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Sample records for d-t graphite tiles

  1. Transparent graphitic tiles synthesized from carbon nanowalls by shock compression and rapid quenching

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazutaka; Atou, Toshiyuki; Niwase, Keisuke; Nakamura, Kazutaka G.; Yoshimura, Akihiko; Tanimura, Makoto; Kobayashi, Ken-ichi; Tachibana, Masaru

    2013-01-01

    Here, we report the synthesis of transparent graphitic tiles from carbon nanowalls (CNWs) by shock compression and rapid quenching. The transparent tiles are included in samples recovered from shock pressures above 57 GPa. They exhibit strong photoluminescence but no diamond Raman peak, similar to the case of amorphous diamond synthesized from C60 fullerene and neutron-irradiated graphite. However, the electron energy-loss spectroscopy exhibits relatively intense π* peak associated with graphite, that is inconsistent with the transparency. From these results, it is suggested that the transparent tile is a mixture of amorphous diamond and superhard graphitic material with the transparency. Such carbon phase may come from the unique structural feature of CNWs as the starting material for the shock compression.

  2. Surface characterization of TFTR first wall graphite tiles used during DT operations

    SciTech Connect

    Paffett, M. T.; Willms, R. S.; Gentile, C.; Skinner, C.

    2001-01-01

    Surface characterization studies were performed on graphite tiles used as first wall materials during DT operation of the Tokamak Fusion Test Reactor (TFTR) at the Princeton Plasma Physics Laboratory. These ex situ analysis studies revealed a number of interesting and unexpected features. In this work we examined the spatial and (where possible) the depth distribution of impurity species deposited onto the plasma facing surfaces using Xray Photo-electron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS).

  3. Spectroscopic study of energetic helium-ion irradiation effects on nuclear graphite tiles

    NASA Astrophysics Data System (ADS)

    Kim, Do Wan; Lee, K. W.; Choi, D. M.; Noh, S. J.; Kim, H. S.; Lee, Cheol Eui

    2016-02-01

    Helium ion-irradiation effects on the nuclear graphite tiles were studied in order to understand the structural modifications and damages that can be produced by fusion reaction in tokamaks. The surface morphological changes due to increasing dose of the irradiation were examined by the field-effect scanning electron microscopy, and X-ray photoelectron spectroscopy elucidated the changes in the shallow surface bonding configurations caused by the energetic irradiation. Raman spectroscopy revealed the structural defects and diamond-like carbon sites that increased with increasing irradiation dose, and the average inter-defect distance was found from the Raman peak intensities as a function of the irradiation dose.

  4. Measurement of leakage neutron spectra from graphite cylinders irradiated with D-T neutrons for validation of evaluated nuclear data.

    PubMed

    Luo, F; Han, R; Chen, Z; Nie, Y; Shi, F; Zhang, S; Lin, W; Ren, P; Tian, G; Sun, Q; Gou, B; Ruan, X; Ren, J; Ye, M

    2016-10-01

    A benchmark experiment for validation of graphite data evaluated from nuclear data libraries was conducted for 14MeV neutrons irradiated on graphite cylinder samples. The experiments were performed using the benchmark experimental facility at the China Institute of Atomic Energy (CIAE). The leakage neutron spectra from the surface of graphite (Φ13cm×20cm) at 60° and 120° and graphite (Φ13cm×2cm) at 60° were measured by the time-of-flight (TOF) method. The obtained results were compared with the measurements made by the Monte Carlo neutron transport code MCNP-4C with the ENDF/B-VII.1, CENDL-3.1 and JENDL-4.0 libraries. The results obtained from a 20cm-thick sample revealed that the calculation results with CENDL-3.1 and JENDL-4.0 libraries showed good agreements with the experiments conducted in the whole energy region. However, a large discrepancy of approximately 40% was observed below the 3MeV energy region with the ENDF/B-VII.1 library. For the 2cm-thick sample, the calculated results obtained from the abovementioned three libraries could not reproduce the experimental data in the energy range of 5-7MeV. The graphite data in CENDL-3.1 were verified for the first time and were proved to be reliable.

  5. Impurity diagnosis of a KSTAR graphite divertor tile using laser induced breakdown spectroscopy technique

    NASA Astrophysics Data System (ADS)

    Kim, Minju; Cho, Min Sang; Cho, Byoung Ick

    2017-04-01

    Laser induced breakdown spectroscopy (LIBS) has been tested to diagnose impurity elements on a Korea Superconducting Tokamak Advanced Research (KSTAR) divertor tile. Spectral lines of various impurity elements such as iron, chromium, and nickel were detected from the divertor surface. The variation of spectra with consecutive laser pulses demonstrates the potential for depth profiling analysis for the deposited impurity layer. The LIBS plasma parameters have been qualitatively determined from analysis of the relative line intensities and linewidths for each element. The validity of this analysis has been checked with atomic spectral simulations.

  6. Measurement of Tritium Surface Distribution on TFTR Bumper Limiter Tiles

    SciTech Connect

    K. Sugiyama; T. Tanabe; C.H. Skinner; C.A. Gentile

    2004-06-28

    The tritium surface distribution on graphite tiles used in the Tokamak Fusion Test Reactor (TFTR) bumper limiter and exposed to TFTR deuterium-tritium (D-T) discharges from 1993 to 1997 was measured by the Tritium Imaging Plate Technique (TIPT). The TFTR bumper limiter shows both re-/co-deposition and erosion. The tritium images for all tiles measured are strongly correlated with erosion and deposition patterns, and long-term tritium retention was found in the re-/co-depositions and flakes. The CFC tiles located at erosion dominated areas clearly showed their woven structure in their tritium images owing to different erosion yields between fibers and matrix. Significantly high tritium retention was observed on all sides of the erosion tiles, indicating carbon transport via repetition of local erosion/deposition cycles.

  7. Molecular random tilings as glasses

    PubMed Central

    Garrahan, Juan P.; Stannard, Andrew; Blunt, Matthew O.; Beton, Peter H.

    2009-01-01

    We have recently shown that p-terphenyl-3,5,3′,5′-tetracarboxylic acid adsorbed on graphite self-assembles into a two-dimensional rhombus random tiling. This tiling is close to ideal, displaying long-range correlations punctuated by sparse localized tiling defects. In this article we explore the analogy between dynamic arrest in this type of random tilings and that of structural glasses. We show that the structural relaxation of these systems is via the propagation–reaction of tiling defects, giving rise to dynamic heterogeneity. We study the scaling properties of the dynamics and discuss connections with kinetically constrained models of glasses. PMID:19720990

  8. Preassembly Of Insulating Tiles

    NASA Technical Reports Server (NTRS)

    Izu, Y. D.; Yoshioka, E. N.; Rosario, T.

    1988-01-01

    Concept for preassembling high-temperature insulating tiles speeds and simplifies installation and repair and reduces damage from handling. Preassembly concept facilitates placement of tiles on gently contoured surfaces as well as on flat ones. Tiles bonded to nylon mesh with room-temperature-vulcanizing silicon rubber. Spacing between tiles is 0.03 in. Applications include boilers, kilns, and furnaces.

  9. Brazing graphite to graphite

    DOEpatents

    Peterson, George R.

    1976-01-01

    Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of virtually graphite.

  10. Performance of the TFTR moveable limiter tiles

    NASA Astrophysics Data System (ADS)

    Ulrickson, M.; Cecchi, J. L.; Doyle, B. L.; Dylla, H. F.; Medley, S. S.; Owens, D. K.; Trester, P.

    1985-08-01

    The movable limiter for the Tokamak Fusion Test Reactor (TFTR) is composed of an Inconel X-750 backing plate covered with titanium carbide coated graphite tiles. It has been used for ohmic heating discharges at input powers up to about 2 MW for durations up to 3 s. Even though these levels were well within the design requirements, discharges showed high levels (up to 1%) of titanium contamination. It was observed that certain tiles were showing substantial coating removal which became progressively worse as more discharges were made. After about 800 discharges the tiles were removed. A few of the tiles were examined in the Sandia external beam facility. This analysis showed that the TiC coating was completely removed over large areas. There was also evidence of plasma deposited material on the tiles. The thickness of the remaining coating from this beam analysis agreed with the thickness determined from sectioning control coupons from the production runs. There was a weak correlation between damage and coating thickness. The correlation was such that there was a higher probability of coating failure as the coating thickness increased from 15 μm to 40 μm. Test were done using the ASTM-C-633 procedure for measuring coating bond strength. The adhesion strength agreed well with the behavior observed in TFTR. The coating has been removed, and the tiles reinstalled.

  11. Handmade Tile Mosaics

    ERIC Educational Resources Information Center

    Keeler, Rusty

    2007-01-01

    Just like the classroom, children's outdoor environments should be filled with artistic creations that add sparkle and imagination to the space. One of the author's favorite ways to add art to the outdoors is by installing a mosaic mural of child-made tiles. The process of making the tiles is fun for all; each tile is a charming work of art in…

  12. Generalized quasiperiodic Rauzy tilings

    NASA Astrophysics Data System (ADS)

    Vidal, Julien; Mosseri, Rémy

    2001-05-01

    We present a geometrical description of new canonical d-dimensional codimension one quasiperiodic tilings based on generalized Fibonacci sequences. These tilings are made up of rhombi in 2d and rhombohedra in 3d as the usual Penrose and icosahedral tilings. Thanks to a natural indexing of the sites according to their local environment, we easily write down, for any approximant, the sites coordinates, the connectivity matrix and we compute the structure factor.

  13. Rewaterproofing Silica Tiles

    NASA Technical Reports Server (NTRS)

    Lleger, L. J.; Wade, D. C.

    1983-01-01

    Waterproofing agent, vaporized in bubbler transported by gas flowing in system and deposits in pores of tiles. Vapor carried through hole of approximately 1/16 inch (1.6.mm) diameter made in tile coating. Technique used to waterproof buildups (concrete and brick) and possibly fabrics.

  14. Tiled Multicore Processors

    NASA Astrophysics Data System (ADS)

    Taylor, Michael B.; Lee, Walter; Miller, Jason E.; Wentzlaff, David; Bratt, Ian; Greenwald, Ben; Hoffmann, Henry; Johnson, Paul R.; Kim, Jason S.; Psota, James; Saraf, Arvind; Shnidman, Nathan; Strumpen, Volker; Frank, Matthew I.; Amarasinghe, Saman; Agarwal, Anant

    For the last few decades Moore’s Law has continually provided exponential growth in the number of transistors on a single chip. This chapter describes a class of architectures, called tiled multicore architectures, that are designed to exploit massive quantities of on-chip resources in an efficient, scalable manner. Tiled multicore architectures combine each processor core with a switch to create a modular element called a tile. Tiles are replicated on a chip as needed to create multicores with any number of tiles. The Raw processor, a pioneering example of a tiled multicore processor, is examined in detail to explain the philosophy, design, and strengths of such architectures. Raw addresses the challenge of building a general-purpose architecture that performs well on a larger class of stream and embedded computing applications than existing microprocessors, while still running existing ILP-based sequential programs with reasonable performance. Central to achieving this goal is Raw’s ability to exploit all forms of parallelism, including ILP, DLP, TLP, and Stream parallelism. Raw approaches this challenge by implementing plenty of on-chip resources - including logic, wires, and pins - in a tiled arrangement, and exposing them through a new ISA, so that the software can take advantage of these resources for parallel applications. Compared to a traditional superscalar processor, Raw performs within a factor of 2x for sequential applications with a very low degree of ILP, about 2x-9x better for higher levels of ILP, and 10x-100x better when highly parallel applications are coded in a stream language or optimized by hand.

  15. Graphite on graphite

    NASA Astrophysics Data System (ADS)

    Volovik, G. E.; Pudalov, V. M.

    2016-12-01

    We propose potential geometry for fabrication of the graphite sheets with atomically smooth edges. For such sheets with Bernal stacking, the electron-electron interaction and topology should cause sufficiently high density of states resulting in the high temperature of either spin ordering or superconducting pairing.

  16. The ATLAS Tile Calorimeter

    SciTech Connect

    Henriques, A.

    2015-07-01

    TileCal is the Hadronic calorimeter covering the most central region of the ATLAS experiment at the LHC. It uses iron plates as absorber and plastic scintillating tiles as the active material. Scintillation light produced in the tiles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs). The resulting electronic signals from the approximately 10000 PMTs are measured and digitised every 25 ns before being transferred to off-detector data-acquisition systems. This contribution will review in a first part the performances of the calorimeter during run 1, obtained from calibration data, and from studies of the response of particles from collisions. In a second part it will present the solutions being investigated for the ongoing and future upgrades of the calorimeter electronics. (authors)

  17. Seamless tiled display system

    NASA Technical Reports Server (NTRS)

    Dubin, Matthew B. (Inventor); Larson, Brent D. (Inventor); Kolosowsky, Aleksandra (Inventor)

    2006-01-01

    A modular and scalable seamless tiled display apparatus includes multiple display devices, a screen, and multiple lens assemblies. Each display device is subdivided into multiple sections, and each section is configured to display a sectional image. One of the lens assemblies is optically coupled to each of the sections of each of the display devices to project the sectional image displayed on that section onto the screen. The multiple lens assemblies are configured to merge the projected sectional images to form a single tiled image. The projected sectional images may be merged on the screen by magnifying and shifting the images in an appropriate manner. The magnification and shifting of these images eliminates any visual effect on the tiled display that may result from dead-band regions defined between each pair of adjacent sections on each display device, and due to gaps between multiple display devices.

  18. Planar tilings by polyominoes, polyhexes, and polyiamonds

    NASA Astrophysics Data System (ADS)

    Rhoads, Glenn C.

    2005-02-01

    Using computer programs, we enumerate and classify the tiling behavior of small polyominoes (n[less-than-or-equals, slant]9), polyhexes (n[less-than-or-equals, slant]7), and polyiamonds (n[less-than-or-equals, slant]10). For tiles that tile the Euclidean plane, we give diagrams illustrating how they tile. We also show several larger tiles whose minimal fundamental domain in any admitted (periodic) tiling is significantly larger than for any previously known tile.

  19. Producing superhydrophobic roof tiles.

    PubMed

    Carrascosa, Luis A M; Facio, Dario S; Mosquera, Maria J

    2016-03-04

    Superhydrophobic materials can find promising applications in the field of building. However, their application has been very limited because the synthesis routes involve tedious processes, preventing large-scale application. A second drawback is related to their short-term life under outdoor conditions. A simple and low-cost synthesis route for producing superhydrophobic surfaces on building materials is developed and their effectiveness and their durability on clay roof tiles are evaluated. Specifically, an organic-inorganic hybrid gel containing silica nanoparticles is produced. The nanoparticles create a densely packed coating on the roof tile surface in which air is trapped. This roughness produces a Cassie-Baxter regime, promoting superhydrophobicity. A surfactant, n-octylamine, was also added to the starting sol to catalyze the sol-gel process and to coarsen the pore structure of the gel network, preventing cracking. The application of ultrasound obviates the need to use volatile organic compounds in the synthesis, thereby making a 'green' product. It was also demonstrated that a co-condensation process effective between the organic and inorganic species is crucial to obtain durable and effective coatings. After an aging test, high hydrophobicity was maintained and water absorption was completely prevented for the roof tile samples under study. However, a transition from a Cassie-Baxter to a Wenzel state regime was observed as a consequence of the increase in the distance between the roughness pitches produced by the aging of the coating.

  20. Producing superhydrophobic roof tiles

    NASA Astrophysics Data System (ADS)

    Carrascosa, Luis A. M.; Facio, Dario S.; Mosquera, Maria J.

    2016-03-01

    Superhydrophobic materials can find promising applications in the field of building. However, their application has been very limited because the synthesis routes involve tedious processes, preventing large-scale application. A second drawback is related to their short-term life under outdoor conditions. A simple and low-cost synthesis route for producing superhydrophobic surfaces on building materials is developed and their effectiveness and their durability on clay roof tiles are evaluated. Specifically, an organic-inorganic hybrid gel containing silica nanoparticles is produced. The nanoparticles create a densely packed coating on the roof tile surface in which air is trapped. This roughness produces a Cassie-Baxter regime, promoting superhydrophobicity. A surfactant, n-octylamine, was also added to the starting sol to catalyze the sol-gel process and to coarsen the pore structure of the gel network, preventing cracking. The application of ultrasound obviates the need to use volatile organic compounds in the synthesis, thereby making a ‘green’ product. It was also demonstrated that a co-condensation process effective between the organic and inorganic species is crucial to obtain durable and effective coatings. After an aging test, high hydrophobicity was maintained and water absorption was completely prevented for the roof tile samples under study. However, a transition from a Cassie-Baxter to a Wenzel state regime was observed as a consequence of the increase in the distance between the roughness pitches produced by the aging of the coating.

  1. GRAPHITE EXTRUSIONS

    DOEpatents

    Benziger, T.M.

    1959-01-20

    A new lubricant for graphite extrusion is described. In the past, graphite extrusion mixtures have bcen composed of coke or carbon black, together with a carbonaceous binder such as coal tar pitch, and a lubricant such as petrolatum or a colloidal suspension of graphite in glycerin or oil. Sinee sueh a lubricant is not soluble in, or compatible with the biiider liquid, such mixtures were difficult to extrude, and thc formed pieees lacked strength. This patent teaches tbe use of fatty acids as graphite extrusion lubricants and definite improvemcnts are realized thereby since the fatty acids are soluble in the binder liquid.

  2. Ceramic tile expansion engine housing

    DOEpatents

    Myers, Blake

    1995-01-01

    An expandable ceramic tile housing for a high temperature engine is disclosed wherein each tile is independently supported in place in an interlocking matrix by retention mechanisms which mechanically couple the individual ceramic tiles to an outer metal support housing while maintaining thermal isolation of the metal housing from the ceramic tiles. The ceramic tiles are formed with either an octagonal front face portion and a square shank portion or a square front face portion with an octagonal shank portion. The length of the sides of the octagonal front face portion on one tile is equal to the length of the sides of the square front face portion of adjoining tiles to permit formation of an interlocking matrix. Fibrous ceramic sealing material may be placed between radial and tangential facing surfaces of adjacent tiles to limit radial gas flow therebetween. Labyrinth-sealed pressure-controlled compartments may be established between the tile housing and the outer metal support housing to control radial gas flow.

  3. Ceramic tile expansion engine housing

    DOEpatents

    Myers, B.

    1995-04-11

    An expandable ceramic tile housing for a high temperature engine is disclosed wherein each tile is independently supported in place in an interlocking matrix by retention mechanisms which mechanically couple the individual ceramic tiles to an outer metal support housing while maintaining thermal isolation of the metal housing from the ceramic tiles. The ceramic tiles are formed with either an octagonal front face portion and a square shank portion or a square front face portion with an octagonal shank portion. The length of the sides of the octagonal front face portion on one tile is equal to the length of the sides of the square front face portion of adjoining tiles to permit formation of an interlocking matrix. Fibrous ceramic sealing material may be placed between radial and tangential facing surfaces of adjacent tiles to limit radial gas flow there between. Labyrinth-sealed pressure-controlled compartments may be established between the tile housing and the outer metal support housing to control radial gas flow. 8 figures.

  4. Graphite to Inconel brazing using active filler metal

    SciTech Connect

    King, J.F.; Baity, F.W.; Walls, J.C.; Hoffman, D.J.

    1989-01-01

    Ion cyclotron resonant frequency (ICRF) antennas are designed to supply large amounts of auxiliary heating power to fusion-grade plasmas in the Toroidal Fusion Test Reactor (TFTR) and Tore Supra fusion energy experiments. A single Faraday shield structure protects a pair of resonant double loops which are designed to launch up to 2 MW of power per loop. The shield consists of two tiers of actively cooled Inconel alloy tubes with the front tier being covered with semicircular graphite tiles. Successful operation of the antenna requires the making of high integrity bonds between the Inconel tubes and graphite tiles by brazing. This paper discusses this process.

  5. Covering the Plane with Rep-Tiles.

    ERIC Educational Resources Information Center

    Fosnaugh, Linda S.; Harrell, Marvin E.

    1996-01-01

    Presents an activity in which students use geometric figures, rep-tiles, to design a tile floor. Rep-tiles are geometric figures of which copies can fit together to form a larger similar figure. Includes reproducible student worksheet. (MKR)

  6. Operation of DIII-D with all-graphite walls

    SciTech Connect

    Holtrop, K.L.; Jackson, G.L.; Kellman, A.G.; Lee, R.L.; Hollerbach, M.A

    1993-10-01

    Recently, additional graphite coverage has been installed in the DIII-D tokamak, increasing the graphite tile coverage from 45% to {approximately}90%. Due to a problem with copper impurity bursts during tokamak discharges, copper foam sheets between the graphite tiles and the Inconel wall have been replaced with GRAFOIL gaskets, which further increases the surface area of the graphite inside the DIII-D torus. Although additional graphite has the potential for improving DIII-D performance, if not properly conditioned it can also degrade tokamak discharges by contributing to increased low Z impurity influx and higher particle fueling. To address these concerns, improvements were implemented both in tile preparation and wall conditioning techniques. All previously installed tiles were grit-blasted with boron-carbide grit to remove co-deposited metal impurities and all tiles were outgassed to 1000{degrees}C prior to installation. The glow discharge system used for wall conditioning was modified to include a large area electrode. The only conditioning techniques used were baking and helium conditioning to avoid producing loosely bound carbon. Previously, H{sup 2} or D{sup 2} Taylor discharge cleaning was used extensively during the vent recovery phase. Recovery from the recent 7-month machine opening was extremely rapid with improved modes of energy confinement (H-mode) transitions observed on the 14th plasma discharge. In addition, very high confinement (VH-mode) discharges were obtained without boronization, which is further indication of the rapid vent recovery. Lower recycling/lower fueling efficiency was also observed during operation with all-graphite walls. We will also discuss the use of Ne and Ar glow, and qualification of the new graphite including outgassing tests of the GRAFOIL material.

  7. Kinetics of DNA tile dimerization.

    PubMed

    Jiang, Shuoxing; Yan, Hao; Liu, Yan

    2014-06-24

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile-tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency.

  8. Kinetics of DNA Tile Dimerization

    PubMed Central

    2015-01-01

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile–tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency. PMID:24794259

  9. Graphite-metal brazing for thermal applications

    SciTech Connect

    Hosking, F.M.; Koski, J.A.

    1991-01-01

    Various plasma facing components are being designed and fabricated to support Magnetic Fusion Energy experiments. They typically consist of graphite tiles mechanically or metallurgically attached to metallic cooling substrates. This paper will discuss the active brazing of isotropic and pyrolytic graphite to oxygen free, high conductivity (OFHC) Cu and an alumina-dispersion strengthened Cu with a Ag-Cu-Ti active filler metal. The Ti constituent promotes direct wetting of graphite with the formation of a thin TiC reaction layer. Joint design and materials selection are critical factors since graphite and Cu have large thermal expansion differences that affect residual stresses after brazing and subsequent component thermal performance. Low thermal expansion Mo and compliant Cu interlayers were introduced to lower the residual stresses and extend the thermal life of prototype graphite-Cu braze joints. Although the interlayers showed evidence of reducing the incidence of graphite cracking and spalling under thermal loading when brazed to the dispersion-stengthened Cu, the best graphite braze joints were produced with the more ductile OFHC Cu substrates and no interlayer. These latter joints survived simulated tokamak surface high heat fluxes of 30 MW{center dot}m{sup {minus}2} or greater, while comparable dispersion strengthened Cu samples failed at 10 MW{center dot}m{sup {minus}2}. 23 refs., 14 figs., 2 tabs.

  10. Graphite-metal brazing for thermal applications

    NASA Astrophysics Data System (ADS)

    Hosking, F. M.; Koski, J. A.

    Various plasma facing components are being designed and fabricated to support Magnetic Fusion Energy experiments. They typically consist of graphite tiles mechanically or metallurgically attached to metallic cooling substrates. This paper will discuss the active brazing of isotropic and pyrolytic graphite to oxygen free, high conductivity (OFHC) Cu and an alumina-dispersion strengthened Cu with a Ag-Cu-Ti active filler metal. The Ti constituent promotes direct wetting of graphite with the formation of a thin TiC reaction layer. Joint design and materials selection are critical factors since graphite and Cu have large thermal expansion differences that affect residual stresses after brazing and subsequent component thermal performance. Low thermal expansion Mo and compliant Cu interlayers were introduced to lower the residual stresses and extend the thermal life of prototype graphite-Cu braze joints. Although the interlayers showed evidence of reducing the incidence of graphite cracking and spalling under thermal loading when brazed to the dispersion stengthened Cu, the best graphite braze joints were produced with the more ductile OFHC Cu substrates and no interlayer. These latter joints survived simulated tokamak surface high heat fluxes of 30 MW x m(exp -2) or greater, while comparable dispersion strengthened Cu samples failed at 10 MW x m(exp -2)

  11. Graphite Revisited

    NASA Astrophysics Data System (ADS)

    Draine, B. T.

    2016-11-01

    Laboratory measurements are used to constrain the dielectric tensor for graphite, from microwave to X-ray frequencies. The dielectric tensor is strongly anisotropic even at X-ray energies. The discrete dipole approximation is employed for accurate calculations of absorption and scattering by single-crystal graphite spheres and spheroids. For randomly oriented single-crystal grains, the so-called 1/3{--}2/3 approximation for calculating absorption and scattering cross sections is exact in the limit a/λ \\to 0 and provides better than ∼10% accuracy in the optical and UV even when a/λ is not small, but becomes increasingly inaccurate at infrared wavelengths, with errors as large as ∼40% at λ =10 μ {{m}}. For turbostratic graphite grains, the Bruggeman and Maxwell Garnett treatments yield similar cross sections in the optical and ultraviolet, but diverge in the infrared, with predicted cross sections differing by over an order of magnitude in the far-infrared. It is argued that the Maxwell Garnett estimate is likely to be more realistic, and is recommended. The out-of-plane lattice resonance of graphite near 11.5 μm may be observable in absorption with the MIRI spectrograph on James Webb Space Telescope. Aligned graphite grains, if present in the interstellar medium, could produce polarized X-ray absorption and polarized X-ray scattering near the carbon K edge.

  12. Registration of 3D+t coronary CTA and monoplane 2D+t X-ray angiography.

    PubMed

    Metz, Coert T; Schaap, Michiel; Klein, Stefan; Baka, Nora; Neefjes, Lisan A; Schultz, Carl J; Niessen, Wiro J; van Walsum, Theo

    2013-05-01

    A method for registering preoperative 3D+t coronary CTA with intraoperative monoplane 2D+t X-ray angiography images is proposed to improve image guidance during minimally invasive coronary interventions. The method uses a patient-specific dynamic coronary model, which is derived from the CTA scan by centerline extraction and motion estimation. The dynamic coronary model is registered with the 2D+t X-ray sequence, considering multiple X-ray time points concurrently, while taking breathing induced motion into account. Evaluation was performed on 26 datasets of 17 patients by comparing projected model centerlines with manually annotated centerlines in the X-ray images. The proposed 3D+t/2D+t registration method performed better than a 3D/2D registration method with respect to the accuracy and especially the robustness of the registration. Registration with a median error of 1.47 mm was achieved.

  13. The scientific case for a JET D-T experiment

    SciTech Connect

    Weisen, H.; Sips, A. C. C.; Horton, L. D.; Challis, C. D.; Sharapov, S. E.; Zastrow, K.-D.; Batistoni, P. [EURATOM Collaboration: EFDA-JET Contributors

    2014-08-21

    After the first high power D-T experiment in JET in 1997 (DTE1), when JET was equipped with Carbon PFC's, a proposed second high power (up to ∼40MW) D-T campaign (DTE2) in the current Be/W vessel will address essential operational, technical, diagnostics and scientific issues in support of ITER. These experiments are proposed to minimize the risks to ITER by testing strategies for the management of the in-vessel tritium content, by providing the basis for transferring operational scenarios from non-active operation to D-T mixtures and by addressing the issue of the neutron measurement accuracy. Dedicated campaigns with operation in Deuterium, Hydrogen and Tritium before the D-T campaign proper will allow the investigation of isotope scaling of the H-mode transition, pedestal physics, heat, particle, momentum and impurity transport in much greater detail than was possible in DTE1. The D-T campaign proper will include validations of the baseline ELMy H-Mode scenario, of the hybrid H-mode and advanced tokamak scenarios, as well as the investigation of alpha particle physics and the qualification of ICRH scenarios suitable for D-T operation. This paper reviews the scientific goals of DTE2 together with a summary of the results of DTE1.

  14. Tiling spaces are inverse limits

    NASA Astrophysics Data System (ADS)

    Sadun, Lorenzo

    2003-11-01

    Let M be an arbitrary Riemannian homogeneous space, and let Ω be a space of tilings of M, with finite local complexity (relative to some symmetry group Γ) and closed in the natural topology. Then Ω is the inverse limit of a sequence of compact finite-dimensional branched manifolds. The branched manifolds are (finite) unions of cells, constructed from the tiles themselves and the group Γ. This result extends previous results of Anderson and Putnam, of Ormes, Radin, and Sadun, of Bellissard, Benedetti, and Gambaudo, and of Gähler. In particular, the construction in this paper is a natural generalization of Gähler's.

  15. Thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

    2011-01-01

    A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

  16. Composite treatment of ceramic tile armor

    DOEpatents

    Hansen, James G. R. [Oak Ridge, TN; Frame, Barbara J [Oak Ridge, TN

    2010-12-14

    An improved ceramic tile armor has a core of boron nitride and a polymer matrix composite (PMC) facing of carbon fibers fused directly to the impact face of the tile. A polyethylene fiber composite backing and spall cover are preferred. The carbon fiber layers are cured directly onto the tile, not adhered using a separate adhesive so that they are integral with the tile, not a separate layer.

  17. Composite treatment of ceramic tile armor

    DOEpatents

    Hansen, James G. R. [Oak Ridge, TN; Frame, Barbara J [Oak Ridge, TN

    2012-01-02

    An improved ceramic tile armor has a core of boron nitride and a polymer matrix composite (PMC) facing of carbon fibers fused directly to the impact face of the tile. A polyethylene fiber composite backing and spall cover are preferred. The carbon fiber layers are cured directly onto the tile, not adhered using a separate adhesive so that they are integral with the tile, not a separate layer.

  18. Production Process for Strong, Light Ceramic Tiles

    NASA Technical Reports Server (NTRS)

    Holmquist, G. R.; Cordia, E. R.; Tomer, R. S.

    1985-01-01

    Proportions of ingredients and sintering time/temperature schedule changed. Production process for lightweight, high-strength ceramic insulating tiles for Space Shuttle more than just scaled-up version of laboratory process for making small tiles. Boron in aluminum borosilicate fibers allows fusion at points where fibers contact each other during sintering, thereby greatly strengthening tiles structure.

  19. Bridged graphite oxide materials

    NASA Technical Reports Server (NTRS)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  20. Nuclear graphite

    SciTech Connect

    Mercuri, R. A.; Criscione, J. M.

    1985-07-02

    A high strength, high coefficient of thermal expansion fine-grained isotropic graphite article produced from 30% to 70% of attritor milled gilsonite coke or other high CTE carbon filler particles and minor amounts of a binder such a coal tar pitch and petroleum pitch, the article being formed by warm isostatic molding at a temperature of between 50/sup 0/ C. and 70/sup 0/ C. under a pressure between 100 and 1000 psi for a time between 1 and 10 minutes. The particle size of the fillers ranges up to 150 microns.

  1. Coherent fluctuations in the initial TFTR D-T experiments

    SciTech Connect

    Fredrickson, E.; Chang, Z.Y.; Budny, R.V.

    1995-03-01

    The initial operation of TFTR with approximately equal power in the tritium and deuterium neutral beam injectors has resulted in the production of fusion power in excess of 9MW and central {beta}{sub {alpha}} > 0.25%. This {beta}{sub {alpha}} is within a factor of 2--3 of the {beta}{sub {alpha}} in projections of ITER performance. Effects of this {alpha} population on TAE modes, sawteeth and fishbone activity are being searched for. The D-T plasmas are also being studied for evidence of changes in MHD activity which might be attributed to the fast {alpha} population. This paper reports on the activity in the Alfven range of frequencies in the D-T plasmas and on detailed measurements of the MHD activity preceding major disruptions in D-D and D-T.

  2. The Level-1 Tile-Muon Trigger in the Tile Calorimeter upgrade program

    NASA Astrophysics Data System (ADS)

    Ryzhov, A.

    2016-12-01

    The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). TileCal provides highly-segmented energy measurements for incident particles. Information from TileCal's outermost radial layer can assist in muon tagging in the Level-1 Muon Trigger by rejecting fake muon triggers due to slow charged particles (typically protons) without degrading the efficiency of the trigger. The main activity of the Tile-Muon Trigger in the ATLAS Phase-0 upgrade program was to install and to activate the TileCal signal processor module for providing trigger inputs to the Level-1 Muon Trigger. This report describes the Tile-Muon Trigger, focusing on the new detector electronics such as the Tile Muon Digitizer Board (TMDB) that receives, digitizes and then provides the signal from eight TileCal modules to three Level-1 muon endcap Sector-Logic Boards.

  3. Developing tiled projection display systems

    SciTech Connect

    Hereld, M.; Judson, I. R.; Paris, J.; Stevens, R. L.

    2000-06-08

    Tiled displays are an emerging technology for constructing high-resolution semi-immersive visualization environments capable of presenting high-resolution images from scientific simulation [EVL, PowerWall]. In this way, they complement other technologies such as the CAVE [Cruz-Niera92] or ImmersaDesk, [Czernuszenko97], which by design give up pure resolution in favor of width of view and stereo. However, the largest impact may well be in using large-format tiled displays as one of possibly multiple displays in building ''information'' or ''active'' spaces that surround the user with diverse ways of interacting with data and multimedia information flows [IPSI, Childers00, Raskar98, ROME, Stanford, UNC]. These environments may prove to be the ultimate successor of the desktop metaphor for information technology work.

  4. Shuttle Upgrade Program: Tile TPS

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Stewart, David A.; DiFiore, Robert; Irby, Ed; Arnold, James (Technical Monitor)

    2001-01-01

    One of the areas where the thermal protection system on the Space Shuttle Orbiter could be improved is the RSI (Reusable Surface Insulation) tile. The improvement would be in damage resistance that would reduce the resultant maintenance and inspection required. It has performed very well in every other aspect. Improving the system's damage resistance has been the subject of much research over the past several years. One of the results of that research was a new system developed for damage prone areas on the orbiter (i.e., base heat shield). That system, designated as TUFI, Toughened Uni-Piece Fibrous Insulation, was successfully demonstrated as an experiment on the Orbiter and is now baselined for the base heat shield. This paper describes the results of a current research program to further improve the TUFI tile system, thus making it applicable to more areas on the orbiter. The way to remove the current limitations of the TUFI system (i.e., weight or thermal conductivity differences between it and the baseline tile (LI-900)) is to improve the characteristics of LI-900 or AETB-8. Specifically this paper describes the results of two efforts. The first shows performance data of an improved LI-900 system involving the application of TUFI and the second describes data that shows a reduced difference in thermal conductivity between the advanced TUFI substrate (AETB-8) now used on the orbiter and LI-900.

  5. Preparation of graphitic articles

    DOEpatents

    Phillips, Jonathan; Nemer, Martin; Weigle, John C.

    2010-05-11

    Graphitic structures have been prepared by exposing templates (metal, metal-coated ceramic, graphite, for example) to a gaseous mixture that includes hydrocarbons and oxygen. When the template is metal, subsequent acid treatment removes the metal to yield monoliths, hollow graphitic structures, and other products. The shapes of the coated and hollow graphitic structures mimic the shapes of the templates.

  6. Development of a nondestructive vibration technique for bond assessment of Space Shuttle tiles

    NASA Technical Reports Server (NTRS)

    Moslehy, Faissal A.

    1994-01-01

    This final report describes the achievements of the above titled project. The project is funded by NASA-KSC (Grant No. NAG 10-0117) for the period of 1 Jan. to 31 Dec. 1993. The purpose of this project was to develop a nondestructive, noncontact technique based on 'vibration signature' of tile systems to quantify the bond conditions of the thermal protection system) tiles of Space Shuttle orbiters. The technique uses a laser rapid scan system, modal measurements, and finite element modeling. Finite element models were developed for tiles bonded to both clamped and deformable integrated skin-stringer orbiter mid-fuselage. Results showed that the size and location of a disbonded tile can be determined from frequency and mode shape information. Moreover, a frequency response survey was used to quickly identify the disbonded tiles. The finite element results were compared with experimentally determined frequency responses of a 17-tile test panel, where a rapidscan laser system was employed. An excellent degree of correlation between the mathematical simulation and experimental results was realized. An inverse solution for single-tile assemblies was also derived and is being implemented into a computer program that can interact with the modal testing software. The output of the program displays the size and location of disbond. This program has been tested with simulated input (i.e., finite element data), and excellent agreement between predicted and simulated disbonds was shown. Finally, laser vibration imaging and acoustic emission techniques were shown to be well suited for detecting and monitoring the progressive damage in Graphite/Epoxy composite materials.

  7. Microwave limb sounder, graphite epoxy support structure

    NASA Technical Reports Server (NTRS)

    Pynchon, G.

    1980-01-01

    The manufacturing and processing procedures which were used to fabricate a precision graphite/epoxy support structure for a spherical microwave reflecting surface are described. The structure was made fromm GY-70/930 ultra high modulus graphite prepreg, laminated to achieve an isotropic in plane thermal expansion of less than + or - 0.1 PPM/F. The structure was hand assembled to match the interface of the reflective surface, which was an array of 18 flexure supported, aluminum, spherically contoured tiles. Structural adhesives were used in the final assembly to bond the elements into their final configuration. A eutectic metal coating was applied to the composite surface to reduce dimensional instabilities arising from changes in the composite epoxy moisture content due to environmental effects. Basic materials properties data are reported and the results of a finite element structural analysis are referenced.

  8. Castellated tiles as the beam-facing components for the diagnostic calorimeter of the negative ion source SPIDER

    SciTech Connect

    Peruzzo, S. Cervaro, V.; Dalla Palma, M.; Delogu, R.; Fasolo, D.; Franchin, L.; Pasqualotto, R.; Rizzolo, A.; Tollin, M.; Serianni, G.; De Muri, M.; Pimazzoni, A.; Zampieri, L.

    2016-02-15

    This paper presents the results of numerical simulations and experimental tests carried out to assess the feasibility and suitability of graphite castellated tiles as beam-facing component in the diagnostic calorimeter of the negative ion source SPIDER (Source for Production of Ions of Deuterium Extracted from Radio frequency plasma). The results indicate that this concept could be a reliable, although less performing, alternative for the present design based on carbon fiber composite tiles, as it provides thermal measurements on the required spatial scale.

  9. Global Swath and Gridded Data Tiling

    NASA Technical Reports Server (NTRS)

    Thompson, Charles K.

    2012-01-01

    This software generates cylindrically projected tiles of swath-based or gridded satellite data for the purpose of dynamically generating high-resolution global images covering various time periods, scaling ranges, and colors called "tiles." It reconstructs a global image given a set of tiles covering a particular time range, scaling values, and a color table. The program is configurable in terms of tile size, spatial resolution, format of input data, location of input data (local or distributed), number of processes run in parallel, and data conditioning.

  10. Multilayer Impregnated Fibrous Thermal Insulation Tiles

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Szalai, Christine e.; Hsu, Ming-ta; Carroll, Joseph A.

    2007-01-01

    The term "secondary polymer layered impregnated tile" ("SPLIT") denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term "secondary" refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric-entry heating.

  11. Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences.

    PubMed

    Meindl, T; Wirth, S; Weckbach, S; Dietrich, O; Reiser, M; Schoenberg, S O

    2009-03-01

    To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen's kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences.

  12. Liquid scintillator tiles for calorimetry

    SciTech Connect

    Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; Barbaro, P. De; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.

    2016-11-28

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

  13. Liquid scintillator tiles for calorimetry

    NASA Astrophysics Data System (ADS)

    Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; De Barbaro, P.; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.

    2016-11-01

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. The light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

  14. Thermal Characterization of TPS Tiles

    SciTech Connect

    Kacmar, C. J.; LaCivita, K. J.; Jata, K. V.; Sathish, S.

    2006-03-06

    The Thermal Protection System (TPS) used on space shuttles protects the metallic structure from the large amounts of heat created during travel through the atmosphere, both on takeoff and reentry. The shuttle experiences high thermo-acoustic loading and impact damage from micro-meteorites, which can cause disbonds, delaminations, chips, cracks, and other defects to the TPS system. To enhance durability and damage tolerance, new TPS tiles with an added protective ceramic-matrix-composite layer are being developed. This paper explores the use of pulsed thermography as a quick, diverse, non-destructive technique, to characterize the TPS system. The pulsed thermography images obtained are presented and analyzed.

  15. Parametric Multi-Level Tiling of Imperfectly Nested Loops

    SciTech Connect

    Hartono, Albert; Baskaran, Muthu M.; Bastoul, Cedric; Cohen, Albert; Krishnamoorthy, Sriram; Norris, Boyana; Ramanujam, J.; Sadayappan, Ponnuswamy

    2009-05-18

    Tiling is a critical loop transformation for generating high-performance code on modern architectures. Efficient generation of multilevel tiled code is essential to exploit several levels of parallelism and/or to maximize data reuse in deep memory hierarchies. Tiled loops with parameterized tile sizes (not compile time constants) facilitate runtime feedback and dynamic optimizations used in iterative compilation and automatic tuning. The existing parametric multilevel tiling approach has focused on transformation for perfectly nested loops, where all assignment statements are contained inside the innermost loop of a loop nest. Previous solutions to tiling for imperfect loop nests are limited to the case where tile sizes are fixed. In this paper, we present an approach to parameterized multilevel tiling for imperfectly nested loops. Our tiling algorithm generates loops that iterate over full rectangular tiles that are amenable for potential compiler optimizations such as register tiling. Experimental results using a number of computational benchmarks demonstrate the effectiveness of our tiling approach.

  16. Chapter 20: Graphite

    SciTech Connect

    Burchell, Timothy D

    2012-01-01

    Graphite is truly a unique material. Its structure, from the nano- to the millimeter scale give it remarkable properties that lead to numerous and diverse applications. Graphite bond anisotropy, with strong in-plane covalent bonds and weak van der Waals type bonding between the planes, gives graphite its unique combination of properties. Easy shear of the crystal, facilitated by weak interplaner bonds allows graphite to be used as a dry lubricant, and is responsible for the substances name! The word graphite is derived from the Greek to write because of graphites ability to mark writing surfaces. Moreover, synthetic graphite contains within its structure, porosity spanning many orders of magnitude in size. The thermal closure of these pores profoundly affects the properties for example, graphite strength increases with temperature to temperatures in excess of 2200 C. Consequently, graphite is utilized in many high temperature applications. The basic physical properties of graphite are reviewed here. Graphite applications include metallurgical; (aluminum and steel production), single crystal silicon production, and metal casting; electrical (motor brushes and commutators); mechanical (seals, bearings and bushings); and nuclear applications, (see Chapter 91, Nuclear Graphite). Here we discuss the structure, manufacture, properties, and applications of Graphite.

  17. The Sad Case of the Columbine Tiles.

    ERIC Educational Resources Information Center

    Dowling-Sendor, Benjamin

    2003-01-01

    Analyzes free-speech challenge to school district's guidelines for acceptable expressions on ceramic tiles painted by Columbine High School students to express their feelings about the massacre. Tenth Circuit found that tile painting constituted school-sponsored speech and thus district had the constitutional authority under "Hazelwood School…

  18. Bonding Heat-Resistant Fabric to Tile

    NASA Technical Reports Server (NTRS)

    Holt, J. W.; Smiser, L. W.

    1985-01-01

    Acid etching, densification, and silica cement ensure strong bond. Key step in preparation for bonding to glazed tile is etching quartz fabric and tile with acid. This increases adhesion of silica cement used to form bond. Procedures use high-temperature materials exclusively and therefore suitable for securing flexible seals and heat barriers around doors and viewing ports in furnaces and kilns.

  19. Performance of the Tile PreProcessor Demonstrator for the ATLAS Tile Calorimeter Phase II Upgrade

    NASA Astrophysics Data System (ADS)

    Carrió, F.; Moreno, P.; Valero, A.

    2016-03-01

    The Tile Calorimeter PreProcessor demonstrator is a high performance double AMC board based on FPGA resources and QSFP modules. This board has been designed in the framework of the ATLAS Tile Calorimeter Demonstrator project for the Phase II Upgrade as the first stage of the back-end electronics. The TilePPr demonstrator has been conceived to receive and process the data coming from the front-end electronics of the TileCal Demonstrator module, as well as to configure it. Moreover, the TilePPr demonstrator handles the communication with the Detector Control System to monitor and control the front-end electronics. The TilePPr demonstrator represents 1/8 of the final TilePPr that will be designed and installed into the detector for the ATLAS Phase II Upgrade.

  20. Graphite Technology Development Plan

    SciTech Connect

    W. Windes; T. Burchell; M.Carroll

    2010-10-01

    The Next Generation Nuclear Plant (NGNP) will be a helium-cooled High Temperature Gas Reactor (HTGR) with a large graphite core. Graphite physically contains the fuel and comprises the majority of the core volume. Graphite has been used effectively as a structural and moderator material in both research and commercial high-temperature gas-cooled reactors. This development has resulted in graphite being established as a viable structural material for HTGRs. While the general characteristics necessary for producing nuclear grade graphite are understood, historical “nuclear” grades no longer exist. New grades must be fabricated, characterized, and irradiated to demonstrate that current grades of graphite exhibit acceptable non-irradiated and irradiated properties upon which the thermomechanical design of the structural graphite in NGNP is based. This Technology Development Plan outlines the research and development (R&D) activities and associated rationale necessary to qualify nuclear grade graphite for use within the NGNP reactor.

  1. Liquid scintillator tiles for calorimetry

    DOE PAGES

    Amouzegar, M.; Belloni, A.; Bilki, B.; ...

    2016-11-28

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity,more » and some preliminary results on radiation hardness.« less

  2. Microstructure evolution in D-T neutron irradiated silver

    NASA Astrophysics Data System (ADS)

    Sugio, K.; Ohkubo, H.; Mukouda, I.; Shimomura, Y.; Kutsukake, C.; Takeuchi, H.

    2002-12-01

    Irradiation of high purity silver with 14 MeV D-T neutrons was carried out at the fusion neutron source facility in Japan Atomic Energy Research Institute. The range of neutron fluence was 6.1×10 17 to 1.1×10 21 n/m 2, which is lower than in earliest D-T neutron irradiations. Thin foil and bulk specimens were irradiated at 288, 423 and 573 K, and observed using transmission electron microscopy. For irradiation at 288 K, the fraction of interstitial clusters in bulk is higher than that in thin foil. In irradiation experiments at 288 and 432 K, the number density of defect clusters is proportional to the neutron fluence to the power of 1.3. In irradiation experiments at 573 K, the defects are mostly stacking fault tetrahedrons (SFTs) and their number density is proportional to the neutron fluence. During isochronal annealing of specimens irradiated at 288 K, disappearance and coalescence of defect clusters were observed, and SFTs were mobile.

  3. Solar-energy treatment of ceramic tiles

    NASA Astrophysics Data System (ADS)

    Harris, J. N.; Clayton, M. E.

    1981-12-01

    The 400 kW Advanced Components Test Facility was used to provide a concentrated source of solar energy for firing ceramic wall tile. A domed top cylindrical cavity with a white refractory fiber lining provided diffuse reflection of the concentrated solar beam directly onto the upper surface of the unfired wall tile. The tile were placed directly on the cavity floor in a circular pattern, centered at 450 intervals so that eight tile could be fired at one time. The tile and cavity walls were instrumented with thermocouples, and pyrometric cones were used to determine temperature distribution within the cavity. The glazed and unglazed solar fired titles were tested for flatness, modulus of rupture, water absorption, porosity, bulk density, apparent specific gravity, percent linear thermal expansion and crystalline phases present in the fired bodies. The major problems encountered are: cracking by thermal shock, and uneven shrinkage and glaze maturity across individual tile. The cavity failed to provide even heating at all eight tile positions.

  4. Fibrous-Ceramic/Aerogel Composite Insulating Tiles

    NASA Technical Reports Server (NTRS)

    White, Susan M.; Rasky, Daniel J.

    2004-01-01

    Fibrous-ceramic/aerogel composite tiles have been invented to afford combinations of thermal-insulation and mechanical properties superior to those attainable by making tiles of fibrous ceramics alone or aerogels alone. These lightweight tiles can be tailored to a variety of applications that range from insulating cryogenic tanks to protecting spacecraft against re-entry heating. The advantages and disadvantages of fibrous ceramics and aerogels can be summarized as follows: Tiles made of ceramic fibers are known for mechanical strength, toughness, and machinability. Fibrous ceramic tiles are highly effective as thermal insulators in a vacuum. However, undesirably, the porosity of these materials makes them permeable by gases, so that in the presence of air or other gases, convection and gas-phase conduction contribute to the effective thermal conductivity of the tiles. Other disadvantages of the porosity and permeability of fibrous ceramic tiles arise because gases (e.g., water vapor or cryogenic gases) can condense in pores. This condensation contributes to weight, and in the case of cryogenic systems, the heat of condensation undesirably adds to the heat flowing to the objects that one seeks to keep cold. Moreover, there is a risk of explosion associated with vaporization of previously condensed gas upon reheating. Aerogels offer low permeability, low density, and low thermal conductivity, but are mechanically fragile. The basic idea of the present invention is to exploit the best features of fibrous ceramic tiles and aerogels. In a composite tile according to the invention, the fibrous ceramic serves as a matrix that mechanically supports the aerogel, while the aerogel serves as a low-conductivity, low-permeability filling that closes what would otherwise be the open pores of the fibrous ceramic. Because the aerogel eliminates or at least suppresses permeation by gas, gas-phase conduction, and convection, the thermal conductivity of such a composite even at

  5. Adhesives for bonding RSI tile to GrPI structure for advanced space transportation systems

    NASA Technical Reports Server (NTRS)

    Smith, K. E.; Hamermesh, C. L.; Hogenson, P. A.

    1979-01-01

    A system was developed for bonding RSI tiles to a graphite/polymide composite substrate which would withstand the full range of environmental conditions. The bonding system, designated RA59, consists of a mixture of glass (sesquisiloxane) resin in RTV 560 silicone. A significant number of data points for the RA59 are in the 65-psi failure range both when tested, and after exposure to 700 F. This is over two times the best shear and tensile values obtained with RV60 at this temperature. It is concluded that with a thorough understanding of the critical parameters involved, the higher values should be obtained consistently with the RA59. This is of particular significance if higher strength tiles were to be used in a hard-bonded configuration.

  6. Tritium Removal from Codeposits on Carbon Tiles by a Scanning Laser

    SciTech Connect

    C.H. Skinner; C.A. Gentile; A. Carpe; G. Guttadora; S. Langish; K.M. Young; W.M. Shu; and H. Nakamura

    2001-09-28

    A novel method for tritium release has been demonstrated on codeposited layers on graphite and carbon-fiber-composite tiles from the Tokamak Fusion Test Reactor (TFTR). A scanning continuous wave Nd laser beam heated the codeposits to a temperature of 1200-2300 degrees C for 10 to 200 milliseconds in an argon atmosphere. The temperature rise of the codeposit was significantly higher than that of the manufactured tile material (e.g., 1770 degrees C cf. 1080 degrees C). A major fraction of tritium was thermally desorbed with minimal change to the surface appearance at a laser intensity of 8 kW/cm(superscript ''2''), peak temperatures above 1230 degrees C and heating duration 10-20 milliseconds. In two experiments, 46% and 84% of the total tritium was released during the laser scan. The application of this method for tritium removal from a tokamak reactor appears promising and has significant advantages over oxidative techniques.

  7. The TileCal Laser Calibration System

    NASA Astrophysics Data System (ADS)

    Giangiobbe, Vincent; ATLAS Tile Calorimeter Group

    TileCal is the central hadronic calorimeter of the ATLAS detector operating at LHC. It is a sampling calorimeter whose active material is made of scintillating plastic tiles. Scintillation light is read by photomultipliers. A Laser system is used to monitor their gain stability. During dedicated calibration runs the Laser system sends via long optical fibers, a monitored amount of light simultaneously to all the ≈10000 photomultipliers of TileCal. This note describes two complementary methods to measure the stability of the photomultipliers gain using the Laser calibration runs. The results of validation tests are presented for both methods and theirrespective performances and limitations are discussed.

  8. Remotely replaceable tokamak plasma limiter tiles

    DOEpatents

    Gallix, R.

    1987-12-09

    U-shaped tiles placed end-to-end over a pair of parallel runners have two rods which engage L-shaped slots. A sliding bar between the runners has grooves with clips to retain the rods pressed into receiving legs of the L-shaped slots in the runners. Sliding the bar in the direction of retaining legs of the L-shaped slots latches the tiles in place over the wall. Resilient contact strips under the parallel sides of the U-shaped tile assure thermal and electrical contact with the wall. 6 figs.

  9. Distributed graph visualization on tiled displays

    NASA Astrophysics Data System (ADS)

    Chae, Sangwon

    2013-03-01

    In this paper, we propose a distributed force-directed layout algorithm in order to handle large graph data on tiled display that consists of multiple computing machines and multiple displays connected to each computing machine through Ethernet. The distributed tiled display makes one big screen using multiple displays in order to discern data obviously. Besides, multiple computing devices on tiled displays share the parts of an entire dataset. Therefore, it can dramatically reduce the processing time to visualize data on screen compared with the processing time on a single machine.

  10. The challenging scales of the bird: Shuttle tile structural integrity

    NASA Technical Reports Server (NTRS)

    Schneider, W. C.; Miller, G. J.

    1985-01-01

    The principal design issues, tests, and analyses required to solve the tile integrity problem on the space shuttle orbiters are addressed. Proof testing of installed tiles is discussed along with an airflow test of special tiles. Orbiter windshield tiles are considered in terms of changes necessary to ensure acceptable margins of safety for flight.

  11. Stability of triple-helical poly(dT)-poly(dA)-poly(dT) DNA with counterions.

    PubMed Central

    Dadarlat, V M; Saxena, V K

    1998-01-01

    Structural conformation of triple-helical poly(dT)-poly(dA)-poly(dT) has been a very controversial issue recently. Earlier investigations, based on fiber diffraction data and molecular modeling, indicated an A-form conformation with C'3-endo sugar pucker. On the other hand, Raman, solution infrared spectral, and NMR studies show a B-form structure with C'2-endo sugars. In accordance with these experimental results, a theoretical model with B-form, C'2-endo sugars was proposed in 1993. In the present work we investigate the dynamics and stability of the two conformations within the effective local field approach applied to the normal mode calculations for the system. The presence of counterions was explicitly taken into account. Stable equilibrium positions for the counterions were calculated by analyzing the normal mode dynamics and free energy of the system. The breathing modes of the triple helix are shifted to higher frequencies over those of the double helix by 4-16 cm-1. The characteristic marker band for the B conformation at 835 cm-1 is split up into two marker bands at 830 and 835 cm-1. A detailed comparison of the normal modes and the free energies indicates that the B-form structure, with C'2-endo sugar pucker, is more stable than the A-form structure. The normal modes and the corresponding dipole moments are found to be in close agreement with recent spectroscopic findings. PMID:9649369

  12. High-Strength, Low-Shrinkage Ceramic Tiles

    NASA Technical Reports Server (NTRS)

    Wheeler, W. H.; Creedon, J. F.

    1986-01-01

    Addition of refractory fibers and whiskers to insulating tiles composed primarily of fibrous silica, such as those used on the skin of Space Shuttle orbiter, greatly improves properties. New composition suitable for lightweight, thermally-stable mirror blanks and as furnace and kiln insulation. Improved tiles made with current tile-fabrication processes. For given density, tiles containing silicon carbide and boron additives stronger in flexure than tiles made from silica alone. In addition, tiles with additives nearly immune to heat distortion, whereas pure-silica tiles shrink and become severely distorted.

