This research provides information on potential energy efficiency opportunities for petroleum refineries. This Energy Guide introduces energy efficiency opportunities available for petroleum refineries. It begins with descriptions of the trends, structure, and production of the refining industry and the energy used in the refining and conversion processes. Specific energy savings for each energy efficiency measure based on case studies of plants and references to technical literature are provided. If available, typical payback periods are also listed. The Energy Guide draws upon the experiences with energy efficiency measures of petroleum refineries worldwide. The findings suggest that given available resources and technology, there are opportunities to reduce energy consumption cost-effectively in the petroleum refining ...
Date: February 15, 2005
Creator: Worrell, Ernst & Galitsky, Christina
Partner: UNT Libraries Government Documents Department

Atomic-Resolution 3D Electron Microscopy with Dynamic Diffraction

Description: Achievement of atomic-resolution electron-beam tomography will allow determination of the three-dimensional structure of nanoparticles (and other suitable specimens) at atomic resolution. Three-dimensional reconstructions will yield ''section'' images that resolve atoms overlapped in normal electron microscope images (projections), resolving lighter atoms such as oxygen in the presence of heavier atoms, and atoms that lie on non-lattice sites such as those in non-periodic defect structures. Lower-resolution electron microscope tomography has been used to produce reconstructed 3D images of nanoparticles [1] but extension to atomic resolution is considered not to be straightforward. Accurate three-dimensional reconstruction from two-dimensional projections generally requires that intensity in the series of 2-D images be a monotonic function of the specimen structure (often specimen density, but in our case atomic potential). This condition is not satisfied in electron microscopy when specimens with strong periodicity are tilted close to zone-axis orientation and produce ''anomalous'' image contrast because of strong dynamic diffraction components. Atomic-resolution reconstructions from tilt series containing zone-axis images (with their contrast enhanced by strong dynamical scattering) can be distorted when the stronger zone-axis images overwhelm images obtained in other ''random'' orientations in which atoms do not line up in neat columns. The first demonstrations of 3-D reconstruction to atomic resolution used five zone-axis images from test specimens of staurolite consisting of a mix of light and heavy atoms [2,3]. Initial resolution was to the 1.6{angstrom} Scherzer limit of a JEOL-ARM1000. Later experiments used focal-series reconstruction from 5 to 10 images to produce staurolite images from the ARM1000 with resolution extended beyond the Scherzer limit to 1.38{angstrom} [4,5]. To obtain a representation of the three-dimensional structure, images were obtained in zone-axis projections <100>, <010>, <001>, <101>, <310>, and combined to produce a three-dimensional map of Coulomb potential. Images of specimen sections are much more easily interpreted than projection images ...
Date: February 15, 2005
Creator: O'Keefe, Michael A.; Downing, Kenneth H.; Wenk, Hans-Rudolf & Meisheng, Hu
Partner: UNT Libraries Government Documents Department

Resolution Quality and Atom Positions in Sub-Angstrom Electron Microscopy

Description: Ability to determine whether an image peak represents one single atom or several depends on resolution of the HR-(S)TEM. Rayleigh's resolution criterion, an accepted standard in optics, was derived as a means for judging when two image intensity peaks from two sources of light (stars) are distinguishable from a single source. Atom spacings closer than the Rayleigh limit have been resolved in HR-TEM, suggesting that it may be useful to consider other limits, such as the Sparrow resolution criterion. From the viewpoint of the materials scientist, it is important to be able to use the image to determine whether an image feature represents one or more atoms (resolution), and where the atoms (or atom columns) are positioned relative to one another (resolution quality). When atoms and the corresponding image peaks are separated by more than the Rayleigh limit of the HR-(S)TEM, it is possible to adjust imaging parameters so that relative peak positions in the image correspond to relative atom positions in the specimen. When atoms are closer than the Rayleigh limit, we must find the relationship of the peak position to the atom position by peak fitting or, if we have a suitable model, by image simulation. Our Rayleigh-Sparrow parameter QRS reveals the ''resolution quality'' of a microscope image. QRS values greater than 1 indicate a clearly resolved twin peak, while values between 1 and 0 mean a lower-quality resolution and an image with peaks displaced from the relative atom positions. The depth of the twin-peak minimum can be used to determine the value of QRS and the true separation of the atom peaks that sum to produce the twin peak in the image. The Rayleigh-Sparrow parameter can be used to refine relative atom positions in defect images where atoms are closer than the Rayleigh limit of the HR-(S)TEM, ...
Date: February 15, 2005
Creator: O'Keefe, Michael A.; Allard, Lawrence F. & Blom, Douglas A.
Partner: UNT Libraries Government Documents Department

