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Sample records for d-t graphite tiles

  1. On residual gas analysis during high temperature baking of graphite tiles

    NASA Astrophysics Data System (ADS)

    Prakash, A. A.; Chaudhuri, P.; Khirwadkar, S.; Chauhan, N.; Raole, P. M.; Reddy, D. Chenna; Saxena, Y. C.

    2008-05-01

    Steady-state Super-conducting Tokamak-1 (SST-1) is a medium size tokamak with major radius of 1.1 m and minor radius of 0.20 m. It is designed for plasma discharge duration of 1000 seconds to obtain fully steady-state plasma operation. Plasma Facing Components (PFC), consisting of divertors, passive stabilizers, baffles and poloidal limiters are also designed to be UHV compatible for steady state operation. All PFC are made up of graphite tiles mechanically attached to the copper alloy substrate. Graphite is one of the preferred first wall armour material in present day tokamaks. High thermal shock resistance and low atomic number of carbon are the most important properties of graphite for this application. High temperature vacuum baking of graphite tiles is the standard process to remove the impurities. Residual Gas Analyzer (RGA) has been used for qualitative and quantitative measurements of released gases from graphite tiles during baking. Surface Analysis of graphite tiles has also been done before and after baking. This paper describes the residual gas analysis during baking and surface analysis of graphite tiles.

  2. Surface impurity removal from DIII-D graphite tiles by boron carbide grit blasting

    SciTech Connect

    Lee, R.L.; Hollerbach, M.A.; Holtrop, K.L.; Kellman, A.G.; Taylor, P.L.; West, W.P.

    1993-11-01

    During the latter half of 1992, the DIII-D tokamak at General Atomics (GA) underwent several modifications of its interior. One of the major tasks involved the removal of accumulated metallic impurities from the surface of the graphite tiles used to line the plasma facing surfaces inside of the tokamak. Approximately 1500 graphite tiles and 100 boron nitride tiles from the tokamak were cleaned to remove the metallic impurities. The cleaning process consisted of several steps: the removed graphite tiles were permanently marked, surface blasted using boron carbide (B{sub 4}C) grit media (approximately 37 {mu}m. diam.), ultrasonically cleaned in ethanol to remove loose dust, and outgassed at 1000{degrees}C. Tests were done using, graphite samples and different grit blaster settings to determine the optimum propellant and abrasive media pressures to remove a graphite layer approximately 40-50 {mu}m deep and yet produce a reasonably smooth finish. EDX measurements revealed that the blasting technique reduced the surface Ni, Cr, and Fe impurity levels to those of virgin graphite. In addition to the surface impurity removal, tritium monitoring was performed throughout the cleaning process. A bubbler system was set up to monitor the tritium level in the exhaust gas from the grit blaster unit. Surface wipes were also performed on over 10% of the tiles. Typical surface tritium concentrations of the tiles were reduced from about 500 dpm/100 cm{sup 2} to less than 80 dpm/100 cm{sup 2} following the cleaning. This tile conditioning, and the installation of additional graphite tiles to cover a high fraction of the metallic plasma facing surfaces, has substantially reduced metallic impurities in the plasma discharges which has allowed rapid recovery from a seven-month machine opening and regimes of enhanced plasma energy confinement to be more readily obtained. Safety issues concerning blaster operator exposure to carcinogenic metals and radioactive tritium will also be addressed.

  3. Induced radioactivity of commercial isotropic graphites for high heat flux tiles

    NASA Astrophysics Data System (ADS)

    Shikama, T.; Kayano, H.; Fujitsuka, M.; Tanabe, T.

    1991-03-01

    It used as the plasma-facing material in the next-generation fusion devices, graphite will induce radioactivity in impurities in the graphite. This study was carried out to evaluate the amount of radiologically significant impurities in commercial isotropic graphite tiles. Special attention is given to the benefits of purification by halogen treatment. Graphite tiles from seven Japanese companies were irradiated in JMTR to neutron fluences up to 7.7 × 10 24 n/m 2 fast ( E > 0.1 MeV) and 1 × 10 25 n/m 2 thermal ( E < 0.683 eV) at about 450 K. Subsequent γ-ray spectroscopy revealed that major impurities contributing to the induced radioactivity are the IIId, IVa, Va elements and rare earth elements. The origins of these impurities are suggested and the effects of halogen treatment on the reduction of these impurities are analyzed.

  4. Recovery of Retained Tritium from Graphite Tile of JT-60U

    SciTech Connect

    Takeishi, Toshiharu; Katayama, Kazunari; Nishikawa, Masabumi; Miya, Naoyuki; Masaki, Kei

    2005-07-15

    Tritium thermal release and full combustion with oxygen were performed on isotropic graphite tiles used for plasma facing material of JT-60U. Approximately 50-80 % of tritium was released by dry argon gas purge and 20-50 % of tritium was released by humid argon gas purge up to 800-1200 deg. C within one day, respectively. Further several percent of tritium was released by full combustion with oxygen. It was experimentally confirmed that all retained tritium is not released by thermal dry gas purge and by use of isotope exchange reaction at high temperature in such a short period. In the full combustion operation, isotropic graphite begins to combust at higher temperature than 650 deg. C, but effective combustion temperature was higher than 700 deg. C. Since it is very difficult to heat the graphite tile attached on the wall of vacuum vessel at higher than 700 deg. C, it is considered to be not easy to recover all the tritium retained in the graphite while in the vacuum vessel.

  5. 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.

  6. 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. PMID:27620063

  7. 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.

  8. 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.

  9. 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

  10. Tiling phosphorene.

    PubMed

    Guan, Jie; Zhu, Zhen; Tománek, David

    2014-12-23

    We present a scheme to categorize the structure of different layered phosphorene allotropes by mapping their nonplanar atomic structure onto a two-color 2D triangular tiling pattern. In the buckled structure of a phosphorene monolayer, we assign atoms in "top" positions to dark tiles and atoms in "bottom" positions to light tiles. Optimum sp3 bonding is maintained throughout the structure when each triangular tile is surrounded by the same number N of like-colored tiles, with 0≤N≤2. Our ab initio density functional calculations indicate that both the relative stability and electronic properties depend primarily on the structural index N. The proposed mapping approach may also be applied to phosphorene structures with nonhexagonal rings and 2D quasicrystals with no translational symmetry, which we predict to be nearly as stable as the hexagonal network.

  11. Self-assembly of 50 bp poly(dA)·poly(dT) DNA on highly oriented pyrolytic graphite via atomic force microscopy observation and molecular dynamics simulation.

    PubMed

    Doi, Kentaro; Takeuchi, Hiroshi; Nii, Ryosuke; Akamatsu, Shingo; Kakizaki, Toshiya; Kawano, Satoyuki

    2013-08-28

    This study has investigated the formation patterns resulting from the self-assembly of deoxyribonucleic acid (DNA) on highly oriented pyrolytic graphite (HOPG), using both experimental and molecular dynamics approaches. Under optimized conditions based on pretreatment of HOPG surface and specific solution concentrations, DNA is found to self-assemble to form various patterned networks. The associated self-assembly mechanism is elucidated using coarse-grained molecular dynamics simulations and fractal dimension analysis. The results of this work demonstrate an effective technique allowing the formation of arrays of negatively charged biomacromolecules on negatively charged HOPG surfaces.

  12. TFTR D-T results

    SciTech Connect

    Meade, D.M.

    1995-03-01

    Temperatures, densities and confinement of deuterium plasmas confined in tokamaks have been achieved within the last decade that are approaching those required for a D-T reactor. As a result, the unique phenomena present in a D-T reactor plasma can now be studied in the laboratory. Recent experiments on the Tokamak Fusion Test Reactor (TFTR) have been the first magnetic fusion experiments to study plasmas with reactor fuel concentrations of tritium. The injection of {approximately} 20 MW of tritium and 14 MW of deuterium neutral beams into the TFTR produced a plasma with a T/D density ratio of {approximately} 1 and yielded a maximum fusion power of {approximately} 9.2 MW. The fusion power density in the core of the plasma was {approximately} 1.8 MW m{sup {minus}3} approximating that expected in a D-T fusion reactor. A TFTR plasma with T/D density ratio of {approximately} 1 was found to have {approximately} 20% higher energy confinement time than a comparable D plasma, indicating a confinement scaling with average ion mass, A, of {tau}{sub E} {approximately} A{sup 0.6}. The core ion temperature increased from 30 keV to 37 keV due to a 35% improvement of ion thermal conductivity. Using the electron thermal conductivity from a comparable deuterium plasma, about 50% of the electron temperature increase from 9 keV to 10.6 keV can be attributed to electron heating by the alpha particles. The {approx} 5% loss of alpha particles was consistent with classical first orbit loss without anomalous effects. Initial measurements have been made of the confined energetic alphas and the resultant alpha ash density.

  13. 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.

  14. Interlocking wettable ceramic tiles

    SciTech Connect

    Tabereaux, Jr., Alton T.; Fredrickson, Guy L.; Groat, Eric; Mroz, Thomas; Ulicny, Alan; Walker, Mark F.

    2005-03-08

    An electrolytic cell for the reduction of aluminum having a layer of interlocking cathode tiles positioned on a cathode block. Each tile includes a main body and a vertical restraining member to prevent movement of the tiles away from the cathode block during operation of the cell. The anode of the electrolytic cell may be positioned about 1 inch from the interlocking cathode tiles.

  15. 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.

  16. Repairing ceramic insulating tiles

    NASA Technical Reports Server (NTRS)

    Dunn, B. R.; Laymance, E. L.

    1980-01-01

    Fused-silica tiles containing large voids or gauges are repaired without adhesives by plug insertion method. Tiles are useful in conduits for high-temperature gases, in furnaces, and in other applications involving heat insulation.

  17. 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…

  18. 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.

  19. Tile densification with TEOS

    NASA Technical Reports Server (NTRS)

    Ecord, G. M.; Schomburg, C.

    1981-01-01

    Densification process uses brushed or sprayed coating of tetraethyl orthosilicate. Liquid is applied and cured in three steps; tile weight increase averages 0.15 g per square centimeter. TEOS liquid is prepared by mixing TEOS with hydrochloric acid and adding marking dye. TEOS application provides variable stiffness, strength, and penetration. Surface of tile shows no buidup and is more durable for additional coatings.

  20. Penrose tilings as model sets

    NASA Astrophysics Data System (ADS)

    Shutov, A. V.; Maleev, A. V.

    2015-11-01

    The Baake construction, based on generating a set of vertices of Penrose tilings as a model set, is refined. An algorithm and a corresponding computer program for constructing an uncountable set of locally indistinguishable Penrose tilings are developed proceeding from this refined construction. Based on an analysis of the parameters of tiling vertices, 62 versions of rhomb combinations at the tiling center are determined. The combinatorial structure of Penrose tiling worms is established. A concept of flip transformations of tilings is introduced that makes it possible to construct Penrose tilings that cannot be implemented in the Baake construction.

  1. Repairing Thermal Tiles

    NASA Technical Reports Server (NTRS)

    Mccain, C. R., Jr.; Feiler, C. W.

    1984-01-01

    Small chips and depression in surfaces of surface insulation tiles repaired using Ludox colloidal silica solution and silica powder. No waiting time necessary between mixing filler and using it. Patch cures quickly without heat being applied.

  2. "Densified" tiles form stronger bonds

    NASA Technical Reports Server (NTRS)

    Dotts, R. L.; Holt, J. W.

    1981-01-01

    Application of colloidal silica more than doubles bond strength of ceramic tile/substrate attachments. "Densification" process strengthens surface where tile attaches to felt strain-isolator pad, redistributing stresses and preventing failures at that point. First, isopropyl alcohol is applied to bottom tile surface. Second, aqueous mixture of cementing colloidal silica and reinforcing ball-milled silica particles is painted on tile. Finally, after drying, tile is rewaterproofed by exposure to vapors or methyltrimethoxysilane and acetic acid.

  3. Tiling Motion Patches.

    PubMed

    Hyun, Kyunglyul; Kim, Manmyung; Hwang, Youngseok; Lee, Jehee

    2013-05-01

    Simulating multiple character interaction is challenging because character actions must be carefully coordinated to align their spatial locations and synchronized with each other. We present an algorithm to create a dense crowd of virtual characters interacting with each other. The interaction may involve physical contacts, such as hand shaking, hugging, and carrying a heavy object collaboratively. We address the problem by collecting deformable motion patches, each of which describes an episode of multiple interacting characters, and tiling them spatially and temporally. The tiling of motion patches generates a seamless simulation of virtual characters interacting with each other in a non-trivial manner. Our tiling algorithm uses a combination of stochastic sampling and deterministic search to address the discrete and continuous aspects of the tiling problem. Our tiling algorithm made it possible to automatically generate highly-complex animation of multiple interacting characters. We achieved the level of complexity far beyond the current state-of-the-art animation techniques could generate, in terms of the diversity of human behaviors and the spatial/temporal density of interpersonal interactions. PMID:23669532

  4. Tiling motion patches.

    PubMed

    Hyun, Kyunglyul; Kim, Manmyung; Hwang, Youngseok; Lee, Jehee

    2013-11-01

    Simulating multiple character interaction is challenging because character actions must be carefully coordinated to align their spatial locations and synchronized with each other. We present an algorithm to create a dense crowd of virtual characters interacting with each other. The interaction may involve physical contacts, such as hand shaking, hugging, and carrying a heavy object collaboratively. We address the problem by collecting deformable motion patches, each of which describes an episode of multiple interacting characters, and tiling them spatially and temporally. The tiling of motion patches generates a seamless simulation of virtual characters interacting with each other in a nontrivial manner. Our tiling algorithm uses a combination of stochastic sampling and deterministic search to address the discrete and continuous aspects of the tiling problem. Our tiling algorithm made it possible to automatically generate highly complex animation of multiple interacting characters. We achieve the level of interaction complexity far beyond the current state of the art that animation techniques could generate, in terms of the diversity of human behaviors and the spatial/temporal density of interpersonal interactions. PMID:24029911

  5. 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.

  6. Tiling Microarray Analysis Tools

    SciTech Connect

    Nix, Davis Austin

    2005-05-04

    TiMAT is a package of 23 command line Java applications for use in the analysis of Affymetrix tiled genomic microarray data. TiMAT enables: 1) Rebuilding the genome annotation for entire tiled arrays (repeat filtering, chromosomal coordinate assignment). 2) Post processing of oligo intensity values (quantile normalization, median scaling, PMMM transformation), 3) Significance testing (Wilcoxon rank sum and signed rank tests, intensity difference and ratio tests) and Interval refinement (filtering based on multiple statistics, overlap comparisons), 4) Data visualization (detailed thumbnail/zoomed view with Interval Plots and data export to Affymetrix's Integrated Genome Browser) and Data reports (spreadsheet summaries and detailed profiles)

  7. Bridging Gaps Between Refractory Tiles

    NASA Technical Reports Server (NTRS)

    Haney, J. W. J.

    1982-01-01

    Excessively large gaps between tiles on Space Shuttle eliminated without time-consuming and costly procedure of removing and replacing tiles. Ceramic tile silver is bonded in gap. Bonded silver prevents airframe under gap from getting too hot during reentry and presents aerodynamically smooth exterior surface.

  8. Latin-Square Tiling

    ERIC Educational Resources Information Center

    Gridgeman, N. T.

    1971-01-01

    The author presents a variation of a tiling problem where each row or column contains a complete set of elements, each diagonal is free of contiguous like elements, and at least one partition exists. These restrictions limit the number of solutions considerably, and methods of solution are subsequently discussed. (CT)

  9. The Shuttle tile story

    NASA Technical Reports Server (NTRS)

    Cooper, P. A.; Holloway, P. F.

    1981-01-01

    The structural problems associated with the reusable thermal protection system (TPS) of the Space Shuttle Orbiter are assessed. The ceramic insulation was placed on the aluminum in the form of about 30,000 tiles over approximately 70% of the Orbiter's exterior. The tiles were bonded to felt pads, and then the tile-pad structure was attached to the aluminum skin. As Orbiter design progressed, it was discovered that the TPS would have to withstand loads greater than initially predicted. The group tensile strength was less than that of the individual components. This was the primary factor contributing to the delay of the first flight. Values are given for Orbiter isotherms during a normal flight as well as the corresponding TPS distribution. The complete TPS assemblage is shown schematically, noting the sequence of assembling the tile components into a testing specimen. It is noted that tensile loads are applied to the strain-isolation path at discrete regions along transverse fiber bundles, causing a 50% reduction in system tensile strength. Procedures for strengthening the interface between the insulation and strain-isolation path are discussed and flight-simulation tests are outlined.

  10. Tiling Microarray Analysis Tools

    2005-05-04

    TiMAT is a package of 23 command line Java applications for use in the analysis of Affymetrix tiled genomic microarray data. TiMAT enables: 1) Rebuilding the genome annotation for entire tiled arrays (repeat filtering, chromosomal coordinate assignment). 2) Post processing of oligo intensity values (quantile normalization, median scaling, PMMM transformation), 3) Significance testing (Wilcoxon rank sum and signed rank tests, intensity difference and ratio tests) and Interval refinement (filtering based on multiple statistics, overlap comparisons),more » 4) Data visualization (detailed thumbnail/zoomed view with Interval Plots and data export to Affymetrix's Integrated Genome Browser) and Data reports (spreadsheet summaries and detailed profiles)« less

  11. 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.

  12. Producing superhydrophobic roof tiles.

    PubMed

    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.

  13. 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.

  14. 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.

  15. 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.

  16. 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)

  17. Detecting Filler Spaces Under Tiles

    NASA Technical Reports Server (NTRS)

    Mende, Paul; Shinkevich, David; Scheuer, John

    1991-01-01

    Eddy-current probe nondestructively and indirectly indicates whether screed present under ceramic tile on aluminum substrate. Transducer coil excites eddy currents in aluminum substrate material. Response appears on oscilloscope or meter. Changes in response indicate spatially abrupt changes in substrate. Intended for use on insulating tiles on Space Shuttle, potential terrestrial applications in nondestructive testing.

  18. Tile Patterns with LOGO--Part II: Tile Patterns from Rep Tiles Using LOGO.

    ERIC Educational Resources Information Center

    Clason, Robert G.

    1991-01-01

    Described is a recursive LOGO method for dissecting polygons into congruent parts (rep tiles) similar to the original polygon, thereby producing unexpected patterns. A list of descriptions for such dissections is included along with suggestions for modifications that allow extended student explorations into tile patterns. (JJK)

  19. 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.

  20. Pentaheptite modifications of the graphite sheet.

    PubMed

    Deza, M; Fowler, P W; Shtogrin, M; Vietze, K

    2000-01-01

    Pentaheptites (three-coordinate tilings of the plane by pentagons and heptagons only) are classified under the chemically motivated restriction that all pentagons occur in isolated pairs and all heptagons have three heptagonal neighbors. They span a continuum between the two lattices exemplified by the boron nets in ThMoB4 (cmm) and YCrB4 (pgg), in analogy with the crossover from cubic-close-packed to hexagonal-close-packed packings in 3D. Symmetries realizable for these pentaheptite layers are three strip groups (periodic in one dimension), p1a1, p112, and p111, and five Fedorov groups (periodic in two dimensions), cmm, pgg, pg, p2, and p1. All can be constructed by simultaneous rotation of the central bonds of pyrene tilings of the graphite sheet. The unique lattice of cmm symmetry corresponds to the previously proposed pentaheptite carbon metal. Analogous pentagon-heptagon tilings on other surfaces including the torus, Klein bottle, and cylinder, face-regular tilings of pentagons and b-gons, and a full characterization of tilings involving isolated pairs and/or triples of pentagons are presented. The Kelvin paradigm of a continuum of structures arising from propagation of two original motifs has many potential applications in 2D and 3D. PMID:11128090

  1. Removable fastener for insulating tiles

    NASA Technical Reports Server (NTRS)

    Brown, J. N.; Cade, D. H.; Logston, H. A.

    1979-01-01

    Fastening device that consists of internally threaded silica insert, silica plug, and molded rubber retainer, seals holes in ceramic tiles securely over wide temperature excursions without cracking from thermal stresses. Device proves useful in high-temperature industrial applications.

  2. Lozenge Tilings and Hurwitz Numbers

    NASA Astrophysics Data System (ADS)

    Novak, Jonathan

    2015-10-01

    We give a new proof of the fact that, near a turning point of the frozen boundary, the vertical tiles in a uniformly random lozenge tiling of a large sawtooth domain are distributed like the eigenvalues of a GUE random matrix. Our argument uses none of the standard tools of integrable probability. In their place, it uses a combinatorial interpretation of the Harish-Chandra/Itzykson-Zuber integral as a generating function for desymmetrized Hurwitz numbers.

  3. 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.

  4. Image Composition Engine for Tiles

    2011-08-22

    The Image Composition Engine for Tiles (lceT) is a high-performance sort-last parallel rendering library. It is designed to be used in parallel applications requiring rendering. The primary purpose of IceT is to be integrated into parallel visualization applications such as ParaView to provide parallel rendering capabilities. The Image Composition Engine for Tiles (lceT) is a high-performance sort-last parallel rendering library. IceT uses a "sort-Iasf' approach to rendering. Each process in a parallel application independently rendersmore » a local piece of geometry. The resulting images are given to IceT, and IceT combines the images together to form a single cohesive image. Ice T is also capable of driving tiled displays, largeformat displays comprising an array of smaller displays. To this end IceT can collect the smaller tile images and organize them such that the entire tiled display can be driven. Ice T takes advantage of spatial coherence in geometry by identifying empty regions of the display and reducing the overall required work.« less

  5. Image Composition Engine for Tiles

    SciTech Connect

    Moreland, Kenneth

    2011-08-22

    The Image Composition Engine for Tiles (lceT) is a high-performance sort-last parallel rendering library. It is designed to be used in parallel applications requiring rendering. The primary purpose of IceT is to be integrated into parallel visualization applications such as ParaView to provide parallel rendering capabilities. The Image Composition Engine for Tiles (lceT) is a high-performance sort-last parallel rendering library. IceT uses a "sort-Iasf' approach to rendering. Each process in a parallel application independently renders a local piece of geometry. The resulting images are given to IceT, and IceT combines the images together to form a single cohesive image. Ice T is also capable of driving tiled displays, largeformat displays comprising an array of smaller displays. To this end IceT can collect the smaller tile images and organize them such that the entire tiled display can be driven. Ice T takes advantage of spatial coherence in geometry by identifying empty regions of the display and reducing the overall required work.

  6. 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.

  7. Composite treatment of ceramic tile armor

    DOEpatents

    Hansen, James G. R.; Frame, Barbara J.

    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.

  8. 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.

  9. 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.

  10. 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.

  11. Application of ultrasonics to space shuttle tiles

    SciTech Connect

    Zimmerman, R.M.; Hogenson, P.A.

    1980-01-01

    Two types of discrete sized ceramic tiles bonded to the outer skin of space vehicles are used for the thermal protection of the Space Shuttle during reentry. Failure of any one of the more than 30,000 tiles on the Space Shuttle could have significant effects. Ultrasonic testing to establish the soundness of the Space Shuttle tiles was evaluated and found to be a viable and valuable method. The method is simple, quick, and has a statistical basis. The testing method involves comparing the measured velocities of finished tiles to velocity-tensile strength relationships obtained for coupons. Acceptance criteria can be developed for the computerized data collection and the status of the tile determined automatically. The method was instituted after many tiles were in existence. It is planned that the method be used to determine tile material quality before any machining or finishing is done in an effort to make the system more efficient. (LCL)

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Water Detection and Removal From Shuttle Tiles

    NASA Astrophysics Data System (ADS)

    Youngquist, Robert C.

    2003-01-01

    Current methods for detecting and removing water from the Space Shuttle tiles have proved inadequate in cases of excessive water exposure. This paper describes two new tools that are currently being introduced to Shuttle processing to supplement the existing methods. A capacitive device has been developed to augment the IR camera method of detecting water in the tiles and a vacuum pump system is being tested as a likely replacement to the heat lamps currently used to dry wet tiles.

  17. Fast Glazing of Alumina/Silica Tiles

    NASA Technical Reports Server (NTRS)

    Creedon, J. F.; Gzowski, E. R.; Wheeler, W. H.

    1986-01-01

    Technique for applying ceramic coating to fibrous silica/alumina insulation tiles prevents cracks and substantially reduces firing time. To reduce thermal stresses in tile being coated, high-temperature, shorttime firing schedule implemented. Such schedule allows coating to mature while substrate remains at relatively low temperature, reducing stress differential between coating and substrate. Technique used to repair tiles with damaged coatings and possibly used in heat-treating objects made of materials having different thermal-expansion coefficients.

  18. 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.

  19. 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.

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

    PubMed

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

    2016-02-01

    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. PMID:26932097

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  2. 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.

  3. Thermal Characterization of TPS Tiles

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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…

  8. 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.

  9. Fibonacci words, hyperbolic tilings and grossone

    NASA Astrophysics Data System (ADS)

    Margenstern, Maurice

    2015-04-01

    In this paper, we study the contribution of the theory of grossone to the study of infinite Fibonacci words, combining this tool with the help of a particular tiling of the hyperbolic plane: the tiling { 7, 3 } , called the heptagrid. With the help of the numeral system based on grossone, we obtain a richer family of infinite Fibonacci words compared with the traditional approach.

  10. Wind-Resistant Filler for Tile Gaps

    NASA Technical Reports Server (NTRS)

    Bellavia, J.; Quigley, I. A.; Callahan, T. S.