  13. Process evaluation and characterization of TiC coating on graphite for doublet III limiters and neutral beam armor

    NASA Astrophysics Data System (ADS)

    Trester, P. W.; Sevier, D. L.; Chin, J.; Horner, M. H.; Staley, H. G.; Kaplan, R.

    An investigation was conducted to evaluate a thin coating of TiC deposited on a graphite substrate by a commercial CVD coating process. Microstructural analyses are presented for specimens positioned at various locations within the retort during the CVD coating runs. Coating requirements for thickness, quality and uniformity were met. These findings provide the data base for production coating graphite neutral-beam armor and limiter tiles for Tokamaks.

  14. High-Yield D-T Neutron Generator

    SciTech Connect

    Ludewigt, B.A.; Wells, R.P.; Reijonen, J.

    2006-11-15

    A high-yield D-T neutron generator has been developed for neutron interrogation in homeland security applications such as cargo screening. The generator has been designed as a sealed tube with a performance goal of producing 5 {center_dot} 10{sup 11} n/s over a long lifetime. The key generator components developed are a radio-frequency (RF) driven ion source and a beam-loaded neutron production target that can handle a beam power of 10 kW. The ion source can provide a 100 mA D{sup +}/T{sup +} beam current with a high fraction of atomic species and can be pulsed up to frequencies of several kHz for pulsed neutron generator operation. Testing in D-D operation has been started.

  15. Notch sensitivity of space shuttle tile materials

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1980-01-01

    Tests were conducted at room temperature to determine the notch sensitivity of the thermal protection tile for the space shuttle. Two types of RSI tile were studied: LI-900 and LI-2200. Three point bend specimens were cut from discarded tiles in the in-plane (ip) and through-the-thickness (ttt) directions. They were tested with or without a sharp notch. The LI-900 (ip and ttt) specimens were not very notch sensitive, but the LI-2200 (ip and ttt) specimens were. The LI-2200 material showed about a 35 percent reduction in strength due to the presence of the notch. This reduction in strength should be considered in the design of mechanically fastened tile concepts.

  16. VB Platinum Tile & Carpet, Inc. Information Sheet

    EPA Pesticide Factsheets

    VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

  17. Radioactivity in zircon and building tiles.

    PubMed

    Deng, W; Tian, K; Zhang, Y; Chen, D

    1997-08-01

    Zircon (ZrSiO4) is commonly used in the manufacture of glazed tiles. In this study we found high concentrations of the radionuclides 226Ra, 232Th, 40K in zircon sand. The average radium equivalent (A(Ra) + 1.26 A(Th) + 0.086 A(k)) in zircon sand is 17,500 Bq kg(-1), which is 106 times as much as that in ordinary building materials. The external radiation (gamma + beta) dose rates in air at 5 cm from the surface of piles of zircon sand sacks range from 1.1 to 4.9 x 10(-2) mGy h(-1) with an average of 2.1 x 10(-2) mGy h(-1). Although no elevated gamma-ray radiation or radon exhalation rate was detected in rooms decorated with glazed tiles, which is characteristic of combined alpha, beta and gamma emitting thin materials, the average gamma-ray radiation dose rate at the surface of the tile stacks in shops is 1.5 times as much as the indoor background level. The average area density of total beta emitting radionuclides in glazed floor tiles and glazed wall tiles is 0.30 Bq cm(-2) and 0.28 Bq cm(-2), respectively. It was estimated that the average beta dose rates in tissue at a depth 7 mg cm(-2) with a distance 20-100 cm from the floor tiles were 3.2 to 0.9 x 10(-7) Gy h(-1). The study indicates that the beta-rays from glazed tiles might be one of the main factors leading to an increase in ionizing radiation received by the general public. Workers in glazed tile manufacturing factories and in tile shops or stores may be exposed to elevated levels of both beta-rays and gamma-rays from zircon sand or glazed tile stacks. No elevated radiation from unglazed tiles was detected.

  18. Cutting Symmetrical Recesses In Soft Ceramic Tiles

    NASA Technical Reports Server (NTRS)

    Nesotas, Tony C.; Tyler, Brent

    1989-01-01

    Simple tool cuts hemispherical recesses in soft ceramic tiles. Designed to expose wires of thermocouples embedded in tiles without damaging leads. Creates neat, precise holes around wires. End mill includes axial hole to accommodate thermocouple wires embedded in material to be cut. Wires pass into hole without being bent or broken. Dimensions in inches. Used in place of such tools as dental picks, tweezers, spatulas, and putty knives.

  19. Laser Scanner for Tile-Cavity Measurement

    NASA Technical Reports Server (NTRS)

    Yoshino, Stanley Y.; Wykes, Donald H.; Hagen, George R.; Lotgering, Gene E.; Gaynor, Michael B.; Westerlund, Paul G.; Baal, Thomas A.

    1987-01-01

    Irregular surfaces mapped and digitized for numerical-control machinery. Fast, accurate laser scanning system measures size and shape of cavity without making any physical contact with cavity and walls. Measurements processed into control signals for numerically controlled machining of tile or block to fit cavity. System generates map of grid points representing cavity and portion of outer surface surrounding cavity. Map data used to control milling machine, which cuts tile or block to fit in cavity.

  20. Quasicrystalline tilings with nematic colloidal platelets

    PubMed Central

    Dontabhaktuni, Jayasri; Ravnik, Miha; Žumer, Slobodan

    2014-01-01

    Complex nematic fluids have the remarkable capability for self-assembling regular colloidal structures of various symmetries and dimensionality according to their micromolecular orientational order. Colloidal chains, clusters, and crystals were demonstrated recently, exhibiting soft-matter functionalities of robust binding, spontaneous chiral symmetry breaking, entanglement, shape-driven and topological driven assembly, and even memory imprinting. However, no quasicrystalline structures were found. Here, we show with numerical modeling that quasicrystalline colloidal lattices can be achieved in the form of original Penrose P1 tiling by using pentagonal colloidal platelets in layers of nematic liquid crystals. The tilings are energetically stabilized with binding energies up to 2500 kBT for micrometer-sized platelets and further allow for hierarchical substitution tiling, i.e., hierarchical pentagulation. Quasicrystalline structures are constructed bottom-up by assembling the boat, rhombus, and star maximum density clusters, thus avoiding other (nonquasicrystalline) stable or metastable configurations of platelets. Central to our design of the quasicrystalline tilings is the symmetry breaking imposed by the platelet shape and the surface anchoring conditions at the colloidal platelets, which are misaligning and asymmetric over two perpendicular mirror planes. Finally, the design of the quasicrystalline tilings as platelets in nematic liquid crystals is inherently capable of a continuous variety of length scales of the tiling, ranging over three orders of magnitude in the typical length (from to ), which could allow for the design of quasicrystalline photonics at multiple frequency ranges. PMID:24550269

  1. Producing graphite with desired properties

    NASA Technical Reports Server (NTRS)

    Dickinson, J. M.; Imprescia, R. J.; Reiswig, R. D.; Smith, M. C.

    1971-01-01

    Isotropic or anisotropic graphite is synthesized with precise control of particle size, distribution, and shape. The isotropic graphites are nearly perfectly isotropic, with thermal expansion coefficients two or three times those of ordinary graphites. The anisotropic graphites approach the anisotropy of pyrolytic graphite.

  2. Graphite for nuclear reactors

    SciTech Connect

    Virgiliev, Yu.S.; Kalyagina, I.P.

    1993-12-31

    Relative dimensional changes and physical properties of structural graphites - {Gamma}p-280 (nuclear graphite) and {Gamma}p{Pi}-2 (modificated variety of nuclear graphite for the rings of elastic contact) irradiated at temperatures ranging from 320 to 1900K with a fluence of about 2.5.10{sup 22}nvt (E {ge} 0.18 MeV) are represented. In order to ensure a long-time serviceability of the VGM - reactor blocks the high-strength graphite of {Gamma}p-1 grade are developed. The properties and its irradiation changes of {Gamma}p-1 graphite are represented. A secondary swelling of the graphite develops similar to the swelling of metals, alloys and high-melting compounds.

  3. Radiation Effects in Graphite

    SciTech Connect

    Burchell, Timothy D

    2012-01-01

    The requirements for a solid moderator are reviewed and the reasons that graphite has become the solid moderator of choice discussed. The manufacture and properties of some currently available near-isotropic and isotropic grades are described. The major features of a graphite moderated reactors are briefly outlined. Displacement damage and the induced structural and dimensional changes in graphite are described. Recent characterization work on nano-carbons and oriented pyrolytic graphites that have shed new light on graphite defect structures are reviewed, and the effect of irradiation temperature on the defect structures is highlighted. Changes in the physical properties of nuclear graphite caused by neutron irradiation are reported. Finally, the importance of irradiation induced creep is presented, along with current models and their deficiencies.

  4. Oxidation Resistant Graphite Studies

    SciTech Connect

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

  5. Tile drainage as karst: Conduit flow and diffuse flow in a tile-drained watershed

    USGS Publications Warehouse

    Schilling, K.E.; Helmers, M.

    2008-01-01

    The similarity of tiled-drained watersheds to karst drainage basins can be used to improve understanding of watershed-scale nutrient losses from subsurface tile drainage networks. In this study, short-term variations in discharge and chemistry were examined from a tile outlet collecting subsurface tile flow from a 963 ha agricultural watershed. Study objectives were to apply analytical techniques from karst springs to tile discharge to evaluate water sources and estimate the loads of agricultural pollutants discharged from the tile with conduit, intermediate and diffuse flow regimes. A two-member mixing model using nitrate, chloride and specific conductance was used to distinguish rainwater versus groundwater inputs. Results indicated that groundwater comprised 75% of the discharge for a three-day storm period and rainwater was primarily concentrated during the hydrograph peak. A contrasting pattern of solute concentrations and export loads was observed in tile flow. During base flow periods, tile flow consisted of diffuse flow from groundwater sources and contained elevated levels of nitrate, chloride and specific conductance. During storm events, suspended solids and pollutants adhered to soil surfaces (phosphorus, ammonium and organic nitrogen) were concentrated and discharged during the rapid, conduit flow portion of the hydrograph. During a three-day period, conduit flow occurred for 5.6% of the time but accounted for 16.5% of the total flow. Nitrate and chloride were delivered primarily with diffuse flow (more than 70%), whereas 80-94% of total suspended sediment, phosphorus and ammonium were exported with conduit and intermediate flow regimes. Understanding the water sources contributing to tile drainage and the manner by which pollutant discharge occurs from these systems (conduit, intermediate or diffuse flow) may be useful for designing, implementing and evaluating non-point source reduction strategies in tile-drained landscapes. ?? 2007 Elsevier B.V. All

  6. Method for producing dustless graphite spheres from waste graphite fines

    DOEpatents

    Pappano, Peter J [Oak Ridge, TN; Rogers, Michael R [Clinton, TN

    2012-05-08

    A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

  7. Dynamic Moire methods for detection of loosened space shuttle tiles

    NASA Astrophysics Data System (ADS)

    Snow, W. L.; Burner, A. W.; Goad, W. K.

    1981-09-01

    Moire fringe methods for detecting loose space shuttle tiles were investigated with a test panel consisting of a loose tile surrounded by four securely bonded tiles. The test panel was excited from 20 to 150 Hz with in-plane sinusoidal acceleration of 2 g (peak). If the shuttle orbiter can be subjected to periodic excitation of 1 to 2 g (peak) and rigid-body periodic displacements do not mask the change in the Moire pattern due to tile looseness, then the use of projected Moire fringes to detect out-of-plane rockin appears to be the most viable indicator of tile looseness since no modifications to the tiles are required.

  8. Symmetry groups associated with tilings on a flat torus.

    PubMed

    Loyola, Mark L; De Las Peñas, Ma Louise Antonette N; Estrada, Grace M; Santoso, Eko Budi

    2015-01-01

    This work investigates symmetry and color symmetry properties of Kepler, Heesch and Laves tilings embedded on a flat torus and their geometric realizations as tilings on a round torus in Euclidean 3-space. The symmetry group of the tiling on the round torus is determined by analyzing relevant symmetries of the planar tiling that are transformed to axial symmetries of the three-dimensional tiling. The focus on studying tilings on a round torus is motivated by applications in the geometric modeling of nanotori and the determination of their symmetry groups.

  9. Coating method for graphite

    DOEpatents

    Banker, John G.; Holcombe, Jr., Cressie E.

    1977-01-01

    A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided comprising coating the graphite surface with a suspension of Y.sub.2 O.sub.3 particles in water containing about 1.5 to 4% by weight sodium carboxymethylcellulose.

  10. Coating method for graphite

    DOEpatents

    Banker, J.G.; Holcombe, C.E. Jr.

    1975-11-06

    A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided. The graphite surface is coated with a suspension of Y/sub 2/O/sub 3/ particles in water containing about 1.5 to 4 percent by weight sodium carboxymethylcellulose.

  11. Remotely replaceable tokamak plasma limiter tiles

    DOEpatents

    Tsuo, Simon , Langford, Alison A.

    1989-01-01

    U-shaped limiter tiles placed end-to-end over a pair of parallel runners secured to a wall have two rods which engage L-shaped slots in the runners. The short receiving legs of the L-shaped slots are perpendicular to the wall and open away from the wall, while long retaining legs are parallel to and adjacent the wall. A sliding bar between the runners has grooves with clips to retain the rods pressed into receiving legs of the L-shaped slots in the runners. Sliding the bar in the direction of retaining legs of the L-shaped slots latches the tiles in place over the runners. Resilient contact strips between the parallel arms of the U-shaped tiles and the wall assure thermal and electrical contact with the wall.

  12. Crosslinking in viral capsids via tiling theory.

    PubMed

    Twarock, R; Hendrix, R W

    2006-06-07

    A vital part of a virus is its protein shell, called the viral capsid, that encapsulates and hence protects the viral genome. It has been shown in Twarock [2004. A tiling approach to vius capsids assembly explaining a structural puzzle in virology. J. Theor. Biol. 226, 477-482] that the surface structures of viruses with icosahedrally symmetric capsids can be modelled in terms of tilings that encode the locations of the protein subunits. This theory is extended here to multi-level tilings in order to model crosslinking structures. The new framework is demonstrated for the case of bacteriophage HK97, and it is shown, how the theory can be used in general to decide if crosslinking, and what type of crosslinking, is compatible from a mathematical point of view with the geometrical surface structure of a virus.

  13. Improvement of PVC floor tiles by gamma radiation

    NASA Astrophysics Data System (ADS)

    du Plessis, T. A.; Badenhorst, F.

    Gamma radiation presents a unique method of transforming highly plasticized PVC floor tiles, manufactured at high speed through injection moulding, into a high quality floor covering at a cost at least 30% less than similarly rated rubber tiles. A specially formulated PVC compound was developed in collaboration with a leading manufacturer of floor tiles. These tiles are gamma crosslinked in its shipping cartons to form a dimensionally stable product which is highly fire resistant and inert to most chemicals and solvents. The crosslinked tiles are more flexible than the highly filled conventional PVC floor tiles, scratch resistant and have a longer lifespan and increased colour fastness. These tiles are also less expensive to install than conventional rubber tiles.

  14. NEW METHOD OF GRAPHITE PREPARATION

    DOEpatents

    Stoddard, S.D.; Harper, W.T.

    1961-08-29

    BS>A method is described for producing graphite objects comprising mixing coal tar pitch, carbon black, and a material selected from the class comprising raw coke, calcined coke, and graphite flour. The mixture is placed in a graphite mold, pressurized to at least 1200 psi, and baked and graphitized by heating to about 2500 deg C while maintaining such pressure. (AEC)

  15. Graphite for fusion energy applications

    SciTech Connect

    Eatherly, W.P.; Clausing, R.E.; Strehlow, R.A.; Kennedy, C.R.; Mioduszewski, P.K.

    1987-03-01

    Graphite is in widespread and beneficial use in present fusion energy devices. This report reflects the view of graphite materials scientists on using graphite in fusion devices. Graphite properties are discussed with emphasis on application to fusion reactors. This report is intended to be introductory and descriptive and is not intended to serve as a definitive information source. (JDH)

  16. Superlubricity of graphite.

    PubMed

    Dienwiebel, Martin; Verhoeven, Gertjan S; Pradeep, Namboodiri; Frenken, Joost W M; Heimberg, Jennifer A; Zandbergen, Henny W

    2004-03-26

    Using a home-built frictional force microscope that is able to detect forces in three dimensions with a lateral force resolution down to 15 pN, we have studied the energy dissipation between a tungsten tip sliding over a graphite surface in dry contact. By measuring atomic-scale friction as a function of the rotational angle between two contacting bodies, we show that the origin of the ultralow friction of graphite lies in the incommensurability between rotated graphite layers, an effect proposed under the name of "superlubricity" [Phys. Rev. B 41, 11 837 (1990)

  17. Two Views of Islam: Ceramic Tile Design and Miniatures.

    ERIC Educational Resources Information Center

    Macaulay, Sara Grove

    2001-01-01

    Describes an art project focusing on Islamic art that consists of two parts: (1) ceramic tile design; and (2) Islamic miniatures. Provides background information on Islamic art and step-by-step instructions for designing the Islamic tile and miniature. Includes learning objectives and resources on Islamic tile miniatures. (CMK)

  18. 21. TILES OF THE NEW WORLD PANEL, NORTH WALL OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. TILES OF THE NEW WORLD PANEL, NORTH WALL OF THE INDIAN HOUSE. THE RELIEF BROCADE TILES ILLUSTRATE SCENES OF NATIVE AMERICAN HISTORY AND CULTURE, AND THE EARLY EUROPEAN EXPLORATION OF THE NEW WORLD. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  19. 90. TILES OF THE NEW WORLD PANEL, NORTH WALL OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    90. TILES OF THE NEW WORLD PANEL, NORTH WALL OF THE INDIAN HOUSE. THE RELIEF BROCADE TILES ILLUSTRATE SCENES OF NATIVE AMERICAN HISTORY AND CULTURE, AND THE EARLY EUROPEAN EXPLORATION OF THE NEW WORLD. SAME VIEW AS PA-107-21. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  20. Production and characterization of glazed tiles containing incinerated sewage sludge.

    PubMed

    Lin, D F; Chang, W C; Yuan, C; Luo, H L

    2008-01-01

    In this article, glaze with different colorants was applied to tile specimens manufactured by incinerated sewage sludge ash (ISSA) and clay. Improvements using different amounts of colorants, and glaze components and concentrations on tile bodies were investigated. Four different proportions of clay (by weight ratio) were replaced by ISSA. Tiles of size 12 cm x 6 cm x 1 cm were made and left in an electric furnace to make biscuit tiles at 800 degrees C. Afterwards, four colorants, Fe2O3 (red), V2O5 (yellow), CoCO3 (blue), and MnO2 (purple), and four different glaze concentrations were applied on biscuit tile specimens. These specimens were later sintered into glazed tiles at 1050 degrees C. The study shows that replacement of clay by sludge ash had adverse effects on properties of tiles. Water absorption increased and bending strength reduced with increased amounts of ash. However, both water absorption and bending strength improved for glazed ash tiles. Abrasion of grazed tiles reduced noticeably from 0.001 to 0.002 g. This implies glaze can enhance abrasion resistance of tiles. Effects like lightfastness and acid-alkali resistance improved as different glazes were applied on tiles. In general, red glazed tiles showed the most stable performance, followed by blue, yellow, and purple.

  1. CFD-Predicted Tile Heating Bump Factors Due to Tile Overlay Repairs

    NASA Technical Reports Server (NTRS)

    Lessard, Victor R.

    2006-01-01

    A Computational Fluid Dynamics investigation of the Orbiter's Tile Overlay Repair (TOR) is performed to assess the aeroheating Damage Assessment Team's (DAT) existing heating correlation method for protuberance interference heating on the surrounding thermal protection system. Aerothermodynamic heating analyses are performed for TORs at the design reference damage locations body points 1800 and 1075 for a Mach 17.9 and a=39deg STS-107 flight trajectory point with laminar flow. Six different cases are considered. The computed peak heating bump factor on the surrounding tiles are below the DAT's heating bump factor values for smooth tile cases. However, for the uneven tiles cases the peak interference heating is shown to be considerably higher than the existing correlation prediction.

  2. Jagged Tiling for Intra-tile Parallelism and Fine-Grain Multithreading

    SciTech Connect

    Shrestha, Sunil; Manzano Franco, Joseph B.; Marquez, Andres; Feo, John T.; Gao, Guang R.

    2015-05-01

    In this paper, we have developed a novel methodology that takes into consideration multithreaded many-core designs to better utilize memory/processing resources and improve memory residence on tileable applications. It takes advantage of polyhedral analysis and transformation in the form of PLUTO, combined with a highly optimized finegrain tile runtime to exploit parallelism at all levels. The main contributions of this paper include the introduction of multi-hierarchical tiling techniques that increases intra tile parallelism; and a data-flow inspired runtime library that allows the expression of parallel tiles with an efficient synchronization registry. Our current implementation shows performance improvements on an Intel Xeon Phi board up to 32.25% against instances produced by state-of-the-art compiler frameworks for selected stencil applications.

  3. High Temperature Filler for Tile Gaps

    NASA Technical Reports Server (NTRS)

    Holt, J. W.; Wang, D. S.

    1983-01-01

    Gaps between ceramic tiles filled with ceramic-coated fabric that withstands temperatures as high as 2,000 degrees F (1,300 degrees C). Reusable high-temperature gap filler is made of fabric coated with ceramic slurry and bonded in place with room-temperature-vulcanized adhesive. Procedure used in kilns and furnaces.

  4. TILE at Iowa: Adoption and Adaptation

    ERIC Educational Resources Information Center

    Florman, Jean C.

    2014-01-01

    This chapter introduces a University of Iowa effort to enhance and support active learning pedagogies in technology-enhanced (TILE) classrooms and three elements that proved essential to the campus-wide adoption of those pedagogies. It then describes the impact of those professional development efforts on the curricula and cultures of three…

  5. L-Tromino Tiling of Multilated Chessboards

    ERIC Educational Resources Information Center

    Gardner, Martin

    2009-01-01

    An "n" x "n" chessboard is called deficient if one square is missing from any spot on the board. Can all deficient boards with a number of cells divisible by 3 be tiled by bent (or L-shaped) trominoes? The answer is yes, with exception of the order-5 board. This paper deals with the general problem plus numerous related puzzles and proofs…

  6. Silicon on graphite cloth

    SciTech Connect

    Rand, J.A.; Cotter, J.E.; Thomas, C.J.; Ingram, A.E.; Bai, Y.B.; Ruffins, T.R.; Barnett, A.M.

    1994-12-31

    A new polycrystalline silicon solar cell has been developed that utilizes commercially available graphite cloth as a substrate. This solar cell has achieved an energy conversion efficiency of 13.4% (AM1.5G). It is believed that this is a record efficiency for a silicon solar cell formed on a graphite substrate. The silicon-on-fabric structure is comprised of a thin layer of polycrystalline silicon grown directly on the graphite fabric substrate. The structure is fabricated by a low-cost ribbon process that avoids the expense and waste of wafering. The fabric substrate gives structural support to the thin device. Critical to the achievement of device quality silicon layers is control over impurities in the graphite fabric. The silicon-on-fabric technology has the potential to supply lightweight, low-cost solar cells to weight-sensitive markets at a fraction of the cost of conventionally thinned wafers.

  7. Intercalated graphite electrical conductors

    NASA Technical Reports Server (NTRS)

    Banks, B. A.

    1983-01-01

    For years NASA has wanted to reduce the weight of spacecraft and aircraft. Experiments are conducted to find a lightweight synthetic metal to replace copper. The subject of this paper, intercalated graphite, is such a material. Intercalated graphite is made by heating petroleum or coal to remove the hydrogen and to form more covalent bonds, thus increasing the molecular weight. The coal or petroleum eventually turns to pitch, which can then be drawn into a fiber. With continued heating the pitch-based fiber releases hydrogen and forms a carbon fiber. The carbon fiber, if heated sufficiently, becomes more organized in parallel layers of hexagonally arranged carbon atoms in the form of graphite. A conductor of intercalated graphite is potentially useful for spacecraft or aircraft applications because of its low weight.

  8. Graphite Technology Development Plan

    SciTech Connect

    W. Windes; T. Burchell; R. Bratton

    2007-09-01

    This technology development plan is designed to provide a clear understanding of the research and development direction necessary for the qualification of nuclear grade graphite for use within the Next Generation Nuclear Plant (NGNP) reactor. The NGNP will be a helium gas cooled Very High Temperature Reactor (VHTR) with a large graphite core. Graphite physically contains the fuel and comprises the majority of the core volume. Considerable effort will be required to ensure that the graphite performance is not compromised during operation. Based upon the perceived requirements the major data needs are outlined and justified from the perspective of reactor design, reatcor performance, or the reactor safety case. The path forward for technology development can then be easily determined for each data need. How the data will be obtained and the inter-relationships between the experimental and modeling activities will define the technology development for graphite R&D. Finally, the variables affecting this R&D program are discussed from a general perspective. Factors that can significantly affect the R&D program such as funding, schedules, available resources, multiple reactor designs, and graphite acquisition are analyzed.

  9. Carbon-14 Graphitization Chemistry

    NASA Astrophysics Data System (ADS)

    Miller, James; Collon, Philippe; Laverne, Jay

    2014-09-01

    Accelerator Mass Spectrometry (AMS) is a process that allows for the analysis of mass of certain materials. It is a powerful process because it results in the ability to separate rare isotopes with very low abundances from a large background, which was previously impossible. Another advantage of AMS is that it only requires very small amounts of material for measurements. An important application of this process is radiocarbon dating because the rare 14C isotopes can be separated from the stable 14N background that is 10 to 13 orders of magnitude larger, and only small amounts of the old and fragile organic samples are necessary for measurement. Our group focuses on this radiocarbon dating through AMS. When performing AMS, the sample needs to be loaded into a cathode at the back of an ion source in order to produce a beam from the material to be analyzed. For carbon samples, the material must first be converted into graphite in order to be loaded into the cathode. My role in the group is to convert the organic substances into graphite. In order to graphitize the samples, a sample is first combusted to form carbon dioxide gas and then purified and reduced into the graphite form. After a couple weeks of research and with the help of various Physics professors, I developed a plan and began to construct the setup necessary to perform the graphitization. Once the apparatus is fully completed, the carbon samples will be graphitized and loaded into the AMS machine for analysis.

  10. Tile-based Level of Detail for the Parallel Age

    SciTech Connect

    Niski, K; Cohen, J D

    2007-08-15

    Today's PCs incorporate multiple CPUs and GPUs and are easily arranged in clusters for high-performance, interactive graphics. We present an approach based on hierarchical, screen-space tiles to parallelizing rendering with level of detail. Adapt tiles, render tiles, and machine tiles are associated with CPUs, GPUs, and PCs, respectively, to efficiently parallelize the workload with good resource utilization. Adaptive tile sizes provide load balancing while our level of detail system allows total and independent management of the load on CPUs and GPUs. We demonstrate our approach on parallel configurations consisting of both single PCs and a cluster of PCs.

  11. Beautiful Math, Part 5: Colorful Archimedean Tilings from Dynamical Systems.

    PubMed

    Ouyang, Peichang; Zhao, Weiguo; Huang, Xuan

    2015-01-01

    The art of tiling originated very early in the history of civilization. Almost every known human society has made use of tilings in some form or another. In particular, tilings using only regular polygons have great visual appeal. Decorated regular tilings with continuous and symmetrical patterns were widely used in decoration field, such as mosaics, pavements, and brick walls. In science, these tilings provide inspiration for synthetic organic chemistry. Building on previous CG&A “Beautiful Math” articles, the authors propose an invariant mapping method to create colorful patterns on Archimedean tilings (1-uniform tilings). The resulting patterns simultaneously have global crystallographic symmetry and local cyclic or dihedral symmetry.

  12. Analysis on Thermal Conductivity of Graphite/Al Composite by Experimental and Modeling Study

    NASA Astrophysics Data System (ADS)

    Xue, C.; Bai, H.; Tao, P. F.; Jiang, N.; Wang, S. L.

    2017-01-01

    Graphite/Al composites were fabricated by vacuum hot pressing technology in this study. The main factors affecting the thermal conductivity (TC) of graphite/Al composites were deeply investigated by experimental and modeling study. The results showed that the TC of graphite/Al composite can be improved via designing the preferred orientation of graphite flakes, selecting graphite flakes with large diameter, increasing the content of graphite flakes in graphite/Al composite and solving the poor wettability between Al and graphite. The modified model can well predict the heat transfer behavior of graphite/Al composite.

  13. An efficient pseudomedian filter for tiling microrrays

    PubMed Central

    Royce, Thomas E; Carriero, Nicholas J; Gerstein, Mark B

    2007-01-01

    Background Tiling microarrays are becoming an essential technology in the functional genomics toolbox. They have been applied to the tasks of novel transcript identification, elucidation of transcription factor binding sites, detection of methylated DNA and several other applications in several model organisms. These experiments are being conducted at increasingly finer resolutions as the microarray technology enjoys increasingly greater feature densities. The increased densities naturally lead to increased data analysis requirements. Specifically, the most widely employed algorithm for tiling array analysis involves smoothing observed signals by computing pseudomedians within sliding windows, a O(n2logn) calculation in each window. This poor time complexity is an issue for tiling array analysis and could prove to be a real bottleneck as tiling microarray experiments become grander in scope and finer in resolution. Results We therefore implemented Monahan's HLQEST algorithm that reduces the runtime complexity for computing the pseudomedian of n numbers to O(nlogn) from O(n2logn). For a representative tiling microarray dataset, this modification reduced the smoothing procedure's runtime by nearly 90%. We then leveraged the fact that elements within sliding windows remain largely unchanged in overlapping windows (as one slides across genomic space) to further reduce computation by an additional 43%. This was achieved by the application of skip lists to maintaining a sorted list of values from window to window. This sorted list could be maintained with simple O(log n) inserts and deletes. We illustrate the favorable scaling properties of our algorithms with both time complexity analysis and benchmarking on synthetic datasets. Conclusion Tiling microarray analyses that rely upon a sliding window pseudomedian calculation can require many hours of computation. We have eased this requirement significantly by implementing efficient algorithms that scale well with genomic

  14. What's D&T For? Gathering and Comparing the Values of Design and Technology Academics and Trainee Teachers

    ERIC Educational Resources Information Center

    Hardy, Alison

    2015-01-01

    Some who read and research about Design & Technology (D&T) would say that the concept of value is key to understanding and defining D&T. Closer inspection reveals though that there are two ways in which values are defined in D&T: how values are taught and learnt about in D&T to use them to make judgments in D&T lessons, and…

  15. Recompressed exfoliated graphite articles

    DOEpatents

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2013-08-06

    This invention provides an electrically conductive, less anisotropic, recompressed exfoliated graphite article comprising a mixture of (a) expanded or exfoliated graphite flakes; and (b) particles of non-expandable graphite or carbon, wherein the non-expandable graphite or carbon particles are in the amount of between about 3% and about 70% by weight based on the total weight of the particles and the expanded graphite flakes combined; wherein the mixture is compressed to form the article having an apparent bulk density of from about 0.1 g/cm.sup.3 to about 2.0 g/cm.sup.3. The article exhibits a thickness-direction conductivity typically greater than 50 S/cm, more typically greater than 100 S/cm, and most typically greater than 200 S/cm. The article, when used in a thin foil or sheet form, can be a useful component in a sheet molding compound plate used as a fuel cell separator or flow field plate. The article may also be used as a current collector for a battery, supercapacitor, or any other electrochemical cell.

  16. Graphite Gamma Scan Results

    SciTech Connect

    Mark W. Drigert

    2014-04-01

    This report documents the measurement and data analysis of the radio isotopic content for a series of graphite specimens irradiated in the first Advanced Graphite Creep (AGC) experiment, AGC-1. This is the first of a series of six capsules planned as part of the AGC experiment to fully characterize the neutron irradiation effects and radiation creep behavior of current nuclear graphites. The AGC-1 capsule was irradiated in the Advanced Test Reactor (ATR) at INL at approximately 700 degrees C and to a peak dose of 7 dpa (displacements per atom). Details of the irradiation conditions and other characterization measurements performed on specimens in the AGC-1 capsule can be found in “AGC-1 Specimen Post Irradiation Data Report” ORNL/TM 2013/242. Two specimens from six different graphite types are analyzed here. Each specimen is 12.7 mm in diameter by 25.4 mm long. The isotope with the highest activity was 60Co. Graphite type NBG-18 had the highest content of 60Co with an activity of 142.89 µCi at a measurement distance of 47 cm.

  17. Boeing's High Voltage Solar Tile Test Results

    NASA Technical Reports Server (NTRS)

    Reed, Brian J.; Harden, David E.; Ferguson, Dale C.; Snyder, David B.

    2002-01-01

    Real concerns of spacecraft charging and experience with solar array augmented electrostatic discharge arcs on spacecraft have minimized the use of high voltages on large solar arrays despite numerous vehicle system mass and efficiency advantages. Boeing's solar tile (patent pending) allows high voltage to be generated at the array without the mass and efficiency losses of electronic conversion. Direct drive electric propulsion and higher power payloads (lower spacecraft weight) will benefit from this design. As future power demand grows, spacecraft designers must use higher voltage to minimize transmission loss and power cable mass for very large area arrays. This paper will describe the design and discuss the successful test of Boeing's 500-Volt Solar Tile in NASA Glenn's Tenney chamber in the Space Plasma Interaction Facility. The work was sponsored by NASA's Space Solar Power Exploratory Research and Technology (SERT) Program and will result in updated high voltage solar array design guidelines being published.

  18. Degenerate polygonal tilings in simple animal tissues

    NASA Astrophysics Data System (ADS)

    Hočevar, A.; Ziherl, P.

    2009-07-01

    The salient feature of one-cell-thick epithelia is their en face view, which reveals the polygonal cross section of the close-packed prismatic cells. The physical mechanisms that shape these tissues were hitherto explored using theories based on cell proliferation, which were either entirely topological or included certain morphogenetic forces. But mitosis itself may not be instrumental in molding the tissue. We show that the structure of simple epithelia can be explained by an equilibrium model where energy-degenerate polygons in an entropy-maximizing tiling are described by a single geometric parameter encoding their inflatedness. The two types of tilings found numerically—ordered and disordered—closely reproduce the patterns observed in Drosophila, Hydra, and Xenopus and they generalize earlier theoretical results. Free of a specific cell self-energy, cell-cell interaction, and cell division kinetics, our model provides an insight into the universality of living and inanimate two-dimensional cellular structures.

  19. Upgrade of the ATLAS Tile Calorimeter Electronics

    NASA Astrophysics Data System (ADS)

    Carrió, F.; Tile Calorimeter System, ATLAS

    2015-02-01

    The Tile Calorimeter (TileCal) is the hadronic calorimeter covering the central region of the ATLAS experiment at LHC. The TileCal readout consists of about 10000 channels. The bulk of its upgrade will occur for the High Luminosity LHC phase (Phase-II) where the peak luminosity will increase 5 times compared to the design luminosity (1034 cm-2s-1) but with maintained energy (i.e. 7+7 TeV). An additional increase of the average luminosity with a factor of 2 can be achieved by luminosity levelling. This upgrade is expected to happen around 2024. The TileCal upgrade aims at replacing the majority of the on- and off- detector electronics to the extent that all calorimeter signals will be digitized and sent to the off-detector electronics in the counting room. To achieve the required reliability, redundancy has been introduced at different levels. Three different options are presently being investigated for the front-end electronic upgrade. Extensive test beam studies will determine which option will be selected. 10 Gbps optical links are used to read out all digitized data to the counting room while 5 Gbps down-links are used for synchronization, configuration and detector control. For the off-detector electronics a pre-processor (sROD) is being developed, which takes care of the initial trigger processing while temporarily storing the main data flow in pipeline and derandomizer memories. One demonstrator prototype module with the new calorimeter module electronics, but still compatible with the present system, is planned to be inserted in ATLAS this year.

  20. Mapping Signal Processing Kernels to Tiled Architectures

    DTIC Science & Technology

    2007-11-02

    attractive alternatives to monolithic computer architecture designs because they allow a larger design to be built from smaller modules and limit the...Computer Architectures. ACM Transactions on Computer Systems, 2(4):289–308, November 1984. [12] Steven Swanson, Ken Michelson , Andrew Schwerin, and...Program MIT Lincoln LaboratoryHPEC 2004-3 JML 28 Sep 2004 Tiled Architectures • Monolithic single-chip architectures are becoming rare in the industry

  1. Chemical Composition of Ceramic Tile Glazes

    NASA Astrophysics Data System (ADS)

    Anufrik, S. S.; Kurian, N. N.; Zhukova, I. I.; Znosko, K. F.; Belkov, M. V.

    2016-11-01

    We have carried out laser emission and x-ray fluorescence spectral analysis of glaze before and after its application to ceramic tile produced by Keramin JSC (Belarus). We have studied the internal microstructure of the ceramic samples. It was established that on the surface and within the bulk interior of all the samples, there are micropores of sizes ranging from a few micrometers to tens of micrometers and microcracks as long as several hundred micrometers. The presence of micropores on the surface of the ceramic tile leads to an increase in the water absorption level and a decrease in frost resistance. It was found that a decrease in the surface tension of ceramic tile coatings is promoted by substitution of sodium by potassium, silica by boric anhydride, magnesium and barium by calcium, CaO by sodium oxide, and SiO2 by chromium oxide. We carried out a comparative analysis of the chemical composition of glaze samples using S4 Pioneer and ElvaX x-ray fluorescence spectrometers and also an LIBS laser emission analyzer.

  2. Foam-on-Tile Damage Model

    NASA Technical Reports Server (NTRS)

    Koharchik, Michael; Murphy, Lindsay; Parker, Paul

    2012-01-01

    An impact model was developed to predict how three specific foam types would damage the Space Shuttle Orbiter insulating tiles. The inputs needed for the model are the foam type, the foam mass, the foam impact velocity, the foam impact incident angle, the type being impacted, and whether the tile is new or aged (has flown at least one mission). The model will determine if the foam impact will cause damage to the tile. If it can cause damage, the model will output the damage cavity dimensions (length, depth, entry angle, exit angle, and sidewall angles). It makes the calculations as soon as the inputs are entered (less than 1 second). The model allows for the rapid calculation of numerous scenarios in a short time. The model was developed from engineering principles coupled with significant impact testing (over 800 foam impact tests). This model is applicable to masses ranging from 0.0002 up to 0.4 pound (0.09 up to 181 g). A prior tool performed a similar function, but was limited to the assessment of a small range of masses and did not have the large test database for verification. In addition, the prior model did not provide outputs of the cavity damage length, entry angle, exit angle, or sidewall angles.

  3. Cesium diffusion in graphite

    SciTech Connect

    Evans, R.B. III; Davis, W. Jr.; Sutton, A.L. Jr.

    1980-05-01

    Experiments on diffusion of /sup 137/Cs in five types of graphite were performed. The document provides a completion of the report that was started and includes a presentation of all of the diffusion data, previously unpublished. Except for data on mass transfer of /sup 137/Cs in the Hawker-Siddeley graphite, analyses of experimental results were initiated but not completed. The mass transfer process of cesium in HS-1-1 graphite at 600 to 1000/sup 0/C in a helium atmosphere is essentially pure diffusion wherein values of (E/epsilon) and ..delta..E of the equation D/epsilon = (D/epsilon)/sub 0/ exp (-..delta..E/RT) are about 4 x 10/sup -2/ cm/sup 2//s and 30 kcal/mole, respectively.

  4. Irradiation Creep in Graphite

    SciTech Connect

    Ubic, Rick; Butt, Darryl; Windes, William

    2014-03-13

    An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarly characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.

  5. Coatings for graphite fibers

    NASA Technical Reports Server (NTRS)

    Galasso, F. S.; Scola, D. A.; Veltri, R. D.

    1980-01-01

    Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

  6. Superlubricity of Graphite

    NASA Astrophysics Data System (ADS)

    Dienwiebel, Martin; Verhoeven, Gertjan S.; Pradeep, Namboodiri; Frenken, Joost W.; Heimberg, Jennifer A.; Zandbergen, Henny W.

    2004-03-01

    Using a home-built frictional force microscope that is able to detect forces in three dimensions with a lateral force resolution down to 15 pN, we have studied the energy dissipation between a tungsten tip sliding over a graphite surface in dry contact. By measuring atomic-scale friction as a function of the rotational angle between two contacting bodies, we show that the origin of the ultralow friction of graphite lies in the incommensurability between rotated graphite layers, an effect proposed under the name of “superlubricity” [

    M. Hirano and K. Shinjo, Phys. Rev. BPRBMDO0163-1829 41, 11 837 (1990)10.1103/PhysRevB.41.11837
    ].

  7. Improved graphite furnace atomizer

    DOEpatents

    Siemer, D.D.

    1983-05-18

    A graphite furnace atomizer for use in graphite furnace atomic absorption spectroscopy is described wherein the heating elements are affixed near the optical path and away from the point of sample deposition, so that when the sample is volatilized the spectroscopic temperature at the optical path is at least that of the volatilization temperature, whereby analyteconcomitant complex formation is advantageously reduced. The atomizer may be elongated along its axis to increase the distance between the optical path and the sample deposition point. Also, the atomizer may be elongated along the axis of the optical path, whereby its analytical sensitivity is greatly increased.

  8. Optimization Of Phase-Contrast Enhanced X-Ray Imaging Of D-T Layers

    SciTech Connect

    Kozioziemski, B

    2005-06-17

    Phase-contrast enhanced x-ray imaging has been demonstrated for characterization of D-T layers inside of beryllium shells. These first demonstrations used both scintillator and direct-detection imaging. This memo details tradeoffs between the two methods in order to optimize the imaging. The guiding principle for optimization is to minimize the exposure time while maximizing the signal-to-noise ratio at the D-T solid-vapor interface. Direct-detection and scintillator performance are comparable when imaging the full capsule. However, a scintillator allows for higher-resolution images necessary for studying local defects in the D-T layer.

  9. Interference Lattice-based Loop Nest Tilings for Stencil Computations

    NASA Technical Reports Server (NTRS)

    VanderWijngaart, Rob F.; Frumkin, Michael

    2000-01-01

    A common method for improving performance of stencil operations on structured multi-dimensional discretization grids is loop tiling. Tile shapes and sizes are usually determined heuristically, based on the size of the primary data cache. We provide a lower bound on the numbers of cache misses that must be incurred by any tiling, and a close achievable bound using a particular tiling based on the grid interference lattice. The latter tiling is used to derive highly efficient loop orderings. The total number of cache misses of a code is the sum of (necessary) cold misses and misses caused by elements being dropped from the cache between successive loads (replacement misses). Maximizing temporal locality is equivalent to minimizing replacement misses. Temporal locality of loop nests implementing stencil operations is optimized by tilings that avoid data conflicts. We divide the loop nest iteration space into conflict-free tiles, derived from the cache miss equation. The tiling involves the definition of the grid interference lattice an equivalence class of grid points whose images in main memory map to the same location in the cache-and the construction of a special basis for the lattice. Conflicts only occur on the boundaries of the tiles, unless the tiles are too thin. We show that the surface area of the tiles is bounded for grids of any dimensionality, and for caches of any associativity, provided the eccentricity of the fundamental parallelepiped (the tile spanned by the basis) of the lattice is bounded. Eccentricity is determined by two factors, aspect ratio and skewness. The aspect ratio of the parallelepiped can be bounded by appropriate array padding. The skewness can be bounded by the choice of a proper basis. Combining these two strategies ensures that pathologically thin tiles are avoided. They do not, however, minimize replacement misses per se. The reason is that tile visitation order influences the number of data conflicts on the tile boundaries. If two

  10. Graphite-based photovoltaic cells

    DOEpatents

    Lagally, Max; Liu, Feng

    2010-12-28

    The present invention uses lithographically patterned graphite stacks as the basic building elements of an efficient and economical photovoltaic cell. The basic design of the graphite-based photovoltaic cells includes a plurality of spatially separated graphite stacks, each comprising a plurality of vertically stacked, semiconducting graphene sheets (carbon nanoribbons) bridging electrically conductive contacts.

  11. Design optimization methods for genomic DNA tiling arrays

    PubMed Central

    Bertone, Paul; Trifonov, Valery; Rozowsky, Joel S.; Schubert, Falk; Emanuelsson, Olof; Karro, John; Kao, Ming-Yang; Snyder, Michael; Gerstein, Mark

    2006-01-01

    A recent development in microarray research entails the unbiased coverage, or tiling, of genomic DNA for the large-scale identification of transcribed sequences and regulatory elements. A central issue in designing tiling arrays is that of arriving at a single-copy tile path, as significant sequence cross-hybridization can result from the presence of non-unique probes on the array. Due to the fragmentation of genomic DNA caused by the widespread distribution of repetitive elements, the problem of obtaining adequate sequence coverage increases with the sizes of subsequence tiles that are to be included in the design. This becomes increasingly problematic when considering complex eukaryotic genomes that contain many thousands of interspersed repeats. The general problem of sequence tiling can be framed as finding an optimal partitioning of non-repetitive subsequences over a prescribed range of tile sizes, on a DNA sequence comprising repetitive and non-repetitive regions. Exact solutions to the tiling problem become computationally infeasible when applied to large genomes, but successive optimizations are developed that allow their practical implementation. These include an efficient method for determining the degree of similarity of many oligonucleotide sequences over large genomes, and two algorithms for finding an optimal tile path composed of longer sequence tiles. The first algorithm, a dynamic programming approach, finds an optimal tiling in linear time and space; the second applies a heuristic search to reduce the space complexity to a constant requirement. A Web resource has also been developed, accessible at http://tiling.gersteinlab.org, to generate optimal tile paths from user-provided DNA sequences. PMID:16365382

  12. 55. QUARRY TILE CUTTERS, SECOND FLOOR, NORTH WING. WORKERS PRESSED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    55. QUARRY TILE CUTTERS, SECOND FLOOR, NORTH WING. WORKERS PRESSED THE CUTTERS INTO SLABS OF CLAY, LIFTED THEM ONTO DRYING BOARDS AND PRESSED THE PLUNGERS TO RELEASE THE CUT TILES. REPRODUCTIONS CUTTERS ARE NOT USED IN PRODUCTION. WOODEN FORMS FOR PRODUCING CLAY SLABS WITH ROLLING PINS REST AGAINST THE WALL. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  13. (Irradiation creep of graphite)

    SciTech Connect

    Kennedy, C.R.

    1990-12-21

    The traveler attended the Conference, International Symposium on Carbon, to present an invited paper, Irradiation Creep of Graphite,'' and chair one of the technical sessions. There were many papers of particular interest to ORNL and HTGR technology presented by the Japanese since they do not have a particular technology embargo and are quite open in describing their work and results. In particular, a paper describing the failure of Minor's law to predict the fatigue life of graphite was presented. Although the conference had an international flavor, it was dominated by the Japanese. This was primarily a result of geography; however, the work presented by the Japanese illustrated an internal program that is very comprehensive. This conference, a result of this program, was better than all other carbon conferences attended by the traveler. This conference emphasizes the need for US participation in international conferences in order to stay abreast of the rapidly expanding HTGR and graphite technology throughout the world. The United States is no longer a leader in some emerging technologies. The traveler was surprised by the Japanese position in their HTGR development. Their reactor is licensed and the major problem in their graphite program is how to eliminate it with the least perturbation now that most of the work has been done.

  14. GRAPHITE BONDING METHOD

    DOEpatents

    King, L.D.P.

    1964-02-25

    A process for bonding or joining graphite members together in which a thin platinum foil is placed between the members, heated in an inert atmosphere to a temperature of 1800 deg C, and then cooled to room temperature is described. (AEC)

  15. Structural graphitic carbon foams

    SciTech Connect

    Kearns, K.M.; Anderson, H.J.

    1998-12-31

    Graphitic carbon foams are a unique material form with very high structural and thermal properties at a light weight. A process has been developed to produce microcellular, open-celled graphitic foams. The process includes heating a mesophase pitch preform above the pitch melting temperature in a pressurized reactor. At the appropriate time, the pressure is released, the gas nucleates bubbles, and these bubbles grow forming the pitch into the foam structure. The resultant foamed pitch is then stabilized in an oxygen environment. At this point a rigid structure exists with some mechanical integrity. The foam is then carbonized to 800 C followed by a graphitization to 2700 C. The shear action from the growing bubbles aligns the graphitic planes along the foam struts to provide the ideal structure for good mechanical properties. Some of these properties have been characterized for some of the foam materials. It is known that variations of the blowing temperature, blowing pressure and saturation time result in foams of variously sized with mostly open pores; however, the mechanism of bubble nucleation is not known. Therefore foams were blown with various gases to begin to determine the nucleation method. These gases are comprised of a variety of molecular weights as well as a range of various solubility levels. By examining the resultant structures of the foam, differences were noted to develop an explanation of the foaming mechanism.

  16. Coatings for Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Galasso, F. S.; Scola, D. A.; Veltri, R. D.

    1980-01-01

    Several approaches for applying high resistance coatings continuously to graphite yarn were investigated. Two of the most promising approaches involved (1) chemically vapor depositing (CVD) SiC coatings on the surface of the fiber followed by oxidation, and (2) drawing the graphite yarn through an organo-silicone solution followed by heat treatments. In both methods, coated fibers were obtained which exhibited increased electrical resistances over untreated fibers and which were not degraded. This work was conducted in a previous program. In this program, the continuous CVD SiC coating process used on HTS fiber was extended to the coating of HMS, Celion 6000, Celion 12000 and T-300 graphite fiber. Electrical resistances three order of magnitude greater than the uncoated fiber were measured with no significant degradation of the fiber strength. Graphite fibers coated with CVD Si3N4 and BN had resistances greater than 10(exp 6) ohm/cm. Lower pyrolysis temperatures were used in preparing the silica-like coatings also resulting in resistances as high as three orders of magnitude higher than the uncoated fiber. The epoxy matrix composites prepared using these coated fibers had low shear strengths indicating that the coatings were weak.

  17. NASA TileWorld manual (system version 2.2)

    NASA Technical Reports Server (NTRS)

    Philips, Andrew B.; Bresina, John L.

    1991-01-01

    The commands are documented of the NASA TileWorld simulator, as well as providing information about how to run it and extend it. The simulator, implemented in Common Lisp with Common Windows, encodes a particular range in a spectrum of domains, for controllable research experiments. TileWorld consists of a two dimensional grid of cells, a set of polygonal tiles, and a single agent which can grasp and move tiles. In addition to agent executable actions, there is an external event over which the agent has not control; this event correspond to a 'gust of wind'.

  18. Geopolymers as potential repair material in tiles conservation

    NASA Astrophysics Data System (ADS)

    Geraldes, Catarina F. M.; Lima, Augusta M.; Delgado-Rodrigues, José; Mimoso, João Manuel; Pereira, Sílvia R. M.

    2016-03-01

    The restoration materials currently used to fill gaps in historical architectural tiles (e.g. lime or organic resin pastes) usually show serious drawbacks in terms of compatibility, effectiveness or durability. The existing solutions do not fully protect Portuguese faïence tiles ( azulejos) in outdoor conditions and frequently result in further deterioration. Geopolymers can be a potential solution for tile lacunae infill, given the chemical-mineralogical similitude to the ceramic body, and also the durability and versatile range of physical properties that can be obtained through the manipulation of their formulation and curing conditions. This work presents and discusses the viability of the use of geopolymeric pastes to fill lacunae in tiles or to act as "cold" cast ceramic tile surrogates reproducing missing tile fragments. The formulation of geopolymers, namely the type of activators, the alumino-silicate source, the quantity of water required for adequate workability and curing conditions, was studied. The need for post-curing desalination was also considered envisaging their application in the restoration of outdoor historical architectural tiles frequently exposed to adverse environmental conditions. The possible advantages and disadvantages of the use of geopolymers in the conservation of tiles are also discussed. The results obtained reveal that geopolymers pastes are a promising material for the restoration of tiles, when compared to other solutions currently in use.

  19. Magnetic frustration of graphite oxide

    NASA Astrophysics Data System (ADS)

    Lee, Dongwook; Seo, Jiwon

    2017-03-01

    Delocalized π electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, π electrons develop ferromagnetism due to the unique structure of the material. The π electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negative Curie temperature, field irreversibility, and slow relaxation. The overall results indicate that magnetic moments in graphite oxide slowly interact and develop magnetic frustration.

  20. Magnetic frustration of graphite oxide

    PubMed Central

    Lee, Dongwook; Seo, Jiwon

    2017-01-01

    Delocalized π electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, π electrons develop ferromagnetism due to the unique structure of the material. The π electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negative Curie temperature, field irreversibility, and slow relaxation. The overall results indicate that magnetic moments in graphite oxide slowly interact and develop magnetic frustration. PMID:28327606

  1. Milestone 5 test report. Task 5, subtask 5.2: Tile to foam strength tests

    NASA Technical Reports Server (NTRS)

    Greenberg, H. S.

    1994-01-01

    This report summarizes work that has been performed to date on the strength of a cryotank insulation system using Rohacell foam and TUFI-coated AETB-12 ceramic tiles directly bonded to a simulated graphite-epoxy tank wall. Testing utilized a custom specimen design which consists of a long tensile specimen with eccentric loading to induce curvature similar to the curvature expected due to 'pillowing' of the tank when pressurized. A finite element model was constructed to predict the specific element strains in the test article, and to assist with design of the test specimen to meet the specific goals of curvature and laminate strain. The results indicate that the heat treated 3.25-pcf density Rohacell foam does not provide sufficient strength for the induced stresses due to curvature and stress concentration at the RTV bondline to the TUFI tile. The test was repeated using higher density non-heat treated Rohacell foam (6.9 pcf) without foam failure. The finite element model was shown to predict specimen behavior, and validation of the model was successful. It is pertinent to mention that the analyses described herein accurately predicted the failure of the heat treated foams and based on this analysis method it is expected that the untreated 3.25 pcf Rohacell foam will be successful.

  2. Tungsten Deposition on Graphite using Plasma Enhanced Chemical Vapour Deposition.

    NASA Astrophysics Data System (ADS)

    Sharma, Uttam; Chauhan, Sachin S.; Sharma, Jayshree; Sanyasi, A. K.; Ghosh, J.; Choudhary, K. K.; Ghosh, S. K.

    2016-10-01

    The tokamak concept is the frontrunner for achieving controlled thermonuclear reaction on earth, an environment friendly way to solve future energy crisis. Although much progress has been made in controlling the heated fusion plasmas (temperature ∼ 150 million degrees) in tokamaks, technological issues related to plasma wall interaction topic still need focused attention. In future, reactor grade tokamak operational scenarios, the reactor wall and target plates are expected to experience a heat load of 10 MW/m2 and even more during the unfortunate events of ELM's and disruptions. Tungsten remains a suitable choice for the wall and target plates. It can withstand high temperatures, its ductile to brittle temperature is fairly low and it has low sputtering yield and low fuel retention capabilities. However, it is difficult to machine tungsten and hence usages of tungsten coated surfaces are mostly desirable. To produce tungsten coated graphite tiles for the above-mentioned purpose, a coating reactor has been designed, developed and made operational at the SVITS, Indore. Tungsten coating on graphite has been attempted and successfully carried out by using radio frequency induced plasma enhanced chemical vapour deposition (rf -PECVD) for the first time in India. Tungsten hexa-fluoride has been used as a pre-cursor gas. Energy Dispersive X-ray spectroscopy (EDS) clearly showed the presence of tungsten coating on the graphite samples. This paper presents the details of successful operation and achievement of tungsten coating in the reactor at SVITS.