Pyramidal Defects in GaN:Mg Grown with Ga Polarity

Description: Transmission electron microscopy (TEM) studies show formation of different types of Mg-rich defects in GaN. Types of defects strongly depend on crystal growth polarity. For bulk crystals grown with N-polarity, the planar defects are distributed at equal distances (20 unit cells of GaN). For growth with Ga-polarity (for both bulk and MOCVD grown crystals) a different type of defects have been found. These defects are three-dimensional Mg-rich hexagonal pyramids (or trapezoids) with their base on the (0001) plane and six walls formed on 1123 planes. The defects appear in [1120] and [1100] cross-section TEM micrographs as triangular and trapezoidal with sides inclined at 43 and 47 degrees to the base depending on the above observation directions, respectively. The dimension of these pyramids varies depending on growth method (50-1000 Angstrom), but the angle between the base and their sides remain the same. The direction from the tip of the pyramid to its base (and from the shorter to the longer base for trapezoidal defects) is along the Ga to N matrix bond direction. Analysis of the reconstructed exit wave phase image from the pyramid side indicates a shift of Ga atomic column positions from the matrix to the N position within the pyramid. In this way a 0.6{+-}0.2 Angstrom displacement can be measured on the pyramid side between Ga positions in the matrix and within the pyramid.
Date: February 15, 2005
Creator: Liliental-Weber, Zuzanna; Tomaszewicz, Tomasz; Zakharov, Dmitri & O'Keefe, Michael A.
Partner: UNT Libraries Government Documents Department

High Current Ion Sources and Injectors for Heavy Ion Fusion

Description: Heavy ion beam driven inertial fusion requires short ion beam pulses with high current and high brightness. Depending on the beam current and the number of beams in the driver system, the injector can use a large diameter surface ionization source or merge an array of small beamlets from a plasma source. In this paper, we review the scaling laws that govern the injector design and the various ion source options including the contact ionizer, the aluminosilicate source, the multicusp plasma source, and the MEVVA source.
Date: February 15, 2005
Creator: Kwan, Joe W.
Partner: UNT Libraries Government Documents Department

RHEOLOGICAL PROPERTIES OF SAVANNAH RIVER SITE (srs) RADIOACTIVE HIGH LEVEL WASTES AND MELTER FEEDS FOR SLUDGE BATCH 2

Description: The Savannah River Site, SRS, is currently pursuing an aggressive program to empty its High Level Waste, HLW, tanks and immobilize its radioactive waste into a durable borosilicate glass in the Defense Waste Processing Facility, DWPF. To create a batch of feed for the DWPF, several tanks of sludge slurry are combined into one of the million gallon, i.e. 3.79E06 liters, feed tanks for DWPF. A batch of feed nominally consists of 500,000 gallons, i.e. 1.89E06 liters. After a batch of feed is prepared, a portion of the batch, 26,500 liters, is transferred to DWPF. This batch is then chemically adjusted in the Chemical Processing Cell, CPC, prior to being fed to the melter to make the final product; canisters filled with glass. During the processing of the third batch, or Sludge Batch 2, of feed through the DWPF CPC, pumping and transfer problems were noted. These problems hindered the processing of the feed through the CPC, and thus impacted canister production in DWPF. In order to investigate the root cause of these problems, data were collected and evaluated for possible trends. One trend noted was the relationship between the pH, solids loading concentration, and temperature of the feed. As any one of these three variables changed, the rheological properties of the feed appeared to change. To determine the dependency of the rheological property, samples were obtained and shipped to Savannah River National Laboratory's, SRNL, Shielded Cells Facility. The samples were processed under two sets of conditions and rheological measurements obtained. The results of the SRNL studies showed that the ending pH of the samples impacted the rheological properties of the sample. Lowering the pH of the sludge slurry resulted in lower plastic viscosity and yield stress values,thus alleviating the processing problems. Increasing the solids loading typically increased both the ...
Date: February 15, 2005
Creator: TERRI, FELLINGER
Partner: UNT Libraries Government Documents Department