    1982-01-01

    Filler developed for gaps between insulating tiles on Space Shuttle finds application in industries that use tiles for thermal or environmental protection. Filler consists of tight-fitting ceramic tubes and fibrous alumina. Combination resists high wind loads while providing requisite heat protection. Quartz-thread stitching holds envelope together.

  11. Shaving Ceramic Tiles To Final Dimensions

    NASA Technical Reports Server (NTRS)

    Shaw, Ernest

    1992-01-01

    Combination of template and routing tool cuts ceramic tiles to final dimensions. Template guides router along precisely defined planes to accurately and uniformly shave chamfers on edge of tiles. Legs of template temporarily bonded to workpiece by double-backed adhesive tape. Adaptable to in-situ final machining of other nominally flat, narrow surfaces.

  12. 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.

  13. Consistency and derangements in brane tilings

    NASA Astrophysics Data System (ADS)

    Hanany, Amihay; Jejjala, Vishnu; Ramgoolam, Sanjaye; Seong, Rak-Kyeong

    2016-09-01

    Brane tilings describe Lagrangians (vector multiplets, chiral multiplets, and the superpotential) of four-dimensional { N }=1 supersymmetric gauge theories. These theories, written in terms of a bipartite graph on a torus, correspond to worldvolume theories on N D3-branes probing a toric Calabi–Yau threefold singularity. A pair of permutations compactly encapsulates the data necessary to specify a brane tiling. We show that geometric consistency for brane tilings, which ensures that the corresponding quantum field theories are well behaved, imposes constraints on the pair of permutations, restricting certain products constructed from the pair to have no one-cycles. Permutations without one-cycles are known as derangements. We illustrate this formulation of consistency with known brane tilings. Counting formulas for consistent brane tilings with an arbitrary number of chiral bifundamental fields are written down in terms of delta functions over symmetric groups.

  14. Consistency and derangements in brane tilings

    NASA Astrophysics Data System (ADS)

    Hanany, Amihay; Jejjala, Vishnu; Ramgoolam, Sanjaye; Seong, Rak-Kyeong

    2016-09-01

    Brane tilings describe Lagrangians (vector multiplets, chiral multiplets, and the superpotential) of four-dimensional { N }=1 supersymmetric gauge theories. These theories, written in terms of a bipartite graph on a torus, correspond to worldvolume theories on N D3-branes probing a toric Calabi-Yau threefold singularity. A pair of permutations compactly encapsulates the data necessary to specify a brane tiling. We show that geometric consistency for brane tilings, which ensures that the corresponding quantum field theories are well behaved, imposes constraints on the pair of permutations, restricting certain products constructed from the pair to have no one-cycles. Permutations without one-cycles are known as derangements. We illustrate this formulation of consistency with known brane tilings. Counting formulas for consistent brane tilings with an arbitrary number of chiral bifundamental fields are written down in terms of delta functions over symmetric groups.

  15. 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.

  16. Lozenge Tilings with Free Boundaries

    NASA Astrophysics Data System (ADS)

    Panova, Greta

    2015-11-01

    We study lozenge tilings of a domain with partially free boundary. In particular, we consider a trapezoidal domain (half-hexagon), s.t. the horizontal lozenges on the long side can intersect it anywhere to protrude halfway across. We show that the positions of the horizontal lozenges near the opposite flat vertical boundary have the same joint distribution as the eigenvalues from a Gaussian Unitary Ensemble (the GUE-corners/minors process). We also prove the existence of a limit shape of the height function, which is also a vertically symmetric plane partition. Both behaviors are shown to coincide with those of the corresponding doubled fixed boundary hexagonal domain. We also consider domains where the different sides converge to {∞} at different rates and recover again the GUE-corners process near the boundary.

  17. Seamless stitching of tile scan microscope images.

    PubMed

    Legesse, F B; Chernavskaia, O; Heuke, S; Bocklitz, T; Meyer, T; Popp, J; Heintzmann, R

    2015-06-01

    For diagnostic purposes, optical imaging techniques need to obtain high-resolution images of extended biological specimens in reasonable time. The field of view of an objective lens, however, is often smaller than the sample size. To image the whole sample, laser scanning microscopes acquire tile scans that are stitched into larger mosaics. The appearance of such image mosaics is affected by visible edge artefacts that arise from various optical aberrations which manifest in grey level jumps across tile boundaries. In this contribution, a technique for stitching tiles into a seamless mosaic is presented. The stitching algorithm operates by equilibrating neighbouring edges and forcing the brightness at corners to a common value. The corrected image mosaics appear to be free from stitching artefacts and are, therefore, suited for further image analysis procedures. The contribution presents a novel method to seamlessly stitch tiles captured by a laser scanning microscope into a large mosaic. The motivation for the work is the failure of currently existing methods for stitching nonlinear, multimodal images captured by our microscopic setups. Our method eliminates the visible edge artefacts that appear between neighbouring tiles by taking into account the overall illumination differences among tiles in such mosaics. The algorithm first corrects the nonuniform brightness that exists within each of the tiles. It then compensates for grey level differences across tile boundaries by equilibrating neighbouring edges and forcing the brightness at the corners to a common value. After these artefacts have been removed further image analysis procedures can be applied on the microscopic images. Even though the solution presented here is tailored for the aforementioned specific case, it could be easily adapted to other contexts where image tiles are assembled into mosaics such as in astronomical or satellite photos.

  18. 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

  19. 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.

  20. Surface damage in TiC coating layers on PDX wall armor tiles

    NASA Astrophysics Data System (ADS)

    Gotoh, Y.; Hoven, H.; Koizlik, K.; Linke, J.; Wallura, E.; Nickel, H.; Kugel, H.; Ulrickson, M.

    1987-02-01

    Surface damage and material redepositions are investigated on 17 graphite tile surface of the PDX wall armor exposed to more than 6500 shots of neutral beam injection (NBI) shine-through and more than 700 shots of direct NBI. Titanium deposition layers, from 0.1 to 7 μm in thickness, redeposited metal droplets, or micro-projections with diameters of less than 2-3 μm and a number density at around 10 8/cm 2, are observed on the tile front faces. Aligned wedge-shaped pits are observed at all micro-projections, which are likely due to shadowed Ti-deposition at redeposited metal droplets by Ti-getter evaporation. Blistering observed in both the TiC coating and Ti-deposition layers is due to plasma shine-through D 0 beam irradiations to a fluence of more than 2 × 10 19 at./cm 2.

  1. 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.

  2. 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.

  3. Aerogel: Tile Composites Toughen a Brittle Superinsulation

    NASA Technical Reports Server (NTRS)

    White, Susan; Rasky, Daniel; Arnold, James O. (Technical Monitor)

    1998-01-01

    Pure aerogels, though familiar in the laboratory for decades as exotic lightweight insulators with unusual physical properties, have had limited industrial applications due to their low strength and high brittleness. Composites formed of aerogels and the ceramic fiber matrices used as space shuttle tiles bypass the fragility of pure aerogels and can enhance the performance of space shuttle tiles in their harsh operating environment. Using a layer of aerogel embedded in a tile may open up a wide range of applications where thermal insulation, gas convection control and mechanical strength matter.

  4. Aerogel: Tile Composites Toughen a Brittle Superinsulation

    NASA Technical Reports Server (NTRS)

    White, Susan; Rasky, Daniel; Arnold, James O. (Technical Monitor)

    1998-01-01

    Pure aerogels, though familiar in the laboratory for decades as exotic lightweight insulators with unusual physical properties, have had limited industrial applications due to their low strength and high brittleness. Composites formed of aerogels and the ceramic fiber matrices like those used as space shuttle tiles bypass the fragility of pure aerogels and can enhance the performance of space shuttle tiles in their harsh operating environment. Using a layer of aerogel embedded in a tile may open up a wide range of applications where thermal insulation, gas convection control and mechanical strength matter.

  5. 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.

  6. 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.

  7. The use of waste ceramic tile in cement production

    SciTech Connect

    Ay, N.; Uenal, M.

    2000-03-01

    In ceramic tile production, because of various reasons, unsold fired products come out. These are waste tiles and only a little part of them are used. Remainings create environmental problems. If these waste tiles are used in cement production, this pollution decreases. In this study, usage of waste tile as pozzolan was studied. Waste tile was added into Portland cement in 25%, 30%, 35%, and 40% weight ratios. Pozzolanic properties of waste tile and setting time, volume stability, particle size, density, specific surface area, and strength of cement including waste tile were investigated. The test results indicated that the waste tiles show pozzolanic properties, and chemical and physical properties of the cement including tile conforms to cement standard up to the addition of 35% waste tile.

  8. Applied physics: The virtues of tiling

    NASA Astrophysics Data System (ADS)

    Fratzl, Peter

    2014-12-01

    A cracked metal film on an elastic substrate has been shown to provide ultrahigh sensitivity in detecting mechanical vibrations. The result draws inspiration from principles of tiling that apply to many biological systems. See Letter p.222

  9. 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.

  10. Manufacture of ceramic tiles from fly ash

    SciTech Connect

    Hnat, J.G.; Mathur, A.; Simpson, J.C.

    1999-08-10

    The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants. 6 figs.

  11. Manufacture of ceramic tiles from fly ash

    SciTech Connect

    Hnat, James G.; Mathur, Akshay; Simpson, James C.

    1999-01-01

    The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants.

  12. 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.

  13. 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

  14. 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.

  15. Heating and ablation of tokamak graphite by pulsed nanosecond Nd-YAG lasers

    SciTech Connect

    Semerok, A.; Fomichev, S. V.; Weulersse, J.-M.; Brygo, F.; Thro, P.-Y.; Grisolia, C.

    2007-04-15

    The results on laser heating and ablation of graphite tiles of thermonuclear tokamaks are presented. Two pulsed Nd-YAG lasers (20 Hz repetition rate, 5 ns pulse duration and 10 kHz repetition rate, 100 ns pulse duration) were applied for ablation measurements. The ablation thresholds (1.0{+-}0.5 J/cm{sup 2} for 5 ns and 2.5{+-}0.5 J/cm{sup 2} for 100 ns laser pulses) were determined for the Tore Supra tokamak graphite tiles (backside) nonexposed to plasma. The high repetition rate Nd-YAG laser (10 kHz, 100 ns pulse duration) and the developed pyrometer system were applied for graphite heating measurements. Some unexpected features of laser heating of the graphite surface were observed. They were explained by the presence of a thin surface layer with the properties different from those of the bulk graphite. The theoretical models of laser heating and near-threshold ablation of graphite with imperfectly adhered layer were developed to interpret the experimental results.

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

    DOEpatents

    Pappano, Peter J; Rogers, Michael R

    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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Approximation of virus structure by icosahedral tilings.

    PubMed

    Salthouse, D G; Indelicato, G; Cermelli, P; Keef, T; Twarock, R

    2015-07-01

    Viruses are remarkable examples of order at the nanoscale, exhibiting protein containers that in the vast majority of cases are organized with icosahedral symmetry. Janner used lattice theory to provide blueprints for the organization of material in viruses. An alternative approach is provided here in terms of icosahedral tilings, motivated by the fact that icosahedral symmetry is non-crystallographic in three dimensions. In particular, a numerical procedure is developed to approximate the capsid of icosahedral viruses by icosahedral tiles via projection of high-dimensional tiles based on the cut-and-project scheme for the construction of three-dimensional quasicrystals. The goodness of fit of our approximation is assessed using techniques related to the theory of polygonal approximation of curves. The approach is applied to a number of viral capsids and it is shown that detailed features of the capsid surface can indeed be satisfactorily described by icosahedral tilings. This work complements previous studies in which the geometry of the capsid is described by point sets generated as orbits of extensions of the icosahedral group, as such point sets are by construction related to the vertex sets of icosahedral tilings. The approximations of virus geometry derived here can serve as coarse-grained models of viral capsids as a basis for the study of virus assembly and structural transitions of viral capsids, and also provide a new perspective on the design of protein containers for nanotechnology applications. PMID:26131897

  2. Structural testing of hollow clay tile units

    SciTech Connect

    Flanagan, R.D. ); Bennett, R.M. . Dept. of Civil Engineering)

    1992-08-05

    This report presents the results of laboratory testing of hollow clay tile masonry units. The testing is part of an ongoing natural phenomena evaluation program of Hollow Clay Tile Wall (HCTW) facilities at the Oak Ridge Y-12 Plant. The primary purpose of these tests is to determine structural properties of unit tiles of the same lot to be used in large-scale laboratory testing of HCTW structures. Light red (terra cotta) clay masonry units, taken from the construction supply yard of were sampled and tested in accordance with applicable ASTM standards. Measurement of size, measurement of void area, initial rate of absorption, compressive strength, and splitting tensile strength procedures were performed. Evaluation of the test results along with comparison to other published clay tile data is provided. Volume 1 of this document contains a description of the testing, a summary of the results, comparison to other published clay tile data, and conclusion drawn from the results. Volume 2 contains the unreduced test data, data reduction software, and quality assurance aspects of the testing.

  3. Tiled WMS/KML Server V2

    NASA Technical Reports Server (NTRS)

    Plesea, Lucian

    2012-01-01

    This software is a higher-performance implementation of tiled WMS, with integral support for KML and time-varying data. This software is compliant with the Open Geospatial WMS standard, and supports KML natively as a WMS return type, including support for the time attribute. Regionated KML wrappers are generated that match the existing tiled WMS dataset. Ping and JPG formats are supported, and the software is implemented as an Apache 2.0 module that supports a threading execution model that is capable of supporting very high request rates. The module intercepts and responds to WMS requests that match certain patterns and returns the existing tiles. If a KML format that matches an existing pyramid and tile dataset is requested, regionated KML is generated and returned to the requesting application. In addition, KML requests that do not match the existing tile datasets generate a KML response that includes the corresponding JPG WMS request, effectively adding KML support to a backing WMS server.

  4. Texture and color features for tile classification

    NASA Astrophysics Data System (ADS)

    Baldrich, Ramon; Vanrell, Maria; Villanueva, Juan J.

    1999-09-01

    In this paper we present the results of a preliminary computer vision system to classify the production of a ceramic tile industry. We focus on the classification of a specific type of tiles whose production can be affected by external factors, such as humidity, temperature, origin of clays and pigments. Variations on these uncontrolled factors provoke small differences in the color and the texture of the tiles that force to classify all the production. A constant and non- subjective classification would allow avoiding devolution from customers and unnecessary stock fragmentation. The aim of this work is to simulate the human behavior on this classification task by extracting a set of features from tile images. These features are induced by definitions from experts. To compute them we need to mix color and texture information and to define global and local measures. In this work, we do not seek a general texture-color representation, we only deal with textures formed by non-oriented colored-blobs randomly distributed. New samples are classified using Discriminant Analysis functions derived from known class tile samples. The last part of the paper is devoted to explain the correction of acquired images in order to avoid time and geometry illumination changes.

  5. 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.

  6. Crosslinking in viral capsids via tiling theory.

    PubMed

    Twarock, R; Hendrix, R W

    2006-06-01

    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.

  7. 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... Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor tile subcategory... manufacture of asbestos floor tile....

  8. 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... Asbestos Floor Tile Subcategory § 427.70 Applicability; description of the asbestos floor tile subcategory... manufacture of asbestos floor tile....

  9. Testing of clay tile infilled frames

    SciTech Connect

    Flanagan, R.D.; Bennett, R.M.; Burdette, E.G.; Goodpasture, D.W.

    1992-08-21

    Several large-scale static tests of clay tile infilled frames were recently conducted. For in-plane racking tests, the effects of cyclic loading, varying frame stiffness, varying infill size, infill offset from frame centerline, and single and double wythe infill construction were investigated. Out-of-plane tests examined infilled frame response to inertial loadings and inter-story drift loadings. Multiple loadings were performed to determine in-plane strength and stiffness degradation from both out-of-plane loadings. To determine constitutive properties of the infills, prism compression, mortar compression and various unit tile tests were performed.

  10. Dynamical implications of Viral Tiling Theory.

    PubMed

    ElSawy, K M; Taormina, A; Twarock, R; Vaughan, L

    2008-05-21

    The Caspar-Klug classification of viruses whose protein shell, called viral capsid, exhibits icosahedral symmetry, has recently been extended to incorporate viruses whose capsid proteins are exclusively organised in pentamers. The approach, named 'Viral Tiling Theory', is inspired by the theory of quasicrystals, where aperiodic Penrose tilings enjoy 5-fold and 10-fold local symmetries. This paper analyses the extent to which this classification approach informs dynamical properties of the viral capsids, in particular the pattern of Raman active modes of vibrations, which can be observed experimentally. PMID:18353372

  11. 2. MORAVIAN POTTERY AND TILE WORKS, VIEW FROM THE SOUTHWEST. ...

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

    2. MORAVIAN POTTERY AND TILE WORKS, VIEW FROM THE SOUTHWEST. INDIAN HOUSE WING AT THE LEFT. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  12. Small form factor full parallax tiled light field display

    NASA Astrophysics Data System (ADS)

    Alpaslan, Zahir Y.; El-Ghoroury, Hussein S.

    2015-03-01

    With the recent introduction of Ostendo's Quantum Photonic Imager (QPI) display technology, a very small pixel pitch, emissive display with high brightness and low power consumption became available. We used QPI's to create a high performance light field display tiles with a very small form factor. Using 8 of these QPI light field displays tiled in a 4x2 array we created a tiled full parallax light field display. Each individual light field display tile combines custom designed micro lens array layers with monochrome green QPIs. Each of the light field display tiles can address 1000 x 800 pixels placed under an array of 20 x 16 lenslets with 500 μm diameters. The light field display tiles are placed with small gaps to create a tiled display of approximately 46 mm (W) x 17 mm (H) x 2 mm (D) in mechanical dimensions. The prototype tiled full parallax light field display demonstrates small form factor, high resolution and focus cues.

  13. INTERIOR VIEW OF BATHROOM 1 SHOWING THE MOSAICPATTERN TILE FLOOR. ...

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

    INTERIOR VIEW OF BATHROOM 1 SHOWING THE MOSAIC-PATTERN TILE FLOOR. CERAMIC TILE WAINSCOT, AND CERAMIC ACCESSORIES. VIEW FACING NORTH. - Hickam Field, Officers' Housing Type H, 208 Sixth Street, Honolulu, Honolulu County, HI

  14. INTERIOR VIEW OF BATHROOM 1. SHOWING ORIGINAL MOSAIC PATTERN TILE ...

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

    INTERIOR VIEW OF BATHROOM 1. SHOWING ORIGINAL MOSAIC PATTERN TILE FLOOR, TILE WAINSCOT AND SHOWER SURROUND, AND CERAMIC ACCESSORIES. VIEW FACING EAST. - Hickam Field, Officers' Housing Type J, 701 Beard Street, Honolulu, Honolulu County, HI

  15. 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)

  16. Hydrogen and deuterium in graphite limiters from TFTR, PDX and PLT

    SciTech Connect

    Wampler, W.R.; Doyle, B.L.; Pontau, A.E.

    1986-01-01

    Retention of hydrogen isotopes in graphite limiters impacts plasma fueling, isotope changeover rates and tritium inventory in fusion reactors. This paper describes measurements of the amount of euterium (D) in graphite tiles from the TFTR limiter, and in graphite limiters from PDX and PLT, after extended exposure to high power D plasmas. D concentrations decreased abruptly over the first micron and fell to the bulk value of 4 to 13 atomic, ppM beyond 40 microns from the exposed surface. The average near-surface aeral densities of D on the TFTR tiles was 10/sup 17/ D/cm/sup 2/. The total amount of near-surface D in TFTR limiters estimated using this value is larger than the amount of D in a plasma but small compared to the allowed tritium inventory. The D concentrations found in the bulk are large enough to be an important factor for tritium inventory. The 1 at. % of hydrogen (H) found in the limiters and in graphite not exposed to plasma may be an important source of hydrogen to the plasma. We discuss the influence of the H and D concentrations found in the bulk of graphite on tritium inventory estimates and hydrogen isotope changeover rates.

  17. Hydrogen and deuterium in graphite limiters from TFTR, PDX and PLT

    NASA Astrophysics Data System (ADS)

    Wampler, W. R.; Doyle, B. L.; Pontau, A. E.

    1987-02-01

    Retention of hydrogen isotopes in graphite limiters impacts plasma fueling, isotope changeover rates and tritium inventory in fusion reactors. This paper describes measurements of the amount of deuterium (D) in graphite tiles from the TFTR limiter, and in graphite limiters from PDX and PLT, after extended exposure to high power D plasmas. D concentrations decreased abruptly over the first micron and fell to the bulk value of 4 to 13 atomic ppm beyond 40 microns from the exposed surface. The average near-surface areal densities of D on the TFTR tiles was 10 17 D/cm 2. The total amount of near-surface D in TFTR limiters estimated using this value is larger than the amount of D in a plasma but small compared to the allowed tritium inventory. The D concentrations found in the bulk are large enough to be an important factor for tritium inventory. The 1 at.% of hydrogen (H) found in the limiters and in graphite not exposed to plasma may be an important source of hydrogen to the plasma. We discuss the influence of the H and D concentrations found in the bulk of graphite on tritium inventory estimates and hydrogen isotope changeover rates.

  18. 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.

  19. 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)

  20. 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

  1. 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

  2. Improving Emittance of High-Temperature Insulating Tile

    NASA Technical Reports Server (NTRS)

    Gzowski, E. R.

    1985-01-01

    Simple addition to ceramic insulating tiles provides backup properties that minimize transfer of heat through tiles when their surfaces become damaged. Addition of 3 percent by weight of 320- or 600-grit silicon carbide powder to ceramic during production results in impregnated tile material that resists overheating. Silicon carbide increases emittance and decreases transmittance of ceramic.

  3. Installation of Ceramic Tile: Residential Thin-Set Methods.

    ERIC Educational Resources Information Center

    Short, Sam

    This curriculum guide contains materials for use in teaching a course on residential thin-set methods of tile installation. Covered in the individual units are the following topics: the tile industry; basic math; tools; measurement; safety in tile setting; installation materials and guidelines for their use; floors; counter tops and backsplashes;…

  4. Solar-energy treatment of ceramic tile. Final report

    SciTech Connect

    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 45/sup 0/ 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 tiles were subjected to standard ceramic testing procedures to determine: flatness, modulus of rupture, water absorption, porosity, bulk density, apparent specific gravity, percent linear thermal expansion and crystalline phases present in the fired bodies. These data were compared with the same data for commercial fired tiles from the same batch of raw materials. The glazed tile surfaces were compared with commercially fired tile for reflectance and color match. The major problems encountered were: cracking by thermal shock, and uneven shrinkage and glaze maturity across individual tile. The cavity also failed to provide even heating at all eight tile positions. An alternate air heat exchanger system is recommended to fire the tile by convection rather than direct radiation.

  5. 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.

  6. 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.

  7. 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.

  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. Graphite design handbook

    SciTech Connect

    Ho, F.H.

    1988-09-01

    The objectives of the Graphite Design Handbook (GDH) are to provide and maintain a single source of graphite properties and phenomenological model of mechanical behavior to be used for design of MHTGR graphite components of the Reactor System, namely, core support, permanent side reflector, hexagonal reflector elements, and prismatic fuel elements; to provide a single source of data and material models for use in MHTGR graphite component design, performance, and safety analyses; to present properties and equations representing material models in a form which can be directly used by the designer or analyst without the need for interpretation and is compatible with analytical methods and structural criteria used in the MHTGR project, and to control the properties and material models used in the MHTGR design and analysis to proper Quality Assurance standards and project requirements. The reference graphite in the reactor internal components is the nuclear grade 2020. There are two subgrades of interest, the cylinder nuclear grade and the large rectangular nuclear grade. The large rectangular nuclear grade is molded in large rectangular blocks. It is the reference material for the permanent side reflector and the central column support structure. The cylindrical nuclear grade is isostatically pressed and is intended for use as the core support component. This report gives the design properties for both H-451 and 2020 graphite as they apply to their respective criteria. The properties are presented in a form for design, performance, and safety calculations that define or validate the component design. 103 refs., 20 figs., 19 tabs.

  10. Lozenge Tilings, Glauber Dynamics and Macroscopic Shape

    NASA Astrophysics Data System (ADS)

    Laslier, Benoît; Toninelli, Fabio Lucio

    2015-09-01

    We study the Glauber dynamics on the set of tilings of a finite domain of the plane with lozenges of side 1/ L. Under the invariant measure of the process (the uniform measure over all tilings), it is well known (Cohn et al. J Am Math Soc 14:297-346, 2001) that the random height function associated to the tiling converges in probability, in the scaling limit , to a non-trivial macroscopic shape minimizing a certain surface tension functional. According to the boundary conditions, the macroscopic shape can be either analytic or contain "frozen regions" (Arctic Circle phenomenon Cohn et al. N Y J Math 4:137-165, 1998; Jockusch et al. Random domino tilings and the arctic circle theorem, arXiv:math/9801068, 1998). It is widely conjectured, on the basis of theoretical considerations (Henley J Statist Phys 89:483-507, 1997; Spohn J Stat Phys 71:1081-1132, 1993), partial mathematical results (Caputo et al. Commun Math Phys 311:157-189, 2012; Wilson Ann Appl Probab 14:274-325, 2004) and numerical simulations for similar models (Destainville Phys Rev Lett 88:030601, 2002; cf. also the bibliography in Henley (J Statist Phys 89:483-507, 1997) and Wilson (Ann Appl Probab 14:274-325, 2004), that the Glauber dynamics approaches the equilibrium macroscopic shape in a time of order L 2+ o(1). In this work we prove this conjecture, under the assumption that the macroscopic equilibrium shape contains no "frozen region".