  3. Photographing Shuttle Thermal Tiles in Space

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Launched on July 26, 2005 from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes (CMGs). STS-114 also carried the Raffaello Multi-Purpose Logistics Module and the External Stowage Platform-2. A major focus of the mission was the testing and evaluation of new Space Shuttle flight safety, which included new inspection and repair techniques. Upon its approach to the International Space Station (ISS), the Space Shuttle Discovery underwent a photography session in order to assess any damages that may have occurred during its launch and/or journey through Space. The mission's third and final Extra Vehicular Activity (EVA) included taking a close-up look and the repair of the damaged heat shield. Gap fillers were removed from between the orbiter's heat-shielding tiles located on the craft's underbelly. Never before had any repairs been done to an orbiter while still in space. This particular photo was taken by astronaut Stephen K. Robinson, STS-114 mission specialist, whose shadow is visible on the thermal protection tiles.

  4. Computerized Machine for Cutting Space Shuttle Thermal Tiles

    NASA Technical Reports Server (NTRS)

    Ramirez, Luis E.; Reuter, Lisa A.

    2009-01-01

    A report presents the concept of a machine aboard the space shuttle that would cut oversized thermal-tile blanks to precise sizes and shapes needed to replace tiles that were damaged or lost during ascent to orbit. The machine would include a computer-controlled jigsaw enclosed in a clear acrylic shell that would prevent escape of cutting debris. A vacuum motor would collect the debris into a reservoir and would hold a tile blank securely in place. A database stored in the computer would contain the unique shape and dimensions of every tile. Once a broken or missing tile was identified, its identification number would be entered into the computer, wherein the cutting pattern associated with that number would be retrieved from the database. A tile blank would be locked into a crib in the machine, the shell would be closed (proximity sensors would prevent activation of the machine while the shell was open), and a "cut" command would be sent from the computer. A blade would be moved around the crib like a plotter, cutting the tile to the required size and shape. Once the tile was cut, an astronaut would take a space walk for installation.

  5. Low-Density, Aerogel-Filled Thermal-Insulation Tiles

    NASA Technical Reports Server (NTRS)

    Santos, Maryann; Heng, Vann; Barney, Andrea; Oka, Kris; Droege, Michael

    2005-01-01

    Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6 lb/ft3 (about 53 to 200 kg/cu m). Results available at the time of reporting the information for this article showed that the thermal-insulation properties of the partially or fully aerogel- impregnated tiles were equivalent or superior to those of the corresponding non-impregnated tiles and that the partially impregnated tiles exhibited minimal (<1.5 percent) shrinkage after multiple exposures at a temperature of 2,300 F (1,260 C). Latest developments have shown that tiles containing aerogels at the higher end of the density range are stable after multiple exposures at the said temperature.

  6. Drainage water management effects on tile discharge and water quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) fluxes from tile drained watersheds have been implicated in water quality studies of the Mississippi River Basin, but the contribution of tile drains to N export in headwater watersheds is not well understood. The objective of this study was to ascertain seasonal and annual contribution...

  7. Creative Tiling: A Story of 1000-and-1 Curves

    ERIC Educational Resources Information Center

    Al-Darwish, Nasir

    2012-01-01

    We describe a procedure that utilizes symmetric curves for building artistic tiles. One particular curve was found to mesh nicely with hundreds other curves, resulting in eye-catching tiling designs. The results of our work serve as a good example of using ideas from 2-D graphics and algorithms in a practical web-based application.

  8. Future Armor Tiles MIL-STD-166O Tests.

    DTIC Science & Technology

    1997-02-01

    The U.S. Army Defense Ammunition Center (DAC), Validation Engineering Division, was tasked by DAC to conduct MIL- STD -1660 tests on armor tile...containers on a wooden pallet. This report contains test results with the armor tile containers on a wooden pallet meeting MIL- STD -1660, Design Criteria for Ammunition Unit Loads, requirements.

  9. Highly Symmetric and Congruently Tiled Meshes for Shells and Domes

    PubMed Central

    Rasheed, Muhibur; Bajaj, Chandrajit

    2016-01-01

    We describe the generation of all possible shell and dome shapes that can be uniquely meshed (tiled) using a single type of mesh face (tile), and following a single meshing (tiling) rule that governs the mesh (tile) arrangement with maximal vertex, edge and face symmetries. Such tiling arrangements or congruently tiled meshed shapes, are frequently found in chemical forms (fullerenes or Bucky balls, crystals, quasi-crystals, virus nano shells or capsids), and synthetic shapes (cages, sports domes, modern architectural facades). Congruently tiled meshes are both aesthetic and complete, as they support maximal mesh symmetries with minimal complexity and possess simple generation rules. Here, we generate congruent tilings and meshed shape layouts that satisfy these optimality conditions. Further, the congruent meshes are uniquely mappable to an almost regular 3D polyhedron (or its dual polyhedron) and which exhibits face-transitive (and edge-transitive) congruency with at most two types of vertices (each type transitive to the other). The family of all such congruently meshed polyhedra create a new class of meshed shapes, beyond the well-studied regular, semi-regular and quasi-regular classes, and their duals (platonic, Catalan and Johnson). While our new mesh class is infinite, we prove that there exists a unique mesh parametrization, where each member of the class can be represented by two integer lattice variables, and moreover efficiently constructable. PMID:27563368

  10. Intercalated Graphite Fiber Conductor.

    DTIC Science & Technology

    1980-12-01

    Lightweight electrical conductors were developed from graphitic fibers inter- calated with highly electrophilic intercalants. Conductance increases of...intercalated with highly electrophilic molecules ("intercalants") to en- hance their electrical conductivity. Evaluation of the elec- trical resistance of two...corrosion resistant to fluorine containing chemicals. Since the moisture permeability of the TFE is much less than that of the FEP, attempts were made to

  11. Improved Graphite Fiber Adhesion.

    DTIC Science & Technology

    1981-09-01

    determined from a variety of surface analysis techniques , the oxygen-containing functional groups on commercial AS-i graphite fiber are predominantly...heterogenity within the fiber itself or experimental errors within the technique . In the limited time devoted to this work we did not devise a procedure...samples. Drzal optically measured the diameter of each fiber tested. Figure 6 shows the linear regression analysis plot used to determine the polar and

  12. Microcracks in nuclear graphite and highly oriented pyrolytic graphite (HOPG)

    NASA Astrophysics Data System (ADS)

    Wen, Keyun; Marrow, James; Marsden, Barry

    2008-10-01

    Microcracks with varied length and width are observed in nuclear grade graphite and highly oriented pyrolytic graphite (HOPG) by transmission electron microscopy. In situ observations show that these cracks tend to close up on heating the sample. The crystal dimensional change from in situ electron-irradiation also causes the closure of the cracks. Although some of the cracks may be identifiable as accommodation porosity (i.e. Mrozowski cracks), others appear to have already formed prior to carbonization and graphitization.

  13. Detection of Leptomeningeal Metastasis by Contrast-Enhanced 3D T1-SPACE: Comparison with 2D FLAIR and Contrast-Enhanced 2D T1-Weighted Images

    PubMed Central

    Gil, Bomi; Hwang, Eo-Jin; Lee, Song; Jang, Jinhee; Jung, So-Lyung; Ahn, Kook-Jin; Kim, Bum-soo

    2016-01-01

    Introduction To compare the diagnostic accuracy of contrast-enhanced 3D(dimensional) T1-weighted sampling perfection with application-optimized contrasts by using different flip angle evolutions (T1-SPACE), 2D fluid attenuated inversion recovery (FLAIR) images and 2D contrast-enhanced T1-weighted image in detection of leptomeningeal metastasis except for invasive procedures such as a CSF tapping. Materials and Methods Three groups of patients were included retrospectively for 9 months (from 2013-04-01 to 2013-12-31). Group 1 patients with positive malignant cells in CSF cytology (n = 22); group 2, stroke patients with steno-occlusion in ICA or MCA (n = 16); and group 3, patients with negative results on MRI, whose symptom were dizziness or headache (n = 25). A total of 63 sets of MR images are separately collected and randomly arranged: (1) CE 3D T1-SPACE; (2) 2D FLAIR; and (3) CE T1-GRE using a 3-Tesla MR system. A faculty neuroradiologist with 8-year-experience and another 2nd grade trainee in radiology reviewed each MR image- blinded by the results of CSF cytology and coded their observations as positives or negatives of leptomeningeal metastasis. The CSF cytology result was considered as a gold standard. Sensitivity and specificity of each MR images were calculated. Diagnostic accuracy was compared using a McNemar’s test. A Cohen's kappa analysis was performed to assess inter-observer agreements. Results Diagnostic accuracy was not different between 3D T1-SPACE and CSF cytology by both raters. However, the accuracy test of 2D FLAIR and 2D contrast-enhanced T1-weighted GRE was inconsistent by the two raters. The Kappa statistic results were 0.657 (3D T1-SPACE), 0.420 (2D FLAIR), and 0.160 (2D contrast-enhanced T1-weighted GRE). The 3D T1-SPACE images showed the highest inter-observer agreements between the raters. Conclusions Compared to 2D FLAIR and 2D contrast-enhanced T1-weighted GRE, contrast-enhanced 3D T1 SPACE showed a better detection rate of

  14. METHOD OF FABRICATING A GRAPHITE MODERATED REACTOR

    DOEpatents

    Kratz, H.R.

    1963-05-01

    S>A nuclear reactor formed of spaced bodies of uranium and graphite blocks is improved by diffusing helium through the graphite blocks in order to replace the air in the pores of the graphite with helium. The helium-impregnated graphite conducts heat better, and absorbs neutrons less, than the original air- impregnated graphite. (AEC)

  15. CMB-13 research on carbon and graphite

    NASA Technical Reports Server (NTRS)

    Smith, M. C.

    1972-01-01

    Preliminary results of the research on carbon and graphite accomplished during this report period are presented. Included are: particle characteristics of Santa Maria fillers, compositions and density data for hot-molded Santa Maria graphites, properties of hot-molded Santa Maria graphites, and properties of hot-molded anisotropic graphites. Ablation-resistant graphites are also discussed.

  16. Radiation shielding design of BNCT treatment room for D-T neutron source.

    PubMed

    Pouryavi, Mehdi; Farhad Masoudi, S; Rahmani, Faezeh

    2015-05-01

    Recent studies have shown that D-T neutron generator can be used as a proper neutron source for Boron Neutron Capture Therapy (BNCT) of deep-seated brain tumors. In this paper, radiation shielding calculations have been conducted based on the computational method for designing a BNCT treatment room for a recent proposed D-T neutron source. By using the MCNP-4C code, the geometry of the treatment room has been designed and optimized in such a way that the equivalent dose rate out of the treatment room to be less than 0.5μSv/h for uncontrolled areas. The treatment room contains walls, monitoring window, maze and entrance door. According to the radiation protection viewpoint, dose rate results of out of the proposed room showed that using D-T neutron source for BNCT is safe.

  17. Poly(dA:dT) tracts: major determinants of nucleosome organization.

    PubMed

    Segal, Eran; Widom, Jonathan

    2009-02-01

    Homopolymeric stretches of deoxyadenosine nucleotides (A's) on one strand of double-stranded DNA, referred to as poly(dA:dT) tracts or A-tracts, are overabundant in eukaryotic genomes. They have unusual structural, dynamic, and mechanical properties, and may resist sharp bending. Such unusual material properties, together with their overabundance in eukaryotes, raised the possibility that poly(dA:dT) tracts might function in eukaryotes to influence the organization of nucleosomes at many genomic regions. Recent genome-wide studies strongly confirm these ideas and suggest that these tracts play major roles in chromatin organization and genome function. Here we review what is known about poly(dA:dT) tracts and how they work.

  18. Optical design and studies of a tiled single grating pulse compressor for enhanced parametric space and compensation of tiling errors

    NASA Astrophysics Data System (ADS)

    Daiya, D.; Patidar, R. K.; Sharma, J.; Joshi, A. S.; Naik, P. A.; Gupta, P. D.

    2017-04-01

    A new optical design of tiled single grating pulse compressor has been proposed, set-up and studied. The parametric space, i.e. the laser beam diameters that can be accommodated in the pulse compressor for the given range of compression lengths, has been calculated and shown to have up to two fold enhancement in comparison to our earlier proposed optical designs. The new optical design of the tiled single grating pulse compressor has an additional advantage of self compensation of various tiling errors like longitudinal and lateral piston, tip and groove density mismatch, compared to the earlier designs. Experiments have been carried out for temporal compression of 650 ps positively chirped laser pulses, at central wavelength 1054 nm, down to 235 fs in the tiled grating pulse compressor set up with the proposed design. Further, far field studies have been performed to show the desired compensation of the tiling errors takes place in the new compressor.

  19. Heat exchanger using graphite foam

    DOEpatents

    Campagna, Michael Joseph; Callas, James John

    2012-09-25

    A heat exchanger is disclosed. The heat exchanger may have an inlet configured to receive a first fluid and an outlet configured to discharge the first fluid. The heat exchanger may further have at least one passageway configured to conduct the first fluid from the inlet to the outlet. The at least one passageway may be composed of a graphite foam and a layer of graphite material on the exterior of the graphite foam. The layer of graphite material may form at least a partial barrier between the first fluid and a second fluid external to the at least one passageway.

  20. Tile-in-ONE: A web platform which integrates Tile Calorimeter data quality and calibration assessment

    NASA Astrophysics Data System (ADS)

    Sivolella, A.; Ferreira, F.; Maidantchik, C.; Solans, C.; Solodkov, A.; Burghgrave, B.; Smirnov, Y.

    2015-12-01

    The ATLAS Tile Calorimeter collaboration assesses the quality of calibration data in order to ensure its proper operation. A number of tasks is then performed by executing several tools and accessing web systems, which were independently developed to meet distinct collaboration's requirements and do not necessarily are connected with each other. Thus, to attend the collaboration needs, several programs are usually implemented without a global perspective of the detector, requiring basic software features. In addition, functionalities may overlap in their objectives and frequently replicate resources retrieval mechanisms. Tile-in-ONE is a designed and implemented platform that assembles various web systems used by the calorimeter community through a single framework and a standard technology. It provides an infrastructure to support the code implementation, avoiding duplication of work while integrating with an overall view of the detector status. Database connectors smooth the process of information access since developers do not need to be aware of where records are placed and how to extract them. Within the environment, a dashboard stands for a particular Tile operation aspect and gets together plug-ins, i.e. software components that add specific features to an existing application. A server contains the platform core, which represents the basic environment to deal with the configuration, manage user settings and load plug-ins at runtime. A web middleware assists users to develop their own plug-ins, perform tests and integrate them into the platform as a whole. Backends are employed to allow that any type of application is interpreted and displayed in a uniform way. This paper describes Tile-in-ONE web platform.

  1. Floor tile and mastic removal project report

    SciTech Connect

    Not Available

    1992-11-01

    A test program was developed and coordinated with State and Federal Regulators and carried out at Fort Sill, Oklahoma. This program was carefully designed to create the worst conditions in order to evaluate whether asbestos fibers are released when asbestos containing floor tile and mastic are removed. There were over 1,000 samples taken and analyzed during the execution of the program. The conclusions reached were based upon analysis of the critical samples using the Transmission Electron Microscope (TEM) technology. Additionally, the TEM procedures were used to evaluate personnel samples to determine whether those fibers found were asbestos or other materials. Most of the (TEM) samples were analyzed by the US Environmental Protection Agency (EPA) Risk Reduction Engineering Laboratory in Cincinnati, Ohio.

  2. Tile-Compressed FITS Kernel for IRAF

    NASA Astrophysics Data System (ADS)

    Seaman, R.

    2011-07-01

    The Flexible Image Transport System (FITS) is a ubiquitously supported standard of the astronomical community. Similarly, the Image Reduction and Analysis Facility (IRAF), developed by the National Optical Astronomy Observatory, is a widely used astronomical data reduction package. IRAF supplies compatibility with FITS format data through numerous tools and interfaces. The most integrated of these is IRAF's FITS image kernel that provides access to FITS from any IRAF task that uses the basic IMIO interface. The original FITS kernel is a complex interface of purpose-built procedures that presents growing maintenance issues and lacks recent FITS innovations. A new FITS kernel is being developed at NOAO that is layered on the CFITSIO library from the NASA Goddard Space Flight Center. The simplified interface will minimize maintenance headaches as well as add important new features such as support for the FITS tile-compressed (fpack) format.

  3. Spectral response data for development of cool coloured tile coverings

    NASA Astrophysics Data System (ADS)

    Libbra, Antonio; Tarozzi, Luca; Muscio, Alberto; Corticelli, Mauro A.

    2011-03-01

    Most ancient or traditional buildings in Italy show steep-slope roofs covered by red clay tiles. As the rooms immediately below the roof are often inhabited in historical or densely urbanized centres, the combination of low solar reflectance of tile coverings and low thermal inertia of either wooden roof structures or sub-tile insulation panels makes summer overheating a major problem. The problem can be mitigated by using tiles coated with cool colours, that is colours with the same spectral response of clay tiles in the visible, but highly reflecting in the near infrared range, which includes more than half of solar radiation. Cool colours can yield the same visible aspect of common building surfaces, but higher solar reflectance. Studies aimed at developing cool colour tile coverings for traditional Italian buildings have been started. A few coating solutions with the typical red terracotta colour have been produced and tested in the laboratory, using easily available materials. The spectral response and the solar reflectance have been measured and compared with that of standard tiles.

  4. Graphitic packing removal tool

    DOEpatents

    Meyers, Kurt Edward; Kolsun, George J.

    1997-01-01

    Graphitic packing removal tools for removal of the seal rings in one piece. he packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

  5. Graphitic packing removal tool

    DOEpatents

    Meyers, K.E.; Kolsun, G.J.

    1997-11-11

    Graphitic packing removal tools for removal of the seal rings in one piece are disclosed. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal. 5 figs.

  6. Graphitic packing removal tool

    SciTech Connect

    Meyers, K.E.; Kolsun, G.J.

    1996-12-31

    Graphitic packing removal tools are described for removal of the seal rings in one piece from valves and pumps. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

  7. DNA tile based self-assembly: building complex nanoarchitectures.

    PubMed

    Lin, Chenxiang; Liu, Yan; Rinker, Sherri; Yan, Hao

    2006-08-11

    DNA tile based self-assembly provides an attractive route to create nanoarchitectures of programmable patterns. It also offers excellent scaffolds for directed self-assembly of nanometer-scale materials, ranging from nanoparticles to proteins, with potential applications in constructing nanoelectronic/nanophotonic devices and protein/ligand nanoarrays. This Review first summarizes the currently available DNA tile toolboxes and further emphasizes recent developments toward self-assembling DNA nanostructures with increasing complexity. Exciting progress using DNA tiles for directed self-assembly of other nanometer scale components is also discussed.

  8. Affine reflection groups for tiling applications: Knot theory and DNA

    NASA Astrophysics Data System (ADS)

    Bodner, M.; Patera, J.; Peterson, M.

    2012-01-01

    We present in this paper some non-conventional applications of affine Weyl groups Waff of rank 2, the symmetry group of the tiling/lattice. We first develop and present the tools for applications requiring tilings of a real Euclidean plane {R}^2. We then elucidate the equivalence of these tilings with 2D projections of knots. The resulting mathematical structure provides a framework within which is encompassed recent work utilizing knot theory for modeling the structure and function of genetic molecules, specifically the action of particular enzymes in altering the topology of DNA in site-specific recombination.

  9. 57. ORIGINAL TILE PRESS AND EXPERIMENTAL DENTAL KILN, SECOND FLOOR, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    57. ORIGINAL TILE PRESS AND EXPERIMENTAL DENTAL KILN, SECOND FLOOR, NORTH WING, HENRY MERCER USED THE KILN FOR HIS EARLIEST GLAZE TESTS. THE PRESS WAS DESIGNED TO BE USED WITH METAL CASED MOLDS. SINCE ONLY THE EARLIEST TILE DESIGNS ARE IN METAL CASES. THIS TECHNIQUE WAS PROBABLY DISCONTINUED. THIS PRESS WAS, THEREFORE, PROBABLY NOT USED EXTENSIVELY AT THIS SITE. THE UPPER PART OF GLAZE KILN No. 2 IS AT THE LEFT REAR. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  10. Investigating D-T Reaction Spectra with the Gas Cherenkov Detector

    NASA Astrophysics Data System (ADS)

    Huff, Michael A.; Kim, Yong Ho; McEvoy, Aaron; Young, Carlton S.; Mack, Joe M.; Herrmann, Hans W.; Horsfield, Colin J.

    2010-11-01

    In this study, a new analysis of the gamma ray spectra of the D-T fusion reaction using a Gas Cherenkov Detector (GCD) is presented. The D-T reaction is an essential process to understand for the future of fusion science. The reaction produces a He^5* nucleus that usually decays into a He^4 + n. It has been seen that this reaction produces a 16.75 MeV gamma ray .0025% of the time. The Gamma Ray History (GRH) group at Los Alamos proposes that there is an even less often occurrence where a gamma ray of around 12 MeV is produced. As the truth of this statement would affect the future potential yield of fusion reactors using D-T fuel, it is worth investigating. D-T spectra were obtained by detecting the produced gamma ray with the GCD at the University of Rochester OMEGA laser facility. A GCD response curve, calculated by the Monte Carlo modeling software ACCEPT, was used to forward convolve theoretical spectra into what the theoretical curves would have looked like in the GCD data. Results are presented.

  11. REFRACTORY COATING FOR GRAPHITE MOLDS

    DOEpatents

    Stoddard, S.D.

    1958-06-24

    Refractory coating for graphite molds used in the casting of uranium is described. The coating is an alumino-silicate refractory composition which may be used as a mold surface in solid form or as a coating applied to the graphite mold. The composition consists of a mixture of ball clay, kaolin, alumina cement, alumina, water, sodium silicate, and sodium carbonate.

  12. Cryotribology of diamond and graphite

    SciTech Connect

    Iwasa, Yukikazu; Ashaboglu, A.F.; Rabinowicz, E.R.

    1996-12-31

    An experimental study was carried out on the tribological behavior of materials of interest in cryogenic applications, focusing on diamond and graphite. Both natural diamond (referred in the text as diamond) and chemical-vapor-deposition (CVD) diamond (CVD-diamond) were used. The experiment was carried out using a pin-on-disk tribometer capable of operating at cryogenic temperatures, from 4.2 to 293 K. Two basic scenarios of testing were used: (1) frictional coefficient ({mu}) vs velocity (v) characteristics at constant temperatures; (2) {mu} vs temperature (T) behavior at fixed sliding speeds. For diamond/CVD-diamond, graphite/CVD-diamond, stainless steel/CVD-diamond pairs, {mu}`s are virtually velocity independent. For each of diamond/graphite, alumina/graphite, and graphite/graphite pairs, the {partial_derivative}{mu}/{partial_derivative}v characteristic is favorable, i.e., positive. For diamond/CVD-diamond and graphite/CVD-diamond pairs, {mu}`s are nearly temperature independent between in the range 77 - 293 K. Each {mu} vs T plot for pin materials sliding on graphite disks has a peak at a temperature in the range 100 - 200 K.

  13. BioTile, A Perl based tool for the identification of differentially enriched regions in tiling microarray data

    PubMed Central

    2013-01-01

    Background Genome-wide tiling array experiments are increasingly used for the analysis of DNA methylation. Because DNA methylation patterns are tissue and cell type specific, the detection of differentially methylated regions (DMRs) with small effect size is a necessary feature of tiling microarray ‘peak’ finding algorithms, as cellular heterogeneity within a studied tissue may lead to a dilution of the phenotypically relevant effects. Additionally, the ability to detect short length DMRs is necessary as biologically relevant signal may occur in focused regions throughout the genome. Results We present a free open-source Perl application, Binding Intensity Only Tile array analysis or “BioTile”, for the identification of differentially enriched regions (DERs) in tiling array data. The application of BioTile to non-smoothed data allows for the identification of shorter length and smaller effect-size DERs, while correcting for probe specific variation by inversely weighting on probe variance through a permutation corrected meta-analysis procedure employed at identified regions. BioTile exhibits higher power to identify significant DERs of low effect size and across shorter genomic stretches as compared to other peak finding algorithms, while not sacrificing power to detect longer DERs. Conclusion BioTile represents an easy to use analysis option applicable to multiple microarray platforms, allowing for its integration into the analysis workflow of array data analysis. PMID:23452827

  14. Baseline Graphite Characterization: First Billet

    SciTech Connect

    Mark C. Carroll; Joe Lords; David Rohrbaugh

    2010-09-01

    The Next Generation Nuclear Plant Project Graphite Research and Development program is currently establishing the safe operating envelope of graphite core components for a very high temperature reactor design. To meet this goal, the program is generating the extensive amount of quantitative data necessary for predicting the behavior and operating performance of the available nuclear graphite grades. In order determine the in-service behavior of the graphite for the latest proposed designs, two main programs are underway. The first, the Advanced Graphite Creep (AGC) program, is a set of experiments that are designed to evaluate the irradiated properties and behavior of nuclear grade graphite over a large spectrum of temperatures, neutron fluences, and compressive loads. Despite the aggressive experimental matrix that comprises the set of AGC test runs, a limited amount of data can be generated based upon the availability of space within the Advanced Test Reactor and the geometric constraints placed on the AGC specimens that will be inserted. In order to supplement the AGC data set, the Baseline Graphite Characterization program will endeavor to provide supplemental data that will characterize the inherent property variability in nuclear-grade graphite without the testing constraints of the AGC program. This variability in properties is a natural artifact of graphite due to the geologic raw materials that are utilized in its production. This variability will be quantified not only within a single billet of as-produced graphite, but also from billets within a single lot, billets from different lots of the same grade, and across different billets of the numerous grades of nuclear graphite that are presently available. The thorough understanding of this variability will provide added detail to the irradiated property data, and provide a more thorough understanding of the behavior of graphite that will be used in reactor design and licensing. This report covers the

  15. Pristine graphite oxide.

    PubMed

    Dimiev, Ayrat; Kosynkin, Dmitry V; Alemany, Lawrence B; Chaguine, Pavel; Tour, James M

    2012-02-08

    Graphite oxide (GO) is a lamellar substance with an ambiguous structure due to material complexity. Recently published GO-related studies employ only one out of several existing models to interpret the experimental data. Because the models are different, this leads to confusion in understanding the nature of the observed phenomena. Lessening the structural ambiguity would lead to further developments in functionalization and use of GO. Here, we show that the structure and properties of GO depend significantly on the quenching and purification procedures, rather than, as is commonly thought, on the type of graphite used or oxidation protocol. We introduce a new purification protocol that produces a product that we refer to as pristine GO (pGO) in contrast to the commonly known material that we will refer to as conventional GO (cGO). We explain the differences between pGO and cGO by transformations caused by reaction with water. We produce ultraviolet-visible spectroscopic, Fourier transform infrared spectroscopic, solid-state nuclear magnetic resonance spectroscopic, thermogravimetric, and scanning electron microscopic analytical evidence for the structure of pGO. This work provides a new explanation for the acidity of GO solutions and allows us to add critical details to existing GO models.

  16. 45. Everett, Weinreb, photographer DETAIL, CEMENT TILE PATTERN FROM RECEPTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. Everett, Weinreb, photographer DETAIL, CEMENT TILE PATTERN FROM RECEPTION HALL LOOKING EAST ACROSS ARRIVAL LOBBY FLOOR - Los Angeles Union Passenger Terminal, Tracks & Shed, 800 North Alameda Street, Los Angeles, Los Angeles County, CA

  17. 44. Everett Weinreb, photographer DETAIL, CEMENT TILE PATTERN, FROM LOGGIA ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    44. Everett Weinreb, photographer DETAIL, CEMENT TILE PATTERN, FROM LOGGIA LOOKING EAST ACROSS RECEPTION HALL - Los Angeles Union Passenger Terminal, Tracks & Shed, 800 North Alameda Street, Los Angeles, Los Angeles County, CA

  18. South front, west part, showing wrought iron gates and tiling ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    South front, west part, showing wrought iron gates and tiling at the former main entrance. - San Bernardino Valley College, Life Science Building, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA

  19. 25. CAFETERIA Note remains of tile floor in foreground. Food ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. CAFETERIA Note remains of tile floor in foreground. Food cooked on the stove was served to workers in the eating area to the left of the counter (off picture). - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA

  20. 24. DETAIL VIEW OF TILE GAUGE IN INTERMEDIATE LOCK WALL, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. DETAIL VIEW OF TILE GAUGE IN INTERMEDIATE LOCK WALL, LOOKING NORTHEAST. NOTE STEEL WALL ARMOR EMBEDDED IN CONCRETE. - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 26, Alton, Madison County, IL

  1. Interference Heating to Cavities Between Simulated RSI Tiles

    NASA Technical Reports Server (NTRS)

    Johnson, C. B.

    1973-01-01

    Test results for full scale simulated surface insulation tiles on both the tunnel wall and in the free stream, for in-line and staggered tile orientations, are summarized as follows: (1) The staggered tile orientation has heating on the forward face which is a factor of 4.5 times higher than the heating to the forward face of the in-line tile orientation; (2) the longitudinal gap heating was the highest for the 0.3175 cm gap and the lowest for the 0.1587 cm gap; and (3) there was an order of magnitude decrease in the heating on the forward face of a spanwise gap when the gap size was decreased from 0.3175 cm to 0.1587 cm.

  2. ATLAS Tile Calorimeter performance with Run 1 data

    NASA Astrophysics Data System (ADS)

    Cerdá Alberich, L.

    2016-07-01

    The performance of the central hadronic calorimeter, TileCal, in the ATLAS Experiment at the Large Hadron Collider is studied using cosmic-ray muons and the large sample of proton-proton collisions acquired during the Run 1 of LHC (2010-2012). Results are presented for the precision of the absolute energy scale and timing, noise characterization, and time-stability of the detector. The results show that the Tile Calorimeter performance is within the design requirements of the detector.

  3. 56. ORIGINAL MOLDS. THE MORAVIAN POTTERY AND TILE WORKS HAS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. ORIGINAL MOLDS. THE MORAVIAN POTTERY AND TILE WORKS HAS APPROXIMATELY 6,000 PLASTER MOLDS OF VARIOUS TYPES, INCLUDING THE DEEP CAVITY MOLDS IN THE CENTER OF THE PHOTOGRAPH. THESE MOLDS PRODUCED ALLEGORICAL FIGURES TO BE INSTALLED AROUND THE CORNICES OF PUBLIC SCHOOLS. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  4. No inherent glassiness in a Penrose tiling quasicrystal

    SciTech Connect

    Strandburg, K.J.; Dressel, P.R.

    1988-11-01

    Consideration of the structure of the Penrose pattern has led to speculation that a system with a Penrose tiling ground state might be subject to inherent glassy behavior. Monte Carol simulations show, using a simple model of the energetics, that there is no inherent glassiness in the Penrose tiling. Thermodynamic quantities measured are completely reversible, displaying no observable hysterisis, and the system may be easily cooled from a highly disordered configuration into its lowest energy state. 11 refs., 7 figs.

  5. On the Minimum Weight Steiner Triangular Tiling problem

    SciTech Connect

    Doddi, S.; Zhu, B.

    1995-04-01

    In this paper, we introduce the Minimum Weight Steiner Triangular Tiling problem, which is a generalization of the Minimum Weight Steiner Triangulation. Contrary to the conjecture of Eppstein that the Minimum Weight Steiner Triangulation of a convex polygon has the property that the Steiner points all lie on the boundary of the polygon [Epp94], we show that the Steiner points of a Minimum Weight Steiner Triangular Tiling could lie in the interior of a convex polygon.

  6. DNAzyme-Controlled Cleavage of Dimer and Trimer Origami Tiles.

    PubMed

    Wu, Na; Willner, Itamar

    2016-04-13

    Dimers of origami tiles are bridged by the Pb(2+)-dependent DNAzyme sequence and its substrate or by the histidine-dependent DNAzyme sequence and its substrate to yield the dimers T1-T2 and T3-T4, respectively. The dimers are cleaved to monomer tiles in the presence of Pb(2+)-ions or histidine as triggers. Similarly, trimers of origami tiles are constructed by bridging the tiles with the Pb(2+)-ion-dependent DNAzyme sequence and the histidine-dependent DNAzyme sequence and their substrates yielding the trimer T1-T5-T4. In the presence of Pb(2+)-ions and/or histidine as triggers, the programmed cleavage of trimer proceeds. Using Pb(2+) or histidine as trigger cleaves the trimer to yield T5-T4 and T1 or the dimer T1-T5 and T4, respectively. In the presence of Pb(2+)-ions and histidine as triggers, the cleavage products are the monomer tiles T1, T5, and T4. The different cleavage products are identified by labeling the tiles with 0, 1, or 2 streptavidin labels and AFM imaging.

  7. Programmable disorder in random DNA tilings

    NASA Astrophysics Data System (ADS)

    Tikhomirov, Grigory; Petersen, Philip; Qian, Lulu

    2016-11-01

    Scaling up the complexity and diversity of synthetic molecular structures will require strategies that exploit the inherent stochasticity of molecular systems in a controlled fashion. Here we demonstrate a framework for programming random DNA tilings and show how to control the properties of global patterns through simple, local rules. We constructed three general forms of planar network—random loops, mazes and trees—on the surface of self-assembled DNA origami arrays on the micrometre scale with nanometre resolution. Using simple molecular building blocks and robust experimental conditions, we demonstrate control of a wide range of properties of the random networks, including the branching rules, the growth directions, the proximity between adjacent networks and the size distribution. Much as combinatorial approaches for generating random one-dimensional chains of polymers have been used to revolutionize chemical synthesis and the selection of functional nucleic acids, our strategy extends these principles to random two-dimensional networks of molecules and creates new opportunities for fabricating more complex molecular devices that are organized by DNA nanostructures.

  8. Tiling solutions for optimal biological sensing

    NASA Astrophysics Data System (ADS)

    Walczak, Aleksandra M.

    2015-10-01

    Biological systems, from cells to organisms, must respond to the ever-changing environment in order to survive and function. This is not a simple task given the often random nature of the signals they receive, as well as the intrinsically stochastic, many-body and often self-organized nature of the processes that control their sensing and response and limited resources. Despite a wide range of scales and functions that can be observed in the living world, some common principles that govern the behavior of biological systems emerge. Here I review two examples of very different biological problems: information transmission in gene regulatory networks and diversity of adaptive immune receptor repertoires that protect us from pathogens. I discuss the trade-offs that physical laws impose on these systems and show that the optimal designs of both immune repertoires and gene regulatory networks display similar discrete tiling structures. These solutions rely on locally non-overlapping placements of the responding elements (genes and receptors) that, overall, cover space nearly uniformly.

  9. METHOD OF OBTAINING UNIFORM COATINGS ON GRAPHITE

    DOEpatents

    Campbell, I.E.

    1961-04-01

    A method is given for obtaining uniform carbide coatings on graphite bodies. According to the invention a metallic halide in vapor form is passed over the graphite body under such conditions of temperature and pressure that the halide reacts with the graphite to form a coating of the metal carbide on the surface of the graphite.

  10. Method of Obtaining Uniform Coatings on Graphite

    DOEpatents

    Campbell, I. E.

    1961-04-01

    A method is given for obtaining uniform carbide coatings on graphite bodies. According to the invention a metallic halide in vapor form is passed over the graphite body under such conditions of temperature and pressure that the halide reacts with the graphite to form a coating of the metal carbide on the surface of the graphite.

  11. Mineral resource of the month: graphite

    USGS Publications Warehouse

    ,

    2008-01-01

    The article presents facts about graphite ideal for industrial applications. Among the characteristics of graphite are its metallic luster, softness, perfect basal cleavage and electrical conductivity. Batteries, brake linings and powdered metals are some of the products that make use of graphite. It attributes the potential applications for graphite in high-technology fields to innovations in thermal technology and acid-leaching techniques.

  12. A comparison study between 3D T2-weighted SPACE and conventional 2D T2-weighted turbo spin echo in assessment of carotid plaque.

    PubMed

    Lv, Peng; Dai, Yuanyuan; Lin, Jiang; Zhang, Weisheng; Liu, Hao; Liu, Hui; Tang, Xiao

    2017-03-01

    The aim of this study was to compare 3D T2-weighted sampling perfection with application optimized contrast using different flip angle evolutions (T2w SPACE) with conventional 2D T2w turbo-spin echo (TSE) in plaque imaging of carotid artery. 45 patients underwent 3.0-T MRI for carotid arteries imaging. MR sequences included T2w SPACE, T2w TSE, Time of flight (TOF) and T1-weighted (T1w) TSE. The signal intensity of intra-plaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), and loose matrix (LM) were measured and their contrast ratios (CRs) against adjacent muscle were calculated. CRs from T2w SPACE and T2w TSE were compared to each other. CRs of LM, LRNC, and IPH measured on T2w SPACE were 1.74-3.04 (2.44), 0.98-1.66 (1.39), and 1.91-2.93 (2.51), respectively. CRs of LM, LRNC, and IPH on T2w TSE were 1.97-3.41 (2.44), 1.18-1.73 (1.43), and 2.26-3.75 (2.26), respectively. There was no significant difference of CR of the carotid plaques between T2w SPACE and T2w TSE (p = 0.455). Markedly significant differences of CRs were found between LM and LRNC (p < 0.001), and between LRNC and IPH (p < 0.001) on T2w SPACE and T2w TSE. T2w SPACE was comparable with conventional T2w TSE in characterization of carotid plaque.

  13. Graphitized needle cokes and natural graphites for lithium intercalation

    SciTech Connect

    Tran, T.D.; Spellman, L.M.; Pekala, R.W.; Goldberger, W.M.; Kinoshita, K.

    1996-05-10

    This paper examined effects of heat treatment and milling (before or after heat treatment) on the (electrochemical) intercalating ability of needle petroleum coke; natural graphite particles are included for comparison. 1 tab, 4 figs, 7 refs.

  14. Spent graphite fuel element processing

    SciTech Connect

    Holder, N.D.; Olsen, C.W.

    1981-07-01

    The Department of Energy currently sponsors two programs to demonstrate the processing of spent graphite fuel elements. General Atomic in San Diego operates a cold pilot plant to demonstrate the processing of both US and German high-temperature reactor fuel. Exxon Nuclear Idaho Company is demonstrating the processing of spent graphite fuel elements from Rover reactors operated for the Nuclear Rocket Propulsion Program. This work is done at Idaho National Engineering Laboratory, where a hot facility is being constructed to complete processing of the Rover fuel. This paper focuses on the graphite combustion process common to both programs.

  15. Orbiter thermal pressure drop characteristics for shuttle orbiter thermal protection system components: High density tile, low density tile, densified low density tile, and strain isolation pad

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Nystrom, D. M.

    1980-01-01

    Pressure drop tests were conducted on available samples of low and high density tile, densified low density tile, and strain isolation pads. The results are presented in terms of pressure drop, material thickness and volume flow rate. Although the test apparatus was only capable of a small part of the range of conditions to be encountered in a Shuttle Orbiter flight, the data serve to determine the type of flow characteristics to be expected for each material type tested; the measured quantities also should serve as input for initial venting and flow through analysis.

  16. A novel explicit 2D+t cyclic shape model applied to echocardiography.

    PubMed

    Casero, Ramón; Noble, J Alison

    2008-01-01

    In this paper, we propose a novel explicit 2D+t cyclic shape model that extends the Point Distribution Model (PDM) to shapes like myocardial contours with cyclic dynamics. We also propose an extension to Procrustes alignment that removes pose and subject size variability while maintaining dynamic effects. Our model draws on ideas from Principal Component Analysis (PCA), Multidimensional Scaling (MDS) and Kernel PCA (KPCA) and solves 3 shortcomings of previous implicit models: (1) cardiac cycles in the data set do not each need to have the same number of frames, (2) the required number of subjects for statistically significant results is substantially reduced and (3) the displacement of contour points incorporates time as an explicit variable. We illustrate our method by computing models of the myocardium in the 4 principal planes of 2D+t echocardiography data.

  17. Phase change material in floor tiles for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Lee, Amy Sarah

    Traditional passive solar systems have relied on sensible heat storage for energy savings. Recent research has investigated taking advantage of latent heat storage for additional energy savings. This is accomplished by the incorporation of phase change material into building materials used in traditional passive applications. Trombe walls, ceilings and floors can all be enhanced with phase change materials. This research introduces a new flooring material that incorporates a phase change material ready for commercial manufacture. An agglomerate floor tile containing 20% by mass of encapsulated octadecane has been manufactured. Flexural and compressive strength of 7.4 MPa and 24.5 MPa respectively, were measured for the tile. Peak melting transition temperature was determined to be 27.2°C with a latent heat of 33.9 J/g of tile. Structural and thermal performance of the tile surpassed that of a typical ceramic tile. Each tile was composed of quartz, resin and phase change material. Statistical modeling was performed to analyze the response of flexural and compressive strength on varying amounts of quartz, resin and phase change material. Resulting polynomials described the effect of adding phase change material into the tile. With as little as 10% by mass of phase change material, the strength was reduced to less than 50% of tile without phase change material. It was determined that the maximum phase change material content to attain structural integrity greater than ceramic tile was 20% by mass. The statistical analysis used for this research was based on mixture experiments. A procedure was developed to simplify the selection of data points used in the fit of the polynomials to describe the response of flexural and compressive strengths. Analysis of energy savings using this floor tile containing 20% by mass of phase change material was performed as an addendum to this research. A known static simulation method, SLR (solar load ratio), was adapted to include

  18. Foam on Tile Impact Modeling for the STS-107 Investigation

    NASA Technical Reports Server (NTRS)

    Stellingwerf, R. F.; Robinson, J. H.; Richardson, S.; Evans, S. W.; Stallworth, R.; Hovater, M.

    2004-01-01

    Following the breakup of the Space Shuttle Columbia during reentry a NASA/Contractor investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System elements by impact of External Tank insulating foam projectiles. The authors formed a working subgroup within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the Orbiter's tiles and of the Tank's foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working subgroups who performed tests on these items for this purpose. Two- and three-dimensional models of the tiles were constructed, including the glass outer layer, the main body of LI-900 insulation, the densified lower layer of LI-900, the Nomex felt mounting layer, and the Aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with Southwest Research Institute foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger foam projectiles on the examples of tile systems used on the Orbiter. Results for impacts on the main landing gear door are presented in this paper, including effects of impacts at several angles, and of rapidly rotating projectiles. General results suggest that foam impacts on tiles at about 500 mph could cause appreciable damage if the impact angle is greater than about 20 degrees. Some variations of the foam properties, such as increased brittleness or increased density could increase damage in some cases. Rotation up to 17 rps failed to increase the damage for the two cases considered. This does not rule out other cases

  19. Temperature derivatives for fusion reactivity of D-D and D-T

    SciTech Connect

    Langenbrunner, James R.; Makaruk, Hanna Ewa

    2016-11-29

    Deuterium-tritium (D-T) and deuterium-deuterium (D-D) fusion reaction rates are observable using leakage gamma flux. A direct measurement of γ-rays with equipment that exhibits fast temporal response could be used to infer temperature, if the detector signal is amenable for taking the logarithmic time-derivative, alpha. We consider the temperature dependence for fusion cross section reactivity.

  20. Cross Sections Calculations of ( d, t) Nuclear Reactions up to 50 MeV

    NASA Astrophysics Data System (ADS)

    Tel, E.; Yiğit, M.; Tanır, G.

    2013-04-01

    In nuclear fusion reactions two light atomic nuclei fuse together to form a heavier nucleus. Fusion power is the power generated by nuclear fusion processes. In contrast with fission power, the fusion reaction processes does not produce radioactive nuclides. The fusion will not produce CO2 or SO2. So the fusion energy will not contribute to environmental problems such as particulate pollution and excessive CO2 in the atmosphere. Fusion powered electricity generation was initially believed to be readily achievable, as fission power had been. However, the extreme requirements for continuous reactions and plasma containment led to projections being extended by several decades. In 2010, more than 60 years after the first attempts, commercial power production is still believed to be unlikely before 2050. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. In the fusion reactor, tritium self-sufficiency must be maintained for a commercial power plant. Therefore, for self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. Working out the systematics of ( d, t) nuclear reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. Since the experimental data of charged particle induced reactions are scarce, self-consistent calculation and analyses using nuclear theoretical models are very important. In this study, ( d, t) cross sections for target nuclei 19F, 50Cr, 54Fe, 58Ni, 75As, 89Y, 90Zr, 107Ag, 127I, 197Au and 238U have been investigated up to 50 MeV deuteron energy. The excitation functions for ( d, t) reactions have been calculated by pre-equilibrium reaction mechanism. Calculation results have been also compared with the available measurements in

  1. Foil deposition alpha collector probe for TFTR`s D-T phase

    SciTech Connect

    Hermann, H.W.; Darrow, D.S.; Timberlake, J.; Zweben, S.J.; Chong, G.P.; Pitcher, C.S.; Macaulay-Newcombe, R.G.

    1995-03-01

    A new foil deposition alpha collector sample probe has been developed for TFTR`s D-T phase. D-T fusion produced alpha particles escaping from the plasma are implanted in nickel foils located in a series of collimating ports on the detector. The nickel foils are removed from the tokamak after exposure to one or more plasma discharges and analyzed for helium content. This detector is intended to provide improved alpha particle energy resolution and pitch angle coverage over existing lost alpha detectors, and to provide an absolutely calibrated cross-check with these detectors. The ability to resolve between separate energy components of alpha particle loss is estimated to be {approx} 20%. A full 360{degree} of pitch angle coverage is provided for by 8 channels having an acceptance range of {approx} 53{degree} per channel. These detectors will be useful in characterizing classical and anomalous alpha losses and any collective alpha instabilities that may be excited during the D-T campaign of TFTR.

  2. Microstructural characterisation of nuclear grade graphite

    NASA Astrophysics Data System (ADS)

    Jones, A. N.; Hall, G. N.; Joyce, M.; Hodgkins, A.; Wen, K.; Marrow, T. J.; Marsden, B. J.

    2008-10-01

    Field emission and transmission electron microscopy are used to characterise the microstructure and morphology of baked carbon block and graphitized grades (from the same carbon block stock) of nuclear graphite. Quantitative analysis using Raman and energy dispersive spectroscopy (EDS) were used to investigate the decrease of crystallinity with graphitization and sample purity. Both baked carbon and graphitized nuclear graphites show no sensitivity of the Raman band shift to strain, consistent with strain accommodation by the porous structure.

  3. CALANDRIA TYPE SODIUM GRAPHITE REACTOR

    DOEpatents

    Peterson, R.M.; Mahlmeister, J.E.; Vaughn, N.E.; Sanders, W.J.; Williams, A.C.

    1964-02-11

    A sodium graphite power reactor in which the unclad graphite moderator and fuel elements are contained within a core tank is described. The core tank is submersed in sodium within the reactor vessel. Extending longitudinally through the core thnk are process tubes with fuel elements positioned therein. A bellows sealing means allows axial expansion and construction of the tubes. Within the core tank, a leakage plenum is located below the graphite, and above the graphite is a gas space. A vent line regulates the gas pressure in the space, and another line removes sodium from the plenum. The sodium coolant flows from the lower reactor vessel through the annular space between the fuel elements and process tubes and out into the reactor vessel space above the core tank. From there, the heated coolant is drawn off through an outlet line and sent to the heat exchange. (AEC)

  4. Intercalated hybrid graphite fiber composite

    NASA Technical Reports Server (NTRS)

    Gaier, James R. (Inventor)

    1993-01-01

    The invention is directed to a highly conductive lightweight hybrid material and methods of producing the same. The hybrid composite is obtained by weaving strands of a high strength carbon or graphite fiber into a fabric-like structure, depositing a layer of carbon onto the structure, heat treating the structure to graphitize the carbon layer, and intercalating the graphitic carbon layer structure. A laminate composite material useful for protection against lightning strikes comprises at least one layer of the hybrid material over at least one layer of high strength carbon or graphite fibers. The composite material of the present invention is compatible with matrix compounds, has a coefficient of thermal expansion which is the same as underlying fiber layers, and is resistant to galvanic corrosion in addition to being highly conductive. These materials are useful in the aerospace industry, in particular as lightning strike protection for airplanes.

  5. Graphite-reinforced bone cement

    NASA Technical Reports Server (NTRS)

    Knoell, A. C.

    1976-01-01

    Chopped graphite fibers added to surgical bone cement form bonding agent with mechanical properties closely matched to those of bone. Curing reaction produces less heat, resulting in reduced traumatization of body tissues. Stiffness is increased without affecting flexural strength.

  6. Graphite for the nuclear industry

    SciTech Connect

    Burchell, T.D.; Fuller, E.L.; Romanoski, G.R.; Strizak, J.P.

    1991-01-01

    Graphite finds applications in both fission and fusion reactors. Fission reactors harness the energy liberated when heavy elements, such as uranium or plutonium, fragment or fission''. Reactors of this type have existed for nearly 50 years. The first nuclear fission reactor, Chicago Pile No. 1, was constructed of graphite under a football stand at Stagg Field, University of Chicago. Fusion energy devices will produce power by utilizing the energy produced when isotopes of the element hydrogen are fused together to form helium, the same reaction that powers our sun. The role of graphite is very different in these two reactor systems. Here we summarize the function of the graphite in fission and fusion reactors, detailing the reasons for their selection and discussing some of the challenges associated with their application in nuclear fission and fusion reactors. 10 refs., 15 figs., 1 tab.

  7. Hollow clay tile wall program summary report

    SciTech Connect

    Henderson, R.C.; Jones, W.D.

    1995-07-30

    Many of the Y-12 Plant buildings, constructed during the 1940s and 1950s, consist of steel ed concrete framing infilled with hollow clay tile (HCT). The infill was intended to provide for building enclosure and was not designed to have vertical or lateral load-carrying capacity. During the late 1970s and early 1980s, seismic and wind evaluations were performed on many of these buildings in conjunction with the preparation of a site-wide safety analysis report. This analytical work, based on the best available methodology, considered lateral load-carrying capacity of the HCT infill on the basis of building code allowable shear values. In parallel with the analysis effort, DOE initiated a program to develop natural phenomena capacity and performance criteria for existing buildings, but these criteria did not specify guidelines for determining the lateral force capacity of frames infilled with HCT. The evaluation of infills was, therefore, based on the provisions for the design of unreinforced masonry as outlined in standard masonry codes. When the results of the seismic and wind evaluations were compared with the new criteria, the projected building capacities fell short of the requirements. Apparently, if the buildings were to meet the new criteria, many millions of dollars would be required for building upgrades. Because the upgrade costs were significant, the assumptions and approaches used in the analyses were reevaluated. Four issues were identified: (1) Once the infilled walls cracked, what capacity (nonlinear response), if any, would the walls have to resist earthquake or wind loads applied in the plane of the infill (in-plane)? (2) Would the infilled walls remain within the steel or reinforced concrete framing when subjected to earthquake or high wind loads applied perpendicular to the infill (out-of-plane)? (3) What was the actual shear capacity of the HCT infill? (4) Was modeling the HCT infill as a shear wall the best approach?

  8. Upgrades of Diagnostic Techniques and Technologies for JET next D-T Campaigns

    SciTech Connect

    Murari, Andrea

    2015-07-01

    JET next D-T campaign is presently scheduled for the year 2017. The main scientific objectives include the assessment of the isotopic effects on various plasma aspects: mainly on confinement, on the threshold to access the H mode and on ELM behaviour. From a technical point of view, the total yield of the entire D-T phase is expected to be 1.7 1021 neutrons, about a factor of six higher than the previous main D-T campaign on JET, DTE1. Therefore the radiation field will be quite relevant for next step devices, since the neutron flux at the first wall (∼10{sup 16} n/cm{sup 2}s), for example, will be comparable to the one in ITER behind the blanket. From a point of view of diagnostics developments, for many years JET diagnostics have been upgraded in order to provide adequate support for the scientific exploitation of a D-T campaign. The main efforts have concentrated on improving three main aspects of JET measuring capability: 1) the quality of the measurements of the electron and ion fluids to support the plasma physics programme 2) the diagnostic for the fusion products 3) diagnostic technologies for ITER. In terms of general diagnostic capability, compared to the previous DTE1, JET diagnostics have a much better spatial and temporal resolution of both the ion and electron fluid (about one order of magnitude improvement for each parameter). The consistency of the various independent measurements of the same parameters has also increased significantly; the three independent measurements of the electron temperature, for example, agree now within 5%. Moreover, solutions are being addressed to operate some cameras, both visible and IR, even during the full D-T phase to provide imaging of the plasma and the first wall. Various upgrades of neutral particle analysis are being considered, mainly to measure the isotopic composition. A new set of reflectometers is expected to provide valuable information about the changes in the turbulence with the different fuel mixtures

  9. Construction of 2D quasi-periodic Rauzy tiling by similarity transformation

    SciTech Connect

    Zhuravlev, V. G.; Maleev, A. V.

    2009-05-15

    A new approach to constructing self-similar fractal tilings is proposed based on the construction of semigroups generated by a finite set of similarity transformations. The Rauzy tiling-a 2D analog of 1D Fibonacci tiling generated by the golden mean-is used as an example to illustrate this approach. It is shown that the Rauzy torus development and the elementary fractal boundary of Rauzy tiling can be constructed in the form of a set of centers of similarity semigroups generated by two and three similarity transformations, respectively. A centrosymmetric tiling, locally dual to the Rauzy tiling, is constructed for the first time and its parameterization is developed.

  10. Effects of temperature on internal friction of Graphit-iC graphite-like carbon coatings

    NASA Astrophysics Data System (ADS)

    Zhu, Zhi-yong; Shi, Wen; Wan, Zi; Yuan, Jun-feng; Li, Xiao

    2013-12-01

    Graphit-iC graphite-like carbon coatings were deposited on SDC90 cold work die steel by using an unbalanced magnetron sputtering technology. Effects of the temperature on microstructure and internal friction of the carbon coatings were characterized by Raman spectroscopy (Raman) and a low-frequency mechanical analyzer (LMA-1) testing system. The results indicate that the internal friction of the two-side deposited carbon coatings is small (2.17×10-4), being higher than one of the substrate (1.63×10-4), and increases with temperature. However, there is an internal friction peak at 250°C accompanied with partial sp3 transferred to sp2 and increasing the intensity ratio ID/IG. There is gradual graphitization tendency of the carbon coatings as temperatures increase from 25°C to 350 °C. This would be progressive transformation from amorphous to crystalline.

  11. Microwave versus conventional sintering of silicon carbide tiles

    SciTech Connect

    Kass, M.D.; Caughman, J.B.O.; Forrester, S.C.; Akerman, A.

    1997-05-07

    Silicon carbide is being evaluated as an armor material because of its lightweight, high-hardness, and excellent armor efficiency. However, one of the problems associated with silicon carbide is the high cost associated with achieving fully dense tiles. Full density requires either hot pressing and sintering or reaction bonding. Past efforts have shown that hot pressed tiles have a higher armor efficiency than those produced by reaction bonded sintering. An earlier stuy showed that the acoustic properties of fully-dense silicon carbide tiles were enhanced through the use of post-sintered microwave heat treatments. One of the least expensive forming techniques is to isostatically press-and-sinter. In this study, the authors have used microwave energy to densify silicon carbide green bodies. Microwave sintering has been demonstrated to be a very quick way to sinter ceramics such as alumina to exceptionally high densities. Previous work has shown that microwave post treatment of fully-dense reaction bonded silicon carbide tiles significantly improves the acoustic properties of the tiles. These properties include Poisson`s ratio, Young`s modulus, shear modulus, and bulk modulus.

  12. Investigation of registration algorithms for the automatic tile processing system

    NASA Technical Reports Server (NTRS)

    Tamir, Dan E.