Comments on 'Pore-Scale Visulization of Colloid Transport andRetention in Partly Saturated Porous Media'

Description: The recent study by Crist et al. (2004) attempted to provide pore scale insights into mechanisms responsible for controlling colloid transport in unsaturated porous media. However, because they relied on images obtained along surfaces that were open to the atmosphere, artificial evaporation resulted in 2 more critical artifacts; formation of air-water-solid (AWS) contact lines, and advection/deposition of colloids to AWS contact lines. These evaporation-related artifacts need to be addressed because they account for most of the colloid deposition at AWS contact lines reported in Crist et al. (2004)...As stated in Crist el al. (2004), ''... the front panel was removed to avoid light reflections that obscured the view and, thus, exposed one side of the sand column to air''. Although a more recent paper (Crist et al., 2005) also presents results using the same methods and is therefore also affected by evaporation, we will restrict our present comments to Crist et al. (2004). Here, we show that removal of the front panel results in a sequence of three critical artifacts; (1) significant evaporation, (2) drying of thin films and formation of air-water-solid (AWS) contact lines, and (3) advection of colloids to AWS contact lines where they are deposited. As explained below, these artifacts so drastically disturbed their system that the magnitude of their observations are not likely to occur anywhere except within the most superficial few cm of soils. Before explaining these artifacts, we note that although trapping of colloids at AWS contact lines reported in Crist et al. (2004) is largely an artifact of evaporation, colloid filtration within perimeters of pendular rings is in fact a main prediction of the film straining model (Wan and Tokunaga, 1997). In that model, colloid filtration is predicted to be more efficient below a critical water saturation, when capillary connections between pendular rings ...
Date: February 15, 2005
Creator: Wan, Jiamin & Tokunaga, Tetsu K.
Partner: UNT Libraries Government Documents Department

Detection and Quantification of Pu(III, IV, V, and VI) Using a1.0-meter Liquid Core Waveguide

Description: Detection and quantification of the aquo ions of Pu in 1 MHClO4 was carried out using a 1-meter liquid core waveguide (LCW) coupledto a fiber optic UV-Vis spectrometer. Detection limits of 7 x 10-7 M forPu(VI), 1.6 x 10-5 M for Pu(V), 5 x 10-6 M for Pu(IV) and 8 x 10-6 M forPu(III) were achieved. The limits of detection represent increases of 18to 33 times those achievable using a conventional 1-cm path length.Because of the much lower detection limits of the LCW, routineidentification of the oxidation states in dilute Pu solutions can bemade.
Date: February 15, 2005
Creator: Wilson, Richard E.; Hu, Yung-Jin & Nitsche, Heino
Partner: UNT Libraries Government Documents Department

Processing of alumina-niobium interfaces via liquid-film-assistedjoining

Description: Alumina-niobium interfaces were fabricated at 1400 C via solid-state diffusion brazing of a 127-{micro}m-thick niobium foil between alumina blocks. Prior to brazing, some of the alumina mating surfaces, both polished and unpolished, were evaporation-coated with copper films {approx}1.4 {micro}m, {approx}3.0 {micro}m, and {approx}5.5 {micro}m thick to induce liquid-film-assisted joining at the brazing temperature. The effects of copper film thickness and surface roughness on fracture characteristics and ceramic-metal interfacial microstructure were investigated by room-temperature four-point bend tests, optical microscopy, profilometry, and atomic force microscopy. The average strength of bonds between niobium and polished alumina substrates increased with the introduction of copper film interlayers, and the scatter in strength tended to decrease, with an optimum combination of strength and Weibull modulus arising for a copper film thickness of 3.0 {micro}m. The strength characteristics of niobium bonded to unpolished alumina substrates were also improved by liquid-film-assisted joining, but were unaffected by the thickness of the copper interlayers.
Date: February 15, 2005
Creator: McKeown, Joseph T.; Sugar, Joshua D.; Gronsky, Ronald & Glaeser,Andreas M.
Partner: UNT Libraries Government Documents Department