  11. 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…

  12. 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.

  13. Computer-controlled optical scanning tile microscope.

    PubMed

    Wang, C; Shumyatsky, P; Zeng, F; Zevallos, M; Alfano, R R

    2006-02-20

    A new type of computer-controlled optical scanning, high-magnification imaging system with a large field of view is described that overcomes the commonly believed incompatibility of achieving both high magnification and a large field of view. The new system incorporates galvanometer scanners, a CCD camera, and a high-brightness LED source for the fast acquisition of a large number of a high-resolution segmented tile images with a magnification of 800x for each tile. The captured segmented tile images are combined to create an effective enlarged view of a target totaling 1.6 mm x 1.2 mm in area. The speed and sensitivity of the system make it suitable for high-resolution imaging and monitoring of a small segmented area of 320 microm x 240 microm with 4 microm resolution. Each tile segment of the target can be zoomed up without loss of the high resolution. This new microscope imaging system gives both high magnification and a large field of view. This microscope can be utilized in medicine, biology, semiconductor inspection, device analysis, and quality control. PMID:16523776

  14. 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…

  15. Performance of the ATLAS Tile Calorimeter

    NASA Astrophysics Data System (ADS)

    Heelan, Louise; ATLAS Collaboration

    2015-06-01

    The ATLAS Tile hadronic calorimeter (TileCal) provides highly-segmented energy measurements of incoming particles. It is a key detector for the measurement of hadrons, jets, tau leptons and missing transverse energy. It is also useful for identification and reconstruction of muons due to good signal to noise ratio. The calorimeter consists of thin steel plates and 460,000 scintillating tiles configured into 5000 cells, each viewed by two photomultipliers. The calorimeter response and its readout electronics is monitored to better than 1% using radioactive source, laser and charge injection systems. The calibration and performance of the calorimeter have been established through test beam measurements, cosmic ray muons and the large sample of proton-proton collisions acquired in 2011 and 2012. Results on the calorimeter performance are presented, including the absolute energy scale, timing, noise and associated stabilities. The results demonstrate that the Tile Calorimeter has performed well within the design requirements and it has given essential contribution to reconstructed objects and physics results. In addition, the data quality procedures used during the LHC data-taking are described and the outcome of the detector consolidation in the maintenance period is also presented.

  16. Radioactivity level in Chinese building ceramic tile.

    PubMed

    Xinwei, L

    2004-01-01

    The activity concentrations of (226)Ra, (232)Th and (40)K have been determined by gamma ray spectrometry. The concentrations of (226)Ra, (232)Th and (40)K range from 158.3 to 1087.6, 91.7 to 1218.4, and 473.8 to 1031.3 Bq kg(-1) for glaze, and from 63.5 to 131.4, 55.4 to 106.5, and 386.7 to 866.8 Bq kg(-1) for ceramic tile, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and with the typical world values. The radium equivalent activities (Ra(eq)), external hazard index (H(ex)) and internal hazard index (H(in)) associated with the radionuclides were calculated. The Ra(eq) values of all ceramic tiles are lower than the limit of 370 Bq kg(-1). The values of H(ex) and H(in) calculated according to the Chinese criterion for ceramic tiles are less than unity. The Ra(eq) value for the glaze of glazed tile collected from some areas are >370 Bq kg(-1).

  17. Chemical response of lithiated graphite with deuterium irradiation

    SciTech Connect

    Taylor, C. N.; Heim, B.; Allain, J. P.

    2011-03-01

    Lithium wall conditioning has been found to enhance plasma performance for graphite walled fusion devices such as TFTR, CDX-U, T-11M, TJ-II and NSTX. Among observed plasma enhancements is a reduction in edge density and reduced deuterium recycling. The mechanism by which lithiated graphite retains deuterium is largely unknown. Under controlled laboratory conditions, X-ray photoelectron spectroscopy (XPS) is used to observe the chemical changes that occur on ATJ graphite after lithium deposition. The chemical state of lithiated graphite is found to change upon deuterium irradiation indicating the formation Li-O-D, manifest at 532.9 {+-} 0.6 eV. Lithium-deuterium interactions are also manifest in the C 1s photoelectron energy range and show Li-C-D interactions at 291.2 {+-} 0.6 eV. Post-mortem NSTX tiles that have been exposed to air upon extraction are cleaned and examined, revealing the chemical archaeology that formed during NSTX operations. XPS spectra show strong correlation ({+-} 0.3 eV) in Li-O-D and Li-O peaks from post-mortem and control experiments, thus validating offline experiments. We report findings that show that deuterium is found to interact with lithium after lithium has already reacted with carbon and oxygen.

  18. 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.

  19. Covering shapes with tiles: Primary students' visualisation and drawing

    NASA Astrophysics Data System (ADS)

    Owens, Kay; Outhred, Lynne

    1998-12-01

    Students' early area concepts were investigated by an analysis of responses to a worksheet of items that involved visualising the tiling of given figures. Students in Years 2 and 4 in four schools attempted the items on three occasions and some of the students completed ten classroom spatial activities. Half the students had difficulty visualising the tiling of shapes, but students who participated in spatial activities were generally more successful in determining the number of tiles that would cover a shape. Students' drawings indicated a varying awareness of structural features such as alignment and tile size. Students who drew the tilings were more likely to be successful on the items involving trapezia. The tiling items were part of a test of spatial thinking, Thinking About 2D Shapes, and scores on the overall test were very highly correlated with results for the tiling items.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Anosov Diffeomorphisms and {γ}-Tilings

    NASA Astrophysics Data System (ADS)

    Almeida, João P.; Pinto, Alberto A.

    2016-07-01

    We consider a toral Anosov automorphism {G_γ:{mathbb{T}}_γto{mathbb{T}}_γ} given by {G_γ(x,y)=(ax+y,x)} in the { < v,w > } base, where {ainmathbb{N} backslash\\{1\\}}, {γ=1/(a+1/(a+1/ldots))}, {v=(γ,1)} and {w=(-1,γ)} in the canonical base of {{mathbb{R}}^2} and {{mathbb{T}}_γ={mathbb{R}}^2/(v{mathbb{Z}} × w{mathbb{Z}})}. We introduce the notion of {γ}-tilings to prove the existence of a one-to-one correspondence between (i) marked smooth conjugacy classes of Anosov diffeomorphisms, with invariant measures absolutely continuous with respect to the Lebesgue measure, that are in the isotopy class of {G_γ}; (ii) affine classes of {γ}-tilings; and (iii) {γ}-solenoid functions. Solenoid functions provide a parametrization of the infinite dimensional space of the mathematical objects described in these equivalences.

  8. 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.

  9. Firing ceramic tiles in solar energy equipment

    SciTech Connect

    Pasichnyi, V.V.; Berezhetskaya, V.Ya.; Chop, Yu.I.; Kashket, G.I.

    1987-03-01

    In the interest of satisfying the growing demand for glazed ceramic tiles and conserving the natural gas ordinarily used to fire them, the authors assess the feasibility of using a solar kiln for the process. Their design incorporates a parabolic reflector and a tracking system to continuously focus radiant solar energy on the tile. Their energy analysis includes such factors as solar thermal input, radiant heat transfer, and heat flow, the relationship between the firing time and the heat flow density, and the surface quality of the glaze and colorizer. Their results indicate that when the heat flow density rises above a level at which the specific expenditure of heat is no longer dependent on the color of the pigment, this expenditure or input comes to a quarter of what is currently needed using existing technologies and fuels.

  10. NASA TileWorld Simulator Program

    NASA Technical Reports Server (NTRS)

    Philips, Andrew; Bresina, John; Drummond, Mark

    1993-01-01

    NASA TileWorld (NTW) computer program formulated to further research on planning, scheduling, and control problems. Designed to focus on three particular attributes of real-world problems: exogenous events, uncertain outcomes of actions, and metric time. Written specifically for use by NASA, NTW modified easily to act as software base for other simulated environments. Written in Allegro Common Lisp for Sun-3-(TM) and Sun-4-series(TM) computers running SunOS(TM).

  11. 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.

  12. Laser printing of enamels on tiles

    NASA Astrophysics Data System (ADS)

    Fernández-Pradas, J. M.; Restrepo, J. W.; Gómez, M. A.; Serra, P.; Morenza, J. L.

    2007-07-01

    A Nd:YAG laser beam is used as a tool to print patterns of coloured enamels on tile substrates. For this, the laser beam is scanned over a layer of raw enamel previously sprayed on the tile surface. The possibility to focus the laser energy to heat a small zone without affecting the rest of the piece presents some advantages in front of traditional furnace techniques in which the whole piece has to be heated; among them, energy saving and the possibility to apply enamels with higher melting temperatures than those of the substrate. In this work, we study the effects of laser irradiation of a green enamel, based in chromium oxide pigment and lead frit, deposited on a white tile substrate. Lines obtained with different combinations of laser beam power and scan speeds were investigated with the aim to optimize the process from the point of view of the quality of the patterns. For this purpose, the morphology of the lines and their cross-sections is studied. The results show that lines with good visual properties can be printed with the laser. The characteristics of the marked lines were found to be directly related with the accumulated energy density delivered. Moreover, there is a linear relationship between the accumulated energy density and the volume of melted material. A minimum accumulated energy density is required to melt a shallow zone of the glazed substrate to allow the adhesion of the enamelled lines.

  13. 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.

  14. Tritium Removal from JET and TFTR Tiles by a Scanning Laser

    SciTech Connect

    C.H. Skinner; N. Bekris; J.P. Coad; C.A. Gentile; M. Glugla

    2002-05-30

    Fast and efficient tritium removal is needed for future D-T machines with carbon plasma-facing components. A novel method for tritium release has been demonstrated on co-deposited layers on tiles retrieved from the Tokamak Fusion Test Reactor (TFTR) and from the Joint European Torus (JET). A scanning continuous wave neodymium laser beam was focused to =100 W/mm2 and scanned at high speed over the co-deposits, heating them to temperatures =2000 C for about 10 ms in either air or argon atmospheres. Fiber optic coupling between the laser and scanner was implemented. Up to 87% of the co-deposited tritium was thermally desorbed from the JET and TFTR samples. This technique appears to be a promising in-situ method for tritium removal in a next-step D-T device as it avoids oxidation, the associated de-conditioning of the plasma-facing surfaces, and the expense of processing large quantities of tritium oxide.

  15. 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.

  16. Properties of ceramic tiles made from bio-treated bodies for internal wall tiles

    SciTech Connect

    Sidorova, V.A.; Biryukova, O.V.; Pyatkova, Z.P.; Solnyshkina, T.N.; Vainberg, S.N.

    1986-07-01

    The influence of bio-treatment on the structure and properties of internal wall tiles was tested. Nepheline-dolomite body D-8 was used for the manufacturing of the tiles. At the stage in which the clays and nonplastics are blended in the mixing tank with the slip, a suspension of silicate bacteria was added. It was found that the most marked change begins after three days. Tables show the fluidity of the experimental and control slips and the relationship between the density of the pressed specimens and the pressing force. The viscosity of the slip with the addition of the electrolyte is much lower than the viscosity of the control slip. The introduction of biotechnology in the production of ceramic tiles for internal wall facing will reduce the fuel consumption by 8-10%, reduce the cost of installing rollers made from scarce steels, reduce the amount of loss, and increase the grading of the product.

  17. 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

  18. 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.

  19. 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.

  20. Graphite technology development plan

    SciTech Connect

    1986-07-01

    This document presents the plan for the graphite technology development required to support the design of the 350 MW(t) Modular HTGR within the US National Gas-Cooled Reactor Program. Besides descriptions of the required technology development, cost estimates, and schedules, the plan also includes the associated design functions and design requirements.

  1. 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)

  2. (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.

  3. Deconstructing graphite: graphenide solutions.

    PubMed

    Pénicaud, Alain; Drummond, Carlos

    2013-01-15

    Growing interest in graphene over past few years has prompted researchers to find new routes for producing this material other than mechanical exfoliation or growth from silicon carbide. Chemical vapor deposition on metallic substrates now allows researchers to produce continuous graphene films over large areas. In parallel, researchers will need liquid, large scale, formulations of graphene to produce functional graphene materials that take advantage of graphene's mechanical, electrical, and barrier properties. In this Account, we describe methods for creating graphene solutions from graphite. Graphite provides a cheap source of carbon, but graphite is insoluble. With extensive sonication, it can be dispersed in organic solvents or water with adequate additives. Nevertheless, this process usually creates cracks and defects in the graphite. On the other hand, graphite intercalation compounds (GICs) provide a means to dissolve rather than disperse graphite. GICS can be obtained through the reaction of alkali metals with graphite. These compounds are a source of graphenide salts and also serve as an excellent electronic model of graphene due to the decoupling between graphene layers. The graphenide macroions, negatively charged graphene sheets, form supple two-dimensional polyelectrolytes that spontaneously dissolve in some organic solvents. The entropic gain from the dissolution of counterions and the increased degrees of freedom of graphene in solution drives this process. Notably, we can obtain graphenide solutions in easily processable solvents with low boiling points such as tetrahydrofuran or cyclopentylmethylether. We performed a statistical analysis of high resolution transmission electronic micrographs of graphene sheets deposited on grids from GICs solution to show that the dissolved material has been fully exfoliated. The thickness distribution peaks with single layers and includes a few double- or triple-layer objects. Light scattering analysis of the

  4. Design, fabrication, and tests of a metallic shell tile thermal protection system for space transportation

    NASA Technical Reports Server (NTRS)

    Macconochie, Ian O.; Kelly, H. Neale

    1989-01-01

    A thermal protection tile for earth-to-orbit transports is described. The tiles consist of a rigid external shell filled with a flexible insulation. The tiles tend to be thicker than the current Shuttle rigidized silica tiles for the same entry heat load but are projected to be more durable and lighter. The tiles were thermally tested for several simulated entry trajectories.

  5. Military Curriculum Materials for Vocational and Technical Education. Builders School, Ceramic Tile Setting 3-9.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This course, for individualized or group instruction on ceramic tile setting, was developed from military sources for use in vocational education. The course provides students with skills in mortar preparation, surface preparation, tile layout planning, tile setting, tile cutting, and the grouting of tile joints. Both theory and shop assignments…

  6. Design optimization methods for genomic DNA tiling arrays.

    PubMed

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

    2006-02-01

    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.

  7. 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

  8. Intrinsic DNA curvature of double-crossover tiles

    NASA Astrophysics Data System (ADS)

    Kim, Seungjae; Kim, Junghoon; Qian, Pengfei; Shin, Jihoon; Amin, Rashid; Ahn, Sang Jung; LaBean, Thomas H.; Kim, Moon Ki; Park, Sung Ha

    2011-06-01

    A theoretical model which takes into account the structural distortion of double-crossover DNA tiles has been studied to investigate its effect on lattice formation sizes. It has been found that a single vector appropriately describes the curvature of the tiles, of which a higher magnitude hinders lattice growth. In conjunction with these calculations, normal mode analysis reveals that tiles with relative higher frequencies have an analogous effect. All the theoretical results are shown to be in good agreement with experimental data.

  9. On the perturbation of a uniform tiling with resistors

    NASA Astrophysics Data System (ADS)

    Owaidat, M. Q.; Asad, J. H.; Tan, Zhi-Zhong

    2016-06-01

    The perturbation of a uniformly tiled resistor network by adding an edge (a resistor) to the network is considered. The two-point resistance on the perturbed tiling in terms of that on the perfect tiling is obtained using Green’s function. Some theoretical results are presented for an infinite modified square lattice. These results are confirmed experimentally by constructing an actual resistor lattice of size 13 × 13.

  10. Probing the energetics of oligo(dT).poly(dA) by laser cross-linking.

    PubMed Central

    Mesner, L D; Hockensmith, J W

    1992-01-01

    Experimentally determined changes in free energy (delta G(o)) for thymine-thymine interactions occurring in oligo(dT).poly(dA) are dependent on the method used for preparation of the double-stranded template. A rapid laser cross-linking technique was used to examine the equilibrium between oligomers of (dT) bound to either poly(dA) or poly(rA). The single-pulse (4-6 nsec) ultraviolet laser excitation of these polynucleotides causes pyrimidine dimer formation between contiguous oligo(dT) molecules, resulting in a "ligation" of the oligomers. Analysis of the resulting data using standard binding isotherms allowed determination of the degree of cooperativity existing between oligomers. Using the cooperativity, delta G(o), delta H(o), and delta S(o) are calculated, thereby providing thermodynamic parameters for this interaction. The measured cooperativity of oligo(dT) molecule interactions allows direct calculation of the number of 3' ends available as nicked structures or the number of 3' ends associated with gaps for oligo(dT).poly(dA) when used as a substrate for DNA synthesis. Images PMID:1557354

  11. Determination of the D2 parameter for (d,t) reactions

    NASA Astrophysics Data System (ADS)

    Knutson, L. D.; Colby, P. C.; Hichwa, B. P.

    1981-08-01

    Measurements of the tensor analyzing powers have been obtained for (d-->,t) reactions on 91Zr, 118Sn, 119Sn, and 208Pb for deuteron energies both above and below the Coulomb barrier. The measurements are sensitive to the presence of D-state components in the triton wave function and allow the determination of a parameter D2. This parameter is a measure of the importance of triton wave function components in which one neutron moves with orbital angular momentum L=2 relative to the deuteron center of mass. Values of D2 are extracted from the tensor analyzing power measurements by making use of distorted-wave Born approximation calculations. Analysis of the sub-Coulomb measurements leads to D2=-0.279+/-0.012 fm2, which is somewhat larger in magnitude than recent theoretical predictions. [NUCLEAR REACTIONS 91Zr(d,t), Ed=6.0,7.5 MeV, 118Sn(d,t), Ed=12.0 MeV, 119Sn(d,t), Ed=6.0,7.5,9.0 MeV, 208Pb(d,t), Ed=10.0,12.3 MeV; measured polarization parameters T20(θ), T21(θ), T22(θ) deduced D2. Enriched targets, DWBA analysis.

  12. 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

  13. 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.

  14. Tritium in the DIII-D carbon tiles

    SciTech Connect

    Taylor, P.L.; Kellman, A.G.; Lee, R.L.

    1993-06-01

    The amount of tritium in the carbon tiles used as a first wall in the DIII-D tokamak was measured recently when the tiles were removed and cleaned. The measurements were made as part of the task of developing the appropriate safety procedures for processing of the tiles. The surface tritium concentration on the carbon tiles was surveyed and the total tritium released from tile samples was measured in test bakes. The total tritium in all the carbon tiles at the time the tiles were removed for cleaning is estimated to be 15 mCi and the fraction of tritium retained in the tiles from DIII-D operations has a lower bound of 10%. The tritium was found to be concentrated in a narrow surface layer on the plasma facing side of the tile, was fully released when baked to 1,000{degree}C, and was released in the form of tritiated gas (DT) as opposed to tritiated water (DTO) when baked.

  15. 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'.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

    Greenberg, H. S.

    1994-12-01

    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.

  19. Complex tiling patterns in liquid crystals

    PubMed Central

    Tschierske, C.; Nürnberger, C.; Ebert, H.; Glettner, B.; Prehm, M.; Liu, F.; Zeng, X.-B.; Ungar, G.

    2012-01-01

    In this account recent progress in enhancing the complexity of liquid crystal self-assembly is highlighted. The discussed superstructures are formed mainly by polyphilic T-shaped and X-shaped molecules composed of a rod-like core, tethered with glycerol units at both ends and flexible non-polar chain(s) in lateral position, but also related inverted molecular structures are considered. A series of honeycomb phases composed of polygonal cylinders ranging from triangular to hexagonal, followed by giant cylinder honeycombs is observed for ternary T-shaped polyphiles on increasing the size of the lateral chain(s). Increasing the chain size further leads to new modes of lamellar organization followed by three-dimensional and two-dimensional structures incorporating branched and non-branched axial rod-bundles. Grafting incompatible chains to opposite sides of the rod-like core leads to quaternary X-shaped polyphiles. These form liquid crystalline honeycombs where different cells are filled with different material. Projected on an Euclidian plane, all honeycomb phases can be described either by uniformly coloured Archimedean and Laves tiling patterns (T-shaped polyphiles) or as multi-colour tiling patterns (X-shaped polyphiles). It is shown that geometric frustration, combined with the tendency to segregate incompatible chains into different compartments and the need to find a periodic tiling pattern, leads to a significant increase in the complexity of soft self-assembly. Mixing of different chains greatly enhances the number of possible ‘colours’ and in this way, periodic structures comprising up to seven distinct compartments can be generated. Relations to biological self-assembly are discussed shortly. PMID:24098852

  20. Tile Percolation: An OpenMP Tile Aware Parallelization Technique for the Cyclops-64 Multicore Processor

    NASA Astrophysics Data System (ADS)

    Gan, Ge; Wang, Xu; Manzano, Joseph; Gao, Guang R.

    Programming a multicore processor is difficult. It is even more difficult if the processor has software-managed memory hierarchy, e.g. the IBM Cyclops-64 (C64). A widely accepted parallel programming solution for multicore processor is OpenMP. Currently, all OpenMP directives are only used to decompose computation code (such as loop iterations, tasks, code sections, etc.). None of them can be used to control data movement, which is crucial for the C64 performance. In this paper, we propose a technique called tile percolation. This method provides the programmer with a set of OpenMP pragma directives. The programmer can use these directives to annotate their program to specify where and how to perform data movement. The compiler will then generate the required code accordingly. Our method is a semi-automatic code generation approach intended to simplify a programmer’s work. The paper provides (a) an exploration of the possibility of developing pragma directives for semi-automatic data movement code generation in OpenMP; (b) an introduction of techniques used to implement tile percolation including the programming API, the code generation in compiler, and the required runtime support routines; (c) and an evaluation of tile percolation with a set of benchmarks. Our experimental results show that tile percolation can make the OpenMP programs run on the C64 chip more efficiently.

  1. Study of TFTR D-T neutron spectra using natural diamond detectors

    SciTech Connect

    Roquemore, A.L.; Krasilnikov, A.V., Gorelenkov, N.N.

    1996-12-31

    Three Natural Diamond Detector (NDD) based spectrometers have been used for neutron spectra measurement during Deuterium-Tritium (D-T) experiments using high power Neutral Beam Injection (NBI) and Ton Cyclotron Resonance Heating (ICRH) on the Tokamak Fusion Test Reactor (TFTR) in 1996. A 2-3 % energy resolution coupled with the high radiation resistance of NDDs (5 x 10{sup 14}n/cm{sup 2}) makes them ideal for measuring the D-T neutron spectra in the high radiation environment of TFTR tritium experiments. The compact size of the NDD made it possible to insert one of the detectors into one of the center channels of the TFTR multichannel neutron collimator to provide a vertical view perpendicular to the vessel midplane, Two other detectors were placed inside shields in TFTR test cell and provide measurements of the neutrons having angles of emission of 110- 180{degrees} and 60-12-{degrees} with respect to the direction of the plasma current. By using a 0.25 {mu}s shaping time of the Ortec 673 spectroscopy amplifier we were able to accumulate useful spectrometry data at count rates up to 1.5 x 10{sup 3} counts/sec. To model the D- T neutron spectra measured by each of three NDD`s the Neutron Source post TRANSP (NST) code and semi-analytical model were developed. A set of D-T and D-D plasmas is analyzed for the dynamics of D-T neutron spectral broadening for each of three NDD cones of view. The application of three NDD based D-T neutron -spectrometer array demonstrated the anisotropy of the ion distribution function. and provided a mature of the dynamics of the effective ion temperatures for each detector view, and determined the tangential velocity of resonant tritons during ICRH.

  2. Graphite polyhedral crystals.

    PubMed

    Gogotsi, Y; Libera, J A; Kalashnikov, N; Yoshimura, M

    2000-10-13

    Polyhedral nano- and microstructures with shapes of faceted needles, rods, rings, barrels, and double-tipped pyramids, which we call graphite polyhedral crystals (GPCs), have been discovered. They were found in pores of glassy carbon. They have nanotube cores and graphite faces, and they can exhibit unusual sevenfold, ninefold, or more complex axial symmetry. Although some are giant radially extended nanotubes, Raman spectroscopy and transmission electron microscopy suggest GPCs have a degree of perfection higher than in multiwall nanotubes of similar size. The crystals are up to 1 micrometer in cross section and 5 micrometers in length, and they can probably be grown in much larger sizes. Preliminary results suggest a high electrical conductivity, strength, and chemical stability of GPC.

  3. Symmetries and color symmetries of a family of tilings with a singular point.

    PubMed

    Evidente, Imogene F; Felix, Rene P; Loquias, Manuel Joseph C

    2015-11-01

    Tilings with a singular point are obtained by applying conformal maps on regular tilings of the Euclidean plane and their symmetries are determined. The resulting tilings are then symmetrically colored by applying the same conformal maps on colorings of regular tilings arising from sublattice colorings of the centers of the tiles. In addition, conditions are determined in order that the coloring of a tiling with singularity that is obtained in this manner is perfect. PMID:26522407

  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. METHOD FOR EVALUATING MOLD GROWTH ON CEILING TILE

    EPA Science Inventory

    A method to extract mold spores from porous ceiling tiles was developed using a masticator blender. Ceiling tiles were inoculated and analyzed using four species of mold. Statistical analysis comparing results obtained by masticator extraction and the swab method was performed. T...