    1995-01-01

    The Robotic Tile Inspection System (RTPS), under development in NASA-KSC, is expected to automate the processes of post-flight re-water-proofing and the process of inspection of the Shuttle heat absorbing tiles. An important task of the robot vision sub-system is to register the 'real-world' coordinates with the coordinates of the robot model of the Shuttle tiles. The model coordinates relate to a tile data-base and pre-flight tile-images. In the registration process, current (post-flight) images are aligned with pre-flight images to detect the rotation and translation displacement required for the coordinate systems rectification. The research activities performed this summer included study and evaluation of the registration algorithm that is currently implemented by the RTPS, as well as, investigation of the utility of other registration algorithms. It has been found that the current algorithm is not robust enough. This algorithm has a success rate of less than 80% and is, therefore, not suitable for complying with the requirements of the RTPS. Modifications to the current algorithm has been developed and tested. These modifications can improve the performance of the registration algorithm in a significant way. However, this improvement is not sufficient to satisfy system requirements. A new algorithm for registration has been developed and tested. This algorithm presented very high degree of robustness with success rate of 96%.

  13. Interlaced Particle Systems and Tilings of the Aztec Diamond

    NASA Astrophysics Data System (ADS)

    Fleming, Benjamin J.; Forrester, Peter J.

    2011-02-01

    Motivated by the problem of domino tilings of the Aztec diamond, a weighted particle system is defined on N lines, with line j containing j particles. The particles are restricted to lattice points from 0 to N, and particles on successive lines are subject to an interlacing constraint. It is shown that this particle system is exactly solvable, to the extent that not only can the partition function be computed exactly, but so too can the marginal distributions. These results in turn are used to give new derivations within the particle picture of a number of known fundamental properties of the tiling problem, for example that the number of distinct configurations is 2 N( N+1)/2, and that there is a limit to the GUE minor process, which we show at the level of the joint PDFs. It is shown too that the study of tilings of the half Aztec diamond—not known from earlier literature—also leads to an interlaced particle system, now with successive lines 2 n-1 and 2 n ( n=1,…, N/2-1) having n particles. Its exact solution allows for an analysis of the half Aztec diamond tilings analogous to that given for the Aztec diamond tilings.

  14. Analysis of Thick Sandwich Shells with Embedded Ceramic Tiles

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Smith, C.; Lumban-Tobing, F.

    1996-01-01

    The Composite Armored Vehicle (CAV) is an advanced technology demonstrator of an all-composite ground combat vehicle. The CAV upper hull is made of a tough light-weight S2-glass/epoxy laminate with embedded ceramic tiles that serve as armor. The tiles are bonded to a rubber mat with a carefully selected, highly viscoelastic adhesive. The integration of armor and structure offers an efficient combination of ballistic protection and structural performance. The analysis of this anisotropic construction, with its inherent discontinuous and periodic nature, however, poses several challenges. The present paper describes a shell-based 'element-layering' technique that properly accounts for these effects and for the concentrated transverse shear flexibility in the rubber mat. One of the most important advantages of the element-layering technique over advanced higher-order elements is that it is based on conventional elements. This advantage allows the models to be portable to other structural analysis codes, a prerequisite in a program that involves the computational facilities of several manufacturers and government laboratories. The element-layering technique was implemented into an auto-layering program that automatically transforms a conventional shell model into a multi-layered model. The effects of tile layer homogenization, tile placement patterns, and tile gap size on the analysis results are described.

  15. Ferric chloride graphite intercalation compounds prepared from graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp3 electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp2 electronic structure and are electrical conductors. They contain first stage FeCl3 intercalated graphite. Some of the products contain FeCl2*2H2O, others contain FeF3 in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearing of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol %), this new GIC deintercalates without losing its molecular structure. However, when the compounds are heated to 800 C in quartz tube, they lost most of its halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber. This iron-oxide-covered fiber may be useful in making carbon-fiber/ceramic-matrix composites with strong bonding at the fiber-ceramic interface.

  16. Ferrix Chloride-Graphite Intercalation Compounds Prepared From Graphite Flouride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1995-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp(sup 3) electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp(sup 2) electronic structure and are electrical conductors. They contain first-stage FeCl3 intercalated graphite. Some of the products contain FeCl2 (center dot) 2H2O, others contain FeF3, in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearance of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol%), this new GIC deintercalates without losing its molecular structure. However, when the compounds are exposed to 800 C N2, in a quartz tube, they lost most of their halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber.

  17. Summer Thermal Performance of Ventilated Roofs with Tiled Coverings

    NASA Astrophysics Data System (ADS)

    Bortoloni, M.; Bottarelli, M.; Piva, S.

    2017-01-01

    The thermal performance of a ventilated pitched roof with tiled coverings is analysed and compared with unventilated roofs. The analysis is carried out by means of a finite element numerical code, by solving both the fluid and thermal problems in steady-state. A whole one-floor building with a pitched roof is schematized as a 2D computational domain including the air-permeability of tiled covering. Realistic data sets for wind, temperature and solar radiation are used to simulate summer conditions at different times of the day. The results demonstrate that the batten space in pitched roofs is an effective solution for reducing the solar heat gain in summer and thus for achieving better indoor comfort conditions. The efficiency of the ventilation is strictly linked to the external wind conditions and to buoyancy forces occurring due to the heating of the tiles.

  18. Flutter Analysis of the Shuttle Tile Overlay Repair Concept

    NASA Technical Reports Server (NTRS)

    Bey, Kim S.; Scott, Robert C.; Bartels, Robert E.; Waters, William A.; Chen, Roger

    2007-01-01

    The Space Shuttle tile overlay repair concept, developed at the NASA Johnson Space Center, is designed for on-orbit installation over an area of damaged tile to permit safe re-entry. The thin flexible plate is placed over the damaged area and secured to tile at discreet points around its perimeter. A series of flutter analyses were performed to determine if the onset of flutter met the required safety margins. Normal vibration modes of the panel, obtained from a simplified structural analysis of the installed concept, were combined with a series of aerodynamic analyses of increasing levels of fidelity in terms of modeling the flow physics to determine the onset of flutter. Results from these analyses indicate that it is unlikely that the overlay installed at body point 1800 will flutter during re-entry.

  19. Complex Archimedean tiling self-assembled from DNA nanostructures.

    PubMed

    Zhang, Fei; Liu, Yan; Yan, Hao

    2013-05-22

    Archimedean tilings are periodic polygonal tessellations that are created by placing regular polygons edge-to-edge around a vertex to fill the plane. Here we show that three- and four-arm DNA junction tiles with specifically designed arm lengths and intertile sticky-end interactions can be used to form sophisticated two-dimensional (2D) and three-dimensional (3D) tessellation patterns. We demonstrate two different complex Archimedean patterns, (3(3).4(2)) and (3(2).4.3.4), and the formation of 2D lattices, 3D tubes, and sealed polygon-shaped pockets from the tessellations. The successful growth of hybrid DNA tile motif arrays suggests that it maybe possible to generate 2D quasi-crystals from DNA building blocks.

  20. Solare Cell Roof Tile And Method Of Forming Same

    DOEpatents

    Hanoka, Jack I.; Real, Markus

    1999-11-16

    A solar cell roof tile includes a front support layer, a transparent encapsulant layer, a plurality of interconnected solar cells and a backskin layer. The front support layer is formed of light transmitting material and has first and second surfaces. The transparent encapsulant layer is disposed adjacent the second surface of the front support layer. The interconnected solar cells has a first surface disposed adjacent the transparent encapsulant layer. The backskin layer has a first surface disposed adjacent a second surface of the interconnected solar cells, wherein a portion of the backskin layer wraps around and contacts the first surface of the front support layer to form the border region. A portion of the border region has an extended width. The solar cell roof tile may have stand-offs disposed on the extended width border region for providing vertical spacing with respect to an adjacent solar cell roof tile.

  1. Monte Carlo estimation of the number of tatami tilings

    NASA Astrophysics Data System (ADS)

    Kimura, Kenji; Higuchi, Saburo

    2016-04-01

    Motivated by the way Japanese tatami mats are placed on the floor, we consider domino tilings with a constraint and estimate the number of such tilings of plane regions. We map the system onto a monomer-dimer model with a novel local interaction on the dual lattice. We make use of a variant of the Hamiltonian replica exchange Monte Carlo method where data for ferromagnetic and anti-ferromagnetic models are combined to make a single family of histograms. The properties of the density of states is studied beyond exact enumeration and combinatorial methods. The logarithm of the number of the tilings is linear in the boundary length of the region for all the regions studied.

  2. Spatio-temporal interpolation of soil moisture in 3D+T using automated sensor network data

    NASA Astrophysics Data System (ADS)

    Gasch, C.; Hengl, T.; Magney, T. S.; Brown, D. J.; Gräler, B.

    2014-12-01

    Soil sensor networks provide frequent in situ measurements of dynamic soil properties at fixed locations, producing data in 2- or 3-dimensions and through time (2D+T and 3D+T). Spatio-temporal interpolation of 3D+T point data produces continuous estimates that can then be used for prediction at unsampled times and locations, as input for process models, and can simply aid in visualization of properties through space and time. Regression-kriging with 3D and 2D+T data has successfully been implemented, but currently the field of geostatistics lacks an analytical framework for modeling 3D+T data. Our objective is to develop robust 3D+T models for mapping dynamic soil data that has been collected with high spatial and temporal resolution. For this analysis, we use data collected from a sensor network installed on the R.J. Cook Agronomy Farm (CAF), a 37-ha Long-Term Agro-Ecosystem Research (LTAR) site in Pullman, WA. For five years, the sensors have collected hourly measurements of soil volumetric water content at 42 locations and five depths. The CAF dataset also includes a digital elevation model and derivatives, a soil unit description map, crop rotations, electromagnetic induction surveys, daily meteorological data, and seasonal satellite imagery. The soil-water sensor data, combined with the spatial and temporal covariates, provide an ideal dataset for developing 3D+T models. The presentation will include preliminary results and address main implementation strategies.

  3. Implications of tiling for performance and design flow

    NASA Astrophysics Data System (ADS)

    Demircan, Ertugrul; Tian, Ruiqi; Grobman, Warren D.

    2002-07-01

    In this paper, we discuss rule-based and model-based tiling methodologies for interconnect layers and their implications for design flows and performance. The addition of these 'dummy' tiling metal features modifies the final physical design and reduces the variation of back-end process parameters. This is a newly developing area of design flow and its importance is increasing with each succeeding semiconductor generation. Along with this development new methodologies and tools need to be introduced to handle time placement post-physical design, as well as efficient methods for representing the resulting large amount of dat. Additionally, the inclusion of tiles may introduce performance-degrading parasitic effects. The situation is complicated by the order of the elements of the design flow: parasitics characterization requires knowledge about the placement of dummy metal times, which takes place after physical design. In this study, we co pare the advantages of having uniform interconnect characteristics to the performance degradation caused by the additional layout parasitics. We also discuss several possible scenarios for the modification of design flows to account for these effects the thereby recover timing and power targets closure. These scenarios depend for their success on the very different length scales of polish and electromagnetic effects. Finally, an analysis of correlations in the parameters that define design corners leads to the new conclusion that the negative effect of increased parasitic loading due to tiling is not as sever as a simple analysis would suggest. This result is due to the fact that the tiling parasitic loading is somewhat compensated for by the improved planarity resulting from tiling, which tightens the process variation-induced spread of metal electrical parameters.

  4. PHASE CHANGE MATERIALS IN FLOOR TILES FOR THERMAL ENERGY STORAGE

    SciTech Connect

    Douglas C. Hittle

    2002-10-01

    Passive solar systems integrated into residential structures significantly reduce heating energy consumption. Taking advantage of latent heat storage has further increased energy savings. This is accomplished by the incorporation of phase change materials into building materials used in passive applications. Trombe walls, ceilings and floors can all be enhanced with phase change materials. Increasing the thermal storage of floor tile by the addition of encapsulated paraffin wax is the proposed topic of research. Latent heat storage of a phase change material (PCM) is obtained during a change in phase. Typical materials use the latent heat released when the material changes from a liquid to a solid. Paraffin wax and salt hydrates are examples of such materials. Other PCMs that have been recently investigated undergo a phase transition from one solid form to another. During this process they will release heat. These are known as solid-state phase change materials. All have large latent heats, which makes them ideal for passive solar applications. Easy incorporation into various building materials is must for these materials. This proposal will address the advantages and disadvantages of using these materials in floor tile. Prototype tile will be made from a mixture of quartz, binder and phase change material. The thermal and structural properties of the prototype tiles will be tested fully. It is expected that with the addition of the phase change material the structural properties will be compromised to some extent. The ratio of phase change material in the tile will have to be varied to determine the best mixture to provide significant thermal storage, while maintaining structural properties that meet the industry standards for floor tile.

  5. Graphite Formation in Cast Iron

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  6. High-Performance Tiled WMS and KML Web Server

    NASA Technical Reports Server (NTRS)

    Plesea, Lucian

    2007-01-01

    This software is an Apache 2.0 module implementing a high-performance map server to support interactive map viewers and virtual planet client software. It can be used in applications that require access to very-high-resolution geolocated images, such as GIS, virtual planet applications, and flight simulators. It serves Web Map Service (WMS) requests that comply with a given request grid from an existing tile dataset. It also generates the KML super-overlay configuration files required to access the WMS image tiles.

  7. Characterization of color texture: color texture based sorting of tiles

    NASA Astrophysics Data System (ADS)

    Bourada, Y.; Lafon, Dominique; Eterradossi, O.

    1998-09-01

    Many materials used by the building industry show a color texture which affects the product commercial value. This texture can be seen as the spatial arrangement of regions of acceptable color differences. This work describes an appearance based automated sorting via color texture analysis, using ceramic tiles as example. Textural analysis of the tiles digital images expressed in CIEL*a*b* color system is performed through the analysis of intrinsic features of each region and relationships between regions. Results obtained through the automated process are compared to a visual sorting which leads to calculation of application dependant color and texture tolerances.

  8. NGNP Graphite Testing and Qualification Specimen Selection Strategy

    SciTech Connect

    Robert Bratton

    2005-05-01

    The available grades of graphite for the NGNP are reviewed. A selection matrix is presented outlining the available grades for the NGNP graphite irradiation program based upon input from potential NGNP vendors, graphite manufactures, and graphite experts.

  9. Tony Rollins fashions a new tile for the Space Shuttle orbiter

    NASA Technical Reports Server (NTRS)

    1998-01-01

    In the Tile Fabrication Shop, Tony Rollins, with United Space Alliance, holds down a curtain while making a test sample of tile on a block 5-axis computerized numerical control milling machine. About 70 percent of a Space Shuttle orbiter's external surface is shielded from heat by a network of more than 24,000 tiles formed from a silica fiber compound. They are known as High-Temperature Reusable Surface Insulation (HRSI) tiles and Low-Temperature Reusable Surface Insulation (LRSI) tiles. Most HRSI tiles are 6 inches square, but may be as large as 12 inches in some areas, and 1 to 5 inches thick. LRSI tiles are generally 8 inches square, ranging from 0.2- to 1-inch thick. More advanced materials such as Flexible Insulation Blankets have replaced tiles on some upper surfaces of the orbiter.

  10. D-T neutron generator development for cancer therapy. 1980 annual progress report

    SciTech Connect

    Bacon, F.M.; Walko, R.J.; Bickes, R.W. Jr.; Cowgill, D.F.; Riedel, A.A.; O'Hagan, J.B.

    1980-05-01

    This report summarizes the work completed during the first year of a two-year grant by NCI/HEW to investigate the feasibility of developing a D-T neutron generator for use in cancer therapy. Experiments have continued on the Target Test Facility (TTF) developed during a previous grant to investigate high-temperature metal hydrides for use as target materials. The high voltage reliability of the TTF has been improved so that 200 kV, 200 mA operation is now routine. In recent target tests, the D-D neutron production rate was measured to be > 1 x 10/sup 11//s, a rate that corresponds to a D-T neutron production rate of > 1 x 10/sup 13//s - the desired rate for use in cancer therapy. Deuterium concentration depth profiles in the target, measured during intense ion beam bombardment, show that deuterium is depleted near the surface of the target due to impurities implanted by the ion beam. Recent modifications of the duopigatron ion source to reduce secondary electron damage to the electrodes also improved the ion source efficiency by about 40%. An ultra high vacuum version of the TTF is now being constructed to determine if improved vacuum conditions will reduce ion source impurities to a sufficiently low level that the deuterium near the surface of the target is not depleted. Testing will begin in June 1980.

  11. On achieving a clinically useful D-T neutron isocentric therapy system

    SciTech Connect

    Hilton, J.L.; Hendry, G.O.

    1981-04-01

    The Cyclotron Corporation's Model 4100 Neutron Cancer Therapy System with its output of 8 x 10/sup 12/ (14 MeV) neutron/sec designed for 500 hours is made up of: a factory recyclable miniature 200 kV sealed tube which radially accelerates up to 450 mA of deuterium and tritium ions from four duoplasmatron-type ion sources onto a central target; hand changeable radiation collimators; boronated hydrogenous shielding; isocentric gantry mounting; clinical diagnostics; and controls. The self-contained gas handling system which provides the needed differential gas pressure also stores, pumps, cleans, and recycles the D-T inventory. It is composed of a reversible getter high vacuum pump, a selective noble gas sputter ion pump, and a specialized uranium trap which, by controlled thermal decomposition of uranium hydride, regulates the ion source pressure. A D-T gas inventory of 3.7 k curies provides beam-on time of about three hours, while the gas recycle requires one to two hours. The four-sided target is made up from an array of heat transfer-optimized small copper tubes and their metal surface cladding which results in relatively high neutron output and long target life. The double vacuum walls, providing redundant tritium containment, are combined with other safety features.

  12. Foam on Tile Impact Modeling for the Space Shuttle Program

    NASA Technical Reports Server (NTRS)

    Stellingwerf, R. F.; Robinson, J. H.; Richardson, S.; Evans, S. W.; Stallworth, R.; Hovater, M.

    2003-01-01

    Following the breakup of the Space Shuttle Columbia during reentry a NASA-wide investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System (TPS) elements by impact of External Tank insulating foam projectiles. Our team was to apply rigorous, physics-based analysis techniques to help determine parameters of interest for an experimental test program, utilize validated codes to investigate the full range of impact scenarios, and use analysis derived models to predict aero-thermal-structural responses to entry conditions. We were to operate on a non-interference basis with the j Team, and were to supply significant findings to that team and to the Orbiter Vehicle Engineering Working Group, being responsive to any solicitations for support from these entities. The authors formed a working sub-group within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the LI-900 TPS tiles and of the BX-250 foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working sub-groups who performed tests on these items for this purpose. Two- and three- dimensional models of the tiles were constructed, including the glass outer layer, the densified lower layer of LI-900 insulation, the Nomex felt Strain Isolation Pad (SIP) mounting layer, and the underlying aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with the Southwest Research Institute (SwRI) foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger ET foam projectiles on the TPS tile systems used

  13. Thermal Pyrolytic Graphite Enhanced Components

    NASA Technical Reports Server (NTRS)

    Hardesty, Robert E. (Inventor)

    2015-01-01

    A thermally conductive composite material, a thermal transfer device made of the material, and a method for making the material are disclosed. Apertures or depressions are formed in aluminum or aluminum alloy. Plugs are formed of thermal pyrolytic graphite. An amount of silicon sufficient for liquid interface diffusion bonding is applied, for example by vapor deposition or use of aluminum silicon alloy foil. The plugs are inserted in the apertures or depressions. Bonding energy is applied, for example by applying pressure and heat using a hot isostatic press. The thermal pyrolytic graphite, aluminum or aluminum alloy and silicon form a eutectic alloy. As a result, the plugs are bonded into the apertures or depressions. The composite material can be machined to produce finished devices such as the thermal transfer device. Thermally conductive planes of the thermal pyrolytic graphite plugs may be aligned in parallel to present a thermal conduction path.

  14. Compact D-D/D-T neutron generators and their applications

    SciTech Connect

    Lou, Tak Pui

    2003-01-01

    Neutron generators based on the 2H(d,n)3He and 3H(d,n)4He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large surface area to dissipate the heat load. This thesis describes the rationale behind the new designs and their potential applications. A survey of other neutron sources is presented to show their advantages and disadvantages compared to the fusion-based neutron generator. A prototype neutron facility was built at LBNL to test these neutron generators. High current ion beams were extracted from an RF-driven ion source to produce neutrons. With an average deuteron beam current of 24 mA and an energy of 100 keV, a neutron yield of >109 n/s has been obtained with a D-D coaxial neutron source. Several potential applications were investigated by using computer simulations. The computer code used for simulations and the variance reduction techniques employed were discussed. A study was carried out to determine the neutron flux and resolution of a D-T neutron source in thermal neutron scattering applications for condensed matter experiments. An error analysis was performed to validate the scheme used to predict the resolution. With a D-T neutron yield of 1014 n/s, the thermal neutron flux at the sample was predicted to be 7.3 x 105 n/cm2s. It was found that the resolution of cold neutrons was better than that of thermal neutrons when the duty factor is high. This neutron generator could be efficiently used for research and educational purposes at universities. Additional applications studied were positron production and

  15. Systems and methods for forming defects on graphitic materials and curing radiation-damaged graphitic materials

    DOEpatents

    Ryu, Sunmin; Brus, Louis E.; Steigerwald, Michael L.; Liu, Haitao

    2012-09-25

    Systems and methods are disclosed herein for forming defects on graphitic materials. The methods for forming defects include applying a radiation reactive material on a graphitic material, irradiating the applied radiation reactive material to produce a reactive species, and permitting the reactive species to react with the graphitic material to form defects. Additionally, disclosed are methods for removing defects on graphitic materials.

  16. 40 CFR 427.70 - Applicability; description of the asbestos floor tile subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... asbestos floor tile subcategory. 427.70 Section 427.70 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ASBESTOS MANUFACTURING POINT SOURCE CATEGORY Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor tile...

  17. 40 CFR 427.70 - Applicability; description of the asbestos floor tile subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... asbestos floor tile subcategory. 427.70 Section 427.70 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ASBESTOS MANUFACTURING POINT SOURCE CATEGORY Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor tile...

  18. Steep-Slope Assembly Testing of Clay and Concrete Tile With and Without Cool Pigmented Colors

    SciTech Connect

    Miller, William A

    2005-11-01

    Cool color pigments and sub-tile venting of clay and concrete tile roofs significantly impact the heat flow crossing the roof deck of a steep-slope roof. Field measures for the tile roofs revealed a 70% drop in the peak heat flow crossing the deck as compared to a direct-nailed asphalt shingle roof. The Tile Roofing Institute (TRI) and its affiliate members are keenly interested in documenting the magnitude of the drop for obtaining solar reflectance credits with state and federal "cool roof" building efficiency standards. Tile roofs are direct-nailed or are attached to a deck with batten or batten and counter-batten construction. S-Misson clay and concrete tile roofs, a medium-profile concrete tile roof, and a flat slate tile roof were installed on fully nstrumented attic test assemblies. Temperature measures of the roof, deck, attic, and ceiling, heat flows, solar reflectance, thermal emittance, and the ambient weather were recorded for each of the tile roofs and also on an adjacent attic cavity covered with a conventional pigmented and directnailed asphalt shingle roof. ORNL measured the tile's underside temperature and the bulk air temperature and heat flows just underneath the tile for batten and counter-batten tile systems and compared the results to the conventional asphalt shingle.

  19. GROWTH EVALUATION OF FUNGI (PENICILLIUM AND ASPERGILLUS SPP.) ON CEILING TILES

    EPA Science Inventory

    The paper gives results of an evaluation of the potential for fungal growth on four different ceiling tiles in static chambers. It was found that even new ceiling tiles supported fungal growth under favorable conditions. Used ceiling tiles appeared to be more susceptible to funga...

  20. Method of Joining Graphite Fibers to a Substrate

    NASA Technical Reports Server (NTRS)

    Beringer, Durwood M. (Inventor); Caron, Mark E. (Inventor); Taddey, Edmund P. (Inventor); Gleason, Brian P. (Inventor)

    2014-01-01

    A method of assembling a metallic-graphite structure includes forming a wetted graphite subassembly by arranging one or more layers of graphite fiber material including a plurality of graphite fibers and applying a layer of metallization material to ends of the plurality of graphite fibers. At least one metallic substrate is secured to the wetted graphite subassembly via the layer of metallization material.

  1. Graphite filament wound pressure vessels

    NASA Technical Reports Server (NTRS)

    Feldman, A.; Damico, J. J.

    1972-01-01

    Filament wound NOL rings, 4-inch and 8-inch diameter closed-end vessels involving three epoxy resin systems and three graphite fibers were tested to develop property data and fabrication technology for filament wound graphite/epoxy pressure vessels. Vessels were subjected to single-cycle burst tests at room temperature. Manufacturing parameters were established for tooling, winding, and curing that resulted in the development of a pressure/vessel performance factor (pressure x volume/weight) or more than 900,000 in. for an oblate spheroid specimen.

  2. Graphite fiber reinforced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1975-01-01

    Mechanical properties of neat resin samples and graphite fiber reinforced samples of thermoplastic resins were characterized with particular emphasis directed to the effects of environmental exposure (humidity, temperature and ultraviolet radiation). Tensile, flexural, interlaminar shear, creep and impact strengths were measured for polysulfone, polyarylsulfone and a state-of-the-art epoxy resin samples. In general, the thermoplastic resins exhibited environmental degradation resistance equal to or superior to the reference epoxy resin. Demonstration of the utility and quality of a graphite/thermoplastic resin system was accomplished by successfully thermoforming a simulated compressor blade and a fan exit guide vane.

  3. Pyrolytic graphite collector development program

    NASA Technical Reports Server (NTRS)

    Wilkins, W. J.

    1982-01-01

    Pyrolytic graphite promises to have significant advantages as a material for multistage depressed collector electrodes. Among these advantages are lighter weight, improved mechanical stiffness under shock and vibration, reduced secondary electron back-streaming for higher efficiency, and reduced outgassing at higher operating temperatures. The essential properties of pyrolytic graphite and the necessary design criteria are discussed. This includes the study of suitable electrode geometries and methods of attachment to other metal and ceramic collector components consistent with typical electrical, thermal, and mechanical requirements.

  4. Synthetic Metals from Intercalated Graphite

    DTIC Science & Technology

    1988-05-09

    Studies of the Structure of SbCl 5Graphite Inter- calation Compounds", L.E. McNeil, J. Steinbeck, L. Salamanca- Riba and G. Dresselhaus, Bull. APS 29...Graphite Intercalation Compounds", L.E. McNeil, J. Steinbeck, L. Salamanca- Riba and G. Dresselhaus, Phys. Rev. B31, 2451 (1985). 12. "Non-Ohmic Transport...Boston (1984), p. 149. 16. "High Resolution Electron Microscopy and X-Ray Diffraction Studies on SbCI5 - GIC", G. Roth, L. Salamanca- Riba , A.R. Kortan, G

  5. RECOVERY OF VALUABLE MATERIAL FROM GRAPHITE BODIES

    DOEpatents

    Fromm, L.W. Jr.

    1959-09-01

    An electrolytic process for recovering uranium from a graphite fuel element is described. The uraniumcontaining graphite body is disposed as the anode of a cell containing a nitric acid electrolyte and a 5 amp/cm/sup 2/ current passed to induce a progressive disintegration of the graphite body. The dissolved uranium is quickly and easily separated from the resulting graphite particles by simple mechanical means, such as centrifugation, filtration, and decontamination.

  6. Raman characterization of bulk ferromagnetic nanostructured graphite

    NASA Astrophysics Data System (ADS)

    Pardo, Helena; Divine Khan, Ngwashi; Faccio, Ricardo; Araújo-Moreira, F. M.; Fernández-Werner, Luciana; Makarova, Tatiana; Mombrú, Álvaro W.

    2012-08-01

    Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm-1 showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.

  7. Composition and method for brazing graphite to graphite

    DOEpatents

    Taylor, Albert J.; Dykes, Norman L.

    1984-01-01

    The present invention is directed to a brazing material for joining graphite structures that can be used at temperatures up to about 2800.degree. C. The brazing material formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600.degree. C. with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800.degree. C. so as to provide a brazed joint consisting essentially of hafnium carbide. This brazing temperature for hafnium carbide is considerably less than the eutectic temperature of hafnium carbide of about 3150.degree. C. The brazing composition also incorporates the thermosetting resin so that during the brazing operation the graphite structures may be temporarily bonded together by thermosetting the resin so that machining of the structures to final dimensions may be completed prior to the completion of the brazing operation. The resulting brazed joint is chemically and thermally compatible with the graphite structures joined thereby and also provides a joint of sufficient integrity so as to at least correspond with the strength and other properties of the graphite.

  8. Task 4 supporting technology. Part 1: Detailed test plan for leading edge tile development. Leading edge material development and testing

    NASA Technical Reports Server (NTRS)

    Hogenson, P. A.; Staszak, Paul; Hinkle, Karrie

    1995-01-01

    This task develops two alternative candidate tile materials for leading edge applications: coated alumina enhanced thermal barrier (AETB) tile and silicone impregnated reusable ceramic ablator (SIRCA) tile. Upon reentry of the X-33/RLV space vehicle, the leading edges experience the highest heating rates and temperatures. The wing leading edge and nose cap experience peak temperatures in the range 2000 to 2700 F. Replacing reinforced carbon-carbon (RCC) with tile-based thermal protection system (TPS) materials is the primary objective. Weight, complexity, coating impact damage, and repairability are among the problems that this tile technology development addresses. The following subtasks will be performed in this development effort: tile coating development; SIRCA tile development; robustness testing of tiles; tile repair development; tile operations/processing; tile leading edge configuration; and life cycle testing.

  9. On the Challenge of Keeping ATLAS Tile Calorimeter Raw Data

    NASA Astrophysics Data System (ADS)

    Tsiskaridze, V. K.

    2012-08-01

    The Tile Calorimeter (TileCal) for the ATLAS experiment at the CERN Large Hadron Collider (LHC) is currently taking data with proton-proton collisions. The TileCal read-out system was initially designed to reconstruct the data in real-time and to store for each channel the signal amplitude, time and quality factor at the required high rate. This approach implied discarding 80% of the raw data that correspond to noise or small signals. Practical experience operating in this scheme with increasing rate have led to several modifications and understanding that some kind of data compression is helpful during data processing and storing. An alternate approach is to use online reconstruction for Level 2 triggering only and to implement a data flow lossless compression scheme for further offiine analysis. A new version of the lossless compression algorithm is proposed which allows to both save the complete raw data and to feed the trigger with the reconstructed signal amplitude and time. It does not increase the data flow as compared to the existing approach and the size of the data fragments transmitted is more stable. We will describe the lossless compression algorithm as a possible upgrade of the Tile data acquisition and highlight some details of the implementation. We will report on its testing and validation and on the overall performance measured on high rate tests, calibration and √ {s} = 7 TeV proton-proton collisions runs.

  10. Drainage water management effects on tile dicharge and water quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drainage water management (DWM) has received considerable attention as a potential best management practice for improving water quality in tile drained landscapes. However, only a limited number of studies have documented the effectiveness of DWM in mitigating nitrogen (N) and phosphorus (P) loads. ...

  11. Contributions of systematic tile drainage to watershed scale phosphorus transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus (P) transport from agricultural fields continues be a focal point for addressing harmful algal blooms (HABs) and nuisance algae in freshwater systems throughout the world. In humid, poorly drained regions, attention has turned to P delivery through subsurface tile drainage. Research on th...

  12. EVALUATION OF FUNGAL GROWTH (PENICILLIUM GLABRUM) ON A CEILING TILE

    EPA Science Inventory

    The paper gives results of a study employing static chambers to study the impact of different equilibrium relative humidities (RHs) and moisture conditions on the ability of a new ceiling tile to support fungal growth. Amplification of the mold, Penicillium glabrum, occurred at R...

  13. Phosphorus modeling in tile drained agricultural systems using APEX

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus losses through tile drained systems in agricultural landscapes may be causing the persistent eutrophication problems observed in surface water. The purpose of this paper is to evaluate the state of the science in the Agricultural Policy/Environmental eXtender (APEX) model related to surf...

  14. Nutrient export in tile drainage: Comparing manure injection to fertigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Subsurface tile drainage of agricultural land is implicated as a major source of nutrients to the Mississippi River. To protect water quality, land application of manure should maximize crop nutrient use and minimize nutrient loss. Weather constraints and regulations restrict the period during which...

  15. Tiled architecture of a CNN-mostly IP system

    NASA Astrophysics Data System (ADS)

    Spaanenburg, Lambert; Malki, Suleyman

    2009-05-01

    Multi-core architectures have been popularized with the advent of the IBM CELL. On a finer grain the problems in scheduling multi-cores have already existed in the tiled architectures, such as the EPIC and Da Vinci. It is not easy to evaluate the performance of a schedule on such architecture as historical data are not available. One solution is to compile algorithms for which an optimal schedule is known by analysis. A typical example is an algorithm that is already defined in terms of many collaborating simple nodes, such as a Cellular Neural Network (CNN). A simple node with a local register stack together with a 'rotating wheel' internal communication mechanism has been proposed. Though the basic CNN allows for a tiled implementation of a tiled algorithm on a tiled structure, a practical CNN system will have to disturb this regularity by the additional need for arithmetical and logical operations. Arithmetic operations are needed for instance to accommodate for low-level image processing, while logical operations are needed to fork and merge different data streams without use of the external memory. It is found that the 'rotating wheel' internal communication mechanism still handles such mechanisms without the need for global control. Overall the CNN system provides for a practical network size as implemented on a FPGA, can be easily used as embedded IP and provides a clear benchmark for a multi-core compiler.

  16. A design rationale for NASA TileWorld

    NASA Technical Reports Server (NTRS)

    Philips, Andrew B.; Swanson, Keith J.; Drummond, Mark E.; Bresina, John L.

    1991-01-01

    Automated systems that can operate in unrestricted real-world domains are still well beyond current computational capabilities. This paper argues that isolating essential problem characteristics found in real-world domains allows for a careful study of how particular control systems operate. By isolating essential problem characteristics and studying their impact on autonomous system performance, we should be able to more quickly deliver systems for practical real-world problems. For our research on planning, scheduling, and control, we have selected three particular domain attributes to study: exogenous events, uncertain action outcome, and metric time. We are not suggesting that studies of these attributes in isolation are sufficient to guarantee the obvious goals of good methodology, brilliant architectures, or first-class results; however, we are suggesting that such isolation facilitates the achievement of these goals. To study these attributes, we have developed the NASA TileWorld. We describe the NASA TileWorld simulator in general terms, present an example NASA TileWorld problem, and discuss some of our motivations and concerns for NASA TileWorld.

  17. High speed hydrogen/graphite interaction

    NASA Technical Reports Server (NTRS)

    Kelly, A. J.; Hamman, R.; Sharma, O. P.; Harrje, D. T.

    1974-01-01

    Various aspects of a research program on high speed hydrogen/graphite interaction are presented. Major areas discussed are: (1) theoretical predictions of hydrogen/graphite erosion rates; (2) high temperature, nonequilibrium hydrogen flow in a nozzle; and (3) molecular beam studies of hydrogen/graphite erosion.

  18. Separation medium containing thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

    2012-01-01

    A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

  19. CMB-13 research on carbon and graphite

    NASA Technical Reports Server (NTRS)

    Smith, M. C.

    1972-01-01

    The research on graphite and carbon for this period is reported. Topics discussed include: effects of grinding on the Santa Marie graphites, properties and purities of coal-tar, resin-bonded graphite, carbonization of resin components, and glass-like carbon filler.

  20. Graphitization behaviour of chemically derived graphene sheets.

    PubMed

    Long, Donghui; Li, Wei; Qiao, Wenming; Miyawaki, Jin; Yoon, Seong-Ho; Mochida, Isao; Ling, Licheng

    2011-09-01

    Graphene sheets were prepared via chemical reduction of graphite oxides and then graphitized at 2800 °C. The structure changes from pristine graphite to graphitized graphene sheets were monitored using X-ray diffraction and Raman spectroscopy. It was found that the graphitized graphene sheets exhibited relatively low degree of graphitization and high level of structural defects. XPS spectra revealed that oxygen functionalities could be completely eliminated after graphitization. Morphology observations indicated that graphitization could induce the coalescence and connection of the crumpled graphene agglomerations into compressed grains. The connections included the joint of graphitic sheets along the c-axis with van der Waals force between graphitic sheets and the joint of sheets in the in-plane with covalent bond between carbon atoms. New structures such as the formation of loop at the tip of graphene sheets and the formation of 3D concentric graphene nanoparticles occurred in the graphitized graphene sheets, as a result of self-organization to achieve their lowest potential energy. Our findings should provide some experimental implications for understanding of graphitization behaviour and thermal stability of strictly 2D graphene monolayers.

  1. Garuda: a scalable tiled display wall using commodity PCs.

    PubMed

    Nirnimesh; Harish, Pawan; Narayanan, P J

    2007-01-01

    Cluster-based tiled display walls can provide cost-effective and scalable displays with high resolution and a large display area. The software to drive them needs to scale too if arbitrarily large displays are to be built. Chromium is a popular software API used to construct such displays. Chromium transparently renders any OpenGL application to a tiled display by partitioning and sending individual OpenGL primitives to each client per frame. Visualization applications often deal with massive geometric data with millions of primitives. Transmitting them every frame results in huge network requirements that adversely affect the scalability of the system. In this paper, we present Garuda, a client-server-based display wall framework that uses off-the-shelf hardware and a standard network. Garuda is scalable to large tile configurations and massive environments. It can transparently render any application built using the Open Scene Graph (OSG) API to a tiled display without any modification by the user. The Garuda server uses an object-based scene structure represented using a scene graph. The server determines the objects visible to each display tile using a novel adaptive algorithm that culls the scene graph to a hierarchy of frustums. Required parts of the scene graph are transmitted to the clients, which cache them to exploit the interframe redundancy. A multicast-based protocol is used to transmit the geometry to exploit the spatial redundancy present in tiled display systems. A geometry push philosophy from the server helps keep the clients in sync with one another. Neither the server nor a client needs to render the entire scene, making the system suitable for interactive rendering of massive models. Transparent rendering is achieved by intercepting the cull, draw, and swap functions of OSG and replacing them with our own. We demonstrate the performance and scalability of the Garuda system for different configurations of display wall. We also show that the

  2. Designing mid-wave infrared (MWIR) thermo-optic coefficient (dn/dT) in chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Gleason, Benn; Sisken, Laura; Smith, Charmayne; Richardson, Kathleen

    2016-05-01

    Seventeen infrared-transmitting GeAsSe chalcogenide glasses were fabricated to determine the role of chemistry and structure on mid-wave infrared (MWIR) optical properties. The refractive index and thermoptic coefficients of samples were measured at λ = 4.515 μm using an IR-modified Metricon prism coupler, located at University of Central Florida. Thermo-optic coefficient (dn/dT) values were shown to range from approximately -40 ppm/°C to +65 ppm/°C, and refractive index was shown to vary between approximately 2.5000 and 2.8000. Trends in refractive index and dn/dT were found to be related to the atomic structures present within the glassy network, as opposed to the atomic percentage of any individual constituent. A linear correlation was found between the quantity (n-3•dn/dT) and the coefficient of thermal expansion (CTE) of the glass, suggesting the ability to compositionally design chalcogenide glass compositions with zero dn/dT, regardless of refractive index or dispersion performance. The tunability of these novel glasses offer increased thermal and mechanical stability as compared to the current commercial zero dn/dT options such as AMTIR-5 from Amorphous Materials Inc. For IR imaging systems designed to achieve passive athermalization, utilizing chalcogenide glasses with their tunable ranges of dn/dT (including zero) can be key to addressing system size, weight, and power (SWaP) limitations.

  3. BNCT of skin tumors using the high-energy D-T neutrons.

    PubMed

    Masoudi, S Farhad; Rasouli, Fatemeh S; Ghasemi, Marjan

    2017-04-01

    Owing to the continuing need for providing improved and universally accepted facilities to be used in radiation therapies, a number of recently published BNCT-related studies have focused on investigating appropriate neutron sources as alternatives for nuclear reactors. Of special interest are D-T neutron generators, which theoretically have shown the potential to be utilized as neutron sources for BNCT of deep-seated tumors. This work is devoted to investigate the feasibility of using the high-energy neutrons emitted from these generators for treatment of surface tumors, especially skin. Using a set of MCNPX simulations, the D-T neutrons are passed through an optimized arrangement of materials to slow-down toward the desired energy range, and to remove the neutron and gamma contamination considering the IAEA recommended criteria, especially determined for pre-clinical survey for treatment of surface tumors. By assessment with these parameters, it is shown that the designed beam, corresponding to a configuration composed of natural uranium as neutron multiplier, D2O as moderator, Pb as reflector, Bi as gamma filter, and polyethylene and BeO as collimators provides high-intensity of desired neutrons, and low-background doses as well. It was found that an appropriate material for collimator, if accompanied with an optimized geometry, is an important parameter for keeping the undesired components to the recommended level. A typical simulated phantom, subjected to the irradiation of the designed spectrum, is used to study the performance of the resultant beam in shallow tissue. For an arbitrary chosen (10)B concentration, the evaluated depth-dose curves show that the proposed configuration establishes acceptable agreement between the appropriate neutron intensity and penetration to desired depth in tissue in a reasonable treatment time of about 25-38min. Considering the simulations carried out, the total dose delivered to the tumor is expected to be of about 4.2 times

  4. Electrochemical identification of metal ions in archaeological ceramic glazes by stripping voltammetry at graphite/polyester composite electrodes.

    PubMed

    Doménech-Carbó, A; Doménech-Carbó, M T; Osete-Cortina, L; Gimeno-Adelantado, J V; Bosch-Reig, F; Mateo-Castro, R

    2002-01-04

    The electrochemical response of metal ions in different samples of coloured ceramic tin-lead glazes attached to graphite/polyester composite electrodes is described. In addition to the ubiquous signals for lead, reductive dissolution processes are followed by anodic stripping peaks for Co, Cu, Sb, Mn, Sn and Fe, enabling the direct identification of such elements in microsamples proceeding from archaeological glazed tiles from Valencia (Spain) workshops (16th-18th century). Additional anodic and cathodic peaks corresponding to redox processes involving metal species in solution generated during stripping processes are also used. Peak potentials, Tafel plots and shape parameters are used for characterising the different species.

  5. Fabrication of Reticulated Graphitic Foam.

    DTIC Science & Technology

    2007-11-02

    mesophase pitch (MP). Mesophase pitch is...goes through several heat treatments to stabilize the mesophase pitch , burn out the polyurethane, carbonize and finally graphitize the foam, all the while maintaining the same morphology as the initial polyurethane foam....struts gives some initial molecular orientation. The dipped foam is dried, leaving behind a the polyurethane foam coated with the pitch . The foam

  6. Graphite oral tattoo: case report.

    PubMed

    Moraes, Renata Mendonça; Gouvêa Lima, Gabriela de Morais; Guilhermino, Marinaldo; Vieira, Mayana Soares; Carvalho, Yasmin Rodarte; Anbinder, Ana Lia

    2015-10-16

    Pigmented oral lesions compose a large number of pathological entities, including exogenous pigmentat oral tattoos, such as amalgam and graphite tattoos. We report a rare case of a graphite tattoo on the palate of a 62-year-old patient with a history of pencil injury, compare it with amalgam tattoos, and determine the prevalence of oral tattoos in our Oral Pathology Service. We also compare the clinical and histological findings of grafite and amalgam tattoos. Oral tattoos affect women more frequently in the region of the alveolar ridge. Graphite tattoos occur in younger patients when compared with the amalgam type. Histologically, amalgam lesions represent impregnation of the reticular fibers of vessels and nerves with silver, whereas in cases of graphite tattoos, this impregnation is not observed, but it is common to observe a granulomatous inflammatory response, less evident in cases of amalgam tattoos. Both types of lesions require no treatment, but in some cases a biopsy may be done to rule out melanocytic lesions.

  7. Igneous Graphite in Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Igneous graphite. a rare constituent in terrestrial mafic and ultramafic rocks. occurs in three EH and one EL enstatite chondrite impact-melt breccias as 2-150 Ilm long euhedrallaths. some with pyramidal terminations. In contrast. graphite in most enstatite chondrites exsolved from metallic Fe-Ni as polygonal. rounded or irregular aggregates. Literature data for five EH chondrites on C combusting at high temperatures show that Abee contains the most homogeneous C isotopes (i.e. delta(sup 13)C = -8.1+/-2.1%); in addition. Abee's mean delta(sup l3)C value is the same as the average high-temperature C value for the set of five EH chondrites. This suggests that Abee scavenged C from a plurality of sources on its parent body and homogenized the C during a large-scale melting event. Whereas igneous graphite in terrestrial rocks typically forms at relatively high pressure and only moderately low oxygen fugacity (e.g., approx. 5 kbar. logfO2, approx. -10 at 1200 C ). igneous graphite in asteroidal meteorites formed at much lower pressures and oxygen fugacities.

  8. Calorimetric and ionimetric dosimetry intercomparisons II: d + T neutron source at the Antoni Van Leeuwenhoek hospital.

    PubMed

    McDonald, J C; Ma, I C; Mijhnheer, B J; Zoetelief, H

    1981-01-01

    A series of dosimetric measurements was carried out at the Antoni van Leeuwenhoek Hospital, Amsterdam, using a Philips d + T generator, which produced neutrons with energies of approximately 14 MeV. A-150 plastic ionization chambers, an A-150 plastic calorimeter, and a GM dosimeter were used to determine total absorbed dose and the photon absorbed dose fraction. The ion chambers were calibrated in a 60Co gamma-ray field in air and compared in a phantom placed in the 60Co gamma-ray beam. Comparison of the total absorbed dose derived from the ionization chamber measurements to that determined using the calorimeter indicated agreement for the neutron measurements between the techniques to within +/- 2%.

  9. A novel design of beam shaping assembly to use D-T neutron generator for BNCT.

    PubMed

    Kasesaz, Yaser; Karimi, Marjan

    2016-12-01

    In order to use 14.1MeV neutrons produced by d-T neutron generators, two special and novel Beam Shaping Assemblies (BSA), including multi-layer and hexagonal lattice have been suggested and the effect of them has been investigated by MCNP4C Monte Carlo code. The results show that the proposed BSA can provide the qualified epithermal neutron beam for BNCT. The final epithermal neutron flux is about 6e9 n/cm2.s. The final proposed BSA has some different advantages: 1) it consists of usual and well-known materials (Pb, Al, Fluental and Cd); 2) it has a simple geometry; 3) it does not need any additional gamma filter; 4) it can provide high flux of epithermal neutrons. As this type of neutron source is under development in the world, it seems that they can be used clinically in a hospital considering the proposed BSA.

  10. Substructure procedure for including tile flexibility in stress analysis of shuttle thermal protection system

    NASA Technical Reports Server (NTRS)

    Giles, G. L.

    1980-01-01

    A substructure procedure to include the flexibility of the tile in the stress analysis of the shuttle thermal protection system (TPS) is described. In this procedure, the TPS is divided into substructures of (1) the tile which is modeled by linear finite elements and (2) the SIP which is modeled as a nonlinear continuum. This procedure was applied for loading cases of uniform pressure, uniform moment, and an aerodynamic shock on various tile thicknesses. The ratios of through-the-thickness stresses in the SIP which were calculated using a flexible tile compared to using a rigid tile were found to be less than 1.05 for the cases considered.

  11. Modelling the graphite fracture mechanisms

    SciTech Connect

    Jacquemoud, C.; Marie, S.; Nedelec, M.

    2012-07-01

    In order to define a design criterion for graphite components, it is important to identify the physical phenomena responsible for the graphite fracture, to include them in a more effective modelling. In a first step, a large panel of experiments have been realised in order to build up an important database; results of tensile tests, 3 and 4 point bending tests on smooth and notched specimens have been analysed and have demonstrated an important geometry related effects on the behavior up to fracture. Then, first simulations with an elastic or an elastoplastic bilinear constitutive law have not made it possible to simulate the experimental fracture stress variations with the specimen geometry, the fracture mechanisms of the graphite being at the microstructural scale. That is the reason why a specific F.E. model of the graphite structure has been developed in which every graphite grain has been meshed independently, the crack initiation along the basal plane of the particles as well as the crack propagation and coalescence have been modelled too. This specific model has been used to test two different approaches for fracture initiation: a critical stress criterion and two criteria of fracture mechanic type. They are all based on crystallographic considerations as a global critical stress criterion gave unsatisfactory results. The criteria of fracture mechanic type being extremely unstable and unable to represent the graphite global behaviour up to the final collapse, the critical stress criterion has been preferred to predict the results of the large range of available experiments, on both smooth and notched specimens. In so doing, the experimental observations have been correctly simulated: the geometry related effects on the experimental fracture stress dispersion, the specimen volume effects on the macroscopic fracture stress and the crack propagation at a constant stress intensity factor. In addition, the parameters of the criterion have been related to

  12. Evaluation of the Hooghoudt and Kirkham tile drain equations in SWAT to simulate tile flow and nitrate-nitrogen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Subsurface tile drains in agricultural systems of Midwest U.S. are a major contributor of nitrate-N (NO3-N) loadings to hypoxic conditions in the Gulf of Mexico. Existing soil moisture retention parameter computation algorithm in the widely used Soil and Water Assessment Tool (SWAT) model is known t...

  13. A D-D/D-T fusion reaction based neutron generator system for liver tumor BNCT

    SciTech Connect

    Koivunoro, H.; Lou, T.P.; Leung, K. N.; Reijonen, J.

    2003-04-02

    Boron-neutron capture therapy (BNCT) is an experimental radiation treatment modality used for highly malignant tumor treatments. Prior to irradiation with low energetic neutrons, a 10B compound is located selectively in the tumor cells. The effect of the treatment is based on the high LET radiation released in the {sup 10}B(n,{alpha}){sup 7}Li reaction with thermal neutrons. BNCT has been used experimentally for brain tumor and melanoma treatments. Lately applications of other severe tumor type treatments have been introduced. Results have shown that liver tumors can also be treated by BNCT. At Lawrence Berkeley National Laboratory, various compact neutron generators based on D-D or D-T fusion reactions are being developed. The earlier theoretical studies of the D-D or D-T fusion reaction based neutron generators have shown that the optimal moderator and reflector configuration for brain tumor BNCT can be created. In this work, the applicability of 2.5 MeV neutrons for liver tumor BNCT application was studied. The optimal neutron energy for external liver treatments is not known. Neutron beams of different energies (1eV < E < 100 keV) were simulated and the dose distribution in the liver was calculated with the MCNP simulation code. In order to obtain the optimal neutron energy spectrum with the D-D neutrons, various moderator designs were performed using MCNP simulations. In this article the neutron spectrum and the optimized beam shaping assembly for liver tumor treatments is presented.

  14. Digital holography particle image velocimetry for the measurement of 3D t-3c flows

    NASA Astrophysics Data System (ADS)

    Shen, Gongxin; Wei, Runjie

    2005-10-01

    In this paper a digital in-line holographic recording and reconstruction system was set up and used in the particle image velocimetry for the 3D t-3c (the three-component (3c), velocity vector field measurements in a three-dimensional (3D), space field with time history ( t)) flow measurements that made up of the new full-flow field experimental technique—digital holographic particle image velocimetry (DHPIV). The traditional holographic film was replaced by a CCD chip that records instantaneously the interference fringes directly without the darkroom processing, and the virtual image slices in different positions were reconstructed by computation using Fresnel-Kirchhoff integral method from the digital holographic image. Also a complex field signal filter (analyzing image calculated by its intensity and phase from real and image parts in fast fourier transform (FFT)) was applied in image reconstruction to achieve the thin focus depth of image field that has a strong effect with the vertical velocity component resolution. Using the frame-straddle CCD device techniques, the 3c velocity vector was computed by 3D cross-correlation through space interrogation block matching through the reconstructed image slices with the digital complex field signal filter. Then the 3D-3c-velocity field (about 20 000 vectors), 3D-streamline and 3D-vorticiry fields, and the time evolution movies (30 field/s) for the 3D t-3c flows were displayed by the experimental measurement using this DHPIV method and techniques.

  15. Graphite nanoreinforcements in polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Fukushima, Hiroyuki

    Nanocomposites composed of polymer matrices with clay reinforcements of less than 100 nm in size, are being considered for applications such as interior and exterior accessories for automobiles, structural components for portable electronic devices, and films for food packaging. While most nanocomposite research has focused on exfoliated clay platelets, the same nanoreinforcement concept can be applied to another layered material, graphite, to produce nanoplatelets and nanocomposites. Graphite is the stiffest material found in nature (Young's Modulus = 1060 GPa), having a modulus several times that of clay, but also with excellent electrical and thermal conductivity. The key to utilizing graphite as a platelet nanoreinforcement is in the ability to exfoliate this material. Also, if the appropriate surface treatment can be found for graphite, its exfoliation and dispersion in a polymer matrix will result in a composite with not only excellent mechanical properties but electrical properties as well, opening up many new structural applications as well as non-structural ones where electromagnetic shielding and high thermal conductivity are requirements. In this research, a new process to fabricate exfoliated nano-scale graphite platelets was established (Patent pending). The size of the resulted graphite platelets was less than 1 um in diameter and 10 nm in thickness, and the surface area of the material was around 100 m2/g. The reduction of size showed positive effect on mechanical properties of composites because of the increased edge area and more functional groups attached with it. Also various surface treatment techniques were applied to the graphite nanoplatelets to improve the surface condition. As a result, acrylamide grafting treatment was found to enhance the dispersion and adhesion of graphite flakes in epoxy matrices. The resulted composites showed better mechanical properties than those with commercially available carbon fibers, vapor grown carbon fibers

  16. Catalytic properties of lamellar compounds of graphite

    NASA Astrophysics Data System (ADS)

    Novikov, Yu. N.; Vol'pin, M. E.

    1981-05-01

    In heterogenous catalysis, the supports derived from graphite and carbon-graphite materials constitute a unique and exceptionally attractive group. The lamellar compounds of graphite with various kinds of electron acceptors and donors show catalytic activities on the following reactions: the oxidation of organic compounds with molecular oxygen, many sorts of polymerization, alcohol and formic acid dehydrogenation, hydrogenation and isomerization of olefins and acetylenes, ammonia synthesis from nitrogen and hydrogen, and also CO hydrogenation. Furthermore, the transition metal lamellar compounds of graphite are highly active catalysts in the process of the graphite-to-diamond conversion.

  17. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.

    1977-01-01

    The results of research for the origination of graphite-fiber reinforced glass matrix composites are presented. The method selected to form the composites consisted of pulling the graphite fiber through a slurry containing powdered glass, winding up the graphite fiber and the glass it picks up on a drum, drying, cutting into segments, loading the tape segment into a graphite die, and hot pressing. During the course of the work, composites were made with a variety of graphite fibers in a glass matrix.

  18. On the superconductivity of graphite interfaces

    NASA Astrophysics Data System (ADS)

    Esquinazi, P.; Heikkilä, T. T.; Lysogorskiy, Y. V.; Tayurskii, D. A.; Volovik, G. E.

    2014-11-01

    We propose an explanation for the appearance of superconductivity at the interfaces of graphite with Bernal stacking order. A network of line defects with flat bands appears at the interfaces between two slightly twisted graphite structures. Due to the flat band the probability to find high temperature superconductivity at these quasi one-dimensional corridors is strongly enhanced. When the network of superconducting lines is dense it becomes effectively two-dimensional. The model provides an explanation for several reports on the observation of superconductivity up to room temperature in different oriented graphite samples, graphite powders as well as graphite-composite samples published in the past.

  19. Optimized Conditioning of Activated Reactor Graphite

    SciTech Connect

    Tress, G.; Doehring, L.; Pauli, H.; Beer, H.-F.

    2002-02-25

    The research reactor DIORIT at the Paul Scherrer Institute was decommissioned in 1993 and is now being dismantled. One of the materials to be conditioned is activated reactor graphite, approximately 45 tons. A cost effective conditioning method has been developed. The graphite is crushed to less than 6 mm and added to concrete and grout. This graphite concrete is used as matrix for embedding dismantling waste in containers. The waste containers that would have been needed for separate conditioning and disposal of activated reactor graphite are thus saved. Applying the new method, the cost can be reduced from about 55 SFr/kg to about 17 SFr/kg graphite.