Modeling Antimortar Lethality by a Solid-State Heat-Capacity Laser

Description: We have studied the use of a solid-state heat-capacity laser (SSHCL) in mortar defense. This type of laser, as built at LLNL, produces high-energy pulses with a wavelength of about 1 {micro}m and a pulse repetition rate of 200 Hz. Currently, the average power is about 26 kW. Our model of target interactions includes optical absorption, two-dimensional heat transport in the metal casing and explosive, melting, wind effects (cooling and melt removal), high-explosive reactions, and mortar rotation. The simulations continue until HE initiation is reached. We first calculate the initiation time for a range of powers on target and spot sizes. Then we consider an engagement geometry in which a mortar is fired at an asset defended by a 100-kW SSHCL. Propagation effects such as diffraction, turbulent broadening, scattering, and absorption are calculated for points on the trajectory, by means of a validated model. We obtain kill times and fluences, as functions of the rotation rate. These appear quite feasible.
Date: February 15, 2005
Creator: Boley, C D & Rubenchik, A M
Partner: UNT Libraries Government Documents Department

Design and Performance Characteristics of the ORNL AdvancedMicroscopy Laboratory and JEOL 2200FS-AC Aberration-CorrectedSTEM/TEM

Description: At ORNL, the new Advanced Microscopy Laboratory (AML) has recently been completed, with two aberration-corrected instruments installed, and two more planned in the near future to fill the 4-laboratory building. The installed JEOL 2200FS-AC has demonstrated aTEM information limit of 0.9A. This limit is expected given the measured instrument parameters (HT and OL power supply stabilities, beam energy spread, etc.), and illustrates that the environmental influences are not adversely affecting the instrument performance. In STEM high-angle annular dark-field (HA-ADF) mode, images of a thin Si crystal in<110>zone axis orientation, after primary aberrations in the illuminating beam were optimally corrected, showed a significant vibration effect. The microscope is fitted with three magnetically levitated turbo pumps (one on the column at about the specimen position,and two near floor level) that pump the Omega energy filter and detector chamber. These pumps run at 48,000 rpm, precisely equivalent to 800Hz. It was determined that the upper turbo pump was contributing essentially all of the 800Hz signal to the image, and in fact that the pump was defective. After replacing the pump with one significantly quieter than the original, the Si atomic column image and associated diffractogram(Fig. 4b) show a much-reduced effect of the 800Hz signal, but still some residual effect from the turbo pump. The upper pump will be removed from the main column to an adjacent frame on the floor, and will have a large-diameter, well-damped, pump line to the original connection to the column to effectively isolate the pump from the column. If the 800Hz signal results from mechanical vibrations, they will be damped, and if the signal results from acoustic coupling to the column, it can be damped by appropriate acoustic materials.
Date: February 15, 2005
Creator: Allard, Lawrence F.; Blom, Douglas A.; O'Keefe, Michael A. & Mishina, S.
Partner: UNT Libraries Government Documents Department

The Influence of Selected Liquid and Soil Properties on the Propagation of Spills over Flat Permeable Surfaces

Description: In an effort to determine spill characteristics, information about a spill's spatial distribution with time is being studied. For permeable surfaces, spill phenomenology is controlled by liquid and soil properties, the most relevant of which are presented in this report. The pertinent liquid and soil properties were tabulated for ten liquids and four soils. The liquids represented an array of organic compounds, some of which are or are soon to be documented in the liquid spectra library by the Environmental Molecular Science Laboratory at Pacific Northwest National Laboratory. The soils were chosen based on ongoing surface spectra work and to represent a range of relevant soil properties. The effect of the liquid and soil properties on spill phenomenology were explored using a spill model that couples overland flow described by gravity currents with the Green-Ampt infiltration model. From the simulations, liquid viscosity was found to be a controlling liquid property in determining the amount of time a spill remains on the surface, with the surface vanish time decreasing as viscosity decreased. This was attributed to decreasing viscosity increasing both the hydraulic conductivity of the soil and allowing for the spill to more quickly spread out onto an unsaturated soil surface. Soil permeability also controlled vanish times with the vanish times increasing as permeability decreased, corresponding to finer textured materials. Maximum spill area was found to be largely controlled by liquid viscosity on coarse, highly permeable soils. On the less permeable soils maximum spill area began to be controlled by the steady-area spill height due to the restricting of infiltration to the extent that the spill is then able to reach its steady-area spill height. Simulations performed with and without the inclusion of capillarity in the Green-Ampt infiltration model displayed the importance of capillarity in describing infiltration rate in fine textured ...
Date: February 15, 2005
Creator: Keller, Jason M. & Simmons, Carver S.
Partner: UNT Libraries Government Documents Department