  6. 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

  7. Improving Efficiency of 3-SAT-Solving Tile Systems

    NASA Astrophysics Data System (ADS)

    Brun, Yuriy

    The tile assembly model has allowed the study of the nature's process of self-assembly and the development of self-assembling systems for solving complex computational problems. Research into this model has led to progress in two distinct classes of computational systems: Internet-sized distributed computation, such as software architectures for computational grids, and molecular computation, such as DNA computing. The design of large complex tile systems that emulate Turing machines has shown that the tile assembly model is Turing universal, while the design of small tile systems that implement simple algorithms has shown that tile assembly can be used to build private, fault-tolerant, and scalable distributed software systems and robust molecular machines. However, in order for these types of systems to compete with traditional computing devices, we must demonstrate that fairly simple tile systems can implement complex and intricate algorithms for important problems. The state of the art, however, requires vastly complex tile systems with large tile sets to implement such algorithms.

  8. Glazed tiles manufactured from incinerated sewage sludge ash and clay.

    PubMed

    Lin, Deng-Fong; Luo, Huan-Lin; Sheen, Yeong-Nain

    2005-02-01

    Sewage sludge incineration is applied extensively in highly populated cities as a final sludge treatment. In this study, incinerated ash was utilized as an additive to clay to manufacture glaze tiles. Four different amounts of ash (0, 15, 30, and 45%) were added, and five glaze concentrations (0.03, 0.06, 0.1, 0.15, and 0.2 g/cm2) were applied on the surface of biscuit tiles to study the effects of ash additive and glaze concentration on properties of fired samples. Sewage sludge was dehydrated and incinerated into ash at 800 degrees C. Subsequently, tile specimens were manufactured and fired at 800 degrees C to make biscuit tiles. Fritted glazes and iron oxide were used as the fundamental glaze and colorant, respectively. Finally, glaze was applied on the surface of biscuit tiles and then fired at 1050 degrees C to sinter them into glazed tile specimens. Tests were performed to analyze properties, including water absorption, firing shrinkage, weight loss on ignition, abrasion resistance, bending resistance, acid-alkali resistance, and aging resistance on specimens of glaze tile. To further understand more about the microstructural behavior of glazed tile specimens, analysis of energy dispersive spectrometer, scanning electron microscopy, and X-ray were carried out in this study.

  9. New SWAT tile drain equations: Modifications, Calibration, Validation, and Application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Subsurface tile drainage is a commonly used agricultural practice to enhance crop yield in poorly drained but highly productive soils in many other regions of the world. However, the presence of subsurface tile drainage systems also expedites the transport of nitrate-nitrogen (NO3-N) and other chemi...

  10. 81. MORAVIAN POTTERY AND TILE WORKS, VIEW FROM THE SOUTHWEST. ...

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

    81. MORAVIAN POTTERY AND TILE WORKS, VIEW FROM THE SOUTHWEST. INDIAN HOUSE WING AT THE LEFT. SAME VIEW AS PA-107-2. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  11. 80. KILN AT FIRST MORAVIAN POTTERY AND TILE WORKS AT ...

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

    80. KILN AT FIRST MORAVIAN POTTERY AND TILE WORKS AT ALDIE, 1901. PHOTOGRAPH PUBLISHED IN HOUSE AND GARDEN. AUGUST 1901, p. 19. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  12. 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...

  13. Nutrient and Pesticide Removal From Laboratory Simulated Tile Drainage Discharge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excess nutrient and pesticide transport through subsurface tile drainage is well documented. One approach receiving consideration for reducing the amount of nutrients and pesticides in subsurface drainage waters is end-of-tile filters. The filters are often comprised of industrial wastes or by-produ...

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. Graphite fiber reinforced thermoplastic resins

    NASA Technical Reports Server (NTRS)

    Navak, R. C.

    1977-01-01

    The results of a program designed to optimize the fabrication procedures for graphite thermoplastic composites are described. The properties of the composites as a function of temperature were measured and graphite thermoplastic fan exit guide vanes were fabricated and tested. Three thermoplastics were included in the investigation: polysulfone, polyethersulfone, and polyarylsulfone. Type HMS graphite was used as the reinforcement. Bending fatigue tests of HMS graphite/polyethersulfone demonstrated a gradual shear failure mode which resulted in a loss of stiffness in the specimens. Preliminary curves were generated to show the loss in stiffness as a function of stress and number of cycles. Fan exit guide vanes of HMS graphite polyethersulfone were satisfactorily fabricated in the final phase of the program. These were found to have stiffness and better fatigue behavior than graphite epoxy vanes which were formerly bill of material.

  19. The photochemistry of d(T-A) in aqueous solution and in ice.

    PubMed Central

    Bose, S N; Kumar, S; Davies, R J; Sethi, S K; McCloskey, J A

    1984-01-01

    When d(T-A) is irradiated at 254 nm in aqueous solution an internal photoadduct is formed between its constituent adenine and thymine bases. The resultant photoproduct, designated TA*, arises from a singlet excited state precursor; a similar photoreaction is not observed with d(C-A) or d(T-G). In contradistinction, irradiation of d(T-A) in frozen aqueous solution yields a dimeric photoproduct in which two d(T-A) molecules are coupled together by a (6-4) photoadduct linkage between their respective thymine bases. Both photoproducts have been extensively characterised by a combination of electron impact and fast atom bombardment mass spectrometry, UV, CD, 1H NMR and fluorescence spectroscopy. Acid treatment of TA* gives 6-methylimidazo[4,5-b]pyridin-5-one whose identity was established by an independent chemical synthesis involving photorearrangement of 6-methyl-imidazo[4,5-b]pyridine N(4)-oxide. A tentative mechanism is presented to account for the acid degradation of TA*. The structure of the dimeric ice photoproduct follows from its cleavage, by snake venom phosphodiesterase, to 5'-dAMP and the (6-4) bimolecular photoadduct of thymidine; on acid hydrolysis it gives adenine and 6-(5'-methyl-2'-oxopyrimidin-4'-yl) thymine. PMID:6493984

  20. The photochemistry of d(T-A) in aqueous solution and in ice.

    PubMed

    Bose, S N; Kumar, S; Davies, R J; Sethi, S K; McCloskey, J A

    1984-10-25

    When d(T-A) is irradiated at 254 nm in aqueous solution an internal photoadduct is formed between its constituent adenine and thymine bases. The resultant photoproduct, designated TA*, arises from a singlet excited state precursor; a similar photoreaction is not observed with d(C-A) or d(T-G). In contradistinction, irradiation of d(T-A) in frozen aqueous solution yields a dimeric photoproduct in which two d(T-A) molecules are coupled together by a (6-4) photoadduct linkage between their respective thymine bases. Both photoproducts have been extensively characterised by a combination of electron impact and fast atom bombardment mass spectrometry, UV, CD, 1H NMR and fluorescence spectroscopy. Acid treatment of TA* gives 6-methylimidazo[4,5-b]pyridin-5-one whose identity was established by an independent chemical synthesis involving photorearrangement of 6-methyl-imidazo[4,5-b]pyridine N(4)-oxide. A tentative mechanism is presented to account for the acid degradation of TA*. The structure of the dimeric ice photoproduct follows from its cleavage, by snake venom phosphodiesterase, to 5'-dAMP and the (6-4) bimolecular photoadduct of thymidine; on acid hydrolysis it gives adenine and 6-(5'-methyl-2'-oxopyrimidin-4'-yl) thymine.

  1. Leakage Rate of Combined Hemispherical Shells with D-T Neutrons

    NASA Astrophysics Data System (ADS)

    Chen, Y.; An, L.; Mou, Y. F.; Guo, H. P.; Wang, X. H.

    2003-06-01

    A 2-dimensional assembly made of hemispheres of beryllium, stainless steel and simulation material had been established. A NE-213 detector was used to measure leakage neutron spectrum at the assembly center with D-T neutrons. The transmission rate per source neutron was obtained. The measurements were compared with the calculation using MCNP/4A code and ENDF/B-V database.

  2. 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.

  3. Properties of structural clay load-bearing wall tile

    SciTech Connect

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

    1993-02-02

    Structural clay tile has been produced in the United States and used in load-bearing walls for over a century. While the fundamentals of the manufacturing process have not changed significantly, specific fabrication details and material additives have led to increased strength and economy of current products. Red burned clay masonry units were sampled and tested in accordance with applicable ASTM standards. Objective of the tests was to compare tiles used in the original construction of the Oak Ridge Y-12 Plant (1940s) to tiles being used in current large scale laboratory tests and wall repairs. Results of the tests are compared to other contemporary and historic clay tile data. The effects of the evolution of clay tile manufacturing on engineering properties is also examined.

  4. Buffet loads on shuttle thermal-protection-system tiles

    NASA Technical Reports Server (NTRS)

    Coe, C. F.

    1982-01-01

    Results of wind-tunnel and acoustic tests to investigate buffet loads on Shuttle Thermal-Protection-System (TPS) tiles are given. Also described is the application of these results to the prediction of tile buffet loads for the first shuttle flight into orbit. The wind-tunnel tests of tiles were conducted at transonic and supersonic Mach numbers simulating flow regions on the Orbiter where shock waves and boundary-layer separations occur. The acoustic tests were conducted in a progressive wave tube at an overall sound pressure level (OASPL) approximately equal to the maximum OASPL measured during the wind-tunnel tests in a region of flow separation. The STS-1 buffet load predictions yielded peak tile stresses due to buffeting that were as much as 20 percent of the total stress for the design-load case when a shock wave was on a tile.

  5. In vivo mapping of arabidopsis scaffold/matrix attachment regions reveals link to nucleosome-disfavoring poly(dA:dT) tracts.

    PubMed

    Pascuzzi, Pete E; Flores-Vergara, Miguel A; Lee, Tae-Jin; Sosinski, Bryon; Vaughn, Matthew W; Hanley-Bowdoin, Linda; Thompson, William F; Allen, George C

    2014-01-01

    Scaffold or matrix attachment regions (S/MARs) are found in all eukaryotes. The pattern of distribution and genomic context of S/MARs is thought to be important for processes such as chromatin organization and modulation of gene expression. Despite the importance of such processes, much is unknown about the large-scale distribution and sequence content of S/MARs in vivo. Here, we report the use of tiling microarrays to map 1358 S/MARs on Arabidopsis thaliana chromosome 4 (chr4). S/MARs occur throughout chr4, spaced much more closely than in the large plant and animal genomes that have been studied to date. Arabidopsis S/MARs can be divided into five clusters based on their association with other genomic features, suggesting a diversity of functions. While some Arabidopsis S/MARs may define structural domains, most occur near the transcription start sites of genes. Genes associated with these S/MARs have an increased probability of expression, which is particularly pronounced in the case of transcription factor genes. Analysis of sequence motifs and 6-mer enrichment patterns show that S/MARs are preferentially enriched in poly(dA:dT) tracts, sequences that resist nucleosome formation, and the majority of S/MARs contain at least one nucleosome-depleted region. This global view of S/MARs provides a framework to begin evaluating genome-scale models for S/MAR function. PMID:24488963

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Local growth of icosahedral quasicrystalline tilings

    NASA Astrophysics Data System (ADS)

    Hann, Connor T.; Socolar, Joshua E. S.; Steinhardt, Paul J.

    2016-07-01

    Icosahedral quasicrystals (IQCs) with extremely high degrees of translational order have been produced in the laboratory and found in naturally occurring minerals, yet questions remain about how IQCs form. In particular, the fundamental question of how locally determined additions to a growing cluster can lead to the intricate long-range correlations in IQCs remains open. In answer to this question, we have developed an algorithm that is capable of producing a perfectly ordered IQC yet relies exclusively on local rules for sequential, face-to-face addition of tiles to a cluster. When the algorithm is seeded with a special type of cluster containing a defect, we find that growth is forced to infinity with high probability and that the resultant IQC has a vanishing density of defects. The geometric features underlying this algorithm can inform analyses of experimental systems and numerical models that generate highly ordered quasicrystals.

  13. 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.

  14. Coal fly ash utilization: low temperature sintering of wall tiles.

    PubMed

    Chandra, Navin; Sharma, Priya; Pashkov, G L; Voskresenskaya, E N; Amritphale, S S; Baghel, Narendra S

    2008-01-01

    We present here a study of the sintering of fly ash and its mixture with low alkali pyrophyllite in the presence of sodium hexa meta phosphate (SHMP), a complex activator of sintering, for the purpose of wall tile manufacturing. The sintering of fly ash with SHMP in the temperature range 925-1050 degrees C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with >or=40% (w/w) pyrophyllite in the fly ash-pyrophyllite mix satisfies the acceptable limit (19.6 J/m) set by the Indian Standards Institute for wall tiles. Increasing the pyrophyllite content results in an increase in the apparent density of tiles, while shrinkage and water absorption decrease. The strength of fly ash tiles is attributed to the formation of a silicophosphate phase; in pyrophyllite rich tiles, it is attributed to the formation of a tridymite-structured T-AlPO(4) phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO(4) crystals become more prominent as the pyrophyllite content increases in the sintered tiles.

  15. 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.

  16. 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.

  17. Examining graphite reinforcement in composites

    NASA Technical Reports Server (NTRS)

    Sanders, R. E.; Yates, C. I.

    1980-01-01

    Structure of graphite layers in composite parts can be checked by pyrolizing epoxy portion of composite samples. After 2-3 hours in nitrogen atmosphere at 540 C, only graphite fibers remain. These can be separated and checked for proper number, thickness, and orientation.

  18. Multiaxial graphite test specimen

    SciTech Connect

    1988-09-01

    A multiaxial test program is to be conducted by Oak Ridge National Laboratory (ORNL) on the core component graphite. The objectives of the tests are to obtain failure data under uniaxial and biaxial states of stress in order to construct a failure surface in a two-dimensional stress space. These data will be used in verifying the accuracy of the maximum stress failure theory being proposed for use in designing the core graphite components. Tubular specimens are proposed to be used and are either loaded axially and/or subjected to internal pressure. This report includes a study on three specimen configurations. The conclusions of that study indicate that an elliptical transition geometry procedures the smallest discontinuity effects. Several loading combustions were studied using the elliptical transition specimen. The primary purpose is to establish the location of the highest stress state and its relation to the gage section for all of the loading conditions. The tension/internal pres sure loading condition (1:1) indicated that the high stress area is just outside the gage section but still should be acceptable. 5 refs., 18 figs.

  19. 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

  20. 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

  1. Intrinsic DNA curvature of double-crossover tiles.

    PubMed

    Kim, Seungjae; Kim, Junghoon; Qian, Pengfei; Shin, Jihoon; Amin, Rashid; Ahn, Sang Jung; LaBean, Thomas H; Kim, Moon Ki; Park, Sung Ha

    2011-06-17

    A theoretical model which takes into account the structural distortion of double-crossover DNA tiles has been studied to investigate its effect on lattice formation sizes. It has been found that a single vector appropriately describes the curvature of the tiles, of which a higher magnitude hinders lattice growth. In conjunction with these calculations, normal mode analysis reveals that tiles with relative higher frequencies have an analogous effect. All the theoretical results are shown to be in good agreement with experimental data. PMID:21543827

  2. Hypervelocity impact testing of Shuttle Orbiter thermal protection system tiles

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.; Ortega, Javier

    1990-01-01

    Results are presented from a series of 22 hypervelocity impact tests carried out on the thermal protection system (TPS) for the Shuttle Orbiter. Both coated and uncoated low-density (0.14 g/cu cm) LI-900 and high-density (0.35 g/cu cm) LI-2200 tiles were tested. The results are used to develop the penetration and damage correlations which can be used in meteoroid and debris hazard analyses for spacecraft with a ceramic tile TPS. It is shown that tile coatings act as a 'bumper' to fragment the impacting projectile, with thicker coating providing increased protection.

  3. Radioactivity measurements of ITER materials using the TFTR D-T neutron field

    SciTech Connect

    Kumar, A.; Abdou, M.A.; Barnes, C.W.; Kugel, H.W.; Loughlin, M.J.

    1994-08-01

    The availability of high D-T fusion neutron yields at TFTR has provided a useful opportunity to directly measure D-T neutron-induced radioactivity in a realistic tokamak fusion reactor environment for materials of vital interest to ITER. These measurements are valuable for characterizing radioactivity in various ITER candidate materials. for validating complex neutron transport calculations, and for meeting fusion reactor licensing requirements. The radioactivity measurements at TFTR involve potential ITER materials including stainless steel 316, vanadium, titanium, chromium, silicon, iron, cobalt, nickel, molybdenum, aluminum, copper, zinc. zirconium, niobium, and tungsten. Small samples of these materials were irradiated close to the plasma and just outside the vacuum vessel wall of TFTR, locations of different neutron energy spectra. Saturation activities for both threshold and capture reactions were measured. Data from dosimetric reactions have been used to obtain preliminary neutron energy spectra. Spectra from the first wall were compared to calculations from ITER and to measurements from accelerator-based tests.

  4. Benchmark experiment on a copper slab assembly bombarded by D-T neutrons

    NASA Astrophysics Data System (ADS)

    Maekawa, Fujio; Oyama, Yukio; Konno, Chikara; Ikeda, Yujiro; Maekawa, Hiroshi; Kosako, Kazuaki

    1994-03-01

    Copper is a very important material for fusion reactor because it is used in superconducting magnets or first walls and so on. To verify nuclear data of copper, a benchmark experiment was performed using the D-T neutron source of the FNS facility in Japan Atomic Energy Research Institute. An cylindrical experimental assembly of 629 mm in diameter and 608 mm in thickness made of pure copper was located at 200 mm from the D-T neutron source. In the assembly, the following quantities were measured: (1) neutron spectra in energy regions of MeV and keV, (2) neutron reaction rates, (3) prompt and decay gamma-ray spectra, and (4) gamma-ray heating rates. The obtained experimental data were compiled in this report.

  5. Chromosome aberrations induced in human lymphocytes by D-T neutrons

    SciTech Connect

    Lloyd, D.C.; Edwards, A.A.; Prosser, J.S.; Bolton, D.; Sherwin, A.G.

    1984-06-01

    Unstable chromosome aberrations induced by in vitro irradiation with D-T neutrons have been analyzed in human blood lymphocytes. With respect to 250 kVp X rays a maximum limiting RBE at low doses of 4.1 was obtained for dicentric aberrations. Using aberrations as markers in mixed cultures of irradiated and unirradiated cells permits an assessment of interphase death plus mitotic delay. The low-dose RBE for this effect is 2.5. Assuming all unstable aberrations observed at metaphase would lead to cell death by nondisjunction allows an assessment of mitotic death. The low-dose RBE for this effect is 4.5. The data are compared with similar work obtained earlier with /sup 242/Cm ..cap alpha.. particles. The application of the present work to cytogenetic assessment of dose after accidental exposure to D-T neutrons is discussed.

  6. 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

  7. DNA with adenine tracts contains poly(dA).poly(dT) conformational features in solution.

    PubMed

    Brahms, S; Brahms, J G

    1990-03-25

    The conformation of DNA's with adenine-thymine tracts exhibiting retardation in electrophoretic migration and considered as curved were investigated in solution by CD and RAMAN spectroscopy. The following curved multimers with adenine tracts but of different flanking sequences d(CA5TGCC)n, d(TCTCTA6TATATA5)n, d(GA4T4C)n yield CD spectroscopic features indicating a non-B structure of the dA.dT tract with similarities to polyd(A).polyd(T). We suggest that adenine-thymine bases in these multimers contain some of the distinctive conformational features of poly(A).polyd(T) probably with large propeller twist found by NMR (Behling and Kearns, 1987) and by X-ray diffraction on oligonucleotides containing a tract of adenines (Nelson et al. 1987, Coll et al; 1987; DiGabriele et al. 1989). Some elements of distinctive CD features of the contiguous adenines run are also observed in the straight multi-9-mer d(CA5GCC)n which lacks in-phase relation to the helical repeat. Despite the presence of the TpA step in the straight multimer d(GT4A4)n, the altered dA.dT conformation is not completely destroyed. Interruption of adenine tract by a guanine in d(CAAGAATGCC)n leads to a B-like conformation and to a normal electrophoretic mobility. The Raman spectra reveal a rearrangement of the sugar-phosphate backbone of dA.dT tract in the multimer d(CA5TGCC)n with respect to that of polydA.polydT. This is reflected in the presence of an unique Raman band associated to C2'-endo sugar with a predominant contribution of C1'-exo puckering which is exhibited by the multimer whereas two distinct Raman bands characterize poly(dA).poly(dT) backbone conformation.

  8. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    NASA Astrophysics Data System (ADS)

    Sinha, Amar; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P. S.; Bishnoi, Saroj

    2015-05-01

    The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated keff of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor ks and external neutron source efficiency φ∗ in great details. Experiments with D-T neutrons are also underway.

  9. 35. DETAIL INTERIOR VIEW OF TILE DECORATION ON WALL OF ...

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

    35. DETAIL INTERIOR VIEW OF TILE DECORATION ON WALL OF POWERHOUSE #1 ON LEVEL +55; THE WINDOWS LOOK OUT ON DISCHARGE CHANNEL DOWNSTREAM FROM POWERHOUSE. - Bonneville Project, Powerhouse No.1, Spanning Bradford Slough, from Bradford Island, Bonneville, Multnomah County, OR

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. VIEW OF COMPASS ROSE TILE INLAY IN FLOOR OF LOBBY, ...

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

    VIEW OF COMPASS ROSE TILE INLAY IN FLOOR OF LOBBY, BUILDING 1, LOOKING SOUTHEAST - Roosevelt Base, Administration & Brig Building, Bounded by Nevada & Colorado Streets, Reeves & Richardson Avenues, Long Beach, Los Angeles County, CA

  16. Detail of first floor of loading dock showing composition tile ...

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

    Detail of first floor of loading dock showing composition tile over wood floor/basement ceiling - Southern Pacific Railroad Depot, Railroad Terminal Post Office & Express Building, Fifth & I Streets, Sacramento, Sacramento County, CA

  17. INTERIOR VIEW OF BATHROOM 2. SHOWING ORIGINAL TILE. CERAMIC ACCESSORIES, ...

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

    INTERIOR VIEW OF BATHROOM 2. SHOWING ORIGINAL TILE. CERAMIC ACCESSORIES, AND MARBLE THRESHOLD. VIEW FACING EAST. - Hickam Field, Officers' Housing Type G, 205 Seventh Street, Honolulu, Honolulu County, HI

  18. Self-glazing ceramic tiles based on acidic igneous glasses

    SciTech Connect

    Merkin, A.P.; Nanazashvili, V.I.

    1988-07-01

    A technology was derived to produce self-glazing ceramic tiles based on single-component systems of acidic igneous (volcanic) glasses. A weakly alkaline solution of NaOH or KOH was used as the sealing water to activate the sintering process. Tests conducted on the self-glazing ceramic tiles showed that their water absorption amounts to 2.5-8%, linear shrinkage is 3.2-7%, and frost resistance amounts to 35-70 cycles. The application of acidic igneous glasses as the main raw material for the production of ceramic facing tiles made it possible to widen the raw material base and simplify the technology for fabricating ceramic facing tiles at lower cost. The use of waste products when processing perlite-bearing rocks, when carrying out mining and cutting of tuffs, slags, and tuff breccia for recovering cut materials was recommended.

  19. 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.

  20. Influence of microwave-annealing on the mechanical properties of alumina tiles

    SciTech Connect

    Kass, M.D.; Akerman, M.A.; Baity, F.W. Jr.; Lowden, R.A.

    1995-12-31

    Fully dense alumina armor tiles were annealed at 1400{degrees}C for one hour using microwave radiation at 28 GHz. Ultrasonic measurements showed that the acoustic impedances, and Young`s moduli of the post-annealed tiles were higher than for unannealed tiles. The post-annealed tiles also exhibited higher hardness values and improved armor performance. Microstructure analysis indicated that the grain boundary regions of the tiles were affected by the microwave heating.

  1. 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

  2. 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.

  3. Ceramic tile grout removal & sealing using high power lasers

    SciTech Connect

    Lawrence, J.; Li, L.; Spencer, J.T.

    1996-12-31

    Work has been conducted using a Nd:YAG laser, a CO{sub 2} laser and a high power diode laser (HPDL) in order to determine the feasibility of removing contaminated tile grout from the void between adjoining vitrified ceramic tiles, and to seal the void permanently with a material having an impermeable surface glaze. Reported on in the paper are; the basic process phenomena, the process effectiveness, suitable vitrifiable material development, a heat affect study and a morphological and compositional analysis.

  4. Density of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.

    1990-01-01

    The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not.

  5. Density of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.

    1989-01-01

    The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not.

  6. 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.