  20. Are Design and Technology Teachers Able to Meet the Challenges Inherent in the Theme for This Conference "D&T--A Platform for Success"?

    ERIC Educational Resources Information Center

    Atkinson, E. Stephanie

    2009-01-01

    This paper has emerged out of the author's life-long passion for Design and Technology (D&T), which she will refer to as D&T from now on, her on-going research which has informed her practice as a teacher of D&T in England over the past 45 years, and in particular her practice as a trainer of D&T teachers for the past 20 years. In…

  1. Erosion and deposition on JET divertor and limiter tiles during the experimental campaigns 2005-2009

    NASA Astrophysics Data System (ADS)

    Krat, S.; Coad, J. P.; Gasparyan, Yu.; Hakola, A.; Likonen, J.; Mayer, M.; Pisarev, A.; Widdowson, A.; JET-EFDA contributors

    2013-07-01

    Erosion from and deposition on JET divertor tiles used during the 2007-2009 campaign and on inner wall guard limiter (IWGL) tiles used during 2005-2009 are studied. The tungsten coating on the divertor tiles was mostly intact with the largest erosion ˜30% in a small local area. Locally high erosion areas were observed on the load bearing divertor tile 5 and on the horizontal surface of the divertor tile 8. The IWGL tiles show a complicated distribution of erosion and deposition areas. The total amount of carbon deposited on the all IWGL tiles during the campaign 2005-2009 is estimated to be 65 g. The density of carbon deposits is estimated to be 0.67-0.83 g/cm3.

  2. AGC-2 Graphite Preirradiation Data Package

    SciTech Connect

    David Swank; Joseph Lord; David Rohrbaugh; William Windes

    2012-10-01

    The NGNP Graphite R&D program is currently establishing the safe operating envelope of graphite core components for a Very High Temperature Reactor (VHTR) design. The program is generating quantitative data necessary for predicting the behavior and operating performance of the new nuclear graphite grades. To determine the in-service behavior of the graphite for pebble bed and prismatic designs, the Advanced Graphite Creep (AGC) experiment is underway. This experiment is examining the properties and behavior of nuclear grade graphite over a large spectrum of temperatures, neutron fluences and compressive loads. Each experiment consists of over 400 graphite specimens that are characterized prior to irradiation and following irradiation. Six experiments are planned with the first, AGC-1, currently being irradiated in the Advanced Test Reactor (ATR) and pre-irradiation characterization of the second, AGC-2, completed. This data package establishes the readiness of 512 specimens for assembly into the AGC-2 capsule.

  3. Composition and method for brazing graphite to graphite

    DOEpatents

    Taylor, A.J.; Dykes, N.L.

    1982-08-10

    A brazing material is described for joining graphite structures that can be used up to 2800/sup 0/C. The brazing material is formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600/sup 0/C with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800/sup 0/C so as to provide a brazed joint consisting essentially of hafnium carbide. The resulting brazed joint is chemically and thermally compatible with the graphite structures.

  4. Evidence of graphitic AB stacking order of graphite oxides.

    PubMed

    Jeong, Hae-Kyung; Lee, Yun Pyo; Lahaye, Rob J W E; Park, Min-Ho; An, Kay Hyeok; Kim, Ick Jun; Yang, Cheol-Woong; Park, Chong Yun; Ruoff, Rodney S; Lee, Young Hee

    2008-01-30

    Graphite oxide (GO) samples were prepared by a simplified Brodie method. Hydroxyl, epoxide, carboxyl, and some alkyl functional groups are present in the GO, as identified by solid-state 13C NMR, Fourier-transform infrared spectroscopy, and X-ray photoemission spectroscopy. Starting with pyrolytic graphite (interlayer separation 3.36 A), the average interlayer distance after 1 h of reaction, as determined by X-ray diffraction, increased to 5.62 A and then increased with further oxidation to 7.37 A after 24 h. A smaller signal in 13C CPMAS NMR compared to that in 13C NMR suggests that carboxyl and alkyl groups are at the edges of the flakes of graphite oxide. Other aspects of the chemical bonding were assessed from the NMR and XPS data and are discussed. AB stacking of the layers in the GO was inferred from an electron diffraction study. The elemental composition of GO prepared using this simplified Brodie method is further discussed.

  5. Mortar characterization study of unreinforced hollow clay tile masonry

    SciTech Connect

    Butala, M.B.

    1992-09-14

    This report presents the results of an investigation of mortar removed from existing hollow clay tile masonry walls in buildings located at the Oak Ridge Y-12 Plant. Primary purpose of this investigation was to evaluate the properties of existing mortar and provide a similar specification for the mortar to be used in construction of test specimens and test walls for the Hollow Clay Tile Wall Test Program. A mortar characterization study of mortar samples removed from walls in four buildings, 9207, 9206, 9204-2 and 9212 was performed by Testwell Craig Materials Consultants (TCMC) under subcontract to Martin Marietta Energy Systems, Inc (MMES). The mortar samples were collected by MMES and analyzed by TCMC in accordance with applicable ASTM standards. Petrographical and chemical analyses were performed. From the results of this investigation a mortar mix was prepared to resemble the properties of existing mortar.

  6. Calibration and monitoring systems of the ATLAS tile hadron calorimeter

    NASA Astrophysics Data System (ADS)

    Boumediene, D.

    2013-08-01

    The TileCal is the hadronic calorimeter covering the most central region of the ATLAS experiment at LHC. It is a sampling calorimeter with iron plates as absorber and plastic scintillating tiles as the active material. The scintillation light produced by the passage of charged particles is transmitted by wavelength shifting fibers to about 10,000 photomultiplier tubes (PMTs). Integrated to the calorimeter, there is a composite device that allows to monitor and/or equalize the signals at various stages of their formation. This device is based on signal generation from different sources: radioactive, LASER, charge injection and minimum bias events produced in proton-proton collisions. Recent performances of these systems are presented.

  7. Slipping properties of ceramic tiles / Quantification of slip resistance

    NASA Astrophysics Data System (ADS)

    Terjek, Anita

    2013-12-01

    Regarding the research and application of ceramic tiles there is a great importance of defining precisely the interaction and friction between surfaces. Measuring slip resistance of floor coverings is a complex problem; slipperiness is always interpreted relatively. In the lack of a consistent and clear EU standard, it is practical to use more method in combination. It is necessary to examine the structure of materials in order to get adequate correlation. That is why measuring techniques of surface roughness, an important contributor to slip resistance and cleaning, is fundamental in the research. By comparing the obtained test results, relationship between individual methods of analysis and values may be determined and based on these information recommendations shall be prepared concerning the selection and application of tiles.

  8. DNA-Tile Structures Induce Ionic Currents through Lipid Membranes.

    PubMed

    Göpfrich, Kerstin; Zettl, Thomas; Meijering, Anna E C; Hernández-Ainsa, Silvia; Kocabey, Samet; Liedl, Tim; Keyser, Ulrich F

    2015-05-13

    Self-assembled DNA nanostructures have been used to create man-made transmembrane channels in lipid bilayers. Here, we present a DNA-tile structure with a nominal subnanometer channel and cholesterol-tags for membrane anchoring. With an outer diameter of 5 nm and a molecular weight of 45 kDa, the dimensions of our synthetic nanostructure are comparable to biological ion channels. Because of its simple design, the structure self-assembles within a minute, making its creation scalable for applications in biology. Ionic current recordings demonstrate that the tile structures enable ion conduction through lipid bilayers and show gating and voltage-switching behavior. By demonstrating the design of DNA-based membrane channels with openings much smaller than that of the archetypical six-helix bundle, our work showcases their versatility inspired by the rich diversity of natural membrane components.

  9. Large-scale testing of structural clay tile infilled frames

    SciTech Connect

    Flanagan, R.D.; Bennett, R.M.

    1993-03-18

    A summary of large-scale cyclic static tests of structural clay tile infilled frames is given. In-plane racking tests examined the effects of varying frame stiffness, varying infill size, infill offset from frame centerline, and single and double wythe infill construction. Out-of-plane tests examined infilled frame response to inertial loadings and inter-story drift loadings. Sequential in-plane and out-of-plane loadings were performed to determine the effects of orthogonal damage and degradation on both strength and stiffness. A combined out-of-plane inertial and in-plane racking test was conducted to investigate the interaction of multi-directional loading. To determine constitutive properties of the infills, prism compression, mortar compression and various unit tile tests were performed.

  10. Methylation profiling using methylated DNA immunoprecipitation and tiling array hybridization.

    PubMed

    Cheung, Hoi-Hung; Lee, Tin-Lap; Rennert, Owen M; Chan, Wai-Yee

    2012-01-01

    DNA methylation is an important epigenetic modification that regulates development and plays a role in the pathophysiology of many diseases. It is dynamically changed during germline development. Methylated DNA immunoprecipitation (MeDIP) is an efficient, cost-effective method for locus-specific and genome-wide analysis. Methylated DNA fragments are enriched by a 5-methylcytidine-recognizing antibody, therefore allowing the analysis of both CpG and non-CpG methylation. The enriched DNA fragments can be amplified and hybridized to tiling arrays covering CpG islands, promoters, or the entire genome. Comparison of different methylomes permits the discovery of differentially methylated regions that might be important in disease- or tissue-specific expression. Here, we describe an established MeDIP protocol and tiling array hybridization method for profiling methylation of testicular germ cells.

  11. 3He on preplated graphite

    NASA Astrophysics Data System (ADS)

    Gordillo, M. C.; Boronat, J.

    2016-10-01

    By using the diffusion Monte Carlo method, we obtained the full phase diagram of 3He on top of graphite preplated with a solid layer of 4He. All the 4He atoms of the substrate were explicitly considered and allowed to move during the simulation. We found that the ground state is a liquid of density 0.007 ±0.001 Å-2, in good agreement with available experimental data. This is significantly different from the case of 3He on clean graphite, in which both theory and experiment agree on the existence of a gas-liquid transition at low densities. Upon an increase in 3He density, we predict a first-order phase transition between a dense liquid and a registered 7/12 phase, the 4/7 phase being found metastable in our calculations. At larger second-layer densities, a final transition is produced to an incommensurate triangular phase.

  12. Graphite moderated (252)Cf source.

    PubMed

    Sajo-Bohus, Laszlo; Barros, Haydn; Greaves, Eduardo D; Vega-Carrillo, Hector Rene

    2015-06-01

    The Thorium molten-salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid-fuel reactor. The neutron source to run this subcritical reactor is a (252)Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the (252)Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator.

  13. Fission Product Sorptivity in Graphite

    SciTech Connect

    Tompson, Jr., Robert V.; Loyalka, Sudarshan; Ghosh, Tushar; Viswanath, Dabir; Walton, Kyle; Haffner, Robert

    2015-04-01

    Both adsorption and absorption (sorption) of fission product (FP) gases on/into graphite are issues of interest in very high temperature reactors (VHTRs). In the original proposal, we proposed to use packed beds of graphite particles to measure sorption at a variety of temperatures and to use an electrodynamic balance (EDB) to measure sorption onto single graphite particles (a few μm in diameter) at room temperature. The use of packed beds at elevated temperature is not an issue. However, the TPOC requested revision of this initial proposal to included single particle measurements at elevated temperatures up to 1100 °C. To accommodate the desire of NEUP to extend the single particle EDB measurements to elevated temperatures it was necessary to significantly revise the plan and the budget. These revisions were approved. In the EDB method, we levitate a single graphite particle (the size, surface characteristics, morphology, purity, and composition of the particle can be varied) or agglomerate in the balance and measure the sorption of species by observing the changes in mass. This process involves the use of an electron stepping technique to measure the total charge on a particle which, in conjunction with the measured suspension voltages for the particle, allows for determinations of mass and, hence, of mass changes which then correspond to measurements of sorption. Accommodating elevated temperatures with this type of system required a significant system redesign and required additional time that ultimately was not available. These constraints also meant that the grant had to focus on fewer species as a result. Overall, the extension of the original proposed single particle work to elevated temperatures added greatly to the complexity of the proposed project and added greatly to the time that would eventually be required as well. This means that the bulk of the experimental progress was made using the packed bed sorption systems. Only being able to recruit one

  14. Dispersive interactions in graphitic nanostructures

    NASA Astrophysics Data System (ADS)

    Woods, L. M.; Popescu, A.; Drosdoff, D.; Bondarev, I. V.

    2013-02-01

    The Casimir interaction between graphitic nanostructures, such as carbon nanotubes and graphene sheets, is investigated at the quantum mechanical limit (T = 0 K) using a quantum electrodynamical approach for absorbing and dispersive media. It is found that the nanotube/nanotube interaction in a double wall carbon nanotube configuration is profoundly affected by the collective low frequency excitations of individual nanotubes. It is shown that pronounced, low frequency peaks in the nanotube electron energy loss spectra are a main factor contributing to the strength of the intertube attraction. The graphene/graphene force is also investigated. It is obtained that the graphene optical transparency is the main reason for the reduced attraction as compared to the one for perfect metals. This study presents a unified approach for electromagnetic interactions in graphitic nanostructures, which is able to account for their unique electronic and response properties and geometry configurations.

  15. 3D-graphite structure

    SciTech Connect

    Belenkov, E. A. Ali-Pasha, V. A.

    2011-01-15

    The structure of clusters of some new carbon 3D-graphite phases have been calculated using the molecular-mechanics methods. It is established that 3D-graphite polytypes {alpha}{sub 1,1}, {alpha}{sub 1,3}, {alpha}{sub 1,5}, {alpha}{sub 2,1}, {alpha}{sub 2,3}, {alpha}{sub 3,1}, {beta}{sub 1,2}, {beta}{sub 1,4}, {beta}{sub 1,6}, {beta}{sub 2,1}, and {beta}{sub 3,2} consist of sp{sup 2}-hybridized atoms, have hexagonal unit cells, and differ in regards to the structure of layers and order of their alternation. A possible way to experimentally synthesize new carbon phases is proposed: the polymerization and carbonization of hydrocarbon molecules.

  16. AGC-3 Graphite Preirradiation Data Analysis Report

    SciTech Connect

    William Windes; David Swank; David Rohrbaugh; Joseph Lord

    2013-09-01

    This report describes the specimen loading order and documents all pre-irradiation examination material property measurement data for the graphite specimens contained within the third Advanced Graphite Capsule (AGC-3) irradiation capsule. The AGC-3 capsule is third in six planned irradiation capsules comprising the Advanced Graphite Creep (AGC) test series. The AGC test series is used to irradiate graphite specimens allowing quantitative data necessary for predicting the irradiation behavior and operating performance of new nuclear graphite grades to be generated which will ascertain the in-service behavior of the graphite for pebble bed and prismatic Very High Temperature Reactor (VHTR) designs. The general design of AGC-3 test capsule is similar to the AGC-2 test capsule, material property tests were conducted on graphite specimens prior to loading into the AGC-3 irradiation assembly. However the 6 major nuclear graphite grades in AGC-2 were modified; two previous graphite grades (IG-430 and H-451) were eliminated and one was added (Mersen’s 2114 was added). Specimen testing from three graphite grades (PCEA, 2114, and NBG-17) was conducted at Idaho National Laboratory (INL) and specimen testing for two grades (IG-110 and NBG-18) were conducted at Oak Ridge National Laboratory (ORNL) from May 2011 to July 2013. This report also details the specimen loading methodology for the graphite specimens inside the AGC-3 irradiation capsule. The AGC-3 capsule design requires "matched pair" creep specimens that have similar dose levels above and below the neutron flux profile mid-plane to provide similar specimens with and without an applied load. This document utilized the neutron flux profile calculated for the AGC-3 capsule design, the capsule dimensions, and the size (length) of the selected graphite and silicon carbide samples to create a stacking order that can produce "matched pairs" of graphite samples above and below the AGC-3 capsule elevation mid-point to

  17. Response and Uniformity Studies of Directly Coupled Tiles

    SciTech Connect

    Zutshi, Vishnu

    2010-04-02

    A finely-segmented scintillator-based calorimeter which capitalizes on the marriage of proven detection techniques with novel solid-state photo-detector devices such as Multi-pixel Photon Counters (MPPCs) is an interesting calorimetric system from the point of view of future detector design. A calorimeter system consisting of millions of channels will require a high degree of integration. The first steps towards this integration have already been facilitated by the small size and magnetic field immunity of the MPPCs. The photo-conversion occurs right at the tile, thus obviating the need for routing of long clear fibers. Similar considerations apply to the presence of wave-length shifting (WLS) fibers inside the tiles which couple it to the photo-detectors. Significant simplification in construction and assembly ensue if the MPPCs can be coupled directly to the scintillator tiles. Equally importantly, the total absence of fibers would offer greater flexibility in the choice of the transverse segmentation while enhancing the electro-mechanical integrability of the design. The NIU high-energy physics group has been studying the fiberless or direct-coupling option for some time now. Encouraging results on response and response uniformity have been obtained using radioactive sources. This MOU seeks to set up a framework to extend these tests using beams at the MTBF. The results will be relevant to high granularity scintillator/crystal electromagnetic and hadronic calorimetry. The tests involve a set of small directly-coupled tile counters fabricated at NIU which will be placed in the beam to study their response and response uniformity as a function of the incident position of the particles passing through them.

  18. Natural radioactivity content of granite tiles used in Greece.

    PubMed

    Papaefthymiou, H

    2008-01-01

    Measurements of (226)Ra, (232)Th and (40)K activity concentrations in commercial granite tiles imported in Greece were performed using gamma-ray spectrometry. The activity concentration of (226)Ra, (232)Th and (40)K ranged from 1 to 434, 2 to 239 and 71 to 1576 Bq kg(-1), respectively. The calculated activity concentration index (I) values for all granite samples examined were found to be within the EC limit values for superficial and other materials with restricted use.

  19. Cellular Uptake of Tile-Assembled DNA Nanotubes

    PubMed Central

    Kocabey, Samet; Meinl, Hanna; MacPherson, Iain S.; Cassinelli, Valentina; Manetto, Antonio; Rothenfusser, Simon; Liedl, Tim; Lichtenegger, Felix S.

    2014-01-01

    DNA-based nanostructures have received great attention as molecular vehicles for cellular delivery of biomolecules and cancer drugs. Here, we report on the cellular uptake of tubule-like DNA tile-assembled nanostructures 27 nm in length and 8 nm in diameter that carry siRNA molecules, folic acid and fluorescent dyes. In our observations, the DNA structures are delivered to the endosome and do not reach the cytosol of the GFP-expressing HeLa cells that were used in the experiments. Consistent with this observation, no elevated silencing of the GFP gene could be detected. Furthermore, the presence of up to six molecules of folic acid on the carrier surface did not alter the uptake behavior and gene silencing. We further observed several challenges that have to be considered when performing in vitro and in vivo experiments with DNA structures: (i) DNA tile tubes consisting of 42 nt-long oligonucleotides and carrying single- or double-stranded extensions degrade within one hour in cell medium at 37 °C, while the same tubes without extensions are stable for up to eight hours. The degradation is caused mainly by the low concentration of divalent ions in the media. The lifetime in cell medium can be increased drastically by employing DNA tiles that are 84 nt long. (ii) Dyes may get cleaved from the oligonucleotides and then accumulate inside the cell close to the mitochondria, which can lead to misinterpretation of data generated by flow cytometry and fluorescence microscopy. (iii) Single-stranded DNA carrying fluorescent dyes are internalized at similar levels as the DNA tile-assembled tubes used here.

  20. Tiling patterns from ABC star molecules: 3-colored foams?

    PubMed

    Kirkensgaard, Jacob J K; Pedersen, Martin C; Hyde, Stephen T

    2014-10-07

    We present coarse-grained simulations of the self-assembly of 3-armed ABC star polyphiles. In systems of star polyphiles with two arms of equal length the simulations corroborate and expand previous findings from related miktoarm star terpolymer systems on the formation of patterns containing columnar domains whose sections are 2D planar tilings. However, the systematic variation of face topologies as the length of the third (unequal) arm is varied differs from earlier findings regarding the compositional dependence. We explore 2D 3-colored foams to establish the optimal patterns based on interfacial energy alone. A generic construction algorithm is described that accounts for all observed 2D tiling patterns and suggests other patterns likely to be found beyond the range of the simulations reported here. Patterns resulting from this algorithm are relaxed using Surface Evolver calculations to form 2D foams with minimal interfacial length as a function of composition. This allows us to estimate the interfacial enthalpic contributions to the free energy of related star molecular assemblies assuming strong segregation. We compare the resulting phase sequence with a number of theoretical results from particle-based simulations and field theory, allowing us to tease out relative enthalpic and entropic contributions as a function of the chain lengths making up the star molecules. Our results indicate that a richer polymorphism is to be expected in systems not dominated by chain entropy. Further, analysis of corresponding planar tiling patterns suggests that related two-periodic columnar structures are unlikely hypothetical phases in 4-arm star polyphile melts in the absence of sufficient arm configurational freedom for minor domains to form lens-shaped di-gons, which require higher molecular weight polymeric arms. Finally, we discuss the possibility of forming a complex tiling pattern that is a quasi-crystalline approximant for 3-arm star polyphiles with unequal arm

  1. Poster: Building a Large Tiled-Display Cluster

    DTIC Science & Technology

    2012-10-01

    constructed a tiled-display matrix which makes the most use of the available space. However, this has made maintenance incon- 1Axel Mellinger’s Milky Way ...image of the milky way . Pub- lications of the Astronomical Society of the Pacific, 2009. [5] T. Ni, G. S. Schmidt, O. G. Staadt, M. A. Livingston, R...theoretically mul- tiply computational throughput. In the same way , individual dis- plays or projectors can be combined to expand the visual real

  2. Optically Tiled Flat Panel Displays. A Feasibility Study

    DTIC Science & Technology

    1992-11-01

    distortion. The fabrication of a traditional rotational symmetric Fresnel lens could be possible using diamond turning methods. However the rotational...and allow the microlens array to be located next to the LCD module output polarizer and immediately followed by the negative Fresnel lens and then the...microlenses remapping the pixels onto a diffuser through a 4 negative Fresnel lens (Figure 11). This method could tile together LCD modules separated by a

  3. A hollow clay tile wall seismic performance program overview

    SciTech Connect

    Beavers, J.E.; Jones, W.D.; Stoddart, W.C.T.

    1992-02-25

    An overview of a multiyear hollow clay tile wall (HCTW) program being conducted by Martin Marietta Energy Systems, Inc., at the Oak Ridge Y-12 Plant, for the US Department of Energy is presented. The purpose of the HCTW program is to determine the load capacity of unreinforced infilled HCTW buildings when subjected to earthquakes. Progress to date tends to indicate that extensive retrofit of such structures may not be warranted in low-to-moderate seismic zones.

  4. The geometry of the 37-tile microwave antenna support structure

    NASA Technical Reports Server (NTRS)

    Finley, L. A.

    1980-01-01

    The geometry of the support structure for a proposed parabolic shaped microwave antenna is examined. The surface of the antenna is comprised of 37 hexagonal shaped tiles, each connected to a truss module. The units are joined together to form a rigidized, faceted, concave parabolic surface. The geometry specifications are described through an explanation of the structural components which make up the antenna, a description of the coordinate system devised to identify the structure, and a presentation of the nondimensional results.

  5. Graphite/Thermoplastic-Pultrusion Die

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Frye, Mark W.; Johnson, Gary S.; Stanfield, Clarence E.

    1990-01-01

    Attachment to extruder produces thermoplastic-impregnated graphite tape. Consists of profile die, fiber/resin collimator, and crosshead die body. Die designed to be attached to commercially available extrusion machine capable of extruding high-performance thermoplastics. Simple attachment to commercial extruder enables developers of composites to begin experimenting with large numbers of proprietary resins, fibers, and hybrid composite structures. With device, almost any possible fiber/resin combination fabricated.

  6. Poco Graphite Mirror Metrology Report

    NASA Technical Reports Server (NTRS)

    Kester, Thomas J.

    2005-01-01

    Recently a lightweight mirror technology was tested at Marshall Space Flight Center's Space Optic Manufacturing Technology Center (MSFC, SOMTC). The mirror is a Poco Graphite CVD Si clad SiC substrate. It was tested for cryogenic (cryo) survivability to 20deg Kelvin in SOMTC's X-ray Calibration and Cryogenic Test Facility. The surface figure of the mirror was measured before and after cry0 cycling. The test technique and results are discussed.

  7. The effect of manufacturing variables on radiation doses from porcelain tiles.

    PubMed

    Selby, J H; Strydom, R

    2008-06-01

    Previous studies have focused on the radiological properties of glazed ceramic tiles. This study was conducted to describe the radiological properties of porcelain tiles and how they were affected by variations in the manufacturing parameters. The data showed that the majority of the uranium in the tiles was attributable to the addition of zircon while less than half of the thorium in the tile was attributable to the added zircon, and the remainder came from other minerals in the formulation. The effects of firing temperatures and compressive strengths of the tiles are presented and show that higher firing temperatures increase radon emanation, while higher compressive strengths reduce radon emanation. The study also described how the addition of zircon to the tile formulation affected the radiological exposures that could be received by a member of the public from the use of such porcelain tiles. A dose assessment was conducted based on 23 different types of tile formulation. Screening procedures for building materials have been described in European Commission documents, and these limit the addition of zircon in a porcelain tile to approximately 9% by mass. The dose assessment reported in this study showed that 20% zircon could be added to a porcelain tile without exceeding the prescribed dose limits.

  8. Graphite Nanoreinforcements for Aerospace Nanocomposites

    NASA Technical Reports Server (NTRS)

    Drzal, Lawrence T.

    2005-01-01

    New advances in the reinforcement of polymer matrix composite materials are critical for advancement of the aerospace industry. Reinforcements are required to have good mechanical and thermal properties, large aspect ratio, excellent adhesion to the matrix, and cost effectiveness. To fulfill the requirements, nanocomposites in which the matrix is filled with nanoscopic reinforcing phases having dimensions typically in the range of 1nm to 100 nm show considerably higher strength and modulus with far lower reinforcement content than their conventional counterparts. Graphite is a layered material whose layers have dimensions in the nanometer range and are held together by weak Van der Waals forces. Once these layers are exfoliated and dispersed in a polymer matrix as nano platelets, they have large aspect ratios. Graphite has an elastic modulus that is equal to the stiffest carbon fiber and 10-15 times that of other inorganic reinforcements, and it is also electrically and thermally conductive. If the appropriate surface treatment can be found for graphite, its exfoliation and dispersion in a polymer matrix will result in a composite with excellent mechanical properties, superior thermal stability, and very good electrical and thermal properties at very low reinforcement loadings.

  9. Development of polyphenylquinoxaline graphite composites

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.; Hergenrother, P. M.; Shdo, J. G.

    1973-01-01

    The potential of polyphenylquinoxaline (PPQ)/graphite composites to serve as structural material at 316 C (600 F)has been demonstrated using a block copolymer, BlCo(13), PPQ derivative. Initially, thirteen polyphenylquinoxalines were evaluated. From this work, four candidate polymers were selected for preliminary evaluation as matrices for HMS graphite fiber reinforced composites. The preliminary composite evaluation enabled selection of one of the four polymers for advanced composite preparation and testing. Using an experimentally established cure schedule for each of the four polymers, preliminary laminates of 50% resin volume content, prepared without postcure, were tested for flexure strength and modulus, interlaminar shear strength (short beam), and tensile strength and modulus at ambient temperature. A block copolymer (Bl Co 13) derived from one mole p-bis (phenylglyoxalyl) benzene, one fourth mole 3,3'-diaminobenzidine and three-fourths mole 3,3', 4,4'-tetraminobenzophenone was selected for extensive study. Tensile, flexural, and interlaminar shear values were obtained after aging and testing postcured BlCo(13) laminates at 316 C (600 F). The potential of PPQ/graphite laminates to serve as short term structural materials at temperatures up to 371 C (700 F) was demonstrated through weight loss experiments.

  10. Revealing Transcriptome Landscape of Mouse Spermatogonial Cells by Tiling Microarray

    PubMed Central

    Lee, Tin-Lap.; Rennert, Owen M.; Chan, Wai-Yee.

    2014-01-01

    Summary Spermatogenesis is a highly regulated developmental process by which spermatogonia develop into mature spermatozoa. This process involves many testis- or male germ cell-specific events through tightly regulated gene expression programs. In the past decade the advent of microarray technologies has allowed functional genomic studies of male germ cell development, resulting in the identification of genes governing various processes. A major limitation with conventional gene expression microarray is that there is a bias from gene probe design. The gene probes for expression microarrays are usually represented by a small number probes located at the 3’ end of a transcirpt. Tiling microarrays eliminate such issue by interrogating the genome in an unbiased fashion through probes tiled for the entire genome. These arrays provide a higher genomic resolution and allow identification of novel transcripts. To reveal the complexity of the genomic landscape of developing male germ cells, we applied tiling microarray to evaluate the transcriptome in spermatogonial cells. Over 50% of the mouse and rat genome are expressed during testicular development. More than 47% of transcripts are uncharacterized. The results suggested the transcription machinery in spermaotogonial cells are more complex than previously envisioned. PMID:22144238

  11. Effects of thermal blooming on systems comprised of tiled subapertures

    NASA Astrophysics Data System (ADS)

    Leakeas, Charles L.; Bartell, Richard J.; Krizo, Matthew J.; Fiorino, Steven T.; Cusumano, Salvatore J.; Whiteley, Matthew R.

    2010-04-01

    Laser weapon systems comprise of tiled subapertures are rapidly emerging in the directed energy community. The Air Force Institute of Technology Center for Directed Energy (AFIT/CDE), under sponsorship of the HEL Joint Technology Office has developed performance models of such laser weapon system configurations consisting of tiled arrays of both slab and fiber subapertures. These performance models are based on results of detailed waveoptics analyses conducted using WaveTrain. Previous performance model versions developed in this effort represent system characteristics such as subaperture shape, aperture fill factor, subaperture intensity profile, subaperture placement in the primary aperture, subaperture mutual coherence (piston), subaperture differential jitter (tilt), and beam quality wave-front error associated with each subaperture. The current work is a prerequisite for the development of robust performance models for turbulence and thermal blooming effects for tiled systems. Emphasis is placed on low altitude tactical scenarios. The enhanced performance model developed will be added to AFIT/CDE's HELEEOS parametric one-on-one engagement level model via the Scaling for High Energy Laser and Relay Engagement (SHaRE) toolbox.

  12. Buffing, burnishing, and stripping of vinyl asbestos floor tile

    SciTech Connect

    Hollett, B.A.; Edwards, A.; Clark, P.J.

    1995-10-01

    Studies were conducted to evaluate airborne asbestos concentrations during the three principal types of preventative maintenance (low-speed spray-buffing, ultra high-speed burnishing, and wet-stripping) used on asbestos-containing floor tiles. These were done under pre-existing and prepared levels of floor care maintenance. Airborne asbestos concentrations were measured before and during each floor care procedure to determine the magnitude of the increase in airborne asbestos levels during each procedure. Airborne total fiber concentrations were also measured for comparison with the Occupational Safety and Health Administration`s (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cm{sup 3}. Low-speed spray-buffing and wet-stripping were evaluated on pre-existing floor conditions and three levels of prepared floor care conditions (poor, medium, and good). Ultra high-speed burnishing and wet-stripping were evaluated on two levels of prepared floor care conditions (poor and good). Floor care conditions were defined in consultation with the Chemical Specialty Manufacturers Association and other representatives of floor-care chemical manufacturers. Controlled studies were conducted in an unoccupied building at the decommissioned Chanute Air Force Base in Rantoul, Illinois, with the cooperation of the U.S. Air Force. The building offered approximately 8600 ft{sup 2} of open floor space tiled with 9-inch by 9-inch resilient floor tile containing approximately 5% chrysotile asbestos.

  13. Orion EFT-1 Catalytic Tile Experiment Overview and Flight Measurements

    NASA Technical Reports Server (NTRS)

    Salazar, Giovanni; Amar, Adam; Hyatt, Andrew; Rezin, Marc D.

    2016-01-01

    This paper describes the design and results of a surface catalysis flight experiment flown on the Orion Multipurpose Crew Vehicle during Exploration Flight Test 1 (EFT1). Similar to previous Space Shuttle catalytic tile experiments, the present test consisted of a highly catalytic coating applied to an instrumented TPS tile. However, the present catalytic tile experiment contained significantly more instrumentation in order to better resolve the heating overshoot caused by the change in surface catalytic efficiency at the interface between two distinct materials. In addition to collecting data with unprecedented spatial resolution of the "overshoot" phenomenon, the experiment was also designed to prove if such a catalytic overshoot would be seen in turbulent flow in high enthalpy regimes. A detailed discussion of the results obtained during EFT1 is presented, as well as the challenges associated with data interpretation of this experiment. Results of material testing carried out in support of this flight experiment are also shown. Finally, an inverse heat conduction technique is employed to reconstruct the flight environments at locations upstream and along the catalytic coating. The data and analysis presented in this work will greatly contribute to our understanding of the catalytic "overshoot" phenomenon, and have a significant impact on the design of future spacecraft.

  14. Tiling of the Drosophila epidermis by multidendritic sensory neurons.

    PubMed

    Grueber, Wesley B; Jan, Lily Y; Jan, Yuh Nung

    2002-06-01

    Insect dendritic arborization (da) neurons provide an opportunity to examine how diverse dendrite morphologies and dendritic territories are established during development. We have examined the morphologies of Drosophila da neurons by using the MARCM (mosaic analysis with a repressible cell marker) system. We show that each of the 15 neurons per abdominal hemisegment spread dendrites to characteristic regions of the epidermis. We place these neurons into four distinct morphological classes distinguished primarily by their dendrite branching complexities. Some class assignments correlate with known proneural gene requirements as well as with central axonal projections. Our data indicate that cells within two morphological classes partition the body wall into distinct, non-overlapping territorial domains and thus are organized as separate tiled sensory systems. The dendritic domains of cells in different classes, by contrast, can overlap extensively. We have examined the cell-autonomous roles of starry night (stan) (also known as flamingo (fmi)) and sequoia (seq) in tiling. Neurons with these genes mutated generally terminate their dendritic fields at normal locations at the lateral margin and segment border, where they meet or approach the like dendrites of adjacent neurons. However, stan mutant neurons occasionally send sparsely branched processes beyond these territories that could potentially mix with adjacent like dendrites. Together, our data suggest that widespread tiling of the larval body wall involves interactions between growing dendritic processes and as yet unidentified signals that allow avoidance by like dendrites.

  15. Defect detection for end surface of ferrite magnetic tile

    NASA Astrophysics Data System (ADS)

    Tao, Jiayuan; Wang, Yuwei; Wang, Keyi

    2016-09-01

    A visual automatic detection method is proposed for defect detection on end surface of ferrite magnetic tile to tackle the disadvantages generated by human work which has low efficiency and unstable accuracy. Because the defects on end surface of ferrite magnetic tile with dark colors and low contrasts are negative for defect detection, uniform illumination is provided by LED light source and a dedicated optical system is designed to extract defects conveniently. The approach uses comparison of the fitting and actual edge curves to detect defects mainly with most defects located on the edge. Firstly improved adaptive median filter is used as the image preprocessing. Subsequently the appropriate threshold is calculated by Otsu algorithm based on the extreme points in the gray-level histogram to segment the preprocessing image. Then the Sobel operator can be used to extract the edge of end surface precisely. Finally through comparing the ideal fitting and actual edge curves of end surface, to detect the defects with some relevant features. Experimental results show that the proposed scheme could detect defects on the end surface of ferrite magnetic tile efficiency and accurately with 93.33% accuracy rate, 2.30% false acceptance rate and 8.45% correct rejection rate.

  16. Alpha storage regime in high temperature sub-ignited D-T tokamaks

    SciTech Connect

    Zweben, S.J.; Furth, H.P.; Mikkelsen, D.R.; Redi, M.H.; Strachan, J.D.

    1988-07-01

    Alpha particle parameters in sub-ignited D-T tokamaks like TFTR can be optimized in a high temperature ''alpha storage regime '' in which the alpha particle thermalization time /tau//sub ..cap alpha../ is long (approx.1.0 sec) and in which the alpha particle source rate S/sub ..cap alpha../ is enhanced due to a beam-target and beam-beam reactions (by a factor of approx.2-3). Near reactor-level alpha instability parameters ..beta../sub ..cap alpha../(0) approx. n/sub ..cap alpha../(0)/n/sub e/(O) approx. 1% are predicted by simulation codes when Q approx. 0.5-1, while present TFTR ''supershots'' already have ..beta../sub ..cap alpha../(O) approx. n/sub /alpha/(O)/n/sub e/(O) /approx/ 0.1-0.2%. Plasmas in this regime can be used to test theories of collective alpha instabilities for the first time, and can be used to provide a strong (but transient) alpha heating pulse. An experimental scenario to exploit this regime is described. 28 refs., 5 figs., 5 tabs.,

  17. Helium release and microstructural changes in Er(D,T)2-x3Hex films).

    SciTech Connect

    Gelles, D. S.; Browning, James Frederick; Snow, Clark Sheldon; Banks, James Clifford; Mangan, Michael A.; Rodriguez, Mark Andrew; Brewer, Luke N.; Kotula, Paul Gabriel

    2007-12-01

    Er(D,T){sub 2-x} {sup 3}He{sub x}, erbium di-tritide, films of thicknesses 500 nm, 400 nm, 300 nm, 200 nm, and 100 nm were grown and analyzed by Transmission Electron Microscopy, X-Ray Diffraction, and Ion Beam Analysis to determine variations in film microstructure as a function of film thickness and age, due to the time-dependent build-up of {sup 3}He in the film from the radioactive decay of tritium. Several interesting features were observed: One, the amount of helium released as a function of film thickness is relatively constant. This suggests that the helium is being released only from the near surface region and that the helium is not diffusing to the surface from the bulk of the film. Two, lenticular helium bubbles are observed as a result of the radioactive decay of tritium into {sup 3}He. These bubbles grow along the [111] crystallographic direction. Three, a helium bubble free zone, or 'denuded zone' is observed near the surface. The size of this region is independent of film thickness. Four, an analysis of secondary diffraction spots in the Transmission Electron Microscopy study indicate that small erbium oxide precipitates, 5-10 nm in size, exist throughout the film. Further, all of the films had large erbium oxide inclusions, in many cases these inclusions span the depth of the film.

  18. Automated White Matter Hyperintensity Detection in Multiple Sclerosis Using 3D T2 FLAIR

    PubMed Central

    Zhong, Yi; Wang, Ying; Kang, Yan; Haacke, E. Mark

    2014-01-01

    White matter hyperintensities (WMH) seen on T2WI are a hallmark of multiple sclerosis (MS) as it indicates inflammation associated with the disease. Automatic detection of the WMH can be valuable in diagnosing and monitoring of treatment effectiveness. T2 fluid attenuated inversion recovery (FLAIR) MR images provided good contrast between the lesions and other tissue; however the signal intensity of gray matter tissue was close to the lesions in FLAIR images that may cause more false positives in the segment result. We developed and evaluated a tool for automated WMH detection only using high resolution 3D T2 fluid attenuated inversion recovery (FLAIR) MR images. We use a high spatial frequency suppression method to reduce the gray matter area signal intensity. We evaluate our method in 26 MS patients and 26 age matched health controls. The data from the automated algorithm showed good agreement with that from the manual segmentation. The linear correlation between these two approaches in comparing WMH volumes was found to be Y = 1.04X + 1.74  (R2 = 0.96). The automated algorithm estimates the number, volume, and category of WMH. PMID:25136355

  19. A Parametric Investigation of Breaking Bow Waves using a 2D+T Wave Maker

    NASA Astrophysics Data System (ADS)

    Maxeiner, E. A.; Shakeri, M.; Duncan, J. H.

    2008-11-01

    An experimental study of bow waves generated by a 2D+T (Two Dimensions plus Time) wave maker in a tank that is 14.8 m long, 1.2 m wide and 2.2 m deep is presented. Rather than simulating a specific ship hull, here we use a parametric set of wave maker motions with each parameter simulating a common feature of a ship hull form. Three categories of wave maker motions are used: ``slap'' (rotation of the wave board (held flat) about the keel), ``fixed'' (translation the wave board while it is upper part remains flat and at a fixed angle relative to horizontal), and ``full'' (simultaneous rotation and translation). The wave maker motions are run over a range of speeds and, in the ``fixed'' cases, over a range of angles. The temporal histories of the wave profiles were measured using a cinematic LIF technique. The relationship between various geometrical features of the waves and the wave maker motion parameters is explored. Each category of wave maker motions produces waves that develop and break in markedly different ways, thus highlighting the complex nature of bow waves. The wave crest speeds vary between 2 and 2.5 times the maximum speed of the wave maker and, for a given class of wave maker motion, vary with wave maker speed.

  20. Study on the impact of pair production interaction on D-T controllable neutron density logging.

    PubMed

    Yu, Huawei; Zhang, Li; Hou, Boran

    2016-05-01

    This paper considers the effect of pair production on the precision of D-T controllable neutron source density logging. Firstly, the principle of the traditional density logging and pulsed neutron density logging are analyzed and then gamma ray cross sections as a function of energy for various minerals are compared. In addition, the advantageous areas of Compton scattering and pair production interactions on high-energy gamma ray pulse height spectrum and the errors of a controllable source density measurement are studied using a Monte Carlo simulation method. The results indicate that density logging mainly utilizes the Compton scattering of gamma rays, while the attenuation of neutron induced gamma rays and the precision of neutron gamma density measurements are affected by pair production interactions, particularly in the gamma rays with energy higher than 2MeV. By selecting 0.2-2MeV energy range and performing proper lithology correction, the effect of pair production can be eliminated effectively and the density measurement error can be rendered close to the precision of chemical source density logging.

  1. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    DOEpatents

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  2. Electrochemical Ultracapacitors Using Graphitic Nanostacks

    NASA Technical Reports Server (NTRS)

    Marotta, Christopher

    2012-01-01

    Electrochemical ultracapacitors (ECs) have been developed using graphitic nanostacks as the electrode material. The advantages of this technology will be the reduction of device size due to superior power densities and relative powers compared to traditional activated carbon electrodes. External testing showed that these materials display reduced discharge response times compared to state-of-the-art materials. Such applications are advantageous for pulsed power applications such as burst communications (satellites, cell phones), electromechanical actuators, and battery load leveling in electric vehicles. These carbon nanostructures are highly conductive and offer an ordered mesopore network. These attributes will provide more complete electrolyte wetting, and faster release of stored charge compared to activated carbon. Electrochemical capacitor (EC) electrode materials were developed using commercially available nanomaterials and modifying them to exploit their energy storage properties. These materials would be an improvement over current ECs that employ activated carbon as the electrode material. Commercially available graphite nanofibers (GNFs) are used as precursor materials for the synthesis of graphitic nanostacks (GNSs). These materials offer much greater surface area than graphite flakes. Additionally, these materials offer a superior electrical conductivity and a greater average pore size compared to activated carbon electrodes. The state of the art in EC development uses activated carbon (AC) as the electrode material. AC has a high surface area, but its small average pore size inhibits electrolyte ingress/egress. Additionally, AC has a higher resistivity, which generates parasitic heating in high-power applications. This work focuses on fabricating EC from carbon that has a very different structure by increasing the surface area of the GNF by intercalation or exfoliation of the graphitic basal planes. Additionally, various functionalities to the GNS

  3. Pyrolytic graphite gauge for measuring heat flux

    NASA Technical Reports Server (NTRS)

    Bunker, Robert C. (Inventor); Ewing, Mark E. (Inventor); Shipley, John L. (Inventor)

    2002-01-01

    A gauge for measuring heat flux, especially heat flux encountered in a high temperature environment, is provided. The gauge includes at least one thermocouple and an anisotropic pyrolytic graphite body that covers at least part of, and optionally encases the thermocouple. Heat flux is incident on the anisotropic pyrolytic graphite body by arranging the gauge so that the gauge surface on which convective and radiative fluxes are incident is perpendicular to the basal planes of the pyrolytic graphite. The conductivity of the pyrolytic graphite permits energy, transferred into the pyrolytic graphite body in the form of heat flux on the incident (or facing) surface, to be quickly distributed through the entire pyrolytic graphite body, resulting in small substantially instantaneous temperature gradients. Temperature changes to the body can thereby be measured by the thermocouple, and reduced to quantify the heat flux incident to the body.

  4. Uranium Oxide Aerosol Transport in Porous Graphite

    SciTech Connect

    Blanchard, Jeremy; Gerlach, David C.; Scheele, Randall D.; Stewart, Mark L.; Reid, Bruce D.; Gauglitz, Phillip A.; Bagaasen, Larry M.; Brown, Charles C.; Iovin, Cristian; Delegard, Calvin H.; Zelenyuk, Alla; Buck, Edgar C.; Riley, Brian J.; Burns, Carolyn A.

    2012-01-23

    The objective of this paper is to investigate the transport of uranium oxide particles that may be present in carbon dioxide (CO2) gas coolant, into the graphite blocks of gas-cooled, graphite moderated reactors. The transport of uranium oxide in the coolant system, and subsequent deposition of this material in the graphite, of such reactors is of interest because it has the potential to influence the application of the Graphite Isotope Ratio Method (GIRM). The GIRM is a technology that has been developed to validate the declared operation of graphite moderated reactors. GIRM exploits isotopic ratio changes that occur in the impurity elements present in the graphite to infer cumulative exposure and hence the reactor’s lifetime cumulative plutonium production. Reference Gesh, et. al., for a more complete discussion on the GIRM technology.

  5. METHOD FOR COATING GRAPHITE WITH METALLIC CARBIDES

    DOEpatents

    Steinberg, M.A.

    1960-03-22

    A method for producing refractory coatings of metallic carbides on graphite was developed. In particular, the graphite piece to be coated is immersed in a molten solution of 4 to 5% by weight of zirconium, titanium, or niobium dissolved in tin. The solution is heated in an argon atmosphere to above 1400 deg C, whereby the refractory metal reacts with the surface of the graphite to form a layer of metalic carbide. The molten solution is cooled to 300 to 400 deg C, and the graphite piece is removed. Excess tin is wiped from the graphite, which is then heated in vacuum to above 2300 deg C. The tin vaporizes from the graphite surface, leaving the surface coated with a tenacious layer of refractory metallic carbide.

  6. Superlubricity of Fullerene Intercalated Graphite Composite

    NASA Astrophysics Data System (ADS)

    Miura, Kouji; Tsuda, Daisuke; Itamura, Noriaki; Sasaki, Naruo

    2007-08-01

    A novel superlubric system of fullerene intercalated graphite composite is reported. First, it is clarified that fullerene intercalated graphite films exhibit an ultralow average friction force and an excellent friction coefficient μ <0.001 smaller than μ <0.002 for MoS2 and μ\\cong 0.001 for graphite. Next, it is demonstrated that superlubricity can be controlled by changing the intercalant species. The C60 intercalated graphite film shows much less maximum static friction force than the C70 intercalated graphite film. Finally, we propose one of the simple guidelines on designing a practical superlubric system-reduction in the contact area between the intercalated fullerene and the graphite sheet to the pointlike contact. Our newly developed superlubric system will contribute to solving energy and environmental problems.

  7. Removal of carbon-14 from irradiated graphite

    NASA Astrophysics Data System (ADS)

    Dunzik-Gougar, Mary Lou; Smith, Tara E.

    2014-08-01

    Approximately 250,000 tonnes of irradiated graphite waste exists worldwide and that quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation IV gas-cooled, graphite moderated reactors. This situation indicates the need for a graphite waste management strategy. On of the isotopes of great concern for long-term disposal of irradiated graphite is carbon-14 (14C), with a half-life of 5730 years. Study of irradiated graphite from some nuclear reactors indicates 14C is concentrated on the outer 5 mm of the graphite structure. The aim of the research presented here is to develop a practical method by which 14C can be removed. In parallel with these efforts, the same irradiated graphite material is being characterized to identify the chemical form of 14C in irradiated graphite. A nuclear-grade graphite, NBG-18, and a high-surface-area graphite foam, POCOFoam®, were exposed to liquid nitrogen (to increase the quantity of 14C precursor) and neutron-irradiated (1013 neutrons/cm2/s). During post-irradiation thermal treatment, graphite samples were heated in the presence of an inert carrier gas (with or without the addition of an oxidant gas), which carries off gaseous products released during treatment. Graphite gasification occurs via interaction with adsorbed oxygen complexes. Experiments in argon only were performed at 900 °C and 1400 °C to evaluate the selective removal of 14C. Thermal treatment also was performed with the addition of 3 and 5 vol% oxygen at temperatures 700 °C and 1400 °C. Thermal treatment experiments were evaluated for the effective selective removal of 14C. Lower temperatures and oxygen levels correlated to more efficient 14C removal.

  8. Coverage percentage and raman measurement of cross-tile and scaffold cross-tile based DNA nanostructures.

    PubMed

    Gnapareddy, Bramaramba; Ahn, Sang Jung; Dugasani, Sreekantha Reddy; Kim, Jang Ah; Amin, Rashid; Mitta, Sekhar Babu; Vellampatti, Srivithya; Kim, Byeonghoon; Kulkarni, Atul; Kim, Taesung; Yun, Kyusik; LaBean, Thomas H; Park, Sung Ha

    2015-11-01

    We present two free-solution annealed DNA nanostructures consisting of either cross-tile CT1 or CT2. The proposed nanostructures exhibit two distinct structural morphologies, with one-dimensional (1D) nanotubes for CT1 and 2D nanolattices for CT2. When we perform mica-assisted growth annealing with CT1, a dramatic dimensional change occurs where the 1D nanotubes transform into 2D nanolattices due to the presence of the substrate. We assessed the coverage percentage of the 2D nanolattices grown on the mica substrate with CT1 and CT2 as a function of the concentration of the DNA monomer. Furthermore, we fabricated a scaffold cross-tile (SCT), which is a new design of a modified cross-tile that consists of four four-arm junctions with a square aspect ratio. For SCT, eight oligonucleotides are designed in such a way that adjacent strands with sticky ends can produce continuous arms in both the horizontal and vertical directions. The SCT was fabricated via free-solution annealing, and self-assembled SCT produces 2D nanolattices with periodic square cavities. All structures were observed via atomic force microscopy. Finally, we fabricated divalent nickel ion (Ni(2+))- and trivalent dysprosium ion (Dy(3+))-modified 2D nanolattices constructed with CT2 on a quartz substrate, and the ion coordinations were examined via Raman spectroscopy.

  9. METHOD FOR COATING GRAPHITE WITH NIOBIUM CARBIDE

    DOEpatents

    Kane, J.S.; Carpenter, J.H.; Krikorian, O.H.

    1962-01-16

    A method is given for coating graphite with a hard, tenacious layer of niobium carbide up to 30 mils or more thick. The method makes use of the discovery that niobium metal, if degassed and heated rapidly below the carburization temperature in contact with graphite, spreads, wets, and penetrates the graphite without carburization. The method includes the obvious steps of physically contacting niobium powders or other physical forms of niobium with graphite, degassing the assembly below the niobium melting point, e.g., 1400 deg C, heating to about 2200 to 2400 deg C within about 15 minutes while outgassing at a high volume throughput, and thereafter carburizing the niobium. (AEC)

  10. NGNP Graphite Selection and Acquisition Strategy

    SciTech Connect

    Burchell, T.; Bratton, R.; Windes, W.

    2007-09-30

    The nuclear graphite (H-451) previously used in the United States for High-Temperature Reactors (HTRs) is no longer available. New graphites have been developed and are considered suitable candidates for the Next-Generation Nuclear Plant (NGNP). A complete properties database for these new, available, candidate grades of graphite must be developed to support the design and licensing of NGNP core components. Data are required for the physical, mechanical (including radiation-induced creep), and oxidation properties of graphites. Moreover, the data must be statistically sound and take account of in-billet, between billets, and lot-to-lot variations of properties. These data are needed to support the ongoing development1 of the risk-derived American Society of Mechanical Engineers (ASME) graphite design code (a consensus code being prepared under the jurisdiction of the ASME by gas-cooled reactor and NGNP stakeholders including the vendors). The earlier Fort St. Vrain design of High-Temperature Reactor (HTRs) used deterministic performance models for H-451, while the NGNP will use new graphite grades and risk-derived (probabilistic) performance models and design codes, such as that being developed by the ASME. A radiation effects database must be developed for the currently available graphite materials, and this requires a substantial graphite irradiation program. The graphite Technology Development Plan (TDP)2 describes the data needed and the experiments planned to acquire these data in a timely fashion to support NGNP design, construction, and licensing. The strategy for the selection of appropriate grades of graphite for the NGNP is discussed here. The final selection of graphite grades depends upon the chosen reactor type and vendor because the reactor type (pebble bed or prismatic block) has a major influence on the graphite chosen by the designer. However, the time required to obtain the needed irradiation data for the selected NGNP graphite is sufficiently

  11. Nickel coated graphite fiber conductive composites

    SciTech Connect

    Evans, R.E.; Hall, D.E.; Luxon, B.A.

    1986-07-01

    Nickel coated graphite (NCG) fiber, consisting of a thin continuous plating of high purity nickel over an aerospace-grade graphite core, offers performance added features by combining the lightweight and high structural reinforcement of graphite fiber with the thermal and electrical conductivity of nickel. These NCG filaments, which are composite constructions in their own right, can be processed and impregnated with thermosetting or thermoplastic resins in the same manner that graphite fiber tows are processed and impregnated to produce roving, tape or fabric prepreg. Therefore, NCG fibers can be readily integrated into structural laminate assemblies using established composites-manufacturing practices.

  12. Nanostructured carbon films with oriented graphitic planes

    SciTech Connect

    Teo, E. H. T.; Kalish, R.; Kulik, J.; Kauffmann, Y.; Lifshitz, Y.

    2011-03-21

    Nanostructured carbon films with oriented graphitic planes can be deposited by applying energetic carbon bombardment. The present work shows the possibility of structuring graphitic planes perpendicular to the substrate in following two distinct ways: (i) applying sufficiently large carbon energies for deposition at room temperature (E>10 keV), (ii) utilizing much lower energies for deposition at elevated substrate temperatures (T>200 deg. C). High resolution transmission electron microscopy is used to probe the graphitic planes. The alignment achieved at elevated temperatures does not depend on the deposition angle. The data provides insight into the mechanisms leading to the growth of oriented graphitic planes under different conditions.

  13. Filler bar heating due to stepped tiles in the shuttle orbiter thermal protection system

    NASA Technical Reports Server (NTRS)

    Petley, D. H.; Smith, D. M.; Edwards, C. L. W.; Patten, A. B.; Hamilton, H. H., II

    1983-01-01

    An analytical study was performed to investigate the excessive heating in the tile to tile gaps of the Shuttle Orbiter Thermal Protection System due to stepped tiles. The excessive heating was evidence by visible discoloration and charring of the filler bar and strain isolation pad that is used in the attachment of tiles to the aluminum substrate. Two tile locations on the Shuttle orbiter were considered, one on the lower surface of the fuselage and one on the lower surface of the wing. The gap heating analysis involved the calculation of external and internal gas pressures and temperatures, internal mass flow rates, and the transient thermal response of the thermal protection system. The results of the analysis are presented for the fuselage and wing location for several step heights. The results of a study to determine the effectiveness of a half height ceramic fiber gap filler in preventing hot gas flow in the tile gaps are also presented.

  14. CAD Tools for Creating Space-filing 3D Escher Tiles

    SciTech Connect

    Howison, Mark; Sequin, Carlo H.