Inverse Scattering Approach to Improving Pattern Recognition

Description: The Helmholtz machine provides what may be the best existing model for how the mammalian brain recognizes patterns. Based on the observation that the ''wake-sleep'' algorithm for training a Helmholtz machine is similar to the problem of finding the potential for a multi-channel Schrodinger equation, we propose that the construction of a Schrodinger potential using inverse scattering methods can serve as a model for how the mammalian brain learns to extract essential information from sensory data. In particular, inverse scattering theory provides a conceptual framework for imagining how one might use EEG and MEG observations of brain-waves together with sensory feedback to improve human learning and pattern recognition. Longer term, implementation of inverse scattering algorithms on a digital or optical computer could be a step towards mimicking the seamless information fusion of the mammalian brain.
Date: February 15, 2005
Creator: Chapline, G & Fu, C
Partner: UNT Libraries Government Documents Department

Ceramic Laser Materials

Description: Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.
Date: February 15, 2005
Creator: Soules, T F; Clapsaddle, B J; Landingham, R L & Schaffers, K I
Partner: UNT Libraries Government Documents Department

Physical and Chemical Analytical Analysis: A key component of Bioforensics

Description: The anthrax letters event of 2001 has raised our awareness of the potential importance of non-biological measurements on samples of biological agents used in a terrorism incident. Such measurements include a variety of mass spectral, spectroscopic, and other instrumental techniques that are part of the current armamentarium of the modern materials analysis or analytical chemistry laboratory. They can provide morphological, trace element, isotopic, and other molecular ''fingerprints'' of the agent that may be key pieces of evidence, supplementing that obtained from genetic analysis or other biological properties. The generation and interpretation of such data represents a new domain of forensic science, closely aligned with other areas of ''microbial forensics''. This paper describes some major elements of the R&D agenda that will define this sub-field in the immediate future and provide the foundations for a coherent national capability. Data from chemical and physical analysis of BW materials can be useful to an investigation of a bio-terror event in two ways. First, it can be used to compare evidence samples collected at different locations where such incidents have occurred (e.g. between the powders in the New York and Washington letters in the Amerithrax investigation) or between the attack samples and those seized during the investigation of sites where it is suspected the material was manufactured (if such samples exist). Matching of sample properties can help establish the relatedness of disparate incidents, and mis-matches might exclude certain scenarios, or signify a more complex etiology of the events under investigation. Chemical and morphological analysis for sample matching has a long history in forensics, and is likely to be acceptable in principle in court, assuming that match criteria are well defined and derived from known limits of precision of the measurement techniques in question. Thus, apart from certain operational issues (such as how to prioritize ...
Date: February 15, 2005
Creator: Velsko, S P
Partner: UNT Libraries Government Documents Department

The crystal structure of Rv1347c, a putative antibiotic resistance protein from Mycobacterium tuberculosis, reveals a GCN5-related fold and suggests an alternative function in siderophore biosynthesis

Description: Mycobacterium tuberculosis, the cause of TB, is a devastating human pathogen. The emergence of multi-drug resistance in recent years has prompted a search for new drug targets and for a better understanding of mechanisms of resistance. Here we focus on the gene product of an open reading frame from M. tuberculosis, Rv1347c, which is annotated as a putative aminoglycoside N-acetyltransferase. The Rv1347c protein does not show this activity, however, and we show from its crystal structure, coupled with functional and bioinformatic data, that its most likely role is in the biosynthesis of mycobactin, the M. tuberculosis siderophore. The crystal structure of Rv1347c was determined by MAD phasing from selenomethionine-substituted protein and refined at 2.2 {angstrom} resolution (R = 0.227, R{sub free} = 0.257). The protein is monomeric, with a fold that places it in the GCN5-related N-acetyltransferase (GNAT) family of acyltransferases. Features of the structure are an acylCoA binding site that is shared with other GNAT family members, and an adjacent hydrophobic channel leading to the surface that could accommodate long-chain acyl groups. Modeling the postulated substrate, the N{sup {var_epsilon}}-hydroxylysine side chain of mycobactin, into the acceptor substrate binding groove identifies two residues at the active site, His130 and Asp168, that have putative roles in substrate binding and catalysis.
Date: February 15, 2005
Creator: Card, G L; Peterson, N A; Smith, C A; Rupp, B; Schick, B M & Baker, E N
Partner: UNT Libraries Government Documents Department