  7. Spatial chaos of Wang tiles with two symbols

    NASA Astrophysics Data System (ADS)

    Chen, Jin-Yu; Chen, Yu-Jie; Hu, Wen-Guei; Lin, Song-Sun

    2016-02-01

    This investigation completely classifies the spatial chaos problem in plane edge coloring (Wang tiles) with two symbols. For a set of Wang tiles B , spatial chaos occurs when the spatial entropy h ( B ) is positive. B is called a minimal cycle generator if P ( B ) ≠ 0̸ and P ( B ' ) = 0̸ whenever B ' ⫋ B , where P ( B ) is the set of all periodic patterns on ℤ2 generated by B . Given a set of Wang tiles B , write B = C 1 ∪ C 2 ∪ ⋯ ∪ C k ∪ N , where Cj, 1 ≤ j ≤ k, are minimal cycle generators and B contains no minimal cycle generator except those contained in C1∪C2∪⋯∪Ck. Then, the positivity of spatial entropy h ( B ) is completely determined by C1∪C2∪⋯∪Ck. Furthermore, there are 39 equivalence classes of marginal positive-entropy sets of Wang tiles and 18 equivalence classes of saturated zero-entropy sets of Wang tiles. For a set of Wang tiles B , h ( B ) is positive if and only if B contains a MPE set, and h ( B ) is zero if and only if B is a subset of a SZE set.

  8. 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.

  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. 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.

  11. Helix-coil transition of the self-complementary dG-dG-dA-dA-dT-dT-dC-dC duplex.

    PubMed

    Patel, D J; Canuel, L L

    1979-05-15

    The helix-coil transition of the octanucleotide self-complementary duplex dG-dG-dA-dA-dT-dT-dC-dC has been monitored at the Watson-Crick protons, the base and sugar nonexchangeable protons and the backbone phosphates by high-resolution nuclear magnetic resonance (NMR) spectroscopy. The melting transition of the octanucleotide monitored by ultraviolet absorbance spectroscopy is characterized by the thermodynamic parameters delta H degree = -216.7 kJ/mol and delta S degree (25 degrees C) = -0.632 KJ mol-1 K-1 in 0.1 M NaCl, 10 mM phosphate solution. Correlation of the transition midpoint values monitored by the ultraviolet absorbance studies at strand concentrations below 0.2 mM and by NMR studies at 5.3 mM suggest that both methods are monitoring the octanucleotide duplex-to-strand transition. The NMR spectra of the Watson-Crick ring NH protons of the octanucleotide duplex have been followed as a function of temperature. The resonance from the terminal dG.dC base pairs broadens out at room temperature while the resonances from the other base pairs broaden simultaneously with the onset of the melting transition. The nonexchangeable base and sugar H-1' protons are resolved in the duplex and strand states and shift as average peaks through the melting transition. The experimental shifts on duplex formation have been compared with calculated values based on ring-current and atomic diamagnetic anisotropy contributions for a B-DNA base-pair-overlap geometry in solution. Several nonexchangeable proton resonances broaden in the fast-exchange region during the duplex-to-strand transition and the excess widths yield a duplex dissociation rate constant for the octanucleotide of 1.9 x 10(3) s-1 at 32 degrees C (fraction of duplex = 0.86) in 0.1 M NaCl, 10 mM phosphate buffer. The 31P resonances of the seven internucleotide phosphates are distributed over 0.6 ppm in the duplex state, shift downfield during the duplex-to-strand transition and undergo additional downfield shifts

  12. 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. xml:lang="fr"

  13. 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.

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  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. Irradiation Induced Creep of Graphite

    SciTech Connect

    Burchell, Timothy D; Murty, Prof K.L.; Eapen, Dr. Jacob

    2010-01-01

    The current status of graphite irradiation induced creep strain prediction is reviewed and the major creep models are described. The ability of the models to quantitatively predict the irradiation induced creep strain of graphite is reported. Potential mechanisms of in-crystal creep are reviewed as are mechanisms of pore generation under stress. The case for further experimental work is made and the need for improved creep models across multi-scales is highlighted.

  20. D-T gamma-to-neutron branching ratio determined from inertial confinement fusion plasmas

    SciTech Connect

    Kim, Y.; Mack, J. M.; Herrmann, H. W.; Young, C. S.; Hale, G. M.; Caldwell, S.; Hoffman, N. M.; Evans, S. C.; Sedillo, T. J.; McEvoy, A.; Langenbrunner, J.; Hsu, H. H.; Huff, M. A.; Batha, S.; Horsfield, C. J.; Rubery, M. S.; Garbett, W. J.; Stoeffl, W.; Grafil, E.; Bernstein, L.; and others

    2012-05-15

    A new deuterium-tritium (D-T) fusion gamma-to-neutron branching ratio [{sup 3}H(d,{gamma}){sup 5}He/{sup 3}H(d,n){sup 4}He] value of (4.2 {+-} 2.0) Multiplication-Sign 10{sup -5} was recently reported by this group [Y. Kim et al. Phys. Rev. C (submitted)]. This measurement, conducted at the OMEGA laser facility located at the University of Rochester, was made for the first time using inertial confinement fusion (ICF) plasmas. Neutron-induced backgrounds are significantly reduced in these experiments as compared to traditional beam-target accelerator-based experiments due to the short pulse nature of ICF implosions and the use of gas Cherenkov {gamma}-ray detectors with fast temporal responses and inherent energy thresholds. It is expected that this ICF-based measurement will help resolve the large and long-standing inconsistencies in previously reported accelerator-based values, which vary by a factor of approximately 30. The reported value at ICF conditions was determined by averaging the results of two methods: (1) a direct measurement of ICF D-T {gamma}-ray and neutron emissions using absolutely calibrated detectors and (2) a separate cross-calibration against the better known D-{sup 3}He gamma-to-proton branching ratio [{sup 3}He(d, {gamma}){sup 5}Li/{sup 3}He(d,p){sup 4}He]. Here we include a detailed explanation of these results, and introduce as a corroborative method an in-situ{gamma}-ray detector calibration using neutron-induced {gamma}-rays. Also, by extending the established techniques to two additional series of implosions with significantly different ion temperatures, we test the branching ratio dependence on ion temperature. The data show a D-T branching ratio is nearly constant over the temperature range 2-9 keV. These studies motivate further investigation into the {sup 5}He and {sup 5}Li systems resulting from D-T and D-{sup 3}He fusion, respectively, and result in improved ICF {gamma}-ray reaction history diagnosis at the National Ignition

  1. Fusion gamma diagnostics for D-T and D-/sup 3/He plasmas

    SciTech Connect

    Medley, S.S.; Hendel, H.

    1982-11-01

    Nuclear reactions of interest in controlled thermonuclear fusion research often possess a branch yielding prompt emission of gamma radiation. In principle, the gamma emission can be exploited to provide a new fusion diagnostic offering measurements comparable to those obtained by the well established neutron diagnostics methods. The conceptual aspects for a fusion gamma diagnostic are discussed in this paper and the feasibility for application to the Tokamak Fusion Test Reactor during deuterium neutral beam heating of a D-T plasma and minority ion cyclotron resonance heating of a D-/sup 3/He plasma is examined.

  2. 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?

  3. 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.

  4. Quantitative and functional analysis of CD69(+) NKG2D(+) T regulatory cells in healthy subjects.

    PubMed

    Vitales-Noyola, M; Doníz-Padilla, L; Álvarez-Quiroga, C; Monsiváis-Urenda, A; Portillo-Salazar, H; González-Amaro, R

    2015-07-01

    T regulatory (Treg) cells have a key role in immune homeostasis and the pathogenesis of chronic inflammatory and autoimmune diseases. CD69 is an early leukocyte activation molecule that under steady state conditions is detected in a small proportion of lymphocytes in peripheral blood and lymphoid tissues. Although it has been reported that a subset of CD69(+) T cells behaves as Treg lymphocytes, the possible relationship between CD69(+) Treg cells and CD4(+)NKG2D(+) T lymphocytes, which also exert immunosuppressive activity, has not been explored. In this study, we analyzed the expression of CD69 and NKG2D by T lymphocytes from the peripheral blood of twenty-five healthy subjects by multi-parametric flow cytometry analysis, and their suppressive activity by an assay of inhibition of lymphocyte activation (CD40L expression) and proliferation (carboxyfluorescein partition assay). We found a very small percentage of CD4(+)CD69(+)NKG2D(+) T cells (median 0.002%, Q1-Q3, 0.001-0.004%), which also expressed TGF-β (Latency Associated Peptide or LAP) and IL-10, in all samples analyzed. These cells exerted an important in vitro suppressive effect on both activation and proliferation of T effector cells. Our data suggest that at very small numbers, CD4(+)CD69(+)NKG2D(+) lymphocytes seem to exert a relevant functional immune-regulatory role in healthy subjects.

  5. Review of D-T Experiments Relevant to Burning Plasma Issues

    SciTech Connect

    R.J. Hawryluk

    2001-12-21

    Progress in the performance of tokamak devices has enabled not only the production of significant bursts of fusion energy from deuterium-tritium (D-T) plasmas in the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET) but, more importantly, the initial study of the physics of burning magnetically confined plasmas. The TFTR and JET, in conjunction with the worldwide fusion effort, have studied a broad range of topics including magnetohydrodynamic stability, transport, wave-particle interactions, the confinement of energetic particles, and plasma boundary interactions. The D-T experiments differ in three principal ways from previous experiments: isotope effects associated with the use of deuterium-tritium fuel, the presence of fusion-generated alpha particles, and technology issues associated with tritium handling and increased activation. The effect of deuterium-tritium fuel and the presence of alpha particles is reviewed and placed in the perspective of the much large r worldwide database using deuterium fuel and theoretical understanding. Both devices have contributed substantially to addressing the scientific and technical issues associated with burning plasmas. However, future burning plasma experiments will operate with larger ratios of alpha heating power to auxiliary power and will be able to access additional alpha-particle physics issues. The scientific opportunities for extending our understanding of burning plasmas beyond that provided by current experiments is described.

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

    SciTech Connect

    Lou, Tak Pui

    2003-05-01

    Neutron generators based on the {sup 2}H(d,n){sup 3}He and {sup 3}H(d,n){sup 4}He 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 >10{sup 9} 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 10{sup 14} n/s, the thermal neutron flux at the sample was predicted to be 7.3 x 10{sup 5} n/cm{sup 2}s. 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 Boron Neutron Capture Therapy (BNCT). The

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

    NASA Astrophysics Data System (ADS)

    Lou, Tak Pui

    2003-10-01

    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 Boron Neutron Capture Therapy (BNCT). The neutron flux required for positron production

  8. 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.

  9. 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.

  10. Determination of the triton D-state parameter D2 from sub-Coulomb (d-->, t) measurements

    NASA Astrophysics Data System (ADS)

    Sen, S.; Knutson, L. D.

    1982-07-01

    Measurements of the tensor analyzing powers for sub-Coulomb (d-->, t) reactions on 91Zr at Ed=5 MeV and 147Sm at Ed=6.5 MeV are presented. The measurements are analyzed to obtain values of the triton D-state parameter D2. The results are found to be in good agreement with the D2 values derived from previous sub-Coulomb measurements, and lend support to the contention that analyzing power measurements for sub-Coulomb (d-->, t) reactions provide reliable information about the D-state components. NUCLEAR REACTIONS 91Zr(d-->, t), Ed=5.0 MeV, 147Sm(d-->, t), Ed=6.5 MeV; measured polarization parameters T20(θ), T21(θ), T22(θ) deduced D2. Enriched targets, DWBA analysis.

  11. 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%.

  12. Structural testing of hollow clay tile units. Volume 1

    SciTech Connect

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

    1992-08-05

    This report presents the results of laboratory testing of hollow clay tile masonry units. The testing is part of an ongoing natural phenomena evaluation program of Hollow Clay Tile Wall (HCTW) facilities at the Oak Ridge Y-12 Plant. The primary purpose of these tests is to determine structural properties of unit tiles of the same lot to be used in large-scale laboratory testing of HCTW structures. Light red (terra cotta) clay masonry units, taken from the construction supply yard of were sampled and tested in accordance with applicable ASTM standards. Measurement of size, measurement of void area, initial rate of absorption, compressive strength, and splitting tensile strength procedures were performed. Evaluation of the test results along with comparison to other published clay tile data is provided. Volume 1 of this document contains a description of the testing, a summary of the results, comparison to other published clay tile data, and conclusion drawn from the results. Volume 2 contains the unreduced test data, data reduction software, and quality assurance aspects of the testing.

  13. The ATLAS tile calorimeter performance at the LHC

    SciTech Connect

    Calkins, R.

    2011-07-01

    The Tile Calorimeter (TileCal), the central section of the hadronic calorimeter of the ATLAS experiment, is a key detector component to detect hadrons, jets and taus and to measure the missing transverse energy. Due to the very good muon signal to noise ratio it assists the spectrometer in the identification and reconstruction of muons. TileCal is built of steel and scintillating tiles coupled to optical fibers and read out by photomultipliers. The calorimeter is equipped with systems that allow to monitor and to calibrate each stage of the read out system exploiting different signal sources: laser light, charge injection and a radioactive source. The performance of the calorimeter has been measured and monitored using calibration data, random triggered data, cosmic muons and more importantly LHC collision events. The results presented here assess the absolute energy scale calibration precision, the energy and timing uniformity and the synchronization precision. The ensemble of the results demonstrates a very good understanding of the performance of the Tile Calorimeter that is proved to be well within the design expectations. (authors)

  14. Leaching of dissolved phosphorus from tile-drained agricultural areas.

    PubMed

    Andersen, H E; Windolf, J; Kronvang, B

    2016-01-01

    We investigated leaching of dissolved phosphorus (P) from 45 tile-drains representing animal husbandry farms in all regions of Denmark. Leaching of P via tile-drains exhibits a high degree of spatial heterogeneity with a low concentration in the majority of tile-drains and few tile-drains (15% in our investigation) having high to very high concentration of dissolved P. The share of dissolved organic P (DOP) was high (up to 96%). Leaching of DOP has hitherto been a somewhat overlooked P loss pathway in Danish soils and the mechanisms of mobilization and transport of DOP needs more investigation. We found a high correlation between Olsen-P and water extractable P. Water extractable P is regarded as an indicator of risk of loss of dissolved P. Our findings indicate that Olsen-P, which is measured routinely in Danish agricultural soils, may be a useful proxy for the P leaching potential of soils. However, we found no straight-forward correlation between leaching potential of the top soil layer (expressed as either degree of P saturation, Olsen-P or water extractable P) and the measured concentration of dissolved P in the tile-drain. This underlines that not only the source of P but also the P loss pathway must be taken into account when evaluating the risk of P loss. PMID:27332841

  15. Characterization of ceramic roof tile wastes as pozzolanic admixture.

    PubMed

    Lavat, Araceli E; Trezza, Monica A; Poggi, Mónica

    2009-05-01

    The aim of this work is to study the recycling of tile wastes in the manufacture of blended cements. Cracked or broken ceramic bodies are not accepted as commercial products and, therefore, the unsold waste of the ceramic industry becomes an environment problem. The use of powdered roof tile in cement production, as pozzolanic addition, is reported. The wastes were classified as nonglazed, natural and black glazed tiles. The mineralogy of the powders was controlled by SEM-EDX microscopy, XRD analysis and FTIR spectroscopy. Particle size was checked by laser granulometry. Once the materials were fully characterized, pozzolanic lime consumption tests and Fratini tests were carried out. Different formulations of cement-tile blends were prepared by incorporation of up to 30% weight ratios of recycled waste. The compressive strength of the resulting specimens was measured. The evolution of hydration of the cement-tile blends was analyzed by XRD and FTIR techniques. Vibrational spectroscopy presented accurate evidence of pozzolanic activity. The results of the investigation confirmed the potential use of these waste materials to produce pozzolanic cement. PMID:19124234

  16. 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.

  17. Characterization of ceramic roof tile wastes as pozzolanic admixture.

    PubMed

    Lavat, Araceli E; Trezza, Monica A; Poggi, Mónica

    2009-05-01

    The aim of this work is to study the recycling of tile wastes in the manufacture of blended cements. Cracked or broken ceramic bodies are not accepted as commercial products and, therefore, the unsold waste of the ceramic industry becomes an environment problem. The use of powdered roof tile in cement production, as pozzolanic addition, is reported. The wastes were classified as nonglazed, natural and black glazed tiles. The mineralogy of the powders was controlled by SEM-EDX microscopy, XRD analysis and FTIR spectroscopy. Particle size was checked by laser granulometry. Once the materials were fully characterized, pozzolanic lime consumption tests and Fratini tests were carried out. Different formulations of cement-tile blends were prepared by incorporation of up to 30% weight ratios of recycled waste. The compressive strength of the resulting specimens was measured. The evolution of hydration of the cement-tile blends was analyzed by XRD and FTIR techniques. Vibrational spectroscopy presented accurate evidence of pozzolanic activity. The results of the investigation confirmed the potential use of these waste materials to produce pozzolanic cement.

  18. 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.

  19. Removal of the deposition on JT-60 tile by nano-sec pulsed-laser irradiation

    NASA Astrophysics Data System (ADS)

    Sugiyama, K.; Sakawa, Y.; Tanabe, T.; Watanabe, D.; Shibahara, T.; Masaki, K.

    2010-10-01

    To clarify the property of tritium removal from carbon codeposition by using pulsed-laser induced desorption, hydrogen removal from co-deposits on JT-60 divertor tile using a fourth-harmonic emission (266 nm) of a nano-sec Nd:YAG laser was demonstrated. The threshold laser fluence for ablation was ˜0.3 J/cm 2, which was slightly higher compared to that of the pico-sec laser irradiation. The energy absorption coefficient for the nano-sec laser, which was obtained by fitting the removal rate by so-called Beer's law, was larger than the pico-sec laser. Since the time constant of thermal wave propagation into the target is of the order of nano-sec, such differences between nano- and pico-sec lasers could be attributed to thermal effects. The ablation threshold of the deposited layer was lower than that of a pure graphite, which could be attributed to the difference of thermal conductivity between deposited layer and pure graphite. The removal rate of the nano-sec laser was higher than that of pico-sec laser in the fluence range of >˜0.5 J/cm 2. On the other hand, the production ratio [hydrocarbon species]/[H 2] continuously increased with the laser fluence, and no significant ionization of carbon was observed in this fluence range. This indicated that the fluence range in this study was "weak"-ablation range, which was still not sufficient to minimize the hydrocarbon production.

  20. 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.

  1. 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.

  2. 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.

  3. Web system to support analysis of the Tile Calorimeter commissioning

    NASA Astrophysics Data System (ADS)

    Maidantchik, C.; Faria, A.; Grael, F. F.; Ferreira, F. G.; Galvão, K. K.; Dotti, A.; Solans, C.; Price, L.

    2008-07-01

    This article describes the set of computer systems that support the data analysis and quality control during the Tile Calorimeter commissioning phase. The Tile Commissioning Web System (TCWS) encapsulates the steps to retrieve information, execute programs, access the outcomes, register statements and verify the equipment status. TCWS integrates different applications, each one presenting a particular view of the commissioning process. The TileComm Analysis stores plots and analysis results, provides equipment-oriented visualization, collects information regarding the equipment performance, and outlines its status in each test. The Timeline application provides the equipment status history in a chronological way. The Web Interface for Shifters supports monitoring tasks by managing test parameters, graphical views of the detector's performance, and information status of all equipment that was used in each test. The DCS Web System provides a standard way to verify the behaviour of power sources and the cooling system.

  4. Flow and heat transfer in space vehicle tile gaps

    NASA Technical Reports Server (NTRS)

    Garimella, S. V.; Shollenberger, K. A.; Eibeck, P. A.; White, S.

    1992-01-01

    The flow patterns and the characteristics of the convective heat transfer in intersecting tile gaps on space vehicles were experimentally investigated using a water channel flow facility for simulating flow conditions in the tile gaps on the Aeroassist Flight Experiment (AFE) vehicle. It was found that penetration of external flow into the perpendicular gap was limited in most cases to roughly two gap widths, while greater entrainment occurred in the parallel gap. Heat transfer in the bulk of the perpendicular gap occurred by natural convection. The Reynolds number and the relative tile-height differences had the strongest influence on heat transfer and affected both the magnitude and the symmetry of the temperature and the flow fields.

  5. 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.

  6. Mechanical construction and installation of the ATLAS tile calorimeter

    NASA Astrophysics Data System (ADS)

    Abdallah, J.; Adragna, P.; Alexa, C.; Alves, R.; Amaral, P.; Ananiev, A.; Anderson, K.; Andresen, X.; Antonaki, A.; Batusov, V.; Bednar, P.; Behrens, A.; Bergeaas, E.; Biscarat, C.; Blanch, O.; Blanchot, G.; Blocki, J.; Bohm, C.; Boldea, V.; Bosi, F.; Bosman, M.; Bromberg, C.; Brunel, B.; Budagov, J.; Calderón, D.; Calvet, D.; Cardeira, C.; Carli, T.; Carvalho, J.; Cascella, M.; Castillo, M. V.; Costello, J.; Cavalli-Sforza, M.; Cavasinni, V.; Cerqueira, A. S.; Clement, C.; Cobal, M.; Cogswell, F.; Constantinescu, S.; Costanzo, D.; Da Silva, P.; David, M.; Davidek, T.; Dawson, J.; De, K.; Del Prete, T.; Di Girolamo, B.; Dita, S.; Dolejsi, J.; Dolezal, Z.; Dotti, A.; Downing, R.; Drake, G.; Efthymiopoulos, I.; Errede, D.; Errede, S.; Farbin, A.; Fassouliotis, D.; Feng, E.; Fenyuk, A.; Ferdi, C.; Ferreira, B. C.; Ferrer, A.; Ferrer, J.; Flaminio, V.; Flix, J.; Francavilla, P.; Fullana, E.; Garde, V.; Gayde, J. C.; Gellerstedt, K.; Giakoumopoulou, V.; Giangiobbe, V.; Gildemeister, O.; Gilewsky, V.; Giokaris, N.; Gollub, N.; Gomes, A.; Gonzalez, V.; Gouveia, J.; Grenier, P.; Gris, P.; Grudzinski, J.; Guarino, V.; Guicheney, C.; Gupta, A.; Hakobyan, H.; Haney, M.; Hellman, S.; Henriques, A.; Higon, E.; Hill, N.; Holmgren, S.; Hruska, I.; Hurwitz, M.; Huston, J.; Jen-La Plante, I.; Jon-And, K.; Junk, T.; Karyukhin, A.; Khubua, J.; Klereborn, J.; Kopikov, S.; Korolkov, I.; Krivkova, P.; Kulchitsky, Y.; Kurochkin, Y.; Kuzhir, P.; Lapin, V.; Lasseur, C.; LeCompte, T.; Lefevre, R.; Leitner, R.; Li, J.; Lyablin, M.; Lim, H.; Lokajicek, M.; Lomakin, Y.; Lourtie, P.; Lovas, L.; Lupi, A.; Maidantchik, C.; Maio, A.; Maliukov, S.; Manousakis, A.; Marques, C.; Marroquim, F.; Martin, F.; Mazzoni, E.; Mergelkuhl, D.; Merritt, F.; Miagkov, A.; Miller, R.; Minashvili, I.; Miralles, L.; Montarou, G.; Nemecek, S.; Nessi, M.; Nikitine, I.; Nodulman, L.; Norniella, O.; Nyman, T.; Onofre, A.; Oreglia, M.; Palan, B.; Pallin, D.; Pantea, D.; Pereira, A.; Pilcher, J.; Pina, J.; Pinhão, J.; Pod, E.; Podlyski, F.; Portell, X.; Poveda, J.; Pribyl, L.; Price, L. E.; Proudfoot, J.; Ramalho, M.; Ramstedt, M.; Raposeiro, L.; Reis, J.; Richards, R.; Roda, C.; Romanov, V.; Rose-Dulcina, L.; Rosnet, P.; Roy, P.; Ruiz, A.; Rumiantsau, V.; Russakovich, N.; da Costa, J. Sa; Salto, O.; Salvachua, B.; Sanchis, E.; Sanders, H.; Santoni, C.; Santos, J.; Saraiva, J. G.; Sarri, F.; Says, L.-P.; Schlager, G.; Schlereth, J.; Seixas, J. M.; Selldèn, B.; Shalanda, N.; Shchelchkov, A.; Shevtsov, P.; Shochet, M.; Silva, J.; Simaitis, V.; Simonyan, M.; Sissakian, A.; Sjoelin, J.; Skrzecz, F.; Solans, C.; Solodkov, A.; Solovianov, O.; Sorokina, J.; Sosebee, M.; Spano, F.; Speckmeyer, P.; Stanek, R.; Starchenko, E.; Starovoitov, P.; Suk, M.; Sykora, I.; Tang, F.; Tas, P.; Teuscher, R.; Tokar, S.; Topilin, N.; Torres, J.; Underwood, D.; Usai, G.; Utkin, V.; Valero, A.; Valkar, S.; Valls, J. A.; Vartapetian, A.; Vazeille, F.; Vellidis, C.; Ventura, F.; Vichou, I.; Vivarelli, I.; Volpi, M.; White, A.; Wood, K.; Zaitsev, A.; Zenin, A.; Zenis, T.; Zenonos, Z.; Zenz, S.; Zilka, B.

    2013-11-01

    This paper summarises the mechanical construction and installation of the Tile Calorimeter for the ATLAS experiment at the Large Hadron Collider in CERN, Switzerland. The Tile Calorimeter is a sampling calorimeter using scintillator as the sensitive detector and steel as the absorber and covers the central region of the ATLAS experiment up to pseudorapidities ±1.7. The mechanical construction of the Tile Calorimeter occurred over a period of about 10 years beginning in 1995 with the completion of the Technical Design Report and ending in 2006 with the installation of the final module in the ATLAS cavern. During this period approximately 2600 metric tons of steel were transformed into a laminated structure to form the absorber of the sampling calorimeter. Following instrumentation and testing, which is described elsewhere, the modules were installed in the ATLAS cavern with a remarkable accuracy for a structure of this size and weight.