    2009-04-10

    We discuss the design and implementation of CAD tools for creating decorative solids that tile 3-space in a regular, isohedral manner. Starting with the simplest case of extruded 2D tilings, we describe geometric algorithms used for maintaining boundary representations of 3D tiles, including a Java implementation of an interactive constrained Delaunay triangulation library and a mesh-cutting algorithm used in layering extruded tiles to create more intricate designs. Finally, we demonstrate a CAD tool for creating 3D tilings that are derived from cubic lattices. The design process for these 3D tiles is more constrained, and hence more difficult, than in the 2D case, and it raises additional user interface issues.

  15. Retrosynthetic Analysis-Guided Breaking Tile Symmetry for the Assembly of Complex DNA Nanostructures.

    PubMed

    Wang, Pengfei; Wu, Siyu; Tian, Cheng; Yu, Guimei; Jiang, Wen; Wang, Guansong; Mao, Chengde

    2016-10-11

    Current tile-based DNA self-assembly produces simple repetitive or highly symmetric structures. In the case of 2D lattices, the unit cell often contains only one basic tile because the tiles often are symmetric (in terms of either the backbone or the sequence). In this work, we have applied retrosynthetic analysis to determine the minimal asymmetric units for complex DNA nanostructures. Such analysis guides us to break the intrinsic structural symmetries of the tiles to achieve high structural complexities. This strategy has led to the construction of several DNA nanostructures that are not accessible from conventional symmetric tile designs. Along with previous studies, herein we have established a set of four fundamental rules regarding tile-based assembly. Such rules could serve as guidelines for the design of DNA nanostructures.

  16. Stereodynamics of the reactions: F + H2/HD/HT→FH + H/D/T

    NASA Astrophysics Data System (ADS)

    Chi, Xiao-Lin; Zhao, Jin-Feng; Zhang, Yong-Jia; Ma, Feng-Cai; Li, Yong-Qing

    2015-05-01

    Among many kinds of ways to study the properties of atom and molecule collision, the quasi-classical trajectory (QCT) method is an effective one to investigate the molecular reaction dynamics. QCT calculations have been carried out to investigate the stereodynamics of the reactions F + H2/HD/HT→FH + H/D/T, which proceed on the lowest-lying electronic states of the FH2 system based on the potential energy surface (PES) of the 12A’ FH2 ground state. Although the QCT method cannot describe all quantum effects in the process of the reaction, it has unique advantages when facing a three-atoms system or complicated polyatomic systems. Differential cross sections (DCSs) and three angle distribution functions P(θr), P(ϕr), P(θr, ϕr) on the PES at the collision of 2.74 kcal/mol have been investigated. The isotope effect becomes more obvious with the reagent molecule H2 turning into HD and HT. P(θr, ϕr), as the joint probability density function of both polar angles θr and ϕr, can reflect the properties of three-dimensional dynamic more intuitively. Project supported by the National Natural Science Foundation of China (Grant No. 11474141), the Scientific Research Foundation for the Returned Overseas Chinese Scholars (Grant No. 2014-1685), the Scientific Research Foundation for the Doctor of Liaoning University, the Special Fund Based Research New Technology of Methanol Conversion and Coal Instead of Oil, and the China Postdoctoral Science Foundation (Grant No. 2014M550158).

  17. Sawtooth mixing of alpha particles in TFTR D-T plasmas

    SciTech Connect

    Petrov, M.P.; Budny, R.V.; Chang, Z.

    1996-12-31

    Radially resolved confined alpha particle energy and density distributions are routinely measured on TFTR using two diagnostics: PCX and {alpha}-CHERS. The Pellet Charge-eXchange (PCX) diagnostic uses the ablation cloud formed by an impurity pellet (Li or B) for neutralization of the alphas followed by analysis of the escaping helium neutrals. PCX detects deeply trapped alpha particles in the energy range 0.5 - 3.8 MeV. The {alpha}-CHERS technique, were the alpha signal is excited by charge-exchange between alphas and the deuterium atoms of one of the heating beams and appears as a wing on the He{sup +} 468.6 nm line, detects mainly passing alphas in the range of 0.15 - 0.7 MeV. Studies of alpha losses during DT experiments on TFTR have also been conducted using lost alpha detectors located on the walls of the plasma chamber. All of these diagnostics were used for investigating the influence of sawtooth crashes on alphas in high power D-T discharges in TFTR. Both PCX and {alpha}-CHERS measurements show a strong depletion of the alpha core density and transport of trapped alphas radially outwards well beyond q = 1 surface after a sawtooth crash. Lost alpha detectors measure bursts of alpha loss of the previously confined alphas (<1%). Thus, a sawtooth crash leads mainly to radial redistribution of the alphas rather than losses. For modeling of alpha sawtooth mixing, a code is used which is based on the conventional model of magnetic reconnection and the conservation of particles, energy and magnetic flux. The effect of the particle orbit averaged toroidal drift in a perturbed helical electric field generated by the crash has also been included in the code. It is shown that mixing of the passing alphas is dominated by the magnetic reconnection whereas trapped alphas are affected mainly by ExB drift.

  18. Numerical investigation of the spatial scale and time dependency of tile drainage contribution to stream flow

    NASA Astrophysics Data System (ADS)

    Thomas, Nicholas W.; Arenas, Antonio A.; Schilling, Keith E.; Weber, Larry J.

    2016-07-01

    Tile drainage systems are pervasive in the Central U.S., significantly altering the hydrologic system. The purpose of this study was to assess the effects of tile drainage systems on streamflow. A physically based coupled hydrologic model was applied to a 45 km2 agricultural Iowa watershed. Tile drainage was incorporated though an equivalent porous medium approach, calibrated though numerical experimentation. Experimental results indicated that a significant increase in hydraulic conductivity of the equivalent medium layer was needed to achieve agreement in total outflow with an explicit numerical representation of a tiled system. Watershed scale analysis derived the tile drainage contribution to stream flow (QT/Q) from a numerical tracer driven analysis of instream surface water. During precipitation events tile drainage represented 30% of stream flow, whereas during intervals between precipitations events, 61% of stream flow originated from the tile system. A division of event and non-event periods produced strong correlations between QT/Q and drainage area, positive for events, and negative for non-events. The addition of precipitation into the system acted to saturate near surface soils, increase lateral soil water movement, and dilute the relatively stable instream tile flow. Increased intensity precipitation translated the QT/Q relationship downward in a consistent manner. In non-event durations, flat upland areas contributed large contributions of tile flow, diluted by larger groundwater (non-tile) contribution to stream flow in the downstream steeper portion of the watershed. Study results provide new insights on the spatiotemporal response of tile drainage to precipitation and contributions of tile drainage to streamflow at a watershed scale, with results having important implications for nitrate transport.

  19. Radiation hardness of 3HF-tile/O2-WLS-fiber calorimeter

    SciTech Connect

    Han, S.W.; Hu, L.D.; Liu, N.Z.

    1993-11-01

    The radiation hardness of a 3HF-tile/O2-WLS-fiber calorimeter with two different tile/fiber patterns has been studied. Two calorimeter modules were irradiated up to 10 Mrad with the BEPC 1.3 GeV electron beam. The radiation damage of these modules is compared with our previous measurements from SCSN81-tile/BCF91A-WLS-fiber modules. The longitudinal damage profiles are fitted as a function of depth.

  20. Graphitized-carbon fiber/carbon char fuel

    SciTech Connect

    Cooper, John F.

    2007-08-28

    A method for recovery of intact graphitic fibers from fiber/polymer composites is described. The method comprises first pyrolyzing the graphite fiber/polymer composite mixture and then separating the graphite fibers by molten salt electrochemical oxidation.

  1. Investigating Interaction between Science and Design & Technology (D&T) in the Secondary School--A Case Study Approach

    ERIC Educational Resources Information Center

    Lewis, Tim; Barlex, David; Chapman, Colin

    2007-01-01

    Interaction between science and design and technology (D&T) in schools is seen by many educationalists and industrialists as being desirable. During the period 1970 to 1990 progress was made in the UK, however the advent of the national curriculum compartmentalised subjects thus hindering further progress. Bodies in the UK such as the Office…

  2. Excision of DNA segments introduced into cloning vectors by the poly(dA-dT) joining method.

    PubMed Central

    Goff, S P; Berg, P

    1978-01-01

    A method is described for excising cloned DNA segments that have been inserted into their vectors by poly(dA-dT) joins. The recombinant DNA is cleaved within the vector DNA portion by one or more restriction endonucleases to generate a linear DNA molecule with the insert DNA sequence flanked by the poly(dA-dT) joins. After denaturation, the single strands "snap back" because of the intrastrand poly(dA) and poly(dT) sequences to form circular structures with "tails" of vector DNA. The vector portion of the DNA is then digested by Escherichia coli exonuclease VII, while the insert portion remains resistant to attack. The resistant strands are annealed and purified by electrophoresis in agarose. The insert DNA segment free of contaminating vector sequences can be used as a hybridization probe and for insertion into a new vector since suitable cohesive termini are generated from the retained poly(dA) and poly(dT) tails by an appropriate exonuclease. Images PMID:347445

  3. Nonrigid registration of dynamic medical imaging data using nD + t B-splines and a groupwise optimization approach.

    PubMed

    Metz, C T; Klein, S; Schaap, M; van Walsum, T; Niessen, W J

    2011-04-01

    A registration method for motion estimation in dynamic medical imaging data is proposed. Registration is performed directly on the dynamic image, thus avoiding a bias towards a specifically chosen reference time point. Both spatial and temporal smoothness of the transformations are taken into account. Optionally, cyclic motion can be imposed, which can be useful for visualization (viewing the segmentation sequentially) or model building purposes. The method is based on a 3D (2D+time) or 4D (3D+time) free-form B-spline deformation model, a similarity metric that minimizes the intensity variances over time and constrained optimization using a stochastic gradient descent method with adaptive step size estimation. The method was quantitatively compared with existing registration techniques on synthetic data and 3D+t computed tomography data of the lungs. This showed subvoxel accuracy while delivering smooth transformations, and high consistency of the registration results. Furthermore, the accuracy of semi-automatic derivation of left ventricular volume curves from 3D+t computed tomography angiography data of the heart was evaluated. On average, the deviation from the curves derived from the manual annotations was approximately 3%. The potential of the method for other imaging modalities was shown on 2D+t ultrasound and 2D+t magnetic resonance images. The software is publicly available as an extension to the registration package elastix.

  4. Deuterium pumping speed measurements on 77 K cryopanels and implications for D-T retention in neutral beam systems

    SciTech Connect

    Dylla, H.F.

    1988-11-01

    An upper limit for the pumping speed of deuterium on 77 K surfaces has been determined by in-situ pressure measurements in a TFTR neutral beam line pumped by 423 m/sup 2/ of LN/sub 2/-cooled cryopanels. The measurement has importance for estimating the tritium retention in the beam line following operation of the ion sources with tritium. No D/sub 2/ pumping was observed. An upper limit for D/sub 2/ pumping on 77 K surfaces of less than or equal to2.4 x 10/sup -7/ l/s cm/sup 2/ was determined, corresponding to a D/sub 2/ sticking coefficient of less than or equal to1.5 x 10/sup -8/. Based on the upper limit a D-T retention factor, equal to the ratio of retained D-T to D-T input, has been determined to be less than or equal to5 x 10/sup -3/. This upper limit for D-T retention bounds the tritium inventory within the beam line to a small fraction of the tritium throughput. Comparably small upper limits for hydrogenic sticking coefficients, of the order of 10/sup -6/ - 10/sup -10/, have been determined from a review of H/sub 2/O cryotrapping measurements at 77 K and from the physical adsorption studies of H/sub 2/ on H/sub 2/O at 4 K. 22 refs., 5 figs., 1 tab.

  5. Aperiodic compression and reconstruction of real-world material systems based on Wang tiles

    NASA Astrophysics Data System (ADS)

    Doškář, Martin; Novák, Jan; Zeman, Jan

    2014-12-01

    The paper presents a concept to compress and synthesize complex material morphologies that is based on Wang tilings. Specifically, a microstructure is stored in a set of Wang tiles and its reconstruction is performed by means of a stochastic tiling algorithm. A substantial part of the study is devoted to the setup of optimal parameters of the automatic tile design by means of parametric studies with statistical descriptors at heart. The performance of the method is demonstrated on four two-dimensional two-phase target systems, monodisperse media with hard and soft disks, sandstone, and high porosity metallic foam.

  6. Microwave energy versus convected hot air for rapidly drying ceramic tile

    SciTech Connect

    Earl, D.A.

    1995-12-31

    The purpose of this study was to determine if microwave energy could provide advantages over the conventional hot air method currently used for rapidly drying ceramic tile. Tiles consisting of a typical fast-fire body formula were dried to 0.5% moisture using a 2.45 GHz, 950W microwave oven and a natural gas-fired roller dryer. Statistical methods were employed to develop equations for predicting microwave energy consumption, tile % moisture and surface temperature given drying time, tile volume and % relative humidity. Microwave drying was found to require 36% less energy than hot air drying. Moisture was removed and surface temperature elevated at faster rates using microwave energy.

  7. High Resolution Modeling of Tile-Drained Controls on Ecohydrologic Dynamics in Intensively Managed Landscapes.

    NASA Astrophysics Data System (ADS)

    Wagner, D.; Le, P. V.; Kumar, P.; Woo, D.

    2015-12-01

    Tile drains are widely used in the Midwestern United States to improve the productivity of poorly drained agricultural fields. Since tile drain reduces vadose zone soil moisture by lowering the water table, and its outlets feed directly into streams and ditches, tile flow can affect various hydrologic, biotic and biogeochemical processes in the watershed. However, the effects of tile flow on ecohydrologic and nutrient dynamics at scales dominated by microtopographic variability, such as depression and roadside ditches, remain poorly understood. Here we present an explicit model of tile flow and incorporate into the integrated ecohydrologic-flow model, MLCan-GCSFlow, to investigate the impacts of tile drain on ecohydrologic and nutrient dynamics in intensively managed agricultural fields at lidar-resolution scales. Explicit coupling between subsurface and tile flow is obtained by modifications of variably saturated Richards equation to capture the impacts of tile drain on soil moisture. The coupling between subsurface and overland flow is obtained by prescribing a boundary condition switching approach at the top surface of the computational domain. Model results for study sites in Critical Zone Observatory for Intensively Managed Landscapes (IMLCZO) show the significance of tile drain flow on the vertical and spatial soil moisture distribution and coupled surface - sub-surface flow dynamics.

  8. Tethers as Debris: Simulating Impacts of Tether Fragments on Shuttle Tiles

    NASA Technical Reports Server (NTRS)

    Evans, Steven W.

    2004-01-01

    The SPHC hydrodynamic code was used to simulate impacts of Kevlar and aluminum projectiles on a model of the LI-900 type insulating tiles used on Space Shuffle Orbiters The intent was to examine likely damage that such tiles might experience if impacted by orbital debris consisting of tether fragments. Projectile speeds ranged from 300 meters per second to 10 kilometers per second. Damage is characterized by penetration depth, tile surface-hole diameter, tile body-cavity diameter, coating fracture diameter, tether and cavity wall material phases, and deformation of the aluminum backwall.

  9. Self-assembly of fully addressable DNA nanostructures from double crossover tiles

    PubMed Central

    Wang, Wen; Lin, Tong; Zhang, Suoyu; Bai, Tanxi; Mi, Yongli; Wei, Bryan

    2016-01-01

    DNA origami and single-stranded tile (SST) are two proven approaches to self-assemble finite-size complex DNA nanostructures. The construction elements appeared in structures from these two methods can also be found in multi-stranded DNA tiles such as double crossover tiles. Here we report the design and observation of four types of finite-size lattices with four different double crossover tiles, respectively, which, we believe, in terms of both complexity and robustness, will be rival to DNA origami and SST structures. PMID:27484479

  10. Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Gong, Leslie; Quinn, Robert D.

    2004-01-01

    This report deals with hypothetical reentry thermostructural performance of the Space Shuttle orbiter with missing or eroded thermal protection system (TPS) tiles. The original STS-5 heating (normal transition at 1100 sec) and the modified STS-5 heating (premature transition at 800 sec) were used as reentry heat inputs. The TPS missing or eroded site is assumed to be located at the center or corner (spar-rib juncture) of the lower surface of wing midspan bay 3. For cases of missing TPS tiles, under the original STS-5 heating, the orbiter can afford to lose only one TPS tile at the center or two TPS tiles at the corner (spar-rib juncture) of the lower surface of wing midspan bay 3. Under modified STS-5 heating, the orbiter cannot afford to lose even one TPS tile at the center or at the corner of the lower surface of wing midspan bay 3. For cases of eroded TPS tiles, the aluminum skin temperature rises relatively slowly with the decreasing thickness of the eroded central or corner TPS tile until most of the TPS tile is eroded away, and then increases exponentially toward the missing tile case.

  11. Aperiodic compression and reconstruction of real-world material systems based on Wang tiles.

    PubMed

    Doškář, Martin; Novák, Jan; Zeman, Jan

    2014-12-01

    The paper presents a concept to compress and synthesize complex material morphologies that is based on Wang tilings. Specifically, a microstructure is stored in a set of Wang tiles and its reconstruction is performed by means of a stochastic tiling algorithm. A substantial part of the study is devoted to the setup of optimal parameters of the automatic tile design by means of parametric studies with statistical descriptors at heart. The performance of the method is demonstrated on four two-dimensional two-phase target systems, monodisperse media with hard and soft disks, sandstone, and high porosity metallic foam.

  12. Ceramic-ceramic shell tile thermal protection system and method thereof

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R. (Inventor); Smith, Marnell (Inventor); Goldstein, Howard E. (Inventor); Zimmerman, Norman B. (Inventor)

    1986-01-01

    A ceramic reusable, externally applied composite thermal protection system (TPS) is proposed. The system functions by utilizing a ceramic/ceramic upper shell structure which effectively separates its primary functions as a thermal insulator and as a load carrier to transmit loads to the cold structure. The composite tile system also prevents impact damage to the atmospheric entry vehicle thermal protection system. The composite tile comprises a structurally strong upper ceramic/ceramic shell manufactured from ceramic fibers and ceramic matrix meeting the thermal and structural requirements of a tile used on a re-entry aerospace vehicle. In addition, a lightweight high temperature ceramic lower temperature base tile is used. The upper shell and lower tile are attached by means effective to withstand the extreme temperatures (3000 to 3200F) and stress conditions. The composite tile may include one or more layers of variable density rigid or flexible thermal insulation. The assembly of the overall tile is facilitated by two or more locking mechanisms on opposing sides of the overall tile assembly. The assembly may occur subsequent to the installation of the lower shell tile on the spacecraft structural skin.

  13. The action of macrosounds on graphite ore and derived products

    NASA Technical Reports Server (NTRS)

    Bradeteanu, C.; Dragan, O.

    1974-01-01

    A suspension of graphite ore, floated graphite, and the gangue left over from flotation were subjected to the action of macrosounds under determinant conditions. The following was found: (1) The graphite ore undergoes an efficient settling action. (2) The floated graphite is strongly crushed down to the dimensions of colloidal graphite. (3) The gangue left over from flotation can be further processed to recuperate graphite from its nuclei.

  14. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.; Jones, R. J.; Vaughan, R. W.

    1972-01-01

    High temperature resin matrices suitable for use in advanced graphite fiber composites for jet engine applications were evaluated. A series of planned, sequential screening experiments with resin systems in composite form were performed to reduce the number of candidates to a single A-type polyimide resin that repetitively produced void-free, high strength and modulus composites acceptable for use in the 550 F range for 1000 hours. An optimized processing procedure was established for this system. Extensive mechanical property studies characterized this single system, at room temperature, 500 F, 550 F and 600 F, for various exposure times.

  15. Synthetic Metals from Intercalated Graphite.

    DTIC Science & Technology

    1985-09-30

    34, L. Salamanca- Riba and M.S. Dres- selhaus, Carbon, (in press) (1986). 16. "High Resolution Transmission Electron Microscopy on KH.-GICs", L. Salaman...ca- Riba , N.C. Yeh, M.S. Dresselhaus, M. Endo and T. Enoki, J. of Mat. Res. (in press) (1986). 11 04 -.4* 17. "Electron Beam Induced Damage and...Structure of SbCl5 Graphite Intercalation Compounds", L. Salamanca- Riba , G. Roth, J.M. Gibson, A.R. Kortan, G. Dresselhaus and - R.J. Birgeneau, Phys. Rev

  16. Effect of graphite surface structure on initial irreversible reaction in graphite anodes

    SciTech Connect

    Suzuki, Kimihito; Hamada, Takeshi; Sugiura, Tsutomu

    1999-03-01

    The initial irreversible reaction that occurs in graphite anodes during the first lithium intercalation in lithium rechargeable batteries was studied in view of graphite surface structure. Graphitized mesophase spheres and pitch-based carbon fibers, which show low irreversible capacity, were shown to have turbostatic surface regions and highly graphitized cores using Ar-ion laser Raman spectroscopy. Burning off these surface regions resulted in remarkable increases of initial irreversible capacity. Those results can be explained by a proposed model that a turbostatic structure of the graphite surface region resists drastic swelling of interlayer spaces arising from cointercalation of solvated ions and depresses the side reaction.

  17. Analysis of Wigner energy release process in graphite stack of shut-down uranium-graphite reactor

    NASA Astrophysics Data System (ADS)

    Bespala, E. V.; Pavliuk, A. O.; Kotlyarevskiy, S. G.

    2015-10-01

    Data, which finding during thermal differential analysis of sampled irradiated graphite are presented. Results of computational modeling of Winger energy release process from irradiated graphite staking are demonstrated. It's shown, that spontaneous combustion of graphite possible only in adiabatic case.

  18. Assembly of a tile-based multilayered DNA nanostructure

    NASA Astrophysics Data System (ADS)

    Son, Junyoung; Lee, Junywe; Tandon, Anshula; Kim, Byeonghoon; Yoo, Sanghyun; Lee, Chang-Won; Park, Sung Ha

    2015-04-01

    The Watson-Crick complementarity of DNA is exploited to construct periodically patterned nanostructures, and we herein demonstrate tile-based three dimensional (3D) multilayered DNA nanostructures that incorporate two design strategies: vertical growth and horizontal layer stacking with substrate-assisted growth. To this end, we have designed a periodically holed double-double crossover (DDX) template that can be used to examine the growth of the multilayer structures in both the vertical and horizontal directions. For vertical growth, the traditional 2D double crossover (DX) DNA lattice is seeded and grown vertically from periodic holes in the DDX template. For horizontal stacking, the DDX layers are stacked by binding the connector tiles between each layer. Although both types of multilayers exhibited successful formation, the observations with an atomic force microscope indicated that the DDX layer growth achieved with the horizontal stacking approach could be considered to be slightly better relative to the vertical growth of the DX layers in terms of uniformity, layer size, and discreteness. In particular, the newly designed DDX template layer provided a parallel arrangement between each domain with substrate-assisted growth. This kind of layer arrangement suggests a possibility of using our design scheme in the construction of other periodic structures.The Watson-Crick complementarity of DNA is exploited to construct periodically patterned nanostructures, and we herein demonstrate tile-based three dimensional (3D) multilayered DNA nanostructures that incorporate two design strategies: vertical growth and horizontal layer stacking with substrate-assisted growth. To this end, we have designed a periodically holed double-double crossover (DDX) template that can be used to examine the growth of the multilayer structures in both the vertical and horizontal directions. For vertical growth, the traditional 2D double crossover (DX) DNA lattice is seeded and grown

  19. Inhibition of Oxidation in Nuclear Graphite

    SciTech Connect

    Phil Winston; James W. Sterbentz; William E. Windes

    2013-10-01

    Graphite is a fundamental material of high temperature gas cooled nuclear reactors, providing both structure and neutron moderation. Its high thermal conductivity, chemical inertness, thermal heat capacity, and high thermal structural stability under normal and off normal conditions contribute to the inherent safety of these reactor designs. One of the primary safety issues for a high temperature graphite reactor core is the possibility of rapid oxidation of the carbon structure during an off normal design basis event where an oxidizing atmosphere (air ingress) can be introduced to the hot core. Although the current Generation IV high temperature reactor designs attempt to mitigate any damage caused by a postualed air ingress event, the use of graphite components that inhibit oxidation is a logical step to increase the safety of these reactors. Recent experimental studies of graphite containing between 5.5 and 7 wt% boron carbide (B4C) indicate that oxidation is dramatically reduced even at prolonged exposures at temperatures up to 900°C. The proposed addition of B4C to graphite components in the nuclear core would necessarily be enriched in B-11 isotope in order to minimize B-10 neutron absorption and graphite swelling. The enriched boron can be added to the graphite during billet fabrication. Experimental oxidation rate results and potential applications for borated graphite in nuclear reactor components will be discussed.

  20. Mineral Resource of the Month: Graphite

    USGS Publications Warehouse

    Olson, Donald W.

    2008-01-01

    Graphite, a grayish black opaque mineral with a metallic luster, is one of four forms of pure crystalline carbon (the others are carbon nanotubes, diamonds and fullerenes). It is one of the softest minerals and it exhibits perfect basal (one-plane) cleavage. Graphite is the most electrically and thermally conductive of the nonmetals, and it is chemically inert.

  1. Tire containing thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2011-01-01

    A tire, tire lining or inner tube, containing a polymer composite, made of at least one rubber and/or at least one elastomer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g.

  2. Scintillating tile/fiber calorimetry development at FNAL

    NASA Astrophysics Data System (ADS)

    Foster, G. W.; Freeman, J.; Hagstrom, R.

    1991-07-01

    The technique of calorimetry using scintillating tiles with waveshifting fibers imbedded in them for readout has been refined for use in SSC test calorimeters and for the CDF Endplug upgrade. The technique offers high light yield, good spatial uniformity, flexible readout mechanics and a very small "readout crack". Various production techniques have been developed and optimized, including control and correction of scintillator plate uniformity, techniques for splicing plastic fibers with low light losses, and laser-cutting of the groove in which the fiber is placed.

  3. Shake table testing of structural clay tile infilled frames

    SciTech Connect

    Bennett, R.M.; Fowler, J.J.; Flanagan, R.D.

    1996-03-08

    Two steel frames with structural clay tile infills were tested under simulated seismic loads in both the out-of-plane and in-plane direction. Out-of-plane testing showed that infill panels separate from their bounding frame, and respond at their own natural frequency during a seismic excitation. Due to arching, the panels remain stable. In-plane seismic testing showed similar behavior patterns to previous static testing. The natural frequency was adequately predicted using a piecewise linear equivalent strut analytical method. The structure was then subjected to over one thousand cycles of loading using a sine sweep before failure.

  4. Modelling the viscoelasticity of ceramic tiles by finite element

    NASA Astrophysics Data System (ADS)

    Pavlovic, Ana; Fragassa, Cristiano

    2016-05-01

    This research details a numerical method aiming at investigating the viscoelastic behaviour of a specific family of ceramic material, the Grès Porcelain, during an uncommon transformation, known as pyroplasticity, which occurs when a ceramic tile bends under a combination of thermal stress and own weight. In general, the theory of viscoelasticity can be considered extremely large and precise, but its application on real cases is particularly delicate. A time-depending problem, as viscoelasticity naturally is, has to be merged with a temperature-depending situation. This paper investigates how the viscoelastic response of bending ceramic materials can be modelled by commercial Finite Elements codes.

  5. Hydrogen storage in graphite nanofibers

    SciTech Connect

    Park, C.; Tan, C.D.; Hidalgo, R.; Baker, R.T.K.; Rodriguez, N.M.

    1998-08-01

    Graphite nanofibers (GNF) are a type of material that is produced by the decomposition of carbon containing gases over metal catalyst particles at temperatures around 600 C. These molecularly engineered structures consist of graphene sheets perfectly arranged in a parallel, perpendicular or at angle orientation with respect to the fiber axis. The most important feature of the material is that only edges are exposed. Such an arrangement imparts the material with unique properties for gas adsorption because the evenly separated layers constitute the most ordered set of nanopores that can accommodate an adsorbate in the most efficient manner. In addition, the non-rigid pore walls can also expand so as to accommodate hydrogen in a multilayer conformation. Of the many varieties of structures that can be produced the authors have discovered that when gram quantities of a selected number of GNF are exposed to hydrogen at pressures of {approximately} 2,000 psi, they are capable of adsorbing and storing up to 40 wt% of hydrogen. It is believed that a strong interaction is established between hydrogen and the delocalized p-electrons present in the graphite layers and therefore a new type of chemistry is occurring within these confined structures.

  6. SIMPLIFIED SODIUM GRAPHITE REACTOR SYSTEM

    DOEpatents

    Dickinson, R.W.

    1963-03-01

    This patent relates to a nuclear power reactor comprising a reactor vessel, shielding means positioned at the top of said vessel, means sealing said reactor vessel to said shielding means, said vessel containing a quantity of sodium, a core tank, unclad graphite moderator disposed in said tank, means including a plurality of process tubes traversing said tank for isolating said graphite from said sodium, fuel elements positioned in said process tubes, said core tank being supported in spaced relation to the walls and bottom of said reactor vessel and below the level of said sodium, neutron shielding means positioned adjacent said core tank between said core tank and the walls of said vessel, said neutron shielding means defining an annuiar volume adjacent the inside wall of said reactor vessel, inlet plenum means below said core tank for providing a passage between said annular volume and said process tubes, heat exchanger means removably supported from the first-named shielding means and positioned in said annular volume, and means for circulating said sodium over said neutron shielding means down through said heat exchanger, across said inlet plenum and upward through said process tubes, said last-named means including electromagnetic pumps located outside said vessel and supported on said vessel wall between said heat exchanger means and said inlet plenum means. (AEC)

  7. Status of Graphite Oxidation Work

    SciTech Connect

    Rebecca Smith

    2010-05-01

    Data were developed to compare the extent of structural damage associated with high temperature exposure to an air leak. Two materials, NBG-18 graphite and unpurified PCEA graphite have been tested as of this report. The scope was limited to isothermal oxidation at a single temperature, 750°C. Ambient post-oxidation compression strength testing was performed for three levels of burn off (1%, 5%, and 10% mass loss) for two leak scenarios: 100% air and 10% air in helium. Temperature, gas flow, and dynamic mass loss oxidation conditions were monitored and recorded for each sample. The oxidation period was controlled with flow of inert gas during the thermal ramp and upon cool down with a constant 10 liter per minute flow maintained throughout furnace operation. Compressive strengths of parallel un-oxidized samples were tested to assess the relative mass loss effects. In addition to baseline samples matching the un-oxidized dimensions of the oxidized samples, two sets of mechanically reduced samples were prepared. One set was trimmed to achieve the desired mass loss by removing an effectively uniform depth from the geometric surface of the sample. The other set was cored to produce a full penetration axial hole down the center of each sample.

  8. Development of polyphenylquinoxaline graphite composites

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.; Hill, S. G.; Shdo, J. G.

    1974-01-01

    This exploratory program was divided into four basic tasks. The initial phase was devoted toward investigating processing variables associated with previously developed PPO resins. These polymers were derived from p-bis(phenyl glyoxalyl)benzene reacted with 3,3'-diamino benzidine and/or 3,3',4,4'-tetramino benzophenone. Four new phenyl quinoxaline polymers were synthesized and characterized in Tasks 2 and 3. These consisted of a hydroxyl group containing PPQ synthesized from 3,3'-diamino benzidine (DAB), m-bis(phenyl glyoxal)benzene and m-bis(p'-hydroxy phenyl glyoxalyl) benzene; a cyano group containing PPQ from the reaction of DAB and p-bis(p'-cyano phenoxy phenyl glyoxalyl)benzene; an end-capped block copolymer; and a polymer from the reaction of 3,3',4,4'-tetraamino benzo phenone and m-bis(phenyl glyoxalyl)benzene. The latter two polymers were chosen for composite studies in the latter two tasks of the program. Mechanical properties of the graphite reinforced PPQ composites were determined over the temperature range of +21 C to 316 C. Flexural strengths of the HMS graphite fiber composites were in excess of 8.97 X 10 to the 8th power N/sq m (130,000 psi) at +21 C (70 F) with over 50% strength retention at +316 C.

  9. Microstructural Characterization of Next Generation Nuclear Graphites

    SciTech Connect

    Karthik Chinnathambi; Joshua Kane; Darryl P. Butt; William E. Windes; Rick Ubic

    2012-04-01

    This article reports the microstructural characteristics of various petroleum and pitch based nuclear graphites (IG-110, NBG-18, and PCEA) that are of interest to the next generation nuclear plant program. Bright-field transmission electron microscopy imaging was used to identify and understand the different features constituting the microstructure of nuclear graphite such as the filler particles, microcracks, binder phase, rosette-shaped quinoline insoluble (QI) particles, chaotic structures, and turbostratic graphite phase. The dimensions of microcracks were found to vary from a few nanometers to tens of microns. Furthermore, the microcracks were found to be filled with amorphous carbon of unknown origin. The pitch coke based graphite (NBG-18) was found to contain higher concentration of binder phase constituting QI particles as well as chaotic structures. The turbostratic graphite, present in all of the grades, was identified through their elliptical diffraction patterns. The difference in the microstructure has been analyzed in view of their processing conditions.

  10. Fiber release characteristics of graphite hybrid composites

    NASA Technical Reports Server (NTRS)

    Henshaw, J.

    1980-01-01

    The paper considers different material concepts that can be fabricated of hybridized composites which demonstrate improved graphite fiber retention capability in a severe fire without significant reduction to the composite properties. More than 30 panels were fabricated for mechanical and fire tests, the details and results of which are presented. Methods of composite hybridization investigated included the addition of oxidation resistant fillers to the resin, mechanically interlocking the graphite fibers by the use of woven fabrics, and the addition of glass fibers and glass additives designed to melt and fuse the graphite fibers together. It is concluded that a woven fabric with a serving of glass around each graphite tow is by far the superior of those evaluated: not only is there a coalescing effect in each graphite layer, but there is also a definite adhesion of each layer to its neighbor.

  11. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.; Thompson, E. R.

    1978-01-01

    A composite that can be used at temperatures up to 875 K with mechanical properties equal or superior to graphite fiber reinforced epoxy composites is presented. The composite system consist of graphite fiber, uniaxially or biaxially, reinforced borosilicate glass. The mechanical and thermal properties of such a graphite fiber reinforced glass composite are described, and the system is shown to offer promise as a high performance structural material. Specific properties that were measured were: a modified borosilicate glass uniaxially reinforced by Hercules HMS graphite fiber has a three-point flexural strength of 1030 MPa, a four-point flexural strength of 964 MPa, an elastic modulus of 199 GPa and a failure strain of 0.0052. The preparation and properties of similar composites with Hercules HTS, Celanese DG-102, Thornel 300 and Thornel Pitch graphite fibers are also described.

  12. Structure of different grades of nuclear graphite

    NASA Astrophysics Data System (ADS)

    Mironov, B. E.; Westwood, A. V. K.; Scott, A. J.; Brydson, R.; Jones, A. N.

    2012-07-01

    Owing to its low neutron absorption cross-section, large scattering cross section and thermal and chemical stability, graphite is a key component of operational nuclear reactors where it is used as a moderator, reflector and as major structural component for 90% of current UK nuclear plants. It is also of interest for use in developing the future high temperature gas-cooled reactors. The properties of the nuclear graphite are influenced by its structural characteristics, which change as a function of neutron irradiation, temperature and oxidation. The principal structural changes during neutron irradiation that affect the integrity and dimensions of nuclear graphite components, thereby affecting service lifetime, are that the a-axis contracts and the c-axis expands in the crystallites. Characterization of virgin graphite structure and of the damage evolution after irradiation of nuclear graphite has an important role to play in the understanding and development of materials used in current and future nuclear reactors, respectively.

  13. Microstructural characterization of next generation nuclear graphites.

    PubMed

    Karthik, Chinnathambi; Kane, Joshua; Butt, Darryl P; Windes, William E; Ubic, Rick

    2012-04-01

    This article reports the microstructural characteristics of various petroleum and pitch based nuclear graphites (IG-110, NBG-18, and PCEA) that are of interest to the next generation nuclear plant program. Bright-field transmission electron microscopy imaging was used to identify and understand the different features constituting the microstructure of nuclear graphite such as the filler particles, microcracks, binder phase, rosette-shaped quinoline insoluble (QI) particles, chaotic structures, and turbostratic graphite phase. The dimensions of microcracks were found to vary from a few nanometers to tens of microns. Furthermore, the microcracks were found to be filled with amorphous carbon of unknown origin. The pitch coke based graphite (NBG-18) was found to contain higher concentration of binder phase constituting QI particles as well as chaotic structures. The turbostratic graphite, present in all of the grades, was identified through their elliptical diffraction patterns. The difference in the microstructure has been analyzed in view of their processing conditions.

  14. Model experiments of superlubricity of graphite

    NASA Astrophysics Data System (ADS)

    Dienwiebel, Martin; Pradeep, Namboodiri; Verhoeven, Gertjan S.; Zandbergen, Henny W.; Frenken, Joost W. M.

    2005-02-01

    Graphite is known to be a good solid lubricant. The low-friction behavior is traditionally ascribed to the low resistance to shear. We have recently observed that the ultra-low friction found in friction force microscopy experiments on graphite is due to a effect called superlubricity [M. Dienwiebel, G. S. Verhoeven, N. Pradeep, J.W.M. Frenken, J.A. Heimberg, H.W. Zandbergen, Phys. Rev. Lett. 92 (2004) 126101]. Here, we provide additional experimental evidence that superlubricity has been taken place between a small graphite flake attached to the scanning tip and the graphite surface. Finally, we speculate about the significance of this for the lubricating properties of graphite.

  15. New family of tilings of three-dimensional Euclidean space by tetrahedra and octahedra.

    PubMed

    Conway, John H; Jiao, Yang; Torquato, Salvatore

    2011-07-05

    It is well known that two regular tetrahedra can be combined with a single regular octahedron to tile (complete fill) three-dimensional Euclidean space . This structure was called the "octet truss" by Buckminster Fuller. It was believed that such a tiling, which is the Delaunay tessellation of the face-centered cubic (fcc) lattice, and its closely related stacking variants, are the only tessellations of that involve two different regular polyhedra. Here we identify and analyze a unique family comprised of a noncountably infinite number of periodic tilings of whose smallest repeat tiling unit consists of one regular octahedron and six smaller regular tetrahedra. We first derive an extreme member of this unique tiling family by showing that the "holes" in the optimal lattice packing of octahedra, obtained by Minkowski over a century ago, are congruent tetrahedra. This tiling has 694 distinct concave (i.e., nonconvex) repeat units, 24 of which possess central symmetry, and hence is distinctly different and combinatorically richer than the fcc tetrahedra-octahedra tiling, which only has two distinct tiling units. Then we construct a one-parameter family of octahedron packings that continuously spans from the fcc to the optimal lattice packing of octahedra. We show that the "holes" in these packings, except for the two extreme cases, are tetrahedra of two sizes, leading to a family of periodic tilings with units composed four small tetrahedra and two large tetrahedra that contact an octahedron. These tilings generally possess 2,068 distinct concave tiling units, 62 of which are centrally symmetric.

  16. A Global User-Driven Model for Tile Prefetching in Web Geographical Information Systems

    PubMed Central

    Pan, Shaoming; Chong, Yanwen; Zhang, Hang; Tan, Xicheng

    2017-01-01

    A web geographical information system is a typical service-intensive application. Tile prefetching and cache replacement can improve cache hit ratios by proactively fetching tiles from storage and replacing the appropriate tiles from the high-speed cache buffer without waiting for a client’s requests, which reduces disk latency and improves system access performance. Most popular prefetching strategies consider only the relative tile popularities to predict which tile should be prefetched or consider only a single individual user's access behavior to determine which neighbor tiles need to be prefetched. Some studies show that comprehensively considering all users’ access behaviors and all tiles’ relationships in the prediction process can achieve more significant improvements. Thus, this work proposes a new global user-driven model for tile prefetching and cache replacement. First, based on all users’ access behaviors, a type of expression method for tile correlation is designed and implemented. Then, a conditional prefetching probability can be computed based on the proposed correlation expression mode. Thus, some tiles to be prefetched can be found by computing and comparing the conditional prefetching probability from the uncached tiles set and, similarly, some replacement tiles can be found in the cache buffer according to multi-step prefetching. Finally, some experiments are provided comparing the proposed model with other global user-driven models, other single user-driven models, and other client-side prefetching strategies. The results show that the proposed model can achieve a prefetching hit rate in approximately 10.6% ~ 110.5% higher than the compared methods. PMID:28085937

  17. New family of tilings of three-dimensional Euclidean space by tetrahedra and octahedra

    PubMed Central

    Conway, John H.; Jiao, Yang; Torquato, Salvatore

    2011-01-01

    It is well known that two regular tetrahedra can be combined with a single regular octahedron to tile (complete fill) three-dimensional Euclidean space . This structure was called the “octet truss” by Buckminster Fuller. It was believed that such a tiling, which is the Delaunay tessellation of the face-centered cubic (fcc) lattice, and its closely related stacking variants, are the only tessellations of that involve two different regular polyhedra. Here we identify and analyze a unique family comprised of a noncountably infinite number of periodic tilings of whose smallest repeat tiling unit consists of one regular octahedron and six smaller regular tetrahedra. We first derive an extreme member of this unique tiling family by showing that the “holes” in the optimal lattice packing of octahedra, obtained by Minkowski over a century ago, are congruent tetrahedra. This tiling has 694 distinct concave (i.e., nonconvex) repeat units, 24 of which possess central symmetry, and hence is distinctly different and combinatorically richer than the fcc tetrahedra-octahedra tiling, which only has two distinct tiling units. Then we construct a one-parameter family of octahedron packings that continuously spans from the fcc to the optimal lattice packing of octahedra. We show that the “holes” in these packings, except for the two extreme cases, are tetrahedra of two sizes, leading to a family of periodic tilings with units composed four small tetrahedra and two large tetrahedra that contact an octahedron. These tilings generally possess 2,068 distinct concave tiling units, 62 of which are centrally symmetric. PMID:21690370

  18. AGC-2 Graphite Preirradiation Data Analysis Report

    SciTech Connect

    William Windes; W. David Swank; David Rohrbaugh; Joseph Lord

    2013-08-01

    This report described the specimen loading order and documents all pre-irradiation examination material property measurement data for the graphite specimens contained within the second Advanced Graphite Capsule (AGC-2) irradiation capsule. The AGC-2 capsule is the second in six planned irradiation capsules comprising the Advanced Graphite Creep (AGC) test series. The AGC test series is used to irradiate graphite specimens allowing quantitative data necessary for predicting the irradiation behavior and operating performance of new nuclear graphite grades to be generated which will ascertain the in-service behavior of the graphite for pebble bed and prismatic Very High Temperature Reactor (VHTR) designs. Similar to the AGC-1 specimen pre-irradiation examination report, material property tests were conducted on specimens from 18 nuclear graphite types but on an increased number of specimens (512) prior to loading into the AGC-2 irradiation assembly. All AGC-2 specimen testing was conducted at Idaho National Laboratory (INL) from October 2009 to August 2010. This report also details the specimen loading methodology for the graphite specimens inside the AGC-2 irradiation capsule. The AGC-2 capsule design requires “matched pair” creep specimens that have similar dose levels above and below the neutron flux profile mid-plane to provide similar specimens with and without an applied load. This document utilized the neutron flux profile calculated for the AGC-2 capsule design, the capsule dimensions, and the size (length) of the selected graphite and silicon carbide samples to create a stacking order that can produce “matched pairs” of graphite samples above and below the AGC-2 capsule elevation mid-point to provide specimens with similar neutron dose levels.

  19. Modeling Fission Product Sorption in Graphite Structures

    SciTech Connect

    Szlufarska, Izabela; Morgan, Dane; Allen, Todd

    2013-04-08

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission

  20. Modelleing the Multiaxial Strength of Nuclear Graphite

    SciTech Connect

    Burchell, Timothy D; Yahr, Terry; Battiste, Rick

    2006-01-01

    The core of a prismatic High Temperature Reactor (HTR) is constructed from an array of nuclear graphite components including replaceable fuel blocks, replaceable and permanent moderator blocks, and core support posts. Similarly, the core of a Pebble Bed Reactor is confined by large graphite blocks which define the (annular) core geometry. In both HTR designs (prismatic and pebble bed) the large graphite components act as neutron moderator and reflector as well as providing mechanical support to the active core. During reactor operation the graphite components of the core are subjected to complex stress states arising from structural loads, thermal gradients, neutron irradiation damage, and seismic events. Structural design of HTR cores requires that the designer have a suitable theory of failure. Both deterministic (e.g. maximum principal stress theory) and probabilistic (e.g., Weibull failure theory) have been considered as candidates. To test candidate theories a multiaxial testing program was conducted at Oak Ridge National Laboratory on grade H-451 graphite, the fuel element and moderator graphite used in the Fort St. Vrain high temperature reactor in the USA. Large test specimens ({approx}27 cm length) were subjected to combined axial stress (both tension and compression) and internal pressure. A total of 59 specimens were tested at 9 stress ratios in the first and fourth stress quadrants. In a parallel effort a physically based fracture model of graphite was developed. The model used a fracture mechanics based failure criteria and has been shown to predict the tensile failure probability of several graphites of widely ranging texture. Here we report the basis and performance of the fracture model and multiaxial strength data for grade H-451 graphite. Moreover, we report the successful extension of the model to predict the failure envelope for H-451 graphite in the first and fourth multiaxial quadrants. The model's predictions are compared to experimental

  1. Close-up of Shuttle Thermal Tiles in Space

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Launched on July 26, 2005 from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes (CMGs). STS-114 also carried the Raffaello Multi-Purpose Logistics Module and the External Stowage Platform-2. A major focus of the mission was the testing and evaluation of new Space Shuttle flight safety, which included new inspection and repair techniques. Upon its approach to the International Space Station (ISS), the Space Shuttle Discovery underwent a photography session in order to assess any damages that may have occurred during its launch and/or journey through Space. The mission's third and final Extra Vehicular Activity (EVA) included taking a close-up look and the repair of the damaged heat shield. Gap fillers were removed from between the orbiter's heat-shielding tiles located on the craft's underbelly. Never before had any repairs been done to an orbiter while still in space. This particular photo was taken by astronaut Stephen K. Robinson, STS-114 mission specialist, whose shadow is visible on the thermal protection tiles, and a portion of the Canadian built Remote Manipulator System (RMS) robotic arm and the Nile River is visible at the bottom.

  2. Tiling analysis of melting in strongly-coupled dusty plasma*

    NASA Astrophysics Data System (ADS)

    Suranga Ruhunusiri, W. D.; Feng, Yan; Liu, Bin; Goree, John

    2010-11-01

    A dusty plasma is an ionized gas containing micron-size particles of solid matter, which collect electrons and ions and become negatively charged. Due to large Coulomb interparticle potential energies, the microparticles represent a strongly-coupled plasma. In the absence of an external disturbance, the microparticles self-organize, arranging themselves in a crystalline lattice, due to their Coulomb interaction. If kinetic energy is added, the arrangement of microparticles becomes disordered, like atoms in a liquid. This melting process can be characterized by a proliferation of defects, which previous experimenters measured using Voronoi analysis. Here we use another method, tiling [1] to quantify defects. We demonstrate this method, which until now has been used only in simulations, in a dusty plasma experiment. A single layer of 4.83 μm polymer microparticles was electrically levitated in a glow discharge argon plasma. The lattice was melted by applying random kicks to the micoparticles from rastered laser beams. We imaged the particle positions and computed the corresponding tiling for both the crystalline lattice and liquid states. [1] Matthew A. Glaser, Phys. Rev A 41, 4585 (1990) ^*Work supported by NSF and NASA.

  3. Close-up of Shuttle Thermal Tiles in Space

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Launched on July 26 2005, from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes (CMGs). STS-114 also carried the Raffaello Multi-Purpose Logistics Module and the External Stowage Platform-2. A major focus of the mission was the testing and evaluation of new Space Shuttle flight safety, which included new inspection and repair techniques. Upon its approach to the International Space Station (ISS), the Space Shuttle Discovery underwent a photography session in order to assess any damages that may have occurred during its launch and/or journey through Space. The mission's third and final Extra Vehicular Activity (EVA) included taking a close-up look and the repair of the damaged heat shield. Gap fillers were removed from between the orbiter's heat-shielding tiles located on the craft's underbelly. Never before had any repairs been done to an orbiter while still in space. This close up of the thermal tiles was taken by astronaut Stephen K. Robinson, STS-114 mission specialist (out of frame). Astronaut Soichi Noguchi, STS-114 mission specialist representing the Japan Aerospace Exploration (JAXA), can be seen in the background perched on a Space Station truss.

  4. Space Shuttle Communications Coverage Analysis for Thermal Tile Inspection

    NASA Technical Reports Server (NTRS)

    Kroll, Quin D.; Hwu, Shian U.; Upanavage, Matthew; Boster, John P.; Chavez, Mark A.

    2009-01-01

    The space shuttle ultra-high frequency Space-to-Space Communication System has to provide adequate communication coverage for astronauts who are performing thermal tile inspection and repair on the underside of the space shuttle orbiter (SSO). Careful planning and quantitative assessment are necessary to ensure successful system operations and mission safety in this work environment. This study assesses communication systems performance for astronauts who are working in the underside, non-line-of-sight shadow region on the space shuttle. All of the space shuttle and International Space Station (ISS) transmitting antennas are blocked by the SSO structure. To ensure communication coverage at planned inspection worksites, the signal strength and link margin between the SSO/ISS antennas and the extravehicular activity astronauts, whose line-of-sight is blocked by vehicle structure, was analyzed. Investigations were performed using rigorous computational electromagnetic modeling techniques. Signal strength was obtained by computing the reflected and diffracted fields along the signal propagation paths between transmitting and receiving antennas. Radio frequency (RF) coverage was determined for thermal tile inspection and repair missions using the results of this computation. Analysis results from this paper are important in formulating the limits on reliable communication range and RF coverage at planned underside inspection and repair worksites.

  5. Self-Replication of Nanoscale tiles and patterns

    NASA Astrophysics Data System (ADS)

    Chaikin, Paul

    2012-02-01

    We want to make a ``non-biological'' system which can self-replicate. The idea is to design particles with specific and reversible and irreversible interactions, introduce seed motifs, and cycle the system in such a way that a copy is made. Repeating the cycle would double the number of offspring in each generation leading to exponential growth. Using the chemistry of DNA either on colloids or on DNA tiles makes the specific recognition part easy. In the case of DNA tiles we have in fact replicated the seed at least to the third generation. The DNA linkers can also be self-protected so that particles don't interact unless they are held together for sufficient time -- a nano-contact glue. Chemical modification of the DNA allows us to permanently crosslink hybridized strands for irreversible bonds and a new type of photolithography. We have also designed and produced colloidal particles that use novel ``lock and key'' geometries to get specific and reversible physical interactions.[4pt] With Tong Wang, Ruojie Sha, Remi Dreyfus, Mirjam E. Leunissen, Corinna Maass, David J. Pine, and Nadrian C. Seeman.

  6. Baseline Graphite Initial Mechanical Test Report

    SciTech Connect

    Mark Carroll; Randy Lloyd

    2009-09-01

    The Next Generation Nuclear Plant (NGNP) Project is tasked with selecting a high temperature gas reactor technology that will be capable of generating electricity and supplying large amounts of process heat. The NGNP is presently being designed as a helium-cooled high temperature gas reactor (HTGR) with a large graphite core. The graphite baseline characterization project is conducting the research and development (R&D) activities deemed necessary to fully qualify nuclear-grade graphite for use in the NGNP reactor. One of the major fundamental objectives of the project is establishing nonirradiated thermomechanical and thermophysical properties by characterizing lot-to-lot and billet-to-billet variations (for probabilistic baseline data needs) through extensive data collection and statistical analysis. The reactor core will be made up of stacks of graphite moderator blocks. In order to gain a more comprehensive understanding of the varying characteristics in a wide range of suitable graphites, any of which can be classified as “nuclear grade,” an experimental program has been initiated to develop an extensive database of the baseline characteristics of numerous candidate graphites. Various factors known to affect the properties of graphite will be investigated, including specimen size, spatial location within a graphite billet, specimen orientation within a billet (either parallel to [P] or transverse to [T] the long axis of the as-produced billet), and billet-to-billet variations within a lot or across different production lots. Because each data point is based on a certain position within a given billet of graphite, particular attention must be paid to the traceability of each specimen and its spatial location and orientation within each billet. The evaluation of these properties is discussed in the Graphite Technology Development Plan (Windes et. al 2007). One of the key components in the evaluation of these graphite types will be mechanical testing of

  7. 40 CFR 427.70 - Applicability; description of the asbestos floor tile subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... asbestos floor tile subcategory. 427.70 Section 427.70 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ASBESTOS MANUFACTURING POINT SOURCE CATEGORY Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor...

  8. 40 CFR 427.70 - Applicability; description of the asbestos floor tile subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... asbestos floor tile subcategory. 427.70 Section 427.70 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ASBESTOS MANUFACTURING POINT SOURCE CATEGORY Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor...

  9. 40 CFR 427.70 - Applicability; description of the asbestos floor tile subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... asbestos floor tile subcategory. 427.70 Section 427.70 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ASBESTOS MANUFACTURING POINT SOURCE CATEGORY Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor...

  10. Effect of surface inlet type on suspended sediment transported through a subsurface drain tile system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Throughout the Prairie Pothole Region, subsurface tile and surface inlets are used to remove water from low-lying or poorly-drained soils. Open inlets are being increasingly converted to buried inlets in which perforated tile is placed in a trench of rock (i.e., a French drain) and buried below a la...

  11. Preferential flow estimates to an agricultural tile drain with implications for glyphosate transport

    USGS Publications Warehouse

    Stone, W.W.; Wilson, J.T.

    2006-01-01

    Agricultural subsurface drains, commonly referred to as tile drains, are potentially significant pathways for the movement of fertilizers and pesticides to streams and ditches in much of the Midwest. Preferential flow in the unsaturated zone provides a route for water and solutes to bypass the soil matrix and reach tile drains faster than predicted by traditional displacement theory. This paper uses chloride concentrations to estimate preferential flow contributions to a tile drain during two storms in May 2004. Chloride, a conservative anion, was selected as the tracer because of differences in chloride concentrations between the two sources of water to the tile drain, preferential and matrix flow. A strong correlation between specific conductance and chloride concentration provided a mechanism to estimate chloride concentrations in the tile drain throughout the storm hydrographs. A simple mixing analysis was used to identify the preferential flow component of the storm hydrograph. During two storms, preferential flow contributed 11 and 51% of total storm tile drain flow; the peak contributions, 40 and 81%, coincided with the peak tile drain flow. Positive relations between glyphosate [N-(phosphonomethyl)glycine] concentrations and preferential flow for the two storms suggest that preferential flow is an important transport pathway to the tile drain. ?? ASA, CSSA, SSSA.

  12. A Scintillator tile-fiber preshower detector for the CDF Central Calorimeter

    SciTech Connect

    S. Lami

    2004-08-12

    The front face of the CDF central calorimeter is being equipped with a new Preshower detector, based on scintillator tiles read out by WLS fibers. A light yield of about 40 pe/MIP at the tile exit was obtained, exceeding the design requirements.

  13. Supporting Students' Understanding of Linear Equations with One Variable Using Algebra Tiles

    ERIC Educational Resources Information Center

    Saraswati, Sari; Putri, Ratu Ilma Indra; Somakim

    2016-01-01

    This research aimed to describe how algebra tiles can support students' understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students…

  14. Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter

    NASA Technical Reports Server (NTRS)

    Belknap, Shannon; Zhang, Michael

    2013-01-01

    The 3D Automated Thermal Tool for Damaged Acreage Tile Math Model builder was developed to perform quickly and accurately 3D thermal analyses on damaged lower surface acreage tiles and structures beneath the damaged locations on a Space Shuttle Orbiter. The 3D model builder created both TRASYS geometric math models (GMMs) and SINDA thermal math models (TMMs) to simulate an idealized damaged cavity in the damaged tile(s). The GMMs are processed in TRASYS to generate radiation conductors between the surfaces in the cavity. The radiation conductors are inserted into the TMMs, which are processed in SINDA to generate temperature histories for all of the nodes on each layer of the TMM. The invention allows a thermal analyst to create quickly and accurately a 3D model of a damaged lower surface tile on the orbiter. The 3D model builder can generate a GMM and the correspond ing TMM in one or two minutes, with the damaged cavity included in the tile material. A separate program creates a configuration file, which would take a couple of minutes to edit. This configuration file is read by the model builder program to determine the location of the damage, the correct tile type, tile thickness, structure thickness, and SIP thickness of the damage, so that the model builder program can build an accurate model at the specified location. Once the models are built, they are processed by the TRASYS and SINDA.