Density Measurements of Be Shells

Description: The purpose of this memo is to lay out the uncertainties associated with the measurement of density of Be ablators by the weigh and volume method. I am counting on the readers to point out any faulty assumptions about the techniques or uncertainties associated with them. Based on the analysis presented below we should expect that 30 {micro}m thick shells will have an uncertainty in the measured density of about 2% of the value, coming more or less equally from the mass and volume measurement. The uncertainty is roughly inversely proportional to the coating thickness, thus a 60 {micro}m walled shell would result in a 1% uncertainty in the density.
Date: February 15, 2005
Creator: Cook, R C
Partner: UNT Libraries Government Documents Department

Topology Changing Transitions in Bubbling Geometries

Description: Topological transitions in bubbling half-BPS Type IIB geometries with SO(4) x SO(4) symmetry can be decomposed into a sequence of n elementary transitions. The half-BPS solution that describes the elementary transition is seeded by a phase space distribution of fermions filling two diagonal quadrants. We study the geometry of this solution in some detail. We show that this solution can be interpreted as a time dependent geometry, interpolating between two asymptotic pp-waves in the far past and the far future. The singular solution at the transition can be resolved in two different ways, related by the particle-hole duality in the effective fermion description. Some universal features of the topology change are governed by two-dimensional Type 0B string theory, whose double scaling limit corresponds to the Penrose limit of AdS_5 x S5 at topological transition. In addition, we present the full class of geometries describing the vicinity of the most general localized classical singularity that can occur in this class of half-BPS bubbling geometries.
Date: February 15, 2005
Creator: Horava, Petr & Shepard, Peter G.
Partner: UNT Libraries Government Documents Department

Topology Changing Transitions in Bubbling Geometries

Description: Topological transitions in bubbling half-BPS Type IIB geometries with SO(4) x SO(4) symmetry can be decomposed into a sequence of n elementary transitions. The half-BPS solution that describes the elementary transition is seeded by a phase space distribution of fermions filling two diagonal quadrants. We study the geometry of this solution in some detail. We show that this solution can be interpreted as a time dependent geometry, interpolating between two asymptotic pp-waves in the far past and the far future. The singular solution at the transition can be resolved in two different ways, related by the particle-hole duality in the effective fermion description. Some universal features of the topology change are governed by two-dimensional Type 0B string theory, whose double scaling limit corresponds to the Penrose limit of AdS_5 x S^5 at topological transition. In addition, we present the full class of geometries describing the vicinity of the most general localized classical singularity that can occur in this class of half-BPS bubbling geometries.
Date: February 15, 2005
Creator: Horava, Petr & Shepard, Peter G.
Partner: UNT Libraries Government Documents Department

Final Technical Report - "Determining How Magnetic Helicity Injection Really Works"

Description: This research program involved direct observation of the complicated plasma dynamics underlying spheromak formation. Spheromaks are self-organizing magnetically dominated plasma configurations which potentially offer a simple, low-cost means for confining the plasma in a controlled thermonuclear fusion reactor. The spheromak source used in these studies was a coaxial co-planar magnetized plasma gun which was specifically designed to have the simplest relevant geometry. The simplicity of the geometry facilitated understanding of the basic physics and minimized confusion that would otherwise have resulted from complexities due to the experimental geometry. The coaxial plasma gun was mounted on one end of a large vacuum tank that had excellent optical access so the spheromak formation process could be tracked in detail using ultra-high speed cameras. The main accomplishments of this research program were (1) obtaining experimental data characterizing the detailed physics underlying spheromak formation and the development of new theoretical models motivated by these observations, (2) determining the relationship between spheromak physics and astrophysical jets, (3) developing a new high-speed camera diagnostic for the SSPX spheromak at the Lawrence Livermore National Lab, and (4) training graduate students and postdoctoral fellows.
Date: February 15, 2005
Creator: Bellan, Paul M.
Partner: UNT Libraries Government Documents Department