  7. 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.

  8. Fly ash of mineral coal as ceramic tiles raw material.

    PubMed

    Zimmer, A; Bergmann, C P

    2007-01-01

    The aim of this work was to evaluate the use of mineral coal fly ash as a raw material in the production of ceramic tiles. The samples of fly ash came from Capivari de Baixo, a city situated in the Brazilian Federal State of Santa Catarina. The fly ash and the raw materials were characterized regarding their physical chemical properties, and, based on these results; batches containing fly ash and typical raw materials for ceramic tiles were prepared. The fly ash content in the batches varied between 20 and 80 wt%. Specimens were molded using a uniaxial hydraulic press and were fired. All batches containing ash up to 60 wt% present adequate properties to be classified as several kinds of products in the ISO 13006 standard () regarding its different absorption groups (pressed). The results obtained indicate that fly ash, when mixed with traditional raw materials, has the necessary requirements to be used as a raw material for production of ceramic tiles.

  9. 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.

  10. 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 this paper, the…

  11. 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.

  12. Study of Effects of Different Reactions on Plasma Parameters in D-T Magnetic Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Motevalli, S. M.; Fadaei, F.

    2012-09-01

    The consideration of the three main nuclear reactions of the hydrogen isotopes (D(D, n)3He, D(D, p)T and T(D, n)4He) only leads to wrong results for determination of plasma parameters in magnetic confinement fusion reactors. The nuclear reaction 3He(D, p)4He influences the amount of produced tritium since it makes an important contribution to the charged particle energy deposition and to the temperatures. In this paper, we have considered different nuclear reactions of Deuterium-Tritium (D-T) fusion in tokamak reactor. This study has been carried out on the base of the particle and power balance equations in a zero-dimensional model then plasma parameters have been calculated. Finally, the obtained results have been compared with the theoretical results reported by other researchers.

  13. 3D+t brain MRI segmentation using robust 4D Hidden Markov Chain.

    PubMed

    Lavigne, François; Collet, Christophe; Armspach, Jean-Paul

    2014-01-01

    In recent years many automatic methods have been developed to help physicians diagnose brain disorders, but the problem remains complex. In this paper we propose a method to segment brain structures on two 3D multi-modal MR images taken at different times (longitudinal acquisition). A bias field correction is performed with an adaptation of the Hidden Markov Chain (HMC) allowing us to take into account the temporal correlation in addition to spatial neighbourhood information. To improve the robustness of the segmentation of the principal brain structures and to detect Multiple Sclerosis Lesions as outliers the Trimmed Likelihood Estimator (TLE) is used during the process. The method is validated on 3D+t brain MR images. PMID:25571045

  14. Three dimensional template matching segmentation method for motile cells in 3D+t video sequences.

    PubMed

    Pimentel, J A; Corkidi, G

    2010-01-01

    In this work, we describe a segmentation cell method oriented to deal with experimental data obtained from 3D+t microscopical volumes. The proposed segmentation technique takes advantage of the pattern of appearances exhibited by the objects (cells) from different focal planes, as a result of the object translucent properties and its interaction with light. This information allows us to discriminate between cells and artifacts (dust an other) with equivalent size and shape that are present in the biological preparation. Using a simple correlation criteria, the method matches a 3D video template (extracted from a sample of cells) with the motile cells contained into the biological sample, obtaining a high rate of true positives while discarding artifacts. In this work, our analysis is focused on sea urchin spermatozoa cells but is applicable to many other microscopical structures having the same optical properties. PMID:21096252

  15. H∞ control for 2-D T-S fuzzy FMII model with stochastic perturbation

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng; Wang, Weiqun; Li, Lizhen

    2015-03-01

    This paper deals with the problem of H∞ control for 2-D non-linear system with stochastic perturbation. Based on spatial fuzzy set and inference mechanism, 2-D T-S fuzzy FMII model with stochastic perturbation is established first. Then the results for stability analysis and bounded real lemma are obtained. Moreover, an H∞ fuzzy controller is designed. In order to reduce the computational demand of the conditions for the existence of H∞ fuzzy controller, the control inputs are regarded as the variables independent of the states, and some free matrices are introduced to reduce the conservatism of this method. Then, a new H∞ fuzzy controller is derived. Two simulation examples are given to illustrate the effectiveness of the proposed approach.

  16. 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.

  17. 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.

  18. 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.

  19. An automated data management/analysis system for space shuttle orbiter tiles. [stress analysis

    NASA Technical Reports Server (NTRS)

    Giles, G. L.; Ballas, M.

    1982-01-01

    An engineering data management system was combined with a nonlinear stress analysis program to provide a capability for analyzing a large number of tiles on the space shuttle orbiter. Tile geometry data and all data necessary of define the tile loads environment accessed automatically as needed for the analysis of a particular tile or a set of tiles. User documentation provided includes: (1) description of computer programs and data files contained in the system; (2) definitions of all engineering data stored in the data base; (3) characteristics of the tile anaytical model; (4) instructions for preparation of user input; and (5) a sample problem to illustrate use of the system. Description of data, computer programs, and analytical models of the tile are sufficiently detailed to guide extension of the system to include additional zones of tiles and/or additional types of analyses

  20. 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.

  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. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

    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.

  15. 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.

  16. Structure of mutagen nucleic acid complexes in solution. Proton chemical shifts in 9-aminoacridine complexes with dG-dC, dC-dG, and dA-dT-dG-dC-dA-dT.

    PubMed

    Reuben, J; Baker, B M; Kallenbach, N R

    1978-07-11

    The influence of self-complementary oligodeoxynucleotides on the chemical shifts of protons of the mutagenic acridine dye 9-aminoacridine has been measured. Upfield shifts indicative of intercalative binding are found in the cases of dG-dC, dC-dG, and dA-dT-dG-dC-dA-dT but not in dA-dT. Geometries for the complexes that are compatibile with the chemical-shift data and the X-ray structure of the complex between ri5C-rG and 9-aminoacridine determined by Sakore et al. [Sakore, T.D., Jain, S.C., Tsai, C., and Sobell, H.M. (1977), Proc. Natl. Acad. Sci. U.S.A. 74, 188--192] can be identified using recent theoretical estimates of shifts induced by nucleotide bases.

  17. 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...

  18. 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.

  19. A novel surface defect inspection algorithm for magnetic tile

    NASA Astrophysics Data System (ADS)

    Xie, Luofeng; Lin, Lijun; Yin, Ming; Meng, Lintao; Yin, Guofu

    2016-07-01

    In this paper, we propose a defect extraction method for magnetic tile images based on the shearlet transform. The shearlet transform is a method of multi-scale geometric analysis. Compared with similar methods, the shearlet transform offers higher directional sensitivity and this is useful to accurately extract geometric characteristics from data. In general, a magnetic tile image captured by CCD camera mainly consists of target area, background. Our strategy for extracting the surface defects of magnetic tile comprises two steps: image preprocessing and defect extraction. Both steps are critical. After preprocessing the image, we extract the target area. Due to the low contrast in the magnetic tile image, we apply the discrete shearlet transform to enhance the contrast between the defect area and the normal area. Next, we apply a threshold method to generate a binary image. To validate our algorithm, we compare our experimental results with Otsu method, the curvelet transform and the nonsubsampled contourlet transform. Results show that our algorithm outperforms the other methods considered and can very effectively extract defects.

  20. 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...

  1. 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...

  2. Kinetics of the clay roofing tile convection drying

    SciTech Connect

    Thomas, S. . Faculty of Food Technology); Skansi, D. . Faculty of Chemical Engineering and Technology); Sokele, M. . Telecommunications Center)

    1993-01-01

    Kinetics of the convection drying process of flat tile has been investigated experimentally in an industrial tunnel dryer. Several velocities of wet tile movement through the dryer were tested to obtain maximum allowable drying rate curve. As there are various models to describe the kinetics of convection drying, finding a model that would fairly well approximate the kinetics of the whole drying process was part of the research. Especially the polynomial and exponential models were tested. It was found that exponential model of the type: B(t) = (a[minus]B[sub e])[center dot]EXP([minus]bt[sup 2])+B[sub e], ([minus]dB(t)/dt) = 2bt(B(t)[minus]B[sub e]) significantly correlates the kinetics of the whole tile drying process. Applying the maximum allowable drying rate curve obtained for flat tile in the first period of drying, a grapho-analytic model for the optimal conducting of the process has been developed.

  3. Tiles made from slag sitall based on chemical industry slag

    SciTech Connect

    Batalin, B.S.; Moskalets, N.B.; Klyuchnik, I.A.; Golius, T.E.

    1987-11-01

    The authors establish the feasibility of obtaining ceramic silicate-based facing tiles from fluoroamphibole slag sitall wastes from the hydropyrolytic production of hydrogen fluoride. The recovered ceramic is tested by x-ray diffraction and electron microscopy for its crystallization behavior, structure, workability, corrosion resistance, phase composition, impact strength, and other properties.

  4. Increasing the frost resistance of facade glazed tiles

    SciTech Connect

    Egerev, V.M.; Zotov, S.N.; Romanova, G.P.

    1986-09-01

    The authors investigate the protective properties of a coating of boron oxides and zirconium oxides applied as a glaze to ceramic tiles by conducting a series of tests to determine the frost resistance, the propensity to absorb water, the moisture expansion coefficient, the fracture behavior, and the effect of thermal cycling on the oxides. Results are graphed and tabulated.

  5. Direct readout of gaseous detectors with tiled CMOS circuits

    NASA Astrophysics Data System (ADS)

    Visschers, J. L.; Blanco Carballo, V.; Chefdeville, M.; Colas, P.; van der Graaf, H.; Schmitz, J.; Smits, S.; Timmermans, J.

    2007-03-01

    A coordinated design effort is underway, exploring the three-dimensional direct readout of gaseous detectors by an anode plate equipped with a tiled array of many CMOS pixel readout ASICs, having amplification grids integrated on their topsides and being contacted on their backside.

  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. Fracture toughness of anisotropic graphites

    SciTech Connect

    Kennedy, C.R.; Kehne, M.T.

    1985-01-01

    Fracture toughness measurements have been made at 0, 30, 45, 60, and 90/sup 0/ from the extrusion axis on a reasonably anisotropic graphite, grade AGOT. It was found that the fracture toughness did not vary appreciably with orientation. An observed variation in strength was found to be the result of defect orientation.

  9. 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

    2015-10-01

    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. PMID:26632800

  10. Thermal neutron scattering in graphite

    NASA Astrophysics Data System (ADS)

    Al-Qasir, Iyad Ibrahim

    Generation IV Very High Temperature Reactor (VHTR) concepts, are graphite moderated and gas cooled thermal spectrum reactors. The characteristics of the low energy (E < 1 eV) neutron spectrum in these reactors will be dictated by the process of neutron slowing-down and thermalization in the graphite moderator. The ability to accurately predict this process in these reactors can have significant neutronic and safety implications. In reactor design calculations, thermal neutron scattering cross section libraries are needed for the prediction of the thermal neutron environment in the core. Currently used libraries (ENDF/B-VII) are a product of the 1960s and remain based on many physical approximations. In addition, these libraries show noticeable discrepancies with experimental data. In this work, investigation of thermal neutron scattering in graphite as a function of temperature was performed. The fundamental input for the calculation of thermal neutron scattering cross sections, i.e., the phonon frequency distribution and/or the dispersion relations, was generated using a modern approach that is based on quantum mechanical electronic structure (ab initio) simulations combined with a lattice dynamics direct method supercell approach. The calculations were performed using the VASP and PHONON codes. The VASP calculations used the local density approximation, and the projector augmented-wave pseudopotential. A supercell of 144 atoms was used; and the integration over the Brillouin zone was confined to a 3x3x4 k-mesh generated by the Monkhorst-Pack scheme. A plane-wave basis set with an energy cutoff of 500 eV was applied. The corresponding dispersion relations, heat capacity, and phonon frequency distribution show excellent agreement with experimental data. Despite the use of the above techniques to produce more accurate input data, the examination of the results indicated persistence of the inconsistencies between calculations and measurements at neutron energies

  11. 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

  12. Fixed tile rate codec for bandwidth saving in video processors

    NASA Astrophysics Data System (ADS)

    Lachine, Vladimir; Dinh, Chon-Tam Le; Le, Dinh Kha; Wong, Jeffrey

    2014-02-01

    The paper presents an image compression circuit for bandwidth saving in video display processors. This is intra frame tile based compression algorithm offering visually lossless quality for compression rates between 1.5 and 2.5. RGB and YCbCr (4:4:4, 4:2:2 and 4:2:0) video formats are supported for 8/10 bits video signals. The Band Width Compressor (BWC) consists of Lossless Compressor (LC) and Quantization Compressor (QC) that generate output bit streams for tiles of pixels. Size of output bit stream generated for a tile by the LC may be less or greater than a required size of output memory block. The QC generates bit stream that always fits output memory block of the required size. The output bit stream generated by the LC is transmitted if its size is less than the required size of the output memory block. Otherwise, the output bit stream generated by the QC is transmitted. The LC works on pixel basis. A difference between original and predicted pixel's values for each pixel of a tile is encoded as prefix and suffix. The prefix is encoded by means of variable length code, and suffix is encoded as is. The QC divides a tile of pixels on a set of blocks and quantizes pixels of each block independently of the other blocks. The number of quantization bits for all pixels of a block depends on standard deviation calculated over the block. A difference between pixel's value and average value over the block is quantized and transmitted.

  13. 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.

  14. 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.

  15. 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.

  16. Aortic valve and ascending aortic root modeling from 3D and 3D+t CT

    NASA Astrophysics Data System (ADS)

    Grbic, Saša; Ionasec, Razvan I.; Zäuner, Dominik; Zheng, Yefeng; Georgescu, Bogdan; Comaniciu, Dorin

    2010-02-01

    Aortic valve disorders are the most frequent form of valvular heart disorders (VHD) affecting nearly 3% of the global population. A large fraction among them are aortic root diseases, such as aortic root aneurysm, often requiring surgical procedures (valve-sparing) as a treatment. Visual non-invasive assessment techniques could assist during pre-selection of adequate patients, planning procedures and afterward evaluation of the same. However state of the art approaches try to model a rather short part of the aortic root, insufficient to assist the physician during intervention planning. In this paper we propose a novel approach for morphological and functional quantification of both the aortic valve and the ascending aortic root. A novel physiological shape model is introduced, consisting of the aortic valve root, leaflets and the ascending aortic root. The model parameters are hierarchically estimated using robust and fast learning-based methods. Experiments performed on 63 CT sequences (630 Volumes) and 20 single phase CT volumes demonstrated an accuracy of 1.45mm and an performance of 30 seconds (3D+t) for this approach. To the best of our knowledge this is the first time a complete model of the aortic valve (including leaflets) and the ascending aortic root, estimated from CT, has been proposed.

  17. Gint2D-T2 correlation NMR of porous media

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Blümich, Bernhard

    2015-03-01

    The internal magnetic field gradient induced in porous media by magnetic susceptibility differences at material interfaces impacts diffusion measurements in particular at high magnetic field and can be used to probe the pore structure. Insight about the relationship between pore space and internal gradient Gint can be obtained from 2D Laplace NMR experiments. When measuring distributions of transverse relaxation times T2 in fluid filled porous media, relaxation and diffusion in internal gradients arise simultaneously and data are often interpreted with the assumption that one or the other parameter be constant throughout the sample. To examine this assumption we measure correlations of the distributions of Gint2D and T2 by 2D Laplace NMR for three different kinds of samples, glass beads with different bead diameters saturated with water, glass beads filled with oil and water, and a wet mortar sample. For the first two samples the cases where either the internal gradient or diffusion dominates were examined separately in order to better understand the relationship between Gint and D. These results are useful for assessing the impact of internal gradients and diffusion in unknown samples, such as the mortar sample. The experiments were performed at different magnetic field strengths corresponding to 300 MHz and 700 MHz 1H Larmor frequency to identify the impact of the magnetic field on the internal gradient. Subsequently, spatially resolved Gint2D-T2 maps were obtained to study the sample heterogeneity.

  18. Gint2D-T2 correlation NMR of porous media.

    PubMed

    Zhang, Yan; Blümich, Bernhard

    2015-03-01

    The internal magnetic field gradient induced in porous media by magnetic susceptibility differences at material interfaces impacts diffusion measurements in particular at high magnetic field and can be used to probe the pore structure. Insight about the relationship between pore space and internal gradient G(int) can be obtained from 2D Laplace NMR experiments. When measuring distributions of transverse relaxation times T(2) in fluid filled porous media, relaxation and diffusion in internal gradients arise simultaneously and data are often interpreted with the assumption that one or the other parameter be constant throughout the sample. To examine this assumption we measure correlations of the distributions of G(int)(2)D and T(2) by 2D Laplace NMR for three different kinds of samples, glass beads with different bead diameters saturated with water, glass beads filled with oil and water, and a wet mortar sample. For the first two samples the cases where either the internal gradient or diffusion dominates were examined separately in order to better understand the relationship between G(int) and D. These results are useful for assessing the impact of internal gradients and diffusion in unknown samples, such as the mortar sample. The experiments were performed at different magnetic field strengths corresponding to 300 MHz and 700 MHz (1)H Larmor frequency to identify the impact of the magnetic field on the internal gradient. Subsequently, spatially resolved Gint(2)D-T(2) maps were obtained to study the sample heterogeneity. PMID:25723135

  19. Spectroscopic Factors from the Single Neutron Pickup Reaction ^64Zn(d,t)

    NASA Astrophysics Data System (ADS)

    Leach, Kyle; Garrett, P. E.; Ball, G. C.; Bangay, J. C.; Bianco, L.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Krücken, R.; Phillips, A. A.; Rand, E. T.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wirth, H.-F.; Wong, J.

    2009-10-01

    A great deal of attention has recently been paid towards high-precision superallowed β-decay Ft values. With the availability of extremely high-precision (<0.1%) experimental data, precision on the individual Ft values are now dominated by the ˜1% theoretical corrections^[1]. This limitation is most evident in heavier superallowed nuclei (e.g. ^62Ga) where the isospin-symmetry-breaking (ISB) correction calculations become more difficult due to the truncated model space. Experimental spectroscopic factors for these nuclei are important for the identification of the relevant orbitals that should be included in the model space of the calculations. Motivated by this need, the single-nucleon transfer reaction ^64Zn(d,t)^63Zn was conducted at the Maier-Leibnitz-Laboratory (MLL) of TUM/LMU in Munich, Germany, using a 22 MeV polarized deuteron beam from the tandem Van de Graaff accelerator and the TUM/LMU Q3D magnetic spectrograph, with angular distributions from 10^o to 60^o. Results from this experiment will be presented and implications for calculations of ISB corrections in the superallowed &+circ; decay of ^62Ga will be discussed.^[1] I.S. Towner and J.C. Hardy, Phys. Rev. C 77, 025501 (2008).

  20. Spectroscopic Factors from the Single Neutron Pickup ^64Zn(d,t)

    NASA Astrophysics Data System (ADS)

    Leach, Kyle; Garrett, P. E.; Demand, G. A.; Finlay, P.; Green, K. L.; Phillips, A. A.; Rand, E. T.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wong, J.; Towner, I. S.; Ball, G. C.; Faestermann, T.; Krücken, R.; Hertenberger, R.; Wirth, H.-F.

    2010-11-01

    A great deal of attention has recently been paid towards high-precision superallowed β-decay Ft values. With the availability of extremely high-precision (<0.1%) experimental data, precision on the individual Ft values are now dominated by the ˜1% theoretical corrections. This limitation is most evident in heavier superallowed nuclei (e.g. ^62Ga) where the isospin-symmetry-breaking (ISB) correction calculations become more difficult due to the truncated model space. Experimental spectroscopic factors for these nuclei are important for the identification of the relevant orbitals that should be included in the model space of the calculations. Motivated by this need, the single-nucleon transfer reaction ^64Zn(d,t)^63Zn was conducted at the Maier-Leibnitz-Laboratory (MLL) of TUM/LMU in Munich, Germany, using a 22 MeV polarized deuteron beam from the tandem Van de Graaff accelerator and the TUM/LMU Q3D magnetic spectrograph, with angular distributions from 10^o to 60^o. Results from this experiment will be presented and implications for calculations of ISB corrections in the superallowed ° decay of ^62Ga will be discussed.

  1. 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.

  2. 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. PMID:26945102

  3. 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.

  4. LET spectrometry of 14 MeV (D-T) neutrons using CR-39 track detectors

    NASA Astrophysics Data System (ADS)

    Sahoo, G. S.; Tripathy, S. P.; Sunil, C.; Sarkar, P. K.

    2013-04-01

    Linear energy transfer (LET) spectrum in water in the range of 12 keV/μm to 382 keV/μm due to 14 MeV (D-T) neutrons is estimated using the track size parameters in two different types of CR-39 track detectors, viz. Intercast (1.5 mm) and Pershore (0.5 mm). Another set of CR-39s (Intercast) combined with 1 mm polyethylene (PE) radiators is exposed to study the effect of enhanced recoils on the LET spectrum. The detection efficiencies for all these cases and the enhancement ratio due to PE radiator are determined. Using this LET spectrum, the microdosimetric spectra of absorbed doses and dose equivalents are estimated based on the Q-L conversion factors as given in ICRP 60. The shape of the LET spectra are found to be similar in all the cases, however, the dose equivalents obtained with the CR-39+PE radiator is about 20% more than the other detectors without PE. The ratios of dose equivalents obtained from LET spectra (HLET) and the ambient dose equivalent (H*(10)) obtained from fluence-to-dose equivalent conversion factors (ICRP 74) for 14 MeV neutrons are used to estimate the dose response of the detectors. H*(10) is also measured using a neutron rem meter, the response of which is found to be about 23% less than the actual dose.

  5. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reactions by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  6. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reaction by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  7. 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.

  8. 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.

  9. Life considerations of the shuttle orbiter densified-tile thermal protection system

    NASA Technical Reports Server (NTRS)

    Cooper, P. A.; Sawyer, J. W.

    1983-01-01

    The Shuttle orbiter themal protection system (TPS) incorporates ceramic reusable surface insulation tiles bonded to the orbiter substructure through a strain isolation pad. Densification of the bonding surface of the tiles increases the static strength of the tiles. The densification proces does not, however, necessarily lead to an equivalent increase in fatigue strength. Investigation of the expected lifetime of densified tile TPS under both sinusoidal loading and random loading simulating flight conditions indicates that the strain isolation pads are the weakest components of the TPS under fatigue loading. The felt pads loosen under repetitive loading and, in highly loaded regions, could possibly cause excessive step heights between tiles causing burning of the protective insulation between tiles. A method of improving the operational lifetime of the TPS by using a strain isolation pad with increased stiffness is presented as is the consequence of the effect of increased stiffness on the tile inplane strains and transverse stresses.

  10. Procedure and analysis reports in support of the hollow clay tile wall testing program

    SciTech Connect

    Not Available

    1990-11-01

    The following are included that were generated in the research program on the structural behavior of clay tile walls: test procedure for out-of-plane full scale static testing of a hollow clay tile wall panel, ultimate strength calculations for out-of-plane air bag tests, test procedure for in-plane infilled frame static testing of a hollow clay tile wall panel, in-plane infilled frame static testing of a hollow clay tile wall panel (calculations), test procedure for in-plane masonry static testing of a hollow clay tile wall panel, numerical analysis for in-plane behavior of infilled frames, in-plane analysis of hollow clay tile infilled frames (effect of wall-frame interface and connection rigidity), test procedure for in-plane masonry biaxial compressiont esting of a hollow clay tile wall panel, and outbuilding test program. (DLC)

  11. Procedure and analysis reports in support of the hollow clay tile wall testing program. Revision 1

    SciTech Connect

    Not Available

    1990-11-01

    The following are included that were generated in the research program on the structural behavior of clay tile walls: test procedure for out-of-plane full scale static testing of a hollow clay tile wall panel, ultimate strength calculations for out-of-plane air bag tests, test procedure for in-plane infilled frame static testing of a hollow clay tile wall panel, in-plane infilled frame static testing of a hollow clay tile wall panel (calculations), test procedure for in-plane masonry static testing of a hollow clay tile wall panel, numerical analysis for in-plane behavior of infilled frames, in-plane analysis of hollow clay tile infilled frames (effect of wall-frame interface and connection rigidity), test procedure for in-plane masonry biaxial compressiont esting of a hollow clay tile wall panel, and outbuilding test program. (DLC)

  12. Netropsin . dG-dG-dA-dA-dT-dT-dC-dC complex. Antibiotic binding at adenine . thymine base pairs in the minor groove of the self-complementary octanucleotide duplex.