  15. Effect of strain isolator pad modulus on inplane strain in Shuttle Orbiter thermal protection system tiles

    NASA Technical Reports Server (NTRS)

    Sawyer, J. W.

    1983-01-01

    The thermal protection system used on the Space Shuttle orbiter to determine strains in the reusable surface insulation tiles under simulated flight loads was investigated. The effects of changes in the strain isolator pad (SIP) moduli on the strains in the tile were evaluated. To analyze the SIP/tile system, it was necessary to conduct tests to determine inplane tension and compression modulus and inplane failure strain for the densified layer of the tiles. It is shown that densification of the LI-900 tile material increases the modulus by a factor of 6 to 10 and reduces the failure strain by about 50%. It is indicated that the inplane strain levels in the Shuttle tiles in the highly loaded regions are approximately 2 orders of magnitude lower than the failure strain of the material. It is concluded that most of the LI-900 tiles on the Shuttle could be mounted on a SIP with tensile and shear stiffnesses 10 times those of the present SIP without inplane strain failure in the tile.

  16. A simple model for predicting solute concentration in agricultural tile lines shortly after application

    NASA Astrophysics Data System (ADS)

    Steenhuis, T. S.; Bodnar, M.; Geohring, L. D.; Aburime, S.-A.; Wallach, R.

    Agricultural tile drainage lines have been implicated as a source of pesticide contamination of surface waters. Field experiments were conducted and a simple model was developed to examine preferential transport of applied chemicals to agricultural tile lines. The conceptual model consists of two linear reservoirs, one near the soil surface and one near the tile drain. The connection between the two reservoirs is via preferential flow paths with very little interaction with the soil matrix. The model assumes that only part of the field contributes solutes to the tile drain. The model was evaluated with data from the field experiments in which chloride, 2,4-D, and atrazine concentrations were measured on eight tile-drained plots that were irrigated twice. Atrazine was applied two months prior to the experiment, 2,4-D was sprayed just before the first irrigation, and chloride before the second irrigation. All three chemicals were found in the tile effluent shortly after the rainfall began. Generally, the concentration increased with increased flow rates and decreased exponentially after the rainfall ceased. Although the simple model could simulate the observed chloride concentration patterns in the tile outflow for six of the eight plots, strict validation was not possible because of the difficulty with independent measurement of the data needed for a preferential flow model applied to field conditions. The results show that, to simulate pesticide concentration in tile lines, methods that can measure field averaged preferential flow characteristics need to be developed.

  17. A technique for brazing graphite/graphite and stainless steel/high-carbon steel joints

    SciTech Connect

    Ohmura, H.; Kawashiri, K. . Dept. of Metals and Inorganic Materials); Yoshida, T. . Vehicle Machine Engineering Dept.); Yoshimoto, O. . Quality Control Dept.)

    1994-10-01

    A new brazing technique for joining graphite to itself or to metals such as Mo, W, or Cu, with conventional brazing filler metals has been developed. Essentially, it is impossible to braze graphite with Cu filler metal because no wetting occurs. However, when a graphite base material is combined with an Fe base metal in Cu brazing, the Fe base metal dissolves in molten Cu. Simultaneously, the dissolved Fe grows as part of a columnar Fe-9 [approximately] 6Cu-1.6C alloy phase at the graphite interface at a constant brazing temperature, that is, the dissolution and deposit of base metal takes place. By placing an Fe foil insert between both graphite base materials, therefore, the columnar phase is formed at both graphite faces and grows toward the Fe foil during heating. As a result, both graphite base materials are united by the columnar phase through the Fe foil. In the same way, a graphite/Mo or /W joint can be produced. Moreover, when using BAu-1, which has a lower melting point than that of BCu-1, it is also possible to braze graphite to Cu. The shear strength of a graphite/graphite joint with a 0.12-mm thick Fe foil at room temperature was about 32 MPa. Further, the bending strength of the graphite/graphite and /Cu joints at 873 K (1,112 F), as measured using the four-point bending test, was 35 and 11 MPa, respectively. In addition, the technique can be applied to the brazing of AISI 304 stainless steel to high-C steel with BCu-1 where, normally, Cr[sub 23]C[sub 6] and Cr[sub 7]C[sub 3] layers are formed at the high-C steel braze interface; these carbide layers result in the loss of mechanical properties of the joint.

  18. Positive feedback fishery: Population consequences of `crab-tiling' on the green crab Carcinus maenas

    NASA Astrophysics Data System (ADS)

    Sheehan, E. V.; Thompson, R. C.; Coleman, R. A.; Attrill, M. J.

    2008-11-01

    Collection of marine invertebrates for use as fishing bait is a substantial activity in many parts of the world, often with unknown ecological consequences. As new fisheries develop, it is critical for environmental managers to have high quality ecological information regarding the potential impacts, in order to develop sound management strategies. Crab-tiling is a largely unregulated and un-researched fishery, which operates commercially in the south-west UK. The target species is the green crab Carcinus maenas. Those crabs which are pre-ecdysis and have a carapace width greater than 40 mm are collected to be sold to recreational anglers as bait. Collection involves laying artificial structures on intertidal sandflats and mudflats in estuaries. Crabs use these structures as refugia and are collected during low tide. However, the effect that this fishery has on populations of C. maenas is not known. The impact of crab-tiling on C. maenas population structure was determined by sampling crabs from tiled estuaries and non-tiled estuaries using baited drop-nets. A spatially and temporarily replicated, balanced design was used to compare crab abundance, sizes and sex ratios between estuaries. Typically, fisheries are associated with a reduction in the abundance of the target species. Crab-tiling, however, significantly increased C. maenas abundance. This was thought to be a result of the extra habitat in tiled estuaries, which probably provides protection from natural predators, such as birds and fish. Although crabs were more abundant in tiled estuaries than non-tiled estuaries, the overall percentage of reproductively active crabs in non-tiled estuaries was greater than in tiled estuaries. As with most exploited fisheries stocks, crabs in exploited (tiled) estuaries tended to be smaller, with a modal carapace width of 20-29 mm rather than 30-39 mm in non-tiled estuaries. The sex ratio of crabs however; was not significantly different between tiled and non-tiled

  19. Experimental Investigation of Muon-catalyzed dt Fusion in Wide Ranges of D/T Mixture Conditions

    SciTech Connect

    Bom, V.R.; Eijk, C.W.E. van; Demin, A.M.; Golubkov, A.N.; Grishechkin, S.K.; Klevtsov, V.G.; Kuryakin, A.V.; Musyaev, R.K.; Perevozchikov, V.V.; Vinogradov, Yu.I.; Yukhimchuk, A.A.; Zlatoustovskii, S.V.; Demin, D.L.; Filchenkov, V.V.; Grafov, N.N.; Gritsaj, K.I.; Konin, A.D.; Medved', S.V.; Rudenko, A.I.; Yukhimchuk, S.A.

    2005-04-01

    A vast program of the experimental investigation of muon-catalyzed dt fusion was performed on the Joint Institute for Nuclear Research phasotron. Parameters of the dt cycle were obtained in a wide range of the D/T mixture conditions: temperatures of 20-800 K, densities of 0.2-1.2 of the liquid hydrogen density (LHD), and tritium concentrations of 15-86%. In this paper, the results obtained are summarized.

  20. Terahertz NDE Application for Corrosion Detection and Evaluation under Shuttle Tiles

    NASA Technical Reports Server (NTRS)

    Anastasi, Robert F.; Madaras, Eric I.; Seebo, Jeffrey P.; Smith, Stephen W.; Lomness, Janice K.; Hintze, Paul E.; Kammerer, Catherine C.; Winfree, William P.; Russell, Richard W.

    2007-01-01

    Pulsed Terahertz NDE is being examined as a method to inspect for possible corrosion under Space Shuttle Tiles. Other methods such as ultrasonics, infrared, eddy current and microwave technologies have demonstrable shortcomings for tile NDE. This work applies Terahertz NDE, in the frequency range between 50 GHz and 1 THz, for the inspection of manufactured corrosion samples. The samples consist of induced corrosion spots that range in diameter (2.54 to 15.2 mm) and depth (0.036 to 0.787 mm) in an aluminum substrate material covered with tiles. Results of these measurements are presented for known corrosion flaws both covered and uncovered and for blind tests with unknown corrosion flaws covered with attached tiles. The Terahertz NDE system is shown to detect all artificially manufactured corrosion regions under a Shuttle tile with a depth greater than 0.13 mm.

  1. Porosity detection in ceramic armor tiles via ultrasonic time-of-flight

    SciTech Connect

    Margetan, Frank J.; Richter, Nathaniel; Jensen, Terrence

    2011-06-23

    Some multilayer armor panels contain ceramic tiles as one constituent, and porosity in the tiles can affect armor performance. It is well known that porosity in ceramic materials leads to a decrease in ultrasonic velocity. We report on a feasibility study exploring the use of ultrasonic time-of-flight (TOF) to locate and characterize porous regions in armor tiles. The tiles in question typically have well-controlled thickness, thus simplifying the translation of TOF data into velocity data. By combining UT velocity measurements and X-ray absorption measurements on selected specimens, one can construct a calibration curve relating velocity to porosity. That relationship can then be used to translate typical ultrasonic C-scans of TOF-versus-position into C-scans of porosity-versus-position. This procedure is demonstrated for pulse/echo, focused-transducer inspections of silicon carbide (SiC) ceramic tiles.

  2. Advanced Modeling Strategies for the Analysis of Tile-Reinforced Composite Armor

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Chen, Tzi-Kang

    1999-01-01

    A detailed investigation of the deformation mechanisms in tile-reinforced armored components was conducted to develop the most efficient modeling strategies for the structural analysis of large components of the Composite Armored Vehicle. The limitations of conventional finite elements with respect to the analysis of tile-reinforced structures were examined, and two complementary optimal modeling strategies were developed. These strategies are element layering and the use of a tile-adhesive superelement. Element layering is a technique that uses stacks of shear deformable shell elements to obtain the proper transverse shear distributions through the thickness of the laminate. The tile-adhesive superelement consists of a statically condensed substructure model designed to take advantage of periodicity in tile placement patterns to eliminate numerical redundancies in the analysis. Both approaches can be used simultaneously to create unusually efficient models that accurately predict the global response by incorporating the correct local deformation mechanisms.

  3. Fractal spectral triples on Kellendonk's C∗-algebra of a substitution tiling

    NASA Astrophysics Data System (ADS)

    Mampusti, Michael; Whittaker, Michael F.

    2017-02-01

    We introduce a new class of noncommutative spectral triples on Kellendonk's C∗-algebra associated with a nonperiodic substitution tiling. These spectral triples are constructed from fractal trees on tilings, which define a geodesic distance between any two tiles in the tiling. Since fractals typically have infinite Euclidean length, the geodesic distance is defined using Perron-Frobenius theory, and is self-similar with scaling factor given by the Perron-Frobenius eigenvalue. We show that each spectral triple is θ-summable, and respects the hierarchy of the substitution system. To elucidate our results, we construct a fractal tree on the Penrose tiling, and explicitly show how it gives rise to a collection of spectral triples.

  4. THE NEXT GENERATION NUCLEAR PLANT GRAPHITE PROGRAM

    SciTech Connect

    William E. Windes; Timothy D. Burchell; Robert L. Bratton

    2008-09-01

    Developing new nuclear grades of graphite used in the core of a High Temperature Gas-cooled Reactor (HTGR) is one of the critical development activities being pursued within the Next Generation Nuclear Plant (NGNP) program. Graphite’s thermal stability (in an inert gas environment), high compressive strength, fabricability, and cost effective price make it an ideal core structural material for the HTGR reactor design. While the general characteristics necessary for producing nuclear grade graphite are understood, historical “nuclear” grades no longer exist. New grades must be fabricated, characterized, and irradiated to demonstrate that current grades of graphite exhibit acceptable non-irradiated and irradiated properties upon which the thermo-mechanical design of the structural graphite in NGNP is based. The NGNP graphite R&D program has selected a handful of commercially available types for research and development activities necessary to qualify this nuclear grade graphite for use within the NGNP reactor. These activities fall within five primary areas; 1) material property characterization, 2) irradiated material property characterization, 3) modeling, and 4) ASTM test development, and 5) ASME code development efforts. Individual research and development activities within each area are being pursued with the ultimate goal of obtaining a commercial operating license for the nuclear graphite from the US NRC.

  5. Brazed graphite/refractory metal composites for first-wall protection elements

    NASA Astrophysics Data System (ADS)

    Šmid, I.; Croessmann, C. D.; Salmonson, J. C.; Whitley, J. B.; Kny, E.; Reheis, N.; Kneringer, G.; Nickel, H.

    1991-03-01

    The peak surface heat flux deposition on divertor elements of near term fusion devices is expected to exceed 10 MW/m 2. The needed reliability of brazed plasma interactive components, particularly under abnormal operating conditions with peak surface temperatures well beyond 1000°C, makes refractory metallic substrates and brazes with a high melting point very attractive. TZM, a high temperature alloy of molybdenum, and isotropic graphite, materials very closely matched in their thermal expansion, were brazed with four high-temperature brazes. The brazes used were Zr, 90Ni/10Ti, 90Cu/10Ti and 70Ag/27Cu/3Ti (nominal composition prior to brazing, wt%). The resulting composite tiles of 50 × 50 mm2 with a TZM thickness of 5 mm and a graphite thickness of 10 mm have been tested in high heat flux simulation for their thermal fatigue properties. Up to 600 loading cycles were carried out with an average heat flux of 10 MW/m 2 for 0.5 s pulses. The maximum surface temperature was 1100°C. In support of the experiment, the thermal response and temperature gradients of the samples were investigated using a finite element model.

  6. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.

    1974-01-01

    Processing techniques were developed for the fabrication of both polyphenylquinoxaline and polyimide composites by the in situ polymerization of monomeric reactants directly on the graphite reinforcing fibers, rather than using previously prepared prepolymer varnishes. Void-free polyphenylquinoxaline composites were fabricated and evaluated for room and elevated flexure and shear properties. The technology of the polyimide system was advanced to the point where the material is ready for commercial exploitation. A reproducible processing cycle free of operator judgment factors was developed for fabrication of void-free composites exhibiting excellent mechanical properties and a long time isothermal life in the range of 288 C to 316 C. The effects of monomer reactant stoichiometry and process modification on resin flow were investigated. Demonstration of the utility and quality of this polyimide system was provided through the successful fabrication and evaluation of four complex high tip speed fan blades.

  7. Superconductivity in graphite intercalation compounds

    DOE PAGES

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; ...

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic statesmore » and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.« less

  8. Superconductivity in graphite intercalation compounds

    SciTech Connect

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P. M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  9. Development of polyphenylquinoxaline graphite composites

    NASA Technical Reports Server (NTRS)

    Shdo, J. D.

    1976-01-01

    Six polyphenylquinoxalines (PPQ) containing pendant cyano (CN) groups were synthesized. The polymers were characterized in terms of inherent viscosity, glass transition temperature, softening temperature and weight loss due to aging in air at 316 C (600 F). The potential for crosslinking PPQs by trimerization of pendant CN groups was investigated. A polymer derived from 1 mole 3,3,4,4 -tetraaminobenzophenone, .2 mole p-bis(p -cyanophenoxyphenylglyoxalyl)benzene and .8 mole p-bis(phenylglyoxalyl)benzene was selected for more extensive characterization in HM-S graphite fiber-reinforced composites. Mechanical properties were determined using composites made from HM-S fiber and polymer and composites made from HM-S fiber, polymer and a potential CN group trimerization catalyst. Composite mechanical properties, inter-laminar shear strength and flexure properties, were determined over the temperature range of +21 C to 316 C.

  10. Cryogenic distillation: a fuel enrichment system for near-term tokamak-type D-T fusion reactors

    SciTech Connect

    Misra, B.; Davis, J.F.

    1980-02-01

    The successful operation and economic viability of deuterium-tritium- (D-T-) fueled tokamak-type commercial power fusion reactors will depend to a large extent on the development of reliable tritium-containment and fuel-recycle systems. Of the many operating steps in the fuel recycle scheme, separation or enrichment of the isotropic species of hydrogen by cryogenic distillation is one of the most important. A parametric investigation was carried out to study the effects of the various operating conditions and the composition of the spent fuel on the degree of separation. A computer program was developed for the design and analysis of a system of interconnected distillation columns for isotopic separation such that the requirements of near-term D-T-fueled reactors are met. The analytical results show that a distillation cascade consisting of four columns is capable of reprocessing spent fuel varying over a wide range of compositions to yield reinjection-grade fuel with essentially unlimited D/T ratio.

  11. The characterization of fluorinated graphite

    SciTech Connect

    Hagaman, E.W.; Gakh, A.A.; Annis, B.K.

    1995-12-31

    The characterization of solid fossil fuels by chemical and spectroscopic methods requires extensive modelling in less complex systems for chemical proof of principle and technique development. In previous work coal was fluorinated with dilute, elemental fluorine under conditions that were expected to lead to materials that contain only fluoromethine moieties. The solid state, cross polarization/magic angle spinning (CP/MAS) {sup 13}C NMR spectra of the fluorinated coal are complex, indicating more chemical modification than originally anticipated. Our goal in the coal derivatization was to sequentially increase the severity of the fluorination and observe by {sup 19}F and {sup 13}C NMR the type and concentration of fluorine functional groups created in the coal milieu. This requires the ability to discriminate between C, CF, CF{sub 2}, and CF, moieties in the coal matrix. The task can be accomplished by implementing the spectral editing technique of Wu and Zilm which distinguishes different kinds of carbon resonances, especially CH and CH{sub 2} resonances. These experiments utilize cross polarization (CP) and polarization inversion (PI) to effect the discrimination. Our version of this experiment is a triple resonance experiment that incorporates {sup 19}F-{sup 13}C CP, PI, and simultaneous {sup 1}H and {sup 19}F dipolar decoupling. In order to evaluate the elemental fluorine chemistry in a matrix simpler than coal, fluorinated graphite was prepared. X-ray photoelectron spectroscopy (XPS) was used to characterize the surface species, i.e., count CF, CF{sub 2} and CF{sub 3} species. These well-characterized samples are the models we will use to test the NIVIR editing experiments. The XPS and atomic force microscopy (AFM) data on the first fluorinated graphites we have prepared are reported in this paper.

  12. Thermodynamics and Kinetics of DNA Tile-Based Self-Assembly

    NASA Astrophysics Data System (ADS)

    Jiang, Shuoxing

    Deoxyribonucleic acid (DNA) has emerged as an attractive building material for creating complex architectures at the nanometer scale that simultaneously affords versatility and modularity. Particularly, the programmability of DNA enables the assembly of basic building units into increasingly complex, arbitrary shapes or patterns. With the expanding complexity and functionality of DNA toolboxes, a quantitative understanding of DNA self-assembly in terms of thermodynamics and kinetics, will provide researchers with more subtle design guidelines that facilitate more precise spatial and temporal control. This dissertation focuses on studying the physicochemical properties of DNA tile-based self-assembly process by recapitulating representative scenarios and intermediate states with unique assembly pathways. First, DNA double-helical tiles with increasing flexibility were designed to investigate the dimerization kinetics. The higher dimerization rates of more rigid tiles result from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. Next, the thermodynamics and kinetics of single tile attachment to preformed "multitile" arrays were investigated to test the fundamental assumptions of tile assembly models. The results offer experimental evidences that double crossover tile attachment is determined by the electrostatic environment and the steric hindrance at the binding site. Finally, the assembly of double crossover tiles within a rhombic DNA origami frame was employed as the model system to investigate the competition between unseeded, facet and seeded nucleation. The results revealed that preference of nucleation types can be tuned by controlling the rate-limiting nucleation step. The works presented in this dissertation will be helpful for refining the DNA tile assembly model for future designs and simulations. Moreover, The works presented here could also be

  13. Nitrate and Pesticide Transport From Tile-Drained Fields in the Willamette Valley, Oregon

    NASA Astrophysics Data System (ADS)

    Warren, K. L.; Rupp, D. E.; Selker, J. S.; Dragila, M. I.; Peachey, R. E.

    2002-12-01

    Tile drainage affects the hydrology and thus the solute transport on agricultural fields by increasing the volume of water that drains from the subsurface. Previous NAWQA studies have shown elevated nitrate levels in wells and high detection frequencies for selected pesticides in Willamette Valley streams. As a substantial area of Willamette Valley agricultural land is tile-drained, it is important to determine the role of tile drains in surface water and ground water pollution. Four fields in the Willamette Valley were instrumented to monitor tile effluent for two winter seasons. On two fields, surface runoff was also monitored for the second season. Field areas ranged from 3 to 30 acres and were cropped in grass, corn, or a grass/corn rotation. Tile effluent nitrate concentrations frequently exceeded 10 ppm on some fields. Flow-weighted averages for each field were 0.87 ppm and 1.36 ppm for two established grass fields, and 8.1 ppm and 14.4 ppm for grass fields that had recently grown corn. Mass losses ranged from 1.15%-6.45% of the applied nitrate through the tile drains. Diuron, Metolachlor, and Chlorpyrifos were tested in selected surface runoff and tile effluent samples. On one field, Metolachlor concentrations were similar in the tile drains and surface runoff. Concentrations in both sources were 10 times lower than the drinking water advisory for Metolachlor. In a second field, Chlorpyrifos concentrations were two orders of magnitude lower than drinking water advisories in both sources. On the same field, Diuron concentrations were significantly higher in the surface runoff than in the tile effluent. Diuron concentrations were 1-2 orders of magnitude higher during the first precipitation events after application in the surface runoff. On a third field, Diuron was at least 10 times lower than drinking water advisories in the tile effluent, with the highest concentrations found in samples collected within 21 days of pesticide application.

  14. Method for molding threads in graphite panels

    DOEpatents

    Short, W.W.; Spencer, C.

    1994-11-29

    A graphite panel with a hole having a damaged thread is repaired by drilling the hole to remove all of the thread and making a new hole of larger diameter. A bolt with a lubricated thread is placed in the new hole and the hole is packed with graphite cement to fill the hole and the thread on the bolt. The graphite cement is cured, and the bolt is unscrewed therefrom to leave a thread in the cement which is at least as strong as that of the original thread. 8 figures.

  15. Method for molding threads in graphite panels

    DOEpatents

    Short, William W.; Spencer, Cecil

    1994-01-01

    A graphite panel (10) with a hole (11) having a damaged thread (12) is repaired by drilling the hole (11) to remove all of the thread and make a new hole (13) of larger diameter. A bolt (14) with a lubricated thread (17) is placed in the new hole (13) and the hole (13) is packed with graphite cement (16) to fill the hole and the thread on the bolt. The graphite cement (16) is cured, and the bolt is unscrewed therefrom to leave a thread (20) in the cement (16) which is at least as strong as that of the original thread (12).

  16. Graphite Fluoride Fiber Composites For Heat Sinking

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Long, Martin; Stahl, Mark

    1989-01-01

    Graphite fluoride fiber/polymer composite materials consist of graphite fluoride fibers in epoxy, polytetrafluoroethylene, or polyimide resin. Combines high electrical resistivity with high thermal conductivity and solves heat-transfer problems of many electrical systems. Commercially available in powder form, for use as dry lubricant or cathode material in lithium batteries. Produced by direct fluorination of graphite powder at temperature of 400 to 650 degree C. Applications include printed-circuit boards for high-density power electronics, insulators for magnetic-field cores like those found in alternators and transformers, substrates for thin-film resistors, and electrical-protection layers in aircraft de-icers.

  17. Synthesis of soluble graphite and graphene.

    PubMed

    Kelly, K F; Billups, W E

    2013-01-15

    Because of graphene's anticipated applications in electronics and its thermal, mechanical, and optical properties, many scientists and engineers are interested in this material. Graphene is an isolated layer of the π-stacked hexagonal allotrope of carbon known as graphite. The interlayer cohesive energy of graphite, or exfoliation energy, that results from van der Waals attractions over the interlayer spacing distance of 3.34 Å (61 meV/C atom) is many times weaker than the intralayer covalent bonding. Since graphene itself does not occur naturally, scientists and engineers are still learning how to isolate and manipulate individual layers of graphene. Some researchers have relied on the physical separation of the sheets, a process that can sometimes be as simple as peeling of sheets from crystalline graphite using Scotch tape. Other researchers have taken an ensemble approach, where they exploit the chemical conversion of graphite to the individual layers. The typical intermediary state is graphite oxide, which is often produced using strong oxidants under acidic conditions. Structurally, researchers hypothesize that acidic functional groups functionalize the oxidized material at the edges and a network of epoxy groups cover the sp(2)-bonded carbon network. The exfoliated material formed under these conditions can be used to form dispersions that are usually unstable. However, more importantly, irreversible defects form in the basal plane during oxidation and remain even after reduction of graphite oxide back to graphene-like material. As part of our interest in the dissolution of carbon nanomaterials, we have explored the derivatization of graphite following the same procedures that preserve the sp(2) bonding and the associated unique physical and electronic properties in the chemical processing of single-walled carbon nanotubes. In this Account, we describe efficient routes to exfoliate graphite either into graphitic nanoparticles or into graphene without

  18. Status of Chronic Oxidation Studies of Graphite

    SciTech Connect

    Contescu, Cristian I.; Mee, Robert W.

    2016-05-01

    Graphite will undergo extremely slow, but continuous oxidation by traces of moisture that will be present, albeit at very low levels, in the helium coolant of HTGR. This chronic oxidation may cause degradation of mechanical strength and thermal properties of graphite components if a porous oxidation layer penetrates deep enough in the bulk of graphite components during the lifetime of the reactor. The current research on graphite chronic oxidation is motivated by the acute need to understand the behavior of each graphite grade during prolonged exposure to high temperature chemical attack by moisture. The goal is to provide the elements needed to develop predictive models for long-time oxidation behavior of graphite components in the cooling helium of HTGR. The tasks derived from this goal are: (1) Oxidation rate measurements in order to determine and validate a comprehensive kinetic model suitable for prediction of intrinsic oxidation rates as a function of temperature and oxidant gas composition; (2) Characterization of effective diffusivity of water vapor in the graphite pore system in order to account for the in-pore transport of moisture; and (3) Development and validation of a predictive model for the penetration depth of the oxidized layer, in order to assess the risk of oxidation caused damage of particular graphite grades after prolonged exposure to the environment of helium coolant in HTGR. The most important and most time consuming of these tasks is the measurement of oxidation rates in accelerated oxidation tests (but still under kinetic control) and the development of a reliable kinetic model. This report summarizes the status of chronic oxidation studies on graphite, and then focuses on model development activities, progress of kinetic measurements, validation of results, and improvement of the kinetic models. Analysis of current and past results obtained with three grades of showed that the classical Langmuir-Hinshelwood model cannot reproduce all

  19. Adsorption of lead over graphite oxide.

    PubMed

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M; Oki, Aderemi

    2014-01-24

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption Spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb(2+) was found to be 98%, 91% and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water.

  20. High electrical resistivity carbon/graphite fibers

    NASA Technical Reports Server (NTRS)

    Vogel, F. L.; Forsman, W. C.

    1980-01-01

    Carbon/graphite fibers were chemically oxidized in the liquid phase to fibers of graphite oxide. Resistivity increases as high as 10,000 times were obtained, the oxidized fiber decomposed on exposure to atmosphere. A factor of 1,000 remained as a stable increment. The largest change observed was 1,000,000 times. Best results were obtained on the most highly graphitized fibers. Electrochemical oxidation yielded a lower increase--about 10 times, but provided a controllable method of synthesis and insight to the mechanism of reaction. Tensile tests indicated that the strength of the fiber on oxidation was decreased by no more than 25 percent.

  1. Self-Retracting Motion of Graphite Microflakes

    NASA Astrophysics Data System (ADS)

    Zheng, Quanshui; Jiang, Bo; Liu, Shoupeng; Weng, Yuxiang; Lu, Li; Xue, Qikun; Zhu, Jing; Jiang, Qing; Wang, Sheng; Peng, Lianmao

    2008-02-01

    We report the observation of a novel phenomenon, the self-retracting motion of graphite, in which tiny flakes of graphite, after being displaced to various suspended positions from islands of highly orientated pyrolytic graphite, retract back onto the islands under no external influences. Reports of this phenomenon have not been found in the literature for single crystals of any kind. Models that include the van der Waals force, electrostatic force, and shear strengths were considered to explain the observed phenomenon. These findings may conduce to create nanoelectromechanical systems with a wide range of mechanical frequency from megahertz to gigahertz.

  2. Fabrication of graphite/polyimide composite structures.

    NASA Technical Reports Server (NTRS)

    Varlas, M.

    1972-01-01

    Selection of graphite/polyimide composite as a prime candidate for high-temperature structural applications involving long-duration temperature environments of 400 to 600 F. A variety of complex graphite/polyimide components has been fabricated, using a match-metal die approach developed for making fiber-reinforced resin composites. Parts produced include sections of a missile adapter skin flange, skin frame section, and I-beam and hat-section stringers, as well as unidirectional (0 deg) and plus or minus 45 deg oriented graphite/polyimide tubes in one-, two-, and six-inch diameters.

  3. Monolithic porous graphitic carbons obtained through catalytic graphitization of carbon xerogels

    NASA Astrophysics Data System (ADS)

    Kiciński, Wojciech; Norek, Małgorzata; Bystrzejewski, Michał

    2013-01-01

    Pyrolysis of organic xerogels accompanied by catalytic graphitization and followed by selective-combustion purification was used to produce porous graphitic carbons. Organic gels impregnated with iron(III) chloride or nickel(II) acetate were obtained through polymerization of resorcinol and furfural. During the pyrolysis stage graphitization of the gel matrix occurs, which in turn develops mesoporosity of the obtained carbons. The evolution of the carbon into graphitic structures is strongly dependent on the concentrations of the transition metal. Pyrolysis leads to monoliths of carbon xerogel characterized by substantially enhanced mesoporosity resulting in specific surface areas up to 400 m2/g. Removal of the amorphous carbon by selective-combustion purification reduces the xerogels' mesoporosity, occasionally causing loss of their mechanical strength. The graphitized carbon xerogels were investigated by means of SEM, XRD, Raman scattering, TG-DTA and N2 physisorption. Through this procedure well graphitized carbonaceous materials can be obtained as bulk pieces.

  4. Performance of brazed graphite, carbon-fiber composite, and TZM materials for actively cooled structures; Qualification tests

    SciTech Connect

    Smid, I. ); Croessmann, C.D.; Watson, R.D. ); Linke, J. ); Cardella, A.; Bolt, H,. ); Reheis, N.; Kny, E. )

    1991-07-01

    The divertor of a near-term fusion device has to withstand high heat fluxes, heat shocks, and erosion caused by the plasma. Furthermore, it has to be maintainable through remote techniques. Above all, a good heat removal capability across the interface (low-Z armor/heat sink) plus overall integrity after many operational cycles are needed. To meet all these requirements, an active metal brazing technique is applied to bond graphite and carbon-fiber composite materials to a heat sink consisting of a Mo-41Re coolant tube through a TZM body. Plain brazed graphite and TZM tiles are tested for their fusion-relevant properties. The interfaces appear undamaged after thermal cycling when the melting point of the braze joint is not exceeded and when the graphite armor is {gt}4 mm thick. High heat flux tests are performed on three actively cooled divertor targets. The braze joints show no sign of failure after exposure to thermal loads {approximately}25% higher than the design value surface heat flux of 10 MW/m{sup 2}.

  5. Stable dispersions of polymer-coated graphitic nanoplatelets

    NASA Technical Reports Server (NTRS)

    Stankovich, Sasha (Inventor); Nguyen, Sonbinh T. (Inventor); Ruoff, Rodney S. (Inventor)

    2011-01-01

    A method of making a dispersion of reduced graphite oxide nanoplatelets involves providing a dispersion of graphite oxide nanoplatelets and reducing the graphite oxide nanoplatelets in the dispersion in the presence of a reducing agent and a polymer. The reduced graphite oxide nanoplatelets are reduced to an extent to provide a higher C/O ratio than graphite oxide. A stable dispersion having polymer-treated reduced graphite oxide nanoplatelets dispersed in a dispersing medium, such as water or organic liquid is provided. The polymer-treated, reduced graphite oxide nanoplatelets can be distributed in a polymer matrix to provide a composite material.

  6. Bulge RR Lyrae stars in the VVV tile b201

    NASA Astrophysics Data System (ADS)

    Gran, F.; Minniti, D.; Saito, R. K.; Navarrete, C.; Dékány, I.; McDonald, I.; Contreras Ramos, R.; Catelan, M.

    2015-03-01

    Context. The VISTA Variables in the Vía Láctea (VVV) Survey is one of the six ESO public surveys currently ongoing at the VISTA telescope on Cerro Paranal, Chile. VVV uses near-IR (ZYJHKs) filters that at present provide photometry to a depth of Ks ~ 17.0 mag in up to 36 epochs spanning over four years, and aim at discovering more than 106 variable sources as well as trace the structure of the Galactic bulge and part of the southern disk. Aims: A variability search was performed to find RR Lyrae variable stars. The low stellar density of the VVV tile b201, which is centered at (ℓ,b) ~ (-9°, -9°), makes it suitable to search for variable stars. Previous studies have identified some RR Lyrae stars using optical bands that served to test our search procedure. The main goal is to measure the reddening, interstellar extinction, and distances of the RR Lyrae stars and to study their distribution on the Milky Way bulge. Methods: For each star in the tile with more than 25 epochs (~90% of the objects down to Ks ~ 17.0 mag), the standard deviation and χ2 test were calculated to identify variable candidates. Periods were determined using the analysis of variance. Objects with periods in the RR Lyrae range of 0.2 ≤ P ≤ 1.2 days were selected as candidate RR Lyrae. They were individually examined to exclude false positives. Results: A total of 1.5 sq deg were analyzed, and we found 39 RR Lyr stars, 27 of which belong to the ab-type and 12 to the c-type. Our analysis recovers all the previously identified RR Lyrae variables in the field and discovers 29 new RR Lyr stars. The reddening and extinction toward all the RRab stars in this tile were derived, and distance estimations were obtained through the period-luminosity relation. Despite the limited amount of RR Lyrae stars studied, our results are consistent with a spheroidal or central distribution around ~8.1 and ~8.5 kpc. for either the Cardelli or Nishiyama extinction law. Our analysis does not reveal a stream

  7. Superhydrophilic graphite surfaces and water-dispersible graphite colloids by electrochemical exfoliation

    SciTech Connect

    Li, Yueh-Feng; Chen, Shih-Ming; Lai, Wei-Hao; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2013-08-14

    Superhydrophilic graphite surfaces and water-dispersible graphite colloids are obtained by electrochemical exfoliation with hydrophobic graphite electrodes. Such counterintuitive characteristics are caused by partial oxidation and investigated by examining both graphite electrodes and exfoliated particles after electrolysis. The extent of surface oxidation can be explored through contact angle measurement, scanning electron microscope, electrical sheet resistance, x-ray photoelectron spectroscopy, zeta-potential analyzer, thermogravimetric analysis, UV-visible, and Raman spectroscopy. The degree of wettability of the graphite anode can be altered by the electrolytic current and time. The water contact angle declines generally with increasing the electrolytic current or time. After a sufficient time, the graphite anode becomes superhydrophilic and its hydrophobicity can be recovered by peeling with adhesive tape. This consequence reveals that the anodic graphite is oxidized by oxygen bubbles but the oxidation just occurs at the outer layers of the graphite sheet. Moreover, the characteristics of oxidation revealed by UV peak shift, peak ratio between D and G bands, and negative zeta-potential indicate the presence of graphite oxide on the outer shell of the exfoliated colloids. However, thermogravimetric analysis for the extent of decomposition of oxygen functional groups verifies that the amount of oxygen groups is significantly less than that of graphite oxide prepared via Hummer method. The structure of this partially oxidized graphite may consist of a graphite core covered with an oxidized shell. The properties of the exfoliated colloids are also influenced by pH of the electrolytic solution. As pH is increased, the extent of oxidation descends and the thickness of oxidized shell decreases. Those results reveal that the degree of oxidation of exfoliated nanoparticles can be manipulated simply by controlling pH.

  8. FennoFlakes: a project for identifying flake graphite ores in the Fennoscandian shield and utilizing graphite in different applications

    NASA Astrophysics Data System (ADS)

    Palosaari, Jenny; Eklund, O.; Raunio, S.; Lindfors, T.; Latonen, R.-M.; Peltonen, J.; Smått, J.-H.; Kauppila, J.; Lund, S.; Sjöberg-Eerola, P.; Blomqvist, R.; Marmo, J.

    2016-04-01

    Natural graphite is a strategic mineral, since the European Commission stated (Report on critical raw materials for the EU (2014)) that graphite is one of the 20 most critical materials for the European Union. The EU consumed 13% of all flake graphite in the world but produced only 3%, which stresses the demand of the material. Flake graphite, which is a flaky version of graphite, forms under high metamorphic conditions. Flake graphite is important in different applications like batteries, carbon brushes, heat sinks etc. Graphene (a single layer of graphite) can be produced from graphite and is commonly used in many nanotechnological applications, e.g. in electronics and sensors. The steps to obtain pure graphene from graphite ore include fragmentation, flotation and exfoliation, which can be cumbersome and resulting in damaging the graphene layers. We have started a project named FennoFlakes, which is a co-operation between geologists and chemists to fill the whole value chain from graphite to graphene: 1. Exploration of graphite ores (geological and geophysical methods). 2. Petrological and geochemical analyses on the ores. 3. Development of fragmentation methods for graphite ores. 4. Chemical exfoliation of the enriched flake graphite to separate flake graphite into single and multilayer graphene. 5. Test the quality of the produced material in several high-end applications with totally environmental friendly and disposable material combinations. Preliminary results show that flake graphite in high metamorphic areas has better qualities compared to synthetic graphite produced in laboratories.

  9. Bonding changes in compressed superhard graphite.

    PubMed

    Mao, Wendy L; Mao, Ho-kwang; Eng, Peter J; Trainor, Thomas P; Newville, Matthew; Kao, Chi-chang; Heinz, Dion L; Shu, Jinfu; Meng, Yue; Hemley, Russell J

    2003-10-17

    Compressed under ambient temperature, graphite undergoes a transition at approximately 17 gigapascals. The near K-edge spectroscopy of carbon using synchrotron x-ray inelastic scattering reveals that half of the pi-bonds between graphite layers convert to sigma-bonds, whereas the other half remain as pi-bonds in the high-pressure form. The x-ray diffraction pattern of the high-pressure form is consistent with a distorted graphite structure in which bridging carbon atoms between graphite layers pair and form sigma-bonds, whereas the nonbridging carbon atoms remain unpaired with pi-bonds. The high-pressure form is superhard, capable of indenting cubic-diamond single crystals.

  10. Postbuckling behavior of graphite-epoxy panels

    NASA Technical Reports Server (NTRS)

    Starnes, J. H., Jr.; Dickson, J. N.; Rouse, M.

    1984-01-01

    Structurally efficient fuselage panels are often designed to allow buckling to occur at applied loads below ultimate. Interest in applying graphite-epoxy materials to fuselage primary structure led to several studies of the post-buckling behavior of graphite-epoxy structural components. Studies of the postbuckling behavior of flat and curved, unstiffened and stiffened graphite-epoxy panels loaded in compression and shear were summarized. The response and failure characteristics of specimens studied experimentally were described, and analytical and experimental results were compared. The specimens tested in the studies described were fabricated from commercially available 0.005-inch-thick unidirectional graphite-fiber tapes preimpregnated with 350 F cure thermosetting epoxy resins.

  11. Feasibility of intercalated graphite railgun armatures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Gooden, Clarence E.; Yashan, Doreen; Naud, Steven

    1990-01-01

    Graphite intercalation compounds may provide an excellent material for the fabrication of electro-magnetic railgun armatures. As a pulse of power is fed into the armature the intercalate could be excited into the plasma state around the edges of the armature, while the bulk of the current would be carried through the graphite block. Such an armature would have the desirable characteristics of both diffuse plasma armatures and bulk conduction armatures. In addition, the highly anisotropic nature of these materials could enable the electrical and thermal conductivity to be tailored to meet the specific requirements of electromagnetic railgun armatures. Preliminary investigations were performed in an attempt to determine the feasibility of using graphite intercalation compounds as railgun armatures. Issues of fabrication, resistivity, stability, and electrical current spreading are addressed for the case of highly oriented pyrolytic graphite.

  12. Immobilization of Rocky Flats Graphite Fines Residue

    SciTech Connect

    Rudisill, T.S.

    1999-04-06

    The development of the immobilization process for graphite fines has proceeded through a series of experimental programs. The experimental procedures and results from each series of experiments are discussed in this report.

  13. Analysis of Picosecond Pulsed Laser Melted Graphite

    DOE R&D Accomplishments Database

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  14. A digital gigapixel large-format tile-scan camera.

    PubMed

    Ben-Ezra, M

    2011-01-01

    Although the resolution of single-lens reflex (SLR) and medium-format digital cameras has increased in recent years, applications for cultural-heritage preservation and computational photography require even higher resolutions. Addressing this issue, a large-format cameras' large image planes can achieve very high resolution without compromising pixel size and thus can provide high-quality, high-resolution images.This digital large-format tile scan camera can acquire high-quality, high-resolution images of static scenes. It employs unique calibration techniques and a simple algorithm for focal-stack processing of very large images with significant magnification variations. The camera automatically collects overlapping focal stacks and processes them into a high-resolution, extended-depth-of-field image.

  15. Direct molding of pavement tiles made of ground tire rubber

    NASA Astrophysics Data System (ADS)

    Quadrini, Fabrizio; Gagliardi, Donatella; Tedde, Giovanni Matteo; Santo, Loredana; Musacchi, Ettore

    2016-10-01

    Large rubber products can be molded by using only ground tire rubber (GTR) without any additive or binder due to a new technology called "direct molding". Rubber granules and powders from tire recycling are compression molded at elevated temperatures and pressures. The feasibility of this process was clearly shown in laboratory but the step to the industrial scale was missing. Thanks to an European Project (SMART "Sustainable Molding of Articles from Recycled Tires") this step has been made and some results are reported in this study. The press used for compression molding is described. Some tests were made to measure the energy consumption so as to evaluate costs for production in comparison with conventional technologies for GTR molding (by using binders). Results show that 1 m2 tiles can be easily molded with several thicknesses in a reasonable low time. Energy consumption is higher than conventional technologies but it is lower than the cost for binders.

  16. Courant-sharp eigenvalues of Neumann 2-rep-tiles

    NASA Astrophysics Data System (ADS)

    Band, Ram; Bersudsky, Michael; Fajman, David

    2016-11-01

    We find the Courant-sharp Neumann eigenvalues of the Laplacian on some 2-rep-tile domains. In {R}2 , the domains we consider are the isosceles right triangle and the rectangle with edge ratio √{2} (also known as the A4 paper). In {R}n , the domains are boxes which generalize the mentioned planar rectangle. The symmetries of those domains reveal a special structure of their eigenfunctions, which we call folding/unfolding. This structure affects the nodal set of the eigenfunctions, which, in turn, allows to derive necessary conditions for Courant-sharpness. In addition, the eigenvalues of these domains are arranged as a lattice which allows for a comparison between the nodal count and the spectral position. The Courant-sharpness of most eigenvalues is ruled out using those methods. In addition, this analysis allows to estimate the nodal deficiency—the difference between the spectral position and the nodal count.

  17. Genome-wide transcription analyses in rice using tiling microarrays.

    PubMed

    Li, Lei; Wang, Xiangfeng; Stolc, Viktor; Li, Xueyong; Zhang, Dongfen; Su, Ning; Tongprasit, Waraporn; Li, Songgang; Cheng, Zhukuan; Wang, Jun; Deng, Xing Wang

    2006-01-01

    Sequencing and computational annotation revealed several features, including high gene numbers, unusual composition of the predicted genes and a large number of genes lacking homology to known genes, that distinguish the rice (Oryza sativa) genome from that of other fully sequenced model species. We report here a full-genome transcription analysis of the indica rice subspecies using high-density oligonucleotide tiling microarrays. Our results provided expression data support for the existence of 35,970 (81.9%) annotated gene models and identified 5,464 unique transcribed intergenic regions that share similar compositional properties with the annotated exons and have significant homology to other plant proteins. Elucidating and mapping of all transcribed regions revealed an association between global transcription and cytological chromosome features, and an overall similarity of transcriptional activity between duplicated segments of the genome. Collectively, our results provide the first whole-genome transcription map useful for further understanding the rice genome.

  18. pH-Controlled Assembly of DNA Tiles.

    PubMed

    Amodio, Alessia; Adedeji, Abimbola Feyisara; Castronovo, Matteo; Franco, Elisa; Ricci, Francesco

    2016-10-05

    We demonstrate a strategy to trigger and finely control the assembly of supramolecular DNA nanostructures with pH. Control is achieved via a rationally designed strand displacement circuit that responds to pH and activates a downstream DNA tile self-assembly process. We observe that the DNA structures form under neutral/basic conditions, while the self-assembly process is suppressed under acidic conditions. The strategy presented here demonstrates a modular approach toward building systems capable of processing biochemical inputs and finely controlling the assembly of DNA-based nanostructures under isothermal conditions. In particular, the presented architecture is relevant for the development of complex DNA devices able to sense and respond to molecular markers associated with abnormal metabolism.

  19. In-flight investigation of shuttle tile pressure orifice installations

    NASA Technical Reports Server (NTRS)

    Moes, Timothy R.; Meyer, Robert R., Jr.

    1990-01-01

    To determine shuttle orbiter wing loads during ascent, wing load instrumentation was added to Columbia (OV-102). This instrumentation included strain gages and pressure orifices on the wing. The loads derived from wing pressure measurements taken during STS 61-C did not agree with those derived from strain gage measurements or with the loads predicted from the aerodynamic database. Anomalies in the surface immediately surrounding the pressure orifices in the thermal protection system (TPS) tiles were one possible cause of errors in the loads derived from wing pressure measurements. These surface anomalies were caused by a ceramic filler material which was installed around the pressure tubing. The filler material allowed slight movement of the TPS tile and pressure tube as the airframe flexed and bent under aerodynamic loads during ascent and descent. Postflight inspection revealed that this filler material had protruded from or receeded beneath the surface, causing the orifice to lose its flushness. Flight tests were conducted at NASA Ames Research Center Dryden Flight Research Facility to determine the effects of any anomaly in surface flushness of the orifice installation on the measured pressures at Mach numbers between 0.6 and 1.4. An F-104 aircraft with a flight test fixture mounted beneath the fuselage was used for these flights. Surface flushness anomalies typical of those on the orbiter after flight (STA 61-C) were tested. Also, cases with excessive protrusion and recession of the filler material were tested. This report shows that the anomalies in STS 61-C orifice installations adversely affected the pressure measurements. But the magnitude of the affect was not great enough to account for the discrepancies with the strain gage measurements and the aerodynamic predictions.

  20. Decay of neutron pulses in graphite assemblies

    SciTech Connect

    Malik, U.; Kothari, L.S.

    1982-09-01

    A new neutron scattering kernel for graphite has been developed with the frequency distribution function generated by the authors using the unfolding technique. This has been used to study the decay of neutron pulses in different graphite assemblies. This kernel (with theta /SUB D/ = 2000 K) can give a slightly better explanation of the experimental results than those based on the Krumhansl and Brooks model or the Young and Koppel model of lattice vibrations.

  1. Tribology of alumina-graphite composites

    NASA Astrophysics Data System (ADS)

    Yu, Chih-Yuan

    Alumina-graphite composites, which combine high wear resistance and self-lubricity, are a potential and promising candidate for advanced tribological applications. The processing, mechanical properties and tribology of alumina-graphite composites are discussed. Full density is difficult to achieve by a pressureless sintering route. Porosity of the composites increases with graphite content which causes the strength, modulus of elasticity, and hardness of the composites to decrease. The increased porosity does cause the fracture toughness to slightly increases. Tribology of alumina-graphite composites was studied with a pin-on-disk tribometer with emphasis on the following aspects: the graphite content in both pin and disk, the graphite flake size and the orientation of the graphite flakes. Scan electronic microscopy (SEM) and X-ray diffraction are utilized to examine and characterize the wear debris and the worn surface. Results confirmed that it is necessary to optimize the structure and the supply of lubricant to improve the tribological behavior and that the arrangements of sliding couples also affect the tribology of self-lubricated ceramic composites. Continuous measurements of the friction coefficients were collected at high frequency in an attempt to correlate the tribology of alumina-graphite composites to vibrations introduced by friction. While these measurements indicate that the time frequency behavior of tribology is an important area of study, conclusions regarding the frequency response of different sliding couples could not be definitively stated. Finally, a new concept connecting instantaneous wear coefficient and instantaneous contact stress is proposed for prediction of wear behavior of brittle materials.

  2. GRAPHITE PRODUCTION UTILIZING URANYL NITRATE HEXAHYDRATE CATALYST

    DOEpatents

    Sheinberg, H.; Armstrong, J.R.; Schell, D.H.

    1964-03-10

    ABS>The graphitizing of a mixture composed of furfuryl alcohol binder and uranyl nitrate hexahydrate hardener and the subsequent curing, baking, and graphitizing with pressure being initially applied prior to curing are described. The pressure step may be carried out by extrusion, methyl cellulose being added to the mixture before the completion of extrusion. Uranium oxide may be added to the graphitizable mixture prior to the heating and pressure steps. The graphitizable mixture may consist of discrete layers of different compositions. (AEC)

  3. Induction graphitizing furnace acceptance test report

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The induction furnace was designed to provide the controlled temperature and environment required for the post-cure, carbonization and graphitization processes for the fabrication of a fibrous graphite NERVA nozzle extension. The acceptance testing required six tests and a total operating time of 298 hrs. Low temperature mode operations, 120 to 850 C, were completed in one test run. High temperature mode operations, 120 to 2750 C, were completed during five tests.

  4. An experimental summary of plasma arc exposures of space shuttle high-temperature reusable surface insulation tile array with a single missing tile (conducted at the Ames Research Center)

    NASA Technical Reports Server (NTRS)

    Galanter, S. A.

    1975-01-01

    A space shuttle high temperature reusable surface insulation (HRSI) tile array with a single missing or lost tile was exposed to a hot gas simulated reentry environment to investigate the heating conditions in and around the vicinity of the missing HRSI tile. Heat flux and pressure data for the lost tile condition were obtained by the use of a water cooled lost tile calibration model. The maximum aluminum substrate temperature obtained during the simulated reentry was 128 C (263 F). The lost tile calibration data indicated a maximum heat flux in the lost tile cavity region of 63 percent of the upstream reference value. This test was conducted at the Ames Research Center in the 20 MW semielliptical thermal protection system (TPS) pilot plasma arc test facility.

  5. Numerical Investigation of the Spatiotemporal Contribution of Tile Drainage to Stream Flow

    NASA Astrophysics Data System (ADS)

    Thomas, N. W.; Schilling, K. E.; Weber, L. J.

    2015-12-01

    Tile drainage systems are pervasive in the Central U.S., significantly altering the hydrologic system. A physically based coupled hydrologic model was applied to a 45 km2 agricultural Iowa watershed. The tile drainage contribution to stream flow (QT/Q) was derived from a tracer driven analysis of instream surface water. QT/Q varied instantaneously from 6% to 71 % at the basin outlet, with tile flow correlating linearly with total stream flow. In low precipitation periods 62 % of stream flow traveled through the tile system. In heavy precipitation periods a dilution effect shifted QT/Q to 27 %. Precipitation driven events produced a strong positive logarithmic correlation between QT/Q and drainage area. The addition of precipitation into the system saturated near surface soils, increased lateral soil water movement, and diluted the relatively stable instream tile flow. A negative logarithmic trend in QT/Q to drainage area persisted non-event durations. Larger groundwater (non-tile) contribution to stream flow at the outlet diluted instream tile flow at increased drainage areas. Logarithmic regression slopes were consistent for event and non-event periods, respectively. While, the intercept responded in a predicable manner to precipitation intensity. This study, indicates a strong systematic response of QT/Q to meteorological forcing, drainage area over a single year.

  6. Technical note: comparing von Luschan skin color tiles and modern spectrophotometry for measuring human skin pigmentation.

    PubMed

    Swiatoniowski, Anna K; Quillen, Ellen E; Shriver, Mark D; Jablonski, Nina G

    2013-06-01

    Prior to the introduction of reflectance spectrophotometry into anthropological field research during the 1950s, human skin color was most commonly classified by visual skin color matching using the von Luschan tiles, a set of 36 standardized, opaque glass tiles arranged in a chromatic scale. Our goal was to establish a conversion formula between the tile-based color matching method and modern reflectance spectrophotometry to make historical and contemporary data comparable. Skin pigmentation measurements were taken on the forehead, inner upper arms, and backs of the hands using both the tiles and a spectrophotometer on 246 participants showing a broad range of skin pigmentation. From these data, a second-order polynomial conversion formula was derived by jackknife analysis to estimate melanin index (M-index) based on tile values. This conversion formula provides a means for comparing modern data to von Luschan tile measurements recorded in historical reports. This is particularly important for populations now extinct, extirpated, or admixed for which tile-based measures of skin pigmentation are the only data available.

  7. Analytical and experimental evaluations of Space Shuttle TPS tile vibration response

    NASA Technical Reports Server (NTRS)

    Piersol, A. G.; Pope, L. D.

    1982-01-01

    Analytical studies and laboratory experiments have been performed to evaluate the vibration response of the Space Shuttle Thermal Protection System (TPS) tiles due to the intense rocket generated acoustic noise during lift-off. The TPS tiles are mounted over the exterior of the Space Shuttle Orbiter structure through Strain Isolation Pads (SIP) which protect the tiles from thermal induced shear loads at their interface. The analytical predictions indicate that the response of a typical tile is governed by the structural vibration inputs through the SIP under the tile at frequencies below 250 Hz, and by the direct acoustic excitation over the exterior surface of the tile at frequencies above 250 Hz. An evaluation of the laboratory test data for this same tile, in which conditioned (partial) coherent output spectral analysis procedures were used, leads to exactly the same conclusion. The results demonstrate the power of conditioned spectral analysis procedures in identifying vibration response mechanisms when two or more of the inputs are highly correlated.

  8. Nondeterministic self-assembly of two tile types on a lattice

    NASA Astrophysics Data System (ADS)

    Tesoro, S.; Ahnert, S. E.

    2016-04-01

    Self-assembly is ubiquitous in nature, particularly in biology, where it underlies the formation of protein quaternary structure and protein aggregation. Quaternary structure assembles deterministically and performs a wide range of important functions in the cell, whereas protein aggregation is the hallmark of a number of diseases and represents a nondeterministic self-assembly process. Here we build on previous work on a lattice model of deterministic self-assembly to investigate nondeterministic self-assembly of single lattice tiles and mixtures of two tiles at varying relative concentrations. Despite limiting the simplicity of the model to two interface types, which results in 13 topologically distinct single tiles and 106 topologically distinct sets of two tiles, we observe a wide variety of concentration-dependent behaviors. Several two-tile sets display critical behaviors in the form of a sharp transition from bound to unbound structures as the relative concentration of one tile to another increases. Other sets exhibit gradual monotonic changes in structural density, or nonmonotonic changes, while again others show no concentration dependence at all. We catalog this extensive range of behaviors and present a model that provides a reasonably good estimate of the critical concentrations for a subset of the critical transitions. In addition, we show that the structures resulting from these tile sets are fractal, with one of two different fractal dimensions.