An integrative approach to energy, carbon, and redox metabolism in the cyanobacterium Synechocystis sp. PCC 6803

Description: The team of the Fellowship for Interpretation of Genomes (FIG) under the leadership of Ross Overbeek, began working on this Project in November 2003. During the previous year, the Project was performed at Integrated Genomics Inc. A transition from the industrial environment to the public domain prompted us to adjust some aspects of the Project. Notwithstanding the challenges, we believe that these adjustments had a strong positive impact on our deliverables. Most importantly, the work of the research team led by R. Overbeek resulted in the deployment of a new open source genomic platform, the SEED (Specific Aim 1). This platform provided a foundation for the development of CyanoSEED a specialized portal to comparative analysis and metabolic reconstruction of all available cyanobacterial genomes (Specific Aim 3). The SEED represents a new generation of software for genome analysis. Briefly, it is a portable and extendable system, containing one of the largest and permanently growing collections of complete and partial genomes. The complete system with annotations and tools is freely available via browsing or via installation on a user's Mac or Linux computer. One of the important unique features of the SEED is the support of metabolic reconstruction and comparative genome analysis via encoding and projection of functional subsystems. During the project period, the FIG research team has validated the new software by developing a significant number of core subsystems, covering many aspects of central metabolism (Specific Aim 2), as well as metabolic areas specific for cyanobacteria and other photoautotrophic organisms (Specific Aim 3). In addition to providing a proof of technology and a starting point for further community-based efforts, these subsystems represent a valuable asset. An extensive coverage of central metabolism provides the bulk of information required for metabolic modeling in Synechocystis sp.PCC 6803. Detailed analysis of several subsystems covering energy, ...
Date: February 15, 2005
Creator: Ross Overbeek, Veronika Fonstein, Andrei Osterman, Svetlana Gerdes, Olga Vassieva, Olga Zagnitko, Dmitry Rodionov
Partner: UNT Libraries Government Documents Department

Restoring Sustainable Forests on Appalachian Mined Lands for Wood Products, Renewable Energy, Carbon Sequestration, and Other Ecosystems Services Quarterly Report

Description: The overall purpose of this project is to evaluate the biological and economic feasibility of restoring high-quality forests on mined land, and to measure carbon sequestration and wood production benefits that would be achieved from forest restoration procedures. During the reporting period (October-December 2004) we completed the validation of a forest productivity classification model for mined land. A coefficient of determination (R{sup 2}) of 0.68 confirms the model's ability to predict SI based on a selection of mine soil properties. To determine carbon sequestration under different forest management scenarios, a field study was installed as a 3 x 3 factorial in a random complete block design with three replications at each of three locations, Ohio (Figure 1), West Virginia (Figure 2), and Virginia (Figure 3). The treatments included three forest types (white pine, hybrid poplar, mixed hardwood) and three silvicultural regimes (competition control, competition control plus tillage, competition control plus tillage plus fertilization). For hybrid poplar, total plant biomass differences increased significantly with the intensity of silvicultural input. Root, stem, and foliage biomass also increased with the level of silvicultural intensity. Financial feasibility analyses of reforestation on mined lands previously reclaimed to grassland have been completed for conversion to white pine and mixed hardwood species. Examination of potential policy instruments for promoting financial feasibility also have been completed, including lump sum payments at time of conversion, annual payments through the life of the stand, and payments based on carbon sequestration that provide both minimal profitability and fully offset initial reforestation outlays. We have compiled a database containing mine permit information obtained from permitting agencies in Virginia, West Virginia, Pennsylvania, Ohio, and Kentucky. Due to differences and irregularities in permitting procedures between states, we found it necessary to utilize an alternative method to determine mined land acreages in the Appalachian region. ...
Date: February 15, 2005
Creator: Burger, James A.; Galbraith, J.; Fox, T.; Amacher, G.; Sullivan, J. & Zipper, C.
Partner: UNT Libraries Government Documents Department