    PubMed

    Patel, D J

    1979-09-01

    The structure of the netropsin . dG-dG-dA-dA-dT-dT-dC-dC complex (one antibiotic molecule/self-complementary octanucleodide duplex) and its dynamics as a function of temperature have been monitored by the nuclear magnetic resonances of the Watson-Crick protons, the nonexchangeable base and sugar protons and the backbone phosphates. The antibiotic forms a complex with the nucleic acid duplex at the dA . dT-containing tetranucleotide segment dA-dA-dT-dT, with slow migration amongst potential binding sites at low temperature. The downfield shifts in the exchangeable protons of netropsin on complex formation demonstrate the contributions of hydrogen-bonding interactions between the antibiotic and the nucleic acid to the stability of the complex. Complex formation results in changes in the glycosidic torsion angles of both thymidine residues and one deoxyadenosine residue as monitored by chemical shift changes in the thymine C-6 and adenine C-8 protons. The close proximity of the pyrrole rings of the antibiotic and the base-pair edges in the minor groove is manifested in the downfield shifts (0.3--0.5 ppm) of the pyrrole C-3 protons of netropsin and one adenine C-2 proton and one thymine N-3 base-pair proton on complex formation. The internucleotide phosphates of the octanucleotide undergo 31P chemical shift changes on addition of netropsin and these may reflect, in part, contributions from electrostatic interactions between the charged ends of the antibiotic and the backbone phosphates of the nucleic acid.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. Observation of the 16.7 MeV D-T fusion gamma using a gas Cerenkov detector

    NASA Astrophysics Data System (ADS)

    Ladish, J. S.; Toevs, J. W.; Young, C. S.; Nash, P.; Iversen, S.; Zagarino, P.; Jennings, L.; Seno, R. D.

    A measurement of the 16.7 MeV gamma production in a D-T fusion plasma was performed, using a four channel carbon dioxide gas Cerenkov detector system to measure the Cerenkov light generated by the gamma conversion electrons produced in a thin aluminum foil.

  19. 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.

  20. 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.

  1. Study of the effect of nano surface morphology on the stain-resistant property of ceramic tiles

    NASA Astrophysics Data System (ADS)

    Pan, S. P.; Hung, J. K.; Liu, Y. T.

    2014-03-01

    In this study, six types of commercially available ceramic tiles, including nano-structured ceramic tiles and regular ceramic tiles, were selected to investigate the effect of surface morphology on their stain-resistant property. The stain-resistant efficiencies of various ceramic tiles with nano-size surface were measured in order to determine the appropriate method for testing ceramic tiles with nano-structure surface.

  2. 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.

  3. Inspection of magnetic tile internal cracks based on impact acoustics

    NASA Astrophysics Data System (ADS)

    Xie, Luofeng; Huang, Qinyuan; Zhao, Yue; Yin, Guofu

    2015-04-01

    An automatic system is developed for internal cracks detection in magnetic tiles based on the impact acoustics, using wavelet packet transform (WPT), principal component analysis (PCA) and hidden Markov model (HMM). In this system, the detecting device is considered as core part to collect and analyse the impact sounds. The original impact sounds are first decomposed up to six levels based on WPT to extract the features. PCA is then performed for dimension reduction and clustering analysis. By adopting the features extracted based on WPT and optimised by PCA as inputs, an HHM classifier is developed for automatic inspection. The results of classification show that the accuracy rate is 100%, demonstrating that the system has significant potential in detecting magnetic tile internal cracks.

  4. 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.

  5. Structural state of expanded graphite prepared from intercalation compounds

    SciTech Connect

    Teplykh, A. E. Bogdanov, S. G.; Dorofeev, Yu. A.; Pirogov, A. N.; Skryabin, Yu. N.; Makotchenko, V. G.; Nazarov, A. S.; Fedorov, V. E.

    2006-12-15

    The structural state of nanocrystalline samples of expanded graphite is investigated using X-ray diffraction and neutron diffraction analyses. The expanded graphite samples are prepared by a rapid thermal decomposition of intercalation compounds of oxidized graphite based on fluorinated graphite, graphite oxide, and graphite aminofluoride. It is established that the main phase of expanded graphite belongs to the hexagonal crystal system (space group P6{sub 3}/mmc) and that carbon atoms in the structure occupy the 2b and 2c positions. The unit cell parameters and the unit cell volume in the structure of expanded graphite samples are larger than those in the structure of massive graphite.

  6. 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.

  7. 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.

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

    PubMed

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

    2014-10-01

    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

  9. 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.

  10. Experimental testing of hollow clay tile infilled frames

    SciTech Connect

    Flanagan, R.D. ); Bennett, R.M.; Barclay, G.A. . Dept. of Civil Engineering)

    1992-02-27

    A common building construction of the Oak Ridge Y-12 Plant is structural steel framing with infilled unreinforced hollow clay tile walls. A comprehensive program is underway to evaluate the resistance of this construction to natural phenomena loadings, particularly earthquake. This paper presents the results of the first series of large-scale infilled frame tests which were statically loaded in-plane to failure. Varying frame to infill stiffness was examined within the range of actual building construction.

  11. 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.

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

    SciTech Connect

    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.

  13. 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

  14. An integrated approach for assessing the bioreceptivity of glazed tiles to phototrophic microorganisms.

    PubMed

    Coutinho, M L; Miller, A Z; Rogerio-Candelera, M A; Mirão, J; Cerqueira Alves, L; Veiga, J P; Águas, H; Pereira, S; Lyubchyk, A; Macedo, M F

    2016-01-01

    A laboratory-based methodology was designed to assess the bioreceptivity of glazed tiles. The experimental set-up consisted of multiple steps: manufacturing of pristine and artificially aged glazed tiles, enrichment of phototrophic microorganisms, inoculation of phototrophs on glazed tiles, incubation under optimal conditions and quantification of biomass. In addition, tile intrinsic properties were assessed to determine which material properties contributed to tile bioreceptivity. Biofilm growth and biomass were appraised by digital image analysis, colorimetry and chlorophyll a analysis. SEM, micro-Raman and micro-particle induced X-ray emission analyses were carried out to investigate the biodeteriorating potential of phototrophic microorganisms on the glazed tiles. This practical and multidisciplinary approach showed that the accelerated colonization conditions allowed different types of tile bioreceptivity to be distinguished and to be related to precise characteristics of the material. Aged tiles showed higher bioreceptivity than pristine tiles due to their higher capillarity and permeability. Moreover, biophysical deterioration caused by chasmoendolithic growth was observed on colonized tile surfaces. PMID:26900634

  15. 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.

  16. An integrated approach for assessing the bioreceptivity of glazed tiles to phototrophic microorganisms.

    PubMed

    Coutinho, M L; Miller, A Z; Rogerio-Candelera, M A; Mirão, J; Cerqueira Alves, L; Veiga, J P; Águas, H; Pereira, S; Lyubchyk, A; Macedo, M F

    2016-01-01

    A laboratory-based methodology was designed to assess the bioreceptivity of glazed tiles. The experimental set-up consisted of multiple steps: manufacturing of pristine and artificially aged glazed tiles, enrichment of phototrophic microorganisms, inoculation of phototrophs on glazed tiles, incubation under optimal conditions and quantification of biomass. In addition, tile intrinsic properties were assessed to determine which material properties contributed to tile bioreceptivity. Biofilm growth and biomass were appraised by digital image analysis, colorimetry and chlorophyll a analysis. SEM, micro-Raman and micro-particle induced X-ray emission analyses were carried out to investigate the biodeteriorating potential of phototrophic microorganisms on the glazed tiles. This practical and multidisciplinary approach showed that the accelerated colonization conditions allowed different types of tile bioreceptivity to be distinguished and to be related to precise characteristics of the material. Aged tiles showed higher bioreceptivity than pristine tiles due to their higher capillarity and permeability. Moreover, biophysical deterioration caused by chasmoendolithic growth was observed on colonized tile surfaces.

  17. Signal reconstruction performance with the ATLAS Hadronic Tile Calorimeter

    NASA Astrophysics Data System (ADS)

    Klimek, Pawel; ATLAS Tile Calorimeter Group

    2012-12-01

    The Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of ATLAS. It is a key detector for the reconstruction of hadrons, jets, taus and missing transverse energy. TileCal is a sampling calorimeter with steel as absorber and scintillators as active medium. The scintillators are read-out by wavelength shifting fibers coupled to photomultiplier tubes (PMTs). The analogue signals from the PMTs are amplified, shaped and digitized by sampling the signal every 25 ns. The read out system is designed to reconstruct the data in real time fulfilling the tight constraints imposed by the ATLAS first level trigger rate (100 kHz). The signal amplitude for each channel and their phase are measured using Optimal Filtering techniques both at online and offline level. We present the performance of these techniques on the data collected in the proton-proton collisions at center-of-mass energy equal to 7 TeV. We will address the performance for the measurement on high pile-up environment and on various physics and calibration signals.

  18. A brief introduction to tiling microarrays: principles, concepts, and applications.

    PubMed

    Lemetre, Christophe; Zhang, Zhengdong D

    2013-01-01

    Technological achievements have always contributed to the advancement of biomedical research. It has never been more so than in recent times, when the development and application of innovative cutting-edge technologies have transformed biology into a data-rich quantitative science. This stunning revolution in biology primarily ensued from the emergence of microarrays over two decades ago. The completion of whole-genome sequencing projects and the advance in microarray manufacturing technologies enabled the development of tiling microarrays, which gave unprecedented genomic coverage. Since their first description, several types of application of tiling arrays have emerged, each aiming to tackle a different biological problem. Although numerous algorithms have already been developed to analyze microarray data, new method development is still needed not only for better performance but also for integration of available microarray data sets, which without doubt constitute one of the largest collections of biological data ever generated. In this chapter we first introduce the principles behind the emergence and the development of tiling microarrays, and then discuss with some examples how they are used to investigate different biological problems.

  19. 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.

  20. Functionalization of ceramic tile surface by sol-gel technique.

    PubMed

    Bondioli, F; Taurino, R; Ferrari, A M

    2009-06-15

    The aim of this investigation was the surface functionalization of industrial ceramic tiles by sol-gel technique to improve at the same time the cleanability of unglazed surfaces. This objective was pursued through the design and preparation of nanostructured coating that was deposited on polished unglazed tiles by air-brushing. In particular TiO(2)-SiO(2) binary film with 1, 2 or 5wt% of titania were prepared by using tetraethoxysilane and titania nanoparticles as precursors. The obtained films were characterized by scratch tests to verify the adhesion of the coatings to the polished tiles. To mainly evaluate the effect of the thermal treatment (temperature range 100-600 degrees C) on the photocatalicity of the coatings, the films were studied under UV exposure by contact angle measurements and cleanability test. Particular attention has been paid to preserve the aesthetical aspect of the final product and the obtained hue variation was evaluated by means of UV-visible spectroscopy and colorimetric analysis.

  1. Biofilm formation on the surface of ceramic tiles.

    PubMed

    Sessa, R; Di Pietro, M; Zamparelli, M; Schiavoni, G; Del Piano, M

    2000-10-01

    The aim of the study was to investigate the formation of biofilm on the surface of ceramic tiles, widely present in public and private buildings, using six parallel flow chambers. Our flow system was conceived and made to compare biofilm results by parallel distributed rectangular tiles. The tiles, divided into two identical A and B sections, were placed within the flow chambers. Biofilm formation was performed after 72 h and was quantified by viable counts of bacteria. Average viable counts ranged from 1.1x10(7) to 7.3x10(7) cfu cm(-2) and from 1.1x10(7) to 5.8x10(7) cfu cm(-2) respectively for biofilm A and B sections. As statistical analysis does not show significant differences, we can conclude that biofilms obtained were so similar to each other that they confirmed the system reproducibility. Our next step will be to use our system to study Legionella pneumophila and to evaluate the efficacy of antibacterial agents.

  2. 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.

  3. 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.

  4. 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.

  5. Sealing nuclear graphite with pyrolytic carbon

    NASA Astrophysics Data System (ADS)

    Feng, Shanglei; Xu, Li; Li, Li; Bai, Shuo; Yang, Xinmei; Zhou, Xingtai

    2013-10-01

    Pyrolytic carbon (PyC) coatings were deposited on IG-110 nuclear graphite by thermal decomposition of methane at ∼1830 °C. The PyC coatings are anisotropic and airtight enough to protect IG-110 nuclear graphite against the permeation of molten fluoride salts and the diffusion of gases. The investigations indicate that the sealing nuclear graphite with PyC coating is a promising method for its application in Molten Salt Reactor (MSR).

  6. 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.

  7. Small-angle x-ray scattering of intercalation compounds of graphite, fluorographite, and graphite oxide

    SciTech Connect

    Perevozkin, V.Yu.; Yur'ev, G.S.; Nazarov, A.S.; Danilenko, A.M.; Lisitsa, V.V.; Makotchenko, V.G.; Paasonen, V.M.; Yakovlev, I.I.

    1988-05-01

    Graphite intercalation compounds are interesting as cathode materials in chemical current sources and catalysts and are good conductors of electricity. Small-angle x-ray scattering was studied on natural graphite, intercalation compounds of fluorinated graphite, graphite oxide, and the products of reduction of the compounds. It was shown that scattering takes place in regions with a lower density and the size of the density inhomogeneities was determined.

  8. 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

  9. 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.

  10. 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)

  11. Hydrogen isotope trapping on graphite collectors during an isotope exchange experiment in the tokomak fusion test reactor

    SciTech Connect

    Kilpatrick, S.J.; Nygren, R.; Wampler, W.R.; Ulrickson, M.; Dylla, H.F.; Manos, D.M.; Ramsey, A.T.; Hirooka, Y.

    1988-01-01

    A rotatable collector probe was used to expose several graphite samples to a deuterium-to-hydrogen-to-deuterium exchange experiment in the Tokamak Fusion Test Reactor (TFTR) at the start of the 1988 operations period. This experiment proved the utility of helium conditioning discharges in accelerating the changeover process. Samples included portions of a tile taken from the inner bumper limiter (POCO AXF-5Q graphite) of TFTR during the recent machine opening, and coupons which had been conditioned in the Plasma Surface Interaction Experimental Facility (PISCES) by exposure to a helium plasma. The samples were exposed to different groups of the /approximately/100 1.4MA discharges that comprised the experiment. They were removed and analyzed for retained deuterium and impurities by nuclear reaction analysis and Rutherford backscattering spectrometry. Codeposited carbon layers had been formed with thicknesses up to several tenths of a micron. The inferred percentages of trapped hydrogenic species were in general agreement with spectroscopic data. The computed carbon fluence per D discharge, 1.2 /times/ 10 X C/cmS, is compared to recent measurements on limiter tiles removed from TFTR. 21 refs., 3 figs., 1 tab.

  12. 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. PMID:26340356

  13. 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.

  14. 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.

  15. 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.

  16. Gasifiable carbon-graphite fibers

    NASA Technical Reports Server (NTRS)

    Humphrey, Marshall F. (Inventor); Ramohalli, Kumar N. R. (Inventor); Dowler, Warren L. (Inventor)

    1982-01-01

    Fine, carbon-graphite fibers do not combust during the combustion of a composite and are expelled into the air as fine conductive particles. Coating of the fibers with a salt of a metal having a work function below 4.2 eV such as an alkaline earth metal salt, e.g., calcium acetate, catalytically enhances combustion of the fibers at temperatures below 1000.degree. C. such that the fibers self-support combustion and burn to produce a non-conductive ash. Fire-polishing the fibers before application of the coating is desirable to remove sizing to expose the carbon surface to the catalyst.

  17. 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.

  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. Benchmarking thermal neutron scattering in graphite

    NASA Astrophysics Data System (ADS)

    Zhou, Tong

    A Slowing-Down-Time experiment was designed and performed at the Oak Ridge National Laboratory (ORNL) by using the Oak Ridge Electron Linear Accelerator (ORELA) as a neutron source to study the neutron thermalization in graphite at room and higher temperatures. The MCNP5 code was utilized to simulate the detector responses and help optimize the experimental design including the size of the graphite assembly, furnace, shielding system and detector position. To facilitate such analysis, MCNP5 version 1.30 was modified to enable perturbation calculation using point detector type tallies. By using the modified MCNP5 code, the sensitivity of the experimental models to the graphite total thermal neutron cross-sections was studied to optimize the design of the experiment. Measurements of slowing-down-time spectrum in graphite were performed at room temperature for a 70x70x70 cm graphite pile by using a Li-6 scintillator and a U-235 fission counter at different locations. The measurements were directly compared to Monte Carlo simulations that use different graphite thermal neutron scattering cross-section libraries. Simulations based on the ENDF/B-VI graphite library were found to have a 30%-40% disagreement with the measurements. In addition to the graphite SDT experiment, which provided the data in the energy region above the graphite Bragg-cutoff energy, transmission experiments were performed for different types of graphite samples using the NIST 8.9 A beam (located at NG-6) to investigating the energy region below the Bragg-cutoff energy. Measurements confirmed that reactor grade graphite, which is a two phase material (crystalline graphite and binder (amorphous-like) carbon), has different thermal neutron scattering cross section from pyrolytic graphite (crystalline graphite). The experiments presented in this work compliment each other and provide an experimental data set which can be used to benchmark graphite thermal neutron scattering cross section libraries that

  20. Characteristics of the large (dA).(dT) homopolymer tracts in D. discoideum gene flanking and intron sequences.

    PubMed

    Marx, K A; Hess, S T; Blake, R D

    1993-08-01

    D. discoideum, the slime mold, is one of the most AT rich eukaryotic genomes known. In this paper we examine this organism's database for overlapping N-tuples of high frequency and find A and T tracts possess among the highest frequencies in flanking sequences but not in coding sequences. We examined both overlapping and non-overlapping frequencies of the A, T, G and C homopolymer tracts of 2 < N < 6. Overlapping (dG).(dC) and (dA).(dT) tracts occur at greater frequencies than expected, based on random occurrence. Long (dA).(dT) tracts of N > 10 occur at well above expected frequencies in flanking and intron regions, while (dG).(dC) tracts above N = 5 are rarely found. Some of the implications of these findings for tract origins in slip-strand replication and for chromatin structure are discussed.

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

    PubMed

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

    2016-09-19

    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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Geostatistical modelling with 3D+T data: soil moisture, temperature, and electrical conductivity at the field scale

    NASA Astrophysics Data System (ADS)

    Gasch, Caley K.; Hengl, Tomislav; Gräler, Benedikt; Meyer, Hanna; Magney, Troy; Brown, David J.

    2015-04-01

    Dynamic soil data collected using automated sensor networks can facilitate our understanding of soil processes, but highly dimensional data may be difficult to analyze in a manner that incorporates correlation in properties through 3-dimensions and time (3D+T). We demonstrate two approaches to making continuous predictions of dynamic soil properties from fixed point observations. For this analysis, we used the Cook Farm data set, which includes hourly measurements of soil volumetric water content, temperature, and electrical conductivity at 42 points and five depths, collected over five years. We compare performance of two modeling frameworks. In the first framework we used random forest algorithms to fit a 3D+T regression model to make predictions of all three soil variables from 2- and 3-dimensional, temporal, and spatio-temporal covariates. In the second framework we developed a 3D+T kriging model after detrending the observations for depth-dependent seasonal effects. The results show that both models accurately predicted soil temperature, but the kriging model outperformed the regression model according to cross-validation; it explained 37%, 96%, and 16% of the variability in water content, temperature, and electrical conductivity respectively versus 34%, 93%, and 4% explained by the random forest model. The full random forest regression model had high goodness-of-fit for all variables, which was reduced in cross-validation. Temporal model components (i.e. day of the year) explained most of the variability in observations. The seamless predictions of 3D+T data produced from this analysis can assist in understanding soil processes and how they change through a season, under different land management scenarios, and how they relate to other environmental processes.

  9. Developments in Hollow Graphite Fiber Technology

    NASA Technical Reports Server (NTRS)

    Stallcup, Michael; Brantley, Lott W., Jr. (Technical Monitor)

    2002-01-01

    Hollow graphite fibers will be lighter than standard solid graphite fibers and, thus, will save weight in optical components. This program will optimize the processing and properties of hollow carbon fibers developed by MER and to scale-up the processing to produce sufficient fiber for fabricating a large ultra-lightweight mirror for delivery to NASA.

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Program overview of the hollow clay tile wall program

    SciTech Connect

    Not Available

    1992-03-01

    Some of the facilities at the Oak Ridge Y-12 Plant were designed and constructed at a time when either the building codes did not require consideration of earthquake loads or the design requirements were considerably lower than current requirements specified by General Design Criteria, Department of Energy (DOE) Order 6430.lA. Also, some of the buildings were constructed with unreinforced infilled hollow clay tile wails (HCTWs), whose performance in past earthquakes continue to be of concern to designers and to code committees. Martin Marietta Energy Systems Inc. is in a phased program to update the safety documentation for existing facilities known as the Safety Analysis Report Update Program (SARUP). Phase I of SARUP identifies those facilities where natural phenomena (i.e. earthquake, wind/tornado and flood) loading is an initiating or contributing event to accident scenarios with potential human health effects and off-site consequences. Detailed quantitative evaluations are to be performed in Phase III to determine the effects of natural phenomena loadings on such facilities. The HCTW program was developed by the Center for Natural Phenomena Engineering to determine the contribution of HCTWs to the lateral-load-carrying capacity of steel and reinforced concrete frame buildings. The HCRW program consists of laboratory tests of unit tiles, assemblages of tiles, and HCT walls influed in steel frames; in situ tests of a full size wall and portions of walls; and analytical studies directed toward incorporating the test results into analysis methodologies for seismic structural analyses. This report gives an overview of the HC-RW program and presents an approach for applying the HCTW program results to meet DOE requirements for evaluating existing DOE facilities for natural phenomena hazards as defined in DOE 6430.lA. The program supports the Phase II SARUP evaluations for the Y-12 plant.

  20. White paper on the Hollow Clay Tile Wall Program

    SciTech Connect

    Not Available

    1992-03-01

    Some of the facilities at the Oak Ridge Y-12 Plant were designed and constructed at a time when either the building codes did not require consideration of earthquake loads or the design requirements were considerably lower than current requirements specified by General Design Criteria, Department of Energy (DOE) Order 6430.1A. Also, some of these buildings were constructed with unreinforced hollow clay tile walls (HCTWs), whose performance in past earthquakes continue to be of concern to designers and to code committees. Martin Marietta Energy Systems Inc. is conducting a phased program to update the safety documentation for exiting facilities. Phase I of the Safety Analysis Report Update Program (SARUP) identifies those facilities where natural phenomena (i.e. earthquake, wind/tornado and flood) loading is an initiating or contributing event to accident scenarios with potential human health effects. Detailed quantitative evaluations are performed in Phase II for the effects of natural phenomena loadings. The HCIW program was developed to determine the contribution of HCTWs to the lateral-load-carrying capacity of steel and reinforced concrete frame buildings. The HC-IV program consists of laboratory tests of unit tiles, assemblages of tiles, and HCT walls enfilled in steel frames; in situ tests of a full size wall and portions of wails; and analytical studies directed toward incorporating the test results into analysis methodologies for seismic structural analyses. This report examines the underlying basis of the HCTW program. Also, an approach is presented for applying the HCTW program results to meet DOE requirements for evaluating existing DOE facilities for natural phenomena hazards as defined in DOE 6430.1A. The program supports the Phase II SARUP evaluations for the Y-12 Plant.

  1. 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

  2. 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.

  3. Fundamental mechanisms of deuterium retention in lithiated graphite plasma facing surfaces

    NASA Astrophysics Data System (ADS)

    Taylor, Chase N.

    Plasma impurities and undesirable deuterium recycling degrade plasma confinement and impede a sustainable fusion reaction. This occurs by inducing plasma instabilities and reducing plasma temperature. Lithium wall conditioning has been used in fusion devices including TFTR, CDX-U, FTU, TJ-II, MAST and NSTX as a means to reduce plasma impurities and improve deuterium retention, resulting in significant enhancements in plasma performance. These improvements have come via a reduction in deuterium recycling in addition to a reduction in oxygen and carbon impurities. NSTX, with ATJ graphite walls, is the leading fusion device in lithium research. Many previous studies have investigated deuterated lithium, deuterated graphite, and lithiated graphite in order to understand fundamental properties and particular applications. Deuterium irradiation of lithiated graphite studies are few in number and no systematic research has been conducted to determine the fundamental mechanisms by which deuterium is retained in lithiated graphite. This work presents controlled laboratory studies that use X-ray photoelectron spectroscopy (XPS) to identify the fundamental chemical interactions in lithiated graphite. Li-O chemical interactions are observed in the photoelectron energy spectrum at 529.5 eV after thermally depositing lithium onto ATJ graphite. Deuterium retention induces Li-O-D and Li-C-D interactions which are observed at 529.9 eV and 291.2 eV, respectively. Examination of NSTX post-mortem tiles confirms the formation of Li-O-D and Li-C-D chemical interactions and validates the procedures in these experiments. Prior to these findings, deuterium was assumed to bind exclusively with lithium to form stoichiometric LiD. Instead, we find that in a graphite matrix, lithium will always bind with oxygen and carbon (when present) prior to the introduction of deuterium. The deuterium saturation of lithiated graphite is also assessed using XPS and results indicate that saturation occurs

  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. 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.

  6. The poly dA strand of poly dA.poly dT adopts an A-form in solution: a UV resonance Raman study.

    PubMed Central

    Jollès, B; Laigle, A; Chinsky, L; Turpin, P Y

    1985-01-01

    The study by resonance Raman spectroscopy with a 257 nm excitation wave-length of adenine in two single-stranded polynucleotides, poly rA and poly dA, and in three double-stranded polynucleotides, poly dA.poly dT, poly(dA-dT).poly(dA-dT) and poly rA.poly rU, allows one to characterize the A-genus conformation of polynucleotides containing adenine and thymine bases. The characteristic spectrum of the A-form of the adenine strand is observed, except small differences, for poly rA, poly rA.poly rU and poly dA.poly dT. Our results prove that it is the adenine strand which adopts the A-family conformation in poly dA.poly dT. PMID:4000953

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

    PubMed

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

    2011-07-01

    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.