  9. Structure and functionality of bromine doped graphite.

    PubMed

    Hamdan, Rashid; Kemper, A F; Cao, Chao; Cheng, H P

    2013-04-28

    First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br2). However, with increased compression (decreased layer-layer separation) Br2 molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br2 molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.

  10. Structure and functionality of bromine doped graphite

    SciTech Connect

    Hamdan, Rashid; Kemper, A. F.; Cao Chao; Cheng, H. P.

    2013-04-28

    First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br{sub 2}). However, with increased compression (decreased layer-layer separation) Br{sub 2} molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br{sub 2} molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.

  11. Measurement of the cleavage energy of graphite

    PubMed Central

    Wang, Wen; Dai, Shuyang; Li, Xide; Yang, Jiarui; Srolovitz, David J.; Zheng, Quanshui

    2015-01-01

    The basal plane cleavage energy (CE) of graphite is a key material parameter for understanding many of the unusual properties of graphite, graphene and carbon nanotubes. Nonetheless, a wide range of values for the CE has been reported and no consensus has yet emerged. Here we report the first direct, accurate experimental measurement of the CE of graphite using a novel method based on the self-retraction phenomenon in graphite. The measured value, 0.37±0.01 J m−2 for the incommensurate state of bicrystal graphite, is nearly invariant with respect to temperature (22 °C≤T≤198 °C) and bicrystal twist angle, and insensitive to impurities from the atmosphere. The CE for the ideal ABAB graphite stacking, 0.39±0.02 J m−2, is calculated based on a combination of the measured CE and a theoretical calculation. These experimental measurements are also ideal for use in evaluating the efficacy of competing theoretical approaches. PMID:26314373

  12. Graphite Composite Panel Polishing Fixture

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Strojny, Carl; Budinoff, Jason

    2011-01-01

    The use of high-strength, lightweight composites for the fixture is the novel feature of this innovation. The main advantage is the light weight and high stiffness-to-mass ratio relative to aluminum. Meter-class optics require support during the grinding/polishing process with large tools. The use of aluminum as a polishing fixture is standard, with pitch providing a compliant layer to allow support without deformation. Unfortunately, with meter-scale optics, a meter-scale fixture weighs over 120 lb (.55 kg) and may distort the optics being fabricated by loading the mirror and/or tool used in fabrication. The use of composite structures that are lightweight yet stiff allows standard techniques to be used while providing for a decrease in fixture weight by almost 70 percent. Mounts classically used to support large mirrors during fabrication are especially heavy and difficult to handle. The mount must be especially stiff to avoid deformation during the optical fabrication process, where a very large and heavy lap often can distort the mount and optic being fabricated. If the optic is placed on top of the lapping tool, the weight of the optic and the fixture can distort the lap. Fixtures to support the mirror during fabrication are often very large plates of aluminum, often 2 in. (.5 cm) or more in thickness and weight upwards of 150 lb (68 kg). With the addition of a backing material such as pitch and the mirror itself, the assembly can often weigh over 250 lb (.113 kg) for a meter-class optic. This innovation is the use of a lightweight graphite panel with an aluminum honeycomb core for use as the polishing fixture. These materials have been used in the aerospace industry as structural members due to their light weight and high stiffness. The grinding polishing fixture consists of the graphite composite panel, fittings, and fixtures to allow interface to the polishing machine, and introduction of pitch buttons to support the optic under fabrication. In its

  13. Detecting Subsurface Agricultural Tile Drainage using GIS and Remote Sensing Technique

    NASA Astrophysics Data System (ADS)

    Budhathoki, M.; Gokkaya, K.; Tank, J. L.; Christopher, S. F.; Hanrahan, B.

    2015-12-01

    Subsurface tile drainage is a common practice in many of the row crop dominated agricultural lands in the Upper Midwest, which increases yield by making the soil more productive. It is reported that nearly half of all cropland in Indiana benefits from some sort of artificial drainage. However, subsurface tile has a significant negative impact on surface water quality by providing a fast means of transport for nutrients from fertilizers. Therefore, generating spatial data of tile drainage in the field is important and useful for agricultural landscape and hydrological studies. Subsurface tile drains in Indiana's croplands are not widely mapped. In this study, we will delineate subsurface tile drainage in agricultural land in Shatto Ditch watershed, located in Kosciusko County, Indiana. We will use geo-spatial methodology, which was purposed by earlier researchers to detect tile drainage. We will use aerial color-infrared and satellite imagery along with Light Detection and Ranging (LiDAR) data. In order to map tile lines with possible accuracy, we will use GIS-based analysis in combination with remotely sensed data. This research will be comprised of three stages: 1) masking out the potential drainage area using a decision tree rule based on land cover information, soil drainage category, surface slope, and satellite image differencing technique, 2) delineate tile lines using image processing techniques, and 3) check the accuracy of mapped tile lines with ground control points. To our knowledge, this study will be the first to check the accuracy of mapping with ground truth data. Based on the accuracy of results, we will extend the methodology to greater spatial scales. The results are expected to contribute to better characterizing and controlling water pollution sources in Indiana, which is a major environmental problem.

  14. Gap heating with pressure gradients. [for Shuttle Orbiter thermal protection system tiles

    NASA Technical Reports Server (NTRS)

    Scott, C. D.; Maraia, R. J.

    1979-01-01

    The heating rate distribution and temperature response on the gap walls of insulating tiles is analyzed to determine significant phenomena and parameters in flows where there is an external surface pressure gradient. Convective heating due to gap flow, modeled as fully developed pipe flow, is coupled with a two-dimensional thermal model of the tiles that includes conduction and radiative heat transfer. To account for geometry and important environmental parameters, scale factors are obtained by curve-fitting measured temperatures to analytical solutions. These scale factors are then used to predict the time-dependent gap heat flux and temperature response of tile gaps on the Space Shuttle Orbiter during entry.

  15. Beam test results of a high-granularity tile/fiber electromagnetic calorimeter

    NASA Astrophysics Data System (ADS)

    Ono, H.; Miyata, H.; Iba, S.; Nakajima, N.; Sanchez, A. L. C.; Fujii, Y.; Itoh, S.; Kajino, F.; Kanzaki, J.; Kawagoe, K.; Kim, S.; Kishimoto, S.; Matsumoto, T.; Matsunaga, H.; Nagano, A.; Nakamura, R.; Takeshita, T.; Tamura, Y.; Yamauchi, S.

    2009-03-01

    A prototype sampling electromagnetic calorimeter (17.1 radiation lengths) for future linear collider experiments was built, using 4 cm×4 cm×1 mm plastic scintillator tiles and 4 mm-thick lead absorber. Wavelength-shifting fibers were used to guide the scintillation light into multi-anode photo-multiplier tubes. The calorimeter was tested at the beam test facility of the High Energy Accelerator Research Organization (KEK) in 2004. In this article we present our beam test results for the tile/fiber calorimeter focusing on the linearity in energy response, the energy resolution, position resolution and uniformity across the tile front face.

  16. Analysis of Tile-Reinforced Composite Armor. Part 1; Advanced Modeling and Strength Analyses

    NASA Technical Reports Server (NTRS)

    Davila, C. G.; Chen, Tzi-Kang; Baker, D. J.

    1998-01-01

    The results of an analytical and experimental study of the structural response and strength of tile-reinforced components of the Composite Armored Vehicle are presented. The analyses are based on specialized finite element techniques that properly account for the effects of the interaction between the armor tiles, the surrounding elastomers, and the glass-epoxy sublaminates. To validate the analytical predictions, tests were conducted with panels subjected to three-point bending loads. The sequence of progressive failure events for the laminates is described. This paper describes the results of Part 1 of a study of the response and strength of tile-reinforced composite armor.

  17. Self assembly of rectangular shapes on concentration programming and probabilistic tile assembly models.

    PubMed

    Kundeti, Vamsi; Rajasekaran, Sanguthevar

    2012-06-01

    Efficient tile sets for self assembling rectilinear shapes is of critical importance in algorithmic self assembly. A lower bound on the tile complexity of any deterministic self assembly system for an n × n square is [Formula: see text] (inferred from the Kolmogrov complexity). Deterministic self assembly systems with an optimal tile complexity have been designed for squares and related shapes in the past. However designing [Formula: see text] unique tiles specific to a shape is still an intensive task in the laboratory. On the other hand copies of a tile can be made rapidly using PCR (polymerase chain reaction) experiments. This led to the study of self assembly on tile concentration programming models. We present two major results in this paper on the concentration programming model. First we show how to self assemble rectangles with a fixed aspect ratio (α:β), with high probability, using Θ(α + β) tiles. This result is much stronger than the existing results by Kao et al. (Randomized self-assembly for approximate shapes, LNCS, vol 5125. Springer, Heidelberg, 2008) and Doty (Randomized self-assembly for exact shapes. In: proceedings of the 50th annual IEEE symposium on foundations of computer science (FOCS), IEEE, Atlanta. pp 85-94, 2009)-which can only self assembly squares and rely on tiles which perform binary arithmetic. On the other hand, our result is based on a technique called staircase sampling. This technique eliminates the need for sub-tiles which perform binary arithmetic, reduces the constant in the asymptotic bound, and eliminates the need for approximate frames (Kao et al. Randomized self-assembly for approximate shapes, LNCS, vol 5125. Springer, Heidelberg, 2008). Our second result applies staircase sampling on the equimolar concentration programming model (The tile complexity of linear assemblies. In: proceedings of the 36th international colloquium automata, languages and programming: Part I on ICALP '09, Springer-Verlag, pp 235-253, 2009

  18. Thermal insulation attaching means. [adhesive bonding of felt vibration insulators under ceramic tiles

    NASA Technical Reports Server (NTRS)

    Leger, L. J. (Inventor)

    1978-01-01

    An improved isolation system is provided for attaching ceramic tiles of insulating material to the surface of a structure to be protected against extreme temperatures of the nature expected to be encountered by the space shuttle orbiter. This system isolates the fragile ceramic tiles from thermally and mechanically induced vehicle structural strains. The insulating tiles are affixed to a felt isolation pad formed of closely arranged and randomly oriented fibers by means of a flexible adhesive and in turn the felt pad is affixed to the metallic vehicle structure by an additional layer of flexible adhesive.

  19. Electrospun SiO2 "necklaces" on unglazed ceramic tiles: a planarizing strategy

    NASA Astrophysics Data System (ADS)

    Di Mauro, Alessandro; Fragalà, Maria Elena

    2015-05-01

    Silica based nanofibres have been deposited on unglazed ceramic tiles by combining electrospinning and sol-gel processes. Poly(vinyl pyrrolidone) (PVP) alcoholic solutions and commercial spin on glass (Accuglass) mixtures have been used to obtain composite fibrous non-woven mats totally converted, after thermal annealing at 600 °C, to SiO2 microsphere "necklaces". The possibility to get an uniform fibres coverage onto the tile surface confirms the validity of electrospinning (easily scalable to large surface samples) as coating strategy to cover the macroscopic defects typical of the polished unglazed tile surface and improve surface planarization.

  20. A prediction method for flow in the Shuttle tile strain isolation pad

    NASA Technical Reports Server (NTRS)

    Lawing, Pierce L.

    1987-01-01

    The Shuttle Orbiter thermal protection system uses a Strain Isolation Pad (SIP) between the tile and the Orbiter. This paper presents experimental measurements of the pressure drop and associated flow rate through a sample of the SIP material. Included are data for a range of air densities representative of Shuttle ascent and re-entry trajectories. Also presented are new theoretical and correlative methods which predict the experimental data. These methods will help in predicting venting characteristics of tile assemblies during ascent, and hot gas leak under the tiles during descent. The predictive philosophy developed is useful in the study of fibrous and porous media fluid mechanics.

  1. All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient ( d n / d T ) measurements

    NASA Astrophysics Data System (ADS)

    Putnam, Shawn A.; Fairchild, Steven B.; Arends, Armando A.; Urbas, Augustine M.

    2016-05-01

    This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity ( Λ) and thermo-optic coefficient ( d n / d T ) of materials that are absorbing at λ = 10.6 μm and are transparent to semi-transparent at λ = 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and d n / d T properties ranging between 0.7 W/m K ≲ Λ ≲ 33.5 W/m K and -12 × 10-6 K-1 ≲ d n / d T ≲ 14 × 10-6 K-1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.

  2. Electrostatic properties of graphitic nanostructures

    NASA Astrophysics Data System (ADS)

    Erbahar, Dogan

    2014-03-01

    Carbon nanostructures are considered to be one of the most important candidates of circuit elements for future nanoelectronics. However, being one of the main issues of conventional circuitry used today, charge accumulation on circuit elements can also be expected to have important effects on the performance of the nanoscale devices. In this work we investigated charge accumulation on various graphitic systems by simulated charge doping. We report ab initio density functional theory (DFT) calculations of electrostatically charged multilayered carbon nano structures. We investigate the effect of total and background charge on charge distribution profiles on the systems under consideration varying from multilayered graphene to multiwalled carbon nanotubes. We show that the charge distribution profile on the inner layers are mainly induced from the background charge which is imposed by the code on periodic systems. Our population anaylsis indicates that the outermost two layers effectively shields the inner layers electrostatically. Illuminating the typical skin depth of those systems our results could give important insights for designing the nanocircuit elements.

  3. Resin/graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.

    1974-01-01

    Techniques were developed that provided thermo-oxidatively stable A-type polyimide/graphite fiber composites using the approach of in situ polymerization of monomeric reactants directly on reinforcing fibers, rather than employing separately prepared prepolymer varnish. This was accomplished by simply mixing methylene dianiline and two ester-acids and applying this solution to the fibers for subsequent molding. Five different formulated molecular weight resins were examined, and an optimized die molding procedure established for the 1500 formulated molecular weight system. Extensive ultrasonic inspection of composites was successfully utilized as a technique for monitoring laminate quality. Composite mechanical property studies were conducted with this polyimide resin at room temperature and after various time exposures in a thermo-oxidative environment at 561 K (550 F), 589 K (600 F) and 617 K (650 F). It was determined that such composites have a long term life in the temperature range of 561 K to 589 K. The final phase involved the fabrication and evaluation of a series of demonstration airfoil specimens.

  4. Lithium-Graphite Secondary Battery.

    DTIC Science & Technology

    1976-12-01

    C") co - P u j >C 0 w- 0 - .5- ap ...J i F-- t.. to 0 0 i OIL 0 0L 0s Cr-j it4 000 M. to %0 %0 0 00r-r - ;r -d WO 0 0 w - Z;fl 3 :zwV)Z...0 r 4 I. 4 0 0 0 VA 0- u m. 0 V + w 01.- _j 9L .. J to 5 I p Po. oi c co 4J Li 4-𔃽 U) Z 0 +. "t 0. CM CW qr ~ ~ .C .O4 J f U~ 4’ Co 0JUC 3 03 41 m...mixture of graphite and teflon moulding 17 N L. It ir 4j 4A 0. 0 0 CUL C - 0 %0- 41 w In 2~ P 0’U-. z Lo zr J-i -. 00H U0 w....ff .o .2 4-cu 00 C 4JE -GJ

  5. Thermal cycling graphite-polyimide

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Hagaman, J. A.

    1979-01-01

    The effects of repetitive thermal cycling on the temperature-thermal deformation relation of graphite-polyimide were determined. The bending and axial strains, measured with strain gages, of unsymmetric 0 deg sub 2/90 deg sub 2 and 0 deg sub 4/90 deg sub 4 laminates were used as an indication of thermal deformation. The strains were measured as a function of temperature and two temperature ranges were used, room temperature to 180 C and room temperature to 315 C. Five cycles were run in each temperature range and the cycling was done in quasistatic fashion. The response of a flat 0 deg sub 8 laminate was measured as were the effects of repetitive cycling on the strain gages themselves. A piece-wise linear theory, based on classical lamination theory and using the variation of mechanical and thermal expansion properties with temperature, was compared with the experimental results. The correlation between theoretical predictions and experimental results for the thinner laminate was poor.

  6. RADStation3G: a platform for cardiovascular image analysis integrating PACS, 3D+t visualization and grid computing.

    PubMed

    Perez, F; Huguet, J; Aguilar, R; Lara, L; Larrabide, I; Villa-Uriol, M C; López, J; Macho, J M; Rigo, A; Rosselló, J; Vera, S; Vivas, E; Fernàndez, J; Arbona, A; Frangi, A F; Herrero Jover, J; González Ballester, M A

    2013-06-01

    RADStation3G is a software platform for cardiovascular image analysis and surgery planning. It provides image visualization and management in 2D, 3D and 3D+t; data storage (images or operational results) in a PACS (using DICOM); and exploitation of patients' data such as images and pathologies. Further, it provides support for computationally expensive processes with grid technology. In this article we first introduce the platform and present a comparison with existing systems, according to the platform's modules (for cardiology, angiology, PACS archived enriched searching and grid computing), and then RADStation3G is described in detail.

  7. Novel graphite salts of high oxidizing potential

    SciTech Connect

    McCarron, E.M. III

    1980-08-01

    The intercalation of graphite by the third-transition-series metal hexafluorides has yielded the graphite salts, C/sub 8//sup +/OsF/sub 6//sup -/, C/sub 8//sup +/IrF/sub 6//sup -/ and C/sub 12//sup 2 +/PtF/sub 6//sup 2 -/. The fluoroplatinate salt represents the highest electron withdrawal from the graphite network yet achieved. Analogues to the Os and Ir salts have been obtained both by fluorination of Group V pentaflouride intercalates, C/sub 8/MF/sub 5/ (M = As, Sb), and by the interaction of the dioxygenyl salts with graphite (8C + O/sub 2/MF/sub 6/ ..-->.. C/sub 8/MF/sub 6/ + O/sub 2/+). Non-intercalating binary fluorides have been observed to intercalate in the presence of a fluorine-rich environment (e.g., 8C + PF/sub 5/ + 1/2 F/sub 2/ ..-->.. C/sub 8/PF/sub 6/). GeF/sub 4/, which also does not spontaneously intercalate graphite, has been observed to interact with graphite in the presence of 2 atmospheres of fluorine overpressure to give the fluoroplatinate salt analogue, C/sub 12//sup 2 +/GeF/sub 6//sup 2 -/. This material is in equilibrium with the pentafluorogermanate at ordinary pressures and temperatures. C/sub 12//sup 2 +/GeF/sub 6//sup 2 -/ ..-->.. C/sub 12//sup +/GeF/sub 5//sup -/ + 1/2 F/sub 2/. C/sub 12/GeF/sub 6/ must have an oxidizing potential close to that of fluorine itself. The graphite fluorometallate salts are both electronic and ionic (F/sup -/) conductors. For the C/sub 8//sup +/MF/sub 6//sup -/ salts, a maximum electronic conductivity an order of magnitude greater than the parent graphite has been observed for stage two. The high oxidizing potential, coupled with the fluoride ion transport capability of the graphite salts, has been exploited in the construction of solid-state galvanic cells. These cells use the graphite fluorometallate salts as electrode materials in combination with a superionic fluoride-ion-conducting solid electrolyte.

  8. First principles study of oxidation behavior of irradiated graphite

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Dong, Limin; Wang, Chen; Liang, Tongxiang; Lai, Wensheng

    2015-06-01

    The relationship between nuclear graphite microstructure and its oxidation resistance underlines the importance of comprehensive oxidation characterization studies of the new grades of nuclear graphite. Periodic DFT calculations are performed to model oxidation behavior of irradiated graphite. O2 molecules adsorbed on perfect and defective graphite surfaces are calculated. The adsorptive energy of O2 on defective graphite adsorption site with one carbon atom missing is approximately 10 times as strong as that on a defect-free perfect graphite surface. Monovacancy and divacancy on graphite surface can easily chemisorb O2 molecule compared to perfect surface. Two oxidation processes including CO and CO2 formation steps are analyzed. For symmetric monovacancy defect, three dangling C atoms are unsaturated and exhibit high adsorption ability, as well as reconstructed monovacancy and divacancy defects. These vacancy defects in irradiated graphite decrease oxidation resistance of nuclear graphite.

  9. Internal features of graphite in cast irons. Confocal microscopy: useful tool for graphite growth imaging.

    PubMed

    Llorca-Isern, N; Tartera, J; Espanol, M; Marsal, M; Bertran, G; Castel, S

    2002-01-01

    Spherulitic crystallisation is a mode of growth of crystals from the melt. Considerable attention has been given to spheroidal graphite formation, providing detailed information about the internal microstructure of the spherulites in spheroidal (SG irons) and compacted graphite irons (CG irons) (Stefanescu, D., 1990. Cast Irons. ASM Handbook, 10th ed., vol. 1). Nevertheless, the mechanisms responsible for this mode of crystallisation are not fully understood. This study deals with the inoculation mechanisms, with particular emphasis on the study of the inclusions for the heterogeneous nucleation of graphite. It is shown that the graphite nuclei are sulfide products of the nodularizing treatment. It has been observed that when rare-earth treatment is applied, the central nucleus consists of a core and an envelope from which the graphite grows. Confocal Scanning Laser Microscopy (CSLM), in reflection mode, was used to study the internal features of the spheroidal graphite growth. Confocal reflection imaging, which has a capacity for optical sectioning of the sample, provides high-resolution images of surface and subsurface regions of interest contained within a semi-transparent sample. Furthermore, three-dimensional reconstruction of these optical sections can provide insight into the mechanism of graphite growth mechanism interpretation. With CSLM the radial growth of graphite was seen. Other techniques, such as TEM, SEM-EDS, WDS, AES and SAM were also used to corroborate the results.

  10. Preparation of graphite oxide by sodium cholate intercalation and sonication from Indonesian natural graphite

    NASA Astrophysics Data System (ADS)

    Panatarani, Camellia; Maulana, Ayu Oktama; Rianto, Anton; Joni, I. Made

    2016-02-01

    Graphite oxide is widely use in renewable energy application such as solar cells, fuel-cells, battery electrodes, catalyst support, etc. This paper reports the preparation of graphite oxide from Indonesian natural graphite by sodium cholate intercalation. The enrichment process of as received graphite with carbon content of 60% was carried out by using acid leaching (HF) method. The enrichment process successfully obtained graphite with carbon content 95.61% with contaminant minerals observed by EDS were magnesium and aluminum. Purified graphite was then intercalated by sodium cholate at various concentration and sonication time. The XRD results shows that preparation with concentration of sodium cholate 2 Wt.% and sonication 10 hours formed a peak characteristic of graphite oxide at 2θ=15°. In addition, the successful oxidation process designated by the C/O ratio of 15.75 observed from EDS and supported by the present of functional C-H and C-O obtained from the FTIR observation. It is concluded that the graphite oxide successfully prepared by intercalation using sodium cholate and sonication.

  11. Families of tessellations of space by elementary polyhedra via retessellations of face-centered-cubic and related tilings.

    PubMed

    Gabbrielli, Ruggero; Jiao, Yang; Torquato, Salvatore

    2012-10-01

    The problem of tiling or tessellating (i.e., completely filling) three-dimensional Euclidean space R(3) with polyhedra has fascinated people for centuries and continues to intrigue mathematicians and scientists today. Tilings are of fundamental importance to the understanding of the underlying structures for a wide range of systems in the biological, chemical, and physical sciences. In this paper, we enumerate and investigate the most comprehensive set of tilings of R(3) by any two regular polyhedra known to date. We find that among all of the Platonic solids, only the tetrahedron and octahedron can be combined to tile R(3). For tilings composed of only congruent tetrahedra and congruent octahedra, there seem to be only four distinct ratios between the sides of the two polyhedra. These four canonical periodic tilings are, respectively, associated with certain packings of tetrahedra (octahedra) in which the holes are octahedra (tetrahedra). Moreover, we derive two families of an uncountably infinite number of periodic tilings of tetrahedra and octahedra that continuously connect the aforementioned four canonical tilings with one another, containing the previously reported Conway-Jiao-Torquato family of tilings [Conway et al., Proc. Natl. Acad. Sci. USA 108, 11009 (2011)] as a special case. For tilings containing infinite planar surfaces, nonperiodic arrangements can be easily generated by arbitrary relative sliding along these surfaces. We also find that there are three distinct canonical periodic tilings of R(3) by congruent regular tetrahedra and congruent regular truncated tetrahedra associated with certain packings of tetrahedra (truncated tetrahedra) in which the holes are truncated tetrahedra (tetrahedra). Remarkably, we discover that most of the aforementioned periodic tilings can be obtained by "retessellating" the well-known tiling associated with the face-centered-cubic lattice, i.e., by combining the associated fundamental tiles (regular tetrahedra and

  12. Graphene prepared by thermal reduction–exfoliation of graphite oxide: Effect of raw graphite particle size on the properties of graphite oxide and graphene

    SciTech Connect

    Dao, Trung Dung; Jeong, Han Mo

    2015-10-15

    Highlights: • Effect of raw graphite particle size on properties of GO and graphene is reported. • Size of raw graphite affects oxidation degree and chemical structure of GO. • Highly oxidized GO results in small-sized but well-exfoliated graphene. • GO properties affect reduction degree, structure, and conductivity of graphene. - Abstract: We report the effect of raw graphite size on the properties of graphite oxide and graphene prepared by thermal reduction–exfoliation of graphite oxide. Transmission electron microscope analysis shows that the lateral size of graphene becomes smaller when smaller size graphite is used. X-ray diffraction analysis confirms that graphite with smaller size is more effectively oxidized, resulting in a more effective subsequent exfoliation of the obtained graphite oxide toward graphene. X-ray photoelectron spectroscopy demonstrates that reduction of the graphite oxide derived from smaller size graphite into graphene is more efficient. However, Raman analysis suggests that the average size of the in-plane sp{sup 2}-carbon domains on graphene is smaller when smaller size graphite is used. The enhanced reduction degree and the reduced size of sp{sup 2}-carbon domains contribute contradictively to the electrical conductivity of graphene when the particle size of raw graphite reduces.

  13. Method of producing exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    DOEpatents

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z.

    2010-11-02

    The present invention provides a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of graphite, graphite oxide, or a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

  14. Formation mechanism of graphite hexagonal pyramids by argon plasma etching of graphite substrates

    NASA Astrophysics Data System (ADS)

    Glad, X.; de Poucques, L.; Bougdira, J.

    2015-12-01

    A new graphite crystal morphology has been recently reported, namely the graphite hexagonal pyramids (GHPs). They are hexagonally-shaped crystals with diameters ranging from 50 to 800 nm and a constant apex angle of 40°. These nanostructures are formed from graphite substrates (flexible graphite and highly ordered pyrolytic graphite) in low pressure helicon coupling radiofrequency argon plasma at 25 eV ion energy and, purportedly, due to a physical etching process. In this paper, the occurrence of peculiar crystals is shown, presenting two hexagonal orientations obtained on both types of samples, which confirms such a formation mechanism. Moreover, by applying a pretreatment step with different time durations of inductive coupling radiofrequency argon plasma, for which the incident ion energy decreases at 12 eV, uniform coverage of the surface can be achieved with an influence on the density and size of the GHPs.

  15. Graphite matrix materials for nuclear waste isolation

    SciTech Connect

    Morgan, W.C.

    1981-06-01

    At low temperatures, graphites are chemically inert to all but the strongest oxidizing agents. The raw materials from which artificial graphites are produced are plentiful and inexpensive. Morover, the physical properties of artificial graphites can be varied over a very wide range by the choice of raw materials and manufacturing processes. Manufacturing processes are reviewed herein, with primary emphasis on those processes which might be used to produce a graphite matrix for the waste forms. The approach, recommended herein, involves the low-temperature compaction of a finely ground powder produced from graphitized petroleum coke. The resultant compacts should have fairly good strength, low permeability to both liquids and gases, and anisotropic physical properties. In particular, the anisotropy of the thermal expansion coefficients and the thermal conductivity should be advantageous for this application. With two possible exceptions, the graphite matrix appears to be superior to the metal alloy matrices which have been recommended in prior studies. The two possible exceptions are the requirements on strength and permeability; both requirements will be strongly influenced by the containment design, including the choice of materials and the waste form, of the multibarrier package. Various methods for increasing the strength, and for decreasing the permeability of the matrix, are reviewed and discussed in the sections in Incorporation of Other Materials and Elimination of Porosity. However, it would be premature to recommend a particular process until the overall multi-barrier design is better defined. It is recommended that increased emphasis be placed on further development of the low-temperature compacted graphite matrix concept.

  16. Research on Graphite Reinforced Glass Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.

    1977-01-01

    This report contains the results obtained in the first twelve months of research under NASA Langley Contract NAS1-14346 for the origination of graphite-fiber reinforced glass matrix composites. Included in the report is a summary of the research by other investigators in this area. The method selected to form the composites consisted of pulling the graphite fiber through a slurry containing powdered glass, winding up the graphite fiber and the glass it picks up on a drum, drying, cutting into segments, loading the tape segment into a graphite die, and hot pressing. During the course of the work, composites were made with a variety of graphite fibers in a C.G.W. 7740 (Pyrex) glass matrix. The graphite fibers used included Hercules HMS, Hercules HTS, Thornel 300S, and Celanese DG-102 and, of these, the Hercules HMS and Celanese DG-102 graphite fibers in C.G.W. 7740 gave the most interesting but widely different results. Hercules HMS fiber in C.G.W. 7740 glass (Pyrex) showed an average four-point flexural strength of 848 MPa or 127,300 psi. As the test temperature was raised from room temperature to 560 C in argon or vacuum, the strength was higher by 50 percent. However, in air, similar tests at 560 C gave a severe loss in strength. These composites also have good thermal cycle properties in argon or vacuum, greatly increased toughness compared to glass, and no loss in strength in a 100 cycle fatigue test. Celanese DG-102 fiber in C.G.W. 7740 glass (Pyrex) had a much lower flexural strength but did not suffer any loss in this strength when samples were heated to 560 C in air for 4 hrs.

  17. Method for producing thin graphite flakes with large aspect ratios

    DOEpatents

    Bunnell, L. Roy

    1993-01-01

    A method for making graphite flakes of high aspect ratio by the steps of providing a strong concentrated acid and heating the graphite in the presence of the acid for a time and at a temperature effective to intercalate the acid in the graphite; heating the intercalated graphite at a rate and to a temperature effective to exfoliate the graphite in discrete layers; subjecting the graphite layers to ultrasonic energy, mechanical shear forces, or freezing in an amount effective to separate the layes into discrete flakes.

  18. Chemical modification of graphite surfaces using chitosan as a mediator

    SciTech Connect

    Hatley, M.E.; Albahadily, F.N.

    1995-12-01

    Several techniques for modifying graphite surfaces have been utilized the last two decades. Some of these techniques have a few limitations which include monolayer coverage and nonspecific binding to the graphite surfaces. In this report, we describe a novel approach to modify graphite surfaces using chitosan. The graphite is coated with an acidic chitosan solution. After drying, a chitosan film is formed on the graphite surfaces. Glutaraldehyde is attached to the chitosan through an amide linkage. The desired modifiers which contain amine groups are then attached to the free end of the glutaraldehyde. Utilization of the modified graphite surfaces in paste electrodes will be discussed.

  19. Influence of Metal-Coated Graphite Powders on Microstructure and Properties of the Bronze-Matrix/Graphite Composites

    NASA Astrophysics Data System (ADS)

    Zhao, Jian-hua; Li, Pu; Tang, Qi; Zhang, Yan-qing; He, Jian-sheng; He, Ke

    2017-02-01

    In this study, the bronze-matrix/x-graphite (x = 0, 1, 3 and 5%) composites were fabricated by powder metallurgy route by using Cu-coated graphite, Ni-coated graphite and pure graphite, respectively. The microstructure, mechanical properties and corrosive behaviors of bronze/Cu-coated-graphite (BCG), bronze/Ni-coated-graphite (BNG) and bronze/pure-graphite (BPG) were characterized and investigated. Results show that the Cu-coated and Ni-coated graphite could definitely increase the bonding quality between the bronze matrix and graphite. In general, with the increase in graphite content in bronze-matrix/graphite composites, the friction coefficients, ultimate density and wear rates of BPG, BCG and BNG composites all went down. However, the Vickers microhardness of the BNG composite would increase as the graphite content increased, which was contrary to the BPG and BCG composites. When the graphite content was 3%, the friction coefficient of BNG composite was more stable than that of BCG and BPG composites, indicating that BNG composite had a better tribological performance than the others. Under all the values of applied loads (10, 20, 40 and 60N), the BCG and BNG composites exhibited a lower wear rate than BPG composite. What is more, the existence of nickel in graphite powders could effectively improve the corrosion resistance of the BNG composite.

  20. Influence of Metal-Coated Graphite Powders on Microstructure and Properties of the Bronze-Matrix/Graphite Composites

    NASA Astrophysics Data System (ADS)

    Zhao, Jian-hua; Li, Pu; Tang, Qi; Zhang, Yan-qing; He, Jian-sheng; He, Ke

    2017-01-01

    In this study, the bronze-matrix/x-graphite (x = 0, 1, 3 and 5%) composites were fabricated by powder metallurgy route by using Cu-coated graphite, Ni-coated graphite and pure graphite, respectively. The microstructure, mechanical properties and corrosive behaviors of bronze/Cu-coated-graphite (BCG), bronze/Ni-coated-graphite (BNG) and bronze/pure-graphite (BPG) were characterized and investigated. Results show that the Cu-coated and Ni-coated graphite could definitely increase the bonding quality between the bronze matrix and graphite. In general, with the increase in graphite content in bronze-matrix/graphite composites, the friction coefficients, ultimate density and wear rates of BPG, BCG and BNG composites all went down. However, the Vickers microhardness of the BNG composite would increase as the graphite content increased, which was contrary to the BPG and BCG composites. When the graphite content was 3%, the friction coefficient of BNG composite was more stable than that of BCG and BPG composites, indicating that BNG composite had a better tribological performance than the others. Under all the values of applied loads (10, 20, 40 and 60N), the BCG and BNG composites exhibited a lower wear rate than BPG composite. What is more, the existence of nickel in graphite powders could effectively improve the corrosion resistance of the BNG composite.

  1. Noise dependence with pile-up in the ATLAS Tile Calorimeter. Pile-up noise studies in the ATLAS TileCal calorimeter

    SciTech Connect

    Araque, J.P.

    2015-07-01

    The Tile Calorimeter, TileCal, is the central hadronic calorimeter of the ATLAS experiment, positioned between the electromagnetic calorimeter and the muon chambers. It comprises alternating layers of steel (as absorber material) and plastic (as active material), known as tiles. Between 2009 and 2012, the LHC has performed better than expected producing proton-proton collisions at a very high rate. These conditions are really challenging when dealing with the energy measurements in the calorimeter since not only the energy from an interesting event will be measured but a component coming from other collisions, which are difficult to distinguish from the interesting one, will also be present. This component is referred to as pile-up noise. Studies carried out to better understand how pile-up affects calorimeter noise under different circumstances are described. (author)

  2. Biases in the SMART-DNA library preparation method associated with genomic poly dA/dT sequences.

    PubMed

    Vardi, Oriya; Shamir, Inbal; Javasky, Elisheva; Goren, Alon; Simon, Itamar

    2017-01-01

    Avoiding biases in next generation sequencing (NGS) library preparation is crucial for obtaining reliable sequencing data. Recently, a new library preparation method has been introduced which has eliminated the need for the ligation step. This method, termed SMART (switching mechanism at the 5' end of the RNA transcript), is based on template switching reverse transcription. To date, there has been no systematic analysis of the additional biases introduced by this method. We analysed the genomic distribution of sequenced reads prepared from genomic DNA using the SMART methodology and found a strong bias toward long (≥12bp) poly dA/dT containing genomic loci. This bias is unique to the SMART-based library preparation and does not appear when libraries are prepared with conventional ligation based methods. Although this bias is obvious only when performing paired end sequencing, it affects single end sequenced samples as well. Our analysis demonstrates that sequenced reads originating from SMART-DNA libraries are heavily skewed toward genomic poly dA/dT tracts. This bias needs to be considered when deciding to use SMART based technology for library preparation.

  3. Technique for Forming Solid D2 and D-T Layers for Shock Timing Experiments at the National Ignition Facility

    DOE PAGES

    Sater, J. D.; Espinosa-Loza, F.; Kozioziemski, B.; ...

    2016-07-11

    Capsule implosion experiments on the National Ignition Facility (NIF) are driven with a carefully tailored laser pulse that delivers a sequence of shocks to the ablator and fuel. In order to ensure the shocks converge at the desired position, the shock strength and velocity are measured in experimental platforms referred to as keyhole targets. We made shock measurements on capsules completely filled with liquid deuterium for the solid deuterium tritide (D-T) layer campaigns. Modeling has been used to extend these results to form an estimate of the shock properties in solid D-T layers. Furthermore, to verify and improve the surrogacymore » of the liquid-filled keyhole measurements, we have developed a technique to form a solid layer inside the keyhole capsule. The layer is typically uniform over a 400-μm-diameter area. This is sufficient to allow direct measurement of the shock velocity. This layering technique has been successfully applied to 13 experiments on the NIF. The technique may also be applicable to fast-igniter experiments since some proposed designs resemble keyhole targets. We discuss our method in detail and give representative results.« less

  4. Characterization of a Thermo Scientific D711 D-T neutron generator located in a low-scatter facility

    SciTech Connect

    Hayes, John W.; Finn, Erin; Greenwood, Larry; Wittman, Rick

    2014-03-01

    A dosimetry experiment used to measure the neutron flux and spectrum of a D-T neutron generator is presented. The D-T generator at Pacific Northwest National Laboratory is installed in the middle of a large room to minimize scatter of neutrons back to the sample. The efficacy of maintaining a pure fast neutron field for the sample is investigated. Twenty-one positions within 13 cm of the neutron source contained foils or wires of Fe, Ni, Al with additional Au, and In monitors at some locations. Spectral adjustment of the neutron flux at each position based on measured reaction rates and theoretical Monte Carlo calculations show that at least 99.1% of the spectrum lies above 110 keV for all measured positions, and neutrons above 14 MeV can account for as much as 91% at locations along the axis of the generator and close to the source. The 14 MeV component drops to 77% in radial positions far from the source. The largest total flux observed was 8.29E+08 n/cm2-s (±1.4%) in the center of the cooling cap, although additional experiments have shown this value could be as high as 1.20E+09 n/cm2-s.

  5. Biases in the SMART-DNA library preparation method associated with genomic poly dA/dT sequences

    PubMed Central

    Shamir, Inbal; Javasky, Elisheva; Goren, Alon; Simon, Itamar

    2017-01-01

    Avoiding biases in next generation sequencing (NGS) library preparation is crucial for obtaining reliable sequencing data. Recently, a new library preparation method has been introduced which has eliminated the need for the ligation step. This method, termed SMART (switching mechanism at the 5′ end of the RNA transcript), is based on template switching reverse transcription. To date, there has been no systematic analysis of the additional biases introduced by this method. We analysed the genomic distribution of sequenced reads prepared from genomic DNA using the SMART methodology and found a strong bias toward long (≥12bp) poly dA/dT containing genomic loci. This bias is unique to the SMART-based library preparation and does not appear when libraries are prepared with conventional ligation based methods. Although this bias is obvious only when performing paired end sequencing, it affects single end sequenced samples as well. Our analysis demonstrates that sequenced reads originating from SMART-DNA libraries are heavily skewed toward genomic poly dA/dT tracts. This bias needs to be considered when deciding to use SMART based technology for library preparation. PMID:28235101

  6. Technique for Forming Solid D2 and D-T Layers for Shock Timing Experiments at the National Ignition Facility

    SciTech Connect

    Sater, J. D.; Espinosa-Loza, F.; Kozioziemski, B.; Mapoles, E. R.

    2016-07-11

    Capsule implosion experiments on the National Ignition Facility (NIF) are driven with a carefully tailored laser pulse that delivers a sequence of shocks to the ablator and fuel. In order to ensure the shocks converge at the desired position, the shock strength and velocity are measured in experimental platforms referred to as keyhole targets. We made shock measurements on capsules completely filled with liquid deuterium for the solid deuterium tritide (D-T) layer campaigns. Modeling has been used to extend these results to form an estimate of the shock properties in solid D-T layers. Furthermore, to verify and improve the surrogacy of the liquid-filled keyhole measurements, we have developed a technique to form a solid layer inside the keyhole capsule. The layer is typically uniform over a 400-μm-diameter area. This is sufficient to allow direct measurement of the shock velocity. This layering technique has been successfully applied to 13 experiments on the NIF. The technique may also be applicable to fast-igniter experiments since some proposed designs resemble keyhole targets. We discuss our method in detail and give representative results.

  7. Study of outgassing and decomposition of space shuttle heat protection tiles, fillers and adhesive

    NASA Technical Reports Server (NTRS)

    Proctor, B. L.; Hoffman, J. H.

    1982-01-01

    The purpose of this project was to determine the chemicals desorbing from the space shuttle heat protection tiles. The original protocol for this project involved direct insertion probe mass spectrometry (DIPMS) analysis of the outgassing products from the tiles. However, this method proved unsatisfactory due to the large number of compounds desorbing from the tiles. A purge and trap technique was then employed to collect and separate the chemicals desorbing from the tiles. The maximum temperature in this analysis was 180 C which is the gas chromatograph fused silica capillary column's temperature limit. The desorption was also carried out at atmospheric pressure with helium as the purge gas. A description of the modified protocol is given. All compounds are tentatively identified.

  8. Heat Transfer Measurement and Modeling in Rigid High-Temperature Reusable Surface Insulation Tiles

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, George R.

    2011-01-01

    Heat transfer in rigid reusable surface insulations was investigated. Steady-state thermal conductivity measurements in a vacuum were used to determine the combined contribution of radiation and solid conduction components of heat transfer. Thermal conductivity measurements at higher pressures were then used to estimate the effective insulation characteristic length for gas conduction modeling. The thermal conductivity of the insulation can then be estimated at any temperature and pressure in any gaseous media. The methodology was validated by comparing estimated thermal conductivities with published data on a rigid high-temperature silica reusable surface insulation tile. The methodology was also applied to the alumina enhanced thermal barrier tiles. Thermal contact resistance for thermal conductivity measurements on rigid tiles was also investigated. A technique was developed to effectively eliminate thermal contact resistance on the rigid tile s cold-side surface for the thermal conductivity measurements.

  9. Construction of DNA nanotubes with controllable diameters and patterns using hierarchical DNA sub-tiles

    NASA Astrophysics Data System (ADS)

    Shi, Xiaolong; Wu, Xiaoxu; Song, Tao; Li, Xin

    2016-08-01

    The design of DNA nanotubes is a promising and hot research branch in structural DNA nanotechnology, which is rapidly developing as a versatile method for achieving subtle nanometer scale materials and molecular diagnostic/curative devices. Multifarious methods have been proposed to achieve varied DNA nanotubes, such as using square tiles and single-stranded tiles, but it is still a challenge to develop a bottom-up assembly way to build DNA nanotubes with different diameters and patterns using certain universal DNA nanostructures. This work addresses the challenge by assembling three types of spatial DNA nanotubes with different diameters and patterns from the so-called ``basic bricks'', i.e., hierarchical DNA sub-tiles. A high processing rate and throughput synthesis of DNA nanotubes are observed and analyzed by atomic force microscopy. Experimental observations and data analysis suggests the stability and controllability of DNA nanotubes assembled by hierarchical DNA sub-tiles.

  10. Catalytic surface effects on contaminated space shuttle tile in a dissociated nitrogen stream

    NASA Technical Reports Server (NTRS)

    Flowers, O. L.; Stewart, D. A.

    1985-01-01

    Visual inspection revealed contamination on the surface of tiles removed from the lower section of the space shuttle orbiter after the second flight of Columbia (STS-2). Possible sources of this contamination and the effect on surface catalycity are presented.

  11. Aerodynamic heating in gaps of thermal protection system tile arrays in laminar and turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Avery, D. E.

    1978-01-01

    An experimental heat-transfer investigation was conducted on two staggered arrays of metallic tiles in laminar and turbulent boundary layers. This investigation was conducted for two purposes. The impingement heating distribution where flow in a longitudinal gap intersects a transverse gap and impinges on a downstream blocking tile was defined. The influence of tile and gap geometries was analyzed to develop empirical relationships for impingement heating in laminar and turbulent boundary layers. Tests were conducted in a high temperature structures tunnel at a nominal Mach number of 7, a nominal total temperature of 1800 K, and free-stream unit Reynolds numbers from 1.0 x 10 million to 4.8 x 10 million per meter. The test results were used to assess the impingement heating effects produced by parameters that include gap width, longitudinal gap length, slope of the tile forward-facing wall, boundary-layer displacement thickness, Reynolds number, and local surface pressure.

  12. Contact pressure distribution during the polishing process of ceramic tiles: A laboratory investigation

    NASA Astrophysics Data System (ADS)

    Sani, A. S. A.; Sousa, F. J. P.; Hamedon, Z.; Azhari, A.

    2016-02-01

    During the polishing process of porcelain tiles the difference in scratching speed between innermost and peripheral abrasives leads to pressure gradients linearly distributed along the radial direction of the abrasive tool. The aim of this paper is to investigate such pressure gradient in laboratory scale. For this purpose polishing tests were performed on ceramic tiles according to the industrial practices using a custom-made CNC tribometer. Gradual wear on both abrasives and machined surface of the floor tile were measured. The experimental results suggested that the pressure gradient tends to cause an inclination of the abraded surfaces, which becomes stable after a given polishing period. In addition to the wear depth of the machined surface, the highest value of gloss and finest surface finish were observed at the lowest point of the worn out surface of the ceramic floor tile corresponding to the point of highest pressure and lowest scratching speed.

  13. Finding minimum spanning trees more efficiently for tile-based phase unwrapping

    NASA Astrophysics Data System (ADS)

    Sawaf, Firas; Tatam, Ralph P.

    2006-06-01

    The tile-based phase unwrapping method employs an algorithm for finding the minimum spanning tree (MST) in each tile. We first examine the properties of a tile's representation from a graph theory viewpoint, observing that it is possible to make use of a more efficient class of MST algorithms. We then describe a novel linear time algorithm which reduces the size of the MST problem by half at the least, and solves it completely at best. We also show how this algorithm can be applied to a tile using a sliding window technique. Finally, we show how the reduction algorithm can be combined with any other standard MST algorithm to achieve a more efficient hybrid, using Prim's algorithm for empirical comparison and noting that the reduction algorithm takes only 0.1% of the time taken by the overall hybrid.

  14. PMR Graphite Engine Duct Development

    NASA Technical Reports Server (NTRS)

    Stotler, C. L.; Yokel, S. A.

    1989-01-01

    The objective was to demonstrate the cost and weight advantages that could be obtained by utilizing the graphite/PMR15 material system to replace titanium in selected turbofan engine applications. The first component to be selected as a basis for evaluation was the outer bypass duct of the General Electric F404 engine. The operating environment of this duct was defined and then an extensive mechanical and physical property test program was conducted using material made by processing techniques which were also established by this program. Based on these properties, design concepts to fabricate a composite version of the duct were established and two complete ducts fabricated. One of these ducts was proof pressure tested and then run successfully on a factory test engine for over 1900 hours. The second duct was static tested to 210 percent design limit load without failure. An improved design was then developed which utilized integral composite end flanges. A complete duct was fabricated and successfully proof pressure tested. The net results of this effort showed that a composite version of the outer duct would be 14 percent lighter and 30 percent less expensive that the titanium duct. The other type of structure chosen for investigation was the F404 fan stator assembly, including the fan stator vanes. It was concluded that it was feasible to utilize composite materials for this type structure but that the requirements imposed by replacing an existing metal design resulted in an inefficient composite design. It was concluded that if composites were to be effectively used in this type structure, the design must be tailored for composite application from the outset.

  15. Air quality comparison between two European ceramic tile clusters

    NASA Astrophysics Data System (ADS)

    Minguillón, M. C.; Monfort, E.; Escrig, A.; Celades, I.; Guerra, L.; Busani, G.; Sterni, A.; Querol, X.

    2013-08-01

    The European ceramic tile industry is mostly concentrated in two clusters, one in Castelló (Spain) and another one in Modena (Italy). Industrial clusters may have problems to accomplish the EU air quality regulations because of the concentration of some specific pollutants and, hence, the feasibility of the industrial clusters can be jeopardised. The present work assesses the air quality in these ceramic clusters in 2008, when the new EU emission regulations where put into force. PM10 samples were collected at two sampling sites in the Modena ceramic cluster and one sampling site in the Castelló ceramic cluster. PM10 annual average concentrations were 12-14 μg m-3 higher in Modena than in Castelló, and were close to or exceeded the European limit. Air quality in Modena was mainly influenced by road traffic and, in a lower degree, the metalmechanical industry, as evidenced by the high concentrations of Mn, Cu, Zn, Sn and Sb registered. The stagnant weather conditions from Modena hindering dispersion of pollutants also contributed to the relatively high pollution levels. In Castelló, the influence of the ceramic industry is evidenced by the high concentrations of Ti, Se, Tl and Pb, whereas this influence is not seen in Modena. The difference in the impact of the ceramic industry on the air quality in the two areas was attributed to: better abatement systems in the spray-drier facilities in Modena, higher coverage of the areas for storage and handling of dusty raw materials in Modena, presence of two open air quarries in the Castelló region, low degree of abatement systems in the ceramic tile kilns in Castelló, and abundance of ceramic frit, glaze and pigment manufacture in Castelló as opposed to scarce manufacture of these products in Modena. The necessity of additional measures to fulfil the EU air quality requirements in the Modena region is evidenced, despite the high degree of environmental measures implemented in the ceramic industry. The Principal

  16. NMR and computational characterization of mitomycin cross-linked to adjacent deoxyguanosines in the minor groove of the d(T-A-C-G-T-A)ter dot d(T-A-C-G-T-A) duplex

    SciTech Connect

    Norman, D.; Sastry, M.; Patel, D.J. ); Live, D. ); Lipman, R.; Tomasz, M. ); Hingerty, B.E. ); Broyde, S. )

    1990-03-20

    Two-dimensional homonuclear and heteronuclear NMR and minimized potential energy calculations have been combined to define the structure of the antitumor agent mitomycin C (MC) cross-linked to deoxyguanosines on adjacent base pairs in the d(T1-A2-C3-G4-T5-A6){center dot}d(T7-A8-C9-G10-T11-A12) duplex. The majority of the mitomycin and nucleic acid protons in the MC-X 6-mer complex have been assigned from through-bond and through-space two-dimensional proton NMR studies in aqueous solution at 5 and 20{degree}C. The C3{center dot}G10 and G4{center dot}C9 base pairs are intact at the cross-link site and stack on each other in the complex. The amino protons of G4 and G10 resonate at 9.36 and 8.87 ppm and exhibit slow exchange with solvent H{sub 2}O. The NMR experimental data establish that the mitomycin is cross-linked to the DNA through the amino groups of G4 and G10 and is positioned in the minor groove. The proton chemical shifts and NOEs establish fraying at the ends of the d(T-A-C-G-T-A) duplex, and this feature is retained on mitomycin cross-linked formation. The NMR distance constraints have been included in minimized potential energy computations on the MC-X 6-mer complex. These computations were undertaken with the nonplanar five-membered ring of mitomycin in each of two pucker orientation. The resulting low-energy structures MX1 and MX2 have the mitomycin cross-linked in a widened minor groove with the chromophore ring system in the vicinity of the G10-T11 step on one of the two strands in the duplex. The experimental evidence supports this model since the H1{prime} of G10 is shifted dramatically upfield and the H1{prime} proton of T11 is shifted dramatically downfield on complex formation.

  17. SiC Armor Tiles via Magnetic Compaction and Pressureless Sintering

    DTIC Science & Technology

    2008-01-27

    Ceramatec, ORNL ,ARMY and UDRI Unclassified 7Cocoa Beach 2008 What is Dynamic Magnetic Compaction? Dynamic Kinetic process High compaction pressure for sub...1Cocoa Beach 2008 SiC Armor Tiles via Magnetic Compaction and Pressureless Sintering B. Chelluri, and E. A. Knoth, IAP Research, Inc. L. P. Franks...TITLE AND SUBTITLE SiC Armor Tiles via Magnetic Compaction and Pressureless Sintering 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  18. Influence of Tile Geometry on the Dynamic Fracture of Silicon Carbide (SiC)

    DTIC Science & Technology

    2014-03-01

    Influence of Tile Geometry on the Dynamic Fracture of Silicon Carbide (SiC) by Jacqueline T. Le and Shane D. Bartus ARL-TR-6861 March...Influence of Tile Geometry on the Dynamic Fracture of Silicon Carbide (SiC) Jacqueline T. Le George Washington University Shane D...5a. CONTRACT NUMBER W911NF-10-2-0076 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Jacqueline T. Le * and Shane D. Bartus 5d

  19. Reconnecting tile drainage to riparian buffer hydrology for enhanced nitrate removal.

    PubMed

    Jaynes, D B; Isenhart, T M

    2014-03-01

    Riparian buffers are a proven practice for removing NO from overland flow and shallow groundwater. However, in landscapes with artificial subsurface (tile) drainage, most of the subsurface flow leaving fields is passed through the buffers in drainage pipes, leaving little opportunity for NO removal. We investigated the feasibility of re-routing a fraction of field tile drainage as subsurface flow through a riparian buffer for increasing NO removal. We intercepted an existing field tile outlet draining a 10.1-ha area of a row-cropped field in central Iowa and re-routed a fraction of the discharge as subsurface flow along 335 m of an existing riparian buffer. Tile drainage from the field was infiltrated through a perforated pipe installed 75 cm below the surface by maintaining a constant head in the pipe at a control box installed in-line with the existing field outlet. During 2 yr, >18,000 m (55%) of the total flow from the tile outlet was redirected as infiltration within the riparian buffer. The redirected water seeped through the 60-m-wide buffer, raising the water table approximately 35 cm. The redirected tile flow contained 228 kg of NO. On the basis of the strong decrease in NO concentrations within the shallow groundwater across the buffer, we hypothesize that the NO did not enter the stream but was removed within the buffer by plant uptake, microbial immobilization, or denitrification. Redirecting tile drainage as subsurface flow through a riparian buffer increased its NO removal benefit and is a promising management practice to improve surface water quality within tile-drained landscapes.

  20. Effect of tillage on macropore flow and phosphorus transport to tile drains

    NASA Astrophysics Data System (ADS)

    Williams, Mark R.; King, Kevin W.; Ford, William; Buda, Anthony R.; Kennedy, Casey D.

    2016-04-01

    Elevated phosphorus (P) concentrations in subsurface drainage water are thought to be the result of P bypassing the soil matrix via macropore flow. The objectives of this study were to quantify event water delivery to tile drains via macropore flow paths during storm events and to determine the effect of tillage practices on event water and P delivery to tiles. Tile discharge, total dissolved P (DP) and total P (TP) concentrations, and stable oxygen and deuterium isotopic signatures were measured from two adjacent tile-drained fields in Ohio, USA during seven spring storms. Fertilizer was surface-applied to both fields and disk tillage was used to incorporate the fertilizer on one field while the other remained in no-till. Median DP concentration in tile discharge prior to fertilizer application was 0.08 mg L-1 in both fields. Following fertilizer application, median DP concentration was significantly greater in the no-tilled field (1.19 mg L-1) compared to the tilled field (0.66 mg L-1), with concentrations remaining significantly greater in the no-till field for the remainder of the monitored storms. Both DP and TP concentrations in the no-till field were significantly related to event water contributions to tile discharge, while only TP concentration was significantly related to event water in the tilled field. Event water accounted for between 26 and 69% of total tile discharge from both fields, but tillage substantially reduced maximum contributions of event water. Collectively, these results suggest that incorporating surface-applied fertilizers has the potential to substantially reduce the risk of P transport from tile-drained fields.