  8. 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

  9. Graphite Oxidation Thermodynamics/Reactions

    SciTech Connect

    Propp, W.A.

    1998-09-01

    The vulnerability of graphite-matrix spent nuclear fuel to oxidation by the ambient atmosphere if the fuel canister is breached was evaluated. Thermochemical and kinetic data over the anticipated range of storage temperatures (200 to 400 C) were used to calculate the times required for a total carbon mass loss of 1 mgcm-2 from a fuel specimen. At 200 C, the time required to produce even this small loss is large, 900,000 yr. However, at 400 C the time required is only 1.9 yr. The rate of oxidation at 200 C is negligible, and the rate even at 400 C is so small as to be of no practical consequence. Therefore, oxidation of the spent nuclear fuel upon a loss of canister integrity is not anticipated to be a concern based upon the results of this study.

  10. 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.

  11. Superconductivity in graphite intercalation compounds

    DOE PAGESBeta

    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 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

  12. 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.

  13. 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.

  14. Numerical methods for analysis of clay tile infills

    SciTech Connect

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

    1993-10-20

    Recent Department of Energy requirements have led to a comprehensive evaluation of the industrial facilities at the Oak Ridge Y-12 Plant. The structures consist of simply connected steel frames infilled with structural clay tile walls. The objective of the evaluation was to determine the stability of the unreinforced infills, and whether they provide the lateral capacity necessary to resist the moderate seismic hazard at the site. Due to lack of information on the behavior of structural clay tile infills, various large-scale tests were performed to investigate the in-plane, out-of-plane and combined in-plane and out-of-plane behavior. The results of these tests are briefly summarized, and the development of analytical guidelines based on these tests is given. Little interaction between in-plane and out-of-plane loads was observed, both in terms of stiffness and strength. Out-of-plane stability can be examined panel by panel based on arching action. Inter-story drift does not appear to present a stability problem for the type of infill construction investigated. In-plane behavior may be adequately modeled with a nonlinear compression strut. A typical building is chosen for an illustrative application. The methodology and results of the seismic analysis are presented for this structure.

  15. Non isothermal drying process optimisation - Drying of clay tiles

    NASA Astrophysics Data System (ADS)

    Vasić, M.; Radojević, Z.

    2015-11-01

    In our previous studies we have developed a model for determination of the variable effective diffusivity and identification of the exact transition points between possible drying mechanisms. The next goal was to develop a drying regime which could in advance characterize the real non isothermal process of drying clay tiles. In order to do this four isothermal experiments were recorded. Temperature and humidity were maintained at 350C / 75%; 450C / 70%; 450C / 60% and 500C / 60%; respectively in each experiment. All experimentally collected data were analyzed and the exact transition points between possible drying mechanisms were detected. Characteristic drying period (time) for each isothermal drying mechanism was also detected. The real, non-isothermal drying process was approximated by 5 segments. In each of these segments approximately isothermal drying condition were maintained. Temperature and humidity of the drying air, in the first four segments, was maintained on the same level as in recorded isothermal experiments while in the fifth segment, it were maintained at 700C / 40%. The duration of the first four segments were calculated from the diagrams Deff - t respectively for each experiment. The clay tile in experiment five was dried without cracking using the proposed non isothermal drying regime.

  16. Size-Topology Correlations and Crystallization in Tilings and Packings

    NASA Astrophysics Data System (ADS)

    Hilgenfeldt, Sascha

    2014-03-01

    Ever since its empirical formulation in 1928, Lewis`s law has intrigued scientists, postulating a linear correlation between the average in-plane area and the number of neighbors in a two-dimensional tiling. Many supporting and dissenting results have been reported in systems as diverse as foams, Voronoi tilings in glass models, and nanocrystals. A strong size-topology correlation is consistently observed, but it is often pronouncedly nonlinear. Recently, a variant of the granocentric model explained numerous cases of nonlinear correlations, but cannot account for the linear version of the law. We revisit Lewis's original work by conducting more extensive experiments on cucumber epidermis tissue. The data confirms the linear law, but also shows that the individual cells have a pronounced anisotropy, not present in systems with nonlinear correlation laws. We demonstrate how the granocentric model can be modified taking into account the cell anisotropy, and how this feature is capable of reproducing the linear Lewis law, as well as other characteristic differences in size-topology statistical quantities. The model should be generally applicable to jammed, plane-filling systems and identifies domain anisotropy as an important ingredient in their statistical description.

  17. 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.

  18. 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.

  19. Emergence of limit-periodic order in tiling models.

    PubMed

    Marcoux, Catherine; Byington, Travis W; Qian, Zongjin; Charbonneau, Patrick; Socolar, Joshua E S

    2014-07-01

    A two-dimensional (2D) lattice model defined on a triangular lattice with nearest- and next-nearest-neighbor interactions based on the Taylor-Socolar monotile is known to have a limit-periodic ground state. The system reaches that state during a slow quench through an infinite sequence of phase transitions. We study the model as a function of the strength of the next-nearest-neighbor interactions and introduce closely related 3D models with only nearest-neighbor interactions that exhibit limit-periodic phases. For models with no next-nearest-neighbor interactions of the Taylor-Socolar type, there is a large degenerate class of ground states, including crystalline patterns and limit-periodic ones, but a slow quench still yields the limit-periodic state. For the Taylor-Socolar lattic model, we present calculations of the diffraction pattern for a particular decoration of the tile that permits exact expressions for the amplitudes and identify domain walls that slow the relaxation times in the ordered phases. For one of the 3D models, we show that the phase transitions are first order, with equilibrium structures that can be more complex than in the 2D case, and we include a proof of aperiodicity for a geometrically simple tile with only nearest-neighbor matching rules. PMID:25122280

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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…

  5. 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.

  6. Grammar Tiles: An Opportunity for Manipulatives in the Language Arts Classroom (Middle Ground).

    ERIC Educational Resources Information Center

    Atlee, Marilyn; Hardin, Linda Friddle

    1995-01-01

    Presents 2 articles concentrating on middle-school teaching: 1 that describes how a teacher, using 12 zip-lock sandwich bags and 300 small ceramic tiles, may create "grammar tiles," a method for teaching the parts of speech; and another that describes several innovative ways in which students have learned to work with language while manipulating…

  7. 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...

  8. 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...

  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. 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

  11. 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.

  12. 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.

  13. Interface porcelain tile/PVA modified mortar: a novel nanostructure approach.

    PubMed

    Mansur, Alexandra Ancelmo Piscitelli; Mansur, Herman Sander

    2009-02-01

    In ceramic tile systems, the overall result of adherence between porcelain tiles and polymer modified mortars could be explained based on the nano-order structure that is developed at the interface. Based on pull-off tests, Scanning Electron Microscopy images, and Small Angle X-ray Scattering experiments a nanostructured approach for interface tile/PVA modified mortar was built. The increase of adhesion between tile and mortar due to poly(vinyl alcohol), PVA, addition can be explained by the formation of a hybrid ceramic-polymer-ceramic interface by hydrogen bonds between PVA hydroxyl groups and silanol from tile surface and water from nanostructured C-S-H gel interlayer.

  14. 2D tritium distribution on tungsten tiles used in JET ITER-like wall project

    NASA Astrophysics Data System (ADS)

    Hatano, Y.; Widdowson, A.; Bekris, N.; Ayres, C.; Baron-Wiechec, A.; Likonen, J.; Koivuranta, S.; Ikonen, J.; Yumizuru, K.

    2015-08-01

    Post-mortem measurements of 2-dimensional tritium (T) distribution using an imaging plate (IP) technique were performed for tungsten (W) divertor tiles (W-coated CFC) used in JET-ITER like wall (ILW) project. The observed T distributions were clearly inhomogeneous, and there were band-like regions with high T concentrations that extended in the toroidal direction on tiles 1, 3, 4 and 6. The concentrations of T in the band-like regions were higher by an order of magnitude than the concentrations in other parts. The inhomogeneous T distributions were explained by non-uniform co-deposition with other elements such as beryllium. The concentrations of T on the outboard vertical tiles (tiles 7 and 8) were low and relatively uniform in comparison with other tiles.

  15. Porosity Detection in Ceramic Armor Tiles via Ultrasonic Time-Of

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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.

  16. 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.

  17. Thermal and flammability characterization of graphite composites

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.

    1986-01-01

    Thermal, mechanical, and flammability properties of graphite composites fabricated with XU71775/H795, a bismaleimide/vinyl-polystyrylpyridine formulation; H795, a bismaleimide; Cycom 6162, a phenolic; and PSP 6022M, a polystyrylpyridine and two types of graphite reinforcement were evaluated and compared with a composite made with an epoxy resin as a matrix. The measured properties included limiting-oxygen index, smoke evolution, thermal degradation products, total-heat release, heat-release rates, mass loss, flame spread, ignition resistance, thermogravimetric analysis, and selected mechanical properties. It was found that the combination of XU71775/H795 with the graphite tape was the optimum design giving the lowest heat release rate.

  18. 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

  19. Structural change of graphite during electron irradiation

    SciTech Connect

    Koike, J. . Dept. of Mechanical Engineering); Pedraza, D.F. )

    1992-01-01

    Highly oriented pyrolytic graphite was irradiated at room temperature with 300-keV electrons. High resolution transmission electron microscopy and electron energy loss spectroscopy were employed to study the structure of electron-irradiated graphite. Results consistently indicated absence of long-range order periodicity in the basal plane, and loose retention of the c-axis periodicity. Structure was modeled based on a mixture of sixfold and non-sixfold atom rings. Formation of non-sixfold atom rings was related to the observed buckling and discontinuity of the original graphite basal plane.

  20. Structural change of graphite during electron irradiation

    SciTech Connect

    Koike, J.; Pedraza, D.F.

    1992-12-31

    Highly oriented pyrolytic graphite was irradiated at room temperature with 300-keV electrons. High resolution transmission electron microscopy and electron energy loss spectroscopy were employed to study the structure of electron-irradiated graphite. Results consistently indicated absence of long-range order periodicity in the basal plane, and loose retention of the c-axis periodicity. Structure was modeled based on a mixture of sixfold and non-sixfold atom rings. Formation of non-sixfold atom rings was related to the observed buckling and discontinuity of the original graphite basal plane.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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).

  6. 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.

  7. Brownian friction coefficient of Kr/graphite.

    NASA Astrophysics Data System (ADS)

    Boutchko, R.

    1998-03-01

    Calculations of the Brownian friction coefficient of fluid Kr/graphite are described. The phonon frequencies and polarization vectors are calculated for a thick graphite slab using the Benedek-Onida bond charge model(G. Benedek and G. Onida, Phys. Rev. B 47), 16471 (1993). The fluctuating forces on the adatom from the substrate are expressed in terms of the graphite fluctuation spectrum. The friction coefficient is expressed in terms of a spectral density to be derived from the slab calculations. The relation of the results to diffusive processes in monolayer fluids(F. Y. Hansen, L. W. Bruch, and H. Taub, Phys. Rev. B 54), 14077 (1996). is discussed.

  8. Hetero-oligonucleotide nanoscale tiles capable of two-dimensional lattice formation as testbeds for a rapid, affordable purification methodology.

    PubMed

    Lukeman, Philip S

    2013-06-21

    New nanoscale hetero-oligonucleotide tiles are assembled from DNA, RNA and morpholino oligos and purified using size exclusion filtration. Homo-oligonucleotide tiles assembled from RP-cartridge processed DNA oligos are purified by nondenaturing gel electrophoresis. These tiles' purity and homogeneity are demonstrated by gel electrophoresis and their incorporation into two-dimensional arrays visualized by AFM. This purification methodology increases throughput and decreases costs for researchers who wish to screen multiple tiles for utilization in structural or analytical studies.

  9. 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.

  10. Contributions of systematic tile drainage to watershed-scale phosphorus transport.

    PubMed

    King, Kevin W; Williams, Mark R; Fausey, Norman R

    2015-03-01

    Phosphorus (P) transport from agricultural fields continues to be a focal point for addressing harmful algal blooms and nuisance algae in freshwater systems throughout the world. In humid, poorly drained regions, attention has turned to P delivery through subsurface tile drainage. However, research on the contributions of tile drainage to watershed-scale P losses is limited. The objective of this study was to evaluate long-term P movement through tile drainage and its manifestation at the watershed outlet. Discharge data and associated P concentrations were collected for 8 yr (2005-2012) from six tile drains and from the watershed outlet of a headwater watershed within the Upper Big Walnut Creek watershed in central Ohio. Results showed that tile drainage accounted for 47% of the discharge, 48% of the dissolved P, and 40% of the total P exported from the watershed. Average annual total P loss from the watershed was 0.98 kg ha, and annual total P loss from the six tile drains was 0.48 kg ha. Phosphorus loads in tile and watershed discharge tended to be greater in the winter, spring, and fall, whereas P concentrations were greatest in the summer. Over the 8-yr study, P transported in tile drains represented <2% of typical application rates in this watershed, but >90% of all measured concentrations exceeded recommended levels (0.03 mg L) for minimizing harmful algal blooms and nuisance algae. Thus, the results of this study show that in systematically tile-drained headwater watersheds, the amount of P delivered to surface waters via tile drains cannot be dismissed. Given the amount of P loss relative to typical application rates, development and implementation of best management practices (BMPs) must jointly consider economic and environmental benefits. Specifically, implementation of BMPs should focus on late fall, winter, and early spring seasons when most P loading occurs.

  11. 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

  12. Tile Drainage Management Influences on Surface-Water and Groundwater Quality following Liquid Manure Application.

    PubMed

    Frey, Steven K; Topp, Ed; Ball, Bonnie R; Edwards, Mark; Gottschall, Natalie; Sunohara, Mark; Zoski, Erin; Lapen, David R

    2013-01-01

    This study investigated the potential for controlled tile drainage (CD) to reduce bacteria and nutrient loading to surface water and groundwater from fall-season liquid manure application (LMA) on four macroporous clay loam plots, of which two had CD and two had free-draining (FD) tiles. Rhodamine WT (RWT) was mixed into the manure and monitored in the tile water and groundwater following LMA. Tile water and groundwater quality were influenced by drainage management. Following LMA on the FD plots, RWT, nutrients, and bacteria moved rapidly via tiles to surface water; at the CD plots, tiles did not flow until the first post-LMA rainfall, so the immediate risk of LMA-induced contamination of surface water was abated. During the 36-d monitoring period, flow-weighted average specific conductance, redox potential, and turbidity, as well as total Kjeldahl N (TKN), total P (TP), NH-N, reactive P, and RWT concentrations, were higher in the CD tile effluent; however, because of lower tile discharge from the CD plots, there was no significant ( ≤ 0.05) difference in surface water nutrient and RWT loading between the CD and FD plots when all tiles were flowing. The TKN, TP, and RWT concentrations in groundwater also tended to be higher at the CD plots. Bacteria behaved differently than nutrients and RWT, with no significant difference in total coliform, , fecal coliform, fecal streptococcus, and concentrations between the CD and FD tile effluent; however, for all but , hourly loading was higher from the FD plots. Results indicate that CD has potential for mitigating bacteria movement to surface water.

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

    PubMed

    King, Kevin W; Williams, Mark R; Fausey, Norman R

    2015-03-01

    Phosphorus (P) transport from agricultural fields continues to be a focal point for addressing harmful algal blooms and nuisance algae in freshwater systems throughout the world. In humid, poorly drained regions, attention has turned to P delivery through subsurface tile drainage. However, research on the contributions of tile drainage to watershed-scale P losses is limited. The objective of this study was to evaluate long-term P movement through tile drainage and its manifestation at the watershed outlet. Discharge data and associated P concentrations were collected for 8 yr (2005-2012) from six tile drains and from the watershed outlet of a headwater watershed within the Upper Big Walnut Creek watershed in central Ohio. Results showed that tile drainage accounted for 47% of the discharge, 48% of the dissolved P, and 40% of the total P exported from the watershed. Average annual total P loss from the watershed was 0.98 kg ha, and annual total P loss from the six tile drains was 0.48 kg ha. Phosphorus loads in tile and watershed discharge tended to be greater in the winter, spring, and fall, whereas P concentrations were greatest in the summer. Over the 8-yr study, P transported in tile drains represented <2% of typical application rates in this watershed, but >90% of all measured concentrations exceeded recommended levels (0.03 mg L) for minimizing harmful algal blooms and nuisance algae. Thus, the results of this study show that in systematically tile-drained headwater watersheds, the amount of P delivered to surface waters via tile drains cannot be dismissed. Given the amount of P loss relative to typical application rates, development and implementation of best management practices (BMPs) must jointly consider economic and environmental benefits. Specifically, implementation of BMPs should focus on late fall, winter, and early spring seasons when most P loading occurs. PMID:26023967

  15. Using stable isotope tracers to assess flow pathways for P transport in tile-drained landscapes

    NASA Astrophysics Data System (ADS)

    Williams, M. R.; King, K.; Ford, W. I., III; Buda, A. R.; Kennedy, C. D.

    2015-12-01

    Throughout the Midwestern US and other poorly drained agricultural regions, phosphorus (P) transport in tile drainage is of increasing environmental concern. Significant P loads are often measured in subsurface drainage water despite the normally high P adsorption capacity of subsoils, which suggest that the high P loadings observed in tile drainage water during storm events are 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. Results showed that event water accounted for between 26 and 69% of total tile discharge from both fields, with tillage substantially reducing the maximum contributions of event water. Following fertilizer application, median DP concentration was significantly greater in the no-tilled fields (1.19 mg/L) compared to the tilled field (0.66 mg/L). Concentrations remained significantly greater in the no-tilled field compared to the tilled field for the five monitored storms (>1 month) after fertilizer application. Both DP and TP concentrations in the no-tilled fields were significantly related to event water contributions to tile discharge, while only TP concentration was significantly related to event water in the tilled field. Collectively, results suggest that macropore flow is an important flow pathway in tile-drained landscapes and that incorporating surface-applied fertilizers has the potential to substantially reduce the risk of P loss from tile

  16. 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.

  17. Effect of long term target changes on the neutron yield from a low intensity (d, t) neutron generator

    NASA Astrophysics Data System (ADS)

    Dalton, A. W.

    1987-12-01

    Experimental and theoretical techniques have been developed to determine the accuracy with which the integrated neutron output from a low-intensity (d, t) neutron source can be measured during a prolonged irradiation. The experiments involved a neutron generator in which a fixed solid titanium-tritium target and an unanalysed beam of deuterium ions was used. The analysis was based on differential and integral measurements of both the deuterium beam current and the energy spectra of the charged particles emitted from the multiple nuclear interactions in the target during beam bombardment. The overlapping signals produced by the latter are interpreted using an iterative analysis developed at the Lucas Heights Laboratories.

  18. Superhydrophilic graphite surfaces and water-dispersible graphite colloids by electrochemical exfoliation

    NASA Astrophysics Data System (ADS)

    Li, Yueh-Feng; Chen, Shih-Ming; Lai, Wei-Hao; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2013-08-01

    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.

  19. Investigation of Ceramic, Graphite, and Chrome-plated Graphite Nozzles on Rocket Engine

    NASA Technical Reports Server (NTRS)

    Kinney, George R; Lidman, William G

    1949-01-01

    The use of ceramic material for rocket nozzles and the effectiveness of preventing oxidation and erosion of graphite nozzles by chrome-plating the internal surface were investigated. A supported ceramic nozzle, cracked by initial operation, was operated a second time without further cracking or damage. Chrome-plating the internal surface of graphite nozzles effectively prevented oxidation and erosion that occurred during operation with unprotected graphite.

  20. 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.

  1. 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.

  2. 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.

  3. Laboratory for Characterization of Irradiated Graphite

    SciTech Connect

    Karen A. Moore

    2010-03-01

    The newly completed Idaho National Laboratory (INL) Carbon Characterization Laboratory (CCL) is located in Labs C19 and C20 of the Idaho National Laboratory Research Center (IRC). The CCL was established under the Next Generation Nuclear Plant (NGNP) Project to support graphite and ceramic composite research and development activities. The research is in support of the Advanced Graphite Creep (AGC) experiment — a major material irradiation experiment within the NGNP Graphite program. The CCL is designed to characterize and test low activated irradiated materials such as high purity graphite, carbon-carbon composites, and silicon-carbide composite materials. The laboratory is fully capable of characterizing material properties for both irradiated and nonirradiated materials.

  4. 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.

  5. 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.

  6. Hydrologic Impacts of Tile Drainage in Iowa: From Field to Catchment Scale

    NASA Astrophysics Data System (ADS)

    Sloan, B.; Basu, N. B.; Mantilla, R.

    2013-12-01

    Agricultural tile drainage is an integral part of Iowa's landscape, with nearly 30% of Iowa's cropland being drained (Schilling & Helmers, 2008). Tile drainage allows for efficient crop production in Iowa's nutrient rich soils by removing excess water from frequently inundated fields through subsurface pipe networks. These tile systems are suspected of altering the hydrologic regime of Iowa, but the extent of the problem remains unknown. Current research has concluded that the impacts of tile drainage on the hydrologic response entail a complex interaction of processes that is dependent upon landscape, climatic, and anthropogenic controls and that the effects of tile drainage vary with watershed scale. The deterministic field-scale model DRAINMOD is used in both a field and catchment scale analysis of the hydrologic impacts of tile drainage in conditions typical to Iowa. The field scale results indicate that soil permeability and rainfall event size are essential in determining the impact of tile drainage. The addition of drainage can decrease flows in less permeable soils and increase flows in more permeable soils because of the alteration to dominant pre-drainage flow mechanisms. However, for very large storm events, the tile has little impact because surface runoff dominates. The field scale DRAINMOD results are then used in conjunction with a simplified routing equation to analyze the impact of tile drains on the Clear Creek Watershed (CCW) in Iowa. According to the results, at the CCW scale (260 km2), tile drainage can reduce the peak flows at the outlet for certain storm events. It was found that adding drained fields to the densest portion of the CCW width function can decrease the peak at the outlet. However, for very large storm events, tiling may have no impact on the outlet hydrograph since all fields will have a similar hydrograph due to the similar surface runoff mechanism. According to the results, tile drainage is capable of reducing peak flows and

  7. 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.

  8. 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)

  9. 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.

  10. 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

  11. Technique for Forming Solid D2 and D-T Layers for Shock Timing Experiments at the National Ignition Facility

    DOE PAGESBeta

    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 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

  12. 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.

  13. 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. PMID:23635160

  14. 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.

  15. 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.

  16. 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

  17. The Tile and General Research Imaging System (TIGRIS)

    SciTech Connect

    Simpson, J.J.; Al-Rawi, L.L.

    1996-01-01

    The Tile and General Research Imaging System (TIGRIS) is a UNIX-based image software system implemented in, and strictly conforming to, UNIX, C/ANSI C, and X11 Window standards. The TIGRIS design and implementation emulates UNIX at the user, application, and system levels. The TIGRIS Application Programmer Interface (API) provides a convenient way to create divers image processing and analysis applications. TIGRIS has been used primarily to support satellite remote sensing, global change research, and operational activities. Numerous applications related to specific remote sensing issues (e.g., cloud detection, noise reduction in AVHRR Channel 3 data, oceanic transport) are included in the application layer. In addition, a number of powerful general purpose imaging applications (e.g., image algebra, morphological operations, textural analysis) are provided which support general image processing, analysis, interactive visualization, and noninteractive image product generation. Use of TIGRIS to accomplish a few complex image analysis tasks is demonstrated.

  18. Automation of Shuttle Tile Inspection - Engineering methodology for Space Station

    NASA Technical Reports Server (NTRS)

    Wiskerchen, M. J.; Mollakarimi, C.

    1987-01-01

    The Space Systems Integration and Operations Research Applications (SIORA) Program was initiated in late 1986 as a cooperative applications research effort between Stanford University, NASA Kennedy Space Center, and Lockheed Space Operations Company. One of the major initial SIORA tasks was the application of automation and robotics technology to all aspects of the Shuttle tile processing and inspection system. This effort has adopted a systems engineering approach consisting of an integrated set of rapid prototyping testbeds in which a government/university/industry team of users, technologists, and engineers test and evaluate new concepts and technologies within the operational world of Shuttle. These integrated testbeds include speech recognition and synthesis, laser imaging inspection systems, distributed Ada programming environments, distributed relational database architectures, distributed computer network architectures, multimedia workbenches, and human factors considerations.

  19. pH-Controlled Assembly of DNA Tiles

    PubMed Central

    2016-01-01

    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. PMID:27631465

  20. Robotic end-effector for rewaterproofing shuttle tiles

    NASA Technical Reports Server (NTRS)

    Manouchehri, Davoud; Hansen, Joseph M.; Wu, Cheng M.; Yamamoto, Brian S.; Graham, Todd

    1992-01-01

    This paper summarizes work by Rockwell International's Space Systems Division's Robotics Group at Downey, California. The work is part of a NASA-led team effort to automate Space Shuttle rewaterproofing in the Orbiter Processing Facility at the Kennedy Space Center and the ferry facility at the Ames-Dryden Flight Research Facility. Rockwell's effort focuses on the rewaterproofing end-effector, whose function is to inject hazardous dimethylethyloxysilane into thousands of ceramic tiles on the underside of the orbiter after each flight. The paper has five sections. First, it presents background on the present manual process. Second, end-effector requirements are presented, including safety and interface control. Third, a design is presented for the five end-effector systems: positioning, delivery, containment, data management, and command and control. Fourth, end-effector testing and integrating to the total system are described. Lastly, future applications for this technology are discussed.